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Sample records for temperature compressive properties

  1. Effects of temperature on the compressive properties of extruded ...

    African Journals Online (AJOL)

    Recycled plastics, over the years, are believed to be inferior to virgin plastics. In this work, compression test was carried out on virgin and recycled uPVC plastics at different temperatures, from 25°C to 130°C at intervals of 15°C, to determine and to compare their compressive properties. The specimens were heat treated in ...

  2. The development f high temperature triaxial compressive autoclave to investigate the change of rock properties under high temperature

    International Nuclear Information System (INIS)

    Nakata, Eiji; Chigira, Masahiro

    2000-01-01

    The studies on mechanical properties at the high temperature unsaturated condition and saturated condition were rarely carried Out. Development of high temperature triaxial compressive machine combined with two fluid-flow hydrothermal equipments was required to investigate the hydrological and geochemical phenomenon under the deep ground. We developed the 'high temperature triaxial autoclave (HTTA)' to investigate the physical, mechanical and chemical behavior of sedimentary rocks at the high temperature. The HTTA is able to perform permeability test and triaxial compressive test between room temperature and 140 the maximum pore pressure of 10 MPa, the maximum confining pressure of 26 MPa, and the maximum axial stress of 370 MPa. We carried out uniaxial compressive test of dacite at 91.7degC under water saturated condition. The uniaxial compressive strength and the modulus of elasticity of dacite at 91.7degC under water saturated conditions were the lowest. (author)

  3. Compressive mechanical properties of HTPB propellant at low temperatures and high strain rates

    Directory of Open Access Journals (Sweden)

    Xiangdong Chen

    Full Text Available To study the compressive mechanical properties of the hydroxyl-terminated polybutadiene (HTPB propellant at high strain rates (700–1900/s and low temperatures (−50 °C to 25 °C, we conducted a dynamic mechanical experiment using cylindrical specimens on a split Hopkinson pressure bar (SHPB. In addition, scanning electron microscopy was employed to observe the compressive fracture surfaces. The experimental results indicate the effectiveness of the proposed SHPB testing for the HTPB propellant. The effects of the strain rate and low temperature remarkably influenced the variations in stress. The lower temperatures and higher the strain rate generated an obvious increase in the modulus and compressive strength. Even at −50 °C and 1900/s, the propellant still maintained its viscoelastic characteristics. On the basis of the time–temperature equivalence principle, we obtained the master curves of the mechanical parameters. The propellant mainly exhibited transgranular fracture damage, increased porosity, and matrix tearing after impact. Keywords: HTPB propellant, Dynamic mechanical properties, Low temperatures, High strain rates

  4. Room-temperature vibrational properties of potassium gadolinium double tungstate under compression up to 32 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Errandonea, D., E-mail: daniel.errandonea@uv.es [Departamento de Física Aplicada – ICMUV, Universitat de València, 46100 Burjassot, Valencia (Spain); Pellicer-Porres, J. [Departamento de Física Aplicada – ICMUV, Universitat de València, 46100 Burjassot, Valencia (Spain); Pujol, M.C.; Carvajal, J.J.; Aguiló, M. [Física i Cristal lografia de Materials i Nanomaterials (FiCMA-FICNA) – EMAS, Universitat Rovira i Virgili (URV), C/Marcel lí Domingo 1, 43005 Tarragona (Spain)

    2015-07-25

    Highlights: • Two phase transitions are pressure-induced in KGd(WO{sub 4}){sub 2} at 7.2, and 14.2 GPa. • Raman-active modes and their pressure dependences are reported and discussed. • Several modes showing a weak softening are found and related with structural changes. - Abstract: KGd(WO{sub 4}){sub 2} has been studied by high-pressure Raman spectroscopy at room temperature up to 32.2 GPa. Evidences of two pressure-driven phase transitions have been detected. The low-pressure monoclinic phase undergoes a phase transition at 7.2(±0.9) GPa. The second transition is found at 14.2(±1.6) GPa. Both transitions are reversible. No evidence of pressure-induced amorphization is found up to 32 GPa. The pressure dependence of the Raman active modes of the low- and high-pressure phases is reported. A Raman mode is detected to exhibit a weak softening in the low-pressure phase. Three Raman modes are also observed to have a similar behavior in the second high-pressure phase. The reported results are discussed comparing with the studies available in related tungstates. Emphasis is placed on the physical implications of the results.

  5. Compressive ion acoustic double layer and its transitional properties for a two electron temperature warm, multi-ion plasma

    Science.gov (United States)

    Steffy, S. V.; Ghosh, S. S.

    2018-01-01

    The emergence of the compressive ion acoustic double layer has been investigated for a two electron temperature warm, multi-ion plasma by the Sagdeev pseudopotential technique. It shows that the ambient cooler electron concentration plays a deterministic role in initiating the transition process of a compressive ion acoustic solitary wave to its double layer. Incorporating the derivative analysis for the pseudopotential, the transitional phase was further quantified by assigning a critical value for the ambient cooler electron concentration. It has been observed that, beyond that critical value, the width of the solitary wave increases rapidly with the increasing amplitude which coincides with the aforementioned transitional phase, manifesting a change in the internal microphysics of the structure for that region. A comparison with the satellite observation revealed good agreement validating the present model. The model will be useful in interpreting the observed monopolar structures in the auroral acceleration region.

  6. On the compressibility and temperature boundary of warm frozen soils

    Science.gov (United States)

    Qi, Jilin; Dang, Boxiang; Guo, Xueluan; Sun, Xiaoyu; Yan, Xu

    2017-04-01

    A silty-clay obtained along the Qinghai-Tibetan railway and a standard Chinese sand were taken as study objects. Saturated frozen soil samples were prepared for testing. Step-load was used and confined compression was carried out on the soils under different temperatures. Compression index and pseudo-preconsolidation pressure (PPC) were obtained. Unlike unfrozen soils, PPC is not associated with stress history. However, it is still the boundary of elastic and plastic deformations. Different compression indexes can be obtained from an individual compression curve under pressures before and after PPC. The parameters at different thermal and stress conditions were analyzed. It is found that temperature plays a critical role in mechanical behaviours of frozen soils. Efforts were then made on the silty-clay in order to suggest a convincing temperature boundary in defining warm frozen soil. Three groups of ice-rich samples with different ice contents were prepared and tested under confined compression. The samples were compressed under a constant load and with 5 stepped temperatures. Strain rates at different temperatures were examined. It was found that the strain rate at around -0.6°C increased abruptly. Analysis of compression index was performed on the data both from our own testing program and from the literature, which showed that at about -1°C was a turning point in the curves for compression index against temperature. Based on both our work and taking into account the unfrozen water content vs. temperature, the range of -1°C to -0.5°C seems to be the temperature where the mechanical properties change greatly. For convenience, -1.0°C can be defined as the boundary for warm frozen soils.

  7. Small scale plasticity and compressive properties of composites

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard

    . In the present work, the influence of the mechanical properties of the matrix material on the compression strength is studied by changing the temperature during mechanical testing and thereby making it possible changing the matrix properties keeping all other properties in the experimental setup constant......The compression strength of uni-directional composite materials is mainly governed by the fiber-misalignment and the plasticity of the matrix material [1]. Therefore, in order to improve the compression behavior of uni-directional composite materials, a focus on those terms is necessary....... It is demonstrated how going from the more ductile high temperature case to the brittle low temperature case will increase the compression strength significantly with more than 30%. This behavior are validated experimentally as well as numerically using a non-linear smeared out composite material law [2] implemented...

  8. Effect of elevated temperature on the compressive strength of ...

    African Journals Online (AJOL)

    Concrete materials in structures are usually exposed to high temperatures during fire. The relative properties of concrete after such an exposure are of great importance in terms of the serviceability of buildings. The effect of partial replacement of cement with pulverized steel mill scale (PSMS) on the compressive strength of ...

  9. Composition-Structure-Property Relations of Compressed Borosilicate Glasses

    Science.gov (United States)

    Svenson, Mouritz N.; Bechgaard, Tobias K.; Fuglsang, Søren D.; Pedersen, Rune H.; Tjell, Anders Ø.; Østergaard, Martin B.; Youngman, Randall E.; Mauro, John C.; Rzoska, Sylwester J.; Bockowski, Michal; Smedskjaer, Morten M.

    2014-08-01

    Hot isostatic compression is an interesting method for modifying the structure and properties of bulk inorganic glasses. However, the structural and topological origins of the pressure-induced changes in macroscopic properties are not yet well understood. In this study, we report on the pressure and composition dependences of density and micromechanical properties (hardness, crack resistance, and brittleness) of five soda-lime borosilicate glasses with constant modifier content, covering the extremes from Na-Ca borate to Na-Ca silicate end members. Compression experiments are performed at pressures ≤1.0 GPa at the glass transition temperature in order to allow processing of large samples with relevance for industrial applications. In line with previous reports, we find an increasing fraction of tetrahedral boron, density, and hardness but a decreasing crack resistance and brittleness upon isostatic compression. Interestingly, a strong linear correlation between plastic (irreversible) compressibility and initial trigonal boron content is demonstrated, as the trigonal boron units are the ones most disposed for structural and topological rearrangements upon network compaction. A linear correlation is also found between plastic compressibility and the relative change in hardness with pressure, which could indicate that the overall network densification is responsible for the increase in hardness. Finally, we find that the micromechanical properties exhibit significantly different composition dependences before and after pressurization. The findings have important implications for tailoring microscopic and macroscopic structures of glassy materials and thus their properties through the hot isostatic compression method.

  10. Multishock Compression Properties of Warm Dense Argon

    Science.gov (United States)

    Zheng, Jun; Chen, Qifeng; Yunjun, Gu; Li, Zhiguo; Shen, Zhijun

    2015-10-01

    Warm dense argon was generated by a shock reverberation technique. The diagnostics of warm dense argon were performed by a multichannel optical pyrometer and a velocity interferometer system. The equations of state in the pressure-density range of 20-150 GPa and 1.9-5.3 g/cm3 from the first- to fourth-shock compression were presented. The single-shock temperatures in the range of 17.2-23.4 kK were obtained from the spectral radiance. Experimental results indicates that multiple shock-compression ratio (ηi = ρi/ρ0) is greatly enhanced from 3.3 to 8.8, where ρ0 is the initial density of argon and ρi (i = 1, 2, 3, 4) is the compressed density from first to fourth shock, respectively. For the relative compression ratio (ηi’ = ρi/ρi-1), an interesting finding is that a turning point occurs at the second shocked states under the conditions of different experiments, and ηi’ increases with pressure in lower density regime and reversely decreases with pressure in higher density regime. The evolution of the compression ratio is controlled by the excitation of internal degrees of freedom, which increase the compression, and by the interaction effects between particles that reduce it. A temperature-density plot shows that current multishock compression states of argon have distributed into warm dense regime.

  11. Compression and Associated Properties of Boron Carbide

    Science.gov (United States)

    2008-12-01

    Klandadze, G.I., and Eristavi, A.M., 1999: IR- Active Phonons and Structure Elements of Isotope - Enriched Boron Carbide, J. Sol. State Chem. 154, 79- 86...COMPRESSION AND ASSOCIATED PROPERTIES OF BORON CARBIDE D. P. Dandekar*and J. A. Ciezak Army Research Laboratory, APG, MD 21005 M. Somayazulu...of the observed loss of shear strength in boron carbide under plane shock wave compression to amorphization in boron carbide under triaxial stress

  12. CANDU fuel compression tests at elevated temperatures

    International Nuclear Information System (INIS)

    Koehn, E.; Chan, J.K.; Langman, V.J.; Hadaller, G.I.; Fortman, R.A.

    1995-01-01

    An inlet header large break loss of coolant accident (LOCA) in CANDU reactors with fuelling against flow can cause the fuel to shift in the channels with a consequent reactivity insertion. This results in an increased fuel power transient, and a potential increase in the mialyzed consequences for such events. As the reactor's age and the channel axial gaps increase, the magnitude of the predicted power u-dmient increases. A design solution to reduce the power transient is to limit the amount of fuel movement by reducing the channel axial gap. This solution was implemented into Ontario Hydro's Bruce B and Darlington reactors. A consequence of a reduced channel axial gap is the potential for the fuel column axial expansion to become constrained by the channel end components in large break LOCAs. This experimental program investigated the effects of pellet cracking and elevated sheath temperatures on the ability of the fuel elements, of the 37-element bundle design, to sustain axial loads. The unirradiated fuel elements tested were either in the as-received condition or with the U0 2 fuel pellets cracked in a mechanical process to simulate the effect of inufflation. The load deformation characteristics demonstrated that, for a given amount of axial compression. the loads sustainable by the elements at elevated sheath temperatures were low. As a result. excess axial expansion would be easily accommodated without further challenge to pressure tube integrity. (author)

  13. Compressive properties of silica aerogel at 295, 76, and 20K

    International Nuclear Information System (INIS)

    Arvidson, J.M.; Scull, L.L.

    1986-01-01

    Specimens of silica aerogel were tested in compression at 295, 76, and 20 K in a helium gas environment. The properties reported include Young's modulus, the proportional limit, and yield strength. Compressive stress-versus-strain curves at these temperatures are also given. A test apparatus was developed specifically to determine the compressive properties of low strength materials. To measure specimen strain a concentric, overlapping-cylinder, capacitance extensometer was developed. This frictionless device has the capability to conduct variable temperature tests at any temperature from 1.8 to 295 K. Results from the compression tests indicate that at low temperatures the material is not only stronger, but tougher. During 295-K compression tests, the samples fractured and, in some cases, crumbled. After 76- or 20-K compression tests, the specimens remained intact

  14. Structure and Properties of Compressed Borate Glasses

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Bauer, U.; Behrens, H.

    While the influence of thermal history on the structure and properties of glasses has been thoroughly studied in the past century, the influence of pressure history has received considerably less attention. In this study, we investigate the pressure-induced changes in structure and properties...... in a series of borate glasses. Upon isostatic compression, NMR experiments show that the fraction of tetrahedral boron increases, leading to an overall decrease of the molar volume of the network. We correlate these structural changes with changes in elastic moduli from Brillouin scattering experiments......, hardness and crack formation from nanoindentation experiments, and overshoot in isobaric heat capacity from DSC experiments at ambient pressure. The influence of the initial boron speciation on the degree of changes in structure and properties will also be discussed....

  15. Dynamic High-Temperature Characterization of an Iridium Alloy in Compression at High Strain Rates

    Energy Technology Data Exchange (ETDEWEB)

    Song, Bo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Experimental Environment Simulation Dept.; Nelson, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Mechanics of Materials Dept.; Lipinski, Ronald J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Nuclear Fuel Cycle Technology Dept.; Bignell, John L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Structural and Thermal Analysis Dept.; Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program; George, E. P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program

    2014-06-01

    Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-temperature high-strain-rate performance are needed for understanding high-speed impacts in severe elevated-temperature environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain-rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. Current high-temperature Kolsky compression bar techniques are not capable of obtaining satisfactory high-temperature high-strain-rate stress-strain response of thin iridium specimens investigated in this study. We analyzed the difficulties encountered in high-temperature Kolsky compression bar testing of thin iridium alloy specimens. Appropriate modifications were made to the current high-temperature Kolsky compression bar technique to obtain reliable compressive stress-strain response of an iridium alloy at high strain rates (300 – 10000 s-1) and temperatures (750°C and 1030°C). Uncertainties in such high-temperature high-strain-rate experiments on thin iridium specimens were also analyzed. The compressive stress-strain response of the iridium alloy showed significant sensitivity to strain rate and temperature.

  16. Influence of Temperature on Compression, Impact Strength and ...

    African Journals Online (AJOL)

    Izod-type impact and compression tests were carried out on virgin and recycled unplasticized polyvinylchloride (uPVC) for different temperatures, T; from 25oC to 130oC at intervals of 15oC, to determine and compare their impact strength and axial compressive stress (σz)a, respectively. Appropriate formulae available in ...

  17. Effects of Elevated Temperature on Compressive Strength Of Concrete

    African Journals Online (AJOL)

    This study presents the results of investigation of the effects of elevated temperatures on the compressive strength of Grade 40 concrete. A total of thirty cube specimens were cast, cured in water at ambient temperature in the laboratory and subjected to various temperature regimes before testing. A concrete mix of 1:1:3 ...

  18. The Influence of Titanium Hydride Pretreatment on the Compressive Properties of Aluminum Foam

    OpenAIRE

    Zan ZHANG; Xingchuan XIA; Weimin ZHAO; Xiaowei CHEN; Xu CHEN

    2014-01-01

    Macrostructure has an important effect on the compressive properties of closed-cell aluminum foams. Meanwhile, the decomposition behavior of a foaming agent has a significant influence on the macrostructure of closed-cell aluminum foams. In order to get optimal compressive properties on aluminum foams, it is important to obtain the optimal decomposition behavior of a foaming agent. In this paper, different heat treatment temperatures and fixed heat treatment were employed to investigate the d...

  19. Temperature measurements of shock-compressed deuterium

    International Nuclear Information System (INIS)

    Holmes, N.C.; Ross, M.; Nellis, W.J.

    1994-11-01

    The authors measured the temperatures of single and double-shocked D 2 and H 2 up to 85 GPa (0.85 Mbar) and 5,200 K. While single shock temperatures, at pressures to 23 GPa, agree well with previous models, the double shock temperatures are as much as 40% lower than predicted. This is believed to be caused by molecular dissociation, and a new model of the hydrogen EOS at extreme conditions has been developed which correctly predicts their observations. These data and model have important implications for programs which use condensed-phase hydrogen in implosion systems

  20. Properties of compressible elastica from relativistic analogy.

    Science.gov (United States)

    Oshri, Oz; Diamant, Haim

    2016-01-21

    Kirchhoff's kinetic analogy relates the deformation of an incompressible elastic rod to the classical dynamics of rigid body rotation. We extend the analogy to compressible filaments and find that the extension is similar to the introduction of relativistic effects into the dynamical system. The extended analogy reveals a surprising symmetry in the deformations of compressible elastica. In addition, we use known results for the buckling of compressible elastica to derive the explicit solution for the motion of a relativistic nonlinear pendulum. We discuss cases where the extended Kirchhoff analogy may be useful for the study of other soft matter systems.

  1. Compressive properties of aluminum foams by gas injection method

    OpenAIRE

    Zhang Huiming; Chen Xiang; Fan Xueliu

    2012-01-01

    The compressive properties of aluminum foams by gas injection method are investigated under both quasi-static and dynamic compressive loads in this paper. The experimental results indicate that the deformation of the aluminum foams goes through three stages: elastic deforming, plastic deforming and densification stage, during both the quasi-static and dynamic compressions. The aluminum foams with small average cell size or low porosity have high yield strength. An increase in strain rate can ...

  2. Estimation of exit temperatures in the isentropic compression of real ...

    African Journals Online (AJOL)

    This paper presents the estimation of exit temperatures in the isentropic compression of real gases based on the Peng-Robinson equation of state and entropy balance method. The methods were applied to Ar, N2, CH4, CO2, C2H4 and C2H6. Data obtained revealed that isentropic exponent method provides useful results ...

  3. effect of elevated temperature on the compressive strength

    African Journals Online (AJOL)

    HOD

    Concrete materials in structures are usually exposed to high temperatures during fire. The relative ... replacement of cement with pulverized steel mill scale (PSMS) on the compressive strength of concrete cubes was ... Based on results of tests, partial replacement of cement with 10 % PSMS is recommended for use in.

  4. High temperature absorption compression heat pump for industrial waste heat

    DEFF Research Database (Denmark)

    Reinholdt, Lars; Horntvedt, B.; Nordtvedt, S. R.

    2016-01-01

    , the needed temperature levels often range from 100°C and up, but until now, it has been quite difficult to find heat pump technologies that reach this level, and thereby opening up the large-scale heat recovery in the industry. Absorption compression heat pumps can reach temperatures above 100°C...... higher than 82% by the better temperature match of the process to the heat sink and source is reported. Another major benefit of using ammonia and water as working pair is the possibility of reaching quite high temperatures at a significantly lower operating pressure, which makes it possible to reach...

  5. Rubber property: compression set induced by nuclear radiation

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    The methods cover the testing of vulcanized rubber parts that are to be assembled in such a manner that the rubber will remain subjected to compressive stresses or shear during continuous exposure to high energy radiation. Three methods are covered: compression set under constant load with measurements performed at or near the site of irradiation; compression set under constant deflection with measurements performed at or near the site of irradiation; compression set under constant deflection with measurements performed at a site remote from irradiation facility. Each method includes a discussion of the compression device, test specimens, procedure, calculation, and report. The compression set tests are intended to measure the ability of vulcanized rubber compounds to retain elastic properties during prolonged periods of static loading in a field of high energy radiation

  6. Influence of Temperature on Workability and Compressive Strength of Ordinary Concrete with High Calcium Fly Ash

    Directory of Open Access Journals (Sweden)

    Gołaszewski Jacek

    2017-06-01

    Full Text Available The rheological properties of fresh ordinary concrete are closely affected by temperature and time. The paper presents the study of consistency of fresh concrete mixtures made with Portland cement and cement with calcareous fly ash. Two types of admixtures were used. It was proven that the temperature has a clear effect on workability and compressive strength concrete. Influence on workability can be reduced by selecting the appropriate superplasticizer and cement.

  7. Compressive properties of sandwiches with functionally graded ...

    Indian Academy of Sciences (India)

    The compressive behaviour of a new class of sandwich composite made up of jute fiber reinforced epoxy skins and piece-wise linear fly ash reinforced functionally graded (FG) rubber core is investigated in flat-wise mode. FG samples are prepared using conventional casting technique. Presence of gradation is quantified ...

  8. Compression, Mechanical and Release Properties of Chloroquine ...

    African Journals Online (AJOL)

    Results: Tablet formulations containing trifoliate yam starch exhibited faster onset and higher amount of plastic deformation during compression than those containing corn starch. The crushing strength, disintegration and dissolution times of the tablets increased with binder concentration while friability values decreased.

  9. Compressive properties of sandwiches with functionally graded

    Indian Academy of Sciences (India)

    The compressive behaviour of a new class of sandwich composite made up of jute fiber reinforced epoxy skins and piece-wise linear fly ash reinforced functionally graded (FG) rubber core is investigated in flat-wise mode. FG samples are prepared using conventional casting technique. Presence of gradation is quantified ...

  10. Compression and associated properties of boron carbide

    Science.gov (United States)

    Ciezak, Jennifer; Dandekar, Dattatraya

    2009-06-01

    The observed loss of shear strength of boron carbide around 22 GPa has been attributed to presence of amorphous material in the shock recovered, and statically indented and pressurized boron carbide. The present work presents a more direct association of the observed loss of shear strength in boron carbide under plane shock wave compression to amorphization in boron carbide under triaxial stress compression. This evidence is obtained from in-situ measurement of Raman, and infrared vibrational spectra of boron carbide confined in a Diamond Anvil Cell (DAC) under hydrostatic and non-hydrostatic pressures. X-ray-diffraction measurements do show a shift in the compression of boron carbide around 27 GPa. However, X-ray diffraction measurements indicate that the amorphization does not extend to micron scale, as there is no evidence of a loss of crystallinity in the recorded diffraction pattern of boron carbide to 47 GPa. Our work shows that shear plays a very dominant role in the stress-induced amorphization of boron carbide.

  11. Applications of the IITRI compression test fixture at elevated temperature

    Science.gov (United States)

    Camarda, C. J.

    1979-01-01

    The purpose of the present paper is to describe an application of the IITRI compression test fixture at elevated temperature (589K) was described as well as the present compressive moduli and ultimate strains of HTS/PMR-15 graphite/polyimide material. Considerable care was taken in specimen fabrication to minimize back-to-back strain variations due to specimen bending. The effects of specimen width and temperature were studied for various laminate orientations. The IITRI specimen was analyzed using three dimensional finite elements to determine the magnitude and location of stress concentrations to assess their potential effects on measured moduli and ultimate strains. Stress concentrations are of concern since end constraints, free-edge effects, and thermal effects add to the three dimensional nature of stresses in a specimen.

  12. The compressive behaviour and constitutive equation of polyimide foam in wide strain rate and temperature

    Directory of Open Access Journals (Sweden)

    Yoshimoto Akifumi

    2015-01-01

    Full Text Available These days, polymer foams, such as polyurethane foam and polystyrene foam, are used in various situations as a thermal insulator or shock absorber. In general, however, their strength is insufficient in high temperature environments because of their low glass transition temperature. Polyimide is a polymer which has a higher glass transition temperature and high strength. Its mechanical properties do not vary greatly, even in low temperature environments. Therefore, polyimide foam is expected to be used in the aerospace industry. Thus, the constitutive equation of polyimide foam that can be applied across a wide range of strain rates and ambient temperature is very useful. In this study, a series of compression tests at various strain rates, from 10−3 to 103 s−1 were carried out in order to examine the effect of strain rate on the compressive properties of polyimide foam. The flow stress of polyimide foam increased rapidly at dynamic strain rates. The effect of ambient temperature on the properties of polyimide foam was also investigated at temperature from − 190 °C to 270°∘C. The flow stress decreased with increasing temperature.

  13. Effects of heating durations on normal concrete residual properties: compressive strength and mass loss

    Science.gov (United States)

    Nazri, Fadzli Mohamed; Shahidan, Shahiron; Khaida Baharuddin, Nur; Beddu, Salmia; Hisyam Abu Bakar, Badorul

    2017-11-01

    This study investigates the effects of high temperature with five different heating durations on residual properties of 30 MPa normal concrete. Concrete cubes were being heated up to 600°C for 30, 60, 90, 120 and 150 minutes. The temperature will keep constant for 30, 60, 90, 120 and 150 minutes. The standard temperature-time curve ISO 834 is referred to. After heating the specimen were left to cool in the furnace and removed. After cooling down to ambient temperature, the residual mass and residual compressive strength were observed. The obtained result shows that, the compressive strength of concrete decrease as the heating duration increases. This heating duration influence, might affects the loss of free water present and decomposition of hydration products in concrete. As the heating duration increases, the amount of water evaporated also increases led to loss in concrete mass. Conclusively, the percentage of mass and compressive strength loss increased as the heating duration increased.

  14. Characterization of Compressive Properties of Polymer Foam Materials Using DIC and a Modified Arcan Fixture

    DEFF Research Database (Denmark)

    Taher, Siavash Talebi; Thomsen, Ole Thybo; Dulieu-Barton, J. M.

    2013-01-01

    bidirectional loading conditions that are not possible with conventional Arcan fixtures. The MAF is attached to a standard universal test machine, equiped with an environmental chamber, using specially designed grips that do not constrain the specimen wrt. rotations, and hence reduces paristic effects due......A modified Arcan fixture (MAF) has been developed to characterize polymer foam materials with respect to their tensile, compressive, shear and bidirectional mechanical properties at room and at elevated temperatures. The MAF enables the realization of pure compression or high compression to shear......, a “correction factor” for the measured surface strain is determined using nonlinear finite element analysis (FEA). The paper will focus on the characterization of the compressive material properties including the MAF setup, test specimen design, experimental procedure and validated experimental results....

  15. Deterministic Differential Properties of the Compression Function of BMW

    DEFF Research Database (Denmark)

    Guo, Jian; Thomsen, Søren Steffen

    2011-01-01

    In this paper, we give some determinstic differential properties for the compression function of SHA-3 candidate Blue Midnight Wish (tweaked version for round 2). The computational complexity is about 20 compression function calls. This applies to security parameters 0/16, 1/15, and 2/14. The eff....../14. The efficient differentials can be used to find pseudo-preimages of the compression function with marginal gain over brute force. However, none of these attacks threaten the security of the BMW hash functions....

  16. Compressive behaviour at High Temperatures of Fibre Reinforced Concretes

    Directory of Open Access Journals (Sweden)

    S. O. Santos

    2009-01-01

    Full Text Available This paper summarizes the research that is being carried out at the Universities of Coimbra and Rio de Janeiro, on fibre reinforced concretes at high temperatures. Several high strength concrete compositions reinforced with fibres (polypropylene, steel and glass fibres were developed. The results of compressive tests at high temperatures (300 °C, 500 °C and 600 °C and after heating and cooling down of the concrete are presented in the paper. In both research studies, the results indicated that polypropylene fibers prevent concrete spalling. 

  17. Impact of thermodynamic properties and heat loss on ignition of transportation fuels in rapid compression machines

    KAUST Repository

    Ahmed, Ahfaz

    2018-01-30

    Rapid compression machines (RCM) are extensively used to study autoignition of a wide variety of fuels at engine relevant conditions. Fuels ranging from pure species to full boiling range gasoline and diesel can be studied in an RCM to develop a better understanding of autoignition kinetics in low to intermediate temperature ranges. In an RCM, autoignition is achieved by compressing a fuel/oxidizer mixture to higher pressure and temperature, thereby initiating chemical reactions promoting ignition. During these experiments, the pressure is continuously monitored and is used to deduce significant events such as the end of compression and the onset of ignition. The pressure profile is also used to assess the temperature evolution of the gas mixture with time using the adiabatic core hypothesis and the heat capacity ratio of the gas mixture. In such RCM studies, real transportation fuels containing many components are often represented by simpler surrogate fuels. While simpler surrogates such as primary reference fuels (PRFs) and ternary primary reference fuel (TPRFs) can match research and motor octane number of transportation fuels, they may not accurately replicate thermodynamic properties (including heat capacity ratio). This non-conformity could exhibit significant discrepancies in the end of compression temperature, thereby affecting ignition delay (τign) measurements. Another aspect of RCMs that can affect τign measurement is post compression heat loss, which depends on various RCM parameters including geometry, extent of insulation, pre-heating temperature etc. To, better understand the effects of these non-chemical kinetic parameters on τign, thermodynamic properties of a number of FACE G gasoline surrogates were calculated and simulated in a multi-zone RCM model. The problem was further investigated using a variance based analysis and individual sensitivities were calculated. This study highlights the effects on τign due to thermodynamic properties of

  18. Strength properties of interlocking compressed earth brick units

    Science.gov (United States)

    Saari, S.; Bakar, B. H. Abu; Surip, N. A.

    2017-10-01

    This study presents a laboratory investigation on the properties of interlocking compressed earth brick (ICEB) units. Compressive strength, which is one of the most important properties in masonry structures, is used to determine masonry performance. The compressive strength of the ICEB units was determined by applying a compressive strength test for 340 units from four types of ICEB. To analyze the strength of the ICEB units, each unit was capped by a steel plate at the top and bottom to create a flat surface, and then ICEB was loaded until failure. The average compressive strength of the corresponding ICEB units are as follows: wall brick, 19.15 N/mm2; beam brick, 16.99 N/mm2; column brick, 13.18 N/mm2; and half brick, 11.79 N/mm2. All the ICEB units had compressive strength of over 5 N/mm2, which is the minimum strength for a load-bearing brick. This study proves that ICEB units may be used as load-bearing bricks. The strength of ICEBs is equal to that of other common bricks and blocks that are currently available in the market.

  19. Compressive properties of aluminum foams by gas injection method

    Directory of Open Access Journals (Sweden)

    Zhang Huiming

    2012-08-01

    Full Text Available The compressive properties of aluminum foams by gas injection method are investigated under both quasi-static and dynamic compressive loads in this paper. The experimental results indicate that the deformation of the aluminum foams goes through three stages: elastic deforming, plastic deforming and densification stage, during both the quasi-static and dynamic compressions. The aluminum foams with small average cell size or low porosity have high yield strength. An increase in strain rate can lead to an increase of yield strength. The yield strength of the aluminum foams under the dynamic loading condition is much greater than that under the quasi-static loading condition. Dynamic compressive tests show that a higher strain rate can give rise to a higher energy absorption capacity, which demonstrates that the aluminum foams have remarkable strain rate sensitivity on the loading rate.

  20. Law - temperature material properties

    International Nuclear Information System (INIS)

    Van Sciver, S.W.

    1986-01-01

    This chapter is a survey of those properties which are of greatest importance to cryogenics. Included in the discussion are the behavior of the heat capacity, electrical and thermal conductivities, thermal contraction, and some special properties of materials--specifically magnetic spin systems and superconductors. Most of the descriptions are on the basis of thermodynamic or solid-state physics principles. Figures show Deybe specific heat and internal energy functions, and the Brillouin function for different total spin quantum numbers

  1. An investigation of the direct compression properties of pre ...

    African Journals Online (AJOL)

    Batches of acetylsalicylic acid granules and tablets were formulated with the native and pregelatinized forms of both the test and maize starches and microcrystalline cellulose at 5.0 and 10 %w/w by direct compression. Granules were evaluated for their flow properties and drug-excipient compatibility using DSC and FTIR ...

  2. Unfired clay bricks – moisture properties and compressive strength

    DEFF Research Database (Denmark)

    Hansen, E.J. de Place; Hansen, Kurt Kielsgaard

    2002-01-01

    Apparatus, methods and test results from an experimental investigation of (1) the properties for moisture performance of the materials, including water vapour sorption and water vapour transmission, (2) humidity buffering of the indoor climate by an absorbent material, and (3) the compressive...... strength are presented....

  3. Unfired clay bricks – moisture properties and compressive strength

    DEFF Research Database (Denmark)

    Hansen, E.J. de Place; Hansen, Kurt Kielsgaard

    2002-01-01

    Apparatus, methods and test results from an experimental investigation of (1) the properties for moisture performance of the materials, including water vapour sorption and water vapour transmission, (2) humidity buffering of the indoor climate by an absorbent material, and (3) the compressive str...

  4. Direct compression properties of microcrystalline cellulose and its ...

    African Journals Online (AJOL)

    The influence of silicified microcrystalline cellulose (SMCC) on the flow, compaction and tableting properties of metronidazole powder was investigated. The study compared medium grades of both SMCC and standard microcrystalline cellulose (MCC) as direct compressible excipients. The bulk densities, Hausner quotient ...

  5. Dynamic Uniaxial Compression of HSLA-65 Steel at Elevated Temperatures

    Science.gov (United States)

    Dike, Shweta; Wang, Tianxue; Zuanetti, Bryan; Prakash, Vikas

    2017-12-01

    In the present study, the dynamic response of a high-strength, low alloy Grade 65 (HSLA-65) steel, used by the United States Navy for ship hull construction, is investigated under dynamic uniaxial compression at temperatures ranging from room temperature to 1000 °C using a novel elevated temperature split-Hopkinson pressure bar. These experiments are designed to probe the dynamic response of HSLA-65 steel in its single α-ferrite phase, mixed α + γ-austenite phase, and the single γ-austenite phase, as a function of temperature. The investigation is conducted at two different average strain rates—1450 and 2100/s. The experimental results indicate that at test temperatures in the range from room temperature to lower than 600 °C, i.e. prior to the development of the mixed α + γ phase, a net softening in flow strength is observed at all levels of plastic strain with increase in test temperatures. As the test temperatures are increased, the rate of this strain softening with temperature is observed to decrease, and at 600 °C the trend reverses itself resulting in an increase in flow stress at all strains tested. This increase in flow stress is understood be due to dynamic strain aging, where solute atoms play a distinctive role in hindering dislocation motion. At 800 °C, a (sharp) drop in the flow stress, equivalent to one-half of its value at room temperature, is observed. As the test temperature are increased to 900 and 1000 °C, further drop in flow stress are observed at all plastic strain levels. In addition, strain hardening in flow stress is observed at all test temperatures up to 600 °C; beyond 800 °C the rate of strain hardening is observed to decrease, with strain softening becoming dominant at temperatures of 900 °C and higher. Moreover, comparing the high strain rate stress versus strain data gathered on HSLA 65 in the current investigation with those available in the literature at quasi-static strain rates, strain-rate hardening can be

  6. Thermodynamic properties of aqueous solutions with citrate ions. Compressibility studies in aqueous solutions of citric acid

    International Nuclear Information System (INIS)

    Apelblat, Alexander; Korin, Eli; Manzurola, Emanuel

    2013-01-01

    Highlights: • Over a wide range of concentrations and temperatures sound velocities were measured in aqueous solutions of citric acid. • Compressibility properties of citric acid solutions are thermodynamically characterized. • Changes in the structure of water when citric acid is dissolved are discussed. -- Abstract: Sound velocities in aqueous solutions of citric acid were measured from 15 °C to 50 °C in 5 °C intervals, within the 0.1 mol · kg −1 to 5.0 mol · kg −1 concentration range. These sound velocities served to evaluate the isentropic and isothermal compressibilities, the apparent molar compressibilities, the isochoric thermal pressure coefficients, changes of the cubic expansion coefficients with pressure at constant temperature, the changes of heat capacities with volume and hydration numbers of citric acid in aqueous solutions

  7. The effect of temperature on compressive and tensile strengths of commonly used luting cements: an in vitro study.

    Science.gov (United States)

    Patil, Suneel G; Sajjan, Mc Suresh; Patil, Rekha

    2015-02-01

    The luting cements must withstand masticatory and parafunctional stresses in the warm and wet oral environment. Mouth temperature and the temperature of the ingested foods may induce thermal variation and plastic deformation within the cements and might affect the strength properties. The objectives of this study were to evaluate the effect of temperature on the compressive and diametral tensile strengths of two polycarboxylate, a conventional glass ionomer and a resin modified glass ionomer luting cements and, to compare the compressive strength and the diametral tensile strength of the selected luting cements at varying temperatures. In this study, standardized specimens were prepared. The temperature of the specimens was regulated prior to testing them using a universal testing machine at a crosshead speed of 1 mm/min. Six specimens each were tested at 23°C, 37°C and 50°C for both the compressive and diametral tensile strengths, for all the luting cements. All the luting cements showed a marginal reduction in their compressive and diametral tensile strengths at raised temperatures. Fuji Plus was strongest in compression, followed by Fuji I > Poly F > Liv Carbo. Fuji Plus had the highest diametral tensile strength values, followed by Poly F = Fuji I = Liv Carbo, at all temperatures. An increase in the temperature caused no significant reduction in the compressive and diametral tensile strengths of the cements evaluated. The compressive strength of the luting cements differed significantly from one another at all temperatures. The diametral tensile strength of resin modified glass ionomers differed considerably from the other cements, whereas there was no significant difference between the other cements, at all the temperatures.

  8. Elevated-temperature application of the IITRI compression test fixture for graphite/polyimide filamentary composites

    Science.gov (United States)

    Raju, B. B.; Camarda, C. J.; Cooper, P. A.

    1979-01-01

    Seventy-nine graphite/polyimide compression specimens were tested to investigate experimentally the IITRI test method for determining compressive properties of composite materials at room and elevated temperatures (589 K (600 F)). Minor modifications were made to the standard IITRI fixture and a high degree of precision was maintained in specimen fabrication and load alignment. Specimens included four symmetric laminate orientations. Various widths were tested to evaluate the effect of width on measured modulus and strength. In most cases three specimens of each width were tested at room and elevated temperature and a polynomial regression analysis was used to reduce the data. Scatter of replicate tests and back-to-back strain variations were low, and no specimens failed by instability. Variation of specimen width had a negligible effect on the measured ultimate strengths and initial moduli of the specimens. Measured compressive strength and stiffness values were sufficiently high for the material to be considered a usable structural material at temperatures as high as 589 K (600 F).

  9. Recommended reference materials for realization of physicochemical properties pressure-volume-temperature relationships

    CERN Document Server

    Herington, E F G

    1977-01-01

    Recommended Reference Materials for Realization of Physicochemical Properties presents recommendations of reference materials for use in measurements involving physicochemical properties, namely, vapor pressure; liquid-vapor critical temperature and critical pressure; orthobaric volumes of liquid and vapor; pressure-volume-temperature properties of the unsaturated vapor or gas; and pressure-volume-temperature properties of the compressed liquid. This monograph focuses on reference materials for vapor pressures at temperatures up to 770 K, as well as critical temperatures and critical pressures

  10. Dynamic compressive properties of bovine knee layered tissue

    Directory of Open Access Journals (Sweden)

    Nishida Masahiro

    2015-01-01

    Full Text Available In Japan, the most common articular disease is knee osteoarthritis. Among many treatment methodologies, tissue engineering and regenerative medicine have recently received a lot of attention. In this field, cells and scaffolds are important, both ex vivo and in vivo. From the viewpoint of effective treatment, in addition to histological features, the compatibility of mechanical properties is also important. In this study, the dynamic and static compressive properties of bovine articular cartilage-cancellous bone layered tissue were measured using a universal testing machine and a split Hopkinson pressure bar method. The compressive behaviors of bovine articular cartilage-cancellous bone layered tissue were examined. The effects of strain rate on the maximum stress and the slope of stress-strain curves of the bovine articular cartilage-cancellous bone layered tissue were discussed.

  11. Elastic Modulus of Foamcrete in Compression and Bending at Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Md Azree Othuman Mydin

    2012-09-01

    Full Text Available This paper will presents the experimental results that have been performed to examine and characterize the mechanical properties of foamcrete at elevated temperatures. Foamcrete of 650 and 1000 kg/m 3 density were cast and tested under compression and bending. The tests were done at room temperature, 100, 200, 300, 400, 500, and 600°C. The results of this study consistently demonstrated that the loss in stiffness for cement based material like foamcrete at elevated temperatures occurs predominantly after about 95°C, regardless of density. This indicates that the primary mechanism causing stiffness degradation is microcracking, which occurs as water expands and evaporates from the porous body. As expected, reducing the density of LFC reduces its strength and stiffness. However, for LFC of different densities, the normalised strength-temperature and stiffnesstemperature relationships are very similar.

  12. The Influence of Titanium Hydride Pretreatment on the Compressive Properties of Aluminum Foam

    Directory of Open Access Journals (Sweden)

    Zan ZHANG

    2014-12-01

    Full Text Available Macrostructure has an important effect on the compressive properties of closed-cell aluminum foams. Meanwhile, the decomposition behavior of a foaming agent has a significant influence on the macrostructure of closed-cell aluminum foams. In order to get optimal compressive properties on aluminum foams, it is important to obtain the optimal decomposition behavior of a foaming agent. In this paper, different heat treatment temperatures and fixed heat treatment were employed to investigate the decomposition behavior of titanium hydride. For a more intuitive understanding of their decomposition characteristics of the pretreated titanium hydrides, closed-cell commercially pure Al foams were prepared by melt foaming method using different types of pretreated titanium hydrides as foaming agent. In addition, the macrostructures and quasi-static compressive properties were used to evaluate the pretreatment effect. The results showed that pretreatments have a significant influence on the macrostructure and compressive properties of aluminum foams. The decomposition characteristics of titanium hydride pretreated at 753 K for 30 min are most suitable for the preparation of closed-cell aluminum foams under present conditions, as the foams possess good combination of pore size distribution, yield strength and energy absorption capacity. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6082

  13. Investigation of ammonia/water hybrid absorption/compression heat pumps for heat supply temperatures above 100 °C

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Reinholdt, Lars; Markussen, Wiebke Brix

    2014-01-01

    The hybrid absorption/compression heat pump (HACHP) using ammonia-water as working fluid is a promising technology for development of a high temperature industrial heat pump. This is due to two properties inherent to the use of zeotropic mixtures: non-isothermal phase change and reduced vapour...

  14. Material Properties at Low Temperature

    CERN Document Server

    Duthil, P

    2014-07-17

    From ambient down to cryogenic temperatures, the behaviour of materials changes greatly. Mechanisms leading to variations in electrical, thermal, mechanical, and magnetic properties in pure metals, alloys, and insulators are briefly introduced from a general engineering standpoint. Data sets are provided for materials commonly used in cryogenic systems for design purposes.

  15. Mechanical properties of tannin-based rigid foams undergoing compression

    Energy Technology Data Exchange (ETDEWEB)

    Celzard, A., E-mail: Alain.Celzard@enstib.uhp-nancy.fr [Institut Jean Lamour - UMR CNRS 7198, CNRS - Nancy-Universite - UPV-Metz, Departement Chimie et Physique des Solides et des Surfaces, ENSTIB, 27 rue du Merle Blanc, BP 1041, 88051 Epinal cedex 9 (France); Zhao, W. [Institut Jean Lamour - UMR CNRS 7198, CNRS - Nancy-Universite - UPV-Metz, Departement Chimie et Physique des Solides et des Surfaces, ENSTIB, 27 rue du Merle Blanc, BP 1041, 88051 Epinal cedex 9 (France); Pizzi, A. [ENSTIB-LERMAB, Nancy-University, 27 rue du Merle Blanc, BP 1041, 88051 Epinal cedex 9 (France); Fierro, V. [Institut Jean Lamour - UMR CNRS 7198, CNRS - Nancy-Universite - UPV-Metz, Departement Chimie et Physique des Solides et des Surfaces, ENSTIB, 27 rue du Merle Blanc, BP 1041, 88051 Epinal cedex 9 (France)

    2010-06-25

    The mechanical properties of a new class of extremely lightweight tannin-based materials, namely organic foams and their carbonaceous counterparts are detailed. Scaling laws are shown to describe correctly the observed behaviour. Information about the mechanical characteristics of the elementary forces acting within these solids is derived. It is suggested that organic materials present a rather bending-dominated behaviour and are partly plastic. On the contrary, carbon foams obtained by pyrolysis of the former present a fracture-dominated behaviour and are purely brittle. These conclusions are supported by the differences in the exponent describing the change of Young's modulus as a function of relative density, while that describing compressive strength is unchanged. Features of the densification strain also support such conclusions. Carbon foams of very low density may absorb high energy when compressed, making them valuable materials for crash protection.

  16. Hyperelastic Material Properties of Mouse Skin under Compression.

    Directory of Open Access Journals (Sweden)

    Yuxiang Wang

    Full Text Available The skin is a dynamic organ whose complex material properties are capable of withstanding continuous mechanical stress while accommodating insults and organism growth. Moreover, synchronized hair cycles, comprising waves of hair growth, regression and rest, are accompanied by dramatic fluctuations in skin thickness in mice. Whether such structural changes alter skin mechanics is unknown. Mouse models are extensively used to study skin biology and pathophysiology, including aging, UV-induced skin damage and somatosensory signaling. As the skin serves a pivotal role in the transfer function from sensory stimuli to neuronal signaling, we sought to define the mechanical properties of mouse skin over a range of normal physiological states. Skin thickness, stiffness and modulus were quantitatively surveyed in adult, female mice (Mus musculus. These measures were analyzed under uniaxial compression, which is relevant for touch reception and compression injuries, rather than tension, which is typically used to analyze skin mechanics. Compression tests were performed with 105 full-thickness, freshly isolated specimens from the hairy skin of the hind limb. Physiological variables included body weight, hair-cycle stage, maturity level, skin site and individual animal differences. Skin thickness and stiffness were dominated by hair-cycle stage at young (6-10 weeks and intermediate (13-19 weeks adult ages but by body weight in mature mice (26-34 weeks. Interestingly, stiffness varied inversely with thickness so that hyperelastic modulus was consistent across hair-cycle stages and body weights. By contrast, the mechanics of hairy skin differs markedly with anatomical location. In particular, skin containing fascial structures such as nerves and blood vessels showed significantly greater modulus than adjacent sites. Collectively, this systematic survey indicates that, although its structure changes dramatically throughout adult life, mouse skin at a given

  17. Experimental study on compression property of regolith analogues

    Science.gov (United States)

    Omura, Tomomi; Nakamura, Akiko M.

    2017-12-01

    The compression property of regolith reflects the strength and porosity of the regolith layer on small bodies and their variations in the layer that largely influence the collisional and thermal evolution of the bodies. We conducted compression experiments and investigated the relationship between the porosity and the compression using fluffy granular samples. We focused on a low-pressure and high-porosity regime. We used tens of μm-sized irregular and spherical powders as analogs of porous regolith. The initial porosity of the samples ranged from 0.80 to 0.53. The uniaxial pressure applied to the samples lays in the range from 30 to 4 × 105 Pa. The porosity of the samples remained at their initial values below a threshold pressure and then decreased when the pressure exceeded the threshold. We defined this uniaxial pressure at the threshold as "yield strength". The yield strength increased as the initial porosity of a sample decreased. The yield strengths of samples consisting of irregular particles did not significantly depend on their size distributions when the samples had the same initial porosity. We compared the results of our experiments with a previously proposed theoretical model. We calculated the average interparticle force acting on contact points of constituent particles under the uniaxial pressure of yield strength using the theoretical model and compared it with theoretically estimated forces required to roll or slide the particles. The calculated interparticle force was larger than the rolling friction force and smaller than the sliding friction force. The yield strength of regolith may be constrained by these forces. Our results may be useful for planetary scientists to estimate the depth above which the porosity of a regolith layer is almost equal to that of the regolith surface and to interpret the compression property of an asteroid surface obtained by a lander.

  18. Compressive mechanical of high strength concrete (HSC) after different high temperature history

    Science.gov (United States)

    Zhao, Dongfu; Liu, Yuchen; Gao, Haijing; Han, Xiao

    2017-08-01

    The compression strength test of high strength concrete under different high-temperature conditions was carried out by universal testing machine. The friction surface of the pressure bearing surface of the specimen was composed of three layers of plastic film and glycerol. The high temperature working conditions were the combination of different heating temperature and different constant temperature time. The characteristics of failure modes and the developments of cracks were observed; the residual compressive strength and stress-strain curves were measured; the effect of different temperature and heating time on the strength and deformation of high strength concrete under uniaxial compression were analyzed; the failure criterion formula of the high strength concrete after high temperature under uniaxial compression was established. The formula of the residual compressive strength of high strength concrete under the influence of heating temperature and constant temperature time was put forward. The relationship between the residual elastic modulus and the peak strain and residual compressive strength of high strength concrete and different high temperature conditions is established. The quantitative relationship that the residual compressive strength decreases the residual elastic modulus decreases and the peak strain increases with the increase of heating temperature and the constant temperature time was given, which provides a reference for the detection and evaluation of high strength concrete structures after fire.

  19. Effect of evaporator temperature on vapor compression refrigeration system

    Directory of Open Access Journals (Sweden)

    Abdullah A.A.A. Al-Rashed

    2011-12-01

    Full Text Available This paper presents a comparable evaluation of R600a (isobutane, R290 (propane, R134a, R22, for R410A, and R32 an optimized finned-tube evaporator, and analyzes the evaporator effect on the system coefficient of performance (COP. Results concerning the response of a refrigeration system simulation software to an increase in the amount of oil flowing with the refrigerant are presented. It is shown that there is optima of the apparent overheat value, for which either the exchanged heat or the refrigeration coefficient of performance (COP is maximized: consequently, it is not possible to optimize both the refrigeration COP and the evaporator effect. The obtained evaporator optimization results were incorporated in a conventional analysis of the vapor compression system. For a theoretical cycle analysis without accounting for evaporator effects, the COP spread for the studied refrigerants was as high as 11.7%. For cycle simulations including evaporator effects, the COP of R290 was better than that of R22 by up to 3.5%, while the remaining refrigerants performed approximately within a 2% COP band of the R22 baseline for the two condensing temperatures considered.

  20. Impact of compression on gas transport in non-woven gas diffusion layers of high temperature polymer electrolyte fuel cells

    Science.gov (United States)

    Froning, Dieter; Yu, Junliang; Gaiselmann, Gerd; Reimer, Uwe; Manke, Ingo; Schmidt, Volker; Lehnert, Werner

    2016-06-01

    Gas transport in non-woven gas diffusion layers of a high-temperature polymer electrolyte fuel cell was calculated with the Lattice Boltzmann method. The underlying micro structure was taken from two sources. A real micro structure was analyzed in the synchrotron under the impact of a compression mask mimicking the channel/rib structure of a flow field. Furthermore a stochastic geometry model based on synchrotron X-ray tomography studies was applied. The effect of compression is included in the stochastic model. Gas transport in these micro structures was simulated and the impact of compression was analyzed. Fiber bundles overlaying the micro structure were identified which affect the homogeneity of the gas flow. There are significant deviations between the impact of compression on effective material properties for this type of gas diffusion layers and the Kozeny-Carman equation.

  1. Optical properties of highly compressed polystyrene: An ab initio study

    Science.gov (United States)

    Hu, S. X.; Collins, L. A.; Colgan, J. P.; Goncharov, V. N.; Kilcrease, D. P.

    2017-10-01

    Using all-electron density functional theory, we have performed an ab initio study on x-ray absorption spectra of highly compressed polystyrene (CH). We found that the K -edge shifts in strongly coupled, degenerate polystyrene cannot be explained by existing continuum-lowering models adopted in traditional plasma physics. To gain insights into the K -edge shift in warm, dense CH, we have developed a model designated as "single mixture in a box" (SMIAB), which incorporates both the lowering of the continuum and the rising of the Fermi surface resulting from high compression. This simple SMIAB model correctly predicts the K -edge shift of carbon in highly compressed CH in good agreement with results from quantum molecular dynamics (QMD) calculations. Traditional opacity models failed to give the proper K -edge shifts as the CH density increased. Based on QMD calculations, we have established a first-principles opacity table (FPOT) for CH in a wide range of densities and temperatures [ρ =0.1 -100 g /c m3 and T =2000 -1 000 000 K ]. The FPOT gives much higher Rosseland mean opacity compared to the cold-opacity-patched astrophysics opacity table for warm, dense CH and favorably compares to the newly improved Los Alamos atomic model for moderately compressed CH (ρCH≤10 g /c m3 ), but remains a factor of 2 to 3 higher at extremely high densities (ρCH≥50 g /c m3 ). We anticipate the established FPOT of CH will find important applications to reliable designs of high-energy-density experiments. Moreover, the understanding of K -edge shifting revealed in this study could provide guides for improving the traditional opacity models to properly handle the strongly coupled and degenerate conditions.

  2. Influence of Compacting Rate on the Properties of Compressed Earth Blocks

    Directory of Open Access Journals (Sweden)

    Humphrey Danso

    2016-01-01

    Full Text Available Compaction of blocks contributes significantly to the strength properties of compressed earth blocks. This paper investigates the influence of compacting rates on the properties of compressed earth blocks. Experiments were conducted to determine the density, compressive strength, splitting tensile strength, and erosion properties of compressed earth blocks produced with different rates of compacting speed. The study concludes that although the low rate of compaction achieved slightly better performance characteristics, there is no statistically significant difference between the soil blocks produced with low compacting rate and high compacting rate. The study demonstrates that there is not much influence on the properties of compressed earth blocks produced with low and high compacting rates. It was further found that there are strong linear correlations between the compressive strength test and density, and density and the erosion. However, a weak linear correlation was found between tensile strength and compressive strength, and tensile strength and density.

  3. Temperature Effect on Mechanical Properties and Damage Identification of Concrete Structure

    Directory of Open Access Journals (Sweden)

    Yubo Jiao

    2014-01-01

    Full Text Available Static and dynamic mechanical properties of concrete are affected by temperature effect in practice. Therefore, it is necessary to investigate the corresponding influence law and mechanism. This paper demonstrates the variation of mechanical properties of concrete at temperatures from −20°C to 60°C. Temperature effects on cube compressive strength, splitting tensile strength, prism compressive strength, modulus of elasticity, and frequency are conducted and discussed. The results indicate that static mechanical properties such as compressive strength (cube and prism, splitting tensile strength, and modulus of elasticity have highly linear negative correlation with temperature; this law is also applied to the first order frequency of concrete slab. The coupling effect of temperature and damage on change rate of frequency reveals that temperature effect cannot be ignored in damage identification of structure. Mechanism analysis shows that variation of elastic modulus of concrete caused by temperature is the primary reason for the change of frequency.

  4. Structure and Compressive Properties of Invar-Cenosphere Syntactic Foams

    Directory of Open Access Journals (Sweden)

    Dung Luong

    2016-02-01

    Full Text Available The present study investigates the mechanical performance of syntactic foams produced by means of the metal powder injection molding process having an Invar (FeNi36 matrix and including cenospheres as hollow particles at weight fractions (wt.% of 5 and 10, respectively, corresponding to approximately 41.6 and 60.0 vol.% in relation to the metal content and at 0.6 g/cm3 hollow particle density. The synthesis process results in survival of cenospheres and provides low density syntactic foams. The microstructure of the materials is investigated as well as the mechanical performance under quasi-static and high strain rate compressive loads. The compressive stress-strain curves of syntactic foams reveal a continuous strain hardening behavior in the plastic region, followed by a densification region. The results reveal a strain rate sensitivity in cenosphere-based Invar matrix syntactic foams. Differences in properties between cenosphere- and glass microsphere-based materials are discussed in relation to the findings of microstructural investigations. Cenospheres present a viable choice as filler material in iron-based syntactic foams due to their higher thermal stability compared to glass microspheres.

  5. Structure and Compressive Properties of Invar-Cenosphere Syntactic Foams.

    Science.gov (United States)

    Luong, Dung; Lehmhus, Dirk; Gupta, Nikhil; Weise, Joerg; Bayoumi, Mohamed

    2016-02-18

    The present study investigates the mechanical performance of syntactic foams produced by means of the metal powder injection molding process having an Invar (FeNi36) matrix and including cenospheres as hollow particles at weight fractions (wt.%) of 5 and 10, respectively, corresponding to approximately 41.6 and 60.0 vol.% in relation to the metal content and at 0.6 g/cm³ hollow particle density. The synthesis process results in survival of cenospheres and provides low density syntactic foams. The microstructure of the materials is investigated as well as the mechanical performance under quasi-static and high strain rate compressive loads. The compressive stress-strain curves of syntactic foams reveal a continuous strain hardening behavior in the plastic region, followed by a densification region. The results reveal a strain rate sensitivity in cenosphere-based Invar matrix syntactic foams. Differences in properties between cenosphere- and glass microsphere-based materials are discussed in relation to the findings of microstructural investigations. Cenospheres present a viable choice as filler material in iron-based syntactic foams due to their higher thermal stability compared to glass microspheres.

  6. Elevated Temperature, Residual Compressive Strength of Impact-Damaged Sandwich Structure Manufactured Out-of-Autoclave

    Science.gov (United States)

    Grimsley, Brian W.; Sutter, James K.; Burke, Eric R.; Dixon, Genevieve D.; Gyekenyesi, Thomas G.; Smeltzer, Stanley S.

    2012-01-01

    Several 1/16th-scale curved sandwich composite panel sections of a 10 m diameter barrel were fabricated to demonstrate the manufacturability of large-scale curved sections using minimum gauge, [+60/-60/0]s, toughened epoxy composite facesheets co-cured with low density (50 kilograms per cubic meters) aluminum honeycomb core. One of these panels was fabricated out of autoclave (OoA) by the vacuum bag oven (VBO) process using Cycom(Registered Trademark) T40-800b/5320-1 prepreg system while another panel with the same lay-up and dimensions was fabricated using the autoclave-cure, toughened epoxy prepreg system Cycom(Registered Trademark) IM7/977-3. The resulting 2.44 m x 2 m curved panels were investigated by non-destructive evaluation (NDE) at NASA Langley Research Center (NASA LaRC) to determine initial fabrication quality and then cut into smaller coupons for elevated temperature wet (ETW) mechanical property characterization. Mechanical property characterization of the sandwich coupons was conducted including edge-wise compression (EWC), and compression-after-impact (CAI) at conditions ranging from 25 C/dry to 150 C/wet. The details and results of this characterization effort are presented in this paper.

  7. Strength properties of concrete at elevated temperatures

    International Nuclear Information System (INIS)

    Freskakis, G.N.; Burrow, R.C.; Debbas, E.B.

    1979-01-01

    A study is presented concerning the compressive strength, modulus of elasticity, and stress-strain relationships of concrete at elevated temperatures. A review of published results provides information for the development of upper and lower bound relationships for compressive strength and the modulus of elasticity and establishes exposure conditions for a lower bound thermal response. The relationships developed from the literature review are confirmed by the results of a verification test program. The strength and elasticity relationships provide a basis for the development of design stress-strain curves for concrete exposed to elevated temperatures

  8. Tensile and compressive properties of fresh human carotid atherosclerotic plaques.

    LENUS (Irish Health Repository)

    Maher, Eoghan

    2009-12-11

    Accurate characterisation of the mechanical properties of human atherosclerotic plaque is important for our understanding of the role of vascular mechanics in the development and treatment of atherosclerosis. The majority of previous studies investigating the mechanical properties of human plaque are based on tests of plaque tissue removed following autopsy. This study aims to characterise the mechanical behaviour of fresh human carotid plaques removed during endarterectomy and tested within 2h. A total of 50 radial compressive and 17 circumferential tensile uniaxial tests were performed on samples taken from 14 carotid plaques. The clinical classification of each plaque, as determined by duplex ultrasound is also reported. Plaques were classified as calcified, mixed or echolucent. Experimental data indicated that plaques were highly inhomogeneous; with variations seen in the mechanical properties of plaque obtained from individual donors and between donors. The mean behaviour of samples for each classification indicated that calcified plaques had the stiffest response, while echolucent plaques were the least stiff. Results also indicated that there may be a difference in behaviour of samples taken from different anatomical locations (common, internal and external carotid), however the large variability indicates that more testing is needed to reach significant conclusions. This work represents a step towards a better understanding of the in vivo mechanical behaviour of human atherosclerotic plaque.

  9. A measurement method for piezoelectric material properties under longitudinal compressive stress–-a compression test method for thin piezoelectric materials

    International Nuclear Information System (INIS)

    Kang, Lae-Hyong; Lee, Dae-Oen; Han, Jae-Hung

    2011-01-01

    We introduce a new compression test method for piezoelectric materials to investigate changes in piezoelectric properties under the compressive stress condition. Until now, compression tests of piezoelectric materials have been generally conducted using bulky piezoelectric ceramics and pressure block. The conventional method using the pressure block for thin piezoelectric patches, which are used in unimorph or bimorph actuators, is prone to unwanted bending and buckling. In addition, due to the constrained boundaries at both ends, the observed piezoelectric behavior contains boundary effects. In order to avoid these problems, the proposed method employs two guide plates with initial longitudinal tensile stress. By removing the tensile stress after bonding a piezoelectric material between the guide layers, longitudinal compressive stress is induced in the piezoelectric layer. Using the compression test specimens, two important properties, which govern the actuation performance of the piezoelectric material, the piezoelectric strain coefficients and the elastic modulus, are measured to evaluate the effects of applied electric fields and re-poling. The results show that the piezoelectric strain coefficient d 31 increases and the elastic modulus decreases when high voltage is applied to PZT5A, and the compression in the longitudinal direction decreases the piezoelectric strain coefficient d 31 but does not affect the elastic modulus. We also found that the re-poling of the piezoelectric material increases the elastic modulus, but the piezoelectric strain coefficient d 31 is not changed much (slightly increased) by re-poling

  10. Shock absorbing properties of toroidal shells under compression, 3

    International Nuclear Information System (INIS)

    Sugita, Yuji

    1985-01-01

    The author has previously presented the static load-deflection relations of a toroidal shell subjected to axisymmetric compression between rigid plates and those of its outer half when subjected to lateral compression. In both these cases, the analytical method was based on the incremental Rayleigh-Ritz method. In this paper, the effects of compression angle and strain rate on the load-deflection relations of the toroidal shell are investigated for its use as a shock absorber for the radioactive material shipping cask which must keep its structural integrity even after accidental falls at any angle. Static compression tests have been carried out at four angles of compression, 10 0 , 20 0 , 50 0 , 90 0 and the applications of the preceding analytical method have been discussed. Dynamic compression tests have also been performed using the free-falling drop hammer. The results are compared with those in the static compression tests. (author)

  11. Effect of Kollidon VA®64 particle size and morphology as directly compressible excipient on tablet compression properties.

    Science.gov (United States)

    Chaudhary, R S; Patel, C; Sevak, V; Chan, M

    2018-01-01

    The study evaluates use of Kollidon VA ® 64 and a combination of Kollidon VA ® 64 with Kollidon VA ® 64 Fine as excipient in direct compression process of tablets. The combination of the two grades of material is evaluated for capping, lamination and excessive friability. Inter particulate void space is higher for such excipient due to the hollow structure of the Kollidon VA ® 64 particles. During tablet compression air remains trapped in the blend exhibiting poor compression with compromised physical properties of the tablets. Composition of Kollidon VA ® 64 and Kollidon VA ® 64 Fine is evaluated by design of experiment (DoE). A scanning electron microscopy (SEM) of two grades of Kollidon VA ® 64 exhibits morphological differences between coarse and fine grade. The tablet compression process is evaluated with a mix consisting of entirely Kollidon VA ® 64 and two mixes containing Kollidon VA ® 64 and Kollidon VA ® 64 Fine in ratio of 77:23 and 65:35. A statistical modeling on the results from the DoE trials resulted in the optimum composition for direct tablet compression as combination of Kollidon VA ® 64 and Kollidon VA ® 64 Fine in ratio of 77:23. This combination compressed with the predicted parameters based on the statistical modeling and applying main compression force between 5 and 15 kN, pre-compression force between 2 and 3 kN, feeder speed fixed at 25 rpm and compression range of 45-49 rpm produced tablets with hardness ranging between 19 and 21 kp, with no friability, capping, or lamination issue.

  12. FEM Modeling of the Relationship between the High-Temperature Hardness and High-Temperature, Quasi-Static Compression Experiment.

    Science.gov (United States)

    Zhang, Tao; Jiang, Feng; Yan, Lan; Xu, Xipeng

    2017-12-26

    The high-temperature hardness test has a wide range of applications, but lacks test standards. The purpose of this study is to develop a finite element method (FEM) model of the relationship between the high-temperature hardness and high-temperature, quasi-static compression experiment, which is a mature test technology with test standards. A high-temperature, quasi-static compression test and a high-temperature hardness test were carried out. The relationship between the high-temperature, quasi-static compression test results and the high-temperature hardness test results was built by the development of a high-temperature indentation finite element (FE) simulation. The simulated and experimental results of high-temperature hardness have been compared, verifying the accuracy of the high-temperature indentation FE simulation.The simulated results show that the high temperature hardness basically does not change with the change of load when the pile-up of material during indentation is ignored. The simulated and experimental results show that the decrease in hardness and thermal softening are consistent. The strain and stress of indentation were analyzed from the simulated contour. It was found that the strain increases with the increase of the test temperature, and the stress decreases with the increase of the test temperature.

  13. FEM Modeling of the Relationship between the High-Temperature Hardness and High-Temperature, Quasi-Static Compression Experiment

    Directory of Open Access Journals (Sweden)

    Tao Zhang

    2017-12-01

    Full Text Available The high-temperature hardness test has a wide range of applications, but lacks test standards. The purpose of this study is to develop a finite element method (FEM model of the relationship between the high-temperature hardness and high-temperature, quasi-static compression experiment, which is a mature test technology with test standards. A high-temperature, quasi-static compression test and a high-temperature hardness test were carried out. The relationship between the high-temperature, quasi-static compression test results and the high-temperature hardness test results was built by the development of a high-temperature indentation finite element (FE simulation. The simulated and experimental results of high-temperature hardness have been compared, verifying the accuracy of the high-temperature indentation FE simulation.The simulated results show that the high temperature hardness basically does not change with the change of load when the pile-up of material during indentation is ignored. The simulated and experimental results show that the decrease in hardness and thermal softening are consistent. The strain and stress of indentation were analyzed from the simulated contour. It was found that the strain increases with the increase of the test temperature, and the stress decreases with the increase of the test temperature.

  14. Effect of warm compress application on tissue temperature in healthy dogs.

    Science.gov (United States)

    Millard, Ralph P; Towle-Millard, Heather A; Rankin, David C; Roush, James K

    2013-03-01

    To measure the effect of warm compress application on tissue temperature in healthy dogs. 10 healthy mixed-breed dogs. Dogs were sedated with hydromorphone (0.1 mg/kg, IV) and diazepam (0.25 mg/kg, IV). Three 24-gauge thermocouple needles were inserted to a depth of 0.5 cm (superficial), 1.0 cm (middle), and 1.5 cm (deep) into a shaved, lumbar, epaxial region to measure tissue temperature. Warm (47°C) compresses were applied with gravity dependence for periods of 5, 10, and 20 minutes. Tissue temperature was recorded before compress application and at intervals for up to 80 minutes after application. Control data were collected while dogs received identical sedation but with no warm compress. Mean temperature associated with 5 minutes of heat application at the superficial, middle, and deep depths was significantly increased, compared with the control temperature. Application for 10 minutes significantly increased the temperature at all depths, compared with 5 minutes of application. Mean temperature associated with 20 minutes of application was not different at the superficial or middle depths, compared with 10 minutes of application. Temperature at the deep depth associated with 10 minutes of application was significantly higher, compared with 20 minutes of application, but all temperature increases at this depth were minimal. Results suggested that application of a warm compress should be performed for 10 minutes. Changes in temperature at a tissue depth of 1.5 cm were minimal or not detected. The optimal compress temperature to achieve therapeutic benefits was not determined.

  15. Degradation of fish gelatin using hot-compressed water and the properties of the degradation products

    Science.gov (United States)

    Ueno, Shigeaki; Ichinoi, Hirokazu; Zhao, Jiahui; Fujii, Tomoyuki

    2015-04-01

    The degradation of fish gelatin using hot-compressed water was investigated. The hot-compressed water treatment resulted in the degradation of fish gelatin into peptides, and the number of the peptides increased with increasing the temperature. The distribution of amino acids in the product mixture indicated that hot-compressed water treatment at 240°C resulted in a high level of amino acid degradation, and the highest concentrations of free amino acids was at 220°C. Lysinoalanine, which is toxic, was rarely generated by hot-compressed water treatment at higher temperature range. Additionally, the optimum temperature for the hot-compressed water treatment with respect to the angiotensin I-converting enzyme inhibitory was at 180°C. These analyses demonstrate that the degradation of fish gelatin with hot-compressed water could be used to generate functional materials.

  16. In vitro degradation kinetics of pure PLA and Mg/PLA composite: Effects of immersion temperature and compression stress.

    Science.gov (United States)

    Li, Xuan; Chu, Chenglin; Wei, Yalin; Qi, Chenxi; Bai, Jing; Guo, Chao; Xue, Feng; Lin, Pinghua; Chu, Paul K

    2017-01-15

    The effects of the immersion temperature and compression stress on the in vitro degradation behavior of pure poly-lactic acid (pure-PLA) and PLA-based composite unidirectionally reinforced with micro-arc oxidized magnesium alloy wires (Mg/PLA or MAO-MAWs/PLA) are investigated. The degradation kinetics of pure-PLA and the PLA matrix in MAO-MAWs/PLA exhibit an Arrhenius-type behavior. For the composite, the synergic degradation of MAO-MAWs maintains a steady pH and mitigates the degradation of PLA matrix during immersion. However, the external compression stress decreases the activation energy (E a ) and pre-exponential factor (k 0 ) consequently increasing the degradation rate of PLA. Under a compression stress of 1MPa, E a and k 0 of pure PLA are 57.54kJ/mol and 9.74×10 7 day -1 , respectively, but 65.5kJ/mol and 9.81×10 8 day -1 for the PLA matrix in the composite. Accelerated tests are conducted in rising immersion temperature in order to shorten the experimental time. Our analysis indicates there are well-defined relationships between the bending strength of the specimens and the PLA molecular weight during immersion, which are independent of the degradation temperature and external compression stress. Finally, a numerical model is established to elucidate the relationship of bending strength, the PLA molecular weight, activation energy, immersion time and temperature. We systematically evaluate the effects of compression stress and temperature on the degradation properties of two materials: (pure-PLA) and MAO-MAWs/PLA (or Mg/PLA). The initial in vitro degradation kinetics of the unstressed or stressed pure-PLA and MAO-MAWs/PLA composite is confirmed to be Arrhenius-like. MAO-MAWs and external compression stress would influence the degradation activation energy (E a ) and pre-exponential factor (k 0 ) of PLA, and we noticed there is a linear relationship between E a and ln k 0 . Thereafter, we noticed that Mg 2+ , not H + , plays a significant role on the

  17. Fatigue Properties of Plain Concrete under Triaxial Tension-Compression-Compression Cyclic Loading

    Directory of Open Access Journals (Sweden)

    Dongfu Zhao

    2017-01-01

    Full Text Available Fatigue tests were performed on plain concrete under triaxial tension-compression-compression (T-C-C cyclic loading with constant and variable amplitude using a large multiaxial machine. Experimental results show that, under constant amplitude fatigue loads, the development of residual strain in the fatigue loading direction depends mostly on the lateral compressive stress ratio and is nearly independent of stress level. Under variable amplitude fatigue loads, the fatigue residual strain is related to the relative fatigue cycle and lateral compressive stress ratio but has little relationship with the loading process. To model this system, the relative residual strain was defined as the damage variant. Damage evolutions for plain concrete were established. In addition, fatigue damage analysis and predictions of fatigue remaining life were conducted. This work provides a reference for multistage fatigue testing and fatigue damage evaluation of plain concrete under multiaxial loads.

  18. Mechanical vapor compression refrigeration for low temperature industrial applications today

    International Nuclear Information System (INIS)

    Ferguson, J.E.

    1987-01-01

    If the super conductor industry settles out at a temperature of -100 0 F or above, mechanical refrigeration will be vying for the cooling business. Today there very definitely is a break point in the application of equipment at approximately -120 0 F or 189 0 K. Other technologies are generally utilized below this level. However, with market potential comes invention and breakthroughs in refrigeration can also occur. Today standard refrigeration systems are cost effective, reliable and produced in the millions for high temperature applications of +10 0 F to +40 0 F evaporator temperature. Lower temperatures require additional hardware, consume additional power and are produced today in limited quantities for special applications

  19. Adaptive compressed sensing recovery utilizing the property of signal's autocorrelations.

    Science.gov (United States)

    Fu, Changjun; Ji, Xiangyang; Dai, Qionghai

    2012-05-01

    Perfect compressed sensing (CS) recovery can be achieved when a certain basis space is found to sparsely represent the original signal. However, due to the diversity of the signals, there does not exist a universal predetermined basis space that can sparsely represent all kinds of signals, which results in an unsatisfying performance. To improve the accuracy of recovered signal, this paper proposes an adaptive basis CS reconstruction algorithm by minimizing the rank of an accumulated matrix (MRAM), whose eigenvectors approximate the optimal basis sparsely representing the original signal. The accumulated matrix is constructed to efficiently exploit the second-order statistical property of the signal's autocorrelations. Based on the theory of matrix completion, MRAM reconstructs the original signal from its random projections under the observation that the constructed accumulated matrix is of low rank for most natural signals such as periodic signals and those coming from an autoregressive stationary process. Experimental results show that the proposed MRAM efficiently improves the reconstruction quality compared with the existing algorithms.

  20. Structure of boron nitride after the high-temperature shock compression

    International Nuclear Information System (INIS)

    Kurdyumov, A.V.; Ostrovskaya, N.F.; Pilipenko, V.A.; Pilyankevich, A.N.; Savvakin, G.I.; Trefilov, V.I.

    1979-01-01

    Boron nitride structure changes as a result of high temperature dynamic compression are studied. The X-ray technique and transmission electron microscopy have been applied. The data on the structure and regularities of formation of diamond-like modifications of boron nitride at high temperature impact compression permit to consider martensite transformation as the first stage of formation of the sphalerite phase stable at high pressures. The second stage is possible if the temperature at the impact moment is sufficiently high for intensive diffusion processes

  1. Compressive Properties and Anti-Erosion Characteristics of Foam Concrete in Road Engineering

    Science.gov (United States)

    Li, Jinzhu; Huang, Hongxiang; Wang, Wenjun; Ding, Yifan

    2018-01-01

    To analyse the compression properties and anti-erosion characteristics of foam concrete, one dimensional compression tests were carried out using ring specimens of foam concrete, and unconfined compression tests were carried out using foam concrete specimens cured in different conditions. The results of one dimensional compression tests show that the compression curve of foam concrete has two critical points and three stages, which has significant difference with ordinary geotechnical materials such as soil. Based on the compression curve the compression modulus of each stage were determined. The results of erosion tests show that sea water has a slight influence on the long-term strength of foam concrete, while the sulphate solution has a significant influence on the long-term strength of foam concrete, which needs to pay more attention.

  2. Low Temperature Compression Set Resistant O-Ring Materials

    National Research Council Canada - National Science Library

    Heater, Kenneth

    2003-01-01

    Materials used in the construction of aircraft hydraulic and fuel system o-rings and seals must provide long-term performance in aggressive chemical environments over a wide range of temperatures and loads...

  3. Combustion Temperature Effect of Diesel Engine Convert to Compressed Natural Gas Engine

    OpenAIRE

    Semin; Abdul R. Ismail; Rosli A. Bakar

    2009-01-01

    Effect of combustion temperature in the engine cylinder of diesel engine convert to Compressed Natural Gas (CNG) engine was presents in this study. The objective of this study was to investigate the engine cylinder combustion temperature effect of diesel engine convert to CNG engine on variation engine speed. Problem statement: The hypothesis was that the lower performance of CNG engine was caused by the effect of lower in engine cylinder temperature. Are the CNG engine is lower cylinder temp...

  4. Robust steganographic method utilizing properties of MJPEG compression standard

    Directory of Open Access Journals (Sweden)

    Jakub Oravec

    2015-06-01

    Full Text Available This article presents design of steganographic method, which uses video container as cover data. Video track was recorded by webcam and was further encoded by compression standard MJPEG. Proposed method also takes in account effects of lossy compression. The embedding process is realized by switching places of transform coefficients, which are computed by Discrete Cosine Transform. The article contains possibilities, used techniques, advantages and drawbacks of chosen solution. The results are presented at the end of the article.

  5. Strength and Permeability Evolution of Compressed Bentonite in Response to Salinity and Temperature Changes

    Science.gov (United States)

    Winnard, B. R.; Mitchell, T. M.; Browning, J.; Cuss, R. J.; Norris, S.; Meredith, P. G.

    2017-12-01

    Deep geological repositories are the preferred solution to dispose of radioactive waste; design concepts for these disposal facilities include compacted, saturated bentonite as a buffer between waste canister and host rock. Bentonite is favoured for its high swelling capacity, low permeability, and radionuclide retention properties. However, its thermo-hydro-mechanical tolerances must be thoroughly tested to ensure adequate long term performance. Climate variations are likely to induce periods of permafrost, and consequently, changes in groundwater salinity at depth. We performed laboratory experiments investigating effects of temperature and salinity change on uniaxial compressive strength (UCS), and permeability of compacted MX-80 bentonite cylinders. These specimens (moisture content = 22.9±0.1%, dry density = 1.66±0.02 g.cm-3) were compacted with deionised water, and a range of wt% NaCl, CaCl2, or KCl, to compare the effects of compaction fluid. Samples of compressed bentonite were cooled to -20 °C, and heated to 90 ºC, a possible temperature forecast for a repository dependent on factors such as geographical location, waste type, and facility design. Tests were all performed at room temperature, however in situ temperature tests are planned. The UCS of samples that experienced freeze thaw, and 40 ºC treatment failed at 6.5 MPa, with 4% strain, maintaining the same values as untreated bentonite compacted with deionised water. Samples compacted with saline solutions also yielded similar strengths, of 7 MPa, and failed at 4%. However, the 90 ºC, regardless of compaction fluid, failed at 15-18 MPa, at just 2% strain. In all experiments, the spread of strain accommodated varied inconsistently, however, peak stress was uniform. Further experiments into heterogeneity are needed to understand the responsible mechanisms. To obtain permeability, we utilised the pore pressure oscillation (PPO) technique with argon as the pore fluid. We also tested water as the pore

  6. Effect of high temperature corrosion in liquid lithium on mechanical properties of beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Kupriyanov, I.B., E-mail: igorkupr@rol.ru [A.A. Bochvar Research Institute of Inorganic Materials (VNIINM), Box 369, Moscow 123060 (Russian Federation); Kudryavtsev, V.N.; Kurbatova, L.A. [A.A. Bochvar Research Institute of Inorganic Materials (VNIINM), Box 369, Moscow 123060 (Russian Federation); Lyublinski, I.E. [Federal State Unitary Enterprise ' Red Star' , Moscow 115230 (Russian Federation)

    2010-12-15

    Recent experimental results on beryllium corrosion behavior after testing in liquid lithium at temperatures from 600 to 800 {sup o}C for 200-500 h are presented. The influences of test conditions (temperature, duration, lithium purity), beryllium characteristics (microstructure, grain size and chemical composition) and a penetration of lithium into beryllium on compressive properties of beryllium are discussed.

  7. Influence of Eco-Friendly Mineral Additives on Early Age Compressive Strength and Temperature Development of High-Performance Concrete

    Science.gov (United States)

    Kaszynska, Maria; Skibicki, Szymon

    2017-12-01

    High-performance concrete (HPC) which contains increased amount of both higher grade cement and pozzolanic additives generates more hydration heat than the ordinary concrete. Prolonged periods of elevated temperature influence the rate of hydration process in result affecting the development of early-age strength and subsequent mechanical properties. The purpose of the presented research is to determine the relationship between the kinetics of the heat generation process and the compressive strength of early-age high performance concrete. All mixes were based on the Portland Cement CEM I 52.5 with between 7.5% to 15% of the cement mass replaced by the silica fume or metakaolin. Two characteristic for HPC water/binder ratios of w/b = 0.2 and w/b = 0.3 were chosen. A superplasticizer was used to maintain a 20-50 mm slump. Compressive strength was determined at 8h, 24h, 3, 7 and 28 days on 10x10x10 cm specimens that were cured in a calorimeter in a constant temperature of T = 20°C. The temperature inside the concrete was monitored continuously for 7 days. The study determined that the early-age strength (tconcrete with reactive mineral additives is lower than concrete without them. This is clearly visible for concretes with metakaolin which had the lowest compressive strength in early stages of hardening. The amount of the superplasticizer significantly influenced the early-age compressive strength of concrete. Concretes with additives reached the maximum temperature later than the concretes without them.

  8. High-temperature of thermodynamic properties of sodium

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, A. Jr.

    1977-01-01

    The set of high-temperature thermodynamic properties for sodium in the two-phase and subcooled-liquid regions which was previously recommended, has been modified to incorporate recent experimental data. In particular, replacement of the previously estimated critical constants with experimentally-determined values has resulted in substantial differences in the region of the critical point. The following thermodynamic properties were determined: pressure, density, enthalpy, entropy, internal energy, compressibility (adiabatic and isothermal), thermal expansion coefficient, thermal pressure coefficient, and specific heat (constant-pressure and constant-volume). These properties were determined for the saturated liquid, saturated vapor, subcooled liquid, and superheated vapor. The superheated vapor properties are limited to low pressures and more work is required to extend them to higher pressures. The supercritical region was not investigated.

  9. Compressibility, zero sound, and effective mass of a fermionic dipolar gas at finite temperature

    International Nuclear Information System (INIS)

    Kestner, J. P.; Das Sarma, S.

    2010-01-01

    The compressibility, zero-sound dispersion, and effective mass of a gas of fermionic dipolar molecules is calculated at finite temperature for one-, two-, and three-dimensional uniform systems, and in a multilayer quasi-two-dimensional system. The compressibility is nonmonotonic in the reduced temperature, T/T F , exhibiting a maximum at finite temperature. This effect might be visible in a quasi-low-dimensional experiment, providing a clear signature of the onset of many-body quantum degeneracy effects. The collective mode dispersion and effective mass show similar nontrivial temperature and density dependence. In a quasi-low-dimensional system, the zero-sound mode may propagate at experimentally attainable temperatures.

  10. [Impact of directly compressed auxiliary materials on powder property of fermented cordyceps powder].

    Science.gov (United States)

    Chen, Li-Hua; Yue, Guo-Chao; Guan, Yong-Mei; Yang, Ming; Zhu, Wei-Feng

    2014-01-01

    To investigate such physical indexes as hygroscopicity, angle of repose, bulk density, fillibility of compression of mixed powder of directly compressed auxiliary materials and fermented cordyceps powder by using micromeritic study methods. The results showed that spray-dried lactose Flowlac100 and microcrystalline cellulose Avicel PH102 had better effect in liquidity and compressibility on fermented cordyceps powder than pregelatinized starch. The study on the impact of directly compressed auxiliary materials on the powder property of fermented cordyceps powder had guiding significant to the research of fermented cordyceps powder tablets, and could provide basis for the development of fermented cordyceps powder tablets.

  11. High-temperature Superconductivity in compressed Solid Silane

    Science.gov (United States)

    Zhang, Huadi; Jin, Xilian; Lv, Yunzhou; Zhuang, Quan; Liu, Yunxian; Lv, Qianqian; Bao, Kuo; Li, Da; Liu, Bingbing; Cui, Tian

    2015-01-01

    Crystal structures of silane have been extensively investigated using ab initio evolutionary simulation methods at high pressures. Two metallic structures with P21/c and C2/m symmetries are found stable above 383 GPa. The superconductivities of metallic phases are fully explored under BCS theory, including the reported C2/c one. Perturbative linear-response calculations for C2/m silane at 610 GPa reveal a high superconducting critical temperature that beyond the order of 102 K. PMID:25746861

  12. Compressed collagen constructs with optimized mechanical properties and cell interactions for tissue engineering applications

    DEFF Research Database (Denmark)

    Ajalloueian, Fatemeh; Nikogeorgos, Nikolaos; Ajalloueian, Ali

    2018-01-01

    In this study, we are introducing a simple, fast and reliable add-in to the technique of plastic compression (PC) to obtain collagen sheets with decreased fibrillar densities, representing improved cell-interactions and mechanical properties. Collagen hydrogels with different initial concentrations...... for plastic compression, not only a better cell environment and optimum mechanical properties are achieved, but also the application costs of this biopolymer is reduced....

  13. Compressive Properties of PTFE/Al/Ni Composite Under Uniaxial Loading

    Science.gov (United States)

    Wang, Huai-xi; Li, Yu-chun; Feng, Bin; Huang, Jun-yi; Zhang, Sheng; Fang, Xiang

    2017-05-01

    To investigate the mechanical properties of pressed and sintered PTFE/Al/Ni (polytetrafluoroethylene/aluminum/nickel) composite, uniaxial quasi-static and dynamic compression experiments were conducted at strain rates from 10-2 to 3 × 103/s. The prepared samples were tested by an electrohydraulic press with 300 kN loading capacity and a split Hopkinson pressure bar (SHPB) device at room temperature. Experimental results show that PTFE/Al/Ni composite exhibits evident strain hardening and strain rate hardening. Additionally, a bilinear relationship between stress and {{log(}}\\dot{ɛ} ) is observed. The experimental data were fit to Johnson-Cook constitutive model, and the results are in well agreement with measured data.

  14. An investigation of the direct compression properties of pre ...

    African Journals Online (AJOL)

    ADOWIE PERE

    tablets made were then kept in air tight containers and stored in a desiccator until evaluation. Tablet evaluations: The following tests were carried out on the compressed tablets employing standard procedures: tablet weight uniformity, dimensions, crushing strength (hardness), friability, disintegration time and dissolution ...

  15. Thermophysical properties of multi-shock compressed dense argon.

    Science.gov (United States)

    Chen, Q F; Zheng, J; Gu, Y J; Chen, Y L; Cai, L C; Shen, Z J

    2014-02-21

    In contrast to the single shock compression state that can be obtained directly via experimental measurements, the multi-shock compression states, however, have to be calculated with the aid of theoretical models. In order to determine experimentally the multiple shock states, a diagnostic approach with the Doppler pins system (DPS) and the pyrometer was used to probe multiple shocks in dense argon plasmas. Plasma was generated by a shock reverberation technique. The shock was produced using the flyer plate impact accelerated up to ∼6.1 km/s by a two-stage light gas gun and introduced into the plenum argon gas sample, which was pre-compressed from the environmental pressure to about 20 MPa. The time-resolved optical radiation histories were determined using a multi-wavelength channel optical transience radiance pyrometer. Simultaneously, the particle velocity profiles of the LiF window was measured with multi-DPS. The states of multi-shock compression argon plasma were determined from the measured shock velocities combining the particle velocity profiles. We performed the experiments on dense argon plasmas to determine the principal Hugonoit up to 21 GPa, the re-shock pressure up to 73 GPa, and the maximum measure pressure of the fourth shock up to 158 GPa. The results are used to validate the existing self-consistent variational theory model in the partial ionization region and create new theoretical models.

  16. Lowering the cost of large-scale energy storage: High temperature adiabatic compressed air energy storage

    Directory of Open Access Journals (Sweden)

    B. Cárdenas

    2017-06-01

    Full Text Available Compressed air energy storage is an energy storage technology with strong potential to play a significant role in balancing energy on transmission networks, owing to its use of mature technologies and low cost per unit of storage capacity. Adiabatic compressed air energy storage (A-CAES systems typically compress air from ambient temperature in the charge phase and expand the air back to ambient temperature in the discharge phase. This papers explores the use of an innovative operating scheme for an A-CAES system aimed at lowering the total cost of the system for a given exergy storage capacity. The configuration proposed considers preheating of the air before compression which increases the fraction of the total exergy that is stored in the form of high-grade heat in comparison to existing designs in which the main exergy storage medium is the compressed air itself. Storing a high fraction of the total exergy as heat allows reducing the capacity of costly pressure stores in the system and replacing it with cheaper thermal energy stores. Additionally, a configuration that integrates a system based on the aforementioned concept with solar thermal power or low-medium grade waste heat is introduced and thoroughly discussed.

  17. Tension–compression asymmetry in an extruded Mg alloy AM30: Temperature and strain rate effects

    International Nuclear Information System (INIS)

    Zachariah, Z.; Tatiparti, Sankara Sarma V.; Mishra, S.K.; Ramakrishnan, N.; Ramamurty, U.

    2013-01-01

    The effect of strain rate, ε, and temperature, T, on the tension–compression asymmetry (TCA) in a dilute and wrought Mg alloy, AM30, over a temperature range that covers both twin accommodated deformation (below 250 °C in compression) as well as dislocation-mediated plasticity (above 250 °C) has been investigated. For this purpose, uniaxial tension and compression tests were conducted at T ranging from 25 to 400 °C with ε varying between 10 −2 and 10 s −1 . In most of the cases, the stress–strain responses in tension and compression are distinctly different; with compression responses ‘concaving upward,’ due to {101-bar 2} tensile twinning at lower plastic strains followed by slip and strain hardening at higher levels of deformation, for T below 250 °C. This results in significant levels of TCA at T −1 , suggesting that twin-mediated plastic deformation takes precedence at high rates of loading even at sufficiently high T. TCA becomes negligible at T=350 °C; however at T=400 °C, as ε increases TCA gets higher. Microscopy of the deformed samples, carried out by using electron back-scattered diffraction (EBSD), suggests that at T>250 °C dynamic recrystallization begins between accompanied by reduction in the twinned fraction that contributes to the decrease of the TCA

  18. The effect of compression, stretching, and cooking temperature on free oil formation in mozzarella curd.

    Science.gov (United States)

    Rowney, M K; Roupas, P; Hickey, M W; Everett, D W

    2003-02-01

    The effect of the extent and rate of compression and stretching on free oil formation in Mozzarella cheese curd was investigated at 55, 65, and 75 degrees C. Confocal laser scanning microscopy was used to determine the maximum cross-sectional diameter, cross-sectional area, elongation factor (maximum divided by minimum cross-sectional diameter), and circularity of fat globules in the cheese curd at the different temperatures, and after stretching or compression. Free oil was not significantly affected by the rate of biaxial compression from 50 to 2000 mm/min at 65 degrees C, the rate of tensile stretching from 1000 to 2500 mm/min at 60 degrees C, or the extent of biaxial compression from 40 to 80% of the original height at 1000 mm/min and 65 degrees C. Increasing the rate of stretching from 1000 to 2500 mm/min increased the elongation factor from 1.91 to 2.61. Cross-sectional area, maximum diameter, and circularity were not affected by the rate of biaxial compression. The extent of curd compression had no effect on the milk fat globule size and shape. Increasing the extent of stretching at 60 degrees C and at 1000 mm/min increased the free oil content (on a fat basis) from 23.8% (curd stretched by 1.4x) to 32.3% (stretched by 4.6x) and the elongation factor of the globules, but did not affect any of the other globule parameters. Increasing the temperature of the cooking-stretching water increased the cross-sectional area, diameter of the globules, and free oil content from 24.1% at 55 degrees C to 34.5% at 75 degrees C for curd compressed to 50% height at 1000 mm/min.

  19. Particle Engineering of Excipients for Direct Compression: Understanding the Role of Material Properties.

    Science.gov (United States)

    Mangal, Sharad; Meiser, Felix; Morton, David; Larson, Ian

    2015-01-01

    Tablets represent the preferred and most commonly dispensed pharmaceutical dosage form for administering active pharmaceutical ingredients (APIs). Minimizing the cost of goods and improving manufacturing output efficiency has motivated companies to use direct compression as a preferred method of tablet manufacturing. Excipients dictate the success of direct compression, notably by optimizing powder formulation compactability and flow, thus there has been a surge in creating excipients specifically designed to meet these needs for direct compression. Greater scientific understanding of tablet manufacturing coupled with effective application of the principles of material science and particle engineering has resulted in a number of improved direct compression excipients. Despite this, significant practical disadvantages of direct compression remain relative to granulation, and this is partly due to the limitations of direct compression excipients. For instance, in formulating high-dose APIs, a much higher level of excipient is required relative to wet or dry granulation and so tablets are much bigger. Creating excipients to enable direct compression of high-dose APIs requires the knowledge of the relationship between fundamental material properties and excipient functionalities. In this paper, we review the current understanding of the relationship between fundamental material properties and excipient functionality for direct compression.

  20. Effects of axial compression and rotation angle on torsional mechanical properties of bovine caudal discs.

    Science.gov (United States)

    Bezci, Semih E; Klineberg, Eric O; O'Connell, Grace D

    2018-01-01

    The intervertebral disc is a complex joint that acts to support and transfer large multidirectional loads, including combinations of compression, tension, bending, and torsion. Direct comparison of disc torsion mechanics across studies has been difficult, due to differences in loading protocols. In particular, the lack of information on the combined effect of multiple parameters, including axial compressive preload and rotation angle, makes it difficult to discern whether disc torsion mechanics are sensitive to the variables used in the test protocol. Thus, the objective of this study was to evaluate compression-torsion mechanical behavior of healthy discs under a wide range of rotation angles. Bovine caudal discs were tested under a range of compressive preloads (150, 300, 600, and 900N) and rotation angles (± 1, 2, 3, 4, or 5°) applied at a rate of 0.5°/s. Torque-rotation data were used to characterize shape changes in the hysteresis loop and to calculate disc torsion mechanics. Torsional mechanical properties were described using multivariate regression models. The rate of change in torsional mechanical properties with compression depended on the maximum rotation angle applied, indicating a strong interaction between compressive stress and maximum rotation angle. The regression models reported here can be used to predict disc torsion mechanics under axial compression for a given disc geometry, compressive preload, and rotation angle. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Torsional and axial compressive properties of tibiotarsal bones of red-tailed hawks (Buteo jamaicensis).

    Science.gov (United States)

    Kerrigan, Shannon M; Kapatkin, Amy S; Garcia, Tanya C; Robinson, Duane A; Guzman, David Sanchez-Migallon; Stover, Susan M

    2018-04-01

    OBJECTIVE To describe the torsional and axial compressive properties of tibiotarsal bones of red-tailed hawks (Buteo jamaicensis). SAMPLE 16 cadaveric tibiotarsal bones from 8 red-tailed hawks. PROCEDURES 1 tibiotarsal bone from each bird was randomly assigned to be tested in torsion, and the contralateral bone was tested in axial compression. Intact bones were monotonically loaded in either torsion (n = 8) or axial compression (8) to failure. Mechanical variables were derived from load-deformation curves. Fracture configurations were described. Effects of sex, limb side, and bone dimensions on mechanical properties were assessed with a mixed-model ANOVA. Correlations between equivalent torsional and compressive properties were determined. RESULTS Limb side and bone dimensions were not associated with any mechanical property. During compression tests, mean ultimate cumulative energy and postyield energy for female bones were significantly greater than those for male bones. All 8 bones developed a spiral diaphyseal fracture and a metaphyseal fissure or fracture during torsional tests. During compression tests, all bones developed a crushed metaphysis and a fissure or comminuted fracture of the diaphysis. Positive correlations were apparent between most yield and ultimate torsional and compressive properties. CONCLUSIONS AND CLINICAL RELEVANCE The torsional and axial compressive properties of tibiotarsal bones described in this study can be used as a reference for investigations into fixation methods for tibiotarsal fractures in red-tailed hawks. Although the comminuted and spiral diaphyseal fractures induced in this study were consistent with those observed in clinical practice, the metaphyseal disruption observed was not and warrants further research.

  2. Stress-Strain Compression of AA6082-T6 Aluminum Alloy at Room Temperature

    Directory of Open Access Journals (Sweden)

    Alexandre da Silva Scari

    2014-01-01

    Full Text Available Short cylindrical specimens made of AA6082-T6 aluminum alloy were studied experimentally (compression tests, analytically (normalized Cockcroft-Latham criteria—nCL, and numerically (finite element analysis—FEA. The mechanical properties were determined with the stress-strain curves by the Hollomon equation. The elastic modulus obtained experimentally differs from the real value, as expected, and it is also explained. Finite element (FE analysis was carried out with satisfactory correlation to the experimental results, as it differs about 1,5% from the damage analysis by the nCL concerning the experimental data obtained by compression tests.

  3. Temperature dependence of dynamic behavior of commercially pure titanium by the compression test

    International Nuclear Information System (INIS)

    Lee, Su Min; Seo, Song Won; Park, Kyoung Joon; Min, Oak Key

    2003-01-01

    The mechanical behavior of a Commercially Pure Titanium (CP-Ti) is investigated at high temperature Split Hopkinson Pressure Bar (SHPB) compression test with high strain-rate. Tests are performed over a temperature range from room temperature to 1000 .deg. C with interval of 200 deg. C and a strain-rate range of 1900∼2000/sec. The true flow stress-true strain relations depending on temperature are achieved in these tests. For construction of constitutive equation from the true flow stress-true strain relation, parameters for the Johnson-Cook constitutive equation is determined. And the modified Johnson-Cook equation is used for investigation of behavior of flow stress in vicinity of recrystallization temperature. The modified Johnson-Cook constitutive equation is more suitable in expressing the dynamic behavior of a CP-Ti at high temperature, i.e. about recrystallization temperature

  4. Long-term Isothermal Aging Effects on Weight Loss, Compression Properties, and Dimensions of T650-35 Fabric-reinforced PMR-15 Composites-data

    Science.gov (United States)

    Bowles, Kenneth J.; Tsuji, Luis; Kamvouris, John; Roberts, Gary D.

    2003-01-01

    A cooperative program was conducted with the General Electric Aircraft Engines plant in Evendale, Ohio, to study the effects of long-term isothermal aging at elevated temperatures on compression and thermal durability properties of T650 35 fabric-reinforced PMR 15 composites. This degradation study was conducted over an approximate time period of 3 1/2 yr. The aging temperatures were 204, 260, 288, 316, and 343 C. Specimens of different dimensions were evaluated. Specimens with ratios of the cut edge to total surface area of 0.03 to 0.89 were fabricated and aged. The aged and unaged specimens were tested in compression as specified in Test Method for Compressive Properties of Rigid Plastics (ASTM D695M). Thickness changes, degraded surface layer growth, weight loss, and failure modes were monitored and recorded. All property changes were thickness dependent.

  5. EFFECT OF SODIUM HYDROXIDE CONCENTRATION ON FRESH PROPERTIES AND COMPRESSIVE STRENGTH OF SELF-COMPACTING GEOPOLYMER CONCRETE

    Directory of Open Access Journals (Sweden)

    FAREED AHMED MEMON

    2013-02-01

    Full Text Available This paper reports the results of the laboratory tests conducted to investigate the effect of sodium hydroxide concentration on the fresh properties and compressive strength of self-compacting geopolymer concrete (SCGC. The experiments were conducted by varying the concentration of sodium hydroxide from 8 M to 14 M. Test methods such as Slump flow, V-Funnel, L-box and J-Ring were used to assess the workability characteristics of SCGC. The test specimens were cured at 70°C for a period of 48 hours and then kept in room temperature until the day of testing. Compressive strength test was carried out at the ages of 1, 3, 7 and 28 days. Test results indicate that concentration variation of sodium hydroxide had least effect on the fresh properties of SCGC. With the increase in sodium hydroxide concentration, the workability of fresh concrete was slightly reduced; however, the corresponding compressive strength was increased. Concrete samples with sodium hydroxide concentration of 12 M produced maximum compressive strength.

  6. Temperature dependence of elastic properties of paratellurite

    International Nuclear Information System (INIS)

    Silvestrova, I.M.; Pisarevskii, Y.V.; Senyushenkov, P.A.; Krupny, A.I.

    1987-01-01

    New data are presented on the temperature dependence of the elastic wave velocities, elastic stiffness constants, and thermal expansion of paratellurite. It is shown that the external pressure appreciably influences the elastic properties of TeO 2 , especially the temperature dependence of the elastic modulus connected with the crystal soft mode. (author)

  7. Tension–compression asymmetry in an extruded Mg alloy AM30: Temperature and strain rate effects

    Energy Technology Data Exchange (ETDEWEB)

    Zachariah, Z. [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Tatiparti, Sankara Sarma V.; Mishra, S.K.; Ramakrishnan, N. [General Motors Technical Center, ITPL, Whitefield, Bangalore 560066 (India); Ramamurty, U., E-mail: ramu@materials.iisc.ernet.in [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India)

    2013-06-10

    The effect of strain rate, ε, and temperature, T, on the tension–compression asymmetry (TCA) in a dilute and wrought Mg alloy, AM30, over a temperature range that covers both twin accommodated deformation (below 250 °C in compression) as well as dislocation-mediated plasticity (above 250 °C) has been investigated. For this purpose, uniaxial tension and compression tests were conducted at T ranging from 25 to 400 °C with ε varying between 10{sup −2} and 10 s{sup −1}. In most of the cases, the stress–strain responses in tension and compression are distinctly different; with compression responses ‘concaving upward,’ due to {101-bar 2} tensile twinning at lower plastic strains followed by slip and strain hardening at higher levels of deformation, for T below 250 °C. This results in significant levels of TCA at T<250 °C, reducing substantially at high temperatures. At T=150 and 250 °C, high ε leads to high TCA, in particular at T=250 °C and ε=10 s{sup −1}, suggesting that twin-mediated plastic deformation takes precedence at high rates of loading even at sufficiently high T. TCA becomes negligible at T=350 °C; however at T=400 °C, as ε increases TCA gets higher. Microscopy of the deformed samples, carried out by using electron back-scattered diffraction (EBSD), suggests that at T>250 °C dynamic recrystallization begins between accompanied by reduction in the twinned fraction that contributes to the decrease of the TCA.

  8. The Varying Effects of Uniaxial Compressive Stress on the Bainitic Transformation under Different Austenitization Temperatures

    Directory of Open Access Journals (Sweden)

    Mingxing Zhou

    2016-05-01

    Full Text Available In this study, thermal simulation experiments under different austenitization temperatures and different stress states were conducted. High-temperature laser scanning confocal microscopy (LSCM, thermal dilatometry, and scanning electron microscope (SEM were used to quantitatively investigate the effects of the uniaxial compressive stress on bainitic transformation at 330 °C following different austenitization temperatures. The transformation plasticity was also analyzed. It was found that the promotion degree of stress on bainitic transformation increases with the austenitization temperature due to larger prior austenite grain size as well as stronger promoting effect of mechanical driving force on selected variant growth at higher austenitization temperatures. The grain size and the yield strength of prior austenite are other important factors which influence the promotion degree of stress on bainitic transformation, besides the mechanical driving force provided by the stress. Moreover, the transformation plasticity increases with the austenitization temperature.

  9. Analysis of an absorption/absorption–compression refrigeration system for heat sources with large temperature change

    International Nuclear Information System (INIS)

    Chen, Yi; Han, Wei; Jin, Hongguang

    2016-01-01

    Highlights: • This paper proposes an absorption/absorption–compression refrigeration system. • The temperature of the waste gas exhausted from the system is quite low. • The system cooling capacity per unit mass of flue gas is 58.95 kJ kg −1 at −15 °C. • Key parameters were investigated to provide guidance to the system optimization. - Abstract: Absorption refrigeration systems are a promising way to reduce electricity consumption in the field of refrigeration and cooling. To improve the thermal energy utilization performance of the absorption refrigeration system, an absorption/absorption–compression refrigeration system with a large working range is proposed in this paper. The new system consists of a conventional single-effect absorption subcycle and an absorption–compression refrigeration subcycle, and they share the condenser, evaporator, absorber and some other relative components. The temperature of the waste gas exhausted from the system can be 35 °C lower than that of the waste gas from a traditional, single-effect absorption refrigeration system. For the proposed system, the cooling capacity per unit mass of flue gas reaches 58.95 kJ kg −1 when the evaporation temperature is −15 °C, which is 28.21% higher than that of the single-effect absorption refrigeration system. The exergy efficiency of the proposed system is as high as 25.94%. To indicate the direction of system optimization, the new system is further studied using a parametric analysis. The new absorption/absorption–compression refrigeration system provides a promising way to efficiently utilize heat sources with large temperature change or multiple heat sources with different temperatures.

  10. Electromechanical properties of carbon nanotube networks under compression

    Czech Academy of Sciences Publication Activity Database

    Slobodian, P.; Říha, Pavel; Olejník, R.; Sáha, P.

    2011-01-01

    Roč. 22, č. 12 (2011), s. 124006 ISSN 0957-0233 R&D Projects: GA AV ČR IAA200600803 Grant - others:Interní grantová agentura UTB(CZ) IGA/12/FT/10/D; OP VaVpI(XE) CZ.1.05/2.1.00/03.0111 Institutional research plan: CEZ:AV0Z20600510 Keywords : carbon nanotube network * compression * electrical conductivity * stress sensor Subject RIV: JB - Sensor s, Measurment, Regulation Impact factor: 1.494, year: 2011

  11. [Determination of high temperature compressive strength and refractory degree of die material compatible with slip casting core of sintered titanium powder].

    Science.gov (United States)

    Kuang, X; Liao, Y; Chao, Y; Meng, Y

    1999-05-01

    The refractory die is the precondition for developing slip casting core of sintered powder. This study is to determine the high temperature properties of the refractory die material compatible with slip casting core. To prepare three cylindrical specimens (phi 10 x 15 mm) and determine their compressive strength at 1000 degrees C: to make four specimens in flat-topped cone for determining the practical refractory degree by decreasing the pressing temperatures in a sequence of 1420, 1400, 1350 and 1100 degrees C. The compressive strength of this material was 17.8 MPa at 1000 degrees C. Its practical refractory degree was higher than 1100 degrees C. The high temperature properties of the refractory die material that we developed meet the demand of slip casting core of sintered powder.

  12. Liquid phase PVTx properties of (water + tert-butanol) binary mixtures at temperatures from 278.15 to 323.15 K and pressures from 0.1 to 100 MPa. II. Molar isothermal compressions, molar isobaric expansions, molar thermal pressure coefficients, and internal pressure

    International Nuclear Information System (INIS)

    Egorov, Gennadiy I.; Makarov, Dmitriy M.; Kolker, Arkadiy M.

    2013-01-01

    Highlights: ► Molar isothermal compressions and molar isobaric expansions were evaluated. ► Coefficients of thermal pressure and internal pressure were obtained. ► Concentration dependences of coefficients under study display extremes. ► Temperature and pressure dependences of internal pressure of the mixture were linear. -- Abstract: Molar isothermal compressions, molar isobaric expansions, molar coefficients of thermal pressure, and internal pressure were calculated over the whole concentration range of {water (1) + tert-butanol (2)} mixture at pressures from 0.1 to 100 MPa and temperatures from 278.15 to 323.15 K. It was revealed that the extremes, observed on concentration dependences of molar isothermal compression K T,m and molar isobaric expansion E P,m of the mixture, became more pronounced with pressure growth and temperature lowering. Values of molar thermal pressure coefficients of the mixture sharply rose at compositions with small TBA mole fraction and then decreased practically linearly with the alcohol content increasing. Temperature and pressure dependences of the mixture internal pressure were almost linear, and at low TBA concentrations changed significantly from the dependences of water, tert-butanol and their mixtures at large alcohol content

  13. Properties of strain gages at cryogenic temperature

    International Nuclear Information System (INIS)

    Shibata, Nobuo; Fujiyoshi, Toshimitsu.

    1978-01-01

    At the time of developing superconduction generators, the stress measurement for rotor parts is required to grasp the safety and performance of the rotor at cryogenic temperature, which is cooled with liquid helium. In case of carrying out the stress measurement with strain gages, the problems are as follows. The strain gages and lead wires are exposed to cryogenic temperature from 4 to 10 K and strong magnetic field of about 3T, and subjected to high centrifugal acceleration of about 500G. In order to establish the techniques of the stress measurement under such conditions, the adhesives and damp-proof coatings for strain gages and strain gages themselves in Japan and foreign countries were examined on the properties at cryogenic temperature. As for the properties of strain gages, mainly the apparent strain owing to temperature change was investigated, and the change of the gage factors was studies only at liquid nitrogen temperature. The stress measurement with strain gages at low temperature had been studied in detail down to liquid nitrogen temperature concerning LNG tanks. The experimental apparatus, the samples, the testing methods and the test results of cooling tests on adhesives and damp-proof coatings, and the temperature characteristics of strain gages are reported. The usable adhesives and coatings were found, and correction by accurate temperature measurement is required for apparent strain. (Kako, I.)

  14. Temperature-dependent Transport Properties of Graphene

    Science.gov (United States)

    Zhong, Bochen; Singh, Amol; Uddin, Ahsan; Koley, Goutam; Webb, Richard

    2014-03-01

    Temperature-dependent transport properties of graphene synthesized by chemical vapor deposition (CVD) on a Cu thin sheet have been investigated. Raman spectra of our samples show good quality of the CVD graphene. We have measured the temperature dependence of conductivity, charge-carrier density and Hall mobility of graphene by patterning them into micrometer-sized Hall bars. Quantum Hall effect has been observed when the temperature is about 60 Kelvin, which is the evidence for single-layer graphene. Furthermore, the results of temperature dependence of Hall mobility indicate that impurity and defect scattering is the primary scattering mechanism at low temperature, while substrate surface polar phonon scattering is dominant at high temperature.

  15. Extremely low temperature properties of epoxy GFRP

    International Nuclear Information System (INIS)

    Kadotani, Kenzo; Nagai, Matao; Aki, Fumitake.

    1983-01-01

    The examination of fiber-reinforced plastics, that is, plastics such as epoxy, polyester and polyimide reinforced with high strength fibers such as glass, carbon, boron and steel, for extremely low temperature use began from the fuel tanks of rockets. Therafter, the trial manufacture of superconducting generators and extremely low temperature transformers and the manufacture of superconducting magnets for nuclear fusion experimental setups became active, and high performance FRPs have been adopted, of which the extremely low temperature properties have been sufficiently grasped. Recently, the cryostats made of FRPs have been developed, fully utilizing such features of FRPs as high strength, high rigidity, non-magnetic material, insulation, low heat conductivity, light weight and the freedom of molding. In this paper, the mechanical properties at extremely low temperature of the plastic composite materials used as insulators and structural materials for extremely low temperature superconducting equipment is outlined, and in particular, glass fiber-reinforced epoxy laminates are described somewhat in detail. The fracture strain of GFRP at extremely low temperature is about 1.3 times as large as that at room temperature, but at extremely low temperature, clear cracking occurred at 40% of the fracture strain. The linear thermal contraction of GFRP showed remarkable anisotropy. (Kako, I.)

  16. Integrated LTCC pressure/flow/temperature multisensor for compressed air diagnostics.

    Science.gov (United States)

    Fournier, Yannick; Maeder, Thomas; Boutinard-Rouelle, Grégoire; Barras, Aurélie; Craquelin, Nicolas; Ryser, Peter

    2010-01-01

    We present a multisensor designed for industrial compressed air diagnostics and combining the measurement of pressure, flow, and temperature, integrated with the corresponding signal conditioning electronics in a single low-temperature co-fired ceramic (LTCC) package. The developed sensor may be soldered onto an integrated electro-fluidic platform by using standard surface mount device (SMD) technology, e.g., as a standard electronic component would be on a printed circuit board, obviating the need for both wires and tubes and thus paving the road towards low-cost integrated electro-fluidic systems. Several performance aspects of this device are presented and discussed, together with electronics design issues.

  17. Integrated LTCC Pressure/Flow/Temperature Multisensor for Compressed Air Diagnostics†

    Science.gov (United States)

    Fournier, Yannick; Maeder, Thomas; Boutinard-Rouelle, Grégoire; Barras, Aurélie; Craquelin, Nicolas; Ryser, Peter

    2010-01-01

    We present a multisensor designed for industrial compressed air diagnostics and combining the measurement of pressure, flow, and temperature, integrated with the corresponding signal conditioning electronics in a single low-temperature co-fired ceramic (LTCC) package. The developed sensor may be soldered onto an integrated electro-fluidic platform by using standard surface mount device (SMD) technology, e.g., as a standard electronic component would be on a printed circuit board, obviating the need for both wires and tubes and thus paving the road towards low-cost integrated electro-fluidic systems. Several performance aspects of this device are presented and discussed, together with electronics design issues. PMID:22163518

  18. Effects of Strain Rate on Compressive Properties in Bimodal 7075 Al-SiCp Composite

    Science.gov (United States)

    Lee, Hyungsoo; Choi, Jin Hyeok; Jo, Min Chul; Jo, Ilguk; Lee, Sang-Kwan; Lee, Sunghak

    2018-03-01

    A 7075 Al alloy matrix composite reinforced with SiC particulates (SiCps) whose sizes were 10 and 30 μm, i.e., a bimodal Al-SiCp composite, was made by a liquid pressing process, and its quasi-static and dynamic compressive properties were evaluated by using a universal testing machine and a split Hopkinson pressure bar, respectively. Mg-Si-, Al-Fe-, and Cu-rich intermetallic compounds existed inside the Al matrix, but might not deteriorate compressive properties because of their low volume fraction (about 2.6%) which was much lower than that of SiCp. The dynamic compressive strength was higher than the quasi-static strength, and was higher in the specimen tested at 2800 s-1 than in the specimen tested at 1400 s-1 according to the strain-rate hardening. For explaining the strain data, the blocking extent of crack propagation by the Al matrix was quantitatively examined. The melting of Al matrix occurred by adiabatic heating was favorable for the improvement in compressive strain because it favorably worked for activating the shear band formation and for blocking the crack propagation, thereby leading to the excellent compressive strain (10.9-11.6%) as well as maximum compressive strength (1057-1147 MPa). Thus, the present bimodal 7075 Al-SiCp composite provides a promise for new applications to high-performance armor plates.

  19. Experimental Investigation of a Mechanical Vapour Compression Chiller at Elevated Chilled Water Temperatures

    KAUST Repository

    Thu, Kyaw

    2017-05-18

    The performance of a Mechanical Vapour Compression (MVC) chiller is experimentally investigated under operating conditions suitable for sensible cooling. With the emergence of the energy efficient dehumidification systems, it is possible to decouple the latent load from the MVC chillers which can be operated at higher chilled water temperature for handling sensible cooling load. In this article, the performance of the chiller is evaluated at the elevated chilled water outlet temperatures (7 – 17° C) at various coolant temperatures (28 – 32° C) and flow rates (ΔT = 4 and 5° C) for both full- and part-load conditions. Keeping the performance at the AHRI standard as the baseline condition, the efficacy of the chiller in terms of compression ratio, cooling capacity and COP at aforementioned conditions is quantified experimentally. It is observed that for each one-degree Celsius increase in the chilled water temperature, the COP of the chiller improves by about 3.5% whilst the cooling capacity improvement is about 4%. For operation at 17° C chilled water outlet temperature, the improvements in COP and cooling capacity are between 37 – 40% and 40 – 45%, respectively, compared to the performance at the AHRI standards. The performance of the MVC chiller at the abovementioned operation conditions is mapped on the chiller performance characteristic chart.

  20. Mechanical Properties of Injection Molded and Compression Molded Samples from Nature-Butadiene Rubber

    Directory of Open Access Journals (Sweden)

    Skrobak Adam

    2016-01-01

    Full Text Available The aim of this paper is to show what extent there is an impact on the mechanical properties (tensile strength and tear strength of a standardized testing sample made of rubber compound based on nature rubber and butadiene rubber produced by injection molding in comparison with a sample produced by classic preparation (cutting out a compression molded plate according to the standard ISO 23529. For realization of this study it was necessary to design and produce an injection mold for all types testing samples. Subsequently, mechanical properties such as the tensile stress-strain and tear strenght of compression molded samples and injection molded samples were studied, compared and discussed.

  1. On the development of high temperature ammonia-water hybrid absorption-compression heat pumps

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Markussen, Wiebke Brix; Reinholdt, Lars

    2015-01-01

    Ammonia-water hybrid absorption-compression heat pumps (HACHP) are a promising technology for development of ecient high temperature industrial heat pumps. Using 28 bar components HACHPs up to 100 °C are commercially available. Components developed for 50 bar and 140 bar show that these pressure...... limits may be possible to exceed if needed for actual applications. Feasible heat supply temperatures using these component limits are investigated. A feasible solution is defined as one that satisfies constraints on the COP, low and high pressure, compressor discharge temperature, vapour water content......, and 140 bar up to 147 °C. If the compressor discharge temperature limit is increased to 250 °C and the vapour water content constraint is removed, this becomes: 182 °C, 193 °C and 223 °C....

  2. Compressing an Ensemble with Statistical Models: An Algorithm for Global 3D Spatio-Temporal Temperature

    KAUST Repository

    Castruccio, Stefano

    2015-04-02

    One of the main challenges when working with modern climate model ensembles is the increasingly larger size of the data produced, and the consequent difficulty in storing large amounts of spatio-temporally resolved information. Many compression algorithms can be used to mitigate this problem, but since they are designed to compress generic scientific data sets, they do not account for the nature of climate model output and they compress only individual simulations. In this work, we propose a different, statistics-based approach that explicitly accounts for the space-time dependence of the data for annual global three-dimensional temperature fields in an initial condition ensemble. The set of estimated parameters is small (compared to the data size) and can be regarded as a summary of the essential structure of the ensemble output; therefore, it can be used to instantaneously reproduce the temperature fields in an ensemble with a substantial saving in storage and time. The statistical model exploits the gridded geometry of the data and parallelization across processors. It is therefore computationally convenient and allows to fit a non-trivial model to a data set of one billion data points with a covariance matrix comprising of 10^18 entries.

  3. Structure and Mechanical Properties of Powdered Quasicrystalline Al94Fe3Cr3 Alloy Consolidated by Quasi-Hydrostatic Compression

    Directory of Open Access Journals (Sweden)

    Alexandra I. Yurkova

    2017-10-01

    Full Text Available Background. Quasicrystalline Al-based alloys belong to the class of the state-of-the-art metal materials for the application in light engineering constructions, primarily in aviation and the motor transport industry. These materials are commonly made in the form of powders, which is due to the high productivity of powder metallurgy methods. Therefore, the powder consolidation methods are of great importance in the production of products, which is associated with certain difficulties, and consequently, they should be chosen considering not only the quasicrystals’ propensity to brittle fracture but also the metastable nature of the quasicrystalline phases. Certain possibilities in this direction are provided by the quasi-hydrostatic compression method, which can provide a non-trivial combination of strength and ductility properties of materials. Objective. The aim of the paper is to investigate the effect of high pressure under quasi-hydrostatic compression on the formation of structure, phase composition and mechanical properties of the quasicrystalline Al94Fe3Cr3 alloy. Methods. 40 μm Al94Fe3Cr3 alloy quasicrystalline powder was fabricated by water-atomisation technique. Consolidation of quasicrystalline powder was performed by quasi-hydrostatic compression technique in high-pressure cells at room temperature at a pressure of 2.5, 4, and 6 hPa. Structure, phase composition and mechanical characteristics of Al94Fe3Cr3 alloy were performed by scanning electron microscopy (SEM, X-ray diffraction andmicromechanical tests. Results. Using the phase X-ray analysis and SEM, the content of the quasicrystalline icosahedral phase (i-phase in the Al94Fe3Cr3 alloy structure was completely preserved after its consolidation at different pressures (2.5, 4, and 6 hPa under quasi-hydrostatic compression at room temperature. Despite the high pressure applied in the consolidation process, the morphology of quasicrystalline phase particles located in the a

  4. Thermodynamics of aqueous methyldiethanolamine (MDEA) and methyldiethanolammonium chloride (MDEAH+Cl-) over a wide range of temperature and pressure: Apparent molar volumes, heat capacities, and isothermal compressibilities

    International Nuclear Information System (INIS)

    Hawrylak, B.; Palepu, R.; Tremaine, Peter R.

    2006-01-01

    Apparent molar volumes of aqueous methyldiethanolamine and its salt were determined with platinum vibrating tube densitometers over a range of temperatures from 283K= o , heat capacities C p o , and isothermal compressibilities κ T o . The standard partial molar volumes V o for the neutral amine and its salt show increasingly positive and negative values, respectively, at high temperatures and pressures, as predicted by corresponding states and group additivity arguments. The density model and the revised Helgeson-Kirkham-Flowers (HKF) model have been used to represent the temperature and pressure dependence of the standard partial molar properties to yield a full thermodynamic description of the system

  5. Thermoelastic properties of minerals at high temperature

    Indian Academy of Sciences (India)

    The knowledge of elasticity of the minerals is useful for interpreting the structure and composition of the lower mantle and also in seismic studies. The purpose of the present study is to discuss a simple and straightforward method for evaluating thermoelastic properties of minerals at high temperatures. We have extended ...

  6. Compressive fatigue tests on a unidirectional glass/polyester composite at cryogenic temperatures

    International Nuclear Information System (INIS)

    Stone, E.L.; El-Marazki, L.O.; Young, W.C.

    1979-01-01

    The fatigue testing of a unidirectional glass-reinforced polyester composite at cryogenic temperatures to simulate the cyclic compressive loads of the magnet support struts in a superconductive magnetic energy storage unit is reported. Right circular cylindrical specimens were tested at 77, 4.2 K and room temperature at different stress levels using a 1-Hz haversine waveform imposed upon a constant baseload in a load-controlled closed-loop electrohydraulic test machine. Two failure modes, uniform mushrooming near one end and a 45 deg fracture line through the middle of the specimen, are observed, with no systematic difference in fatigue life between the modes. Fatigue lives obtained at 77 and 4.2 K are found to be similar, with fatigue failure at 100,000 cycles occurring at stress levels of 70 and 75% of the ultimate compressive strengths of specimens at room temperature and 77 K, respectively. The room temperature fatigue lives of the glass/polyester specimens are found to be intermediate between those reported for glass/epoxy composites with different glass contents costing over twice as much

  7. Simulated effect on the compressive and shear mechanical properties of bionic integrated honeycomb plates.

    Science.gov (United States)

    He, Chenglin; Chen, Jinxiang; Wu, Zhishen; Xie, Juan; Zu, Qiao; Lu, Yun

    2015-05-01

    Honeycomb plates can be applied in many fields, including furniture manufacturing, mechanical engineering, civil engineering, transportation and aerospace. In the present study, we discuss the simulated effect on the mechanical properties of bionic integrated honeycomb plates by investigating the compressive and shear failure modes and the mechanical properties of trabeculae reinforced by long or short fibers. The results indicate that the simulated effect represents approximately 80% and 70% of the compressive and shear strengths, respectively. Compared with existing bionic samples, the mass-specific strength was significantly improved. Therefore, this integrated honeycomb technology remains the most effective method for the trial manufacturing of bionic integrated honeycomb plates. The simulated effect of the compressive rigidity is approximately 85%. The short-fiber trabeculae have an advantage over the long-fiber trabeculae in terms of shear rigidity, which provides new evidence for the application of integrated bionic honeycomb plates. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Using an artificial neural network to predict carbon dioxide compressibility factor at high pressure and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Mohagheghian, Erfan [Memorial University of Newfoundland, St. John' s (Canada); Zafarian-Rigaki, Habiballah; Motamedi-Ghahfarrokhi, Yaser; Hemmati-Sarapardeh, Abdolhossein [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2015-10-15

    Carbon dioxide injection, which is widely used as an enhanced oil recovery (EOR) method, has the potential of being coupled with CO{sub 2} sequestration and reducing the emission of greenhouse gas. Hence, knowing the compressibility factor of carbon dioxide is of a vital significance. Compressibility factor (Z-factor) is traditionally measured through time consuming, expensive and cumbersome experiments. Hence, developing a fast, robust and accurate model for its estimation is necessary. In this study, a new reliable model on the basis of feed forward artificial neural networks is presented to predict CO{sub 2} compressibility factor. Reduced temperature and pressure were selected as the input parameters of the proposed model. To evaluate and compare the results of the developed model with pre-existing models, both statistical and graphical error analyses were employed. The results indicated that the proposed model is more reliable and accurate compared to pre-existing models in a wide range of temperature (up to 1,273.15 K) and pressure (up to 140MPa). Furthermore, by employing the relevancy factor, the effect of pressure and temprature on the Z-factor of CO{sub 2} was compared for below and above the critical pressure of CO{sub 2}, and the physcially expected trends were observed. Finally, to identify the probable outliers and applicability domain of the proposed ANN model, both numerical and graphical techniques based on Leverage approach were performed. The results illustrated that only 1.75% of the experimental data points were located out of the applicability domain of the proposed model. As a result, the developed model is reliable for the prediction of CO{sub 2} compressibility factor.

  9. Low-Temperature Properties of Silver

    Science.gov (United States)

    Smith, David R.; Fickett, F. R.

    1995-01-01

    Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability. PMID:29151733

  10. Comparison of compression properties of stretchable knitted fabrics and bi-stretch woven fabrics for compression garments

    NARCIS (Netherlands)

    Maqsood, Muhammad

    2017-01-01

    Stretchable fabrics have diverse applications ranging from casual apparel to performance sportswear and compression therapy. Compression therapy is the universally accepted treatment for the management of hypertrophic scarring after severe burns. Mostly stretchable knitted fabrics are used in

  11. Screening of several excipients for direct compression of tablets: A new perspective based on functional properties

    Directory of Open Access Journals (Sweden)

    John Rojas

    2013-01-01

    Full Text Available Excipients are widely used to formulate solid drug forms by direct compression. However, the powderforming and tableting properties of these excipients are affected by the presence of lubricants and active ingredients. In this study, a screening methodology was employed to test the performance of an excipient for direct compression. The effects of three lubricants (magnesium stearate, stearic acid and talc on the compressibility and compaction of these excipients were assessed by the compressibility index and lubricant sensitivity ratio, respectively. Likewise, the dilution potential in blends with a poorly compactible drug such as acetaminophen was also assessed. Finally, the elastic recovery of tablets was evaluated five days after production. All lubricants increased the compressibility of these excipients and improved their flowability. However, hydrophobic lubricants such as magnesium stearate had a marked negative effect on compactibility, especially in plastic-deforming and more regularlyshaped materials with a smooth surface such as Starch 1500. Alginic acid, rice and cassava starches had the largest elastic recovery (>5%, indicating a tendency to cap. Moreover, highly plastic deforming materials such as sorbitol and polyvinylpyrrolidone (PVP-K30 exhibited the best dilution potential (~10%, whereas alginic acid showed a very high value (~70%. In terms of performance, sorbitol, PVP-K30, Avicel PH-101, sodium alginate and pregelatinized starch were the most appropriate excipients for the direct compression of drugs.

  12. Effect of filler addition on the compressive and impact properties of ...

    Indian Academy of Sciences (India)

    Unknown

    Effect of filler addition on the compressive and impact properties of glass fibre reinforced epoxy. NIKHIL GUPTA*, BALRAJ SINGH BRAR† and EYASSU WOLDESENBET. Department of Mechanical Engineering, Louisiana State University, Baton Rouge, LA 70803, USA. †Baba Banda Singh Engineering College, Fateh Garh ...

  13. Measurements of the tensile and compressive properties of micro-concrete used in the Winfrith missile impact experiments

    International Nuclear Information System (INIS)

    Wilson, P.A.

    1982-10-01

    Tests to determine the tensile and compressive properties of a micro-concrete mix are described. The material is a nominally 40MPa ultimate compressive strength concrete used in impact tests with scale models in the prediction of responses in prototype concrete structures. Compressive tests were intended to give complete stress-strain relationships beyond initial failure. Tensile properties were measured by the Brazilian splitting technique and direct tension dog-bone specimens for comparison reasons. (U.K.)

  14. Densities and derived thermodynamic properties of binary (alkanol + boldine) mixtures in the compressed liquid region

    International Nuclear Information System (INIS)

    Durán-Zenteno, Moisés S.; Pérez-López, Hugo I.; Galicia-Luna, Luis A.; Elizalde-Solis, Octavio

    2012-01-01

    Highlights: ► We measured densities for {alkanol (ethanol or 1-propanol) + boldine} mixtures. ► Liquid densities are reported in the ranges of (1 to 20) MPa and (313 to 363) K. ► Thermodynamic derived properties were calculated using an empirical correlation. ► Extrapolated densities at atmospheric pressure agree with the literature data. - Abstract: In this work, densities of two binary systems of {alkanol (ethanol and 1-propanol) + boldine} are measured at temperatures from (313 to 363) K and pressures up to 20 MPa using an Anton Paar vibrating tube densimeter. Each (alkanol + boldine) system was prepared at five diluted compositions with respect to the alkaloid. These are (x 2 = 0.0012, 0.0074, 0.0136, 0.0196, 0.0267) and (x 2 = 0.0018, 0.0046, 0.0077, 0.0112, 0.0142) mixed in ethanol and 1-propanol, respectively. Experimental densities are correlated using an empirical 6-parameter equation with deviations within 0.04%. Extrapolated densities at atmospheric pressure agree with the literature data. Isobaric expansivity, isothermal compressibility, thermal pressure coefficient, and internal pressure have been calculated.

  15. Effect of Fe-Content on the Mechanical Properties of Recycled Al Alloys during Hot Compression

    Directory of Open Access Journals (Sweden)

    Hongzhou Lu

    2017-07-01

    Full Text Available It is unavoidable that Fe impurities will be mixed into Al alloys during recycling of automotive aluminum parts, and the Fe content has a significant effect on the mechanical properties of the recycled Al alloys. In this work, hot compression tests of two Fe-containing Al alloys were carried out at elevated temperatures within a wide strain rate range from 0.01 s−1 to 10 s−1. The effect of Fe content on the peak stress of the stress vs. strain curves, strain rate sensitivity and activation energy for dynamic recrystallization are analyzed. Results show that the recycled Al alloy containing 0.5 wt % Fe exhibits higher peak stresses and larger activation energy than the recycled Al alloy containing 0.1 wt % Fe, which results from the fact that there are more dispersed AlMgFeSi and/or AlFeSi precipitates in the recycled Al alloy containing 0.5 wt % Fe as confirmed by SEM observation and energy spectrum analysis. It is also shown that the Fe content has little effect on the strain rate sensitivity of the recycled Al alloys.

  16. The effect of compressed air massage on skin blood flow and temperature.

    Science.gov (United States)

    Mars, Maurice; Maharaj, Sunil S; Tufts, Mark

    2005-01-01

    Compressed air massage is a new treatment modality that uses air under pressure to massage skin and muscle. It is claimed to improve skin blood flow but this has not been verified. Several pilot studies were undertaken to determine the effects of compressed air massage on skin blood flow and temperature. Skin blood flow (SBF), measured using laser Doppler fluxmetry and skin temperature was recorded under several different situations: (i) treatment, at 1 Bar pressure using a single-hole (5-mm) applicator head, for 1 min at each of several sites on the right and left lower legs, with SBF measured on the dorsum of the left foot; (ii) at the same treatment pressure, SBF was measured over the left tibialis anterior when treatment was performed at different distances from the probe; (iii) SBF and skin temperature of the lower leg were measured with treatment at 0 or 1 Bar for 45 min, using two different applicator heads; (iv) SBF was measured on the dorsum of the foot of 10 subjects with treatment for 1 min at 0, 0.5, 1, 1.5 and 2 Bar using three different applicator heads. (i) SBF of the left foot was not altered by treatment of the right leg or chest, but was significantly increased during treatment of the left sole and first web, p Compressed air massage causes an immediate increase in SBF, and an immediate fall in SBF when treatment is stopped. The effect appears to be locally and not centrally mediated and is related to the pressure used. Treatment cools the skin for at least 15 min after a 45-min treatment.

  17. Fractal Characteristics of Rock Fracture Surface under Triaxial Compression after High Temperature

    Directory of Open Access Journals (Sweden)

    X. L. Xu

    2016-01-01

    Full Text Available Scanning Electron Microscopy (SEM test on 30 pieces of fractured granite has been researched by using S250MK III SEM under triaxial compression of different temperature (25~1000°C and confining pressure (0~40 MPa. Research results show that (1 the change of fractal dimension (FD of rock fracture with temperature is closely related to confining pressure, which can be divided into two categories. In the first category, when confining pressure is in 0~30 MPa, FD fits cubic polynomial fitting curve with temperature, reaching the maximum at 600°C. In the second category, when confining pressure is in 30~40 MPa, FD has volatility with temperature. (2 The FD of rock fracture varies with confining pressure and is also closely related to the temperature, which can be divided into three categories. In the first category, FD has volatility with confining pressure at 25°C, 400°C, and 800°C. In the second category, it increases exponentially at 200°C and 1000°C. In the third category, it decreases exponentially at 600°C. (3 It is found that 600°C is the critical temperature and 30 MPa is the critical confining pressure of granite. The rock transfers from brittle to plastic phase transition when temperature exceeds 600°C and confining pressure exceeds 30 MPa.

  18. Compressive Deformation Behavior of Thick Micro-Alloyed HSLA Steel Plates at Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Lee J.-H.

    2017-06-01

    Full Text Available The hot deformation behavior of a heavy micro-alloyed high-strength low-alloy (HSLA steel plate was studied by performing compression tests at elevated temperatures. The hot compression tests were carried out at temperatures from 923 K to 1,223 K with strain rates of 0.002 s−1 and 1.0 s−1. A long plateau region appeared for the 0.002 s−1 strain rate, and this was found to be an effect of the balancing between softening and hardening during deformation. For the 1.0 s−1 strain rate, the flow stress gradually increased after the yield point. The temperature and the strain rate-dependent parameters, such as the strain hardening coefficient (n, strength constant (K, and activation energy (Q, obtained from the flow stress curves were applied to the power law of plastic deformation. The constitutive model for flow stress can be expressed as σ = (39.8 ln (Z – 716.6 · ε(−0.00955ln(Z + 0.4930 for the 1.0 s−1 strain rate and σ = (19.9ln (Z – 592.3 · ε(−0.00212ln(Z + 0.1540 for the 0.002 s−1 strain rate.

  19. Impact of High Temperature Creep on the Buckling of Axially Compressed Steel Members

    Science.gov (United States)

    Włóka, Agata; Pawłowski, Kamil; Świerzko, Robert

    2017-10-01

    The paper presents results of the laboratory tests of the impact of creep on the buckling of axially compressed steel members at elevated temperatures. Tests were conducted on samples prepared of normal strength steel (S235JR) and high strength steel (S355J2). Samples were made in the form of a prismatic bar of a rectangular cross section 12 x 30 mm and a length of 500 mm. Support type of the specimens during tests was hinged on both ends. The tests were done at 600, 700 and 800°C. Experiments were carried out at static loads corresponding to values 0,8Ncr,T, 0,9Ncr,T, 1,0Ngr,T, where Ncr,T was theoretical value of Euler’s critical load at given temperature. Short-term creep analyses were performed in the universal testing machine Instron/Satec KN 600 equipped with a furnace for high-temperature testing type SF-16 2230, that enables testing at temperatures up to 1200°C. Temperature of the sample placed inside the furnace was verified and recorded with use of the compactRIO cRIO-9076 controller, equipped with a module for the connection of NI 9211 and K-type thermocouples. The system for the measurement and recording of the temperature of the analysed samples operated in the LabVIEW software environment. To measure lateral and longitudinal displacements LVTD Solatron ACR 100 displacement transducer was used. During the tests, the samples were heated to the given temperature (600, 700 or 800°C) and then subjected to a constant compressive load. During each test, for each sample following data was registered: the temperature on the surface of samples, longitudinal and lateral displacements in the middle of the sample. Basing on the conducted tests it was noted, for both analysed steel types, at the temperature of 800°C, growth of lateral displacements due to creep was very rapid, and tested elements were losing bearing capacity over the period of tens to hundreds of seconds, depending on stress level and the grade of the steel. At a temperature of 700°C growth

  20. Testing program for determining the mechanical properties of concrete to temperatures of 6210C

    International Nuclear Information System (INIS)

    Oland, C.B.; Naus, D.J.; Robinson, G.C.

    1980-01-01

    Concrete temperatures in a Liquid Metal Fast Breeder Reactor (LMFBR) in excess of normal code limits can result from postulated large sodium spills in equipment cells. Elevated temperature concrete property data which may have application for providing a basis for the design and evaluation of such postulated accident conditions is limited. Data thus needed to be developed commensurate with LMFBR plant applications for critical physical and mechanical concrete properties under prototypic thermal accident conditions. A test program was conducted to define the variations in physical and mechanical properties of a limestone aggregate concrete and a lightweight insulating concrete exposed to elevated temperatures. Five test series were conducted: unconfined compression, shear, rebar bond, sustained loading (creep), and thermal properties. Testing procedures for determining the mechanical properties of concrete from ambient to 621 0 C (1150 0 F) are described. Ther thermal properties tests are discussed in a separate paper which is also being presented at this conference

  1. Structural characteristics and elevated temperature mechanical properties of AJ62 Mg alloy

    International Nuclear Information System (INIS)

    Kubásek, J.; Vojtěch, D.; Martínek, M.

    2013-01-01

    Structure and mechanical properties of the novel casting AJ62 (Mg–6Al–2Sr) alloy developed for elevated temperature applications were studied. The AJ62 alloy was compared to commercial casting AZ91 (Mg–9Al–1Zn) and WE43 (Mg–4Y–3RE) alloys. The structure was examined by scanning electron microscopy, x-ray diffraction and energy dispersive spectrometry. Mechanical properties were characterized by Viskers hardness measurements in the as-cast state and after a long-term heat treatment at 250 °C/150 hours. Compressive mechanical tests were also carried out both at room and elevated temperatures. Compressive creep tests were conducted at a temperature of 250 °C and compressive stresses of 60, 100 and 140 MPa. The structure of the AJ62 alloy consisted of primary α-Mg dendrites and interdendritic nework of the Al 4 Sr and massive Al 3 Mg 13 Sr phases. By increasing the cooling rate during solidification from 10 and 120 K/s the average dendrite arm thickness decreased from 18 to 5 μm and the total volume fraction of the interdendritic phases from 20% to 30%. Both factors slightly increased hardness and compressive strength. The room temperature compressive strength and hardness of the alloy solidified at 30 K/s were 298 MPa and 50 HV 5, i.e. similar to those of the as-cast WE43 alloy and lower than those of the AZ91 alloy. At 250 °C the compressive strength of the AJ62 alloy decreased by 50 MPa, whereas those of the AZ91 and WE43 alloys by 100 and 20 MPa, respectively. The creep rate of the AJ62 alloy was higher than that of the WE43 alloy, but significantly lower in comparison with the AZ91 alloy. Different thermal stabilities of the alloys were discussed and related to structural changes during elevated temperature expositions. - Highlights: • Small effect of cooling rate on the compressive strength and hardness of AJ 62 • A bit lower compressive strength of AJ 62 compared to AZ91 at room temperature • Higher resistance of the AJ 62 alloy to the

  2. High Temperature Exposure of HPC – Experimental Analysis of Residual Properties and Thermal Response

    Directory of Open Access Journals (Sweden)

    Pavlík Zbyšek

    2016-01-01

    Full Text Available The effect of high temperature exposure on properties of a newly designed High Performance Concrete (HPC is studied in the paper. The HPC samples are exposed to the temperatures of 200, 400, 600, 800, and 1000°C respectively. Among the basic physical properties, bulk density, matrix density and total open porosity are measured. The mechanical resistivity against disruptive temperature action is characterised by compressive strength, flexural strength and dynamic modulus of elasticity. To study the chemical and physical processes in HPC during its high-temperature exposure, Simultaneous Thermal Analysis (STA is performed. Linear thermal expansion coefficient is determined as function of temperature using thermodilatometry (TDA. In order to describe the changes in microstructure of HPC induced by high temperature loading, MIP measurement of pore size distribution is done. Increase of the total open porosity and connected decrease of the mechanical parameters for temperatures higher than 200 °C were identified.

  3. Effect of Curing Temperature Histories on the Compressive Strength Development of High-Strength Concrete

    Directory of Open Access Journals (Sweden)

    Keun-Hyeok Yang

    2015-01-01

    Full Text Available This study examined the relative strength-maturity relationship of high-strength concrete (HSC specifically developed for nuclear facility structures while considering the economic efficiency and durability of the concrete. Two types of mixture proportions with water-to-binder ratios of 0.4 and 0.28 were tested under different temperature histories including (1 isothermal curing conditions of 5°C, 20°C, and 40°C and (2 terraced temperature histories of 20°C for an initial age of individual 1, 3, or 7 days and a constant temperature of 5°C for the subsequent ages. On the basis of the test results, the traditional maturity function of an equivalent age was modified to consider the offset maturity and the insignificance of subsequent curing temperature after an age of 3 days on later strength of concrete. To determine the key parameters in the maturity function, the setting behavior, apparent activation energy, and rate constant of the prepared mixtures were also measured. This study reveals that the compressive strength development of HSC cured at the reference temperature for an early age of 3 days is insignificantly affected by the subsequent curing temperature histories. The proposed maturity approach with the modified equivalent age accurately predicts the strength development of HSC.

  4. Analysis of three-point-bend test for materials with unequal tension and compression properties

    Science.gov (United States)

    Chamis, C. C.

    1974-01-01

    An analysis capability is described for the three-point-bend test applicable to materials of linear but unequal tensile and compressive stress-strain relations. The capability consists of numerous equations of simple form and their graphical representation. Procedures are described to examine the local stress concentrations and failure modes initiation. Examples are given to illustrate the usefulness and ease of application of the capability. Comparisons are made with materials which have equal tensile and compressive properties. The results indicate possible underestimates for flexural modulus or strength ranging from 25 to 50 percent greater than values predicted when accounting for unequal properties. The capability can also be used to reduce test data from three-point-bending tests, extract material properties useful in design from these test data, select test specimen dimensions, and size structural members.

  5. The Microstructural Evolution and Mechanical Properties of Zr-Based Metallic Glass under Different Strain Rate Compressions.

    Science.gov (United States)

    Chen, Tao-Hsing; Tsai, Chih-Kai

    2015-04-16

    In this study, the high strain rate deformation behavior and the microstructure evolution of Zr-Cu-Al-Ni metallic glasses under various strain rates were investigated. The influence of strain and strain rate on the mechanical properties and fracture behavior, as well as microstructural properties was also investigated. Before mechanical testing, the structure and thermal stability of the Zr-Cu-Al-Ni metallic glasses were studied with X-ray diffraction (XRD) and differential scanning calorimeter. The mechanical property experiments and microstructural observations of Zr-Cu-Al-Ni metallic glasses under different strain rates ranging from 10 -3 to 5.1 × 10³ s -1 and at temperatures of 25 °C were investigated using compressive split-Hopkinson bar (SHPB) and an MTS tester. An in situ transmission electron microscope (TEM) nanoindenter was used to carry out compression tests and investigate the deformation behavior arising at nanopillars of the Zr-based metallic glass. The formation and interaction of shear band during the plastic deformation were investigated. Moreover, it was clearly apparent that the mechanical strength and ductility could be enhanced by impeding the penetration of shear bands with reinforced particles.

  6. The Microstructural Evolution and Mechanical Properties of Zr-Based Metallic Glass under Different Strain Rate Compressions

    Directory of Open Access Journals (Sweden)

    Tao-Hsing Chen

    2015-04-01

    Full Text Available In this study, the high strain rate deformation behavior and the microstructure evolution of Zr-Cu-Al-Ni metallic glasses under various strain rates were investigated. The influence of strain and strain rate on the mechanical properties and fracture behavior, as well as microstructural properties was also investigated. Before mechanical testing, the structure and thermal stability of the Zr-Cu-Al-Ni metallic glasses were studied with X-ray diffraction (XRD and differential scanning calorimeter. The mechanical property experiments and microstructural observations of Zr-Cu-Al-Ni metallic glasses under different strain rates ranging from 10−3 to 5.1 × 103 s−1 and at temperatures of 25 °C were investigated using compressive split-Hopkinson bar (SHPB and an MTS tester. An in situ transmission electron microscope (TEM nanoindenter was used to carry out compression tests and investigate the deformation behavior arising at nanopillars of the Zr-based metallic glass. The formation and interaction of shear band during the plastic deformation were investigated. Moreover, it was clearly apparent that the mechanical strength and ductility could be enhanced by impeding the penetration of shear bands with reinforced particles.

  7. Comparison of mechanical compressive properties of commercial and autologous fibrin glues for tissue engineering applications.

    Science.gov (United States)

    Cravens, Matthew G; Behn, Anthony W; Dragoo, Jason L

    2017-11-01

    Fibrin glues are widely used in orthopedic surgery as adhesives and hemostatic agents. We evaluated the compressive properties of selected fibrin glues in order to identify which are appropriate for tissue regeneration applications subject to compression. Uniaxial unconfined compression tests were performed on fibrin gels prepared from commercial and autologous products: (1) Evicel (Ethicon), (2) Tisseel (Baxter), (3) Angel (Arthrex), and (4) ProPlaz (Biorich). Cyclic loads were applied from 0 to 30% strain for 100cycles at 0.5Hz. Following cyclic testing, specimens were subjected to ramp displacement of 1% strain per second to 80% strain. Throughout cyclic loading, Evicel and Tisseel deformed (shortened) less than Angel at all but one time point, and deformed less than ProPlaz at cycles 10 and 20. The dynamic moduli, peak stress, and strain energy were significantly greater in Tisseel than all other groups. Evicel displayed significantly greater dynamic moduli, peak stress, and strain energy than Angel and ProPlaz. Following cyclic testing, Tisseel and Evicel were significantly less deformed than Angel. No specimens exhibited gross failure during ramp loading to 80% strain. Ramp loading trends mirrored those of cyclic loading. The tested commercial glues were significantly more resistant to compression than the autologous products. The compressive properties of Tisseel were approximately twice those of Evicel. All preparations displayed moduli multiple orders of magnitude less than that of native articular cartilage. We conclude that in knee surgeries requiring fibrin glue to undergo compression of daily activity, commercial products are preferable to autologous preparations from platelet-poor plasma, though both will deform significantly. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Integrated LTCC Pressure/Flow/Temperature Multisensor for Compressed Air Diagnostics†

    Directory of Open Access Journals (Sweden)

    Nicolas Craquelin

    2010-12-01

    Full Text Available We present a multisensor designed for industrial compressed air diagnostics and combining the measurement of pressure, flow, and temperature, integrated with the corresponding signal conditioning electronics in a single low-temperature co-fired ceramic (LTCC package. The developed sensor may be soldered onto an integrated electro-fluidic platform by using standard surface mount device (SMD technology, e.g., as a standard electronic component would be on a printed circuit board, obviating the need for both wires and tubes and thus paving the road towards low-cost integrated electro-fluidic systems. Several performance aspects of this device are presented and discussed, together with electronics design issues.

  9. A review on the recent development of solar absorption and vapour compression based hybrid air conditioning with low temperature storage

    Directory of Open Access Journals (Sweden)

    Noor D. N.

    2016-01-01

    Full Text Available Conventional air conditioners or vapour compression systems are main contributors to energy consumption in modern buildings. There are common environmental issues emanating from vapour compression system such as greenhouse gas emission and heat wastage. These problems can be reduced by adaptation of solar energy components to vapour compression system. However, intermittence input of daily solar radiation was the main issue of solar energy system. This paper presents the recent studies on hybrid air conditioning system. In addition, the basic vapour compression system and components involved in the solar air conditioning system are discussed. Introduction of low temperature storage can be an interactive solution and improved economically which portray different modes of operating strategies. Yet, very few studies have examined on optimal operating strategies of the hybrid system. Finally, the findings of this review will help suggest optimization of solar absorption and vapour compression based hybrid air conditioning system for future work while considering both economic and environmental factors.

  10. The effects of heating temperatures and time on deformation energy and oil yield of sunflower bulk seeds in compression loading

    Science.gov (United States)

    Kabutey, A.; Herak, D.; Sigalingging, R.; Demirel, C.

    2018-02-01

    The deformation energy (J) and percentage oil yield (%) of sunflower bulk seeds under the influence of heat treatment temperatures and heating time were examined in compression test using the universal compression testing machine and vessel diameter of 60 mm with a plunger. The heat treatment temperatures were between 40 and 100 °C and the heating time at specific temperatures of 40 and 100 °C ranged from 15 to 75 minutes. The bulk sunflower seeds were measured at a pressing height of 60 mm and pressed at a maximum force of 100 kN and speed of 5 mm/min. Based on the compression results, the deformation energy and oil yield increased along with increasing heat treatment temperatures. The results were statistically significant (p 0.05).

  11. Effects of Elevated Temperatures on the Compressive Strength Capacity of Concrete Cylinders Confined with FRP Sheets: An Experimental Investigation

    Directory of Open Access Journals (Sweden)

    Sherif El-Gamal

    2015-01-01

    Full Text Available Due to their high strength, corrosion resistance, and durability, fiber reinforced polymers (FRP are very attractive for civil engineering applications. One of these applications is the strengthening of concrete columns with FRP sheets. The performance of this strengthening technique at elevated temperature is still questionable and needs more investigations. This research investigates the effects of exposure to high temperatures on the compressive strength of concrete cylinders wrapped with glass and carbon FRP sheets. Test specimens consisted of 30 unwrapped and 60 wrapped concrete cylinders. All specimens were exposed to temperatures of 100, 200, and 300°C for periods of 1, 2, and 3 hours. The compressive strengths of the unwrapped concrete cylinders were compared with their counterparts of the wrapped cylinders. For the unwrapped cylinders, test results showed that the elevated temperatures considered in this study had almost no effect on their compressive strength; however, the wrapped specimens were significantly affected, especially those wrapped with GFRP sheets. The compressive strength of the wrapped specimens decreased as the exposure period and the temperature level increased. After three hours of exposure to 300°C, a maximum compressive strength loss of about 25.3% and 37.9%, respectively, was recorded in the wrapped CFRP and GFRP specimens.

  12. Absolute calibration of the OMEGA streaked optical pyrometer for temperature measurements of compressed materials.

    Science.gov (United States)

    Gregor, M C; Boni, R; Sorce, A; Kendrick, J; McCoy, C A; Polsin, D N; Boehly, T R; Celliers, P M; Collins, G W; Fratanduono, D E; Eggert, J H; Millot, M

    2016-11-01

    Experiments in high-energy-density physics often use optical pyrometry to determine temperatures of dynamically compressed materials. In combination with simultaneous shock-velocity and optical-reflectivity measurements using velocity interferometry, these experiments provide accurate equation-of-state data at extreme pressures (P > 1 Mbar) and temperatures (T > 0.5 eV). This paper reports on the absolute calibration of the streaked optical pyrometer (SOP) at the Omega Laser Facility. The wavelength-dependent system response was determined by measuring the optical emission from a National Institute of Standards and Technology-traceable tungsten-filament lamp through various narrowband (40-nm-wide) filters. The integrated signal over the SOP's ∼250-nm operating range is then related to that of a blackbody radiator using the calibrated response. We present a simple closed-form equation for the brightness temperature as a function of streak-camera signal derived from this calibration. Error estimates indicate that brightness temperature can be inferred to a precision of <5%.

  13. Absolute calibration of the OMEGA streaked optical pyrometer for temperature measurements of compressed materials

    Science.gov (United States)

    Gregor, M. C.; Boni, R.; Sorce, A.; Kendrick, J.; McCoy, C. A.; Polsin, D. N.; Boehly, T. R.; Celliers, P. M.; Collins, G. W.; Fratanduono, D. E.; Eggert, J. H.; Millot, M.

    2016-11-01

    Experiments in high-energy-density physics often use optical pyrometry to determine temperatures of dynamically compressed materials. In combination with simultaneous shock-velocity and optical-reflectivity measurements using velocity interferometry, these experiments provide accurate equation-of-state data at extreme pressures (P > 1 Mbar) and temperatures (T > 0.5 eV). This paper reports on the absolute calibration of the streaked optical pyrometer (SOP) at the Omega Laser Facility. The wavelength-dependent system response was determined by measuring the optical emission from a National Institute of Standards and Technology-traceable tungsten-filament lamp through various narrowband (40-nm-wide) filters. The integrated signal over the SOP's ˜250-nm operating range is then related to that of a blackbody radiator using the calibrated response. We present a simple closed-form equation for the brightness temperature as a function of streak-camera signal derived from this calibration. Error estimates indicate that brightness temperature can be inferred to a precision of <5%.

  14. On the identification of the eggshell elastic properties under quasistatic compression

    Directory of Open Access Journals (Sweden)

    Jana Simeonovová

    2004-01-01

    Full Text Available The problem of the identification of the elastic properties of eggshell, i.e. the evaluation of the Young's modulus and Poisson's ratio is solved. The eggshell is considered as a rotational shell. The experiments on the egg compression under quasistatic loading have been conducted. During these experiments a strain on the eggshell surface has been recorded. By the mutual comparison between experimental and theoretical values of strains the influence of the elastic constants has been demonstrated.

  15. Consideration of critical axial properties of pristine and defected carbon nanotubes under compression.

    Science.gov (United States)

    Ranjbartoreh, A R; Su, D; Wang, G

    2012-06-01

    Carbon nanotubes are hexagonally configured carbon atoms in cylindrical structures. Exceptionally high mechanical strength, electrical conductivity, surface area, thermal stability and optical transparency of carbon nanotubes outperformed other known materials in numerous advanced applications. However, their mechanical behaviors under practical loading conditions remain to be demonstrated. This study investigates the critical axial properties of pristine and defected single- and multi-walled carbon nanotubes under axial compression. Molecular dynamics simulation method has been employed to consider the destructive effects of Stone-Wales and atom vacancy defects on mechanical properties of armchair and zigzag carbon nanotubes under compressive loading condition. Armchair carbon nanotube shows higher axial stability than zigzag type. Increase in wall number leads to less susceptibility of multi-walled carbon nanotubes to defects and higher stability of them under axial compression. Atom vacancy defect reveals higher destructive effect than Stone-Wales defect on mechanical properties of carbon nanotubes. Critical axial strain of single-walled carbon nanotube declines by 67% and 26% due to atom vacancy and Stone-Wales defects.

  16. Physical properties of compressive knits compound with different matters impregnated by microcapsules moisturizing

    Directory of Open Access Journals (Sweden)

    Fadhel Jaâfar

    2011-01-01

    Full Text Available The compressive knits include a very varied group of different device functions, from the more merely (protection to the more developed (scars improvement, skin hydration…. We combined two therapy forms the pressure and the hydration of burned skin. We essayed to reunite the advantages of two techniques pressure and hydration in only one and the same instrument in the form of compressive knit with microencapsulated surface. The compressive knits are elaborated with different textile matters such us Cotton/Spandex, Polyester/Spandex, Polyamide/Spandex, Viscose/Spandex and Cotton/Polyester/Spandex. The hydration product chosen in this application is the Jojoba Oil. The microcapsules were prepared according to the Phase Separation Method. The physical properties such us the Pressure, the Mass per Area, the Thickness, the Air Permeability and the Adiathermic Power are tested. According to the results, we conclude that the knits are compressive, comfort, smooth, no allergen, thinness and washable. The raw materials selected for the samples studied are biocompatible with human skin.

  17. Evaluation on Compression Properties of Different Shape and Perforated rHDPE in Concrete Structures

    Science.gov (United States)

    Yuhazri, M. Y.; Hafiz, K. M.; Myia, Y. Z. A.; Jia, C. P.; Sihombing, H.; Sapuan, S. M.; Badarulzaman, N. A.

    2017-10-01

    The purpose of this study was to develop a concrete structure by incorporating waste HDPE plastic as the main reinforcement material and cement as the matrix via standard casting technique. There are eight different shapes of rHDPE reinforcing structure were used to investigate the compression properties of produced concrete composites. Experimental result shown that the highest shape in compressive strength of rHDPE reinforcing structure were the concrete with the addition of X-perforated beam (18.22 MPa), followed by X-beam (17.7 MPa), square perforated tube (17.54 MPa), round tube (17.42 MPa) and round perforated tube (16.69 MPa). In terms of their compressive behavior, the average concrete containing rHDPE reinforcement was successfully improved by 6 % of the mechanical characteristic compared to control concrete. It is shown that the addition of waste plastic as reinforcement structure can provide better compressive strength based on their shape and pattern respectively.

  18. High throughput dual-wavelength temperature distribution imaging via compressive imaging

    Science.gov (United States)

    Yao, Xu-Ri; Lan, Ruo-Ming; Liu, Xue-Feng; Zhu, Ge; Zheng, Fu; Yu, Wen-Kai; Zhai, Guang-Jie

    2018-03-01

    Thermal imaging is an essential tool in a wide variety of research areas. In this work we demonstrate high-throughput double-wavelength temperature distribution imaging using a modified single-pixel camera without the requirement of a beam splitter (BS). A digital micro-mirror device (DMD) is utilized to display binary masks and split the incident radiation, which eliminates the necessity of a BS. Because the spatial resolution is dictated by the DMD, this thermal imaging system has the advantage of perfect spatial registration between the two images, which limits the need for the pixel registration and fine adjustments. Two bucket detectors, which measures the total light intensity reflected from the DMD, are employed in this system and yield an improvement in the detection efficiency of the narrow-band radiation. A compressive imaging algorithm is utilized to achieve under-sampling recovery. A proof-of-principle experiment was presented to demonstrate the feasibility of this structure.

  19. A Review on Homogeneous Charge Compression Ignition and Low Temperature Combustion by Optical Diagnostics

    Directory of Open Access Journals (Sweden)

    Chao Jin

    2015-01-01

    Full Text Available Optical diagnostics is an effective method to understand the physical and chemical reaction processes in homogeneous charge compression ignition (HCCI and low temperature combustion (LTC modes. Based on optical diagnostics, the true process on mixing, combustion, and emissions can be seen directly. In this paper, the mixing process by port-injection and direct-injection are reviewed firstly. Then, the combustion chemical reaction mechanism is reviewed based on chemiluminescence, natural-luminosity, and laser diagnostics. After, the evolution of pollutant emissions measured by different laser diagnostic methods is reviewed and the measured species including NO, soot, UHC, and CO. Finally, a summary and the future directions on HCCI and LTC used optical diagnostics are presented.

  20. Analysis of temperatures during the firing bricks and final properties solid

    Directory of Open Access Journals (Sweden)

    Gustavo Guerrero Gómez

    2017-01-01

    Full Text Available Context: Since the estructural behavior of the walls in a building directly depends on the properties of the blocks used, these properties are very important. In particular, the final properties of a ceramic block (often used in masonry depend on the cooking temperature of the pulp. Objective: The purpose of this research is to determine the relationship between the final properties of a ceramic block and the temperature at which it was cooked. Additionally, it is wroth considering how quickly these temperatures vary in the kiln. Method: In first place, a system based on Labview was used to record the temperatures in the oven. In second place, it was considered the temperature increasing rate according to the ideal curve for baking blocks, which was classified inside the oven. In third place, samples of the product were taken according to the technical norms NTC 4017 and NTC 4205 in order to determine the properties of the block. Results: According to the samples, we determined: the Initial absorption of water (TIA, the absorption rate at 24 hours of immersion, the compressive strength, and the Modulus of Rupture (MR. Additionally, applying a multiple linear regression analysis, it was found a relationship between the TIA, the temperature increase rate, and the MR. Conclusions: From the results in the research, it is possible to conclude that: blocks baked at more than 1000 °C have the highest modulus of rupture (1.54 MPa; however, it was found that blocks baked at lower temperature presented the highest initial absorption rate (0.37 gr/cm2/min and the best compressive strength (7.28 MPa. Finally, since the temperature and time are not controlled during the baking process, it is difficult for properties to be the most suitable.

  1. On the critical temperature discontinuity at the theoretical bcc-fcc phase transition in compressed selenium and tellurium superconductors

    Science.gov (United States)

    Szczęśniak, D.; Wrona, I. A.; Drzazga, E. A.; Kaczmarek, A. Z.; Szewczyk, K. A.

    2017-11-01

    Recent hydrides-driven advent in the high-pressure phonon-mediated superconductivity motivates research on chemical elements which compound with hydrogen. It is desired that such elements should allow chemical pre-compression of hydrogen to assure the induction of the superconducting phase with the high transition temperature (T C). Herein, we present detailed theoretical insight into the properties of the superconducting state induced under pressure (p) in two of such component elements, namely selenium (Se) and tellurium (Te) at p=250 GPa and p=70 GPa, respectively. The assumed external pressure conditions allow us to conduct our analysis just above previously theoretically predicted bcc-fcc structural phase transition of Se and Te, and identify the possible associated discontinuity effect of the critical temperature. In particular, our numerical analysis is conducted within Migdal-Eliashberg formalism, due to the confirmed electron-phonon pairing mechanism and relatively high electron-phonon coupling constant in the materials of interest. We predict that T C values in Se and Te equal 8.13 K and 5.96 K, respectively, and mark the highest critical temperature values for these elements within the postulated fcc phase. Additionally, we supplement these results by the estimated maximum values of the superconducting energy band gap and the effective mass of electrons. We predict that all these parameters can be used as a guidelines for experimental observation of the critical temperature discontinuity and the corresponding bcc-fcc phase transition in Se and Te superconductors. Moreover, we show that the thermodynamics of superconducting phase in both elements may exhibit deviations from the conventional estimates of the Bardeen-Cooper-Schrieffer theory, and suggest existence of the strong-coupling and retardation effects. Finally, we note that our results can be also instructive for future screening of chemical elements for applications in superconducting hydrides.

  2. Computer codes used in the calculation of high-temperature thermodynamic properties of sodium

    Energy Technology Data Exchange (ETDEWEB)

    Fink, J.K.

    1979-12-01

    Three computer codes - SODIPROP, NAVAPOR, and NASUPER - were written in order to calculate a self-consistent set of thermodynamic properties for saturated, subcooled, and superheated sodium. These calculations incorporate new critical parameters (temperature, pressure, and density) and recently derived single equations for enthalpy and vapor pressure. The following thermodynamic properties have been calculated in these codes: enthalpy, heat capacity, entropy, vapor pressure, heat of vaporization, density, volumetric thermal expansion coefficient, compressibility, and thermal pressure coefficient. In the code SODIPROP, these properties are calculated for saturated and subcooled liquid sodium. Thermodynamic properties of saturated sodium vapor are calculated in the code NAVAPOR. The code NASUPER calculates thermodynamic properties for super-heated sodium vapor only for low (< 1644 K) temperatures. No calculations were made for the supercritical region.

  3. Computer codes used in the calculation of high-temperature thermodynamic properties of sodium

    International Nuclear Information System (INIS)

    Fink, J.K.

    1979-12-01

    Three computer codes - SODIPROP, NAVAPOR, and NASUPER - were written in order to calculate a self-consistent set of thermodynamic properties for saturated, subcooled, and superheated sodium. These calculations incorporate new critical parameters (temperature, pressure, and density) and recently derived single equations for enthalpy and vapor pressure. The following thermodynamic properties have been calculated in these codes: enthalpy, heat capacity, entropy, vapor pressure, heat of vaporization, density, volumetric thermal expansion coefficient, compressibility, and thermal pressure coefficient. In the code SODIPROP, these properties are calculated for saturated and subcooled liquid sodium. Thermodynamic properties of saturated sodium vapor are calculated in the code NAVAPOR. The code NASUPER calculates thermodynamic properties for super-heated sodium vapor only for low (< 1644 K) temperatures. No calculations were made for the supercritical region

  4. Electrical transport properties of AlAs under compression: reversible boundary effect.

    Science.gov (United States)

    Yan, Jiejuan; Ke, Feng; Liu, Cailong; Wang, Qinglin; Zhang, Junkai; Wang, Li; Peng, Gang; Han, Yonghao; Ma, Yanzhang; Gao, Chunxiao

    2015-10-21

    Herein, we report on the intriguing electrical transport properties of compressed AlAs. The relative permittivity and the resistances of both the grain and bulk boundaries vary abnormally at ∼10.9 GPa, accompanied by the cubic-hexagonal structural transition of AlAs. With further compression, the boundary effect becomes undistinguished, and subsequently, the electrical transport mechanism converts from boundary- to bulk-dominated, which gives rise to a significant reduction in the total resistance of AlAs. After being quenched to ambient pressure, resistances recover to the initial values followed by the re-emergence of the boundary effect. Eg decreases with pressure and its pressure dependence changes at ∼14.0 GPa, which rationalizes the anomalous variation of the electrical transport properties. The experimental results indicate that the boundary effect can be modulated by compression and increases the resistance difference between the two states. This opens up a new possible basis for optimizing the performance of AlAs-based applications, including multilevel phase-change memories.

  5. Mechanical properties in crumple-formed paper derived materials subjected to compression

    Directory of Open Access Journals (Sweden)

    D.A.H. Hanaor

    2017-06-01

    Full Text Available The crumpling of precursor materials to form dense three dimensional geometries offers an attractive route towards the utilisation of minor-value waste materials. Crumple-forming results in a mesostructured system in which mechanical properties of the material are governed by complex cross-scale deformation mechanisms. Here we investigate the physical and mechanical properties of dense compacted structures fabricated by the confined uniaxial compression of a cellulose tissue to yield crumpled mesostructuring. A total of 25 specimens of various densities were tested under compression. Crumple formed specimens exhibited densities in the range 0.8–1.3 g cm−3, and showed high strength to weight characteristics, achieving ultimate compressive strength values of up to 200 MPa under both quasi-static and high strain rate loading conditions and deformation energy that compares well to engineering materials of similar density. The materials fabricated in this work and their mechanical attributes demonstrate the potential of crumple-forming approaches in the fabrication of novel energy-absorbing materials from low-cost precursors such as recycled paper. Stiffness and toughness of the materials exhibit density dependence suggesting this forming technique further allows controllable impact energy dissipation rates in dynamic applications.

  6. Mechanical and Thermophysical Properties of Cement and/or Paper (Cellulose Stabilized Compressed Clay Bricks

    Directory of Open Access Journals (Sweden)

    Emmanuel OUEDRAOGO

    2015-05-01

    Full Text Available This article presents an experimental study of the characterization of clay blocks stabilized with cement and/or recycled papers as construction materials. When they are utilized as finish for building envelops, they must have appropriate mechanical strength and water stability. The measurements of the mechanical and thermophysical properties show differences between the properties of four investigated specimens. Mechanical properties such as compression and tensile tresses of clay-cement and clay-cement-paper mixtures are found to be quite similar but are two to three times greater respectively for clay-paper and purely clay blocks. The values of the thermophysical properties of blocks incorporating paper show improvement of their thermo insulation performances.

  7. Analysis of optical properties in injection-molded and compression-molded optical lenses.

    Science.gov (United States)

    Wang, Chung Yen; Wang, Pei Jen

    2014-04-10

    Numerical mold-flow simulations and experimental measurements for injection-molded lenses have been investigated in form accuracy on a two-cavity mold with various process conditions. First, form profiles of the molded lenses have been measured together with the corresponding simulated mold-temperature distribution and displacement distribution of the lens in the z direction. A flow-through type layout of cooling channels has been devised for balance of mold-temperature distribution in mold cavities with various parametric distances for assessments in uniformity of temperature distribution. Finally, a compression-molding process is proposed for the post-process of birefringence relaxation as well as adequate form accuracy of lenses. In conclusion, optimization of process parameters to achieve good form accuracy in a multicavity mold with symmetric geometry but nonuniform cooling conditions is difficult. A good design of cooling channels plus optimized process conditions could provide uniform mold-temperature distribution so that molded lenses of good quality would be possible. Then, the profile deviation of lenses could be further compensated by profile geometry corrections. In conclusion, the post-compression-molding process could make birefringence-free plastic lenses with good form accuracy.

  8. Potential petrophysical and chemical property alterations in a compressed air energy storage porous rock reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Stottlemyre, J.A.; Erikson, R.L.; Smith, R.P.

    1979-10-01

    Successful commercialization of Compressed Air Energy Storage (CAES) systems depends on long-term stability of the underground reservoirs subjected to somewhat unique operating conditions. Specifically, these conditions include elevated and time varying temperatures, effective stresses, and air humidities. To minimize the requirements for premium fuels, it may be desirable to retain the thermal energy of compression. Porous media, e.g., sandstone, may hold promise as elevated temperature reservoirs. In this study, a reservoir composed of clean quartz sandstone and injection air temperatures of 300 to 575/sup 0/K are assumed. Numerical modeling is used to estimate temperature, stress, and humidity conditions within this reference porous media reservoir. A discussion on relative importance to CAES of several potential porous media damage mechanisms is presented. In this context, damage is defined as a reduction in intrinsic permeability (measure of air transport capability), a decrease in effective porosity (measure of storage capability), or an increase in elastic and/or inelastic deformation of the porous material. The potential damage mechanisms presented include: (1) disaggregation, (2) particulate plugging, (3) boundary layer viscosity anomalies, (4) inelastic microstructural consolidation, (5) clay swelling and dispersion, (6) hydrothermal mineral alteration, (7) oxidation reactions, and (8) well casing corrosion. These mechanisms are placed in perspective with respect to anticipated CAES conditions and mechanisms suggested are: (1) of academic interest only, (2) readily identified and controlled via engineering, or (3) potential problem areas requiring additional investigation.

  9. Effect of mineral admixtures on kinetic property and compressive strength of self Compacting Concrete

    Science.gov (United States)

    Jagalur Mahalingasharma, Srishaila; Prakash, Parasivamurthy; Vishwanath, K. N.; Jawali, Veena

    2017-06-01

    This paper presents experimental investigations made on the influence of chemical, physical, morphological and mineralogical properties of mineral admixtures such as fly ash, ground granulate blast furnace slag, metakaoline and micro silica used as a replacement of cement in self compacting concrete on workability and compressive strength. Nineteen concrete mixes were cast by replacing with cement by fly ash or ground granulated blast furnace slag as binary blend at 30%, 40%, 50% and with addition of micro silica and metakaoline at 10% as a ternary blend with fly ash, ground granulated blast furnace slag and obtained results were compare with control mix. Water powder ratio 0.3 and super plasticizer dosage 1% of cementitious material was kept constant for all the mixes. The self compacting concrete tested for slump flow, V-funnel, L-Box, J-Ring, T50, and compressive strength on concrete cube were determined at age of 3, 7, 28, 56, 90 days.

  10. Macroscopic Expressions of Molecular Adiabatic Compressibility of Methyl and Ethyl Caprate under High Pressure and High Temperature

    Directory of Open Access Journals (Sweden)

    Fuxi Shi

    2014-01-01

    Full Text Available The molecular compressibility, which is a macroscopic quantity to reveal the microcompressibility by additivity of molecular constitutions, is considered as a fixed value for specific organic liquids. In this study, we introduced two calculated expressions of molecular adiabatic compressibility to demonstrate its pressure and temperature dependency. The first one was developed from Wada’s constant expression based on experimental data of density and sound velocity. Secondly, by introducing the 2D fitting expressions and their partial derivative of pressure and temperature, molecular compressibility dependency was analyzed further, and a 3D fitting expression was obtained from the calculated data of the first one. The third was derived with introducing the pressure and temperature correction factors based on analogy to Lennard-Jones potential function and energy equipartition theorem. In wide range of temperatures (293temperature of molecular compressibility was certified.

  11. Effect of fiber orientation on tensile and impact properties of Zalacca Midrib fiber-HDPE composites by compression molding

    Science.gov (United States)

    Lasikun, Ariawan, Dody; Surojo, Eko; Triyono, Joko

    2018-02-01

    The research aims to investigate the fiber orientation effect on the tensile and impact properties of zalacca midrib fiber /HDPE composites. The composites were produced by compression molding with pressing temperature at 150°C, pressing pressure at 50 bar, and holding time of 25 minutes. The fiber orientations applied in composites were 0°, 15°, 30°, 45°, 60°, 75°, and 90°, at 10% fiber volume fraction. The samples were evaluated by using: Tensile test and Izod impact test according to ASTM D638 and ASTM D5941, respectively. The result of experiments indicate that the orientation of zalacca midrib fiber influences the characteristics of HDPE composite-zalacca midrib fiber. The composite mechanical strength decline with the increase of orientation fibers from 0° to 90°. The composite failure mode of composites are observed by Scanning Electron Microscope (SEM).

  12. Hot Ductility and Compression Deformation Behavior of TRIP980 at Elevated Temperatures

    Science.gov (United States)

    Zhang, Mei; Li, Haiyang; Gan, Bin; Zhao, Xue; Yao, Yi; Wang, Li

    2018-02-01

    The hot ductility tests of a kind of 980 MPa class Fe-0.31C (wt pct) TRIP steel (TRIP980) with the addition of Ti/V/Nb were conducted on a Gleeble-3500 thermomechanical simulator in the temperatures ranging from 873 K to 1573 K (600 °C to 1300 °C) at a constant strain rate of 0.001 s-1. It is found that the hot ductility trough ranges from 873 K to 1123 K (600 °C to 850 °C). The recommended straightening temperatures are from 1173 K to 1523 K (900 °C to 1250 °C). The isothermal hot compression deformation behavior was also studied by means of Gleeble-3500 in the temperatures ranging from 1173 K to 1373 K (900 °C to 1100 °C) at strain rates ranging from 0.01 s-1 to 10 s-1. The results show that the peak stress decreases with the increasing temperature and the decreasing strain rate. The deformation activation energy of the test steel is 436.7 kJ/mol. The hot deformation equation of the steel has been established, and the processing maps have been developed on the basis of experimental data and the principle of dynamic materials model (DMM). By analyzing the processing maps of strains of 0.5, 0.7, and 0.9, it is found that dynamic recrystallization occurs in the peak power dissipation efficiency domain, which is the optimal area of hot working. Finally, the factors influencing hot ductility and thermal activation energy of the test steel were investigated by means of microscopic analysis. It indicates that the additional microalloying elements play important roles both in the loss of hot ductility and in the enormous increase of deformation activation energy for the TRIP980 steel.

  13. Comparison of the biomechanical tensile and compressive properties of decellularised and natural porcine meniscus.

    Science.gov (United States)

    Abdelgaied, A; Stanley, M; Galfe, M; Berry, H; Ingham, E; Fisher, J

    2015-06-01

    Meniscal repair is widely used as a treatment for meniscus injury. However, where meniscal damage has progressed such that repair is not possible, approaches for partial meniscus replacement are now being developed which have the potential to restore the functional role of the meniscus, in stabilising the knee joint, absorbing and distributing stress during loading, and prevent early degenerative joint disease. One attractive potential solution to the current lack of meniscal replacements is the use of decellularised natural biological scaffolds, derived from xenogeneic tissues, which are produced by treating the native tissue to remove the immunogenic cells. The current study investigated the effect of decellularisation on the biomechanical tensile and compressive (indentation and unconfined) properties of the porcine medial meniscus through an experimental-computational approach. The results showed that decellularised medial porcine meniscus maintained the tensile biomechanical properties of the native meniscus, but had lower tensile initial elastic modulus. In compression, decellularised medial porcine meniscus generally showed lower elastic modulus and higher permeability compared to that of the native meniscus. These changes in the biomechanical properties, which ranged from less than 1% to 40%, may be due to the reduction of glycosaminoglycans (GAG) content during the decellularisation process. The predicted biomechanical properties for the decellularised medial porcine meniscus were within the reported range for the human meniscus, making it an appropriate biological scaffold for consideration as a partial meniscus replacement. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  14. Properties of graphite-composite bipolar plate prepared by compression molding technique for PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Dhakate, S.R.; Mathur, R.B.; Dhami, T.L. [National Physical Laboratory, New Delhi (India). Engineering Material Division, Carbon Technology Unit; Kakati, B.K. [Tezpur University, Assam (India). Department of Energy

    2007-12-15

    Bipolar plate is an important key component of fuel cell on the basis of its manifold function. In this direction a lot of effort is going on worldwide to make light-weight and cost-effective bipolar plate for fuel cell application. In the present investigation effort was made to develop graphite-composites bipolar plate by compression molding technique to achieve the requisite goal. The composites plates were prepared by using different reinforcing fillers such as natural graphite, synthetic graphite, carbon black, carbon fibers with phenolic resin as polymer matrix precursor in its liquid and powder form. The composition of different filler constituent adjusted in between 5 and 40 vol%. The composite plates prepared with appropriate proportion of filler components were characterized for physical and mechanical properties. It is found that no single reinforcing filler constituent composites plate gives the requisite properties for being used as bipolar plate in the PEM fuel cell. The judicious combination of reinforcing constituents gives the properties which are required for bipolar plate to use in fuel cell. By controlling the ratio of reinforcing constituents, one can able to achieve properties such as bulk density {proportional_to}1.85gcm{sup -3}, electrical conductivity >150Scm{sup -1}, shore hardness >65, bending strength >60MPa, modulus >10GPa and compressive >70MPa by applying the pressure (100kgcm{sup -2}) during compression molding. I-V characteristic of the composite bipolar plate, with optimum combination of reinforcing constituent, is found to be adequate as per the US-DOE target for composite bipolar plate. (author)

  15. Data characterizing compressive properties of Al/Al2O3 syntactic foam core metal matrix sandwich

    Directory of Open Access Journals (Sweden)

    Mohammed Yaseer Omar

    2015-12-01

    Full Text Available Microstructural observations and compressive property datasets of metal matrix syntactic foam core sandwich composite at quasi-static and high strain rate (HSR conditions (525–845 s−1 are provided. The data supplied in this article includes sample preparation procedure prior to scanning electron and optical microscopy as well as the micrographs. The data used to construct the stress–strain curves and the derived compressive properties of all specimens in both quasi-static and HSR regions are included. Videos of quasi-static compressive failure and that obtained by a high speed image acquisition system during deformation and failure of HSR specimen are also included.

  16. A reduced mechanism for biodiesel surrogates with low temperature chemistry for compression ignition engine applications

    Science.gov (United States)

    Luo, Zhaoyu; Plomer, Max; Lu, Tianfeng; Som, Sibendu; Longman, Douglas E.

    2012-04-01

    Biodiesel is a promising alternative fuel for compression ignition (CI) engines. It is a renewable energy source that can be used in these engines without significant alteration in design. The detailed chemical kinetics of biodiesel is however highly complex. In the present study, a skeletal mechanism with 123 species and 394 reactions for a tri-component biodiesel surrogate, which consists of methyl decanoate, methyl 9-decanoate and n-heptane was developed for simulations of 3-D turbulent spray combustion under engine-like conditions. The reduction was based on an improved directed relation graph (DRG) method that is particularly suitable for mechanisms with many isomers, followed by isomer lumping and DRG-aided sensitivity analysis (DRGASA). The reduction was performed for pressures from 1 to 100 atm and equivalence ratios from 0.5 to 2 for both extinction and ignition applications. The initial temperatures for ignition were from 700 to 1800 K. The wide parameter range ensures the applicability of the skeletal mechanism under engine-like conditions. As such the skeletal mechanism is applicable for ignition at both low and high temperatures. Compared with the detailed mechanism that consists of 3299 species and 10806 reactions, the skeletal mechanism features a significant reduction in size while still retaining good accuracy and comprehensiveness. The validations of ignition delay time, flame lift-off length and important species profiles were also performed in 3-D engine simulations and compared with the experimental data from Sandia National Laboratories under CI engine conditions.

  17. Thermodynamic properties of molybdenum borides at temperatures above 300 K

    International Nuclear Information System (INIS)

    Bolgar, A.S.; Blinder, A.V.; Serbova, M.I.

    1990-01-01

    Enthalpy of Mo 2 B, MoB, Mo 2 B 5 borides within the range of temperatures above 300 K has been experimentally studied. Parameters of temperature dependences of enthalpy, heat capacity, entropy and the reduced Gibbs energy of the studied substances are calculated within a wide range. It is stated that high-temperature heat capacity of the studied borides can be presented as a sum of the electron component, a harmonic part of the lattice component and a contribution caused by anharmonic oscillations of lattice atoms. Values of coefficients of isothermal compressibility of Mo 2 , MoB, Mo 2 B 5 within the high temperature range are estimated

  18. Neutron irradiation of sapphire for compressive strengthening. II. Physical properties changes

    Energy Technology Data Exchange (ETDEWEB)

    Regan, Thomas M. E-mail: thomas_regan@uml.edu; Harris, Daniel C. E-mail: harrisdc@navair.navy.mil; Blodgett, David W.; Baldwin, Kevin C.; Miragliotta, Joseph A.; Thomas, Michael E.; Linevsky, Milton J.; Giles, John W.; Kennedy, Thomas A.; Fatemi, Mohammad; Black, David R.; Lagerloef, K. Peter D

    2002-01-01

    Irradiation of sapphire with fast neutrons (0.8-10 MeV) at a fluence of 10{sup 22}/m{sup 2} increased the c-axis compressive strength and the c-plane biaxial flexure strength at 600 deg. C by a factor of {approx}2.5. Both effects are attributed to inhibition of r-plane twin propagation by damage clusters resulting from neutron impact. The a-plane biaxial flexure strength and four-point flexure strength in the c- and m-directions decreased by 10-23% at 600 deg. C after neutron irradiation. Neutron irradiation had little or no effect on thermal conductivity, infrared absorption, elastic constants, hardness, and fracture toughness. A featureless electron paramagnetic resonance signal at g=2.02 was correlated with the strength increase: This signal grew in amplitude with increasing neutron irradiation, which also increased the compressive strength. Annealing conditions that reversed the strengthening also annihilated the g=2.02 signal. A signal associated with a paramagnetic center containing two Al nuclei was not correlated with strength. Ultraviolet and visible color centers also were not correlated with strength in that they could be removed by annealing at temperatures that were too low to reverse the compressive strengthening effect of neutron irradiation.

  19. Neutron irradiation of sapphire for compressive strengthening. II. Physical properties changes

    International Nuclear Information System (INIS)

    Regan, Thomas M.; Harris, Daniel C.; Blodgett, David W.; Baldwin, Kevin C.; Miragliotta, Joseph A.; Thomas, Michael E.; Linevsky, Milton J.; Giles, John W.; Kennedy, Thomas A.; Fatemi, Mohammad; Black, David R.; Lagerloef, K. Peter D.

    2002-01-01

    Irradiation of sapphire with fast neutrons (0.8-10 MeV) at a fluence of 10 22 /m 2 increased the c-axis compressive strength and the c-plane biaxial flexure strength at 600 deg. C by a factor of ∼2.5. Both effects are attributed to inhibition of r-plane twin propagation by damage clusters resulting from neutron impact. The a-plane biaxial flexure strength and four-point flexure strength in the c- and m-directions decreased by 10-23% at 600 deg. C after neutron irradiation. Neutron irradiation had little or no effect on thermal conductivity, infrared absorption, elastic constants, hardness, and fracture toughness. A featureless electron paramagnetic resonance signal at g=2.02 was correlated with the strength increase: This signal grew in amplitude with increasing neutron irradiation, which also increased the compressive strength. Annealing conditions that reversed the strengthening also annihilated the g=2.02 signal. A signal associated with a paramagnetic center containing two Al nuclei was not correlated with strength. Ultraviolet and visible color centers also were not correlated with strength in that they could be removed by annealing at temperatures that were too low to reverse the compressive strengthening effect of neutron irradiation

  20. Prediction of oil expression by uniaxial compression using time-varying oilseed properties

    DEFF Research Database (Denmark)

    Bargale, P. C.; Wulfsohn, Dvoralai; Irudayaraj, J.

    2000-01-01

    A mathematical simulation of uniaxial compression of oilseeds for oil extraction was developed based upon combining Terzaghi's theory of consolidation for saturated soils with Darcy's law for unsaturated flow, while incorporating the time-varying nature of the coefficients of permeability...... and consolidation. The model was validated for extruded soy and for sunflower seeds. Material parameters were determined experimentally and predictions of oil recovery rates made for several levels of temperature, pressure and initial sample depth. Results indicated that while the model predicted the values of oil...... of experimental permeability data in the very early stages of pressing (t time, when compared...

  1. Mechanical properties of the human spinal cord under the compressive loading.

    Science.gov (United States)

    Karimi, Alireza; Shojaei, Ahmad; Tehrani, Pedram

    2017-12-01

    The spinal cord as the most complex and critical part of the human body is responsible for the transmission of both motor and sensory impulses between the body and the brain. Due to its pivotal role any types of physical injury in that disrupts its function following by shortfalls, including the minor motor and sensory malfunctions as well as complicate quadriplegia and lifelong ventilator dependency. In order to shed light on the injuries to the spinal cord, the application of the computational models to simulate the trauma impact loading to that are deemed required. Nonetheless, it has not been fulfilled since there is a paucity of knowledge about the mechanical properties of the spinal cord, especially the cervical one, under the compressive loading on the grounds of the difficulty in obtaining this tissue from the human body. This study was aimed at experimentally measuring the mechanical properties of the human cervical spinal cord of 24 isolated fresh samples under the unconfined compressive loading at a relatively low strain rate. The stress-strain data revealed the elastic modulus and maximum/failure stress of 40.12±6.90 and 62.26±5.02kPa, respectively. Owing to the nonlinear response of the spinal cord, the Yeoh, Ogden, and Mooney-Rivlin hyperelastic material models have also been employed. The results may have implications not only for understanding the linear elastic and nonlinear hyperelastic mechanical properties of the cervical spinal cord under the compressive loading, but also for providing a raw data for investigating the injury as a result of the trauma thru the numerical simulations. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Compressibility and resiliency properties of wilton type woven carpets produced with different fiber blend ratio

    Science.gov (United States)

    Osman, B.; Esin, S.; Sıdıka Ziba, O.

    2017-10-01

    Carpet is a textile structure that composed of three components: warp (stuffer and chain warp), weft and pile yarns. These textile products are used for areas which will stand up to the use of home, hotel, work place etc. Furthermore, the capable of carpets are related to it’s especially pile performance during use in various areas. During usage, carpets made from various type of raw materials of pile yarn also acts differently that these differentiate determines carpet performance, as well.This study was focused on the compression and resilience behaviour of carpet composed of 100% viscose and 100% acrylic pile yarns and blended pile yarns of blend ratios, 80%/20%, 50%/50% and 20%/80% viscose/acrylic. During the yarn production process, all spinning conditions were kept constant in order to eliminate the yarn production parameters. Five different types of wilton face to face carpet samples were produced from these yarns at the same pile height and pile density on Van de Wiele carpet weaving machine at 110 picks/min machine speed and 1/1 V carpet construction. Compressibility properties of carpets were examined whether blend ratio was statistically significant on carpet resilience or not. The behaviour of pile yarns under pressure is important that leads to understand the growth characteristic which is exposed to decrease and increase loadings during usage of carpet made from these yarns. Results indicated that blend ratio of pile yarns have significance effect on compression behaviour of carpet samples.

  3. Compressibility and Optical Properties of Single Crystal Magnesite and Siderite up to 75 GPa

    Science.gov (United States)

    Lavina, B.; Dera, P.; Downs, R. T.; Prakapenka, V.

    2008-12-01

    The stability and properties of carbonates at mantle conditions are of great importance for the carbon cycle, controlling the fate of subducting carbonate rich crust and mantle fertilization processes. Theoretical and experimental observations indicate that magnesite is the product of reaction of carbonates with silicate minerals, and it has been found to be stable within lower mantle conditions. A siderite component is likely to be present at mantle conditions in equilibrium with the surrounding iron bearing phases. We conducted compression experiments on natural single crystals of magnesite and Mg-siderite. By using neon as pressure transmitting medium we collected diffraction data in nearly hydrostatic conditions up to ~ 75GPa. The compression curve of magnesite is in good agreement with literature data. Siderite shows a steep volume decrease between 40 and 50 GPa which is most likely related to the change of ionic size associated with the spin pairing reported in siderite at ~ 50GPa. Siderites single crystals, about 10μ thick, were initially colorless and assumed a green color, progressively deeper, after ~ 40GPa and turned into red at the highest pressure. The color variations were reversible, quantitative absorption data are going to be presented. Siderite is not a major phase of the earth's mantle, therefore its density and optical properties are not likely to significantly affect the earth's density profile or the thermal equilibrium, however it might help to learn in detail the effect of spin transition on mineral physical properties.

  4. Nondestructive Methods to Characterize Rock Mechanical Properties at Low-Temperature: Applications for Asteroid Capture Technologies

    Science.gov (United States)

    Savage, Kara A.

    load, and uniaxial compression. Experimental results show that rock mechanical properties (i.e. uniaxial compressive strength and Young's modulus) and nondestructive test responses (i.e. P-wave velocity and Schmidt rebound) are both influenced by low temperature, and the nature of the response depends on the rock type. Chalk and limestone show increased Young's moduli and decreased Schmidt rebounds and P-wave velocities with decreased temperature, while shale shows decreased Young's modulus and increased P-wave velocity. A significant increase in uniaxial compressive strength is observed for limestone samples with decreased temperature, though the inconsistent strength of chalk and shale samples at room temperature impaired the significance of correlations between decreased temperature and strength change for these samples. Altogether, these results indicate that ultrasonic pulse velocity and impact hammer methods may be suitable for in situ characterization of asteroid material; however, these methods will require temperature correction factors.

  5. Low-Temperature Combustion of High Octane Fuels in a Gasoline Compression Ignition Engine

    Directory of Open Access Journals (Sweden)

    Khanh Duc Cung

    2017-12-01

    Full Text Available Gasoline compression ignition (GCI has been shown as one of the advanced combustion concepts that could potentially provide a pathway to achieve cleaner and more efficient combustion engines. Fuel and air in GCI are not fully premixed compared to homogeneous charge compression ignition (HCCI, which is a completely kinetic-controlled combustion system. Therefore, the combustion phasing can be controlled by the time of injection, usually postinjection in a multiple-injection scheme, to mitigate combustion noise. Gasoline usually has longer ignition delay than diesel. The autoignition quality of gasoline can be indicated by research octane number (RON. Fuels with high octane tend to have more resistance to autoignition, hence more time for fuel-air mixing. In this study, three fuels, namely, aromatic, alkylate, and E30, with similar RON value of 98 but different hydrocarbon compositions were tested in a multicylinder engine under GCI combustion mode. Considerations of exhaust gas recirculating (EGR, start of injection, and boost were investigated to study the sensitivity of dilution, local stratification, and reactivity of the charge, respectively, for each fuel. Combustion phasing (location of 50% of fuel mass burned was kept constant during the experiments. This provides similar thermodynamic conditions to study the effect of fuels on emissions. Emission characteristics at different levels of EGR and lambda were revealed for all fuels with E30 having the lowest filter smoke number and was also most sensitive to the change in dilution. Reasonably low combustion noise (<90 dB and stable combustion (coefficient of variance of indicated mean effective pressure <3% were maintained during the experiments. The second part of this article contains visualization of the combustion process obtained from endoscope imaging for each fuel at selected conditions. Soot radiation signal from GCI combustion were strong during late injection and also more intense

  6. Time-resolved temperature measurements in a rapid compression machine using quantum cascade laser absorption in the intrapulse mode

    KAUST Repository

    Nasir, Ehson Fawad

    2016-07-16

    A temperature sensor based on the intrapulse absorption spectroscopy technique has been developed to measure in situ temperature time-histories in a rapid compression machine (RCM). Two quantum-cascade lasers (QCLs) emitting near 4.55μm and 4.89μm were operated in pulsed mode, causing a frequency "down-chirp" across two ro-vibrational transitions of carbon monoxide. The down-chirp phenomenon resulted in large spectral tuning (δν ∼2.8cm-1) within a single pulse of each laser at a high pulse repetition frequency (100kHz). The wide tuning range allowed the application of the two-line thermometry technique, thus making the sensor quantitative and calibration-free. The sensor was first tested in non-reactive CO-N2 gas mixtures in the RCM and then applied to cases of n-pentane oxidation. Experiments were carried out for end of compression (EOC) pressures and temperatures ranging 9.21-15.32bar and 745-827K, respectively. Measured EOC temperatures agreed with isentropic calculations within 5%. Temperature rise measured during the first-stage ignition of n-pentane is over-predicted by zero-dimensional kinetic simulations. This work presents, for the first time, highly time-resolved temperature measurements in reactive and non-reactive rapid compression machine experiments. © 2016 Elsevier Ltd.

  7. Compressive impact strength of high temperature gas-cooled reactor graphite

    International Nuclear Information System (INIS)

    Ugachi, Hirokazu; Ishiyama, Shintaro; Eto, Motokuni; Ishihara, Masahiro

    1991-01-01

    To investigate the effect of strain rate on fracture behavior for coarse grained nuclear graphite, PGX, a hydraulic servo type impact testing machine has been constructed and compressive impact strength test was performed at various strain up to more than 100(1/s). From the results, the following conclusions were derived. (1) Compressive impact strength of graphite increases with increasing of strain rate in the range of 10 -3 to 100(1/s). (2) Compressive impact strength decreases drastically for strain rates more than 100(1/s). (3) Compressive impact strength dose not depend on specimen volume. (author)

  8. Thermoelastic properties of minerals at high temperature

    Indian Academy of Sciences (India)

    obtained when δT is temperature-dependent are in close agreement with experimental data. ... temperature-independent and then by taking δT as temperature-dependent. 2. Method of analysis. The anharmonicity of the lattice vibration is generally due to thermal ... At high temperature, to understand the elastic behaviour.

  9. A mathematical and numerical framework for the analysis of compressible thermal convection in gases at very high temperatures

    Science.gov (United States)

    Lappa, Marcello

    2016-05-01

    The relevance of non-equilibrium phenomena, nonlinear behavior, gravitational effects and fluid compressibility in a wide range of problems related to high-temperature gas-dynamics, especially in thermal, mechanical and nuclear engineering, calls for a concerted approach using the tools of the kinetic theory of gases, statistical physics, quantum mechanics, thermodynamics and mathematical modeling in synergy with advanced numerical strategies for the solution of the Navier-Stokes equations. The reason behind such a need is that in many instances of relevance in this field one witnesses a departure from canonical models and the resulting inadequacy of standard CFD approaches, especially those traditionally used to deal with thermal (buoyancy) convection problems. Starting from microscopic considerations and typical concepts of molecular dynamics, passing through the Boltzmann equation and its known solutions, we show how it is possible to remove past assumptions and elaborate an algorithm capable of targeting the broadest range of applications. Moving beyond the Boussinesq approximation, the Sutherland law and the principle of energy equipartition, the resulting method allows most of the fluid properties (density, viscosity, thermal conductivity, heat capacity and diffusivity, etc.) to be derived in a rational and natural way while keeping empirical contamination to the minimum. Special attention is deserved as well to the well-known pressure issue. With the application of the socalled multiple pressure variables concept and a projection-like numerical approach, difficulties with such a term in the momentum equation are circumvented by allowing the hydrodynamic pressure to decouple from its thermodynamic counterpart. The final result is a flexible and modular framework that on the one hand is able to account for all the molecule (translational, rotational and vibrational) degrees of freedom and their effective excitation, and on the other hand can guarantee adequate

  10. Assessment of the compressive and tensile mechanical properties of materials used in the Jaipur Foot prosthesis.

    Science.gov (United States)

    Teater, Rachel H; Fischenich, Kristine M; Wheatley, Benjamin B; Abrams, Lisa; Sorby, Sheryl A; Mali, Harlal Singh; Jain, Anil; Donahue, Tammy L Haut

    2018-04-01

    Designed by Dr. Sethi, the Jaipur Foot prosthesis is ideally suited for amputees in developing countries as it utilizes locally sourced, biodegradable, inexpensive materials and is focused on affordability and functionality. To date, however, no data have been reported on the material properties of the foot components. The goal of this work was to evaluate mechanical properties of the Jaipur Foot components to guide foot design and manufacturing and reduce weight. Experimental. Mechanical testing was conducted on two types of woods (ardu and cheed), microcellular rubber, tire cord, cushion compound, tread compound, and skin-colored rubber. Each material was subjected to testing in either tension or compression based on its location and function in the foot. Samples were tested before and after vulcanization. Two-sample t-tests were used to assess statistical differences. Cheed compressed perpendicular to the grain had a significantly higher modulus of elasticity than ardu ( p < 0.05); however, cheed had a higher density. Vulcanization significantly increased the modulus of skin-colored rubber, cushion compound, and tread compound ( p < 0.05) and decreased the moduli of both microcellular rubber and tire cord ( p < 0.05). The material property results from this study provide information for computer modeling to assess material construction on overall foot mechanics for design optimization. Ardu wood was ideal based on the desire to reduce weight, and the tire cord properties serve well to hold the foot together. Clinical relevance With new knowledge on the material properties of the components of the Jaipur Foot, future design modifications and standardized fabrication can be realized, making the Jaipur Foot more available on a global scale.

  11. Diaspore crystal structure and compressibility at high pressures and high temperature

    Science.gov (United States)

    Li, Ming; Snoussi, Karim; Li, Lixin; Wang, Huixin; Yang, Wuming; Gao, Chunxiao

    2010-06-01

    We have determined the unit-cell parameters of diaspore α-AlO(OH) at high pressures (13.5-27.8 GPa) and at high temperature (1900 K). Experimental data are compared with the theoretically predicted crystal structure variations derived from density functional theory (DFT) calculations. The experimental analysis establishes that the a axial direction is more compressible than the b and c axial directions in the low-pressure range (13.5-18 GPa) and at 1900 K, whereas all three directions show similar behaviors in the high-pressure range (18-27.8 GPa). The diaspore isothermal bulk modulus KT values are 137.6 GPa, 124.8 GPa, and 141.3 GPa, respectively, at 300 K, at 1900 K, and again at 300 K after quenching. By comparison, the diaspore isothermal bulk modulus KT computed at 300 K and at ambient pressure in the framework of the plane-wave pseudopotential approach is equal to 129.3 GPa.

  12. Pressure and temperature induced elastic properties of Am and Cf monobismuthides

    Energy Technology Data Exchange (ETDEWEB)

    Jain, S., E-mail: sanjay-rjain@rediffmail.com [School of Physics, Vigyan Bhavan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India); Sushila Devi Bansal College of Engineering, Rau, Indore 452001 (India); Shriya, S.; Varshney, Dinesh, E-mail: vdinesh33@rediffmail.com [School of Physics, Vigyan Bhavan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India); Khenata, R. [Département de Technologie, Université de Mascara, 29000-Algeria (Algeria); Varshney, M. [Department of Physics, M. B. Khalsa College, Raj Mohallah, Indore 452002 (India)

    2016-05-23

    The pressure and temperature dependent mechanical properties as melting temperature, hardness and brittle nature of XBi (X = Am and Cf) are studied. The rare earth actinides pnictides showed a structural phase transition (B1–B2) at a transition pressure (P{sub T}) of 14.3 GPa (AmBi) and 10.8 GPa (CfBi). Pressure dependence of melting temperature (T{sub m}) discerns an increase inferring the hardening or stiffening of the lattice as a consequence of bond compression and bond strengthening. Suppressed T{sub M} as functions of temperature infers the weakening of the lattice results in bond weakening in XBi (X = Am, Cf). Vickers Hardness (H{sub V}), Poisson’s and Pugh ratio of XBi (X = Am and Cf) demonstrates that XBi (X = Am and Cf) is mechanically stiffened, thermally softened and brittle on applied pressure and temperature.

  13. On the effects of fuel properties and injection timing in partially premixed compression ignition of low octane fuels

    KAUST Repository

    Naser, Nimal

    2017-06-29

    A better understanding on the effects of fuel properties and injection timing is required to improve the performance of advanced engines based on low temperature combustion concepts. In this work, an experimental and computational study was conducted to investigate the effects of physical and chemical kinetic properties of low octane fuels and their surrogates in partially premixed compression ignition (PPCI) engines. The main objective was to identify the relative importance of physical versus chemical kinetic properties in predicting practical fuel combustion behavior across a range of injection timings. Two fuel/surrogate pairs were chosen for comparison: light naphtha (LN) versus the primary reference fuel (PRF) with research octane number of 65 (PRF 65), and FACE (fuels for advanced combustion engines) I gasoline versus PRF 70. Two sets of parametric studies were conducted: the first varied the amount of injected fuel mass at different injection timings to match a fixed combustion phasing, and the second maintained the same injected fuel mass at each injection timing to assess resulting combustion phasing changes. Full-cycle computational fluid dynamic engine simulations were conducted by accounting for differences in the physical properties of the original and surrogate fuels, while employing identical chemical kinetics. The simulations were found to capture trends observed in the experiments, while providing details on spatial mixing and chemical reactivity for different fuels and injection timings. It was found that differences in physical properties become increasingly important as injection timing was progressively delayed from premixed conditions, and this was rationalized by analysis of mixture stratification patterns resulting from injection of fuels with different physical properties. The results suggest that accurate descriptions of both physical and chemical behavior of fuels are critical in predictive simulations of PPCI engines for a wide range of

  14. Effect of sintering temperature on microstructure and compressive strength of B4C-AlSi eutectic alloy

    International Nuclear Information System (INIS)

    Liu Jinyun; Zha Wusheng; Liu Gaihua; Lan Jun; Feng Quanhe; Zou Congpei

    2008-01-01

    The block neutron absorber of B 4 C based on Al-Si eutectic alloy has been prepared by powder-metallurgy method. The effects of sinter temperature on microstructure, compressive strength, and ductility of sintered billets have been investigated. It has been shown that the sintering temperature decides sensitively the compressive strength and ductility of sintered billets. Sintered under 550, 555, 560, and 565 degree C, the billet shows different states, such as sub-sintered, best-sintered, over-sintered, and molten. Sintered under 550 degree C, the powder have not been metallurgically combined with each other. Beyond 560 degree C, the billets are molten. The 555 degree C is the best sintering temperature, under which the powder have been partly melted and the metallurgical combination has been occurred, then the billets have a better ductility. (authors)

  15. Modelling property changes in graphite irradiated at changing irradiation temperature

    CSIR Research Space (South Africa)

    Kok, S

    2011-01-01

    Full Text Available A new method is proposed to predict the irradiation induced property changes in nuclear; graphite, including the effect of a change in irradiation temperature. The currently used method; to account for changes in irradiation temperature, the scaled...

  16. Mechanical properties of alumina-PEEK unidirectional composite - Compression, shear, and tension

    Science.gov (United States)

    Kriz, R. D.; Mccolskey, J. D.

    1990-01-01

    An Al2O3 (alumina)-fiber composite with high strain to failure was fabricated with a thermal plastic PEEK (poly-ether-ether-ketone). The Al2O3-PEEK composite shows a marked improvement over thermally setting composite in that it absorbs 150 percent more elastic-strain energy at 76 K than at room temperature. This increase in fracture toughness at low temperatures can provide improved fatigue performance for thermal isolation straps at low temperature. Other mechanical property results suggest improvements for applications where graphite-epoxy materials are presently being used at low temperatures and where light weight is not a critical issue.

  17. Elevated Temperature, Notched Compression Performance of Out of Autoclave Processed Composites

    Science.gov (United States)

    Grimsley, Brian W.; Sutter, James K.; Dixon, Genevieve D.; Smeltzer, Satn S.

    2013-01-01

    Curved honeycomb sandwich panels composed of carbon fiber reinforced toughened-epoxy polymer facesheets are being evaluated for potential use as payload fairing components on the NASA heavy-lift space launch system (HL-SLS). These proposed composite sandwich panels provide the most efficient aerospace launch structures, and offer mass and thermal advantages when compared with existing metallic payload fairing structures. NASA and industry are investigating recently developed carbon fiber epoxy prepreg systems which can be fabricated using out-of autoclave (OOA) processes. Specifically, OOA processes using vacuum pressure in an oven and thereby significantly reducing the cost associated with manufacturing large (up to 10 m diameter) composite structures when compared with autoclave. One of these OOA composite material systems, CYCOM(R) 5320-1, was selected for manufacture of a 1/16th scale barrel portion of the payload fairing; such that, the system could be compared with the well-characterized prepreg system, CYCOM(R) 977-3, typically processed in an autoclave. Notched compression coupons for each material were obtained from the minimum-gauge flat laminate [60/-60/0]S witness panels produced in this manufacturing study. The coupons were also conditioned to an effective moisture equilibrium point and tested according to ASTM D6484M-09 at temperatures ranging from 25 C up to 177 C. The results of this elevated temperature mechanical characterization study demonstrate that, for thin coupons, the OHC strength of the OOA laminate was equivalent to the flight certified autoclave processed composite laminates; the limitations on the elevated temperature range are hot-wet conditions up to 163 C and are only within the margins of testing error. At 25 C, both the wet and dry OOA material coupons demonstrated greater OHC failure strengths than the autoclave processed material laminates. These results indicate a substantial improvement in OOA material development and

  18. Evolution of Skin Temperature after the Application of Compressive Forces on Tendon, Muscle and Myofascial Trigger Point.

    Science.gov (United States)

    Magalhães, Marina Figueiredo; Dibai-Filho, Almir Vieira; de Oliveira Guirro, Elaine Caldeira; Girasol, Carlos Eduardo; de Oliveira, Alessandra Kelly; Dias, Fabiana Rodrigues Cancio; Guirro, Rinaldo Roberto de Jesus

    2015-01-01

    Some assessment and diagnosis methods require palpation or the application of certain forces on the skin, which affects the structures beneath, we highlight the importance of defining possible influences on skin temperature as a result of this physical contact. Thus, the aim of the present study is to determine the ideal time for performing thermographic examination after palpation based on the assessment of skin temperature evolution. Randomized and crossover study carried out with 15 computer-user volunteers of both genders, between 18 and 45 years of age, who were submitted to compressive forces of 0, 1, 2 and 3 kg/cm2 for 30 seconds with a washout period of 48 hours using a portable digital dynamometer. Compressive forces were applied on the following spots on the dominant upper limb: myofascial trigger point in the levator scapulae, biceps brachii muscle and palmaris longus tendon. Volunteers were examined by means of infrared thermography before and after the application of compressive forces (15, 30, 45 and 60 minutes). In most comparisons made over time, a significant decrease was observed 30, 45 and 60 minutes after the application of compressive forces (p 0.05). In conclusion, infrared thermography can be used after assessment or diagnosis methods focused on the application of forces on tendons and muscles, provided the procedure is performed 15 minutes after contact with the skin. Regarding to the myofascial trigger point, the thermographic examination can be performed within 60 minutes after the contact with the skin.

  19. Preparation and properties of low cement castable sintered at different temperatures

    Directory of Open Access Journals (Sweden)

    Sanja Martinović

    2009-12-01

    Full Text Available The low cement high alumina castable (LCC studied in this paper was synthesised, cured and then treated at different sintering temperatures. Since any inhomogeneity introduced during the castable preparation can remain inside the material degrading its properties and therefore the quality during service life, particular attention was given to the processing procedure in order to produce the material with the optimum characteristics. Composition of the castable regarding particle size distribution was adjusted according to the Andreassen’s packing model. The samples were sintered at 1100, 1300 and 1600°C for three hours. Influence of the different sintering temperatures on the castable properties is discussed. Compressive and flexural strengths were determined by destructive testing method, while the water immersion method was used for determination of the bulk density and the water absorption. Changes of elastic properties and microstructure (porosity were observed by the non-destructive testing methods, ultrasonic measurements and image analysis. Based on the results, it can be concluded that sintering temperature has strong influence on the properties of the LCC. Exceptionally good properties were obtained for the sample sintered at 1600°C, but it should be highlighted that the samples treated at 1100 and 1300°C were provided with good properties, too. This should not be neglected because of the energy saving importance, in cases where the material sintered at lower temperature satisfies the application requirements.

  20. Contribution of proteoglycan osmotic swelling pressure to the compressive properties of articular cartilage.

    Science.gov (United States)

    Han, EunHee; Chen, Silvia S; Klisch, Stephen M; Sah, Robert L

    2011-08-17

    The negatively charged proteoglycans (PG) provide compressive resistance to articular cartilage by means of their fixed charge density (FCD) and high osmotic pressure (π(PG)), and the collagen network (CN) provides the restraining forces to counterbalance π(PG). Our objectives in this work were to: 1), account for collagen intrafibrillar water when transforming biochemical measurements into a FCD-π(PG) relationship; 2), compute π(PG) and CN contributions to the compressive behavior of full-thickness cartilage during bovine growth (fetal, calf, and adult) and human adult aging (young and old); and 3), predict the effect of depth from the articular surface on π(PG) in human aging. Extrafibrillar FCD (FCD(EF)) and π(PG) increased with bovine growth due to an increase in CN concentration, whereas PG concentration was steady. This maturation-related increase was amplified by compression. With normal human aging, FCD(EF) and π(PG) decreased. The π(PG)-values were close to equilibrium stress (σ(EQ)) in all bovine and young human cartilage, but were only approximately half of σ(EQ) in old human cartilage. Depth-related variations in the strain, FCD(EF), π(PG), and CN stress profiles in human cartilage suggested a functional deterioration of the superficial layer with aging. These results suggest the utility of the FCD-π(PG) relationship for elucidating the contribution of matrix macromolecules to the biomechanical properties of cartilage. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  1. Powder compression properties of paracetamol, paracetamol hydrochloride, paracetamol cocrystals and coformers.

    Science.gov (United States)

    Persson, Ann-Sofie; Ahmed, Hamzah; Velaga, Sitaram; Alderborn, Göran

    2018-03-31

    The objective was to study the relationship between crystal structure, particle deformation properties and tablet-forming ability for the monoclinic form of paracetamol (PRA), two cocrystals and a salt crystal of PRA in addition to two coformers (oxalic acid and 4,4'-bipyridine). Thus, the structure - property - performance relationship was investigated. Analytical powder compression was used for determination of effective plasticity, as inferred from the Heckel yield pressure and the Frenning parameter, and the elastic deformation was determined from in-die tablet elastic recovery. plasticity could not be linked to the crystal lattice structure as crystals containing zig-zag layers displayed similar plasticity as cThe rystals containing slip planes. In addition, crystals containing slip-planes displayed both high and low plasticity. The mechanical properties could neither be linked to the tablet-forming ability as the tablet tensile strength, unexpectedly, displayed a tendency to reduce with increased plasticity stiffness. Furthermore, the elastic deformation could not explain the tablet forming ability. It was concluded that no relationship between structure - property - performance for paracetamol and its cocrystals and salt could be established. Thus, it was indicated that to establish such a relationship an improved knowledge of crystallographic structure and inter-particle bonding during compaction is needed. Copyright © 2018. Published by Elsevier Inc.

  2. Biocompatibility and compressive properties of Ti-6Al-4V scaffolds having Mg element.

    Science.gov (United States)

    Kalantari, Seyed Mohammad; Arabi, Hossein; Mirdamadi, Shamsodin; Mirsalehi, Seyed Ali

    2015-08-01

    Porous scaffolds of Ti-6Al-4V were produced by mixing of this alloy with different amount of magnesium (Mg) powders. The mixtures were compacted in steel die by applying uniaxial pressure of 500 MPa before sintering the compacts in sealed quartz tubes at 900 °C for 2 h. Employing Archimedes׳ principle and Image Tool software, the total and open volume percentages of porosities within the scaffolds were found to be in the range of 47-64% and 41-47%, respectively. XRD results of titanium before and after sintering showed that no contamination, neither oxides nor nitrides formed during processes. Compressive properties of the scaffolds were studied using an Instron machine. The observed compressive strength and Young׳s module of the scaffolds were in the range of 72-132 MPa, and 37-47 GPa, respectively. Cell attachment and proliferation rate of MG-63 on porous samples were investigated. The results showed that proliferation rate increased with increasing Mg content. However no clear differences were observed between samples regarding cell attachment, so that bridges were observed in all cell gaps within the scaffolds. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Microstructure and compressive properties of AlCrFeCoNi high entropy alloy

    International Nuclear Information System (INIS)

    Wang, Y.P.; Li, B.S.; Ren, M.X.; Yang, C.; Fu, H.Z.

    2008-01-01

    An AlCrFeCoNi high entropy alloy was prepared by vacuum arc melting. Only diffraction peak corresponding to a BCC crystal structure is observed for this AlCrFeCoNi high entropy alloy. The microstructure of this AlCrFeCoNi alloy is polygonal grains with intragranular dendritic segregation. Dendritic segregation area is found to be Al, Ni rich and Cr, Fe deplete, while interdendritic segregation area is Cr, Fe rich and Al, Ni deplete. The distribution of Co is essentially identical. The fine microstructure of dendritic segregation area and of interdendritic segregation area is found to be nanoscale spherical precipitates morphology and basket-weave morphology, respectively. Results of EDS attached on high resolution scanning electron microscope (SEM) revealed that these morphological characteristics are also resulted from elements segregation. This AlCrFeCoNi high entropy alloy exhibits excellent compressive properties. The yield stress, compressive strength and plastic strain of the alloy reaches 1250.96, 2004.23 MPa, and 32.7%, respectively. The fracture mechanism of this AlCrFeCoNi high entropy alloy is observed as cleavage fracture and slip separation

  4. Effect of aggregates on the magnetization property of ferrofluids: A model of gaslike compression

    Directory of Open Access Journals (Sweden)

    Jian Li, Yan Huang, Xiaodong Liu, Yueqing Lin, Lang Bai and Qiang Li

    2007-01-01

    Full Text Available The effect of field-induced aggregation of particles on the magnetization property of ferrofluids is investigated. From the viewpoint of energy, magnetizability of ferrofluids is more complicated than predicted by Langevin theory because the aggregation, i.e., the transition of ferrofluid microstructure, would consume the energy of the applied magnetic field. For calculating the effect of aggregates on the magnetization of ferrofluids, a model of gaslike compression (MGC is proposed to simulate the evolution of the aggregate structure. In this model, the field-induced colloidal particles aggregating in ferrofluids is equivalent to the "gas of the particles" being compressed by the applied magnetic field. The entropy change of the ferrofluid microstructure is proportional to the particle volume fraction in field-induced aggregates phivH. On the basis of the known behavior of ferrofluid magnetization and the aggregate structure determined from the present experiments, phivH is obtained and found to depend on the aggregating characteristic parameter of ferrofluid particles γ in addition to the particle volume fraction in ferrofluids phiv and the strength of applied magnetic field H. The effect of the nonmagnetic surface layer of ferrofluid particles is also studied. The theory of MGC conforms to our experimental results better than Langevin theory.

  5. A nonlinear structural subgrid-scale closure for compressible MHD. I. Derivation and energy dissipation properties

    Energy Technology Data Exchange (ETDEWEB)

    Vlaykov, Dimitar G., E-mail: Dimitar.Vlaykov@ds.mpg.de [Institut für Astrophysik, Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Max-Planck-Institut für Dynamik und Selbstorganisation, Am Faßberg 17, D-37077 Göttingen (Germany); Grete, Philipp [Institut für Astrophysik, Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany); Schmidt, Wolfram [Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg (Germany); Schleicher, Dominik R. G. [Departamento de Astronomía, Facultad Ciencias Físicas y Matemáticas, Universidad de Concepción, Av. Esteban Iturra s/n Barrio Universitario, Casilla 160-C (Chile)

    2016-06-15

    Compressible magnetohydrodynamic (MHD) turbulence is ubiquitous in astrophysical phenomena ranging from the intergalactic to the stellar scales. In studying them, numerical simulations are nearly inescapable, due to the large degree of nonlinearity involved. However, the dynamical ranges of these phenomena are much larger than what is computationally accessible. In large eddy simulations (LESs), the resulting limited resolution effects are addressed explicitly by introducing to the equations of motion additional terms associated with the unresolved, subgrid-scale dynamics. This renders the system unclosed. We derive a set of nonlinear structural closures for the ideal MHD LES equations with particular emphasis on the effects of compressibility. The closures are based on a gradient expansion of the finite-resolution operator [W. K. Yeo (CUP, 1993)] and require no assumptions about the nature of the flow or magnetic field. Thus, the scope of their applicability ranges from the sub- to the hyper-sonic and -Alfvénic regimes. The closures support spectral energy cascades both up and down-scale, as well as direct transfer between kinetic and magnetic resolved and unresolved energy budgets. They implicitly take into account the local geometry, and in particular, the anisotropy of the flow. Their properties are a priori validated in Paper II [P. Grete et al., Phys. Plasmas 23, 062317 (2016)] against alternative closures available in the literature with respect to a wide range of simulation data of homogeneous and isotropic turbulence.

  6. Tensile, Compressive and Thermal Properties of Epoxy / Hollow Glass Beads/ Graphene Ternary Foamed Composites

    International Nuclear Information System (INIS)

    Wu, X. F.; Zhao, Y. K.; Zhao, Z. H.; Sun, Y.; Zhang, Y.; Zheng, S. S.; Xiao, F. J.

    2016-01-01

    Hollow glass beads and graphene were used to improve the performances of the epoxy resin. The density, tensile, compressive properties and thermal behaviors of the as-prepared samples were discussed. Experiment results showed that hollow glass beads could effectively reduce the density of the epoxy resin matrix. When the hollow glass beads loading was 30 wt percent, the density of the composites was 0.81 gcm-3. Moreover, graphene could enhance the mechanical performances of the foamed composites. When the graphene loading was 0.75 wt percent, the tensile strength, Young modulus and strain break of the epoxy/hollow glass beads/graphene ternary samples were 85.2 percent, 53.4 percent and 11.0 percent more than the control binary sample, respectively. Moreover, the compressive strength and modulus were 10.8 percent and 68.6 percent more than the control binary sample, respectively. In addition, DSC and TG results showed that graphene could accelerate the curing and improve the thermal stability of the foamed composites. (author)

  7. Mechanical properties of Concrete with SAP. Part I: Development of compressive strength

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange; Jespersen, Morten H. Seneka; Jensen, Ole Mejlhede

    2010-01-01

    compressive strength. It shows that results agree well with a model based on the following: 1. Concrete compressive strength is proportional to compressive strength of the paste phase 2. Paste strength depends on gel space ratio, as suggested by Powers 3. The influence of air voids created by SAP...... on compressive strength can be accounted for in the same way as when taking the air content into account in Bolomeys formula. The implication of the model is that at low w/c ratios (w/c compressive strength at later ages (from 3 days after casting and onwards...... the compressive strength....

  8. Influence of substrate temperature on certain physical properties ...

    Indian Academy of Sciences (India)

    Influence of substrate temperature on certain physical properties and antibacterial activity of nanocrystalline Ag-doped In 2 O 3 thin films ... films were subjected to various characterization studies, to explore certain features like the influence of various deposition temperatures on physical and antibacterial properties.

  9. Effects of Decortication Temperature on the Functional Properties of ...

    African Journals Online (AJOL)

    The effects of decortication temperature on the functional and sensory properties of the cowpea flour (Vigna unguiculata) and steam flour paste were studied. Cowpea seeds were soaked at different temperatures (20oC, 40oC, 60oC, 80oC and 100oC) prior to decortication. The functional properties of the cowpea flour, ...

  10. Pressure–temperature dependence of thermodynamic properties of ...

    Indian Academy of Sciences (India)

    Haleh Kangarlou and Arash Abdollahi properties of materials under high pressures and temperatures for microscopic under- standing as well as technological applications. In this paper, we report our theoretical study of both pressure and temperature dependences of the thermal properties of rutile within the Debye and ...

  11. Music preferences with hearing aids: effects of signal properties, compression settings, and listener characteristics.

    Science.gov (United States)

    Croghan, Naomi B H; Arehart, Kathryn H; Kates, James M

    2014-01-01

    Current knowledge of how to design and fit hearing aids to optimize music listening is limited. Many hearing-aid users listen to recorded music, which often undergoes compression limiting (CL) in the music industry. Therefore, hearing-aid users may experience twofold effects of compression when listening to recorded music: music-industry CL and hearing-aid wide dynamic-range compression (WDRC). The goal of this study was to examine the roles of input-signal properties, hearing-aid processing, and individual variability in the perception of recorded music, with a focus on the effects of dynamic-range compression. A group of 18 experienced hearing-aid users made paired-comparison preference judgments for classical and rock music samples using simulated hearing aids. Music samples were either unprocessed before hearing-aid input or had different levels of music-industry CL. Hearing-aid conditions included linear gain and individually fitted WDRC. Combinations of four WDRC parameters were included: fast release time (50 msec), slow release time (1,000 msec), three channels, and 18 channels. Listeners also completed several psychophysical tasks. Acoustic analyses showed that CL and WDRC reduced temporal envelope contrasts, changed amplitude distributions across the acoustic spectrum, and smoothed the peaks of the modulation spectrum. Listener judgments revealed that fast WDRC was least preferred for both genres of music. For classical music, linear processing and slow WDRC were equally preferred, and the main effect of number of channels was not significant. For rock music, linear processing was preferred over slow WDRC, and three channels were preferred to 18 channels. Heavy CL was least preferred for classical music, but the amount of CL did not change the patterns of WDRC preferences for either genre. Auditory filter bandwidth as estimated from psychophysical tuning curves was associated with variability in listeners' preferences for classical music. Fast

  12. Numerical solution of shock and ramp compression for general material properties

    Energy Technology Data Exchange (ETDEWEB)

    Swift, D C

    2009-01-28

    A general formulation was developed to represent material models for applications in dynamic loading. Numerical methods were devised to calculate response to shock and ramp compression, and ramp decompression, generalizing previous solutions for scalar equations of state. The numerical methods were found to be flexible and robust, and matched analytic results to a high accuracy. The basic ramp and shock solution methods were coupled to solve for composite deformation paths, such as shock-induced impacts, and shock interactions with a planar interface between different materials. These calculations capture much of the physics of typical material dynamics experiments, without requiring spatially-resolving simulations. Example calculations were made of loading histories in metals, illustrating the effects of plastic work on the temperatures induced in quasi-isentropic and shock-release experiments, and the effect of a phase transition.

  13. Prediction of oil expression by uniaxial compression using time-varying oilseed properties

    DEFF Research Database (Denmark)

    Bargale, P. C.; Wulfsohn, Dvoralai; Irudayaraj, J.

    2000-01-01

    recovery for extruded soybean very well, the predictions were not satisfactory for sunflower seed samples. The higher error was attributed to material non-homogeneity and the presence of hulls in the sunflower seeds, which increased errors in measurement of the medium permeability function. The lack......A mathematical simulation of uniaxial compression of oilseeds for oil extraction was developed based upon combining Terzaghi's theory of consolidation for saturated soils with Darcy's law for unsaturated flow, while incorporating the time-varying nature of the coefficients of permeability...... and consolidation. The model was validated for extruded soy and for sunflower seeds. Material parameters were determined experimentally and predictions of oil recovery rates made for several levels of temperature, pressure and initial sample depth. Results indicated that while the model predicted the values of oil...

  14. Thermodynamic properties of binary liquid mixtures of diethylenetriamine with alcohols at different temperatures

    International Nuclear Information System (INIS)

    Dubey, Gyan Prakash; Kumar, Krishan

    2011-01-01

    Highlights: → Thermodynamic study of diethylenetriamine + 2-methyl-1-propanol, +2-propanol or +1-butanol have been made. → Excess molar volumes and isentropic compressibility were determined. → Types of interactions were discussed based on derived properties. - Abstract: Densities, ρ, viscosities, η, and speeds of sound, u, were measured for the binary liquid mixtures containing diethylenetriamine with 2-methyl-1-propanol, 2-propanol and 1-butanol at 293.15, 298.15, 303.15, 308.15 and 313.15 K. From density and speed of sound data, excess molar volumes, V m E and deviations in isentropic compressibility, Δκ s , and speed of sound, Δu have been evaluated. Viscosity data were used to compute deviations in viscosity and excess Gibbs energy of activation of viscous flow ΔG* E at 298.15, 303.15 and 308.15 K. A Redlich-Kister type equation was applied to fit the excess molar volumes and deviations in isentropic compressibility, speed of sound and viscosity data. The viscosity data have been correlated with the equations of Grunberg-Nissan, Tamura-Kurata, Heric-Brewer and of Hind et al. All the binary systems of the present study have negative values of excess molar volumes and deviations in isentropic compressibility over whole composition range and at all temperatures which indicates strong interactions between the components of binary mixtures.

  15. Temperature-dependent thermal properties of spark plasma sintered alumina

    Directory of Open Access Journals (Sweden)

    Saheb Nouari

    2017-01-01

    Full Text Available In this work, we report temperature-dependent thermal properties of alumina powder and bulk alumina consolidated by spark plasma sintering method. The properties were measured between room temperature and 250ºC using a thermal constants analyzer. Alumina powder had very low thermal properties due to the presence of large pores and absence of bonding between its particles. Fully dense alumina with a relative density of 99.6 % was obtained at a sintering temperature of 1400°C and a holding time of 10 min. Thermal properties were found to mainly dependent on density. Thermal conductivity, thermal diffusivity, and specific heat of the fully dense alumina were 34.44 W/mK, 7.62 mm2s-1, and 1.22 J/gK, respectively, at room temperature. Thermal conductivity and thermal diffusivity decreased while specific heat increased with the increase in temperature from room temperature to 250ºC.

  16. Effects of material properties and speed of compression on microbial survival and tensile strength in diclofenac tablet formulations.

    Science.gov (United States)

    Ayorinde, J O; Itiola, O A; Odeniyi, M A

    2013-03-01

    A work has been done to study the effects of material properties and compression speed on microbial survival and tensile strength in diclofenac tablet formulations. Tablets were produced from three formulations containing diclofenac and different excipients (DC, DL and DDCP). Two types of machines (Hydraulic hand press and single punch press), which compress the tablets at different speeds, were used. The compression properties of the tablets were analyzed using Heckel and Kawakita equations. A 3-dimensional plot was produced to determine the relationship between the tensile strength, compression speed and percentage survival of Bacillus subtilis in the diclofenac tablets. The mode of consolidation of diclofenac was found to depends on the excipient used in the formulation. DC deformed mainly by plastic flow with the lowest Py and Pk values. DL deformed plastically at the initial stage, followed by fragmentation at the later stage of compression, whereas DDCP deformed mainly by fragmentation with the highest Py and Pk values. The ranking of the percentage survival of B. subtilis in the formulations was DDCP > DL > DC, whereas the ranking of the tensile strength of the tablets was DDCP > DL > DC. Tablets produced on a hydraulic hand press with a lower compression speed had a lower percentage survival of microbial contaminants than those produced on a single punch press, which compressed the tablets at a much higher speed. The mode of consolidation of the materials and the speed at which tablet compression is carried out have effects on both the tensile strength of the tablets and the extent of destruction of microbial contaminants in diclofenac tablet formulations.

  17. Tensile properties of compressed moulded Napier/glass fibre reinforced epoxy composites

    Science.gov (United States)

    Fatinah, T. S.; Majid, M. S. Abdul; Ridzuan, M. J. M.; Hong, T. W.; Amin, N. A. M.; Afendi, M.

    2017-10-01

    This paper describes the experimental investigation of the tensile properties of compressed moulded Napier grass fibres reinforced epoxy composites. The effect of treatment 5% sodium hydroxide (NaOH) concentrated solution and hybridization of Napier with CSM E-glass fibres on tensile properties was also studied. The untreated and treated Napier fibres with 25% fibre loading were fabricated with epoxy resin by a cold press process. 7% fibre loading of CSM glass fibre was hybrid as the skin layer for 18% fibre loading of untreated Napier grass fibre. The tensile tests were conducted using Universal Testing Machine in accordance with ASTM D638. The tensile properties of the untreated Napier/epoxy composites were compared with treated Napier/epoxy and untreated Napier/CSM/epoxy composites. The results demonstrated that the tensile performance of untreated Napier fibre composites was significantly improved by both of the modification; alkali treatment and glass fibre hybridization. Napier grass fibres showed promising potentials to be used as reinforcement in the polymer based composites.

  18. Mechanical and thermal postbuckling of shear-deformable FGM plates with temperature-dependent properties

    Science.gov (United States)

    Duc, N. D.; Tung, H. V.

    2010-12-01

    An analytical approach to investigating the stability of simply supported rectangular functionally graded plates under in-plane compressive, thermal, and combined loads is presented. The material properties are assumed to be temperature-dependent and graded in the thickness direction according to a simple power-law distribution in terms of volume fractions of constituents. The equilibrium and compatibility equations for the plates are derived by using the first-order shear deformation theory of plates, taking into account both the geometrical nonlinearity in the von Karman sense and initial geometrical imperfections. The resulting equations are solved by employing the Galerkin procedure to obtain expressions from which the postbuckling load-deflection curves can be traced by an iterative procedure. A stability analysis performed for geometrically midplane-symmetric FGM plates shows the effects of material and geometric parameters, in-plane boundary conditions, temperature-dependent material properties, and imperfections on the postbuckling behavior of the plates.

  19. Evaluation of Aluminum Alloy 2050-T84 Microstructure and Mechanical Properties at Ambient and Cryogenic Temperatures

    Science.gov (United States)

    Hafley, Robert A.; Domack, Marcia S.; Hales, Stephen J.; Shenoy, Ravi N.

    2011-01-01

    Aluminum alloy 2050 is being considered for the fabrication of cryogenic propellant tanks to reduce the mass of future heavy-lift launch vehicles. The alloy is available in section thicknesses greater than that of the incumbent aluminum alloy, 2195, which will enable designs with greater structural efficiency. While ambient temperature design allowable properties are available for alloy 2050, cryogenic properties are not available. To determine its suitability for use in cryogenic propellant tanks, tensile, compression and fracture tests were conducted on 4 inch thick 2050-T84 plate at ambient temperature and at -320degF. Various metallurgical analyses were also performed in order to provide an understanding of the compositional homogeneity and microstructure of 2050.

  20. Effects of Temperature on Dynamic Properties of a Biodegradable Polymer Made from Corn Starch

    Science.gov (United States)

    Nishida, Masahiro; Ito, Noriomi; Kawase, Hiroyuki; Tanaka, Koichi

    The effect of strain rate on compressive properties of starch-based biodegradable plastics (Nihon Cornstarch Co., CPR-M2) was examined. Dynamic stress-strain curves of starch-based biodegradable plastics were measured over a wide range of strain rates from 10-5 s-1 to 104 s-1, using a quasi-static compression testing machine and a split Hopkinson pressure bar (SHPB) system. The strain rate slightly affected Young's modulus and considerably increased 7% flow stress. Empirical equation for 7% flow stress was derived for the strain rates from 10-5 s-1 to 104 s-1. In addition, the effect of temperature on Young's modulus and flow stress was also examined in a range from 4°C to 63°C. A master curve of 7% flow stress, reduced to 24°C, was made. The values of activation energies related to the α and β relaxation processes were respectively estimated from the master curve of 7% flow stress and from the best fit of equations based on Ree-Eyring theory and Bauwens' treatment. Temperature measurement of specimens was also made using thermocouples during dynamic compression.

  1. Characterization of High Temperature Modulus of Elasticity of Lightweight Foamed Concrete under Static Flexural and Compression: An Experimental Investigations

    Directory of Open Access Journals (Sweden)

    Md Azree Othuman Mydin

    2012-09-01

    Full Text Available This paper focused on an experimental works that have been performed to examine the young’s modulus of foamed concrete at elevated temperatures up to 600°C. Foamed concrete of 650 and 1000 kg/m3 density were cast and tested under compression and bending. The experimental results of this study consistently demonstrated that the loss in stiffness for cement based material like foamed concrete at elevated temperatures occurs predominantly after about 95°C, regardless of density. This indicates that the primary mechanism causing stiffness degradation is microcracking, which occurs as water expands and evaporates from the porous body. As expected, reducing the density of LFC reduces its strength and stiffness. However, for LFC of different densities, the normalised strength-temperature and stiffness-temperature relationships are very similar.

  2. Supplementary Material for: Compressing an Ensemble With Statistical Models: An Algorithm for Global 3D Spatio-Temporal Temperature

    KAUST Repository

    Castruccio, Stefano

    2016-01-01

    One of the main challenges when working with modern climate model ensembles is the increasingly larger size of the data produced, and the consequent difficulty in storing large amounts of spatio-temporally resolved information. Many compression algorithms can be used to mitigate this problem, but since they are designed to compress generic scientific datasets, they do not account for the nature of climate model output and they compress only individual simulations. In this work, we propose a different, statistics-based approach that explicitly accounts for the space-time dependence of the data for annual global three-dimensional temperature fields in an initial condition ensemble. The set of estimated parameters is small (compared to the data size) and can be regarded as a summary of the essential structure of the ensemble output; therefore, it can be used to instantaneously reproduce the temperature fields in an ensemble with a substantial saving in storage and time. The statistical model exploits the gridded geometry of the data and parallelization across processors. It is therefore computationally convenient and allows to fit a nontrivial model to a dataset of 1 billion data points with a covariance matrix comprising of 1018 entries. Supplementary materials for this article are available online.

  3. High-temperature properties of mineral wool

    DEFF Research Database (Denmark)

    Augustesen, Maria; Ståhl, Kenny

    Thermal stability and thereby fire safety is an essential property of fibrous insulating materials for buildings. At the same time the viscosity is an important manufacturing property that may impair the thermal stability. This project aims at investigating the thermal stability of some mineral...... behaviour. Figure 1. Isothermal X-ray powder diffraction patterns collected at beamline 711, MAXLAB, Lund, using a Huber G670 Guinier camera. The sample was contained in a 0.5 mm quartz capillary, data were accumulated for 5 min per pattern at T = 1100 K and lambda = 1.2724 Å. Preliminary results show...

  4. effects of temperature on the physicochemical properties

    African Journals Online (AJOL)

    dell

    traditionally processed vegetable oils deteriorate significantly at elevated temperatures (p < 0.05). However, the blends showed relatively better quality and stability than the unblended ones whereby the formulations of palm oil (PO) and sesame oil (SSO) appeared to be more stable than those of PO and sunflower oil (SO).

  5. Study on Dynamic Compressive Mechanical Properties and Failure Modes of Heat-Treated Granite

    Directory of Open Access Journals (Sweden)

    Zhiliang Wang

    Full Text Available Abstract Temperature and external load are two important factors affecting the mechanical properties of rock material. The test on heat- treated granite specimen was carried out by using an improved split Hopkinson pressure bar (SHPB. Based on the test data, the dynamic behavior and failure characteristics of the granite under the coupling action of temperature and impact loading are studied. The results show that the amplitude of incident wave increases with the impact velocity of striker, and the shapes of the transmitted and reflected waves are closely related to the failure state of the specimen. The stress-strain curves for the heat-treated specimens above 700oC are obviously different to those below 500oC in terms of the slopes for the ascending segment and the peak stress, indicating that there is a temperature threshold between 500oC and 700oC. Under the same velocity, the strain rate decreases slightly and then increases as the temperature increases. At a constant temperature, strain rate increases linearly with the impact velocity. The relationship between elastic modulus and strain rate for the heat-treated specimen obviously tends to have no regularity. In addition, both peak stress and peak strain exhibit strain rate sensitivity, but different increasing rates for different temperatures are detected. Below 500oC, the influence of temperature on peak stress and peak strain is not evident, however, the influence becomes remarkable at 700oC and 900oC.

  6. Thermodynamic Properties of Compressed CuX (X = Cl, Br) Compounds: Ab Initio Study

    Science.gov (United States)

    Bioud, Nadhira; Kassali, Kamel; Bouarissa, Nadir

    2017-04-01

    A pseudopotential plane wave method based on the density functional theory has been employed to study some thermodynamic properties of copper chloride (CuCl) and copper bromide (CuBr) compounds under the effect of temperature and pressure. The phase transition pressure, the unit cell volume, the isothermal bulk modulus, the constant volume heat capacity, the entropy, the Debye temperature, the Grüneisen parameter and the volumetric thermal expansion coefficient are studied in the pressure range 0-10 GPa, and for temperatures ranging from 0 K up to 650 K and 750 K for CuCl and CuBr, respectively. The phase transition pressure is found to be around 7.8 and 6.95 GPa for CuCI and CuBr, respectively. These values are respectively in reasonably good agreement with the experimental ones of 8.2 GPa and 6.8 GPa reported in the literature. Moreover, at room temperature and zero pressure, the heat capacity at constant volume and the Grüneisen parameter of both compounds of interest are found to be in good agreement with the available experimental and theoretical data. The information gathered from the present investigation may be useful for the study of the behavior of the fundamental properties of CuCI and CuBr under the influence of high temperature and pressure.

  7. Influence of Moisture Content and Compression Axis on Physico-mechanical Properties of Shorea robusta Seeds

    Science.gov (United States)

    Shashikumar, C.; Pradhan, R. C.; Mishra, S.

    2018-02-01

    Shorea robusta (Sal) is mainly harvested and processed for its seed oil, which has diverse application in commercial food and non-food based industries. Before extraction of its oil, seeds undergo into various post-harvest unit operations. Physical and mechanical properties play an important role in the handling and other processing activity. In this study influence of moisture content and compression axis of sal seed on physico-mechanical properties were studied and their application are highlighted. The experiments were conducted at five different moisture levels of 6.38, 10.49, 13.63, 17.64, and 21.95% (d.b) at two different orientations. The first orientation is on major axis (LEN) of the seed, and the other orientation is on intermediate or minor axis (WID), which is right angle to the major axis. It was observed that 68% of sal seeds were of medium size group at initial moisture content of 10.49% (d.b). The mean length and width of sal seed was found to be 26.7 mm and 12.8 mm, respectively. It was found that values of hardness, deformation at hardness, deformation at hardness percentage and energy for rupture were higher in minor axis (WID) as compared to the major axis (LEN). The results provide necessary data that may be useful to engineers, scientists, industries in the design of a suitable post-harvest processing machine.

  8. Gluten-Free Bread: Influence of Sourdough and Compressed Yeast on Proofing and Baking Properties

    Directory of Open Access Journals (Sweden)

    Carola Cappa

    2016-10-01

    Full Text Available The use of sourdough is the oldest biotechnological process to leaven baked goods, and it represents a suitable technology to improve traditional bread texture, aroma, and shelf life. A limited number of studies concerning the use of sourdough in gluten-free (GF breadmaking have been published in comparison to those on traditional bread. The aim of this study was to compare the properties of GF breads obtained by using a previously in-lab developed GF-sourdough (SD, compressed yeast (CY; Saccharomyces cerevisiae or their mixture (SDCY as leavening agents; more specifically, it aims to confirm the findings of a previous studies and to further improve (both in terms of recipe and process the features of the resulting GF breads. Dough pH and rheological properties were measured. Fresh and stored breads were characterized for weight, height, specific volume, crust and crumb color, moisture, water activity, crumb hardness, and porosity. The combination SDCY was effective in improving bread volume and softness when compared to SD only. Furthermore, SD- and SDCY-crumbs exhibited a less crumbly behavior during storage (69 h, 25 °C, 60% of relative humidity in comparison to CY-breads. This study confirms the positive effect of SD in GF breadmaking, in particular when used in combination with CY.

  9. Cavitation of intercellular spaces is critical to establishment of hydraulic properties of compression wood of Chamaecyparis obtusa seedlings.

    Science.gov (United States)

    Nakaba, Satoshi; Hirai, Asami; Kudo, Kayo; Yamagishi, Yusuke; Yamane, Kenichi; Kuroda, Katsushi; Nugroho, Widyanto Dwi; Kitin, Peter; Funada, Ryo

    2016-03-01

    When the orientation of the stems of conifers departs from the vertical as a result of environmental influences, conifers form compression wood that results in restoration of verticality. It is well known that intercellular spaces are formed between tracheids in compression wood, but the function of these spaces remains to be clarified. In the present study, we evaluated the impact of these spaces in artificially induced compression wood in Chamaecyparis obtusa seedlings. We monitored the presence or absence of liquid in the intercellular spaces of differentiating xylem by cryo-scanning electron microscopy. In addition, we analysed the relationship between intercellular spaces and the hydraulic properties of the compression wood. Initially, we detected small intercellular spaces with liquid in regions in which the profiles of tracheids were not rounded in transverse surfaces, indicating that the intercellular spaces had originally contained no gases. In the regions where tracheids had formed secondary walls, we found that some intercellular spaces had lost their liquid. Cavitation of intercellular spaces would affect hydraulic conductivity as a consequence of the induction of cavitation in neighbouring tracheids. Our observations suggest that cavitation of intercellular spaces is the critical event that affects not only the functions of intercellular spaces but also the hydraulic properties of compression wood. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  10. Influence of Mechanically Activated Electric Arc Furnace Slag on Compressive Strength of Mortars Incorporating Curing Moisture and Temperature Effects

    Directory of Open Access Journals (Sweden)

    Muhammad Nasir Amin

    2017-07-01

    Full Text Available In this study, the influence of mechanically activated electric arc furnace slag (EAFS was investigated through compressive strength tests on 50 mm mortar cubes. The objective was to convert the wasteful EAFS into a useful binding material to reduce the cement content in concrete without compromising strength and economy. Four different groups of mortar were cast which include control mortar, reference fly ash mortar, mortar containing EAFS to determine its optimum fineness and replacement with cement, mortar blend containing fly ash and EAFS of optimum fineness. EAFS were identified with respect to its fineness as slag ground (SG, slag-fine (SF 100% passing 75 µm sieve, and slag-super-fine (SSF 100% passing 45 µm sieve. Compressive strength was measured according to ASTM C109. Specimens were cured under different temperatures and moisture to incorporate the effects of normal and hot environmental conditions. Compressive strength of mortars increases with fineness of EAFS and its strength activity index matches the ASTM C989 blast furnace slag (BFS Grade 80 up to 30% cement substitution and Grade 100 when 10% cement substituted with SSF. The influence of curing temperatures was also significant in mortars containing SG or 10% SF where strength decreased with increasing curing temperature. However, a 20–30% and 20% cement substitution with SF produced strength comparable to control and reference fly ash mortars under moderate (40 °C and high curing temperature (60 °C, respectively. The utilization of EAFS as binder in concrete may reduce needs for cement, as well as save environment and natural resources from depletion.

  11. Influence of the gypsum dehydration temperature and alkali additives on the properties of anhydrite cement

    Directory of Open Access Journals (Sweden)

    Leskeviciene V.

    2010-01-01

    Full Text Available While dehydrating gypsum with additives at the temperatures of 800°C and 900°C the influence of alkali additives on both the crystalline structure of anhydrite and properties of anhydrite binder was investigated. The industrial and household wastes including other lowcost materials were used as additives. Having heated them with gypsum the anhydrite with alkali activation properties was obtained. The properties of such substances were evaluated using the methods of chemical, diffractive X-ray scanning and scanning electron microscopy (SEM analyses. Some additives, e.g. 5 % ground glass waste, were found to increase crystal agglomerate formation of anhydrite binder, accelerate the hydration process of anhydrite and double the compressive strength of hydrated samples compared to samples without additives.

  12. Review of temperature dependence of thermal properties, dielectric properties, and perfusion of biological tissues at hyperthermic and ablation temperatures.

    Science.gov (United States)

    Rossmanna, Christian; Haemmerich, Dieter

    2014-01-01

    The application of supraphysiological temperatures (>40°C) to biological tissues causes changes at the molecular, cellular, and structural level, with corresponding changes in tissue function and in thermal, mechanical and dielectric tissue properties. This is particularly relevant for image-guided thermal treatments (e.g. hyperthermia and thermal ablation) delivering heat via focused ultrasound (FUS), radiofrequency (RF), microwave (MW), or laser energy; temperature induced changes in tissue properties are of relevance in relation to predicting tissue temperature profile, monitoring during treatment, and evaluation of treatment results. This paper presents a literature survey of temperature dependence of electrical (electrical conductivity, resistivity, permittivity) and thermal tissue properties (thermal conductivity, specific heat, diffusivity). Data of soft tissues (liver, prostate, muscle, kidney, uterus, collagen, myocardium and spleen) for temperatures between 5 to 90°C, and dielectric properties in the frequency range between 460 kHz and 3 GHz are reported. Furthermore, perfusion changes in tumors including carcinomas, sarcomas, rhabdomyosarcoma, adenocarcinoma and ependymoblastoma in response to hyperthmic temperatures up to 46°C are presented. Where appropriate, mathematical models to describe temperature dependence of properties are presented. The presented data is valuable for mathematical models that predict tissue temperature during thermal therapies (e.g. hyperthermia or thermal ablation), as well as for applications related to prediction and monitoring of temperature induced tissue changes.

  13. Physical properties of compressive knits compound with different matters impregnated by microcapsules moisturizing

    OpenAIRE

    Fadhel Jaâfar; Mahdi Sahnoun; Morched Cheikhrouhou

    2011-01-01

    The compressive knits include a very varied group of different device functions, from the more merely (protection) to the more developed (scars improvement, skin hydration…). We combined two therapy forms the pressure and the hydration of burned skin. We essayed to reunite the advantages of two techniques pressure and hydration in only one and the same instrument in the form of compressive knit with microencapsulated surface. The compressive knits are elaborated with different textile m...

  14. Molecular Dynamics Modeling of the Effect of Axial and Transverse Compression on the Residual Tensile Properties of Ballistic Fiber

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    Sanjib C. Chowdhury

    2017-02-01

    Full Text Available Ballistic impact induces multiaxial loading on Kevlar® and polyethylene fibers used in protective armor systems. The influence of multiaxial loading on fiber failure is not well understood. Experiments show reduction in the tensile strength of these fibers after axial and transverse compression. In this paper, we use molecular dynamics (MD simulations to explain and develop a fundamental understanding of this experimental observation since the property reduction mechanism evolves from the atomistic level. An all-atom MD method is used where bonded and non-bonded atomic interactions are described through a state-of-the-art reactive force field. Monotonic tension simulations in three principal directions of the models are conducted to determine the anisotropic elastic and strength properties. Then the models are subjected to multi-axial loads—axial compression, followed by axial tension and transverse compression, followed by axial tension. MD simulation results indicate that pre-compression distorts the crystal structure, inducing preloading of the covalent bonds and resulting in lower tensile properties.

  15. Material test machine for tension-compression tests at high temperature

    Science.gov (United States)

    Cioletti, Olisse C.

    1988-01-01

    Apparatus providing a device for testing the properties of material specimens at high temperatures and pressures in controlled water chemistries includes, inter alia, an autoclave housing the specimen which is being tested. The specimen is connected to a pull rod which couples out of the autoclave to an external assembly which includes one or more transducers, a force balance chamber and a piston type actuator. The pull rod feeds through the force balance chamber and is compensated thereby for the pressure conditions existing within the autoclave and tending to eject the pull rod therefrom. The upper end of the push rod is connected to the actuator through elements containing a transducer comprising a linear variable differential transformer (LVDT). The housing and coil assembly of the LVDT is coupled to a tube which runs through a central bore of the pull rod into the autoclave where it is connected to one side of the specimen. The movable core of the LVDT is coupled to a stem which runs through the tube where it is then connected to the other side of the specimen through a coupling member. A transducer in the form of a load cell including one or more strain gages is located on a necked-down portion of the upper part of the pull rod intermediate the LVDT and force balance chamber.

  16. Aging and Curing Temperature Effects on Compressive Strength of Mortar Containing Lime Stone Quarry Dust and Industrial Granite Sludge

    Directory of Open Access Journals (Sweden)

    Muhammad Nasir Amin

    2017-06-01

    Full Text Available In this study, the researchers investigated the potential use of locally available waste materials from the lime stone quarry and the granite industry as a partial replacement of cement. Quarry sites and granite industry in the eastern province of Saudi Arabia produces tons of powder wastes in the form of quarry dust (QD and granite sludge (GS, respectively, causing serious environmental problems along with frequent dust storms in the area. According to ASTM C109, identical 50-mm3 specimens were cast throughout this study to evaluate the compressive strength development of mortars (7, 28 and 91 days containing these waste materials. Experimental variables included different percentage replacement of cement with waste materials (GS, QD, fineness of GS, various curing temperatures (20, 40 and 60 °C as local normal and hot environmental temperatures and curing moisture (continuously moist and partially moist followed by air curing. Finally, the results of mortar containing waste materials were compared to corresponding results of control mortar (CM and mortar containing fly ash (FA. The test results indicated that under normal curing (20 °C, moist cured, the compressive strength of mortar containing the different percentage of waste materials (QD, GS, FA and their combinations remained lower than that of CM at all ages. However, the compressive strength of mortar containing waste materials slightly increased with increased fineness of GS and significantly increased under high curing temperatures. It was recommended that more fineness of GS be achieved to use its high percentage replacement with cement (30% or more incorporating local environmental conditions.

  17. Aging and Curing Temperature Effects on Compressive Strength of Mortar Containing Lime Stone Quarry Dust and Industrial Granite Sludge.

    Science.gov (United States)

    Amin, Muhammad Nasir; Khan, Kaffayatullah; Saleem, Muhammad Umair; Khurram, Nauman; Niazi, Muhammad Umar Khan

    2017-06-11

    In this study, the researchers investigated the potential use of locally available waste materials from the lime stone quarry and the granite industry as a partial replacement of cement. Quarry sites and granite industry in the eastern province of Saudi Arabia produces tons of powder wastes in the form of quarry dust (QD) and granite sludge (GS), respectively, causing serious environmental problems along with frequent dust storms in the area. According to ASTM C109, identical 50-mm3 specimens were cast throughout this study to evaluate the compressive strength development of mortars (7, 28 and 91 days) containing these waste materials. Experimental variables included different percentage replacement of cement with waste materials (GS, QD), fineness of GS, various curing temperatures (20, 40 and 60 °C as local normal and hot environmental temperatures) and curing moisture (continuously moist and partially moist followed by air curing). Finally, the results of mortar containing waste materials were compared to corresponding results of control mortar (CM) and mortar containing fly ash (FA). The test results indicated that under normal curing (20 °C, moist cured), the compressive strength of mortar containing the different percentage of waste materials (QD, GS, FA and their combinations) remained lower than that of CM at all ages. However, the compressive strength of mortar containing waste materials slightly increased with increased fineness of GS and significantly increased under high curing temperatures. It was recommended that more fineness of GS be achieved to use its high percentage replacement with cement (30% or more) incorporating local environmental conditions.

  18. Effect of heat bed temperature of 3D bioprinter to hardness and compressive strength of scaffold bovine hydroxyapatite

    Science.gov (United States)

    Triyono, Joko; Pratama, Aditya; Sukanto, Heru; Nugroho, Yohanes; Wijayanta, Agung Tri

    2018-02-01

    This study aimed to investigate the effect of heat bed temperature of 3D bioprinter toward compressive strength and hardness bovine bone hydroxyapatite scaffold for bone filler applications. BHA-glycerin mixed with a ratio of 1:1, and keep it for 24 hours. After the homogenization process acquired, bio-Ink with shaped slurry will be used as a material for a 3D printer. The printing process with a temperature variation have performed by setting up heat bed temperature. After printing process was completed, the 3D scaffold was detained on the heat bed for 10 minutes before being picked up. The test results in this study had the lowest hardness value of 9.82±0.62 VHN and the highest number of 24.32±0.99 VHN. The compressive strength testing had the lowest value of 1.62±0.16 MPa with the highest number of 5.67±0.39 MPa. Pore observation using a scanning electron microscope. The result shows that the size of the pores were not much different, that was ±100-200 µm. This observation also indicated that the pore form was square pores.

  19. The Effects of Ore Properties on the Characterization of Suspension in Settling and Compression

    Directory of Open Access Journals (Sweden)

    Majid Unesi

    2014-06-01

    Full Text Available Many studies have considered the effects of suspension properties on the dewatering process but fewhave focused on ore properties. Thus, the present work studied the effects of ore properties (density,particle size, mineralogy on the dewatering process based on lab and pilot experiments. A hydrocyclonewas used to prepare the required samples for the experiments. To study the effects of mineralogicalproperties, the sedimentation behaviour of hydrocyclone feed and underflow samples were compared. Itwas observed that the free-settling velocity of feed (2 to 6mm/sec was less than in the underflow sample(2 to 7mm/sec and the final concentration of underflow sample (0.45 to 0.48t/m3 was more than thefeed sample (0.44 to 0.47t/m3. Additionally, to study the effects of particle size and density, thesedimentation behaviour of hydrocyclone overflow and feed samples were compared. The settlingvelocity and final concentration of overflow sample were obtained at 0.15 to 0.4mm/sec and 0.32t/m3,respectively, which was significantly less than the feed sample. This was due to the amount of clayreduction in the underflow sample and particle size and density reduction in the overflow sample.Following on, the pilot experiments were carried out. It was observed that the bed formation of the feedsample tended to overflow in the sample at low flux (10t/m2/day and tended to underflow in the sampleat high flux (28.5t/m2/day. This meant that the long time at lower flux created an opportunity for fineparticles to settle easily, similar to coarser particles and as such, ore properties did not play a decisiverole in bed formation, but their effects appeared instead at higher flux. Furthermore, it was observed thatthe underflow concentration increased by decreasing the flux from 28.5 to 10t/m2/day. These increasingamounts were 0.05t/m3 and 0.12t/m3 in hydrocyclone overflow and underflow samples, respectively, at aheight of 2.5 metres. This meant that the compressibility and

  20. Improving powder flow properties of a direct compression formulation using a two-step glidant mixing process.

    Science.gov (United States)

    Abe, Hidaka; Yasui, Shinichiro; Kuwata, Aya; Takeuchi, Hirofumi

    2009-07-01

    To improve powder flow of a high-dose direct compression formulation (drug content 30%), we compared a two-step operation for mixing glidants with a conventional one-step glidant mixing process. This two-step mixing operation was studied with two kinds of mixtures; an active pharmaceutical ingredient (API)-glidant combination and a direct compression excipient-glidant combination. The two-step operation permitted the selection of the optimum glidant type and concentration in each glidant-mixing procedure even though the formulation had different powder properties such as micronized API and enlarged direct compression vehicles, whereas the conventional approaches forced the selection of a certain glidant type and concentration at one-step mixing. The addition of 0.5% nonporous silica markedly improved API flow. In contrast, 1.0% porous silica was the appropriate glidant to enhance excipient flow at direct compression excipient-glidant mixing. The two-step operation dominantly enhanced powder flow when the appropriate API-glidant mixture and the suitable direct compression excipients-glidant mixture were blended compared to the one-step operation with its optimum glidant concentration. The results showed that the angle of repose was 43 degrees and the critical orifice diameter was 10 mm in the two-step operation, whereas it was 47 degrees and 16 mm in the one-step operation. The two-step operation of glidant mixing enhanced powder flow of the high-dose direct compression formulation compared with the one-step operation. The two-step operation eliminates the bottleneck of powder flow and allows direct compression to be more worth applying for formulation and process development trials.

  1. Properties and Structure of X30MnAlSi26-4-3 High Strength Steel Subjected to Dynamic Compression Processes

    Directory of Open Access Journals (Sweden)

    Śmiglewicz A.

    2017-12-01

    Full Text Available The paper presents the results of investigation on X30MnAlSi26-4-3 austenitic steel subjected to dynamic compression using the split Hopkinson pressure bar. The strain rate was 3700 s−1. The compression test was also carried out without the use of breaking rings and then true strain was about 0.3. The split Hopkinson pressure bar test take only few milliseconds to complete during which time it is impossible to transfer the excess heat out of the specimen, therefore the test must be carried out in adiabatic conditions and so the increase of the temperature caused by the work of plastic deformation had to be calculated. The stepping load method was used in order to evaluate the effect of adiabatic heating on the properties of steel which allowed to maintain the isothermal deformation conditions. The paper presents the comparison of results obtained during deformation under adiabatic and isothermal conditions in correlation to structure changes occurring in course of dynamic compression.

  2. Containerless high temperature property measurements by atomic fluorescence

    Science.gov (United States)

    Schiffman, R. A.; Walker, C. A.

    1984-01-01

    Laser induced fluorescence (LIF) techniques for containerless study of high temperature processes and material properties was studied. Gas jet and electromagnetic levitation and electromagnetic and laser heating techniques are used with LIF in earth-based containerless high temperature experiments. Included are the development of an apparatus and its use in the studies of (1) chemical reactions on Al2O3, molybdenum, tungsten and LaB6 specimens, (2) methods for noncontact specimen temperature measurement, (3) levitation jet properties and (4) radiative lifetime and collisional energy transfer rates for electronically excited atoms.

  3. temperature

    Directory of Open Access Journals (Sweden)

    G. Polt

    2015-10-01

    Full Text Available In-situ X-ray diffraction was applied to isotactic polypropylene with a high volume fraction of α-phase (α-iPP while it has been compressed at temperatures below and above its glass transition temperature Tg. The diffraction patterns were evaluated by the Multi-reflection X-ray Profile Analysis (MXPA method, revealing microstructural parameters such as the density of dislocations and the size of coherently scattering domains (CSD-size. A significant difference in the development of the dislocation density was found compared to compression at temperatures above Tg, pointing at a different plastic deformation mechanism at these temperatures. Based on the individual evolutions of the dislocation density and CSD-size observed as a function of compressive strain, suggestions for the deformation mechanisms occurring below and above Tg are made.

  4. Evaluation Some Properties of NanoMetakaolin or Rice Husk Ash Cement Mortar and its Resistance to Elevated Temperature

    Directory of Open Access Journals (Sweden)

    Jassim Atiya Alwan

    2016-12-01

    Full Text Available The objective of this research is to find the optimum value of some properties like compressive, flexural strength of blended cement mortar by nanometakaolin ( NMK or rice husk ash (RHA and to evaluate the effect of high temperature on these properties. The ordinary Portland cement(OPC of mortar was partially substituted by NMK or RHA of 5,10,15 and 20% by weight of cement. (108 control and blended specimens were casted and tested at ambient temperature (33 ºC for compressive and flexural strength for 28 and 90 days. Another (270 of the control and blended specimens were casted and cured for 90 days and exposed to elevated temperature of a gradual increase in temperature up to 200 ºC,300 ºC, 400 ºC,600 ºC and 800 ºC for two hours in an electrical furnace and they were under the same previous tests. The test results at ambient temperature indicate that the optimum compressive and flexural strength was with ratio of 15% NMK cement replacement in mortar for 28 and 90 days but for RHA was ratio of 10% for 28 days and 15% of cement weight in mortar for 90 days compared to control specimens. The results of exposing control and blended specimens of (90 days to elevated temperature showed that the optimum strength for control and the best MK replacement ratio were found at 200 ºC, and the best RHA replacement ratio specimens was found at 300 ºC. It is also found that exposing the mortar to more than these temperatures destroyed its strength and it was detrimental to its properties.

  5. Effect of high temperature curing on the compressive strength of concrete incorporating large volumes of fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Rivera-Villarreal, R. [Universidad Autonoma de Nuevo Leon, Monterrey (Mexico)

    2001-07-01

    The effect of using different types of heat treatment on the compressive strength of concrete with and without large volumes of fly ash was studied. Curing of concrete is important to obtain a good quality concrete, but it is important to keep concrete from drying until the originally water-filled space in fresh cement paste has been filled to the desired extent by the products of hydration. In hot weather, high temperature promotes faster drying of concrete so a given degree of hydration is reached more rapidly than at lower temperatures. The provision of moist curing is advantageous because of a gradual gain in strength and because of reduced plastic shrinkage and drying shrinkage-cracking. The portland cement content in all the mixtures used in this study was 200 kg per cubic metre and the amount of fly ash varied from 0 to 33, 43, 50 and 56 per cent by mass of the total binder. A superplasticizer was used to obtain 200-220 mm slump. The compressive strength was tested at 3, 7, 14, 28, 56 days and at 6 months. Results showed that, using ASTM standard curing, the compressive strength of portland cement concrete made at 35 degrees C was reduced by about 12 per cent at 28 days compared to that of the concrete made at 23 degrees C. The AASHTO curing strength was found to be a bit higher than with the ASTM curing. The concrete made at 35 degrees C showed no loss of strength when continuous moist-curing was applied. The fly ash concrete mixtures that were cast at 35 degrees C were cured by covering them with membrane curing compounds and placed under ambient conditions. It was crucial to allow enough curing water to promote the pozzolanic reaction. The membrane curing did not allow the ingress of water to the concrete mass. 6 refs., 4 tabs., 13 figs.

  6. Beyond mean-field properties of binary dipolar Bose mixtures at low temperatures

    Science.gov (United States)

    Pastukhov, Volodymyr

    2017-02-01

    We rigorously analyze the low-temperature properties of homogeneous three-dimensional two-component Bose mixture with dipole-dipole interaction. For such a system the effective hydrodynamic action that governs the behavior of low-energy excitations is derived. The infrared structure of the exact single-particle Green's functions is obtained in terms of macroscopic parameters, namely the inverse compressibility and the superfluid density matrices. Within the one-loop approximation we calculate some of the most relevant observable quantities and give the beyond mean-field stability condition for the binary dipolar Bose gas in the dilute limit. A brief variational derivation of the coupled equations that describe macroscopic hydrodynamics of the system in the external nonuniform potential at zero temperature is presented.

  7. Low temperature preparation of α-tricalcium phosphate and its mechanical properties

    Directory of Open Access Journals (Sweden)

    Song Wang

    2017-06-01

    Full Text Available In this work, α-tricalcium phosphate (α-TCP was successfully prepared by the thermal transformation of amorphous calcium phosphate (ACP precursor. β-cyclodextrin (β-CD was used for preparation of ACP precursor and played an important role in designing its special structure. The phase composition and microstructures of the obtained α-TCP at different annealing temperature were analysed by X-ray diffraction and scanning electron microscope, and confirmed that α-TCP can be prepared at 650°C for 3 h using ACP as precursor, which is much lower than the phase transition temperature of α-TCP. Mechanical properties were tested 24 h after mixing the obtained α-TCP with 30 wt.% of deionised water. The compressive strength and the flexural strength were 26.4MPa and 12.0MPa, respectively. The flexural strength was higher than that of α-TCP prepared by other methods.

  8. Effect of Rigid Polyurethane Foam Core Density on Flexural and Compressive Properties of Sandwich Panels with Glass/Epoxy Faces

    Directory of Open Access Journals (Sweden)

    saeed Nemati

    2013-01-01

    Full Text Available Sandwich panels as composite materials have two external walls of either metallic or polymer type. The space between these walls is filled by hard foam or other materials and the thickness of different layers is based on the final application of the panel. In the present work, the extent of variation in core density of polyether urethane foam and subsequent flexural and compressive changes in sandwich panels with glass or epoxy face sheets are tested and investigated. A number of hard polyether urethane foams with different middle panel layers density 80-295 kg/m3 are designed to study the effect of foam density on mechanical properties including flexural and compressive properties. Flexural and compressive test resultsshow that increased core density leads to improved mechanical properties. The slope of the curve decreases beyond density of 235 kg/m3. The reason may be explained on the limitation of shear intensity in increasing the mechanical properties. In this respect an optimum density of 235 kg/m3 is obtained for the system under examinations and for reaching higher strength panels, foams of different core materials should be selected.

  9. Mechanical and thermal properties of glass-fiber-reinforced composities at cryogenic temperatures

    International Nuclear Information System (INIS)

    Khalil, A.; Han, K.S.

    1982-01-01

    Khalil and Han investigate, in this study, materials that are capable of being used in struts for large superconducting energy storage magnets. The candidate matrials that poses the requisite high strength-to-weight ratios and low thermal conductivities are fiberglass-epoxy and polyester composites. This investigation focuses on fiberglass-epoxy composites (G-10CR), on polyester fiberglass (Extren), and on glass-fiber-wound epoxy composite tubes (GFW AT-1008). The mechanical properties tested were the compressive strength, eslastic modulus, fatigue, and fracture behavior at 300 K and at 77 K. thermal conductivity, heat diffusivity, and specific heat were also tested in the temperature range of 4-300 K. Specifications for the samples, the test equipment, and the procedures are given, along with tables and photographs of the results. Calculation methods for various properties are described. A comparative evaluation of the materials is discussed

  10. Influence of binder type and process parameters on the compression properties and microbial survival in diclofenac tablet formulations

    Directory of Open Access Journals (Sweden)

    John Oluwasogo Ayorinde

    2011-12-01

    Full Text Available The influence of binder type and process parameters on the compression properties and microbial survival in diclofenac tablet formulations were studied using a novel gum from Albizia zygia. Tablets were produced from diclofenac formulations containing corn starch, lactose and dicalcium phosphate. Formulations were analyzed using the Heckel and Kawakita plots. Determination of microbial viability in the formulations was done on the compressed tablets of both contaminated and uncontaminated tablets prepared from formulations. Direct compression imparted a higher plasticity on the materials than the wet granulation method. Tablets produced by wet granulation presented with a higher crushing strength than those produced by the direct compression method. Significantly higher microbial survival (pA influência do tipo de ligante e os parâmetros do processo de propriedades de compressão e sobrevivência microbiana em comprimidos de diclofenaco foram estudados utilizando uma nova goma de Albizia zygia. Os comprimidos foram produzidos a partir de formulações de diclofenaco contendo amido de milho, lactose e fosfato bicálcico. As formulações foram analisadas usando os gráficos de Heckel e Kawakita. A determinação da viabilidade microbiana nas formulações foi feita nos comprimidos contaminados e não contaminados preparados a partir de formulações. A compressão direta confere maior plasticidade dos materiais do que o método de granulação úmida. Comprimidos produzidos por granulação úmida apresentaram maior força de esmagamento do que aqueles produzidos pelo método de compressão direta. Observou-se sobrevivência significativamente maior (p<0,05 em formulações preparadas por compressão direta. A sobrevivência percentual dos esporos de Bacillus subtilis diminuiu com o aumento da concentração do agregante. O estudo mostrou que a goma de Albizia é capaz de conferir maior plasticidade aos materiais e apresentou maior redução da

  11. Study on the properties of the fuel compact for High Temperature Gas-cooled Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chung-yong; Lee, Sung-yong; Choi, Min-young; Lee, Seung-jae; Jo, Young-ho [KEPCO Nuclear Fuel, Daejeon (Korea, Republic of); Lee, Young-woo; Cho, Moon-sung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    High Temperature Gas-cooled Reactors (HTGR), one of the Gen-IV reactors, have been using the fuel element which is manufactured by the graphite matrix, surrounding Tristructural-isotropic (TRISO)-coated Uranium particles. Factors with these characteristics effecting on the matrix of fuel compact are chosen and their impacts on the properties are studied. The fuel elements are considered with two types of concepts for HTGR, which are the block type reactor and the pebble bed reactor. In this paper, the cylinder-formed fuel element for the block type reactor is focused on, which consists of the large part of graphite matrix. One of the most important properties of the graphite matrix is the mechanical strength with the high reliability because the graphite matrix should be enabled to protect the TRISO particles from the irradiation environment and the impact from the outside. In this study, the three kinds of candidate graphites and the two kinds of candidate binder (Phenol and Polyvinyl butyral) were chosen and mixed with each other, formed and heated to measure mechanical properties. The objective of this research is to optimize the materials and composition of the mixture and the forming process by evaluating the mechanical properties before/after carbonization and heat treatment. From the mechanical test results, the mechanical properties of graphite pellets was related to the various conditions such as the contents and kinds of binder, the kinds of graphite and the heat treatments. In the result of the compressive strength and Vicker's hardness, the 10 wt% phenol binder added R+S graphite pellet was relatively higher mechanical properties than other pellets. The contents of Phenol binder, the kinds of graphite powder and the temperature of carbonization and heat treatment are considered important factors for the properties. To optimize the mechanical properties of fuel elements, the role of binders and the properties of graphites will be investigated as

  12. Effect of Glass Reinforced Epoxy (GRE pipe filled with Geopolymer Materials for Piping Application: Compression Properties

    Directory of Open Access Journals (Sweden)

    Abu Hashim Mohammad Firdaus

    2016-01-01

    Full Text Available The aim of this paper is to achieve the highest compressive strength of glass reinforced epoxy pipe with the geopolymer filler content of weight percentage that were used in glass reinforced epoxy pipe. The samples were prepared by using the filament winding method. The effect of weight percentage of geopolymer materials in epoxy hardener was studied under mechanical testing, which is using the compression test. A series of glass reinforced epoxy pipe and glass reinforced epoxy pipe filled with 10 – 40 weight percentage geopolymer filler which is white clay were prepared. The compression strength of the glass reinforced epoxy pipe filled geopolymer materials is determined using Instron Universal Testing under compression mode. It was found that compressive strength for samples with white clay geopolymer filler are much higher compare to glass reinforced epoxy pipe without geopolymer filler. Moreover, the compressive strength of glass reinforced epoxy pipe filled with white clay geopolymer filler was increased from 10 wt% to 30 wt% of geopolymer content. However, the compressive strength of glass reinforced epoxy pipe with white clay geopolymer filler suddenly decreased when added to 40 wt%. The results indicated that the blending of geopolymer materials in epoxy system can be obtained in this study.

  13. Compressive strength, plastic flow properties, and surface frictional effects of 1100, 3003 and 6061 aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pinkerton, Gary Wayne [Univ. of Illinois, Urbana-Champaign, IL (United States)

    1993-01-01

    The purpose of this study is to find aluminum alloys that are effective for use as wire vacuum seals in the 800MeV particle accelerator located at the Louis Anderson Meson Physics Facility (LAMPF) in Los Alamos, NM. Three alloys, Al 1100, Al 3003, and Al 6061, are investigated under uniaxial compression to determine stresses for a given height reduction from 0 to 70 percent, and to find plastic flow and surface interaction effects. Right-circular cylindrical specimens are compressed on-end (cylindrically) and radially (for modeling as compressed wire). Aluminum 1100 and 3003 alloys are compared for length to diameter ratios of 1 and 2 for both compression types, and are then compared to results of radial compression of annealed small diameter Al 1100 wire currently used at LAMPE. The specimens are also compressed between three different platen surfaces, polished steel, etched steel, and aluminum 6061-T6, to determine effects of friction. The Al 3003 alloy exhibits 20 to 25% lower stresses at all height reductions than Al 1100 for both cylindrical and radial compression.

  14. Compressive strength, plastic flow properties, and surface frictional effects of 1100, 3003 and 6061 aluminum alloys

    International Nuclear Information System (INIS)

    Pinkerton, G.W.

    1993-01-01

    The purpose of this study is to find aluminum alloys that are effective for use as wire vacuum seals in the 800MeV particle accelerator located at the Louis Anderson Meson Physics Facility (LAMPF) in Los Alamos, NM. Three alloys, Al 1100, Al 3003, and Al 6061, are investigated under uniaxial compression to determine stresses for a given height reduction from 0 to 70 percent, and to find plastic flow and surface interaction effects. Right-circular cylindrical specimens are compressed on-end (cylindrically) and radially (for modeling as compressed wire). Aluminum 1100 and 3003 alloys are compared for length to diameter ratios of 1 and 2 for both compression types, and are then compared to results of radial compression of annealed small diameter Al 1100 wire currently used at LAMPE. The specimens are also compressed between three different platen surfaces, polished steel, etched steel, and aluminum 6061-T6, to determine effects of friction. The Al 3003 alloy exhibits 20 to 25% lower stresses at all height reductions than Al 1100 for both cylindrical and radial compression

  15. The effect of additives on properties, performance and emission of biodiesel fuelled compression ignition engine

    International Nuclear Information System (INIS)

    Rashedul, H.K.; Masjuki, H.H.; Kalam, M.A.; Ashraful, A.M.; Ashrafur Rahman, S.M.; Shahir, S.A.

    2014-01-01

    Highlights: • Fuel additives significantly improve the quality of biodiesel and its blends. • Fuel additives used to enhance biodiesel properties. • Fuel saving from optimized vehicle performance and economy with the use of additives. • Emission reduction from fuel system cleanliness and combustion optimization. - Abstract: With growing concern over greenhouse gases there is increasing emphasis on reducing CO 2 emissions. Despite engine efficiency improvements plus increased dieselization of the fleet, increasing vehicle numbers results in increasing CO 2 emissions. To reserve this trend the fuel source must be changed to renewable fuels which are CO 2 neutral. As a renewable, sustainable and alternative fuel for compression ignition engines, biodiesel is widely accepted as comparable fuel to diesel in diesel engines. This is due to several factors like decreasing the dependence on imported petroleum, reducing global warming, increasing lubricity, and reducing substantially the exhaust emissions from diesel engine. However, there is a major disadvantage in the use of biodiesel as it has lower heating value, higher density and higher viscosity, higher fuel consumption and higher NO X emission, which limits its application. Here fuel additives become essential and indispensable tools not only to minimize these drawbacks but also generate specified products to meet the regional and international standards. Fuel additives can contribute towards fuel economy and emission reduction either directly or indirectly. Their use enable vehicle performance to be maintained at, or near, optimum over the lifetime of the vehicle. A variety of additives are used in automotive biodiesel fuel to meet specification limits and to enhance quality. For example, metal based additives, oxygenated additives, antioxidants, cetane number improvers, lubricity improvers and cold flow improvers are used to meet specifications and quality. This article is a literature review of the effect

  16. Moisture content and the properties of lodgepole pine logs in bending and compression parallel to the grain

    Science.gov (United States)

    David W. Green; Thomas M. Gorman; Joseph F. Murphy; Matthew B. Wheeler

    2007-01-01

    This study evaluates the effect of moisture content on the properties of 127- to 152.4-mm (5- to 6-in.-) diameter lodgepole pine (Pinus contorta Engelm.) logs that were tested either in bending or in compression parallel to the grain. Lodgepole pine logs were obtained from a dense stand near Seeley Lake, Montana, and sorted into four piles of 30 logs each. Two groups...

  17. A comparative study of accuracy and convergence properties of upwind schemes for the compressible Navier-Stokes equations

    Science.gov (United States)

    Fortin, F.; Degrez, G.

    An investigation of the accuracy and convergence properties of various upwind schemes for the compressible Navier-Stokes equations has been performed. Explicit operators included van Leer's FVS and Roe's FDS at first and second order. Implicit operators included first order van Leer FVS and first order Steger and Warming FVS using true or approximate jacobians. Finally, horizontal and vertical line Gauss-Seidel, and approximate factorization solution strategies were compared.

  18. Effect of substrate temperature and post annealing temperature on ZnO:Zn PLD thin film properties

    Science.gov (United States)

    Hasabeldaim, E.; Ntwaeaborwa, O. M.; Kroon, R. E.; Coetsee, E.; Swart, H. C.

    2017-12-01

    The pulsed laser deposition (PLD) substrate temperature and post-annealing temperature are effective methods to control the film optical and structural properties. The structure, morphology and optical properties of the deposited and post-annealed PLD ZnO:Zn films were studied. The films were deposited at different substrate temperatures of 50 °C, 200 °C and 400 °C. The films deposited at the substrate temperature of 50 °C and 200 °C were post-annealed in air at 400 °C and 600 °C for two hours. The films all had a highly preferential orientation with the hexagonal c-axis perpendicular to the substrate surface. The stress was found to be compressive stress with values -3.289 GPa, -4.864 GPa and -4.425 GPa for the film deposited at 50 °C, 200 °C and 400 °C, respectively. After post-annealing treatments, the stress of the films was almost completely released and stress-free films were obtained. The crystallite sizes were 19 nm, 25 nm and 39 nm, while the average particles sizes were 95 nm, 85 nm and 129 nm for the film deposited at 50 °C, 200 °C and 400 °C respectively. The crystallite sizes and particles sizes seemed to increase with the increase in the substrate temperature. Contrary to this, the change in crystallite sizes were inversely proportional to the particles size when increasing the post-annealing temperatures. Deconvoluted X-ray photoelectron spectroscopy peaks of the O1s binding energy region revealed that the films deposited at different substrate temperatures contained oxygen-related defects. Photoluminescence studies revealed that the films all emitted ultra-violet emission around 379 nm. The film deposited at 50 °C emitted a broad green emission centered at ∼524 nm. By increasing the substrate temperature up to 200 °C and 400 °C a new orange emission around 621 nm and 634 nm as well as a weak emission around 416 nm and 500 nm were observed, respectively. After post-annealing treatments, new bands over the visible region (blue, green

  19. Compressibility of tableting materials and properties of tablets with glyceryl behenate

    Directory of Open Access Journals (Sweden)

    Mužíková Jitka

    2015-03-01

    Full Text Available The paper studies the compressibility of directly compressible tableting materials with dry binders, spray-dried lactose and microcrystalline cellulose, and glyceryl dibehenate at various concentrations. Compressibility was evaluated by means of the energy profile of compression and tensile strength of tablets. Release rate of the active ingredient, salicylic acid, from the tablets was also examined. In the case of microcrystalline cellulose, a higher concentration of glyceryl dibehenate increased the strength of tablets, while this did not occur in the case of spray-dried lactose. Increasing concentration of glyceryl dibehenate prolonged the release of salicylic acid; however, no statistically significant difference was found compared to the type of the dry binder used

  20. Measurement of rock properties at elevated pressures and temperatures

    International Nuclear Information System (INIS)

    Pincus, H.J.; Hoskins, E.R.

    1985-01-01

    The papers in this volume were presented at an ASTM symposium held on 20 June 1983 in conjunction with the 24th Annual Rock Mechanics Symposium at Texas A and M University, College Station, TX. The purpose of these papers is to present recent developments in the measurement of rock properties at elevated pressures and temperatures, and to examine and interpret the data produced by such measurement. The need for measuring rock properties at elevated pressures and temperatures has become increasingly important in recent years. Location and design of nuclear waste repositories, development of geothermal energy sites, and design and construction of deep excavations for civil, military, and mining engineering require significantly improved capabilities for measuring rock properties under conditions substantially different from those prevailing in most laboratory and in situ work. The development of high-pressure, high-temperature capabilities is also significant for the analysis of tectonic processes

  1. Effect of Glass Reinforced Epoxy (GRE) pipe filled with Geopolymer Materials for Piping Application: Compression Properties

    OpenAIRE

    Abu Hashim Mohammad Firdaus; Abdullah Mohd Mustafa Al Bakri; Ghazali Che Mohd Ruzaidi; Hussin Kamarudin; Binhussain Mohammed; Omar Mohd Firdaus

    2016-01-01

    The aim of this paper is to achieve the highest compressive strength of glass reinforced epoxy pipe with the geopolymer filler content of weight percentage that were used in glass reinforced epoxy pipe. The samples were prepared by using the filament winding method. The effect of weight percentage of geopolymer materials in epoxy hardener was studied under mechanical testing, which is using the compression test. A series of glass reinforced epoxy pipe and glass reinforced epoxy pipe filled wi...

  2. Elevated temperature tensile properties of borated 304 stainless steel

    International Nuclear Information System (INIS)

    Stephens, J.J.; Sorenson, K.B.; McConnell, P.

    1993-01-01

    This paper presents a comparison of the tensile properties of Powder Metallurgy (PM) 'Grade A' material with that of the conventional IM 'Grade B' material for two selected Types (i.e., boron contents) as defined by the ASTM A887 specification: Types 304B5 and 304B7. Tensile properties have been generated for these materials at temperatures ranging from room temperature to 400degC (752degF). The data at higher temperatures are required for ASME Code Case purposes, since the use temperature of a basket under 'worst case' cask conditions may be as high as 343degC (650degF), due to self-heating by the activated fuel elements. We will also discuss the current status of efforts aimed at obtaining an ASME Boiler and Pressure Vessel Code Case for selected grades of borated stainless steel covered by the ASTM A887 specification. (J.P.N.)

  3. The effect of sludge water treatment plant residuals on the properties of compressed brick

    Science.gov (United States)

    Shamsudin, Shamrul-Mar; Shahidan, S.; Azmi, M. A. M.; Ghaffar, S. A.; Ghani, M. B. Abdul; Saiful Bahari, N. A. A.; Zuki, S. S. M.

    2017-11-01

    The focus of this study is on the production of compressed bricks which contains sludge water treatment plant (SWTP) residuals obtained from SAJ. The main objective of this study is to utilise and incorporate discarded material (SWTP) in the form of residual solution to produce compressed bricks. This serves as one of the recycling efforts to conserve the environment. This study determined the optimum mix based on a mix ratio of 1:2:4 (cement: sand: soil) in the production of compressed bricks where 5 different mixes were investigated i. e. 0%, 5%, 10%, 20%, and 30% of water treatment plant residue solution. The production of the compressed bricks is in accordance with the Malaysian Standard MS 7.6: 1972 and British Standard BS 3921: 1985 - Compressive Strength & Water Absorption. After being moulded and air dried, the cured bricks were subjected to compression tests and water absorption tests. Based on the tests conducted, it was found that 20% of water treatment plant residue solution which is equivalent to 50% of soil content replacement with a mix composition of [10: cement] [20: sand] [20: soil] [20: water treatment plant residue solution] is the optimum mix. It was also observed that the bricks containing SWTP residuals were lighter in weight compared to the control specimens

  4. Effects of graded mechanical compression of rabbit sciatic nerve on nerve blood flow and electrophysiological properties.

    Science.gov (United States)

    Yayama, Takafumi; Kobayashi, Shigeru; Nakanishi, Yoshitaka; Uchida, Kenzo; Kokubo, Yasuo; Miyazaki, Tsuyoshi; Takeno, Kenichi; Awara, Kosuke; Mwaka, Erisa S; Iwamoto, Yukihide; Baba, Hisatoshi

    2010-04-01

    Entrapment neuropathy is a frequent clinical problem that can be caused by, among other factors, mechanical compression; however, exactly how a compressive force affects the peripheral nerves remains poorly understood. In this study, using a rabbit model of sciatic nerve injury (n=12), we evaluated the time-course of changes in intraneural blood flow, compound nerve action potentials, and functioning of the blood-nerve barrier during graded mechanical compression. Nerve injury was applied using a compressor equipped with a custom-made pressure transducer. Cessation of intraneural blood flow was noted at a mean compressive force of 0.457+/-0.022 N (+/-SEM), and the compound action potential became zero at 0.486+/-0.031 N. Marked extravasation of Evans blue albumin was noted after 20 min of intraneural ischemia. The functional changes induced by compression are likely due to intraneural edema, which could subsequently result in impairment of nerve function. These changes may be critical factors in the development of symptoms associated with nerve compression. (c) 2009 Elsevier Ltd. All rights reserved.

  5. Microstructure and compressive mechanical properties of cortical bone in children with osteogenesis imperfecta treated with bisphosphonates compared with healthy children.

    Science.gov (United States)

    Imbert, Laurianne; Aurégan, Jean-Charles; Pernelle, Kélig; Hoc, Thierry

    2015-06-01

    Osteogenesis imperfecta (OI) is a genetic disorder characterized by a change in bone tissue quality, but little data are available to describe the factors involved at the macroscopic scale. To better understand the effect of microstructure alterations on the mechanical properties at the sample scale, we studied the structural and mechanical properties of six cortical bone samples from children with OI treated with bisphosphonates and compared them to the properties of three controls. Scanning electron microscopy, high resolution computed tomography and compression testing were used to assess these properties. More resorption cavities and a higher osteocyte lacunar density were observed in OI bone compared with controls. Moreover, a higher porosity was measured for OI bones along with lower macroscopic Young's modulus, yield stress and ultimate stress. The microstructure was impaired in OI bones; the higher porosity and osteocyte lacunar density negatively impacted the mechanical properties and made the bone more prone to fracture. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Microstructure characteristics and compressive properties of NiAl-based multiphase alloy during heat treatments

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, L.Y., E-mail: lysheng@yeah.net [Peking University, Beijing 100871 (China); PKU-HKUST ShenZhen-Hong Kong Institution, Shenzhen 518057 (China); Xie, Y. [Hunan Electric Power Test and Research Institute, Changsha 410007 (China); Xi, T.F. [Peking University, Beijing 100871 (China); Guo, J.T. [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Zheng, Y.F. [Peking University, Beijing 100871 (China); Ye, H.Q. [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2011-11-15

    Highlights: {yields} The {alpha}-Cr, {sigma} and {mu} phases precipitate and form into network in as cast alloy. {yields} Rapid and intermediate cooling rate after solution treatment break the precipitates network; the lower cooling rate results in some {alpha}-Cr and Ni{sub 3}Al precipitates. {yields} Short-term aging results in massive Ni{sub 3}Al lathes and {alpha}-Cr particles, but long-term aging treatment coarsens the globule-shaped {alpha}-Cr particle and decreases the lath-shaped Ni{sub 3}Al, {mu} and {sigma} phase. {yields} The solid solution with short-term aging treatment improves mechanical properties of the alloy significantly. - Abstract: The alloy of Ni-Al26-Cr15-Co6-Ti3-Mo2-Nb0.5-Ho0.1 (at.%) was heat-treated and studied by microstructure examination and compressive test. The results reveal that in the as-cast alloy, {alpha}-Cr, {sigma} and {mu} phases are segregated along the NiAl phase boundary and form into network. Small Ni{sub 2}AlTi, Cr{sub 2}Nb and Ni{sub 2}Al{sub 3}Ho particles precipitate at NiAl grain boundary. The subsequent solid solution treatment with rapid and intermediate cooling rate transforms the net-like precipitating phases into discontinuous ones, but the rapid cooling leads to micro-cracks along phase boundary. However the lower cooling rate results in spherical {alpha}-Cr particle and needle-like Ni{sub 3}Al phase in NiAl matrix. The short-term aging after solid solution treatment promotes the coarsening of Ni{sub 3}Al lathes and {alpha}-Cr particles, and an orientation relationship of [001-bar]{sub {beta}}||[1-bar 10]{sub {lambda}{sup '}} and (1 1 0){sub {beta}}||(1 1 1){sub {gamma}'} is found between lath-shaped Ni{sub 3}Al phase and NiAl matrix. In addition, the {mu} phases are substituted by {sigma} and some Cr{sub 3}Ni{sub 2} phases. The long-term aging treatment reduces Ni{sub 3}Al, {sigma} and {mu} phases and coarsens the {alpha}-Cr phase further. The solid solution treatment and short-term aging improve the

  7. Temperature dependence of the magnetic properties of ferromagnetic amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gaunt, P.

    1979-01-01

    The magnetic hysteresis properties of amorphous alloys have recently been discussed in terms of an exchange-enhanced applied field. This absolute-zero model is here extended to finite temperatures. The modified treatment predicts a remanent magnetization which is unaffected by thermal activation while the coercive force falls (finally to zero) as temperature increases. Comparison with experiment for TbFe/sub 2/ suggests that regions of volume approx. =7500 A/sup 3/ reverse coherently.

  8. Elastic precursor wave decay in shock-compressed aluminum over a wide range of temperature

    Science.gov (United States)

    Austin, Ryan A.

    2018-01-01

    The effect of temperature on the dynamic flow behavior of aluminum is considered in the context of precursor wave decay measurements and simulations. In this regard, a dislocation-based model of high-rate metal plasticity is brought into agreement with previous measurements of evolving wave profiles at 300 to 933 K, wherein the amplification of the precursor structure with temperature arises naturally from the dislocation mechanics treatment. The model suggests that the kinetics of inelastic flow and stress relaxation are governed primarily by phonon scattering and radiative damping (sound wave emission from dislocation cores), both of which intensify with temperature. The manifestation of these drag effects is linked to low dislocation density ahead of the precursor wave and the high mobility of dislocations in the face-centered cubic lattice. Simulations performed using other typical models of shock wave plasticity do not reproduce the observed temperature-dependence of elastic/plastic wave structure.

  9. Properties, sustainability and elevated temperature behavior of concrete containing Portland limestone cement

    Science.gov (United States)

    El-Hawary, Moetaz; Ahmed, Mahmoud

    2017-09-01

    The utilization of some type of cheap filler as partial cement replacement is an effective way of improving concrete sustainability. With the recent trends to reduce water to cement ratio and improve compaction, there is no enough space or water for complete hydration of cement. This means that actually, a portion of mixed cement acts as expensive filler. Replacing this portion with cheaper filler that requires less energy to produce is, therefore, beneficial. Crushed limestone is the most promising filler. This work is to investigate the effect of the amount of limestone fillers on the sustainability and the fresh and mechanical properties of the resulting concrete. A rich mix is designed with a low water/cement ratio of 0.4. Lime is introduced as a replacement percentage of cement. Ratios of 0, 10, 20 and 30% were used. Slump, compressive strength, specific gravity and water absorption are evaluated for every mix. In addition, the effect of the amount of lime on the residual strength of concrete subjected to elevated temperatures is also investigated. Samples are subjected to six different temperature stations of 20, 100, 200, 300, 500 and 700°C for six hours before being cooled and subsequently tested for compressive strength and specific gravity. Sustainability of the tested mixes is evaluated through reductions in the emitted carbon dioxide, energy and reduction in cost. Based on the annual use of concrete in Kuwait, the sustainability benefits resulting from the use of limestone filler in Kuwait are evaluated and assessed. The paper is concluded with the recommendation of the use of 15% limestone filler as partial cement replacement where the properties and the behavior under high temperature of the resulting concrete are almost the same as those of conventional concrete with considerable cost and sustainability benefits.

  10. Temperature dependence of poly(lactic acid) mechanical properties

    DEFF Research Database (Denmark)

    Zhou, Chengbo; Guo, Huilong; Li, Jingqing

    2016-01-01

    The mechanical properties of polymers are not only determined by their structures, but also related to the temperature field in which they are located. The yield behaviors, Young's modulus and structures of injection-molded poly(lactic acid) (PLA) samples after annealing at different temperatures....... For the samples annealed between 80 and 120 oC, a peculiar double yield appears when stretched within 50–60 oC and only the first or the second yield can be found at the lower and higher draw temperatures. The yield strain and yield stress together with Young's modulus were obtained and discussed in terms...

  11. High Temperature Thermal Properties of Bentonite Foundry Sand

    Directory of Open Access Journals (Sweden)

    Krajewski P.K.

    2015-06-01

    Full Text Available The paper presents results of measuring thermal conductivity and heat capacity of bentonite foundry sand in temperature range ambient - 900­­°C. During the experiments a technical purity Cu plate was cast into the green-sand moulds. Basing on measurements of the mould temperature field during the solidification of the casting, the temperature relationships of the measured properties were evaluated. It was confirmed that water vaporization strongly influences thermal conductivity of the moulding sand in the first period of the mould heating by the poured casting.

  12. [Determination of normal temperature properties of refractory die material compatible with slip casting core of sintered titanium powder].

    Science.gov (United States)

    Kuang, X; Liao, Y; Chao, Y; Wang, H

    1999-05-01

    The refractory die is the precondition for developing slip casting core of sintered powder. This study is to determine the normal temperature properties of the refractory die material compatible with slip casting core. to mix the die material at five different ratios (8/1, 7.5/1, 7/1, 6.5/1, and 6/1) and measure their solidification time with self-manufactured Vicker's needle; to prepare five cylindrical specimens (phi 10 x 15 mm) in different drying time for determining their compressive strength, and then to let another five specimens fire at 1000 degrees C four times for measuring the residual compressive strength at room temperature. The setting time was 16.25 minutes (7.5/1), and the lower the powder-liquid ratio, the longer the setting time. The normal compressive strength was 25.32 MPa (drying 24 hours), while the longer the drying time, the higher the compressive strength achieved (P die material meet the demand of slip casting core of sintered powder.

  13. Effect of High-Temperature Curing Methods on the Compressive Strength Development of Concrete Containing High Volumes of Ground Granulated Blast-Furnace Slag

    Directory of Open Access Journals (Sweden)

    Wonsuk Jung

    2017-01-01

    Full Text Available This paper investigates the effect of the high-temperature curing methods on the compressive strength of concrete containing high volumes of ground granulated blast-furnace slag (GGBS. GGBS was used to replace Portland cement at a replacement ratio of 60% by binder mass. The high-temperature curing parameters used in this study were the delay period, temperature rise, peak temperature (PT, peak period, and temperature down. Test results demonstrate that the compressive strength of the samples with PTs of 65°C and 75°C was about 88% higher than that of the samples with a PT of 55°C after 1 day. According to this investigation, there might be optimum high-temperature curing conditions for preparing a concrete containing high volumes of GGBS, and incorporating GGBS into precast concrete mixes can be a very effective tool in increasing the applicability of this by-product.

  14. On the Influence of the Heat Treatment Temperature on the Superelastic Compressive Behavior of the Ni-Rich NiTi Shape Memory Alloy

    Science.gov (United States)

    Ben Fraj, B.; Gahbiche, A.; Zghal, S.; Tourki, Z.

    2017-11-01

    In this paper, the relationship between the heat treatment temperature and the thermomechanical behavior of the Ni-rich NiTi shape memory alloy was experimentally investigated. Thermal analysis was performed through a differential scanning calorimetry experiments, and the NiTi superelastic effect was exhibited through loading/unloading compression cycle. It was found that the transformation temperatures and the compressive mechanical response are strongly affected by the heat treatment temperatures. The stress-induced phase transformation was characterized through the relationship between the heat treatment temperature and transformation stresses, elastic moduli and the deformation level upon loading. Subsequently, the evolution of the mechanical hysteresis loops and the mechanical dissipated energy was discussed. The obtained findings are supported by hardness measurements. To better understand the global tendency of the various phase transformation stages, the critical stress-temperature diagram was provided for different proposed heat treatment temperatures.

  15. Modeling two-stage bunch compression with wakefields: Macroscopic properties and microbunching instability

    Directory of Open Access Journals (Sweden)

    R. A. Bosch

    2008-09-01

    Full Text Available In a two-stage compression and acceleration system, where each stage compresses a chirped bunch in a magnetic chicane, wakefields affect high-current bunches. The longitudinal wakes affect the macroscopic energy and current profiles of the compressed bunch and cause microbunching at short wavelengths. For macroscopic wavelengths, impedance formulas and tracking simulations show that the wakefields can be dominated by the resistive impedance of coherent edge radiation. For this case, we calculate the minimum initial bunch length that can be compressed without producing an upright tail in phase space and associated current spike. Formulas are also obtained for the jitter in the bunch arrival time downstream of the compressors that results from the bunch-to-bunch variation of current, energy, and chirp. Microbunching may occur at short wavelengths where the longitudinal space-charge wakes dominate or at longer wavelengths dominated by edge radiation. We model this range of wavelengths with frequency-dependent impedance before and after each stage of compression. The growth of current and energy modulations is described by analytic gain formulas that agree with simulations.

  16. Prediction study on mechanical and thermodynamic properties of orthorhombic Mg2SiO4 under high temperature

    International Nuclear Information System (INIS)

    Zhou, Jianting; Zhang, Hong; Chen, Yue; Shong, Jun; Chen, Zhuo; Yang, Juan; Zheng, Zhou; Wang, Feng

    2014-01-01

    In this work, based on density functional theory and quasi-harmonic Debye model, mechanical and thermodynamic properties of orthorhombic Mg 2 SiO 4 under high temperature are predicted. We found out that α-Mg 2 SiO 4 is mechanically stable under the condition from about 0 to 74 GPa. Results indicate that the main cause of mechanical instability is high pressure, and the effect caused by high temperature is small. C 11 , C 22 , C 33 , B and v p reduce with temperature just a little and increase with pressure obviously. Mg 2 SiO 4 has excellent resistance to strong compression; however the resistance to shear is unsatisfactory. The C v tends to the Petit and Dulong limit at high temperature under any pressure, and it is proportional to T 3 at extremely low temperature. Pressure has an opposite effect on C v than temperature. The suppressed effect on C v caused by pressure is not obvious under low and very high temperature. Mg 2 SiO 4 has three different thermal expansion coefficients (α) along a-, b- and c-axes, and α a <α c <α b . α increases rapidly at low temperature (about <300 K), and slows down at high temperature. High pressure would greatly suppress expansion caused by temperature. Nevertheless, increasing tendency of α b and α c is still obvious under high pressure, especially α b . All the properties are mainly due to Si–O covalent bonds and their directions

  17. Temperature dependence of the dielectric properties of rubber wood

    Science.gov (United States)

    Mohammed Firoz Kabir; Wan M. Daud; Kaida B. Khalid; Haji A.A. Sidek

    2001-01-01

    The effect of temperature on the dielectric properties of rubber wood was investigated in three anisotropic directions—longitudinal, radial, and tangential, and at different measurement frequencies. Low frequency measurements were conducted with a dielectric spectrometer, and high frequencies used microwave applied with open-ended coaxial probe sensors. Dielectric...

  18. Influence of substrate temperature on certain physical properties ...

    Indian Academy of Sciences (India)

    The deposited films were subjected to various characterization studies, to explore certain features like the influence of various deposition temperatures on physical and antibacterial properties. XRD results showed that all the samples exhibited preferential orientation along the (2 2 2) plane. The variation in the crystalline ...

  19. Depolarization temperature and piezoelectric properties of Na1/2 ...

    Indian Academy of Sciences (India)

    1/2Bi1/2(Zn1/3Nb2/3)O3, was synthesized using the two-stage calcination method and depolarization temperatures and piezoelectric properties were also investigated. The XRD analysis showed that the ceramics system had a morphotropic ...

  20. Effects of reaction temperature on size and optical properties of ...

    Indian Academy of Sciences (India)

    Administrator

    Effects of reaction temperature on size and optical properties of. CdSe nanocrystals. SHUTANG CHEN, XIAOLING ZHANG*, YANBING ZHAO and QIUHUA ZHANG. Department of Chemistry, School of Science, Beijing Institute of Technology, Beijing 100081, P.R. China. MS received 15 March 2009; revised 6 July 2009.

  1. Depolarization temperature and piezoelectric properties of TiO3 ...

    Indian Academy of Sciences (India)

    WINTEC

    Lead-free piezoelectric ceramics; depolarization temperature; perovskite structure; piezoelectric properties. 1. Introduction. Increasing interest concerning the environmental pro- blems of Pb(Zr, Ti)O3(PZT)-based ceramics has led to the demand of lead-free ferroelectric ceramics in electronic applications (Shieh et al 2007).

  2. Structural properties of gold clusters at different temperatures

    CSIR Research Space (South Africa)

    Mahladisa, MA

    2005-09-01

    Full Text Available A series of gold clusters consisting of aggregates of from 13 to 147 atoms was studied using the Sutton-Chen type many-body potential in molecular dynamics simulations. The properties of these clusters at temperatures from 10 K to 1000 K were...

  3. High temperature magnetic properties of nanocrystalline Sn0 ...

    Indian Academy of Sciences (India)

    Administrator

    High temperature magnetic properties of nanocrystalline Sn0⋅95Co0⋅05O2. O MOUNKACHI1, E SALMANI2, ... exchange interaction between the magnetic ions and the band electrons. Tin dioxide (SnO2) is an n-type ... rate must be well controlled for the chemical homogene- ity. The reactants were constantly stirred using ...

  4. Influence of substrate temperature on certain physical properties ...

    Indian Academy of Sciences (India)

    2016-11-12

    Nov 12, 2016 ... influence of various deposition temperatures on physical and antibacterial properties. ... terial agents include metal oxide semiconductors as they are ... This method is found to be simple, cost-effective and can be used to prepare dense films on large areas with better quality. 2. Experimental details for the ...

  5. Low-temperature localization in the transport properties of self ...

    Indian Academy of Sciences (India)

    Transport properties; scattering mechanisms; low temperature localization. 1. Introduction. The investigation on mixed-valent manganites with per- ovskite structure is on run for the last two decades. Specially, the studies on the hole doped manganites, La1−δAδMnO3. (A = divalent atom) still demands special attention ...

  6. Effects of Temperature on the Physicochemical Properties of ...

    African Journals Online (AJOL)

    The quality and stability of traditionally processed palm, sunflower and sesame oils and their blends as affected by temperature were evaluated by analyzing their physicochemical properties which included acid, saponification, peroxide, iodine values and refractive indices.. The initial quality of traditionally processed oils ...

  7. Mechanical and electrical properties of resistance welds at cryogenic temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S T; Kim, S H; Kim, N S; Ludwig, H

    1979-01-01

    The mechanical and electrical properties of resistance welds at cryogenic temperatures for the large superconducting magnet such as the superconducting MHD Dipole system for the National Coal-Fired Flow Facility (CFFF SCMS) at the U. of Tennessee Space Institute are reported.

  8. The role of strain rate during deposition of CAP on Ti6Al4V by superplastic deformation-like method using high-temperature compression test machine

    Energy Technology Data Exchange (ETDEWEB)

    Ramdan, R.D. [Center for Nano-Technology Precision and Advanced Materials, Department of Mechanical Engineering, University of Malaya, Kuala Lumpur (Malaysia)], E-mail: rddadan_ramdan@yahoo.co.uk; Jauhari, I.; Hasan, R.; Masdek, N.R. Nik [Center for Nano-Technology Precision and Advanced Materials, Department of Mechanical Engineering, University of Malaya, Kuala Lumpur (Malaysia)

    2008-03-25

    This paper describes an implementation of superplastic deformation method for the deposition of carbonated-apatite (CAP) on the well-know titanium alloy, Ti6Al4V. This deposition process was carried out using high-temperature compression test machine, at temperature of 775 deg. C, different strain rates, and conducted along the elastic region of the sample. Before the process, titanium substrate was cryogenically treated in order to approach superplastic characteristic during the process. After the process, thin film of CAP was created on the substrate with the thickness from 0.71 {mu}m to 1.42 {mu}m. The resulted film has a high density of CAP that covered completely the surface of the substrate. From the stress-strain relation chart, it can be observed that as the strain rate decreases, the area under stress-strain chart also decreases. This condition influences the density of CAP layer on the substrate that as this area decreases, the density of CAP layer also decreases as also confirmed by X-ray diffraction characterization. In addition, since the resulting layer of CAP is in the form of thin film, this layer did not alter the hardness of the substrate as measured by Vickers hardness test method. On the other hand, the resulting films also show a good bonding strength properties as the layer remain exist after friction test against polishing clothes for 1 h.

  9. Effects of strain rate and elevated temperature on compressive flow stress and absorbed energy of polyimide foam

    Directory of Open Access Journals (Sweden)

    Horikawa K.

    2012-08-01

    Full Text Available In this study, at first, the effect of strain rate on the strength and the absorbed energy of polyimide foam was experimentally examined by carrying out a series of compression tests at various strain rates, from 10−3 to 103 s−1. This polyimide foam has open cell structure with small cell size of 0.3 ∼ 0.6 mm. In the measurement of impact load, a special load cell with a small part for sensing load was adopted. For the measurement of the displacement, a high-speed camera was used. It was found that the flow stress of polyimide foam and the absorbed energy up to a strain of 0.4 increased with the increase of the strain rates. Secondly, the effect of ambient temperature on the strength and absorbed energy of polyimide foam was also investigated by using a sprit Hopkinson pressure bar apparatus and testing at elevated temperatures of 100 and 200 ∘C. With the increase of temperature, the strength and absorbed energy decreased and the effect is smaller in dynamic tests than static tests.

  10. Thermal properties of solids at room and cryogenic temperatures

    CERN Document Server

    Ventura, Guglielmo

    2014-01-01

    This book is a guide for materials scientists, physicists, chemists and engineers who wish to explore the field of low-temperature material properties. The focus is on heat capacity, thermal expansion and electrical and thermal conductivity. The authors report a wide range of experimental details and data, and have compiled useful tables of low-temperature data. Each chapter of the book starts by addressing the theoretical basis of the phenomena. This is a concise presentation, but it helps the reader to develop a deeper understanding of the experiments. The second part of the chapters is dedicated to describing the main experimental techniques to measure thermal properties at low and very low temperature ranges. The final part of each chapter provides a wealth of relevant experimental data in the form of tables and graphs.

  11. Thermodynamic properties of standard seawater: extensions to high temperatures and pressures

    Directory of Open Access Journals (Sweden)

    J. Safarov

    2009-07-01

    Full Text Available Measurements of (p, ρ, T properties of standard seawater with practical salinity S≈35, temperature T=(273.14 to 468.06 K and pressures, p, up to 140 MPa are reported with the reproducibility of the density measurements observed to be in the average percent deviation range Δρ/ρ=±(0.01 to 0.03%. The measurements are made with a newly constructed vibration-tube densimeter which is calibrated using double-distilled water, methanol and aqueous NaCl solutions. Based on these and previous measurements, an empirical expression for the density of standard seawater has been developed as a function of pressure and temperature. This equation is used to calculate other volumetric properties including isothermal compressibility, isobaric thermal expansibility, differences in isobaric and isochoric heat capacities, the thermal pressure coefficient, internal pressure and the secant bulk modulus. The results can be used to extend the present equation of state of seawater to higher temperatures for pressure up to 140 MPa.

  12. Data on Material Properties and Panel Compressive Strength of a Plastic-bonded Material of Glass Cloth and Canvas

    Science.gov (United States)

    Zender, George W; Schuette, Evan H; Weinberger, Robert A

    1944-01-01

    Results are presented of tests for determining the tensile, compressive, and bending properties of a material of plastic-bonding glass cloth and canvas layers. In addition, 10 panel specimens were tested in compression. Although the material is not satisfactory for primary structural use in aircraft when compared on a strength-weight basis with other materials in common use, there appears to be potential strength in the material that will require research for development. These points are considered in some detail in the concluding discussion of the report. An appendix shows that a higher tensile strength can be obtained by changes in the type of weave used in the glass-cloth reinforcement.

  13. KNO3/NaNO3 - Graphite materials for thermal energy storage at high temperature: Part I. - Elaboration methods and thermal properties

    International Nuclear Information System (INIS)

    Acem, Zoubir; Lopez, Jerome; Palomo Del Barrio, Elena

    2010-01-01

    Composites graphite/salt for thermal energy storage at high temperature (∼200 deg. C) have been developed and tested. As at low temperature in the past, graphite has been used to enhance the thermal conductivity of the eutectic system KNO 3 /NaNO 3 . A new elaboration method has been proposed as an alternative to graphite foams infiltration. It consists of cold-compression of a physical mixing of expanded natural graphite particles and salt powder. Two different compression routes have been investigated: uni-axial compression and isostatic compression. The first part of the paper has been devoted to the analysis of the thermal properties of these new graphite/salt composites. It is proven that cold-compression is a simple and efficient technique for improving the salt thermal conductivity. For instance, graphite amounts between 15 and 20%wt lead to apparent thermal conductivities close to 20 W/m/K (20 times greater than the thermal conductivity of the salt). Furthermore, some advantages in terms of cost and safety are expected because materials elaboration is carried out at room temperature. The second part of the paper is focused on the analyses of the phase transition properties of these graphite/salt composites materials.

  14. Elevated temperature creep properties of the 54Fe-29Ni-17Co "Kovar" alloy.

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, John Joseph, Jr.; Rejent, Jerome Andrew; Schmale, David T.

    2009-01-22

    The outline of this presentation is: (1) Applications of Kovar Alloy in metal/ceramic brazing; (2) Diffusion bonding of precision-photoetched Kovar parts; (3) Sample composition and annealing conditions; (4) Intermediate temperature creep properties (350-650 C); (5) Power law creep correlations--with and without modulus correction; (6) Compressive stress-strain properties (23-900 C); (7) Effect of creep deformation on grain growth; and (8) Application of the power law creep correlation to the diffusion bonding application. The summary and conclusions are: Elevated temperature creep properties of Kovar from 750-900 C obey a power law creep equation with a stress exponent equal to 4.9, modulus compensated activation energy of 47.96 kcal/mole. Grain growth in Kovar creep samples tested at 750 and 800 C is quite sluggish. Significant grain growth occurs at 850 C and above, this is consistent with isothermal grain growth studies performed on Kovar alloy wires. Finite element analysis of the diffusion bonding of Kovar predict that stresses of 30 MPa and higher are needed for good bonding at 850 C, we believe that 'sintering' effects must be accounted for to allow FEA to be predictive of actual processing conditions. Additional creep tests are planned at 250-650 C.

  15. Axial Compression Properties Nonlinear Analysis on Square Double Skin Steel Stub Short Columns Filled with Recycled Concrete

    Directory of Open Access Journals (Sweden)

    Song Bing

    2016-01-01

    Full Text Available Taking the mixing amount of diatomite calcined and vitrified micro bubbles(VMB as the main changing parameters, experiment studies the properties of the vitrified micro bubbles recycled concrete blocks; then this paper adopts the finite element software ANSYS to analyze the square double skin steel stub short columns filled with recycled concrete under axial compression. According to the vertical stress distribution, strain and bearing capacity of the steel tube and core concrete, we make a contrastive axial compression properties analysis on the different hollow ratio χ(0,0.35and the VMB content(0%,100%,130% of square double skin steel stub short columns filled with recycled concrete. The result shows that: Compressive strength of VMB recycled concrete increases with the increase of diatomite calcined content, when mixing amount of diatomite calcined is 3%,the compressive strength of 130% VMB content test specimen can reach 32.45 MPa;Because of the inner circular steel tube is setted which strengthening component buckling capacity and improving the ductility of the component, stress distribution of hollow components is more balance than solid components, and their axial displacements decrease by 5.6% compared with the solid components when they reach ultimate bearing capacity; When the hollow ratio is same, ultimate bearing capacity of 130% VMB content test specimen compared with the content is 0% only reduces by about 3.5%; When the VMB content is same, ultimate bearing capacity of hollow components compared with solid components increases by about 2.5%, which reducing weight as well as improving the anti-seismic performance.

  16. The effects of embalming using a 4% formalin solution on the compressive mechanical properties of human cortical bone.

    Science.gov (United States)

    Ohman, Caroline; Dall'Ara, Enrico; Baleani, Massimiliano; Van Sint Jan, Serge; Viceconti, Marco

    2008-12-01

    The use of formalin fixed bone tissue is often avoided because of its assumed influence on the mechanical properties of bone. Fixed bone tissue would minimise biological risks and eliminate preservation issues for long duration experimental tests. This study aimed to determine the short- and long-term effects of embalming, using a solution with 4% formalin concentration, on the mechanical properties of human cortical bone. Three-millimetre cylindrical specimens of human cortical bone were extracted from two femoral diaphyses and divided in four groups. The first group was used as control, the remaining three groups were left in the embalming solution for 48 h, 4 week, and 8 week, respectively. Compressive mechanical properties, hardness and ash density were assessed. The last was used to check the homogeneity among the four groups. No significant differences were found among the four groups in yield stress, ultimate stress and hardness. The specimens stored for 8 week in the embalming solution had significant lower Young's modulus (-24%), higher yield strain (+20%) and ultimate strain (+53%) compared to the other groups. On a short-term perspective, embalming did not affect the compressive mechanical properties, nor hardness of human cortical bone, whereas a long-term preservation (8 week) did significantly affect Young's modulus, yield strain and ultimate strain in compression. Preserving bone segments for up to 4 week in an embalming solution with low formalin concentration seems to be an interesting alternative when collecting and/or managing fresh or fresh-frozen bone segments for biomechanical experiments is not possible.

  17. Comparison of electromechanical properties and lattice distortions of different cuprate high temperature superconductors

    CERN Document Server

    Scheuerlein, C.; Grether, A; Rikel, M O; Hudspeth, J; Sugano, M; Ballarino, A; Bottura, L

    2016-01-01

    The electromechanical properties of different cuprate high-temperature superconductors, notably two ReBCO tapes, a reinforced and a nonreinforced Bi-2223 tape, and a Bi-2212 wire, have been studied. The axial tensile stress and strain, as well as the transverse compressive stress limits at which an irreversible critical current degradation occurs, are compared. The experimental setup has been integrated in a high-energy synchrotron beamline, and the self-field critical current and lattice parameter changes as a function of tensile stress and strain of a reinforced Bi-2223 tape have been measured simultaneously. Initially, the Bi-2223 filaments exhibit nearly linear elastic behavior up to the strain at which an irreversible degradation is observed. At 77 K, an axial Bi-2223 filament precompression of 0.09% in the composite tape and a Bi-2223 Poisson ratio ν = 0.21 have been determined.

  18. EFFECT OF TEMPERATURE AND pH OF MODIFICATION PROCESS ON THE PHYSICAL-MECHANICAL PROPERTIES OF MODIFIED CASSAVA STARCH

    Directory of Open Access Journals (Sweden)

    Yudi Wicaksono

    2016-11-01

    Full Text Available The use of cassava starch for excipient in the manufacturing of the tablet has some problems, especially on physical-mechanical properties. The purpose of this study was to determine the effect of the differentness of temperature and pH in the process of modification on the physical-mechanical properties of modified cassava starch. Modifications were performed by suspending cassava starch into a solution of 3 % (w/v PVP K30. The effect of the difference of temperature was observed at temperatures of 25; 45 and 65 0C, while the effect of the difference of pH was observed at pH of 4.0; 7.0 and 12.0. The results showed that the temperature and pH did not affect the physical-mechanical properties of the modified cassava starch. Modification of cassava starch at pH and temperature of 7.0 and 45 0C was produced modified cassava starch with the most excellent solubility, while the best swelling power were formed by the modification process at pH and temperature of 7.0 and 25 0C. Overall, the most excellent compression properties of modified cassava starch resulted from the modification process at pH 12.

  19. Properties of magnetocaloric materials with a distribution of Curie temperatures

    DEFF Research Database (Denmark)

    Bahl, Christian Robert Haffenden; Bjørk, Rasmus; Smith, Anders

    2012-01-01

    The magnetocaloric properties of inhomogeneous ferromagnets that contain distributions of Curie temperatures are considered as a function of the width of such a distribution. Assuming a normal distribution of the Curie temperature, the average adiabatic temperature change, ΔTad, the isothermal...... magnetic entropy change, Δs, and the heat capacity, cp, in zero magnetic field and an applied magnetic field of , have been calculated using the mean field model of ferromagnetism. Interestingly, both the peak position and amplitude of each of these parameters vary differently with the width...... of the distribution, explaining the observed mismatch of peak temperatures reported in experiments. Also, the field dependence of ΔTad and Δs is found to depend on the width of the distribution....

  20. Ignition properties of methane/hydrogen mixtures in a rapid compression machine

    NARCIS (Netherlands)

    Gersen, S.; Anikin, N. B.; Mokhov, A. V.; Levinsky, H. B.

    We investigate changes in the combustion behavior of methane, the primary component of natural gas, upon hydrogen addition by characterizing the autoignition behavior of methane/hydrogen mixtures in a rapid compression machine (RCM). Ignition delay times were measured under stoichiometric conditions

  1. Physical properties and consumer reaction to use of compressed wood bricks in southeast Alaska

    Science.gov (United States)

    Allen M. Brackley; Robert Gorman; Karen. Peterson

    2012-01-01

    In late 2008, a group of business people and entrepreneurs in southeast Alaska became aware of a compressed wood brick product that could be used as an alternative fuel in existing wood-burning stoves and heating equipment. The product differed from many others on the market in that it contained no additive to promote binding and burn characteristics. In 2009, local...

  2. The influence of maltodextrins on the structure and properties of compression-molded starch plastic sheets

    NARCIS (Netherlands)

    Soest, van J.J.G.; Kortleve, P.M.

    1999-01-01

    Starch plastic sheets were prepared by compression molding of starch-based plastic granulates. The granulates were prepared by extrusion processing of mixtures of granular potato starch and several maltodextrins (5% w/w) in the presence of glycerol and water as plasticizers and lecithin as melt flow

  3. Optical properties in the far infrared and at low temperatures of fifteen ionic crystals

    International Nuclear Information System (INIS)

    Claudel, Jacques

    1969-01-01

    In this research thesis, the author first briefly presents the problem of interactions between electromagnetic waves and thermal agitation waves in crystal. Then, he reports an analysis of reflection spectra in the far infrared and at low temperatures for fourteen ionic crystals in order to determine their optical properties. The author presents the methods used to calculate optical and dielectric constants. Results obtained for each compound are presented and discussed. In the next part, the author reports the study of transmission spectra of two ionic compounds (caesium iodide and copper oxide) at ambient temperature and at liquid helium temperature. He reports the determination of phonon addition and difference processes which occur during caesium iodide absorption, and the search for a second active infrared frequency for the copper oxide. The author briefly describes a high resolution spectrometer, and presents in a more detailed way the use of a new antimony-based sensor which allows studies to be performed at lower temperatures. Finally, various issues are discussed: Havelock relationship, determination of the optical longitudinal mode, and Szigeti equations of compressibility

  4. High-temperature transient creep properties of CANDU pressure tubes

    International Nuclear Information System (INIS)

    Fong, R.W.L.; Chow, C.K.

    2002-06-01

    During a hypothetical large break loss-of-coolant accident (LOCA), the coolant flow would be reduced in some fuel channels and would stagnate and cause the fuel temperature to rise and overheat the pressure tube. The overheated pressure tube could balloon (creep radially) into contact with its moderator-cooled calandria tube. Upon contact, the stored thermal energy in the pressure tube is transferred to the calandria tube and into the moderator, which acts as a heat sink. For safety analyses, the modelling of fuel channel deformation behaviour during a large LOCA requires a sound knowledge of the high-temperature creep properties of Zr-2.5Nb pressure tubes. To this extent, a ballooning model to predict pressure-tube deformation was developed by Shewfelt et al., based on creep equations derived using uniaxial tensile specimens. It has been recognized, however, that there is an inherent variability in the high-temperature creep properties of CANDU pressure tubes. The variability, can be due to different tube-manufacturing practices, variations in chemical compositions, and changes in microstructure induced by irradiation during service in the reactor. It is important to quantify the variability of high-temperature creep properties so that accurate predictions on pressure-tube creep behaviour can be made. This paper summarizes recent data obtained from high-temperature uniaxial creep tests performed on specimens taken from both unirradiated (offcut) and irradiated pressure tubes, suggesting that the variability is attributed mainly to the initial differences in microstructure (grain size, shape and preferred orientation) and also from tube-to-tube variations in chemical composition, rather than due to irradiation exposure. These data will provide safety analysts with the means to quantify the uncertainties in the prediction of pressure-tube contact temperatures during a postulated large break LOCA. (author)

  5. Properties of two-temperature dissipative accretion flow around black holes

    Science.gov (United States)

    Dihingia, Indu K.; Das, Santabrata; Mandal, Samir

    2018-04-01

    We study the properties of two-temperature accretion flow around a non-rotating black hole in presence of various dissipative processes where pseudo-Newtonian potential is adopted to mimic the effect of general relativity. The flow encounters energy loss by means of radiative processes acted on the electrons and at the same time, flow heats up as a consequence of viscous heating effective on ions. We assumed that the flow is exposed with the stochastic magnetic fields that leads to Synchrotron emission of electrons and these emissions are further strengthen by Compton scattering. We obtain the two-temperature global accretion solutions in terms of dissipation parameters, namely, viscosity (α) and accretion rate ({\\dot{m}}), and find for the first time in the literature that such solutions may contain standing shock waves. Solutions of this kind are multitransonic in nature, as they simultaneously pass through both inner critical point (xin) and outer critical point (xout) before crossing the black hole horizon. We calculate the properties of shock-induced global accretion solutions in terms of the flow parameters. We further show that two-temperature shocked accretion flow is not a discrete solution, instead such solution exists for wide range of flow parameters. We identify the effective domain of the parameter space for standing shock and observe that parameter space shrinks as the dissipation is increased. Since the post-shock region is hotter due to the effect of shock compression, it naturally emits hard X-rays, and therefore, the two-temperature shocked accretion solution has the potential to explain the spectral properties of the black hole sources.

  6. Electrical resistance of CNT-PEEK composites under compression at different temperatures

    Directory of Open Access Journals (Sweden)

    Mohiuddin Mohammad

    2011-01-01

    Full Text Available Abstract Electrically conductive polymers reinforced with carbon nanotubes (CNTs have generated a great deal of scientific and industrial interest in the last few years. Advanced thermoplastic composites made of three different weight percentages (8%, 9%, and 10% of multiwalled CNTs and polyether ether ketone (PEEK were prepared by shear mixing process. The temperature- and pressure-dependent electrical resistance of these CNT-PEEK composites have been studied and presented in this paper. It has been found that electrical resistance decreases significantly with the application of heat and pressure.

  7. Evaluation of varying ductile fracture criteria for 42CrMo steel by compressions at different temperatures and strain rates.

    Science.gov (United States)

    Quan, Guo-zheng; Luo, Gui-chang; Mao, An; Liang, Jian-ting; Wu, Dong-sen

    2014-01-01

    Fracturing by ductile damage occurs quite naturally in metal forming processes, and ductile fracture of strain-softening alloy, here 42CrMo steel, cannot be evaluated through simple procedures such as tension testing. Under these circumstances, it is very significant and economical to find a way to evaluate the ductile fracture criteria (DFC) and identify the relationships between damage evolution and deformation conditions. Under the guidance of the Cockcroft-Latham fracture criteria, an innovative approach involving hot compression tests, numerical simulations, and mathematic computations provides mutual support to evaluate ductile damage cumulating process and DFC diagram along with deformation conditions, which has not been expounded by Cockcroft and Latham. The results show that the maximum damage value appears in the region of upsetting drum, while the minimal value appears in the middle region. Furthermore, DFC of 42CrMo steel at temperature range of 1123~1348 K and strain rate of 0.01~10 s(-1) are not constant but change in a range of 0.160~0.226; thus, they have been defined as varying ductile fracture criteria (VDFC) and characterized by a function of temperature and strain rate. In bulk forming operations, VDFC help technicians to choose suitable process parameters and avoid the occurrence of fracture.

  8. Evaluation of Varying Ductile Fracture Criteria for 42CrMo Steel by Compressions at Different Temperatures and Strain Rates

    Directory of Open Access Journals (Sweden)

    Guo-zheng Quan

    2014-01-01

    Full Text Available Fracturing by ductile damage occurs quite naturally in metal forming processes, and ductile fracture of strain-softening alloy, here 42CrMo steel, cannot be evaluated through simple procedures such as tension testing. Under these circumstances, it is very significant and economical to find a way to evaluate the ductile fracture criteria (DFC and identify the relationships between damage evolution and deformation conditions. Under the guidance of the Cockcroft-Latham fracture criteria, an innovative approach involving hot compression tests, numerical simulations, and mathematic computations provides mutual support to evaluate ductile damage cumulating process and DFC diagram along with deformation conditions, which has not been expounded by Cockcroft and Latham. The results show that the maximum damage value appears in the region of upsetting drum, while the minimal value appears in the middle region. Furthermore, DFC of 42CrMo steel at temperature range of 1123~1348 K and strain rate of 0.01~10 s-1 are not constant but change in a range of 0.160~0.226; thus, they have been defined as varying ductile fracture criteria (VDFC and characterized by a function of temperature and strain rate. In bulk forming operations, VDFC help technicians to choose suitable process parameters and avoid the occurrence of fracture.

  9. Evaluation of Varying Ductile Fracture Criteria for 42CrMo Steel by Compressions at Different Temperatures and Strain Rates

    Science.gov (United States)

    Quan, Guo-zheng; Luo, Gui-chang; Mao, An; Liang, Jian-ting; Wu, Dong-sen

    2014-01-01

    Fracturing by ductile damage occurs quite naturally in metal forming processes, and ductile fracture of strain-softening alloy, here 42CrMo steel, cannot be evaluated through simple procedures such as tension testing. Under these circumstances, it is very significant and economical to find a way to evaluate the ductile fracture criteria (DFC) and identify the relationships between damage evolution and deformation conditions. Under the guidance of the Cockcroft-Latham fracture criteria, an innovative approach involving hot compression tests, numerical simulations, and mathematic computations provides mutual support to evaluate ductile damage cumulating process and DFC diagram along with deformation conditions, which has not been expounded by Cockcroft and Latham. The results show that the maximum damage value appears in the region of upsetting drum, while the minimal value appears in the middle region. Furthermore, DFC of 42CrMo steel at temperature range of 1123~1348 K and strain rate of 0.01~10 s−1 are not constant but change in a range of 0.160~0.226; thus, they have been defined as varying ductile fracture criteria (VDFC) and characterized by a function of temperature and strain rate. In bulk forming operations, VDFC help technicians to choose suitable process parameters and avoid the occurrence of fracture. PMID:24592175

  10. MRI-based experimentations of fingertip flat compression: Geometrical measurements and finite element inverse simulations to investigate material property parameters.

    Science.gov (United States)

    Dallard, Jérémy; Merlhiot, Xavier; Petitjean, Noémie; Duprey, Sonia

    2018-01-23

    Modeling human-object interactions is a necessary step in the ergonomic assessment of products. Fingertip finite element models can help investigating these interactions, if they are built based on realistic geometrical data and material properties. The aim of this study was to investigate the fingertip geometry and its mechanical response under compression, and to identify the parameters of a hyperelastic material property associated to the fingertip soft tissues. Fingertip compression tests in an MRI device were performed on 5 subjects at either 2 or 4 N and at 15° or 50°. The MRI images allowed to document both the internal and external fingertip dimensions and to build 5 subject-specific finite element models. Simulations reproducing the fingertip compression tests were run to obtain the material property parameters of the soft tissues. Results indicated that two ellipses in the sagittal and longitudinal plane could describe the external fingertip geometry. The internal geometries indicated an averaged maximal thickness of soft tissues of 6.4 ± 0.8 mm and a 4 ± 1 mm height for the phalanx bone. The averaged deflections under loading went from 1.8 ± 0.3 mm at 2 N, 50° to 3.1 ± 0.2 mm at 4 N, 15°. Finally, the following set of parameters for a second order hyperelastic law to model the fingertip soft tissues was proposed: C 01 =0.59 ± 0.09 kPa and C 20  = 2.65 ± 0.88 kPa. These data should facilitate further efforts on fingertip finite element modeling. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. High temperature properties and processes in ceramics: thermomigration

    International Nuclear Information System (INIS)

    1978-01-01

    The focus of this program is on the effects of large temperature gradients on the transport processes, the defect structure and resulting physical properties of ceramics. In particular, the transport of ions due to thermal gradients is one of the least understood phenomenon in materials science and is presumably based on fundamental understanding of thermodynamics, atomistic kinetic processes, and structure-property relationships. The purpose of this research is to systematically consider each of the elements of atomic transport due to driving forces other than composition gradients in a model ceramic system

  12. Coupled Effect of Elevated Temperature and Cooling Conditions on the Properties of Ground Clay Brick Mortars

    Science.gov (United States)

    Ali Abd El Aziz, Magdy; Abdelaleem, Salh; Heikal, Mohamed

    2013-12-01

    When a concrete structure is exposed to fire and cooling, some deterioration in its chemical resistivity and mechanical properties takes place. This deterioration can reach a level at which the structure may have to be thoroughly renovated or completely replaced. In this investigation, four types of cement mortars, ground clay bricks (GCB)/sand namely 0/3, 1/2, 2/1 and 3/0, were used. Three different cement contents were used: 350, 400 and 450 kg/m3. All the mortars were prepared and cured in tap water for 3 months and then kept in laboratory atmospheric conditions up to 6 months. The specimens were subjected to elevated temperatures up to 700°C for 3h and then cooled by three different conditions: water, furnace, and air cooling. The results show that all the mortars subjected to fire, irrespective of cooling mode, suffered a significant reduction in compressive strength. However, the mortars cooled in air exhibited a relativity higher reduction in compressive strength rather than those water or furnace cooled. The mortars containing GCB/sand (3/0) and GCB/sand (1/2) exhibited a relatively higher thermal stability than the others.

  13. Evaluation of visco-elastic properties of conditioned wheat kernels and their doughs using a compression test under small strain.

    Science.gov (United States)

    Ponce-García, Néstor; Ramírez-Wong, Benjamín; Torres-Chávez, Patricia I; Figueroa-Cárdenas, Juan de Dios; Serna-Saldívar, Sergio O; Cortez-Rocha, Mario O; Escalante-Aburto, Anayansi

    2017-03-01

    The aim of this research was to evaluate the visco-elastic properties of conditioned wheat kernels and their doughs by applying the compression test under a small strain. Conditioned wheat kernels and their doughs, from soft and hard wheat classes were evaluated for total work (W t ), elastic work (W e ) and plastic work (W p ). Soft wheat kernels showed lower W e than W p , while the hard wheat kernels had a W e that was higher than W p . Regarding dough visco-elasticity, cultivars from soft and hard wheat showed higher W p than W e . The degree of elasticity (DE%) of the conditioned wheat kernel related to its dough decreased ∼46% in both wheat classes. The W t , W e and W p from the soft wheat kernel and dough correlated with physico-chemical and farinographic flour tests. The W t , W p and the maximum compression force (F max ) of the dough from hard wheat class presented highly significant negative correlations with wet gluten. The visco-elasticity parameters from compression test presented significant differences among conditioned wheat classes and their doughs. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  14. Compression of Multilayered Composite Electrospun Scaffolds: A Novel Strategy to Rapidly Enhance Mechanical Properties and Three Dimensionality of Bone Scaffolds

    Directory of Open Access Journals (Sweden)

    Parthasarathy A. Madurantakam

    2013-01-01

    Full Text Available One major limitation of electrospun scaffolds intended for bone tissue engineering is their inferior mechanical properties. The present study introduces a novel strategy to engineer stiffer scaffolds by stacking multiple layers and cold welding them under high pressure. Electrospun polydioxanone (PDO and PDO:nanohydroxyapatite (PDO:nHA scaffolds (1, 2, or 4 layered stacks were compressed either before or after mineralizing treatment with simulated body fluid (SBF. After two weeks in SBF, scaffolds were analyzed for total mineral content and stiffness by Alizarin red S and uniaxial tensile testing, respectively. Scaffolds were also analyzed for permeability, pore size, and fiber diameter. Results indicated that compression of multiple layers significantly increased the stiffness of scaffolds while reducing mineralization and permeability. This phenomenon was attributed to increased density of fibers and loss of surface area due to fiber welding. Statistics revealed, the 4-layered PDO:nHA scaffold compressed first followed by mineralization in revised SBF had maximal stiffness, low permeability and pore size, and mineralization second only to noncompressed scaffolds. Within the limitations of permeability and pore size, this scaffold configuration represents an optimal midway for desired stiffness and mineral content for bone tissue engineering.

  15. Size effect on compression properties of GaN nanocones examined using in situ transmission electron microscopy

    International Nuclear Information System (INIS)

    Kang, Shao-Hui; Fang, Te-Hua

    2014-01-01

    Highlights: • Strain-induced structural variations of GaN nanocones are estimated using in situ TEM. • Young’s modulus of GaN nanocones with a diameter of 100–350 nm are 190–290 GPa. • The E 2 peak was red-shifted, indicated increased compressive stress. - Abstract: Mechanical property measurements of single nanocones are challenging because the small scale of the nanostructures. In this study, critical-stress- and strain-induced structural variations of GaN nanocones are estimated using in situ transmission electron microscopy (TEM) compression experiments. For single GaN nanocones with a diameter of 100–350 nm, the Young’s modulus, plastic deformation energy (W p ), and elastic deformation energy (W e ) values were 190–290 GPa, 0.02–1.65 × 10 −11 J, and 0.04–3.85 × 10 −11 J, respectively. Raman spectra were used to measure GaN indentation. The E 2 peak was red-shifted, indicated increased compressive stress in the indented area

  16. Influence of fiber length on flexural and impact properties of Zalacca Midrib fiber/HDPE by compression molding

    Science.gov (United States)

    Pamungkas, Agil Fitri; Ariawan, Dody; Surojo, Eko; Triyono, Joko

    2018-02-01

    The aim of the research is to investigate the effect of fiber length on the flexural and impact properties of the composite of Zalacca Midrib Fiber (ZMF)/HDPE. The process of making composite was using compression molding method. The variation of fiber length were 1 mm, 3 mm, 5 mm, 7 mm and 9 mm, at 30% fiber volume fraction. The flexural and impact test according to ASTM D790 and ASTM D5941, respectively. Observing fracture surface was examained by using Scanning Electron Microscopy (SEM). The results showed that the flexural and impact strengths would be increase with the increase of fiber length.

  17. High Temperature Oxidation and Mechanical properties of Silicon Nitride.

    Science.gov (United States)

    1980-11-30

    Continuo on r.vers side it nec..eary and iden0 y by block nmber)I : silicon nitride ~ceramics :! corrosion strength oxidation 20. 4 ACT (Continue on...concentration that optimizes densifi- cation during hot pressing can be altered to improve mechanical properties and oxidation resistance by removing Mg...the intergranular phase to improve the high-temperature- strength, creep resistance, and oxidation resistance. Preoxidation followed by surface

  18. Property changes in graphite irradiated at changing irradiation temperature

    International Nuclear Information System (INIS)

    Price, R.J.; Haag, G.

    1979-07-01

    Design data for irradiated graphite are usually presented as families of isothermal curves showing the change in physical property as a function of fast neutron fluence. In this report, procedures for combining isothermal curves to predict behavior under changing irradiation temperatures are compared with experimental data on irradiation-induced changes in dimensions, Young's modulus, thermal conductivity, and thermal expansivity. The suggested procedure fits the data quite well and is physically realistic

  19. Low-temperature localization in the transport properties of self ...

    Indian Academy of Sciences (India)

    293–298. c Indian Academy of Sciences. Low-temperature localization in the transport properties of self-doped. La0.9Mn0.98Zn0.02O3. K DE1 and S DAS2,∗. 1Neotia Institute of Technology, Management and Science, Jhinga 743 368, India. 2Department of Electronics and Communication Engineering, Guru Ghasidas ...

  20. Temperature and pressure dependence of the order parameter fluctuations, conformational compressibility, and the phase diagram of the PEP-PDMS diblock copolymer

    DEFF Research Database (Denmark)

    Schwahn, D.; Frielinghaus, H.; Mortensen, K.

    1996-01-01

    The structure factor of a poly(ethylene-propylene)-poly(dimethylsiloxane) diblock copolymer has been measured by small-angle neutron scattering as a function of temperature and pressure. The conformational compressibility exhibits a pronounced maximum at the order-disorder phase transition. The p...

  1. Effect of Fiber Orientation on Dynamic Compressive Properties of an Ultra-High Performance Concrete

    Science.gov (United States)

    2017-08-01

    varying types of fibers on the post-peak compression behavior of UHPC. As might be expected qualitatively, adding fibers results in a more gradual descent...predominantly affected by alignment in the direction of flow . The following figures illustrate the vari - ation of fiber orientation as a function of...orientations were non-destructively evaluated using x-ray computed tomography. Fibers showed flow -induced alignment along the length of the beam. The

  2. Effect of temperature to the properties of sago starch

    Science.gov (United States)

    Mustafa Kamal, M.; Baini, R.; Mohamaddan, S.; Selaman, O. S.; Zauzi, N. Ahmad; Rahman, M. R.; Rahman, N. Abdul; Chong, K. H.; Atan, M. F.; Samat, N. A. S. Abdul; Taib, S. N. L.; Othman, A. K.

    2017-06-01

    Recently, the importance of sago starch has increased, as it has become one of the main economically important agricultural crops to the most Southeast Asia countries. In the present work, an analysis on drying process of sago starch (Metroxylon sagu Rottb.) underwent various temperature has been made by using four empirical equations. The main goal of this analysis is to suggest the most accurate equation, in order to model and simulate the mechanical drying of sago starch. The experimental investigations were carried out in a gravity convection lab oven; and ±50g of sago starch (sample heights of 1 cm) was dried through four different temperatures, which were 50, 60, 70 and 80ºC. The effect of drying temperature on the drying kinetics, as well as various qualities attributes of sago starch, such as microstructure, colour and functional properties were investigated. The results suggested that drying temperature has significant effect on sago starch drying kinetic; therefore, drying temperature would be the basis to select drying condition. Meanwhile, it was found that the various drying temperature ranging from 50 to 80ºC affected the product quality especially in term of colour.

  3. Photoacoustic technique to measure temperature effects on microbubble viscoelastic properties

    Science.gov (United States)

    Lum, Jordan S.; Stobbe, David M.; Borden, Mark A.; Murray, Todd W.

    2018-03-01

    Phospholipid-coated microbubbles are being developed for several biomedical applications, but little is known about the effect of temperature on the viscoelastic properties of the shell. Here, we report on the use of a photoacoustic technique to study the shell properties of individual microbubbles as a function of temperature. The microbubbles were driven into small-amplitude oscillations by ultrasound waves generated from the absorption of an intensity-modulated infrared laser, and these oscillations were detected by forward-light scattering of a second blue laser. The drive laser modulation frequency was swept to determine the resonant response of 2-4 μm radius microbubbles. Lipid shell elasticity and viscosity were determined by modeling the microbubble response as a linear harmonic oscillator. The results from slow heating showed a linear decrease in elasticity and viscosity between 21 and 53 °C and a corresponding increase in the maximum oscillation amplitude. Rapid heating to 38 °C, on the other hand, showed a transient response in the viscoelastic properties, suggesting shell rupture and reformation during microbubble growth and subsequent dissolution. These effects are important for biomedical applications, which require warming of the microbubbles to body temperature.

  4. Compressive Creep Performance and High Temperature Dimensional Stability of Conventional Silica Refractories

    Energy Technology Data Exchange (ETDEWEB)

    Karakus, M.; Kirkland, T.P.; Liu, K.C.; Moore, R.E.; Pint, B.A.; Wereszczak, A.A.

    1999-03-01

    Furnace designers and refractory engineers recognize that optimized furnace superstructure design and refractory selection are needed as glass production furnaces are continually striving toward greater output and efficiencies. Harsher operating conditions test refractories to the limit, while changing production technology (such as the conversion to oxy-fuel from traditional air-fuel firing) can alter the way the materials perform. Refractories for both oxy- and air-fuel fired furnace superstructures are subjected to high temperatures during service that may cause them to excessively creep or subside if the refractory material is not creep resistant, or if it is subjected to high stress, or both. Furnace designers can ensure that superstructure structural integrity is maintained if the creep behavior of the refractory material is well understood and well represented by appropriate engineering creep models. Several issues limit the abilities of furnace designers to (1) choose the optimum refractory for their applications, (2) optimize the engineering design, or (3) predict the service mechanical integrity of their furnace superstructures. Published engineering creep data are essentially non-existent for almost all commercially available refractories used for glass furnace superstructures. The limited data that do exist are supplied by the various refractory suppliers. Unfortunately, these suppliers generally have different ways of conducting their mechanical testing and they also interpret and report their data differently; this makes it hard for furnace designers to draw fair comparisons between competing grades of candidate refractories. Furthermore, the refractory supplier's data are often not available in a form that can be readily used for furnace design and for the prediction and design of long-term structural integrity of furnace superstructures. With the aim of providing such comparable data, the US DOE's Office of Industrial Technology and its

  5. Heat experiment design to estimate temperature dependent thermal properties

    International Nuclear Information System (INIS)

    Romanovski, M

    2008-01-01

    Experimental conditions are studied to optimize transient experiments for estimating temperature dependent thermal conductivity and volumetric heat capacity. A mathematical model of a specimen is the one-dimensional heat equation with boundary conditions of the second kind. Thermal properties are assumed to vary nonlinearly with temperature. Experimental conditions refer to the thermal loading scheme, sampling times and sensor location. A numerical model of experimental configurations is studied to elicit the optimal conditions. The numerical solution of the design problem is formulated on a regularization scheme with a stabilizer minimization without a regularization parameter. An explicit design criterion is used to reveal the optimal sensor location, heating duration and flux magnitude. Results obtained indicate that even the strongly nonlinear experimental design problem admits the aggregation of its solution and has a strictly defined optimal measurement scheme. Additional region of temperature measurements with allowable identification error is revealed.

  6. To Study Capping or Lamination Tendency of Tablets Through Evaluation of Powder Rheological Properties and Tablet Mechanical Properties of Directly Compressible Blends.

    Science.gov (United States)

    Dudhat, Siddhi M; Kettler, Charles N; Dave, Rutesh H

    2017-05-01

    Air entrapment efficiency of the powders is one of the main factors leading to occurrence of capping or lamination tendency of tablets manufactured from the directly compressible powder blends. The purpose of the current research was to study this underlying cause leading to occurrence of capping or lamination of tablets through evaluation of powder rheological properties. Powder blends were prepared by addition of 0% w/w to 100% w/w of individual active pharmaceutical ingredient (API) [two model API: acetaminophen (APAP) and ibuprofen (IBU)] with microcrystalline cellulose without and with 0.5% w/w Magnesium Stearate as lubricant. Powder rheological properties were analyzed using FT4 Powder Rheometer for dynamic, bulk, and shear properties. Tablet mechanical properties of the respective blends were studied by determining the ability of the material to form tablet of specific strength under applied compaction pressure through tabletability profile. The results showed that powder rheometer distinguished the powder blends based on their ability to relieve entrapped air along with the distinctive flow characteristics. Powder blend prepared with increasing addition of APAP displayed low powder permeability as compared to IBU blends with better powder permeability, compressibility and flow characteristics. Also, lubrication of the APAP blends did not ease their ability to relieve air. Tabletability profiles revealed the potential occurrence of capping or lamination in tablets prepared from the powder blends with high APAP content. This study can help scientist to understand tableting performance at the early-developmental stages and can avoid occurrence capping and lamination of tablets.

  7. Compression and shear properties of elastomeric bearing using finite element analysis

    Directory of Open Access Journals (Sweden)

    2Faculty of Science and Technology, Chiang Mai Rajabhat University, Muang, Chiang Mai, 50300 Thailand.

    2006-09-01

    Full Text Available Standard size samples of four natural rubber compounds, varying the amount of carbon black from 10 to 70 phr, were characterised under uniaxial compression and simple shear tests in order to obtain the strain energy function constants. These constants were then used as hyperelastic material constants for the Windows-based finite element package (COSMOS/M version 1.75. The investigated bearings, made with those NR compounds, had the approximate area and thickness of 50x106 mm2 and 50 mm respectively. Each compound of bearing consisted of four different values of shape factor ranging from about 0.33 to 1.70, according to the number of reinforcing plates in the bearing. Three deformation modes of compression, shear and compression-shear were predicted. Good agreement was found between twelve compression model predictions and the corresponding experimental values of bearings, containing 10, 20 and 40 phr of carbon black and each of which consisted of four different layers of reinforcing metal plates (0, 1, 2 and 3 layers. On the other hand, deviation from the predicted valve was clearly seen in the 70 phr black bearing case. The percentage difference increased with respect to the increasing number of reinforcing plates or the rising shape factor. Therefore, the improved FEA model was supplemented with an imaginary elastic glue layer between the rubber block and metal plate as glue failure compensation. The optimum value of the elastic layers modulus is 8 MPa while the thickness of the layer depends on the total thickness or total volume of rubber block. This model can predict the 70 phr carbon black bearings, having shape factor ranging from 0.5 to 2.35 for 11 cases. The FEA prediction of shear behaviour agrees well with the experimental data for all four bearing compounds and there is no effect of shape factor on shear stress. Moreover, shear stress does not depend on the compressive force applied to like bearing before shear and the FEA results

  8. Microstructure and Properties of High-Temperature Superconductors

    CERN Document Server

    Parinov, I A

    2012-01-01

    The main features of high-temperature superconductors (HTSC) that define their properties are intrinsic brittleness of oxide cuprates, the layered anisotropic structure and the supershort coherence length. Taking into account these features, this treatise presents research into HTSC microstructure and properties, and also explores the possibilities of optimization of the preparation techniques and superconducting compositions. The "composition-technique-experiment-theory-model," employed here, assumes considerable HTSC defectiveness and structure heterogeneity and helps to draw a comprehensive picture of modern representations of the microstructure, strength and the related structure-sensitive properties of the materials considered. Special attention is devoted to the Bi-Sr-Ca-Cu-O and Y-Ba-Cu-O families, which currently offer the most promising applications. Including a great number of illustrations and references, this monograph addresses students, post-graduate students and specialists, taking part in the ...

  9. Microstructure and Properties of High-Temperature Superconductors

    CERN Document Server

    Parinov, Ivan A

    2007-01-01

    The main features of high-temperature superconductors (HTSC) that define their properties are intrinsic brittleness of oxide cuprates, the layered anisotropic structure and the supershort coherence length. Taking into account these features, this treatise presents research into HTSC microstructure and properties, and also explores the possibilities of optimization of the preparation techniques and superconducting compositions. The "composition-technique-experiment-theory-model," employed here, assumes considerable HTSC defectiveness and structure heterogeneity and helps to draw a comprehensive picture of modern representations of the microstructure, strength and the related structure-sensitive properties of the materials considered. Special attention is devoted to the Bi-Sr-Ca-Cu-O and Y-Ba-Cu-O families, which currently offer the most promising applications. Including a great number of illustrations and references, this monograph addresses students, post-graduate students and specialists, taking part in the ...

  10. Effects of Medium Temperature and Industrial By-Products on the Key Hardened Properties of High Performance Concrete.

    Science.gov (United States)

    Safiuddin, Md; Raman, Sudharshan N; Zain, Muhammad Fauzi Mohd

    2015-12-10

    The aim of the work reported in this article was to investigate the effects of medium temperature and industrial by-products on the key hardened properties of high performance concrete. Four concrete mixes were prepared based on a water-to-binder ratio of 0.35. Two industrial by-products, silica fume and Class F fly ash, were used separately and together with normal portland cement to produce three concrete mixes in addition to the control mix. The properties of both fresh and hardened concretes were examined in the laboratory. The freshly mixed concrete mixes were tested for slump, slump flow, and V-funnel flow. The hardened concretes were tested for compressive strength and dynamic modulus of elasticity after exposing to 20, 35 and 50 °C. In addition, the initial surface absorption and the rate of moisture movement into the concretes were determined at 20 °C. The performance of the concretes in the fresh state was excellent due to their superior deformability and good segregation resistance. In their hardened state, the highest levels of compressive strength and dynamic modulus of elasticity were produced by silica fume concrete. In addition, silica fume concrete showed the lowest level of initial surface absorption and the lowest rate of moisture movement into the interior of concrete. In comparison, the compressive strength, dynamic modulus of elasticity, initial surface absorption, and moisture movement rate of silica fume-fly ash concrete were close to those of silica fume concrete. Moreover, all concretes provided relatively low compressive strength and dynamic modulus of elasticity when they were exposed to 50 °C. However, the effect of increased temperature was less detrimental for silica fume and silica fume-fly ash concretes in comparison with the control concrete.

  11. A study of the properties of high temperature polyimide foams

    Science.gov (United States)

    Bodden-Williams, Martha Kay

    In this research, the differences in thermal, mechanical, surface, flammability, and degradation properties of three different, closely related, polyimide foams (namely TEEK-H, TEEK-L and TEEK-C) were comparatively studied. Foams have much higher surface areas than solid polymers and are a greater challenge to fire retard. Because of the intrinsic flame retardancy of aromatic polyimides, one has the ability to investigate the effects of changes in density, surface area, and chemical structure on flame retardancy properties, physical and mechanical properties, and foam degradation that have not been previously reported. Understanding degradation and properties as a function of whether the polymer is porous or nonporous is of significant interest. Data indicate that subtle differences in chemical structure result in large differences in surface area, which further result in large differences in heat release and other flammability properties as observed in radiant panel and cone calorimetry data. Thermal stability and degradation studies indicate that the diamine rather than the dianhydride is the greater contributing factor to the thermal stability of polyimide foams. The degradation mechanisms follow that reported previously in the literature for polyimide films. X-ray photoelectron spectroscopy (XPS) analyses of oxygen-plasma-exposed samples indicate an overall oxidation of the foams and that the degradation mechanism follows that of thermal degradation. The mass loss data after oxygen plasma exposure indicate that chemical structure followed by density play the greatest role in atomic oxygen resistance. A unique weathering study of the polyimide foams gave further insight into the relationship of chemistry, density, and surface area effects. XPS, Infrared and Raman spectroscopies, plus thermogravimetric and thermomechanical analyses, confirm that unlike the thermal and oxygen plasma exposures, the carbonyl linkage in the dianhydride of the TEEK-L series has a

  12. Thermodynamic Properties of He Gas in the Temperature Range 4.2-10 K

    Science.gov (United States)

    Mosameh, S. M.; Sandouqa, A. S.; Ghassib, H. B.; Joudeh, B. R.

    2014-05-01

    The thermodynamic properties of He gas are investigated in the temperature-range 4.2-10 K, with special emphasis on the second virial coefficient in both the classical and quantum regimes. The main input in computing the quantum coefficient is the `effective' phase shifts. These are calculated within the framework of the Galitskii-Migdal-Feynman (GMF) formalism, using the HFDHE2 and Sposito potentials. The virial equation of state is constructed. Extensive calculations are carried out for the pressure-volume-temperature (P-V-T) behavior, as well as chemical potential, and nonideality of the system. The following results are obtained. First, the validity of the GMF formalism for the present system is demonstrated beyond any doubt. Second, the boiling point (phase-transition point) of He gas is determined from the P-V behavior using the virial equation of state, its value being closest than all previous results to the experimental value. Third, the chemical potential is evaluated from the quantum second virial coefficient. It is found that increases (becomes less negative) as the temperature decreases or the number density n increases. Further, shows no sensitivity to the differences between the potentials used up to n = 10 m. Finally, the compressibility Z is computed and discussed as a measure of the nonideality of the system.

  13. Effects of Mixing Temperature and Wood Powder Size on Mechanical Properties of Wood Plastic Recycled Composite

    Science.gov (United States)

    Miki, Tsunehisa; Sugimoto, Hiroyuki; Kojiro, Keisuke; Kanayama, Kozo; Yamamoto, Ken

    In this study, wood (cedar) powder ranging from 53 µm to 1 mm sizes, recycled polypropylene (PP) / polyethylene (PE) and acid-modified PP as a compatibilization agent were used to produce a wood-plastic recycled composite (WPRC). For discussing the effects of the wood powder sizes on the mechanical properties of the WPRC, a mixing process of the wood powder and the plastics in a constant wood content of 50% weight was firstly performed by a mixing machine controlled temperature and rotation of mixing blade. And then, to obtain WPRC panels the wood and plastics mixtures were compressed in a mould under a constant pressure and a temperature for a certain holding time. WPRC specimens for mechanical tests were cut from the WPRC panels, and a tensile strength and a size-stability were acquired. The results show that the successful mixing process runs above 180°C, where the mixing torque required compounding keeps constant or slightly increases. The tensile strength of the WPRC increases when the smaller size of wood powder is used for wood/plastic compound under successful mixing conditions. It is shown from thickness change rate of specimens that mixing temperature of wood/plastic compound affects a size stability of the WPRC.

  14. Experimental Investigation on the Fatigue Mechanical Properties of Intermittently Jointed Rock Models Under Cyclic Uniaxial Compression with Different Loading Parameters

    Science.gov (United States)

    Liu, Yi; Dai, Feng; Dong, Lu; Xu, Nuwen; Feng, Peng

    2018-01-01

    Intermittently jointed rocks, widely existing in many mining and civil engineering structures, are quite susceptible to cyclic loading. Understanding the fatigue mechanism of jointed rocks is vital to the rational design and the long-term stability analysis of rock structures. In this study, the fatigue mechanical properties of synthetic jointed rock models under different cyclic conditions are systematically investigated in the laboratory, including four loading frequencies, four maximum stresses, and four amplitudes. Our experimental results reveal the influence of the three cyclic loading parameters on the mechanical properties of jointed rock models, regarding the fatigue deformation characteristics, the fatigue energy and damage evolution, and the fatigue failure and progressive failure behavior. Under lower loading frequency or higher maximum stress and amplitude, the jointed specimen is characterized by higher fatigue deformation moduli and higher dissipated hysteresis energy, resulting in higher cumulative damage and lower fatigue life. However, the fatigue failure modes of jointed specimens are independent of cyclic loading parameters; all tested jointed specimens exhibit a prominent tensile splitting failure mode. Three different crack coalescence patterns are classified between two adjacent joints. Furthermore, different from the progressive failure under static monotonic loading, the jointed rock specimens under cyclic compression fail more abruptly without evident preceding signs. The tensile cracks on the front surface of jointed specimens always initiate from the joint tips and then propagate at a certain angle with the joints toward the direction of maximum compression.

  15. High-pressure compressibility and vibrational properties of (Ca,Mn)CO 3

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jin; Caracas, Razvan; Fan, Dawei; Bobocioiu, Ema; Zhang, Dongzhou; Mao, Wendy L.

    2016-12-01

    Knowledge of potential carbon carriers such as carbonates is critical for our understanding of the deep-carbon cycle and related geological processes within the planet. Here we investigated the high-pressure behavior of (Ca,Mn)CO3 up to 75 GPa by synchrotron single-crystal X-ray diffraction, laser Raman spectroscopy, and theoretical calculations. MnCO3-rich carbonate underwent a structural phase transition from the CaCO3-I structure into the CaCO3-VI structure at 45–48 GPa, while CaCO3-rich carbonate transformed into CaCO3-III and CaCO3-VI at approximately 2 and 15 GPa, respectively. The equation of state and vibrational properties of MnCO3-rich and CaCO3-rich carbonates changed dramatically across the phase transition. The CaCO3-VI-structured CaCO3-rich and MnCO3-rich carbonates were stable at room temperature up to at least 53 and 75 GPa, respectively. The addition of smaller cations (e.g., Mn2+, Mg2+, and Fe2+) can enlarge the stability field of the CaCO3-I phase as well as increase the pressure of the structural transition into the CaCO3-VI phase.

  16. Impact of temperature on the biological properties of soil

    Science.gov (United States)

    Borowik, Agata; Wyszkowska, Jadwiga

    2016-01-01

    The aim of the study was to determine the response of soil microorganisms and enzymes to the temperature of soil. The effect of the temperatures: 5, 10, 15, 20, and 25°C on the biological properties of soil was investigated under laboratory conditions. The study was performed using four different soils differing in their granulometric composition. It was found that 15°C was the optimal temperature for the development of microorganisms in soil. Typically, in the soil, the highest activity of dehydrogenases was observed at 10-15°C, catalase and acid phosphatase - at 15°C, alkaline phosphatase at 20°C, urease and β-glucosidase at 25°C. The highest colony development index for heterotrophic bacteria was recorded in soils incubated at 25°C, while for actinomycetes and fungi at 15°C. The incubation temperature of soil only slightly changed the ecophysiological variety of the investigated groups of microorganisms. Therefore, the observed climate changes might have a limited impact on the soil microbiological activity, because of the high ability of microorganisms to adopt. The response of soil microorganisms and enzymes was more dependent on the soil granulometric composition, organic carbon, and total nitrogen than on its temperature.

  17. Properties of Free-Machining Aluminum Alloys at Elevated Temperatures

    Science.gov (United States)

    Faltus, Jiří; Karlík, Miroslav; Haušild, Petr

    In areas close to the cutting tool the workpieces being dry machined could be heated up to 350°C and they may be impact loaded. Therefore it is of interest to study mechanical properties of corresponding materials at elevated temperatures. Free-machining alloys of Al-Cu and Al-Mg-Si systems containing Pb, Bi and Sn additions (AA2011, AA2111B, AA6262, and AA6023) were subjected to Charpy U notch impact test at the temperatures ranging from 20 to 350°C. The tested alloys show a sharp drop in notch impact strength KU at different temperatures. This drop of KU is caused by liquid metal embrittlement due to the melting of low-melting point dispersed phases which is documented by differential scanning calorimetry. Fracture surfaces of the specimens were observed using a scanning electron microscope. At room temperature, the fractures of all studied alloys exhibited similar ductile dimple fracture micromorphology, at elevated temperatures, numerous secondary intergranular cracks were observed.

  18. Thermal properties of SFR-HPC exposed to high temperatures

    Science.gov (United States)

    Scheinherrová, Lenka; Pavlík, Zbyšek

    2017-07-01

    In this paper, a non-adiabatic method was used for the assessment of specific heat capacity of steel fibre reinforced high performance concrete in the temperature range 105-1000 °C. The tested SFR-HPC mix was produced from CEM II 42.5 R, ground granulated blast furnace slag, silica sand with maximum particle size of 2 mm, silica fume, brass-coated steel fibres, superplasticizer on polycarboxylate ether basis and batch water. For the studied material, properties after 2 hours thermal treatment at the temperatures of 105 °C, 200 °C, 400 °C, 600 °C, 800 °C, and 1000 °C respectively were tested. Among them, bulk density, matrix density, total open porosity and thermal parameters as thermal conductivity, thermal diffusivity and specific heat capacity were measured. The measured specific heat capacity exhibited high dependence on temperature and pointed to the structural changes that studied material underwent at high temperatures. Accordingly, the obtained residual parameters revealed the thermally induced damage of SFR-HPC and critical temperatures for its functionality.

  19. Microstructure and compression properties of 3D powder printed Ti-6Al-4V scaffolds with designed porosity: Experimental and computational analysis.

    Science.gov (United States)

    Barui, Srimanta; Chatterjee, Subhomoy; Mandal, Sourav; Kumar, Alok; Basu, Bikramjit

    2017-01-01

    The osseointegration of metallic implants depends on an effective balance among designed porosity to facilitate angiogenesis, tissue in-growth and bone-mimicking elastic modulus with good strength properties. While addressing such twin requirements, the present study demonstrates a low temperature additive manufacturing based processing strategy to fabricate Ti-6Al-4V scaffolds with designed porosity using inkjet-based 3D powder printing (3DPP). A novel starch-based aqueous binder was prepared and the physico-chemical parameters such as pH, viscosity, and surface tension were optimized for drop-on-demand (DOD) based thermal inkjet printing. Micro-computed tomography (micro-CT) of sintered scaffolds revealed a 57% total porosity in homogeneously porous scaffold and 45% in the gradient porous scaffold with 99% interconnectivity among the micropores. Under uniaxial compression testing, the strength of homogeneously porous and gradient porous scaffolds were ~47MPa and ~90MPa, respectively. The progressive failure in homogeneously porous scaffold was recorded. In parallel to experimental measurements, finite element (FE) analyses have been performed to study the stress distribution globally and also locally around the designed pores. Consistent with FE analyses, a higher elastic modulus was recorded with gradient porous scaffolds (~3GPa) than the homogenously porous scaffolds (~2GPa). While comparing with the existing literature reports, the present work, for the first time, establishes 'direct powder printing methodology' of Ti-6Al-4V porous scaffolds with biomedically relevant microstructural and mechanical properties. Also, a new FE analysis approach, based on the critical understanding of the porous architecture using micro-CT results, is presented to realistically predict the compression response of porous scaffolds. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Analysis of the three-point-bend test for materials with unequal tension and compression properties

    Science.gov (United States)

    Chamis, C. C.

    1974-01-01

    Structural resins have moduli and strengths which are different in tension and compression. The three-point-bend test is used extensively in their characterization. An investigation is performed to derive all the equations needed for the analysis and test data reduction of the three-point-bend test. The governing equations are derived using well-known linear structural mechanics principles and are represented graphically. The stress concentration effects in the vicinity of the load point are investigated, and failure stress and failure initiation are examined.

  1. The influence of phosphorylation and freezing temperature on the mechanical properties of hydroxyapatite/chitosan composite as bone scaffold biomaterial

    Science.gov (United States)

    Albab, Muh Fadhil; Giovani, Nicholas; Yuwono, Akhmad Herman; Sofyan, Nofrijon; Ramahdita, Ghiska; Whulanza, Yudan

    2018-02-01

    Biomaterials composite of hydroxyapatite/chitosan is a preeminent material for medical applications including bone scaffold. To improve its mechanical properties, the chitosan as the matrix needs to be modified with particular chemical agents. One of the methods is phosphorylation of chitosan by using orthophosphoric acid prior to the biomaterials fabrication. In the current study, biomaterials with the weight composition of 70% hydroxyapatite (HA) and 30% phosphorylated chitosan have been fabricated using thermally induced phase separation (TIPS) method with freezing temperature variation of -20, -30, -40 and -80°C prior to three day-freeze drying. The results obtained by this work showed that the highest compression modulus of 376.9 kPa, highest compressive strength of 38.4 kPa and biggest pore size of 48.24 µm were achieved in the freezing temperature of -20°C. In comparison to non-phosphorylated chitosan/hydroxyapatite, the modification of chitosan using orthophosphoric acid in this work has been found to increase the compressive strength of composite up to 5.5 times.

  2. Thermo-fluid dynamic analysis of wet compression process

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, Abhay; Kim, Heuy Dong [School of Mechanical Engineering, Andong National University, Andong (Korea, Republic of); Chidambaram, Palani Kumar [FMTRC, Daejoo Machinery Co. Ltd., Daegu (Korea, Republic of); Suryan, Abhilash [Dept. of Mechanical Engineering, College of Engineering Trivandrum, Kerala (India)

    2016-12-15

    Wet compression systems increase the useful power output of a gas turbine by reducing the compressor work through the reduction of air temperature inside the compressor. The actual wet compression process differs from the conventional single phase compression process due to the presence of latent heat component being absorbed by the evaporating water droplets. Thus the wet compression process cannot be assumed isentropic. In the current investigation, the gas-liquid two phase has been modeled as air containing dispersed water droplets inside a simple cylinder-piston system. The piston moves in the axial direction inside the cylinder to achieve wet compression. Effects on the thermodynamic properties such as temperature, pressure and relative humidity are investigated in detail for different parameters such as compression speeds and overspray. An analytical model is derived and the requisite thermodynamic curves are generated. The deviations of generated thermodynamic curves from the dry isentropic curves (PV{sup γ} = constant) are analyzed.

  3. Thermo-fluid dynamic analysis of wet compression process

    International Nuclear Information System (INIS)

    Mohan, Abhay; Kim, Heuy Dong; Chidambaram, Palani Kumar; Suryan, Abhilash

    2016-01-01

    Wet compression systems increase the useful power output of a gas turbine by reducing the compressor work through the reduction of air temperature inside the compressor. The actual wet compression process differs from the conventional single phase compression process due to the presence of latent heat component being absorbed by the evaporating water droplets. Thus the wet compression process cannot be assumed isentropic. In the current investigation, the gas-liquid two phase has been modeled as air containing dispersed water droplets inside a simple cylinder-piston system. The piston moves in the axial direction inside the cylinder to achieve wet compression. Effects on the thermodynamic properties such as temperature, pressure and relative humidity are investigated in detail for different parameters such as compression speeds and overspray. An analytical model is derived and the requisite thermodynamic curves are generated. The deviations of generated thermodynamic curves from the dry isentropic curves (PV γ = constant) are analyzed

  4. Biomechanical Property of a Newly Designed Assembly Locking Compression Plate: Three-Dimensional Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Jiang-Jun Zhou

    2017-01-01

    Full Text Available In this study, we developed and validated a refined three-dimensional finite element model of middle femoral comminuted fracture to compare the biomechanical stability after two kinds of plate fixation: a newly designed assembly locking compression plate (NALCP and a locking compression plate (LCP. CT data of a male volunteer was converted to middle femoral comminuted fracture finite element analysis model. The fracture was fixated by NALCP and LCP. Stress distributions were observed. Under slow walking load and torsion load, the stress distribution tendency of the two plates was roughly uniform. The anterolateral femur was the tension stress area, and the bone block shifted toward the anterolateral femur. Maximum stress was found on the lateral border of the number 5 countersink of the plate. Under a slow walking load, the NALCP maximum stress was 2.160e+03 MPa and the LCP was 8.561e+02 MPa. Under torsion load, the NALCP maximum stress was 2.260e+03 MPa and the LCP was 6.813e+02 MPa. Based on those results of finite element analysis, the NALCP can provide adequate mechanical stability for comminuted fractures, which would help fixate the bone block and promote bone healing.

  5. Temperature-dependent transport properties of FeRh

    Science.gov (United States)

    Mankovsky, S.; Polesya, S.; Chadova, K.; Ebert, H.; Staunton, J. B.; Gruenbaum, T.; Schoen, M. A. W.; Back, C. H.; Chen, X. Z.; Song, C.

    2017-04-01

    The finite-temperature transport properties of FeRh compounds are investigated by first-principles density-functional-theory-based calculations. The focus is on the behavior of the longitudinal resistivity with rising temperature, which exhibits an abrupt decrease at the metamagnetic transition point, T =Tm , between ferro- and antiferromagnetic phases. A detailed electronic structure investigation for T ≥0 K explains this feature and demonstrates the important role of (i) the difference of the electronic structure at the Fermi level between the two magnetically ordered states and (ii) the different degree of thermally induced magnetic disorder in the vicinity of Tm, giving different contributions to the resistivity. To support these conclusions, we also describe the temperature dependence of the spin-orbit-induced anomalous Hall resistivity and Gilbert damping parameter. For the various response quantities considered, the impact of thermal lattice vibrations and spin fluctuations on their temperature dependence is investigated in detail. Comparison with corresponding experimental data shows, in general, very good agreement.

  6. Neighborhood properties are important determinants of temperature sensitive mutations.

    Directory of Open Access Journals (Sweden)

    Svetlana Lockwood

    Full Text Available Temperature-sensitive (TS mutants are powerful tools to study gene function in vivo. These mutants exhibit wild-type activity at permissive temperatures and reduced activity at restrictive temperatures. Although random mutagenesis can be used to generate TS mutants, the procedure is laborious and unfeasible in multicellular organisms. Further, the underlying molecular mechanisms of the TS phenotype are poorly understood. To elucidate TS mechanisms, we used a machine learning method-logistic regression-to investigate a large number of sequence and structure features. We developed and tested 133 features, describing properties of either the mutation site or the mutation site neighborhood. We defined three types of neighborhood using sequence distance, Euclidean distance, and topological distance. We discovered that neighborhood features outperformed mutation site features in predicting TS mutations. The most predictive features suggest that TS mutations tend to occur at buried and rigid residues, and are located at conserved protein domains. The environment of a buried residue often determines the overall structural stability of a protein, thus may lead to reversible activity change upon temperature switch. We developed TS prediction models based on logistic regression and the Lasso regularized procedure. Through a ten-fold cross-validation, we obtained the area under the curve of 0.91 for the model using both sequence and structure features. Testing on independent datasets suggested that the model predicted TS mutations with a 50% precision. In summary, our study elucidated the molecular basis of TS mutants and suggested the importance of neighborhood properties in determining TS mutations. We further developed models to predict TS mutations derived from single amino acid substitutions. In this way, TS mutants can be efficiently obtained through experimentally introducing the predicted mutations.

  7. Characterization of High Temperature Mechanical Properties Using Laser Ultrasound

    Energy Technology Data Exchange (ETDEWEB)

    David Hurley; Stephen Reese; Farhad Farzbod; Rory Kennedy

    2012-05-01

    Mechanical properties are controlled to a large degree by defect structures such as dislocations and grain boundaries. These microstructural features involve a perturbation of the perfect crystal lattice (i.e. strain fields). Viewed in this context, high frequency strain waves (i.e. ultrasound) provide a natural choice to study microstructure mediated mechanical properties. In this presentation we use laser ultrasound to probe mechanical properties of materials. This approach utilizes lasers to excite and detect ultrasonic waves, and as a consequence has unique advantages over other methods—it is noncontacting, requires no couplant or invasive sample preparation (other than that used in metallurgical analysis), and has the demonstrated capability to probe microstructure on a micron scale. Laser techniques are highly reproducible enabling sophisticated, microstructurally informed data analysis. Since light is being used for generation and detection of the ultrasonic wave, the specimen being examined is not mechanically coupled to the transducer. As a result, laser ultrasound can be carried out remotely, an especially attractive characteristic for in situ measurements in severe environments. Several examples involving laser ultrasound to measure mechanical properties in high temperature environments will be presented. Emphasis will be place on understanding the role of grain microstructure.

  8. Subzero Temperature Dip-Coating of Sol-Gel Vanadium Pentoxide: Effect of the Deposition Temperature on the Film Structure, Morphology, and Electrochromic Properties

    Directory of Open Access Journals (Sweden)

    Afaf Almoabadi

    2016-01-01

    Full Text Available Vanadium pentoxide sol-gel prepared thin films were deposited on indium-tin-oxide (ITO substrates by dip-coating at a subzero temperature (−10°C. The structure, morphology, and optical and electrochromic properties of dense and porous vanadium oxide films coated at low temperature were determined and compared to those of the corresponding films deposited under room-temperature conditions. The results indicated that, in the films coated at −10°C, a residual compressive stress exists that would originate from the formation of microvoids during the deposition. These microvoids are preserved during the heat treatment of the films. The microvoid morphology would favor the formation of nanostructures that would be responsible for the improved electrochromic properties of the subzero dip-coated films. Low-temperature coated films, heated at 450°C for several hours, undergo the transformation from a layered to a highly uniform nanorod structure that would be an important feature for different applications.

  9. Mechanical properties of GFRP tube confined recycled concrete under axial compression

    International Nuclear Information System (INIS)

    Wang, Xiaogang; Liang, Chaofeng; Zhou, Zechenglong; Dong, Lanqi; Ding, Kewei; Huang, Jialun

    2015-01-01

    This article outlines the recycled aggregate replacement rate and thick-diameter rate of GFRP tube confined in recycled concrete, which has an important impact on the material's compressive strength. Overall, under the same conditions of using recycled concrete, the bearing capacity of short concrete columns can be improved by using broader GFRP tubes. There is a four-fold increase in the bearing capacity of short concrete columns compared to the short column without the restriction of a GFRP tube. The bearing capacity of a short column crafted by recycled coarse aggregate is much lower (about 30%). than those made by common concrete column Additionally, the bearing capacity of short columns made by recycled fine aggregates is also lower than those made by common concrete (approximately 20%). Finally, we find that there is no significant difference between experimental and theoretical data. (paper)

  10. Mechanical properties of GFRP tube confined recycled concrete under axial compression

    Science.gov (United States)

    Wang, Xiaogang; Liang, Chaofeng; Zhou, Zechenglong; Dong, Lanqi; Ding, Kewei; Huang, Jialun

    2015-07-01

    This article outlines the recycled aggregate replacement rate and thick-diameter rate of GFRP tube confined in recycled concrete, which has an important impact on the material's compressive strength. Overall, under the same conditions of using recycled concrete, the bearing capacity of short concrete columns can be improved by using broader GFRP tubes. There is a four-fold increase in the bearing capacity of short concrete columns compared to the short column without the restriction of a GFRP tube. The bearing capacity of a short column crafted by recycled coarse aggregate is much lower (about 30%). than those made by common concrete column Additionally, the bearing capacity of short columns made by recycled fine aggregates is also lower than those made by common concrete (approximately 20%). Finally, we find that there is no significant difference between experimental and theoretical data.

  11. Dynamic Compressive Strength and Failure of Natural Lake Ice Under Moderate Strain Rates at Near Melting Point Temperature

    Directory of Open Access Journals (Sweden)

    Chunfeng Qi

    Full Text Available Abstract This paper presents a series of uniaxial compressive experiments on natural lake ice under moderate strain-rate in the range of 10−1 to 102 s−1 at −0.1 °C. Natural lake ice samples of 8 cm by 8 cm in cross section and 20 cm high were used to investigate strain-rate dependence of uniaxial compressive strength and flaw effects on ice strength under moderate strain rates. The fracture modes of ice at moderate strain rates were also systematically investigated by using high-speed camera. It is found uniaxial compressive strength of natural lake ice increases with increasing strain-rate in the employed moderate strain-rate range. And natural flaws such as air bubble have a significant effect on uniaxial compressive strength of ice under moderate strain-rate, higher air content ice possesses lower compressive strength. Ice fracture mode depends on strain-rate (or compressive velocity of ice specimen, varying from splitting at strain rates lower than 10 s−1 to crushing at strain rates higher than 10 s−1. Ice specimen crushes into fine fragments may due to insufficient time for micro cracks to propagate, thus results in higher strength. In addition, dependence of compressive strength on strain-rate in a wide strain-rate range is also discussed.

  12. Understanding Structure-Property Relations of Compressed Glasses through Relaxation Studies

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Svenson, Mouritz Nolsøe; Youngman, Randall E.

    When a glassy material or its liquid state is subjected to sufficiently high pressure, significant changes can take place in the short- and medium-range structure, vibrational density of states, and physical properties. It is crucial to determine and understand the structure-property relations un...

  13. Thermodynamic modelling and parametric study of a low temperature vapour compression-absorption system based on modified Gouy-Stodola equation

    International Nuclear Information System (INIS)

    Jain, Vaibhav; Sachdeva, Gulshan; Kachhwaha, S.S.

    2015-01-01

    Present paper thermodynamically analyses a VCAS (vapour compression-absorption system) with carbon dioxide (compression section) and ammonia-water (absorption section) as refrigerants and determines the optimal condensing temperature of cascade condenser using modified Gouy-Stodola equation. The optimum cascade condenser temperature is found to be −13 °C for 175 kW refrigeration capacity at an evaporator temperature of −45 °C and condenser temperature of 35 °C. The optimum cascade condenser temperature maximises the overall COP, rational efficiency and minimises the total irreversibility rate of the VCAS system. The value of optimum condensing temperature and its corresponding maximum COP, and minimum irreversibility rate are discussed for a wide range of operating conditions. Further, a comparative study of TSVCS (two stage vapour compression system) used for low temperature refrigeration applications with VCAS shows that at design point, primary energy consumption is reduced by 60.6% and electrical COP is improved by 153.6% in VCAS as compared to conventional TSVCS. But the total irreversibility rate of VCAS is 38.4% higher than the TSVCS due to the use of low grade energy in vapour absorption system and hence the rational efficiency of VCAS is 14% low. - Highlights: • Optimum cascade condenser temperature with modified Gouy-Stodola law is analysed. • It maximises COP, rational efficiency and minimises total irreversibility. • 60.6% of primary energy is saved by cascaded absorption system. • Electrical COP is improved by 153.6% with cascaded absorption system

  14. Effects of Nanosilica on Compressive Strength and Durability Properties of Concrete with Different Water to Binder Ratios

    Directory of Open Access Journals (Sweden)

    Forood Torabian Isfahani

    2016-01-01

    Full Text Available The effects of the addition of different nanosilica dosages (0.5%, 1%, and 1.5% with respect to cement on compressive strength and durability properties of concrete with water/binder ratios 0.65, 0.55, and 0.5 were investigated. Water sorptivity, apparent chloride diffusion coefficient, electrical resistivity, and carbonation coefficient of concrete were measured. The results showed that compressive strength significantly improved in case of water/binder = 0.65, while for water/binder = 0.5 no change was found. Increasing nanosilica content, the water sorptivity decreased only for water/binder = 0.55. The addition of 0.5% nanosilica decreased the apparent chloride diffusion coefficient for water/binder = 0.65 and 0.55; however, higher nanosilica dosages did not decrease it with respect to reference value. The resistivity was elevated by 0.5% nanosilica for all water/binder ratios and by 1.5% nanosilica only for water/binder = 0.5. The carbonation coefficient was not notably affected by increasing nanosilica dosages and even adverse effect was observed for water/binder = 0.65. Further information of microstructure was also provided through characterization techniques such as X-ray diffraction, thermal gravimetric analysis, mercury intrusion porosimetry, and scanning electron microscopy. The effectiveness of a certain nanosilica dosage addition into lower strength mixes was more noticeable, while, for the higher strength mix, the effectiveness was less.

  15. Effect of some prepared superplasticizers (Cyclohexanone Based on compressive strength and physico-chemical properties of oil well cement pastes

    Directory of Open Access Journals (Sweden)

    I. Aiad

    2017-09-01

    Full Text Available Two different superplasticizers particularly cyclohexanone formaldehyde sulfanilate (CFS and cyclohexanone glyoxylic sulfanilate (CGS were prepared; also, their effect on mechanical and physico-chemical properties of oil well cement was assessed. The chemical structures were affirmed by FTIR technique. The designed chemical compounds were predestined as superplasticizers for cement pastes. The pastes were made by superplasticizer (CFS or CGS addition to cement by the ratios of 0, 0.25, 0.50, 0.75, and l.00 as mass% of cement. The water of consistency, setting time, chemically combined water content (Wn, the hydration rate and compressive strength of the admixed hardened pastes were predestined at various time periods. The phase composition was intended by DSC and XRD techniques. The results revealed that as the admixture dose rate increases the demand cement paste water of consistency decreases. Also, as the admixture addition rate increases the chemically combined water content decreases, so the rate of hydration decreases; meanwhile compressive strength magnitudes increase accounting for the low water/cement (initial porosity of the sample.

  16. Mechanical Properties of T650-35/AFR-PE-4 at Elevated Temperatures for Lightweight Aeroshell Designs

    Science.gov (United States)

    Whitley, Karen S.; Collins, TImothy J.

    2006-01-01

    Considerable efforts have been underway to develop multidisciplinary technologies for aeroshell structures that will significantly increase the allowable working temperature for the aeroshell components, and enable the system to operate at higher temperatures while sustaining performance and durability. As part of these efforts, high temperature polymer matrix composites and fabrication technologies are being developed for the primary load bearing structure (heat shield) of the spacecraft. New high-temperature resins and composite material manufacturing techniques are available that have the potential to significantly improve current aeroshell design. In order to qualify a polymer matrix composite (PMC) material as a candidate aeroshell structural material, its performance must be evaluated under realistic environments. Thus, verification testing of lightweight PMC's at aeroshell entry temperatures is needed to ensure that they will perform successfully in high-temperature environments. Towards this end, a test program was developed to characterize the mechanical properties of two candidate material systems, T650-35/AFR-PE-4 and T650-35/RP46. The two candidate high-temperature polyimide resins, AFR-PE-4 and RP46, were developed at the Air Force Research Laboratory and NASA Langley Research Center, respectively. This paper presents experimental methods, strength, and stiffness data of the T650-35/AFR-PE-4 material as a function of elevated temperatures. The properties determined during the research test program herein, included tensile strength, tensile stiffness, Poisson s ratio, compressive strength, compressive stiffness, shear modulus, and shear strength. Unidirectional laminates, a cross-ply laminate and two eight-harness satin (8HS)-weave laminates (4-ply and 10-ply) were tested according to ASTM standard methods at room and elevated temperatures (23, 316, and 343 C). All of the relevant test methods and data reduction schemes are outlined along with

  17. Transport properties of LiF under strong compression: modeling using advanced electronic structure methods and classical molecular dynamics

    Science.gov (United States)

    Mattsson, Thomas R.; Jones, Reese; Ward, Donald; Spataru, Catalin; Shulenburger, Luke; Benedict, Lorin X.

    2015-06-01

    Window materials are ubiquitous in shock physics and with high energy density drivers capable of reaching multi-Mbar pressures the use of LiF is increasing. Velocimetry and temperature measurements of a sample through a window are both influenced by the assumed index of refraction and thermal conductivity, respectively. We report on calculations of index of refraction using the many-body theory GW and thermal ionic conductivity using linear response theory and model potentials. The results are expected to increase the accuracy of a broad range of high-pressure shock- and ramp compression experiments. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  18. Phase transformation, oxidation and shape memory properties of Ti–50Au–10Zr alloy for high temperature applications

    International Nuclear Information System (INIS)

    Wadood, A.; Hosoda, H.; Yamabe-Mitarai, Y.

    2014-01-01

    Highlights: • Ti–50Au–10Zr exhibited better thermo-mechanical and shape memory properties than Ti–50Au. • Improvement was related to solid solution and precipitation strengthening. • No oxidation problem as oxidation was observed at 100 K higher than A f . • TMA was used not only for thermo-mechanical but also for shape memory and oxidation. - Abstract: In this study, we investigated the phase transformation, oxidation and high temperature mechanical and shape memory properties of Ti–50Au–10Zr (all compositions in atomic%) alloy. Thermo-mechanical analyzer (TMA) was used not only for phase transformation but also for the measurement of shape memory effect and oxidation behavior in air environment. Ti–50Au–10Zr exhibited lower martensitic transformation temperature of 758 K than TiAu stoichiometric alloy exhibiting 870 K since Zr addition stabilizes B2 parent phase. Oxidation was initiated at 873 K that was about 100 K higher than the austenite finish temperature, indicating no such oxidation problems for practical use. Shape memory effect was improved by partial substitution of Ti with Zr in Ti–50Au–10Zr alloy. Compression test of Ti–50Au–10Zr revealed high compressive strength of 1239 MPa of martensite at 691 K (=M f − 50 K) and 924 MPa of B2 parent phase at 834 K (=A f + 50 K) in comparison with Ti–50Au. It is concluded that Zr is effective to improve the mechanical and shape memory properties of TiAu alloy, and that Ti–50Au–10Zr shape memory alloy has potential for high temperature (∼650–850 K) practical applications

  19. Finite-Temperature Properties of Three-Dimensional Chiral Helimagnets

    Science.gov (United States)

    Shinozaki, Misako; Hoshino, Shintaro; Masaki, Yusuke; Kishine, Jun-ichiro; Kato, Yusuke

    2016-07-01

    We study a three-dimensional (3d) classical chiral helimagnet at finite temperatures through analysis of a spin Hamiltonian, which is defined on a simple cubic lattice and consists of the Heisenberg exchange, monoaxial Dzyaloshinskii-Moriya interactions, and the Zeeman energy due to a magnetic field applied in the plane perpendicular to the helical axis. We take account of the quasi-two-dimensionality of the known monoaxial chiral helimagnet CrNb3S6 and we adopt three methods: (i) a conventional mean-field (MF) analysis, which we call the 3dMF method, (ii) a hybrid method called the 2dMC-1dMF method, which is composed of a classical Monte Carlo (MC) simulation and a MF approximation applied respectively to the intra- and interlayer interactions, and (iii) a simple-MC simulation (3dMC) at zero field. The temperature dependence of the magnetization calculated by the 3dMF method shows a cusp-like structure similar to that observed in experiments. In the absence of a magnetic field, both 2dMC-1dMF and 3dMC yield similar values of the transition temperature. The 2dMC-1dMF method provides a quantitative description of the thermodynamic properties, even under an external field, at an accessible numerical cost.

  20. Improving the low temperature properties of biodiesel fuel

    Energy Technology Data Exchange (ETDEWEB)

    Bhale, Purnanand Vishwanathrao; Deshpande, Nishikant V.; Thombre, Shashikant B. [Visvesvaraya National Institute of Technology, Mechanical Engineering, South Ambazari Road, Near Bajaj Nagar, 440011 Nagpur, Maharashtra (India)

    2009-03-15

    The use of biodiesel as a diesel fuel extender and lubricity improver is rapidly increasing. While most of the properties of biodiesel are comparable to petroleum based diesel fuel, improvement of its low temperature flow characteristic still remains one of the major challenges when using biodiesel as an alternative fuel for diesel engines. The biodiesel fuels derived from fats or oils with significant amounts of saturated fatty compounds will display higher cloud points and pour points. This paper is aimed to investigate the cold flow properties of 100% biodiesel fuel obtained from Madhuca indica, one of the important species in the Indian context. In this paper, the cold flow properties of biodiesel were evaluated with and without pour point depressants towards the objectives of identifying the pumping and injecting of these biodiesel in CI engines under cold climates. Effect of ethanol, kerosene and commercial additive on cold flow behavior of this biodiesel was studied. A considerable reduction in pour point has been noticed by using these cold flow improvers. The performance and emission with ethanol blended Mahua biodiesel fuel and ethanol-diesel blended Mahua biodiesel fuel have also been studied. A considerable reduction in emission was obtained. Ethanol blended biodiesel is totally a renewable, viable alternative fuel for improved cold flow behavior and better emission characteristics without affecting the engine performance. (author)

  1. Effect of the loading rate on compressive properties of goose eggs

    Czech Academy of Sciences Publication Activity Database

    Nedomová, Š.; Kumbár, V.; Trnka, Jan; Buchar, J.

    2016-01-01

    Roč. 42, č. 2 (2016), s. 223-233 ISSN 0092-0606 Institutional support: RVO:61388998 Keywords : goose egg * compression * rupture force * deformation Subject RIV: BO - Biophysics Impact factor: 1.241, year: 2016 http://download.springer.com/ static /pdf/770/art%253A10.1007%252Fs10867-015-9403-2.pdf?originUrl=http%3A%2F%2Flink.springer.com%2Farticle%2F10.1007%2Fs10867-015-9403-2&token2=exp=1460539397~acl=%2Fstatic%2Fpdf%2F770%2Fart%25253A10.1007%25252Fs10867-015-9403-2.pdf%3ForiginUrl%3Dhttp%253A%252F%252Flink.springer.com%252Farticle%252F10.1007%252Fs10867-015-9403-2*~hmac=fd2b9956908d60e519ce45c412eaf5c228f6f96333e62a06285950a2123f7739

  2. Experimental Characterization and Material Modelling of an AZ31 Magnesium Sheet Alloy at Elevated Temperatures under Consideration of the Tension-Compression Asymmetry

    Science.gov (United States)

    Behrens, B.-A.; Bouguecha, A.; Bonk, C.; Dykiert, M.

    2017-09-01

    Magnesium sheet alloys have a great potential as a construction material in the aerospace and automotive industry. However, the current state of research regarding temperature dependent material parameters for the description of the plastic behaviour of magnesium sheet alloys is scarce in literature and accurate statements concerning yield criteria and appropriate characterization tests to describe the plastic behaviour of a magnesium sheet alloy at elevated temperatures in deep drawing processes are to define. Hence, in this paper the plastic behaviour of the well-established magnesium sheet alloy AZ31 has been characterized by means of convenient mechanical tests (e. g. tension, compression and biaxial tests) at temperatures between 180 and 230 °C. In this manner, anisotropic and hardening behaviour as well as differences between the tension-compression asymmetry of the yield locus have been estimated. Furthermore, using the evaluated data from the above mentioned tests, two different yield criteria have been parametrized; the commonly used Hill’48 and an orthotropic yield criterion, CPB2006, which was developed especially for materials with hexagonal close packed lattice structure and is able to describe an asymmetrical yielding behaviour regarding tensile and compressive stress states. Numerical simulations have been finally carried out with both yield functions in order to assess the accuracy of the material models.

  3. Application of a two-dimensional model for predicting the pressure-flow and compression properties during column packing scale-up.

    Science.gov (United States)

    McCue, Justin T; Cecchini, Douglas; Chu, Cathy; Liu, Wei-Han; Spann, Andrew

    2007-03-23

    A two-dimensional model was formulated to describe the pressure-flow behavior of compressible stationary phases for protein chromatography at different temperatures and column scales. The model was based on the assumption of elastic deformation of the solid phase and steady-state Darcy flow. Using a single fitted value for the empirical modulus parameters, the model was applied to describe the pressure-flow behavior of several adsorbents packed using both fluid flow and mechanical compression. Simulations were in agreement with experimental data and accurately predicted the pressure-flow and compression behavior of three adsorbents over a range of column scales and operating temperatures. Use of the described theoretical model potentially improves the accuracy of the column scale-up process, allowing the use of limited laboratory scale data to predict column performance in large scale applications.

  4. Effect of alkyl chain length and temperature on the thermodynamic properties of ionic liquids 1-alkyl-3-methylimidazolium bromide in aqueous and non-aqueous solutions at different temperatures

    International Nuclear Information System (INIS)

    Sadeghi, Rahmat; Shekaari, Hemayat; Hosseini, Rahim

    2009-01-01

    The alkyl chain length of 1-alkyl-3-methylimidazolium bromide ([Rmim][Br], R = propyl (C 3 ), hexyl (C 6 ), heptyl (C 7 ), and octyl (C 8 )) was varied to prepare a series of room-temperature ionic liquids (RTILs), and experimental measurements of density and speed of sound at different temperatures ranging from (288.15 to 308.15) K for their aqueous and methanolic solutions in the dilute concentration region (0.01 to 0.30) mol . kg -1 were taken. The values of the compressibilities, expansivity and apparent molar properties for [C n mim][Br] in aqueous and methanolic solutions were determined at the investigated temperatures. The obtained apparent molar volumes and apparent molar isentropic compressibilities were fitted to the Redlich-Mayer and the Pitzer's equations from which the corresponding infinite dilution molar properties were obtained. The values of the infinite dilution molar properties were used to obtain some information about solute-solvent and solute-solute interactions. The thermodynamic properties of investigated ionic liquids in aqueous solutions have been compared with those in methanolic solutions. Also, the comparison between thermodynamic properties of investigated solutions and those of electrolyte solutions, polymer solutions, cationic surfactant solutions and tetraalkylammonium salt solutions have been made

  5. The study of some physical properties of high temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, Atif Mahmoud

    2008-07-01

    The phenomenon of superconductivity, the discovery of high temperature superconductivity in the Cuprates and the properties of these materials is described in the introductory chapter. It also includes a discussion of the pseudogap, which has remained a mystery as has the high transition temperature. Possible applications of high temperature superconductivity are reviewed before the theories by Bardeen, Cooper, and Schrieffer (BCS) and Ginzburg and Landau are briefly sketched. The last section gives excerpts of the by now vast literature on this subject, focussing on the role impurities play in this context. The second chapter develops the mathematical tools and the theoretical background for the description of many-body systems. Various Green's functions are introduced which are then used to describe scattering of quasiparticles off defects of arbitrary strength. They are also required to calculate the a.c. conductivity, for which an expression is derived using linear response theory. The convergence problems one encounters when actually calculating the conductivity are briefly discussed. Detailed calculations for the normal state are presented in the third chapter and in the appendix. The third Chapter begins with a detailed presentation of the tight binding model for the energy dispersion because this model appears to give a more accurate description of the electronic properties of high temperature superconductors than the nearly free electron model. The shape of the two-dimensional Fermi surface is calculated and displayed as function of band filling and the next-nearest neighbor hopping integral B, assuming a rigid band. B plays an important role in the formation of so-called hot spots. The quasiparticle density of states and its Hilbert transform F({omega}) are solved by means of complete elliptic integrals formalism. These results are used to obtain impurity bound states. A simple model for the superconductivity in the cuprate materials is developed on

  6. The study of some physical properties of high temperature superconductors

    International Nuclear Information System (INIS)

    Ismail, Atif Mahmoud

    2008-01-01

    The phenomenon of superconductivity, the discovery of high temperature superconductivity in the Cuprates and the properties of these materials is described in the introductory chapter. It also includes a discussion of the pseudogap, which has remained a mystery as has the high transition temperature. Possible applications of high temperature superconductivity are reviewed before the theories by Bardeen, Cooper, and Schrieffer (BCS) and Ginzburg and Landau are briefly sketched. The last section gives excerpts of the by now vast literature on this subject, focussing on the role impurities play in this context. The second chapter develops the mathematical tools and the theoretical background for the description of many-body systems. Various Green's functions are introduced which are then used to describe scattering of quasiparticles off defects of arbitrary strength. They are also required to calculate the a.c. conductivity, for which an expression is derived using linear response theory. The convergence problems one encounters when actually calculating the conductivity are briefly discussed. Detailed calculations for the normal state are presented in the third chapter and in the appendix. The third Chapter begins with a detailed presentation of the tight binding model for the energy dispersion because this model appears to give a more accurate description of the electronic properties of high temperature superconductors than the nearly free electron model. The shape of the two-dimensional Fermi surface is calculated and displayed as function of band filling and the next-nearest neighbor hopping integral B, assuming a rigid band. B plays an important role in the formation of so-called hot spots. The quasiparticle density of states and its Hilbert transform F(ω) are solved by means of complete elliptic integrals formalism. These results are used to obtain impurity bound states. A simple model for the superconductivity in the cuprate materials is developed on the basis

  7. Compressive properties of commercially available polyurethane foams as mechanical models for osteoporotic human cancellous bone

    Directory of Open Access Journals (Sweden)

    Shepherd Duncan ET

    2008-10-01

    Full Text Available Abstract Background Polyurethane (PU foam is widely used as a model for cancellous bone. The higher density foams are used as standard biomechanical test materials, but none of the low density PU foams are universally accepted as models for osteoporotic (OP bone. The aim of this study was to determine whether low density PU foam might be suitable for mimicking human OP cancellous bone. Methods Quasi-static compression tests were performed on PU foam cylinders of different lengths (3.9 and 7.7 mm and of different densities (0.09, 0.16 and 0.32 g.cm-3, to determine the Young's modulus, yield strength and energy absorbed to yield. Results Young's modulus values were 0.08–0.93 MPa for the 0.09 g.cm-3 foam and from 15.1–151.4 MPa for the 0.16 and 0.32 g.cm-3 foam. Yield strength values were 0.01–0.07 MPa for the 0.09 g.cm-3 foam and from 0.9–4.5 MPa for the 0.16 and 0.32 g.cm-3 foam. The energy absorbed to yield was found to be negligible for all foam cylinders. Conclusion Based on these results, it is concluded that 0.16 g.cm-3 PU foam may prove to be suitable as an OP cancellous bone model when fracture stress, but not energy dissipation, is of concern.

  8. Band and percolation approaches to low temperature properties of manganites

    Energy Technology Data Exchange (ETDEWEB)

    Gor' kov, L.P. (Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. L.D. Landau Inst. for Theoretical Physics (Russian Federation)); Kresin, V.Z. (Lawrence Berkeley Lab., CA (United States))

    1998-12-20

    Properties of the parent compound, LaMnO[sub 3] are greatly affected by strong Hund's coupling. Assuming the antiferromagnetic ordering (with a low Neel temperature) along one of the cubic axes, this coupling would result in formation of disconnected ferromagnetic layers. Furthermore, in the presence of the cooperative Jahn-Teller effect the compound becomes a band insulator. At small doping (La[sub 1[minus]x]Ca[sub x]MnO[sub 3], x [much lt] 1) the band insulator phase coexists with the presence of localized holes. An insulator-ferromagnetic metal transition occurs at the percolation point x[sub c] = 0.16.

  9. Low temperature properties of the magnetic semiconductor TmTe

    International Nuclear Information System (INIS)

    Matsumura, Takeshi; Nakamura, Shintaro; Goto, Terutaka; Amitsuka, Hiroshi; Matsuhira, Kazuyuki; Sakakibara; Toshiro; Suzuki, Takashi

    1998-01-01

    The magnetic susceptibility, elastic constant, specific heat and magnetization of the magnetic semiconductor TmTe have been measured in detail. A phase transition which is likely to be an antiferro quadrupolar ordering was found to occur at 1.8 K. The specific heat measurements under magnetic fields along the three main crystal axes revealed the unusual characters of this phase transition. The (H-T) phase diagram below 5 T is very similar to that of the antiferro quadrupolar ordering in CeB 6 . Above 5 T, however, the phase line for H parallels (100) begins to close toward T = 0 K. The physical properties in the paramagnetic region at high temperatures are discussed in the mean field approximation. The theoretical fitting of the elastic softening indicates the antiferro inter-ionic quadrupolar interactions. However, the mean field theory can not explain the specific heat results. (author). 50 refs

  10. Devitrification and high temperature properties of mineral wool

    DEFF Research Database (Denmark)

    Nielsen, Eva Ravn; Augustesen, Maria; Ståhl, Kenny

    2007-01-01

    Mineral wool products can be used for thermal and acoustic insulation as well as for fire protection. The high temperature properties and the crystallization behaviour (devitrification) of the amorphous fibres during heating have been examined. Commercial stone wool and commercial hybrid wool...... (stone wool produced by a glass wool process) have been compared, as well as specially produced stone wool fibres. The fibres differed in chemical compositions and degree of oxidation given by Fe3+/Fetotal ratios. The materials were studied by thermal stability tests, X-ray diffraction, Mössbauer...... spectroscopy, secondary neutral mass spectroscopy, differential scanning calorimetry and thermal gravimetric analysis. When stone wool fibres were heated at 800 ºC in air, oxidation of Fe2+ to Fe3+ occurred simultaneously with migration of divalent cations (especially Mg2+) to the surface. Decreasing Fe3...

  11. Temperature-dependent thermal properties of Ru/C multilayers.

    Science.gov (United States)

    Yan, Shuai; Jiang, Hui; Wang, Hua; He, Yan; Li, Aiguo; Zheng, Yi; Dong, Zhaohui; Tian, Naxi

    2017-09-01

    Multilayers made of Ru/C are the most promising candidates when working in the energy region 8-20 keV. The stability of its thermal properties, including thermal expansion and thermal conduction, needs to be considered for monochromator or focusing components. Ru/C multilayers with periodic thicknesses of 3, 4 and 5 nm were investigated in situ by grazing-incidence X-ray reflectometry and diffuse scattering in order to study their thermal expansion characteristics as a function of annealing temperature up to 400°C. The thermal conductivity of multilayers with the same structure was also measured by the transient hot-wire method and compared with bulk values.

  12. Containerless high temperature property measurements by atomic fluorescence

    Science.gov (United States)

    Nordine, P. C.; Schiffman, R. A.

    1982-01-01

    Laser induced fluorescence techniques were developed for the containerless study of high temperature processes, material properties, levitation, and heating techniques for containerless earth-based experimentation. Experiments were performed in which fluorescence of atomic aluminum, mercury, or tungsten were studied. These experiments include measurements of: (1) Al atom evaporation from CW CO2 laser heated and aerodynamically levitated sapphire and alumina spheres, and self-supported sapphire filaments, (2) Al atom reaction with ambient oxygen in the wake of a levitated specimen, (3) Hg atom concentrations in the wake of levitated alumina and sapphire spheres, relative to the ambient Hg atom concentration, (4) Hg atom concentrations in supersonic levitation jets, and (5) metastable, electronically excited W atom concentrations produced by evaporation of an electrically heated tungsten filament.

  13. High Temperature Thermoelectric Properties of ZnO Based Materials

    DEFF Research Database (Denmark)

    Han, Li

    on the electron and phonon transport was analyzed and discussed in detail. In order to solve the problems of high thermal conductivity without the deterioration of electrical conductivity by nanostructuring for conventional ZnO materials, the doped ZnCdO material was proposed as a new n-type oxide thermoelectric...... material. The material is sintered in air in order to maintain the oxygen stoichiometry and avoid the stability issues. The successful alloying of CdO with ZnO at a molar ratio of 1:9 resulted in a significant reduction of thermal conductivity up to 7-fold at room temperature. By careful selection......O. Following that, the nanostructuring effect for Al-doped ZnO was systematically investigated using samples with different microstructure morphologies. At last, the newly developed ZnCdO materials with superior thermoelectric properties and thermal stability were introduced as promising substitutions...

  14. Methods for evaluating tensile and compressive properties of plastic laminates reinforced with unwoven glass fibers

    Science.gov (United States)

    Karl Romstad

    1964-01-01

    Methods of obtaining strength and elastic properties of plastic laminates reinforced with unwoven glass fibers were evaluated using the criteria of the strength values obtained and the failure characteristics observed. Variables investigated were specimen configuration and the manner of supporting and loading the specimens. Results of this investigation indicate that...

  15. TABLETING PROPERTIES OF EXPERIMENTAL AND COMMERCIALLY AVAILABLE LACTOSE GRANULATIONS FOR DIRECT COMPRESSION

    NARCIS (Netherlands)

    BOLHUIS, GK; ZUURMAN, K

    1995-01-01

    Lactose granulations (125-250 mu m) were prepared from two different alpha-lactose monohydrate powders and one roller dried beta-lactose powder respectively, by wet granulation with only water as a binder. As an effect of the granulation process, the flow properties improved, but the compactibility

  16. Effect of compression pressure on mechanical and electrical properties of polyaniline pellets

    Czech Academy of Sciences Publication Activity Database

    Valentová, H.; Prokeš, J.; Nedbal, J.; Stejskal, Jaroslav

    2013-01-01

    Roč. 67, č. 8 (2013), s. 1109-1112 ISSN 0366-6352 R&D Projects: GA TA ČR TE01020022 Institutional support: RVO:61389013 Keywords : conducting polymer * hardness * mechanical properties Subject RIV: CG - Electrochemistry Impact factor: 1.193, year: 2013

  17. Engineered particles demonstrate improved flow properties at elevated drug loadings for direct compression manufacturing.

    Science.gov (United States)

    Trementozzi, Andrea N; Leung, Cheuk-Yui; Osei-Yeboah, Frederick; Irdam, Erwin; Lin, Yiqing; MacPhee, J Michael; Boulas, Pierre; Karki, Shyam B; Zawaneh, Peter N

    2017-05-15

    Optimizing powder flow and compaction properties are critical for ensuring a robust tablet manufacturing process. The impact of flow and compaction properties of the active pharmaceutical ingredient (API) becomes progressively significant for higher drug load formulations, and for scaling up manufacturing processes. This study demonstrated that flow properties of a powder blend can be improved through API particle engineering, without critically impacting blend tabletability at elevated drug loadings. In studying a jet milled API (D 50 =24μm) and particle engineered wet milled API (D 50 =70μm and 90μm), flow functions of all API lots were similarly poor despite the vast difference in average particle size (ff c 10) compared with the jet milled API blends. Investigation of the compaction properties of both wet and jet milled powder blends also revealed that both jet and wet milled material produced robust tablets at the drug loadings used. The ability to practically demonstrate this uncommon observation that similarly poor flowing APIs can lead to a marked difference upon blending is important for pharmaceutical development. It is especially important in early phase development during API selection, and is advantageous particularly when material-sparing techniques are utilized. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Simultaneous Retrieval of Temperature, Water Vapor and Ozone Atmospheric Profiles from IASI: Compression, De-noising, First Guess Retrieval and Inversion Algorithms

    Science.gov (United States)

    Aires, F.; Rossow, W. B.; Scott, N. A.; Chedin, A.; Hansen, James E. (Technical Monitor)

    2001-01-01

    A fast temperature water vapor and ozone atmospheric profile retrieval algorithm is developed for the high spectral resolution Infrared Atmospheric Sounding Interferometer (IASI) space-borne instrument. Compression and de-noising of IASI observations are performed using Principal Component Analysis. This preprocessing methodology also allows, for a fast pattern recognition in a climatological data set to obtain a first guess. Then, a neural network using first guess information is developed to retrieve simultaneously temperature, water vapor and ozone atmospheric profiles. The performance of the resulting fast and accurate inverse model is evaluated with a large diversified data set of radiosondes atmospheres including rare events.

  19. New graphite/salt materials for high temperature energy storage. Phase change properties study

    International Nuclear Information System (INIS)

    Lopez, J.

    2007-07-01

    This work is a contribution to the study of new graphite/salt composites dedicated to high temperature energy storage (≥200 C). The aim is to analyse and to understand the influence of both graphite and composite microstructure on the phase change properties of salts. This PhD is carried out within the framework of two projects: DISTOR (European) and HTPSTOCK (French). The major contributions of this work are threefold: 1) An important database (solid-liquid phase change properties) is provided from the DSC analysis of six salts and the corresponding composites. 2) Rigorous modeling of salts melting in confined media in several geometries are proposed to understand why, during the first melting of the compression elaborated composites, problems of salt leakage are observed. These models show that the materials morphology is responsible for these phenomena: the graphite matrix restrains the volume expansion due to salt melting: salt melts under pressure, which leads to a melting on a large temperature range and to a loss of energy density. Sensitivity analysis of parameters (geometric and physic) shows that matrix rigidity modulus is the parameter on which it is necessary to act during the composites elaboration to blur this phenomenon. 3) Finally, this work proposes a thermodynamic formulation of both surface/interface phenomena and the presence of dissolved impurities being able to explain a melting point lowering. It seems that the melting point lowering observed (∼ 5 C) are mainly due to the presence of dissolved impurities (brought by graphite) in the liquid, along with an additional Gibbs-Thomson effect (∼ 1 C, related to the size of the clusters crystals). (author)

  20. Reactive Spark Plasma Sintering and Mechanical Properties of Zirconium Diboride–Titanium Diboride Ultrahigh Temperature Ceramic Solid Solutions

    Directory of Open Access Journals (Sweden)

    Karthiselva N. S.

    2016-09-01

    Full Text Available Ultrahigh temperature ceramics (UHTCs such as diborides of zirconium, hafnium tantalum and their composites are considered to be the candidate materials for thermal protection systems of hypersonic vehicles due to their exceptional combination of physical, chemical and mechanical properties. A composite of ZrB2-TiB2 is expected to have better properties. In this study, an attempt has been made to fabricate ZrB2-TiB2 ceramics using mechanically activated elemental powders followed by reactive spark plasma sintering (RSPS at 1400 °C. Microstructure and phase analysis was carried out using X-ray diffractometer (XRD and electron microscopy to understand microstructure evolution. Fracture toughness and hardness were evaluated using indentation methods. Nanoindentation was used to measure elastic modulus. Compressive strength of the composites has been reported.

  1. Chemical and Thermodynamic Properties at High Temperatures: A Symposium

    Science.gov (United States)

    Walker, Raymond F.

    1961-01-01

    This book contains the program and all available abstracts of the 90' invited and contributed papers to be presented at the TUPAC Symposium on Chemical and Thermodynamic Properties at High Temperatures. The Symposium will be held in conjunction with the XVIIIth IUPAC Congress, Montreal, August 6 - 12, 1961. It has been organized, by the Subcommissions on Condensed States and on Gaseous States of the Commission on High Temperatures and Refractories and by the Subcommission on Experimental Thermodynamics of the Commission on Chemical Thermodynamics, acting in conjunction with the Organizing Committee of the IUPAC Congress. All inquiries concerning participation In the Symposium should be directed to: Secretary, XVIIIth International Congress of Pure and Applied Chemistry, National Research Council, Ottawa, 'Canada. Owing to the limited time and facilities available for the preparation and printing of the book, it has not been possible to refer the proofs of the abstracts to the authors for checking. Furthermore, it has not been possible to subject the manuscripts to a very thorough editorial examination. Some obvious errors in the manuscripts have been corrected; other errors undoubtedly have been introduced. Figures have been redrawn only when such a step was essential for reproduction purposes. Sincere apologies are offered to authors and readers for any errors which remain; however, in the circumstances neither the IUPAC Commissions who organized the Symposium, nor the U. S. Government Agencies who assisted in the preparation of this book can accept responsibility for the errors.

  2. Ulta-Low Temperature Properties of Amorphous and Glassy Materials

    Energy Technology Data Exchange (ETDEWEB)

    Douglas D. Osheroff

    2013-01-10

    During the grant period we made detailed studies of the dynamics of two level tunneling systems in glasses at very low temperature and by the application of AC and DC electric fields. Models have been developed that now account for both the formation and subsequent breaking of resonant tunneling pairs, and strongly bound pairs in a swept electric field. Perhaps most importantly, we saw a critical field in the polymeric glass Mylar, beyond which recovery following the application of a strong electric field is substantially modified from the predictions of current models. It was essential during the final grant period to see how general these new properties were by testing for them in a new and broader set of glasses. At the same time, the discovery that tunneling systems with nuclei possessing electric quadrupole moments that couple the TS behavior to magnetic fields was studied in this laboratory, using some of the probes that we alone employ. Finally, we were developing our own dielectric pulsed echo system, operating for the first time at the low energy splittings and hence temperatures at which interactions between TS are important. We combined this technique with the sudden application of both electric and strain fields to better understand the dynamics of the response of TS in glasses on a much shorter time scale than is possible with our established probes.

  3. Changes of microstructures and high temperature properties during high temperature service of Niobium added ferritic stainless steels

    International Nuclear Information System (INIS)

    Fujita, Nobuhiro; Ohmura, Keiichi; Yamamoto, Akio

    2003-01-01

    To improve the fuel economy and clean the exhaust gas of automobiles, the temperature of exhaust gas is getting higher and higher. Niobium added ferritic stainless steels are often being used in automotive exhaust systems, because of their excellent heat resistant properties, especially thermal fatigue resistance, which is very important for materials of exhaust manifold. However, coarse precipitates containing niobium, which cause degradation in high temperature strength and thermal fatigue resistance, are unavoidable during high temperature service. In this study, changes of microstructures and high temperature properties in high temperature aging were investigated using several Nb added ferritic stainless steels. It has been found that the microstructure stability of Nb-Ti-Mo alloyed steels in high temperature aging is superior to that of Nb added steels. The microstructure stability leads to less degradation in high temperature strength during high temperature aging and to longer thermal fatigue lives of Nb-Ti-Mo alloyed steels than in Nb added steels

  4. Properties of concrete containing different type of waste materials as aggregate replacement exposed to elevated temperature – A review

    Science.gov (United States)

    Ghadzali, N. S.; Ibrahim, M. H. W.; Sani, M. S. H. Mohd; Jamaludin, N.; Desa, M. S. M.; Misri, Z.

    2018-04-01

    Concrete is the chief material of construction and it is non-combustible in nature. However, the exposure to the high temperature such as fire can lead to change in the concrete properties. Due to the higher temperature, several changes in terms of mechanical properties were observed in concrete such as compressive strength, modulus of elasticity, tensile strength and durability of concrete will decrease significantly at high temperature. The exceptional fire-proof achievement of concrete is might be due to the constituent materials of concrete such as its aggregates. The extensive use of aggregate in concrete will leads to depletion of natural resources. Hence, the use of waste and other recycled and by-product material as aggregates replacements becomes a leading research. This review has been made on the utilization of waste materials in concrete and critically evaluates its effects on the concrete performances during the fire exposure. Therefore, the objective of this paper is to review the previous search work regarding the concrete containing waste material as aggregates replacement when exposed to elevated temperature and come up with different design recommendations to improve the fire resistance of structures.

  5. Medical history of optic chiasm compression in patients with pituitary insufficiency affects skin temperature and its relation to sleep

    NARCIS (Netherlands)

    Romeijn, N.; Borgers, A.J.F.; Fliers, E.; Alkemade, A.; Bisschop, P.H.; Van Someren, E.J.

    2012-01-01

    The hypothalamus is crucially involved in the circadian timing of the sleep-wake rhythm, yet also accommodates the most important thermoregulatory neuronal network. We have shown before that adults with pituitary insufficiency and history of chiasm compression due to a tumor with suprasellar

  6. Medical History of Optic Chiasm Compression in Patients With Pituitary Insufficiency Affects Skin Temperature and Its Relation to Sleep

    NARCIS (Netherlands)

    Romeijn, N.; Borgers, A.J.; Fliers, E.; Alkemade, A.; Bisschop, P.H.; van Someren, E.J.W.

    2012-01-01

    The hypothalamus is crucially involved in the circadian timing of the sleep-wake rhythm, yet also accommodates the most important thermoregulatory neuronal network. We have shown before that adults with pituitary insufficiency and history of chiasm compression due to a tumor with suprasellar

  7. Microstructure Evolution and High-Temperature Compressibility of Modified Two-Step Strain-Induced Melt Activation-Processed Al-Mg-Si Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Chia-Wei Lin

    2016-05-01

    Full Text Available A two-step strain-induced melt activation (TS-SIMA process that omits the cold working step of the traditional strain-induced melt activation (SIMA process is proposed for 6066 Al-Mg-Si alloy to obtain fine, globular, and uniform grains with a short-duration salt bath. The results show that increasing the salt bath temperature and duration leads to a high liquid phase fraction and a high degree of spheroidization. However, an excessive salt bath temperature leads to rapid grain growth and generates melting voids. The initial degree of dynamic recrystallization, which depends on the extrusion ratio, affects the globular grain size. With an increasing extrusion ratio, the dynamic recrystallization becomes more severe and the dynamic recrystallized grain size becomes smaller. It results in the globular grains becomes smaller. The major growth mechanism of globular grains is Ostwald ripening. Furthermore, high-temperature compressibility can be improved by the TS-SIMA process. After a 4 min salt bath at 620 °C, the high-temperature compression ratio become higher than that of a fully annealed alloy. The results show that the proposed TS-SIMA process has great potential.

  8. Effect of compressive deformation on thermal and corrosive properties of Zr61.7Al8Ni13Cu17Sn0.3 bulk metallic glass

    Science.gov (United States)

    Xu, Yuanli; Shi, Bo

    2018-03-01

    The effect of compressive deformation on thermal stability and corrosive property of Zr61.7Al8Ni13Cu17Sn0.3 bulk metallic glass with a strain of 80% was investigated in this work. The corresponding thermal stability is found to decrease after deformation and this can probably be attributed to the reduction of the viscosity and the increase of the Gibbs free energy after compressive deformation. In addition, the corrosion current density increases and this suggests that the corrosion resistance decreases for the deformed sample in comparison with the as-cast sample.

  9. Rheological Properties with Temperature Response Characteristics and a Mechanism of Solid-Free Polymer Drilling Fluid at Low Temperatures

    Directory of Open Access Journals (Sweden)

    Sheng Wang

    2016-12-01

    Full Text Available The rheological properties of drilling fluid have important effects during drilling in natural gas hydrate at low temperatures. The present study was performed using theoretical analysis. Experiments and micro-analyses were carried out to determine the rheological properties with temperature response characteristics and the mechanism involved in solid-free polymer drilling fluid (SFPDF at low temperatures when drilling in permafrost with natural gas hydrates (NGH. The curves of shear stress with the shear rates of three kinds of polymer drilling fluids, Semen Lepidii natural vegetable gum, polyacrylamide, and xanthan gum, were drawn. Then, statistical and related analyses of test data were performed using Matlab ver. 8.0. Through regression analysis, the Herschel–Bulkley model was used to characterize the rheological characteristics of SFPDF. On this basis, the laws regarding the rheological properties of the three kinds of SFPDF under changing temperatures were analyzed and rheological properties with temperature response state equations were established. Next, the findings of previous studies on rheological properties with temperature response characteristics of the SFPDF were reviewed. Finally, the rheological properties with temperature response mechanisms were assessed using scanning electron microscopy and infrared spectrum analysis.

  10. Physical properties of dense, low-temperature plasmas

    International Nuclear Information System (INIS)

    Redmer, R.

    1997-01-01

    Plasmas occur in a wide range of the density-temperature plane. The physical quantities can be expressed by Green's functions which are evaluated by means of standard quantum statistical methods. The influences of many-particle effects such as dynamic screening and self-energy, structure factor and local-field corrections, formation and decay of bound states, degeneracy and Pauli exclusion principle are studied. As a basic concept for partially ionized plasmas, a cluster decomposition is performed for the self-energy as well as for the polarization function. The general model of a partially ionized plasma interpolates between low-density, nonmetallic systems such as atomic vapors and high-density, conducting systems such as metals or fully ionized plasmas. The equations of state, including the location of the critical point and the shape of the coexistence curve, are determined for expanded alkali-atom and mercury fluids. The occurrence of a metal-nonmetal transition near the critical point of the liquid-vapor phase transition leads in these materials to characteristic deviations from the behavior of nonconducting fluids such as the inert gases. Therefore, a unified approach is needed to describe the drastic changes of the electronic properties as well as the variation of the physical properties with the density. Similar results are obtained for the hypothetical plasma phase transition in hydrogen plasma. The transport coefficients (electrical and thermal conductivity, thermopower) are studied wthin linear response theory given here in the formulation of Zubarev which is valid for arbitrary degeneracy and yields the transport coefficients for the limiting cases of nondegenerate, weakly coupled plasmas (Spitzer theory) as well as degenerate, strongly coupled plasmas (Ziman theory). mercury within the MHNC scheme via effective ion-ion potentials which are derived from the polarization function within an extended RPA. The optical properties of dense plasmas, the shift

  11. The first-principles calculations for the elastic properties of Zr2Al under compression

    International Nuclear Information System (INIS)

    Yuan Xiaoli; Wei Dongqing; Chen Xiangrong; Zhang Qingming; Gong Zizheng

    2011-01-01

    Graphical abstract: The calculated elastic constants C ij as a function of pressure P. Display Omitted Research highlights: → It is found that the five independent elastic constants increase monotonically with pressure. C 11 and C 33 vary rapidly as pressure increases, C 13 and C 12 becomes moderate. However, C 44 increases comparatively slowly with pressure. Figure shows excellent satisfaction of the calculated elastic constants of Zr 2 Al to these equations and hence in our calculation, the Zr 2 Al is mechanically stable at pressure up to 100 GPa. - Abstract: The first-principles calculations were applied to investigate the structural, elastic constants of Zr 2 Al alloy with increasing pressure. These properties are based on the plane wave pseudopotential density functional theory (DFT) method within the generalized gradient approximation (GGA) for exchange and correlation. The result of the heat of formation of Zr 2 Al crystal investigated is in excellent consistent with results from other study. The anisotropy, the shear modulus, and Young's modulus for the ideal polycrystalline Zr 2 Al are also studied. It is found that (higher) pressure can significantly improve the ductility of Zr 2 Al. Moreover, the elastic constants of Zr 2 Al increase monotonically and the anisotropies decrease with the increasing pressure. Finally, it is observed that Zr d electrons are mainly contributed to the density of states at the Fermi level.

  12. Factorial Study of Compressive Mechanical Properties and Primary In Vitro Osteoblast Response of PHBV/PLLA Scaffolds

    Directory of Open Access Journals (Sweden)

    Naznin Sultana

    2012-01-01

    Full Text Available For bone tissue regeneration, composite scaffolds containing biodegradable polymers and nanosized osteoconductive bioceramics have been regarded as promising biomimetic systems. Polymer blends of poly(hydroxybutyrate-co-hydroxyvalerate (PHBV and poly(L-lactic acid (PLLA can be used as the polymer matrix to control the degradation rate. In order to render the scaffolds osteoconductive, nano-sized hydroxyapatite (nHA particles can be incorporated into the polymer matrix. In the first part of this study, a factorial design approach to investigate the influence of materials on the initial compressive mechanical properties of the scaffolds was studied. In the second part, the protein adsorption behavior and the attachment and morphology of osteoblast-like cells (Saos-2 of the scaffolds in vitro were also studied. It was observed that nHA incorporated PHBV/PLLA composite scaffolds adsorbed more bovine serum albumin (BSA protein than PHBV or PHBV/PLLA scaffolds. In vitro studies also revealed that the attachment of human osteoblastic cells (SaOS-2 was significantly higher in nHA incorporated PHBV/PLLA composite scaffolds. From the SEM micrographs of nHA incorporated PHBV/PLLA composite scaffolds seeded with SaOS-2 cells after a 7-day cell culture period, it was observed that the cells were well expanded and spread in all directions on the scaffolds.

  13. Effects of glass fiber mesh with different fiber content and structures on the compressive properties of complete dentures.

    Science.gov (United States)

    Yu, Sang-Hui; Cho, Hye-Won; Oh, Seunghan; Bae, Ji-Myung

    2015-06-01

    No study has yet evaluated the strength of complete dentures reinforced with glass fiber meshes with different content and structures. The purpose of this study was to compare the reinforcing effects of glass fiber mesh with different content and structures with that of metal mesh in complete dentures. Two types of glass fiber mesh were used: SES mesh (SES) and glass cloth (GC2, GC3, and GC4). A metal mesh was used for comparison. The complete dentures were made by placing the reinforcement 1 mm away from the tissue surface. A control group was prepared without any reinforcement (n=10). The compressive properties were measured by a universal testing machine at a crosshead speed of 5 mm/min. The results were analyzed with the Kruskal-Wallis test and the Duncan multiple range test (α=.05). The fracture resistance of the SES group was significantly higher than that of the control, GC4, and metal groups (asymptotic P=.004), but not significantly different from the GC2 and GC3 groups. The toughness of the SES and GC3 groups was significantly higher than that of the others (asymptotic Pglass fiber mesh seemed more important than the structures. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  14. Industrially benign super-compressible piezoresistive carbon foams with predefined wetting properties: from environmental to electrical applications.

    Science.gov (United States)

    Pham, Tung Ngoc; Samikannu, Ajaikumar; Kukkola, Jarmo; Rautio, Anne-Riikka; Pitkänen, Olli; Dombovari, Aron; Lorite, Gabriela Simone; Sipola, Teemu; Toth, Geza; Mohl, Melinda; Mikkola, Jyri-Pekka; Kordas, Krisztian

    2014-11-06

    In the present work electrically conductive, flexible, lightweight carbon sponge materials derived from open-pore structure melamine foams are studied and explored. Hydrophobic and hydrophilic surface properties - depending on the chosen treatment conditions - allow the separation and storage of liquid chemical compounds. Activation of the carbonaceous structures substantially increases the specific surface area from ~4 m(2)g(-1) to ~345 m(2)g(-1), while retaining the original three-dimensional, open-pore structure suitable for hosting, for example, Ni catalyst nanoparticles. In turn the structure is rendered suitable for hydrogenating acetone to 2-propanol and methyl isobutyl ketone as well for growing hierarchical carbon nanotube structures used as electric double-layer capacitor electrodes with specific capacitance of ~40 F/g. Mechanical stress-strain analysis indicates the materials are super-compressible (>70% volume reduction) and viscoelastic with excellent damping behavior (loss of 0.69 ± 0.07), while piezoresistive measurements show very high gauge factors (from ~20 to 50) over a large range of deformations. The cost-effective, robust and scalable synthesis - in conjunction with their fascinating multifunctional utility - makes the demonstrated carbon foams remarkable competitors with other three-dimensional carbon materials typically based on pyrolyzed biopolymers or on covalently bonded graphene and carbon nanotube frameworks.

  15. "Compressed" Compressed Sensing

    OpenAIRE

    Reeves, Galen; Gastpar, Michael

    2010-01-01

    The field of compressed sensing has shown that a sparse but otherwise arbitrary vector can be recovered exactly from a small number of randomly constructed linear projections (or samples). The question addressed in this paper is whether an even smaller number of samples is sufficient when there exists prior knowledge about the distribution of the unknown vector, or when only partial recovery is needed. An information-theoretic lower bound with connections to free probability theory and an upp...

  16. The dynamic compressive behavior and constitutive modeling of D1 railway wheel steel over a wide range of strain rates and temperatures

    Directory of Open Access Journals (Sweden)

    Lin Jing

    Full Text Available The dynamic compressive behavior of D1 railway wheel steel at high strain rates was investigated using a split Hopkinson pressure bar (SHPB apparatus. Three types of specimens, which were derived from the different positions (i.e., the rim, web and hub of a railway wheel, were tested over a wide range of strain rates from 10−3 s−1 to 2.4 × 103 s−1 and temperatures from 213 K to 973 K. Influences of the strain rate and temperature on flow stress were discussed, and rate- and temperature-dependent constitutive relationships were assessed by the Cowper-Symonds model, Johnson-Cook model and a physically-based model, respectively. The experimental results show that the compressive true stress versus true strain response of D1 wheel steel is strain rate-dependent, and the strain hardening rate during the plastic flow stage decreases with the elevation of strain rate. Besides, the D1 wheel steel displays obvious temperature-dependence, and the third-type strain aging (3rd SA is occurred at the temperature region of 673–973 K at a strain rate of ∼1500 s−1. Comparisons of experimental results with theoretical predictions indicate that the physically-based model has a better prediction capability for the 3rd SA characteristic of the tested D1 wheel steel. Keywords: Railway wheel steel, SHPB, Strain rate, Temperature effect, Strain aging

  17. A novel highly porous ceramic foam with efficient thermal insulation and high temperature resistance properties fabricated by gel-casting process

    Science.gov (United States)

    Yu, Jiahong; Wang, Guixiang; Tang, Di; Qiu, Ya; Sun, Nali; Liu, Wenqiao

    2018-01-01

    The design of super thermal insulation and high-temperature resistant materials for high temperature furnaces is crucial due to the energy crisis and the huge wasting. Although it is told that numerous studies have been reported about various of thermal insulation materials prepared by different methods, the applications of yttria-stabilized zirconia (YSZ) ceramic foams fabricated through tert-butyl alcohol (TBA)-based gel-casting process in bulk thermal isolators were barely to seen. In this paper, highly porous yttria-stabilized zirconia (YSZ) ceramic foams were fabricated by a novel gel-casting method using tert-butyl alcohol (TBA) as solvent and pore-forming agent. Different raw material ratio, sintering temperature and soaking time were all investigated to achieve optimal thermal insulation and mechanical properties. We can conclude that porosity drops gradually while compressive strength increases significantly with the rising temperature from 1000-1500°C. With prolonged soaking time, there is no obvious change in porosity but compressive strength increases gradually. All specimens have uniformly distributed pores with average size of 0.5-2μm and show good structural stability at high temperature. The final obtained ceramic foams displayed an outstanding ultra-low thermal conductivity property with only 200.6 °C in cold surface while the hot side was 1000 °C (hold 60 min to keep thermal balance before testing) at the thickness of 10 mm.

  18. Comprehensive Characterization of Voids and Microstructure in TATB-based Explosives from 10 nm to 1 cm: Effects of Temperature Cycling and Compressive Creep

    Energy Technology Data Exchange (ETDEWEB)

    Willey, T M; Lauderbach, L; Gagliardi, F; Cunningham, B; Lorenz, K T; Lee, J I; van Buuren, T; Call, R; Landt, L; Overturf, G

    2010-02-26

    This paper outlines the characterization of voids and Microstructure in TATB-based Explosives over several orders of magnitude, from sizes on the order of 10 nm to about 1 cm. This is accomplished using ultra small angle x-ray scattering to investigate voids from a few nm to a few microns, ultra small angle neutron scattering for voids from 100 nm to 10 microns, and x-ray computed microtomography to investigate microstructure from a few microns to a few centimeters. The void distributions of LX-17 are outlined, and the microstructure of LX-17 is presented. Temperature cycling and compressive creep cause drastically different damage to the microstructure. Temperature cycling leads to a volume expansion (ratchet growth) in TATB-based explosives, and x-ray scattering techniques that are sensitive to sizes up to a few microns indicated changes to the void volume distribution that had previously accounted for most, but not all of the change in density. This paper presents the microstructural damage larger than a few microns caused by ratchet growth. Temperature cycling leads to void creation in the binder poor regions associated with the interior portion of formulated prills. Conversely, compressive creep causes characteristically different changes to microstructure; fissures form at binder-rich prill boundaries prior to mechanical failure.

  19. High-temperature compressive deformation of Si{sub 3}N{sub 4}/BN fibrous monoliths.

    Energy Technology Data Exchange (ETDEWEB)

    Routbort, J. L.

    1999-02-04

    Fibrous monolithic Si{sub 3}N{sub 4}/BN ({approx}85 vol.% Si{sub 3}N{sub 4}/15 vol.% BN) and monolithic Si{sub 3}N{sub 4} ceramics were compressed at a nearly constant strain rate ({var_epsilon}) at 1200-1400 C in N{sub 2}. The {var_epsilon} range was {approx}1 x 10{sup {minus}6} to 5 x 10{sup {minus}6} s{sup {minus}1}; the stress ({sigma}) range was 37-202 MPa. The Si{sub 3}N{sub 4} and the unidirectional fibrous monoliths that were oriented with the long axis of the Si{sub 3}N{sub 4} cells parallel to the compression direction exhibited plasticity at 1300 and 1400 C, with {var_epsilon} {proportional_to} {sigma}. A 0/90{degree} cross-ply Si{sub 3}N{sub 4}/BN laminate also exhibited significant plasticity, but it was weaker than the above-mentioned ceramics. The unidirectional fibrous monoliths that were compressed perpendicular to the cell direction fractured at {approx}50 MPa in all tests. A {+-}45{degree} laminate tested at 1300 C fractured at a stress of {approx}40 MPa. Low fracture stress correlated with shear through BN layers.

  20. Analysis of microwave heating of materials with temperature-dependent properties

    International Nuclear Information System (INIS)

    Ayappa, K.G.; Davis, H.T.; Davis, E.A.; Gordon, J.

    1991-01-01

    In this paper transient temperature profiles in multilayer slabs are predicted, by simultaneously solving Maxwell's equations with the heat conduction equation, using Galerkin-finite elements. It is assumed that the medium is homogeneous and has temperature-dependent dielectric and thermal properties. The method is illustrated with applications involving the heating of food and polymers with microwaves. The temperature dependence of dielectric properties affects the heating appreciably, as is shown by comparison with a constant property model

  1. Influence of the temperature on the dielectric properties of epoxy resins

    OpenAIRE

    Dodd, S. J.; Chalashkanov, N. M.; Fothergill, J.; Dissado, L. A.

    2010-01-01

    Electrical degradation processes in epoxy resins, such as electrical treeing, were found to be dependent on the temperature at which the experiments were carried out. Therefore, it is of considerable research interest to study the influence of temperature on the dielectric properties of the polymers and to relate the effect of temperature on these properties to the possible electrical degradation mechanisms. In this work, the dielectric properties of two different epoxy resin systems have bee...

  2. Properties of aluminum alloys tensile, creep, and fatigue data at high and low temperatures

    CERN Document Server

    1999-01-01

    This book compiles more than 300 tables listing typical average properties of a wide range of aluminum alloys. The individual test results were compiled, plotted in various ways, and analyzed. The average values from the tensile and creep tests were then normalized to the published typical room-temperature tensile properties of the respective alloys for easy comparison. This extensive project was done by Alcoa Laboratories over a period of several years. The types of data presented include: Typical Mechanical Properties of Wrought and Cast Aluminum Alloys at Various Temperatures, including tensile properties at subzero temperatures, at temperature after various holding times at the test temperature, and at room temperature after exposure at various temperatures for various holding times; creep rupture strengths for various times at various temperatures; stresses required to generate various amounts of creep in various lengths of time; rotating-beam fatigue strengths; modulus of elasticity as a function of t...

  3. High Temperature Properties of Alloys Being Considered for Design of a Concentric Canister Launcher

    National Research Council Canada - National Science Library

    Rosen, Robert

    1998-01-01

    This report describes a study to determine the high temperature mechanical properties of several titanium alloys and to compare them with properties of AISI 316L stainless steel and ASTM A387 structural steel...

  4. Effect of substrate temperature on electrical and magnetic properties ...

    Indian Academy of Sciences (India)

    . Figure 1. The temperature dependence of resistivity for LPMO films grown at different substrate temperatures (solid and open circles are the data in zero and 1 T magnetic field). The inset shows the variation of magnetoresistance with ...

  5. The Influence of Forging Temperature on Mechanical Properties of Al-V Titanium Alloys,

    Science.gov (United States)

    Titanium alloys, *Forging, Aluminum alloys, Vanadium alloys, Mechanical properties, Heat treatment, High temperature, Press forging, Quenching, Toughness, Charpy impact tests , Notch toughness, Resistance

  6. Study of the mechanical properties of stainless steel 316LN prepared by hot isostatic compression. Influence of preparation parameters

    International Nuclear Information System (INIS)

    Couturier, Raphael

    1999-01-01

    This research thesis has been performed within an R and D programme which aimed at optimising and certifying the HIP process (hot isostatic pressing) from a technological as well as metallurgical point of view. The objective has been to improve dimensional reproducibility of fabricated parts, and metallurgical properties of the dense material. Reference parts are those belonging to PWR primary circuit, and are made in cast austenitic-ferritic steel. Thus, the objective has been to show that these parts can be beneficially fabricated by powder metallurgy in austenitic grade. A mock part (a primary circuit pump wheel at the 1/2 scale) has first been fabricated by HIP, and a more complex shape generator has been designed. The author reports the determination of microstructure and mechanical characteristics of the austenitic 316LN steel produced by HIP and used to fabricate mock parts and demonstrator parts, the study of the relationship between dense material properties and fabrication parameters (temperature, pressure, consolidation time), and the analysis of the consequences of an elaboration by HIP on the 316LN steel with comparison with forged parts. After a presentation of the Powder Metallurgy elaboration technique, the author reports a bibliographical study on the precipitation at Prior Particle Boundaries (PPB), reports the study of microstructure and mechanical properties of the HIPed 316LN, and discusses the possibility of a decrease of precipitation at PPBs by adjusting powder degassing or a granulometric sorting. The last part reports the extension of the study of steel coherence to a temperature range which encompasses the primary circuit operation temperature (350 C). Resilience tests are performed as well as mechanical tests on notched axisymmetric samples. A finite element calculation of these samples allows the validation of the use of a Thomson-type model to describe the emergence of defects which are typical of a steel elaborated by powder

  7. Estimating thermodynamic properties by molecular dynamics simulations: The properties of fluids at high pressures and temperatures

    International Nuclear Information System (INIS)

    Fraser, D.G.; Refson, K.

    1992-01-01

    The molecular dynamics calculations reported above give calculated P-V-T properties for H 2 O up to 1500 K and 100 GPa, which agree remarkably well with the available experimental data. We also observe the phase transition to a crystalline, orientationally disordered cubic ice structure. No account was taken of molecular flexibility in these calculations nor of potential dissociation at high pressures as suggested by Hamman (1981). However, we note that the closest next-nearest-neighbour O-H approach remains significantly greater than the TIP4P fixed O-H bond length within the water molecule for all pressures studied. The equation of state proposed here should be useful for estimating the properties of H 2 O at up to 1500 K and 100 G Pa (1 Mbar) and is much easier to use in practice than modified Redlich Kwong equations. Extension of these methods to the studies of other fluids and of fluid mixtures at high temperatures and pressures will require good potential models for the species involved, and this is likely to involve a combination of good ab initio work and semiempirical modelling. Once developed, these models should allow robust predictions of thermodynamic properties beyond the range of the experimental data on the basis of fundamental molecular information

  8. Elastic properties

    International Nuclear Information System (INIS)

    Ledbetter, H.M.

    1983-01-01

    This chapter investigates the following five aspects of engineering-material solid-state elastic constants: general properties, interrelationships, relationships to other physical properties, changes during cooling from ambient to near-zero temperature, and near-zero-temperature behavior. Topics considered include compressibility, bulk modulus, Young's modulus, shear modulus, Poisson's ratio, Hooke's law, elastic-constant measuring methods, thermodynamic potentials, higher-order energy terms, specific heat, thermal expansivity, magnetic materials, structural phase transitions, polymers, composites, textured aggregates, and other-phenomena correlations. Some of the conclusions concerning polycrystalline elastic properties and their temperature dependence are: elastic constants are physical, not mechanical, properties which relate thermodynamically to other physical properties such as specific heat and thermal expansivity; elastic constants at low temperatures are nearly temperature independent, as required by the third law of thermodynamics; and elastic constants can be used to study directional properties of materials, such as textured aggregates and composites

  9. Compressive mechanical properties of the intraluminal thrombus in abdominal aortic aneurysms and fibrin-based thrombus mimics

    Science.gov (United States)

    Ashton, John H.; Vande Geest, Jonathan P.; Simon, Bruce R.; Haskett, Darren G.

    2010-01-01

    An intraluminal thrombus (ILT) forms in the majority of abdominal aortic aneurysms (AAAs). While the ILT has traditionally been perceived as a byproduct of aneurysmal disease, the mechanical environment within the ILT may contribute to the degeneration of the aortic wall by affecting biological events of cells embedded within the ILT. In this study, the drained secant modulus (E5 ∼ modulus at 5% strain) of ILT specimens (luminal, medial, and abluminal) procured from elective open repair was measured and compared using unconfined compression. Five groups of fibrin-based thrombus mimics were also synthesized by mixing various combinations of fibrinogen, thrombin, and calcium. Drained secant moduli were compared to determine the effect of the components' concentrations on mimic stiffness. The stiffness of the mimics was also compared to the native ILT. Preliminary data on the water content of the ILT layers and mimics was measured. It was found that the abluminal layer (E5 = 19.3 kPa) is stiffer than the medial (2.49 kPa) and luminal (1.54 kPa) layers, both of which are statistically similar. E5 of the mimics (0.63, 0.22, 0.23, 0.87, and 2.54 kPa) is dependent on the concentration of all three components: E5 decreases with a decrease in fibrinogen (60 to 20 and 20 to 15 mg/ml) and a decrease in thrombin (3 to 0.3 units/ml), and E5 increases with a decrease in calcium (0.1 to 0.01 M). E5 from two of the mimics were not statistically different than the medial and luminal layers of ILT. A thrombus mimic with similar biochemical components, structure, and mechanical properties as native ILT would provide an appropriate test medium for AAA mechanobiology studies. PMID:19058807

  10. Wide-range temperature dependences of Brillouin scattering properties in polymer optical fiber

    Science.gov (United States)

    Minakawa, Kazunari; Hayashi, Neisei; Shinohara, Yuri; Tahara, Masaki; Hosoda, Hideki; Mizuno, Yosuke; Nakamura, Kentaro

    2014-04-01

    We investigate the temperature dependences of the Brillouin scattering properties in a perfluorinated graded-index (PFGI-) polymer optical fiber (POF) in a wide temperature range from -160 to 125 °C. The temperature dependences of the Brillouin frequency shift, linewidth, and Stokes power are almost linear at lower temperature down to -160 °C while they show nonlinear dependences at higher temperature. These behaviors appear to originate from the partial glass transition of the polymer material.

  11. Effects of carbon content on high-temperature mechanical and thermal fatigue properties of high-boron austenitic steels

    Directory of Open Access Journals (Sweden)

    Xiang Chen

    2016-01-01

    Full Text Available High-temperature mechanical properties of high-boron austenitic steels (HBASs were studied at 850 °C using a dynamic thermal-mechanical simulation testing machine. In addition, the thermal fatigue properties of the alloys were investigated using the self-restraint Uddeholm thermal fatigue test, during which the alloy specimens were cycled between room temperature and 800°C. Stereomicroscopy and scanning electron microscopy were used to study the surface cracks and cross-sectional microstructure of the alloy specimens after the thermal fatigue tests. The effects of carbon content on the mechanical properties at room temperature and high-temperature as well as thermal fatigue properties of the HBASs were also studied. The experimental results show that increasing carbon content induces changes in the microstructure and mechanical properties of the HBASs. The boride phase within the HBAS matrix exhibits a round and smooth morphology, and they are distributed in a discrete manner. The hardness of the alloys increases from 239 (0.19wt.% C to 302 (0.29wt.% C and 312 HV (0.37wt.% C; the tensile yield strength at 850 °C increases from 165.1 to 190.3 and 197.1 MPa; and the compressive yield strength increases from 166.1 to 167.9 and 184.4 MPa. The results of the thermal fatigue tests (performed for 300 cycles from room temperature to 800 °C indicate that the degree of thermal fatigue of the HBAS with 0.29wt.% C (rating of 2–3 is superior to those of the alloys with 0.19wt.% (rating of 4–5 and 0.37wt.% (rating of 3–4 carbon. The main cause of this difference is the ready precipitation of M23(C,B6-type borocarbides in the alloys with high carbon content during thermal fatigue testing. The precipitation and aggregation of borocarbide particles at the grain boundaries result in the deterioration of the thermal fatigue properties of the alloys.

  12. Physical and Mechanical Properties of Composites Made with Aluminous Cement and Basalt Fibers Developed for High Temperature Application

    Directory of Open Access Journals (Sweden)

    Pavel Reiterman

    2015-01-01

    Full Text Available Present paper deals with the experimental study of the composition of refractory fiber-reinforced aluminous cement based composites and its response to gradual thermal loading. Basalt fibers were applied in doses of 0.25, 0.5, 1.0, 2.0, and 4.0% in volume. Simultaneously, binder system based on the aluminous cement was modified by fine ground ceramic powder originated from the accurate ceramic blocks production. Ceramic powder was dosed as partial replacement of used cement of 5, 10, 15, 20, and 25%. Influence of composition changes was evaluated by the results of physical and mechanical testing; compressive strength, flexural strength, bulk density, and fracture energy were determined on the different levels of temperature loading. Increased dose of basalt fibers allows reaching expected higher values of fracture energy, but with respect to results of compressive and flexural strength determination as an optimal rate of basalt fibers dose was considered 0.25% in volume. Fine ground ceramic powder application led to extensive increase of residual mechanical parameters just up to replacement of 10%. Higher replacement of aluminous cement reduced final values of bulk density but kept mechanical properties on the level of mixtures without aluminous cement replacement.

  13. Effects of intake air temperature on homogenous charge compression ignition combustion and emissions with gasoline and n-heptane

    Directory of Open Access Journals (Sweden)

    Zhang Jianyong

    2015-01-01

    Full Text Available In a port fuel injection engine, Optimized kinetic process (OKP technology is implemented to realize HCCI combustion with dual-fuel injection. The effects of intake air temperature on HCCI combustion and emissions are investigated. The results show that dual-fuel control prolongs HCCI combustion duration and improves combustion stability. Dual-fuel HCCI combustion needs lower intake air temperature than gasoline HCCI combustion, which reduces the requirements on heat management system. As intake air temperature decreases, air charge increases and maximum pressure rising rate decreases. When intake air temperature is about 55ºC, HCCI combustion becomes worse and misfire happens. In fixed dual fuel content condition, HC and CO emission decreases as intake air temperature increases. The combination of dual-fuel injection and intake air temperature control can expand operation range of HCCI combustion.

  14. 40 CFR 1065.120 - Fuel properties and fuel temperature and pressure.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Fuel properties and fuel temperature... (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.120 Fuel properties and fuel temperature and pressure. (a) Use fuels as specified in the standard-setting part, or as...

  15. Temperature dependence of electromechanical properties of PLZT x ...

    Indian Academy of Sciences (India)

    Administrator

    temperature much lower than the ferroelectric to paraelectric phase transition of the material. The same behaviour is observed for the overtones also. However, the piezoelectric response of the overtones disappears at a lower temperature than the fundamental mode. The quantity, Δfps, depends on the electromechanical.

  16. Influence on the long afterglow properties by the environmental temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wu Haoyi [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Hu Yihua, E-mail: huyh@gdut.edu.c [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Wang Yinhai; Mou Zhongfei [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

    2010-01-15

    Sr{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 2+}, Dy{sup 3+} (SMED) and Ba{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 2+}, Dy{sup 3+} (BMED) were synthesized with the solid-state reaction. The SMED shows long afterglow while the afterglow of BMED is not visible at room temperature. When the environmental temperature is 150 deg. C, the afterglow of SMED is not obvious while the BMED shows the long afterglow. The decay curves measured at different temperatures conform to this phenomenon. It ascribes to the different trap depths of different samples. The thermoluminescence (TL) curves of SMED peaks at 80 deg. C. BMED has two TL peaks peaking at about 80 and 175 deg. C respectively. The low temperature peak is weak and its density is small. The high-temperature peak reveals that one trap of BMED is deeper than the one of SMED. The afterglows of the phosphors strongly depend on the environmental temperature since the lifetime of the trapping carriers is temperature-dependence. BMED is a potential optimum long afterglow phosphor for the purpose of high-temperature application.

  17. Temperature dependence of electromechanical properties of PLZT x ...

    Indian Academy of Sciences (India)

    ... broad peak at a temperature higher than mt. The voltage constant 31 decreases and the planar coupling coefficient p remains constant up to half of the mt and then falls sharply with . Half of the mt can, therefore, be used for specifying the working temperature limit of the piezoceramics for the device applications.

  18. Effect of temperature on shelf life, chemical and microbial properties ...

    African Journals Online (AJOL)

    Cream cheese samples were analyzed to find out the effect of recommended storage temperature (4±1°C) and ambient room temperature (21±1°C) on pH, titratable acidity (% lactic acid), moisture content and microbial growth. Percent reduction in moisture content and increase in titratable acidity of cheeses were found to ...

  19. Temperature dependence of electronic transport property in ferroelectric polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, X.L.; Wang, J.L., E-mail: jlwang@mail.sitp.ac.cn; Tian, B.B.; Liu, B.L.; Zou, Y.H.; Wang, X.D.; Sun, S.; Sun, J.L., E-mail: jlsun@mail.sitp.ac.cn; Meng, X.J.; Chu, J.H.

    2014-10-15

    Highlights: • The ferroelectric polymer was fabricated by Langmuir–Blodgett method. • The electrons as the dominant injected carrier were conformed in the ferroelectric polymer films. • The leakage current conduction mechanisms in ferroelectric polymer were investigated. - Abstract: The leakage current mechanism of ferroelectric copolymer of polyvinylidene fluoride with trifluoroethylene prepared by Langmuir–Blodgett was investigated in the temperature range from 100 K to 350 K. The electron as the dominant injected carrier was observed in the ferroelectric copolymer films. The transport mechanisms in copolymer strongly depend on the temperature and applied voltage. From 100 K to 200 K, Schottky emission dominates the conduction. With temperature increasing, the Frenkel–Poole emission instead of the Schottky emission to conduct the carrier transport. When the temperature gets to 260 K, the leakage current becomes independent of temperature, and the space charge limited current conduction was observed.

  20. Fast Compression and Decompression capabilities at HPCAT, APS

    Science.gov (United States)

    Sinogeikin, S. V.

    2016-12-01

    Materials behavior and phase transformation pathways are strongly influenced by the time dependence of the driving mechanism (compression, thermal transfer, strain, irradiation, etc). While shock compression and static compression are well established techniques available for a long time, the techniques filling the compression rate gap and studying materials behavior as a function of compression rates at intermediate rates remain scarce. Recent advances in synchrotron sources, x-ray optics, fast area detectors, and sample environment control have enabled many time-resolved experimental techniques for studying materials at extreme pressure and temperature conditions. The High Pressure Collaborative Access Team (HPCAT) at the Advanced Photon Source has made a sustained effort to develop and assemble a powerful collection of high-pressure apparatus for time-resolved research and developing techniques for collecting high-quality time-resolved x-ray scattering data at compression rates intermediate between static and shock compression experiments. In this talk we will outline recently developed capabilities at HPCAT for synthesis of metastable and amorphous materials and studying properties (EOS, lattice relaxation, etc.) and phase transition mechanisms of materials using fast unidirectional and cyclic compression-decompression with variable strain rates up to extreme compression of tens of TPa per second.

  1. Apparatus and test method for characterizing the temperature regulating properties of thermal functional porous polymeric materials.

    Science.gov (United States)

    Yao, Bao-Guo; Zhang, Shan; Zhang, De-Pin

    2017-05-01

    In order to evaluate the temperature regulating properties of thermal functional porous polymeric materials such as fabrics treated with phase change material microcapsules, a new apparatus was developed. The apparatus and the test method can measure the heat flux, temperature, and displacement signals during the dynamic contact and then quickly give an evaluation for the temperature regulating properties by simulating the dynamic heat transfer and temperature regulating process when the materials contact the body skin. A series of indices including the psychosensory intensity, regulating capability index, and relative regulating index were defined to characterize the temperature regulating properties. The measurement principle, the evaluation criteria and grading method, the experimental setup and the test results discussion, and the gage capability analysis of the apparatus are presented. The new apparatus provides a method for the objective measurement and evaluation of the temperature regulating properties of thermal functional porous polymeric materials.

  2. Introduction to compressible fluid flow

    CERN Document Server

    Oosthuizen, Patrick H

    2013-01-01

    IntroductionThe Equations of Steady One-Dimensional Compressible FlowSome Fundamental Aspects of Compressible FlowOne-Dimensional Isentropic FlowNormal Shock WavesOblique Shock WavesExpansion Waves - Prandtl-Meyer FlowVariable Area FlowsAdiabatic Flow with FrictionFlow with Heat TransferLinearized Analysis of Two-Dimensional Compressible FlowsHypersonic and High-Temperature FlowsHigh-Temperature Gas EffectsLow-Density FlowsBibliographyAppendices

  3. Dielectric properties measurement system at cryogenic temperatures and microwave frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Molla, J.; Ibarra, A.; Margineda, J.; Zamarro, J. M.; Hernandez, A.

    1994-07-01

    A system based on the resonant cavity method has been developed to measure the permittivity and loss tangent at 12-18 GHz over the temperature range 80 K to 300 K. Changes of permittivity as low as 0.01 % in the range 1 to 30, and 3 x 10{sup 6} for loss tangent values below 10{sup 2}, can be obtained without requiring temperature stability. The thermal expansion coefficient and resistivity factor of copper have been measured between 80 K and 300 K. Permittivity of sapphire and loss tangent of alumina of 99.9 % purity in the same temperature range are presented. (Author) 23 refs.

  4. Laser remote heating in vacuum environment to study temperature dependence of optical properties for bulk materials

    Science.gov (United States)

    Minissale, Marco; Bisson, Regis; Gallais, Laurent

    2016-12-01

    The knowledge of optical and thermal properties of materials at high temperatures is of crucial importance in the field of high power laser/material interactions. We report in this contribution on the development of a spectroscopic ellipsometry system dedicated to the measurement of optical properties of solid materials from the ambient to high temperatures (optic spectrometer to measure reflected light and optical pyrometers for temperature monitoring.

  5. Micromechanical finite element modeling and experimental characterization of the compressive mechanical properties of polycaprolactone:hydroxyapatite composite scaffolds prepared by selective laser sintering for bone tissue engineering

    Science.gov (United States)

    Eshraghi, Shaun; Das, Suman

    2012-01-01

    Bioresorbable scaffolds with mechanical properties suitable for bone tissue engineering were fabricated from polycaprolactone (PCL) and hydroxyapatite (HA) by selective laser sintering (SLS) and modeled by finite element analysis (FEA). Both solid gage parts and scaffolds having 1-D, 2-D and 3-D orthogonal, periodic porous architectures were made with 0, 10, 20 and 30% HA by volume. PCL:HA scaffolds manufactured by SLS had nearly full density (99%) in the designed solid regions and had excellent geometric and dimensional control. Through optimization of the SLS process, the compressive moduli for our solid gage parts and scaffolds are the highest reported in the literature for additive manufacturing. The compressive moduli of solid gage parts were 299.3, 311.2, 415.5 and 498.3 MPa for PCL:HA loading at 100:0, 90:10, 80:20 and 70:30 respectively. The compressive effective stiffness tended to increase as the loading of HA was increased and the designed porosity was lowered. In the case of the most 3-D porous scaffold, the compressive modulus more than doubled from 14.9 MPa to 36.2 MPa when changing the material from 100:0 to 70:30 PCL:HA. A micromechanical finite element analysis (FEA) model was developed to investigate the reinforcement effect of HA loading on the compressive modulus of the bulk material. Using a first-principles based approach, the random distribution of HA particles in a solidified PCL matrix was modeled for any loading of HA to predict the bulk mechanical properties of the composites. The bulk mechanical properties were also used for FEA of the scaffold geometries. Results of the FEA were found to be in good agreement with experimental mechanical testing. The development of patient and site-specific composite tissue engineering constructs with tailored properties can be seen as a direct extension of this work on computational design, a priori modeling of mechanical properties and direct digital manufacturing. PMID:22522129

  6. Micromechanical finite-element modeling and experimental characterization of the compressive mechanical properties of polycaprolactone-hydroxyapatite composite scaffolds prepared by selective laser sintering for bone tissue engineering.

    Science.gov (United States)

    Eshraghi, Shaun; Das, Suman

    2012-08-01

    Bioresorbable scaffolds with mechanical properties suitable for bone tissue engineering were fabricated from polycaprolactone (PCL) and hydroxyapatite (HA) by selective laser sintering (SLS) and modeled by finite-element analysis (FEA). Both solid gage parts and scaffolds having 1-D, 2-D and 3-D orthogonal, periodic porous architectures were made with 0, 10, 20 and 30 vol.% HA. PCL:HA scaffolds manufactured by SLS had nearly full density (99%) in the designed solid regions and had excellent geometric and dimensional control. Through optimization of the SLS process, the compressive moduli for our solid gage parts and scaffolds are the highest reported in the literature for additive manufacturing. The compressive moduli of solid gage parts were 299.3, 311.2, 415.5 and 498.3 MPa for PCL:HA loading at 100:0, 90:10, 80:20 and 70:30, respectively. The compressive effective stiffness tended to increase as the loading of HA was increased and the designed porosity was lowered. In the case of the most 3-D porous scaffold, the compressive modulus more than doubled from 14.9 to 36.2 MPa when changing the material from 100:0 to 70:30 PCL:HA. A micromechanical FEA model was developed to investigate the reinforcement effect of HA loading on the compressive modulus of the bulk material. Using a first-principles based approach, the random distribution of HA particles in a solidified PCL matrix was modeled for any HA loading to predict the bulk mechanical properties of the composites. The bulk mechanical properties were also used for FEA of the scaffold geometries. The results of the FEA were found to be in good agreement with experimental mechanical testing. The development of patient- and site-specific composite tissue-engineering constructs with tailored properties can be seen as a direct extension of this work on computational design, a priori modeling of mechanical properties and direct digital manufacturing. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All

  7. The research on temperature sensing properties of photonic crystal fiber based on Liquid crystal filling

    Directory of Open Access Journals (Sweden)

    Zan Xiangzhen

    2016-01-01

    Full Text Available Based on the photonic bandgap-photonic crystal fibers( PBG-PCF fiber core fills the namitic liquid crystal. By readjusting the temperature to change the refractive index, constitute new liquid fiber-optic temperature sensor. In this paper, we use finite element COMSOL software to simulate and analyze photonic crystal optical fiber sensitive properties. The research show that after the PBG – PCF filling the liquid crystal, its mode field distribution, effective refractive index, waveguide dispersion etc changing with temperature is so big. Therefore, the properties that the refractive index of PCF mode CF changing with temperature sensitive medium, provides the theoretical basis for designing optic fiber temperature sensors.

  8. Composite properties for S-2 glass in a room-temperature-curable epoxy matrix

    Science.gov (United States)

    Clements, L. L.; Moore, R. L.

    1979-01-01

    The authors have measured thermal and mechanical properties of several composites of S-2 glass fiber in a room-temperature-curable epoxy matrix. The filament-wound composites ranged from 50 to 70 vol% fiber. The composites had generally good to excellent mechanical properties, particularly in view of the moderate cost of the material. However, the composites showed rapid increases in transverse thermal expansion above 50 C, and this property must be carefully considered if any use above that temperature is contemplated.

  9. Properties of Palm Oil Fuel Ash (POFA Geopolymer Mortar Cured at Ambient Temperature

    Directory of Open Access Journals (Sweden)

    Olivia Monita

    2017-01-01

    Full Text Available Geopolymer material needs high temperature curing to produce good microstructure, high strength, and durable product. However, curing at ambient temperature is more preferable and practical in application for cast in situ geopolymer. In order to allow curing at ambient temperature, the geopolymer is mixed with mineral additives that has high calcium content such as slag, Ordinary Portland Cement (OPC and high calcium fly ash. In this study, the Ordinary Portland Cement (OPC was added in the Palm Oil Fuel Ash (POFA geopolymer mortar to induce setting and hardening at ambient temperature. Setting time, compressive strength and porosity of the POFA geopolymer mortar were measured. The OPC was added into the geopolymer at dosages of 0%, 20%, 25%, 30%, 35%, and 40%. The alkaline activator used was a combination of NaOH (16M and sodium silicate with a ratio of 2.5 by mass. The POFA geopolymer mortar were cast and cured at ambient temperature. Results show that addition of 35% OPC increased the setting time by 99.44%, increased the compressive strength of mortar by 95.46% and decreased the porosity by 5.27% at 28 days. It can be concluded that inclusion of the OPC could improve the setting and final strength of the geopolymer material.

  10. Compression-Based Compressed Sensing

    OpenAIRE

    Rezagah, Farideh Ebrahim; Jalali, Shirin; Erkip, Elza; Poor, H. Vincent

    2016-01-01

    Modern compression algorithms exploit complex structures that are present in signals to describe them very efficiently. On the other hand, the field of compressed sensing is built upon the observation that "structured" signals can be recovered from their under-determined set of linear projections. Currently, there is a large gap between the complexity of the structures studied in the area of compressed sensing and those employed by the state-of-the-art compression codes. Recent results in the...

  11. Influence of temperature on magnetic properties of silicon steel lamination

    Directory of Open Access Journals (Sweden)

    Junquan Chen

    2017-05-01

    Full Text Available In this paper, we studied the influence of thermal effect on the iron loss components by DC and AC magnetic measurement. The measured result shows that iron loss of nonoriented silicon steel is more influenced by temperature than grain oriented one. Based on loss separation model, we have found a suitable iron loss expression for nonoriented and grain oriented steels. Then a temperature dependent iron loss model is proposed, where temperature coefficient k is introduced to consider thermal effect on dynamic loss. The iron loss model is validated by all series of silicon steel stripe made by WISCO. The relative error of the model is about 11% in a wide range of 20∼400Hz, 20∼200°C, 0∼2T. The proposed model can be applicable to other types of magnetic materials as long as their resistivity rate exhibits approximately linear thermal dependence within a temperature range of 20∼200°C.

  12. Optical properties of indium phosphide nanowire ensembles at various temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Lohn, Andrew J; Onishi, Takehiro; Kobayashi, Nobuhiko P [Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA 95064 (United States); Nanostructured Energy Conversion Technology and Research (NECTAR), Advanced Studies Laboratories, University of California Santa Cruz-NASA Ames Research Center, Moffett Field, CA 94035 (United States)

    2010-09-03

    Ensembles that contain two types (zincblende and wurtzite) of indium phosphide nanowires grown on non-single crystalline surfaces were studied by micro-photoluminescence and micro-Raman spectroscopy at various low temperatures. The obtained spectra are discussed with the emphasis on the effects of differing lattice types, geometries, and crystallographic orientations present within an ensemble of nanowires grown on non-single crystalline surfaces. In the photoluminescence spectra, a typical Varshni dependence of band gap energy on temperature was observed for emissions from zincblende nanowires and in the high temperature regime energy transfer from excitonic transitions and band-edge transitions was identified. In contrast, the photoluminescence emissions associated with wurtzite nanowires were rather insensitive to temperature. Raman spectra were collected simultaneously from zincblende and wurtzite nanowires coexisting in an ensemble. Raman peaks of the wurtzite nanowires are interpreted as those related to the zincblende nanowires by a folding of the phonon dispersion.

  13. Determination of Temperature/Moisture Sensitive Composite Properties

    National Research Council Canada - National Science Library

    Tomblin, John

    2001-01-01

    ...). A series of dynamic mechanical analysis (DMA) and static mechanical tests were performed using specimens conditioned at three relative humidity levels and tested at six different temperatures for two commonly used 270 deg F cure prepreg systems...

  14. Influence of temperature on elastic properties of caesium cyanide

    International Nuclear Information System (INIS)

    Singh, Preeti; Gaur, N.K.; Singh, R.K.

    2007-01-01

    An extended three body force shell model (ETSM), which incorporates the effects of translational-rotational (TR) coupling, three body interactions (TBI) and anharmonicity, has been applied to investigate the temperature dependence of the second order elastic constants (c ij , i,j=1,2) of CsCN. The elastic constant c 44 obtained by us shows an anomalous behaviour with the variation of temperature. The variations of elastic constants (c 11 , c 12 , c 44 ) with temperature are almost in excellent agreement with Brillouin scattering measured data. We have also evaluated the temperature variations of the third order elastic constants (c ijk ) and the pressure derivatives of the c ij in the CsCN material. However, their values could not be compared due to lack of experimental data. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Influence of temperature on the fatigue properties of alloy 690

    International Nuclear Information System (INIS)

    Chai, G.; Frodigh, J.

    2002-01-01

    Owing to good resistance to intergranular stress corrosion cracking (IGSCC), Alloy 690 as steam generator tubing material is today used to replace Alloy 600 in nuclear steam generators. Besides the behaviour in corrosive environments, the response of strain or stress controlled fatigue is also important. Low cycle fatigue tests for hot-extruded tube material of Alloy 690 (Sandvik Sanicro 69) have been performed under total strain-control mode at room temperature (RT) and at elevated temperature (204 0 C). Rectangular specimens taken from the longitudinal axis of the tubes were used. The influences of temperature and strain amplitude on the fatigue life and cyclic deformation behaviour have been investigated. The fatigue life related to plastic strain is somewhat better at 204 0 C than at room temperature, but the difference is rather small. The fatigue life related to total strain at these two temperatures is comparable. The test results are compared with the existing model for Alloy 600. They show a relatively good agreement in the small strain range. This material at 204 0 C shows a cyclic stress response with a cyclic strain hardening first, followed by a relatively stable stress and finally a second cyclic strain hardening, which has rarely been reported on the strain-controlled fatigue at elevated temperature. TEM investigation shows that the material at 204 0 C has a dislocation structure with planar slip mode, which is less damaging or more fatigue resistant. The mechanisms for the second cyclic strain hardening have also been discussed. (author)

  16. Modelling study, efficiency analysis and optimisation of large-scale Adiabatic Compressed Air Energy Storage systems with low-temperature thermal storage

    International Nuclear Information System (INIS)

    Luo, Xing; Wang, Jihong; Krupke, Christopher; Wang, Yue; Sheng, Yong; Li, Jian; Xu, Yujie; Wang, Dan; Miao, Shihong; Chen, Haisheng

    2016-01-01

    Highlights: • The paper presents an A-CAES system thermodynamic model with low temperature thermal energy storage integration. • The initial parameter value ranges for A-CAES system simulation are identified from the study of a CAES plant in operation. • The strategies of system efficiency improvement are investigated via a parametric study with a sensitivity analysis. • Various system configurations are discussed for analysing the efficiency improvement potentials. - Abstract: The key feature of Adiabatic Compressed Air Energy Storage (A-CAES) is the reuse of the heat generated from the air compression process at the stage of air expansion. This increases the complexity of the whole system since the heat exchange and thermal storage units must have the capacities and performance to match the air compression/expansion units. Thus it raises a strong demand in the whole system modelling and simulation tool for A-CAES system optimisation. The paper presents a new whole system mathematical model for A-CAES with simulation implementation and the model is developed with consideration of lowing capital cost of the system. The paper then focuses on the study of system efficiency improvement strategies via parametric analysis and system structure optimisation. The paper investigates how the system efficiency is affected by the system component performance and parameters. From the study, the key parameters are identified, which give dominant influences in improving the system efficiency. The study is extended onto optimal system configuration and the recommendations are made for achieving higher efficiency, which provides a useful guidance for A-CAES system design.

  17. Schlieren-based temperature measurement inside the cylinder of an optical spark ignition and homogeneous charge compression ignition engine.

    Science.gov (United States)

    Aleiferis, Pavlos; Charalambides, Alexandros; Hardalupas, Yannis; Soulopoulos, Nikolaos; Taylor, A M K P; Urata, Yunichi

    2015-05-10

    Schlieren [Schlieren and Shadowgraphy Techniques (McGraw-Hill, 2001); Optics of Flames (Butterworths, 1963)] is a non-intrusive technique that can be used to detect density variations in a medium, and thus, under constant pressure and mixture concentration conditions, measure whole-field temperature distributions. The objective of the current work was to design a schlieren system to measure line-of-sight (LOS)-averaged temperature distribution with the final aim to determine the temperature distribution inside the cylinder of internal combustion (IC) engines. In a preliminary step, we assess theoretically the errors arising from the data reduction used to determine temperature from a schlieren measurement and find that the total error, random and systematic, is less than 3% for typical conditions encountered in the present experiments. A Z-type, curved-mirror schlieren system was used to measure the temperature distribution from a hot air jet in an open air environment in order to evaluate the method. Using the Abel transform, the radial distribution of the temperature was reconstructed from the LOS measurements. There was good agreement in the peak temperature between the reconstructed schlieren and thermocouple measurements. Experiments were then conducted in a four-stroke, single-cylinder, optical spark ignition engine with a four-valve, pentroof-type cylinder head to measure the temperature distribution of the reaction zone of an iso-octane-air mixture. The engine optical windows were designed to produce parallel rays and allow accurate application of the technique. The feasibility of the method to measure temperature distributions in IC engines was evaluated with simulations of the deflection angle combined with equilibrium chemistry calculations that estimated the temperature of the reaction zone at the position of maximum ray deflection as recorded in a schlieren image. Further simulations showed that the effects of exhaust gas recirculation and air

  18. Compression Properties and Electrical Conductivity of In-Situ 20 vol.% Nano-Sized TiCx/Cu Composites with Different Particle Size and Morphology.

    Science.gov (United States)

    Zhang, Dongdong; Bai, Fang; Sun, Liping; Wang, Yong; Wang, Jinguo

    2017-05-04

    The compression properties and electrical conductivity of in-situ 20 vol.% nano-sized TiC x /Cu composites fabricated via combustion synthesis and hot press in Cu-Ti-CNTs system at various particles size and morphology were investigated. Cubic-TiC x /Cu composite had higher ultimate compression strength (σ UCS ), yield strength (σ 0.2 ), and electric conductivity, compared with those of spherical-TiC x /Cu composite. The σ UCS , σ 0.2 , and electrical conductivity of cubic-TiC x /Cu composite increased by 4.37%, 20.7%, and 17.8% compared with those of spherical-TiC x /Cu composite (526 MPa, 183 MPa, and 55.6% International Annealed Copper Standard, IACS). Spherical-TiC x /Cu composite with average particle size of ~94 nm exhibited higher ultimate compression strength, yield strength, and electrical conductivity compared with those of spherical-TiC x /Cu composite with 46 nm in size. The σ UCS , σ 0.2 , and electrical conductivity of spherical-TiC x /Cu composite with average size of ~94 nm in size increased by 17.8%, 33.9%, and 62.5% compared with those of spherical-TiC x /Cu composite (417 MPa, 121 MPa, and 40.3% IACS) with particle size of 49 nm, respectively. Cubic-shaped TiC x particles with sharp corners and edges led to stress/strain localization, which enhanced the compression strength of the composites. The agglomeration of spherical-TiC x particles with small size led to the compression strength reduction of the composites.

  19. Low-temperature thermal properties of yttrium and lutetium dodecaborides

    International Nuclear Information System (INIS)

    Czopnik, A; Shitsevalova, N; Pluzhnikov, V; Krivchikov, A; Paderno, Yu; Onuki, Y

    2005-01-01

    The heat capacity (C p ) and dilatation (α) of YB 12 and LuB 12 are studied. C p of the zone-melted YB 12 tricrystal is measured in the range 2.5-70 K, of the zone-melted LuB 12 single crystal in the range 0.6-70 K, and of the LuB 12 powder sample in the range 4.3-300 K; α of the zone-melted YB 12 tricrystal and LuB 12 single crystals is measured in the range 5-200 K. At low temperatures a negative thermal expansion (NTE) is revealed for both compounds: for YB 12 at 50-70 K, for LuB 12 at 10-20 K and 60-130 K. Their high-temperature NTE is a consequence of nearly non-interacting freely oscillating metal ions (Einstein oscillators) in cavities of a simple cubic rigid Debye lattice formed by B 12 cage units. The Einstein temperatures are ∼254 and ∼164 K, and the Debye temperatures are ∼1040 K and ∼1190 K for YB 12 and LuB 12 respectively. The LuB 12 low-temperature NTE is connected with an induced low-energy defect mode. The YB 12 superconducting transition has not been detected up to 2.5 K

  20. Cell cytoskeletal changes effected by static compressive stress lead to changes in the contractile properties of tissue regenerative collagen membranes

    Directory of Open Access Journals (Sweden)

    K Gellynck

    2013-06-01

    Full Text Available Static compressive stress can influence the matrix, which subsequently affects cell behaviour and the cell’s ability to further transform the matrix. This study aimed to assess response to static compressive stress at different stages of osteoblast differentiation and assess the cell cytoskeleton’s role as a conduit of matrix-derived stimuli. Mouse bone marrow mesenchymal stem cells (MSCs (D1 ORL UVA, osteoblastic cells (MC3T3-E1 and post-osteoblast/pre-osteocyte-like cells (MLO-A5 were seeded in hydrated and compressed collagen gels. Contraction was quantified macroscopically, and cell morphology, survival, differentiation and mineralisation assessed using confocal microscopy, alamarBlue® assay, real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR and histological stains, respectively. Confocal microscopy demonstrated cell shape changes and favourable microfilament organisation with static compressive stress of the collagen matrix; furthermore, cell survival was greater compared to the hydrated gels. The stage of osteoblast differentiation determined the degree of matrix contraction, with MSCs demonstrating the greatest amount. Introduction of microfilament disrupting inhibitors confirmed that pre-stress and tensegrity forces were under the influence of gel density, and there was increased survival and differentiation of the cells within the compressed collagen compared to the hydrated collagen. There was also relative stiffening and differentiation with time of the compressed cell-seeded collagen, allowing for greater manipulation. In conclusion, the combined collagen chemistry and increased density of the microenvironment can promote upregulation of osteogenic genes and mineralisation; MSCs can facilitate matrix contraction to form an engineered membrane with the potential to serve as a ‘pseudo-periosteum’ in the regeneration of bone defects.

  1. Symmetric scaling properties in global surface air temperature anomalies

    Science.gov (United States)

    Varotsos, Costas A.; Efstathiou, Maria N.

    2015-08-01

    We have recently suggested "long-term memory" or internal long-range correlation within the time-series of land-surface air temperature (LSAT) anomalies in both hemispheres. For example, an increasing trend in the LSAT anomalies is followed by another one at a different time in a power-law fashion. However, our previous research was mainly focused on the overall long-term persistence, while in the present study, the upward and downward scaling dynamics of the LSAT anomalies are analysed, separately. Our results show that no significant fluctuation differences were found between the increments and decrements in LSAT anomalies, over the whole Earth and over each hemisphere, individually. On the contrary, the combination of land-surface air and sea-surface water temperature anomalies seemed to cause a departure from symmetry and the increments in the land and sea surface temperature anomalies appear to be more persistent than the decrements.

  2. Effect of thermal history on mechanical properties of polyetheretherketone below the glass transition temperature

    Science.gov (United States)

    Cebe, Peggy; Chung, Shirley Y.; Hong, Su-Don

    1987-01-01

    The effect of thermal history on the tensile properties of polyetheretherketone neat resin films was investigated at different test temperatures (125, 25, and -100) using four samples: fast-quenched amorphous (Q); quenched, then crystallized at 180 C (C180); slowly cooled (for about 16 h) from the melt (SC); and air-cooled (2-3 h) from the melt (AC). It was found that thermal history significantly affects the tensile properties of the material below the glass transition. Fast quenched amorphous films were most tough, could be drawn to greatest strain before rupture, and undergo densification during necking; at the test temperature of -100 C, these films had the best ultimate mechanical properties. At higher temperatures, the semicrystalline films AC and C180 had properties that compared favorably with the Q films. The SC films exhibited poor mechanical properties at all test temperatures.

  3. Compression embedding

    Science.gov (United States)

    Sandford, M.T. II; Handel, T.G.; Bradley, J.N.

    1998-07-07

    A method and apparatus for embedding auxiliary information into the digital representation of host data created by a lossy compression technique and a method and apparatus for constructing auxiliary data from the correspondence between values in a digital key-pair table with integer index values existing in a representation of host data created by a lossy compression technique are disclosed. The methods apply to data compressed with algorithms based on series expansion, quantization to a finite number of symbols, and entropy coding. Lossy compression methods represent the original data as ordered sequences of blocks containing integer indices having redundancy and uncertainty of value by one unit, allowing indices which are adjacent in value to be manipulated to encode auxiliary data. Also included is a method to improve the efficiency of lossy compression algorithms by embedding white noise into the integer indices. Lossy compression methods use loss-less compression to reduce to the final size the intermediate representation as indices. The efficiency of the loss-less compression, known also as entropy coding compression, is increased by manipulating the indices at the intermediate stage. Manipulation of the intermediate representation improves lossy compression performance by 1 to 10%. 21 figs.

  4. A high-speed spatial (linear) scanning pyrometer: A tool for diagnostics, temperature mapping, and property determinations at high temperatures

    Science.gov (United States)

    Cezairliyan, A.; Chang, R. F.; Foley, G. M.

    1990-01-01

    Development of a fast spatial scanning pyrometer for temperature measurements above 1500 K is described. The salient features of the pyrometer are: (1) it measures spectral radiance temperature (at 0.65 micron) at 1024 points along a straight line (25 mm long) on the target; (2) it has no moving parts and uses a self-scanning linear array of silicon photodiodes as the detector; (3) its output is recorded digitally every 1 microsec with a full-scale resolution of about 1 part in 4000, permitting performance of a complete cycle of measurements (1024 points) in about 1 ms. Operational characteristics of the pyrometer are given. Examples of measurements of the temperature along rapidly heated (resistive self-heating) specimens (rod, tube, strip) are presented. Potential use of the pyrometer in the experiments, both ground-based and in microgravity, requiring temperature mapping and property distribution of the specimen at high temperatures is discussed.

  5. Development of radiation pyrometer for time-resolved measurement of temperatures in shock-wave compression experiments

    International Nuclear Information System (INIS)

    Rav, Amit S.; Joshi, K.D.; Gupta, Satish C.

    2011-04-01

    We have developed a radiation pyrometer system for time resolved measurement of temperature in materials subjected to shock loading or to sudden deposition of energy by any other means. This instrument has four channels, with each channel equipped with interference filter and photo-receiver. The interference filter selects the desired wavelength in the visible to near infrared range and the photo-receiver converts the filtered radiation into an electrical signal. The FWHM bandwidth of the interference filter is ∼10 nm around the selected central wavelength and the dynamic bandwidth of photo-receiver is ∼125 MHz which corresponds to time resolution of ∼3ns. The output of photo-receivers at each channel is recorded in fast Digital Storage Oscilloscope (DSO). The recorded intensities at a given instant of time for four wavelength are fitted to Plank's radiation law and the information about the temperature and emissivity of the object is obtained. A software code has been developed to analyze the experimental data for generating time resolved profile of temperature and emissivity. The instrument is demonstrated to make steady state temperature measurement of standard Tungsten Halogen Lamp Source (THLS) with an accuracy of ∼5%. Also it has been used for the measurement of time resolved temperature profile of electrically exploded conducting wire (copper) having transient of the order of ∼15 ns. (author)

  6. Thermal Effects on the Compressive Behavior of IM7/PET15 Laminates

    Science.gov (United States)

    Walker, Sandra Polesky

    2003-01-01

    The effect of changing operating temperature on the compressive response of IM7/PETI5 composite laminates is investigated within this paper. The three temperatures evaluated for this study were 129 C, 21 C, and 177 C, a spectrum from cryogenic to an elevated operating temperature. Laminate compressive strength property testing was conducted using the Wyoming Combined Load Compression fixture to generate strength data at the three operating temperatures of interest for several lay-ups. A three-dimensional finite element analysis model of a [90/0]8s composite laminate subject to compressive loading is developed. The model is used to study the key attributes of the laminate that significantly influence the state of stress in the laminate. Both the resin rich layer located between lamina and the thermal residual stresses present in the laminate due to curing are included in the analysis model. For the laminate modeled, the effect of modeling temperature dependent material properties was determined to be insignificant for the operating temperatures studied. Simply using the material properties measured at the operating temperature of interest was sufficient for predicting stresses accurately in a linear analysis for the current problem. The three-dimensional analysis results revealed that the application of an applied compressive axial load in the 0-degree direction decreased the interlaminar stresses present in the laminate initially due to curing. Therefore, failure was concluded not be attributable to the interlaminar stresses in the composite laminate being studied when a compressive load is applied. The magnitude of the measured laminate compressive strength change with a change in temperature is concluded to be dominated by the change in the lamina compressive axial strength with a change in temperature.

  7. Phonon dynamics in a compressible classical Heisenberg chain

    NARCIS (Netherlands)

    Fivez, Jan; Raedt, Hans De; Raedt, Bart De

    1980-01-01

    The dynamic properties of the compressible classical Heisenberg chain with bilinear coupling are investigated. The sound velocity is calculated exactly. The Fourier-transformed displacement-displacement correlation function is studied as a function of temperature, wave vector, and the model

  8. Experimental and numerical investigation of the evolutions of Zirconium 702 α textures during rolling and in-plane compression at room temperature

    International Nuclear Information System (INIS)

    Francillette, H.

    1997-01-01

    This research thesis deals with the modelling of the evolutions of crystallographic textures of Zirconium 702 plates rolled at room temperature. The modelling is based on active deformation mechanisms. The author also aims at integrating, the best as possible, experimental measurements into micro-macro Taylor-, Sachs- and self-coherent-type models. After a literature survey on zirconium plastic strain and deformation textures (crystal structure, observed deformation mechanisms, impacting factors and mechanism appearance, experimental textures), the author describes the experimental approach (samples, in-plane compression test, rolling, backscattered electron diffraction and X ray diffraction analysis, plate characterization, texture description), reports an analysis of experimental results, and presents the modelling of zirconium texture evolutions (principles, single crystal behaviour, texture prediction models, deformation mechanism modelling, texture simulation) and discussed the choice of models. He finally describes and analyzes the results of numerical simulations, notably when using the models of Taylor or Sachs, and presents different sets of simulations

  9. Temperature dependence of electromechanical properties of PLZT x ...

    Indian Academy of Sciences (India)

    Administrator

    behaviour is observed for the overtones also. However, the piezoelectric response of the overtones disappears at a lower temperature than the fundamental mode. The quantity, Δfps, depends on the electromechanical coupling coefficient as well as geometry of the piezo- ceramic material (Jaffe et al 1971). The behaviour of ...

  10. Thermal aggregation properties of nanoparticles modified with temperature sensitive copolymers.

    Science.gov (United States)

    Hamner, Kristen L; Maye, Mathew M

    2013-12-10

    In this paper, we describe the use of a temperature responsive polymer to reversibly assemble gold nanoparticles of various sizes. Temperature responsive, low critical solution temperature (LCST) pNIPAAm-co-pAAm polymers, with transition temperatures (T(C)) of 51 and 65 °C, were synthesized with a thiol modification, and grafted to the surface of 11 and 51 nm gold nanoparticles (AuNPs). The thermal-responsive behavior of the polymer allowed for the reversible aggregation of the nanoparticles, where at T polymers were hydrophilic and extended between particles. In contrast, at T > T(C), the polymer shell undergoes a hydrophilic to hydrophobic phase transition and collapses, decreasing interparticle distances between particles, allowing aggregation to occur. The AuNP morphology and polymer conjugation were probed by TEM, FTIR, and (1)H NMR. The thermal response was probed by UV-vis and DLS. The structure of the assembled aggregates at T > T(C) was studied via in situ small-angle X-ray scattering, which revealed interparticle distances defined by polymer conformation.

  11. Effects of reaction temperature on size and optical properties of ...

    Indian Academy of Sciences (India)

    Administrator

    solvent systems, ratio of the precursor, injection rates and concentrations of the ligands (Peng and Peng 2001; Qu et al 2001; Peng 2002; Yu and Peng 2002). However, the above studies discussed in detail the influential factors of CdSe nanocrystals synthesis except for reaction temperature. As part of the development of.

  12. Ultra-High Temperature Sensors Based on Optical Property

    Energy Technology Data Exchange (ETDEWEB)

    Nabeel Riza

    2008-09-30

    In this program, Nuonics, Inc. has studied the fundamentals of a new Silicon Carbide (SiC) materials-based optical sensor technology suited for extreme environments of coal-fired engines in power production. The program explored how SiC could be used for sensing temperature, pressure, and potential gas species in a gas turbine environment. The program successfully demonstrated the optical designs, signal processing and experimental data for enabling both temperature and pressure sensing using SiC materials. The program via its sub-contractors also explored gas species sensing using SiC, in this case, no clear commercially deployable method was proven. Extensive temperature and pressure measurement data using the proposed SiC sensors was acquired to 1000 deg-C and 40 atms, respectively. Importantly, a first time packaged all-SiC probe design was successfully operated in a Siemens industrial turbine rig facility with the probe surviving the harsh chemical, pressure, and temperature environment during 28 days of test operations. The probe also survived a 1600 deg-C thermal shock test using an industrial flame.

  13. On Normalized Compression Distance and Large Malware

    OpenAIRE

    Borbely, Rebecca Schuller

    2015-01-01

    Normalized Compression Distance (NCD) is a popular tool that uses compression algorithms to cluster and classify data in a wide range of applications. Existing discussions of NCD's theoretical merit rely on certain theoretical properties of compression algorithms. However, we demonstrate that many popular compression algorithms don't seem to satisfy these theoretical properties. We explore the relationship between some of these properties and file size, demonstrating that this theoretical pro...

  14. High temperature magnetic properties of nanocrystalline Sn0 ...

    Indian Academy of Sciences (India)

    Administrator

    National School of Applied Sciences, Safi, Morocco. 5Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9, France. MS received 17 October 2012; revised 17 December 2012. Abstract. Structural and magnetic properties of Sn0⋅95Co0⋅05O2 nanocrystalline and diluted magnetic semicon-.

  15. Influence of substrate temperature on certain physical properties ...

    Indian Academy of Sciences (India)

    MS received 16 July 2015; revised 19 November 2015; accepted 18 April 2016; published online 12 November 2016. Abstract. Nanocrystalline Ag-doped ... adhesive property. Moreover, silver-doped materials are chemically durable and release silver ions for a long period of time [11]. Silver-doped indium and ceram-.

  16. Temperature-dependent ionic conductivity and transport properties ...

    Indian Academy of Sciences (India)

    Administrator

    with dc conductivity (σdc) for different LiClO4 weight fractions (p) related to transport dimensionality was also focused. The highest ionic ... Percolation; transport properties; VTF model; ionic conductivity; Williams–Landel–Ferry. 1. Introduction ..... thermodynamic interaction parameter and composites are thermodynamically ...

  17. Temperature-dependent ionic conductivity and transport properties ...

    Indian Academy of Sciences (India)

    This paper presents the investigation on physicochemical properties and ionic conductivity of LiClO4-doped poly(vinyl alcohol) (PVA)/modified cellulose composites. The percolative behaviour of LiClO4 with dc conductivity (dc) for different LiClO4 weight fractions (p) related to transport dimensionality was also focused.

  18. Low temperature radiative properties of materials used in cryogenics

    Czech Academy of Sciences Publication Activity Database

    Musilová, Věra; Hanzelka, Pavel; Králík, Tomáš; Srnka, Aleš

    2005-01-01

    Roč. 45, č. 8 (2005), s. 529-536 ISSN 0011-2275 R&D Projects: GA AV ČR(CZ) IBS2065109 Keywords : structural materials * radiant properties * cryostats Subject RIV: BJ - Thermodynamics Impact factor: 0.762, year: 2005

  19. Effect of temperature on antibiotic properties of garlic ( Allium ...

    African Journals Online (AJOL)

    Garlic and ginger are the two most common herbs used in traditional medicine practice for their antimicrobial activities. Moreover, in many countries, they are also used with boiled food preparations, which can destroy their important medicinal properties. We conducted an agar well diffusion assay with aqueous extracts of ...

  20. Magnetic properties of the austenitic stainless steels at cryogenic temperatures

    International Nuclear Information System (INIS)

    Kobayashi, T.; Tsuchiya, K.; Itoh, K.; Kobayashi, S.

    2002-01-01

    The magnetization was measured for the austenitic stainless steel of SUS304, SUS304L, SUS316, and SUS316L with the temperature from 5K to 300K and the magnetic field from 0T to 10T. The field dependences of the magnetizations changed at about 0.7T and 4T. The dependence was analyzed with ranges of 0-0.5T, 1-3T, and 5-10T. There was not so much difference between those stainless steels for the usage at small fields and 300 K. The SUS316 and SUS316L samples showed large non-linearity at high fields and 5K. Therefore, SUS304 was recommended for usage at high fields and low temperatures to design superconducting magnets with the linear approximation of the field dependence of magnetization

  1. High temperature fatigue properties of the 316 FR steel

    International Nuclear Information System (INIS)

    Kobayashi, Kazuo; Yamaguchi, Koji; Kato, Seiichi; Nishijima, Satoshi; Fujioka, Terutaka; Nakazawa, Takanori; Koto, Hiroyuki; Date, Shingo

    1998-01-01

    Type 316 FR stainless steel has been developed as a candidate material for fast breeder reactor of next century. For the structural integrity design of high temperature components including reactor vessel, long-term data and analysis method are investigated for the new 316 FR steel especially to evaluate its time-dependent low-cycle fatigue behavior. The present paper reports dependencies of fatigue life on the strain rate from 10 -2 to 10 -5 s -1 , and on the temperature dependencies from 500degC to 600degC. Data are analyzed by a parametric method formerly proposed by the authors. It is shown that the method has a good predictability of the fatigue life up to very low strain rate of 10 -6 s -1 . (author)

  2. Observable Vortex Properties in Finite Temperature Bose Gases

    OpenAIRE

    Allen, A. J.; Zaremba, E.; Barenghi, C. F.; Proukakis, N. P.

    2012-01-01

    We study the dynamics of vortices in finite temperature atomic Bose-Einstein condensates, focussing on decay rates, precession frequencies and core brightness, motivated by a recent experiment (Freilich et al. Science 329, 1182 (2010)) in which real-time dynamics of a single vortex was observed. Using the ZNG formalism based on a dissipative Gross-Pitaevskii equation for the condensate coupled to a semi-classical Boltzmann equation for the thermal cloud, we find a rapid nonlinear increase of ...

  3. Collective excitations and low temperature transport properties of bismuth

    Energy Technology Data Exchange (ETDEWEB)

    Chudzinski, Piotr; Giamarchi, Thierry [DPMC-MaNEP, University of Geneva (Switzerland)

    2011-07-01

    We examine the influence of collective excitations on several transport coefficients (conductivity, magneto-optical conductivity, Nernst effect) for semimetal, bismuth. A longstanding problem of the transport coefficients in this material is the fact that their amplitude and temperature dependences do not obey naive Fermi liquid expectations. For the conductivity, we show that at high temperatures Baber scattering is able to explain quantitatively the DC resistivity experiments, while at low temperatures many-body effects need to be introduced to explain qualitative deviations from the standard T{sup 2} behavior. An atypical feature in magneto-optical conductivity is predicted. The Nernst effect in bismuth was recently the subject of several contradictory theoretical studies. We show that a plasmon physics allows to get a coherent picture and leads to very large values of the Nernst signal. We use two complementary methods- Feynmann diagrams and field theory (Hubbard-Stratonovich transformation). These methods, which go beyond the standard RPA study, allow to set a limit to the validity of our model and to make contact with the other family of semimetals, 1T-TiSe{sub 2}, also subject of recent experimental interest. To complete the discussion of semimetals, we also study the case of graphite.

  4. Deconfinement and hadron properties at extremes of temperature and density

    International Nuclear Information System (INIS)

    Blaschke, D.

    1998-01-01

    After introducing essential, qualitative concepts and results, we discuss the application of Dyson-Schwinger equations to QCD at finite T and μ. We summarise the calculation of the critical exponents of two-light-flavour QCD using the chiral and thermal susceptibilities; and an algebraic model that elucidates the origin of an anticorrelation between the μ- and T-dependence of a range of meson properties. That model also provides an algebraic understanding of why the finite-T behaviour of bulk thermodynamic properties is mirrored in their μ-dependence, and why meson masses decrease with μ even though f π and - left angle anti qq right angle increase. The possibility of diquark condensation is canvassed. Its realisation is uncertain because it is contingent upon an assumption about the quark-quark scattering kernel that is demonstrably false in some applications; e.g., it predicts the existence of coloured diquarks in the strong interaction spectrum, which are not observed. (orig.)

  5. Deconfinement and hadron properties at extremes of temperature and density

    International Nuclear Information System (INIS)

    Blaschke, D.; Roberts, C.D.

    1998-01-01

    After introducing essential, qualitative concepts and results, the authors discuss the application of Dyson-Schwinger equations to QCD at finite T and μ. They summarize the calculation of the critical exponents of two-light-flavor QCD using the chiral and thermal susceptibilities; and an algebraic model that elucidates the origin of an anticorrelation between the μ- and T-dependence of a range of meson properties. That model also provides an algebraic understanding of why the finite-T behavior of bulk thermodynamic properties is mirrored in their μ-dependence, and why meson masses decrease with μ even though f π and - increase. The possibility of diquark condensation is canvassed. Its realization is uncertain because it is contingent upon an assumption abut the quark-quark scattering kernel that is demonstrably false in some applications; e.g., it predicts the existence of colored diquarks in the strong interaction spectrum, which are not observed

  6. Effect of temperature on viscoelastic properties of semisolid dairy desserts

    OpenAIRE

    Tárrega, Amparo; Durán, Luis; Costell, Elvira

    2003-01-01

    The “natillas”, semisolid dairy dessert of wide consumption in Spain, is composed of milk, starch, hydrocolloids, sugars, colorants and aromas. The particular characteristics of some ingredients, like fat content of milk, type of starch, and/or type and concentration of hydrocolloids, and their crossed interactions, will be reflected in notable differences in their rheological and sensory properties. Little information is available on the differences to be found in commercial samples of this ...

  7. Influence of press temperature on the properties of binderless particleboard made from oil palm trunk

    International Nuclear Information System (INIS)

    Hashim, Rokiah; Said, Norafizah; Lamaming, Junidah; Baskaran, Mohana; Sulaiman, Othman; Sato, Masatoshi; Hiziroglu, Salim; Sugimoto, Tomoko

    2011-01-01

    Research highlights: → Influence of press temperature on binderless particleboard of oil palm trunk. → Modulus of rupture increased with increasing press temperature. → The internal bond strength of samples meets JIS standard. → Water absorption and thickness swelling improved. → Increasing pressing temperature improve properties of the boards. -- Abstract: The objective of this investigation was to evaluate the properties of binderless particleboard manufactured from oil palm trunk as a function of press temperature. Particleboard samples were manufactured with a target density of 0.80 g/cm 3 using press temperatures of 160 o C, 180 o C and 200 o C. The modulus of rupture, internal bond strength, water absorption and thickness swelling of the boards were determined based on Japanese Industrial Standards (JIS). Thermal gravimetric analysis, Fourier transform infrared spectroscopy and field-emission scanning electron microscopy coupled with energy dispersive X-ray analysis were employed to characterize the properties of the raw materials and the manufactured panels. The moduli of rupture of the samples were observed to increase with increasing press temperature, but they did not meet the standard values. However, the internal bond strength of the samples attained satisfactory values according to the JIS standard for all three temperature levels. Water absorption and thickness swelling of the boards decreased with increasing pressing temperature. Based on the findings in this study, increasing the pressing temperature may be considered a potential way of improving the properties of binderless particleboard.

  8. Effect of mold temperature on short and long-term mechanical properties of PBT

    Directory of Open Access Journals (Sweden)

    2008-02-01

    Full Text Available In this work, the effect of mold temperature variation on the short-term mechanical properties obtained from the tensile and Charpy impact tests, and the long-term mechanical properties obtained from dynamic mechanical loading and flexural creep of injection molded polybutylene terepthalate (PBT are reported. It has been observed that the effect of changing the processing condition viz. mold temperature on the viscoelastic properties are more pronounced when their long-term behavior is tested. The tensile and impact properties showed only a negligible effect to the change in mold temperature. Further, analysis of the creep curves by applying a four-element Burger model presented a comprehensive understanding of their long-term viscoelastic behavior with respect to the change in mold temperature.

  9. Effects of cyclic compression on the mechanical properties and calcification process of immature chick bone tissue in culture.

    Science.gov (United States)

    Maeda, Eijiro; Nakagaki, Masashi; Ichikawa, Katsuhisa; Nagayama, Kazuaki; Matsumoto, Takeo

    2017-06-01

    Contribution of mechanical loading to tissue growth during both the development and post-natal maturation is of a particular interest, as its understanding would be important to strategies in bone tissue engineering and regenerative medicine. The present study has been performed to investigate how immature bone responds to mechanical loading using an ex vivo culture system. A slice of the tibia, with the thickness of 3 mm, was obtained from 0-day-old chick. For the ex vivo culture experiment in conjunction with cyclic compressive loading, we developed a custom-made, bioreactor system where both the load and the deformation applied to the specimen was recorded. Cyclic compression, with an amplitude of 0.3 N corresponding to 1 to 2% compressive strain, was applied to immature bone specimen during a 3-day culture period at an overall loading rate 3-4 cycles/min, in the presence of β-glycerol phosphate and dexamethasone in culture medium. The stress-strain relationship was obtained at the beginning and the end of the culture experiment. In addition, analyses for alkaline phosphate release, cell viability and tissue calcification were also performed. It was exhibited that elastic moduli of bone slices were significantly elevated at the end of the 3-day culture in the presence of cyclic compression, which was a similar phenomenon to significant elevation of the elastic moduli of bone tissue by the maturation from 0-day old to 3-day old. By contrast, no significant changes in the moduli were observed in the absence of cyclic compression or in deactivated, cell-free samples. The increases in the moduli were coincided with the increase in calcified area in the bone samples. It was confirmed that immature bone can respond to compressive loading in vitro and demonstrate the growth of bone matrix, similar to natural, in vivo maturation. The elevation of the elastic moduli was attributable to the increased calcified area and the realignment of collagen fibers parallel to

  10. Effects of cyclic compression on the mechanical properties and calcification process of immature chick bone tissue in culture

    Directory of Open Access Journals (Sweden)

    Eijiro Maeda

    2017-06-01

    Full Text Available Contribution of mechanical loading to tissue growth during both the development and post-natal maturation is of a particular interest, as its understanding would be important to strategies in bone tissue engineering and regenerative medicine. The present study has been performed to investigate how immature bone responds to mechanical loading using an ex vivo culture system. A slice of the tibia, with the thickness of 3 mm, was obtained from 0-day-old chick. For the ex vivo culture experiment in conjunction with cyclic compressive loading, we developed a custom-made, bioreactor system where both the load and the deformation applied to the specimen was recorded. Cyclic compression, with an amplitude of 0.3 N corresponding to 1 to 2% compressive strain, was applied to immature bone specimen during a 3-day culture period at an overall loading rate 3–4 cycles/min, in the presence of β-glycerol phosphate and dexamethasone in culture medium. The stress-strain relationship was obtained at the beginning and the end of the culture experiment. In addition, analyses for alkaline phosphate release, cell viability and tissue calcification were also performed. It was exhibited that elastic moduli of bone slices were significantly elevated at the end of the 3-day culture in the presence of cyclic compression, which was a similar phenomenon to significant elevation of the elastic moduli of bone tissue by the maturation from 0-day old to 3-day old. By contrast, no significant changes in the moduli were observed in the absence of cyclic compression or in deactivated, cell-free samples. The increases in the moduli were coincided with the increase in calcified area in the bone samples. It was confirmed that immature bone can respond to compressive loading in vitro and demonstrate the growth of bone matrix, similar to natural, in vivo maturation. The elevation of the elastic moduli was attributable to the increased calcified area and the realignment of collagen

  11. Effect of Injection Molding Melt Temperatures on PLGA Craniofacial Plate Properties during In Vitro Degradation

    Directory of Open Access Journals (Sweden)

    Liliane Pimenta de Melo

    2017-01-01

    Full Text Available The purpose of this article is to present mechanical and physicochemical properties during in vitro degradation of PLGA material as craniofacial plates based on different values of injection molded temperatures. Injection molded plates were submitted to in vitro degradation in a thermostat bath at 37 ± 1°C by 16 weeks. The material was removed after 15, 30, 60, and 120 days; then bending stiffness, crystallinity, molecular weights, and viscoelasticity were studied. A significant decrease of molecular weight and mechanical properties over time and a difference in FT-IR after 60 days showed faster degradation of the material in the geometry studied. DSC analysis confirmed that the crystallization occurred, especially in higher melt temperature condition. DMA analysis suggests a greater contribution of the viscous component of higher temperature than lower temperature in thermomechanical behavior. The results suggest that physical-mechanical properties of PLGA plates among degradation differ per injection molding temperatures.

  12. Diametral Compressive Strength and Elastic Modulus of Flattened Disc using Diametral Compressive Test

    International Nuclear Information System (INIS)

    Kim, Dong Hoon; Kim, Byung Jun; Jang, Chang Heui; Chi, Se Hwan

    2009-01-01

    The nuclear grade graphite is the candidate materials for the in-core components of the very high temperature gas-cooled tractor (VHTR) due to its very high conductivity, melting temperature, chemical resistance and mechanical stability. Nuclear graphite undergoes dimensional change and mechanical properties change because of irradiation damage. To estimate the irradiation damage, surveillance capsule would be inserted in reactor. Surveillance capsule sizes were limited because it would be located inside of a reactor vessel. Thus, a new test method using small specimen is needed and diametral compressive test is one of them. However, circular anvils are needed according to the specimen size. A flattened disc specimen were proposed to overcome such a problem and applied for determination of mechanical properties for brittle rocks. In this study, the applicability of such specimen was investigated. In addition, minimum specimen size for test was determined and diametral compressive strength of nuclear graphite was measured

  13. Mechanical properties of adhesive systems at cryogenic and other temperatures

    Science.gov (United States)

    Staton, W. L.; Klich, P. J.; Cockrell, C. E.

    1982-01-01

    This paper presents a summary of the National Transonic Facility (NTF) fan blade adhesive characterization tests. Data was obtained at -300 F, room temperature (RT) and 200 F. The adhesive characterization data was acquired using specimens fabricated from materials orientated to simulate the lay up of the fan blades. Specimen fabrication, characterization tests, test equipment, test data, results and concluding remarks are reported. Adhesive test results are presented for specimens of the following types: lap shear, double lap shear, butt, short beam shear, flexure, and differential strain.

  14. Thermal Properties of Double-Aluminized Kapton at Low Temperatures

    Science.gov (United States)

    Tuttle, J.; DiPirro, M.; Canavan, E.; Hait, T.

    2007-01-01

    Double-aluminized kapton (DAK) is commonly used in multi-layer insulation blankets in cryogenic systems. NASA plans to use individual DAK sheets in lightweight deployable shields for satellites carrying instruments. A set of these shields will reflect away thermal radiation from the sun, the earth, and the instrument's warm side and allow the instrument's cold side to radiate its own heat to deep space. In order to optimally design such a shield system, it is important to understand the thermal characteristics of DAK down to low temperatures. We describe experiments which measured the thermal conductivity and electrical resistivity down to 4 Kelvin and the emissivity down to 10 Kelvin.

  15. Chemical composition and temperature influence on honey texture properties.

    Science.gov (United States)

    Oroian, Mircea; Paduret, Sergiu; Amariei, Sonia; Gutt, Gheorghe

    2016-01-01

    The aim of this study is to evaluate the chemical composition and temperatures (20, 30, 40, 50 and 60 °C) influence on the honey texture parameters (hardness, viscosity, adhesion, cohesiveness, springiness, gumminess and chewiness). The honeys analyzed respect the European regulation in terms of moisture content and inverted sugar concentration. The texture parameters are influenced negatively by the moisture content, and positively by the °Brix concentration. The texture parameters modelling have been made using the artificial neural network and the polynomial model. The polynomial model predicted better the texture parameters than the artificial neural network.

  16. Effect of ECAP temperature on microstructure and mechanical properties of Al–Zn–Mg–Cu alloy

    OpenAIRE

    Shaeri, M.H.; Shaeri, M.; Ebrahimi, M.; Salehi, M.T.; Seyyedein, S. H

    2016-01-01

    The effect of equal channel angular pressing (ECAP) at different temperatures (room temperature, 120, 150 and 180 °C) on microstructure and mechanical properties of Al-7075 solid solution alloy was investigated. Microstructure of the specimens was examined using orientation imaging microscopy, transmission electron microscopy as well as X-ray diffractometer, and mechanical properties were measured by Vickers microhardness and tensile tests. Microstructural investigations showed that after 3 o...

  17. Tailoring the magnetic properties and magnetorheological behavior of spinel nanocrystalline cobalt ferrite by varying annealing temperature

    OpenAIRE

    Sedlačík, Michal; Pavlínek, Vladimír; Peer, Petra; Filip, Petr

    2014-01-01

    Magnetic nanoparticles of spinel nanocrystalline cobalt ferrite were synthesized via the sol-gel method and subsequent annealing. The influence of the annealing temperature on the structure, magnetic properties, and magnetorheological effect was investigated. The finite crystallite size of the particles, determined by X-ray diffraction and the particle size observed via transmission electron microscopy, increased with the annealing temperature. The magnetic properties observed via a vibrating...

  18. Determination of composition and physical properties of partially ionized plasmas in the function of temperature

    International Nuclear Information System (INIS)

    Zaporowski, B.

    1992-01-01

    The investigations of various kinds of partially ionized plasma were conducted for the pressure of 0.1 MPa and in the range of temperature of 298.15 K to 24000 K. The physical properties of various kinds of partially ionized plasma depend mainly of their composition and temperature. The composition of particular kinds of partially ionized plasmas varies also in the function of temperature. Simultaneous going on of physical and chemical processes in plasma is the reason of difficulties in the calculations of plasma's physical properties. The use of the laws of macroscopic thermodynamics for the calculations of physical properties of partially ionized plasma is impossible. There are enough exact methods for measuring of physical properties of partially ionized plasma. For these reasons the theoretical method using the base of statistic physics was used to calculate the composition and physical properties of various kinds of partially ionized plasma. (author) 2 refs., 2 figs

  19. Effect of annealing temperature on the mechanical properties of Zircaloy-4 cladding

    International Nuclear Information System (INIS)

    Beauregard, R.J.; Clevinger, G.S.; Murty, K.L.

    1977-01-01

    The mechanical properties of Zircaloy cladding materials are sensitive to those fabrication variables which have an effect on the preferred crystallographic orientation or texture of the finished tube. The effect of one such variable, the final annealing temperature, on various mechanical properties is examined using tube reduced Zircaloy-4 fuel rod cladding annealed at temperatures from 905F to 1060F. This temperature range provides cladding with varying degrees of recrystallization including full recrystallization. The burst strength of the cladding at 650F decreased with the annealing temperature reaching a saturation value at approximately 1000F. The total circumferential elongation increased with the annealing temperature reaching a maximum at approximately 1000F and decreasing at higher temperatures. Hoop creep characteristics of Zircaloy cladding were studied as a function of the annealing temperature using closed-end internal pressurization tests at 750F and hoop stresses of 10, 15, 20 and 25 ksi. The effect of annealing temperature on the room temperature mechanical anisotropy parameters, R and P, was studied. The R-parameter was essentially independent of the annealing temperature while the P-parameter increased with annealing temperature. The mechanical anisotropy parameters were also studied as a function of the test temperature from ambient to approximately 800F using continuously monitored high precision extensometry. (Auth.)

  20. Microstructure and Room-Temperature Mechanical Properties of FeCrMoVTi x High-Entropy Alloys

    Science.gov (United States)

    Guo, Jun; Huang, Xuefei; Huang, Weigang

    2017-07-01

    FeCrMoVTi x ( x values represent the molar ratio, where x = 0, 0.5, 1.0, 1.5, and 2.0) high-entropy alloys were prepared by a vacuum arc melting method. The effects of Ti element on the microstructure and room-temperature mechanical properties of the as-cast FeCrMoVTi x alloys were investigated. The results show that the prepared alloys exhibited typical dendritic microstructure and the size of the microstructure became fine with increasing Ti content. The FeCrMoV alloy exhibited a single body-centered cubic structure (BCC1) and the alloys prepared with Ti element exhibited BCC1 + BCC2 mixed structure. The new BCC2 phase is considered as (Fe, Ti)-rich phase and was distributed in the dendrite region. With the increase of Ti content, the volume fraction of the BCC2 phase increased and its shape changed from a long strip to a network. For the FeCrMoV alloy, the fracture strength, plastic strain, and hardness reached as high as 2231 MPa, 28.2%, and 720 HV, respectively. The maximum hardness of 887 HV was obtained in the FeCrMoVTi alloy. However, the fracture strength, yield stress, and plastic strain of the alloys decreased continuously as Ti content increased. In the room-temperature compressive test, the alloys showed typical brittle fracture characteristics.

  1. The mechanical properties of fluoride salts at elevated temperatures. [candidate thermal energy storage materials for solar dynamic systems

    Science.gov (United States)

    Raj, S. V.; Whittenberger, J. D.

    1989-01-01

    The deformation behavior of CaF2 and LiF single crystals compressed in the 111 and the 100 line directions, respectively, are compared with the mechanical properties of polycrystalline LiF-22 (mol pct) CaF2 eutectic mixture in the temperature range 300 to 1275 K for strain rates varying between 7 x 10 to the -7th and 0.2/s. The true stress-strain curves for the single crystals were found to exhibit three stages in an intermediate range of temperatures and strain rates, whereas those for the eutectic showed negative work-hardening rates after a maximum stress. The true stress-strain rate data for CaF2 and LiF-22 CaF2 could be represented by a power-law relation with the strain rate sensitivities lying between 0.05 and 0.2 for both materials. A similar relation was found to be unsatisfactory in the case of LiF.

  2. Optical power limiting and transmitting properties of cadmium iodide single crystals: Temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M. Idrish, E-mail: m.miah@griffith.edu.a [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)] [Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)] [Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

    2009-09-14

    Optical limiting properties of the single crystals of cadmium iodide are investigated using ns laser pulses. It is found that the transmissions in the crystals increase with increasing temperature. However, they limit the transmissions at high input powers. The limiting power is found to be higher at higher temperature. From the measured transmission data, the photon absorption coefficients are estimated. The temperature dependence of the coefficients shows a decrease in magnitude with increasing temperature. This might be due to the temperature-dependent bandgap shift of the material. The results demonstrate that the cadmium iodide single crystals are promising materials for applications in optical power limiting devices.

  3. Optical power limiting and transmitting properties of cadmium iodide single crystals: Temperature dependence

    International Nuclear Information System (INIS)

    Miah, M. Idrish

    2009-01-01

    Optical limiting properties of the single crystals of cadmium iodide are investigated using ns laser pulses. It is found that the transmissions in the crystals increase with increasing temperature. However, they limit the transmissions at high input powers. The limiting power is found to be higher at higher temperature. From the measured transmission data, the photon absorption coefficients are estimated. The temperature dependence of the coefficients shows a decrease in magnitude with increasing temperature. This might be due to the temperature-dependent bandgap shift of the material. The results demonstrate that the cadmium iodide single crystals are promising materials for applications in optical power limiting devices.

  4. Microstructure and anisotropy of the mechanical properties in commercially pure titanium after equal channel angular pressing with back pressure at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Jäger, A., E-mail: jager@fzu.cz; Gärtnerova, V.; Tesař, K.

    2015-09-17

    In this work, we report on the anisotropy of the mechanical properties and the results of in-depth microstructural analysis of commercially pure (CP) grade 2 titanium after severe plastic deformation. CP-Ti was successfully processed at room temperature via four consecutive passes of equal channel angular pressing (ECAP) with very high back pressure (BP). An ECAP-BP die with circular channel cross-section, channel angle φ=90° and arc curvature angle ψ=0° was used. A sub-microcrystalline structure with a grain size of ~150 nm exhibits promising mechanical properties, as determined by hardness measurements and tensile and compression tests in different directions. We observed a significant mechanical anisotropy related to the strong texture. Considering the ID, ED and TD to be the insert, extrusion and transverse directions of the ECAP die, respectively, the highest compression strength was attained for samples with the major axis in the ID and in a direction inclined 22.5° from the ID toward the TD (σ{sub max}~1150 MPa). In contrast, the lowest strength was observed in the ED and at 45° from the ID toward the ED (σ{sub max}~940 MPa). Although a fracture occurred during compression of the samples tested along the ID, compression along the ED exhibited perfect plasticity with balanced hardening and softening mechanisms. Transmission electron microscopy (TEM) examination after ECAP-BP revealed a small amount of high-pressure hexagonal ω-phase. The occurrence of this phase was induced by a combination of severe plastic deformation and high pressure.

  5. Effects of temperature on structure and mechanical properties of alkanethiol coated gold nanoparticle membranes

    Science.gov (United States)

    Salerno, K. Michael; Grest, Gary

    2015-03-01

    Single-nanoparticle-thick membranes have a variety of potential uses due to unique mechanical properties. While these membranes have been studied experimentally and computationally at 300K, the effects of thermal annealing on structure and properties have not been investigated. We present atomistic molecular dynamics simulations that study the effects of temperature on nanoparticle membrane properties. Nanoparticles are made of a gold core coated with organic oligomer ligands. At high grafting density, ligands with CH3 end groups exhibit local crystallinity at 300K while those with COOH end groups orient to form dimers due to electrostatics. Both features influence membrane mechanical properties. As temperature increases ligand crystallinity and COOH affinity are disrupted, and mechanical strength is reduced. Immediately after cooling back to 300K, membranes are weaker and measures of ligand interdigitation and COOH affinity are reduced. Over time, interdigitation and end-group interactions rejuvenate and samples that undergo high-temperature annealing have mechanical properties comparable to the original membranes. The structure/property temperature dependence points to ways that membranes could be tailored for temperature-dependent/resistant properties. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's NNSA under Contract DE-AC04-94AL85000.

  6. The influence of high and low temperatures on the impact properties of glass–epoxy composites

    Directory of Open Access Journals (Sweden)

    SLAVISA PUTIC

    2007-07-01

    Full Text Available The aim of this paper is to present the influence of high and low temperatures on the impact properties glass–epoxy composites. The impact strength an is presented for four different glass–epoxy composite structures at three different temperatures, i.e., at room temperature t = 20 °C, at an elevated temperature t = +50 °C and at a low temperature t = –50 °C. Standard mechanical testing was carried out on the composite materials with specific masses of reinforcement of 210 g m-2 and 550 g m-2 and orientations 0°/90° and ±45°. Micromechanical analysis of the failure was performed in order to determine real models and mechanisms of crack and temperature influence on the impact properties.

  7. Optical emission, shock-induced opacity, temperatures, and melting of Gd3Ga5O12 single crystals shock-compressed from 41 to 290 GPa

    Science.gov (United States)

    Zhou, Xianming; Nellis, William J.; Li, Jiabo; Li, Jun; Zhao, Wanguang; Liu, Xun; Cao, Xiuxia; Liu, Qiancheng; Xue, Tao; Wu, Qiang; Mashimo, T.

    2015-08-01

    Strong oxides at high shock pressures have broad crossovers from elastic solids at ambient to failure by plastic deformation, to heterogeneous deformation to weak solids, to fluid-like solids that equilibrate thermally in a few ns, to melting and, at sufficiently high shock pressures and temperatures, to metallic fluid oxides. This sequence of crossovers in single-crystal cubic Gd3Ga5O12 (Gd-Ga Garnet-GGG) has been diagnosed by fast emission spectroscopy using a 16-channel optical pyrometer in the spectral range 400-800 nm with bandwidths per channel of 10 nm, a writing time of ˜1000 ns and time resolution of 3 ns. Spectra were measured at shock pressures from 40 to 290 GPa (100 GPa = 1 Mbar) with corresponding gray-body temperatures from 3000 to 8000 K. Experimental lifetimes were a few 100 ns. Below 130 GPa, emission is heterogeneous and measured temperatures are indicative of melting temperatures in grain boundary regions rather than bulk temperatures. At 130 GPa and 2200 K, GGG equilibrates thermally and homogeneously in a thin opaque shock front. This crossover has a characteristic spectral signature in going from partially transmitting shock-heated material behind the shock front to an opaque shock front. Opacity is caused by optical scattering and absorption of light generated by fast compression. GGG melts at ˜5000 K in a two-phase region at shock pressures in the range 200 GPa to 217 GPa. Hugoniot equation-of-state data were measured by a Doppler Pin SystemDPS with ps time resolution and are generally consistent with previous data. Extrapolation of previous electrical conductivity measurements indicates that GGG becomes a poor metal at a shock pressure above ˜400 GPa. Because the shock impedance of GGG is higher than that of Al2O3 used previously to make metallic fluid H (MFH), the use of GGG to make MFH will achieve higher pressures and lower temperatures than use of Al2O3. However, maximum dynamic pressures at which emission temperatures of fluid

  8. Low temperature electrical and photo-responsive properties of MoSe2

    DEFF Research Database (Denmark)

    Fan, Chao; Yue, Qu; Yang, Juehan

    2014-01-01

    MoSe2 was fabricated by a facile hydrothermal method, and a simple device based on it was prepared to investigate the low temperature electrical and photo-responsive (PR) properties. PR current of MoSe2 under 650 nm red illumination is 2.55 × 10−5 A and remains approximately at low temperatures, ...

  9. The role of mixing temperature on microstructure and rheological properties of butter blends

    DEFF Research Database (Denmark)

    Buldo, Patrizia; Wiking, Lars

    2012-01-01

    The present study demonstrated that the rheological properties of butter blends can be modified by the applied mixing temperature. Blends were prepared by mixing 10 or 25% of rapeseed oil (RO) with butter, at three different temperatures (13, 18 and 23 °C). Afterwards the blends were stored at 5 ...

  10. Finite-temperature properties of multiferroic BiFeO3

    DEFF Research Database (Denmark)

    Kornev, Igor; Lisenkov, S; Haumont, R

    2007-01-01

    An effective Hamiltonian scheme is developed to study finite-temperature properties of multiferroic BiFeO3. This approach reproduces very well (i) the symmetry of the ground state, (ii) the Néel and Curie temperatures, and (iii) the intrinsic magnetoelectric coefficients (that are very weak...

  11. Effect of thickness and temperature of copper phthalocyanine films on their properties

    Directory of Open Access Journals (Sweden)

    Alieva Kh. S.

    2012-06-01

    Full Text Available The research has shown that copper phthalocyanine films, having a set of unique properties, can be successfully used as gas-sensitive coating of resistive structures. The thickness of the film, in contrast to its temperature, is not the determining factor for high sensitivity. Low operating temperature of structures with copper phthalocyanine films allows to exploit them in economy mode.

  12. Existence domain of the compressive ion acoustic super solitary wave in a two electron temperature warm multi-ion plasma

    Science.gov (United States)

    Steffy, S. V.; Ghosh, S. S.

    2017-10-01

    The transition of an ion acoustic solitary wave into a "supersoliton," or a super solitary wave have been explored in a two electron temperature warm multi-ion plasma using the Sagdeev pseudopotential technique. It is generally believed that the ion acoustic solitary wave can be transformed to a super solitary wave only through a double layer. The present work shows that the transition route of an ion acoustic solitary wave to a super solitary wave is not unique. Depending on the electron temperature ratio, a regular solitary wave may transform to a super solitary wave either via the double layer, or through an extra-nonlinear solitary structure whose morphology differs from that of a regular one. These extra-nonlinear structures are associated with a fluctuation of the charge separation within the potential profile and are named as "variable solitary waves." Depending on these analyses, the upper and lower bounds of a super solitary wave have been deciphered and its existence domain has been delineated in the parametric space. It reveals that super solitary waves are a subset of a more generalized class of extra-nonlinear solitary structures called variable solitary waves.

  13. Selfconsistent calculations of mesonic properties at nonzero temperature

    International Nuclear Information System (INIS)

    Roeder, D.

    2005-01-01

    The main focus of my thesis is QCD and its phase transitions. In chapter II, I present a study about the phase transition temperature of QCD, and its dependence on the quark (or pion) mass. In the first part of this chapter, I use the linear σ-model with O(N) symmetry, which links the transition to chiral symmetry restoration. In the second part of this chapter, I use the Polyakov-loop model, which links the transition to the restoration of Z(N c ) symmetry. The aim of this part is to find how 'strong' one has to break the Z(3) symmetry in order to reproduce the transition temperature (given by lattice QCD calculations). In chapter III, I present a study about the improvement of the standard Hartree-Fock approximation by including nonzero decay width effects. In the standard Hartree-Fock approximation only real-valued tadpole diagrams are taken into account. I improve this scheme by taking additionally into account the cut sunset diagrams, which have a real and an imaginary part. The Dyson-Schwinger equations for the full propagators and the condensate equations become integral equations one has to solve on an energy-momentum grid. In this chapter, my focus is to study the influence of the inclusion of nonzero decay width effects. Finally, in chapter IV, I present a work to study the effects of the 4-momentum dependent real parts of the cut sunset diagrams in the linear σ-model width O(N) symmetry. Besides the effects of the real part of the cut sunset diagram, I study in this chapter the influence of the 'choice' of the vacuum mass of the σ-meson. (orig.)

  14. Thermoelectric properties of high electron concentration materials under large temperature gradients

    International Nuclear Information System (INIS)

    Bulat, L.P.; Stefansky, V.A.

    1994-01-01

    Theoretical methods of investigating of transport properties in solids under large temperature gradients are grounded. The nonlinear and non-local expressions for current density and heat flow are obtained with degenerated of current carriers gas. A number of new effects with large temperature gradients have been tested. Use of large temperature gradients leads to the increasing of the thermoelectric figure of merit. copyright 1995 American Institute of Physics

  15. Electromagnetic properties of terbium gallium garnet at millikelvin temperatures and single photon energy

    OpenAIRE

    Kostylev, Nikita; Goryachev, Maxim; Bushev, Pavel; Tobar, Michael E.

    2017-01-01

    Electromagnetic properties of single crystal terbium gallium garnet (TGG) are characterised from room down to millikelvin temperatures using the whispering gallery mode method. Microwave spectroscopy is performed at low powers equivalent to a few photons in energy and conducted as functions of the magnetic field and temperature. A phase transition is detected close to the temperature of 3.5 K. This is observed for multiple whispering gallery modes causing an abrupt negative frequency shift an...

  16. Hydrodynamic Properties of High Temperature Natural Circulating Helium Cooling Loop

    Directory of Open Access Journals (Sweden)

    Dzianik František

    2017-04-01

    Full Text Available The paper deals with the hydrodynamic properties, i.e. the consumption of mechanical energy expressed by pressure drops within a helium loop intended for the testing of decay heat removal (DHR from the model of a gas-cooled fast reactor (GFR. The system is characterised by the natural circulation of helium, as a coolant, and assume steady operating conditions of circulation. The helium loop consists of four main components: model of gas-cooled fast reactor, model of the heat exchanger for decay heat removal, hot piping branch and cold piping branch. Using the process hydrodynamic calculations, the pressure drops of circulating helium within the main components of the helium loop were determined. The calculations have been done for several defined operating conditions which correspond to the different helium flow rates within the system.

  17. Temperature Dependence of Mechanical Properties of TRISO SiC Coatings

    International Nuclear Information System (INIS)

    Kim, Do Kyung; Park, Kwi Il; Lee, Hyeon Keun; Seong, Young Hoon; Lee, Seung Jun

    2009-04-01

    SiC coating layer has been introduced as protective layer in TRISO nuclear fuel particle of high temperature gas cooled reactor (HTGR) due to excellent mechanical stability at high temperature. It is important to study for high temperature stability in SiC coating layers, because TRISO fuel particles were operating at high temperature around 1000 .deg. C. In this study, the nanoindentation test and micro tensile test were conducted in order to measure the mechanical properties of SiC coating layers at elevated temperature. SiC coating film was fabricated on the carbon substrate using chemical vapor deposition process with different microstructures and thicknesses. Nanoindentation test was performed for the analysis of the hardness, modulus and creep properties up to 500 .deg. C. Impression creep method applied to nanoindentation and creep properties of SiC coating layers were characterized by nanoindentation creep test. The fracture strength of SiC coating layers was measured by the micro tensile method at room temperature and 500 .deg. C. From the results, we can conclude that the hardness and fracture strength are decreased with temperature and no significant change in the modulus is observed with increase in temperature. The deformation mechanism for indentation creep and creep rate changes as the testing temperature increased

  18. Development of evaluation method of high temperature mechanical properties of TRISO SiC coating layers

    International Nuclear Information System (INIS)

    Kim, Do Kyung; Lee, Hyeon Keun; Kim, Dong Seok; Lee, Ji Seok; Park, Kwi Il

    2010-05-01

    SiC coating layer has been introduced as protective layer in TRISO nuclear fuel particle of high temperature gas cooled reactor (HTGR) due to excellent mechanical stability at high temperature. It is important to study for high temperature stability in SiC coating layers, because TRISO fuel particles were operating at high temperature around 1000 .deg. C. In this study, the nanoindentation test and micro tensile test were conducted in order to measure the mechanical properties of SiC coating layers at elevated temperature. SiC coating film was fabricated on the carbon substrate using chemical vapor deposition process with different microstructures and thicknesses. Nanoindentation test was performed for the analysis of the hardness, modulus and creep properties up to 500 .deg. C. Impression creep method applied to nanoindentation and creep properties of SiC coating layers were characterized by nanoindentation creep test. The fracture strength of SiC coating layers was measured by the micro tensile method at room temperature and 500 .deg. C. From the results, we can conclude that the hardness and fracture strength are decreased with temperature and no significant change in the modulus is observed with increase in temperature. The deformation mechanism for indentation creep and creep rate changes as the testing temperature increased

  19. Temperature-dependent dynamic mechanical properties of magnetorheological elastomers under magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Benxiang, E-mail: jubenxiang@qq.com [National Instrument Functional Materials Engineering Technology Research Center, Chongqing 400707 (China); Tang, Rui; Zhang, Dengyou; Yang, Bailian [National Instrument Functional Materials Engineering Technology Research Center, Chongqing 400707 (China); Yu, Miao; Liao, Changrong [College of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)

    2015-01-15

    Both anisotropic and isotropic magnetorheological elastomer (MRE) samples were fabricated by using as-prepared polyurethane (PU) matrix and carbonyl iron particles. Temperature-dependent dynamic mechanical properties of MRE were investigated and analyzed. Due to the unique structural features of as-prepared matrix, temperature has a greater impact on the properties of as-prepared MRE, especially isotropic MRE. With increasing of temperature and magnetic field, MR effect of isotropic MRE can reach up to as high as 4176.5% at temperature of 80 °C, and the mechanism of the temperature-dependent in presence of magnetic field was discussed. These results indicated that MRE is a kind of temperature-dependent material, and can be cycled between MRE and MR plastomer (MRP) by varying temperature. - Highlights: • Both anisotropic and isotropic MRE were fabricated by using as-prepared matrix. • Temperature-dependent properties of MRE under magnetic field were investigated. • As-prepared MRE can transform MRE to MRP by adjusting temperature.

  20. A Review of the Thermodynamic, Transport, and Chemical Reaction Rate Properties of High-temperature Air

    Science.gov (United States)

    Hansen, C Frederick; Heims, Steve P

    1958-01-01

    Thermodynamic and transport properties of high temperature air, and the reaction rates for the important chemical processes which occur in air, are reviewed. Semiempirical, analytic expressions are presented for thermodynamic and transport properties of air. Examples are given illustrating the use of these properties to evaluate (1) equilibrium conditions following shock waves, (2) stagnation region heat flux to a blunt high-speed body, and (3) some chemical relaxation lengths in stagnation region flow.