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2014-01-01
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Cryogenic landslides on saline marine sediments are widely distributed in Typical tundra bioclimatic subzone of the Yamal Peninsula. Interrelation between the height and productivity of the willow tundra, and activation of cryogenic processes are discussed. It is supposed that high willow canopies are the indicators of ancient landslide activities and may serve as fundamental guide for mapping of landslides in the region. Various procedures are proposed to evaluate the relative age of the landslides. They include, study of the succession of vegetation cover, ash content in each vegetation group, groundwater and sediment chemistry on the landslide-affected slopes. It is shown that the landslide process causes desalinization of marine sediments and enriches the active layer with salts. This is an important peculiarity of cryogenic landslides in the region with saline permafrost distribution.
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Geochemistry of Plant-Soil-Permafrost System on Landslide-Affected Slopes, Yamal, Russia as an Indicator of Landslide Age
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10.1007/978-3-319-00867-7_9
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2014-01-01
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We review recent results on biomaterial nanostructured layers transferred by matrix-assisted pulsed laser evaporation (MAPLE). The chapter is organized according to three main applications of these nanostructures: drug delivery systems, biosensing and biomimetic coating of metallic implants. The synthesized layers were optimized based upon the results of investigations performed by physical–chemical methods. Biocompatibility and bioactivity were assessed by dedicated in vitro tests. From the first category we chose the composite alendronate–hydroxyapatite (HA). The coating of metallic implants with these layers demonstrated to enhance human osteoblasts proliferation and differentiation, while inhibiting osteoclasts growth, with benefic effects for the treatment of osteoporosis. Enzyme ribonuclease A (RNase A) immobilized on solid supports has applications in control of the enzymatic reaction, and improved stability as compared to the free enzyme. The results by reversed-phase high-performance liquid chromatography showed that immobilization process does not affect the RNase A behavior. The transfer of pure levan and oxidized levan was obtained by MAPLE without any addition of plasticizers or pigments. The nanostructures exhibited high specific surface areas fully compatible with their potential use in drug delivery systems. For the second application, we refer to the transfer and immobilization of IgG molecules. We investigated the effect of the lipid addition in the initial solution upon the protein thin films adhesion to substrates. From the third class, we selected magnesium substituted octocalcium phosphate (OCP) and strontium substituted OCP deposited by MAPLE on Ti substrates which proved to enhance osteoblast activity and differentiation. We conclude that under optimized conditions, the thin films obtained by MAPLE were similar in composition, morphology and structure with the base material, and most likely preserved their functionality and biological performances.
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Biomaterial Thin Films by Soft Pulsed Laser Technologies for Biomedical Applications
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10.1007/978-3-319-02898-9_11
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2014-01-01
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Electron paramagnetic resonance (EPR) spectroscopy for the assignment of H_6 ^+ and its isotopomers, analysis of large precessional motion of them, and isotope condensation of H_6 ^+ in solid parahydrogen at cryogenic temperature is treated in this chapter. The structure of H_6 ^+ consisting of an H_2 ^+-core sandwiched with two side-on H_2s is confirmed to have D _2 symmetry by the comparison of the experimental hyperfine coupling constants (HFCC) with the theoretical ones. The substitution of one side-on H_2 with D_2 induced distortion of the spin density and nonequivalent HFCCs on the H_2 ^+-core indicating that the quantum effect due to nuclear motion cannot be ignored in this system. Rotational states of side-on D_2 and H_2 are attributable to J = 0 from the corresponding nuclear spin states of I = 0 and 0, 2 for H_2 and D_2, respectively. The H_6 ^+ ion migrates via hole hopping diffusion of H_2 ^+-core in solid parahydrogen, and turns into more stable H_4D_2 ^+ or H_2D_4 ^+ ion when it meets D_2 molecules. During the diffusion, H_6 ^+ and H_4D_2 ^+ are in large precessional motion as indicated by an analysis of the anisotropic HFCCs.
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Hydrogen Molecular Ions in Solid Parahydrogen: EPR Studies at Cryogenic Temperatures
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10.1007/978-3-319-09216-4_4
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2014-01-01
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The paper discusses development of a number of cryogenic and channel processes as well as their paragenetic complexes. In small river basins these complexes form (a) landslide-affected slopes and landslide cirques, (b) river valleys. Up to half of the small river basins’ area in the upstream is subject to cryogenic processes. The vast majority (80 %) of these processes are cryogenic landslides. Other slope processes are interconnected to cyclicity of cryogenic landsliding. They appear between the landsliding cycles, lasting 200–400 years. Cryogenic landsliding within a paragenetic complex of processes is a leading and fast process. Between the active phases of cryogenic landsliding, thermoerosion and thermokarst develop. These processes can be considered accompanying slower processes. Lowering of the surface per landsliding cycle is on average 0.9 m in the upper part of the slope and up to 1.6 m in the lower part. This corresponds to the surface denudation of 4–6 mm per year. Subsequent processes of thermoerosion and thermokarst are responsible for lowering of the surface to significantly higher degree (0.6–1.05 m).
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Cryogenic Landslides in Paragenetic Complexes of Slope and Channel Processes in the Central Yamal Peninsula
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10.1007/978-3-319-04996-0_70
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2014-01-01
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The paper discusses the development of a number of cryogenic and channel processes, as well as their paragenetic complexes. In small river basins, these complexes form (a) landslide-affected slopes and landslide cirques, (b) river valleys. Up to half of the small river basins’ area in the upstream is subject to cryogenic process. The vast majority (80 %) of these processes are cryogenic landslides. Other slope processes are interconnected to cyclicity of cryogenic landslide. They appear between the landslide cycles, lasting between 200–400 years. Cryogenic landslides within paragenetic complexes are rapid and violent process. Thermoerosion and thermokarst develop between the active phases of cryogenic landslides. These processes can be considered to be accompanying slow processes. Lowering of the surface per landslide cycle is on average of 0.9 m in the upper part of the slope and up to 1.6 m in the lower part. This corresponds to surface denudation of 4–6 mm per year. Subsequent processes of thermoerosion and thermokarst are responsible for lowering the surface to significantly higher degree (0.6–1.05 m).
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Cryogenic Landslides in Paragenetic Complexes of Slope and Channel Processes in the Central Yamal Peninsula
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10.1007/978-3-319-00867-7_21
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2014-01-01
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The combination of rapid freeze quenching (RFQ) with resonance Raman (RR) spectroscopy represents a unique tool with which to investigate the nature of short-lived intermediates formed during the enzymatic reactions of metalloproteins. Commercially available equipment allows trapping of intermediates within a millisecond to second time scale for low-temperature RR analysis resulting in the direct detection of metal–ligand vibrations and porphyrin skeletal vibrations in hemoproteins. This chapter briefly discusses RFQ-RR studies carried out previously in our laboratory and presents, as a practical example, protocols for the preparation of RFQ samples of the reaction of metmyoglobin with nitric oxide (NO) under anaerobic conditions. Also described are important controls and practical procedures for the analysis of these samples by low-temperature RR spectroscopy.
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Characterizing Millisecond Intermediates in Hemoproteins Using Rapid-Freeze-Quench Resonance Raman Spectroscopy
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10.1007/978-1-62703-794-5_8
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2014-01-01
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The purpose of this research was to examine the surface roughness in turning EN-8d alloy steel using HSS tool of grade M-42. Cryogenic treatment of tool was done, and comparison was made for surface roughness between untreated and cryogenic treated tool (CT). In this research work, central composite face-centered design approach of response surface methodology was applied to study the impact of machining parameters on surface roughness for CT. Mathematical model for surface roughness was developed to achieve optimum selection of machining parameters.
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Analysis of Roughness in Turning of EN-8D Alloy Steel Using Cryogenically Treated HSS Tool
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10.1007/978-81-322-1859-3_36
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2014-01-01
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We have investigated a composite of cubic α-ZrW_2O_8 and epoxy with a high ceramic loading for its thermal expansion properties at cryogenic temperatures. The composite was fabricated by allowing the ceramic to sediment in the epoxy resin before curing, using only the dense bottom fraction of the composite for further measurements. Density measurements and thermogravimetric analysis showed that the samples repeatably consisted of approximately 60 vol% tungstate without significant voids. The coefficient of thermal expansion was measured by dilatometry at temperatures from 25 to 300 K, and we found negative thermal expansion occurring at temperatures below about 100 K. The observed behavior is consistent with predictions produced by a variational model, which shows that the high ceramic loading is necessary to reliably achieve negative thermal expansion in the composite. The composite has potential applications as compensators for unwanted thermal expansion at low temperatures and for fiber-optic cryogenic temperature sensors.
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Negative thermal expansion in a zirconium tungstate/epoxy composite at low temperatures
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10.1007/s10853-013-7716-8
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2013-12-01
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Purpose The purpose of this study was to investigate the colloidal structures formed on digestion of medium chain triglyceride (MCT) with a specific objective of identifying and characterizing a previously reported vesicular phase, which has been linked to supersaturation and anomalous digestion kinetics, and to evaluate the influence of lipid mass and enzyme inhibition on self assembled structure. Methods MCT was digested in vitro and nanostructure was monitored in real time using synchrotron small angle X-ray scattering (sSAXS), and morphology was studied using cryogenic transmission electron microscopy (cryo-TEM). Results Formation of the putative vesicular phase formed on digestion of MCT was confirmed and its structural attributes were determined. Vesicle formation was dependent on lipid mass and bile salt concentration. The use of enzyme inhibitor for offline analysis of lipolysis samples did influence structural aspects of the digestion medium when compared to real time evaluation. Conclusions The formation of a vesicular phase was directly linked to the kinetics of lipid digestion. Vesicle formation is linked to lipid mass, or more specifically the ratio of lipid to bile salts present in the digestion mixture. Inhibition of lipase to halt digestion during sampling for offline analysis must be done with caution as structural aspects were shown to differ for the MCT digests with and without inhibitor present.
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Structural Aspects of Digestion of Medium Chain Triglycerides Studied in Real Time Using sSAXS and Cryo-TEM
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10.1007/s11095-013-1108-2
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2013-12-01
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This paper describes ultrapurification of isotopically enriched calcium and molybdenum compounds and ^40Ca^100MoO_4 calcium molybdate growth charge in order to remove radioactive uranium, thorium, and radium impurities. ^40Ca^100MoO_4 single crystals grown from such charges are needed for the fabrication of scintillator elements of the cryogenic detector for the AMoRE project: a search for ^100Mo neutrino-less double-beta decay.
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Ultrapurification of isotopically enriched materials for ^40Ca^100MoO_4 crystal growth
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10.1134/S0020168513120029
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2013-12-01
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In metal cutting, the choice of cooling method influences the deformation mechanism, which is related to the dimensional accuracy and surface finish of the parts. The deformation mechanism of titanium alloys under machining conditions is known to be very different from that of commonly used industrial materials. Therefore, the effect of cooling methods on dimensional accuracy and surface finish in machining titanium is of particular interest. This paper investigates experimentally and analytically the influence of cooling method and cutting parameters on two major dimensional accuracy characteristics of a turned titanium part—diameter error and circularity, and surface finish. Data were analyzed via three methods: traditional analysis, Pareto ANOVA, and Taguchi method. The findings indicate that the cooling method has significant effect on circularity error (contribution ratio 76.75 %), moderate effect on diameter error (contribution ratio 25.00 %), and negligible effect on surface finish (contribution ratio 0.16 %).
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Effect of cooling methods on dimensional accuracy and surface finish of a turned titanium part
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10.1007/s00170-013-5223-3
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2013-12-01
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In order to improve depiction of pressure variation and investigate the interrelation among the physical processes in propellant tanks, a 2D axial symmetry Volume-of-Fluid (VOF) CFD model is established to simulate a large-sized liquid propellant tank when the rocket is preparing for launch with propellant loaded at the launch site. The numerical model is considered with propellant free convection, heat transfer between the tank and the external environment, thermal exchange between propellant and inner tank wall surfaces, gas compressibility, and phase change modeled under the assumption of thermodynamic equilibrium. Vaporization rate of the vented LH2 tank and prediction of pressure change in the tank pressurized with GHe are obtained through simulation. We analysis the distributions of phase, temperature, and velocity vectors to reveal interactions among the propellant’s own convection motion, heat transfer and phase change. The results show that the vaporization rate is mainly affected by heat leaks though the tank wall when the tank is vented, but it does not completely accord with the trend of the leakage because of convection motion and temperature nonuniformity of the liquid propellant in the tank. We also find that the main factors on pressure variation in the pressurized tank are the heat transfer on the tank wall surface bonding the ullage and propellant vaporization which has comparatively less influence.
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Simulation Research of Vaporization and Pressure Variation in a Cryogenic Propellant Tank at the Launch Site
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10.1007/s12217-013-9340-2
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2013-11-01
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We discuss the mode I energy release rate of a rectangular piezoelectric material with a crack under electromechanical loading at cryogenic temperatures. A crack was created normal or parallel to the poling direction, and electric fields were applied parallel or normal to the poling. A plane strain finite element analysis was carried out, and the effects of electric field and localized polarization switching on the energy release rate were discussed for the piezoelectric ceramics at cryogenic temperatures.
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Effects of electric field and poling on the mode I energy release rate in cracked piezoelectric ceramics at cryogenic temperatures
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10.1007/s00707-013-0949-4
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2013-11-01
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Electronic components which are able to work at cryogenic temperatures are demanded in cryogenic instruments, high sensitivity measurement systems, space missions, medical diagnosis among other applications. Different non-cryogenic commercial electronic components have been characterized between room temperature and −196°C. A simple measurement technique, taking advantage of the temperature gradient inside a partially empty LN_2 Dewar vessel has been used. The results of the electrical characterization show that some of these components can be used at cryogenic temperatures with a reasonable performance even if their specifications datasheets state the contrary.
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Characterization of commercial-off-the-shelf electronic components at cryogenic temperatures
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10.1134/S0020441214010187
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2013-10-01
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Residual stresses in 30 vol.% magnesium borate whisker-reinforced 2024 aluminum matrix composites have been determined by a nanoindentation method which takes into consideration pile-up and sink-in effects on indentation contact depth. Owing to the thermal mismatch and the large difference in elasticity modulus between the Al matrix and MBO whiskers, tensile residual stress was introduced to Al matrix material during fabrication. It was found that the solution treatment reduced the tensile residual stress by producing interfacial component and dislocations in the composites. Cryogenic cooling released the stress via reversing the tensile residual stress to compression in the matrix, which was more effective than solution treatment to release the tension stress in the composites. The combination of the solution treatment and the cryogenic cooling provided the most effective procedure to release the residual stress in the composites, which reduced the tensile residual stress from 232.6 to 56.5 MPa, i.e., 76% reduction. Meanwhile, no cracks were observed in the composite when processed with such sudden thermal shocking.
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Determination and Relaxation of Residual Stress in 2024 Al-30 vol.% Magnesium Borate Whisker Composites
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10.1007/s11665-013-0599-7
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2013-10-01
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A 10-bit 500 kHz low-power successive approximation register (SAR) analog-to-digital converter (ADC) for cryogenic infrared readout circuit is proposed. To improve the simulation accuracy of metal-oxide-semiconductor field-effect transistors (MOSFETs), corresponding modification in device model is presented on the basis of BSIM3v3 with parameter extraction at 77K. Corresponding timing is adopted in comparator to eliminate the influence caused by abnormal performance of MOSFETs at 77 K. The SAR ADC is fabricated and verified by standard 0.35 μm complementary metal oxide semiconductor (CMOS) process. At 77 K, measurement results show that signal to noise and distortion ratio (SNDR) is 54.74 dB and effective number of bits (ENOB) is 8.8 at the sampling rate of 500 kHz. The total circuit consumes 0.6mW at 3.3V power supply.
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A cryogenic 10-bit successive approximation register analog-to-digital converter design with modified device model
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10.1007/s12204-013-1436-8
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2013-09-13
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Designing nanoparticles for delivery of neurotrophic proteins
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10.1186/1750-1326-8-S1-O16
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2013-09-01
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The ineffectiveness of conventional coolants and their adverse impact on the environment have led to the use of cryogenic LN2 (liquid nitrogen) as an alternative coolant, which is effective in reducing the grinding zone temperature, and providing better lubrication, in addition to being a clean technology. The sol-gel (SG) alumina grinding wheel, with a self-sharpening characteristic, is used for the experiment. The grinding experiments were conducted on AISI 316 stainless steel under the three environments of dry, wet and cryogenic cooling. The Cryogenic coolant delivers a reduction of about 32% in the grinding forces, 30–49% improvement in the surface roughness, and 45–49% lesser temperature even at higher material removal rates. Cryogenic cooling produces fewer surface defects compared to dry and wet cooling. The effects of the LN2 delivery pressure on the machining zone, in terms of the grinding forces, surface roughness, and grinding zone temperature, were also studied.
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Effect of cryogenic cooling and sol-gel alumina wheel on grinding performance of AISI 316 stainless steel
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10.1016/j.acme.2013.03.002
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2013-09-01
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AZ91 magnesium alloy was subjected to a deep cryogenic treatment. X-ray diffraction (XRD), scanning electronic microscopy (SEM), and transmission electronic microscopy (TEM) methods were utilized to characterize the composition and microstructure of the treated samples. The results show that after two cryogenic treatments, the quantity of the precipitate hardening β phase increases, and the sizes of the precipitates are refined from 8–10 μm to 2–4 μm. This is expected to be due to the decreased solubility of aluminum in the matrix at low temperature and the significant plastic deformation owing to internal differences in thermal contraction between phases and grains. The polycrystalline matrix is also noticeably refined, with the sizes of the subsequent nanocrystalline grains in the range of 50–100 nm. High density dislocations are observed to pile up at the grain boundaries, inducing the dynamic recrystallization of the microstructure, leading to the generation of a nanocrystalline grain structure. After two deep cryogenic treatments, the tensile strength and elongation are found to be substantially increased, rising from 243 MPa and 4.4% of as-cast state to 299 MPa and 5.1%.
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Microstructure and mechanical properties of AZ91 magnesium alloy subject to deep cryogenic treatments
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10.1007/s12613-013-0812-6
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2013-09-01
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With the replacement of the current upper-stage ESC-A of the Ariane 5 launcher by an enhanced cryogenic upper-stage, ESA’s Ariane 5 Midterm Evolution (A5-ME) program aims to raise the launcher’s payload capacity in geostationary transfer orbit from 10 to 12 tons, an increase of 20 %. Increasing the in-orbit delivery capability of the A5-ME launcher requires a versatile, high-performance, evolved cryogenic upper-stage engine suitable for delivering multiple payloads to all kinds of orbits, ranging from low earth orbit to geostationary transfer orbit with increased perigee. In order to meet these requirements the re-ignitable liquid oxygen/liquid hydrogen expander cycle engine VINCI^® currently under development is designated to power the future upper stage, featuring a design performance of 180 kN of thrust and 464 s of specific impulse. Since 2010 development tests for the VINCI^® engine have been conducted at the test benches P3.2 and P4.1 at DLR test site in Lampoldshausen under the ESA A5-ME program. For the VINCI^® combustion chamber development the P3.2 test facility is used, which is the only European thrust chamber test facility. Originally erected for the development of the thrust chamber of the Vulcain engine, in 2003 the test facility was modified that today it is able to simulate vacuum conditions for the ignition and startup of the VINCI^® combustion chamber. To maintain the test operations under vacuum conditions over an entire mission life of the VINCI^® engine, including re-ignition following long and short coasting phases, between 2000 and 2005 the test facility P4.1 was completely rebuilt into a new high-altitude simulation facility. During the past two P4.1 test campaigns in 2010 and 2011 a series of important milestones were reached in the development of the VINCI^® engine. In preparation for future activities within the frame of ESA’s A5-ME program DLR has already started the engineering of a stage test facility for the prospective upper stage. The new test facility P5.2 is to perform the qualification of the anticipated upper stage with the VINCI^® engine. In the past year DLR has started the design phase for these modifications. The main design drivers are the test configuration and operation domain described in the test request.
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Test facilities for VINCI^®
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10.1007/s12567-013-0043-8
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2013-08-01
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Pneumatic cryogenic control valves (PCCV) are designed to meet the special requirements for the large cryogenic helium refrigeration system. Polychlorotrifluoroethylene (PCTFE) is adopted as the flat seal material of the valve seat. The leakage rates and compressive strain of the PCTFE gasket with different sealing stress are tested at both room temperature (293 K) and liquid nitrogen temperature (77 K). After 300 open/close cycles, the experimental results show that the sealing properties of the PCTFE gasket are improved. The leakage rates are about 10^−8 (293 K) and 10^−4 (77 K) Pa m^3 s^−1 respectively. Finally, the effects of working pressure on sealing characteristics are discussed. The working pressure has little effect on compressive strain but it has a great influence on leakage rate. The leakage rate is linear with the working pressure of inlet at room temperature, but at liquid nitrogen temperature the leakage rate is linear with the square of the working pressure.
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Seat tightness of pneumatic cryogenic control valve
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10.1007/s11431-013-5272-8
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2013-08-01
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In this investigation, a precipitation hardenable martensitic stainless steel (12Cr–10Ni–0.25Ti–0.7Mo) was subjected to different heat treatment cycles to study their influence on the microstructure and mechanical properties. The heat treatment cycles include solution treatment (S), cryogenic treatment (C), and aging (A). Two solution treatment temperatures, 750 and 1000 °C, and two aging temperatures, 250 and 500 °C, were selected. Solution treatment was followed by a cryogenic treatment at −70 °C for 2 h and an aging treatment at the aforementioned temperatures. Transmission electron microscopy of the solution-treated samples showed four phases: martensite matrix, M_23C_6 carbide, Ti(C, N), and retained austenite. On aging at 500 °C, an additional phase (Ni_3Ti precipitates) was observed in the martensite matrix. Mechanical properties were evaluated at room temperature for all the heat-treated samples. A reasonable increase in yield strength (YS) was observed after cryogenic treatment possibly due to transformation of retained austenite to martensite. After aging at 500 °C, a significant increase in the YS was observed over solution-treated condition. This increase in YS after aging is attributed to precipitation of fine Ni_3Ti precipitates. Solution treatment temperature had an insignificant effect on the mechanical properties of the stainless steel.
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Effect of Heat Treatment on Microstructure and Mechanical Properties of 12Cr–10Ni–0.25Ti–0.7Mo Stainless Steel
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10.1007/s13632-013-0079-3
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2013-08-01
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This study aims to predict the residual stress relieved by cryogenic heat treatment (CHT) of an Al6061 tube. Conventional CHT commonly consists of solid-solution heat treatment, uphill quenching, and artificial ageing. To produce a new residual stress that is opposite to the original in nature, the solid-solution heat-treated aluminum parts are usually immersed in LN_2 during uphill quenching with conventional CHT, followed by rapid heating of the parts using boiling water or high-velocity steam. First of all, conventional T6 and CHT experiments are conducted to measure the temperature of a tube with dimensions Ø200 mm × h200 mm × t10 mm. Computational fluid dynamics (CFD) analysis is conducted to calculate the convective heat transfer coefficient and temperature of the tube. These results are compared with the temperature in the experiment, and the comparison results are used to predict residual stress by means of FE-simulation. In particular, the relaxation of residual stress during artificial ageing is investigated using the Zener-Wert-Avrami function with the user subroutine. The predicted values of residual stress are compared favorably with the experimental results within a deviation of 10–15%, in contrast to measurements obtained by micro-indentation and saw-cutting tests. In addition, the experimental results show that conventional CHT can relieve as much as 57% of the residual stress induced by the water quenching of conventional T6 heat treatment.
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FE-simulation coupled with CFD analysis for prediction of residual stresses relieved by cryogenic heat treatment of Al6061 tube
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10.1007/s12541-013-0177-9
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2013-07-01
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The purpose of this study is to predict the residual stress resulting from the cryogenic heat treatment (CHT) which affects the mechanical properties and microstructure for Al6061 alloy. The CHT is very effective method to reduce the residual stress by quenching media such as liquid nitrogen, boiling water and steam. In this study, experimental T6 and CHT are carried out to measure the temperature of Al parts and to determine the convective heat transfer coefficient. This coefficient is used to predict the residual stress during FE-simulation. In order to consider the relaxation of residual stress during artificial ageing, the Zener-Wert-Avrami function with elasto-plastic nonlinear analysis is used in this study. The predicted residual stress is compared with the measured one by X-ray diffraction (XRD) and is found to be in good agreement with results of the FE-simulation. Further, after T6 and CHT, the electrical conductivity and hardness of the Al6061 alloy are measured to estimate the mechanical properties and its microstructure such as precipitates is observed by Transmission electron microscopy (TEM). Also, the creation of precipitates during T6 and CHT are verified by XRD with component analysis. It is found that CHT affects the residual stress, mechanical properties, and precipitation of the Al 6061 alloy.
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Prediction and measurement of relieved residual stress by the cryogenic heat treatment for Al6061 alloy: mechanical properties and microstructure
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10.1007/s12206-013-0601-1
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2013-07-01
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The present work aims to address the characteristics of steady state deformation, which determines the limit of grain refinement for a given material by severe plastic deformation. The focus is on low temperatures at which most deformation processing is conducted. Submicron grained Al–0.1 Mg alloy prepared by equal channel angular pressing was deformed by plane strain compression in a channel-die and rolling at a constant strain rate of 10^−2 s^−1 and at a range of temperatures from 77 to 473 K to various strains. Microstructures were characterized by electron backscatter imaging and EBSD in a FEGSEM. Grain refinement to the ECAP submicron structure occurred during deformation at cryogenic temperatures of 77–213 K, whereas coarsening took place during deformation at elevated temperatures. A steady state deformation was observed at all temperatures where a constant grain structure was developed and maintained upon further straining. The microstructural characteristics of steady state deformation and mechanism responsible for the establishment of the steady state are discussed.
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Characteristics of steady state deformation of an Al–0.1 Mg alloy at low temperatures
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10.1007/s10853-012-7049-z
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2013-07-01
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Several structural states of nanostructured high purity Ti with average grain size down to 100 nm were achieved by high pressure torsion (HPT) at temperatures 300 and 77 K. As a result of HPT processing, changes of crystallographic texture, of grain and crystallite size, and of the dislocation density have been measured and analyzed. Mechanical properties of the nanostructured Ti were studied by uniaxial compression at temperatures 300, 77, and 4.2 K. The texture components indicate simple shear deformation arising from HPT. With subsequent compression, the yield strength appears to be governed by the grain size rather than by crystallite size, dislocation density, and/or impurity content. Considerable changes of texture were observed after low temperature compressive deformation indicating that twinning markedly contributes to plasticity.
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Microstructure and mechanical properties of high purity nanostructured titanium processed by high pressure torsion at temperatures 300 and 77 K
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10.1007/s10853-013-7276-y
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2013-07-01
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The minimum film formation temperature (MFFT) is the minimum drying temperature needed for a latex coating to coalesce into an optically clear, dense crack-free film. To better understand the interplay of forces near this critical temperature, cryogenic scanning electron microscopy (cryoSEM) was used to track the latex particle deformation and water migration in coatings dried at temperatures just above and below the MFFT. Although the latex particles completely coalesced at both temperatures by the end of the drying process, it was discovered that particle deformation during the early drying stages was drastically different. Below the MFFT, cracks initiated just as menisci began to recede into the packing of consolidated particles, whereas above the MFFT, partial particle deformation occurred before menisci entered the coating and cracks were not observed. The spacing between cracks measured in coatings dried at varying temperatures decreased with decreasing drying temperature near the MFFT, whereas it was independent of temperature below a critical temperature. Finally, the addition of small amounts of silica aggregates was found to lessen the cracking of latex coatings near the MFFT without adversely affecting their optical clarity.
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Drying and cracking of soft latex coatings
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10.1007/s11998-012-9425-7
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2013-07-01
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This study was realized with two different types (flat and thread rolled) of coated (TiAlN), uncoated, and cryogenically treated taps (uncoated). The tapping processes were carried at four different cutting speeds (2, 3, 4, and 5 m/min) and 1.25 mm/rev feed rate under dry and wet cutting conditions on the Ti-6Al-4 V alloy. The measured cutting forces (cutting torque) were evaluated according to the cutting tool and cutting parameters. The best results in terms of cutting torque were obtained with straight flutes with spiral point taps. For the coated cutting tools, it was seen that the cutting torque was higher with respect to the other tools. The cutting fluid caused decreases in cutting forces for both of the cutters. Under dry cutting conditions, in the cryogenically treated tool, cutting torques came out to be lower with respect to the coated and uncoated tool.
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The effect of cryogenic treatment on tapping
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10.1007/s00170-012-4529-x
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2013-07-01
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Disintegration of dolostones to dolomite powder (powderization) was a widespread phenomenon in Triassic dolostones of the Buda Hills, where the areal extent of powdered dolostones is large compared to similar occurrences elsewhere in the world. In the Buda Hills, dolostone disintegration proceeded in four stages that correspond to a gradual decrease in particle size, that is, from the parent dolostone to (1) crackle breccia; via (2) mosaic breccia (diameter <2 cm); via (3) mosaic breccia blocks ‘floating’ in dolomite powder; to (4) dolomite powder (diameter 100–300 μm). Stable isotope ratios and trace element compositions of dolomite remained constant throughout these stages, and there are no indications of dissolution in most locations, suggesting that disintegration was predominantly a mechanical process. Combining these findings with the geological history of the region, and supported by a simple freezing/thawing experiment and pertinent experimental studies on weathering of building stones, it appears that powderization in the Buda Hills was caused by repeated freeze–thaw cycles during and/or after the Pleistocene glaciations. Subaerial exposure under cold climate conditions involves multiple freeze–thaw cycles that create mechanical stresses in the rock framework related to the opposing thermal expansion of rock and water that freezes and of ice that liquefies. This process is herewith called ‘cryogenic powderization’. Our data further suggest that the synergy of four factors promoted dolostone powderization in the Buda Hills: (1) tectonics, which created a pervasive fracture network; (2) intercrystalline porosity of the dolostone; (3) relatively high water saturation; and (4) subaerial exposure under cold climate conditions.
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Cryogenic powderization of Triassic dolostones in the Buda Hills, Hungary
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10.1007/s00531-013-0883-7
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2013-05-01
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The evolution of domestic designs of nitrogen-free spectrometers with microcryogenic cooling systems with semiconductor detectors based on ultrapure germanium is examined. The energy resolution of a monoblock germanium nitrogen-free spectrometer with a microcryogenic system and digital spectrometric setup, built at the Institute of Physical-Technical Problems, is 2.25 keV on the 1.33 MeV line. Nitrogen-free spectrometers have proven themselves well in mobile and stationary laboratories providing fast analysis and at technological checkpoints in NPP.
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Evolution of Nitrogen-Free γ-Ray Spectrometers Based on Semiconductor Detectors with Ultrapure Germanium
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10.1007/s10512-013-9667-1
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2013-05-01
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In this paper, by joining three non-traditional machining methods — plasma-enhanced machining, cryogenic machining, and ultrasonic vibration assisted machining — a new hybrid machining technique for machining of Inconel 718 is presented. Cryogenic machining reduces the temperature in the cutting zone, and therefore decrease tool wear and increases tool life, while plasma-enhanced machining helps to increase the temperature in the workpiece to make it softer. Also, applying ultrasonic vibrations to the tool helps to improve cutting quality and to prolong tool life by lowering, mainly, the cutting force and improving the dynamic cutting stability. This study experimentally investigates the effect of cutting parameters on cutting performance in the machining of Inconel 718 and compares the results of hybrid machining and conventional machining (CM). It is found that the hybrid method results in better surface finish and improves tool life in hard cutting at low cutting speeds as compared to the CM method.
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Improving machinability of Inconel 718 with a new hybrid machining technique
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10.1007/s00170-012-4386-7
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2013-04-01
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A D2 tool steel X153CrVMo12 with composition C1.53 Cr12 V0.95 Mo0.80 Mn0.40(wt% Fe balanced) was studied by use of Mössbauer spectroscopy and X-ray diffraction. It was observed that the study of carbides by X-ray diffraction was difficult while Mössbauer spectroscopy gives some light on the process occurring during cryogenic treatment. With the increase of the martensitic phase the carbides decrease and are dissolved in solid solution of martensite as well as the chromium element.
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Mössbauer studies of a martensitic transformation and of cryogenic treatments of a D2 tool steel
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10.1007/s10751-012-0684-6
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2013-04-01
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Cryogenic ground support equipment (CGSE) is an important part of a famous particle physics experiment — AMS-02. In this paper a design method which optimizes PID parameters of CGSE control system via the particle swarm optimization (PSO) algorithm is presented. Firstly, an improved version of the original PSO, cooperative random learning particle swarm optimization (CRPSO), is put forward to enhance the performance of the conventional PSO. Secondly, the way of finding PID coefficient will be studied by using this algorithm. Finally, the experimental results and practical works demonstrate that the CRPSO-PID controller achieves a good performance.
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Optimization for PID controller of cryogenic ground support equipment based on cooperative random learning particle swarm optimization
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10.1007/s12204-013-1376-3
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2013-04-01
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The hybrid superconducting fault current limiter (SFCL) is now at the stage of practical use in a power grid in Korea. A cryogenic cooling system was designed, fabricated, and successfully tested for a prototype of 22.9 kV/630 A SFCL. The operation scheme of cryogenic system has been investigated in preparation for temporary loss of cryocooler power in hybrid SFCL (in Kim et al., IEEE Trans. Appl. Supercond. 21(3):1284–1287, 2011 ). In this paper, we investigated the empirical modeling of cryogenic cooling system for SFCL using principal components and auto-associative support vector regression (PCSVR) for the prediction and fault detection of the cryogenic cooling system. For empirical model, data were acquired during a blackout test of cryogenic cooling system. Blackout times of the test were 1 hour and 4 hours at two operation current levels. Three set of data were used for training and optimization of the model and the rest set of data was used for verification. Signals for the model are temperatures measured at copper band and cold head of cryocooler, system pressure and liquid temperatures measured at two locations in liquid-nitrogen pool. For optimization of the SVR parameters, the response surface method (RSM) and particle swarm optimization (PSO) were adopted in this paper. After developing the empirical model we analyzed the accuracy of the model. Also, these results were compared with that of auto-associative neural networks (AANN). RSM and PSO gave almost the same optimum point. PCSVR showed much better performance than AANN in accuracy aspects. Moreover, this model can be used for the prognosis of cryogenic cooling system for SFCL.
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Empirical Modeling of Cryogenic System for Hybrid SFCL Using Support Vector Regression
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10.1007/s10948-012-1965-7
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2013-03-01
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Narrow optical transitions in highly charged ions (HCIs) are of particular interest for metrology and fundamental physics, exploiting the high sensitivity of HCIs to new physics. The highest sensitivity for a changing fine structure constant ever predicted for a stable atomic system is found in Ir^17 + . However, laser spectroscopy of HCIs is hindered by the large (∼ 10^6 K) temperatures at which they are produced and trapped. An unprecedented improvement in such laser spectroscopy can be obtained when HCIs are cooled down to the mK range in a linear Paul trap. We have developed a cryogenic linear Paul trap in which HCIs will be sympathetically cooled by ^9Be^ + ions. Optimized optical access for laser light is provided while maintaining excellent UHV conditions. The Paul trap will be connected to an electron beam ion trap (EBIT) which is able to produce a wide range of HCIs. This EBIT will also provide the first experimental input needed for the determination of the transition energies in Ir^17 + , enabling further laser-spectroscopic investigations of this promising HCI.
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Cold highly charged ions in a cryogenic Paul trap
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10.1007/s10751-013-0806-9
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2013-03-01
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The world’s first advanced pelletized cold neutron moderator is prepared to be put into operation at the IBR-2M pulsed research reactor. It provides long-wavelength neutrons to the most of neutron spectrometers at the beams of the IBR-2M reactor. Aromatic hydrocarbons are used as a material for cold moderators. It is a very attractive material because of its high radiation resistance, good moderating properties, incombustibility, etc. It is shown that the idea of beads transport by a helium flow at cryogenic temperatures is successful. The recent progress and plans for moderator development at the IBR-2M reactor as well as the experimental results of beads transport are discussed in the paper.
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Current status of advanced pelletized cold moderators development for IBR-2M research reactor
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10.1134/S154747711302009X
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2013-03-01
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This work presents a study on the effect of low pressure cryogenic liquid nitrogen on cutting forces, friction coefficient, surface roughness of the machined surface and tool wear under high speed machining of a relatively new titanium alloy, Ti-5Al-4V-0.6Mo-0.4Fe. The experiments were conducted in dry and cryogenic conditions. The experimental results show that liquid nitrogen can reduce the friction force, friction coefficient and improve the surface roughness.
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Cutting forces, friction coefficient and surface roughness in machining Ti-5Al-4V-0.6Mo-0.4Fe using carbide tool K313 under low pressure liquid nitrogen
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10.1007/s40430-013-0001-6
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2013-03-01
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This investigation focuses on understanding the effects of particle size and surface area of cryogenically-ground micronized rubber powders (MRP) on the properties of MRP/polypropylene (PP) composites. Comparisons are made with ambient-ground rubber powders and its PP composites. The morphology of the fracture surfaces of the composites is studied in relation to the effects of particle size on mechanical properties. In addition, this paper discusses utilizing a compatibilizer with MRP in improving the mechanical performance of the PP composites for its use in various market segments, such as automotive, consumer and, construction.
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Effects of Micronized Rubber Powders on Structure and Properties of Polypropylene Composites
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10.1007/s12649-012-9166-y
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2013-03-01
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Little is known about the mechanical properties of bulk metallic glassy alloys (BMGs) after cryogenic treatment. In this study, the effects of cryogenic treatment (CT) on the microstructural transition and the mechanical properties of Cu-based bulk metallic glass (BMG) were studied. The results showed that submicron AlCu_2Zr and Cu_5Zr phases can precipitate from the Cu-Zr-Ag-Al matrix after 192 h CT. The formation of these nanometer-sized crystalline phases substantially enhanced the mechanical properties of the bulk amorphous alloy. The micro-hardness and the compressive strength were found to increase respectively from 501 HV and 1510 MPa to 595 HV and 1910 MPa after cryogenic treatment. CT is a promising approach to strengthening metal glasses.
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Cryogenic treatment induced hardening for Cu-Zr-Ag-Al bulk metallic glasses
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10.1007/s11431-012-5107-z
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2013-02-01
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Cavitation is the formation of vapor bubbles within a liquid where the flow dynamics causes the local static pressure to drop below the vapor pressure. The so-called full cavitation model (FCM) developed by Singhal has been widely used in numerical modeling of the cavitation flow for thermosensible and non-thermosensible fluids. Within the FCM, the bubble size is taken to be equivalent to the maximum possible value to forego the calculation of bubble number density. We developed a new cavitation model by re-calculating the bubble radius in FCM to account for the effects of local pressure. The new model was obtained by combining the thermodynamic phase-change theory and the Young-Laplace equation with the assumption of thermodynamic equilibrium during the cavitation process. The cavitation calculations were performed based on the mathematical framework of the homogeneous equilibrium flow model and the transport-equation-based model for vapor phase mass fraction. The model was validated by modeling the cavitating flow of liquid nitrogen and liquid hydrogen through NASA hydrofoil and Ogive with consideration of the phase-change thermal effects. The temperature and pressure distributions with the new model are found to agree well with data from existing experimental studies, as well as the simulations with the FCM.
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Modeling cavitation flow of cryogenic fluids with thermodynamic phase-change theory
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10.1007/s11434-012-5463-x
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2013-02-01
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External energy assisted machining involves the use of a heating, cooling, and mechanical vibration source to facilitate the material removal process. A drastic attention on the external energy assistance is resulted from the requirements for newly developed hard and brittle materials machining and many activities to understand the mechanisms, processes, and the systems have been performed on both micro and macro scale in recent years. This paper attempts to provide an overview in the general idea of these areas with laser and plasma, cryogenic, and vibration assistances. The progresses made up to date will be explained in detail and finally, the future research directions in this area will be discussed.
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Current research trends in external energy assisted machining
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10.1007/s12541-013-0047-5
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2013-02-01
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The present work aims at understanding the effects of cryogenic coolant application and machined surface alterations during orthogonal machining of hardened AISI 52100 bearing steel. Experiments were performed under dry and cryogenic cooling conditions using cubic boron nitride tool inserts with varying initial hardness and tool shape. Several experimental techniques were used in order to analyze the machined surface. In particular, optical and scanning electron microscopes were used for characterizing the surface topography, whereas the microstructural phase composition analysis and chemical characterization have been performed by means of X-ray diffraction and energy-dispersive spectroscopy techniques. The experimental results prove that the white layer is partially reduced or can be totally eliminated under certain process parameters and cryogenic cooling condition.
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Analysis of the white layers formed during machining of hardened AISI 52100 steel under dry and cryogenic cooling conditions
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10.1007/s00170-012-4073-8
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2013-01-01
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Helium Machinery Scientific-Production Association (NPO GELIIMASh) has developed and built the first domestic cryogenic transporting helium tank of the trademark TsTG-40/0.45 with a capacity of 40 m^3 − a key element of the logistic system of liquid helium delivery across Russia and to other countries. The TsTG-40/0.45 tank filled with liquid helium at the enterprise KRIOR was successfully tested at the Orenburg helium plant; the liquefying helium equipment was built at NPO GELIIMASh. The tank filled to the full capacity successfully passed the tests in conformity with the regulations of the Russian Marine Shipping Register, which provides the possibility of transporting liquefied helium all over the world on a par with the foreign-made helium tanks.
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Geliimash – A technological breakthrough
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10.1007/s10556-013-9669-9
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2013-01-01
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The cryogenic properties of polymer materials have received great attention with new developments in space, superconducting, electronic and defense technologies as well as large cryogenic engineering projects such as International Thermonuclear Experimental Reactor (ITER), etc. Polymer materials developed for these applications are mainly employed as electrical insulators, thermal insulators, vacuum sealants, and matrix materials for composites used in cryogenic environments. The requirements are extremely severe and complicated for polymer materials in these unique applications. The polymer materials need to possess good mechanical and physical properties at cryogenic temperatures such as liquid helium (4.2 K), liquid hydrogen (20 K), liquid nitrogen (77 K), and liquid oxygen (90 K) temperatures, etc., to meet the high requirements by the cryogenic engineering applications. Herein the cryogenic mechanical and physical properties of polymer materials will be highlighted in this chapter. Cryogenic tensile properties/behaviors are first presented in some details for various neat polymers and filled polymers. Cryogenic shear strength, impact strength, and fracture toughness are then discussed. Afterwards, cryogenic thermal, creep, sliding, and dielectric properties of polymers are briefly summarized. Finally, discussions about effects of water absorption and cryogenic aging on cryogenic properties of some polymers are conducted.
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Cryogenic Properties of Polymer Materials
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10.1007/978-3-642-35335-2_2
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2013-01-01
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Elemental composition of humic acids (HA) from humus horizons and frost cracks (FC) were studied in frozen metamorphized chernozems and coarse humus burozems. HA molecules from cryogenic cracks proved to be of a more aromatic nature than those from proper humus horizons.
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Elemental Composition of Humic Acids in Frost Cracks of Soils of Cryolithic Belt
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10.1007/978-94-007-5634-2_153
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2013-01-01
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To evaluate the effects of cryogenic temperatures on mechanical properties of a thermo-mechanically treated Mg-rare earth (RE) alloy, tensile tests were carried out from room temperature to liquid nitrogen temperature (LNT) to study the deformation and fracture behavior of the selected magnesium alloy. The results showed that the ultimate strength and yield strength increased while elongation decreased as the testing temperature decreased. The as-forged specimen exhibited higher strength and ductility than the aged specimen. Further scanning electron microscopy (SEM) investigation and optical observation illustrated that the deformation mechanism of the Mg-RE alloy changed from slip to twinning with a decrease in testing temperature. Furthermore, the fracture of tensile specimen transformed from boundary to twin plane as observed by SEM. The brittleness of the second phase at cryogenic temperature is taken into account in discussing the transition of the fracture mode of the Mg-RE alloy from intergranular to transgranular with the decrease of temperature.
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Study of Tensile Properties of Mg-Rare Earth Alloys at Cryogenic Temperatures
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10.1007/978-3-642-30229-9_34
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2013-01-01
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Research and / or Engineering Questions / Objective There are many domestic enterprises that produce auto-hub bearings in China. But the majority of products are only applied in the after-sale market as the unstable quality of the domestic products can’t meet the OEM’s requirements. In order to improve fatigue life and dimensional stability of GCr15 steels, the cryogenic treatment was introduced to control the percentage of retained austenite of GCr15 bearing steel. Methodology The correlation between cryogenic treatment parameters and microstructure of the hub-bearing was studied. The percentage of retained austenite after different cryogenic treatments was measured by X-ray diffraction experimental. The equation was established to reveal the relationship between the percentage of retained austenite and cryogenic temperature. Finally, the fatigue life was performed by strengthen test according to JB/T 50013-2000 test rules of life and reliability of rolling bearings. Results After cryogenically treated in −40, −80, −120, −160, −196 °C chamber for 2 h, the investigation revealed that the retained austenite of the specimen surface is with proportional to the temperature decrease of deep cryogenic treatment. The specimens possess the maximum hardness and the minimum impact toughness during keeping at −80 °C deep cryogenic treatment temperature. Limitations of this study This study work has verified that the cryogenic treatment can improve the fatigue life and dimensional stability of wheel hub bearing. In order to obtain broader application and promotion, it requires further investigation on the characteristic properties of cryogenic treatment to be applied to other automotive bearings and other kinds of parts. What does the paper offer that is new in the field in comparison to other works of the author Since the mechanism of cryogenic treatment is not yet to be understood very well, So in general cryogenic treatment is still in the dormant level at present. In this study, we focus on investigating the mechanism and optimizing parameters of cryogenic treatment to improve the fatigue life of wheel-hub bearing. Conclusion The test results indicate the cryogenic treatment can improve the fatigue life of DAC 4007040 hub bearing, which runs 39.537 million revolutions, Re = 99.22 % by optimizing cryogenic treatment. In the same load conditions, the fatigue life of DAC 4007040 hub bearing subjected to conventional heat treatment is only 21.79 million revolutions in average, Re = 96.7 %.
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Effect of Cryogenic Treatment on Retained Austenite and Fatigue Life of Gcr15 Wheel-Hub Bearing
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10.1007/978-3-642-33738-3_64
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2013-01-01
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The objective of this development is to design, build and test a magnetic-superconductor cryogenic non-contact harmonic drive (MAGDRIVE). This harmonic drive is a mechanism provided with an input axle and an output hub with a great reduction ratio and it will be able to function at cryogenic temperatures. It is based on “non-contact magnetic teeth” instead of fitting teeth on a flexural wave as conventional harmonic drives are based on. Non-contact magnetic teeth are activated by a magnetic wave (similar to an electrical engine) and stabilized by the use of superconductor materials. This can solve the problems of contact wearing and mechanical fatigue. Superconductors are also used for non-contact bearings and for shielding the magnetic fields to avoid electromagnetic interferences or emission. The first preliminary analyses show very promising mechanical performances of the reduction gear. They have demonstrated that the transmitted torque density capability is independent of the size of the gear. Also, the choice of the material for the soft-magnetic teeth is not a critical decision provided that they have a minimum required magnetic permeability. Moreover, some dynamical simulations have shown that the reduction ratio is achieved.
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Magnetic-Superconductor Cryogenic Non-contact Harmonic Drive: Performance and Dynamical Behavior
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10.1007/978-94-007-4902-3_38
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2013-01-01
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In this chapter, self-heat recuperation technology (SHRT) is applied in gas separation processes, which are (1) cryogenic air separation and (2) CO_2 chemical absorption processes. (1) The energy consumption of cryogenic air separation based on self-heat recuperation (SHR) can be reduced by 40 % compared with a conventional process. In the proposed process, not only the latent heat but also the sensible heat of the process stream is circulated in the process. Furthermore, the pressure in the column can be reduced compared with the high pressure part of a conventional cryogenic air separation process. (2) The energy consumption of a CO_2 chemical absorption process based on SHR can be reduced by 70 % compared with the conventional process. In the proposed process, the heat of the exothermic absorption reaction in the absorber and the heat of the steam condensation in the condenser of the stripper are recuperated and circulated for reuse for regeneration of absorbent solution and vaporization in water during CO_2 stripping.
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Gas Separation Section
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10.1007/978-1-4471-4207-2_5
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2013-01-01
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External tanks of the spacecrafts need not only efficient, but also safe cryogenic insulation materials and the issues of their development are still urgent. At present, polyurethane (PUR) or polyisocyanurate (PIR) foams’ cryogenic insulation is widely applied in the partially reusable launch systems. Factors influencing the cryogenic resistance of external thermal insulation performed of spray-on PUR or PIR foams are characterised based on a wide literature search. They include chemical structure and macromolecules’ architecture of polymeric matrix, physical and mechanical properties of foams, thermal stability and combustibility, cellular structure of foams etc. Experimental data on physical and mechanical properties at room and cryogenic temperatures are presented for IWC developed PUR foams further named as IWC-Cryo. Technological processes of spray-on PUR and PIR foams cryogenic insulation, cryo-pumping and the main defects of external tank insulation are analysed as well as applications of foams’ insulation in space technologies ( Space Shuttle , Ariane and Buran ).
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Polyurethane and Polyisocyanurate Foams in External Tank Cryogenic Insulation
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10.1007/978-3-642-35335-2_10
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2013-01-01
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Cryogenic treatment (CT), a supplementary process to conventional heat treatment process, is the process of deep-freezing materials at cryogenic temperatures to enhance the mechanical and physical properties of materials being treated. CT is one of the field in which the materials to be treated play a very imperative role in its technological development. Some of its successful applications in nonferrous materials defy the conventional reasoning that the only affect it has is to convert retained austenite to martensite. For example tungsten carbide cutting tools, electronics materials, some plastics, composites, and polymers show significant improvements that cannot be supported by the conventional theories as to why the process works. CT technologies have applications in wide range of areas including cutting tools, polymers, plastics, power industry, medicine, rocket propulsion and space simulation, food processing, to name but a few of them. The execution of CT on cutting tool materials increases wear resistance, hardness, and dimensional stability and reduces tool consumption and down time for the machine tool set up, thus leading to cost reductions. Similarly, improvements in wear resistance, hardness, dimension stability, crystallinity, tensile strength and elongation have been reported for polymers subjected to CT. The effects of CT on tool materials (steels and carbides) and polymers along with their applications are reviewed for manufacturing industry in this chapter. Although it has been confirmed that CT can improve the service life of tools and polymers, the degree of improvement experienced and the underlying mechanism remains ambiguous. The steps involved in CT are critical enough to account for the significant incongruity in post-treated performance of treated materials. If we look toward the next century, the topic of the-state-of the art and future developments in CT areas has several aspects to it. Firstly it is essential to look at the history of the development of CT. It is equally important to evaluate the current status of science of CT and to identify research and development trends in this area which can act as starting point for future developments. In this chapter, an attempt has been made to present the past, present, and future of CT technology for tool materials and polymers.
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Cryogenic Treatment of Materials: Cutting Tools and Polymers
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10.1007/978-3-642-35335-2_11
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2013-01-01
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Composites are the modern trend materials replacing monolithic metals and alloys in many industrial applications. It has also been widely used in many of engineering applications where materials are subjected to very low temperatures. Hence it finds essential to investigate its mechanical properties after cryogenic treatment of composite materials and compare the results with behavior of materials at ambient conditions. This chapter describes the preparation of glass/epoxy composites for different volume fraction. The developed specimens were subjected to cryogenic treatment with the aid of liquid nitrogen. Mechanical properties such as tensile, impact, and flexural behavior were presented separately of cryogenic treated specimens and untreated specimens. The obtained results exhibited enhanced mechanical properties.
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Influence of Cryogenic Treatment on Mechanical Behavior of Glass Fiber-Reinforced Plastic Composite Laminate
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10.1007/978-3-642-35335-2_9
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2013-01-01
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As the use of polymers in structural components and power transmission systems has grown in the last decades, the demand for improved mechanical performances of these materials is increasing. Besides fibre reinforcement, the research about thermal treatments and surface coatings of these materials is focused on obtaining more strength and resistance to fatigue and wear. In this direction, a contribution can be given by unconventional treatments such as cryogenics. The use of deep cryogenic treatment (DCT) on polymers is already claimed as miraculous by some companies. The analysis of peer-reviewed literature shows that it is not all marketing: many pure and reinforced polymers have shown DCT improvements in hardness and in wear resistance under controlled experimental conditions. Starting from these results, a general overview of potential DCT applications on polymeric products is given in order to suggest further developments and research areas.
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Current and Potential Applications of Cryogenic Treated Polymers
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10.1007/978-3-642-35335-2_12
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2013-01-01
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Dielectrics is ubiquitous in all electrical systems. In this chapter we introduce many aspects in a systematic manner in order for the reader to be able to follow it in a sequence. Firstly, the various media and the salient features of each are discussed. The media range from vacuum to highly compressed gases, liquids, and solids. The basic mechanism of dielectric behavior is discussed in each different case when subject to electric field. The imposed electric field can be of different forms such as steady-state AC and DC voltages. It can also be due to transients in the system brought about by switching operations or they could be due to naturally occurring phenomena namely lightning. The configuration of electrode geometries and the polarity of the electrodes bring about phenomena within the media that need to be understood in order to design electrical systems for a variety of applications. We also focus our attention particularly when the media are at cryogenic temperatures. The electronic and ionic reaction mechanics change drastically at low temperatures. In the early part of this chapter the discussion is centered around the basics such as partial discharge, electrical breakdown, dielectric losses, and permittivity. This is followed by applications of power cable design and operation at or near the boiling point of liquid helium. The reader is directed to some real life experiences of such cable systems. Once again the emphasis here has been on the dielectric aspects and the role that materials play in enabling such technology. With the advent of high temperature superconductors (HTS) the outlook was more promising as superconductivity could be achieved at around the boiling point of liquid nitrogen (77 K). Most dielectric systems were designed with the cryogen playing a dual role of being the cooling medium and also being an integral part of the dielectric. As HTS became more widespread cold compressed gaseous helium is now considered viable for some special applications. Advances in the development of polymeric materials for cryogenic applications have largely kept up with HTS technology. However, there are problems that have to be overcome, in particular mechanical strength at low temperatures. Another problem inherent to devices such as cables and coils is winding gaps and inclusions. This presents opportunities for partial discharges to start and if not avoided leads to aging of the device and finally failure. Important dielectric properties such as permittivity and loss tangent have been discussed at some length. The measurement of these parameters not only gives their numerical values but also provides insight into the behavior of the material properties in a general sense. Composites is another area that is being actively pursued and this topic is discussed in particular the differences between micro- and nano-fillers in polymer resins. The large increase in surface area with the reduction in particle size to the nano-scale has opened up great opportunities for advancement. The interfacial region is one that holds the key to future advancement in this technology. Cryogenic nanocomposites are a fascinating technology that has opened up new horizons, and many laboratories are making great progress in understanding the behavior of these materials both theoretically and with experiments.
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The Behavior of Polymer-Based Dielectrics Under Cryogenic Conditions
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10.1007/978-3-642-35335-2_6
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2013-01-01
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Although epoxy resins have been widely used for engineering applications, because of their good mechanical properties, they are usually brittle and vulnerable to cracking. This problem becomes more severe when thermosetting epoxy resins are employed in extremely low temperature environments. Hence improvement in fracture toughness is desired. Therefore, fillers such as clay, carbon nanotube, etc. have been used to enhance mechanical properties. Though these reinforcements showed promising results at room temperature, at cryogenic temperature they deteriorate the mechanical properties of epoxy resins. This is due to free space, free volume and thermal contraction effect. This study reports on the mechanical characterization of POSS–epoxy nanocomposites at cryogenic temperature (77 K). POSS (Polyhedral oligomeric silsesquioxne) is a hybrid organic–inorganic nanoadditive that directly interact with epoxy resin. These nanocomposites were prepared using DGEBF (diglycidyl ether of bisphenol F) based epoxy resin and three different functionalities of POSS, namely, glycidyl, trisilanol phenyl, and methacryl. POSS was added at various weight fractions of 0.5%, 1%, 3%, 5% and 8% and an amine-based hardener was used to cure epoxy resin. The test results show that the addition of POSS leads to significant improvement in fracture toughness at 77 K. There is no change in flexural modulus observed. Differential scanning calorimetry is used to measure the glass transition temperature.
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Reinforcement of Epoxy Resins with POSS for Enhancing Fracture Toughness at Cryogenic Temperature
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10.1007/978-1-4614-4553-1_19
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2013-01-01
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Polymers are extensively used for sliding systems in cryogenic applications because of their favourable friction and wear behaviour in the absence of external lubrication. Since important new technologies are based on applications under extreme conditions, such as at low temperatures, new requirements on material properties, in particular regarding their operability and reliability, must be met. Up to now, most tribological investigations have been carried out in inert cryogens or cryogenic gas (He, N_2). Few experiments have been performed in vacuum environment at cryogenic temperatures. Rarely were testing in reactive media, such as LH_2 or LOX. Due to the wide range of operating conditions in cryogenic applications, it is difficult to state general rules. Therefore, this chapter tends to give an overview on theories and experimental studies on polymer tribology at cryogenic temperatures.
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Friction and Wear of Polymer Materials at Cryogenic Temperatures
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10.1007/978-3-642-35335-2_3
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2013-01-01
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Superconducting tunnel junctions (STJ) are a class of cryogenic detectors that rely on the generation of free charge carriers by breaking Cooper pairs in a superconducting material with the use of absorbed photon energy. In an STJ, consisting of two superconducting films separated by a thin insulating barrier, the charge carriers can be detected through the tunnel-current pulse they produce if the STJ is under a finite voltage bias. The number of charge carriers generated is proportional to the energy of the absorbed photon, and, depending on the material of choice, ranges from several hundreds to a few thousand per electronvolt of photon energy. This allows STJs to be used as photon-counting detectors with intrinsic energy resolution over a wide energy band from the near infrared to well into the X-ray band. The operating temperature is typically at 10 % of the critical temperature T _c of the superconducting material and may range from 0.1 K to 1 K. Although they have not been deployed in space applications yet, they could well be envisaged as spectrometers with an energy-resolving power of several hundreds in the soft X-ray range, or as highly efficient order-sorting detectors in UV grating spectrographs. STJs can be used simultaneously as absorbers and read-out elements, or alternatively, if a larger sensitive area is required, two or more can be attached as read-out elements to a separate absorber. The state of the art performance comprises energy resolutions of eV to 11 eV in the soft X-ray energy range from 0.4 keV to 5.9 keV, and of 0.1 eV to 0.2 eV in the near-infrared and visible range from 0.5 eV to 5 eV. Imaging arrays of > 100 pixels of close-packed STJs have been made and operated in ground-based astronomical applications.
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Superconducting tunnel junctions
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10.1007/978-1-4614-7804-1_27
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2013-01-01
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Many technologies are needed to build a fusion power plant: vacuum systems, magnet systems, plasma stability control, superconductors, radio waves, microwaves, lasers, accelerators, structural support, cryogenics systems, cryogenic pellet injectors, plasma power control, high-temperature materials that can survive radiation damage, radiation shielding, tritium control, 3D computer aided design systems, safety analyses, and diagnostic instruments. This chapter provides a brief introduction to these topics, which are discussed in the rest of the book.
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Technology Issues
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10.1007/978-1-4471-5556-0_2
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2013-01-01
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The microbial activity of peat soils was studied in boggy larch forests and in an oligo-mesotrophic bog in the basins of the Kochechum and Nizhnaya Tunguska rivers (central Evenkia). It was found that the organic matter transformation in the peat soils of all the plots is mainly performed by oligotrophic bacteria composing 88–98% of the total bacterial complex. The major contribution to the organic matter destruction belonged to the heterotrophic microorganisms, the activity of which depended on the permafrost depth and the soil temperature, the soil acidity, and the botanical composition of the peat. Peat soils were characterized by different activities as judged from their microbiological and biochemical parameters. The functioning of microbial communities in the studied ecotopes of the permafrost zone was within the range of natural variations, which pointed to their ecological stability.
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Microbial activity of peat soils of boggy larch forests and bogs in the permafrost zone of central Evenkia
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10.1134/S1064229313010043
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2013-01-01
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Aluminum lithium alloy will likely become the material of choice over composites as the fuselages of the next generation of narrow-body aircraft due to its high strength to weight ratio and excellent corrosion resistance. In this paper, aluminum lithium alloy samples are milled under air coolant condition and liquid nitrogen condition. Surface integrity factors including roughness and residual stress are measured. The results show that the angle between feed direction and rolling orientation dominates in the formation of surface finish, which is often neglected in previous study. The results also demonstrate the capacity of liquid nitrogen on improving the surface integrity followed by an increase of material removal rate in face milling of aluminum lithium alloy. Finally, the regression models for roughness and residual stress are established and the effectiveness of these models are validated.
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Experimental Study of Surface Integrity of Aluminum Lithium Alloy by Face Milling
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10.1007/978-3-642-40849-6_50
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2013-01-01
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Cryogenics plays a key role on board space-science missions, with a range of applications, mainly in the domain of astrophysics. Indeed a tremendous progress has been achieved over the last 25 years in cryogenics, with enhanced reliability and simpler operations, thus matching the needs of advanced focal-plane detectors and complex science instrumentation. In this article we provide an overview of recent applications of cryogenics in space, with specific emphasis on science missions. The overview includes an analysis of the impact of cryogenics on the spacecraft system design and of the main technical solutions presently adopted. Critical technology developments and programmatic aspects are also addressed, including specific needs of future science missions and lessons learnt from recent programmes.
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Cryogenics in space
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10.1007/978-1-4614-7804-1_37
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2013-01-01
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The Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique emerged more than one decade ago as an alternative and complementary method to Pulsed Laser Deposition (PLD) in view of transferring organic materials onto solid substrates. In contrast to PLD, MAPLE proved to be a less harmful approach for transporting and depositing delicate, heat sensitive molecules. Since origin, MAPLE developed fast and was generally applied for organic biomaterials. It turned recently to inorganic compounds and has become a competitor to PLD. An important benefit of MAPLE is the capability of transferring films of nanoparticles with largely extended active areas. Such films can play an essential role in biology, pharmaceutics or sensing applications. This chapter reviews the mechanisms and recent progresses of MAPLE in thin film assembling for biomimetic applications in drug delivery systems, biosensors and advanced implant coatings.
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Biomimetic Assemblies by Matrix-Assisted Pulsed Laser Evaporation
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10.1007/978-3-642-41341-4_5
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2013-01-01
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This chapter describes the results of our studies on the interlaminar delamination fracture and fatigue of woven glass fiber reinforced polymer composite laminates under Mode I, Mode II, and Mode III loadings at cryogenic temperatures. Delamination fracture tests were carried out at cryogenic temperatures, and the critical energy release rate at the onset of delamination propagation, i.e., fracture toughness, was evaluated based on a finite element analysis coupled with damage. In addition, cryogenic fatigue delamination tests were performed, in order to obtain the delamination growth rate as a function of the range of the energy release rate. After the tests, fractographic observations were made to assess the delamination mechanisms at cryogenic temperatures.
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Interlaminar Delamination Fracture and Fatigue of Woven Glass Fiber Reinforced Polymer Composite Laminates at Cryogenic Temperatures
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10.1007/978-3-642-35335-2_5
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2013-01-01
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Chronologically, gas thermometry was the first method used for the accurate measurement of the thermodynamic temperature—with air used as a working substance—the reason being that the very simple law of the ideal gas (Eq. 1.16) is applicable to several real gases with close approximation. Air was soon replaced by hydrogen and then by helium. The reader is directed to “Further Reading,” for the history and the developments of gas thermometry.
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Gas Thermometry Between 0.5 and 273.16 K
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10.1007/978-1-4419-8282-7_3
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2013-01-01
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A procedure for calculating the heat flux and temperature distributions in a high-temperature superconductor current lead with a section connected to a cryogenic cooling machine that removes the heat released in the current lead at different levels is presented. How the purity of the copper material used for the current-lead segment influences heat fluxes is examined.
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How the material of a resistive part of a high-temperature superconductor current lead influences cryocoolant heat load
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10.3103/S1068371213010021
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2013-01-01
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High specific strength, stiffness, excellent environmental fatigue resistance and low weight remain the winning alliance that impels fibrous composite materials into new arenas, but other properties are also equally important. Fibrous reinforced plastics (FRPs) offer good vibrational damping and a low coefficient of thermal expansion, characteristics that can be engineered for specialized applications. Commercial composites are used in large markets such as automotive components, boats, consumer goods, and corrosion-resistant industrial parts. Advanced composites, initially developed for military aerospace applications, offer performance superior to that of conventional structural metals and now find applications in satellites, aircraft, and sporting goods and in the energy sector in oil and gas exploration and wind turbine constructions. Cryogenic applications of polymeric fiber composites are mainly in superconductivity, space technology, and handling of liquefied gases. By contrast, because of the heterogeneous nature and anisotropic behavior of FRPs, a structural designer faces challenges in predicting the integrity and durability of FRP laminates during service periods. Polymer composites soften, creep, and distort when heated to high temperatures (>100 °C), accompanied by collapse of free volume as the molecular adjustments take place. This can result in buckling and failure of load-bearing composites structures. Severe environmental exposure affects the physical and mechanical properties of polymeric composite materials, resulting in an undesirable degradation and damage. Cryogenic fuel tanks are the most common structural application of FRP at low temperatures. Expose to cryogenic temperatures can cause microcracks as well as delamination in the composites due to thermal residual stresses. These microcracks provide a pathway for the ingress of moisture or corrosive chemicals and are a possible pathway for loss of cryogenic fluids in the tanks. Matrix resins at low temperatures are brittle and do not allow relaxation of residual stresses or stress concentration to take place. At low temperatures, polymers are well below their glass transition temperature and show little viscoelastic behavior. Molecular motion of segments or side groups is still possible, but the degrees of freedom decrease with decreasing temperature. This motion influences the damping behavior of the polymers under cyclic mechanical load. If the temperature-dependent relaxation time of molecular motion is equal to the time of external deformation, maximum power dissipation occurs. Simultaneously, a change in the shear modulus is observed. The goal of this chapter is to extensively study the in-plane mechanical properties of FRP composites at cryogenic temperatures. The composites considered include carbon, glass, and Kevlar fiber-reinforced polymers with different resin matrices.
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Mechanical Behavior of Polymer Composites at Cryogenic Temperatures
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10.1007/978-3-642-35335-2_4
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2013-01-01
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Cryogenic processing is the one-time permanent treatment of the materials at very low temperatures to increase the physical and mechanical properties. Cryogenic processing is capable of treating a wide variety of materials such as metals, alloys, polymers, carbides, ceramics and composites. Cryogenic applications of polymers are not only limited to the fields of space, electrical and superconducting technology but also to other advanced technologies such as cryosurgery and cryobiology in the medical field.
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Cryogenic Processing: State of the Art, Advantages and Applications
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10.1007/978-3-642-35335-2_1
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2013-01-01
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Viruses have co-evolved with their hosts, developing effective approaches for hijacking and manipulating host cellular processes. Therefore, for their efficient replication and spread, viruses depend on dynamic and temporally regulated interactions with host proteins. The rapid identification of host proteins targeted by viral proteins during infection provides significant insights into mechanisms of viral protein function. The resulting discoveries often lead to unique and innovative hypotheses on viral protein function. Here, we describe a robust method for identifying virus–host protein interactions and protein complexes, which we have successfully utilized to characterize spatial–temporal protein interactions during infections with either DNA or RNA viruses, including human cytomegalovirus (HCMV), herpes simplex virus type 1 (HSV-1), pseudorabies virus (PRV), human immunodeficiency virus (HIV-1), Sindbis, and West Nile virus (WNV). This approach involves cryogenic cell lysis, rapid immunoaffinity purification targeting a virus or host protein, followed by identification of associated proteins using mass spectrometry. Like most proteomic approaches, this methodology has evolved over the past few years and continues to evolve. We are presenting here the updated approaches for each step, and discuss alternative strategies allowing for the protocol to be optimized for different biological systems.
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Discovery of Host–Viral Protein Complexes During Infection
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10.1007/978-1-62703-601-6_4
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2012-12-01
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Due to its high hypericin and pseudohypericin in vitro biosynthetic capacity, the Balkan endemic Hypericum rumeliacum was selected as a prospective candidate for long-term preservation of valuable medicinal plant germplasm. Initial cryopreservation experiments were previously conducted based on the successful protocol established and reported for the widely studied H. perforatum . This is the first report on the impact of pre-culture duration on the short- and long-term in vitro recovery of the biosynthetic potential and antioxidant defense system of H. rumeliacum cryopreserved by vitrification. Cryopreservation did not impair the phenolics and flavonoids production of the regenerated plants. Moreover, hypericin and pseudohypericin levels even increased substantially in one of the regenerated lines, reaching yields from 0.107 and 0.752 mg g^−1 DW in the control up to 0.277 and 1.112 mg g^−1 DW for hypericin and pseudohypericin, respectively. However, the physical injury stress of the pre-culture treatment manipulations affected the physiological status of regenerants in a time dependent manner. Within 6 months after thawing, regenerants with the highest oxidative stress after pre-culture, were characterized with an augmentation of antioxidant metabolites such as phenolics, flavonoids, glutathione and ascorbic acid as well as increased antioxidant enzymatic activities in comparison with both the non-frozen control and the regenerants with the lowest pre-culture oxidative stress. Then, after 18 months of recovery, the same first H. rumeliacum group displayed a marked drop of enzymatic antioxidant activity as compared with the other groups of plants. Further research is needed to target oxidative stress alleviation to optimize H. rumeliacum cryopreservation protocol.
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Impact of pre-culture on short- and long-term in vitro recovery of the biosynthetic potential and enzymatic and non-enzymatic antioxidant defense of Hypericum rumeliacum Boiss. after cryostorage
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10.1007/s10725-012-9733-z
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2012-11-01
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The ultrafine-grained Al 6061 alloy, which was fabricated by the combination of cryogenic rolling with warm rolling, achieved high ultimate tensile strength of 420 MPa. Compared with the results by other severe plastic deformation methods, the strengthening effect by the combination of cryogenic rolling with warm rolling was found significantly effective. This notable increase of tensile strength was achieved by the formation of finer precipitates during warm rolling. The presence fine precipitates of diameter below 100 nm, in ultrafine-grained matrix, were confirmed with TEM and STEM. The estimated precipitation strengthening by the fine precipitates was approximately 100 MPa. Based on the results, it was found that cryogenic rolling combined with warm rolling would be effective in increasing strength.
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The achievement of high strength in an Al 6061 alloy by the application of cryogenic and warm rolling
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10.1007/s10853-012-6478-z
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2012-11-01
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Macroporous filled and unfilled poly(vinyl alcohol) (PVA) cryogels are produced by cryogenic treatment (freezing at −20°C for 12 h followed by thawing at a rate of 0.03°C/min) of mixtures of an aqueous PVA solution and a full-component poly(vinyl acetate) (PVAc) dispersion or its individual components. The values of the elasticity modulus and fusion temperature are determined for obtained samples; their microstructure is studied by light microscopy of thin sections. It is shown that the effects that are induced by the incorporation of PVAc dispersion into the macroporous matrix of the PVA cryogel are due to the presence of both a discrete phase, i.e., solid PVAc microparticles, and ingredients of the liquid phase of the PVAc dispersion, mainly, urea. Therewith, the dispersed particles themselves serve as a reinforcing filler, i.e., increase the rigidity and (to a lesser extent) heat endurance of the cryogel, while urea, which possesses chaotropic properties and hinders the intermolecular hydrogen bonding of PVA chains, reduces the rigidity and heat endurance of the composites. As a result, the total effect is determined by the competition of differently directed influences of these components of PVAc dispersion and depends on its concentration in the resulting filled cryogel. It is also shown that PVAc microparticles are mainly entrapped in the gel phase of the macroporous matrix and form necklacelike aggregates, the cross-sectional areas and lengths of which depend on the degree of composite filling.
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A study of cryostructuring of polymer systems. 34. Poly(vinyl alcohol) composite cryogels filled with microparticles of polymer dispersion
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10.1134/S1061933X12060117
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2012-11-01
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A key design issue related to the turbopump of the rocket engine is that cavitation occurs in cryogenic fluids when the fluid pressure is lower than the vapor pressure at a local thermodynamic state. Cavitation in cryogenic fluids generates substantial thermal effects and strong variations in fluid properties, which in turn alter the cavity characteristics. To date, fewer investigate the thermal effect on cavitation in cryogenic fluids clearly by the numerical methods due to the difficulty of the heat transfer in the phase change process. In order to study the thermal effect on cavitation in cryogenic fluid, computations are conducted around a 2D quarter caliber hydrofoil in liquid nitrogen and hydrogen respectively by implementing modified Merkle cavitation model, which accounts for the energy balance and variable thermodynamic properties of the fluid. The numerical results show that with the thermal effect, the vapour content in constant location decreases, the cavity becomes more porous and the interface becomes less distinct which shows increased spreading while getting shorter in length. In the cavity region, the temperature around the cavity depresses due to absorb the evaporation latent heat and the saturation pressure drops. When the vapour volume fraction is higher, the temperature depression and pressure depression becomes larger. It is also observed that a slight temperature rise is found above the reference fluid temperature at the cavity rear end attributed to the release of latent heat during the condensation process. When the fluid is operating close to its critical temperature, thermal effects on cavitation are more obviously in both the liquid nitrogen and hydrogen. The thermal effect on cavitation in liquid hydrogen is more distinctly compared with that in liquid nitrogen due to the density ratio, vapour pressure and other variable properties of the fluid. The investigation provides aid for the design of the cryogenic pump of the liquid rocket.
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Numerical calculation of thermal effect on cavitation in cryogenic fluids
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10.3901/CJME.2012.06.1176
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2012-10-01
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Ultrahigh hardness levels greater than 700 VHN can be obtained in secondary hardening carburizing steels but depend on costly Co alloying additions to maximize hardness achieved through M_2C-type carbide precipitation strengthening. This study aims to incorporate nanometer-scale bcc Cu precipitates to both provide strength as well as catalyze M_2C nucleation in the absence of or with reduced Co. Cu additions of 1.0 and 3.7 wt pct were investigated, using a series of mechanistic models coupled with thermodynamic computational tools to derive final compositions. Thirty-pound experimental heats were cast of each designed alloy, samples of which were carburized and tempered to determine their hardness response. Characterization revealed the successful incorporation of Cu alloying additions into this family of steels, demonstrating a secondary hardening response even in the absence of Co. Matrix strength levels were close to those predicted by design models; however, all four alloys demonstrated a hardness deficit of approximately 200 VHN at the carburized surface, suggesting recalibration of the M_2C precipitation strengthening model may be required in these alloys.
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Cu-Precipitation Strengthening in Ultrahigh-Strength Carburizing Steels
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10.1007/s11661-012-1176-7
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2012-10-01
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The deformation behaviour of interstitial free/ferritic steel has been investigated at cryogenic and room temperature. The study concerns the occurrence of microstructural damages during low temperature deformation conditions for such high stacking fault energy body centred cubic material and their role on the evolution of microstructure and mechanical properties.
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Variation of Tensile Behaviour of Interstitial Free Steel Rolled at Cryogenic and Room Temperature
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10.1007/s40033-012-0012-y
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2012-10-01
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Natural convection in a liquefied natural gas storage tank, which is caused by the heat absorption from the surrounding environment, is studied numerically by solving the conservation equations for mass, momentum, and energy with a commercial computational fluid dynamics code, FLUENT. The present numerical results show that the interfacial heat transfer rate, which is directly related to the boil-offgas generation rate, strongly depends on the liquid-solid contact area. The contribution of the heat transfer rate from the vapor region is negligible compared with that from the liquid region. The effects of the external convection coefficient, tank size, and tank shape on the flow and temperature fields and on the interfacial heat flux are quantified.
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Numerical study of natural convection in a liquefied natural gas tank
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10.1007/s12206-012-0820-x
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2012-09-01
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The effect of deep cryogenic treatment on the microstructure, hardness, and wear behavior of D2 tool steel was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), hardness test, pin-on-disk wear test, and the reciprocating pin-on-flat wear test. The results show that deep cryogenic treatment eliminates retained austenite, makes a better carbide distribution, and increases the carbide content. Furthermore, some new nano-sized carbides form during the deep cryogenic treatment, thereby increasing the hardness and improving the wear behavior of the samples.
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Effect of deep cryogenic treatment on the formation of nano-sized carbides and the wear behavior of D2 tool steel
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10.1007/s12613-012-0630-2
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2012-09-01
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The alloy was reheated to 580 °C for tempering at rates of 2, 5, 10, 20, and 40 °C/s, respectively, after quenching. The amount, distribution, and stability of reversed austenite were investigated by X-ray diffraction (XRD) and electron back scatter diffraction (EBSD). The microstructure and cryogenic impact energy were studied by scanning electron microscope (SEM), transmission electron microscope (TEM) and Charpy V-notch (CVN) tests. The results showed that when the sample was heated at 10 °C/s, the volume fraction of reversed austenite exhibited maximum of 8%; the reversed austenite was uniform along all kinds of boundaries; the reversed austenite contained higher concentration of carbon which enabled it to be more stable. The cryogenic toughness of the alloy was greatly improved when heated at 10 °C/s, as the fracture surface observation showed that it mainly fractured in ductile rupture mode, which was consistent with the results of cryogenic impact energy.
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Effect of Heating Rate Before Tempering on Reversed Austenite in Fe-9Ni-C Alloy
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10.1016/S1006-706X(13)60011-4
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2012-07-01
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This study aims to present the metallurgical and mechanical characterization of cryogenically treated AISI M2 high speed steel (HSS) in terms of carbide precipitation and wear behavior. The samples of commercially available conventionally quenched and tempered AISI M2 HSS were procured and subjected to cryogenic treatment at two levels −110 °C (shallow treatment) and −196 °C (deep treatment) of temperature. The microstructures obtained after cryogenic treatments have been characterized with a prominence to comprehend the influence of cryogenic treatment vis-à-vis conventional quenching and tempering on the nature, size, and distribution of carbides. The mechanical properties such as hardness and wear rate of the specimens have also been compared by performing Rockwell C hardness test and pin-on-disc wear test, respectively. Microstructures, hardness, wear rate and analysis of worn surface reveal the underlying metallurgical mechanism responsible for the improving mechanical properties of the AISI M2 HSS.
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Effect of Cryogenic Treatment on AISI M2 High Speed Steel: Metallurgical and Mechanical Characterization
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10.1007/s11665-011-0032-z
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2012-07-01
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The thermal property of insulation material is essential in developing high temperature superconductor (HTS) devices operating at around liquid nitrogen temperature. Unlike metallic materials, nonmetallic materials have a thermal resistance; therefore, accurate estimate of the heat flow is difficult in the case of nonmetallic materials. In this study, a precise instrument is developed for measuring the thermal property of insulating materials over a temperature range of 30 K to approximately the room temperature by using a cryocooler. The cold head of the cryocooler is thermally anchored to the thermal link and used to cool the apparatus to a desired temperature. The temperature distribution in specimen is measured with respect to the supplied heating power, from which the thermal conductivity is calculated and compared with published data for accuracy confirmation. The effective thermal conductivity of polypropylene laminated paper (PPLP) is presented and the trend in the behavior of conductivity near liquid nitrogen temperature is also discussed.
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Thermal property of insulating material at cryogenic temperature
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10.1007/s12206-012-0528-y
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2012-07-01
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The gas discharge at a lower atom temperature has a number of features which can appear in experiments with dusty plasma. At cryogenic temperatures of gas-discharge tube walls, strong anisotropy of the velocity distribution function of ions takes place, which, in turn, can cause a significant change in dust structure properties. In this study, the dependences of helium ion drift characteristics in a dc uniform electric field on the temperature of own gas atoms are analyzed.
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Dependence of characteristics of helium ion diffusion and drift in own gas on its temperature
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10.3103/S1068335612070044
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2012-06-01
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Anisotropy effects in hot carrier transport have been investigated in germanium crystals at mK temperatures in the electric field range pertaining to the operation of the Edelweiss dark matter detectors. Comparative measurements have been made on n -type specimens of different impurity contents, both ultra-pure ( N _ d − N _ a <10^10 cm^−3) and doped to 10^11 cm^−3. At relatively high field intensities (≳5 V/cm), similar features of electron and hole transport are observed independent of the concentration of electrically active impurities. Differences appear at lower field (down to a fraction of a V/cm) with regard to electron straggling especially, dependent on crystal purity. These experiments demonstrate the importance on carrier transport of impurity scattering at low field, whereas phonon scattering becomes the dominant factor at higher field intensities.
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Transport Anisotropy and Impurity Scattering in Ge at Millikelvin Temperatures: Experimental Study
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10.1007/s10909-012-0548-0
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2012-06-01
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The velocity laws of electrons and holes in germanium single crystals at millikelvin temperatures are determined as a function of the electric field in the 〈001〉 orientation, based on time-of-flight measurements in cryogenic coplanar grid Ge detectors. Results obtained in two n -type crystals (| N _ a − N _ d |<10^10 cm^−3 and doped to 10^11 cm^−3) are compared with the experimental data from previous investigations, and shown to be consistent with Monte-Carlo simulations of carrier transport.
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Hot Carrier Velocities in Doped and in Ultra-pure Germanium Crystals at Millikelvin Temperatures
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10.1007/s10909-012-0535-5
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2012-06-01
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A magnetic field of a few gauss produces sizeable effects on carrier trans-port and charge collection in a germanium dark matter detector operated at millikelvin temperatures. The magnitude of the effects is explained by the large values of the velocities imparted to the carriers, even under the low electric field conditions typical for charge collection in these devices (a few 10^6 cm/s at ∼1 V/cm). Using a suitable experimental setup, effects of the magnetic field on electron and hole transport were investigated separately. A dependence of these effects on the orientation of the field relative to the detector axis is demonstrated, arising in part from magnetic flux conservation through the superconducting (Al) annular electrodes on these devices.
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Effects of a Weak Magnetic Field on Carrier Transport in a Cryogenic Germanium Detector for Dark Matter Search
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10.1007/s10909-012-0546-2
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2012-06-01
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We present new results on the development of larger arrays (presently 72 channels, goal of multiple units of 160 channels) of superconducting LC filters. The a-Si:H based resonators show a quality factor above 10.000. The latest design utilizes oppositely wound planar coil pairs which enable close packing with low magnetic cross talk. We present results on the obtained center frequency distribution within the range of 1 to 3 MHz.
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High-Q LC Filters for FDM Read out of Cryogenic Sensor Arrays
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10.1007/s10909-011-0422-5
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2012-06-01
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The read-out electronics of the EDELWEISS-II experiment is presented. Its implementation has been guided by two important design choices. The first one is putting cold electronics far from the detectors in order to attenuate possible background sources from electronic components. It implies strong constraints on noise optimization, line stray capacitance and thermal load. The second one is acquisition of fully digitized signals to minimize the E.M. noises and to take full advantage of digital processing possibilities for filtering and triggering. The resulting amplification scheme is presented for both ionization and heat channel, as well as performances of the full read-out scheme. Future prospects about the coming EDELWEISS-III experiment electronics are also discussed. This updated design takes advantage of the experience gained in previous steps of the experiment while aiming at fulfilling specific constraints of a future ton-scale experiment.
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EDELWEISS Read-out Electronics and Future Prospects
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10.1007/s10909-012-0568-9
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2012-06-01
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We report the final results of EDELWEISS-II, obtained with ten 400 g heat-and-ionization cryogenic detectors equipped with InterDigit electrodes for the rejection of near-surface events. Results from fourteen months of continuous operation and a total exposure of 384 kg day are presented. We also present the status of EDELWEISS-III, which will accumulate more than 3000 kg day of data with 40 new 800 g detectors in the coming years.
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Status and Prospects of the EDELWEISS Direct WIMP Search Experiment
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10.1007/s10909-012-0512-z
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2012-06-01
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We report the recent progress in the development of decay energy spectroscopy for radionuclide analysis using a metallic magnetic calorimeter. In the present analysis, sample radionuclides were completely enclosed by a 4 π steradian absorber. The use of a 4 π absorber composed of gold foil guarantees that the total energy associated with radioactive decay is converted into thermal energy in the absorber. A paramagnetic temperature sensor was attached to the absorber to accurately measure the temperature change due to radioactive decay. The plutonium isotopes ^238Pu, ^239Pu, and ^240Pu were readily identified in the decay energy spectrum because each isotope creates a single peak at its characteristic Q value. Two clear peaks were observed for ^239Pu and ^240Pu, and a 6.3 keV FWHM was obtained. The energy resolution of the method was affected by the low-energy tail of the spectrum at the left-hand side of the peaks. A 4.1 keV FWHM of a Gaussian fit was obtained for the right-hand side of the peak. Slow heat release to the absorber due to heat flow mechanisms is discussed to explain the low-energy tailing effect.
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Development of Decay Energy Spectroscopy for Radionuclide Analysis Using Cryogenic 4π Measurements
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10.1007/s10909-012-0477-y
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2012-06-01
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In this work, we use 10.36 and 8.98 keV X-rays originating from the decay of ^68Ge and ^65Zn which are homogeneously produced in a Ge crystal in order to evaluate the fiducial volume of a 400 g coplanar grid HP-Ge bolometers in operation in the Edelweiss-II experiment. Different energy estimators are tested on the experimental data and a fiducial fraction of (39.9±5)% is found. The results are compared to simulations taking into account the anisotropy of the electron transport in Ge.
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Fiducial Volume of the Edelweiss Germanium Bolometers for Dark Matter Search Using Cosmogenic Activation
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10.1007/s10909-012-0566-y
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2012-06-01
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The Cryogenic Dark Matter Search (CDMS) utilizes large mass, 3″ diameter × 1″ thick target masses as particle detectors. The target is instrumented with both phonon and ionization sensors and comparison of energy in each channel provides event-by-event classification of electron and nuclear recoils. Fiducial volume is determined by the ability to obtain good phonon and ionization signal at a particular location. Due to electronic band structure in germanium, electron mass is described by an anisotropic tensor with heavy mass aligned along the symmetry axis defined by the [111] Miller index (L valley), resulting in large lateral component to the transport. The spatial distribution of electrons varies significantly for detectors which have their longitudinal axis orientations described by either the [100] or [111] Miller indices. Electric fields with large fringing component at high detector radius also affect the spatial distribution of electrons and holes. Both effects are studied in a 3 dimensional Monte Carlo and the impact on fiducial volume is discussed.
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Comparison of CDMS [100] and [111] Oriented Germanium Detectors
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10.1007/s10909-011-0427-0
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2012-06-01
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Thermally-stimulated current measurements provide a sensitive tool to characterize carrier traps in germanium detectors for direct dark matter search. Using this technique at cryogenic temperatures, very shallow traps have been detected with binding energies of a fraction of a meV, associated with the dopant species in the D ^−( A ^+) charge states. A positive identification of these traps is achieved through an analysis of the field dependence of the carrier emission rates, which demonstrates a potential well for the trapped carriers in the form of a polarization well in r ^−4, consistent with Lax’s model for carrier trapping by a neutral center. The density of these traps is assessed, and implications for the space-charge cancellation procedure in cryogenic Ge detectors are discussed.
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Thermally-Stimulated Current Investigation of Dopant-Related D
^− and A
^+ Trap Centers in Germanium for Cryogenic Detector Applications
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10.1007/s10909-012-0547-1
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2012-06-01
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Superconducting QUantum Interference Device (SQUID) multiplexing is a common technique in the use of large arrays of Transition Edge Sensors (TES). A Time Domain Multiplexer (TDM) combines input TES signals into one output signal using several SQUIDs. Different TES, SQUID and amplifier characteristics induce unavoidable different offsets on the multiplexed signal. Additionally, given the periodicity of the SQUID characteristic, the Flux Locked Loop (FLL) operating point is only defined modulo Φ _0. This can lead to a large output offset. In multiplexed mode, the difference between offsets associated with different pixels can induce a parasitic signal which is often larger than that of the TES. These offset signals drastically constrain the readout dynamic range and thus the maximum gain allowed. They also limit the signal-to-noise ratio, the FLL stability and the multiplexing frequency. Offsets in SQUID readout are discussed and offset compensation for TDM is presented. The dynamic calibration and compensation on a simplified 4:1 TDM are demonstrated in simulation. Dynamic offset compensation is being implemented on a cryogenic SiGe integrated circuit operated at 4 K for 128:1 TDM.
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Cryogenic Integrated Offset Compensation for Time Domain SQUID Multiplexing
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10.1007/s10909-012-0606-7
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2012-06-01
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Beyond the present dark matter direct detection experiment at the Soudan underground laboratory, the SuperCDMS Collaboration is engaged in R&D activities for a 100-kg scale germanium dark matter experiment nominally sited at SNOLAB (2070 m overburden of rock). The expected sensitivity after 3 years of running is 3×10^−46 cm^2 for the spin-independent cross section, an order of magnitude improvement over present exclusion limits for WIMP masses ∼80 GeV/c^2. At this depth, and appropriate design of shielding and cryostat, neutron backgrounds will be negligible. The baseline design is an expanded version of CDMS II with Ge substrates (100×33 mm discs) instrumented with the iZIP phonon sensor layout to achieve the electron surface-event rejection power required.
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Conceptual Design for SuperCDMS SNOLAB
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10.1007/s10909-011-0440-3
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2012-06-01
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Improving upon the present background rejection capabilities of the cryogenic germanium detectors for direct dark matter search involves an in-depth comprehension of the charge collection process in these devices. Experimental data point to the combined effects of lattice and impurity scattering on the anisotropy of electron transport in Ge at mK temperatures. A Monte Carlo simulation code has been implemented to incorporate these features in a consistent model for charge collection. In a novel approach to carrier scattering by charged impurities in Ge at cryogenic temperatures, the scattering field of the impurities is treated statistically as a random contribution to the collection field, described by the Holtsmark distribution function with a single adjustable parameter, the mean density of the charged centers. Simulation of charge collection along these lines in devices different by their impurity content shows excellent agreement to experiment. Especially noteworthy is the fact that the strength of impurity scattering is reversed from the known concentration of dopant impurities in the crystals, as the crystal with the higher dopant concentration shows lower scattering at low field than the one with the lower concentration. This raises as an issue for further improvement of these devices, the question of the nature of the scattering centers in high-purity Ge crystals at cryogenic temperatures, associated presumably with deep level impurities or crystal defects.
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Carrier Anisotropy and Impurity Scattering in Ge at mK Temperatures: Modeling and Comparison to Experiment
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10.1007/s10909-012-0543-5
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2012-06-01
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We discuss the current design of the cold hardware and cold electronics to be used in the upcoming SuperCDMS Soudan deployment. Engineering challenges associated with such concerns as thermal isolation, microphonics, radiopurity, and power dissipation are discussed, along with identifying the design changes necessary for SuperCDMS SNOLAB. The Cryogenic Dark Matter Search (CDMS) employs ultrapure 1-inch thick, 3-inch diameter germanium crystals operating below 50 mK in a dilution cryostat. These detectors give an ionization and phonon signal, which gives us rejection capabilities regarding background events versus dark matter signals.
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SuperCDMS Cold Hardware Design
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10.1007/s10909-012-0584-9
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2012-06-01
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The Cryogenic Dark Matter Search (CDMS) utilizes large mass, 3″ diameter×1″ thick target masses as particle detectors. The target is instrumented with both phonon and ionization sensors, the later providing a ∼1 V cm^−1 electric field in the detector bulk. Cumulative radiation exposure which creates ∼200×10^6 electron-hole pairs could be sufficient to produce a comparable reverse field in the detector thereby degrading the ionization channel performance, if it was not shielded by image charges on the electrodes. To study this, the existing CDMS detector Monte Carlo has been modified to allow for an event by event evolution of the bulk electric field, in three spatial dimensions. Surprisingly, this simple model is not sufficient to explain the degradation of detector performance. Our most recent results and interpretation are discussed.
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Time Evolution of Electric Fields in CDMS Detectors
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10.1007/s10909-012-0465-2
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2012-06-01
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Our purpose of this study is to realize the submillimeter/terahertz camera with large number of pixels (>10 k). To realize such a camera, we have investigated the cryogenic multi-channel readout system with cryogenic ICs (Integrated Circuits) made up with n-channel GaAs-JFETs. Based on previous investigations, we designed and manufactured the multi-chip module with the cryogenic ICs. This multi-chip module is designed to multiplex 32-channel parallel input current signals into 2 serial voltage signals. Estimated maximum reset frequency of current integration amplifiers is 3 kHz and estimated total power dissipation is about 400 μW. The size of this module is 40 mm×30 mm×2 mm. We have demonstrated operation of these modules and preparing integration of these modules with the STJ (Superconductor Tunnel Junction) photon direct detectors.
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The Cryogenic Multi-Channel Readout System for Submillimeter/Terahertz Cameras
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10.1007/s10909-012-0595-6
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2012-06-01
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We report on precise drift velocity measurements of electrons and holes in 50 mK, ultrapure (≈10^10 net shallow impurities per cm^3) germanium 〈100〉 CDMS dark matter detectors as a function of electric field up to 4 V/cm. A laser diode connected to an optical fiber extending from room-temperature to the detector creates electron-hole pairs on one surface of the crystal. High-speed electronics measure the drift current as the generated carriers travel to the opposite face of the crystal. CDMS detectors measure the ionization and phonon response of particle interactions within the crystal. Stable charge collection is necessary for successful background discrimination when looking for a possible dark matter signal. While biased, however, ionization performance degrades over time due to the build-up of space charge. Free electrons and holes created by particle interactions are subject to drift-diffusion dynamics occurring simultaneously with the trapping of carriers to localized surface and bulk states. The combination of these processes determine the evolution of space charge within the crystal, making it important that we understand carrier transport under our unique operating condition of low-temperature and low-field. We find good agreement between our measured drift velocities and our theoretical predictions, indicating carrier scattering is dominated by spontaneous phonon emission. In addition, we present preliminary measurements of effective longitudinal carrier trapping lengths for both n-type and p-type crystals at 50 mK.
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Optically Induced Measurement of Electron and Hole Drift Velocities in a Germanium 〈100〉 CDMS Detector at 50 mK
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10.1007/s10909-012-0472-3
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2012-06-01
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In this study, a series of Sn-doped (Bi_85Sb_15)_1− x Sn_ x ( x = 0, 0.025, 0.05, 0.1, 0.2, 0.3) thermoelectric materials was fabricated through mechanical alloying followed by pressureless sintering. The crystal structure was characterized by x-ray diffraction. The electrical transport properties and thermal properties were measured in the temperature range from 77 K to 300 K. The electrical transport as a function of temperature appeared to be characteristic of a semimetal. The Seebeck coefficient gradually changed from negative to positive with increasing Sn doping, showing p -type electrical transport properties. It is found that the Seebeck coefficients of the p -type Bi-Sb alloys decrease with increasing dopant concentration of Sn, which may be due to increasing carrier concentration. Among the p -type alloys, the power factor of (Bi_85Sb_15)_0.975Sn_0.025 reached a maximum value of 1.3 × 10^−3 W/mK^2 at 265 K, and the optimum figure of merit value of 0.13 was obtained at 240 K. The results indicate that good p -type Bi-Sb alloys can be prepared by this synthesis procedure.
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Thermoelectric Performance of p-Type (Bi_85Sb_15)_1−x
Sn_
x
Materials Prepared by a Pressureless Sintering Technique
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10.1007/s11664-012-2063-0
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2012-06-01
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Russian institutes will participate in setting up the experiments HIHEX (Heavy Ion Heating and Expansion) and LAPLAS (Laboratory Planetary Sciences) as part of the FAIR program of scientific research. The appropriate numerical calculations of targets and preliminary experiments will be performed. Two vacuum chambers for studying the thermodynamic, transport, and optical properties of extreme states generated when matter is heated by intense heavy-ion beams will be developed and built. A system for obtaining a cylindrical beam and the corresponding cryogenic system for the LAPLAS experiments will be developed and built. Special attention will be focused on the development of proton radiography for diagnostics of extreme states of matter.
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Study of the fundamental properties of matter at high energy density created by an intense ion beam
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10.1007/s10512-012-9536-3
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2012-06-01
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The direct detection of the Universe’s Dark Matter is one of the key questions in particle astrophysics. Cryogenic based detectors offer advantages in low radioactive backgrounds, target mass, sensitivity to the small energy depositions and rejection of possible background sources. I will summarize the main experimental approaches, including both cryogenic crystal and liquid targets and the options pursued for their signal readout. Recent advances from around the world and prospects for future proposed experiments will be discussed.
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Review of Dark Matter Direct Detection Using Cryogenic Detectors
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10.1007/s10909-012-0517-7
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