cea-list-ia/ManufactuBERT
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Chang-an Jiang, Kim-leng Poh, and Tze-yun Leong
It is a frequently encountered problem that new knowledge arrived when making decisions in a dynamic world. Usually, domain experts cannot afford enough time and knowledge to effectively assess and combine both qualitative and quantitative information in these models.Existing approaches can solve only one of two tasks instead of both.We propose a four-step algorithm to integrate multiple probabilistic graphic models, which can effectively update existing models with newly acquired models. In this algorithm, the qualitative part of model integration is performed first, followed by the quantitative combination. We illustrate our method with an example of combining three models. We also identify the factors that may influence the complexity of the integrated model. Accordingly, we identify three factors that may influence the complexity of the integrated model. Accordingly, we present three heuristic methods of target variable ordering generation. Such methods show their feasibility through our experiments and are good in different situations. Finally, we provide some comments based on our experiments results. | <urn:uuid:f20540ee-fafb-422d-9d76-a6fc554293b7> | {
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- PASSENGER-STRAND (1) (remove)
- A large-scale chemical modification screen identifies design rules to generate siRNAs with high activity, high stability and low toxicity (2009)
- The use of chemically synthesized short interfering RNAs (siRNAs) is currently the method of choice to manipulate gene expression in mammalian cell culture, yet improvements of siRNA design is expectably required for successful application in vivo. Several studies have aimed at improving siRNA performance through the introduction of chemical modifications but a direct comparison of these results is difficult. We have directly compared the effect of 21 types of chemical modifications on siRNA activity and toxicity in a total of 2160 siRNA duplexes. We demonstrate that siRNA activity is primarily enhanced by favouring the incorporation of the intended antisense strand during RNA-induced silencing complex (RISC) loading by modulation of siRNA thermodynamic asymmetry and engineering of siRNA 3-overhangs. Collectively, our results provide unique insights into the tolerance for chemical modifications and provide a simple guide to successful chemical modification of siRNAs with improved activity, stability and low toxicity. | <urn:uuid:b5654d8e-0f08-4bf6-9a7c-6fd03e5fe0e7> | {
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Matrix-Variate Dirichlet Process Mixture Models
Zhihua Zhang, Guang Dai, Michael Jordan ; JMLR W&CP 9:980-987, 2010.
We are concerned with a multivariate response regression problem where the interest is in considering correlations both across response variates and across response samples. In this paper we develop a new Bayesian nonparametric model for such a setting based on Dirichlet process priors. Building on an additive kernel model, we allow each sample to have its own regression matrix. Although this overcomplete representation could in principle suffer from severe overfitting problems, we are able to provide effective control over the model via a matrix-variate Dirichlet process prior on the regression matrices. Our model is able to share statistical strength among regression matrices due to the clustering property of the Dirichlet process. We make use of a Markov chain Monte Carlo algorithm for inference and prediction. Compared with other Bayesian kernel models, our model has advantages in both computational and statistical efficiency. | <urn:uuid:d459f136-c864-4eb7-a831-92ae8b4a11da> | {
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Year of publication
- 1992 (1) (remove)
- Delbrück scattering in a strong external field (1992)
- We evaluate the Delbrück scattering amplitude to all orders of the interaction with the external field of a nucleus employing nonperturbative electron Green's functions. The results are given analytically in form of a multipole expansion. | <urn:uuid:73eda041-aea7-41ec-bc8b-231413fc8836> | {
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} |
QD Vision`s (www.qdvision.com) Quantum Light™ product platform enables breakthrough performance and significant systems cost savings without the cost/performance trade-offs typical of other materials and lighting technologies. The Quantum Light™ platform exploits the unique light-emitting properties of semiconductor nanocrystals to deliver a new value proposition for LED-based products, including extraordinary color quality, high-power efficiency, manufacturing versatility and design flexibility.
The first products incorporating Quantum Light™ technology are LED lamps and fixtures that deliver savings in energy of up to 80%, best-in-class color quality, and lifetimes in excess of 50,000 hours.
Color, Power, Cost and Design Benefits The Quantum Light™ product platform will deliver unparalleled color and brightness and require significantly less power than current technologies for solid state lighting, flat-panel displays, consumer electronics products, and national security applications. It combines advanced material and device technologies to deliver substantial benefits:
Color: Quantum Light™ products emit pure, finely-tuned colors, enabling better color saturation and color rendering than other technologies.
Power: The Quantum Light™ product platform uses significantly less power than other solutions, making it an attractive option for clean-tech applications, and an optimal choice for consumer electronics applications.
Cost: Quantum dot materials are inherently efficient light emitters, enabling improvements in bills of material and reduced manufacturing complexity for most types of displays and solid-state lighting products. Quantum Light™ technology therefore lowers the overall cost of production in addition to enabling solutions that can dramatically reduce ownership costs by delivering higher performance while using far less power.
Design: The Quantum Light™ product platform opens up new possibilities in the design and manufacture of consumer and industrial products, including the potential for extremely thin displays and compact lighting fixtures. | <urn:uuid:a42f5937-851b-4f9d-a1ce-df87fd5ebb43> | {
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Influence of Ni Catalyst Layer and TiN Diffusion Barrier on Carbon Nanotube Growth Rate
1 Plasmionique Inc., 1650 boul. Lionel Boulet, Varennes, QC, J3X 1S2, Canada
2 Defence Research & Development Canada—Valcartier, 2459 boul. Pie XI Nord, Val-Belair, QC, G3J 1X5, Canada
3 Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON, N6A 5B9, Canada
Nanoscale Research Letters 2010, 5:539-544 doi:10.1007/s11671-010-9544-yPublished: 4 February 2010
Dense, vertically aligned multiwall carbon nanotubes were synthesized on TiN electrode layers for infrared sensing applications. Microwave plasma-enhanced chemical vapor deposition and Ni catalyst were used for the nanotubes synthesis. The resultant nanotubes were characterized by SEM, AFM, and TEM. Since the length of the nanotubes influences sensor characteristics, we study in details the effects of changing Ni and TiN thickness on the physical properties of the nanotubes. In this paper, we report the observation of a threshold Ni thickness of about 4 nm, when the average CNT growth rate switches from an increasing to a decreasing function of increasing Ni thickness, for a process temperature of 700°C. This behavior is likely related to a transition in the growth mode from a predominantly “base growth” to that of a “tip growth.” For Ni layer greater than 9 nm the growth rate, as well as the CNT diameter, variations become insignificant. We have also observed that a TiN barrier layer appears to favor the growth of thinner CNTs compared to a SiO2 layer. | <urn:uuid:ff813192-a2d7-48b7-b222-8942375db1e9> | {
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Noël, Caroline (2009) Plasma polymerisation: study and application. Doctoral thesis, Durham University.
Molecular interactions are often studied using immobilised organic and biological entities at the surface of a substrate. Functionalisation of such surfaces can be achieved via different technologies such as Langmuir-Blodgett films, self-assembled monolayers and spin-coated layers. The main drawback of these methods is the dependence on the substrate, limiting the scope of possible applications. Conversely, plasma polymerisation entails the deposition of thin polymeric films at the surface of a wide variety of substrates. The development of pulsed plasma has opened new paths allowing the high controllability of the functionality and the thickness of the deposited layer. This thesis describes the functionalisation of a surface with pentafluorophenyl ester in a one-step process, reaching higher immobilization yield of bio-molecules than in a multi-step process. Also, the nature of pulsed-plasma polymers provides additional benefits such as irregular surfaces which make functionalities more accessible for subsequent reactions such as enzymatic modification as investigated in the fourth chapter. Finally, the last two chapters of this thesis deal with the occurrence of trapped free radicals within plasma polymers and their ability to induce graft-polymerisation of polymer brushes without prior attachment of initiators at the surface of a substrate. A comparison is drawn between a 'conventional' method using an initiator immobilised on the surface and trapped radicals to induce graft polymerisation. The influence of he nature of the monomer used during plasma polymerisation along with the conditions of deposition are studied with respect to the rate of subsequent graft polymerisation of styrene and the amount of trapped free radicals.
|Item Type:||Thesis (Doctoral)|
|Award:||Doctor of Philosophy|
|Copyright:||Copyright of this thesis is held by the author|
|Deposited On:||08 Sep 2011 18:25| | <urn:uuid:926ef6d8-408c-441d-bd47-66e61b9826a6> | {
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TCP Vegas is analyzed and modified in the congestion avoidance phase by using optimization theory. The optimization approach is to maximize the aggregate utility of all sources subject to the capacity constraints of the network's resources. The congestion avoidance mechanism of sources and the active queue management in bottleneck routers can be interpreted as finding a solution of the optimization problem with constraints by using the first order method. In this method, we discuss several modifications of congestion avoidance in sources and queue management in routers with respect to 1) what the objective function of TCP Vegas should be, 2) how the active queue management should be designed in the framework of the optimization approach.
SICE 2003 Annual Conference (Volume:3 )
Date of Conference: 4-6 Aug. 2003 | <urn:uuid:1c7846b7-acb4-46ca-ac11-ed088ee745b2> | {
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Song, D.P.; Hicks, C. and Earl, C.F.
Product due date assignment for complex assemblies.
International Journal of Production Economics, 76(3),
A method is described to assign product due dates for multistage assemblies with uncertain manufacturing and assembly process times. Earliest start times of operations are specified by a predetermined production plan and processing time distributions for operations are truncated at minimum processing times. The method systematically decomposes the complex product structures of multistage assemblies into two-stage subsystems. Both exact and approximate distributions of completion time for two-stage assemblies are developed. The latter is applied recursively to multistage assemblies to yield an approximate distribution of product completion time. Product due dates are assigned to either minimise earliness and tardiness costs or to meet a service target. This method is applied to examples which use manufacturing and assembly data from a capital goods company. The results are verified by simulation.
Actions (login may be required) | <urn:uuid:8a9996d4-3a4c-42a7-8d6b-479419ced35c> | {
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This paper argues that managing technological knowledge is the last frontier of lean manufacturing. An empirically grounded model of the structure of organizational technological knowledge allows manufacturing managers to determine the true value of lean manufacturing practices over lifecycle of their processes. The approach described in this paper also helps fab managers enhance profitability by choosing appropriate strategies organizational learning and problem-solving for three semiconductor businesses: VLSI, commodity components and specialty parts.
Date of Conference: 16-18 May 2011 | <urn:uuid:517f3a3f-b537-440d-84e6-3b71f4d14277> | {
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On the basis of fuzzy rough data model (FRDM), a method to construct rough neural network is proposed. By adaptive Gaustafason-Kessel (G-K) clustering algorithm, fuzzy partition can be accomplished in input data space. Then based on the search of cluster number, optimal FRDM will be found, and by integrating it with neural network technique, corresponding rough neural network is constructed. The experiment results indicate that rough neural network is superior to traditional Bayesian and learning vector quantization (LVQ) methods, moreover, rough neural network has more powerful synthetic decision-making ability than single FRDM model.
Date of Conference: July 30 2007-Aug. 1 2007 | <urn:uuid:9cd7d441-09b3-464d-83ae-2f19ce3fed50> | {
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Skip to Main Content
The implementation of multi-channel assignment policies can improve a mobile's network performance by increasing the user throughput and reducing transmission delays. However, to define efficient distribution policies, the varying service demands and the search for user QoS fairness should be considered under multimedia traffic scenarios. In this context, this paper proposes and evaluates novel bankruptcy and utility-based multi-channel distribution schemes aimed at maximising the resource's efficiency and guaranteeing user QoS fairness.
Date of Conference: 17-19 Oct. 2007 | <urn:uuid:c62cdbb7-5c74-42d6-a729-f4d4ac520303> | {
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|Compositional Variation Within Hybrid Nanostructures|
The inherently high surface area of bimetallic nanoparticles makes them especially attractive materials for heterogeneous catalysis. The ability to selectively grow these and other types of nanoparticles on a desired surface is ideal for the fabrication of higher-order nanoscale architectures. However, the growth mechanism for bimetallic nanoparticles on a surface is expected to be quite different than that for free particles in solution. The altered growth process can lead to modulations in stoichiometry, elemental homogeneity, and surface structure, all of which can profoundly affect the catalytic or magnetic properties of the bimetallic nanoparticles. Now, researchers have experimentally observed these subtle structural differences through x-ray absorption spectroscopic studies at ALS Beamline 10.3.2. The results illustrate how directed nanoparticle growth on specific surfaces can lead to hybrid nanomaterials with a structurally different bimetallic component than its unhybridized counterpart.
Platinum-based bimetallic alloys (such as PtNi, PtCo, PtRu, etc.) have been studied in the bulk form for some time and have been found to exhibit vastly different properties than their individual constituent metals. This is particularly true in catalysis, where Pt-based bimetallic alloys have shown enhanced oxygen reduction activity or accelerated rates of alkene hydrogenation. The catalytic activity of these materials is dependent on the surface structure, and although bimetallic materials are rather well understood in the bulk form, the picture becomes less clear when these materials reach nanoscale dimensions.
Additionally, the ability to directly integrate a metallic nanoparticle with a semiconductor structure is highly desirable. The formation of such hierarchical hybrid nanostructures can allow for new properties and applications that are not available with just the individual components. However, until recently, it was unclear what effect surface-directed nanoparticle growth would have on the structure of a bimetallic nanoparticle, particularly on its surface composition.
Using a novel, recently developed synthesis technique, the researchers fabricated hybrid nanostructures consisting of cadmium sulfide (CdS) nanorods with PtCo nanoparticles grown selectively on the nanorod tips. The structure of these hybrid nanomaterials was compared to free-standing PtCo nanoparticles synthesized by conventional solution-phase methods, using a combination of x-ray absorption near-edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) spectroscopies at the Pt L3- and Co K-edges and x-ray diffraction measurements. Because x-ray absorption spectroscopy is element specific, changes in the local environment of both the Pt and Co could be examined independently. It was found that, while the environment of the Pt atoms was consistent in both the hybrid nanostructures and the free-standing particles, there was considerable variance in the Co environment between the two forms. XANES and EXAFS measurements revealed the existence of a thin amorphous cobalt oxide (CoO) phase in the hybrid nanostructures that was absent in the free-standing particles.
The data suggest that the formation of the new CoO phase is driven by the expulsion of Co to the surface of the growing bimetallic nanoparticle on the tip of the CdS nanorod. This is a consequence of the different growth process that occurs on the nanorod tips as opposed to free nanoparticle growth in solution. The Co-rich surface could then be oxidized post-synthesis, yielding the CoO surface. In spite of the new surface structure occurring in these hybrids, it was found that some properties, such as PtCo superparamagnetism, were preserved. However, it remains to be seen how the catalytic properties will be affected by nanoparticle hybridization. A detailed understanding of the structure of complex nanosystems will enhance our ability to create hybrid materials that can be precisely tailored for desired applications.
Research conducted by B.D. Yuhas (University of California, Berkeley), S.E. Habas and T. Mokari (Berkeley Lab), and S.C. Fakra (ALS).
Research funding: U.S. Department of Energy (DOE), Office of Basic Energy Sciences (BES). Operation of the ALS is supported by DOE BES.
Publication about this research: B.D. Yuhas, S.E. Habas, S.C. Fakra, and T. Mokari, "Probing compositional variation within hybrid nanostructures," ACS Nano 3, 3369 (2009).
ALS Science Highlight #214 | <urn:uuid:37cd14ad-7612-4362-8e69-90908856be22> | {
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Hung Bui, Mabry Tyson, Neil Yorke-Smith
The Simple Temporal Network (STN) is a widely used framework for reasoning about quantitative temporal constraints over variables with continuous or discrete domains. Determining consistency and deriving the minimal network are traditionally achieved by graph algorithms (e.g., Floyd-Warshall, Johnson) or by iteration of narrowing operators (e.g., $\triangle$STP). However, none of these existing methods exploit effectively the tree-decomposition structure of the constraint graph of an STN. Methods based on variable elimination (e.g., adaptive consistency) can exploit this structure, but have not been applied to STNs, in part because it is unclear how to efficiently pass the `messages' over a set of continuous domains. We first show that for an STN, these messages can be represented compactly as sub-STNs. We then present an efficient message passing scheme for computing the minimal constraints of an STN. Analysis of the new algorithm, Prop-STP, brings formal explanation of the performance of the existing STN solvers $\triangle$STP and SR-PC. Preliminary empirical results validate the efficiency of Prop-STP in cases where the constraint network is known to have small tree-width, such as those that arise in Hierarchical Task Network planning problems.
Subjects: 3.6 Temporal Reasoning; 15.2 Constraint Satisfaction
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FROM MICROSTRUCTURE AND REACTIVITY OF SOLID CARBONS TO FORMATION AND DEPOSITION MECHANISMS
Laboratory for Hydrocarbon Process Chemistry, The Energy Institute
Department of Energy and Geo-Environmental Engineering
The Pennsylvania State University
University Park, PA 16802
Monday, June 7, 1999 3:30 pm
Ben Bandy Conference Center
Center for Applied Energy Research
In three basic allotpropic forms and different degrees of microcrystalline aggregation, solid carbons cross over a wide range of materials with a fascinating diversity in properties and applications - e.g., from graphite to diamond, from carbon fiber to glassy carbon, from carbon black to activated carbon, and from fullerenes to meso carbon microbeads. Solid carbons, or carbonaceous solids, can also constitute many undesirable deposits encountered in petroleum refining and petrochemical processes, and in operation of combustion engines. A good understanding of carbon formation and deposition mechanisms is essential for controlling the production of desirable or undesirable solid carbons. Microscopic examination and characterization of solid carbons in conjunction with reactivity measurements offer important insigths into carbon formation and deposition mechanisms.
At different levels of resolution, from optical microscopy (micrometer scale) to atomic force microscopy (nanometer scale), including SEM and TEM (micrometer-nanometer scale), microscopic examination of solid carbons provides information on:
- structural isotropy/anisotropy of samples
- catalytic/non-catalytic formation
- phase transformations
- possible precursors and reactions
- reaction or deposition conditions
Three different examples, i) characterization of needle coke texture (carbonaceous mesophase formation), ii) solid deposition from heated jet fuels, and iii) undesired globular coke formation in carbon black production, will be discussed to illustrate the use of different microscopic techniques to elucidate carbon formation and deposition mechanisms. Complementary to microscopic characterization, a temperature programmed oxidation (TPO) method was used to determine the reactivity of solid carbon deposits produced from jet fuels heated on different metal surfaces. | <urn:uuid:8104984b-0fa2-417c-b8cc-9fa9209b68f9> | {
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Pinkerton, A. J. and Li, L. (2004) The behaviour of water- and gas-atomised tool steel powders in coaxial laser freeform fabrication. Thin Solid Films, 453-45 (2). pp. 600-605. ISSN 0040-6090Full text not available from this repository.
Recent work has shown that using a lower-cost water-atomised stainless steel powder for multiple layer laser deposition is functionally possible, and can produce parts with final properties equivalent to, or in some respects better than, gas-atormsed powder. Before the feasibility of using water-atomised powders in growing fields such as rapid tooling can be determined, it is essential that the behaviour of more appropriate materials be investigated. This paper reports work using a CO, laser and coaxial powder feed head to compare the characteristics of water- and gas-atomised H13 tool steel during the deposition process. The dimensions and geometries of the deposited tracks, and the final material microstructures are examined, and significant differences arising from the type of atomisation method are revealed. Possible explanations for the observed phenomena are discussed. (C) 2003 Elsevier B.V All rights reserved.
|Journal or Publication Title:||Thin Solid Films|
|Subjects:||T Technology > TA Engineering (General). Civil engineering (General)|
|Departments:||Faculty of Science and Technology > Engineering|
|Deposited On:||19 Nov 2012 12:08|
|Last Modified:||19 Nov 2012 12:08|
Actions (login required) | <urn:uuid:7d86b152-9af2-4222-b6a8-c00e9d7d729a> | {
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The increasing presence of distributed energy resources, information, and intelligence in the electricity infrastructure increases the possibilities for larger economic efficiency of power systems. This work shows the possible cost advantages of applying a model predictive control (MPC) strategy to residential energy systems. MPC can take future information on energy demand and prices into account and might lead to lower energy costs for end consumers. The main objective in this paper is to illustrate the potential for operational cost savings when adopting MPC in the local control of residential energy systems, thereby mainly focusing on micro-combined heat and power (micro-CHP) systems. We conclude that the pricing regime of household energy has a large influence on potential cost savings.
Date of Conference: 25-27 June 2008 | <urn:uuid:bbaa8ae5-6261-41ea-ab98-6501f2819891> | {
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- Stochastische Optimierung (1) (remove)
- The Integrated Size and Price Optimization problem (2012)
- We present the Integrated Size and Price Optimization Problem (ISPO) for a fashion discounter with many branches. Based on a two-stage stochastic programming model with recourse, we develop an exact algorithm and a production-compliant heuristic that produces small optimality gaps. In a field study we show that a distribution of supply over branches and sizes based on ISPO solutions is significantly better than a one-stage optimization of the distribution ignoring the possibility of optimal pricing. | <urn:uuid:557a0c49-a35d-4b3c-80c2-b5affd7b2aba> | {
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} |
Unsupervised adaptation of brain machine interface decoders
The performance of neural decoders can degrade over time due to nonstationarities in the relationship between neuronal activity and behavior. In this case, brain-machine interfaces (BMI) require adaptation of their decoders to maintain high performance across time. One way to achieve this is by use of periodical calibration phases, during which the BMI system (or an external human demonstrator) instructs the user to perform certain movements or behaviors. This approach has two disadvantages: (i) calibration phases interrupt the autonomous operation of the BMI and (ii) between two calibration phases the BMI performance might not be stable but continuously decrease. A better alternative would be that the BMI decoder is able to continuously adapt in an unsupervised manner during autonomous BMI operation, i.e. without knowing the movement intentions of the user. In the present article, we present an efficient method for such unsupervised training of BMI systems for continuous movement control. The proposed method utilizes a cost function derived from neuronal recordings, which guides a learning algorithm to evaluate the decoding parameters. We verify the performance of our adaptive method by simulating a BMI user with an optimal feedback control model and its interaction with our adaptive BMI decoder. The simulation results show that the cost function and the algorithm yield fast and precise trajectories towards targets at random orientations on a 2-dimensional computer screen. For initially unknown and non-stationary tuning parameters, our unsupervised method is still able to generate precise trajectories and to keep its performance stable in the long term. The algorithm can optionally work also with neuronal error signals instead or in conjunction with the proposed unsupervised adaptation. | <urn:uuid:0f33f689-5b4f-4fc9-8ac6-e06166642c6e> | {
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Bag In Bag Out
The DoverPac® Bag In/Bag Out (BIBO) system is a family of contained transfer designs for multiple processes. The primary components for this validated operation consist of multiple groove canisters, docking interface hardware, and softgoods in either continuous liner form or discreet liners.
This system can be applied to any rigid isolator. The use of multiple size canisters allows a broad range of needs to be met, systems can be retrofit to existing assets, and the BIBO system requires a low capital outlay. | <urn:uuid:6220ae52-8382-42b7-870e-f06a0f56b13f> | {
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We propose a new scheme for measuring the quantum efficiency of a single-photon detection apparatus by using polarization-entangled states. The scheme consists of measuring the polarization of a member of a polarization-entangled pair after a 90° polarization rotation conditional on the detection of the correlated photon after polarization selection. We present experimental results obtained with this scheme compared with traditional biphoton calibration. Our results show the interesting potentiality of the suggested scheme.
© 2005 Optical Society of America
Giorgio Brida, Marco Genovese, Marco Gramegna, Maria Luisa Rastello, Maria Chekhova, and Leonid Krivitsky, "Single-photon detector calibration by means of conditional polarization rotation," J. Opt. Soc. Am. B 22, 488-492 (2005) | <urn:uuid:e99fc5d1-b347-4e40-8e0f-8b073b874280> | {
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The future emergence of high performance, low-cost microwave systems requires the development of well-suited technological solutions. A simple one is based on the use of a very common foam material, in combination with, on one hand, accurate 3D modeling techniques and, on the other hand, suitable metallization solutions, resulting in cost-effective high volume production abilities. By applying this foam technology, a wide range of microwave engineering issues can be successfully solved, both at centimeter-wave and millimeter-wave frequency bands. In this paper, the basics of the metallized 3D foam technology will be first described. Then, a primary experimental validation of this technology will be demonstrated by the fabrication of a few conventional devices, integrated in planar or wave-guide technologies. Finally, several added value microwave structures will be presented to illustrate the high flexibility and the multiple advantages offered by this integration approach, for a wide range of applications (at frequency up to 80 GHz).
Microwaves, Radar and Wireless Communications, 2004. MIKON-2004. 15th International Conference on (Volume:2 )
Date of Conference: 17-19 May 2004 | <urn:uuid:e54ba9d0-56ac-44aa-8838-5f03783e83bb> | {
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CMOS implementation of Physically Unclonable Functions (PUFs) facilitates a number of applications ranging from digital rights management, device authentication, counterfeit detection/prevention and cryptographic key generation. Key expectations from such PUF circuits are high (i) uniqueness and (ii) reliability. Uniqueness refers to differentiated responses over challenge-response pairs. Reliability demands unvarying responses under varying environmental conditions such as temperature, supply voltage and noise. This paper describes two methods for achieving the above goals in a ring oscillator based PUF. The first method exploits the negative temperature resistance property of n+ and p+ polysilicon placed as source feedback resistors to de-sensitize ring oscillators to temperature variations. The second method uses an optimized supply voltage (V'DD) to reduce the temperature sensitivity of delay based ring oscillator PUFs. We report an improvement in reliability of 16% by combining these methods. Further, we propose a temperature-invariant ring oscillator PUF architecture based on Serial-Input Serial-Output (SISO) topology. In the proposed design, the relative phase difference between two ring oscillators is translated to a digital response bit. We show that this phase difference based response generation is superior to frequency based response generation in terms of area and power.
Date of Conference: 19-21 Aug. 2012 | <urn:uuid:09a7e95f-2da0-4629-94ae-f1a0639c5d1f> | {
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Carbonaceous microspheres adsorbents prepared from the carbonisation process of glucose during hydrothermal treatment have been studied for Cr (VI) and phenol removal from aqueous solutions. Carbonaceous microspheres were characterised by scanning electron microscopy, energy-dispersive X-ray analysis and Fourier transform infrared spectroscopies. It was found that there were abundant oxygen-containing functional groups on the surface of the carbonaceous microspheres. The equilibrium data of the adsorption and the effect of pH, initial concentration of pollutant and temperature of solution on the adsorption of Cr (VI) and phenol by carbonaceous microspheres were studied. The carbonaceous microspheres exhibited excellent adsorption capacity for Cr (VI) and phenol.
Date of Publication: June 2012 | <urn:uuid:aa87d157-39d5-4461-bab7-d207de48f815> | {
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Atomistic simulations of crack nucleation and intergranular fracture in bulk nc Ni
We report large scale molecular dynamics simulations of dynamic cyclic uniaxial tensile deformation of pure, fully dense nanocrystalline Ni, to reveal the crack initiation, and consequently intergranular fracture is the result of coalescence of nanovoids by breaking atomic bonds at grain boundaries and triple junctions. The results indicate that the brittle fracture behavior accounts for the transition from plastic deformation governed by dislocation to one that is grain-boundary dominant when the grain size reduces to the nanoscale. The grain-boundary mediated plasticity is also manifested by the new grain formation and growth induced by stress-assisted grain-boundary diffusion observed in this work. This work illustrates that grain-boundary decohesion is one of the fundamental deformation mechanisms in nanocrystalline Ni.
The new paper is published on Phys. Rev. B, 76, 024113 (2007). | <urn:uuid:69ae2405-f9b8-4b58-9f73-dc371a83525c> | {
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Date of this Version
We address the problem of object detection and segmentation using global holistic properties of object shape. Global shape representations are highly susceptible to clutter inevitably present in realistic images, and can be applied robustly only using a precise segmentation of the object. To this end, we propose a figure/ground segmentation method for extraction of image regions that resemble the global properties of a model boundary structure and are perceptually salient. Our shape representation, called the chordiogram, is based on geometric relationships of object boundary edges, while the perceptual saliency cues we use favor coherent regions distinct from the background. We formulate the segmentation problem as an integer quadratic program and use a semdefinite programming relaxation to solve it. Obtained solutions provide the segmentation of an object as well as a detection score used for object recognition. Our single-step approach achieves state-of-the-art performance on several object detection and segmentation benchmarks.
Date Posted: 16 July 2012 | <urn:uuid:b62f8b9a-4aef-4af2-92ef-67e00bb4f452> | {
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Research Interests: Micro/Nanoscale Heat Transfer, Energy Conversions, PowerMEMS
QES: Micro LHP Cooler - Coherent Porous Silicon Wick for High Heat Flux and Capillary Pumping [BPN670]
The main goal of this project is to develop a new technique to fabricate the coherent porous silicon (CPS) wick and integrate it into the micro loop heat pipe (micro-LHP). Another goal is to optimize the pore size, pitch, porosity and wick thickness to maximize the heat flux and capillary pressure in the device. Through control of pore size, the flow resistance of the micro-LHP will be defined. Finally, the novel design of the CPS wick will significantly increase the efficiency of micro-LHP while preventing the severe problems such as bubble formation, liquid-vapor interface oscillation, and wick dry out. The micro-LHP is a two phase thermal ground plane device for chip-level, integrated cooling. This system draws significant heat flux from electronics when the operating fluid changes to the vapor phase. The porous wick, a key component of the micro-LHP, is located between evaporator and reservoir and it serves as the engine which achieves continuous fluid circulation. It feeds coolant to the evaporator surface, determines the capillary pumping capability of the overall micro-LHP system and serves as thermal barrier between the coolant channels and evaporator chamber. The traditional sponge-like porous wicks have a randomly distributed pore size and irregular flow path. On the contrary, three-dimensional porous structures made via ion-track etching, photolithography, and replica molding have complex fabrication process and restrictions on the device design. | <urn:uuid:a66b931d-d482-4f69-a233-8e4db6a8e3e1> | {
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US 6993222 B2
A method for producing aperiodic gratings and waveguides with aperiodic gratings uses a simulated annealing process that starts with a random configuration of grating elements and iteratively computes a spectral response from a Fourier transform of the configuration of grating elements obtained in successive iterations. A cost function is computed as a convergence criterion. The aperiodic grating can be used, for example, as a filter in WDM applications.
1. A method for creating an optical filter having aperiodically configured filter elements, comprising:
selecting initial characteristic attributes for the filter elements based upon a random seed;
generating an initial configuration of the filter elements having the initial characteristic attributes;
defining a cost function representing a goodness of fit between a desired spectral response and a computed spectral response of the optical filter;
using a simulated annealing process to iteratively compute the cost function by modifying at least one characteristic attribute of at least one filter element; and
if the iteratively computed cost function is less than a predetermined cost function, selecting the configuration of the filter elements that corresponds to the iteratively computed cost function as a desired configuration of the filter elements to provide the desired spectral response.
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12. A method for producing an optical waveguide with at least one desired optical transmission characteristic, comprising:
selecting initial characteristic attributes for aperiodically configured grating elements based upon a random seed;
generating an initial configuration of the grating elements having the initial characteristic attributes;
defining a cost function representing a goodness of fit between a desired spectral response and a computed spectral response of the optical waveguide;
using a simulated annealing process to iteratively compute the cost function by modifying at least one characteristic attribute of at least one grating element;
if the iteratively computed cost function is less than a predetermined cost function, selecting the configuration of the grating elements that corresponds to the iteratively computed cost function as a desired configuration of the grating elements to provide the desired spectral response; and
forming an aperiodic grating corresponding to the desired configuration of the grating elements in or on the optical waveguide so that the optical waveguide has the at least one desired optical transmission characteristic.
13. The method of
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This application is a continuation-in-part of U.S. patent application Ser. No. 09/914,944, filed Nov. 25, 2003, which is a national phase application of PCT/GB00/00768, filed Mar. 3, 2000, and claiming priority to British application 9905196.3, filed Mar. 3, 1999, the contents of which are incorporated herein by reference in their entirety.
The invention is directed to an optical aperiodic grating and filter structure producing multiple pass bands in either transmission or reflection. The grating/filter structure is designed by an efficient simulated annealing algorithm covering a large search space.
Tunable multi-wavelength optical reflectors are important for a number of applications in optical telecommunications and signal processing including multiple channel optical telecommunications networks using wavelength division multiplexing (WDM). Such networks can provide advanced features, such as wavelength routing, wavelength switching and wavelength conversion, adding and dropping of channels and wavelength manipulation. Filters, such as comb filters and passband filters, are required to exclude spurious signals and to stabilize the different wavelengths. Generally such networks include optical amplifiers, such as Er-doped fiber amplifiers, with an overall bandwidth of approximately 35 nm across the ITU C-band and with a center-to-center spacing between adjacent wavelengths between 100 GHz for WDM and 25 GHz for dense WDM (DWDM).
Simple passband filters that reflect one particular wavelength are employed as cavity mirrors located at the front and rear end of the gain region in distributed Bragg reflector (DBR) lasers. These gratings tend to have a single grating period. A small degree of wavelength-tunability can be achieved by incorporating chirped gratings. However, the tuning range is in the order of 10 nm which is insufficient for optical WDM communication systems.
U.S. Pat. No. 5,325,392 discloses a grating with multiple sequentially arranged chirped regions and a wide tuning range in excess of 100 nm. The spacing between the reflectivity maxima is fixed and corresponds to the length of the repeating units. The laser can be tuned over the entire bandwidth of 45 nm by applying independently controlled currents (charge injection) to the distributed reflector region(s) and a built-in phase-adjustment region.
Conventional DBR laser grating designs typically employ deterministic gratings having a well-defined grating period which is smaller than the length of the grating, and other characteristic feature sizes, which limit their versatility. Conversely, aperiodic grating structures are defined as having repeating units with a length that exceeds the length of the grating. Aperiodic gratings have the advantage over periodic gratings that their spectral response can theoretically be selected to have any shape and form useful for the application. Several methods have been proposed to produce aperiodic grating structures, in particular for optical applications.
U.S. Pat. No. 6,141,370 discloses a grating including an array of gratings that are superimposed in an analog manner, and then subjected to a binary digitization. The process arranges grating segments of equal length and varies coefficients aj of a weighted sum of sinusoidal functions until a fit with the desired reflection peaks is obtained. The reference does not disclose how the process can be optimized.
U.S. Pat. No. 5,942,956 discloses a method for designing mode control and converter devices with an aperiodic grating. The aperiodic grating can have features of arbitrary size and arbitrary refractive index contrast. The disclosed method maximizes the power scattered into a specified mode at the output and the method is sufficiently efficient for the design of small numbers (typically tens) of high-contrast grating features. The method, however, becomes inefficient for gratings having a greater number of elements and lower contrast, as is the case for Group III-V semiconductor lasers where the refractive index contrast is typically Δn˜8×10−3 or less. A high-performance comb filter, for example, in InP may require 1,000 or more grating features which could make the scattering matrix approach difficult to manage.
U.S. Pat. No. 5,666,224 discloses a method for fabricating a non-periodic optical grating with a limited number of predefined grating lines and a limited number of predefined grating line features to keep the calculation of the matrix products of the scattering matrix manageable. The method is based on the calculation of a scattering matrix for each predefined grating line pattern or subsequence, with the scattering matrices for consecutive pairs then calculated by forming the product of the scattering matrices of the subsequences. The required pre-selection of the grating line patterns imposes limitations on the attainable spectral response of the grating.
It would therefore be desirable to develop a method for designing and producing an optical filter or grating structure that obviates the limitations of the prior art by providing grating structures with arbitrary feature sizes governed by their manufacturability, and with a predetermined spectral response, such as, for example, a comb filter with reflection maxima located at predetermined wavelengths and having predetermined relative amplitudes.
The described method according to the invention computes a spectral response of an arbitrarily selected initial grating structure (which can be subsequently refined based on experience) and matches the computed response to a predetermined spectral response. A predetermined spectral response is to be understood as a response where the intensity of individual spectral features, for example the reflectivity of individual reflection maxima of a grating, is selected to provide a desired or optimum response of a device, such as a DBR laser. The method uses a simulated-annealing algorithm to find an acceptable minimum solution after starting from a random seed.
According to one aspect of the invention, a method for creating an optical filter having aperiodically configured filter elements includes selecting initial characteristic attributes for the filter elements based upon a random seed, and generating an initial configuration of the filter elements having the characteristic attributes. A cost function is defined that represents a goodness of fit between a desired spectral response and a computed spectral response of the optical filter. The cost function is iteratively computed using a simulated annealing process by modifying at least one characteristic attribute of at least one filter element. If the iteratively computed cost function is less than a predetermined cost function, the configuration of the filter elements is selected as a desired configuration of the filter elements that corresponds to the iteratively computed cost function, thereby providing the desired spectral response.
According to another aspect of the invention, a method for producing an optical waveguide with a desired optical transmission characteristic includes defining a plurality of grating elements, wherein the grating elements represent an aperiodic grating, and selecting initial characteristic attributes for the grating elements based upon a random seed. An initial configuration of the grating elements having the characteristic attributes is generated, and a cost function representing a goodness of fit between a desired spectral response and a computed spectral response of the optical waveguide is defined. The cost function is iteratively computed using a simulated annealing process by modifying at least one characteristic attribute of at least one grating element. If the iteratively computed cost function is less than a predetermined cost function, the configuration of the grating elements that corresponds to the iteratively computed cost function is selected as a desired optimal configuration of the grating elements, thereby providing the desired spectral response. The aperiodic grating corresponding to the optimal configuration of the grating elements is then formed in or on the optical waveguide.
The aperiodic filter/grating can be designed to yield a specified comb of reflection peaks, with both the wavelength position and the relative amplitude of each peak being selectable. Embodiments of the invention may include one or more of the following features. The characteristic attribute may be a physical dimension of a grating/filter element, such as a physical dimension, which can include the width and/or height and/or index of refraction. The characteristic attribute may also be a spacing between the elements.
The simulated annealing process may include Fourier-transforming the characteristic attributes of the grating/filter elements. The grating/filter may have a fixed or variable length that can be changed by the iterative process. The total number of grating/filter elements can also be fixed or variable. The desired response can be selected to conform to the transmission peaks of the ITU grid or to compensate for a gain of a laser or amplifier.
Further features and advantages of the present invention will be apparent from the following description of preferred embodiments and from the claims.
The following figures depict certain illustrative embodiments of the invention in which like reference numerals refer to like elements. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
The method described herein is directed, inter alia, to an efficient algorithm for the design of aperiodic grating structures with a predetermined spectral response, such as a comb filter for applications as mirrors in optical waveguides and in DFB and DBR lasers. The structures described herein can be fabricated, for example, by electron-beam lithography and/or or photolithography using, for example, electron-beam-written masks.
The aperiodic grating for a device can be designed by starting with a simulated grating having grating elements, i.e., the “contrast” elements, with initial positions along the waveguide defined by a predetermined distribution of elements or by a random distribution generated, for example, by a random seed value. Several constraints may be applied to the grating elements, such as a minimum manufacturable feature size, a desired maximum number of grating elements, etc. The grating lines represent a filter that has multiple transmission passbands of prescribed relative amplitude at the desired wavelengths and substantially stop-bands over other wavelengths within the range of intended device operation on both sides of the desired lasing wavelength.
Simulated annealing is a process which mimics actual annealing of a material by heat treatment. The material is hereby heated up and then slowly cooled down. Previously displaced atoms will then move into their respective equilibrium positions, and dislocations and defects will be largely eliminated.
In simulated annealing, a cost-function takes the place of the potential energy of an atom. The aim of the process is to locate a global minimum in cost space, by randomly “hopping” solutions around (a “hot” system) and then gradually “cooling” the system, thereby reducing the size of the random hops. If the cooling rate is chosen correctly, the solution will hop into the global minimum while the system is hot and be kept there as the system cools.
Referring back to
A cost function C0 is calculated over the spectral range of interest, step 210. As can be seen, the cost function C0 will decrease when the fit between the target filtering function and the calculated filtering function (FT of the real space grating structure) improves. To test if the cost function can be lowered, the index i is increased by 1, step 212, and a characteristic feature of a randomly selected element in the grating structure H0(x) is modified to produce a new grating, H1(x), step 214. The characteristic feature can be a refractive index of an element, a width and/or height of an element, and/or a spacing between elements or groups of elements. In step 216, the FT of the modified real space grating Hi(x) is calculated, yielding a new filtering function hi(λ)=FT[Hi(x)]. A new cost function Ci is calculated, step 218, and compared with the cost function Ci−1 for the previous grating structure, i.e. initially with C0 for the initial grating H0(x). If it is determined in step 220 that the new cost function Ci is lower than the cost function Ci−1, then the new grating is accepted as an improved structure and used as a basis for subsequent iterations, step 222. If the maximum number of iterations N has not been reached, as determined in step 224, then the index i is incremented by 1, step 212, and the process returns to step 214.
Conversely, if it is determined in step 220 that the new cost function Ci is ≧Ci−1, then a random number R between 0 and 1 is computed, step 226, and it is checked in step 228 if exp(−|Ci-Ci−1|/T)>R, in which case the new grating is accepted and the process 200 returns to step 222. However, if the difference between Ci and Ci−1 is such that exp(−|Ci-Ci−1|/T)≦R, then the new grating Hi(x) is rejected and the element or feature previously changed in step 214 is returned to its previous state and the process returns to step 214 via the steps 224 and 212 described above.
If the limit N for the number of iterations has been reached, as determined in step 224, the process 200 checks in step 232 if the Fourier transform hN(λ)=FT [HN(X)] of the grating HN(x) is sufficiently close to the target function T(λ), for example, by computing the cost function CN, and should therefore be accepted as an “optimized” structure, step 234. Those skilled in the art will, of course, appreciate that this “optimized” structure may be a locally, but not necessarily a globally optimized structure, which is mathematically difficult to obtain unless the entire search space is investigated.
If it is determined in step 232 that hN(λ) is not sufficiently close to the target function T(λ), then the annealing temperature T is multiplied by a predetermined factor α<1, i.e., the system is “cooled down”, step 236, and the loop counter i is set again to zero, step 238. The process 200 then returns to step 214 for another random grating change.
The cooling rate α is typically kept constant throughout the annealing process. If hi(λ) does not change after executing additional loops, the process is stopped (not shown) as this may be a sign that the temperature is too low for further changes.
Constraints may be imposed on the grating feature parameters by practical limitations of the fabrication process which can be easily incorporated in the design model. For example, certain dimensions of the grating elements and spacing between the grating elements may be dictated by the feature sizes achievable with e-beam lithography, photolithography and/or focused ion beam milling. Additionally, the grating lines can also have different shapes, as long as these shapes can be adequately and efficiently modeled and manufactured, including but not limited to V-shaped features and cylindrical ‘holes’.
One exemplary cost functions useful for the simulated annealing process is Cn=Σ(T(λi)−hi(λi))2, wherein the index n indicates the index of the iteration and the summation is performed, for example, over the wavelengths λi of interest of the spectral response curve. As discussed below, the selected exponent of 2 is exemplary only and other exponents, such as 4, can be used instead to measure convergence of the process. The annealing process can be performed with a fixed overall length of the grating, whereby the number of grating elements is allowed to vary as long as a minimum defined feature size is maintained. Alternately or in addition, the length of the grating can vary. In the examples discussed below, the grating length was fixed.
Referring now to
The initial grating structure used in the computation includes 10,000 grating elements each having length exactly equal to 50 nm and the refractive index of each element randomly assigned to be either n1=3.292292 or n2=3.300. It should be noted that the length of the grating can be selected to be fixed or can be changed during the computation to provide a better match to the predetermined spectral response. The following values were chosen for the annealing process: Tinit=1; α=0.8; Nmax=200,000. It will be understood based on the discussion of the annealing process, that the iteration can be terminated either when a maximum number Nmax of iterations has been reached or when the computed cost function is less than a predetermined target cost function.
At each iteration, one grating element (between 1 to 10,000) is chosen at random and its index of refraction is “flipped” from n1=3.292292 to n2=3.300, or vice versa.
For the purpose of this comb filter design, an exponent of 4 is selected in the definition of the cost function:
The curve fit to the actual reflectivity is calculated by subtracting the actual reflectivity from the target reflectivity at each wavelength of interest, raising the difference to the fourth power, and summing the results over all target peaks to form the cost function. The target reflectivity is hereby defined by normalized amplitude-weighted delta functions at the wavelengths λi, leaving the target reflectivity undefined elsewhere. While this approach does not take into account the finite width of the reflectivity peaks, it nevertheless enables a fast computation of the spectral filter response with adequate accuracy.
The results compare advantageously with those of Avrutsky et al. (U.S. Pat. No. 6,141,370). Avrutsky does not define a cost function as such, but rather a non-uniformity δ or residual factor as follows:
For the purpose of comparing the curve fit obtained with the disclosed process with the results quoted in U.S. Pat. No. 6,141,370, the non-uniformity of the peaks of the simulated reflectance spectral response was calculated using the definition in U.S. Pat. No. 6,141,370, yielding a residual factor of 11.8503×10−5, which is approximately 30 times smaller than the quoted value of 6×10−4.
The process was repeated with different seed values, resulting in a comb filter peak residual factor for 10 successive runs of:
The computation speed between the scattering matrix method described in U.S. Pat. No. 6,141,370 was also compared with that of the FFT annealing process of FIG. 2. Both processes were executed on a Pentium® III desktop computer with 256MB RAM and running at a clock speed of 1 GHz. Computing the scattering matrix method takes approximately 3.5 min per iteration, whereas computing the FFT annealing process takes approximately 0.18 sec per iteration.
An aperiodic grating structure, such as the structure of
While the invention has been disclosed in connection with the preferred embodiments shown and described in detail, various modifications and improvements thereon will become readily apparent to those skilled in the art. Accordingly, the spirit and scope of the present invention is to be limited only by the following claims.
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Hänvisningar finns i följande patent | <urn:uuid:ca5f151a-ef4b-45bf-ac54-fbad517fc9a0> | {
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THE INTERPLAY OF ENTANGLEMENT AND DISSIPATION IN MANY-BODY QUANTUM SYSTEMS
Michael Foss-Feig, Kaden R. A. Hazzard, Andrew J. Daley, James K. Thompson, John J. Bollinger, and Ana Maria Rey
Understanding the behavior of strongly correlated quantum systems in the presence of dissipation is a fundamental challenge in modern physics. While dissipation generally tends to degrade correlations, it is now widely appreciated that it can also give rise to many-body physics not possible with strictly coherent dynamics, and can be used explicitly for the creation of entanglement. Regardless of whether one’s intention is to minimize or to harness dissipation, determining its effect on interacting many-body quantum systems is central to the fields of quantum simulation, quantum information, and quantum metrology. We present two complementary theoretical studies aimed at understanding both the limitations imposed by and the benefits afforded by dissipation in ultra-cold atomic gas experiments. First, we develop a comprehensive theoretical framework for predicting the effects of dissipation on the dynamics of the quantum Ising model. This model emerges naturally as a description of the spin degrees of freedom in a variety of solid state and atomic systems, and its coherent far-from-equilibrium dynamics has been used extensively for the generation of entanglement in these systems. Focusing in particular on trapped ion systems, we develop a complete description of the dynamical development of quantum correlations, and characterize the relative importance of the different possible sources of dissipation. To the best of our knowledge, this work provides the first closed form solution of an interacting spin-model (in more than one spatial dimension) with local dissipation. In addition to making concrete and experimentally relevant predictions, it should provide a useful benchmark for testing approximate techniques. Next, we consider the effects of reactive two-body collisions on ultracold atomic and molecular vapors. Such collisions are generally considered to be problematic in gases of reactive polar molecules and electronically excited alkaline earth atoms, limiting the lifetime of these otherwise promising experimental platforms. We show that this point of view is overly pessimistic: In particular, reactive two-body collisions drive two-component fermionic gases into entangled steady states. The entanglement, which comes in the form of Dicke states, could be useful for precision metrology experiments, and emerges naturally from initially spin incoherent gases that are well above the degeneracy temperature. | <urn:uuid:2122f463-008b-4607-8e4a-613f28d3dbe5> | {
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The shape-memory alloy actuators might power minimally invasive surgical devices or tiny laptop cameras
Shape-memory alloys that change shape when heated could become tiny mechanical muscles for electronic devices. New mechanical devices based on the alloys produce three to six times more torque than electric motors, and weigh just one-20th as much.
Such devices, known as actuators, can be cut from a flat sheet of metal just a fraction of a millimeter thick. They emerged from a roject that aims to build printable robots, where the robots would consist of both the metal actuators and plastic components that could be built layer-by-layer through a process similar to inkjet printing. | <urn:uuid:445f2943-2c46-4a0d-a7fc-003ee5c0c754> | {
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Date of Award
Doctor of Philosophy (PhD)
Measurements by dielectric spectroscopy, ultrasonics and calorimetry ofseveral low viscosity monomeric liquids undergoing spontaneous chemical reaction, to form three new, linear chain polymers under isothermal conditions, have been used to determine how the number ofcovalent bonds formed during the growth of a linear chain affects the dielectric and ultrasonic properties, their respective relaxation times, and their spectral shape. The dielectric properties changed in the following manner. During this reaction, the static permittivity decreased and the relaxation time increased towards limiting values. As the number of covalent bonds increased towards the Avogadro number, the change in the complex permittivity as measured for a fixed frequency was phenomenologically similar to that observed on varying the frequency, although the exact formalisms in both cases differed. In both cases the relaxation function could be well described by a stretched exponential or sum ofexponentials, characterized by a temperature and system dependent exponent that decreased as the state of the system changed from a monomeric liquid to a fully reacted polymer. At later stages of chemical reaction a second relaxation process at higher frequencies is revealed. The dielectric manifestation of the irreversible process of covalent bond formation is remarkably similar to that observed on supercooling a molecular or polymeric liquid.
Longitudinal velocity and attenuation of ultrasonic waves travelling through the three molecular liquids at different temperatures have been measured as its molecules combine irreversibly to form large entities and thereby decrease the diffusivity and increase the configurational restrictions to their dynamics. From these data, the longitudinal modulus and compliance are calculated, and the molecular relaxation time and related properties are deduced and interpreted in terms ofthe number of covalent bonds formed, by a formalism that connects the size ofthe molecules in the liquid with its elastic behaviour. This relaxation time increases monotonically with increase in the molecule's size, tending to infinity as the number ofcovalent bonds formed approaches Avogadro's number. The complex plane plots ofthe modulus and compliance have a shape which is described by a skewed arc function, with a temperature dependent exponent ϒ, that ranges in values from 0.33- 0.31 for modulus and 0.39-0.45 for compliance. Departure from this shape is shown to be due to contributions from non-zero shear viscosity for relatively small size of molecules, and contributions from a faster, or sub Tg-relaxation process when the molecular size is large, which is similar to the behaviour for the dielectric properties. Simulation of the data suggests that this sub Tg-relaxation process, which is progressively more separated from the main relaxation process as the molecular size increases, contributes significantly to the high frequency elastic properties. The measured longitudinal modulus has been deconvoluted to show that the increase in the bulk modulus, and not the shear modulus, dominates the elastic properties when the molecular size increases. Comparison ofthe calculated relaxation times for the longitudinal modulus and compliance with the dielectric relaxation time show that the compliance and dielectric data change in a remarkably similar manner with increasing time of chemical reaction, which is unexpected owing to their different mechanisms.
In the last part of this work, the dipolar diffusion in the glassy and supercooled liquid states of 9 additional molecular liquids and oftheir linear chain or network polymerized states formed by condensation-polymerization at different temperatures and times have been studied by measuring the dielectric properties for a fixed ac frequency of 1 kHz. The study showed that as the extent of polymerization increased with increasing isothermal temperature of polymerization, the sub-Tg relaxation peak due to localized molecular motions in the molecular state became gradually extinct, and a corresponding peak at a higher temperature evolved and reached its maximum height. The temperature of the sub-Tg relaxation peak in the polymerized state differed from that of the α-relaxation peak of the supercooled molecular liquid by as much as 70K, but, in several cases, the two temperatures were similar. Reasons for the latter occurrence are given in phenomenogical terms. It is concluded that the localized relaxation modes of the polar segments of the macromolecule are not related to the modes of molecular diffusion in the monomeric liquid state above its Tg. The localized relaxation characteristic of the glassy molecular state persists in the incompletely polymerized state, where it is seen as a ϒ-relaxation.
Parthun, Matthew Giles, "Dielectric and Ultrasonic Studies of Macromolecular Growth During Polymerization" (1997). Open Access Dissertations and Theses. Paper 3988. | <urn:uuid:69354dfe-2db1-466b-b58e-8a21563dcdfd> | {
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Marginal Regression Models with Varying Coefficients for Correlated Ordinal Data.
Collaborative Research Center 386, Discussion Paper 177
This paper discusses marginal regression models for repeated or clustered ordinal measurements in which the coefficients of explanatory variables are allowed to vary as smooth functions of other covariates. We model the marginal response probabilities and the marginal pairwise association structure by two semiparametric regressions. To estimate the fixed parameters and varying coefficients in both models we derive an algorithm that is based on penalized generalized estimating equations. This allows to estimate the marginal model without specifying the entire distribution of the correlated categorical response variables. Our implementation of the estimation algorithm uses an orthonormal cubic spline basis that separates the estimated varying coefficients into a linear part and a smooth curvature part. By avoiding an additional backfitting step in the optimization procedure we are able to compute a robust approximation for the covariance matrix of the final estimate. We illustrate our method by an application to longitudinal data from a forest damage survey. We show how to model the dependence of damage state of beeches on non-linear trend functions and time-varying effects of age. | <urn:uuid:240d50a3-f822-4cd9-838e-7712667feffd> | {
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THEORETICAL AND PRACTICAL ASPECTS OF A FLAME ATOMIC FLUORESCENCE DETECTOR FOR LIQUID CHROMATOGRAPHY (HPLC)
A continuum source atomic fluorescence spectrometer (CSAFS) has been constructed for use in high performance liquid chromatography (HPLC). The design is described in detail, and analytical figures of merit such as reproducibility and limits of detection are presented for the spectrometer. The CSAF spectrometer was interfaced to a high performance liquid chromatograph for metal specific detection. Details of this interface are presented, as well as performance characteristics of the interfaced system. The HPLC-CSAFS system was used to speciate cadmium ion from cadmium complexed to soil fulvic acid, and a new method for determining the stability constant of that reaction based on this separation is presented. The peak shapes of the system are described in terms of two models. These models examine the physical and chemical processes of the detector and how these processes affect the peak shape. Computer simulations are used to fit experimental data to the models. A theoretical framework is described which extends present signal-to-noise theory for static systems to dynamic, time-dependent methods. These equations define dynamic figures of merit, particularly signal-to-noise ratio and limit of detection, in terms of their static system counterparts. The postulations are verified by experimentation on the HPLC-CSAFS system and by computer simulation of noise processes.
WILLIAM J TARASZEWSKI,
"THEORETICAL AND PRACTICAL ASPECTS OF A FLAME ATOMIC FLUORESCENCE DETECTOR FOR LIQUID CHROMATOGRAPHY (HPLC)"
(January 1, 1982).
Dissertations (1962 - 2010) Access via Proquest Digital Dissertations. | <urn:uuid:f13c12dc-3ddf-408e-b713-2618b11fc637> | {
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An analysis of the impact of the presence of high levels of interference in wireless sensor networks in residential buildings is presented. Furthermore, this is accompanied by WLAN measurement data to provide a quantitative illustration of actual interference levels experienced and associated signal statistics. The analysis use the excess energy needed with a simple retransmission scheme to maintain a predefined packet error rate as a figure of merit. Based on the analysis results and the example measurement data, a strategy to mitigate the effect of interference utilising the offered figure of merit is proposed.
Date of Conference: Feb. 28 2011-March 3 2011 | <urn:uuid:1034c421-16bc-4bba-b2c9-3e369b0239c9> | {
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Xia, Kaiwen (2005) Laboratory investigations of earthquake dynamics. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-02262005-161824
Earthquake represents one of most destructive geological hazards. In this thesis I will attempt to understand it through controlled laboratory experiments. The earthquake dynamic rupturing process itself is a complicated phenomenon, involving dynamic friction, wave propagation, and heat production. Because controlled experiments can produce results without assumptions needed in theoretical and numerical analysis, the experimental method is thus advantageous over theoretical and numerical methods.
Our laboratory fault is composed of carefully cut photoelastic polymer plates (Homalite-100, Polycarbonate) held together by uniaxial compression. As a unique unit of the experimental design, a controlled exploding wire technique provides the triggering mechanism of laboratory earthquakes. Three important components of real earthquakes (i.e., pre-existing fault, tectonic loading, and triggering mechanism) correspond to and are simulated by frictional contact, uniaxial compression, and the exploding wire technique. Dynamic rupturing processes are visualized using the photoelastic method and are recorded via a high-speed camera. Our experimental methodology, which is full-field, in situ, and non-intrusive, has better control and diagnostic capacity compared to other existing experimental methods.
Using this experimental approach, we have investigated several problems: dynamics of earthquake faulting occurring along homogeneous faults separating identical materials, earthquake faulting along inhomogeneous faults separating materials with different wave speeds, and earthquake faulting along faults with a finite low wave speed fault core. We have observed supershear ruptures, rupture speed transition, directionality of rupture in faults with a material contrast, self-healing slip pulses in faults with a finite core, crack-like to pulse-like rupture transition in faults with a finite core.
|Item Type:||Thesis (Dissertation (Ph.D.))|
|Subject Keywords:||earthquake dynamics; laboratory earthqaukes; rupture transition; self-healing pulse; spontaneous rupture; supershear|
|Degree Grantor:||California Institute of Technology|
|Division:||Geological and Planetary Sciences|
|Thesis Availability:||Public (worldwide access)|
|Defense Date:||25 January 2005|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Imported from ETD-db|
|Deposited On:||04 Mar 2005|
|Last Modified:||26 Dec 2012 02:32|
- Final Version
See Usage Policy.
Repository Staff Only: item control page | <urn:uuid:557962b7-f95e-4224-96c3-1f21b1104e1a> | {
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Knowledge Management for Computational Problem Solving
D. T. Lee (Institute of Information Science, Academia Sinica, Taiwan)
G. C. Lee (Institute of Information Science, Academia Sinica, Taiwan)
Y. W. Huang (Institute of Information Science, Academia Sinica, Taiwan)
Abstract: Algorithmic research is an established knowledge engineering process that has allowed researchers to identify new or significant problems, to better understand existing approaches and experimental results, and to obtain new, effective and efficient solutions. While algorithmic researchers regularly contribute to this knowledge base by proposing new problems and novel solutions, the processes currently used to share this knowledge are inefficient, resulting in unproductive overhead. Most of these publication-centred processes lack explicit high-level knowledge structures to support efficient knowledge management. The authors describe a problem-centred collaborative knowledge management architecture associated with Computational Problem Solving (CPS). Specifically we articulate the structure and flow of such knowledge by making in-depth analysis of the needs of algorithmic researchers, and then extract the ontology. We also propose a knowledge flow measurement methodology to provide human-centred evaluations of research activities within the knowledge structure. This measurement enables us to highlight active research topics and to identify influential researchers. The collaborative knowledge management architecture was realized by implementing an Open Computational Problem Solving (OpenCPS) Knowledge Portal, which is an open-source project accessible at http://www.opencps.org.
Keywords: algorithmic research, collaborative knowledge management architecture, knowledge flow measurement, knowledge management, openCPS, problem-centred
Categories: H.1, H.3, H.4 | <urn:uuid:c9dd413c-6927-4efb-a3f1-ff77496eab33> | {
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Electrochemical and magnetic resonance studies of tertiary phosphine complexes of nickel
Abstract (Summary)Restricted Item. Print thesis available in the University of Auckland Library or available through Inter-Library Loan. In this thesis is presented the results of a study of di-tertiary phosphine compounds, their quaternary derivatives and various of their nickel(II) complexes using electrochemical and magnetic resonance methods. In chapters one and two are presented relevant literature reviews. An outline of relevant theory and the experimental technique used are given in chapters three and four respectively. The synthesis and characterisation, by 1H nmr and 31P nmr and elemental analysis, of several reported and hitherto unreported di-tertiary phosphines, their quaternary derivatives and their nickel(II) complexes is described in chapter five. The synthesis of cis- and trans-1,2-C2H2(PPh2)2, was found to be non-stereospecific, whereas the contrary had previously been reported. New so-termed unsymmetrical di-tertiary phosphines were synthesised. These compounds and their quaternary and nickel(II) derivatives exhibited AB quartets as their 31P nmr spectra from which chemical shifts and coupling constants were directly obtained. In chapter six the 1H nmr and 31P nmr spectral parameters of the compounds synthesised are quantitatively discussed. The coordination chemical shift and the ring effect for one group of compounds was investigated. The 400 MHz 31P nmr spectrum of one compound was conclusively assigned to two unique AA'BB' spin systems. Another compound exhibited a line pattern suggestive of a one-ended dissociation of a coordinated ligand to produce a three-coordinate complex. The redox processes of the (diphosphino)nickel(II)(dithiolate) complexes prepared, and the esr parameters of their electrogenerated redox products were investigated, and are presented in chapter seven. These complexes exhibited quasi-reversible one-electron reduction processes to form stable nickel(I) complexes. The unique, successive one-electron transfer processes of two new dinuclear nickel(II) complexes were observed and investigated. The factors which produce these effects were discussed. One compound was observed to undergo an oxidation process to produce a species tentatively assignable as a nickel(II)-stabilised coordinated di-phosphorus radical cation, with observed hyperfine coupling to two inequivalent 31P nuclei. It was observed that systematic variations in the chelate ring size, chelate linkage, and the number and type of alkyl substituents on the phosphorus nuclei produced systematic variations in the reduction potentials and esr parameters obtained for these [(diphosphino)nickel(II)(dithiolate)]n complexes and their nickel(I) redox products. The (diphosphino)NiS2C2Ph2 complexes studied exhibited one or two one-electron oxidation processes, and esr spectra typical of nickel(II)-stabilised coordinated dithioketyl complexes. One such complex was assigned to undergo rapid dimer formation upon freezing. The production of [(diphosphino)2Ni(I)]+ complexes from the reaction of [(diphosphino)2Ni(II)]2+ complexes and [Ni(S2C2R2)2]- complexes, R = CN and Ph, was observed and concluded to be due to an electron transfer process more complex than that involving an outer-shell mechanism. Presented in chapter eight is an investigation of the redox properties of the complexes of general form [(L-L)2Ni(II)]2+, [(L-L)2Ni(X)]+, (VPP)NiX2, and [(trans-VPP)NiX2]n, L-L = a diphosphino moiety, and X = halogen or SCN, and the esr parameters of their redox products. The successive one-electron redox processes which some of these complexes exhibited were quantitatively investigated, and comparisons were made with the other nickel(II) complexes studied. Several nickel(III) complexes were produced in-situ, and from the resulting esr spectra, assignments of the molecular structures of the complexes were made.
School Location:New Zealand
Source Type:Master's Thesis
Date of Publication:01/01/1987 | <urn:uuid:6b1001c7-4d18-4b97-82e2-e8bc3862e196> | {
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Susanne Butz, Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany.
Title: A Tunable Josephson Metamaterial
Abstract: We present experimental data on a tunable magnetic metamaterial consisting of rf-SQUIDs. A metamaterial is a medium constructed of artifical elements, so- called meta-atoms, that interact in a specific way with an incoming electromagnetic wave. The size of and the distance between the individual meta-atoms is much smaller than the wavelength. Our metamaterial consists of one-dimensional arrays of 27 rf-SQUIDs, one chain placed inside each of the gaps of a coplanar waveguide. Due to the nonlinear inductance of the rf-SQUID, its resonance frequency is tunable in situ by applying a dc magnetic field. We demonstrate that this results in tunable effective parameters of our metamaterial. In order to obtain the effective magnetic permeability from the measured data, we employ a technique that uses only the complex transmission coefficient S21.
Title: Spins and photons: toward quantum networks in diamond
Abstract: Long-lived electronic and nuclear spin states have made nitrogen-vacancy (NV) defects in diamond a leading candidate for solid-state quantum information processing. Moreover, their coherent optical transitions open opportunities for quantum communication. This talk will consider the motivation and requirements for optically-networked quantum devices, and explore challenges and opportunities for realizing them in diamond. In particular, the resonant excitation and emission in these defect centers enables single shot spin detection as well as observation of two-photon quantum interference; these two capabilities have enabled measurement-based entanglement between remote NV centers. | <urn:uuid:0d7a6bbc-3ebe-4c1d-8631-2476c3027671> | {
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Improvement of the oral cavity and finger mechanisms and implementation of a Pressure-Pitch Control System for the Waseda Saxophonist Robot
ABSTRACT Our research is related to the development of an anthropomorphic saxophonist robot which reproduced the human organs involved during the saxophone playing. This research approach aims in understanding the human motor control from an engineering point of view and enabling the communication between humans and robots in musical terms. In a previous research, we have presented the Waseda Saxophonist Robot No. 2 (WAS-2) which improved the design of the lip and finger mechanisms. In addition, a feed-forward air pressure with dead-time compensation and an overblowing correction controller were implemented. However, the range of pressure was too limited to reproduce dynamic effects of the sound (i.e. decrescendo, etc.), a delay on the response of the finger mechanism was detected (due to the use of a wire-driven mechanism) and deviations on the pitch during the saxophone playing were observed. Therefore; in this paper, we present the Waseda Saxophonist Robot No. 2 Refined (WAS-2R). In particular the shape of the oral cavity has been re-designed to increase the sound pressure range and potentiometers were embedded on the fingers to reduce the dynamic delay response of the wire-driven mechanism. In addition, a Pressure-Pitch Controller has been implemented to reduce the deviation of the sound pitch by implementing a feedback error learning algorithm for a Multiple-Input Multiple-Output system. A set of experiments were proposed to verify the effectiveness of the re-designed mechanisms and the improved control strategy. From the experimental results, we could confirm the improvements to extend the sound pressure range to reproduce the decrescendo effect, to reduce the response delay from the finger mechanism as well as the deviations on the sound pitch. | <urn:uuid:c02debbd-bce2-47d9-980f-ccc0c5dc1ec2> | {
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} |
Print version ISSN 1516-1439
ALVES, Péricles Guedes; CASTRO, José Adilson de; MOREIRA, Luciano Pessanha and HEMERLY, Elder Moreira. Modeling, simulation and identification for control of tandem cold metal rolling. Mat. Res. [online]. 2012, vol.15, n.6, pp. 928-936. Epub Oct 23, 2012. ISSN 1516-1439. http://dx.doi.org/10.1590/S1516-14392012005000137.
This paper describes a modeling procedure for tandem cold metal rolling, including the linearization step and system identification for control. The tandem cold rolling process is described by a mathematical model based on algebraic equations developed for control purposes and empirical relations. A state-space model is derived and detailed analyses in open loop are presented, concerning the sensitivity with regard to the variations in process parameters and results for the application of a new subspace identification method are compared with classical methodologies. Therefore, this work intents to be a contribution for developments in new control strategies for tandem cold rolling process that offer the potential to reduce the design efforts, the commissioning time and maintenance in rolling mills. The preliminary results obtained with this model have shown reasonable agreement with operational data presented at literature for industrial cold rolling process.
Keywords : rolling mill control; tandem cold rolling; process simulation; mathematical model; system identification. | <urn:uuid:6dfca831-d849-47a6-b7a3-32c2a7700a77> | {
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Skip to Main Content
We consider an orthogonal space-frequency block coded (OSFBC) orthogonal frequency-division multiplexing (OFDM) system under multi-tone interference and multi-path fading environment. An approximate analytic expression for the bit error probability of OSFBC-OFDM system with a block code matrix for four transmit antennas is derived and the derivation methodology for other code matrices is summarized. The bit error rate simulations are performed for QPSK signals and compared with the theoretical results. The influences of the total energy of multi-tone interference and the fraction of interfered bandwidth are investigated. | <urn:uuid:9cc5897d-c6cb-4030-9ffb-fb797b87ce45> | {
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Online from: 1988
Subject Area: Organization Studies
Options: To add Favourites and Table of Contents Alerts please take a Emerald profile
|Title:||Dynamic capability, knowledge, learning, and firm performance|
|Author(s):||Shih-Yi Chien, (Department of Marketing and Distribution Management, National Kaohsiung First University of Science and Technology, Kaohsiung, Taiwan), Ching-Han Tsai, (Department of Marketing, LONGDE Logistics?Co., Ltd, Taipei, Taiwan)|
|Citation:||Shih-Yi Chien, Ching-Han Tsai, (2012) "Dynamic capability, knowledge, learning, and firm performance", Journal of Organizational Change Management, Vol. 25 Iss: 3, pp.434 - 444|
|Keywords:||Dynamic capabilities, Knowledge management, Knowledge resources, Learning, Learning mechanisms, Learning processes, Organizational performance, Performance|
|Article type:||Research paper|
|DOI:||10.1108/09534811211228148 (Permanent URL)|
|Publisher:||Emerald Group Publishing Limited|
Purpose – This paper seeks to apply the dynamic capability framework to explore why store managers within the same chain of restaurants perform differently. Specifically, this paper argues that knowledge resources and learning mechanisms are critical to the development of dynamic capabilities.
Design/methodology/approach – The approach takes the form of an empirical data analysis. Hypotheses are tested on 132 store managers in a leading fast-food restaurant chain in Taiwan.
Findings – The findings indicate that dynamic capabilities increase store performance, and that both knowledge resources and learning mechanisms have a positive effect on dynamic capabilities. In addition, the effect of knowledge resources on dynamic capabilities is partially mediated by the type of learning mechanism.
Practical implications – Store managers must be able to develop dynamic capabilities if they are to deal with the rapidly changing environment they are facing. Knowledge resources and learning mechanisms both improve the development of dynamic capabilities.
Originality/value – This paper conceptualizes and empirically tests the relationships between knowledge resources, learning mechanisms, dynamic capabilities, and performance in the restaurants of a fast-food chain. In addition, this paper investigates how dynamic capabilities work from a process perceptive by examining the mediation effect of the learning mechanisms.
To purchase this item please login or register.
Complete and print this form to request this document from your librarian | <urn:uuid:d5e9bcf9-775c-4c2d-8acb-7dc2ce18af00> | {
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It is shown that a negative contribution to the group-velocity dispersion always accompanies angular dispersion. We describe structures, such as slabs and prisms, that use this contribution to provide adjustable group-velocity dispersion. We discuss, in particular, considerations regarding incorporation of these structures with a laser resonator. A description of possible submillimeter semiconductor devices is also given.
© 1984 Optical Society of America
O. E. Martinez, J. P. Gordon, and R. L. Fork, "Negative group-velocity dispersion using refraction," J. Opt. Soc. Am. A 1, 1003-1006 (1984) | <urn:uuid:9af8769f-bd6c-472e-9397-ae03cb2df594> | {
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El-Maleh, Aiman H. and Arkasosy, Basil and Andalusi, Adnan (2006) Interconnect-Efficient LDPC Code Design. 18th IEEE Int. Conf. on Microlelectronics. pp. 127-130.
In this paper, we present a new, hardware-oriented technique for designing Low Density Parity Check (LDPC) codes. The technique targets to achieve an interconnect-efficient architecture that reduces the area and delay of the decoder implementation while maintaining good error correction performance. With a fully parallel implementation of the LDPC decoder, the proposed design assumes a constraint on the interconnect wire length which has a direct impact on the maximum signal delay and power dissipation. Furthermore, this design approach is shown to lower interconnect routing congestion, and hence reduce the chip area and maximize chip utilization.
|Divisions:||College Of Computer Sciences and Engineering > Computer Engineering Dept|
|Creators:||El-Maleh, Aiman H. and Arkasosy, Basil and Andalusi, Adnan|
|Email:||email@example.com, firstname.lastname@example.org, email@example.com|
|Deposited By:||AIMAN HELMI EL-MALEH|
|Deposited On:||29 Feb 2008 23:36|
|Last Modified:||12 Apr 2011 13:06|
Repository Staff Only: item control page | <urn:uuid:24ca0ce0-8e78-4213-9e89-4ca50a9c2847> | {
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Synthesis and optimization of carbon nanofiber templated polypyrrole
Erden, Ayça (2008) Synthesis and optimization of carbon nanofiber templated polypyrrole. [Thesis]
Official URL: http://192.168.1.20/record=b1225678 (Table of Contents)
In order to suggest a new promising material to be used as an active material in supercapacitor applications, carbon nanofiber templated Polypyrrole was designed and synthesized. The common conducting polymer/ carbon nanofiber composites used in capacitive applications were usually physically mixed composites of the materials. In this thesis, the outcomes are investigated when these materials of interest are chemically bonded via electropolymerization. Carbon nanofibers with a thickness of 100 nm to 150 nm were chosen to act as a template for the conducting polymer to grow on. The electropolymerization was successful and it is proven by voltammetric measurement, Nuclear Magnetic Resonance spectra, Fourier Transform Infrared spectra and Scanning Electron Microscopy images. After the deposition of Polypyrrole on carbon nanofibers were achieved, the material was optimized by means of the deposition amount and speed. The results were supported by voltammograms, specific capacitance calculations and SEM images. Polymers with different deposition amounts and speeds are compared. The sample deposited by six times cycling at 25 mV/s is found to posses both the highest specific capacitance and the highest surface area.
Repository Staff Only: item control page | <urn:uuid:a87371e1-e092-4403-bd1d-a3111fa67684> | {
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"url": "http://research.sabanciuniv.edu/14152/"
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2ab assembly: a methodology for automatable, high-throughput assembly of standard biological parts
There is growing demand for robust DNA assembly strategies to quickly and accurately fabricate genetic circuits for synthetic biology. One application of this technology is reconstitution of multi-gene assemblies. Here, we integrate a new software tool chain with 2ab assembly and show that it is robust enough to generate 528 distinct composite parts with an error-free success rate of 96%. Finally, we discuss our findings in the context of its implications for biosafety and biosecurity. | <urn:uuid:ed8cad20-9865-4ac6-8824-75fa7a56cb05> | {
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A Synthetic Driver for File System Simulations
A driver is a software module that mimics an actual usage environment by
generating a stream of requests for use in simulations or in stress testing
of an implemented system. This paper describes the design of a computationally
efficient driver for use in performance evaluation of file systems. Based
on observations of a timesharing system in a research environment, it is
shown that files can be naturally classified into three equivalence classes:
System files, Temporary files, and User files. The usage patterns of each
of these classes is shown to be radically different, and a separate locality
model is developed for each class. The driver is parameterized, and actual
values for these parameters are derived from the experimental observations.
Parameters representative of other environments may be used with the driver
to extend its domain of applicability. Insights from the experimental data
presented here may also be of use in other applications such as capacity
planning and file system design. | <urn:uuid:7eac203e-543d-4aad-8fc4-d5fd3ff480b7> | {
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"url": "http://www.cs.cmu.edu/afs/cs/project/coda-www/ResearchWebPages/absdir/mtpa84-abstract.html"
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In situ Chemical Oxidation of Creosote/Coal Tar Residuals: Experimental and Numerical Investigation
Coal tar, coal tar creosote and oily wastes are often present as subsurface contaminants that may migrate below the water table, leaving a widely distributed residual source of contaminants leaching to the ground water. In situ chemical oxidation is a potentially viable technology for the remediation of aquifers contaminated with creosote and coal tars. The oxidant of choice would be flushed through the contaminated area to oxidize aqueous contaminants and enhance the mass transfer of contaminants from the oil phase. A series of batch and column experiments were performed to assess the ability of a chemical oxidizing reagent to oxidize creosote compounds and to increase mass transfer rates. Results from the column experiments were then simulated using a reactive transport model that considered 12 different creosote compounds undergoing dissolution, oxidation and advective-dispersive transport. Three strong chemical oxidizing reagents, Fenton's Reagent, potassium persulfate with ferrous ions, and potassium permanganate were tested with batch experiments to determine their reactivity towards creosote compounds. All three reagents successfully decomposed aqueous creosote compounds and were able to reduce the mass of the monitored creosote compounds within the oil phase. However, both the Fenton's and persulfate reagents required large molar ratios of iron and peroxide because the precipitation of iron continually removed the iron catalyst from the aqueous phase. Fenton's and persulfate reagents could be used in systems that are allowed to become acidic to solubilize the iron, but the cost of adjusting the pH, potential impact on aquifer geochemistry and the short lived free radical reaction make these reagents less practical than KMnO4. KMnO4 oxidizes a wide variety of creosote compound, can be used at very high concentrations, and its concentration will not be reduced significantly as it moves through the zone of contamination. The feasibility of using potassium permanganate as an oxidizing reagent for in situ treatment of creosote residuals was investigated using batch column experiments. Column experiments were conducted at a neutral pH in a carbonate rich sand matrix with creosote at 8 % saturation. The columns were treated intermittently with simulated ground water or KMnO4 dissolved in simulated ground water (8 g/L) for 172 days. Under these experimental conditions the KMnO4 decreased the initial mass of the monitored creosote compounds by 36. 5%, whereas in the control column (no oxidizer) only 3. 9% was removed. To remove all of the monitored creosote compounds from the columns it was calculated that the volume needed would be 40 times less for the KMnO4 solution, compared to flushing alone with simulated ground water. To evaluate the potential effectiveness of in situ chemical oxidation at field sites, numerical model simulations need to incorporate relevant chemical oxidation rates to assess system performance and to provide design guidance. In-depth kinetic studies were performed to determine rate constants and to gain insight into the oxidation of creosote compounds with KMnO4. The study examined the kinetics of the oxidative treatment of a selected group of creosote/coal tar compounds in water using excess potassium permanganate and investigated the correlation between reactivity and physical/chemical properties of the organic pollutants. The oxidation of naphthalene, phenanthrene, chrysene, pyrene, 1-methylnapthalene, 2-methylnaphthalene, acenaphthene, fluorene, carbazole, isopropylbenzene, ethylbenzene and methylbenzene closely followed first-order reaction kinetics, enabling calculation of second-order rate constants. Fluoranthene was only partially oxidized by permanganate and the oxidation of anthracene was too fast to be measured. Biphenyl, dibenzofuran, benzene and tert-butylbenzene failed to react in this study. Comprehensive column experiments complemented by numerical modeling revealed an unequal enhancement of the removal of creosote compounds from the oil phase. For the more readily oxidizable compounds such as pyrene and naphthalene, a significant increase in the mass transfer rates was observed in the oxidation columns, compared to the oxidant free column. For non-oxidizable compounds such as biphenyl and dibenzofuran, an increase in the rate of mass removal was also observed in the oxidation columns, even though their aqueous concentrations were not reduced in the column. This was due to the rapid removal of the more readily oxidizable compounds from the oil, which increases the mole fraction of the non-oxidizable compounds. Thus according to Raoult's Law, the concentration in the aqueous phase becomes closer to its pure phase liquid solubility and its aqueous concentration increases. The most significant result of the experiments is the observed increase in the rate of removal of those compounds that have low aqueous solubilities and are readily oxidized, such as pyrene and fluorene. Compounds that have low aqueous solubilities and are not readily oxidizable, such as chrysene, may still take a long period of time to be removed, but the removal time is greatly reduced with oxidation compared to flushing the area with water alone.
School:University of Waterloo
School Location:Canada - Ontario
Source Type:Master's Thesis
Keywords:earth sciences creosote coal tar oxidation permanganate
Date of Publication:01/01/2004 | <urn:uuid:f1822c64-3213-419a-8cc7-3357aa371b49> | {
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Efficient RFID Data Imputation by Analyzing the Correlations of Monitored Objects
Source: Northeastern University
As a promising technology for tracing the product and human flows, Radio Frequency Identification (RFID) has received much attention within database community. However, the problem of missing readings restricts the application of RFID. Some RFID data cleaning algorithms have therefore been proposed to address this problem. Nevertheless, most of them fill up missing readings simply based on the historical readings of independent monitored objects. While, the correlations (spatio-temporal closeness) among the monitored objects are ignored. The paper observes that the spatio-temporal correlations of monitored objects are very useful for imputing the missing RFID readings. This paper proposes a data imputation model for RFID by efficiently maintaining and analyzing the correlations of the monitored objects. | <urn:uuid:a4f26ca1-df13-4cb2-bb4f-04079347658f> | {
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To ensure consistent, high product quality and reduce development time, the biopharmaceutical industry constantly endeavors to optimize manufacturing processes. Research in this area has received significant recent attention as a result of the U.S. Food and Drug administration Process Analytical (PAT) initiative. This initiative has led an industry-wide effort to utilize "multivariate data acquisition and analysis tools, modern process analyzers or process analytical chemistry tools, process and endpoint monitoring and control tools, and continuous improvement and knowledge management tools." It is hoped that through these advances, process developers will achieve improved process understanding and continuous process improvement.
In many industrial situations, a large number of process variables are measured and recorded frequently for the entire duration of a batch, which is a large amount of data to process. To mitigate this burden, data-driven modeling techniques, such as principal component analysis (PCA) and partial least squares (PLS), provide the means for the dimensional reduction of these complicated multivariate systems. Effectively, PCA and PLS combine the major sources of variation in a system into a small number of orthogonal directions, thus significantly decreasing the complexity of the system. This dissertation addresses theoretical and practical issues related to batch process monitoring using PCA and PLS. The primary contributions of this research focus on online fault detection and diagnosis, online product quality prediction, and pattern matching in large datasets.
In this dissertation, PCA and PLS techniques are used to detect and diagnose a variety of process faults. Once data-driven models are constructed from historical data, these models are used to monitor batches online conducted at an industrial bioprocess pilot plant. To monitor new batches, statistical quality control confidence limits are calculated and when limit violations occurred, a diagnostic method is utilized to determine the specific variables most impacted by process faults.
PLS is used to make online predictions of quality variables from process data. This method accurately predicts final and intermediate titer measurements for normal operating condition batches and successfully detected abnormal batches. This approach allows for the continuous monitoring and prediction of titer values throughout the course of the batch. Different online prediction methods are developed and compared with existing methods.
Two pattern matching metrics, the PCA and PLS similarity factors, are used to make direct comparisons between batches. This pattern matching method has the benefit that it is both data-driven and unsupervised because unlike other pattern matching approaches, neither training data nor a process model is required. This approach generates a data-driven model (i.e., either PCA or PLS) for each separate batch and then calculates the degree of similarity between two batches. A related diagnosis method is able to identify the key process variables that cause dissimilarities between the two batches. This approach is capable of quickly screening large amounts of data for process differences. | <urn:uuid:153857a4-fcaa-41f3-aa19-3c697bc95d83> | {
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The aim of the SASO conference series is to provide a forum for the foundations of a principled approach to engineering systems, networks and services based on self-adaptation and self-organization. To this end, the meeting aims to attract participants with different backgrounds, to foster cross-pollination between research fields, and to expose and discuss innovative theories, frameworks, methodologies, tools, and applications. The complexity of current and emerging computing systems has led the software engineering, distributed systems and management communities to look for inspiration in diverse fields (e.g., complex systems, control theory, artificial intelligence, sociology, and biology) to find new ways of designing and managing networks, systems and services. In this endeavor, self-organization and self-adaptation have emerged as two promising interrelated facets of a paradigm shift.
Contributions must present novel theoretical or experimental results, or practical approaches and experiences in building or deploying real-world systems, applications, tools, frameworks, etc. Contributions contrasting different approaches for engineering a given family of systems, or demonstrating the applicability of a certain approach for different systems are particularly encouraged.
Theories, frameworks and methods for self-* systems
Robustness and dependability of self-* systems
Control of emergent properties in self-* systems
Biologically, socially, and physically inspired self-* systems
Management and control of self-* systems
Design and engineering for self-* systems (self-organization, self-adaptation, selfmanagement, self-monitoring, self-tuning, self-repair, self-configuration, etc.) | <urn:uuid:f0a80d30-b6f0-47e6-a416-e43e6625f12b> | {
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} |
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In this paper a new Active Queue Management (AQM) strategy based on Nonlinear Generalized Minimum Variance (NGMV) control is proposed for TCP/AQM networks. The NGMV control is a model free method which only requires output of the system. Cost function of this method involves weighted output error and weighted control signal terms. The NGMV controller is implemented in order to minimize the cost function which results in a decrease in the jitter (the variance of delay). The numerical simulation results confirm the effectiveness of the proposed method.
Date of Conference: 27-29 Dec. 2011 | <urn:uuid:40b71e98-0774-4999-81a9-c6042f3f38c9> | {
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Laurie H. Ihrig (firstname.lastname@example.org)
Subbarao Kambhampati (email@example.com)
Department of Computer Science and Engineering
Arizona State University, Tempe, AZ 85287-5406
Case-Based Planning (CBP) provides a way of scaling up domain-independent planning to solve large problems in complex domains. It replaces the detailed and lengthy search for a solution with the retrieval and adaptation of previous planning experiences. In general, CBP has been demonstrated to improve performance over generative (from-scratch) planning. However, the performance improvements it provides are dependent on adequate judgements as to problem similarity. In particular, although CBP may substantially reduce planning effort overall, it is subject to a mis-retrieval problem. The success of CBP depends on these retrieval errors being relatively rare. This paper describes the design and implementation of a replay framework for the case-based planner DERSNLP+EBL. DERSNLP+EBL extends current CBP methodology by incorporating explanation-based learning techniques that allow it to explain and learn from the retrieval failures it encounters. These techniques are used to refine judgements about case similarity in response to feedback when a wrong decision has been made. The same failure analysis is used in building the case library, through the addition of repairing cases. Large problems are split and stored as single goal subproblems. Multi-goal problems are stored only when these smaller cases fail to be merged into a full solution. An empirical evaluation of this approach demonstrates the advantage of learning from experienced retrieval failure. | <urn:uuid:9a1964bb-5d27-4b05-b916-6f654d45beb1> | {
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A decision support system for media planning
The media planning problem deals with the optimal allocation of a given budget over a predefined set of advertising vehicles. This problem can be formulated as a nonlinear integer program and solved by means of dynamic programming. A number of other exact and approximate solution methods are proposed, including a branch and bound algorithm, a fully polynomial approximation scheme and a greedy heuristic. It is shown that this greedy heuristic has (1) time and space complexity linear in the number of vehicle options and (2) a nonzero performance lower bound. The proposed decision support system overcomes some of the shortcomings of existing media planning models, including lack of transparency, low levels of interactivity, inability to handle S-shaped advertising response and utilization of exposure distribution models with weak empirical support. It is demonstrated by means of simulation that the proposed procedure yields solutions that are close to optimal even under extreme conditions and that it is sufficiently fast for online use. In the conclusions chapter, applications other than media planning are discussed for the heuristic developed here. Finally, a Pascal implementation of the decision support system is included. | <urn:uuid:7fe7eb10-cd4c-4f97-9afe-21d8e55d1f17> | {
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} |
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Virtual reality (VR) has been causing much concern in various industrial fields, and its applications are widening rapidly. This paper discusses the application of virtual reality in the field of instrument development, and the basic idea is to develop instruments in a virtual development environment generated by computer, with appropriate supports of computer hardware and software, and some essential VR peripherals. The users and developers can preview and interact with the instrument under design, thus making the design more sound an acceptable to both parties. The basic idea, principle and flowchart of the instrument development system is discussed, and a prototype example is given to show the initial effect of the approach when used in a virtual vehicle simulation system. The application of VR in instrument development can greatly enhance the efficiency and flexibility of the instrument development systems. The conclusion is that VR can play a very active and important role in the field of instrument development.
Date of Conference: Aug. 16 2007-July 18 2007 | <urn:uuid:3596007c-1d85-4606-8207-2d4523b8416f> | {
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Norris, G and McConnell, G (2010) Relaxed damage threshold intensity conditions and nonlinear increase in the conversion efficiency of an optical parametric oscillator using a bi-directional pump geometry. Optics Express, 18 (5). pp. 3993-3999. ISSN 1094-4087
A novel bi-directional pump geometry that nonlinearly increases the nonlinear optical conversion efficiency of a synchronously pumped optical parametric oscillator (OPO) is reported. This bi-directional pumping method synchronizes the circulating signal pulse with two counter-propagating pump pulses within a linear OPO resonator. Through this pump scheme, an increase in nonlinear optical conversion efficiency of 22% was achieved at the signal wavelength, corresponding to a 95% overall increase in average power. Given an almost unchanged measured pulse duration of 260 fs under optimal performance conditions, this related to a signal wavelength peak power output of 18.8 kW, compared with 10 kW using the traditional single-pass geometry. In this study, a total effective peak intensity pump-field of 7.11 GW/cm(2) (corresponding to 3.55 GW/cm(2) from each pump beam) was applied to a 3 mm long periodically poled lithium niobate crystal, which had a damage threshold intensity of 4 GW/cm(2), without impairing crystal integrity. We therefore prove the application of this novel pump geometry provides opportunities for power-scaling of synchronously pumped OPO systems together with enhanced nonlinear conversion efficiency through relaxed damage threshold intensity conditions.
Actions (login required) | <urn:uuid:fc4ac6ae-497d-40cc-a5e7-c216043d55c6> | {
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Volume 41, Issue 6 (November 1996)
The Importance of Thin Layer Chromatography in the Analysis of Reactive Dyes Released from Wool Fibers
Samples of reactively-dyed wool were obtained from a range of manufacturers and distributors and “digested” by alkaline hydrolysis to yield colored solutions. Results demonstrate that thin layer chromatographic analysis of reactive dyes yields important additional information, over and above that obtained from techniques such as comparison microscopy and visible light microspectrophotometry. Colored solutions obtained from single fibers were analyzed by thin layer chromatography (TLC) and reproducible results were obtained from a range of fiber lengths. | <urn:uuid:21b8da86-1bfa-4408-92cc-19ac426f98ab> | {
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Electrical inductance sensors are non-contact devices that measure the inductance of an electrical component or system. They consist of a wire loop or coils and are relatively inexpensive. Inductance, the property of a circuit or circuit element to oppose a change in current flow, refers to the capacity of a conductor to produce a magnetic field. The standard unit of inductance is the Henry (H). Because the Henry is a large unit, electrical inductance sensors often measure inductance in microhenry (µH) or millihenry (mH) levels.
Electrical inductance sensors contain a nickel-iron core shaft that rotates within the coil around the material. The inductance measured by an electrical inductance sensor depends on the number of turns in the coil, the type of material around which the coil rotates, and the radius of the coil. With the rotation of the shaft, displacement occurs within the coil and generates inductance. This displacement produces signals that can be measured by an inductance meter and recorded. Most inductance meters are digital, hand held devices suitable for measuring inductance of very low value. The results of the inductance calculation can be plotted as a graph for future study.
Selecting electrical inductance sensors requires a careful analysis of product specifications and application requirements. Most electrical inductance sensors have a standard accuracy variance of less than 0.5% when measured on full scale. For best results, an electrical inductance sensor should be able to generate an output signal of at least 4-20 mA. Typically, a sensor’s measurement range is approximately 30% of the coil diameter. For high precision measurements, the thickness of the coil should be at least 0.025 inches (in.).
Electrical inductance sensors are used in many different applications. Some electrical sensors are used in the automotive industry and the power industry. Other electrical sensors are used in constructing planar transformers, generating electrical magnetic fields, and monitoring the inductance of an electrical component. Electrical sensors such as electrical inductance sensors are widely used for detecting the presence of electrical voltage in equipments, and defective grounds. | <urn:uuid:bfe63548-3bc5-44fa-be93-553592b82423> | {
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US 4242406 A
This invention relates to a structural laminate having a plastic surface finish coat laminated to a structural base which has exceptional bond strength between the structural base and the plastic layer with which it interfaces. The structural base comprises a glass reinforced gypsum layer. The plastic laminate portion comprises a plastic surface finish coat, preferably a polyester gel coat or an acrylic resin, bonded to a reinforcing layer of curable polyester or epoxy resin reinforced with glass fibers. The reinforcing layer is adhered to a bonding layer which comprises glass fibers protruding from the reinforcing layer and coated with a limited amount of organic resin such as polyester or epoxy resin. The glass reinforced gypsum layer is applied to the protruding fibers of the bonding layer to form an interface having a bond strength of at least about 150 psi as determined by ASTM C297-68.
1. A structural laminate comprising:
(a) a plastic surface finish coat bonded to
(b) a reinforcing layer of an organic resin selected from polyester resins and epoxy resins containing reinforcing fibers, adhered to
(c) a bonding layer of organic resin coated glass fibers which are bonded to the reinforcing layer and which protrude therefrom, said glass fibers being present in an amount sufficient to provide a surface density of 0.25 to 0.65 ounces per square foot of reinforcing layer surface area, said protruding glass fibers being coated with an amount of the organic resin sufficient to promote adhesion of the fibers to one another at their intersections, but insufficient to encapsulate the fibers so as to prevent the gypsum layer (d) from intimately surrounding and engaging a substantial portion of the individual protruding coated fibers, said coated glass fibers being engaged and surrounded by
(d) a gypsum layer reinforced with glass fibers which functions as the structural base, and said structural laminate is characterized by having a bond strength between the gypsum layer and the plastic layer with which it interfaces of at least about 150 psi as determined by ASTM C297-68.
2. A structural laminate in accordance with claim 1 in which the plastic surface finish coat is selected from the group consisting of polyester resins, acrylic resins and acrylonitrile-butadiene-styrene resins and the reinforcing layer comprises a polyester resin.
3. A structural laminate in accordance with claim 1 in which the plastic surface finish coat is an epoxy resin, the reinforcing layer comprises an epoxy resin and the glass fibers comprising the bonding layer are mist coated with a polyester resin.
4. A structural laminate in accordance with claim 2 in which the glass fibers comprising the bonding layer are mist coated with a polyester resin.
5. A structural laminate in accordance with claim 1 in which the reinforcing fibers in the reinforcing layer are selected from chopped glass roving, glass strand mat, inorganic fibers and organic fibers.
6. A process for making a structural laminate comprising:
(a) applying a curable plastic finish coat containing a catalyst therefor to the surface of a mold;
(b) partially curing said curable plastic finish coat;
(c) applying a reinforcing layer of organic resin containing reinforcing fibers to said partially cured plastic finish coat by spraying said organic resin and reinforcing fibers onto said plastic finish coat;
(d) densifying said reinforcing layer to remove entrapped air;
(e) while said reinforcing layer is tacky, applying a bonding layer of chopped glass fibers by dry spraying said glass fibers onto said reinforcing layer in such a manner that said glass fibers protrude from said reinforcing layer;
(f) applying a light mist organic resin coating by spraying a limited amount of catalyzed resin over the surface of the protruding glass fibers;
(g) allowing the organic resin coating on the protruding glass fibers and the organic resin of the reinforcing layer to cure to at least the gel state;
(h) applying a neat coat of plaster containing no glass fibers by spraying the plaster onto the protruding glass fibers;
(i) applying a layer of glass reinforced plaster onto the protruding fibers by simultaneously spraying the plaster and operating a glass chopper to supply a stream of chopped glass fibers into the wet plaster; and
(j) drying the plaster to form a hard gypsum structural base.
7. A process in accordance with claim 6 in which the curable plastic finish coat is a polyester resin, the organic resin of the reinforcing layer and the organic resin applied to the protruding glass fibers are both polyester resins, and the chopped glass fibers comprising the bonding layer are present in an amount to provide surface density of 0.65 ounces per square foot of reinforcing layer surface area.
8. A process in accordance with claim 6 in which the curable plastic finish coat is an epoxy resin, the organic resin of the reinforcing layer and the organic resin applied to the protruding glass fibers are both epoxy resins, and the chopped glass fibers comprising the bonding layer are present in an amount to provide a surface density of 0.25 to 0.65 ounces per square foot of reinforcing layer surface area.
9. A process for making a structural laminate comprising
(a) applying a reinforcing layer of polyester resin containing reinforcing fibers to a shell material selected from an acrylic resin and an acrylonitrile-butadiene-styrene resin by spraying said polyester resin and reinforcing fibers onto the interior surface of said shell material;
(b) densifying said reinforcing layer to remove entrapped air;
(c) while said reinforcing layer is tacky, applying a bonding layer of chopped glass fibers by dry spraying said glass fibers onto said reinforcing layer in such a manner that said glass fibers protrude from said reinforcing layer;
(d) applying a light mist of polyester resin coating by spraying a limited amount of catalyzed polyester resin over the surface of the protruding glass fibers;
(e) allowing the polyester resin coating on the protruding glass fibers and the polyester resin of the reinforcing layer to cure to at least the gel state;
(f) applying a neat coat of plaster containing no glass fibers by spraying the plaster onto the protruding glass fibers;
(g) applying a layer of glass reinforced plaster onto the protruding fibers by simultaneously spraying the plaster and operating a glass chopper to supply a stream of chopped glass fibers into the wet plaster; and
(h) drying the plaster to form a hard gypsum structural base.
10. A process in accordance with claim 9 in which the chopped glass fibers comprising the bonding layer are present in an amount to provide a surface density of 0.25 to 0.65 ounces per square foot of reinforcing layer surface.
1. Field of the Invention
This invention pertains to a structural laminate having a plastic surface finish coat laminated to a structural base, which is useful in manufacturing wall units, building panels, furniture, cabinets, and plumbing ware. Useful items which may be manufactured by the practice of this invention include shower stalls, tubs and sinks.
2. Description of the Prior Art
Fiber glass reinforced materials are used in making structural panels and shaped articles. The large quantities of organic resin necessary for structural integrity of such articles renders them costly to produce. One proposed solution employs inorganic materials such as gypsum as a substitute for the costly resin used in the structural base. The inorganic materials used in the structural base should have adequate physical properties and a good bond to the plastic surface finish to provide structural integrity to the laminated product. The plastic surface finish is preferably a polyester gel coat or acrylic resin which provide water and stain resistance, colorfastness, durability and cleanability.
U.S. Pat. No. 3,868,296, to McKeon, Jr., et al teaches a plaster structural unit with a water impervious face, an intermediate layer of fiber glass reinforced resin, a second intermediate layer of organic resin mixed with protruding wood chips, and a backing layer of gypsum. The wood chips and the second intermediate layer protrude from the resin to engage the gypsum layer bonding it to the laminate. The chips have relatively low tensile strength and are bulky, on the order of one-fourth to one-half inch wide, so that the layer containing the chips must inherently be relatively thick, from 0.2 to 0.5 inches.
Briefly, the present invention comprises a multi-layer, fiber glass reinforced laminate having organic and inorganic layers and a process for making said laminate.
The first layer is an organic resin gel coat which is bonded to a second layer (reinforcing layer) of organic resin and reinforcing glass fibers. A third layer (bonding layer) comprises glass fibers sprayed onto the reinforcing layer and having a coating of organic resin applied to said glass fibers. The glass fibers of the bonding layer protrude therefrom and serve as means to engage a layer of glass fiber reinforced gypsum which is the fourth layer of the laminate product.
The organic resin gel coat may be applied to the surface of a mold, followed by the application of the glass fiber reinforced organic resin layer. The reinforcing layer is then rolled or otherwise compressed to densify it and remove entrapped air. The glass fibers of the bonding layer are dry sprayed onto the reinforcing layer while the reinforcing layer is still tacky. A small amount of organic resin is then misted onto the surface of the glass fibers of the bonding layer to promote adhesion of the fibers to each other and to the reinforcing layer. A layer of glass fiber reinforced gypsum is applied to the bonding layer, and the gypsum intimately surrounds the glass fibers of the bonding layer which protrude therefrom in random directions. The protruding fibers of the bonding layer mechanically engage the gypsum layer and provide adhesion between the gypsum layer and the organic resin layers. The laminate is strong and light weight and utilizes a minimum of the relatively expensive organic resin.
The sole drawing represents a schematic sectional view of the laminate product of the invention showing the various layers and their relationships to one another.
Throughout, reference numerals relate to the drawing.
1. The Plastic Surface Finish Coat
"Plastic surface finish coat" 1 may be any of the organic resin gel coat materials well known to the art, and may include a decorative and/or protective external layer bonded to a structural resin underlayer. Materials which may be used include the well known polyester or epoxy resin gel coats. Whereas it is preferred that the plastic finish coat 1 be a polyester or epoxy resin, acrylic or acrylonitrile-butadiene-styrene (ABS) resins may also be used. When using the acrylic or ABS resins, a previously formed film or sheet of the acrylic or ABS resin is employed as the exterior layer. Thereafter, the polyester resin/glass fiber reinforcing layer, the bonding layer of glass fibers and polyester mist coat, and the glass reinforced gypsum composition are applied to the acrylic or ABS film as hereinafter described.
The thickness of the plastic surface finish coat 1 is not critical. Generally, the plastic finish coat 1 may range from about 15 to about 25 mils in thickness with about 20 mils being presently preferred.
Materials conventionally employed in the gel coat art as adjuvants may be present. These include materials such as pigments, fillers, extenders, stabilizers, plasticizers or other additives.
2. The Reinforcing Layer
Reinforcing layer 2 is bonded to plastic surface finish coat 1 and consists of a castable organic resin capable of curing at room temperature. This layer is reinforced with fibers, preferably glass fibers, in an amount ranging from about 20% to 30% by weight. The cured thickness of the reinforcing layer generally will range from about 20 to about 125 mils with a thickness of 30 to 50 mils being presently preferred. The preferred organic resin comprises either a polyester or epoxy resin, depending upon the composition of plastic finish coat 1. Where the plastic finish coat 1 comprises polyester, acrylic, or ABS resins, the reinforcing layer 2 preferably comprises a polyester resin. Where the plastic finish coat 1 comprises an epoxy resin, however, the reinforcing layer preferably comprises an epoxy resin. The organic resin is catalyzed sufficiently to permit gelling within a reasonable time, for example 10 to 60 minutes, followed by a complete curing of the resin. The preferrred production technique employs room temperature gelling, however, the gelling or curing operation may be carried out at elevated temperatures.
Where reinforcing layer 2 is a polyester resin, it typically comprises polyesters of ethylenically unsaturated polycarboxylic acids, or anhydrides, with polyhydric alcohols, and co-polymerizable ethylenically unsaturated compounds. Optionally, a saturated polycarboxylic acid may be used in combination with the unsaturated acid or anhydride.
Polycarboxylic unsaturated acids useful in preparing the polyester resin include such acids as maleic, fumaric, mesaconic, citraconic, itaconic, and halo and alkyl derivatives of such acids and the like. The ethylenically unsaturated acids are conventionally employed in amounts from 10 to 100 mole percent, preferably 20 to 80 mole percent, of the total acid content of the polyester.
Useful saturated polycarboxylic acids include acids having only aromatic unsaturation as well as acids having fully saturated carbon-carbon linkages. These include such saturated dicarboxylic acids as: malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic and sebacic, and aromatic dicarboxylic acids such as phthalic, isophthalic, terphthalic, tetrachlorophthalic, and the like.
The corresponding anhydrides of the above-listed saturated and unsaturated polycarboxylic acids are, of course, equally useful in the preparation of the polyester resins and yield polyesters which have essentially the same properties as those made with the acids. The term "saturated polycarboxylic acids" is, throughout this disclosure, intended to include aromatic polycarboxylic acids and non-olefinically unsaturated polycarboxylic acids.
The polyhydric alcohols useful in preparing the polyesters include: ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, glycerol, neopentyl glycol, pentaerythritol, trimethylol propane, trimethylol ethane, and the like. The preferred polyols have a molecular weight of less than about 2000. Typically, they are employed in an equimolar ratio to the total acid content or a slight excess, as much as about 5 mole percent.
Polymerizable ethylenically unsaturated compounds useful in preparing the reinforcing layer compositions are those which crosslink with the unsaturated polyesters to form thermosetting materials. These include such monomers as: styrene, alpha-methyl styrene, divinyl benzene, vinyl acetate, allyl acetate, diallyl phthalate, diallyl succinate, diallyl adipate, diallyl sebacate, diallyl itaconate, diallyl maleate, diallyl fumarate, triallyl cyanurate, methyl acrylate, methyl methacrylate, hexyl acrylate, octyl acrylate, octyl methacrylate, and the like. The preferred monomers are liquid compounds soluble in the polyester components. Such monomers should preferably be free of non-aromatic conjugated double bonds. The amount of monomer employed in the composition is not critical but is usually sufficient to provide a liquid, flowable, interpolymerizable mixture. Ordinarily, the percentage of monomer will be between about 10 percent to about 60 percent of the total weight of the polyester and monomer.
The polyester composition may contain, if required, known inhibitors to prevent premature crosslinking or gelatin. Known inhibitors include quinonic or phenolic compounds, copper compounds or hydroxylamine derivatives and the like. Specific examples of useful inhibitors are: p-benzoquinone, 2,5-di-tert-butyl-quinone, hydroquinone, tert-butyl pyrocatechol, 3-isopropyl catechol, and chloranil.
Catalysts and promoters may be introduced into the polyester resin, usually at the time of application, to facilitate the cure. Catalysts include free radical producing compounds such as peroxides, hydroperoxides, peresters and diacylperoxides and azo nitriles. Benzoyl peroxide, methyl-ethyl ketone peroxide, lauroyl peroxide, cumene peroxide, tert-butyl benzoate, and 2,2 azobis isobutyronitrile are also examples of useful materials.
Promoters, usually used in combination with the catalyst, include cobalt naphthenate, dimethyl aniline, diethyl aniline, cobalt metal dispersions, vanadium pentoxide/phosphate solutions, manganese compounds, tertiary amines, and quaternary ammonium salts.
Where reinforcing layer 2 is based on an epoxy resin, the compositions employed are typically undiluted liquid resins which are conventionally two-component systems, i.e. the resin and catalyst or curing agent are separately packaged and admixed at the time of use.
Epoxy resins which may be used in these compositions include, for example, polyglycidyl esters, such as those obtainable by the reaction of di- or polycarboxylic acid with epichlorohydrin or glycerol dichlorohydrin in the presence of an alkali. Such polyglycidyl esters may be derived from aliphatic dicarboxylic acids, e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, or dimerised or trimerised linoleic acid, but are preferably derived from aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terphthalic acid, naphthalene-2,6-dicarboxylic acid, diphenyl-o,o'-dicarboxylic acid and ethylene glycol bis(p-carboxyphenyl)ether. Such specific polyglycidyl esters, are for example, diglycidyl phthalate, diglycidyl adipate and those diglycidyl esters which correspond to the average formula: ##STR1## in which A represents a divalent aromatic hydrocarbon radical, such as a phenylene group, and p represents a small, whole or fractional number.
Other epoxy resins which may be used include polyglycidyl ethers such as those obtainable by the interaction of a dihydric or polyhydric alcohol or a dihydric or polyhydric phenol with epichlorohydrin or a related substance (for example, glycerol dichlorohydrin) under alkaline conditions or, alternatively, in the presence of an acidic catalyst with subsequent treatment with alkali. These compounds may be drived from diols or polyols, such as ethylene glycol, diethylene glycol, triethylene glycol, propane-1,2-diol, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol, glycerol or N-acryldialkanolamines such as N-phenyldiethanolamine, or preferably, from dihydric or polyhydric phenols such as resorcinol, catechol, hydroquinone, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)methylphenylmethane, bis(4-hydroxyphenyl)tolylmethane, bis(4-hydroxyphenyl)sulphone and especially, 2,2-bis(4-hydroxyphenyl)propane or phenolformaldehyde condensation products.
There may further be employed aminopolyepoxides such as are, for example, obtained by the dehydrohalogenation of the reaction products of epihalohydrins and primary or secondary amines such as aniline, n-butyl-amine or bis(4-methylaminophenyl)methane, and products obtained by the partial or complete epoxidation of cyclic or acyclic polyolefins.
As curing agents to be used in the epoxy resin compounds there may be mentioned these conventionally employed as cross-linking agents for epoxy resins, for example amines containing at least two hydrogen atoms directly attached to nitrogen, e.g., aliphatic and aromatic primary and secondary amines such as mono- and di-butylamine, p-phenylenediamine, bis(p-aminophenyl)methane, ethylene-diamine, N,N-diethylenediamine, diethylenetriamine, tetra(hydroxyethyl)-diethylenetriamine, triethylenetetramine, tetraethylene-pentamine, piperidene, guanidine, and guanidine derivatives, such as phenylguanidine and diphenylguanidine, dicyanodiamide, polymers of aminostyrenes, and polyamino-amides, e.g., those prepared from aliphatic polyamines and dimerised and trimerised unsaturated fatty acids, isocyanates and isothiocyanates; polyhydric phenols, e.g. resorcinol, hydroquinone, 2,-bis(4-hydroxyphenyl)propane, phenol-aldehyde resins and oil-modified phenol-aldehyde resins; reaction products of aluminum alkoxides or phenolates with tautomeric-reacting compounds of the acetoacetic ester type; Friedel-Crafts catalysts, e.g., AlCl.sub.3, SnCl.sub.4, ZnCl.sub.2, BF.sub.3, and their complexes with organic compounds; phosphoric acid; and polycarboxylic acids and their anhydrides e.g., phthalic anhydride, methylenedimethylene-tetrahydrophthalic anhydride, dodecenylsuccinic anhydride, hexahydrophthalic anhydride, hexachloroendomethylene-tetrahydrophthalic anhydrides or endomethylenetetrahydrophthalic anhydrides, or their mixtures, or maleic or succinic anhydrides.
There may also be used catalytic hardeners, e.g. tertiary amines such as 2,4,6,-tris(dimethylaminomethyl)phenol, triethanolamines, or N-benzyldimethylamines; alkali metal alkoxides of alcohols such as 2,4-dihydroxy-3-hydroxymethylpentane; stannous salts of alkanoic acids, such as stannous octoate; and aluminum alkoxides.
Other classes of castable organic resins such as polyurethanes or polyamide-imide resins or the like may also be useful as reinforcing layer resins.
The reinforcing layer resin compositions can contain pigments, fillers, extenders, plasticizers or similar adjuvants conventionally employed in fiber reinforced structural compositions.
The preferred reinforcing fiber for the practice of this invention is chopped glass roving. However, glass strand mat may also be used. Glass fiber lengths may range from about 1/4 inch to about 1 inch with 1/2 inch lengths being preferred.
Other classes of reinforcing fiber may be used including inorganic fibers such as carbon, boron, alumina, asbestos and mineral wool. Organic fibers may also be used. Examples are polyester, polyamide, and cellulosic type fibers.
Bonding layer 3 comprises glass fibers which are bonded to reinforcing layer 2 and which protrude in random directions from the reinforcing layer 2. The fibers are coated with a controlled amount of organic resin. The organic resin may conveniently be, but need not be, the same resin employed in reinforcing layer 2. The amount of organic resin applied to the fibers of the bonding layer is sufficient to promote adhesion of the fibers to one another at their intersections and adhesion of the fibers to reinforcing layer 2, but insufficient to encapsulate the fibers so as to prevent the subsequently applied gypsum layer from intimately surrounding and engaging a substantial portion of the individual coated fibers on the surface of the bonding layer.
One of the critical factors in achieving a satisfactory laminate product is the amount of glass fibers per unit area (surface density) in the interface of the bonding layer 3 with the gypsum layer 4. It is preferred that the glass fibers of the bonding layer 3 be chopped glass roving applied in amounts ranging from 0.25 to 0.65 ounces per square foot of reinforcing layer surface area. Surface densities below 0.25 ounces per square foot and above 0.65 ounces per square foot do not provide good bonding strength between the gypsum layer 4 and the glass fibers of the bonding layer 3. It is preferred that the bond strength between these layers be at least about 150 psi as determined by ASTM C297-68. The organic resin used to coat fibers of bonding layer 3 is, preferably, a curable polyester or epoxy resin and may conveniently be the same resin used in reinforcing layer 2. The type of resin used in bonding layer 3 will depend upon the resin used in the reinforcing layer 2; i.e. polyester where the reinforcing layer 2 is polyester, and epoxy where the reinforcing layer 2 is opoxy.
The glass fibers of bonding layer 3 preferably range in length from 1/4 to 1 inch with about 1/2 inch lengths being presently preferred.
Gypsum layer 4 comprises hydrated calcined gypsum or hydrated calcium sulfate hemihydrate, commonly known as plaster of paris in the hydrated state. It may range in thickness from about 1/8 inch to 1 inch although this parameter is not critical and the layer may be thicker or thinner if desired. Gypsum layer 4 is reinforced with chopped fibers, preferably glass fibers of either chopped roving or chopped strand mat, ranging from about 1/2 to 4 inches in length with 1 inch being generally preferred. The glass fiber content of the gypsum may range from about 0.5 percent to 20 percent of the composition by weight, depending upon the consistency of the plaster.
"Consistency" may be defined as the pounds of water per 100 pounds of calcined gypsum (plaster). A "low consistency" composition may contain 24 to 32 pounds of water per 100 pounds of plaster, and in these compositions a lower fiber content (0.5-7%) is used. A "moderate consistency" employes from 32 to 50 pounds of water per 100 pounds of plaster, and a higher fiber content (7-10%) may be used. A "high consistency" composition uses from 50 to 90 pounds of water per 100 pounds of plaster, and the fiber content may range up to about 20% by weight.
The protruding glass fibers of bonding layer 3 are intimately surrounded by the reinforced gypsum layer providing an extremely strong, adherent bond between the inorganic and organic layers.
Throughout the laminate, while the reinforcing fibers are glass the fiber diameter may range from 36 to 48 microns or from type "G" to type "K". It is generally preferred that the glass fibers used in the practice of the present invention be coated with coupling or sizing agents conventionally used to promote bonding of glass fibers to organic resins. Bonding agents which may be employed include conventional formulations such as epoxy resins, silane or siloxane resins and other compositions such as methacrylic acid/chromium complex silane resins.
Additional layers may be applied to the gypsum layer as desired. For example, the gypsum may be coated to improve its appearance or to provide additional protection from moisture or to seal any protruding glass fiber ends.
With reference to FIG. 1, plastic surface finish coat 1 may be applied in a suitable mold (not pictured). Where the plastic finish coat 1 is a liquid it will be applied in any conventional manner desired, e.g., spraying or brushing, with spraying being preferred. Where plastic finish coat 1 is a previously formed film or sheet of acrylic or ABS resin it will simply be positioned in the mold and subsequent layers applied as described below.
Plastic finish coat 1, when applied as a liquid, is permitted to at least partially cure before reinforcing layer 2 is applied. Preferably, the reinforcing fiber and the organic resin of reinforcing layer 2 are sprayed simultaneously, in coverging streams, onto the plastic finish coat. Alternatively, the resin and fiber are applied intermittently to form the reinforcing layer. Conventional commercially available spray equipment may be used, capable of applying resin, catalyst, and chopped fiber in converging streams or independently permitting simultaneous or intermittent application of the resin and reinforcing fiber. After the reinforcing layer 2 is applied, and while it is still fluid, it is essential that it be rolled or brushed to remove the trapped air and densify the layer.
The glass fibers of bonding layer 3 are dry sprayed onto the reinforcing layer while it is still tacky, i.e. while the reinforcing layer is still fluid enough to permit the ends of the fibers of the bonding layer to partially embed themselves in the resin of the reinforcing layer 2. The protruding glass fibers of bonding layer 3 are then coated with the curable organic resin by "misting", i.e. the organic resin is applied in a fine, brief spray in an amount sufficient to bond the fibers to one another and to the reinforcing layer 2, but not so much as to cover the fibers and prevent the gypsum layer from surrounding them.
Bonding layer 3 and reinforcing layer 2 are then permitted to cure at room temperature for 10 to 60 minutes, depending upon the type and amount of catalyst used, to at least a gelled state before applying gypsum layer 4. The preferred production technique employs room temperature gelling, however, the gelling or curing operation may be carried out at elevated temperatures.
Gypsum layer 4 is applied by spraying or casting. Spraying is preferred but other methods may be used where desired. The gypsum and other layers are then permitted to harden sufficiently to be removed from the mold.
The mold employed may be made of any conventional materials such as metal, plastic or wood. Parting agents such as silicone lubricants will typically be applied to the mold to assist in removing the laminate products.
Subsequent layers may be applied in any manner that suits the material chosen, such as spraying, brushing, rolling or casting.
The article mold is cleaned and coated with a polyvinyl alcohol mold release agent. The plastic finish coat is applied to the surface of the mold using a spray gun to spray a catalyzed polyester gel composition. Methyl ethyl ketone peroxide is used as the catalyst at an amount of 1% by weight of the polyester gel composition. The mold is coated with a uniform polyester gel film of about 20 mils in the wet stage. The polyester gel coat is allowed to cure through the exothermic stage prior to applying the next layer of polyester resin.
The reinforcing layer of glass fiber reinforced all purpose polyester is applied to the polyester gel coat by the spray up method using an airless spray system equipped with a catalyzer and a glass chopper. The glass content in the reinforcing layer is about 20% by weight of the all purpose polyester/glass fiber composition. The glass fiber roving is chopped to about 0.5 inch lengths. Methyl ethyl ketone peroxide is again used as the catalyst at a level of about 1% by weight of all purpose polyester. The thickness of the reinforcing layer is about 30 mils. After the reinforcing layer is applied, the all purpose polyester/glass fiber composition is densified by rolling to ensure that all entrapped air is removed.
While the reinforcing layer is still wet and tacky, a layer of dry glass fibers, about 0.5 inches long, is spray applied to the reinforcing layer using a glass chopper to cut the fiber roving at a rate of about 1.5 lbs./minute. The amount of glass fibers per unit area is about 0.5 oz./ft..sup.2, approximately enough to cover the surface with a single layer of fibers. These glass fibers are not compressed into the polyester matrix and are allowed to protrude from the polyester surface. Thereafter, a light mist of the all purpose polyester and MEK peroxide catalyst are sprayed over the surface of the glass fibers without saturating them. The polyester resin is then allowed to gel at room temperature.
A structural base of glass reinforced gypsum is applied to the polyester laminate. The plaster formulation is used in combination with 1 inch glass fibers. Hot water (120 (HYDROCAL PLW plaster) at a consistency of about 65 lbs. of water to 100 lbs. of plaster. The mixing procedure for batch production involves soaking the plaster in the mixng water for 2 minutes and then mixing the wetted plaster with a high shear mixer for 4 minutes. The spray up equipment used to apply the glass reinforced gypsum is calibrated to yield a glass content of about 10% by weight of the dried gypsum/glass fiber composition.
A neat coat of the plaster (containing no glass fibers) is sprayed onto the glass fibers protruding from the polyester surface. Then, the glass chopper is activated and a layer of glass reinforced plaster is spray applied. The total thickness of the glass reinforced gypsum layer is about 0.25 inches.
After the gypsum has set and dried, the laminate is removed from the mold and is placed in an air circulating dryer set at 110 F. to complete the drying.
An acrylic sheet which has been vacuum formed or thermally shaped into an acrylic shell is made into a laminate product having a glass reinforced gypsum structural base. The interior surface of the acrylic shell is cleaned to ensure that the surface is free of oil, grease and mold release agent. A reinforcing layer of glass reinforced all purpose polyester is spray applied to the interior surface of the acrylic shell. This is done by the spray up method using an airless system equipped with a catalyzer and a glass chopper. Methyl ethyl ketone peroxide is used as the catalyst at a level of about 1.5% by weight of the polyester composition. The glass fiber roving is chopped to about 1 inch lengths and is incorporated into the polyester at a content of about 15% by weight of the polyester resin/glass fiber composite. The polyester reinforcing layer has a thickness of about 40 mils. After the spray application is completed, the glass fiber reinforced polyester layer is densified by using a brush to ensure that all entrapped air is removed.
While the polyester resin in the reinforcing layer is still tacky, a layer of dry glass fibers about 0.5 inches in length is applied thereto using a glass chopper. The amount of glass fiber per unit of surface area is about 0.25 oz./ft..sup.2. The glass chopper is calibrated to cut the roving at a rate of about 1.25 lbs./minute. The glass fibers are spray applied in such a manner that many of the fibers protrude from the polyester resin surface. These protruding fibers are then coated with a light mist of the catalyzed all purpose polyester without saturating them. The polyester coating is then allowed to get at room temperature.
A structural base of glass reinforced gypsum is applied to the surface having the protruding glass fibers. The plaster formulation is prepared as described in Example 1, with the exception of the spray up equipment which is calibrated to yield a glass content of about 12% by weight of the dried gypsum/glass fiber composition.
A neat coat of the plaster (HYDROCAL PLW plaster) containing no glass fibers is sprayed onto the glass fibers protruding from the polyester surface. Then, the glass chopper is turned on and a layer of glass fiber reinforced plaster is spray applied. The total thickness of the glass reinforced gypsum layer is about 0.5 inches. The gypsum is allowed to set and dry at room temperature, afterwhich, the laminate is placed in an air circulating dryer set at about 120
A polyester gel coat/glass reinforced gypsum laminate was made in accordance with the procedure described in Example 1. The glass fibers in the bonding layer had a length of 0.5 inches and the bonding fibers were applied in varying surface densities. The bond strength was tested flatwise in tension using 2 inch ASTM C297-68. The results are shown below:
______________________________________Surface Density Bond Strength Location of Failure______________________________________0.25 oz./ft..sup.2 148 psi In gypsum layer0.5 oz./ft..sup.2 289 psi Bonding Layer/Gypsum Layer Interface0.75 oz./ft..sup.2 36 psi Bonding Layer/Gypsum Layer Interface______________________________________
In the sample having the 0.25 oz./ft..sup.2 surface density, the failure occurred in the gypsum, and therefore, the real bond strength is higher than 148 psi. Quite unexpectedly, the sample having the 0.75 oz./ft..sup.2 surface density had a sharp reduction in bond strength. Since it is preferred that the bond strength be at least 150 psi, the sample having the 0.75 oz./ft..sup.2 surface density was unacceptable.
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International Journal of Chemical Engineering
Volume 2012 (2012), Article ID 316891, 2 pages
Advances in Mixing Technology: Recent Advances in Mixing Research and Development
1Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
2Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan
3Department of Mechanical Design Engineering, Andong National University, Songchon-Dong, Kyungbuk, Andong 760-749, Republic of Korea
4Department of Civil Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
Received 2 October 2012; Accepted 2 October 2012
Copyright © 2012 Shunsuke Hashimoto et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Mixing has been one of essential unit operations for chemical engineering processes. Among a number of mixers, stirred tanks that are available in a wide variety of tank sizes and impeller shapes are the most frequently adopted to homogenize different substances and to conduct chemical reactions in industrial chemical processes. In addition, there are various technologies for fluid mixing: static mixer, micromixer, unsteady agitation, eccentric agitation, and so on. Recently in various industrial processes, a wide range of operation for stirred tank is required depending on purposes and conditions, and high efficiency on mixing has been strongly required. In addition, the techniques of computer simulation analyses by the use of CFD software have been dramatically developed, which is essential to analyze the mixing mechanism. The main goal of this special issue was to gather contributions dealing with the latest breakthrough of mixing techniques. There is a collection of twelve papers in this special issue focused on mixing fundamental (2 papers), multiphase mixing (3 papers), chemical reactive mixing for metallurgical industry, and biotechnology (4 papers), and new technology of mixing (3 papers) ranging in topic from laminar-to-turbulent mixing by means of both experimental analyses and numerical simulations. The highlights of each paper are introduced as follows.
In the paper entitled by “Design mixers to minimize effects of erosion and corrosion erosion”, E. E. Janz and J. Fasano from Chemineer, Inc. provide techniques for minimizing the wear on impellers cover the choice of impeller, size and speed of the impeller, alloy selection, and surface coating or coverings. An example is provided as well as an assessment of the approximate life improvement.
In the work entitled by “Effect of impeller agitation on preparation of tetra-n-butyl ammonium bromide semi-clathrate hydrate slurries”, S. Hashimoto et al. from Osaka University, which shows the effect of impeller agitation on particle size distribution and aggregation of tetra-n-butyl ammonium bromide (TBAB) semiclathrate hydrate slurries. The slurries containing TBAB solution and its semiclathrate hydrate have attracted a lot of interest as latent heat transport media. First of all, the effects of impeller rotational speed and impeller type on the particle size and frequency of aggregation are investigated. The results suggest that the particle size distribution and the frequency of particle aggregation are strongly affected by the intensity of shear rate and its uniformity, which is controllable with impeller type and its rotation speed.
In the research entitled by “Correlation of power consumption for several kinds of mixing impellers”, Y. Kato et al. review the correlations of power consumption in nonbaffled and baffled agitated vessels with several kinds of impellers, which are developed in a wide range of Reynolds numbers from laminar-to-turbulent flow regions. The power correlations are based on Kamei and Hiraoka’s expressions for paddle and pitched paddle impellers. The calculated correlation values agree well with experimental ones, and the correlations will develop the other types of impellers.
In the paper entitled by “Effect of temperature change on geometric structure of isolated mixing regions in stirred vessel”, N. Ohmura et al. show the effect of temperature change on the geometric structure of isolated mixing regions (IMRs) in a stirred vessel by the decolorization of fluorescent green dye by acid-base neutralization. The step temperature-change can dramatically reduce the elimination time of IMRs, as compared with a steady temperature operation. During the transient process from an initial state to disappearance of IMR, the IMR showed interesting three-dimensional geometrical changes, that is, simple torus with single filament, simple torus without filaments, a combination of crescent shape and circular tori, and doubly-entangled torus.
In the work entitled by “Phosphorus removal from wastewater using oven-dried alum sludge”, S. A. Rashid and W. T. Mohammed deal with the removal of phosphorus from wastewater by using oven-dried alum sludge (ODS) as an adsorbent that was collected from Al-Qadisiya treatment plant (Iraq). The results show that the percent removal of phosphorus increases with the increase of oven dried alum sludge dose, but thr pH of solution has insignificant effect. In addition, the oven-dried alum sludge was effective in adsorbing phosphorus, and percent removal of phosphorus reaches 85% with increasing of contact time.
In the paper entitled by “Laminar mixing in stirred tank agitated by an impeller inclined”, K. Takahashi et al. show the mixing performance in a vessel agitated by an impeller inclined itself, which is considered one of the typical ways to promote mixing performance by the spatial chaotic mixing. The effect of eccentric position of inclined impeller on mixing time was also studied and a significant reduction of mixing time is observed. To confirm the experimental results, the velocity profiles are calculated numerically and two novel numerical simulation methods are proposed.
In the research entitled by “Characterization of minimum impeller speed for suspension of solids in liquid at high solid concentration, using gamma ray densitometry”, P. A. Tanguy et al. exhibit the limitations of applying conventional measurement techniques for the accurate characterization of critical impeller speed for just off-bottom suspension (Njs) at high solid concentrations. Subsequently, the Gamma-Ray Densitometry technique for characterizing Njs is introduced, which can overcome the limitations of previous experimental techniques. The theoretical concept of this method is explained and experimental validation is presented to confirm the accuracy of the Gamma-Ray Densitometry technique. By utilizing the similarity to the incipient movement of solid particles in other systems, a theoretical model for Njs prediction is presented.
In the work entitled by “The effects of mixing, reaction rates and stoichiometry on yield for mixing sensitive reactions—Part I: model development”, S. M. Kresta et al. provide the model and design of the effect of mixing, reaction rates, and stoichiometry on yield for mixing sensitive reactions: competitive-consecutive and competitive-parallel reactions. A detailed investigation of the effects of initial mixing condition (striation thickness), dimensionless reaction rate ratio and reaction stoichiometry on the yield of desired product shows that the stoichiometry has a considerable effect on yield. All three variables are found to interact strongly. Model results for 12 stoichiometries are used to determine the mixing scale and relative rate ratio, needed to achieve a specified yield for each reaction scheme. The results show that all three variables need to be considered when specifying reactors for mixing sensitive reactions. Incidentally, Professor S. K. also organizes another paper.
In the paper entitled by “Effect of mixing on microorganism growth in loop bioreactors”, A. M. Al Taweel et al. show the impact of mixing on the promotion of microorganism growth rate using a multiphase forced circulation pipe-loop reactor model capable of identifying conditions under which it is possible to convert natural gas into single cell protein (SCP). The impact of mixing in the interphase mass transfer is found to exert a critical role in determining the overall productivity of the bioreactor, particularly at the high cell loadings needed to reduce the capital costs associated with the large-scale production needed for the production of relatively low-value SCP in a sustainable manner.
In the paper entitled by “Investigation of the pulsed annular gas jet for chemical reactor cleaning”, C. V. Fedorovich et al. provide the study of aerodynamic efficiency of the impulse system carried by numerical modeling and experimentally with the help of a specially created experimental facility. The characteristics of the pulsed jets mixing are investigated and designed pulsed peelings system has shown high efficiency and reliability in functioning that allows us to recommend it for wide spreading in chemical industry.
The research of S. Ibrahim entitled by “Zwietering’s equation for the suspension of porous particles and the use of curved blade impellers” reveals Njs of porous palm shell activated carbon (PSAC) particles for a few impeller blades. Specific power per unit mass for all three impellers showed reduction towards minima as the concentration of particles increased. The result means that the Zwietering equation can be used to predict suspension for porous particles with adjustment to the solid particle density. S values for curved-blade impellers are presented for the first time.
In the work entitled by “The effects of mixing, reaction rates and stoichiometry on yield for mixing sensitive reactions—part II: design protocols”, S. M. Kresta et al. provide the design strategy of the effect of mixing, reaction rates, and stoichiometry on yield for mixing sensitive reactions.
The guest editors are also sincerely thankful to the editorial staff for the support, guidance, and efforts in welcoming this series of papers on a timely subject. We hope that this special issue will be available for the future innovation of mixing technology.
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This article is
- freely available
Flexible Temperature Sensor Array Based on a Graphite-Polydimethylsiloxane Composite
Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan
* Author to whom correspondence should be addressed.
Received: 12 January 2010; in revised form: 12 March 2010 / Accepted: 20 March 2010 / Published: 9 April 2010
Abstract: This paper presents a novel method to fabricate temperature sensor arrays by dispensing a graphite-polydimethylsiloxane composite on flexible polyimide films. The fabricated temperature sensor array has 64 sensing cells in a 4 × 4 cm2 area. The sensor array can be used as humanoid artificial skin for sensation system of robots. Interdigitated copper electrodes were patterned on the flexible polyimide substrate for determining the resistivity change of the composites subjected to ambient temperature variations. Polydimethylsiloxane was used as the matrix. Composites of different graphite volume fractions for large dynamic range from 30 ºC to 110 ºC have been investigated. Our experiments showed that graphite powder provided the composite high temperature sensitivity. The fabricated temperature sensor array has been tested. The detected temperature contours are in good agreement with the shapes and magnitudes of different heat sources.
Keywords: composite; temperature sensor array; flexible substrate
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Cite This Article
MDPI and ACS Style
Shih, W.-P.; Tsao, L.-C.; Lee, C.-W.; Cheng, M.-Y.; Chang, C.; Yang, Y.-J.; Fan, K.-C. Flexible Temperature Sensor Array Based on a Graphite-Polydimethylsiloxane Composite. Sensors 2010, 10, 3597-3610.
Shih W-P, Tsao L-C, Lee C-W, Cheng M-Y, Chang C, Yang Y-J, Fan K-C. Flexible Temperature Sensor Array Based on a Graphite-Polydimethylsiloxane Composite. Sensors. 2010; 10(4):3597-3610.
Shih, Wen-Pin; Tsao, Li-Chi; Lee, Chian-Wen; Cheng, Ming-Yuan; Chang, Chienliu; Yang, Yao-Joe; Fan, Kuang-Chao. 2010. "Flexible Temperature Sensor Array Based on a Graphite-Polydimethylsiloxane Composite." Sensors 10, no. 4: 3597-3610. | <urn:uuid:a32c4205-b1c8-411e-87f0-b2e93c7e4e30> | {
"__label__manufacturing": 0.9324022531509399,
"__label__other": 0.0676177442073822,
"date": "2013-05-24T08:31:12Z",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368704392896/warc/CC-MAIN-20130516113952-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"language": "en",
"language_score": 0.7960392236709595,
"token_count": 547,
"url": "http://www.mdpi.com/1424-8220/10/4/3597"
} |
Ni-based superalloys possess desirable high-temperature properties including strength, ductility, fracture toughness as well as resistance to creep and oxidation. An important factor for strengthening mechanism is the microstructure of the alloy which consists of ordered γ’- Ni3Al precipitates within a γ (Ni-Al) matrix. In addition, a variety of substitutional and interstitial elements like Cr, Ta, Re, Ru, Ti, W, Mo, C, S etc. play a crucial role in strengthening of these alloys. It is thus important to understand the electronic structure and diffusion of these elements. Using density functional theory methods with plane-wave basis sets we determine the partitioning behavior of alloying elements in the interface. We also systematically explore the energetics and kinetics of diffusion of Cr, Mo, C, and O in the bulk and across the γ/γ'’ interface. We use transition state theory combined with nudged elastic band method to determine the transition paths and diffusion activation barriers. | <urn:uuid:17457af2-ca37-4ca2-a86b-6a9ba413a3bf> | {
"__label__manufacturing": 0.9893733859062195,
"__label__other": 0.010646654292941093,
"date": "2013-05-24T08:31:11Z",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368704392896/warc/CC-MAIN-20130516113952-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"language": "en",
"language_score": 0.8896821737289429,
"token_count": 211,
"url": "http://www.programmaster.org/PM/PM.nsf/ApprovedAbstracts/F2AB6AD5E48E0492852575F4006C952F?OpenDocument"
} |
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in Data Studio
Manu-FineWeb
Manu-FineWeb is a high-quality, large-scale corpus specifically curated for the manufacturing domain. It was extracted from the 15-trillion-token FineWeb dataset and refined to facilitate efficient domain-specific pretraining for models like ManufactuBERT.
Dataset Summary
- Developed by: Robin Armingaud and Romaric Besançon (Université Paris-Saclay, CEA, List)
- Statistics: 2B tokens/4,5 million documents
Construction & Curation
The dataset was built using a rigorous pipeline to ensure high relevance and low redundancy:
1. Domain-Specific Filtering
A fastText classifier was trained on a positive set of manufacturing-specific sources to filter the general FineWeb corpus. The training sources included:
- Elsevier: Abstracts from industrial and manufacturing engineering journals.
- ArXiv: Abstracts from categories like physics, computer science, and engineering related to industrial processes.
- Wikipedia: Articles from manufacturing and engineering categories.
- BigPatent: Patent descriptions containing "manufacturing" keywords.
2. Multi-Stage Deduplication
To improve training efficiency, the 10B token corpus was reduced by ~80% through:
- Lexical Deduplication (MinHash): Eliminating near-exact text duplicates.
- Semantic Deduplication (SemDeDup): Identifying and removing semantically redundant documents using sentence embeddings (all-MiniLM-L6-v2), leaving only the most representative data points.
Citation
If you use ManufactuBERT in your research, please cite:
@misc{armingaud2025manufactubertefficientcontinualpretraining,
title={ManufactuBERT: Efficient Continual Pretraining for Manufacturing},
author={Robin Armingaud and Romaric Besançon},
year={2025},
eprint={2511.05135},
archivePrefix={arXiv},
primaryClass={cs.CL},
url={https://arxiv.org/abs/2511.05135},
}
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Size of downloaded dataset files:
6.06 GB
Size of the auto-converted Parquet files:
6.06 GB
Number of rows:
4,567,285
Models trained or fine-tuned on cea-list-ia/Manu-FineWeb