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2018-07-01
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This paper is a review of the series of investigations carried out at the S. A. Khristianovich Institute of Theoretical and Applied Mechanics (ITAM, Siberian Branch of the Russian Academy of Sciences (RAS)) aimed at solving the sonic boom problem. It has been shown, with the example of flow over a body of revolution at Mach number M = 2, that a decrease in the flow temperature near the body leads to a change in the flow structure in the region of the formation of a hanging shock wave and a decrease (by 12%) in the sonic boom intensity on the ground. The results are presented of investigations of the influence of the relative position and geometrical shape of configuration elements of a supersonic passenger airplane on the sonic boom parameters at long distances from the disturbance source. The prospective aspect of the supersonic passenger airplane providing the minimum level of sonic boom in cruising flight has been determined. The scheme (IZS method) for measuring in the experiment disturbed pressure profiles at a given distance from the investigated model has been described.
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Investigations of the Sonic Boom Problem at the Institute of Theoretical and Applied Mechanics, Siberian Branch of the Russian Academy of Sciences
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10.1007/s10891-018-1838-4
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2018-07-01
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Considering the poor lubricating effect of cryogenic air (CA) and inadequate cooling ability of nanofluid minimum quantity lubrication (NMQL), this work proposes a new manufacturing technique cryogenic air nanofluid minimum quantity lubrication (CNMQL). A heat transfer coefficient and a finite difference model under different grinding conditions were established based on the theory of boiling heat transfer and conduction. The temperature field in the grinding zone under different cooling conditions was simulated. Results showed that CNMQL exerts the optimal cooling effect, followed by CA and NMQL. On the basis of model simulation, experimental verification of the surface grinding temperature field under cooling conditions of CA, MQL, and CNMQL was conducted with Ti–6Al–4V as the workpiece material. Simultaneously, CNMQL exhibits the smallest specific tangential and normal grinding forces (2.17 and 2.66 N/mm, respectively). Further, the lowest grinding temperature (155.9 °C) was also obtained, which verified the excellent cooling and heat transfer capabilities of CNMQL grinding. Furthermore, the experimental results were in agreement with theoretical analysis, thereby validating the accuracy of the theoretical model.
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Temperature field model and experimental verification on cryogenic air nanofluid minimum quantity lubrication grinding
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10.1007/s00170-018-1936-7
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2018-07-01
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The focus of this work is to highlight the relative response of Al-based micro- and nanocomposites in the form of enhancement in flexural strength via induced thermal stresses at high and cryogenic temperatures in ex situ and in situ atmospheres. In this investigation, we have tried to explore the reliability, matrix-reinforcement interaction and microstructural integrity of these materials in their service period by designing appropriate heat treatment regimes. Al-Al_2O_3 micro- and nanocomposites had been fabricated by powder processing method. The micro- and nanocomposites were subjected to down-thermal shock (from positive to negative temperature) and up-thermal shock (from negative to positive temperature) with varying thermal gradients. For isothermal conditioning, the composites were exposed to + 80 and − 80 °C for 1 h separately. High-temperature three-point flexural tests were performed at 100 and 250 °C on the composites. All the composites subjected to thermal shock and isothermal conditioning was tested in three-point flexural mode post-treatments. Al-1 vol.% Al_2O_3 nanocomposite’s flexural strength improved to 118 MPa post-thermal shock treatment of gradient of 160 °C. The Al-5 and 10 vol.% Al_2O_3 microcomposites possessed flexural strength of 200 and 99.8 MPa after thermal shock treatment of gradient of 160 and 80 °C, respectively. The observed improvement in flexural strength of micro- and nanocomposites post-thermal excursions were compared and have been discussed with the support of fractography. The microcomposites showed a higher positive scale of response to the thermal excursions as compared to that of the nanocomposites.
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Response of Al-Based Micro- and Nanocomposites to Rapid Fluctuations in Thermal Environments
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10.1007/s11665-018-3437-0
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2018-07-01
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Ferroelectrics are utilized in a myriad of technological applications including vibration damping due to their inherent electromechanical coupling. Through the domain structure in ferroelectric ceramics, the high stiffness material can also exhibit high damping. The combination of high stiffness and high damping is an elusive property in engineering materials. Nonetheless, high stiffness and damping materials would be useful in load-bearing structures that are subjected to vibrations, in particular in space structures. Applying an electric field to ferroelectrics has shown promise for achieving this desirable combination of properties. However, there is limited knowledge on how the dynamic electromechanical properties of ferroelectrics change in a space environment (in particular at cryogenic temperatures), which has limited the exploitation of this ferroelectric property in space structures. This is due in part to the lack of experimental methods to measure such properties. To close this gap, cryogenic broadband electromechanical spectroscopy (CBES) was developed to measure the dynamic electromechanical response of ferroelectrics, viz. lead zirconate titanate, at cryogenic temperatures. In particular, CBES is used to measure simultaneously, for the first time, the dynamic stiffness, loss tangent, and electric displacement response of ferroelectrics subjected to large electric fields at cryogenic temperatures as low as 34 K. Measurements reveal a decrease in the amount of electric field-induced domain switching (and corresponding thermodynamic driving force) and the resulting mechanical damping. This points toward the need to develop alternative material compositions and microstructures for utilizing domain switching-induced damping in space structures.
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Dynamic Electromechanical Characterization of Ferroelectrics at Cryogenic Temperatures
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10.1007/s11340-018-0395-2
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2018-07-01
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We investigate the conditions when the motion of a heavy ball in a helical channel takes the form of rolling or rolling with partial sliding. This problem is relevant for the manufacturing technology of unsuspended spherical laser targets being developed at the thermonuclear target laboratory at the Lebedev Physics Institute of the Russian Academy of Sciences. While moving through the cryostat channel, the laser target may slide part of the way, which causes undesirable damage to its surface. We study the possible motion regimes with the objective of determining the optimal regime that minimizes the sliding length.
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Necessary and Sufficient Conditions of Rolling and Sliding of a Spherical Shell in a Helical Channel
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10.1007/s10598-018-9408-3
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2018-07-01
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This paper presents the results of experimental investigation of the effects of three cooling strategies (minimum quantity lubrication (MQL), cryogenic cooling using liquid nitrogen (LN_2), and combined (MQL + LN_2)) and three tool coatings (uncoated and AlTiN- and GMS^2-coated) on cutting force components ( F _ x , F _ y , F _ z ); the resultant cutting force, F _ r ; and cutter tooth frequency in peripheral high--speed end milling of Inconel-718 to improve machinability and reduce cost. All the experiments were conducted on a Cincinnati Milacron Sabre 750 vertical machining center (VMC), equipped with Acramatic 2100 CNC controller using uncoated and AlTiN- and GMS^2-coated solid carbide bull-nose helical end mills of 12.7 mm (0.5 in.) diameter, and 0.762 mm (0.03 in.) corner radius. Each experiment consisted of eight passes, each pass of 76.2 mm (3 in.) cutting length. Axial and radial depths of cut, cutting speed, and material removal rate were kept constant for all experiments. The experimental results show that uncoated end mills generated lowest resultant cutting forces, whereas GMS^2-coated end mills generated highest resultant cutting forces under all cooling strategies. MQL cooling strategy generated lowest resultant cutting forces, whereas LN_2 cooling strategy generated highest resultant cutting forces for all end mill coatings. Using LN_2 cooling strategy alone is not recommended for machining Inconel-718 due to high cutting forces and vibrations. Uncoated end mills under MQL cooling strategy generated the lowest cutting forces and are recommended for machining Inconel-718, whereas GMS^2-coated end mills under LN_2 cooling strategy generated highest cutting forces.
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Effects of cooling strategies and tool coatings on cutting forces and tooth frequency in high-speed down-milling of Inconel-718 using helical bull-nose solid carbide end mills
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10.1007/s00170-018-2096-5
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2018-07-01
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In this study, milling of the Inconel 718 superalloy was performed in dry conditions with the aim of reducing the adverse effects of the coolant on the environment. As is known, cutting tools quickly complete their life due to the high-temperature on the cutting zone in the dry condition milling process of hard materials. The nanocomposite TiAlSiN/TiSiN/TiAlN thin film was deposited on the cutting tools and then subjected to cryogenic heat treatment to increase the tool life of the used cutting tools. As a result, the life of the cutting tools has been increased by the thin film coating and cryogenic heat treatment applied to the cutting tools. After cryogenic treatment at a cutting speed of 30 m/min, the tool life of uncoated, TiN-, nanocomposite TiAlSiN/TiSiN/TiAlN-, and TiAlN-coated carbide cutting tools increases by 54, 110, 29, and 30%. The applied cryogenic heat treatment resulted in an 18% increase in the hard η phase of the structure of the carbide cutting tools. In addition, cryogenic heat treatment improved the adhesion of hard coatings to the substrate. The EDS analysis applied to the worn tools revealed that the mechanisms causing wear of the cutting tools were abrasion and adhesion.
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Improvement of cutting performance of carbide cutting tools in milling of the Inconel 718 superalloy using multilayer nanocomposite hard coating and cryogenic heat treatment
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10.1007/s00170-018-1931-z
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2018-06-05
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Introduction In the field of the high injection rate X-ray meterage, currently there are no national standards in China, which are urgently needed in areas such as inertial confinement fusion diagnosis and aerospace observation. Globally, many metrology laboratories have developed their own meterage standards based on Cryogenic radiometers. And one soft X-ray cryogenic radiometer has been installed at 4B7B experiment station on Beijing Synchrotron Radiation Facility to measure the X-ray power from 50 nW to 1 $$\upmu \hbox {W}$$ μ W . Purpose The purpose is to verify the accuracy of the X-ray power measurement and the performance of the cryogenic radiometer. Experimental The spectral responsivity of a Si photodiode detector calibrated in the Physikalisch-Technische Bundesanstalt of Germany is calibrated at 750 eV again with the cryogenic radiometer based on synchrotron light source. Results Some important performance parameters (e.g., time constant, responsivity, and nonequivalence error) of the cryogenic radiometer were measured and were in agreement with the design indexes. Calibration results show that total relative uncertainties of X-ray power measurement were below 1% ( $$k=1)$$ k = 1 ) , and that good consistency was received compared with the calibrations done by the PTB. Conclusion The cryogenic radiometer built at 4B7B is reliable and accurate for soft X-ray power measurement. And the performance of the cryogenic radiometer is also very good.
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A soft X-ray cryogenic radiometer built on BSRF
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10.1007/s41605-018-0062-2
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2018-06-01
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A cryogenic scanning electron microscopy (cryo-SEM) technique was used to explore the shear-thickening behavior of Fe-ZSM5 zeolite pastes and to discover its underlying mechanism. Bare Fe-ZSM5 zeolite samples were found to contain agglomerations, which may break the flow of the pastes and cause shear-thickening behaviors. However, the shear-thickening behaviors can be eliminated by the addition of halloysite and various boehmites because of improved particle packing. Furthermore, compared with pure Fe-ZSM5 zeolite samples and its composite samples with halloysite, the samples with boehmite (Pural SB or Disperal) additions exhibited network structures in their cryo-SEM images; these structures could facilitate the storage and release of flow water, smooth paste flow, and avoid shear-thickening. By contrast, another boehmite (Versal 250) formed agglomerations rather than network structures after being added to the Fe-ZSM5 zeolite paste and resulted in shear-thickening behavior. Consequently, the results suggest that these network structures play key roles in eliminating the shear-thickening behavior.
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Shear-thickening behavior of Fe-ZSM5 zeolite slurry and its removal with alumina/boehmites
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10.1007/s12613-018-1615-6
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2018-06-01
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The growing use of energy by most of world population and the consequent increasing demand for energy are making unexploited low quality gas reserves interesting from an industrial point of view. To meet the required specifications for a natural gas grid, some compounds need to be removed from the sour stream. Because of the high content of undesired compounds (i.e., CO_2) in the stream to be treated, traditional purification processes may be too energy intensive and the overall system may result unprofitable, therefore new technologies are under study. In this work, a new process for the purification of natural gas based on a low temperature distillation has been studied, focusing on the dynamics of the system. The robustness of the process has been studied by dynamic simulation of an industrial-scale plant, with particular regard to the performances when operating conditions are changed. The results show that the process can obtain the methane product with a high purity and avoid the solidification of carbon dioxide.
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Study of the robustness of a low-temperature dual-pressure process for removal of CO_2 from natural gas
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10.1007/s11705-017-1688-1
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2018-06-01
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The present work applies the finite element method to calculate the maximum allowable time that cryogenic inertial confinement fusion (ICF) targets can be exposed to infrared radiation (IR). Hence, a 3-D numerical model integrated with discrete coordinate radiation model was developed to investigate the influence of transmittance of the laser entrance holes (LEHs) and boundary conditions on the temperature field distribution and the maximum DT layer deterioration time for CH, Be, and diamond capsules. Our study shows that introducing such a radiation model can accurately obtain more detailed spatial and temporal distribution information in the ICF targets. The simulation results demonstrate that the Be and diamond capsules provided much better temperature field homogenization than the CH capsule under equivalent boundary conditions, but the CH capsule was heated more by IR radiation than the Be and diamond. In addition, the maximum DT layer deterioration time was significantly increased to 3 s when decreasing the transmittance of the LEH from 0.2 to 0.01. However, either reducing the capsule IR absorption or increasing the inner hohlraum IR absorption demonstrated no conclusive increase in the maximum DT layer deterioration time. These results are expected to provide useful parameters in the design of cryogenic targets and shroud systems.
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Numerical Analysis of the Effect of Infrared Radiation on Cryogenic Inertial Confinement Fusion Targets
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10.1007/s10894-018-0155-4
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2018-06-01
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This paper first develops a cryogenic cutting system with adjustable jet temperature (− 196~20 °C), and then carries out a series of dry cutting and cryogenic turning experiments for titanium alloy. Metallographic microscope is used to observe the chip morphology of titanium alloy and the geometric characteristic parameters of the chip are measured using a Digimizer image measurement software. The influence of cutting speed and cooling conditions on the chip morphology, chip height ratio, and serrated pitch has been analyzed. The experimental results reveal that the cutting speed and cooling conditions play significant roles on the chip morphology and serrated characteristics of titanium alloy. During the cryogenic cutting process, with the increase of cutting speed, the chip height ratio and serrated pitch of titanium alloy chip increase. It has been found that under the condition of cryogenic cutting, the lower jet temperature, the more obvious serrated characteristic of titanium alloy chip. It is also found that the fibrous adiabatic shear band exists in the shear zone; the chip height ratio and serrated pitch remarkably increase.
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Experimental study on chip deformation of Ti-6Al-4V titanium alloy in cryogenic cutting
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10.1007/s00170-018-1890-4
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2018-06-01
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This paper is devoted to the assessment of wall interference in the slotted wall test section of the European Transonic Windtunnel (ETW) over a wide range of Reynolds numbers. The experimental part of the investigation was performed in February 2014 by testing the NASA Common Research Model mounted on a fin-sting support. These tests were carried out within the scope of the ESWIRP project funded by the European Commission in the 7th framework program. The numerical research was based on the Electronic WindTunnel (EWT-TsAGI) software with a cryogenic solver. The assessed Mach number influence on the wall signatures revealed a very similar effect to applying the classical Prandtl–Glauert rule over the investigated Mach number range. Practically, no Reynolds number effects on the wall pressure distributions generated by the model and its support system could be identified over the wide range of Re numbers investigated. The first attempt of the EWT-TsAGI code application for a simulation of ETW tests featuring the model in the slotted wall tunnel showed a fair coincidence of the pressure coefficient distribution on test section walls in the model region, on the wing-root sections and the drag polar at moderate lift coefficient values.
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A numerical approach for assessing slotted wall interference using the CRM model at ETW
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10.1007/s13272-017-0248-1
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2018-05-31
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A cryogenic permanent magnet undulator prototype designed for Chinese High Energy Photon Source Test Facility (HEPS-TF) at Institute of High Energy Physics is constructed and now commissioning. Motion precision of girders is a significant parameter to guarantee gap error so as to avoid phase error and radiation intensity loss. In order to study and minimize girder parallelism errors, RADIA and SPECTRA are used to calculate qualified motion precision. Spring Modules and single motor closed-loop feedback are designed to compensate the errors. Magnetic field is finally tuned to reach specifications. Details of the study and analysis will be presented in this paper.
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Influence of cryogenic permanent magnet undulator motion error on magnetic field error and radiation intensity loss
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10.1007/s41605-018-0063-1
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2018-05-05
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Purpose High energy photon source test facility (HEPS-TF) has manufactured a three-dimensional Hall probe to measure the cryogenic permanent magnet undulator (CPMU). Since the operating environment of the CPMU is the subcooled liquid nitrogen (85K), the temperature of the Hall probe will have a decrease of several degrees while carrying out the local magnetic measurement. We established a magnetic field strength and temperature-dependent calibration system to calibrate the Hall probe. Methods The magnetic field strength of the Hall probe was calibrated by a standard dipole electromagnet and a nuclear magnetic resonance Tesla meter (NMR). The temperature of Hall probe was controlled by a control system which can modulate temperature from $$0^{\circ }$$ 0 ∘ C to $$30^{\circ }$$ 30 ∘ C. Results A new homemade Hall probe has finished the temperature-dependent ( $$0^{\circ }$$ 0 ∘ C to $$30^{\circ }$$ 30 ∘ C), magnetic field strength (-1.2 to 1.2 T) and angle error calibration at this new calibration system. The temperature correction error is less than 0.045%. The calibration error of magnetic field strength is less than 1.5 Gs. The RMS calibration error of Hall sensors angle matrix is less than 5.1E-5. Conclusion The magnetic field strength and temperature-dependent calibration system including a standard dipole electromagnet, a temperature regulation system, an NMR and a five-dimensional Hall bench was established. The detailed magnetic field strength and temperature-dependent calibration system is introduced and the results of the calibrations are presented.
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Magnetic field strength and temperature-dependent calibration system of Hall probe for the HEPS-TF cryogenic permanent magnet undulator
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10.1007/s41605-018-0050-6
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2018-05-01
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The world runs a serious risk of sliding into catastrophic climate change. It is to all practical purposes impossible to bring the emissions of greenhouse gases to a halt straight away. This article discusses a number of sources of uncertainty and the possibility of bias in climate forecasting. It identifies a specific approach towards rapid decarbonization combined with a systematic reduction in fossil fuel extraction: the manufacture of synthetic hydrocarbon compounds for use as fuel as well as plastics, using carbon dioxide from power stations and cement factories as feedstock during a transitional phase. Policymakers and even researchers working on renewable energy seem to be insufficiently aware of the potential of this mature chemical technology to reduce emissions. The paper also surveys several economic and managerial issues regarding the implementation of the transition to a world using only renewable energy, and provides some information concerning the latest state of the technology of renewable electricity generation.
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Synthetic carbohydrate compounds and their integration with renewable electricity supplies
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10.1007/s10098-018-1509-3
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2018-05-01
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Commercially pure titanium is used for low-temperature applications due to good toughness attributed to single-phase microstructure (α). Electron beam welding (EBW) and gas tungsten arc welding (GTAW) processes have been used for welding two grades of commercially pure titanium (Grade 2 and Grade 4). Martensitic microstructure is found to be finer in the case of EBW joint as compared to GTAW joint due to faster rate of cooling in the former process. Weldments have been characterized to study the mechanical behavior at ambient (298 K) and cryogenic temperatures (20 and 77 K). Strength of weldments increases with the decrease in temperature, which is found to be more prominent in case of Grade 4 titanium as compared to Grade 2. Weld efficiency of Grade 4 is found to be higher at all the temperatures (ambient, 77 and 20 K). However, ultimate tensile strength/yield strength ratio is higher for Grade 2 as compared to Grade 4. % Elongation is found to increase/retained at cryogenic temperatures for Grade 2, and it is found to decrease for Grade 4. Electron backscattered diffraction analysis and transmission electron microscopy of deformed samples confirmed the presence of extensive twinning in Grade 2 and the presence of finer martensitic structure in Grade 4. Fractography analysis of tested specimens revealed the presence of cleavage facets in Grade 4 and dimples in specimens of Grade 2. Higher strength in Grade 4 is attributed to higher oxygen restricting the twin-assisted slip, which is otherwise prominent in Grade 2 titanium.
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Mechanical Behavior of Commercially Pure Titanium Weldments at Lower Temperatures
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10.1007/s11665-018-3307-9
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2018-05-01
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The paper considers the processes related to the specimens and loading device in the tensile testing of metals in strain-controlled mode, including under the conditions of cryogenic temperatures up to 4.2 K. It is demonstrated how the potential elastic energy accumulation and its subsequent relaxation in the development of the specimen strain affect the process of kinetics. The strain rate dependencies on the strain value and stiffness factor (relation between the values of stiffness of the specimen and the machine) are obtained. Noteworthy is that the values of initial and nominal strain rates can differ by an order of magnitude in case of the machine compliance. To obtain the strain rates that are similar for different machines at the initial stage of the process, the formula is proposed allowing one to calculate the required nominal rate. At the temperatures lower than 30 K there is a dramatic increase of the influence of the machine stiffness, dimensions and shape of the specimens on the obtained characteristics, which requires the special measures in the process of testing. Some international and national standards are considered. It is shown that, at present, the process of standardization for tensile testing of metals is inadequate, and the requirements of the current regulatory documents are the minimum, which are not in agreement with the development paces of testing equipment. To significantly enhance the level of accuracy of the obtained mechanical characteristics, it is required to employ the urgent measures as the machine compliance limitation, as well as the decrease of the dimensions range for the specimens together with the standardization of the permissible range of the stiffness factor, and the required selection of the nominal strain rate considering the latter.
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On the Accuracy in Determination of the Mechanical Material Characteristics at Low Temperatures
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10.1007/s11223-018-9993-6
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2018-05-01
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This study investigates the heat transfer characteristics of an insulated double pipe in accordance with the degree of vacuum and the working fluid pressure for liquefied natural gas transportation. A total of 16 cases were examined, and the degree of vacuum was set at 760, 0.1, 0.01 and 0.001 torr. Meanwhile, the working fluid pressure was set at 1, 3, 5 and 7 bar to analyze the effect of variables. A correlation analysis based on statistics was performed to quantitatively study the temperature distribution and the heat transfer characteristics. An approximated formula on the quantity of heat depending on the thermal conductivity of rarefied gas was also calculated. The approximated curve was compared with the theory formula. Consequently, the heat insulation property was improved in proportion to the degree of vacuum. A comparison of the approximated curve and the theory formula further showed that thermal conductivity was dominant at a high degree of vacuum.
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Statistical experimental study for verifying thermal characteristics of insulated double pipe
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10.1007/s12206-018-0443-y
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2018-04-01
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Titanium alloys have been attracting interest in aerospace industries because of their high strength-to-weight ratio. However, they are classified as difficult-to-machine materials due to poor tool life in machining processes. Cryogenic machining is a process that uses liquid nitrogen (LN2) as a coolant, and proposed as a method to enhance tool life in the present study. This paper presents a theoretical study to develop a predictive cutting force model for cryogenic machining of Ti-6Al-4V. A modified (in terms of cutting temperature) Johnson-Cook model that considers phase transformation, and a friction coefficient were used as input parameters for inclusion of the cryogenic cooling effect. The predictive cutting force model was validated based on an orthogonal cutting test. The predicted forces showed good agreement with the experimental data, with minimum and maximum error magnitudes of 1.9 and 17.7% for cutting force, and 0.3 and 32.8% for thrust force, respectively. Investigation of the effects of cryogenic cooling on the cutting force, micro-structure, surface integrity and burr height were conducted. The cutting force during cryogenic machining was increased compared to dry machining by a martensitic phase transformation of the work material. There was no effect of cooling condition on the surface roughness. The burr height under cryogenic conditions was decreased by 56.2 and 28.2% compared to the dry and wet conditions, respectively.
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Predictive cutting force model for a cryogenic machining process incorporating the phase transformation of Ti-6Al-4V
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10.1007/s00170-018-1606-9
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2018-04-01
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The ITER magnet system is based on the “cable-in-conduit” conductor (CICC) concept, which consists of stainless steel jackets filled with superconducting strands. The jackets provide high strength, limited fatigue crack growth rate and fracture toughness properties to counteract the high stress imposed by, among others, electromagnetic loads at cryogenic temperature. Austenitic nitrogen-strengthened stainless steels have been chosen as base material for the jackets of the central solenoid and the toroidal field system, for which an extensive set of cryogenic mechanical property data are readily available. However, little is published for their welded joints, and their specific performance when considering different combinations of parent and filler metals. Moreover, the impact of post-weld heat treatments that are required for Nb_3Sn formation is not extensively treated. Welds are frequently responsible for cracks initiated and propagated by fatigue during service, causing structural failure. It becomes thus essential to select the most suitable combination of parent and filler material and to assess their performance in terms of strength and crack propagation at operation conditions. An extensive test campaign has been conducted at 7 K comparing tungsten inert gas (TIG) welds using two fillers adapted to cryogenic service, EN 1.4453 and JK2LB, applied to two different base metals, AISI 316L and 316LN. A large set of fracture toughness data are presented, and the detrimental effect on fracture toughness of post-weld heat treatments (unavoidable for some of the components) is demonstrated. In this study, austenitic stainless steel TIG welds with various filler metals have undergone a comprehensive fracture mechanics characterization at 7 K. These results are directly exploitable and contribute to the cryogenic fracture mechanics properties database of the ITER magnet system. Additionally, a correlation between the impact in fracture toughness and microstructure resulting from the above treatment is provided.
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A Comparative Study of Fracture Toughness at Cryogenic Temperature of Austenitic Stainless Steel Welds
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10.1007/s11665-018-3266-1
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2018-03-01
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The performance of the upstream moderator for neutron beams 1, 4, 5, 6, and 9 extracted from the IBR-2 reactor is simulated towards selecting its optimum configuration. For different moderator options, gain factors with respect to the existing comb-shaped water moderator are computed. Taking into account the technological issues in manufacturing a combined moderator, the scheme with optimal physical characteristics is selected.
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Optimization and Comparing a Different Various of Head Part of a Moderator of “Central” Direction for IBR-2 Reactor
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10.1134/S1547477118020103
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2018-03-01
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This paper presents the first comprehensive investigation on milling Ti–6Al–4V alloy in cryogenic cooling, and it mainly focuses on the effect of diffusion wear behavior of WC-Co tool in operations. Diffusion coefficient calculation model of elements is established considering cutting temperature. A series of conventional and cryogenic cooling experiments are conducted, as well as element diffusion behaviors are observed and analyzed by SEM and EDS, and the diffusion coefficient of model is verified. Similarly, the influence of cutting temperature on diffusion wear on contact surface of tool/workpiece is studied. Through the phase diagram analysis of elements, the affinity behaviors between them are researched, and then the mechanism of diffusion wear is deduced. The results showed that the calculation results of diffusion coefficient are similar with the measurement ones under two kinds of cooling model at 150 m/min speed, and they are close to diffusion effect of 1200 and 800 K, respectively. Moreover, Co element has the most difficult diffusion ability, but C and Ti are easiest. At cryogenic conditions, their diffusion degrees are all apparent decline compared with conventional one, and the cutting temperature rise is slow with the increase of cutting speed. Although the former cutting force increases, the workpiece rebound is well suppressed. Furthermore, the friction degree of tool/workpiece is decreased on contact surface, and the elements diffusion behavior of carbide tools is improved. In cryogenic cooling condition, decreased friction degree of tool/workpiece and the weakening of solid solution degree between Ti, W, and Co elements are the main reasons for effectively inhibit of the diffusion wear.
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Diffusion thermodynamic behavior of milling Ti-6A1-4V alloy in liquid nitrogen cryogenic cooling
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10.1007/s00170-017-1427-2
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2018-03-01
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Creation of a delivery system based on noncontact positioning and transport of the cryogenic fuel targets represents one of the major tasks in a general program of inertial fusion energy (IFE) research. The purpose is to maintain the fuel layer quality during acceleration and injection of IFE targets at the focus of a powerful laser facility or IFE reactor. The program of the Lebedev Physical Institute (LPI) includes much development work on creation of different designs of the hybrid accelerators for IFE target transport with levitation. One of the main directions is an electromagnetic accelerator (EM-AC) + PMG system, where PMG is the permanent magnet guideway. The operational principle is based on quantum levitation of type-II high-temperature superconductors (HTSC) in the magnetic field. At the current stage, conceptual development of “EM-AC + PMG” hybrid accelerator is complete, and proof-of-principle experiments in mutually normal magnetic fields are made. This accelerator is a combination of the acceleration system (field coils generating the traveling magnetic waves) and the levitation system (PMG including a magnetic rail or magnetic track). The results obtained show that the HTSCs can be successfully used to maintain friction-free motion of HTSC sabots over the PMG, and also provide the required stability of the levitation height over the whole acceleration length due to the pinning effect. Additionally, using the driving body from MgB_2 superconducting coils as a sabot component (critical current 5,000 A at magnetic induction 0.25 T) allows one to reach injection velocities of 200 m/s under 400 g at 5 m acceleration length.
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Magnetic Acceleration of the Levitating Sabot Made of Type-II Superconductors
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10.1007/s10946-018-9700-x
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2018-03-01
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This paper compares some of the key machinability aspects acquired during milling of Ti6Al4V titanium alloy with uncoated and coated cryogenically treated end mills. Tool wear, coefficient of friction, cutting force, and chip morphology were the major criteria considered. Ti6Al4V is one of the titanium alloys that are widely used in aerospace and biomedical applications; however, it has a poor machinability and tribological properties. To evaluate the performance of cryogenically treated end mills, milling operations using a force dynamometer and dry sliding tests were conducted. The milling operations were conducted with a cutting speed of 90 m/min, a feed rate of 0.11 mm/tooth, a 1-mm axial depth of cut, and a 10-mm radial depth of cut under dry cutting conditions. The dry sliding tests were conducted using a tribometer with a ball-on-disk geometry under 10 N load and a speed of 5 cm/s. The milling test results showed that flank wear, chipping, and tool breakage were the wear mechanisms of the end mills. The cutting force measurements and the dry sliding tests showed that the cutting force and friction force values decreased when the cryogenic treatment time increased. As a result of the study, tools treated cryogenically for 36 h showed the best performance for the cutting force, friction force, and tool wear criteria. These improvements were characterized with hardness, fracture toughness, scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analyses.
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Effect of cryogenic treatment on the microstructure and the wear behavior of WC-Co end mills for machining of Ti6Al4V titanium alloy
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10.1007/s00170-017-1444-1
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2018-03-01
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One of the main challenges of the manufacturing industry is to optimise the cutting tool life in order to increase both the process productivity and the product surface quality in machining operations. Several innovative strategies were developed and tested as function of both the workpiece material and the peculiar machining operation, being the most interesting in case of difficult-to-cut alloys, the use of low-temperature cutting fluids that would be able to inhibit the thermally activated wear mechanisms responsible of the cutting edge geometrical alterations. In this context, the aim of the paper is to investigate the effect of cryogenic cooling technologies based on the use of liquid nitrogen (LN2) and gaseous nitrogen (N2) cooled at − 100 °C on the tool wear when using uncoated and coated cemented carbide inserts in semi-finishing turning of the Ti6Al4V titanium alloy. Four commercially available insert grades commonly used in machining difficult-to-cut alloys were tested using the cutting parameters recommended by the tool manufacturer. The investigation combined scanning electron microscopy and optical profiler analyses to efficiently define and quantify the main tool wear mechanisms. The study proved that the innovative technology based on cooled N2, regardless of the adopted insert grade, determined the best results in terms of tool life improvement since it simultaneously inhibited the cratering phenomenon onto the tool rake face and produced the lowest flank wear with respect to both the dry cutting, wet strategy, and LN2 cooling cases. It was also proved that the best results were obtained for the uncoated insert when using cooled N2.
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Wear mechanisms of uncoated and coated carbide tools when machining Ti6Al4V using LN2 and cooled N2
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10.1007/s00170-017-1289-7
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2018-03-01
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Improvement of energy efficiency in comminution of rocks using various pretreatment methods is being explored worldwide. This paper presents experimental data on breakage characteristics of granite and sandstone using cryogenic pre-treatment. The samples were treated with varying duration of immersion in liquid nitrogen. Combined pretreatment using oven heating followed by quenching in liquid nitrogen were also explored. The results indicate that using cryogenic pretreatment uniaxial tensile strength of granite can be decreased by more than 40% while in uniaxial compressive strength about 28% reduction is possible. For sandstone as much as 33% reduction in uniaxial compressive strength was observed.
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Effect of Cryogenic Pre-Treatment on Breakage Characteristics of Rocks
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10.1134/S1062739118023557
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2018-03-01
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Adiabatic shear localization plays an important role in the deformation and failure of ultrafine grained 6061 aluminum alloy processed by friction stir processing. To understand the effects of temperature and strain on adiabatic shear localization in the ultrafine grained 6061 aluminum alloy, it has been investigated dynamic mechanical behavior of ultrafine grained 6061 aluminum alloy under the controlled shock loading experiments. Deformation characteristics and microstructures in the shear band were performed by optical microscopy and transmission electron microscopy. The shear band in the ultrafine grained aluminum alloy is a long and straight band distinguished from the matrix. The width of the shear band decreases with increasing nominal strain. The results show that the grains in the boundary of the shear band are highly elongated along the shear direction and form the elongated cell structures (0.2 μ in width), and the core of the shear band consists of a number of recrystallized equiaxed grains 0.2-0.3 μ in diameters and the second phases distribute in both the boundary and the inner of the equiaxed new grains. The calculated temperature in the shear band is about 692 K. Rotational dynamic recrystallization mechanism is responsible for the formation of the microstructure in the shear band.
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Adiabatic Shear Localization and Microstructure in Ultrafine Grained Aluminum Alloy at Cryogenic Temperature
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10.1007/s11665-018-3157-5
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2018-02-01
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In order to make clear the effect of heat-force on tool wear for milling Ti-6Al-4V alloy in cryogenic cooling. The thermal-mechanical calculation models were established. Compared with conventional cutting, the thermal-mechanical effect rules and thermal action characteristics were analyzed in cryogenic cooling. As well as the cryogenic cooling milling method was executed for a series of processing experiments. The influence of heat-force on chip morphology and surface quality are researched. Meanwhile, the regular tool wear and mechanism were discussed. The results show that the measurement data and change tendency of milling forces are similar to the calculated data; the model is basically effective. Besides, when the cutting micro-unit is kept away from the tool nose, the tool-workpiece contact temperature and cutting force are all slow change compared with conventional cutting in cryogenic. Because of the tool-workpiece interaction squeezing action, the plastic-brittle deformation is obtained under the effect of liquid nitrogen cold quenching. Furthermore, the built-up edge in tool nose is not formed in cryogenic with unobvious thermal softening effect, so the friction effect of hard material is reduced. As a result, it improves obviously the workpiece machining quality and tool life, even as the stable wear range of tool has been transformed from 0.075–0.2 to 0.05–0.26 mm. Therefore, the thermal- mechanical effect influences tool wear, and controlling heat-force is evident, effective for improving tool life through cryogenic cooling.
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Tool wear behavior of thermal-mechanical effect for milling Ti-6Al-4V alloy in cryogenic
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10.1007/s00170-017-1012-8
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2018-02-01
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In this study, the grinding experiments were conducted on SiC particle-reinforced aluminum matrix (SiCp/Al) composites under wet, dry, cryogenic, and ELID grinding conditions, and the effects of grinding depth and table speed on grinding forces and grinding force ratio were investigated. The experimental results showed that both the normal and tangential grinding forces of SiCp/Al composites increased evidently with the increasing of the grinding depth and table speed under the four grinding conditions. And the grinding forces under the cryogenic condition were the largest, the grinding forces under the dry condition were the second, and the grinding forces under the wet condition were the minimum. Additionally, the grinding force ratio values decreased with the increase of grinding depth under the wet and dry conditions, while the grinding force ratio values increased slightly with the increase of the grinding depth under the cryogenic and ELID grinding conditions. The grinding force ratio was minimum under ELID grinding condition.
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A study of grinding forces of SiCp/Al composites
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10.1007/s00170-017-1115-2
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2018-02-01
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The surface tensions of 42 binary cryogenic mixtures at low temperature are correlated using the Shereshefsky model and excellent results are obtained. The average percent deviation is about ∼ 1.08%. The Gibbs energy change in the surface region is calculated and is used to obtain the excess number of molecular layers in the surface region. Furthermore, the model is used to derive an equation for the standard Gibbs energy of adsorption. The experimental standard Gibbs energy of adsorption is obtained from surface tension data and compared with calculated data. The agreement between experimental and calculated data is found to be very good. The magnitude of the Gibbs energy change in the surface region and the standard Gibbs energy of adsorption are discussed in terms of nature and type of intermolecular interactions in binary mixtures.
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The Prediction of Surface Tension and Thermodynamic Analysis of the Surface in Mixtures of Cryogenic Liquids
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10.1007/s10953-018-0718-z
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2018-02-01
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We report a custom-geometry linear ion trap designed for fluorescence spectroscopy of gas-phase ions at ambient to cryogenic temperatures. Laser-induced fluorescence from trapped ions is collected from between the trapping rods, orthogonal to the excitation laser that runs along the axis of the linear ion trap. To increase optical access to the ion cloud, the diameter of the round trapping rods is 80% of the inscribed diameter, rather than the roughly 110% used to approximate purely quadrupolar electric fields. To encompass as much of the ion cloud as possible, the first collection optic has a 25.4 mm diameter and a numerical aperture of 0.6. The choice of geometry and collection optics yields 10^7 detected photons/s from trapped rhodamine 6G ions. The trap is coupled to a closed-cycle helium refrigerator, which in combination with two 50 Ohm heaters enables temperature control to below 25 K on the rod electrodes. The purpose of the instrument is to broaden the applicability of fluorescence spectroscopy of gas-phase ions to cases where photon emission is a minority relaxation pathway. Such studies are important to understand how the microenvironment of a chromophore influences excited state charge transfer processes. Graphical Abstract ᅟ
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A Linear Ion Trap with an Expanded Inscribed Diameter to Improve Optical Access for Fluorescence Spectroscopy
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10.1007/s13361-017-1763-3
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2018-01-30
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This paper presents the results of the tests and analysis on the coefficient of thermal expansion for the steel strand under combined low temperatures and prestressing forces. A test program was firstly carried out to study the thermal expansion behaviour of the seven-wire strand under combined different low temperatures ranging from 20 to − 165 °C and different prestressing levels ranging from 0 to 0.75 f _t/ f _tk. The test results exhibited the thermal expansion behaviours of the steel strand under low temperatures in terms of thermal strain versus temperature curves, transit linear thermal expansion coefficient, and average thermal expansion coefficient. The influences of the low temperature and prestressing levels on the thermal expansion behaviours of the steel strand were separately discussed and analysed. Based on the test data, mathematical models were developed to predict the thermal expansion coefficients including transit and average of the steel strand. The developed regression models fully considered the influences of the low temperature and prestressing stresses acted on the strand. Finally, design equations were proposed to predict the transit and average thermal expansion coefficient of the steel strand under combined low temperature and prestressing forces.
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Tests and Analysis on Thermal Expansion Behaviour of Steel Strand used in Prestressed Concrete Structure under Low Temperatures
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10.1186/s40069-018-0236-9
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2018-01-11
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Methods able to enhance surface integrity of machined components have been one of the emerging areas in manufacturing engineering, and a technique that has been providing satisfying results in the last years is cryogenic machining. Besides promoting surface integrity improvement, it is considered an alternative to the use of conventional cutting fluids, which is in accordance with the latest global trends for sustainable means of production. In this sense, replacing grinding operation, which uses large volumes of conventional cutting fluids, by hard turning assisted by liquid nitrogen, for example, could be a good choice. The aim of this work was to investigate the effects of cryogenic cooling on the surface integrity of quenched and tempered AISI D6 tool steel after turning operation. Dry and cryogenic turning trials with polycrystalline cubic boron nitride tools were performed and the results of surface integrity (surface roughness and topography, microhardness and residual stresses, as well as the modified microstructure of the deformed layer) were analyzed for comparison. The results showed that cryogenic cooling played an important role in modifying the workpiece surface integrity, providing low values of surface roughness (similar to those obtained in grinding operations), as well as higher values of surface microhardness and compressive residual stresses as compared to the dry condition.
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Effects of cryogenic cooling on the surface integrity in hard turning of AISI D6 steel
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10.1007/s40430-017-0922-6
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2018-01-03
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Inconel 718 is a popular, but difficult to machine, nickel-based supper alloy. Machining performance of this material can be improved by appropriate modelling and optimization. In the present study, response surface modelling and optimization for turning of Inconel 718 under four machining conditions: dry with untreated inserts, dry with cryogenically treated inserts, minimum quantity lubrication with untreated inserts and minimum quantity lubrication with cryogenically treated inserts is carried out. With the aim of improving the machinability of Inconel 718, an attempt has been made to examine the effect of cryogenic treatment of tool and minimum quantity lubrication in terms of indicators such as surface quality of workpiece, tool wear and material removal rate. Cutting speed, feed rate and depth of cut are used as the control parameters. Whereas, cutting force, tool vibration, cutting temperature, surface roughness and tool wear are the measured responses. Prediction models are developed for each response. Later, all the responses are optimized together by desirability approach and are validated using confirmation experiments. A spider plot is drawn to display the relationships among control and response parameters. The plot shows that application of minimum quantity lubrication with cryogenically treated inserts resulted in least cutting force, tool vibration, cutting temperature, minimum surface roughness of workpiece along with least tool wear and best material removal rate compared to other three conditions used. This clearly shows machinability improvement of Inconel 718.
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Experimental results on the performance of cryogenic treatment of tool and minimum quantity lubrication for machinability improvement in the turning of Inconel 718
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10.1007/s40430-017-0920-8
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2018-01-01
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Conventional radio frequency matching techniques using silicon-based phase shifters operate well at ambient temperatures, but will perform poorly in cryogenic environments due to carrier freeze-out. However, varactors made from gallium arsenide retain carrier mobility at such temperatures. This paper describes the modification and evaluation of a commercial phase shifter operating in the UHF frequency range for cryogenic applications.
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Modification of a Commercial Phase Shifter for Cryogenic Applications
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10.1007/978-3-319-92726-8_4
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2018-01-01
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We present the status of the development of Superconducting Tunnel Junction (STJ) detector with the cryogenic preamplifier as far-infrared single photon detector for the COsmic BAckground Neutrino Decay search (COBAND) experiment. The photon energy spectrum from the radiative decay of the cosmic background neutrino is expected to have a sharp cutoff at high energy end in a far-infrared region ranging from 15 meV to 30 meV. The detector is required to measure an individual photon energy with a sufficient energy resolution less than 2% for identifying the cutoff structure, and to be designed for a rocket or satellite experiment. We develop an array of Nb/Al-STJ pixels which can detect a single far-infrared photon delivered by a diffractive grating according to its wavelength. To achieve high signal-to-noise ratio of the STJ, we use a preamplifier made with the Silicon-on-Insulator (SOI) technique that can be operated around 0.3K. We have developed the Nb/Al-STJ with the SOI cryogenic preamplifier and have tested the detector performance around 0.3K.
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Development of Superconducting Tunnel Junction Photon Detectors with Cryogenic Preamplifier for COBAND Experiment
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10.1007/978-981-13-1316-5_45
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2018-01-01
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To achieve the high accuracy during machining of difficult-to-machine materials, nonconventional machining has become the lifeline of the industry. Electro discharge machining (EDM) is one of the most extensively used machining method among all the nonconventional machining processes. Cryogenic treatment is introduced in this process for improving the tool life as well as reducing the machining cost. In this investigation, effect of deep cryogenically treated post tempered electrodes during EDM operation of AISI 304 stainless steel has been studied. The process performance has been assessed by means of radial overcut (ROC) when pulse on time, duty cycle, peak current, gap voltage and flushing pressure are considered as process parameters. Machining is performed using three tungsten carbide electrodes (untreated, cryogenically treated single and double tempered electrodes). Microstructural analysis has been carried out for the machined surfaces. From this study it is observed that, deep cryotreated post tempered electrodes considerably decrease the radial overcut.
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Effect of Process Parameters and Cryotreated Post Tempered Electrodes on the Radial Overcut of AISI 304 During EDM: A Comparative Study
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10.1007/978-3-319-76276-0_3
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2018-01-01
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We report on a new study for the performance of the Silicon Photo-Multipliers (SiPMs) light sensors when they are exposed to high electric field strengths in cryogenic environment. Three different SiPMs from two vendors (FBK and Hamamatsu) have been tested. The SiPMs showed very good stability, with respect to the gain and the crosstalk probability, when they are exposed to high electric fields compared to the case with the absence of the electric field.
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New Study for SiPMs Performance in High Electric Field Environment
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10.1007/978-981-13-1316-5_56
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2018-01-01
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Reactive Al–Ni composites are of interest for combustion synthesis, for joining, and as components of energetic formulations. Mechanical milling is one of the most practical techniques used for their preparation. This study investigated the effect of ball milling at cryogenic temperatures on the reactivity and structure of Al–Ni composites. Stoichiometric mixtures of Al and Ni powders were milled both at room temperature and cooled by liquid nitrogen. Products were characterized using scanning electron microscopy, differential scanning calorimetry, and x-ray diffraction. Aluminum and nickel were mixed on a finer scale in cryogenically milled powders compared to those prepared at room temperature. DSC traces of the cryogenically milled powder showed three exothermic peaks, while only two clearly resolved peaks were observed for the powders milled at room temperature. A low-temperature reaction preceding the first peak was detected only for the cryomilled material. Apparent activation energies, obtained by model-free analysis, were consistent with previous work on nanofoils. Ignition temperatures of powders prepared at room temperature decreased with increasing structural refinement. This effect was even stronger for the cryogenically milled powder. Energetic characteristics of the prepared materials were correlated with their respective structural refinement. These correlations suggest that the cryomilled material has a narrower zone separating Al and Ni in which the elements are mixed together compared to the similar material prepared by room temperature milling.
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Effect of milling temperature on structure and reactivity of Al–Ni composites
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10.1007/s10853-017-1591-7
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2018-01-01
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Normal metal–insulator–superconductor (NIS) tunnel junctions, as well as SIS junctions, are the main building blocks for superconducting electronics. Single NIS junctions NIS junction and arrays are used in microwave bolometers, cryogenic thermometers, electron coolers Electron coolers , radiation detector. In such devices, junctions should fit different parameters for area, transparency, material properties and thermal characteristics. This leads to various fabrication methods and technique for measurements. Estimations made for equilibrium measurement conditions can be controversial in the case of microwave bolometers, ultra-low temperature thermometers, electron coolers. In terahertz bolometers, as well as in electron coolers, the energy distribution of electrons becomes different from Fermi distribution. In bolometers illuminated with terahertz radiation, the density of electrons will increase at higher energies, and in electron coolers, the distribution will be with reduced density at higher energies. Andreev reflection and proximity effect at the superconductor-normal metal interface induce changes in IV curve compared to simple SIN model. In this review, we present two levels of description for practical applications; first approximation is conventional with single-electron tunneling and equilibrium electron energy distribution, and the second taking into account non-Fermi distribution, Andreev currents Andreev current , high-energy phonon creation and phonon escape.
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Nanodevices with Normal Metal—Insulator—Superconductor Tunnel Junctions
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10.1007/978-3-319-90481-8_5
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2018-01-01
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In recent years, size and capacity of wind turbines have increased significantly to meet the ambitious worldwide renewable energy targets. Extraordinarily high costs of manufacture and maintenance are one of the main issues to confine the expansion of the share of wind turbines in various renewables. To mitigate the high costs, advanced, and cost-effective repairing of wind turbine blades is critically needed to enable on-site repairing and restoration of damaged wind turbine blades. Moreover, advanced manufacturing technologies of hardened bearing steels are required to improve the functional performance of bearing and gearbox metal components. In this chapter, both conventional techniques and state-of-the-art repairing techniques for wind turbine blades (composites) are introduced firstly. Then, current machining process of hardened steels for bearing and gearbox components is summarized. Current achievements in novel machining process of hardened steel components are discussed for laser-assisted machining and cryogenic machining. The relationship between the desired surface integrity and manufacturing process conditions is explained through experimental results in literature. An overview is provided on the future applications of these advanced repairing technologies for wind turbine blades and advanced manufacturing technologies for wind turbine bearing and gearbox components.
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Advanced Repairing of Composite Wind Turbine Blades and Advanced Manufacturing of Metal Gearbox Components
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10.1007/978-3-319-78166-2_8
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2018-01-01
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The fatigue is a primary mode of failure in many hot work die steels such as AISI H13 on account of severe thermal fatigue conditions as in hot forging. The present work involves hardening of AISI H13 die steel specimens at 1020 °C, oil quenching followed by double tempering at 500 °C and then cryogenic treatment at minus 185 °C at different cryosoaking periods from 8 to 32 h followed by soft tempering at 100 °C. The influence of tertiary carbide evolution on wear behavior, surface roughness and fatigue limit was studied. It has been established that there are reduction in wear rate, improvement in hardness, surface roughness and increasing the fatigue life on account of fine tertiary carbide precipitation.
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Evolution of Tertiary Carbides and Its Influence on Wear Behavior, Surface Roughness and Fatigue Limit of Die Steels
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10.1007/978-981-10-6002-1_19
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2018-01-01
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By consolidating the principles of both first and second laws of thermodynamics, exergy-based analyses have demonstrated their potential for evaluating the efficiency, productivity, and sustainability of various biofuel production systems including biogas. Exergy-based approaches have been extensively applied in biofuel industry for finding the most thermodynamically, economically, and environmentally sound production, upgrading, refining, and utilization systems. In this chapter, after briefly explaining the concept of exergy, a case study on the application of advanced exergy and exergoeconomic analyses for evaluating two biogas upgrading processes, i.e., high pressure water scrubbing (HPWS) and cryogenic separation (CS) was presented and discussed. According to the results obtained, endogenous exergy destruction and investments costs of most of the elements of both biogas upgrading processes were higher than their corresponding exogenous counterparts, showing a weak economic correlation among those elements. Exergy destruction and investment costs associated with compressors and pumps were avoidable and unavoidable, respectively. While, exergy destruction and investment costs related to heat exchangers and air coolers were found to be unavoidable and avoidable, respectively. Finally, three different strategies were suggested for discounting costs and improving the process performance.
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Exergy-Based Performance Assessment of Biogas Plants: Application of Advanced Exergy and Exergoeconomic Analyses for Evaluating Biogas Upgrading Process
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10.1007/978-3-319-77335-3_14
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2018-01-01
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Electricity demand varies, influenced by factors like time of the day and season. The National Grid is prepared for surges in demand, with power stations on standby ready to crank up the power. However, dealing with these peaks and troughs will become increasingly difficult as coal-fired power stations closed down and more intermittent renewable energy like wind and solar comes online. In 2015, renewables provided almost a quarter of UK electricity. The intermittent nature of green sources has seen researchers focus on trying to improve energy storage. The cryogenic energy facility stores power from renewables or off-peak generation by chilling air into liquid form. When the liquid air warms up, it expands and can drive a turbine to make electricity. The 5 MW plant near Manchester can power up to 5000 homes for around 3 h. Cryogenic storage works by using renewable or off-peak electricity to cool air down to −190 °C, which turns it into a liquid. Intermittent supply is an ongoing problem for the development of the renewable power market. Could cryogenic energy storage prove the best way to reduce waste by saving off-peak power for later use? Birmingham University’s Professor Richard Williams argues the case.
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Reliable Renewables with Cryogenic Energy Storage
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10.1007/978-3-319-70721-1_3
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2018-01-01
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Materials issues related to the construction of future fusion reactors are described. The sources of stress in a fusion reactor structure are outlined. Stresses due to thermal expansion are calculated from the first wall heat load. Stresses due to coolant pressure are calculated from the MHD pressure drop in conducting coolants in a magnetic field (Hartmann flow). Stresses due to transient plasma behaviors, including disruptions and vertical displacement events (VDEs), are described. The nature of repetitive stress on fatigue failure is shown. The concept of fracture toughness, starting from the Griffith theory of crack growth, is also shown. Next, the effects of radiation damage are explored from the Kinchin-Pease displacement cascade model, including calculations of electronic stopping and energy- and angle-dependent cross sections to arrive at a displacements per atom (DPA) cross section. Helium production and its effects are also described. The impacts of radiation damage (and their temperature dependence) are shown for embrittlement, void swelling, and creep. The development of advanced materials for fusion reactor structural materials, including SiC-SiC composites and ODS and RAFM steels, are described. The properties of structural materials and coolant from the standpoint of tritium leakage from blanket systems are addressed using Sievert’s law, and the Sievert coefficients for various structural materials and coolants are given. Superconducting magnet materials are discussed from the BCS theory perspective for Type II superconductors, and the engineering for cryogenic stability is described, along with stresses in magnets and electrical fault protection. The newer REBCO superconductors are also introduced. Finally, topics in vacuum technology including conductance calculations, throughput, and the design of tritium-compatible mechanical roughing pumps and cryosorption pumps are given, and features of the ITER vacuum system are described. Blanket neutronics are described, and two designs for a fusion reactor blanket (non-breeding and breeding) are given.
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Fusion Technology
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10.1007/978-3-319-98171-0_11
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2018-01-01
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The structure and functional activity of microbial complexes of a forest oligo-mesotrophic subshrub- grass-moss bog (OMB, Central Evenkiya) and a subshrub-sedge bog in the polygonal tundra (PB, Lena River Delta Samoylovsky Island) was studied. Soil of the forest bog (OMB) differed from that of the polygonal tundra bog (PB) in higher productivity (C_org, N_total, P, and K reserves), higher biomass of aerobic chemoorganotrophs (2.0 to 2.6 times), and twice the level of available organic matter. The contribution of microorganisms to the carbon pool was different, with the share of C_mic in C_org 1.4 to 2.5 times higher in PB compared to OMB. Qualitative composition of the methane cycle microorganisms in PB and OMB soils differed significantly. Methanogenic archaea ( Euryarchaeota ) in the shrub-sedge PB of tundra were more numerous and diverse than in the oligo-mesotrophic bog (OMB) and belonged to six families ( Methanomassiliicoccaceae , Methanoregulaceae , Methanobacteriaceae , Methanomicrobiaceaee , Methanosarcinaceae , and Methanotrichaceae ), while members of only four families ( Methanosarcinacea , Methanobacteriaceae , Methanotrichaceae , and Methanomassiliicoccaceae ) were revealed in OMB. In both bogs, methane-oxidizing bacteria belonged to Alphaproteobacteria (II) and Gammaproteobacteria (I). Methanotroph diversity was higher in OMB than in PB. Microbial communities of PB soils had higher potential activity of methanogenesis and methanotrophy compared to those of OMB. Methanogenic and methanotrophic activities in PB were 20 and 2.3 times higher, respectively, than in OMB.
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Structure of microbial communities of peat soils in two bogs in Siberian tundra and forest zones
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10.1134/S0026261718010083
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2018-01-01
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Shubnikov modelled his laboratory after the Leiden example, which implied among other things that he attached great importance to the workshop. In it he employed a large number of qualified craftsmen whom he acquired from the most unlikely places, such as Ivan Pavlovich Korolev who had earlier worked as a ship mechanic and turned out to be a very good head of the workshop. Shubnikov and the other physicists in his group were never seen at a workbench (contrary to Kapitsa for instance) and did not make their own apparatus as many physicists still did at the time.
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Shubnikov’s Scientific Work at UFTI
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10.1007/978-3-319-72098-2_8
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2018-01-01
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The present review is devoted to some problems of the production of liquid para -hydrogen by catalytic ortho - para conversion (OPC) of molecular hydrogen at cryogenic temperatures, the catalysts of this process, and catalyst operation in hydrogen liquefiers. The methods of evaluating the catalyst activity in OPC and calculations of the performance of hydrogen liquefiers are given. The most important papers that deal with the use of catalysts of OPC under the conditions of hydrogen liquefiers were considered. A procedure for processing the experimental data on catalyst activity was presented for calculations of the laboratory and industrial hydrogen liquefiers working at different temperature levels based on these data.
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Low-Temperature Conversion of ortho-Hydrogen into Liquid para-Hydrogen: Process and Catalysts. Review
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10.1134/S2070050418010117
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2018-01-01
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Hard turning is the process of turning workpieces having a hardness greater than 45 HRC. It can be treated as pre-grinding operation as it gives surface finish about 0.0003 mm. Hard turning became more interesting after the invention of new hard materials such as CBN, ceramic, cermet, etc. which are cheaper than diamond. Coatings of these hard materials using methods such as PVD (physical vapor deposition), CVD (chemical vapor deposition), etc. increase the wear resistance of tool. Also, cryogenically treated inserts increase the tool life. This literature study covers in depth some research papers on the thermal study of hard materials. In hard turning, heat generated in the cutting zone is very high, which leads to high temperature. High temperature can affect many properties of the workpiece, as well as a tool such as fatigue life of workpiece, may be decreased. So it is important to control the temperature in cutting zone. Also, tool geometry plays a major role in hard turning as different nose radius can generate different cutting temperature as well as wear rate. The issue in the thermal study of tool materials is the measurement of temperature in the different zones. Many researchers have used different temperature measurement methods to determine the temperature generated. This rich literature covers all the aspects of thermal hard materials.
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Literature Review of Hard Turning and It’s Thermal Aspects
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10.1007/978-3-319-76276-0_24
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2018-01-01
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In this paper a definition and classification of hybrid processes is given with the focus on assisted hybrid machining processes developed at the Faculty of Mechanical Engineering in Ljubljana. These processes include high-pressure jet assisted machining, cryogenic machining, laser assisted machining and ultrasonic assisted machining. The principles of each individual process are described, followed by the presentations of the results of machinability and productivity improvements. The results were obtained during the last eight years of research on machinability of different hard-to-machine materials at the Department for Management of Manufacturing Technologies.
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Hybrid Machining Processes
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10.1007/978-3-319-89563-5_1
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2018-01-01
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During the last few decades, the Arctic has experienced large-scale vegetation changes. Understanding the mechanisms behind this vegetation change is crucial for our ability to predict future changes. This study tested the hypothesis that decreased cryogenic disturbances cause vegetation change in patterned ground study fields (non-sorted circles) in Abisko, Sweden during the last few decades. The hypothesis was tested by surveying the composition of plant communities across a gradient in cryogenic disturbance and by reinvestigating plant communities previously surveyed in the 1980s to scrutinise how these communities changed in response to reduced cryogenic disturbance. Whereas the historical changes in species occurrence associated with decreased cryogenic disturbances were relatively consistent with the changes along the contemporary gradient of cryogenic disturbances, the species abundance revealed important transient changes highly dependent on the initial plant community composition. Our results suggest that altered cryogenic disturbances cause temporal changes in vegetation dynamics, but the net effects on vegetation communities depend on the composition of initial plant species.
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Decreased cryogenic disturbance: one of the potential mechanisms behind the vegetation change in the Arctic
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10.1007/s00300-017-2173-5
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2018-01-01
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Stable isotopologues of water (mainly ^1H_2 ^16O, HD^16O and ^1H_2 ^18O) have been used for decades as tracers of the Earth’s water cycle. In this chapter, we briefly describe the theoretical background and state-of-the-art techniques of the use of water stable isotopes to investigate the sources of plant water. We aim to provide the basic understanding of stable isotope fractionation within the Earth’s critical zone that is relevant for studies of plant water sources. We then present a practical guide of their most common applications in field studies and the most common and up-to-date laboratory procedures. We finally introduce the existing statistical approaches for estimating the relative contributions of water sources to plant transpiration. By acknowledging the advantages and limitations of each approach, we aim to provide an overview of the current techniques to researchers in the fields of plant ecophysiology, ecohydrology and forest ecology, so that they can make informed decisions when designing their experiments.
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Stable-Isotope Techniques to Investigate Sources of Plant Water
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10.1007/978-3-319-93233-0_26
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2018-01-01
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Being short of conventional chromophores, polyacrylamide is generally not regarded as a fluorescent material. Exactly the polymerization of dilute solutions of acrylamide and N,N′-methylenebisacrylamide led to thick liquids at 60 °C, showing no fluorescence. Things changed when the phase transition of water was involved. The squeezing effect of ice crystals not only created polymeric solids (cryogels) at − 20 °C, but also endowed them unexpected fluorescence emissions. The macroporous cryogels are mainly blue fluorescent polymers. However yellow and red fluorescence were also achieved by changing the ingredient ratios. A series of instrumental detections revealed that the multicolor fluorescence were based on exquisite amido stacking induced from ice squeezing. If people make good use of the squeezing effect of the heaven-sent molecule to manipulate the interactions of monomer functionalities, cryogenic polymerization can be a promising method to produce diverse polymeric materials.
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Ice Squeezing Induced Multicolor Fluorescence Emissions from Polyacrylamide Cryogels
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10.1007/s10895-017-2196-x
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2017-12-01
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A central element of a power plant based on inertial confinement fusion (ICF) is a target with cryogenic hydrogen fuel that should be delivered to the center of a reactor chamber with a high accuracy and repetition rate. Therefore, a cryogenic target factory (CTF) is an integral part of any ICF reactor. A promising way to solve this problem consists in the FST layering method developed at the Lebedev Physical Institute (LPI). This method (rapid fuel layering inside moving free-standing targets) is unique, having no analogs in the world. The further development of FST-layering technologies is implemented in the scope of the LPI program for the creation of a modular CTF and commercialization of the obtained results. In this report, we discuss our concept of CTF (CTF-LPI) that exhibits the following distinctive features: using a FST-layering technology for the elaboration of an in-line production of cryogenic targets, using an effect of quantum levitation of high-temperature superconductors (HTSCs) in magnetic field for noncontacting manipulation, transport, and positioning of the free-standing cryogenic targets, as well as in using a Fourier holography technique for an on-line characterization and tracking of the targets flying into the reactor chamber. The results of original experimental and theoretical investigations performed at LPI indicate that the existing and developing target fabrication capabilities and technologies can be applied to ICF target production. The unique scientific, engineering, and technological base developed in Russia at LPI allows one to make a CTFLPI prototype for mass production of targets and delivery thereof at the required velocity into the ICF reactor chamber.
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Cryogenic Hydrogen Fuel for Controlled Inertial Confinement Fusion (Cryogenic Target Factory Concept Based on FST-Layering Method)
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10.1134/S1063778817070018
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2017-12-01
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The present work is aimed at in-process estimation of surface roughness using cutting parameters along with cutting force, sound, and vibration in turning of Inconel 718 with cryogenically treated and untreated carbide inserts. Initially, prediction models are developed by regression analysis using only cutting parameters and then using only force, sound, and vibration. Later on, these models are modified to include all the parameters after performing correlation analysis for determining significant parameters. The modified models are developed using only significant parameters from the cutting parameters and measured responses. The prediction results of modified regression models are compared with experimental results and fine association of fit between measured and estimated surface roughness is confirmed. Based on coefficient of determination ( R ^2) values, the regression models are found to be better for estimating surface roughness. Finally, it is found that modified regression models are estimating surface roughness with more than 90% accuracy which can be said as acceptable for the two types of inserts used. Use of sound emitted while machining along with values of cutting parameters, force, and vibration to predict surface roughness has not been reported earlier particularly for Inconel 718. As cutting force, sound, and vibration can be measured during the turning process, this method can be useful for real-time control of the process to get the desired surface roughness for machining of difficult to cut material like Inconel 718.
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Estimation of surface roughness using cutting parameters, force, sound, and vibration in turning of Inconel 718
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10.1007/s40430-017-0819-4
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2017-12-01
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The investigation was aimed at evaluation of level and rate of cutaneous and tympanic temperature drop due to a single short-timed (3 min) cooling in a cryosauna (–70°С), and adaptation-indicative physiological parameters, including blood catecholamines, ACTH, lipoproteins and free fatty acids. The subjects were seven healthy men. Exposure to cold invariably reduced the internal (tympanic) and cutaneous temperature by 1°С and 7°С on average, respectively. Tympanic temperature remained 0.4°С low on the average for more than 20 min after exposure. Cutaneous temperature was 1°С below the norm for an hour after cooling. For one hour after the short-term cold exposure, blood norepinephrine remained increased, and so did the blood concentrations of high-density lipoprotein cholesterol and free fatty acids. These results demonstrate brief adaptive changes following a single exposure at–70°C.
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Effect of Short-term Cooling at –70°C in an Air Cryogenic Sauna on Body Temperature and Lipid Profile of Healthy People
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10.1134/S0362119717070180
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2017-12-01
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Successfully recovering stored cryopreserved cells requires attention to two major factors, i.e., storage temperature and proper handling of the frozen samples. These key considerations are in turn impacted by how the inventory system is constructed, the frequency and process for retrieving specimens, as well as how the material is secured. In addition, shipping biological materials requires attention to the type of material transported, adherence to regulatory requirements, packaging materials and proper assembly, labeling, and engaging reputable carriers. This paper provides an overview discussion of the current best practices for storing, handling, and shipping of cryopreserved cells and provides references to more detailed information on specific topics.
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Best practices for storing and shipping cryopreserved cells
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10.1007/s11626-017-0214-6
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2017-12-01
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Effects of temperature on fracture characteristics of type 304 stainless steel at cryogenic to elevated temperatures are investigated. Three point bending fracture tests according to ASTM E1820 guidelines are conducted on single edge notched bending specimens made of cold drawn flat bars in a temperature range of −195 °C to 500 °C. The test setup includes a thermal chamber, a temperature display and control unit capable of maintaining desired thermal conditions and a remote displacement recording device. Crack lengths are estimated by using load-load line displacement curves with proper calibration equations. The temperature dependency of tensile properties of the test material is also considered. Resistance curves ( J -Δ a ) are then determined for ten values of test temperature. Finally, fracture parameters of test specimens such as critical J values and tearing modulus are extracted. Results reveal that harsh thermal conditions have significant effects on ductile fracture performance of type 304 stainless steel.
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Fracture Performance of Type 304 Stainless Steel Reinforcement Belt from Cryogenic to Elevated Temperatures
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10.1007/s40799-017-0205-2
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2017-12-01
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We experimentally investigated the dissolution of forsterite, enstatite and magnesite in graphite-saturated COH fluids, synthesized using a rocking piston cylinder apparatus at pressures from 1.0 to 2.1 GPa and temperatures from 700 to 1200 °C. Synthetic forsterite, enstatite, and nearly pure natural magnesite were used as starting materials. Redox conditions were buffered by Ni–NiO–H_2O (ΔFMQ = − 0.21 to − 1.01), employing a double-capsule setting. Fluids, binary H_2O–CO_2 mixtures at the P, T , and f O_2 conditions investigated, were generated from graphite, oxalic acid anhydrous (H_2C_2O_4) and water. Their dissolved solute loads were analyzed through an improved version of the cryogenic technique, which takes into account the complexities associated with the presence of CO_2-bearing fluids. The experimental data show that forsterite + enstatite solubility in H_2O–CO_2 fluids is higher compared to pure water, both in terms of dissolved silica ( m SiO_2 = 1.24 mol/kg_H2O versus m SiO_2 = 0.22 mol/kg_H2O at P = 1 GPa, T = 800 °C) and magnesia ( m MgO = 1.08 mol/kg_H2O versus m MgO = 0.28 mol/kg_H2O) probably due to the formation of organic C–Mg–Si complexes. Our experimental results show that at low temperature conditions, a graphite-saturated H_2O–CO_2 fluid interacting with a simplified model mantle composition, characterized by low MgO/SiO_2 ratios, would lead to the formation of significant amounts of enstatite if solute concentrations are equal, while at higher temperatures these fluid, characterized by MgO/SiO_2 ratios comparable with that of olivine, would be less effective in metasomatizing the surrounding rocks. However, the molality of COH fluids increases with pressure and temperature, and quintuplicates with respect to the carbon-free aqueous fluids. Therefore, the amount of fluid required to metasomatize the mantle decreases in the presence of carbon at high P – T conditions. COH fluids are thus effective carriers of C, Mg and Si in the mantle wedge up to the shallowest level of the upper mantle.
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Experimental determination of magnesia and silica solubilities in graphite-saturated and redox-buffered high-pressure COH fluids in equilibrium with forsterite + enstatite and magnesite + enstatite
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10.1007/s00410-017-1427-0
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2017-12-01
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The optoacoustic gravitational-wave antenna (OGRAN) located in the underground laboratory of the Baksan Neutrino Observatory has a limited sensitivity sufficient only to detect gravitational radiation from astronomical objects at a distance of 100 kpc. In order to cover sources in the zone with a radius of up to 15 Mpc, it is proposed to economically upgrade the antenna and cool down the body of the acoustic detector to a temperature of liquid nitrogen of ~78 K [1]. In this case, the spectral density of the Brownian noise of the detector decreases owing to temperature and also owing to the subsequent increase in its acoustic Q factor by one and a half to two orders of magnitude. This paper presents the results of an experiment for testing these ideas on the cryo-OGRAN prototype while preserving the optical detection scheme used for the uncooled antenna.
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Cryogenic Model of the Gravitational Antenna OGRAN
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10.1134/S1063778817100039
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2017-11-01
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The objective of the present work is to characterize the wear behavior of a cryogenically treated low-carbon AISI 420 martensitic stainless steel, by means of ball-on-disk tribological tests. Wear tests were performed under a range of applied normal loads and in two different environments, namely a petrolatum bath and an argon atmosphere. Wear tracks were analyzed by both optical and scanning electron microscopy and Raman spectroscopy to evaluate wear volume, track geometry, surface features and the tribolayers generated after testing. This paper is an extension of the work originally reported in the VIII Iberian Conference of Tribology (Prieto and Tuckart, in: Ballest Jiménez, Rodríguez Espinosa, Serrano Saurín, Pardilla Arias, Olivares Bermúdez (eds) VIII Iberian conference of tribology, Cartagena, 2015 ). In this study, it has been experimentally demonstrated that cryogenically treated specimens showed a wear resistance improvement ranging from 35 to 90% compared to conventionally treated ones.
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Influence of Cryogenic Treatments on the Wear Behavior of AISI 420 Martensitic Stainless Steel
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10.1007/s11665-017-2986-y
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2017-11-01
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Ball bearings (e.g., deep-groove, angular-contact, and roller bearings) support loads in a rotor system and provide lubrication between the shaft and housing. The deep-groove ball bearings used in a turbopump do not differ significantly from angular-contact ball bearings or the bearings found in other applications. Deep-groove ball bearings consist of rolling elements, an inner raceway, an outer raceway, and a retainer to guide the rolling elements. In ball bearings, the resistive (churning or drag) forces and torques acting on the rolling elements and raceways are affected by the fluid flow rate and direction, as well as the rotational speed. These churning and drag forces and torques affect the internal dissipation or power losses into the bearing, which become very significant for high-speed applications. This study numerically investigated the characteristics of the flow conditions for deep-groove ball bearings, with a particular focus on the friction distribution on the rolling elements. A simple analytical model of the fluid flow inside a ball bearing was developed using a computational analysis, and the flow characteristics at high rotational speeds are presented.
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Fluid Flow Analysis for Friction Torque around Rolling Element in Ball Bearings
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10.3103/S106836661706006X
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2017-11-01
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目的 奥氏体不锈钢 (ASS) 在深冷压力容器中应用广泛。ASS较高的应变硬化特性有助于其产生应变强化。在应变强化过程中, 保载时间是影响材料最终变形量的关键参数。基于室温蠕变应变弛豫理论, 本文旨在提出一种S30408深冷压力容器应变强化过程中的保载时间预测方法。 创新点 1. 根据室温蠕变应变弛豫理论, 保载过程即为材料在室温蠕变中应变速率逐渐减缓、材料结构逐渐稳定的过程; 本文据此获得了保载时间的计算模型。2. 结合材料试验与容器试验, 将计算模型中涉及的多个微观变量转换为唯一宏观变量一圆柱壳上的最大环向应力, 可为常规工业生产提供定量的、具有实际可操作性的技术支持。 方法 1. 根据室温蠕变应变弛豫理论, 建立蠕变本构关系, 得出保载时间计算模型。2. 通过材料试验, 考虑实际生产中的特定条件, 将保载时间计算模型的多个微观变量简化为唯一宏观变量。3. 通过在多个工业规模的容器上进行实验, 比较验证所提计算方法的可靠性。 结论 1. 室温蠕变应变弛豫理论可以用于描述应变强化保载过程中的材料变化。2. 容器保载时长, 即材料应变弛豫时长, 与其所承受的最大应力有关。3. 所提出的保载时间计算方法可以为容器保载时间提供可靠预测; 其平均绝对误差为7.53%, 且绝大部分情况下偏于保守。 Austenitic stainless steel (ASS) has been widely used for cryogenic pressure vessels. Its high strain hardening characteristic allows cold-stretching. In the cold-stretching process, the load-holding time is a critical operating parameter which affects the final deformation of the material. In this paper, a load-holding time prediction method for the cold-stretching process of S30408 cryogenic pressure vessels is proposed, based on room-temperature creep strain relaxation. The proposed correlation has only one variable, the maximum circumferential stress applied to the cylindrical shell, which can be easily obtained by finite element analysis. Consequently, the strain rate measurement during the cold-stretching process is significantly simplified. The prediction method and the strain rate measurement were verified by experimental measurements conducted on two vessels manufactured via the cold-stretching process. The measured strain relaxation times accurately matched the calculated values and the load-holding time for the process was well predicted.
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A load-holding time prediction method based on creep strain relaxation for the cold-stretching process of S30408 cryogenic pressure vessels
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10.1631/jzus.A1600798
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2017-11-01
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Response of carbon mineralization to nitrogen application in cryogenic soils
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10.1134/S1067413617060066
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2017-11-01
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The dynamic behavior of the thermal-cryogenic regime of the hydrosystem of the Vilyui Hydroelectric Power Plant, which was the first to be constructed in a continuous space of permafrost rock, is presented. Features of the evolution of the thermal-moisture regime of the hydrosystem and the role of rockfill in thermal and mass transfer (crogenic) processes in the artificially created combined natural and engineered system are considered. It is established that, despite more than a 50-period of service, the thermal regime of the hydrosystem is in a fixed state and far from the steady state. Thawing of the shoreline abutments of the dam and in the reservoir floor is observed, and it is noted that the thermocryogenic processes seen in the lower rockfill retaining prism and at the base of the dam are both cyclic. The stability indicators of the hydrosystem are within the standards defined by Russian legislative documents.
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Thermal Cryogenic Regime of the Hydrosystem of Vilyui Hydroelectric Power Plants-1, 2: Geocryologic Monitoring
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10.1007/s10749-017-0846-4
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2017-10-01
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Cryogenic-assisted machining has already shown its advantages on the process and the machining parameters have been analysed. However, part of the coolant jet characteristics as the pressure and flow rate have not been completely studied and optimized. Hence, the main objective of this study is to investigate the impact of these parameters on tool wear and surface integrity when machining the titanium alloy Ti-6Al-4V. Several nozzle diameters have been therefore employed in order to vary the pressure and the flow rate. A new nozzle holder has been developed to ensure the replacement of these calibrated nozzles of different diameters. The machining tests have allowed to draw attention to the impact of the pressure and the flow rate of the liquid nitrogen jet not only on tool life but also on surface integrity. Indeed, the increase of flow rate and pressure increases tool life. Moreover, surface integrity has been greatly improved notably at the highest pressure and the highest flow rate.
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Impact of supply conditions of liquid nitrogen on tool wear and surface integrity when machining the Ti-6Al-4V titanium alloy
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10.1007/s00170-017-0604-7
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2017-10-01
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The structural characterization of glycans by mass spectrometry is particularly challenging. This is because of the high degree of isomerism in which glycans of the same mass can differ in their stereochemistry, attachment points, and degree of branching. Here we show that the addition of cryogenic vibrational spectroscopy to mass and mobility measurements allows one to uniquely identify and characterize these complex biopolymers. We investigate six disaccharide isomers that differ in their stereochemistry, attachment point of the glycosidic bond, and monosaccharide content, and demonstrate that we can identify each one unambiguously. Even disaccharides that differ by a single stereogenic center or in the monosaccharide sequence order show distinct vibrational fingerprints that would clearly allow their identification in a mixture, which is not possible by ion mobility spectrometry/mass spectrometry alone. Moreover, this technique can be applied to larger glycans, which we demonstrate by distinguishing isomeric branched and linear pentasaccharides. The creation of a database containing mass, collision cross section, and vibrational fingerprint measurements for glycan standards should allow unambiguous identification and characterization of these biopolymers in mixtures, providing an enabling technology for all fields of glycoscience. Graphical Abstract ᅟ
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Cryogenic Vibrational Spectroscopy Provides Unique Fingerprints for Glycan Identification
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10.1007/s13361-017-1728-6
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2017-10-01
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This paper systematically investigated the effect of cryogenic temperature and soaking time on the 0Cr12Mn5Ni4Mo3Al steel. Microstructure observation and mechanical tests were performed on the specimens by scanning electron microscopy, x-ray diffraction, Vickers hardness tests and tensile tests. Cryogenic treatments were carried out at different temperatures of −73, −120, −160 and −196 °C for a given soaking time of 4 h and at a specific temperature of −73 °C for different soaking time of 8, 12, 21 and 32 h, followed by the subsequent tempering treatment. The results showed that the volume fraction of martensite in this steel has significantly increased and the size of martensite lath has decreased after cryogenic treatment, which leads to the improvement of the mechanical properties of the steel. The cryogenic treatment affected the microstructure by promoting the transformation of retained austenite to martensite and the formation of reversed austenite in the steel. The optimal hardness and strength of this steel were obtained by cryogenic treatment at −73 °C for 8 h. It has been found that the soaking time is a critical parameter for the mechanical properties of 0Cr12Mn5Ni4Mo3Al steel. When the cryogenic temperature is lower than −73 °C, there is no further improvement of the mechanical properties.
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Effect of Cryogenic Treatment on Microstructure and Mechanical Properties of 0Cr12Mn5Ni4Mo3Al Steel
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10.1007/s11665-017-2932-z
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2017-10-01
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This paper presents the analysis of average surface roughness, cutting force, and feed force in turning of difficult-to-machine Ti-6Al-4V alloy by experimental investigation and performance modeling. Based on knowledge of the literature, to pacify the elevated temperature in machining Ti-6Al-4V and to ensure a clean environment, the experiments are carried out in cryogenic (liquid nitrogen) condition by following the Taguchi L_18 mixed-level orthogonal array. Afterward, the models of responses have been formulated by the response surface methodology (RSM) and artificial neural network (ANN). The higher values of correlation coefficient (≥96%) and lower values of error determined the adequacy of the developed models. Comparative study of both models revealed that the RSM-based model revealed greater accuracy for the testing data and hence recommended. Analysis of variance (ANOVA) determined the effects of cutting speed, feed rate, and insert configuration on the quality characteristics. The results revealed that a cutting speed not exceeding 110 m/min is likely to generate favorable machining responses. In addition, the higher feed rate was found to ensure better machining performances. Moreover, the desirability-based multi-response optimization determined that a cutting speed of 78 m/min, a feed rate of 0.16 mm/rev, and use of the SNMM tool insert are capable of minimizing surface roughness at 1.05 μm, main cutting force at 315 N, and feed force at 208 N.
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Study of surface roughness and cutting forces using ANN, RSM, and ANOVA in turning of Ti-6Al-4V under cryogenic jets applied at flank and rake faces of coated WC tool
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10.1007/s00170-017-0566-9
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2017-10-01
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The Atacama Large Millimeter/Sub-millimeter Array (ALMA) is currently the largest (sub-)mm wave telescope in the world and will be used for astronomical observations in all atmospheric windows from 35 to 950 GHz when completed. The ALMA band 1 (35–50 GHz) receiver will be used for the longest wavelength observations with ALMA. Because of the longer wavelength, the size of optics and waveguide components will be larger than for other ALMA bands. In addition, all components will be placed inside the ALMA cryostat in each antenna, which will impose severe mechanical constraints on the size and position of receiver optics components. Due to these constraints, the designs of the corrugated feed horn and lens optics are highly optimized to comply with the stringent ALMA optical requirements. In this paper, we perform several tolerance analyses to check the impact of fabrication errors in such an optimized design. Secondly, we analyze the effects of operating this optics inside the ALMA cryostat, in particular the effects of having the cryostat IR filters placed next to the band 1 feed horn aperture, with the consequent near-field effects. Finally, we report on beam measurements performed on the first three ALMA band 1 receivers inside test cryostats, which satisfy ALMA specifications. In these measurements, we can clearly observe the effects of fabrication tolerances and IR filter effects on prototype receiver performance.
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ALMA Band 1 Optics (35–50 GHz): Tolerance Analysis, Effect of Cryostat Infrared Filters and Cold Beam Measurements
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10.1007/s10762-017-0414-x
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2017-10-01
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Forging dies are subjected to fatigue failures for which different surface treatments are used as most of the failures begin from the surface. In this work, the influence of cryogenic treatment on fatigue limit of die steels has been discussed with hardening of fatigue specimens of AISI H13 die steels at 1020 °C, oil quenching, double tempering at 500 °C, cryogenic treatment at minus 185 °C for 16 h followed by soft tempering at 100 °C. The fatigue limit analysis had been carried out with constant amplitude rotating bending fatigue testing at room temperature, at 3000 rpm with load variations which indicated improved fatigue limit for 16 h cryogenically treated specimens in the high cycle fatigue regime. This has been attributed to decreased surface roughness, increased hardness and precipitation of finer tertiary carbides as an influence of microstructure. The minimum value of fatigue strength exponent, in Basquin equation, has also depicted the increased fatigue limit for cryogenically treated H13 specimens.
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Influence of Tertiary Carbides on Improving Fatigue Limit of H13 Die Steels
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10.1007/s13632-017-0380-7
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2017-09-01
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Increased mineralization of the organic matter (OM) stored in permafrost is expected to constitute the largest additional global warming potential from terrestrial ecosystems exposed to a warmer climate. Chemical composition of permafrost OM is thought to be a key factor controlling the sensitivity of decomposition to warming. Our objective was to characterise OM from permafrost soils of the European Arctic: two mineral soils—Adventdalen, Svalbard, Norway and Vorkuta, northwest Russia—and a “palsa” (ice-cored peat mound patterning in heterogeneous permafrost landscapes) soil in Neiden, northern Norway, in terms of molecular composition and state of decomposition. At all sites, the OM stored in the permafrost was at an advanced stage of decomposition, although somewhat less so in the palsa peat. By comparing permafrost and active layers, we found no consistent effect of depth or permafrost on soil organic matter (SOM) chemistry across sites. The permafrost-affected palsa peat displayed better preservation of plant material in the deeper layer, as indicated by increasing contribution of lignin carbon to total carbon with depth, associated to decreasing acid (Ac) to aldehyde (Al) ratio of the syringyl (S) and vanillyl (V) units, and increasing S/V and contribution of plant-derived sugars. By contrast, in Adventdalen, the Ac/Al ratio of lignin and the Alkyl C to O-alkyl C ratio in the NMR spectra increased with depth, which suggests less oxidized SOM in the active layer compared to the permafrost layer. In Vorkuta, SOM characteristics in the permafrost profile did not change substantially with depth, probably due to mixing of soil layers by cryoturbation. The composition and state of decomposition of SOM appeared to be site-specific, in particular bound to the prevailing organic or mineral nature of soil when attempting to predict the SOM proneness to degradation. The occurrence of processes such as palsa formation in organic soils and cryoturbation should be considered when up-scaling and predicting the responses of OM to climate change in arctic soils.
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Soil organic matter molecular composition and state of decomposition in three locations of the European Arctic
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10.1007/s10533-017-0373-2
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2017-09-01
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The possibility of using cryogenic treatment technology for tool steel of grade Kh12VMF in preparing rolls for a profile-bending mill is analyzed. The nature of the effect of cryogenic treatment on the structure is considered: proportion of residual austenite and secondary carbide distribution, mechanical properties, and wear resistance of steel analog AISI D2. Results are analyzed for this experiment under Severstal conditions for improving the wear resistance of roundhead rolls by cryogenic treatment. Preliminary evaluation is provided for the efficiency of using cryogenic treatment in the production of bent rolled product.
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Use of Cryogenic Treatment to Improve Profile-Bending Roll Wear Resistance
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10.1007/s11015-017-0524-7
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2017-09-01
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This paper aimed to restrain the processing defects of aluminum alloy honeycombs using in aerospace with low stiffness and thin-walled, such as burr and collapse edge. The honeycomb material was treated by new method named ice fixation, and a CNC milling machine was used for a series of cryogenic machining. The fixation strength was calculated and machining defect reasons were analyzed. The cryogenic milling mechanism with ice fixation was established at the same time. Results show that compared to the without ice or conventional fixation way, the honeycomb fixation force and strength are all greatly increasing and that can reach 287 N and 19.1 kPa, respectively. Meanwhile, the processing defects are effectively suppressed. Others the cutting depth has greater influence on surface quality, and it makes the milling force improved three times, while the improvement of fixation and milling force and the cryogenic processing are the main reasons of reducing defects. The ice fixation cryogenic processing provides a new and effective method for aluminum alloy honeycomb with low rigidity and thin-wall.
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Green machining of aluminum honeycomb treated using ice fixation in cryogenic
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10.1007/s00170-017-0181-9
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2017-08-16
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Absolute spectral radiometry is currently the only established primary thermometric method for the temperature range above 1300 K. Up to now, the ongoing improvements of high-temperature fixed points and their formal implementation into an improved temperature scale with the mise en pratique for the definition of the kelvin, rely solely on single-wavelength absolute radiometry traceable to the cryogenic radiometer. Two alternative primary thermometric methods, yielding comparable or possibly even smaller uncertainties, have been proposed in the literature. They use ratios of irradiances to determine the thermodynamic temperature traceable to blackbody radiation and synchrotron radiation. At PTB, a project has been established in cooperation with VNIIOFI to use, for the first time, all three methods simultaneously for the determination of the phase transition temperatures of high-temperature fixed points. For this, a dedicated four-wavelengths ratio filter radiometer was developed. With all three thermometric methods performed independently and in parallel, we aim to compare the potential and practical limitations of all three methods, disclose possibly undetected systematic effects of each method and thereby confirm or improve the previous measurements traceable to the cryogenic radiometer. This will give further and independent confidence in the thermodynamic temperature determination of the high-temperature fixed point’s phase transitions.
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Thermodynamic Temperature of High-Temperature Fixed Points Traceable to Blackbody Radiation and Synchrotron Radiation
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10.1007/s10765-017-2273-z
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2017-08-01
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Purpose A new in-vacuum three-dimensional Hall probe magnetic measurement system is under fabrication for characterizing the magnetic performance of the Cryogenic Permanent Magnet Undulator (CPMU). In order to fit the small gap (5 mm) of magnetic structure and vacuum environment, a small three-dimensional Hall probe has been manufactured. The angular and positional misalignment errors of the Hall sensors play an important role in the measurement accuracy of the CPMU. In order to minimize the misalignment errors, a method of calibrating angle error and relative assembly displacements of a three-dimensional Hall probe is carried out. Methods The angle error of Hall sensors will be calibrated by a standard dipole magnet and a five-dimensional Hall bench. The standard dipole magnet will generate a single direction and uniform magnetic field. And the five-dimensional Hall bench is used to rotate the Hall probe which is put in the center of magnet. Based on the relationship between angle and magnetic field strength, the angle error of each Hall sensor will be obtained. The relative position between the sensitive areas of the Hall sensors will be calibrated by a two-dimensional magnetic field undulator section. Based on Maxwell’s equations, through the calculation of measurement magnetic field strength, the relative assembly displacements of the three Hall sensors can be derived. Results The details of the calibration methods and the data processing of angle error and relative assembly displacements of a three-dimensional Hall probe are presented. The three-dimensional magnetic fields of a cryogenic permanent magnet undulator can be received accurately by correcting these angle errors and position errors of Hall sensors. Conclusions This paper illustrates the relative position and angle calibration procedures and the data processing of a three-dimensional Hall probe. Now the design of a smaller Hall probe is in process. The calibration of the angle errors and position errors will be carried out after the fabrication of the standard dipole magnet.
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Hall sensor angle error and relative position calibrations for cryogenic permanent magnet undulator of high energy photon source test facility (HEPS-TF)
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10.1007/s41605-017-0018-y
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2017-08-01
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This paper is aimed to restrain the defects such as fluff and ablation, which were often found in machining of the aramid fiber-reinforced composites (AFRP). The cooling method of spray liquid nitrogen was adopted in the orthogonal milling process. The processing parameters including cutting depth, cutting speed, cooling temperature, feed speed, and liquid nitrogen flow were considered in details, and their effects on the processing quality were researched and analyzed. The analysis optimization methods of processing parameter were employed for the influence on the machining surface quality. Meanwhile, the optimal machining surface quality was predicted and verified. The results show that the cryogenic way realizes a bigger improved role on machining quality than the conventional one for AFRP. As well as the influence order of processing parameters on the roughness is cutting depth, cutting speed, cooling temperature, feed speed, and liquid nitrogen flow. And the predicted result Ra = 0.557 μm of minimum surface roughness value is similar with the actual one Ra = 0.572 μm and verifies the feasibility of optimization method. For processing of AFRP, the cooling way of spray liquid nitrogen has a positive role with high quality and efficiency.
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Optimization of cryogenic milling parameters for AFRP
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10.1007/s00170-017-0003-0
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2017-08-01
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This paper presents the first comprehensive investigation on the serious problems of tool wear and service life in conventional milling nickel-based superalloy. A series of machining experiments were conducted at various combinations of cutting parameters in conventional and cryogenic at 77-K milling processes. The morphology and element compositions of tool processing surfaces were analyzed and measured by the scanning electron microscopy and an energy-dispersive spectrometer, respectively. Meanwhile, the carbide tool wear behavior and mechanism in cryogenic cooling condition were also discussed in detail. The new findings indicate that at low cutting speed, the adhesive wear is easily found for the conventional machining, and the oxidation wear is for the high speed. As well as the cutting depth and feed speed are all limited, that is, lower machining efficiency. In liquid nitrogen cryogenic condition, the tool wear is not apparent at low and medium speeds, so that we can choose larger cutting depth and feed speed. At high speed, a part of adhesion and diffusion wears can be found, that is, inconspicuous oxidative wear, and the chip already made the plastic change. Furthermore, the tool service life can be increased four times at high speed and the processing efficiency is also improved obviously. The use of the liquid nitrogen cryogenic processing method can effectively solve the problems of serious tool wear and the lower processing efficiency for the nickel-based superalloy.
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Research on tool wear of milling nickel-based superalloy in cryogenic
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10.1007/s00170-017-0079-6
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2017-07-01
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Hot single point incremental forming (SPIF) with induction heating and cryogenic cooling has been applied to form the Ti-6Al-4V sheets. The influence of both the forming temperature and the cooling rate after deformation, on microstructure evolution and microhardness of Ti-6Al-4V sheets, has been extensively studied. We propose the use and development of a new system of heating by induction. The system is composed of a medium–high frequency generator and a continuously water-cooled heating head, which is placed under the sheet and linked axially to the punch movement, heating the material locally by generating an eddy current within the material. Furthermore, a cooling system integrated with the movement of the forming punch allows us to apply a cryogenic fluid to the recently deformed sheet metal. Both localized heating and cooling systems are particularly suitable for such a process as SPIF, whose primary characteristic is the incremental forming of localized sheet zones. The meta-dynamic and static recrystallization processes have been suppressed in the sheet material, evident by the final microstructure and mechanical properties. Finally, a comparison between parts is made, both with and without cooling during hot SPIF.
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Induction heating and cryogenic cooling in single point incremental forming of Ti-6Al-4V: process setup and evolution of microstructure and mechanical properties
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10.1007/s00170-016-9794-7
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2017-07-01
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Although electrical discharge machining is a metal removal process in form of debris, efforts have been made in this article to make use of this process as a surface treatment method. Effect of different process parameters and mechanism of material deposition also studied under this study. Powder mixed electric discharge machining (PMEDM) process has been used which helps in improving the surface properties. In this study, changes in surface properties of cryogenically treated titanium alloy after PMEDM process were investigated. Experimental results showed significant improvement in micro-hardness by 94.85 %. Various studies, like scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) were carried out to study the characteristics of the machined surface. After scanning the machined surface through XRD and EDX, the transfer of various elements from electrode material and powder mixed dielectric and their chemical compounds were observed. After screening the results, peak current was observed as the highly influential parameter that affected the micro-hardness as well as surface quality of the machined surface.
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Investigating surface properties of cryogenically treated titanium alloys in powder mixed electric discharge machining
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10.1007/s40430-016-0639-y
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2017-07-01
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Physicochemical properties of nutritional supplements, such as apple, Jerusalem artichoke, and black currant cryogenic powder, were studied by adiabatic calorimetry in the range of 80–320 K and differential thermal analysis in the range of 80–400 K. Temperatures of relaxation transitions and influence of water on these transitions were determined. In thermograms, completely dehydrated samples demonstrated several relaxation transitions (γ-, β-, α_1 and α_2), which are caused by the presence in the studied nutritional supplements of some polysaccharides. The water has a plasticizing effect on nutritional supplements and lowers their relaxation transition temperature. By melting enthalpy of the water phase, which is insoluble in cryogenic powder, the concentration of the saturated solution of water in cryogenic powder at the melting point of water using a calorimetric method was determined (22 ± 1 mass % H_2O in cryogenic powder from apple; 19 ± 1 mass % H_2O in Jerusalem artichoke; 24.1 ± 0.1 mass % from black currant). The diagram of physical states of cryogenic powder from an apple–water system was constructed and analyzed in a wide temperature range and over the entire range of concentrations of ingredients.
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Nutritional supplements from plant raw materials and influence of water on their physicochemical properties
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10.3103/S1068367417040152
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2017-07-01
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Cryogenic treatment is a supplementary heat treatment usually applied after quenching. Its effects are permanent and this process affects the entire section. There have been many studies related to cryogenic treatment, most of which have been focused on tool steels. In the current study, a high-speed-train railway material was investigated, and different heat treatment processes were applied to the eutectoid steel. The effects of quenching and cryogenic treatment were investigated on the mechanical properties (toughness, hardness and wear). Four different structures were obtained with different heat treatment cycles: Pearlitic, tempered martensite, 12 hour cryo-treated tempered and 36 hour cryo-treated tempered. As a result of Charpy v-notch tests and hardness tests, cryogenic treatment was found to improve the toughness and hardness of quenched samples. The results of the ball-on-disc wear tests showed that the cryo-treated samples have better wear resistance than pearlitic and martensitic samples.
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The effects of cryogenic treatment on the toughness and tribological behaviors of eutectoid steel
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10.1007/s12206-017-0613-3
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2017-07-01
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Titanium alloys are widely used in aerospace, biomedical, and other engineering areas due to their superior properties. However, machining of titanium alloys has always been a challenge due to the high temperatures and tool wear rates. Dry machining has a limited range of permissible cutting conditions and is hence not suitable for industrial production. As a solution, flood cooling using cutting fluids is conventionally used to reduce the cutting temperatures. However, it is often discouraged in light of the associated environmental and health hazards. In order to achieve sustainable machining, different strategies for applying the cutting fluids are developed. Some of the prominent methods include minimum quantity lubrication (MQL), minimum quantity cooled lubrication (MQCL), and cryogenic cooling. This paper provides a comprehensive review of the available recent literature on such studies. Each of these techniques and results obtained in the studies has been discussed with emphasis on the advantages and limitations of each method. Major conclusions drawn are that coated carbides are better and machinability is greatly affected by the microstructure of the material. MQL certainly improved compared to other methods while cryogenic or super cooled cutting fluid application (MQCL) has been found to be better for specific situations. Use of nanofluids for titanium is not very popular among the researchers.
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Application of cutting fluids in machining of titanium alloys—a review
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10.1007/s00170-016-9883-7
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2017-07-01
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In this study, the effect of both cryogenic and dry machining of AZ31 magnesium alloy on temperature and surface roughness was examined. Cryogenic machining experiments were conducted by applying liquid nitrogen at the cutting zone. The cutting parameters (cutting speed, depth of cut, and feed rate) were varied, and their effect on the results was identified. It was found that the cryogenic machining was able to reduce the maximum temperature at the machined surface to about 60% as compared with dry machining. A finite element model was developed to predict the temperature distribution at the machined surface. The simulated results showed good agreement with the experimental data. After analyzing the temperature distribution, the model also suggested that the cryogenic-assisted machining removes heat at a faster rate as to that of the dry machining. An arithmetic model using the response surface method was also developed to predict the maximum temperature at the surface during cryogenic and dry machining. The analysis pointed out that the maximum temperature was greatly affected by the cutting speed followed by feed rate and depth of cut. Cryogenic machining leads to better surface finish with up to 56% reduction in surface roughness compared with dry machining.
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Thermal analysis during turning of AZ31 magnesium alloy under dry and cryogenic conditions
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10.1007/s00170-016-9893-5
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2017-07-01
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Titanium alloy is well known for its difficulty to machine, owing to the important “tool wear” phenomenon. Machining assistance is an interesting solution to lengthen the tool lifetime. In this study, we focused on the effect of cryogenic assistance—during machining of Ti17—on the tool wear and cutting forces for different combinations of cutting speed, feed rate and depth of cut. Compared to conventional lubrication, cryogenic support lengthens the tool life for all tested conditions and has no significant influence on cutting force. A comparison of the cryogenic effect and high-pressure water jet assistance is also presented.
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Tool wear and cutting forces under cryogenic machining of titanium alloy (Ti17)
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10.1007/s00170-016-9841-4
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2017-07-01
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This experimental study focuses on the phase state and phase transformation response of the surface and subsurface of machined NiTi alloys. X-ray diffraction (XRD) analysis and differential scanning calorimeter techniques were utilized to measure the phase state and the transformation response of machined specimens, respectively. Specimens were machined under dry machining at ambient temperature, preheated conditions, and cryogenic cooling conditions at various cutting speeds. The findings from this research demonstrate that cryogenic machining substantially alters austenite finish temperature of martensitic NiTi alloy. Austenite finish ( A _f) temperature shows more than 25 percent increase resulting from cryogenic machining compared with austenite finish temperature of as-received NiTi. Dry and preheated conditions do not substantially alter austenite finish temperature. XRD analysis shows that distinctive transformation from martensite to austenite occurs during machining process in all three conditions. Complete transformation from martensite to austenite is observed in dry cutting at all selected cutting speeds.
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Surface Characteristics of Machined NiTi Shape Memory Alloy: The Effects of Cryogenic Cooling and Preheating Conditions
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10.1007/s11665-017-2791-7
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2017-07-01
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A novel process comprised of ultra-fast cooling after control rolling, intercritical quenching and tempering (UFC-LT) was applied to 3.5%Ni steel. In addition, quenching and tempering (QT) treatment was conducted in comparison. The present study focuses on the relationship between the microstructure and cryogenic toughness of 3.5%Ni steel. Results show that the microstructure of steel treated by UFC-LT consisted of tempered martensite, intercritical ferrite and two types of reversed austenite (RA) (needle shape and blocky). Compared to the QT sample, the UFC-LT sample’s ultimate tensile strength decreased slightly, while its elongation increased from 32.3 to 35.7%, and its Charpy absorption energy at −135 °C increased from 112 to 237 J. The ductile-brittle transition temperature of UFC-LT sample was lower than that of the QT sample by 18 °C. The superior cryogenic toughness after UFC-LT compared to QT treatment can be attributed to the dissolution of cementite, approximately 3.0% increase in RA and the decrease in effective grain size.
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Effects of Ultra-Fast Cooling After Hot Rolling and Intercritical Treatment on Microstructure and Cryogenic Toughness of 3.5%Ni Steel
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10.1007/s11665-017-2735-2
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2017-06-01
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The deformation behaviour of metals and alloys is significantly affected by both stacking-fault energy and processing temperature. By lowering the former, deformation twinning is favoured over dislocation slip, whilst cryogenic processing partially suppresses dynamic recovery. Three materials having different stacking-fault energies, that is, Al AA1050 (high), pure Cu (medium) and Cu–15Zn alloy (low) were rolled at room (RTR) and at cryogenic (CR) temperatures up to a true strain equal to 1.5. Annealed coarse-grained samples were tested in tension at room and cryogenic temperatures. The processed samples were characterized by optical and transmission electron microscopy, hardness measurements and room-temperature tensile tests. CR increases the tensile strength with respect to RTR for the three materials; elongation to failure is decreased for AA1050, whilst for Cu and Cu–15Zn the CR effectively increases the ductility. Cu–15Zn sample after CR exhibits a microstructure relatively heterogeneous, suggesting static recrystallization events in the temperature excursion from 77 to 298 K. Finally, it was concluded that cryogenic deformation increases strength, whilst low SFE increases the ability to absorb plastic deformation, an effect strongly increased at cryogenic temperatures. The present investigation gives some basis for the development of cryogenic severe plastic deformation processes.
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Plastic deformation of FCC alloys at cryogenic temperature: the effect of stacking-fault energy on microstructure and tensile behaviour
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10.1007/s10853-017-0979-8
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2017-06-01
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Metastable 304 austenitic stainless steel was subjected to rolling at cryogenic and room temperatures, followed by annealing at different temperatures from 500 to 950°C. Phase transition during annealing was studied using X-ray diffractometry. Transmission electron microscopy and electron backscattered diffraction were used to characterize the martensite transformation and the distribution of austenite grain size after annealing. The recrystallization mechanism during cryogenic rolling was a reversal of martensite into austenite and austenite growth. Cryogenic rolling followed by annealing refined grains to 4.7 μm compared with 8.7 μm achieved under room-temperature rolling, as shown by the electron backscattered diffraction images. Tensile tests showed significantly improved mechanical properties after cryogenic rolling as the yield strength was enhanced by 47% compared with room-temperature rolling.
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Effect of cryogenic rolling and annealing on the microstructure evolution and mechanical properties of 304 stainless steel
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10.1007/s12613-017-1446-x
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2017-06-01
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This paper reports the technical details of the development of a low-temperature amplifier for nuclear magnetic resonance measurements of superfluid $${}^3$$ 3 He in very confined geometries. The amplifier consists of commercially available enhancement-mode pseudomorphic high-electron-mobility transistor devices and temperature-insensitive passive components with an operating frequency range of 0.2–6 MHz.
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Development of Cryogenic Enhancement-Mode Pseudomorphic High-Electron-Mobility Transistor Amplifier
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10.1007/s10909-017-1763-5
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2017-06-01
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Superinvar Fe-31Ni-5Co alloy (SI) and Co-20Cr-15W-10Ni superalloy (SA) are used in space applications. Similar metal (SI-SI and SA-SA) joints as well as dissimilar metal (SA-SI) joints of these alloys have been made using electron beam welding (EBW) technique. Extensive characterization of these weldments has been carried out using optical and electron microscopy, microhardness measurements and tensile testing at ambient and cryogenic temperatures. It has been observed that weld efficiency is 100% for similar metal joints, whereas it is governed by base metal properties of the alloy having lower strength for dissimilar metal joint. Weld efficiency of SA-SI/EBW joint is comparable with base metal of lower strength indicating no detrimental formation of intermetallic/brittle phase. Microhardness of the SA-SI/EBW joint is found to be representative of the respective base metal properties with no sudden variation across the SA/SI interface in the weldment indicating good dilution in the weld. This has been confirmed through energy-dispersive spectrum using x-rays (EDX) showing the presence of Fe near the superalloy weldment interface and the presence of Cr and W near the superinvar weldment interface. Increase in strength and decrease in ductility of base metals are observed for all types of joints when tested at cryogenic temperature (77 K) vis-à-vis at ambient temperature. Fracture features of the failed surface of SA-SI/EBW joint are found to be similar to that of the SI-SI/EBW joint. Microhardness, mechanical properties and fracture analysis confirm that failure of dissimilar metal joint takes place toward lower strength base metal, i.e., superinvar.
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Studies on Similar and Dissimilar Metal EBW Joints of Fe-31Ni-5Co and Co-20Cr-15W-10Ni Alloys
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10.1007/s11665-017-2718-3
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2017-05-13
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The non-contact mechanical seal of a high-speed turbopump in a liquid rocket engine operates under very harsh conditions (such as rapid start-up, cryogenic, high-speed, high-pressure and low-viscosity sealing fluid). The performance of the seal is very different to the performance under normal running conditions. In this paper, for the sake of safety, an experiment is carried out with liquid nitrogen as the sealing fluid. The experimental results with liquid nitrogen are expected to provide an equivalent seal performance as would be experienced with liquid oxygen and liquid hydrogen rocket engine. The main performance parameters, including face temperatures, leakage, face friction force, and friction coefficients, are measured in the speed-up, stable, and speed-down stages. The results show that in the speed-up stage, with rapidly increasing speed, the local face temperature rises dramatically to even higher than the vaporization temperature of liquid nitrogen, and a two-phase flow phenomenon occurs. In the start-up and stable stages, the friction coefficients are 0.25 and 0.13, respectively. After the test, it was found that the wear thickness of the rotor was 0.2 mm, and serious point corrosion appeared on the surface of the stator.
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An Experimental Test on a Cryogenic High-Speed Hydrodynamic Non-Contact Mechanical Seal
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10.1007/s11249-017-0865-1
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2017-05-02
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Environmental control during transfer between instruments is required for samples sensitive to air or thermal exposure to prevent morphological or chemical changes prior to analysis. Atom probe tomography is a rapidly expanding technique for three-dimensional structural and chemical analysis, but commercial instruments remain limited to loading specimens under ambient conditions. In this study, we describe a multifunctional environmental transfer hub allowing controlled cryogenic or room-temperature transfer of specimens under atmospheric or vacuum pressure conditions between an atom probe and other instruments or reaction chambers. The utility of the environmental transfer hub is demonstrated through the acquisition of previously unavailable mass spectral analysis of an intact organic molecule made possible via controlled cryogenic transfer into the atom probe using the hub. The ability to prepare and transfer specimens in precise environments promises a means to access new science across many disciplines from untainted samples and allow downstream time-resolved in situ atom probe studies.
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An environmental transfer hub for multimodal atom probe tomography
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10.1186/s40679-017-0045-2
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2017-05-01
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Synthesis of a mathematical model of cooling of supercharging gas in the vapor space of cryogenic tanks containing liquefied gas is studied. Based on the model of a unidimensional dynamic thermal boundary layer, it is shown that the heat flux through the free liquid hydrogen surface in the cryogenic tank having a vapor space supercharged with gaseous hydrogen is much less than the heat flux through a wetted surface. The operational process of supercharging vapor space with gaseous hydrogen is studied by the example of a commercial liquid hydrogen tank. An example of calculation that shows the procedure of calculation of specific heat fluxes is given. The calculation results show that in the working range of fractions of the vapor space the heat flux through the liquid surface is much less than the heat flux through a wetted surface and that the heat of the supercharging gas exerts practically no influence on the change in temperature of the cryogenic liquid during its storage in the tank.
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Estimation of Heat Flux Through Free Liquid Hydrogen Surface in Cryogenic Tanks with Supercharged Vapor Space
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10.1007/s10556-017-0302-1
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2017-05-01
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We present our results on utilization of the quantum levitation effect for HTSC samples (superconducting ceramics based on YBa_2Cu_3O_7 −x and SuperOx J-PI-12-20Ag-20Cu superconducting tapes) in magnetic fields of different configurations with respect to developing special carriers for hybrid systems of noncontact transport of cryogenic targets in ICF experiments. We implement the obtained results for developing and engineering of “HTSC-MAGLEV” delivery system to minimize the risk for damage of the fuel layer at the target acceleration and during target injection into the center of the ICF reaction chamber.
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Development of Hybrid Transport Systems for Delivering Cryogenic Fusion Targets Into Focus of High-Power Laser System or ICF Reactor
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10.1007/s10946-017-9640-x
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2017-05-01
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Preservation of genetic diversity within germplasm repositories represents an important tool for plant conservation. However, seeds must tolerate extreme levels of post-harvest desiccation and cold to realize benefits of ex situ storage. Factors including local climate and habitat impact expression of desiccation and freezing tolerance especially for widely distributed species. Our aim here was to understand the influence of a latitudinal gradient on seed desiccation and cryo-freezing tolerance. We sampled mature U. paniculata seeds from two geographically and genetically distinct populations then examined seed-water relations and germination following desiccation via equilibrium drying assays (0.5 to 91% RH; −797 to −12.9 MPa). Germination ability after drying and subsequent cryo-freezing treatments (−196 °C, 1 to 1440 min) was also evaluated. Seeds of both populations displayed similar reverse sigmoid moisture sorption isotherms characteristic of desiccation tolerant tissues. Furthermore, initial seed water potential (−63 and −90 MPa) was considerably lower than the lethal limit (−20 MPa) identified for desiccation sensitive tissues. Final germination (range 58–93%) and temporal patterns differed significantly between populations following desiccation and cryo-freezing stress, but these germination responses were similar to initial germination. A higher proportion of non-germinated, yet viable seeds remained for the northern compared to southern population. Location does influence germination response, but differential germination is related to seed dormancy rather than desiccation or cryo-freezing sensitivity. Ex situ conservation of U. paniculata is therefore feasible across the latitudinal gradient studied here.
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Different plant provenance same seed tolerance to abiotic stress: implications for ex situ germplasm conservation of a widely distributed coastal dune grass (Uniola paniculata L.)
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10.1007/s10725-016-0244-1
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2017-05-01
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This paper presents comprehensive investigation on the nickel-base alloy material used in the aerospace with difficult machining whose cutting tool is worn failure quickly. The reason mainly relates to the high temperature of cutting zone. The cryogenic cooling method was adopted for a series of machining experiments. Based on the entropy production of the cutting system, the entropy productions of diffusion, adhesion, and oxidation wear of tool were calculated under different cutting speeds. And the wear mechanism was explained through the self-organization characteristics of cutting friction and wear system. The results indicate that with the increase of cutting speed, it has the greater entropy production. To traditional cutting, at the 132 m/min speed, the entropy production has not had the decreased stage with time, and the tool self-organizing has not played a role. However, in cryogenic cooling environment, when the speed is 220 m/min, the cutting tool’s self-organization is still in effect, and its service life can be significantly extended more than three times. Compared with the traditional processing, the cryogenic one is more likely to form a self-organization dissipative structure and obviously improves the cutting speed which the self-organization can play a role. Furthermore, it also increases the cutting effect with the best processing efficiency.
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Milling wear of carbide tool for processing nickel-based alloy in cryogenic based on the entropy change
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10.1007/s00170-016-9505-4
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2017-05-01
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In this paper, a complete industrial validation of a recently published scheme for on-line adaptation of the control updating period in model predictive control is proposed. The industrial process that serves in the validation is a cryogenic refrigerator that is used to cool the supra-conductors involved in particle accelerators or experimental nuclear reactors. Two recently predicted features are validated: the first states that it is sometimes better to use less efficient (per iteration) optimizer if the lack of efficiency is over-compensated by an increase in the updating control frequency. The second is that for a given solver, it is worth monitoring the control updating period based on the on-line measured behavior of the cost function.
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Experimental investigation of control updating period monitoring in industrial PLC-based fast MPC: Application to the constrained control of a cryogenic refrigerator
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10.1007/s11768-017-6109-y
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2017-04-25
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Rhodium–iron resistance thermometers are recommended as precise thermometers at temperatures below 25 K. The thermometers were developed at the National Physical Laboratory and produced by H. Tinsley and Co Ltd almost 50 years ago. Later, they were made by other companies and institutes as well, but despite this, the availability of the thermometers decreased and a new source of supply was needed. Several years ago, the Technical Institute of Physics and Chemistry (TIPC), Chinese Academy of Sciences, developed its own technology for making wire of Rh-0.5 at% Fe alloy which was used in the production of new thermometers. These devices have been tested previously at INRIM (Italy) and later at INTiBS (Poland). INTiBS has carried out an investigation focused on the thermometers’ stability after thermal cycling treatment. This paper presents the results of stability tests of about 30 thermometers produced by TIPC in two batches. The resistance of each thermometer was measured at temperatures of about 4.6 K and 7.2 K before and after 10, 30 and 50 thermal cycles from room temperature. The methods of measurement and the design of the cryostat used for the research are also presented.
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Tests of the Stability of Chinese RhFe Resistance Thermometers at Low Temperatures
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10.1007/s10765-017-2232-8
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