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Sample records for flexible specific-heat ratio

  1. Lattice Boltzmann Scheme associated with flexible Prandtl number and specific heat ratio based on the polyatomic ES-BGK model

    CERN Document Server

    Hu, Kainan; Zhang, Hongwu

    2016-01-01

    A lattice Boltzmann scheme associated with flexible Prandtl number and specific heat ratio is proposed, which is based on the polyatomic ellipsoidal statistics model(ES-BGK). The Prandtl number can be modified by a parameter of the Gaussian distribution and the specific heat ratio can be modified by additional free degrees. For the sake of constructing the scheme proposed, the Gaussian distribution is expanded on the Hermite polynomials and the general term formula for the Hermite coefficients of the Gaussian distribution is deduced. Benchmarks are carried out to verify the scheme proposed. The numerical results are in good agreement with the the analytical solutions.

  2. Flux Limiter Lattice Boltzmann Scheme Approach to Compressible Flows with Flexible Specific-Heat Ratio and Prandtl Number

    Institute of Scientific and Technical Information of China (English)

    甘延标; 许爱国; 张广财; 李英骏

    2011-01-01

    We further develop the lattice Boltzmann (LB) model [Physica A 382 (2007) 502] for compressible flows from two aspects. Firstly, we modify the Bhatnagar Gross Krook (BGK) collision term in the LB equation, which makes the model suitable for simulating flows with different Prandtl numbers. Secondly, the flux limiter finite difference (FLFD) scheme is employed to calculate the convection term of the LB equation, which makes the unphysical oscillations at discontinuities be effectively suppressed and the numerical dissipations be significantly diminished. The proposed model is validated by recovering results of some well-known benchmarks, including (i) The thermal Couette flow; (ii) One- and two-dlmenslonal FLiemann problems. Good agreements are obtained between LB results and the exact ones or previously reported solutions. The flexibility, together with the high accuracy of the new model, endows the proposed model considerable potential for tracking some long-standing problems and for investigating nonlinear nonequilibrium complex systems.

  3. Variation of the ratio of specific heats across a detached bow shock

    Science.gov (United States)

    Chao, J. K.; Wiskerchen, M. J.

    1974-01-01

    Equations are derived which allow the ratio of specific heats behind the earth's bow shock to be evaluated if several pre-shock parameters (the specific-heat ratio, the Alfvenic Mach number, the sonic Mach number, and the angle between the shock normal at the stagnation point and the magnetic field) and the density jump across the shock are known. Numerical examples show that the dependence of the post-shock ratio on the pre-shock ratio is weak.

  4. On the averaging of ratios of specific heats in a multicomponent planetary atmosphere

    Science.gov (United States)

    Dubisch, R.

    1974-01-01

    The use of adiabatic relations in the calculation of planetary atmospheres requires knowledge of the ratio of specific heats of a mixture of gases under various pressure and temperature conditions. It is shown that errors introduced by simple averaging of the ratio of specific heats in a multicomponent atmosphere can be roughly 0.4%. Therefore, the gamma-averaging error can become important when integrating through the atmosphere to a large depth.

  5. A new scheme based on the Hermite expansion to construct lattice Boltzmann models associated with arbitrary specific heat ratio

    CERN Document Server

    Hu, Kainan; Geng, Shaojuan

    2016-01-01

    A new lattice Boltzmann scheme associated with flexible specific heat ratio is proposed. The new free degree is introduced via the internal energy associated with the internal structure. The evolution equation of the distribution function is reduced to two evolution equations. One is connected to the density and velocity, the other is of the energy. A two-dimensional lattice Boltzmann model and a three-dimensional lattice Boltzmann model are derived via the Hermite expansion. The two lattice Boltzmann models are applied to simulating the shock tube of one dimension. Good agreement between the numerical results and the analytical solutions are obtained.

  6. Reconsideration on the role of the specific heat ratio in Arrhenius law applications

    Institute of Scientific and Technical Information of China (English)

    Yunfeng Liu; Zonglin Jiang

    2008-01-01

    Arrhenius law implicates that only those molecules which possess the internal energy greater than the activation energy Ea can react. However, the internal energy will not be proportional to the gas temperature if the specific heat ratio y and the gas constant R vary during chemical reaction processes. The varying y may affect significantly the chemical reaction rate calculated with the Arrhenius law under the constant y assumption, which has been widely accepted in detonation and combustion simulations for many years. In this paper, the roles of variable y and R in Arrhenius law applications are reconsidered, and their effects on the chemical reaction rate are demonstrated by simulating one-dimensional C-J and two-dimensional cellular detonations. A new overall one-step detonation model with variable y and R is proposed to improve the Arrhenius law. Numerical experiments demonstrate that this improved Arrhenius law works well in predicting detonation phenomena with the numerical results being in go agreement with experimental data.

  7. Constant-Pressure Specific Heat to Hemispherical Total Emissivity Ratio for Undercooled Liquid Nickel, Zirconium, and Silicon

    Science.gov (United States)

    Rulison, Aaron J.; Rhim, Won-Kyu

    1995-01-01

    Radiative cooling curves of nickel, zirconium, and silicon melts that were obtained using the high-temperature, high-vacuum electrostatic levitator (HTHVESL) have been analyzed to determine the ratio between the constant-pressure specific heat and the hemispherical total emissivity, c(sub p)(T)epsilon(sub T)(T). This ratio determined over a wide liquid temperature range for each material allows us to determine c(sub p)(T) if epsilon(sub T)(T) is known or vice versa. Following the recipe, the hemi-spherical total emissivities for each sample at its melting temperature, epsilon(sub T)(T(sub M)), have been determined using c(sub p)(T(sub m)) values available in the literature. They are 0.15, 0.29, and 0.17, for Ni, Zr, and Si, respectively.

  8. Pressure data from a 64A010 airfoil at transonic speeds in heavy gas media of ratio of specific heats from 1.67 to 1.12

    Science.gov (United States)

    Gross, A. R.; Steinle, F. W., Jr.

    1975-01-01

    A NACA 64A010 pressure-instrumented airfoil was tested at transonic speeds over a range of angle of attack from -1 to 12 degrees at various Reynolds numbers ranging from 2 to 6 million in air, argon, Freon 12, and a mixture of argon and Freon 12 having a ratio of specific heats corresponding to air. Good agreement of results is obtained for conditions where compressibility is not significant and for the air and comparable argon-Freon 12 mixture. Comparison of heavy gas results with air, when adjusted for transonic similarity, show improved, but less than desired agreement.

  9. An Experimental Parametric Study of Geometric, Reynolds Number, and Ratio of Specific Heats Effects in Three-Dimensional Sidewall Compression Scramjet Inlets at Mach 6

    Science.gov (United States)

    Holland, Scott D.; Murphy, Kelly J.

    1993-01-01

    Since mission profiles for airbreathing hypersonic vehicles such as the National Aero-Space Plane include single-stage-to-orbit requirements, real gas effects may become important with respect to engine performance. The effects of the decrease in the ratio of specific heats have been investigated in generic three-dimensional sidewall compression scramjet inlets with leading-edge sweep angles of 30 and 70 degrees. The effects of a decrease in ratio of specific heats were seen by comparing data from two facilities in two test gases: in the Langley Mach 6 CF4 Tunnel in tetrafluoromethane (where gamma=1.22) and in the Langley 15-Inch Mach 6 Air Tunnel in perfect gas air (where gamma=1.4). In addition to the simulated real gas effects, the parametric effects of cowl position, contraction ratio, leading-edge sweep, and Reynolds number were investigated in the 15-Inch Mach 6 Air Tunnel. The models were instrumented with a total of 45 static pressure orifices distributed on the sidewalls and baseplate. Surface streamline patterns were examined via oil flow, and schlieren videos were made of the external flow field. The results of these tests have significant implications to ground based testing of inlets in facilities which do not operate at flight enthalpies.

  10. The ratio of specific heats for postshock plasmas of a detached bow shock - An MHD model. [in solar wind-earth interaction

    Science.gov (United States)

    Chao, J. K.; Wiskerchen, M. J.

    1974-01-01

    The empirical relationship between the standoff distance of a detached bow shock (generated by the flow of a supersonic gas past an impenetrable obstacle), the size of the obstacle, the Mach number of the gas, and the ratio of specific heats has been generalized to include the magnetic field. The value of the ratio of specific heats (gamma-prime) in the postshock plasma has been calculated in terms of the preshock Alfvenic and sonic Mach numbers and orientation of the magnetic field. The empirical relationship is further generalized by taking into consideration the normal momentum and energy flux due to waves and/or turbulence and/or heat flow in association with high Mach number shocks. The computed value of gamma prime is substantially modified in comparison with that given by the MHD or the gas dynamic model. For this generalized model the computed gamma prime can be considered to be a more precise thermodynamic quantity, since the macroscopic parameters of the plasma have been separated out. Application of this empirical relationship to the earth's bow shock has been given.

  11. A decoupled scheme based on the Hermite expansion to construct lattice Boltzmann models for the compressible Navier-Stokes equations with arbitrary specific heat ratio

    CERN Document Server

    Hu, Kainan; Geng, Shaojuan

    2016-01-01

    A decoupled scheme based on the Hermite expansion to construct lattice Boltzmann models for the compressible Navier-Stokes equations with arbitrary specific heat ratio is proposed. The local equilibrium distribution function including the rotational velocity of particle is decoupled into two parts, i.e. the local equilibrium distribution function of the translational velocity of particle and that of the rotational velocity of particle. From these two local equilibrium functions, two lattice Boltzmann models are derived via the Hermite expansion, namely one is in relation to the translational velocity and the other is connected with the rotational velocity. Accordingly, the distribution function is also decoupled. After this, the evolution equation is decoupled into the evolution equation of the translational velocity and that of the rotational velocity. The two evolution equations evolve separately. The lattice Boltzmann models used in the scheme proposed by this work are constructed via the Hermite expansion...

  12. Flexible Conversion Ratio Fast Reactor Systems Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Neil Todreas; Pavel Hejzlar

    2008-06-30

    Conceptual designs of lead-cooled and liquid salt-cooled fast flexible conversion ratio reactors were developed. Both concepts have cores reated at 2400 MWt placed in a large-pool-type vessel with dual-free level, which also contains four intermediate heat exchanges coupling a primary coolant to a compact and efficient supercritical CO2 Brayton cycle power conversion system. Decay heat is removed passively using an enhanced Reactor Vessel Auxiliary Cooling System and a Passive Secondary Auxiliary Cooling System. The most important findings were that (1) it is feasible to design the lead-cooled and salt-cooled reactor with the flexible conversion ratio (CR) in the range of CR=0 and CR=1 n a manner that achieves inherent reactor shutdown in unprotected accidents, (2) the salt-cooled reactor requires Lithium thermal Expansion Modules to overcme the inherent salt coolant's large positive coolant temperature reactivity coefficient, (3) the preferable salt for fast spectrum high power density cores is NaCl-Kcl-MgCl2 as opposed to fluoride salts due to its better themal-hydraulic and neutronic characteristics, and (4) both reactor, but attain power density 3 times smaller than that of the sodium-cooled reactor.

  13. vdW气体比热容比与音速关系的理论研究%A Theoretical Study on Relation between Specific Heat Capacity Ratio of VDW Gas and Sonic Speed

    Institute of Scientific and Technical Information of China (English)

    陈漓

    2012-01-01

    The relation between specific heat capacity ratio of vdW gas and sonic speed is analyzed and derived by thermodynamics relation and is compared, analyzed with the value from experimental determination and specific heat capacity ratio of ideal gas. The relation curve between specific heat capacity ratio and temperature is developed by using simulation technique of Matlab and the reasons why the coincident degree between specific heat capacity ratio of vdW gas and real gas is better than the specific heat capacity ratio of ideal gas are provided in the paper.%通过热力学关系分析和导出vdW气体的比热容比与音速的关系式,将它与实验测定的数值以及理想气体比热容比进行对比分析,并运用Matlab仿真技术绘制出比热容比与温度的关系曲线,进而说明vdW气体比热容比与实际气体比热容比吻合的程度好于理想气体的比热容比.

  14. Measurement of Gas Specific Heat Ratio using Pulse Signal Timer%用脉冲信号计时器测量气体比热容比

    Institute of Scientific and Technical Information of China (English)

    刘万林; 刘凌飞; 袁辉; 陈东生

    2013-01-01

    The principle and method of measuring gas specific heat ratio were described mainly using self-made photoelectric gate with computer auxiliary,when the light path of photoelectric gate is blocked by a small ball,will generate an electrical pulse from the photosensitive tube,we could use a computer sound card with audition software to capture the pulse,in order to achieve the measurement of ball vibration cycle,improve the accuracy.%主要说明用自制光电门配合计算机辅助测量气体比热容比的原理和方法,当小球挡住光电门的光路时,会使光敏管产生一个电脉冲,可以利用计算机声卡配合audition软件捕捉这个脉冲,从而实现小球振动周期的测量,提高实验的精确度。

  15. Decoupled scheme based on the Hermite expansion to construct lattice Boltzmann models for the compressible Navier-Stokes equations with arbitrary specific heat ratio.

    Science.gov (United States)

    Hu, Kainan; Zhang, Hongwu; Geng, Shaojuan

    2016-10-01

    A decoupled scheme based on the Hermite expansion to construct lattice Boltzmann models for the compressible Navier-Stokes equations with arbitrary specific heat ratio is proposed. The local equilibrium distribution function including the rotational velocity of particle is decoupled into two parts, i.e., the local equilibrium distribution function of the translational velocity of particle and that of the rotational velocity of particle. From these two local equilibrium functions, two lattice Boltzmann models are derived via the Hermite expansion, namely one is in relation to the translational velocity and the other is connected with the rotational velocity. Accordingly, the distribution function is also decoupled. After this, the evolution equation is decoupled into the evolution equation of the translational velocity and that of the rotational velocity. The two evolution equations evolve separately. The lattice Boltzmann models used in the scheme proposed by this work are constructed via the Hermite expansion, so it is easy to construct new schemes of higher-order accuracy. To validate the proposed scheme, a one-dimensional shock tube simulation is performed. The numerical results agree with the analytical solutions very well.

  16. Decoupled scheme based on the Hermite expansion to construct lattice Boltzmann models for the compressible Navier-Stokes equations with arbitrary specific heat ratio

    Science.gov (United States)

    Hu, Kainan; Zhang, Hongwu; Geng, Shaojuan

    2016-10-01

    A decoupled scheme based on the Hermite expansion to construct lattice Boltzmann models for the compressible Navier-Stokes equations with arbitrary specific heat ratio is proposed. The local equilibrium distribution function including the rotational velocity of particle is decoupled into two parts, i.e., the local equilibrium distribution function of the translational velocity of particle and that of the rotational velocity of particle. From these two local equilibrium functions, two lattice Boltzmann models are derived via the Hermite expansion, namely one is in relation to the translational velocity and the other is connected with the rotational velocity. Accordingly, the distribution function is also decoupled. After this, the evolution equation is decoupled into the evolution equation of the translational velocity and that of the rotational velocity. The two evolution equations evolve separately. The lattice Boltzmann models used in the scheme proposed by this work are constructed via the Hermite expansion, so it is easy to construct new schemes of higher-order accuracy. To validate the proposed scheme, a one-dimensional shock tube simulation is performed. The numerical results agree with the analytical solutions very well.

  17. Specific heats of degenerate ideal gases

    OpenAIRE

    Caruso, Francisco; Oguri, Vitor; Silveira, Felipe

    2017-01-01

    From arguments based on Heisenberg's uncertainty principle and Pauli's exclusion principle, the molar specific heats of degenerate ideal gases at low temperatures are estimated, giving rise to values consistent with the Nerst-Planck Principle (third law of Thermodynamics). The Bose-Einstein condensation phenomenon based on the behavior of specific heat of massive and non-relativistic boson gases is also presented.

  18. MEASUREMENT OF SPECIFIC HEAT CAPACITY OF SALTSTONE

    Energy Technology Data Exchange (ETDEWEB)

    Harbour, J; Vickie Williams, V

    2008-09-29

    {approx} 55% higher than the previous measurement of specific heat capacity on a reference Saltstone mix in 1997. Values of mixes prepared using Deliquification, Dissolution and Adjustment (DDA), Modular Caustic Side Solvent Extraction Unit (MCU) and Salt Waste Processing Facility (SWPF) simulants and premix at 0.60 w/cm ratio were {approx} 1.95 J/g/{sup o}C and were equivalent within experimental error. The simple law of mixtures was used to predict the heat capacities of the Saltstone and the results were in excellent agreement with experimental data. This simple law of mixtures can therefore be used to predict the heat capacities of Saltstone mixes in those cases where measurements have not been made. The time dependence of the heat capacity is important as an input to the modeling of temperature increase in Saltstone vaults. The heat capacity of a mix of MCU and premix at 0.60 w/cm ratio was measured immediately after initial mixing and then periodically up to times greater than 100 days. Within experimental error, the heat capacity did not change with time. Therefore, the modeling is not complicated by requiring a time dependent function for specific heat capacity. The water to cementitious material (w/cm) ratio plays a key role in determining the value of the heat capacity. Both experimental and predictive values for SWPF mixes as function of the w/cm ratio were obtained and presented in this report. Predictions of the maximum temperatures of the Saltstone mixes were made using the heat of hydration data from previous isothermal measurements and the newly measured heat capacities for DDA, MCU and SWPF mixes. The maximum temperature increase ranged from 37 to 48 C for these mixes. The presence of aluminate at 0.33 M produced a temperature increase of 68 C which is close to the adiabatic temperature rise of 74 C observed by Steimke and Fowler in 1997 for a mix containing 0.35 M aluminate. Aluminum dissolution of the sludge will increase the aluminate in the DSS which

  19. Specific heat and thermal conductivity of nanomaterials

    Science.gov (United States)

    Bhatt, Sandhya; Kumar, Raghuvesh; Kumar, Munish

    2017-01-01

    A model is proposed to study the size and shape effects on specific heat and thermal conductivity of nanomaterials. The formulation developed for specific heat is based on the basic concept of cohesive energy and melting temperature. The specific heat of Ag and Au nanoparticles is reported and the effect of size and shape has been studied. We observed that specific heat increases with the reduction of particle size having maximum shape effect for spherical nanoparticle. To provide a more critical test, we extended our model to study the thermal conductivity and used it for the study of Si, diamond, Cu, Ni, Ar, ZrO2, BaTiO3 and SrTiO3 nanomaterials. A significant reduction is found in the thermal conductivity for nanomaterials by decreasing the size. The model predictions are consistent with the available experimental and simulation results. This demonstrates the suitability of the model proposed in this paper.

  20. Measuring Specific Heats at High Temperatures

    Science.gov (United States)

    Vandersande, Jan W.; Zoltan, Andrew; Wood, Charles

    1987-01-01

    Flash apparatus for measuring thermal diffusivities at temperatures from 300 to 1,000 degrees C modified; measures specific heats of samples to accuracy of 4 to 5 percent. Specific heat and thermal diffusivity of sample measured. Xenon flash emits pulse of radiation, absorbed by sputtered graphite coating on sample. Sample temperature measured with thermocouple, and temperature rise due to pulse measured by InSb detector.

  1. Effect of tip vortices on membrane vibration of flexible wings with different aspect ratios

    Directory of Open Access Journals (Sweden)

    Genç Mustafa Serdar

    2016-01-01

    Full Text Available In this study, the effect of the aspect ratio on the aerodynamics characteristic of flexible membrane wings with different aspect ratios (AR = 1 and AR = 3 is experimentally investigated at Reynolds number of 25000. Time accurate measurements of membrane deformation using Digital Image Correlation system (DIC is carried out while normal forces of the wing will be measured by helping a load-cell system and flow on the wing was visualized by means of smoke wire technic. The characteristics of high aspect ratio wings are shown to be affected by leading edge separation bubbles at low Reynolds number. It is concluded that the camber of membrane wing excites the separated shear layer and this situation increases the lift coefficient relatively more as compared to rigid wings. In membrane wings with low aspect ratio, unsteadiness included tip vortices and vortex shedding, and the combination of tip vortices and vortex shedding causes complex unsteady deformations of these membrane wings. The characteristic of high aspect ratio wings was shown to be affected by leading edge separation bubbles at low Reynolds numbers whereas the deformations of flexible wing with low aspect ratio affected by tip vortices and leading edge separation bubbles.

  2. Thickness ratio and d 33 effects on flexible piezoelectric unimorph energy conversion

    Science.gov (United States)

    Ha, Taewoo; Zhang, John X. J.; Lu, Nanshu

    2016-03-01

    Piezoelectric unimorphs are bilayer structures where a blanket piezoelectric film (with top and bottom electrodes) is uniformly laminated on an inactive but flexible substrate. Because of their simple construction and flexibility, unimorphs are widely used as a key element in flexible sensors and actuators. The response of a unimorph is governed by the material properties of the film and the substrate as well as their geometric parameters. For low frequency biological energy harvesting, structural optimization is critical due to the dimensional confinement imposed by curvilinear and deformable bio-tissues. Here we report a comprehensive theoretical framework to investigate the effects of the film-to-substrate thickness ratio on voltage, charge, and energy outputs when the unimorph is subjected to eight different boundary/loading conditions. A broad class of power generators can be designed using such a framework under the assumption that the unimorph length is very large compared to its thickness, where the only dimensionless variable is the film-to-substrate thickness ratio. We show that the analytical and finite element modeling results are in excellent agreement. For not so thin unimorphs, there is non-zero normal stress in the thickness direction (σ 3) and d 33 can play a significant role in this case. Non-monotonic dependence of voltage and energy generation on thickness ratio has been found in some cases and optimum thickness ratio for unimorph generator can be predicted. When the unimorph is actuated by voltage applied across the piezo-film thickness, non-monotonic maximum deflection versus thickness ratio is also found. This work provides new physical insights on unimorphs and analytical solutions that can be used for the structural design and optimization of unimorphs under different boundary/loading conditions.

  3. Flexibility.

    Science.gov (United States)

    Humphrey, L. Dennis

    1981-01-01

    Flexibility is an important aspect of all sports and recreational activities. Flexibility can be developed and maintained by stretching exercises. Exercises designed to develop flexibility in ankle joints, knees, hips, and the lower back are presented. (JN)

  4. Optimization of structural parameters for spatial flexible redundant manipulators with maximum ratio of load to mass

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xu-ping; YU Yue-qing

    2005-01-01

    Optimization of structural parameters aimed at improving the load carrying capacity of spatial flexible redundant manipulators is presented in this paper. In order to increase the ratio of load to mass of robots, the cross-sectional parameters and constructional parameters are optimized respectively. The cross-sectional and configurational parameters are optimized simultaneously. The numerical simulation of a 4R spatial manipulator is performed. The results show that the load capacity of robots has been greatly improved through the optimization strategies proposed in this paper.

  5. Pairing and specific heat in hot nuclei

    CERN Document Server

    Gambacurta, Danilo; Sandulescu, Nicu

    2013-01-01

    The thermodynamics of pairing phase-transition in nuclei is studied in the canonical ensemble and treating the pairing correlations in a finite-temperature variation after projection BCS approach (FT-VAP). Due to the restoration of particle number conservation, the pairing gap and the specific heat calculated in the FT-VAP approach vary smoothly with the temperature, indicating a gradual transition from the superfluid to the normal phase, as expected in finite systems. We have checked that the predictions of the FT-VAP approach are very accurate when compared to the results obtained by an exact diagonalization of the pairing Hamiltonian. The influence of pairing correlations on specific heat is analysed for the isotopes $^{161,162}$Dy and $^{171,172}$Yb. It is shown that the FT-VAP approach, applied with a level density provided by mean field calculations and supplemented, at high energies, by the level density of the back-shifted Fermi gas model, can approximate reasonably well the main properties of specifi...

  6. Very low temperature specific heat of Al 5056

    Energy Technology Data Exchange (ETDEWEB)

    Barucci, M. [INFN, Section of Florence, Via G. Sansone 1, 50019 Sesto Fiorentino, Florence (Italy); Department of Physics, University of Florence, Via G. Sansone 1, 50019 Sesto Fiorentino, Florence (Italy); Ligi, C. [INFN -Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, I 00044 Frascati (Italy); Lolli, L. [INFN, Section of Florence, Via G. Sansone 1, 50019 Sesto Fiorentino, Florence (Italy); Department of Physics, University of Florence, Via G. Sansone 1, 50019 Sesto Fiorentino, Florence (Italy); Marini, A. [INFN - Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, I 00044 Frascati (Italy); Martelli, V., E-mail: martelliv@fi.infn.i [INFN, Section of Florence, Via G. Sansone 1, 50019 Sesto Fiorentino, Florence (Italy); LENS, University of Florence, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Risegari, L.; Ventura, G. [INFN, Section of Florence, Via G. Sansone 1, 50019 Sesto Fiorentino, Florence (Italy); Department of Physics, University of Florence, Via G. Sansone 1, 50019 Sesto Fiorentino, Florence (Italy)

    2010-03-15

    The transition temperature from normal to superconducting state and the specific heat of Al 5056 aluminium alloy in the 0.1-3.6K temperature range have been measured. This alloy is largely used in resonant detectors of gravitational waves. A comparison with specific heat data of the same material obtained by different measuring methods is given.

  7. Calculation of Specific Heat for Aluminium Thin Films

    Institute of Scientific and Technical Information of China (English)

    LU Yao; SONG Qing-Lin; XIA Shan-Hong

    2005-01-01

    @@ We employ Prasher's non-dimensional form to analyse the size effects on specific heat of Al thin films. Compared the calculation results of pure aluminium film with the experimental data, it is found that the reduction of phonon states is not the main reason of the size effect on the specific heat Al thin films with thickness from 10hm to 370nm. However, the Al thin film in air usually has an oxidation layer and the specific heat of the layer is smaller than Al. By including the contribution of the oxidation layer to the thin-film specific heat, the calculation results are much closer to the experimental data. This may be a possible reason of the size effects on specific heat of Al thin films.

  8. Specific Heat in a Typical Metallic Glass Former

    Institute of Scientific and Technical Information of China (English)

    KE Hai-Bo; ZHAO Zuo-Feng; WEN Ping; WANG Wei-Hua

    2012-01-01

    The specific heat in a typical Pd40Ni10Cu30P20 metallic glass forming system is investigated.It is found that the specific heat of the metallic liquid is around 4.7R (R is the gas constant) and that it is almost independent of temperature.The glass transition observed during cooling is accompanied by a decrease in the specific heat of 1.5R.The specific heat of the metallic glass is similar to that of its crystalline phases,contributed mainly from atomic vibrations.Combined with the results of the structural relaxation and diffusivities,we demonstrate an intrinsic connection between the atomic motion and the specific heat in the metallic glass-forming liquid.The results support the idea that glass transition is a process accompanied by the freezing of most of the atomic transitional motions in a metallic supercooled liquid during cooling.%The specific heat in a typical Pd40 Ni10 Cu30 P20 metallic glass forming system is investigated. It is found that the specific heat of the metallic liquid is around 4.7R (R is the gas constant) and that it is almost independent of temperature. The glass transition observed during cooling is accompanied by a decrease in the specific heat of 1.5R. The specific heat of the metallic glass is similar to that of its crystalline phases, contributed mainly from atomic vibrations. Combined with the results of the structural relaxation and diffusivities, we demonstrate an intrinsic connection between the atomic motion and the specific heat in the metallic glass-forming liquid. The results support the idea that glass transition is a process accompanied by the freezing of most of the atomic transitional motions in a metallic supercooled liquid during cooling.

  9. Flexible Self-Powered GaN Ultraviolet Photoswitch with Piezo-Phototronic Effect Enhanced On/Off Ratio.

    Science.gov (United States)

    Peng, Mingzeng; Liu, Yudong; Yu, Aifang; Zhang, Yang; Liu, Caihong; Liu, Jingyu; Wu, Wei; Zhang, Ke; Shi, Xieqing; Kou, Jinzong; Zhai, Junyi; Wang, Zhong Lin

    2016-01-26

    Flexible self-powered sensing is urgently needed for wearable, portable, sustainable, maintenance-free and long-term applications. Here, we developed a flexible and self-powered GaN membrane-based ultraviolet (UV) photoswitch with high on/off ratio and excellent sensitivity. Even without any power supply, the driving force of UV photogenerated carriers can be well boosted by the combination of both built-in electric field and piezoelectric polarization field. The asymmetric metal-semiconductor-metal structure has been elaborately utilized to enhance the carrier separation and transport for highly sensitive UV photoresponse. Its UV on/off ratio and detection sensitivity reach to 4.67 × 10(5) and 1.78 × 10(12) cm·Hz(0.5) W(1-), respectively. Due to its excellent mechanical flexibility, the piezoelectric polarization field in GaN membrane can be easily tuned/controlled based on piezo-phototronic effect. Under 1% strain, a stronger and broader depletion region can be obtained to further enhance UV on/off ratio up to 154%. As a result, our research can not only provide a deep understanding of local electric field effects on self-powered optoelectronic detection, but also promote the development of self-powered flexible optoelectronic devices and integrated systems.

  10. Specific heat of erbium from 0. 4 to 23 K

    Energy Technology Data Exchange (ETDEWEB)

    Hill, R.W.; Cosier, J.; Hukin, D.A. (Oxford Univ. (UK). Clarendon Lab.)

    1984-05-01

    New measurements are reported which show substantial agreement with published values below 1 K and above 15 K, but very large differences at intermediate temperatures, the new values being smaller. Analysis of the results shows that (i) the hyperfine specific heat is consistent with the results of nuclear magnetic resonance experiments, (ii) the electronic specific heat coefficient ..gamma..=10+-0.2 mJ mol/sup -1/ K/sup -2/, and (iii) the ferromagnetic-antiferromagnetic transition temperature is 19.2 K. The temperature dependence of the magnetic specific heat below 7 K appears to be anomalously rapid.

  11. Changes of aerobic capacity, fat ratio and flexibility in older TCC practitioners: a five-year follow-up.

    Science.gov (United States)

    Lan, Ching; Chen, Ssu-Yuan; Lai, Jin-Shin

    2008-01-01

    The objective of this study was to evaluate the 5-year changes of aerobic capacity, fat ratio and flexibility in older Tai Chi Chuan (TCC) practitioners and sedentary controls. Sixty-nine community-dwelling elderly individuals (mean age: 68.6 +/- 6.3 years) completed this study. The TCC group (18 M; 17 F) had been practicing TCC regularly for 6.3 +/- 3.7 years at baseline and continued training in the study interval. The control group (16 M; 18 F) did not participate in any regular exercise program. A graded bicycle exercise testing was conducted at the baseline and at 5-year to evaluate the age-related decline in aerobic capacity. Triceps and subscapular skinfolds, and thoracolumbar flexibility were also measured. At baseline, the TCC group displayed higher peak oxygen uptake $({\\dot{\\rm V}}{\\rm O}_{2{\\rm peak}})$ and thoraolumbar flexibility, and lower fat ratio than the control group. At the 5-year follow-up, the TCC group displayed a smaller decrease in $\\dot{\\rm V}{\\rm O}_{2{\\rm peak}}$ than the sedentary group. The annual decrease of $\\dot{\\rm V}{\\rm O}_{2{\\rm peak}}$ in TCC men and women was 0.32 and 0.22 ml . kg(-1) . min(-1), respectively. In the control group, the annual decrease of $\\dot{\\rm V}{\\rm O}_{2{\\rm peak}}$ was 0.50 and 0.36 ml . kg(-1) . min(-1) in men and women, respectively. The TCC group also showed a smaller increase of body fat ratio, and a less decrease of flexibility than the control group. In conclusion, long-term practice of TCC attenuates the age-related decline of aerobic capacity, and it also reduces the increase of body fat ratio in older individuals. TCC may be prescribed as a conditioning exercise for the elderly to maintain their health fitness.

  12. Specific heat anomaly in relaxor ferroelectrics and dipolar glasses

    Science.gov (United States)

    Kutnjak, Z.; Pirc, R.

    2017-03-01

    The temperature and electric field dependence of the specific heat of relaxor ferroelectrics and dipolar glasses is investigated by means of a Landau-type theoretical model. It is shown that the dipolar specific heat, which is due to the randomly interacting polar nanoregions in relaxors and electric dipoles in dipolar glasses, is negative in a temperature region below the permittivity maximum. Also, it follows that for sufficiently low values of the field, where the induced polarization shows a quasi linear field dependence, the dipolar specific heat is proportional to the second temperature derivative of the dielectric polarization. This quantity can be extracted from the experimental temperature profile of the polarization, thus enabling an indirect experimental estimate of the negative specific heat, which is demonstrated for a set of representative relaxor and dipolar glass systems.

  13. Some remarks on non-extensive specific heat properties

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez-Ramirez, Jose [Division de Ciencias Basicas e Ingenieria, Universidad Autonoma Metropolitana-Iztapalapa, Apartado Postal 55-534, Mexico DF 09340 (Mexico); Valdes-Parada, Fracisco J. [Division de Ciencias Basicas e Ingenieria, Universidad Autonoma Metropolitana-Iztapalapa, Apartado Postal 55-534, Mexico DF 09340 (Mexico)]. E-mail: iqfv@xanum.uam.mx; Ochoa-Tapia, J. Alberto [Division de Ciencias Basicas e Ingenieria, Universidad Autonoma Metropolitana-Iztapalapa, Apartado Postal 55-534, Mexico DF 09340 (Mexico)

    2005-09-26

    The aim of this Letter is to describe some relevant properties of specific heat derived from non-extensive statistics approach. It is shown that in the high- and low-temperature limits, the non-extensive specific heat displays the Dulong-Petit classical value 3R and a T{sup 3}-dependence, respectively. The latter property implies, that in a strict sense, the non-extensive statistics approach can be unable to explain anomalous low-temperature behavior.

  14. High Aspect Ratio Microstructures in Flexible Printed Circuit Boards : Process and Applications

    OpenAIRE

    Yousef, Hanna

    2008-01-01

    Flexible printed circuit boards (flex PCBs) are used in a wide range of electronic devices today due to their light weight, bendability, extensive wiring possibilities, and low-cost manufacturing techniques. The general trend in the flex PCB industry is further miniaturization alongside increasing functionality per device and reduced costs. To meet these demands, a new generation of low cost manufacturing technologies is being developed to enable structures with smaller lateral dimensions and...

  15. A novel large thrust-weight ratio V-shaped linear ultrasonic motor with a flexible joint.

    Science.gov (United States)

    Li, Xiaoniu; Yao, Zhiyuan; Yang, Mojian

    2017-06-01

    A novel large thrust-weight ratio V-shaped linear ultrasonic motor with a flexible joint is proposed in this paper. The motor is comprised of a V-shaped transducer, a slider, a clamp, and a base. The V-shaped transducer consists of two piezoelectric beams connected through a flexible joint to form an appropriate coupling angle. The V-shaped motor is operated in the coupled longitudinal-bending mode. Longitudinal and bending movements are transferred by the flexible joint between the two beams. Compared with the coupled longitudinal-bending mode of the single piezoelectric beam or the symmetrical and asymmetrical modes of the previous V-shaped transducer, the coupled longitudinal-bending mode of the V-shaped transducer with a flexible joint provides higher vibration efficiency and more convenient mode conformance adjustment. A finite element model of the V-shaped transducer is created to numerically study the influence of geometrical parameters and to determine the final geometrical parameters. In this paper, three prototypes were then fabricated and experimentally investigated. The modal test results match well with the finite element analysis. The motor mechanical output characteristics of three different coupling angles θ indicate that V-90 (θ = 90°) is the optimal angle. The mechanical output experiments conducted using the V-90 prototype (Size: 59.4 mm × 30.7 mm × 4 mm) demonstrate that the maximum unloaded speed is 1.2 m/s under a voltage of 350 Vpp, and the maximum output force is 15 N under a voltage of 300 Vpp. The proposed novel V-shaped linear ultrasonic motor has a compact size and a simple structure with a large thrust-weight ratio (0.75 N/g) and high speed.

  16. Contribution to the PV-to-inverter sizing ratio determination using a custom flexible experimental setup

    OpenAIRE

    Camps, Xavier; Velasco Quesada, Guillermo; Hoz Casas, Jordi de la; Martín Cañadas, María Elena

    2015-01-01

    This work presents a novel approach to the experimental validation of the optimal PV-to-inverter sizing ratio value for the energy yield maximization of a GCPVS by means the implementation of a custom workbench using a solar array simulator which has allowed to replicate a wide variety of technical configurations and environmental data. The compliance between the experimental setup and the mathematical model developed to simulate the optimal PV-to-inverter sizing ratio value was demonstrated ...

  17. Fluctuation-dissipation theorem for frequency-dependent specific heat

    DEFF Research Database (Denmark)

    Dyre, Jeppe; Nielsen, Johannes K.

    1996-01-01

    A derivation of the fluctuation-dissipation (FD) theorem for the frequency-dependent specific heat of a system described by a master equation is presented. The FD theorem is illustrated by a number of simple examples, including a system described by a linear Langevin equation, a two-level system......, and a system described by the energy master equation. It is shown that for two quite different models with low-energy cutoffs—a collection of two-level systems and a system described by the energy master equation—the frequency-dependent specific heat in dimensionless units becomes universal at low temperatures......, i.e., independent of both energy distribution and temperature. These two models give almost the same universal frequency-dependent specific heat, which compares favorably to experiments on supercooled alcohols....

  18. Dynamic specific heat of frustrated Ising spin rings

    CERN Document Server

    Ismail, G

    2003-01-01

    The dynamic specific heat C(omega) is calculated exactly for rings of six coupled Ising spins within Glauber dynamics. We used the response of the internal energy to small temperature oscillations to find C(omega). The spin glass (SG) and disordered ferromagnetic (DFM) rings showed here have four energy minima and thus four diverging relaxation times in the time evolution of magnetization and three such times in the evolution of energy. The properties of the real and imaginary parts of dynamic specific heat are investigated for different temperatures and frequencies. The dynamic susceptibility is affected by the longest relaxing mode while the dynamic specific heat is not. Our results confirm that C(omega) is sensitive only to rapidly relaxing processes for ferromagnetic (FM) and anti-ferromagnetic (AFM) cases. (Author)

  19. Specific heat properties of polariton modes in quasicrystals

    Science.gov (United States)

    Mauriz, P. W.; Albuquerque, E. L.; Vasconcelos, M. S.

    2001-05-01

    We investigate the thermodynamical properties of plasmon polaritons that propagate in multiple semiconductor layers arranged in a quasiperiodical fashion. This quasiperiodicity can be of the so-called deterministic (or controlled) disorder type, i.e., they are neither random nor periodic. Also, they are characterized by the nature of their Fourier spectrum, which can be dense pure point (Fibonacci sequence) or singular continuous (Thue-Morse sequence). The sequences are described in terms of a series of generations that obey peculiar recursion relations. We present both analytical and numerical studies on the temperature dependence of the polariton's specific heat associated with the generation number n=1,2,3,... for their multiscale fractal energy spectra. We show that when T-->0, the specific heat displays oscillations and when T-->∞, the specific heat goes to zero with T-2 (because the energy spectrum considered is bounded).

  20. 3 omega method for specific heat and thermal conductivity measurements

    CERN Document Server

    Lü, L; Zhang, D L

    2001-01-01

    We present a 3 omega method for simultaneously measuring the specific heat and thermal conductivity of a rod- or filament-like specimen using a way similar to a four-probe resistance measurement. The specimen in this method needs to be electrically conductive and with a temperature-dependent resistance, for acting both as a heater to create a temperature fluctuation and as a sensor to measure its thermal response. With this method we have successfully measured the specific heat and thermal conductivity of platinum wire specimens at cryogenic temperatures, and measured those thermal quantities of tiny carbon nanotube bundles some of which are only 10^-9 g in mass.

  1. Level Statistics and Specific Heat of Metallic Nano-Particles

    Institute of Scientific and Technical Information of China (English)

    程南璞; 陈志谦; 陈洪

    2003-01-01

    The thermodynamic properties of an ensemble of metallic nano-particles are affected by the level distribution and the level correlation between the discrete electronic energy levels. We numerically calculate the specific heat of metallic nano-particles in the canonical ensemble with an odd or even number of electrons by considering the effects of the level distribution and the level correlation. The behaviour of the specific heat at low and high temperatures, compared with the average nearest-neighbour level spacing, is also investigated.

  2. Specific heat of a non-local attractive Hubbard model

    Energy Technology Data Exchange (ETDEWEB)

    Calegari, E.J., E-mail: eleonir@ufsm.br [Laboratório de Teoria da Matéria Condensada, Departamento de Física, UFSM, 97105-900, Santa Maria, RS (Brazil); Lobo, C.O. [Laboratório de Teoria da Matéria Condensada, Departamento de Física, UFSM, 97105-900, Santa Maria, RS (Brazil); Magalhaes, S.G. [Instituto de Física, Universidade Federal Fluminense, Av. Litorânea s/n, 24210, 346, Niterói, Rio de Janeiro (Brazil); Chaves, C.M.; Troper, A. [Centro Brasileiro de Pesquisas Físicas, Rua Xavier Sigaud 150, 22290-180, Rio de Janeiro, RJ (Brazil)

    2013-10-01

    The specific heat C(T) of an attractive (interaction G<0) non-local Hubbard model is investigated within a two-pole approximation that leads to a set of correlation functions, which play an important role as a source of anomalies as the pseudogap. For a giving range of G and n{sub T} (where n{sub T}=n{sub ↑}+n{sub ↓}), the specific heat as a function of the temperature presents a two peak structure. Nevertehelesss, the presence of a pseudogap eliminates the two peak structure. The effects of the second nearest-neighbor hopping on C(T) are also investigated.

  3. Specific Heat, Charge Release and Dielectric Constant of PZT Ceramics

    NARCIS (Netherlands)

    Cereceda, N.; Noheda, B.; Gonzalo, J.A.; Mielcarek, S.; Mroz, B.

    1998-01-01

    Dielectric constant, specific heat and charge release measurements have been performed to study the FRL-FRH and FRH-PC phase transitions in Zr rich PZT (PbZr1-xTixO3). Both transitions have been described together by means of a two order parameters effective field model, in order to include the

  4. Specific heat of the simple-cubic Ising model

    NARCIS (Netherlands)

    Feng, X.; Blöte, H.W.J.

    2010-01-01

    We provide an expression quantitatively describing the specific heat of the Ising model on the simple-cubic lattice in the critical region. This expression is based on finite-size scaling of numerical results obtained by means of a Monte Carlo method. It agrees satisfactorily with series expansions

  5. Anomalous Specific Heat around Ferromagnetic Instability in Metals

    Science.gov (United States)

    Ishigaki, Aya; Moriya, Tôru

    1996-02-01

    The low-temperature specific heat around the ferromagnetic instability is studied by using the self-consistent renormalization (SCR) theory of spin fluctuations with particular attention to the crossover between the Fermi liquid (γT+ηT3ln T+···) and the quantum critical (-Tln T) regimes.

  6. Measurement of the specific heat capacity of graphite

    Energy Technology Data Exchange (ETDEWEB)

    Picard, S.; Burns, D.T.; Roger, P

    2006-01-15

    With the objective of implementing graphite calorimetry at the BIPM to measure absorbed dose, an experimental assembly has recently been constructed to measure the specific heat capacity of graphite. A status description of the apparatus and results from the first measurements are given. The outcome is discussed and the experimental uncertainty is reviewed. (authors)

  7. Experimental validation of damping properties and solar pressure effects on flexible, high area-to-mass ratio debris model

    Science.gov (United States)

    Channumsin, Sittiporn; Ceriotti, Matteo; Radice, Gianmarco; Watson, Ian

    2017-09-01

    Multilayer insulation (MLI) is a recently-discovered type of debris originating from delamination of aging spacecraft; it is mostly detected near the geosynchronous orbit (GEO). Observation data indicates that these objects are characterised by high reflectivity, high area-to-mass ratio (HAMR), fast rotation, high sensitivity to perturbations (especially solar radiation pressure) and change of area-to-mass ratio (AMR) over time. As a result, traditional models (e.g. cannonball) are unsuitable to represent and predict this debris' orbital evolution. Previous work by the authors effectively modelled the flexible debris by means of multibody dynamics to improve the prediction accuracy. The orbit evolution with the flexible model resulted significantly different from using the rigid model. This paper aims to present a methodology to determine the dynamic properties of thin membranes with the purpose to validate the deformation characteristics of the flexible model. A high-vacuum chamber (10-4 mbar) to significantly decrease air friction, inside which a thin membrane is hinged at one end but free at the other provides the experimental setup. A free motion test is used to determine the damping characteristics and natural frequency of the thin membrane via logarithmic decrement and frequency response. The membrane can swing freely in the chamber and the motion is tracked by a static, optical camera, and a Kalman filter technique is implemented in the tracking algorithm to reduce noise and increase the tracking accuracy of the oscillating motion. Then, the effect of solar radiation pressure on the thin membrane is investigated: a high power spotlight (500-2000 W) is used to illuminate the sample and any displacement of the membrane is measured by means of a high-resolution laser sensor. Analytic methods from the natural frequency response and Finite Element Analysis (FEA) including multibody simulations of both experimental setups are used for the validation of the

  8. Flexible C : N ratio enhances metabolism of large phytoplankton when resource supply is intermittent

    Directory of Open Access Journals (Sweden)

    D. Talmy

    2014-04-01

    Full Text Available Phytoplankton cell size influences particle sinking rate, food web interactions and biogeographical distributions. We present a model in which the uptake, storage and assimilation of nitrogen and carbon are explicitly resolved in different sized phytoplankton cells. In the model, metabolism and cellular C : N ratio are influenced by accumulation of carbon polymers such as carbohydrate and lipid, which is greatest when cells are nutrient starved, or exposed to high light. Allometric relations and empirical datasets are used to constrain the range of possible C : N, and indicate larger cells can accumulate significantly more carbon storage compounds than smaller cells. When forced with extended periods of darkness combined with brief exposure to saturating irradiance, the model predicts organisms large enough to accumulate significant carbon reserves may on average synthesize protein and other functional apparatus up to five times faster than smaller organisms. The advantage of storage in terms of average daily protein synthesis rate is greatest when modeled organisms were previously nutrient starved, and carbon storage reservoirs saturated. Small organisms may therefore be at a disadvantage in terms of average daily growth rate in environments that involve prolonged periods of darkness and intermittent nutrient limitation. We suggest this mechanism is a significant constraint on phytoplankton C : N variability and cell size distribution in different oceanic regimes.

  9. Flexible C : N ratio enhances metabolism of large phytoplankton when resource supply is intermittent

    Directory of Open Access Journals (Sweden)

    D. Talmy

    2014-09-01

    Full Text Available Phytoplankton cell size influences particle sinking rate, food web interactions and biogeographical distributions. We present a model in which the uptake, storage and assimilation of nitrogen and carbon are explicitly resolved in different-sized phytoplankton cells. In the model, metabolism and cellular C : N ratio are influenced by the accumulation of carbon polymers such as carbohydrate and lipid, which is greatest when cells are nutrient starved, or exposed to high light. Allometric relations and empirical data sets are used to constrain the range of possible C : N, and indicate that larger cells can accumulate significantly more carbon storage compounds than smaller cells. When forced with extended periods of darkness combined with brief exposure to saturating irradiance, the model predicts organisms large enough to accumulate significant carbon reserves may on average synthesize protein and other functional apparatus up to five times faster than smaller organisms. The advantage of storage in terms of average daily protein synthesis rate is greatest when modeled organisms were previously nutrient starved, and carbon storage reservoirs saturated. Small organisms may therefore be at a disadvantage in terms of average daily growth rate in environments that involve prolonged periods of darkness and intermittent nutrient limitation. We suggest this mechanism is a significant constraint on phytoplankton C : N variability and cell size distribution in different oceanic regimes.

  10. Gust load alleviation wind tunnel tests of a large-aspect-ratio flexible wing with piezoelectric control

    Directory of Open Access Journals (Sweden)

    Ying Bi

    2017-02-01

    Full Text Available An active control technique utilizing piezoelectric actuators to alleviate gust-response loads of a large-aspect-ratio flexible wing is investigated. Piezoelectric materials have been extensively used for active vibration control of engineering structures. In this paper, piezoelectric materials further attempt to suppress the vibration of the aeroelastic wing caused by gust. The motion equation of the flexible wing with piezoelectric patches is obtained by Hamilton’s principle with the modal approach, and then numerical gust responses are analyzed, based on which a gust load alleviation (GLA control system is proposed. The gust load alleviation system employs classic proportional-integral-derivative (PID controllers which treat piezoelectric patches as control actuators and acceleration as the feedback signal. By a numerical method, the control mechanism that piezoelectric actuators can be used to alleviate gust-response loads is also analyzed qualitatively. Furthermore, through low-speed wind tunnel tests, the effectiveness of the gust load alleviation active control technology is validated. The test results agree well with the numerical results. Test results show that at a certain frequency range, the control scheme can effectively alleviate the z and x wingtip accelerations and the root bending moment of the wing to a certain extent. The control system gives satisfying gust load alleviation efficacy with the reduction rate being generally over 20%.

  11. Nodal effects on the electronic specific heat of anisotropic superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Perez, Luis A. [Departamento de Fisica Quimica, Instituto de Fisica, Universidad Nacional Autonoma de Mexico, C.P. 01000, Mexico D.F. (Mexico)], E-mail: lperez@fisica.unam.mx; Samuel Millan, J. [Facultad de Ingenieria, Universidad Autonoma del Carmen, C.P. 24180, Cd. del Carmen, Campeche (Mexico); Wang Chumin [Insituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, C.P. 04510, Mexico D.F. (Mexico)

    2008-04-01

    Based on the BCS formalism, the electronic specific heat of d-symmetry superconducting states is studied. This study is performed on a square lattice described by a generalized Hubbard model, in which correlated-hopping interactions are included in addition to the repulsive Coulomb ones. Instead of the exponential temperature dependence for the s-channel, the results show second and higher power-law behaviors for d-wave superconducting specific heat, depending on the angular dependence of the single-excitation energy gap occurred at different carrier concentrations. The results of this study could help to understand a variety of power-law behaviors observed in La{sub 2-x}Sr{sub x}CuO{sub 4} superconductors.

  12. The 55 K specific heat anomaly in palladium hydride

    Science.gov (United States)

    Jacobi, N.; Vaughan, R. W.

    1976-01-01

    A specific heat anomaly in PdH and PdD has been observed by Aston et al. (1957) close to 55 K. Its position was found to be independent of hydrogen concentration and its magnitude to be linear in hydrogen concentration. Ferguson's (1965) and Brodowsky's (1972) explanations of the anomaly are shown to be unsatisfactory. This is true also for the detailed mechanical statistical model proposed by Staford and McLellan (1974) for interstitial solid solutions of hydrogen in transition metals. It is shown that Gopal's (1966) simple Schottky model of specific heat anomaly, which considers a system of several levels with Boltzmann statistics, provides much better agreement with experiment than the more elaborate models, both in magnitude and in predicting a linear dependence on hydrogen concentration.

  13. Study on the specific heat of wood by statistical mechanics

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    From the microstructure of wood, theoretical expressions of the wood specific heat were derived by statistical mechanics. With the theoretical expressions derived, the theoretical values of specific heat for 33 tree species, with different moisture contents and under varied temperature conditions were calculated and comparison was also made to the experimental values under the same conditions. The results showed that the maximum error and mean error by the theoretical expressions of this paper are only 7.8% and 2.5% respectively, while those error of the theoretical values for 33 tree species calculated with Dunlap's empiric equation were 15.2% (max.) and 9.3% (mean), and forКириллов empiric equation, they were 20% (max.) and 11% (mean).

  14. Non-additive model for specific heat of electrons

    Science.gov (United States)

    Anselmo, D. H. A. L.; Vasconcelos, M. S.; Silva, R.; Mello, V. D.

    2016-10-01

    By using non-additive Tsallis entropy we demonstrate numerically that one-dimensional quasicrystals, whose energy spectra are multifractal Cantor sets, are characterized by an entropic parameter, and calculate the electronic specific heat, where we consider a non-additive entropy Sq. In our method we consider an energy spectra calculated using the one-dimensional tight binding Schrödinger equation, and their bands (or levels) are scaled onto the [ 0 , 1 ] interval. The Tsallis' formalism is applied to the energy spectra of Fibonacci and double-period one-dimensional quasiperiodic lattices. We analytically obtain an expression for the specific heat that we consider to be more appropriate to calculate this quantity in those quasiperiodic structures.

  15. Specific Heat Properties of Proton Transfer in Hydrogen Bonded Systems

    Institute of Scientific and Technical Information of China (English)

    庞小峰; 封原平

    2003-01-01

    The thermodynamic properties of proton transport along hydrogen-bonded systems at finite temperatures have been studied by our model. We first derive the dynamic equations of the proton transport and find the solutions and the free energy of the systems. Finally, we obtain the specific heats of the hydrogen bonded systems, resulting from the motion of the soliton, by using transfer integral way. The theoretical value is basically consistent with the experimental data.

  16. On the specific heat capacity enhancement in nanofluids.

    Science.gov (United States)

    Hentschke, Reinhard

    2016-12-01

    Molten salts are used as heat transfer fluids and for short-term heat energy storage in solar power plants. Experiments show that the specific heat capacity of the base salt may be significantly enhanced by adding small amounts of certain nanoparticles. This effect, which is technically interesting and economically important, is not yet understood. This paper presents a critical discussion of the existing attendant experimental literature and the phenomenological models put forward thus far. A common assumption, the existence of nanolayers surrounding the nanoparticles, which are thought to be the source of, in some cases, the large increase of a nanofluid's specific heat capacity is criticized and a different model is proposed. The model assumes that the influence of the nanoparticles in the surrounding liquid is of long range. The attendant long-range interfacial layers may interact with each other upon increase of nanoparticle concentration. This can explain the specific heat maximum observed by different groups, for which no other theoretical explanation appears to exist.

  17. Low temperature specific heat of glasses: a non-extensive approach

    OpenAIRE

    Razdan, Ashok

    2005-01-01

    Specific heat is calculated using Tsallis statistics. It is observed that it is possible to explain some low temperature specific heat properties of glasses using non-extensive approach. A similarity between temperature dependence of non-extensive specific heat and fractal specific heat is also discussed.

  18. Can the frequency-dependent specific heat be measured by thermal effusion methods?

    OpenAIRE

    Christensen, Tage; Olsen, Niels Boye; Dyre, Jeppe C.

    2007-01-01

    It has recently been shown that plane-plate heat effusion methods devised for wide-frequency specific-heat spectroscopy do not give the isobaric specific heat, but rather the so-called longitudinal specific heat. Here it is shown that heat effusion in a spherical symmetric geometry also involves the longitudinal specific heat.

  19. Estimating thermal diffusivity and specific heat from needle probe thermal conductivity data

    Science.gov (United States)

    Waite, W.F.; Gilbert, L.Y.; Winters, W.J.; Mason, D.H.

    2006-01-01

    Thermal diffusivity and specific heat can be estimated from thermal conductivity measurements made using a standard needle probe and a suitably high data acquisition rate. Thermal properties are calculated from the measured temperature change in a sample subjected to heating by a needle probe. Accurate thermal conductivity measurements are obtained from a linear fit to many tens or hundreds of temperature change data points. In contrast, thermal diffusivity calculations require a nonlinear fit to the measured temperature change occurring in the first few tenths of a second of the measurement, resulting in a lower accuracy than that obtained for thermal conductivity. Specific heat is calculated from the ratio of thermal conductivity to diffusivity, and thus can have an uncertainty no better than that of the diffusivity estimate. Our thermal conductivity measurements of ice Ih and of tetrahydrofuran (THF) hydrate, made using a 1.6 mm outer diameter needle probe and a data acquisition rate of 18.2 pointss, agree with published results. Our thermal diffusivity and specific heat results reproduce published results within 25% for ice Ih and 3% for THF hydrate. ?? 2006 American Institute of Physics.

  20. The modification of existing Bai Bithaman Ajil (BBA) instrument by using the concept of qardhul hassan and flexible sharing ratio

    Science.gov (United States)

    Rajak, Abd Aziz Arrashid Abd; Halim, Nurfadhlina Abdul; Jaaman @ Sharman, Saiful Hafizah

    2017-08-01

    Bai Bithaman Ajil (BBA) instrument as the main mode of financing has become the biggest leap in the revolution of real estate purchase. Through many years of developing and refining its usage in financial institutions, BBA has confronted several argumentation and debate among scholars on its conformity towards Shariah. Although there are cases of inconsistency findings when it comes to conformity towards Shariah, BBA is still one of the predominant, accepted mode of financing especially in Malaysia. Therefore, this paper will prove that BBA instrument using the approach of Constant Rate of Return (CRR) is mathematically identical to the conventional approach which is annuity. Besides, this paper will also provide the amortization of CRR. It is proven that CRR formula is likely based on the amortization of conventional approach. Besides, this paper discusses mainly on the incompliance of BBA towards Shariah and hence will introduce the proxy for BBA instruments by implementing profit-loss sharing (PLS). The modified BBA instrument is develop by deliberating the concept of qardhul hassan as its principal payment and as for its rental payment will introduce the sharing ratio to represent the ownership of bank and customers in every periodic payments by using flexible sharing ratio. This modification does not include any increment in the repayment of principal and the profit gained is based solely on the payment of rent to purchase the ownership of the bank. Hence, this modified BBA is much more compliance towards Shariah law because it does not comprise any riba, gharar, or masyir.

  1. Measurement of the Specific Heat Using a Gravity Cancellation Approach

    Science.gov (United States)

    Zhong, Fang

    2003-01-01

    The specific heat at constant volume C(sob V) of a simple fluid diverges near its liquid-vapor critical point. However, gravity-induced density stratification due to the divergence of isothermal susceptibility hinders the direct comparison of the experimental data with the predictions of renormalization group theory. In the past, a microgravity environment has been considered essential to eliminate the density stratification. We propose to perform specific heat measurements of He-3 on the ground using a method to cancel the density stratification. A He-3 fluid layer will be heated from below, using the thermal expansion of the fluid to cancel the hydrostatic compression. A 6% density stratification at a reduced temperature of 10(exp -5) can be cancelled to better than 0.1% with a steady 1.7 micro K temperature difference across a 0.05 cm thick fluid layer. A conventional AC calorimetry technique will be used to determine the heat capacity. The minimized bulk density stratification with a relaxation time 6500 sec at a reduced temperature of 10(exp -5) will stay unchanged during 1 Hz AC heating. The smear of the specific heat divergence due to the temperature difference across the cell is about 0.1% at a reduced temperature of 10(exp -6). The combination of using High Resolution Thermometry with a 0.5 n K temperature resolution in the AC technique and the cancellation of the density stratification will enable C(sub V) to be measured down to a reduced temperature of 10(exp -6) with less than a 1% systematic error.

  2. Negative specific heat in a thermodynamic model of multifragmentation

    CERN Document Server

    Das, C B; Mekjian, A Z

    2003-01-01

    We consider a soluble model of multifragmentation which is similar in spirit to many models which have been used to fit intermediate energy heavy ion collision data. In this model $c_v$ is always positive but for finite nuclei $c_p$ can be negative for some temperatures and pressures. Furthermore, negative values of $c_p$ can be obtained in canonical treatment. One does not need to use the microcanonical ensemble. Negative values for $c_p$ can persist for systems as large as 200 paticles but this depends upon parameters used in the model calculation. As expected, negative specific heats are absent in the thermodynamic limit.

  3. Anomalous specific heat in ultradegenerate QED and QCD

    CERN Document Server

    Gerhold, A; Rebhan, Anton K

    2004-01-01

    We discuss the origin of the anomalous $T\\ln T^{-1}$ behavior of the low-temperature entropy and specific heat in ultradegenerate QED and QCD and report on a recent calculation which is complete to leading order in the coupling and which contains an infinite series of anomalous terms involving also fractional powers in $T$. This result involves dynamical hard-dense-loop resummation and interpolates between Debye screening effects at larger temperatures and non-Fermi-liquid behavior from only dynamically screened magnetic fields at low temperature.

  4. The Einstein specific heat model for finite systems

    Science.gov (United States)

    Boscheto, E.; de Souza, M.; López-Castillo, A.

    2016-06-01

    The theoretical model proposed by Einstein to describe the phononic specific heat of solids as a function of temperature consists of the very first application of the concept of energy quantization to describe the physical properties of a real system. Its central assumption lies in the consideration of a total energy distribution among N (in the thermodynamic limit N → ∞) non-interacting oscillators vibrating at the same frequency (ω). Nowadays, it is well-known that most materials behave differently at the nanoscale, having thus some cases physical properties with potential technological applications. Here, a version of the Einstein model composed of a finite number of particles/oscillators is proposed. The main findings obtained in the frame of the present work are: (i) a qualitative description of the specific heat in the limit of low-temperatures for systems with nano-metric dimensions; (ii) the observation that the corresponding chemical potential function for finite solids becomes null at finite temperatures as observed in the Bose-Einstein condensation and; (iii) emergence of a first-order like phase transition driven by varying N.

  5. Electronic specific heat of anisotropic superconductors and its doping dependence

    Energy Technology Data Exchange (ETDEWEB)

    Perez, L.A. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico (UNAM), A.P. 20-364, 01000, Mexico D.F. (Mexico)]. E-mail: lperez@fisica.unam.mx; Millan, J.S. [Facultad de Ingenieria, Universidad Autonoma del Carmen, 24180, Cd. del Carmen, Campeche (Mexico); Dominguez, B.C. [Facultad de Ingenieria, Universidad Autonoma del Carmen, 24180, Cd. del Carmen, Campeche (Mexico); Intituto de Fisica ' Manuel Sandoval Vallarta' , 78290, San Luis Potosi, S.L.P. (Mexico); Wang, C. [Instituto de Investigaciones en Materiales, UNAM, A.P. 70-360, 04510, Mexico D.F. (Mexico)

    2007-03-15

    The specific heat of electrons in p- and d-symmetry superconducting states (C{sub S}) is comparatively studied within the BCS framework. This study is performed on a square lattice described by a generalized Hubbard model, in which correlated-hopping interactions are included in addition to the repulsive Coulomb ones. The temperature dependences of C{sub S} show a power law behavior, instead of the exponential behavior found in the s channel, and for a given gap amplitude the number of nodes in the gap enhances C{sub S} in the low temperature regime. Moreover, the normalized discontinuity of C{sub S} at the critical temperature (T{sub c}) is smaller than the BCS analytical result of 1.43 for a wide range of electron densities. Finally, the results show that the single-particle van Hove singularity determines the location of the maximum gap, and then the position of the maximum discontinuity of the specific heat at T{sub c}.

  6. Specific Heat and Second Sound Measurements with the DYNAMIX Instrument

    Science.gov (United States)

    Nissen, Joel

    2003-01-01

    In addition to its primary role of studying non-linear heat transport effects near the lambda transition of He-4, the DYNAMX apparatus is suitable for measurements of the specific heat and the velocity of second sound. We plan to take advantage of available time on orbit to make measurements in these areas near to the lambda transition. The specific heat work would be similar to LPE, aimed at improving our knowledge of the singularity in the bulk heat capacity at the transition, but would provide more accurate results close to the transition. It would focus roughly equally on each side of the transition and would be synergistic with the CQ experiment, providing wider-range data at Q = 0. The second sound measurements are made possible by the fast time constant and high resolution of the DYNAMX thermometers, which allow accurate time-of-flight measurements of second sound pulses. It appears possible to measure the second sound velocity to about 1% at a reduced temperature of t = 5x10(exp -8) by averaging over a moderate number of pulses. The data would complement and extend earlier ground-based measurements, leading to improved tests of the theory of static critical phenomena at the lambda transition.

  7. Dielectric and specific heat relaxations in vapor deposited glycerol

    Energy Technology Data Exchange (ETDEWEB)

    Kasina, A., E-mail: angeline.kasina@fys.kuleuven.be, E-mail: wubbenhorst@fys.kuleuven.be; Putzeys, T.; Wübbenhorst, M., E-mail: angeline.kasina@fys.kuleuven.be, E-mail: wubbenhorst@fys.kuleuven.be [Department of Physics and Astronomy, Soft Matter and Biophysics Section, KU Leuven, Leuven (Belgium)

    2015-12-28

    Recently [S. Capponi, S. Napolitano, and M. Wübbenhorst, Nat. Commun. 3, 1233 (2012)], vapor deposited glasses of glycerol have been found to recover their super-cooled liquid state via a metastable, ordered liquid (MROL) state characterized by a tremendously enhanced dielectric strength along with a slow-down of the relaxation rate of the structural relaxation. To study the calorimetric signature of this phenomenon, we have implemented a chip-based, differential AC calorimeter in an organic molecular beam deposition setup, which allows the simultaneous measurement of dielectric relaxations via interdigitated comb electrodes and specific heat relaxation spectra during deposition and as function of the temperature. Heating of the as-deposited glass just above the bulk T{sub g} and subsequent cooling/reheating revealed a step-wise increase in c{sub p} by in total 9%, indicating unambiguously that glycerol, through slow vapour deposition, forms a thermodynamically stable glass, which has a specific heat as low as that of crystalline glycerol. Moreover, these glasses were found to show excellent kinetic stability as well as evidenced by both a high onset-temperature and quasi-isothermal recovery measurements at −75 °C. The second goal of the study was to elucidate the impact of the MROL state on the specific heat and its relaxation to the super-cooled state. Conversion of “MROL glycerol” to its “normal” (ordinary liquid, OL) state revealed a second, small (∼2%) increase of the glassy c{sub p}, a little gain (<10%) in the relaxed specific heat, and no signs of deviations of τ{sub cal} from that of normal “bulk” glycerol. These findings altogether suggest that the MROL state in glycerol comprises largely bulk-type glycerol that coexist with a minor volume fraction (<10%) of PVD-induced structural anomalies with a crystal-like calorimetric signature. Based on the new calorimetric findings, we have proposed a new physical picture that assumes the

  8. The specific heat of pure and hydrogenated amorphous silicon

    Science.gov (United States)

    Queen, Daniel Robert

    At low temperature, amorphous materials have low energy excitations that result in a heat capacity that is in excess of the Debye heat capacity calculated from the sound velocity. These excitations are ubiquitous to the glassy state and occur with roughly the same density for all glasses. The specific heat has a linear temperature dependence below 1K that has been described by the phenomenological two-level systems (TLS) model in addition to a T 3 temperature dependence which is in excess of the T3 Debye specific heat. It is still unknown what exact mechanism gives rise to the TLS but it is assumed that groups of atoms have configurations that are close in energy and, at low temperature, these atoms can change configurations by tunneling through the energy barrier separating them. It has been an open question as to whether tetrahedrally bonded materials, like amorphous silicon, can support TLS due to the over-constrained nature of their bonding. It is shown in this work that amorphous silicon (a-Si) and hydrogenated amorphous silicon (a-Si:H) have specific heat CP in excess of the Debye specific heat which depends on the details of the growth process. There is a linear term that is due to TLS in addition to an excess T3 contribution. We find that the TLS density depends on number density of atoms in the a-Si film and that the presence of hydrogen in a-Si:H increases CP further. We suggest that regions of low density are sufficiently under-constrained to support tunneling between structural configurations at low temperature as described by the TLS model. The presence of H further lowers the energy barriers for the tunneling process resulting in an increase in TLS density in a-Si:H. The presence of H in a-Si:H network is found to be metastable. Annealing causes H to diffuse away from clustered regions which reduces the density of TLS. A low temperature anomaly is found in the a-Si:H films in their as prepared state that is of unknown origin but appears to take the

  9. Unsteady Flow in a Supersonic Turbine with Variable Specific Heats

    Science.gov (United States)

    Dorney, Daniel J.; Griffin, Lisa W.; Huber, Frank; Sondak, Douglas L.; Turner, James (Technical Monitor)

    2001-01-01

    Modern high-work turbines can be compact, transonic, supersonic, counter-rotating, or use a dense drive gas. The vast majority of modern rocket turbine designs fall into these Categories. These turbines usually have large temperature variations across a given stage, and are characterized by large amounts of flow unsteadiness. The flow unsteadiness can have a major impact on the turbine performance and durability. For example, the Space Transportation Main Engine (STME) fuel turbine, a high work, transonic design, was found to have an unsteady inter-row shock which reduced efficiency by 2 points and increased dynamic loading by 24 percent. The Revolutionary Reusable Technology Turbopump (RRTT), which uses full flow oxygen for its drive gas, was found to shed vortices with such energy as to raise serious blade durability concerns. In both cases, the sources of the problems were uncovered (before turbopump testing) with the application of validated, unsteady computational fluid dynamics (CFD) to the designs. In the case of the RRTT and the Alternate Turbopump Development (ATD) turbines, the unsteady CFD codes have been used not just to identify problems, but to guide designs which mitigate problems due to unsteadiness. Using unsteady flow analyses as a part of the design process has led to turbine designs with higher performance (which affects temperature and mass flow rate) and fewer dynamics problems. One of the many assumptions made during the design and analysis of supersonic turbine stages is that the values of the specific heats are constant. In some analyses the value is based on an average of the expected upstream and downstream temperatures. In stages where the temperature can vary by 300 to 500 K, however, the assumption of constant fluid properties may lead to erroneous performance and durability predictions. In this study the suitability of assuming constant specific heats has been investigated by performing three-dimensional unsteady Navier

  10. The energy gap of the compound FeSe0.5Te0.5 determined by specific heat and Point Contact Spectroscopy

    Science.gov (United States)

    Escudero, Roberto; López-Romero, Rodolfo E.

    2015-10-01

    The superconductor FeSe0.5Te0.5 was studied with Point Contact spectroscopy and specific heat in polycrystalline samples. The transition temperature determined by magnetic measurement was TC=14.5 K. The size of the energy gap measured by junctions is Δ = 1.9 meV, whereas the gap determined by the specific heat measurements was Δ = 2.3 meV. The gap evolution with temperature follows BCS, the ratio 2Δ/KBTC has values between 2.88 ≤ 2 Δ /KBTC ≤ 3.04. The compound was grown by solid state synthesis in quartz ampoules under vacuum at 950 °C. Crystal structure was characterized by X-ray diffraction. The superconducting properties were characterized by magnetization, resistivity and specific heat. This superconductor shows an isotropic energy gap as observed with the fitting of the specific heat at low temperature.

  11. Cosmographic study of the universe's specific heat: a landscape for cosmology?

    Science.gov (United States)

    Luongo, Orlando; Quevedo, Hernando

    2014-01-01

    We propose a method for constructing the specific heat for the universe by following standard definitions of classical thermodynamics, in a spatially flat homogeneous and isotropic spacetime. We use cosmography to represent the specific heat in terms of measurable quantities, and show that a negative specific heat at constant volume and a zero specific heat at constant pressure are compatible with observational data. We derive the most general cosmological model which is compatible with the values obtained for the specific heat of the universe, and show that it alleviates the fine-tuning and the coincidence problems of the CDM model.

  12. Cosmographic study of the universe's specific heat: A landscape for Cosmology?

    CERN Document Server

    Luongo, Orlando

    2012-01-01

    We propose a method for constructing the specific heat for the universe by following standard definitions of classical thermodynamics, in a spatially flat homogeneous and isotropic spacetime. We use cosmography to represent the specific heat in terms of measurable quantities, and show that a negative specific heat at constant volume and a zero specific heat at constant pressure are compatible with observational data. We derive the most general cosmological model which is compatible with the values obtained for the specific heat of the universe, and show that it overcomes the fine-tuning and the coincidence problems of the $\\Lambda$CDM model.

  13. Specific Heat of Matter Formed in Relativistic Nuclear Collisions

    CERN Document Server

    Basu, Sumit; Chatterjee, Rupa; Nayak, Tapan K; Nandi, Basanta K

    2016-01-01

    We report the excitation energy dependence of specific heat (\\cv) of hadronic matter at freeze-out in Au+Au and Cu+Cu collisions at the Relativistic Heavy Ion Collider energies by analyzing the published data on event-by-event mean transverse momentum (\\meanpt) distributions. The \\meanpt~distributions in finite \\pt~ranges are converted to distributions of effective temperatures, and dynamical fluctuations in temperature are extracted by subtracting widths of the corresponding mixed event distributions. The heat capacity per particle at the kinetic freezeout surface is presented as a function of collision energy, which shows a sharp rise in \\cv~below \\sNN~=~62.4~GeV. We employ the Hadron Resonance Gas (HRG) model to estimate \\cv~at the chemical and kinetic freezeout surfaces. The experimental results are compared to the HRG and other theoretical model calculations. HRG results show good agreement with data. Model predictions for \\cv~at the Large Hadron Collider energy are presented.

  14. Quantum elasticity of graphene: Thermal expansion coefficient and specific heat

    Science.gov (United States)

    Burmistrov, I. S.; Gornyi, I. V.; Kachorovskii, V. Yu.; Katsnelson, M. I.; Mirlin, A. D.

    2016-11-01

    We explore thermodynamics of a quantum membrane, with a particular application to suspended graphene membrane and with a particular focus on the thermal expansion coefficient. We show that an interplay between quantum and classical anharmonicity-controlled fluctuations leads to unusual elastic properties of the membrane. The effect of quantum fluctuations is governed by the dimensionless coupling constant, g0≪1 , which vanishes in the classical limit (ℏ →0 ) and is equal to ≃0.05 for graphene. We demonstrate that the thermal expansion coefficient αT of the membrane is negative and remains nearly constant down to extremely low temperatures, T0∝exp(-2 /g0) . We also find that αT diverges in the classical limit: αT∝-ln(1 /g0) for g0→0 . For graphene parameters, we estimate the value of the thermal expansion coefficient as αT≃-0.23 eV-1 , which applies below the temperature Tuv˜g0ϰ0˜500 K (where ϰ0˜1 eV is the bending rigidity) down to T0˜10-14 K. For T specific heat of the membrane and investigate the behavior of the Grüneisen parameter.

  15. Exciton condensation and its influence on the specific heat

    Energy Technology Data Exchange (ETDEWEB)

    Wachter, P., E-mail: wachter@solid.phys.ethz.ch [Laboratorium fuer Festkoerperphysik, ETH Zuerich, 8093 Zuerich (Switzerland); Bucher, B. [HSR Hochschule fuer Technik, 8640 Rapperswil (Switzerland)

    2013-01-01

    In rare earth compounds with localized 4f states the observation of bound 4f-hole-5d-electron states, excitons, is questionable. On the other hand the same compounds exhibit p-d excitons, which are derived from itinerant bands. In rare earth compounds, which exhibit intermediate valence, 4f-5d hybridization produces a narrow, several 10 meV wide 4f band. Now 4f-5d excitons are possible and have been observed in TmSe{sub 0.45}Te{sub 0.55} and similar compositions. The special band structure of these materials permits an enormous amount of excitons ( Almost-Equal-To 10{sup 21} cm{sup -3}), which condense in a first order transition at low temperatures and high pressure. This static and immense concentration of excitons dominates the heat conductivity and the thermal diffusivity and even exhibits the phenomenon of superfluidity in a solid. The measured specific heat shows that phonons couple to these excitons forming exciton polarons.

  16. On the proper Mach number and ratio of specific heats for modeling the Venus bow shock

    Science.gov (United States)

    Tatrallyay, M.; Russell, C. T.; Luhmann, J. G.; Barnes, A.; Mihalov, J. D.

    1984-01-01

    Observational data from the Pioneer Venus Orbiter are used to investigate the physical characteristics of the Venus bow shock, and to explore some general issues in the numerical simulation of collisionless shocks. It is found that since equations from gas-dynamic (GD) models of the Venus shock cannot in general replace MHD equations, it is not immediately obvious what the optimum way is to describe the desired MHD situation with a GD code. Test case analysis shows that for quasi-perpendicular shocks it is safest to use the magnetospheric Mach number as an input to the GD code. It is also shown that when comparing GD predicted temperatures with MHD predicted temperatures total energy should be compared since the magnetic energy density provides a significant fraction of the internal energy of the MHD fluid for typical solar wind parameters. Some conclusions are also offered on the properties of the terrestrial shock.

  17. Determination of the Specific Heat Ratio of a Gas in a Plastic Syringe

    Science.gov (United States)

    Chamberlain, Jeff

    2010-01-01

    The rapid compression or expansion of a gas in a plastic syringe is a poor approximation of an adiabatic process. Heat exchange with the walls of the syringe brings the gas to equilibrium in an amount of time that is not significantly greater than the length of the compression or expansion itself. Despite this limitation, it is still possible to…

  18. Gamma-effects on 2-dimensional transonic aerodynamics. [specific heat ratio due to shock induced separation

    Science.gov (United States)

    Tuzla, K.; Russell, D. A.; Wai, J. C.

    1976-01-01

    Nonlifting 10% biconvex airfoils are mounted in a 30 x 40 cm Ludwieg-tube-driven transonic test-section and the flow field recorded with a holographic interferometer. Nitrogen, argon, and carbon dioxide are used as the principal test gases. Experiments are conducted with Reynolds number based on chord of (0.5-3.5) x 10 to the 6th with Mach numbers of 0.70, 0.75, and 0.80. Supporting calculations use inviscid transonic small-disturbance and full-potential computer codes coupled with simple integral boundary-layer modeling. Systematic studies show that significant gamma-effects can occur due to shock-induced separation.

  19. Specific heat and thermal conductivity in the mixed state of MgB2.

    Science.gov (United States)

    Tewordt, L; Fay, D

    2002-09-23

    The specific heat C and the electronic and phononic thermal conductivities kappa(e) and kappa(ph) are calculated in the mixed state for magnetic fields H near H(c2), including the effects of supercurrent flow and Andreev scattering. The resulting function C(H) is nearly linear while kappa(e)(H) exhibits an upward curvature near H(c2). The slopes decrease with impurity scattering which improves the agreement with the data on MgB2. The ratio of phonon relaxation times tau(n)/tau(s)=g(omega(0),H) for phonon energy omega(0) is smeared out around omega(0)=2Delta and tends to one for increasing H. This leads to a rapid reduction of kappa(ph)(H) in MgB2 for relatively small fields due to the rapid suppression of the smaller energy gap.

  20. Specific heat studies in Ho–Ba–CuO superconductors: Fermionic and bosonic contributions

    Indian Academy of Sciences (India)

    Dinesh Varshney; Sanjay Shah; R K Singh

    2000-08-01

    The specific heats of superconducting HoBa2Cu3O7– (c ≅ 92 K) have been theoretically investigated in the temperature domain 70 ≤ ≤ 110 K. The bosonic (phonons) contribution to the specific heat is estimated from Debye model in the harmonic approximation for high temperature expansion ( > D/2) using the moments of the phonon density of states. The fermionic constituent as the electronic specific heat is deduced using a suitable trial function above and below c. As a next step the contribution of specific heat by charge oscillations (plasmons) are obtained. The theoretical results from bosonic and fermionic terms are then compared with the experimental results. We find that the specific heats from electronic as well as plasmon term are only a fraction of lattice specific heat and in particular, plasmons do not influence the thermal conduction significantly. The implications of the above analysis are discussed.

  1. Specific heat in the second Landau level fractional quantum Hall effect

    OpenAIRE

    Schmidt, B. A.; Bennaceur, K.; Gaucher, S.; Gervais, G.; Pfeiffer, L. N.; West, K. W.

    2016-01-01

    Specific heat has had an important role in the study of superfluidity and superconductivity, and could provide important information on the fractional quantum Hall effect as well. However, tra- ditional measurements of the specific heat of a two-dimensional electron gas are difficult due to the large background contribution of the phonon bath, even at very low temperatures. Here, we report measurements of the specific heat per electron of a single two-dimensional electron gas with no contribu...

  2. Molecular dynamics simulations on specific heat capacity and glass transition tempera-ture of liquid silver

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The embedded-atom method is adopted to simulate the specific heat capacity of liquid silver. The relationship between the specific heat capacity and the temperature above and below melting point is derived. The results show that there exists an anormaly of the specific heat capacity of liquid silver near 950 K. Simulated pair distribution functions show that the liquid-to-glass transition takes place at this temperature.

  3. Multi-Objective Flight Control for Drag Minimization and Load Alleviation of High-Aspect Ratio Flexible Wing Aircraft

    Science.gov (United States)

    Nguyen, Nhan; Ting, Eric; Chaparro, Daniel; Drew, Michael; Swei, Sean

    2017-01-01

    As aircraft wings become much more flexible due to the use of light-weight composites material, adverse aerodynamics at off-design performance can result from changes in wing shapes due to aeroelastic deflections. Increased drag, hence increased fuel burn, is a potential consequence. Without means for aeroelastic compensation, the benefit of weight reduction from the use of light-weight material could be offset by less optimal aerodynamic performance at off-design flight conditions. Performance Adaptive Aeroelastic Wing (PAAW) technology can potentially address these technical challenges for future flexible wing transports. PAAW technology leverages multi-disciplinary solutions to maximize the aerodynamic performance payoff of future adaptive wing design, while addressing simultaneously operational constraints that can prevent the optimal aerodynamic performance from being realized. These operational constraints include reduced flutter margins, increased airframe responses to gust and maneuver loads, pilot handling qualities, and ride qualities. All of these constraints while seeking the optimal aerodynamic performance present themselves as a multi-objective flight control problem. The paper presents a multi-objective flight control approach based on a drag-cognizant optimal control method. A concept of virtual control, which was previously introduced, is implemented to address the pair-wise flap motion constraints imposed by the elastomer material. This method is shown to be able to satisfy the constraints. Real-time drag minimization control is considered to be an important consideration for PAAW technology. Drag minimization control has many technical challenges such as sensing and control. An initial outline of a real-time drag minimization control has already been developed and will be further investigated in the future. A simulation study of a multi-objective flight control for a flight path angle command with aeroelastic mode suppression and drag

  4. Internal energy and specific heat in a ferromagnetic-antiferromagnetic double layers

    Institute of Scientific and Technical Information of China (English)

    Jiang Wei; Guo An-Bang

    2007-01-01

    The internal energy and specific heat of a Heisenberg ferro- antiferromagnetic double-layer system are studied by using spin-wave theory and the retarded Green function method at low temperatures. Numerical results show that the antiferromagnetic intralayer coupling J2 has an important influence on internal energy and specific heat for a four-sublattice system with antiferromagnetic (or ferrimagnetic) interlayer couplings.

  5. Communication: High pressure specific heat spectroscopy reveals simple relaxation behavior of glass forming molecular liquid

    DEFF Research Database (Denmark)

    Roed, Lisa Anita; Niss, Kristine; Jakobsen, Bo

    2015-01-01

    The frequency dependent specific heat has been measured under pressure for the molecular glass forming liquid 5-polyphenyl-4-ether in the viscous regime close to the glass transition. The temperature and pressure dependences of the characteristic time scale associated with the specific heat...

  6. Evidence for unconventional superconductivity in UPt sub 3 : Splitting of the specific heat anomaly at Tc

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, N.E.; Fisher, R.A.; Kim, S.; Woodfield, B.F. (MCSD, LBL, Univ. of California, Berkeley (USA)); Taillefer, L.; Hasselbach, K.; Flouquet, J. (CRTBT, CNRS, 38 - Grenoble (France)); Giorgi, A.L.; Smith, J.L. (Los Alamos National Lab., NM (USA))

    1989-12-01

    The specific heats of two samples of UPt{sub 3} have been measured in the vicinity of Tc. Both samples show specific heat anomalies sharper than any previously observed and two clearly resolved maxima. The results are interpreted as evidence of splitting of the transition and unconventional pairing. (orig.).

  7. Specific heat and thermal conductivity of explosives, mixtures, and plastic-bonded explosives determined experimentally

    Energy Technology Data Exchange (ETDEWEB)

    Baytos, J.F.

    1979-09-01

    The specific heat and thermal conductivity of explosives and plastic-bonded explosives of interest to WX operations, determined experimentally, are reported in three tables. Specific heat was determined by differential scanning calorimetry against sapphire standards. Thermal conductivity was determined by two means: the guarded hot-plate method or the differential scanning calorimeter comparative method on miniature samples.

  8. Ambient-pressure specific heat of single-crystal UGe2

    Science.gov (United States)

    Lashley, J. C.; Fisher, R. A.; Flouquet, J.; Hardy, F.; Huxley, A.; Phillips, N. E.

    2006-05-01

    Measurements of the specific heat of UGe2 at ambient pressure show a feature in the 18-23 K region that is suggestive of a CDW transition. The magnetic field dependence of the specific heat shows the presence of structure in the electron density of states and an unusual nature of the ferromagnetic ordering at the Curie temperature.

  9. Ambient-pressure specific heat of single-crystal UGe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Lashley, J.C. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Fisher, R.A. [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Flouquet, J. [Departement de la Recherche Fondamentale sur la Matiere Condensee, SPSMS, CEA Grenoble, 38054 Grenoble Cedex 9 (France); Hardy, F. [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Huxley, A. [Departement de la Recherche Fondamentale sur la Matiere Condensee, SPSMS, CEA Grenoble, 38054 Grenoble Cedex 9 (France); Phillips, N.E. [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States)]. E-mail: nephill@cchem.berkeley.edu

    2006-05-01

    Measurements of the specific heat of UGe{sub 2} at ambient pressure show a feature in the 18-23K region that is suggestive of a CDW transition. The magnetic field dependence of the specific heat shows the presence of structure in the electron density of states and an unusual nature of the ferromagnetic ordering at the Curie temperature.

  10. Model for the orientation, magnetic field, and temperature dependence of the specific heat of CeCu6

    Science.gov (United States)

    Edelstein, A. S.

    1988-03-01

    The results of a model calculation of the orientation, magnetic field, and temperature dependence of the specific heat C of CeCu6 are found to be in good agreement with the single-crystal data of Amato et al. The model incorporates both the Kondo and crystal-field effects. It is suggested that the low-temperature Wilson's ratio C/Tχ, where χ is the susceptibility, may not change in an applied field H and that both C/T and χ at low temperatures as a function of H may be proportional to the many-body density of states at the energy μH.

  11. In vitro measurements of temperature-dependent specific heat of liver tissue.

    Science.gov (United States)

    Haemmerich, Dieter; dos Santos, Icaro; Schutt, David J; Webster, John G; Mahvi, David M

    2006-03-01

    We measured the specific heat of liver tissue in vitro by uniformly heating liver samples between two electrodes. We insulated the samples by expanded polystyrene, and corrected for heat loss and water loss. The specific heat of the liver is temperature-dependent, and increases by 17% at 83.5 degrees C (p specific heat was 3411 J kg(-1)K(-1) at 25 degrees C, and 4187 J kg(-1)K(-1) at 83.5 degrees C. Water loss from the samples was significant above 70 degrees C, with approximately 20% of reduction in sample mass at 90 degrees C.

  12. Specific Heat of Hollow Nanosphere Coupled to Substrate: Quantum Size Effects

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With the help of the elastic wave theory, in the perturbed approximation the density-of-states for vibrational modes and the specific heat axe studied for different hollow Si nanospheres, coupled with a semi-infinite substrate. We find that the modes of such coupled hollow spheres are significantly broadened and shifted toward low frequencies. The specific heat of the coupled hollow nanosphere is bigger than an isolated one due to the coupling interaction and quantum size effects. The predicted coupling and size enhancements on specific heat are probed in thermal experiments.

  13. Low-Temperature Specific Heat of Superconducting MgB2

    Institute of Scientific and Technical Information of China (English)

    雒建林; 张杰; 陈兆甲; 白海洋; 王玉鹏; 孟继宝; 金铎; 任志安; 车广灿; 赵忠贤

    2001-01-01

    The specific heat of the recently discovered superconductor MgB2 has been measured at temperatures rangingfrom 4.5 to 80K. The superconducting anomaly △C at Tc is clearly observed. The total specific heat in thenormal state can be well fitted by electronic and phonon contributions. The Debye temperature θD is found to be737K, much larger than other intermetallic superconductors. The normal-state electronic specific heat coefficientγ is found to be 2.48±0.5 mJ/mol. K2 and △C/γTc is between 1.41 and 2.15.

  14. Specific heat of UPt/sub 3/: Evidence for unconventional superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, R.A.; Kim, S.; Woodfield, B.F.; Phillips, N.E.; Taillefer, L.; Hasselbach, K.; Flouquet, J.; Giorgi, A.L.; Smith, J.L.

    1989-03-20

    The specific heats of two samples of UPt/sub 3/ have been measured in the vicinity of the transition to the superconducting state. In both cases the specific-heat anomalies are sharper than any previously observed, and two maxima are clearly resolved. The results are interpreted as evidence of a splitting of the transition and unconventional pairing. A model that is consistent with the known sample dependence of the superconducting-state specific heat is used to derive ''intrinsic'' values of the related parameters.

  15. Effect of size on specific heat and Debye temperature of nanomaterials

    Science.gov (United States)

    Patel, Ghanshyam R.; Thakar, Nilesh A.; Pandya, Tushar C.

    2016-05-01

    Liquid drop model is used to predict the size dependent melting temperature of low dimensional systems. In the present work we have extended liquid drop model for predicting size dependent Debye temperature of nanoparticles of Au and Se. It is found that the Debye temperature drop when the particle size is decreased. The results obtained for the size dependence of the Debye temperature are found to be in good agreement with the experimental data. This supports the validity of the method presented in this paper. In the present study relationship for size dependent of specific heat is also deduced for nanoparticles using liquid drop model. Our theoretical predictions of size dependent of specific heat of Cu nanoparticles agree fairly well with available computer simulation results. The present relationship for Debye temperature and specific heat may be used to predict the Debye temperature and specific heat for nanomaterials.

  16. Surface tension and specific heat of liquid Ni70.2Si29.8 alloy

    Institute of Scientific and Technical Information of China (English)

    WANG Haipeng; WEI Bingbo

    2005-01-01

    The surface tension and specific heat of stable and metastable liquid Ni70.2Si29.8 eutectic alloy were measured by electromagnetic levitation oscillating drop method and drop calorimetry. The surface tension depends on temperature linearly within the experimental undercooling regime of 0-182 K (0.12 TE). Its value is 1.693 N·m-1 at the eutectic temperature of 1488 K, and the temperature coefficient is -4.23×10-4 N·m-1·K-1. For the specific heat measurement, the maximum undercooling is up to 253 K (0.17 TE). The specific heat is determined as a polynomial function of temperature in the experimental temperature regime. On the basis of the measured data of surface tension and specific heat, the temperature-dependent density, excess volume and sound speed of liquid Ni70.2Si29.8 alloy are predicted theoretically.

  17. Specific heat of superheated Al-10Sr alloy melts[Foundation item

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The specific heat of superheated Al-10Sr melts was determined at different heating rates between 1  K/min and 20  K/min using a differential scanning calorimeter(DSC). As a whole, the specific heat increases with increasing temperature. A hump is observed on the specific heat curve at the temperature corresponding to the phase boundary temperature dependent on heating rate. Moreover, the hump shifts to higher temperature in the measured temperature range from about 840  ℃ to 890  ℃ with increasing heating rate. At certain temperature in the higher superheated zone, the specific heat of the melt as a function of temperature shows a sharp rise . The result indicates that disorder zone fraction begins to increase while atom clusters fraction decreases at the breaking temperature.

  18. Quasiparticle specific heats for the crystalline color superconducting phase of QCD

    CERN Document Server

    Casalbuoni, R; Mannarelli, M; Nardulli, G; Ruggieri, M; Stramaglia, S; 10.1016/j.physletb.2003.09.071

    2003-01-01

    We calculate the specific heats of quasiparticles of two-flavor QCD in its crystalline phases for low temperature. We show that for the different crystalline structures considered here there are gapless modes contributing linearly in temperature to the specific heat. We evaluate also the phonon contributions which are cubic in temperature. These features might be relevant for compact stars with an inner shell in a color superconducting crystalline phase. (21 refs).

  19. Quasi-particle Specific Heats for the Crystalline Color Superconducting Phase of QCD

    CERN Document Server

    Casalbuoni, Roberto; Mannarelli, M; Nardulli, Giuseppe; Ruggieri, Marco; Stramaglia, S

    2003-01-01

    We calculate the specific heats of quasi-particles of two-flavor QCD in its crystalline phases for low temperature. We show that for the different crystalline structures considered here there are gapless modes contributing linearly in temperature to the specific heat. We evaluate also the phonon contributions which are cubic in temperature. These features might be relevant for compact stars with an inner shell in a color superconducting crystalline phase.

  20. Quasi-particle specific heats for the crystalline color superconducting phase of QCD

    Energy Technology Data Exchange (ETDEWEB)

    Casalbuoni, R.; Gatto, R.; Mannarelli, M.; Nardulli, G.; Ruggieri, M.; Stramaglia, S

    2003-11-27

    We calculate the specific heats of quasi-particles of two-flavor QCD in its crystalline phases for low temperature. We show that for the different crystalline structures considered here there are gapless modes contributing linearly in temperature to the specific heat. We evaluate also the phonon contributions which are cubic in temperature. These features might be relevant for compact stars with an inner shell in a color superconducting crystalline phase.

  1. Specific heat spectra of non-interacting fermions in a quasiperiodic ladder sequence

    Science.gov (United States)

    Moreira, D. A.; Albuquerque, E. L.; Anselmo, D. H. A. L.

    2008-07-01

    We compute the specific heat spectra of non-interacting fermions whose energy spectrum was obtained from a quasiperiodic ladder sequence (Fibonacci and Rudin-Shapiro type), mimicking a DNA molecule model. The specific heat is calculated from their underlying multi-fractal energy spectrum, considering several values of energy densities. Comparisons are made with a real DNA sequence, namely the human chromosome 22 (Ch22).

  2. Phonon spectrum of the ferromagnetic superconductor UGe2 and consequences for its specific heat

    Science.gov (United States)

    Raymond, S.; Huxley, A.

    2006-03-01

    We report inelastic neutron scattering measurements of the phonon spectrum of the pressure-induced ferromagnetic superconductor UGe2 . The phonon contribution to the specific heat was estimated from a fit to our data. The excess specific heat previously noted at around Tx≈30K is not due to phonons but is well described by the temperature dependence of the magnetic order parameter at the molecular field level.

  3. Specific heat spectra of non-interacting fermions in a quasiperiodic ladder sequence

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, D.A. [Departamento de Fisica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil); Albuquerque, E.L. [Departamento de Fisica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil)], E-mail: eudenilson@dfte.ufrn.br; Anselmo, D.H.A.L. [Departamento de Fisica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil)

    2008-07-28

    We compute the specific heat spectra of non-interacting fermions whose energy spectrum was obtained from a quasiperiodic ladder sequence (Fibonacci and Rudin-Shapiro type), mimicking a DNA molecule model. The specific heat is calculated from their underlying multi-fractal energy spectrum, considering several values of energy densities. Comparisons are made with a real DNA sequence, namely the human chromosome 22 (Ch22)

  4. Specific Heat Capacity of Physically Confined Ethylene glycol in Nano Pores

    Science.gov (United States)

    Amanuel, Samuel; Linthicum, Will

    2013-03-01

    Sensible heat is a cheap and effective means of storing solar energy where energy storage density can be improved by enhancing the specific heat capacity of the heat transfer materials. Formulating composite materials of heat transfer fluids is a mechanism by which the bulk specific heat capacity can be altered and preferably increased. Traditionally, the specific heat capacity of composite material is evaluated from the weighed average of the individual specific heat capacities of the constituents. This, however, does not take into account the effect of interfacial atoms and molecules. The effect of interfacial atoms and molecules becomes increasingly significant when one of the constituents has dimensions in nano meters. In this study, we evaluate the role of interfacial molecules on the specific heat capacity of composite systems. In order to systematically control the interfacial molecules, we have measured the specific heat capacity of ethylene glycol when it is physically confined in nano pores. This work has been supported financially by Union College Faculty Research Fund, NSF-EEC 0939322 and New York State NASA space grant for financial support.

  5. The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon

    Science.gov (United States)

    Khara, Galvin S.; Murphy, Samuel T.; Daraszewicz, Szymon L.; Duffy, Dorothy M.

    2016-10-01

    The swift heavy ion (SHI) irradiation of materials is often modelled using the two-temperature model. While the model has been successful in describing SHI damage in metals, it fails to account for the presence of a bandgap in semiconductors and insulators. Here we explore the potential to overcome this limitation by explicitly incorporating the influence of the bandgap in the parameterisation of the electronic specific heat for Si. The specific heat as a function of electronic temperature is calculated using finite temperature density functional theory with three different exchange correlation functionals, each with a characteristic bandgap. These electronic temperature dependent specific heats are employed with two-temperature molecular dynamics to model ion track creation in Si. The results obtained using a specific heat derived from density functional theory showed dramatically reduced defect creation compared to models that used the free electron gas specific heat. As a consequence, the track radii are smaller and in much better agreement with experimental observations. We also observe a correlation between the width of the band gap and the track radius, arising due to the variation in the temperature dependence of the electronic specific heat.

  6. A Flexible Power Control Method of VSC-HVDC Link for the Enhancement of Effective Short-Circuit Ratio in a Hybrid Multi-Infeed HVDC System

    DEFF Research Database (Denmark)

    Liu, Yan; Chen, Zhe

    2013-01-01

    With the emerging use of voltage source converter high voltage direct current (VSC-HVDC) links, the hybrid multi-infeed HVDC (HMIDC) system that includes the line commutated converter (LCC) HVDC and the VSC-HVDC links is becoming a promising power transmission structure in the modern power systems....... To evaluate the contribution of the VSC-HVDC link on the voltage stability of HMIDC system, this paper proposes an effective short circuit ratio (ESCR) calculation method. Through the calculation, the voltage support capability of the VSC-HVDC link can be quantitatively represented by the ESCR. Furthermore......, based on the calculation results, a flexible power control strategy for the VSC-HVDC link is developed to provide maximum reactive power support under grid faults. The theoretical analysis of the HMIDC system is based on the Danish transmission grid, evaluated through PSCAD simulations under different...

  7. Critical behavior of 2,6-dimethylpyridine-water: Measurements of specific heat, dynamic light scattering, and shear viscosity

    DEFF Research Database (Denmark)

    Mirzaev, S. Z.; Behrends, R.; Heimburg, Thomas Rainer

    2006-01-01

    2,6-dimethylpyridine-water, specific heat, dynamic light scattering, shear viscosity Udgivelsesdato: 14 April......2,6-dimethylpyridine-water, specific heat, dynamic light scattering, shear viscosity Udgivelsesdato: 14 April...

  8. 增殖比可调快堆堆芯方案设计%Core Design of Fast Reactor With Flexible Breeding Ratio

    Institute of Scientific and Technical Information of China (English)

    肖云龙; 吴宏春; 郑友琦

    2013-01-01

    增殖比可调快堆是指在不对堆芯设计进行重大改动的条件下实现增殖比可调的快中子反应堆。这一思想使快堆设计可先于工业发展需求,实现对核能形势的动态响应。为实现更大的增殖比,选择了增殖性能更为优异的金属燃料,堆芯采取非均匀布置,轴向和径向布置有使用压水堆乏燃料的增殖区。利用SRAC/COREBN软件包和自行编写的换料耦合脚本为工具,提出了具有不同增殖比的钠冷快堆堆芯方案设计。在同一个堆中,使用相同的燃料,仅通过改变组件数量及堆芯布置,便可实现增殖比在1.0~1.4范围内的可调。计算结果表明,各增殖比方案下的空泡反应性和最大线功率等参数均满足快堆设计要求。%Fast reactor with flexible breeding ratio can achieve variable breeding ratios without significant changes of core design . This concept enables fast reactor to effectively respond to the industrial needs .In order to obtain larger breeding ratio ,the metal fuel with better performance was selected . Assemblies were heterogeneously arranged .Blankets of PWR spent nuclear fuels were axially and radially arranged . Various sodium cooled fast reactor core schemes with different breeding ratios were proposed .SRAC/COREBN package was used for neutronic calculation and perl scripts was used for shuffling and data exchange .Different breeding ratios were achieved by changing the number of assemblies and their loading pattern . The achieved breeding ratios varied from 1.0 to 1.4 .Numerical results show that concerning parameters ,such as void worth and maximum linear power ,of all schemes satisfy the criteria of fast reactor designs .

  9. A Study of Specific Heat Capacity Functions of Polyvinyl Alcohol- Cassava Starch Blends

    Science.gov (United States)

    Sin, Lee Tin; Rahman, W. A. W. A.; Rahmat, A. R.; Morad, N. A.; Salleh, M. S. N.

    2010-03-01

    The specific heat capacity ( C sp) of polyvinyl alcohol (PVOH) blends with cassava starch (CSS) was studied by the differential scanning calorimetry method. Specimens of PVOH-CSS blends: PPV37 (70 mass% CSS) and PPV46 (60 mass% CSS) were prepared by a melt blending method with glycerol added as a plasticizer. The results showed that the specific heat capacity of PPV37 and PPV46 at temperatures from 330 K to 530 K increased from (2.963 to 14.995) J· g-1 · K-1 and (2.517 to 14.727) J · g-1· K-1, respectively. The specific heat capacity of PVOH-CSS depends on the amount of starch. The specific heat capacity of the specimens can be approximated by polynomial equations with a curve fitting regression > 0.992. For instance, the specific heat capacity (in J · g-1 · K-1) of PPV37 can be expressed by C sp = -17.824 + 0.063 T and PPV46 by C sp = -18.047 + 0.061 T, where T is the temperature (in K).

  10. Specific heat of Nb3Sn: The case for a single gap

    Directory of Open Access Journals (Sweden)

    Y. J. Jo

    2014-10-01

    Full Text Available The important influence of multiple gaps in the superconductivity of MgB2 and Fe-based compounds, especially because of the possibility that manipulation of a second gap can significantly raise the upper critical field Hc2, has refocused attention on Nb3Sn because anomalies in both specific heat and point-contact tunneling studies have led to the proposal that Nb3Sn is also a two-gap superconductor. Here, we search for evidence of the second gap in a careful study of the influence of the homogenization temperature on the sample uniformity. We show that it is very difficult to fabricate samples that are both homogeneous and stoichiometric. We find so-called “second-gap” anomalies disappear only after high temperature and long-term annealing. Such a well-annealed sample shows only a strong, electron-phonon-coupled, single-gap behavior. In contrast, samples reacted and annealed at lower temperatures, as in the earlier two-gap studies, show small chemical composition variations of the A15 phase. We propose that the second gap sightings are actually due to variation of Tc within very difficult-to-fully homogenize samples. A curiosity of the A15 Nb3Sn phase is that almost any mixture of Nb and Sn tries to form a stoichiometric A15 composition, but the residue of course contains off-stoichiometric A15, Nb, and other phases when the Nb:Sn ratio departs from the true 3:1 stoichiometry.

  11. Specific heat of Nb{sub 3}Sn: The case for a single gap

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Y. J., E-mail: jophy@knu.ac.kr [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Zhou, Jian; Sung, Zu Hawn; Lee, Peter J.; Larbalestier, D. C. [National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States)

    2014-10-01

    The important influence of multiple gaps in the superconductivity of MgB{sub 2} and Fe-based compounds, especially because of the possibility that manipulation of a second gap can significantly raise the upper critical field H{sub c2}, has refocused attention on Nb{sub 3}Sn because anomalies in both specific heat and point-contact tunneling studies have led to the proposal that Nb{sub 3}Sn is also a two-gap superconductor. Here, we search for evidence of the second gap in a careful study of the influence of the homogenization temperature on the sample uniformity. We show that it is very difficult to fabricate samples that are both homogeneous and stoichiometric. We find so-called “second-gap” anomalies disappear only after high temperature and long-term annealing. Such a well-annealed sample shows only a strong, electron-phonon-coupled, single-gap behavior. In contrast, samples reacted and annealed at lower temperatures, as in the earlier two-gap studies, show small chemical composition variations of the A15 phase. We propose that the second gap sightings are actually due to variation of T{sub c} within very difficult-to-fully homogenize samples. A curiosity of the A15 Nb{sub 3}Sn phase is that almost any mixture of Nb and Sn tries to form a stoichiometric A15 composition, but the residue of course contains off-stoichiometric A15, Nb, and other phases when the Nb:Sn ratio departs from the true 3:1 stoichiometry.

  12. Specific heat of twisted bilayer graphene: Engineering phonons by atomic plane rotations

    Energy Technology Data Exchange (ETDEWEB)

    Nika, Denis L. [E. Pokatilov Laboratory of Physics and Engineering of Nanomaterials, Department of Physics and Engineering, Moldova State University, Chisinau MD-2009, Republic of Moldova (Moldova, Republic of); Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, Bourns College of Engineering, University of California—Riverside, Riverside, California, 92521 (United States); Cocemasov, Alexandr I. [E. Pokatilov Laboratory of Physics and Engineering of Nanomaterials, Department of Physics and Engineering, Moldova State University, Chisinau MD-2009, Republic of Moldova (Moldova, Republic of); Balandin, Alexander A., E-mail: balandin@ee.ucr.edu [Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, Bourns College of Engineering, University of California—Riverside, Riverside, California, 92521 (United States)

    2014-07-21

    We have studied the phonon specific heat in single-layer, bilayer, and twisted bilayer graphene. The calculations were performed using the Born-von Karman model of lattice dynamics for intralayer atomic interactions and spherically symmetric interatomic potential for interlayer interactions. We found that at temperature T < 15 K, specific heat varies with temperature as T{sup n}, where n = 1 for graphene, n = 1.6 for bilayer graphene, and n = 1.3 for the twisted bilayer graphene. The phonon specific heat reveals an intriguing dependence on the twist angle in bilayer graphene, which is particularly pronounced at low temperature. The results suggest a possibility of phonon engineering of thermal properties of layered materials by twisting the atomic planes.

  13. Measurement and Model Validation of Nanofluid Specific Heat Capacity with Differential Scanning Calorimetry

    Directory of Open Access Journals (Sweden)

    Harry O'Hanley

    2012-01-01

    Full Text Available Nanofluids are being considered for heat transfer applications; therefore it is important to know their thermophysical properties accurately. In this paper we focused on nanofluid specific heat capacity. Currently, there exist two models to predict a nanofluid specific heat capacity as a function of nanoparticle concentration and material. Model I is a straight volume-weighted average; Model II is based on the assumption of thermal equilibrium between the particles and the surrounding fluid. These two models give significantly different predictions for a given system. Using differential scanning calorimetry (DSC, a robust experimental methodology for measuring the heat capacity of fluids, the specific heat capacities of water-based silica, alumina, and copper oxide nanofluids were measured. Nanoparticle concentrations were varied between 5 wt% and 50 wt%. Test results were found to be in excellent agreement with Model II, while the predictions of Model I deviated very significantly from the data. Therefore, Model II is recommended for nanofluids.

  14. Quantum criticality at the superconductor-insulator transition revealed by specific heat measurements.

    Science.gov (United States)

    Poran, S; Nguyen-Duc, T; Auerbach, A; Dupuis, N; Frydman, A; Bourgeois, Olivier

    2017-02-22

    The superconductor-insulator transition (SIT) is considered an excellent example of a quantum phase transition that is driven by quantum fluctuations at zero temperature. The quantum critical point is characterized by a diverging correlation length and a vanishing energy scale. Low-energy fluctuations near quantum criticality may be experimentally detected by specific heat, cp, measurements. Here we use a unique highly sensitive experiment to measure cp of two-dimensional granular Pb films through the SIT. The specific heat shows the usual jump at the mean field superconducting transition temperature marking the onset of Cooper pairs formation. As the film thickness is tuned towards the SIT, is relatively unchanged, while the magnitude of the jump and low-temperature specific heat increase significantly. This behaviour is taken as the thermodynamic fingerprint of quantum criticality in the vicinity of a quantum phase transition.

  15. Quantum criticality at the superconductor-insulator transition revealed by specific heat measurements

    Science.gov (United States)

    Poran, S.; Nguyen-Duc, T.; Auerbach, A.; Dupuis, N.; Frydman, A.; Bourgeois, Olivier

    2017-01-01

    The superconductor–insulator transition (SIT) is considered an excellent example of a quantum phase transition that is driven by quantum fluctuations at zero temperature. The quantum critical point is characterized by a diverging correlation length and a vanishing energy scale. Low-energy fluctuations near quantum criticality may be experimentally detected by specific heat, cp, measurements. Here we use a unique highly sensitive experiment to measure cp of two-dimensional granular Pb films through the SIT. The specific heat shows the usual jump at the mean field superconducting transition temperature marking the onset of Cooper pairs formation. As the film thickness is tuned towards the SIT, is relatively unchanged, while the magnitude of the jump and low-temperature specific heat increase significantly. This behaviour is taken as the thermodynamic fingerprint of quantum criticality in the vicinity of a quantum phase transition. PMID:28224994

  16. ‘‘Cooling by Heating’’- Demonstrating the Significance of the Longitudinal Specific Heat

    DEFF Research Database (Denmark)

    Papini, Jon J.; Dyre, J. C.; Christensen, Tage Emil

    2012-01-01

    is generally considerably larger than in solids. This paper presents analytical solutions of the relevant coupled thermoviscoelastic equations. In general, there is a difference between the isobaric specific heat cp measured at constant isotropic pressure and the longitudinal specific heat cl pertaining...... between these two specific heats. For a typical glass-forming liquid, when the temperature at the surface is increased by 1 K, a lowering of the temperature at the sphere center of the order of 5 mK is expected if the experiment is performed at the glass transition. The cooling-by-heating effect......Heating a solid sphere at its surface induces mechanical stresses inside the sphere. If a finite amount of heat is supplied, the stresses gradually disappear as temperature becomes homogeneous throughout the sphere. We show that before this happens, there is a temporary lowering of pressure...

  17. Measurements of thermal diffusivity, specific heat capacity and thermal conductivity with LFA 447 apparatus

    DEFF Research Database (Denmark)

    Zajas, Jan Jakub; Heiselberg, Per

    The LFA 447 can be successfully used for measurements of thermal diffusivity, specific heat and thermal conductivity of various samples. It is especially useful when determining the properties of materials on a very small scale. The matrix measurement mode allows for determining the local...... properties with a fine resolution, down to 1 millimeter. Special attention needs to be taken when determining the specific heat capacity in the comparative method. First of all, the test and reference sample should be of nearly identical thickness. Secondly, their heat diffusion time should be comparable, so...... that the heat losses from both samples during the measurement are similar. Finally, the leveling of the samples is very important. Very small discrepancies can cause a massive error in the derivation of specific heat capacity and, as a result, thermal conductivity....

  18. The specific heat of alumel and chromel alloys near their magnetic transitions

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, E. [Univ. del Atlantico, Barranquilla (Colombia). Dept. de Fisica; Jurado, J.F. [Dept. de Fisica, Univ. Autonoma de Occidente, Cali (Colombia); Vargas, R.A. [Dept. de Fisica, Univ. del Valle, Cali (Colombia)

    1996-10-15

    We report the results of specific heat measurements at zero magnetic field and normal pressure on chromel (90% Ni-10% Cr) and alumel (95% Ni-2% Mn-2% Al) alloys using high-resolution a.c. calorimetry. We find a large anomaly in the specific heat at 225 K (for chromel) and at 463 K (for alumel), which is associated with the transition of each alloy into a ferromagnetic ordering when they are cooled below their corresponding Curie points. The experimental data for both alloys are compared with previously reported specific heat data of pure Ni Near T{sub c}, and for both alloys a critical behavior quite similar to Ni is found. (orig.)

  19. Phonon spectrum of YBCO obtained by specific heat inversion method for real data

    CERN Document Server

    Tao Wen; Dai Xian Xi; Dai Ji Xin; Evenson, W E

    2003-01-01

    In this paper, the phonon spectrum of YBCO is obtained from experimental specific heat data by an exact inversion formula with a parameter for eliminating divergences. The results can be compared to those of neutron inelastic scattering, which can only be carried out in a few laboratories. Some key points of specific heat-phonon spectrum inversion (SPI) theory and a method of asymptotic behaviour control are discussed. An improved unique existence theorem is presented, and a universal function set for numerical calculation of SPI is calculated with high accuracy, which makes the inversion method applicable and convenient in practice. This is the first time specific heat-phonon SPI has been realized for a concrete system.

  20. Theoretical analysis for the specific heat and thermal parameters of solid C60

    Science.gov (United States)

    Soto, J. R.; Calles, A.; Castro, J. J.

    1997-08-01

    We present the results of a theoretical analysis for the thermal parameters and phonon contribution to the specific heat in solid C60. The phonon contribution to the specific heat is calculated through the solution of the corresponding dynamical matrix, for different points in the Brillouin zone, and the construccion of the partial and generalized phonon density of states. The force constants are obtained from a first principle calculation, using a SCF Hartree-Fock wave function from the Gaussian 92 program. The thermal parameters reported are the effective temperatures and vibrational amplitudes as a function of temperature. Using this model we present a parametization scheme in order to reproduce the general behaviour of the experimental specific heat for these materials.

  1. Frequency-dependent specific heat from thermal effusion in spherical geometry.

    Science.gov (United States)

    Jakobsen, Bo; Olsen, Niels Boye; Christensen, Tage

    2010-06-01

    We present a method of measuring the frequency-dependent specific heat at the glass transition applied to 5-polyphenyl-4-ether. The method employs thermal waves effusing radially out from the surface of a spherical thermistor that acts as both a heat generator and a thermometer. It is a merit of the method compared to planar effusion methods that the influence of the mechanical boundary conditions is analytically known. This implies that it is the longitudinal rather than the isobaric specific heat that is measured. As another merit the thermal conductivity and specific heat can be found independently. The method has highest sensitivity at a frequency where the thermal diffusion length is comparable to the radius of the heat generator. This limits in practice the frequency range to 2-3 decades. An account of the 3ω technique used including higher-order terms in the temperature dependence of the thermistor and in the power generated is furthermore given.

  2. Spin excitations and the electronic specific heat of URu2Si2

    DEFF Research Database (Denmark)

    Mason, T.E.; Buyers, W.J.L.

    1991-01-01

    and conduction electrons yields m*/m(b) almost-equal-to 7.7 for T T(N) which is sufficient to account for the difference between band-structure calculations and the measured electronic specific heat. In addition, inclusion of the temperature dependence of the spin...... excitations as T(N) is approached from below reproduces, qualitatively, the peak observed in the specific heat at T(N). The peak arises from a gap in the spin, not charge spectrum below T(N)....

  3. Determination of the thermal conductivity and specific heat capacity of neem seeds by inverse problem method

    Directory of Open Access Journals (Sweden)

    S.N. Nnamchi

    2010-01-01

    Full Text Available Determination of the thermal conductivity and the specific heat capacity of neem seeds (Azadirachta indica A. Juss usingthe inverse method is the main subject of this work. One-dimensional formulation of heat conduction problem in a spherewas used. Finite difference method was adopted for the solution of the heat conduction problem. The thermal conductivityand the specific heat capacity were determined by least square method in conjunction with Levenberg-Marquardt algorithm.The results obtained compare favourably with those obtained experimentally. These results are useful in the analysis ofneem seeds drying and leaching processes.

  4. Specific heat of underdoped cuprate superconductors from a phenomenological layered Boson–Fermion model

    Energy Technology Data Exchange (ETDEWEB)

    Salas, P., E-mail: patysalasc@hotmail.com; Fortes, M.; Solís, M.A.; Sevilla, F.J.

    2016-05-15

    Highlights: • We present a superconductivity model which includes the Boson–Fermion model and extend it to layered structures. • The model straightforwardly predicts and reproduces the electronic specific heat of underdoped cuprates. • The linear component of the electronic specific heat, and the quadratic and cubic behaviors for low temperatures are obtained. • The total specific heat is built giving very satisfactory results. • The mass anisotropy is explained through this model. - Abstract: We adapt the Boson–Fermion superconductivity model to include layered systems such as underdoped cuprate superconductors. These systems are represented by an infinite layered structure containing a mixture of paired and unpaired fermions. The former, which stand for the superconducting carriers, are considered as noninteracting zero spin composite-bosons with a linear energy–momentum dispersion relation in the CuO{sub 2} planes where superconduction is predominant, coexisting with the unpaired fermions in a pattern of stacked slabs. The inter-slab, penetrable, infinite planes are generated by a Dirac comb potential, while paired and unpaired electrons (or holes) are free to move parallel to the planes. Composite-bosons condense at a critical temperature at which they exhibit a jump in their specific heat. These two values are assumed to be equal to the superconducting critical temperature T{sub c} and the specific heat jump reported for YBa{sub 2}Cu{sub 3}O{sub 6.80} to fix our model parameters namely, the plane impenetrability and the fraction of superconducting charge carriers. We then calculate the isochoric and isobaric electronic specific heats for temperatures lower than T{sub c} of both, the composite-bosons and the unpaired fermions, which matches the latest experimental curves. From the latter, we extract the linear coefficient (γ{sub n}) at T{sub c}, as well as the quadratic (αT{sup 2}) term for low temperatures. We also calculate the lattice

  5. Specific heats of lunar surface materials from 90 to 350 degrees Kelvin

    Science.gov (United States)

    Robie, R.A.; Hemingway, B.S.; Wilson, W.H.

    1970-01-01

    The specific heats of lunar samples 10057 and 10084 returned by the Apollo 11 mission have been measured between 90 and 350 degrees Kelvin by use of an adiabatic calorimeter. The samples are representative of type A vesicular basalt-like rocks and of finely divided lunar soil. The specific heat of these materials changes smoothly from about 0.06 calorie per gram per degree at 90 degrees Kelvin to about 0.2 calorie per gram per degree at 350 degrees Kelvin. The thermal parameter ??=(k??C)-1/2 for the lunar surface will accordingly vary by a factor of about 2 between lunar noon and midnight.

  6. Specific heat of pristine and brominated graphite fibers, composites and HOPG. [Highly Oriented Pyrolytic Graphite

    Science.gov (United States)

    Hung, Ching-Chen; Maciag, Carolyn

    1987-01-01

    Differential scanning calorimetry was used to obtain specific heat values of pristine and brominated P-100 graphite fibers and brominated P-100/epoxy composite as well as pristine and brominated highly oriented pyrolytic graphite (HOPG) for comparison. Based on the experimental results obtained, specific heat values are calculated for several different temperatures, with a standard deviation estimated at 1.4 percent of the average values. The data presented here are useful in designing heat transfer devices (such as airplane de-icing heaters) from bromine fibers.

  7. Low-temperature specific heat of YMn{sub 2} in the paramagnetic and antiferromagnetic phases

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, R.A.; Emerson, J.P.; Phillips, N.E. [Lawrence Berkeley Lab., CA (United States); Ballou, R.; Lelievre-Berna, E. [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France). Lab. Louis Neel

    1992-07-01

    The low-temperature specific heat of YMn{sub 2} has been measured at applied pressures of 0 to 7.7 kbar. A paramagnetic state is stabilized for moderate values of the applied pressure (of the order of 1.6 kbar). A large linear term in the specific heat, which decreases regularly with increasing pressure, is observed in this phase. It is ascribed to giant spin fluctuations associated with a magnetic-non magnetic instability and a strong geometrical spin frustration.

  8. Low-temperature specific heat of YMn sub 2 in the paramagnetic and antiferromagnetic phases

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, R.A.; Emerson, J.P.; Phillips, N.E. (Lawrence Berkeley Lab., CA (United States)); Ballou, R.; Lelievre-Berna, E. (Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France). Lab. Louis Neel)

    1992-07-01

    The low-temperature specific heat of YMn{sub 2} has been measured at applied pressures of 0 to 7.7 kbar. A paramagnetic state is stabilized for moderate values of the applied pressure (of the order of 1.6 kbar). A large linear term in the specific heat, which decreases regularly with increasing pressure, is observed in this phase. It is ascribed to giant spin fluctuations associated with a magnetic-non magnetic instability and a strong geometrical spin frustration.

  9. 热解过程中生物质半焦比热容的测定%Determination of specific heat capacity of biomass char during pyrolysis

    Institute of Scientific and Technical Information of China (English)

    陈群; 庞任重; 陈熙; 杨锐明; 禚玉群; 陈昌和

    2014-01-01

    The specific heat capacities of chars during primary pyrolysis of biomass with different conversion and the heat capacities of virgin biomass were determined.The ratio method was employed to measure the specific heat capacities of two biomass samples and their pyrolyzed chars through thermogravimetry and differential scanning calorimetry ( TG-DSC).A mathematical model was developed to calculate values of specific heat of chars.The results show that the specific heat capacitei s of the two biomass samples and their derived chars increase linearly within 60~200℃.The values oft he specific heat capacity fo the chars are lower than those fo the virgin biomass samples.The specific heat of chars decreases as the extent of pyrolysis increases.The calculated specific heat capacities from the developed mathematical model are quite close to those me asured by TG-DSC analyses eb twe n 150~200℃.%采用热重-差示量热扫描法( TG-DSC)测量了生物质和一次热解焦炭及不同转化率下半焦的比热容,建立了计算半焦比热容的数学模型并与实验测量结果进行了对比。结果表明,生物质样品和热解焦炭的比热容在60~200℃随温度升高而线性增大。生物质焦炭的比热容低于生物质样品的比热容,从60℃时的1.2 J/(g· K)增大到200℃附近的1.8~2.0 J/(g· K)。生物质半焦比热容随热解转化率的提高而降低。由半焦比热容数学模型计算得到的结果在接近150~200℃时与实验测定的半焦比热容数值基本一致。

  10. Low temperature specific heat of the spin-density-wave compound (TMTSF)2PF6

    DEFF Research Database (Denmark)

    Odin, J.; Lasjaunias, J.C.; Biljakovic, K.;

    1994-01-01

    We report on specific heat measurements of the SDW compound (TMTSF)2PF6 between 2 and 25 K, performed by two different techniques. We discuss the two successive transitions which occur in this T-range : the SDW ordering transition at T = 12.1 K, and a glass transition around-3-3.5 K. The latter...

  11. The Heat Is on: An Inquiry-Based Investigation for Specific Heat

    Science.gov (United States)

    Herrington, Deborah G.

    2011-01-01

    A substantial number of upper-level science students and practicing physical science teachers demonstrate confusion about thermal equilibrium, heat transfer, heat capacity, and specific heat capacity. The traditional method of instruction, which involves learning the related definitions and equations, using equations to solve heat transfer…

  12. Dynamic properties of silica aerogels as deduced from specific-heat and thermal-conductivity measurements

    DEFF Research Database (Denmark)

    Bernasconi, A.; Sleator, T.; Posselt, D.;

    1992-01-01

    The specific heat C(p) and the thermal conductivity lambda of a series of base-catalyzed silica aerogels have been measured at temperatures between 0.05 and 20 K. The results confirm that the different length-scale regions observed in the aerogel structure are reflected in the dynamic behavior...

  13. Low-temperature specific-heat and thermal-conductivity of silica aerogels

    DEFF Research Database (Denmark)

    Bernasconi, A.; Sleator, T.; Posselt, D.;

    1992-01-01

    Specific heat, C(p), and thermal conductivity, lambda, have been measured on a series of base-catalyzed silica aerogels at temperatures between 0.05 and 20 K. Results for both C(p)(T) and lambda(T) confirm that the different length-scale regions observed in the aerogel structure are reflected...

  14. Low-temperature specific heat and thermal conductivity of silica aerogels

    DEFF Research Database (Denmark)

    Sleator, T.; Bernasconi, A.; Posselt, D.;

    1991-01-01

    Specific-heat and thermal-conductivity measurements were made on a series of base-catalyzed silica aerogels at temperatures between 0.05 and 20 K. Evidence for a crossover between regimes of characteristically different excitations was observed. The data analysis indicates a "bump" in the density...

  15. Pauli Spin Paramagnetism and Electronic Specific Heat in Generalised d-Dimensions

    Institute of Scientific and Technical Information of China (English)

    Muktish Acharyya

    2011-01-01

    The variations of pauli spin paramagnetic susceptibility and the electronic specific heat of solids, are calculated as functions of temperature following the free electron approximation, in generalised d-dimensions.The results are compared and become consistent with that obtained in three dimensions.Interestingly, the Pauli spin paramagnetic susceptibility becomes independent of temperature only in two dimensions.

  16. Derivation of Varying Specific Heat Gasdynamic Functions,Normal Shock Analytical Solution and its Improvements

    Institute of Scientific and Technical Information of China (English)

    TsuiChih-Ya

    1992-01-01

    A set of new gasdynamic functions with varying specific heat are deriveo for the first time.An original analytical solution of normal shock waves is owrked out therewith.This solution is thereafter further improved by not involving total temperature,Illustrative examples of comparison are given,including also some approximate solutions to show the orders of their errors.

  17. Determination of the specific heat petroleum derivates; Determinacao do calor especifico de derivados ultrapesados de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Ballesteros Hernandez, Julie A.; Zuniga Linan, Lamia; Jardini, Andre; Maciel, Maria Regina Wolf; Maciel Filho, Rubens Maciel [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Quimica; Medina, Lilian Carmen [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

    2008-07-01

    In the development of the specific mathematical modeling for heavy and ultra heavy petroleum fractions in a molecular distiller is very important the definition of physical and chemical parameters as density and specific heat of the mixture, the enthalpy of vaporization, among others, since they are used in the energy balance. Information on these properties and their variation with temperature are found in the open literature for mixture with few components (simple mixtures). However, for multicomponent solutions consisting of complex mixtures such as oil and its heavy and ultraheavy fractions, available data are few, or are limited to low temperatures. The specific heat is an important property in the energy balance. This property can be measured by Differential Scanning Calorimetry (DSC), which gives results with great sensitivity and accuracy. This paper presents the variation of specific heat with the temperature of ultra-heavy oil fractions in the range from 80 deg to 350 deg C . Through the study of this variation, the equation nowadays used can be adjusted, in order to determine the specific heat. New values of the constants are determined, so that the equation can be used for these complex products, optimizing the estimative of Cp and so no experimental data are always necessary for simulations. (author)

  18. Effect of nonmagnetic and magnetic impurities on the specific heat jump in anisotropic superconductors

    NARCIS (Netherlands)

    Openov, LA

    The specific-heat jump DeltaC at a critical temperature T-c in an anisotropic superconductor containing both potential and spin-flip scatterers is calculated within a weak-coupling mean-field approximation. It is shown that the presence of even a small amount of spin-flip scatterers in the sample

  19. Laboratory Activity: Specific Heat by Change in Internal Energy of Silly Putty

    Science.gov (United States)

    Koser, John

    2011-01-01

    Students in introductory physics courses often don't study thermodynamics or thermodynamic events. If any thermal physics is taught in introductory courses (e.g., Physics 101 for Liberal Arts Majors), it usually involves the concepts of specific heat and various temperature scales. Seldom are the first and second laws of thermodynamics taught in…

  20. Research on the Specific Heat Capacity of PBX Formulations Based on RDX

    Directory of Open Access Journals (Sweden)

    Flávio Rodrigues Chaves

    2016-07-01

    Full Text Available The experimental results of specific heat capacity of 2 plastic bonded explosives formulations based on 1,3,5-trinitroperhydro-1,3,5-triazine, using differential scanning calorimetry thermal analysis, and the theoretical ones calculated with the specific heat capacity and mass fraction of individual compounds are compared for a temperature range between 340 and 410 K. Apart the filler, the plastic bonded explosives composition includes the binder based on hydroxyl-terminated polybutadiene, the plasticizer bis (2-ethylhexyl sebacate and the curing agent isophorone diisocyanate. The experimental and theoretical results showed a better approach when no curing agent is added. Without curing agent, the specific heat capacity of plastic bonded explosives increases linearly with temperature. When plastic bonded explosive is cured, the specific heat capacity is nearly constant until 380 K and decreases linearly for higher temperature values. These results suggest that phase change requires adjusting parameters to different heating rates in order to describe adequately the experimental data.

  1. Temperature dependence of lattice vibrations and analysis of specific heat in graphite. Cooperative research

    Energy Technology Data Exchange (ETDEWEB)

    Nihira, Takeshi; Iwata, Tadao; Iwase, Akihiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-11-01

    The semi-continuum model of lattice vibrations of graphite proposed by Komatsu and Nagamiya is the only one that has succeeded in expressing analytically the dispersion relation of lattice vibrations. The expressions of the dispersion relation contain the interlayer spacing, c, and the elastic constants, C{sub 11}, C{sub 12}, C{sub 13}, C{sub 33}, C{sub 44} and {kappa}, as parameters, where c{rho}{kappa}{sup 2} is the bending elastic constants of a graphite layer and {rho} is the density. We improve the semi-continuum model by taking these parameters as a function of temperature. For the parameters except {kappa}, we use the experimental data already known and the relations derived from them. {kappa} is derived as a function of temperature by fitting the calculated specific heat to the experimental one. The improved semi-continuum model can explain the specific heat well in the temperature range below 360 K and be reliably used there for the analysis of thermal conductivity, etc.. {kappa} decreases largely with temperature increasing, which means that there occurs the softening of the out-of-plane vibration. The second derivative of the experimental specific heat curve with respect to temperature gives information on the frequency distribution of lattice vibrations. From the analysis of the low-temperature specific heat, the value of C{sub 44} at room temperature is determined to be 0.415 x 10{sup 11} dyn/cm{sup 2}. (author)

  2. Finite Size Effect on the Specific Heat of a Bose Gas in Multi-filament Cables

    Science.gov (United States)

    Guijarro, G.; Solís, M. A.

    2016-05-01

    The specific heat for an ideal Bose gas confined in semi-infinite multi-filament cables is analyzed. We start with a Bose gas inside a semi-infinite tube of impenetrable walls and finite rectangular cross section. The internal filament structure is created by applying to the gas two, mutually perpendicular, finite Kronig-Penney delta potentials along the tube cross section, while particles are free to move perpendicular to the cross section. The energy spectrum accessible to the particles is obtained and introduced into the grand potential to calculate the specific heat of the system as a function of temperature for different values of the periodic structure parameters such as the cross-section area, the wall impenetrability, and the number of filaments. The specific heat as a function of temperature shows at least two maxima and one minimum. The main difference with respect to the infinite case is that the peak associated with the BE condensation becomes a smoothed maximum, namely there is not a jump in the specific heat derivative, whose temperature no longer represents a critical point.

  3. The Heat Is on: An Inquiry-Based Investigation for Specific Heat

    Science.gov (United States)

    Herrington, Deborah G.

    2011-01-01

    A substantial number of upper-level science students and practicing physical science teachers demonstrate confusion about thermal equilibrium, heat transfer, heat capacity, and specific heat capacity. The traditional method of instruction, which involves learning the related definitions and equations, using equations to solve heat transfer…

  4. Laboratory Activity: Specific Heat by Change in Internal Energy of Silly Putty

    Science.gov (United States)

    Koser, John

    2011-01-01

    Students in introductory physics courses often don't study thermodynamics or thermodynamic events. If any thermal physics is taught in introductory courses (e.g., Physics 101 for Liberal Arts Majors), it usually involves the concepts of specific heat and various temperature scales. Seldom are the first and second laws of thermodynamics taught in…

  5. Specific heat of underdoped cuprate superconductors from a phenomenological layered Boson-Fermion model

    Science.gov (United States)

    Salas, P.; Fortes, M.; Solís, M. A.; Sevilla, F. J.

    2016-05-01

    We adapt the Boson-Fermion superconductivity model to include layered systems such as underdoped cuprate superconductors. These systems are represented by an infinite layered structure containing a mixture of paired and unpaired fermions. The former, which stand for the superconducting carriers, are considered as noninteracting zero spin composite-bosons with a linear energy-momentum dispersion relation in the CuO2 planes where superconduction is predominant, coexisting with the unpaired fermions in a pattern of stacked slabs. The inter-slab, penetrable, infinite planes are generated by a Dirac comb potential, while paired and unpaired electrons (or holes) are free to move parallel to the planes. Composite-bosons condense at a critical temperature at which they exhibit a jump in their specific heat. These two values are assumed to be equal to the superconducting critical temperature Tc and the specific heat jump reported for YBa2Cu3O6.80 to fix our model parameters namely, the plane impenetrability and the fraction of superconducting charge carriers. We then calculate the isochoric and isobaric electronic specific heats for temperatures lower than Tc of both, the composite-bosons and the unpaired fermions, which matches the latest experimental curves. From the latter, we extract the linear coefficient (γn) at Tc, as well as the quadratic (αT2) term for low temperatures. We also calculate the lattice specific heat from the ARPES phonon spectrum, and add it to the electronic part, reproducing the experimental total specific heat at and below Tc within a 5% error range, from which the cubic (ßT3) term for low temperatures is obtained. In addition, we show that this model reproduces the cuprates mass anisotropies.

  6. Specific heat flow rate: an on-line monitor and potential control variable of specific metabolic rate in animal cell culture that combines microcalorimetry with dielectric spectroscopy.

    Science.gov (United States)

    Guan, Y; Evans, P M; Kemp, R B

    1998-06-05

    One of the requirements for enhanced productivity by the animal culture systems used in biotechnology is the direct assessment of the metabolic rate by on-line biosensors. Based on the fact that cell growth is associated with an enthalpy change, it is shown that the specific heat flow rate is stoichiometrically related to the net specific rates of substrates, products, and indeed to specific growth rate, and therefore a direct reflection of metabolic rate. Heat flow rate measured by conduction calorimetry has a technical advantage over estimates for many material flows which require assays at a minimum of two discrete times to give the rate. In order to make heat flow rate specific to the amount of the living cellular system, it would be advantageous to divide it by viable biomass. This requirement has been fulfilled by combining a continuous flow microcalorimeter ex situ with a dielectric spectroscope in situ, the latter measuring the viable cell mass volume fraction. The quality of the resulting biosensor for specific heat flow rate was illustrated using batch cultures of Chinese hamster ovary cells (CHO 320) producing recombinant human interferon-gamma (IFN-gamma) during growth in a stirred tank bioreactor under fully aerobic conditions. The measuring scatter of the probe was decreased significantly by applying the moving average technique to the two participant signals. It was demonstrated that the total metabolic rate of the cells, as indicated by the specific heat flow rate sensor, decreased with increasing time in batch culture, coincident with the decline in the two major substrates, glucose and glutamine, and the accumulation of the by-products, ammonia and lactate. Furthermore, the specific heat flow rate was an earlier indicator of substrate depletion than the flow rate alone. The calorimetric-respirometric ratio showed the intensive participation of anaerobic processes during growth and the related IFN-gamma production. Specific heat flow rate was

  7. A molecular dynamics study on melting point and specific heat of Ni3Al alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Using the Embedding Atom Method(EAM)for highly undercooled Ni3Al alloy,the melting point and the specific heat were studied by a molecular dynamics simula-tion.The simulation of melting point was carried out by means of the sandwich method and the NVE ensemble method,and the results show a good agreement,whereas are larger than the experimental value of 1663 K.This difference is attrib-uted to the influence of surface melting on experimental results,which causes the smaller measurements compared with the thermodynamic melting point.The simulated specific heat of Ni3Al alloy weakly and linearly increases with the in-crease of undercooling in the temperature range from 800 K to 2000 K.

  8. Negative specific heat of black-holes from fluid-gravity correspondence

    Science.gov (United States)

    Bhattacharya, Swastik; Shankaranarayanan, S.

    2017-04-01

    Black holes in asymptotically flat space-times have negative specific heat—they get hotter as they loose energy. A clear statistical mechanical understanding of this has remained a challenge. In this work, we address this issue using fluid-gravity correspondence which aims to associate fluid degrees of freedom to the horizon. Using linear response theory and the teleological nature of event horizon, we show explicitly that the fluctuations of the horizon-fluid lead to negative specific heat for a Schwarzschild black Hole. We also point out how the specific heat can be positive for Kerr–Newman or AdS black holes. Our approach constitutes an important advance as it allows us to apply the canonical ensemble approach to study thermodynamics of asymptotically flat black hole space-times.

  9. Thermal conductivity, electrical conductivity and specific heat of copper-carbon fiber composite

    Science.gov (United States)

    Kuniya, Keiichi; Arakawa, Hideo; Kanai, Tsuneyuki; Chiba, Akio

    1988-01-01

    A new material of copper/carbon fiber composite is developed which retains the properties of copper, i.e., its excellent electrical and thermal conductivity, and the property of carbon, i.e., a small thermal expansion coefficient. These properties of the composite are adjustable within a certain range by changing the volume and/or the orientation of the carbon fibers. The effects of carbon fiber volume and arrangement changes on the thermal and electrical conductivity, and specific heat of the composite are studied. Results obtained are as follows: the thermal and electrical conductivity of the composite decrease as the volume of the carbon fiber increases, and were influenced by the fiber orientation. The results are predictable from a careful application of the rule of mixtures for composites. The specific heat of the composite was dependent, not on fiber orientation, but on fiber volume. In the thermal fatigue tests, no degradation in the electrical conductivity of this composite was observed.

  10. A molecular dynamics study on melting point and specific heat of Ni3Al alloy

    Institute of Scientific and Technical Information of China (English)

    YANG Hong; L(U) YongJun; CHEN Min; GUO ZengYuan

    2007-01-01

    Using the Embedding Atom Method (EAM) for highly undercooled Ni3Al alloy, the melting point and the specific heat were studied by a molecular dynamics simulation. The simulation of melting point was carried out by means of the sandwich method and the NVE ensemble method, and the results show a good agreement, whereas are larger than the experimental value of 1663 K. This difference is attributed to the influence of surface melting on experimental results, which causes the smaller measurements compared with the thermodynamic melting point. The simulated specific heat of Ni3Al alloy weakly and linearly increases with the increase of undercooling in the temperature range from 800 K to 2000 K.

  11. The DNA electronic specific heat at low temperature: The role of aperiodicity

    Energy Technology Data Exchange (ETDEWEB)

    Sarmento, R.G. [Departamento de Física, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN (Brazil); Mendes, G.A. [Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN (Brazil); Albuquerque, E.L., E-mail: eudenilson@gmail.com [Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN (Brazil); Fulco, U.L. [Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN (Brazil); Vasconcelos, M.S. [Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN (Brazil); Ujsághy, O. [Department of Theoretical Physics and Condensed Matter Research Group of the Hungarian Academy of Sciences, Budapest University of Technology and Economics, Budafoki út 8, H-1521 Budapest (Hungary); Freire, V.N. [Departamento de Física, Universidade Federal do Ceará, 60455-760, Fortaleza, CE (Brazil); Caetano, E.W.S. [Instituto Federal de Educação, Ciência e Tecnologia do Ceará, 60040-531, Fortaleza, CE (Brazil)

    2012-07-16

    The electronic specific heat spectra at constant volume (C{sub V}) of a long-range correlated extended ladder model, mimicking a DNA molecule, is theoretically analyzed for a stacked array of a double-stranded structure made up from the nucleotides guanine G, adenine A, cytosine C and thymine T. The role of the aperiodicity on C{sub V} is discussed, considering two different nucleotide arrangements with increasing disorder, namely the Fibonacci and the Rudin–Shapiro quasiperiodic structures. Comparisons are made for different values of the band fillings, considering also a finite segment of natural DNA, as part of the human chromosome Ch22. -- Highlights: ► Quasiperiodic sequence to mimic the DNA nucleotides arrangement. ► Electronic tight-binding Hamiltonian model. ► Electronic density of states. ► Electronic specific heat spectra.

  12. Thermal behavior, specific heat capacity and adiabatic time-to-explosion of G(FOX-7).

    Science.gov (United States)

    Xu, Kangzhen; Song, Jirong; Zhao, Fengqi; Ma, Haixia; Gao, Hongxu; Chang, Chunran; Ren, Yinghui; Hu, Rongzu

    2008-10-30

    [H(2)N=C(NH(2))(2)](+)(FOX-7)(-)-G(FOX-7) was prepared by mixing FOX-7 and guanidinium chloride solution in potassium hydroxide solution. Its thermal decomposition was studied under the non-isothermal conditions with DSC and TG/DTG methods. The apparent activation energy (E) and pre-exponential constant (A) of the two exothermic decomposition stages were obtained by Kissinger's method and Ozawa's method, respectively. The critical temperature of thermal explosion (T(b)) was obtained as 201.72 degrees C. The specific heat capacity of G(FOX-7) was determined with Micro-DSC method and theoretical calculation method and the standard molar specific heat capacity is 282.025 J mol(-1) K(-1) at 298.15 K. Adiabatic time-to-explosion of G(FOX-7) was also calculated to be a certain value between 13.95 and 15.66 s.

  13. An International Round-Robin Study, Part II: Thermal Diffusivity, Specific Heat and Thermal Conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hsin [ORNL; Porter, Wallace D [ORNL; Bottner, Harold [Fraunhofer-Institute, Freiburg, Germany; Konig, Jan [Fraunhofer-Institute, Freiburg, Germany; Chen, Lidong [Chinese Academy of Sciences; Bai, Shengqiang [Chinese Academy of Sciences; Tritt, Terry M. [Clemson University; Mayolett, Alex [Corning, Inc; Senawiratne, Jayantha [Corning, Inc; Smith, Charlene [Corning, Inc; Harris, Fred [ZT-Plus; Gilbert, Partricia [Marlow Industries, Inc; Sharp, J [Marlow Industries, Inc; Lo, Jason [CANMET - Materials Technology Laboratory, Natural Resources of Canada; Keinke, Holger [University of Waterloo, Canada; Kiss, Laszlo I. [University of Quebec at Chicoutimi

    2013-01-01

    For bulk thermoelectrics, figure-of-merit, ZT, still needs to improve from the current value of 1.0 - 1.5 to above 2 to be competitive to other alternative technologies. In recent years, the most significant improvements in ZT were mainly due to successful reduction of thermal conductivity. However, thermal conductivity cannot be measured directly at high temperatures. The combined measurements of thermal diffusivity and specific heat and density are required. It has been shown that thermal conductivity is the property with the greatest uncertainty and has a direct influence on the accuracy of the figure of merit. The International Energy Agency (IEA) group under the implementing agreement for Advanced Materials for Transportation (AMT) has conducted two international round-robins since 2009. This paper is Part II of the international round-robin testing of transport properties of bulk bismuth telluride. The main focuses in Part II are on thermal diffusivity, specific heat and thermal conductivity.

  14. Theoretical approach to the phonon modes and specific heat of germanium nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Trejo, A.; López-Palacios, L.; Vázquez-Medina, R.; Cruz-Irisson, M., E-mail: irisson@ipn.mx

    2014-11-15

    The phonon modes and specific heat of Ge nanowires were computed using a first principles density functional theory scheme with a generalized gradient approximation and finite-displacement supercell algorithms. The nanowires were modeled in three different directions: [001], [111], and [110], using the supercell technique. All surface dangling bonds were saturated with Hydrogen atoms. The results show that the specific heat of the GeNWs at room temperature increases as the nanowire diameter decreases, regardless the orientation due to the phonon confinement and surface passivation. Also the phonon confinement effects could be observed since the highest optical phonon modes in the Ge vibration interval shifted to a lower frequency compared to their bulk counterparts.

  15. Specific heat of the non-centrosymmetric superconductor Re3W

    Institute of Scientific and Technical Information of China (English)

    Yan Jing; Shan Lei; Luo Qiang; Wang Wei-Hua; Wen Hai-Hu

    2009-01-01

    The alloys of non-centrosymmetric superconductor, Re3W, which were reported to have an α-Mn structure [P.Greenfield and P. A. Beck, J. Metals, N. Y. 8, 265 (1959)] with Tc = 9 K, are prepared by arc melting. The values of ac susceptibility and the low-temperature specific heat of these alloys are measured. It is found that there are two superconducting phases coexisting in the samples with Tc1 ≈ 9 K and Tc2≈7 K, which are both non-centrosymmetric in structure as reported previously. By analysing the specific heat data measured in various magnetic fields down to a temperature of 1.8 K, we find that the absence of the inversion symmetry does not lead to an obvious deviation from an s-wave pairing symmetry in Re3W.

  16. Magnon specific heat and free energy of Heisenberg ferromagnetic single-walled nanotubes: Green's function approach

    Science.gov (United States)

    Mi, Bin-Zhou; Zhai, Liang-Jun; Hua, Ling-Ling

    2016-01-01

    The effect of magnetic spin correlation on the thermodynamic properties of Heisenberg ferromagnetic single-walled nanotubes are comprehensively investigated by use of the double-time Green's function method. The influence of temperature, spin quantum number, diameter of the tube, anisotropy strength and external magnetic field to internal energy, free energy, and magnon specific heat are carefully calculated. Compared to the mean field approximation, the consideration of the magnetic correlation effect significantly improves the internal energy values at finite temperature, while it does not so near zero temperature, and this effect is related to the diameter of the tube, anisotropy strength, and spin quantum number. The magnetic correlation effect lowers the internal energy at finite temperature. As a natural consequence of the reduction of the internal energy, the specific heat is reduced, and the free energy is elevated.

  17. Error Analysis on Determination of Specific Heat of Agricultural Products Using Mixture Method

    Directory of Open Access Journals (Sweden)

    Ropiudin

    2006-04-01

    Full Text Available This paper reporting method of error analysis in determination of specific heat of agricultural product using mixture method. There are six Variables evaluated on error measurement, those are: mass of water, mass of simple, equilibrium temparature, water temparature, sample temparature and calorimeter temperature. As the results of experiment on potatoes and carrot, calorimeter temperature gave biggest error contribution based on simulation conducted using Visual Basic Application (VBA at Microsoft Word.

  18. Generalized computer algorithms for enthalpy, entropy and specific heat of superheated vapors

    Science.gov (United States)

    Cowden, Michael W.; Scaringe, Robert P.; Gebre-Amlak, Yonas D.

    This paper presents an innovative technique for the development of enthalpy, entropy, and specific heat correlations in the superheated vapor region. The method results in a prediction error of less than 5 percent and requires the storage of 39 constants for each fluid. These correlations are obtained by using the Beattie-Bridgeman equation of state and a least-squares regression for the coefficients involved.

  19. Thermophysical Properties of Matter - The TPRC Data Series. Volume 4. Specific Heat - Metallic Elements and Alloys

    Science.gov (United States)

    1971-01-01

    use it as a teaching tool to point out to his students the topography of the state of knowledge on the specific heat of metals. We believe there is...Experimental Thermochemistry , Vol. I, Interscience, New York, 1956. 60. Weissberger, A. (Editor), "Calorimetry" in Technique of Organic Chemistry Vol. I...Physical Methods of Organic Chemistry, Chap. X, Interscience, New York, 1959. 61. Skinner, H. A. (Editor), Experimental Thermochemistry , Vol. II

  20. Accurate determination of specific heat at high temperatures using the flash diffusivity method

    Science.gov (United States)

    Vandersande, J. W.; Zoltan, A.; Wood, C.

    1989-01-01

    The flash diffusivity method of Parker et al. (1961) was used to measure accurately the specific heat of test samples simultaneously with thermal diffusivity, thus obtaining the thermal conductivity of these materials directly. The accuracy of data obtained on two types of materials (n-type silicon-germanium alloys and niobium), was + or - 3 percent. It is shown that the method is applicable up to at least 1300 K.

  1. Negative specific heat of black-holes from Fluid-Gravity Correspondence

    OpenAIRE

    Bhattacharya, Swastik; Shankaranarayanan, S.

    2017-01-01

    Black-holes in asymptotically flat space-times have negative specific heat --- they get hotter as they loose energy. A clear statistical mechanical understanding of this has remained a challenge. In this work, we address this issue using fluid-gravity correspondence which aims to associate fluid degrees of freedom to the horizon. Using linear response theory and the teleological nature of event horizon, we show explicitly that the fluctuations of the horizon-fluid lead to negative specific he...

  2. Hyperfine specific heats of PrX 2 ( X = Ir, Pt, Rh, Ru) laves phase compounds

    Science.gov (United States)

    Greidanus, F. J. A. M.; de Jongh, L. J.; Huiskamp, W. J.; Buschow, K. H. J.

    1980-01-01

    Specific heat data below 1 K for the C-15 compounds PrX 2 (X = Ir, Pt, Rh, Ru) reveal Schottky-type anomalies, ascribed to hyperfine interactions. Apparently the 4f-moments are magnetically ordered. The values deduced for these moments are only ≈ 70% of that for J = 4, indicating that the Pr 3+ moment is partially quenched by the crystal field.

  3. Reply to ``Comment on `T3 specific-heat anomaly in network solids' ''

    Science.gov (United States)

    Phillips, J. C.

    1987-02-01

    My paper asserted that a wide range of data supports a structural model of melt-quenched vitreous silica based on defective cristobalite microcrystallites. These defects may contribute to the apparent ``excess T3'' term in the specific heat. This model is supported by recent data on porous vitreous silica prepared by the sol-gel method. The older model, based on analogies with the vibrational spectrum of crystalline Ge, has become less plausible in the overall context of presently available data.

  4. Specific heat and related thermophysical properties of liquid Fe-Cu-Mo alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The specific heat and related thermophysical properties of liquid Fe77.5Cu13Mo9.5 monotectic alloy were investigated by an electromagnetic levitation drop calo-rimeter over a wide temperature range from 1482 to 1818 K.A maximum under-cooling of 221 K(0.13 Tm)was achieved and the specific heat was determined as 44.71 J·mol1·K1.The excess specific heat,enthalpy change,entropy change and Gibbs free energy difference of this alloy were calculated on the basis of experimental results.It was found that the calculated results by traditional esti-mating methods can only describe the solidification process under low under-cooling conditions.Only the experimental results can reflect the reality under high undercooling conditions.Meanwhile,the thermal diffusivity,thermal conductivity,and sound speed were derived from the present experimental results.Furthermore,the solidified microstructural morphology was examined,which consists of(Fe)and(Cu)phases.The calculated interface energy was applied to exploring the correlation between competitive nucleation and solidification microstructure within monotectic alloy.

  5. Specific heat and related thermophysical properties of liquid Fe-Cu-Mo alloy

    Institute of Scientific and Technical Information of China (English)

    WANG HaiPeng; LUO BingChi; CHANG Jian; WEI BingBo

    2007-01-01

    The specific heat and related thermophysical properties of liquid Fe77.5Cu13Mo9.5 monotectic alloy were investigated by an electromagnetic levitation drop calorimeter over a wide temperature range from 1482 to 1818 K. A maximum undercooling of 221 K (0.13 Tm) was achieved and the specific heat was determined as 44.71 J·mol-1·K-1. The excess specific heat, enthalpy change, entropy change and Gibbs free energy difference of this alloy were calculated on the basis of experimental results. It was found that the calculated results by traditional estimating methods can only describe the solidification process under low undercooling conditions. Only the experimental results can reflect the reality under high undercooling conditions. Meanwhile, the thermal diffusivity, thermal conductivity, and sound speed were derived from the present experimental results. Furthermore, the solidified microstructural morphology was examined, which consists of (Fe) and (Cu) phases. The calculated interface energy was applied to exploring the correlation between competitive nucleation and solidification microstructure within monotectic alloy.

  6. Energy fluctuations and the singularity of specific heat in a 3D Ising model

    Science.gov (United States)

    Kaupuzs, Jevgenijs

    2004-05-01

    We study the energy fluctuations in 3D Ising model near the phase transition point. Specific heat is a relevant quantity which is directly related to the mean squared amplitude of the energy fluctuations in the system. We have made extensive Monte Carlo simulations in 3D Ising model to clarify the character of the singularity of the specific heat Cv based on the finite-size scaling of its maximal values Cvmax depending on the linear size of the lattice L. An original iterative method has been used which automatically finds the pseudocritical temperature corresponding to the maximum of Cv. The simulations made up to L Wolff's cluster algorithm allowed us to verify the possible power-like as well as logarithmic singularity of the specific heat predicted by different theoretical treatments. The most challenging and interesting result we have obtained is that the finite-size scaling of Cvmax in 3D Ising model is well described by a logarithmic rather than power-like ansatz, just like in 2D case. Another modification of our iterative method has been considered to estimate the critical coupling of 3D Ising model from the Binder cumulant data within L ɛ [96; 384]. Furthermore, the critical exponent β has been evaluated from the simulated magnetization data within the range of reduced temperatures t >= 0.000086 and system sizes L <= 410.

  7. Specific heat and magnetic interactions in NdCrO3

    Science.gov (United States)

    Bartolomé, Fernando; Bartolomé, Juan; Castro, Miguel; Melero, Julio J.

    2000-07-01

    The specific heat of NdCrO3 in the thermal range from 0.3 to 300 K is presented. The magnetic ordering of Cr ions at TN=219+/-1 K is observed, as well as the spin reorientation transition (SRT) at TSRT=34.2+/-0.5 K. The specific heat of the isostructural nonmagnetic compound LaGaO3 has been subtracted, allowing us to separate and quantify the different magnetic contributions to the specific heat in NdCrO3. The exchange coupling constant for the Cr-Cr interaction is found to be \\|JCr\\|/kB=21.7(7) K. The fitting of the Schottky contribution from the thermal depopulation of the Nd3+ 4I9/2 ground multiplet allows us to propose a crystal-field energy-level scheme which is in agreement with the available neutron-scattering spectral lines. The intensity of the Nd-Cr magnetic interaction is obtained. Finally, we show that the strength of the Nd-Cr interaction in this compound is of the same order of magnitude as that found in other Nd orthoperovskites, namely, in NdFeO3, despite the different Zeeman splitting of the Nd ground doublet in both compounds.

  8. Temperature-dependent specific heat of suspended platinum nanofilms at 80-380 K

    Science.gov (United States)

    Li, Qin-Yi; Narasaki, Masahiro; Takahashi, Koji; Ikuta, Tatsuya; Nishiyama, Takashi; Zhang, Xing

    2016-11-01

    Metallic nanofilms are important components of nanoscale electronic circuits and nanoscale sensors. The accurate characterization of the thermophysical properties of nanofilms is very important for nanoscience and nanotechnology. Currently, there is very little specific heat data for metallic nanofilms, and the existing measurements indicate distinct differences according to the nanofilm size. The present work reports the specific heats of 40-nm-thick suspended platinum nanofilms at 80-380 K and ˜5×10-4 Pa using the 3ω method. Over 80-380 K, the specific heats of the Pt nanofilms range from 166-304 J/(kg·K), which are 1.65-2.60 times the bulk values, indicating significant size effects. These results are useful for both scientific research in nanoscale thermophysics and evaluating the transient thermal response of nanoscale devices. Project supported by the National Natural Science Foundation of China (Grant Nos. 51327001 and 51636002), and partially supported by CREST, JST, and JSPS KAKENHI (Grant Nos. 16H04280, 26289047, 16K14174, and 16K06126).

  9. The effect of high temperature induced variation of specific heat on the hypersonic turbulent boundary layer and its computation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    For hypersonic vehicles,as the temperature in its boundary layer usually exceeds 600 K,for which the molecular vibrational degree of freedom is excited,the perfect gas model is no longer valid.In this paper,the effect of high temperature induced variation of specific heat on the hypersonic turbulent boundary layer of flat plates is investigated by direct numerical simulations with the perfect gas model,i.e.with constant specific heat,as well as with a variable specific heat gas model.The comparison of the results from the two gas models has found that the effect of the variation of specific heat on the velocity of the turbulent boundary layers is relatively small,while its effect on temperature,such as the mean temperature,the temperature fluctuations,is appreciable.It is also found that the mean specific heat is quite close to the specific heat calculated by using the mean temperature,indicating that it is possible to do turbulence modeling.The modeling is done under the variable specific heat gas model with the mean temperature as the variable.The feasibility of such consideration is verified by applying the SST model for variable specific heat turbulence computation.

  10. Evidence for unconventional superconductivity in UPt/sub 3/: Splitting of the specific heat anomaly at T/sub c/

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, N.E.; Fisher, R.A.; Kim, S.; Woodfield, B.F.; Taillefer, L.; Hasselbach, K.; Flouquet, J.; Giorgi, A.L.; Smith, J.L.

    1989-01-01

    The specific heats of two samples of UPt/sub 3/ have been measured in the vicinity of T/sub c/. Both samples show specific heat anomalies sharper than any previously observed and two clearly resolved maxima. The results are interpreted as evidence of splitting of the transition and unconventional pairing. 9 refs., 1 fig., 1 tab.

  11. Effects of phonon dimensionality in the specific heat of multiwall carbon nanotubes at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Jorge, Guillermo A; Bekeris, V; Acha, C [Laboratorio de Bajas Temperaturas, Departamento de Fisica, FCEyN-UBA, Pab. 1, Ciudad Universitaria (1428), Buenos Aires (Argentina); Escobar, M M; Goyanes, S [Laboratorio de Polimeros y Materiales Compuestos, Departamento de Fisica, FCEyN-UBA, Pab. 1, Ciudad Universitaria (1428), Buenos Aires (Argentina); Zilli, D; Cukierman, A L [PINMATE, Departamento de Industrias, FCEyN-UBA, Pab. Industrias, Ciudad Universitaria (1428), Buenos Aires (Argentina); Candal, R J, E-mail: gjorge@df.uba.a [Instituto de Fisicoquimica de Materiales, Ambiente y EnergIa, CONICET-UBA, Ciudad Universitaria (1428) Buenos Aires (Argentina)

    2009-05-01

    We have measured the specific heat at constant pressure, C{sub p}, of three different samples of multiwall carbon nanotubes (MWNT). For all samples, C{sub p} departs from a graphitic behavior at T < 120 K. C{sub p} measurements show a temperature threshold from a linear regime for intermediate temperature to a higher-order power law for low temperatures. Moreover, it was found that this crossover only depends on the internal structure of the individual MWNT and not on the spatial order of the MWNT within a bundle.

  12. Low-temperature specific heat of the superconductor Mo{sub 3}Sb{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Tran, V.H. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, PO Box 1410, 50-950 Wroclaw (Poland)], E-mail: v.h.tran@int.pan.wroc.pl; Miller, W. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, PO Box 1410, 50-950 Wroclaw (Poland); Bukowski, Z. [Laboratory for Solid State Physics, ETH Zuerich, 8093 Zuerich (Switzerland)

    2008-11-15

    The low-temperature specific heat of a superconductor Mo{sub 3}Sb{sub 7} with T{sub c} = 2.2 {+-} 0.05 K has been measured in magnetic fields up to 5 T. In the normal state, the electronic specific heat coefficient {gamma}{sub n}, and the Debye temperature {theta}{sub D} are found to be 34.5(2) mJ mol{sup -1} K{sup -2} and 283(5) K, respectively. The enhanced {gamma}{sub n} value is interpreted as due to a narrow Mo-4d band pinned at the Fermi level. The electronic specific heat in the superconducting state can be analyzed in terms a phenomenological two BCS-like gap model with the gap widths 2{delta}{sub 1}/k{sub B}T{sub c} = 4.0 and 2{delta}{sub 2}/k{sub B}T{sub c} = 2.5, and relative weights of the molar electronic heat coefficients {gamma}{sub 1}/{gamma}{sub n} = 0.7 and {gamma}{sub 2}/{gamma}{sub n} = 0.3. Some characteristic thermodynamic parameters for the studied superconductor, like the specific heat jump at T{sub c}, {delta}C(T{sub c})/{gamma}{sub n}T{sub c}, the electron-phonon coupling constant, {lambda}{sub e-ph}, the upper H{sub c2} and thermodynamic critical H{sub c0} fields, the penetration depth {lambda}, coherence length {xi} and the Ginzburg-Landau parameter {kappa} are evaluated. The estimated values of parameters such as 2{delta}{sub 0}/k{sub B}T{sub c}, {delta}C(T{sub c})/{gamma}{sub n}T{sub c}, N(E{sub F}) and {lambda}{sub e-ph} suggest that Mo{sub 3}Sb{sub 7} belongs to an intermediate-coupling regime. The electronic band structure calculations indicate that the density of states near the Fermi level is formed mainly by the Mo-4d orbitals and that there is no overlap between the Mo-4d and Sb-sp orbitals.

  13. An analysis of boundary-effects in obtaining the frequency dependent specific heat by effusivity measurements

    DEFF Research Database (Denmark)

    Christensen, Tage Emil; Behrens, Claus

    The frequency dependent specific heat is a significant response function characterizing the glass transition. Contrary to the dielectric response it is not easily measured over many decades. The introduction of the 3-omega method, where the temperature oscillations at a planar oscillatoric heat...... generator is measured, made this possible. The method relied on a 1-d solution to the heat diffusion equation. There have been attempts to invoke the boundary effects to first order. However we present the fully 3-d solution to the problem including these effects. The frequency range can hereby...

  14. Vortex Contribution to Specific Heat of Dirty $d$-Wave Superconductors: Breakdown of Scaling

    OpenAIRE

    Kuebert, C.; Hirschfeld, P. J.

    1997-01-01

    We consider the problem of the vortex contribution to thermal properties of dirty d-wave superconductors. In the clean limit, the main contribution to the density of states in a d-wave superconductor arises from extended quasiparticle states which may be treated semiclassically, giving rise to a specific heat contribution \\delta C(H)\\sim H^{1/2}. We show that the extended states continue to dominate the dirty limit, but lead to a H \\log H behavior at the lowest fields, H_{c1}\\ltsim H\\ll H_{c2...

  15. Specific Heat of the Spin-1/2 Antiferromagnetic Heisenberg Chain

    Institute of Scientific and Technical Information of China (English)

    云国宏; 梁希侠

    2001-01-01

    A simple analytic theory of thermodynamics at finite temperature for the spin-1/2 antiferromagnetic Heisenberg chain is proposed based on the picture of the particle-hole pair excitations. The dispersion relation of the particle-hole pairs is derived in the formulation of thermodynamic Bethe ansatz provided that the particles and holes have the same energy and they are excited as normalmodes. It is shown that the behaviour of the specific heat is in excellent agreement with the numerical and experimental results.

  16. The speed of sound and specific heat in the QCD plasma: hydrodynamics, fluctuations and conformal symmetry

    CERN Document Server

    Gavai, R V; Mukherjee, S; Gavai, Rajiv V.; Gupta, Sourendu; Mukherjee, Swagato

    2004-01-01

    We report the continuum limits of the speed of sound, c_s, and the specific heat at constant volume, c_v, in quenched QCD at temperatures of 2Tc and 3Tc. At these temperatures, c_s is within 2-sigma of the ideal gas value, whereas c_v differs significantly from the ideal gas. However, both are compatible with results expected in a theory with conformal symmetry. We investigate effective measures of conformal symmetry in the high temperature phase of QCD.

  17. Theory of specific heat of vortex liquid of high T c superconductors

    Science.gov (United States)

    Bai, Chen; Chi, Cheng; Wang, Jiangfan

    2016-10-01

    Superconducting thermal fluctuation (STF) plays an important role in both thermodynamic and transport properties in the vortex liquid phase of high T c superconductors. It was widely observed in the vicinity of the critical transition temperature. In the framework of Ginzburg-Landau-Lawrence-Doniach theory in magnetic field, a self-consistent analysis of STF including all Landau levels is given. Besides that, we calculate the contribution of STF to specific heat in vortex liquid phase for high T c cuprate superconductors, and the fitting results are in good agreement with experimental data. Project supported by the National Natural Science Foundation of China (Grant No. 11274018).

  18. Experimental Study on Specific Heat of Concrete at High Temperatures and Its Influence on Thermal Energy Storage

    Directory of Open Access Journals (Sweden)

    Jianwen Pan

    2016-12-01

    Full Text Available Using concrete as a thermal energy storage (TES material is a promising option for large-scale solar-thermal resource development and utilization. Specific heat is one of the most important characteristics for TES performance. In this paper, the half-open dynamic method based on the mixing principle is proposed and applied to measure concrete-specific heat at temperatures up to 600 °C. Measurement of the specific heat of corundum ceramic (99% Al2O3 is first performed, and the test results illustrate the accuracy and efficiency of the proposed test method. Furthermore, concrete-specific heat tests are carried out at high temperatures. It found that the specific heat increases as the temperature rises, especially, linearly in the range of 300–600 °C, in which the concrete TES module is expected to be in operation. Finally, the effect of concrete-specific heat changes with temperature on its TES capacity is investigated, demonstrating that specific heat is of great significance for concrete TES design for concentrating solar power.

  19. A new experimental method to determine specific heat capacity of inhomogeneous concrete material with incorporated microencapsulated-PCM

    DEFF Research Database (Denmark)

    Pomianowski, Michal Zbigniew; Heiselberg, Per; Jensen, Rasmus Lund

    2014-01-01

    PCM. This paper describes the development of the new material and the experimental set-up to determine the specific heat capacity of the PCM concrete material. Moreover, various methods are proposed and compared to calculate the specific heat capacity of the PCM concrete. Finally, it is hoped......The study presented in this paper focuses on an experimental investigation of the specific heat capacity as a function of the temperature Cp (T) of concrete mixed with various amounts of phase change material (PCM). The tested specimens are prepared by directly mixing concrete and microencapsulated...

  20. Spin-Wave Analysis of Specific Heat and Magnetization in EuO and EuS

    DEFF Research Database (Denmark)

    Dietrich, O. W.; Henderson, A. J.; Meyer, H.

    1975-01-01

    Recent neutron scattering measurements of the spin-wave spectrum have shown that the second-nearest-neighbor exchange constant in EuO is ferromagnetic, in disagreement with previously published results from both specific-heat and magnetization measurements. We undertook a thorough study of the bulk...... data on both EuO and its isomorph EuS, including some previously unpublished specific-heat data. The new analysis resolved the controversy regarding the specific heat, which is actually in good agreement with the neutron scattering results. However, the NMR data are more sensitive to effects other than...

  1. Phason-Strain Influence on Low-Temperature Specific Heat of the Decagonal Al-Ni-Co Quasicrystal

    Institute of Scientific and Technical Information of China (English)

    LI Cui-Lian; LIU You-Yan

    2001-01-01

    According to the quasicrystal continuum model and linear elasticity theory, based on the equivalence assumptionof phonons and phasons in quasicrystals, we have deduced five phase velocities of elastic wave propagating in the decagonal quasicrystals. By inserting these velocities into the specific heat expression, we have succeeded in explaining the experiment of specific heat performed on the single-grained decagonal AI-Ni-Co quasicrystalsat low temperature. Our results show that the contribution of the phason strain to the specific heat cannot beneglected at low temperature. Moreover, the phason-strain may be a main reason for the decagonal quasicrystalspossessing anisotropic thermal conductivity.

  2. Low temperature specific heat (zero field and with field) of Fe and Mn-doped MgB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Ashok [Department of Physics, Manipal Institute of Technology, Manipal 576104 (India)], E-mail: ashokanu_rao@rediffmail.com; Gahtori, Bhasker; Agarwal, S.K. [Superconductivity and Cryogenics Division, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Chakraborty, Tirthankar; Sarkar, Chandan Kumar [Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata 700032 (India); Das, Anirban [Department of Physics, Sikkim Manipal Institute of Technology, Majitar, Rangpo, Sikkim 737132 (India)

    2009-01-01

    Polycrystalline samples of MgB{sub 2} superconductor (Mn-doped as well as pristine) were investigated by measurements of the electrical resistivity, magneto-resistance in the temperature range of 4-300 K. All the samples show metallic behaviour. It is observed that the upper critical field slightly decreases with Mn concentration. Specific heat measurements were performed with field as well as without field. For comparison, we also prepared one Fe-doped and specific heat measurements were also carried out on this sample. It is observed that the jump in specific heat decreases with increase in Mn content.

  3. Specific Heat and Electrical Transport Properties of Sn0.8Ag0.2Te Superconductor

    Science.gov (United States)

    Mizuguchi, Yoshikazu; Yamada, Akira; Higashinaka, Ryuji; Matsuda, Tatsuma D.; Aoki, Yuji; Miura, Osuke; Nagao, Masanori

    2016-10-01

    Sn0.8Ag0.2Te is a new superconductor with Tc ˜ 2.4 K. The superconducting properties of Sn0.8Ag0.2Te have been investigated by specific heat measurements under magnetic fields. The bulk nature of superconductivity was confirmed from the amplitude of the specific heat jump at the superconducting transition, and the amplitude is consistent with fully gapped superconductivity. The upper critical field was estimated from specific heat and electrical resistivity measurements under magnetic fields. The Hall coefficient was positive, suggesting that Ag acts as a p-type dopant in Sn0.8Ag0.2Te.

  4. Comparison of Young's modulus and specific heat anomalies at the magnetic transition in α'-NaV 2O 5

    Science.gov (United States)

    Postolache, Emanuel; Powell, D. K.; Popov, G.; Rai, Ram C.; Greenblatt, M.; Brill, J. W.

    2000-12-01

    We have measured Young's modulus (using a vibrating reed technique) and the specific heat (using ac calorimetry) on the same crystals of α'-NaV 2O 5 at its Tc=34 K magnetic phase transition. Both properties exhibit large, unsymmetrical, and sample-dependent anomalies. While the specific heat results suggest tricritical behavior of the transition, large fluctuation effects are observed in the modulus above Tc. Fits of the modulus in terms of the specific heat, entropy, and free energy suggest that fluctuations are strongly stress- and sample-dependent.

  5. Round robin test on the measurement of the specific heat of solar salt

    Science.gov (United States)

    Muñoz-Sánchez, Belén; Nieto-Maestre, Javier; González-Aguilar, José; Julia, José Enrique; Navarrete, Nuria; Faik, Abdessamad; Bauer, Thomas; Bonk, Alexander; Navarro, María Elena; Ding, Yulong; Uranga, Nerea; Veca, Elisabetta; Sau, Salvatore; Giménez, Pau; García, Pierre; Burgaleta, Juan Ignacio

    2017-06-01

    Solar salt (SS), a well-known non-eutectic mixture of sodium nitrate (60% w/w) and potassium nitrate (40% w/w), is commonly used either as Thermal Energy Storage (TES) material (double tank technology) or Heat Transfer Fluid (HTF) (solar tower) in modern CSP plants worldwide. The specific heat (cp, kJ kg-1 °C-1) of SS is a very important property in order to support the design of new CSP Plants or develop novel materials based on SS. A high scientific effort has been dedicated to perform a suitable thermophysical characterization of this material. However, there is still a great discrepancy among the cp values reported by different authors1. These differences may be due to either experimental errors (random or systematic) or divergences in the starting material (grade of purity, presence of impurities and/or water). In order to avoid the second source of uncertainty (the starting material), a Round Robin Test (RRT) was proposed starting from a common material. In this way, the different methods from each laboratory could be compared. The study should lay the foundations for the establishment of a systematic procedure for the measurement of the specific heat of this kind of materials. Nine institutions, research centers and companies, accepted the proposal and are contributing with their results. The initiative was organized within the Workshop SolarPACES Task III - Material activity.

  6. Low-temperature specific heat in hydrogenated and Mn-doped La (Fe,Si ) 13

    Science.gov (United States)

    Lovell, Edmund; Ghivelder, Luis; Nicotina, Amanda; Turcaud, Jeremy; Bratko, Milan; Caplin, A. David; Basso, Vittorio; Barcza, Alexander; Katter, Matthias; Cohen, Lesley F.

    2016-10-01

    It is now well established that the paramagnetic-to-ferromagnetic transition in the magnetocaloric La (FeSi) 13 is a cooperative effect involving spin, charge, and lattice degrees of freedom. However, the influence of this correlated behavior on the ferromagnetic state is as yet little studied. Here we measure the specific heat at low temperatures in a systematic set of LaF exM nyS iz samples, with and without hydrogen, to extract the Sommerfeld coefficient, the Debye temperature, and the spin-wave stiffness. Substantial and systematic changes in magnitude of the Sommerfeld coefficient are observed with Mn substitution and introduction of hydrogen, showing that over and above the changes to the density of states at the Fermi energy there are significant enhanced d -band electronic interactions at play. The Sommerfeld coefficient is found to be 90 -210 mJ mo l-1K-2 , unusually high compared to that expected from band-structure calculations. The Debye temperature determined from the specific heat measurement is insensitive to Mn and Si doping but increases when hydrogen is introduced into the system. The Sommerfeld coefficient is reduced in magnetic field for all compositions that have a measurable spin-wave contribution. These results move our understanding of the cooperative effects forward in this important and interesting class of materials significantly and provide a basis for future theoretical development.

  7. Specific heat treatment of selective laser melted Ti-6Al-4V for biomedical applications

    Science.gov (United States)

    Huang, Qianli; Liu, Xujie; Yang, Xing; Zhang, Ranran; Shen, Zhijian; Feng, Qingling

    2015-12-01

    The ductility of as-fabricated Ti-6Al-4V falls far short of the requirements for biomedical titanium alloy implants and the heat treatment remains the only applicable option for improvement of their mechanical properties. In the present study, the decomposition of as-fabricated martensite was investigated to provide a general understanding on the kinetics of its phase transformation. The decomposition of asfabricated martensite was found to be slower than that of water-quenched martensite. It indicates that specific heat treatment strategy is needed to be explored for as-fabricated Ti-6Al-4V. Three strategies of heat treatment were proposed based on different phase transformation mechanisms and classified as subtransus treatment, supersolvus treatment and mixed treatment. These specific heat treatments were conducted on selective laser melted samples to investigate the evolutions of microstructure and mechanical properties. The subtransus treatment leaded to a basket-weave structure without changing the morphology of columnar prior β grains. The supersolvus treatment resulted in a lamellar structure and equiaxed β grains. The mixed treatment yielded a microstructure that combines both features of the subtransus treatment and supersolvus treatment. The subtransus treatment is found to be the best choice among these three strategies for as-fabricated Ti-6Al-4V to be used as biomedical implants.

  8. Unusual specific heat of almost dry L-cysteine and L-cystine amino acids.

    Science.gov (United States)

    Ishikawa, M S; Lima, T A; Ferreira, F F; Martinho, H S

    2015-03-01

    A detailed quantitative analysis of the specific heat in the 0.5- to 200-K temperature range for almost dry L-cysteine and its dimer, L-cystine, amino acids is presented. We report the occurrence of a sharp first-order transition at ∼76 K for L-cysteine associated with the thiol group ordering which was successfully modeled with the two-dimensional Ising model. We demonstrated that quantum rotors, two-level systems (TLS), Einstein oscillators, and acoustic phonons (the Debye model) are essential ingredients to correctly describe the overall experimental data. Our analysis pointed out the absence of the TLS contribution to the low temperature specific heat of L-cysteine. This result was similar to that found in other noncrystalline amorphous materials, e.g., amorphous silicon, low density amorphous water, and ultrastable glasses. L-cystine presented an unusual nonlinear acoustic dispersion relation ω(q)=vq0.95 and a Maxwell-Boltzmann-type distribution of tunneling barriers. The presence of Einstein oscillators with ΘE∼70 K was common in both systems and adequately modeled the boson peak contributions.

  9. Simultaneous determination of thermal conductivity, thermal diffusivity and specific heat in sI methane hydrate

    Science.gov (United States)

    Waite, W.F.; Stern, L.A.; Kirby, S.H.; Winters, W.J.; Mason, D.H.

    2007-01-01

    Thermal conductivity, thermal diffusivity and specific heat of sI methane hydrate were measured as functions of temperature and pressure using a needle probe technique. The temperature dependence was measured between −20°C and 17°C at 31.5 MPa. The pressure dependence was measured between 31.5 and 102 MPa at 14.4°C. Only weak temperature and pressure dependencies were observed. Methane hydrate thermal conductivity differs from that of water by less than 10 per cent, too little to provide a sensitive measure of hydrate content in water-saturated systems. Thermal diffusivity of methane hydrate is more than twice that of water, however, and its specific heat is about half that of water. Thus, when drilling into or through hydrate-rich sediment, heat from the borehole can raise the formation temperature more than 20 per cent faster than if the formation's pore space contains only water. Thermal properties of methane hydrate should be considered in safety and economic assessments of hydrate-bearing sediment.

  10. The specific heat of Cu-Al-Ni shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Larrea, I. [Dpto. Fisica Aplicada II, Facultad de Ciencia y Tecnologia, UPV/EHU, Apto. 644, 48080 Bilbao (Spain); Lopez-Echarri, A. [Instituto de Sintesis y Estudio de Materiales, Facultad de Ciencia y Tecnologia, UPV/EHU, Apto. 644, 48080 Bilbao (Spain)]. E-mail: a.lopezecharri@ehu.es; Bocanegra, E.H. [Dpto. Fisica Aplicada II, Facultad de Ciencia y Tecnologia, UPV/EHU, Apto. 644, 48080 Bilbao (Spain); No, M.L. [Dpto. Fisica Aplicada II, Facultad de Ciencia y Tecnologia, UPV/EHU, Apto. 644, 48080 Bilbao (Spain); San Juan, J.M. [Dpto. Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, UPV/EHU, Apto. 644, 48080 Bilbao (Spain)

    2006-11-25

    The specific heat of Cu{sub 81.8}Al{sub 13.7}Ni{sub 4.5} (AK10) shape memory alloy has been studied by means of conventional DSC and adiabatic calorimetry techniques. The transformation temperatures and the shape of the calorimetric curves obtained by adiabatic calorimetry do not show any noticeable dependence on the temperature measurement rates, contrarily to what is observed by other calorimetric techniques. The dynamical character of the various experimental methods together with the influence of the latent heat associated to the first order character of these phase transitions are discussed. The specific heat of AK10 has been measured from 50 to 350 K which covers the phase transformation temperature range. The forward and reverse martensitic transformation peaks were found at 299.5 and 304.6 K, showing a thermal hysteresis of 5.1 deg. C. The C {sub p} accuracy can be estimated in 0.1% of C {sub p} and permits a reliable assignment of the following values to the phase transition thermodynamic functions: {delta}H = 7.4 {+-} 0.2 J/g and {delta}S = 0.025 {+-} 0.001 J/gK.

  11. Thermal Behavior, Specific Heat Capacity and Adiabatic Time-to-explosion of GDN

    Institute of Scientific and Technical Information of China (English)

    YANG Xing-kun; XU Kang-zhen; ZHAO Feng-qi; YANG Xin; WANG Han; SONG Ji-rong; WANG Yao-yu

    2009-01-01

    A new compound, [(NH2)2C=NH2]+N(NO2)2-(GDN), was prepared by mixing ammonium dinitramide (ADN) and guanidine hydrochloride in water. The thermal behavior of GDN was studied under the non-isothermal conditions with DSC and TG/DTG methods. The apparent activation energy(E) and pre-exponential constant(A) of the exothermic decomposition stage of GDN were 118.75 kJ/mol and 1010.86 s-1, respectively. The critical temperature of the thermal explosion(Tb) of GDN was 164.09 ℃. The specific heat capacity of GDN was determined with the Micro-DSC method and the theoretical calculation method, and the standard molar specific heat capacity was 234.76J·mol-1·K-1 at 298.15K.The adiabatic time-to-explosion of GDN was also calculated to be a certain value between 404.80 and 454.95 s.

  12. Unusual specific heat of almost dry L-cysteine and L-cystine amino acids

    Science.gov (United States)

    Ishikawa, M. S.; Lima, T. A.; Ferreira, F. F.; Martinho, H. S.

    2015-03-01

    A detailed quantitative analysis of the specific heat in the 0.5- to 200-K temperature range for almost dry L-cysteine and its dimer, L-cystine, amino acids is presented. We report the occurrence of a sharp first-order transition at ˜76 K for L-cysteine associated with the thiol group ordering which was successfully modeled with the two-dimensional Ising model. We demonstrated that quantum rotors, two-level systems (TLS), Einstein oscillators, and acoustic phonons (the Debye model) are essential ingredients to correctly describe the overall experimental data. Our analysis pointed out the absence of the TLS contribution to the low temperature specific heat of L-cysteine. This result was similar to that found in other noncrystalline amorphous materials, e.g., amorphous silicon, low density amorphous water, and ultrastable glasses. L-cystine presented an unusual nonlinear acoustic dispersion relation ω (q ) =v q0.95 and a Maxwell-Boltzmann-type distribution of tunneling barriers. The presence of Einstein oscillators with ΘE˜70 K was common in both systems and adequately modeled the boson peak contributions.

  13. Unconventional superconductors under a rotating magnetic field. I. Density of states and specific heat

    Science.gov (United States)

    Vorontsov, A. B.; Vekhter, I.

    2007-06-01

    We develop a fully microscopic theory for the calculations of the angle-dependent properties of unconventional superconductors under a rotated magnetic field. We employ the quasiclassical Eilenberger equations and use a variation of the Brandt-Pesch-Tewordt (BPT) method to obtain a closed-form solution for the Green’s function. The equations are solved self-consistently for quasi-two-dimensional dx2-y2(dxy) superconductors with the field rotated in the basal plane. The solution is used to determine the density of states and the specific heat. We find that applying the field along the gap nodes may result in minima or maxima in the angle-dependent specific heat, depending on the location in the T-H plane. This variation is attributed to the scattering of the quasiparticles on vortices, which depends on both the field and the quasiparticle energy, and is beyond the reach of the semiclassical approximation. We investigate the anisotropy across the T-H phase diagram and compare our results with the experiments on heavy fermion CeCoIn5 .

  14. Iridium double perovskite Sr2YIrO6 : A combined structural and specific heat study

    Science.gov (United States)

    Corredor, L. T.; Aslan-Cansever, G.; Sturza, M.; Manna, Kaustuv; Maljuk, A.; Gass, S.; Dey, T.; Wolter, A. U. B.; Kataeva, Olga; Zimmermann, A.; Geyer, M.; Blum, C. G. F.; Wurmehl, S.; Büchner, B.

    2017-02-01

    Recently, the iridate double perovskite Sr2YIrO6 has attracted considerable attention due to the report of unexpected magnetism in this Ir5 + (5 d4 ) material, in which according to the Jeff model, a nonmagnetic ground state is expected. However, in recent works on polycrystalline samples of the series Ba2 -xSrxYIrO6 no indication of magnetic transitions have been found. We present a structural, magnetic, and thermodynamic characterization of Sr2YIrO6 single crystals, with emphasis on the temperature and magnetic field dependence of the specific heat. As determined by x-ray diffraction, the Sr2YIrO6 single crystals have a cubic structure, with space group F m 3 ¯m . In agreement with the expected nonmagnetic ground state of Ir5 + (5d 4 ) in Sr2YIrO6 , no magnetic transition is observed down to 430 mK. Moreover, our results suggest that the low-temperature anomaly observed in the specific heat is not related to the onset of long-range magnetic order. Instead, it is identified as a Schottky anomaly caused by paramagnetic impurities present in the sample, of the order of n ˜0.5 (2 )% . These impurities lead to non-negligible spin correlations, which nonetheless, are not associated with long-range magnetic ordering.

  15. Lattice specific heat and local density of states of Ni-based dilute alloys at low temperature

    Indian Academy of Sciences (India)

    P D Semlaty; Kapil Dev; P N Ram

    2006-06-01

    A detailed theoretical study of the low-temperature lattice specific heat of Ni-based dilute alloys has been carried out. Lattice Green's function method has been used to calculate the local density of states of substitutional impurities and lattice specific heat in different alloys. The resonance condition has been investigated for possible occurrence of resonance modes. Except in NiCr and NiMn, low-frequency resonance modes have been obtained in all the alloys. However, no localized mode was obtained. The impurity-induced increase in lattice specific heat is explained on the basis of the obtained resonance modes. The calculation shows an excellent agreement with the measured lattice specific heat in these alloys

  16. Log-periodic oscillations in the specific heat behaviour for self-similar Ising type spin systems

    Science.gov (United States)

    Khamzin, A. A.; Nigmatullin, R. R.; Popov, I. I.; Zhelifonov, M. P.

    2012-11-01

    The self-similar model of spin-system of the Ising type is formulated. The thermodynamic properties of this model are considered. Analytically and numerically the specific heat of this system is calculated in the nearest neighbor approximation (only the influence of two neighboring spins was taken into account). It is shown that in temperature dependence of the specific heat the log-periodic oscillations are appeared. These oscillations are imposed on the expected power-law dependence.

  17. First and Second-Law Efficiency Analysis and ANN Prediction of a Diesel Cycle with Internal Irreversibility, Variable Specific Heats, Heat Loss, and Friction Considerations

    Directory of Open Access Journals (Sweden)

    M. M. Rashidi

    2014-04-01

    Full Text Available The variability of specific heats, internal irreversibility, heat and frictional losses are neglected in air-standard analysis for different internal combustion engine cycles. In this paper, the performance of an air-standard Diesel cycle with considerations of internal irreversibility described by using the compression and expansion efficiencies, variable specific heats, and losses due to heat transfer and friction is investigated by using finite-time thermodynamics. Artificial neural network (ANN is proposed for predicting the thermal efficiency and power output values versus the minimum and the maximum temperatures of the cycle and also the compression ratio. Results show that the first-law efficiency and the output power reach their maximum at a critical compression ratio for specific fixed parameters. The first-law efficiency increases as the heat leakage decreases; however the heat leakage has no direct effect on the output power. The results also show that irreversibilities have depressing effects on the performance of the cycle. Finally, a comparison between the results of the thermodynamic analysis and the ANN prediction shows a maximum difference of 0.181% and 0.194% in estimating the thermal efficiency and the output power. The obtained results in this paper can be useful for evaluating and improving the performance of practical Diesel engines.

  18. Experimental thermal conductivity, thermal diffusivity, and specific heat values for mixtures of nitrogen, oxygen, and argon

    Science.gov (United States)

    Perkins, R. A.; Cieszkiewicz, M. T.

    1991-01-01

    Experimental measurements of thermal conductivity and thermal diffusivity obtained with a transient hot-wire apparatus are reported for three mixtures of nitrogen, oxygen, and argon. Values of the specific heat, Cp, are calculated from these measured values and the density calculated with an equation of state. The measurements were made at temperatures between 65 and 303 K with pressures between 0.1 and 70 MPa. The data cover the vapor, liquid, and supercritical gas phases for the three mixtures. The total reported points are 1066 for the air mixture (78.11 percent nitrogen, 20.97 percent oxygen, and 0.92 percent argon), 1058 for the 50 percent nitrogen, 50 percent oxygen mixture, and 864 for the 25 percent nitrogen, 75 oxygen mixture. Empirical thermal conductivity correlations are provided for the three mixtures.

  19. PBX-9502 Shock Sensitivity Correlation with Specific Heat and Reactive Temperature Magnitudes

    Science.gov (United States)

    Billingsley, James

    2005-07-01

    This work is a supplementary follow-on to papers [1 and 2], presented in two previous SCCM conferences, that related plane impact shock sensitivity of CHNO energetic materials to specific heat (Cp per average atom) magnitude and reactive temperature (TR) conditions. More specifically, plane impact shock energy input that is equal to the thermal vibratory energy increment (the area under the Cp versus temperature data curve between an experimental temperature, TEXP, and a reactive temperature) is sufficient to cause shock induced reactions, up to and including detonation, in CHNO energetic materials. This statement is demonstratively verified at four different test temperatures for PBX-9502 in this proposed paper. *Billingsley, J. P., paper in Shock Compression of Condensed Matter -- 1995, AIP Conference Proceedings 370, Part I, pages 429 -- 432. *Billingsley, J. P., paper in Shock Compression of Condensed Matter -- 1999, AIP Conference Proceedings, 505, Part II, pages 899 -- 902.

  20. Measurements of Specific Heat and Density of Al2O3 Nanofluid

    Science.gov (United States)

    Vajjha, Ravikanth S.; Das, Debendra K.

    2008-10-01

    This paper presents measurements of specific heat and density of aluminum oxide (Al2O3) nanoparticles suspended in 60:40 (by mass) ethylene glycol and water mixture (EG/W). These property values are necessary to determine the fluid dynamic and heat transfer characteristics of nanofluids. These properties have been measured over a range of temperatures for nanoparticle volumetric concentrations of 0 to 10%. From the experimental results, empirical correlations have been developed as a function of temperature and particle volume concentration. These correlations will be valuable in studying the heat transfer performance and the pumping power requirement of Al2O3 nanofluid in various applications such as industrial heat exchangers, building heating and automotive cooling.

  1. Specific-heat measurement of single metallic, carbon, and ceramic fibers at very high temperature

    Science.gov (United States)

    Pradère, C.; Goyhénèche, J. M.; Batsale, J. C.; Dilhaire, S.; Pailler, R.

    2005-06-01

    The main objective of this work is to present a method for measuring the specific heat of single metallic, carbon, and ceramic fibers at very high temperature. The difficulty of the measurement is due to the microscale of the fiber (≈10μm) and the important range of temperature (700-2700K). An experimental device, a modelization of the thermal behavior, and an analytic model have been developed. A discussion on the measurement accuracy yields a global uncertainty lower than 10%. The characterization of a tungsten filament with thermal properties identical to those of the bulk allows the validation of the device and the thermal estimation method. Finally, measurements on carbon and ceramic fibers have been done at very high temperature.

  2. Modelling of Dynamic Transmission Cable Temperature Considering Soil-Specific Heat, Thermal Resistivity, and Precipitation

    DEFF Research Database (Denmark)

    Olsen, Rasmus; Anders, George J.; Holboell, Joachim

    2013-01-01

    This paper presents an algorithm for the estimation of the time-dependent temperature evolution of power cables, when real-time temperature measurements of the cable surface or a point within its vicinity are available. The thermal resistivity and specific heat of the cable surroundings are varied...... as functions of the moisture content which is known to vary with time. Furthermore, issues related to the cooling effect during rainy weather are considered. The algorithm is based on the lumped parameters model and takes as input distributed temperature sensing measurements as well as the current and ambient...... temperature. The concept is verified by studying a laboratory setup of a 245 kV cable system....

  3. Vibrational properties and specific heat of core-shell Ag-Au icosahedral nanoparticles.

    Science.gov (United States)

    Sauceda, Huziel E; Garzón, Ignacio L

    2015-11-14

    The vibrational density of states (VDOS) of metal nanoparticles can be a fingerprint of their geometrical structure and determine their low-temperature thermal properties. Theoretical and experimental methods are available nowadays to calculate and measure it over a size range of 1-4 nm. In this work, we present theoretical results regarding the VDOS of Ag-Au icosahedral nanoparticles with a core-shell structure in that size range (147-923 atoms). The results are obtained by changing the size and type of atoms in the core-shell structure. For all sizes investigated, a smooth and monotonic variation of the VDOSs from Ag to Au is obtained by increasing the number of core Au atoms, and vice versa. Nevertheless, the Ag561Au362 nanoparticle, with a Ag core, shows an anomalous enhancement at low frequencies. An analysis of the calculated VDOSs indicates that as a general trend the low-frequency region is mainly due to the shell contribution, whereas at high frequencies the core effect would be dominant. A linear variation with size is obtained for the period of quasi-breathing mode (QBM), in agreement with the behaviour obtained for pure Ag and Au nanoparticles. A non-monotonic variation is obtained for the QBM frequency as a function of the Ag concentration for all nanoparticles investigated. The calculated specific heat at low temperatures of the Ag-Au nanoparticles is smaller (larger) than the corresponding one calculated for the pure Au (Ag) nanoparticles of same size. Nevertheless, the enhancement of VDOS at low frequencies of the Ag561Au362 nanoparticle with a Ag core induced larger values of specific heat than those of the pure Au923 nanoparticle in the temperature range of 5-15 K.

  4. Flexible Flatfoot

    Science.gov (United States)

    ... this page. Please enable Javascript in your browser. Flexible Flatfoot What Is Flatfoot? Flatfoot is often a ... may develop as a result of a flatfoot. Flexible Flatfoot Flexible flatfoot is one of the most ...

  5. Low temperature specific heat of the Kondo-semimetal CeNiSn in zero and applied magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Brueckl, A.; Neumaier, K.; Einzel, D.; Andres, K. [Walther-Meissner-Inst., Garching (Germany); Flaschin, S.; Kalvius, G.M. [Technical Univ. Munich, Garching (Germany). Physics Dept.; Nakamoto, G. [Japan Advanced Inst. of Science and Technology, Ishikawa (Japan); Takabatake, T. [Hiroshima Univ., Higashi-Hiroshima (Japan). Dept. of Quantum Matter

    1999-06-01

    The specific heat of several CeNiSn single crystals of various purity has been measured in the temperature range from 25 mK to 5 K and in magnetic fields from zero to 7 Tesla. At very low temperatures (below {approximately} 200 mK) the specific heat is found to vary linearly with temperature (C = {gamma}T), the coefficient {gamma} decreasing with increasing purity. Above 200 mK, the specific heat is well described as the sum of a linear and a quadratic term. An applied magnetic field affects mostly the linear term, which first slightly decreases, then strongly increases with field. In magnetic fields, a nuclear hyperfine specific heat contribution is superimposed, which is due mostly to the bare Zeeman-splitting of the {sup 115}Sn, {sup 117}Sn, {sup 119}Sn nuclei (all with spin I = 1/2 and with abundances of 0.35, 7.61, and 8.58% respectively) in the externally applied field. The results on the specific heat at very low temperatures in applied fields fit into the model of an enhanced (heavy-fermion type) density of states which is modified by coherent antiferromagnetic fluctuations into a V-shaped density of states at the Fermi energy.

  6. Investigation of Specific Heat and Thermal Conductivity of Rasa Grape (Vitis Vinifera L. as a Function of Moisture Content

    Directory of Open Access Journals (Sweden)

    J Khodaei

    2013-09-01

    Full Text Available Kurdistan Rasa grape is one of the delicious and sweet fruits with black color. It contains vitamins E, C and some protectors such as antioxidants. In order to design equipments and facilities for drying, preservation and processing of Rasa grape, it is necessary and important to know about its specific heat and thermal conductivity. In this paper the specific heat and thermal conductivity of Rasa grape were studied. The method of mixtures and hot wire as a heating source was used for measuring the specific heat and thermal conductivity, respectively. The experimental variables were temperature at four levels of 40, 50, 60 and 70 °C and moisture content at four levels of 22.36, 37.56, 52.13 and 71.53%. The results showed that the specific heat and thermal conductivity of Rasa grape increased linearly from 1.6523 kJ kg-1°C-1 to 3.3253 kJ kg-1°C-1 and 0.1252 W m-1°C-1 to 0.4202 W m-1°C-1 respectively, with increasing moisture content and temperature. The results also showed that the effect of moisture content on increasing the specific heat and thermal conductivity was more significant than that from temperature rise.

  7. Monte Carlo study of internal energy and specific heat of a nano-graphene bilayer in a longitudinal magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xiao-hong; Wang, Wei, E-mail: ww9803@126.com; Chen, Dong-dong; Xu, Si-yuan

    2016-06-15

    The thermodynamic properties of a nano-graphene bilayer, consisting of the upper layer A of spin-3/2 with antiferromagnetic intralayer exchange coupling and the bottom layer B of spin-5/2 with ferromagnetic intralayer exchange coupling, have been studied by the use of Monte Carlo simulation. We find a number of characteristic phenomena. The effects of the exchange coupling, the single-ion anisotropy and the longitudinal magnetic field on the internal energy, the specific heat and the blocking temperature of the mixed-spin bilayer system have been investigated in detail. The internal energy and the specific heat profiles are clarified. In particular, we have found that the specific heat curve may show two peaks phenomenon for appropriate values of the system parameters.

  8. Low temperature specific heat in BaFe1.9Ni0.1As2 single crystals

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Low-temperature specific heat was measured on the BaFe1.9Ni0.1As2 single crystals with critical transition temperature Tc = 20.1 K.A clear specific heat jump with the value ΔC/T|Tc ≈ 23 mJ/mol K2 was observed.In addition,a roughly linear magnetic field dependence of the electronic specific heat coefficient Δγ(H) was found in the zero-temperature limit,suggesting that at least one Fermi pocket,probably the hole derivative one,was fully gapped with a small anisotropy in the present sample.A slight curvature of the curve Δγ(H) may suggest a complex gap structure(anisotropic gap or nodes) at other Fermi surfaces.

  9. Dissociation and specific heats of gas hydrates under submarine and sublacustrine environments

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, R.; Hachikubo, A.; Shoji, H. [Kitami Inst. of Technology, Kitami (Japan)

    2008-07-01

    Studies have shown that natural gas hydrates located near a mud volcano in Lake Baikal contain high concentrations of ethane. Gas hydrates absorb and release large amounts of latent heat during their formation and dissociation processes. In this study, the specific heat of synthetic methane and ethane hydrates were measured under high pressure using a heat-flow calorimeter. The aim of the study was to develop an improved understanding of the thermal environment of gas hydrate-bearing sediments in submarine and sublacustrine environments. Ice was placed in 2 sampling cells and pressurized with methane and ethane at 5 MPa and 2 MPa. After the gas hydrates formed, the samples were then heated from 263 K to 288 K. An analysis of data obtained from the experiment showed that large negative heat flow peaks corresponding with methane gas hydrate dissociation occurred in temperature ranges of 279 to 282 K at a pressure of 5 MPa, and at temperatures of 283-286 K at 2 MPa for the ethane gas hydrate. Future experiments with the calorimeter will be conducted at higher pressure ranges. 15 refs., 3 figs.

  10. Membrane-based nanocalorimeter for high-resolution measurements of low-temperature specific heat

    CERN Document Server

    Tagliati, S; Rydh, A

    2012-01-01

    A differential, membrane-based nanocalorimeter for general specific heat studies of very small samples, ranging from 0.5 mg to sub-{\\mu}g in mass, is described. The calorimeter operates over the temperature range from above room temperature down to 0.5 K. It consists of a pair of cells, each of which is a stack of heaters and thermometer in the center of a silicon nitride membrane, in total giving a background heat capacity less than 100 nJ/K at 300 K, decreasing to 10 pJ/K at 1K. The device has several distinctive features: i) The resistive thermometer, made of a Ge_{1-x}Au_{x} alloy, displays a high dimensionless sensitivity |dlnR/dlnT | \\geq 1 over the entire temperature range. ii) The sample is placed in direct contact with the thermometer, which is allowed to self-heat. The thermometer can thus be operated at high dc current to increase the resolution. iii) Data are acquired with a set of eight synchronized lock-in amplifiers measuring dc, 1st and 2nd harmonic signals of heaters and thermometer. This giv...

  11. Magnetic and specific heat studies of the frustrated Er2Mn2O7 compound

    Institute of Scientific and Technical Information of China (English)

    N.Ben Amor; M.Bejar; E.Dhahri; M.A.Valente; P.Lachkar; E.K.Hlil

    2013-01-01

    A new Er2Mn2O7 compound was synthesized by the ceramic method and its crystal structure was characterized using powder X-ray diffraction (XRD) and observed by scanning electron microscopy (SEM).The magnetic properties were investigated using a BS2 magnetometer and the heat capacity was studied using a quantum design (PPMS).The structural study revealed that this compound was monophasic and crystallized in the monclinic system with the P2/M space group.Magnetization measurements were carried out in the temperature range of 1.8-200 K under an applied magnetic field of 0.05 T.A crossover from a room temperature paramagnetic phase to an antiferromagnetic one at low temperature was detected from the magnetic study.The magnetic susceptibility,in the paramagnetic region above 40 K,was found to present a simple Curie-Weiss type behavior.From the specific heat (CP) measurements in magnetic fields up to 5 T,we noted the presence of a wide peak characteristic of a second order magneto-structural transition.

  12. The Specific Heat of UGe_2: Effects of Pressure and Magnetic Field

    Science.gov (United States)

    Fisher, R. A.; Bouquet, F.; Lashley, J. C.; Phillips, N. E.; Huxley, A.; Flouquet, J.

    2003-03-01

    At ambient pressure (P) UGe2 undergoes transitions from paramagnetic, to ferromagnetic (FM), to coupled charge-density wave (CDW) spin-density wave (SDW) phases on cooling. Within a narrow range of P, and at temperatures (T) below ˜0.7 K (but depending on sample quality), superconductivity (SC) coexists with both the CDW-SDW and FM phases. The γT term for the specific heat (C) increases with increasing P, most rapidly between ˜1 and ˜1.4 GPa, the region in which SC develops, then approaches a constant value at 1.8 GPa. The γT term decreases in a magnetic field. In the CDW-SDW region of the phase diagram C includes an exponential term that represents the CDW-SDW and decreases in a magnetic field. The electronic entropy increases rapidly in a narrow interval of P in the vicinity of the CDW-SDW transition, which suggests that it might be broadened first order. A transition to SC is not observed to 0.35 K in the range of P where it is expected to occur, but there are upturns in C/T, absent at other P's, that suggest the onset of SC.

  13. Flexible supercapacitors

    Institute of Scientific and Technical Information of China (English)

    Shan Shi; Chengjun Xu; Cheng Yang; Jia Li; Hongda Du; Baohua Li; Feiyu Kang

    2013-01-01

    Flexible supercapacitors show a great potential for applications in wearable,miniaturized,portable,largescale transparent and flexible consumer electronics due to their significant,inherent advantages,such as being flexible,lightweight,low cost and environmentally friendly in comparison with the current energy storage devices.In this report,recent progress on flexible supercapacitors,flexible electrodes and electrolytes is reviewed.In addition,the future challenges and opportunities are discussed.

  14. Power law specific heat divergence in Sr{sub 3}Ru{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Rost, A.W.; Berridge, A.M.; Mercure, J.F.; Mackenzie, A.P. [Scottish Universities Physics Alliance (SUPA), School of Physics and Astronomy, University of St. Andrews (United Kingdom); Perry, R.S. [SUPA, School of Physics, University of Edinburgh (United Kingdom); Grigera, S.A. [Scottish Universities Physics Alliance (SUPA), School of Physics and Astronomy, University of St. Andrews (United Kingdom); Instituto de Fisica de Liquidos y Sistemas Biologicos, UNLP-CONICET, La Plata (Argentina)

    2010-03-15

    We present measurement and analysis of field-dependent specific heat measurements on Sr{sub 3}Ru{sub 2}O{sub 7}, showing that, at low temperatures, an incipient divergence is cut off by the formation of a new phase previously identified to show the transport properties of an electronic nematic. We discuss how to interpret a specific heat divergence in a system with van Hove singularities, and caution against a simple-minded comparison of experimentally determined power laws with the predictions of quantum critical theories. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  15. Heat flux measurements of Tb3M series (M=Co, Rh and Ru): Specific heat and magnetocaloric properties

    Science.gov (United States)

    Monteiro, J. C. B.; Lombardi, G. A.; dos Reis, R. D.; Freitas, H. E.; Cardoso, L. P.; Mansanares, A. M.; Gandra, F. G.

    2016-12-01

    We report on the magnetic properties and magnetocaloric effect (MCE) for the Tb3M series, with M=Co, Rh and Ru, obtained using a heat flux technique. The specific heat of Tb3Co and Tb3Rh are very similar, with a first order type transition occurring around 6 K below the magnetic ordering temperature without any corresponding feature on the magnetization. The slightly enhanced electronic specific heat, the Debye temperature around 150 K and the presence of the magnetic specific heat well above the ordering temperature are also characteristic of many other compounds of the R3M family (R=Rare Earth). The specific heat for Tb3Ru, however, presents two peaks at 37 K and 74 K. The magnetization shows that below the first peak the system presents an antiferromagnetic behavior and is paramagnetic above 74 K. We obtained a magnetocaloric effect for M=Co and Rh, -∆S=12 J/kg K, but for Tb3Ru it is less than 3 J/kg K (μ0∆H=5 T). We believe that the experimental results show that the MCE is directly related with the process of hybridization of the (R)5d-(M)d electrons that occurs in the R3M materials.

  16. Measurement of the Specific Heat of Plastic Waste/Fly Ash Composite Material Using Differential Scanning Calorimetry

    Science.gov (United States)

    Fujino, J.; Honda, T.

    2009-06-01

    Plastic waste/fly ash composite, which is made mostly from plastic waste and fly ash, is one of the materials developed for the purpose of recycling. Currently, the composite is used for cable troughs shielding underground lines. However, there exists little information concerning the thermophysical properties of the composite. Thermophysical properties and the structure of the composite must be determined to estimate the heat transfer in the composite and create the different proportions of the composite material. This article deals with measurements of the specific heat of the plastic waste/fly ash composite and its components using a differential scanning calorimeter. The composite sample, which ranged from 10 mg to 19 mg in mass, was cut from a cable trough. The standard reference material is synthetic sapphire disks of 19.6 mg and 29.6 mg in mass. The specific heat of the plastic waste/fly ash composite increases from 1.25 kJ · kg-1 · K-1 to 1.59 kJ · kg-1 · K-1 at temperatures from 305 K to 360 K. The uncertainty for the specific heat data of the composite is estimated to be about 4 %. In addition, the specific heat value depends heavily on the content of the plastic waste.

  17. Magnon specific heat and free energy of Heisenberg ferromagnetic single-walled nanotubes: Green's function approach

    Energy Technology Data Exchange (ETDEWEB)

    Mi, Bin-Zhou, E-mail: mbzfjerry2008@126.com [Department of Basic Curriculum, North China Institute of Science and Technology, Beijing 101601 (China); Department of Physics, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083 (China); Zhai, Liang-Jun [The School of Mathematics and Physics, Jiangsu University of Technology, Changzhou 213001 (China); Hua, Ling-Ling [Department of Basic Curriculum, North China Institute of Science and Technology, Beijing 101601 (China)

    2016-01-15

    The effect of magnetic spin correlation on the thermodynamic properties of Heisenberg ferromagnetic single-walled nanotubes are comprehensively investigated by use of the double-time Green's function method. The influence of temperature, spin quantum number, diameter of the tube, anisotropy strength and external magnetic field to internal energy, free energy, and magnon specific heat are carefully calculated. Compared to the mean field approximation, the consideration of the magnetic correlation effect significantly improves the internal energy values at finite temperature, while it does not so near zero temperature, and this effect is related to the diameter of the tube, anisotropy strength, and spin quantum number. The magnetic correlation effect lowers the internal energy at finite temperature. As a natural consequence of the reduction of the internal energy, the specific heat is reduced, and the free energy is elevated. - Highlights: • Magnon specific heat and free energy of Heisenberg ferromagnetic single-walled nanotubes (HFM-SWNTs) are investigated. • The magnetic correlations effect has a considerable contribution to the thermodynamics properties of HFM-SWNTs. • Magnetic correlation effects are always to lower the internal energy at finite temperature. • At Curie point, magnetic correlation energy is much less than zero. • The peak values of magnon specific heat curves rise and shift right towards higher temperatures with the diameter of tubes, the anisotropy strength, and the spin quantum number rising.

  18. Specific heat, resistivity, and AC susceptibility of the cubic PrX 2 compounds (X = Pt, Ru, Ir, Rh)

    Science.gov (United States)

    Greidanus, F. J. A. M.; Nieuwenhuys, G. J.; de Jongh, L. J.; Huiskamp, W. J.; Capel, H. W.; Buschow, K. H. J.

    1983-04-01

    Specific-heat, differential-susceptibility and electrical-resistivity measurements on PrX 2 (X = Ir, Pt, Rh, Ru) compounds reveal phase transitions at Tc = 11.2±0.5 K, 7.7±0.5 K, 7.9±0.5 Kand 33.9±0.5 K for X = Ir, Pt, Rh, and Ru, respective ly. From earlier neutron inelastic scattering experiments, the crystalline electric field levels of these compounds have been determined. The specific-heat results are compared with the results of a mean-field calculation, assuming bilinear exchange interactions. The presence of broad secondary maxima in the temperature dependence of the specific heat of PrRh 2, PrRu 2 and especially PrIr 2 can qualitatively be explained by the presence of biquadratic (quadrupolar) interactions. The behaviour of the susceptibility is in agreement with ferromagnetic ordering. The electrical resistivity drops markedly below Tc, and the dϱ/d T versus T curve is similar to that of the specific heat.

  19. Strategic flexibility

    OpenAIRE

    Kim, KiHyung

    2014-01-01

    A flexible system is defined as one that can change the entity's stance, capability or status reacting to a change of the entity's environment. Flexibility has gathered the attention of academic researchers and industry practitioners as an efficient approach to cope with today's volatile environment. As the environments become more unpredictable and volatile, it is imperative for a flexible system to respond quickly to a change in its circumstance. How much flexibility is embedded into the sy...

  20. Flexible Ablators

    Science.gov (United States)

    Stackpoole, Margaret M. (Inventor); Ghandehari, Ehson M. (Inventor); Thornton, Jeremy J. (Inventor); Covington, Melmoth Alan (Inventor)

    2017-01-01

    A low-density article comprising a flexible substrate and a pyrolizable material impregnated therein, methods of preparing, and devices using the article are disclosed. The pyrolizable material pyrolizes above 350 C and does not flow at temperatures below the pyrolysis temperature. The low-density article remains flexible after impregnation and continues to remain flexible when the pyrolizable material is fully pyrolized.

  1. Flexible Carbon Aerogels

    Directory of Open Access Journals (Sweden)

    Marina Schwan

    2016-09-01

    Full Text Available Carbon aerogels are highly porous materials with a large inner surface area. Due to their high electrical conductivity they are excellent electrode materials in supercapacitors. Their brittleness, however, imposes certain limitations in terms of applicability. In that context, novel carbon aerogels with varying degree of flexibility have been developed. These highly porous, light aerogels are characterized by a high surface area and possess pore structures in the micrometer range, allowing for a reversible deformation of the aerogel network. A high ratio of pore size to particle size was found to be crucial for high flexibility. For dynamic microstructural analysis, compression tests were performed in-situ within a scanning electron microscope allowing us to directly visualize the microstructural flexibility of an aerogel. The flexible carbon aerogels were found to withstand between 15% and 30% of uniaxial compression in a reversible fashion. These findings might stimulate further research and new application fields directed towards flexible supercapacitors and batteries.

  2. Stage- and sex-specific heat tolerance in the yellow dung fly Scathophaga stercoraria.

    Science.gov (United States)

    Blanckenhorn, Wolf U; Gautier, Roland; Nick, Marcel; Puniamoorthy, Nalini; Schäfer, Martin A

    2014-12-01

    Thermal tolerance varies at all hierarchical levels of biological organization: among species, populations, individuals, and even within individuals. Age- or developmental stage- and sex-specific thermal effects have received relatively little attention in the literature, despite being crucial for understanding thermal adaptation in nature and responses to global warming. We document stage- and sex- specific heat tolerance in the yellow dung fly Scathophaga stercoraria (Diptera: Scathophagidae), a species common throughout the northern hemisphere that generally favours cool climates. Exposure of eggs to temperatures up to 32°C did not affect larval hatching rate, but subsequent egg-to-adult survival at a benign temperature was reduced. Permanent transfer from benign (18°C) to hot temperatures (up to 31°C) at different larval and pupal stages strongly decreased egg-to-adult survival, though survival continuously improved the later the transfer occurred. Temporary transfer for only two days increased mortality more weakly, survival being lowest when temperature stress was imposed early during the larval or pupal stages. Adult flies provided with sugar and water tolerated 31°C longer than previously thought (5 days in males to 9 days in females). Eggs were thus less susceptible to thermal stress than larvae, pupae or adults, in agreement with the hypothesis that more mobile stages require less physiological protection against heat because they can behaviourally thermoregulate. The probability of mating, of laying a clutch, and hatching success were generally independently reduced by exposure of females or males to warm temperatures (24°C) during the juvenile or adult stages, with some interactions evident. High temperature stress thus affects survival differentially depending on when it occurs during the juvenile or the pre-reproductive adult life stage, and affects reproductive success via the mating behaviour of both sexes, female physiology in terms of

  3. Flexible Software for Flexible Scheduling

    Science.gov (United States)

    Economou, Frossie; Jenness, Tim; Tilanus, Remo P. J.; Hirst, Paul; Adamson, Andy J.; Rippa, Mathew; Delorey, Kynan K.; Isaak, Kate G.

    The JAC Observation Management Project (OMP) provides software for the James Clerk Maxwell (JCMT) and the United Kingdom Infrared (UKIRT) telescopes that manages the life-cycle of flexibly scheduled observations. Its aim is to increase observatory efficiency under flexible (queue) scheduled observing, without depriving the principal investigator (PI) of the flexibility associated with classical scheduling.

  4. A temperature relaxation method for the measurement of the specific heat of solids at room temperature in student laboratories

    Science.gov (United States)

    Marín, E.; Delgado-Vasallo, O.; Valiente, H.

    2003-10-01

    A laboratory experiment is described which employs a relaxation method for the measurement of the specific heat at constant pressure of solids at room temperature. The experiment employs measurements of the cooling (or heating) rate of a sample whose temperature differs from that of the surroundings due to light heating. This rate depends on the temperature difference, the specific heat of the sample and the heat transfer coefficient. The sample is suspended adiabatically in a reservoir in which a vacuum can be made. The influence of heat dissipation by convection on the results is discussed for the first time for this kind of experiment. The theoretical aspects related to the described technique involve concepts from several branches of physics that makes the experiment of interest and suitable for students at undergraduate and graduate levels of physics, material sciences and engineering.

  5. Effect of severe plastic deformation on the specific heat and magnetic properties of cold rolled Gd sheets

    Science.gov (United States)

    Taskaev, S.; Skokov, K.; Khovaylo, V.; Buchelnikov, V.; Pellenen, A.; Karpenkov, D.; Ulyanov, M.; Bataev, D.; Usenko, A.; Lyange, M.; Gutfleisch, O.

    2015-03-01

    We report on specific heat and magnetic properties of thin Gd sheets obtained by means of a cold rolling technique. At temperatures well below Curie temperature TC, the cold rolling has a minor impact on the specific heat Cp. However, a well defined λ-type anomaly of Cp seen in the vicinity of TC in a polycrystalline Gd sample is markedly suppressed in the severely deformed samples. Depression of the λ peak is due to a large decrease of magnetization that presumably originates in a local magnetic anisotropy induced by the severe plastic deformation. Results of calculation of magnetocaloric effect from the Cp and magnetization data indicate that the magnetocaloric effect gradually decreases as the degree of plastic deformation increases. This trend is further confirmed by the direct measurements of the adiabatic temperature change ΔTad.

  6. The calculation of high-temperature equilibrium and nonequilibrium specific heat data for N2, O2 and NO

    Science.gov (United States)

    Jaffe, Richard L.

    1987-01-01

    Specific heat data for high-temperature air species are needed to compute the temperature and enthalpy of gas mixtures in aerothermodynamics flowfield calculations. Accurate data are known only for temperatures under 6000 K, but are required for temperatures exceeding 25,000 K. In the present study, CP data are computed for N2, O2 and NO. The calculations are based on summations over all the vibration-rotation energy levels for all known bound electronic states. Estimates are made for the error introduced by the neglect of possible additional high-lying electronic states. In addition, a scheme for the partitioning of the internal energy into vibrational, rotational and electronic contributions is presented which consistently accounts for the nonseparable nature of the various energy modes. The multitemperature specific heat data are recommended for use in nonequilibrium flowfield models.

  7. Low-Temperature Specific Heat of the Underdoped La2-xSrxCuO4 Single Crystals

    Institute of Scientific and Technical Information of China (English)

    LIU Zhi-Yong; YANG Hai-Peng; LU Xi-Feng; ZHOU Fang; WEN Hai-Hu

    2004-01-01

    @@ We report the low-temperature specific heat of La2-xSrxCuO4 (x = 0.063) single crystals before and after annealing in the temperature region of 2-10 K and magnetic fields up to 12 T. The data confirm the √H dependence of the linear term coefficient γpredicted for d-wave paring in the Volovik theory at T = 0 K. However, the data do not satisfy the proposed Simon-Lee scaling law at finite temperatures, i.e. CDOs/ (T2) = f(T/ √H), where f is an unknown scaling function and CDos is the extra specific heat contributed by the nodal quasiparticles due to the Doppler effect. Possible reasons for this failure are presented.

  8. Calculation of the Specific Heats for the H-M and E-IV Phase Transitions in NH4I

    Institute of Scientific and Technical Information of China (English)

    H. Yurtseven; H. Kaya

    2003-01-01

    This study gives our calculation for the specific heats Cvi due to an Ising model using the observed Cp data for the JT-JZT and JL-TV phase transitions in NH^I. By fitting to the Cp data we determine the values of the critical exponent for the pressure of 0.14GPa (H-M phase transition) and for the pressures of 0.75, 1.35 and 1.97GPa (E-HV phase transition) in NH^I. Our exponent values are close to the predicted values of the specific heat in a three-dimensional Ising model. Our calculated Cyi are in good agreement with the experimental Cp for NH^I in most cases.

  9. Low Temperature Specific Heat in Lightly Mn-Substituted Electron-Doped SrTiO3

    Science.gov (United States)

    Okuda, Tetsuji; Hata, Hiroto; Eto, Takahiro; Sobaru, Shogo; Oda, Ryosuke; Noda, Masaaki; Kuwahara, Hideki

    2017-08-01

    We found large changes in the low-temperature specific heat (low-T C) in the lightly Mn-substituted electron-doped perovskites Sr0.95La0.05Ti1-yMnzO3 with y = 0.02 and 0.04 by applying magnetic fields up to 9 T. The changes in the low-T C are qualitatively well explained by the Schottky specific heat (CSch) of localized spins of the Mn 3d electrons in weak internal magnetic fields via itinerant electrons. However, the actual numbers of localized spins estimated from CSch are about 30% smaller than the expected values. Part of the localized spins of the Mn 3d electrons may disappear due to Kondo coupling with the itinerant electrons.

  10. Low-temperature specific heat and magnetic properties of the filled skutterudite ferromagnet NdRu4As12

    Science.gov (United States)

    Rudenko, A.; Henkie, Z.; Cichorek, T.

    2016-09-01

    We present the low-temperature specific heat and magnetic properties of the filled skutterudite compound NdRu4As12 that exhibits a ferromagnetic transition at TC ≃ 2.3 K . Magnetic entropy considerations point at a quartet ground state of the Nd3+ ions. Deep in the ferromagnetic state, the heat capacity shows a Schottky anomaly that we ascribe to the Zeeman splitting in the presence of a molecular field. Comparison of the specific heats of NdRu4As12 and its Os-based homologue near their Curie temperatures supports our earlier observation suggesting an unusual lowering of the Th cubic point symmetry in the latter filled skutterudite.

  11. SPECIFIC HEAT CAPACITY AND THERMAL CONDUCTIVITY OF HEAT STORAGE MATERIALS BASED ON PARAFFIN, BROWN-COAL WAX AND POLYETHYLENE WAX

    Directory of Open Access Journals (Sweden)

    Snezhkin Yu.

    2014-08-01

    Full Text Available The present paper overviews heat storage materials (HSM with phase change based on organic compounds. They consist of paraffin, brown-coal wax and polyethylene wax. These materials are produced on an industrial scale for the foundry work. It is shown that heat capacity of HSM in the solid and liquid states can be used for heat storage in addition to the heat of phase change. The results of investigations of phase change during heating and cooling HSM are presented. The studies are carried out by differential scanning calorimetry (DSC. The measurement techniques of the specific heat capacity and the coefficient of thermal conductivity are shown. Temperature dependences of the specific heat capacity of HSM in the solid and liquid states are researched by DSC. Values of the coefficient of thermal conductivity are determined by contact stationary technique of the flat plate over the entire temperature range of the operation of heat storage system.

  12. A δ-function-like peak in the specific heat of two-dimensional vortex lattice: Monte carlo study

    Institute of Scientific and Technical Information of China (English)

    梁彦天; 曹义刚; 焦正宽

    2002-01-01

    A repulsive vortex-vortex interaction model was used to numerically study the melting transition of the two-dimensional vortex system with Monte Carlo method. Then a δ-function-like peak in the specific heat was observed and the internal energy showed a sharp drop at the melting temperature, whieh indicated that there exists a first-order melting transition at finite temperatures. The Lindemarm criterion was also investigated and valid, but different from previous simulation results.

  13. Specific heat and frequency-dependent ac-susceptibility of PrNi2 below 1 K

    Science.gov (United States)

    Greidanus, F. J. A. M.; De Jongh, L. J.; Huiskamp, W. J.; Buschow, K. H. J.

    1982-01-01

    Ac-susceptibility measurements on PrNi2 show broad anomalies, the temperature of the susceptibility maximum shifting from 0.3-0.5 K as the frequency is varied in between 3 Hz and 3 kHz. On the other hand the specific heat is featureless in the same temperature range. The behaviour is interpreted in terms of a mixed electronic-nuclear phase transition. Strong relaxation effects are observed in the susceptibility at temperatures close to the maxima.

  14. Low-temperature crystal structure, specific heat, and dielectric properties of lithium tetraborate Li2B4O7

    Science.gov (United States)

    Senyshyn, A.; Schwarz, B.; Lorenz, T.; Adamiv, V. T.; Burak, Ya. V.; Banys, J.; Grigalaitis, R.; Vasylechko, L.; Ehrenberg, H.; Fuess, H.

    2010-11-01

    Coherent neutron powder diffraction experiments were carried out together with specific heat, dilatometry, and dielectric spectroscopy studies on Li2B4O7 enriched with B11 isotope to 99.3% at low temperatures. Neither traces of phase transformations nor discontinuous changes in physical properties were observed. Negative thermal expansion, anomalous thermal behavior of selected interatomic distances/angles, isotropic displacement parameters on specific sites as well as dielectric constant were discussed in terms of dynamic lithium disorder.

  15. Origin of two maxima in specific heat in enthalpy relaxation under thermal history composed of cooling, annealing, and heating

    Science.gov (United States)

    Sakatsuji, Waki; Konishi, Takashi; Miyamoto, Yoshihisa

    2016-12-01

    The origin of two maxima in specific heat observed at the higher and the lower temperatures in the glass-transition region in the heating process has been studied for polymethyl methacrylate and polyvinyl chloride using differential scanning calorimetry, and the calculation was done using the phenomenological model equation under a thermal history of the typical annealing experiment composed of cooling, annealing, and heating. The higher maximum is observed above the glass-transition temperature, and it remains almost unchanged independent of annealing time ta, while the lower one is observed above an annealing temperature Ta and shifts toward the higher one, increasing its magnitude with ta. The analysis by the phenomenological model equation proposed in order to interpret the memory effect in the glassy state clarifies that under a typical annealing history, two maxima in specific heat essentially appear. The shift of the lower maximum toward higher temperatures from above Ta is caused by an increase in the amount of relaxation during annealing with ta. The annealing temperature and the amount of relaxation during annealing play a major role in the determination of the number of maxima in the specific heat.

  16. A study on specific heat capacities of Li-ion cell components and their influence on thermal management

    Science.gov (United States)

    Loges, André; Herberger, Sabrina; Seegert, Philipp; Wetzel, Thomas

    2016-12-01

    Thermal models of Li-ion cells on various geometrical scales and with various complexity have been developed in the past to account for the temperature dependent behaviour of Li-ion cells. These models require accurate data on thermal material properties to offer reliable validation and interpretation of the results. In this context a thorough study on the specific heat capacities of Li-ion cells starting from raw materials and electrode coatings to representative unit cells of jelly rolls/electrode stacks with lumped values was conducted. The specific heat capacity is reported as a function of temperature and state of charge (SOC). Seven Li-ion cells from different manufactures with different cell chemistry, application and design were considered and generally applicable correlations were developed. A 2D thermal model of an automotive Li-ion cell for plug-in hybrid electric vehicle (PHEV) application illustrates the influence of specific heat capacity on the effectivity of cooling concepts and the temperature development of Li-ion cells.

  17. Origin of two maxima in specific heat in enthalpy relaxation under thermal history composed of cooling, annealing, and heating.

    Science.gov (United States)

    Sakatsuji, Waki; Konishi, Takashi; Miyamoto, Yoshihisa

    2016-12-01

    The origin of two maxima in specific heat observed at the higher and the lower temperatures in the glass-transition region in the heating process has been studied for polymethyl methacrylate and polyvinyl chloride using differential scanning calorimetry, and the calculation was done using the phenomenological model equation under a thermal history of the typical annealing experiment composed of cooling, annealing, and heating. The higher maximum is observed above the glass-transition temperature, and it remains almost unchanged independent of annealing time t_{a}, while the lower one is observed above an annealing temperature T_{a} and shifts toward the higher one, increasing its magnitude with t_{a}. The analysis by the phenomenological model equation proposed in order to interpret the memory effect in the glassy state clarifies that under a typical annealing history, two maxima in specific heat essentially appear. The shift of the lower maximum toward higher temperatures from above T_{a} is caused by an increase in the amount of relaxation during annealing with t_{a}. The annealing temperature and the amount of relaxation during annealing play a major role in the determination of the number of maxima in the specific heat.

  18. Specific-heat of polycrystalline (Hg,Pb)Ba 2Ca 2C 3O 8+δ near T c

    Science.gov (United States)

    Jeandupeux, O.; Schilling, A.; Büchi, S.; Guo, J. D.; Ott, H. R.

    1994-12-01

    We have measured the specific heat of polycrystalline (Hg,Pb)Ba 2Ca 2Cu 3O 8+δ between 60 K and 200 K with a calorimeter based on the standard continuous-heating method. The occurence of an anomaly in Cp( T)/ T peaking at Tc for these samples clearly shows that superconductivity is a bulk phenomenon in this type of compound. After subtraction of a fitted background, we deduce a value of ΔCp/ Tc≈27 mJ/mole K 2 for a 15% Pb-doped sample containing ≈60% of Hg-1223. An as-prepared sample containing Hg 0.8Pb 0.2Ba 2Ca 2Cu 3O 8+δ as the dominant phase shows a distinct anomaly in the specific heat data at Tc=130 K and at Tc=115 K for a specimen cut from the same initial sample after oxygen annealing. The size and the shape of the specific heat anomalies are very similar, irrespective of the value of Tc and thus hole-dopping level.

  19. The determination of values of the specific heat capacity of the selected thermal insulation materials used in track bed structure

    Directory of Open Access Journals (Sweden)

    Dobeš Peter

    2017-01-01

    Full Text Available The report concentrates on the determination of the specific heat capacity of the selected thermal insulation materials (liapor, styrodur, foam concrete. The aim of the report is to gain the necessary input parameters for the numerical modelling of the temperature changes of various track bed structures of the railway line where a part or, if appropriate, the whole protective layer is replaced by the material with better thermal insulation properties. There are described the methods for stating the specific heat capacity as well as the calibration of the calorimeter for stating of the calorimetric constant in the introduction of the report. The parameters needed for calculation of the specific heat capacity of the selected thermal insulation materials are characterized in the second part of the report. There are also introduced the laboratory stated values of the parameter in question. The comparison of the values stated by the laboratory measurements with the values introduced in the technical data sheets from their producers (or if appropriate gained from the foreign sources is made in the conclusion of the report.

  20. Forgiveness Flexibility

    Directory of Open Access Journals (Sweden)

    Tuğba Seda Çolak

    2016-01-01

    Full Text Available Forgiveness flexibility is the skill to minimize the negative effect of an event by using cognitive, affective and behavioral skills while taking a stand at the end of an injurious process. A number of studies were conducted to test the flexibility of the structure of forgiveness. The theoretical structure, structural validity and the confirmatory factor analysis supported the theoretical structure of forgiveness flexibility. The criterion validity evaluated in similar manners was found high. Forgiveness flexibility designed as a three dimensional structure and its sub-dimensions was confirmed theoretically as the recognition of forgivenessand the internalization of forgiveness through insight and its practice.

  1. Conflicting flexibility

    NARCIS (Netherlands)

    De Jong, P.; Schaap, A.

    2011-01-01

    New buildings are designed for first users. For a sustainable approach there are many advantages in designing in flexibility and adjustability in order to enable and facilitate the other sequential users. For the first investor this flexibility is translated into improved exit values due to

  2. RSM Base Study of the Effect of Argon Gas Flow Rate and Annealing Temperature on the [Bi]:[Te] Ratio and Thermoelectric Properties of Flexible Bi-Te Thin Film

    Science.gov (United States)

    Nuthongkum, Pilaipon; Sakulkalavek, Aparporn; Sakdanuphab, Rachsak

    2016-10-01

    Bismuth telluride (Bi-Te) thin films coated on a flexible substrate were prepared by RF (radio frequency) magnetron sputtering technique. A response surface methodology based on a central composite design was used to optimize deposition parameters, including the amount of Ar gas flow rate (100.5-106.5 sccm) in the sputtering process and the annealing temperature (250-320°C) for stoichiometric Bi2Te3 thin films. The mathematical model was validated and proven to be statistically sufficient and accurate in predicting a response (Te content). The stoichiometric Bi2Te3 thin films can be prepared on terms appropriate to the Ar flow rate and annealing temperature under several conditions, such as at the Ar flow rate of 103.5 sccm followed by an annealing temperature of 285°C. The characterization of the crystal structure and surface morphology of selected samples with different [Bi]:[Te] content were analyzed by x-ray diffraction (XRD) and a field emission scanning electron microscope, respectively. The XRD spectra showed Bi-Te and Bi2Te3 structures that corresponded with the ratio of [Bi]:[Te]. The Seebeck coefficient and electrical conductivity were simultaneously measured at room temperature and up to 300°C by a direct current four-terminal method. The maximum power factor of the stoichiometric Bi2Te3 thin film was 61×10-5 W/K2m at 243°C.

  3. Specific heat of single crystal MgB2: a two-band superconductor with two different anisotropies.

    Science.gov (United States)

    Bouquet, F; Wang, Y; Sheikin, I; Plackowski, T; Junod, A; Lee, S; Tajima, S

    2002-12-16

    Heat-capacity measurements of a 39 microg MgB2 single crystal in fields up to 14 T and below 3 K allow the determination of the low-temperature linear term of the specific heat, its field dependence, and its anisotropy. Our results are compatible with two-band superconductivity, the band carrying the smaller gap being isotropic, that carrying the larger gap having an anisotropy of approximately 5. Three different upper critical fields are thus needed to describe the superconducting state of MgB2.

  4. Specific heat and phonon density of state of cubic phase of protonic conductor LaAlO3

    Science.gov (United States)

    Sharma, Anupam Deep; Sinha, M. M.

    2016-05-01

    Perovskite oxides find wide range of applications like oxygen sensors, catalyst support, high frequency capacitors, high temperature superconducting microwave devices, solid state oxide fuel cell (SOFC) etc. LaAlO3 is one of such type of prominent perovskite oxides and very prominent material for protonic conductions. Therefore knowledge of the thermal properties of LaAlO3 is most significant. Hence in the present study we have studied phonon density of states and specific heat of LaAlO3 in cubic structure by applying lattice dynamical theoretical model. The calculated results are interpreted with existing experimental or theoretical results.

  5. Flexible magnetoimpedance sensor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bodong; Kavaldzhiev, Mincho N.; Kosel, Jürgen, E-mail: jurgen.kosel@kaust.edu.sa

    2015-03-15

    Flexible magnetoimpedance (MI) sensors fabricated using a NiFe/Cu/NiFe tri-layer on Kapton substrate have been studied. A customized flexible microstrip transmission line was employed to investigate the MI sensors's magnetic field and frequency responses and their dependence on the sensors's deflection. For the first time, the impedance characteristic is obtained through reflection coefficient analysis over a wide range of frequencies from 0.1 MHz to 3 GHz and for deflections ranging from zero curvature to a radius of 7.2 cm. The sensor element maintains a high MI ratio of up to 90% and magnetic sensitivity of up to 9.2%/Oe over different bending curvatures. The relationship between the curvature and material composition is discussed based on the magnetostriction effect and stress simulations. The sensor's large frequency range, simple fabrication process and high sensitivity provide a great potential for flexible electronics and wireless applications. - Highlights: • A flexible magnetoimpedance (MI) sensor is developed. • Studies are carried out using a flexible microstrip transmission line. • An MI ratio of up to 90% is obtained. • The effect of magnetostriction is studied.

  6. Flexible Sigmoidoscopy

    Science.gov (United States)

    ... Task Force (USPSTF). Most doctors recommend colonoscopy to screen for colon cancer because colonoscopy shows the entire colon and can remove colon polyps. However, preparing for and performing a flexible sigmoidoscopy may take less time and you may ...

  7. Calculation of thermal conductivity, thermal diffusivity and specific heat capacity of sedimentary rocks using petrophysical well logs

    Science.gov (United States)

    Fuchs, Sven; Balling, Niels; Förster, Andrea

    2015-12-01

    In this study, equations are developed that predict for synthetic sedimentary rocks (clastics, carbonates and evapourates) thermal properties comprising thermal conductivity, specific heat capacity and thermal diffusivity. The rock groups are composed of mineral assemblages with variable contents of 15 major rock-forming minerals and porosities of 0-30 per cent. Petrophysical properties and their well-logging-tool-characteristic readings were assigned to these rock-forming minerals and to pore-filling fluids. Relationships are explored between each thermal property and other petrophysical properties (density, sonic interval transit time, hydrogen index, volume fraction of shale and photoelectric absorption index) using multivariate statistics. The application of these relations allows computing continuous borehole profiles for each rock thermal property. The uncertainties in the prediction of each property vary depending on the selected well-log combination. Best prediction is in the range of 2-8 per cent for the specific heat capacity, of 5-10 per cent for the thermal conductivity, and of 8-15 for the thermal diffusivity, respectively. Well-log derived thermal conductivity is validated by laboratory data measured on cores from deep boreholes of the Danish Basin, the North German Basin, and the Molasse Basin. Additional validation of thermal conductivity was performed by comparing predicted and measured temperature logs. The maximum deviation between these logs is effect on the subsurface temperature field can be observed in the North German Basin. This effect reduces the surface heat-flow density by 25 mW m-2.

  8. Studies of Nucleation and Growth, Specific Heat and Viscosity of Undercooled Melts of Quasicrystals and Polytetrehedral-Phase-Forming Alloys

    Science.gov (United States)

    2003-01-01

    By investigating the properties of quasicrystals and quasicrystal-forming liquid alloys, we may determine the role of ordering of the liquid phase in the formation of quasicrystals, leading to a better fundamental understanding of both the quasicrystal and the liquid. A quasicrystal is solid characterized by a symmetric but non-periodic arrangement of atoms, usually in the form of an icosahedron (12 atoms, 20 triangular faces). It is theorized that the short-range order in liquids takes this same form. The degree of ordering depends on the temperature of the liquid, and affects many of the liquid s properties, including specific heat, viscosity, and electrical resistivity. The MSFC role in this project includes solidification studies, phase diagram determination, and thermophysical property measurements on the liquid quasicrystal-forming alloys, all by electrostatic levitation (ESL). The viscosity of liquid quasicrystal-forming alloys is measured by the oscillating drop method, both in the stable and undercooled liquid state. The specific heat of solid, undercooled liquid, and stable liquid are measured by the radiative cooling rate of the droplets.

  9. Evaluation of high specific-heat ceramic for regenerator use at temperatures between 2-30 K

    Science.gov (United States)

    Lawless, W. N.

    1979-01-01

    Specific heat, thermal conductivity (both in the range 2-30 K), and microhardness data were measured on the ceramics labelled LS-8, LS-8A, and LS-8A doped with CsI, SnCl2, and AgCl. A work hardened sample of LS-8A was also studied in an effort to determine the feasibility of using these types of LS-8 materials to replace Pb spheres in the regenerator of the JPL cryocooler. The LS-8A materials are all more than an order of magnitude harder than Pb, and the dopants do not significantly improve the hardness. However, the SnCl2 dopant has a remarkable effect in improving the specific heat and thermal conductivity of LS-8A. The SnCl2 doping level which maximized the regenerator enthalpy change in going from an unloaded to a loaded condition was found to be 0.2 percent SnCl2 in LS-8A. It was also found that the enthalpy change for a regenerator employing the LS-8A material is more than three times larger than for the Pb spheres case. The use of rods, rather than spheres, of optimally doped LS-8A in regenerators is discussed.

  10. Influence of tribomechanical micronization and hydrocolloids addition on enthalpy and apparent specific heat of whey protein model solutions

    Directory of Open Access Journals (Sweden)

    Zoran Herceg

    2002-01-01

    Full Text Available Knowledge of thermophysical properties, especially the phase transitions temperature, specific heat and enthalpy, are essential in defining the freezing process parameters as well as storage conditions of frozen food. In this work thermophysical properties of 10% model solutions prepared with 60% whey protein concentrate (WPC with various hydrocolloids addition (HVEP, YO-EH, YO-L i YO-M were investigated. Powdered whey protein concentrate was treated in equipment for tribomechanical micronization and activation at 40000 rpm (Patent: PCT/1B99/00757 just before model solutions preparation. Particle size analysis was performed using Frich –laser particle sizer “analysette 22”. The phase transition temperatures were determined by differential thermal analysis (DTA, while specific heat and enthalpy were calculated according to several mathematical equations. The results have shown that, due to tribomechanical treatment, certain changes in thermophysical and energetic properties of materials occurred. Tribomechanical treatment affects changes in granulometrical composition of WPC which result in higher abilities of reactions with hydrocolloids in model solutions and significant changes in thermophysical properties of the mentioned models.

  11. Specific heat study of the iridium double perovskite Sr{sub 2}YIrO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Corredor, Laura T.; Manna, Kaustuv; Aslan Cansever, Gizem; Gass, Sebastian; Zimmermann, Andreas; Dey, Tushar; Blum, Christian; Maljuk, Andrey; Wurmehl, Sabine; Wolter, Anja; Buechner, Bernd [Leibniz Institute for Solid State and Materials Research Dresden, IFW Dresden (Germany)

    2016-07-01

    Recently, Mott insulators with a d{sup 4} electronic configuration were predicted to show superexchange-driven quantum phase transitions. Double perovskites R{sub 2}MM{sup '}O{sub 6} with M{sup '3+} ion, yielding a formal oxidation state of Ir{sup 5+} with 5d{sup 4} electronic configuration, may be candidates to verify or discard such transitions and its impact on the magnetic structure. According to the strong spin-orbit coupling J{sub eff} model, a non-magnetic ground state is expected. Such material is realized in Sr{sub 2}YIrO{sub 6}. Nevertheless, it is claimed that a strong non-cubic crystal field together with a ''intermediate-strength'' spin-orbit coupling, would lead to a different ground state configuration and to antiferromagnetic behavior with T{sub N} = 1.3 K. Also, anomalies in the specific heat were associated to this novel magnetism. In this work, we present magnetic and thermodynamic characterization of Sr{sub 2}YIrO{sub 6} single crystals. No long magnetic order was found. The magnetic contribution to the specific heat was calculated, finding a Schottky anomaly due to magnetic impurities. Further analysis suggests non-negligible spin correlations, which nonetheless, are not associated with long range magnetic ordering.

  12. Specific heat study of geometrically frustrated magnet clinoatacamite Cu{sub 2}Cl(OH){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Morodomi, Hiroki; Ienaga, Koichiro; Inagaki, Yuji; Kawae, Tatsuya [Department of Applied Quantum Physics, Kyushu University, Moto-oka, Fukuoka 812-8581 (Japan); Hagiwara, Masayuki; Zheng, X G, E-mail: 3te09049m@s.kyushu-u.ac.j [Department of Physics, Saga University, Saga, 840-8502 (Japan)

    2010-01-01

    We have performed the specific heat study in a new geometrically frustrated system, clinoatacamite Cu2Cl(OH)3 with the corner-sharing tetrahedron structure of the Cu{sup 2+} ions with 5=1/2 Heisenberg spin. At H=0 T, two anomalies are observed at T{sub 2}=18.1 K and at T{sub 2}=6.2 K. The specific heat decreases rapidly below T{sub 2} and shows no anomaly down to T=150 mK despite the existence of the spin fluctuation shown in the {mu}SR experiments. As the magnetic field is increased, the sharp peak at T{sub 2} is broadened and shows a small reentrant behavior in the T - H phase diagram. On the other hand, the peak at T{sub 1} shows no obvious change up to H=5 T. The entropy at T{sub 1} is estimated as {approx}0.35Rln2 at H=0 T. These features may be caused by the two dimensional nature of the kagome antiferromagnets which are weakly coupled via Cu{sup 2+} ions at the triangular sites located in between the kagome layers.

  13. Crystal-field study of magnetization and specific heat properties of frustrated pyrochlore Pr2Zr2O7

    Science.gov (United States)

    Alam, J.; Jana, Y. M.; Biswas, A. Ali

    2016-10-01

    The experimental results of temperature dependent dc magnetic susceptibility, field dependent isothermal magnetization, magnetic specific heat and entropy of the pyrochlore Pr2Zr2O7 are simulated and analyzed using appropriate D3d crystal-field (CF) and anisotropic molecular field tensors at Pr-sites in the self-consistent mean-field approach involving four magnetically non-equivalent rare-earth spins on the tetrahedral unit of the pyrochlore structure. CF level pattern and wave-functions of the ground 3H4 multiplet of the Pr3+ ions are obtained considering intermediate coupling between different Russell-Saunders terms of the 4f2 electronic configurations of Pr-ion and J-mixing effects. CF analysis shows that the CF ground-state of the Pr3+ ion in Pr2Zr2O7 is a well-isolated doublet, with significant admixtures of terms coming from |MJ=±4> and |MJ=±1>, and the Pr-spins are effectively Ising-like along the local axes. Magnetic specific heat in zero-field is simulated by considering a temperature dependence of the exchange splitting of the ground doublet.

  14. The specific heat loss combined with the thermoelastic effect for an experimental analysis of the mean stress influence on axial fatigue of stainless steel plain specimens

    Directory of Open Access Journals (Sweden)

    G. Meneghetti

    2014-10-01

    Full Text Available The energy dissipated to the surroundings as heat in a unit volume of material per cycle, Q, was recently proposed by the authors as fatigue damage index and it was successfully applied to correlate fatigue data obtained by carrying out fully reversed stress- and strain-controlled fatigue tests on AISI 304L stainless steel plain and notched specimens. The use of the Q parameter to analyse the experimental results led to the definition of a scatter band having constant slope from the low- to the high-cycle fatigue regime. In this paper the energy approach is extended to analyse the influence of mean stress on the axial fatigue behaviour of unnotched cold drawn AISI 304L stainless steel bars. In view of this, stress controlled fatigue tests on plain specimens at different load ratios R (R=-1; R=0.1; R=0.5 were carried out. A new energy parameter is defined to account for the mean stress effect, which combines the specific heat loss Q and the relative temperature variation due to the thermoelastic effect corresponding to the achievement of the maximum stress level of the stress cycle. The new two-parameter approach was able to rationalise the mean stress effect observed experimentally. It is worth noting that the results found in the present contribution are meant to be specific for the material and testing condition investigated here.

  15. Nodal Gap in Fe-Based Layered Superconductor LaO0.9F0.1-δFeAs Probed by Specific Heat Measurements

    Institute of Scientific and Technical Information of China (English)

    MU Gang; ZHU Xi-Yu; FANG Lei; SHAN Lei; REN Cong; WEN Hai-Hu

    2008-01-01

    We report the specific heat measurements on the newly discovered Fe-based layered LaO0.9F0.1-δFeAs supercon-ductor with the onset transition temperature Tc≈28 K. A nonlinear magnetic field dependence of the electronic specific heat coefficient γ(H) has been found in the low temperature limit, which is consistent with the prediction for a nodal superconductor. The maximum gap value △0 ≈ 3.4 ± 0.5 me V is derived by analysing γ( H) based on the d-wave model. We also detected the electronic specific heat difference between 9 T and 0 T in a wide temper-ature range, a specific heat anomaly can be clearly observed near Tc. The Debye temperature of our sample is determined to be about 315.7K. Our results suggest an unconventional mechanism for this new superconductor.

  16. Study on constant-pressure specific heat of non-equi- librium phase change process in gas-liquid two-phase flow system

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, the air-water vapor-water system is taken as an example, and the formula of constantpressure specific heat during non-equilibrium phase change process in the two-phase flow system is deduced using the theory of two-phase flow and thermophysics. The constant-pressure specific heat of non-equilibrium phase change process is calculated with the corresponding numerical model, and the numerical results are compared to those of the equilibrium phase change process. It is shown that in evaporation process, the variational rate of the non-equilibrium specific heat increases with increasing initial fluid temperature and particle mass fraction. The smaller particle radius is, the faster the variational rate is. Meanwhile, the constant-pressure specific heat of equilibrium process is higher than that of the non-equilibrium process all the time.

  17. Flexible magnetoimpedance sensor

    KAUST Repository

    Li, Bodong

    2015-03-01

    Flexible magnetoimpedance (MI) sensors fabricated using a NiFe/Cu/NiFe tri-layer on Kapton substrate have been studied. A customized flexible microstrip transmission line was employed to investigate the MI sensors\\'s magnetic field and frequency responses and their dependence on the sensors\\'s deflection. For the first time, the impedance characteristic is obtained through reflection coefficient analysis over a wide range of frequencies from 0.1 MHz to 3 GHz and for deflections ranging from zero curvature to a radius of 7.2 cm. The sensor element maintains a high MI ratio of up to 90% and magnetic sensitivity of up to 9.2%/Oe over different bending curvatures. The relationship between the curvature and material composition is discussed based on the magnetostriction effect and stress simulations. The sensor\\'s large frequency range, simple fabrication process and high sensitivity provide a great potential for flexible electronics and wireless applications.

  18. Effect of high energy electron beam (10MeV) on specific heat capacity of low-density polyethylene/hydroxyapatite nano-composite.

    Science.gov (United States)

    Soltani, Z; Ziaie, F; Ghaffari, M; Beigzadeh, A M

    2017-02-01

    In the present work, thermal properties of low density polyethylene (LDPE) and its nano composites are investigated. For this purpose LDPE reinforced with different weight percents of hydroxyapatite (HAP) powder which was synthesized via hydrolysis method are produced. The samples were irradiated with 10MeV electron beam at doses of 75 to 250kGy. Specific heat capacity measurement have been carried out at different temperatures, i.e. 25, 50, 75 and 100°C using modulated temperature differential scanning calorimetry (MTDSC) apparatus and the effect of three parameters include of temperature, irradiation dose and the amount of HAP nano particles as additives on the specific heat capacity of PE/HAP have been investigated precisely. The MTDSC results indicate that the specific heat capacity have decreased by addition of nano sized HAP as reinforcement for LDPE. On the other hand, the effect of radiation dose is reduction in the specific heat capacity in all materials including LDPE and its nano composites. The HAP nano particles along with cross-link junctions due to radiation restrain the movement of the polymer chains in the vicinity of each particle and improve the immobility of polymer chains and consequently lead to reduction in specific heat capacity. Also, the obtained results confirm that the radiation effect on the specific heat capacity is more efficient than the reinforcing effect of nano-sized hydroxyapatite.

  19. Resistivity, Specific Heat, and Susceptibility of the Intermediate Valence System Cerium ((RHODIUM(X)PALLADIUM(1 -X))(3))

    Science.gov (United States)

    Scoboria, Clarence Preston, III

    In the mixed valent system Ce(Rh(,x)Pd(,1-x))(,3), the dependence of resistivity, magnetic susceptibility, and specific heat on the rhodium concentration x has been experimentally studied. Ce(Rh(,x)Pd(,1-x))(,3) is tetravalent from x = .216 to 1.00, and mixed valent from x = .216 to x = 0. Based on Vegard's rule and lattice constant data, n(,f) is considered to vary linearly with x, ranging from n(,f) = 0 at x = .216 to n(,f) (TURNEQ) .55 at x = 0. The resistivity was measured from 1.5K to 300K for x from 0 to 1. In the tetravalent range the temperature dependence was independent of x. In the mixed valent region (rho) at all temperatures increased rapidly with n(,f). (rho) (T = 0) was found to be proportional to n(,f)('2) in the mixed valent range. Application of pressures up to seven kilobars were found to produce very little change in resistivity in the mixed valent range. The specific heat was measured from 2K to 15K in the mixed valent range and for CeRh(,3). C/T versus T('2) plots were well-fitted by a straight line at low temperature except for a bump at 6K, which is not understood. The mixed valence component of the electronic specific heat coefficient (gamma) is found to be proportional to n(,f)('2). Magnetic susceptibility was measured from 2K to 300K in the mixed valent range. For each x, (chi) (T) was approximately independent of temperature below (TURN) 150K, except for an impurity tail below 40K. (chi)(,0) (the plateau value) was found to be approximately proportional to n(,f) in the mixed valent range. All three quantities (rho), (gamma), and (chi) are compared to the theories of Yosida and Sakurai, and Newns and Hewson. The best fits indicate that the f level density of states is well represented by a lorentzian which can accommodate six electrons.

  20. Piping Flexibility

    Science.gov (United States)

    1978-01-01

    A NASA computer program aids Hudson Engineering Corporation, Houston, Texas, in the design and construction of huge petrochemical processing plants like the one shown, which is located at Ju'aymah, Saudi Arabia. The pipes handling the flow of chemicals are subject to a variety of stresses, such as weight and variations in pressure and temperature. Hudson Engineering uses a COSMIC piping flexibility analysis computer program to analyze stresses and unsure the necessary strength and flexibility of the pipes. This program helps the company realize substantial savings in reduced engineering time.

  1. Calculation of thermal conductivity, thermal diffusivity and specific heat capacity of sedimentary rocks using petrophysical well logs

    DEFF Research Database (Denmark)

    Fuchs, Sven; Balling, Niels; Förster, Andrea

    2015-01-01

    of 15 major rock-forming minerals and porosities of 0–30 per cent. Petrophysical properties and their well-logging-tool-characteristic readings were assigned to these rock-forming minerals and to pore-filling fluids. Relationships are explored between each thermal property and other petrophysical...... of each property vary depending on the selected well-log combination. Best prediction is in the range of 2–8 per cent for the specific heat capacity, of 5–10 per cent for the thermal conductivity, and of 8–15 for the thermal diffusivity, respectively. Well-log derived thermal conductivity is validated...... by laboratory data measured on cores from deep boreholes of the Danish Basin, the North German Basin, and the Molasse Basin. Additional validation of thermal conductivity was performed by comparing predicted and measured temperature logs. The maximum deviation between these logs is

  2. Electronic structure of UN based on specific heat and field-induced transitions up to 65 T

    Science.gov (United States)

    Troć, R.; Samsel-Czekała, M.; Pikul, A.; Andreev, A. V.; Gorbunov, D. I.; Skourski, Y.; Sznajd, J.

    2016-12-01

    The 5 f electrons of uranium in the uranium mononitride (UN) compound are described in the literature as either localized or fully itinerant. Motivated by these contradictory statements, we studied low-temperature specific heat and high-field magnetization of single-crystalline UN in magnetic fields up to 9 and 65 T, respectively. Our detailed analysis of the magnetic contribution to the specific heat of UN revealed that its real ground state is complex and the 5 f electrons seem to have a dual nature; i.e., they possess simultaneously local and itinerant characters in two substates. High-field experiments allowed us to construct a tentative magnetic phase diagram of UN with a metamagnetic transition from antiferromagnetism to ferrimagnetism at a magnetic field as high as 58 T at 2 K. Such a field only enables a reversal of 1 of the 12 antiferromagnetically coupled ferromagnetic layers in the direction of the magnetic field. Any further steplike transitions require application of ever higher magnetic fields, which is beyond the experimental possibilities. We show that the magnetic phase diagram can be successfully reproduced considering a layer model of the Ising spins. That model allows rough estimation of a phase transition into fully induced ferromagnetism at a field as high as about 258 T. It gives rise to a giant coupling between ferromagnetically ordered layers in UN. The obtained characteristics are presented, together with the results of recent x-ray photoemission spectroscopy and transport property measurements. They are analyzed and compared with a number of earlier experiments and band structure calculations that were performed for this compound and are widely described in the literature. We show that different experiments probe different substates of the uranium 5 f electrons in UN (itinerant or localized), which supports our hypothesis on their dual nature.

  3. Flexibility conflict?

    NARCIS (Netherlands)

    Delsen, L.W.M.

    2002-01-01

    The chapter deals with the presupposed conflict of interests between employers and employees resulting from a decoupling of operating hours and working times. It starts from the notion that both long operating hours and flexibility are relative concepts. As there is some discretion, the ultimate

  4. Flexible Consumption

    DEFF Research Database (Denmark)

    Holm Jacobsen, Peter; Pallesen, Trine

    This report presents the first findings from our qualitative study of consumer behaviour vis-à-vis flexible consumption. The main of objective of this report is to present our first round of data from Bornholm, and to assist the design of products/services designed in WP6. In the report, we adopt...

  5. Flexible isotopy classification of flexible links

    OpenAIRE

    Björklund, Johan

    2012-01-01

    In this paper we define and study flexible links and flexible isotopy in projective space. Flexible links are meant to capture the topological properties of real algebraic links. We classify all flexible links up to flexible isotopy using Ekholms interpretation of Viros encomplexed writhe.

  6. Flexible Capitalism

    DEFF Research Database (Denmark)

    Approaching “work” as at heart a practice of exchange, this volume explores sociality in work environments marked by the kind of structural changes that have come to define contemporary “flexible” capitalism. It introduces anthropological exchange theory to a wider readership, and shows how...... the perspective offers new ways to enquire about the flexible capitalism’s social dimensions. The essays contribute to a trans-disciplinary scholarship on contemporary economic practice and change by documenting how, across diverse settings, “gift-like” socialities proliferate, and even sustain the intensified...... flexible commoditization that more commonly is touted as tearing social relations apart. By interrogating a keenly debated contemporary work regime through an approach to sociality rooted in a rich and distinct anthropological legacy, the volume also makes a novel contribution to the anthropological...

  7. Quasiparticle density of states of 2H-NbSe2 single crystals revealed by low-temperature specific heat measurements according to a two-component model

    Institute of Scientific and Technical Information of China (English)

    Yan Jing; Shan Lei; Wang Yue; Xiao Zhi-Li; Wen Hai-Hu

    2008-01-01

    Low-temperature specific heat in a dichalcogenide superconductor 2H-NbSe2 is measured in various magnetic fields. It is found that the specific heat can be described very well by a simple model concerning two components corresponding to vortex normal core and ambient superconducting region, separately. For calculating the specific heat outside the vortex core region, we use the Bardeen-Cooper-Schrieffer (BCS) formalism under the assumption of a narrow distribution of the superconducting gaps. The field-dependent vortex core size in the mixed state of 2H-NbSe2, determined by using this model, can explain the nonlinear field dependence of specific heat coefficient γ(H), which is in good agreement with the previous experimental results and more formal calculations. With the high-temperature specific heat data, we can find that, in the multi-band superconductor 2H-NbSe2, the recovered density of states (or Fermi surface) below Tc under a magnetic field seems not to be gapped again by the charge density wave (CDW) gap, which suggests that the superconducting gap and the CDW gap may open on different Fermi surface sheets.

  8. Flexible Blades for Wind Turbines

    Science.gov (United States)

    Collins, Madeline Carlisle; Macphee, David; Harris, Caleb

    2016-11-01

    Previous research has shown that windmills with flexible blades are more efficient than those with rigid blades. Flexibility offers passive pitch control, preferable to active pitch control which is costly and requires maintenance. Flexible blades morph such that the blade more closely resembles its design point at part load and over load. The lift-to-drag ratios on individual blades was investigated. A mold was designed and machined from an acrylic slab for the casting of blades with a NACA 0012 cross section. A flexible blade was cast from silicone and a rigid blade was cast from polyurethane. Each of these blades was tested in a wind tunnel, cantilever mounted, spanning the whole test section. The angle of attack was varied by rotating the mount. All tests were performed at the same wind speed. A load cell within the mount measured forces on the blade, from which the lift and drag forces were calculated. The stall point for the flexible blade occurred later than for the rigid blade, which agrees with previous research. Lift-to-drag ratios were larger for the flexible blade at all angles of attack tested. Flexible blades seem to be a viable option for passive pitch control. Future research will include different airfoil cross sections, wind speeds, and blade materials. Funding from NSF REU site Grant EEC 1358991 is greatly appreciated.

  9. Full density-matrix numerical renormalization group calculation of impurity susceptibility and specific heat of the Anderson impurity model

    Science.gov (United States)

    Merker, L.; Weichselbaum, A.; Costi, T. A.

    2012-08-01

    Recent developments in the numerical renormalization group (NRG) allow the construction of the full density matrix (FDM) of quantum impurity models [see A. Weichselbaum and J. von Delft, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.99.076402 99, 076402 (2007)] by using the completeness of the eliminated states introduced by F. B. Anders and A. Schiller [F. B. Anders and A. Schiller, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.95.196801 95, 196801 (2005)]. While these developments prove particularly useful in the calculation of transient response and finite-temperature Green's functions of quantum impurity models, they may also be used to calculate thermodynamic properties. In this paper, we assess the FDM approach to thermodynamic properties by applying it to the Anderson impurity model. We compare the results for the susceptibility and specific heat to both the conventional approach within NRG and to exact Bethe ansatz results. We also point out a subtlety in the calculation of the susceptibility (in a uniform field) within the FDM approach. Finally, we show numerically that for the Anderson model, the susceptibilities in response to a local and a uniform magnetic field coincide in the wide-band limit, in accordance with the Clogston-Anderson compensation theorem.

  10. In Situ Nanocalorimetric Investigations of Plasma Assisted Deposited Poly(ethylene oxide)-like Films by Specific Heat Spectroscopy.

    Science.gov (United States)

    Madkou, Sherif; Melnichu, Iurii; Choukourov, Andrei; Krakovsky, Ivan; Biederman, Hynek; Schönhals, Andreas

    2016-04-28

    In recent years, highly cross-linked plasma polymers have started to unveil their potential in numerous biomedical applications in thin-film form. However, conventional diagnostic methods often fail due to their diverse molecular dynamics conformations. Here, glassy dynamics and the melting transition of thin PEO-like plasma assisted deposited (ppPEO) films (thickness 100 nm) were in situ studied by a combination of specific heat spectroscopy, utilizing a pJ/K sensitive ac-calorimeter chip, and composition analytical techniques. Different cross-linking densities were obtained by different plasma powers during the deposition of the films. Glassy dynamics were observed for all values of the plasma power. It was found that the glassy dynamics slows down with increasing the plasma power. Moreover, the underlying relaxation time spectra broaden indicating that the molecular motions become more heterogeneous with increasing plasma power. In a second set of the experiment, the melting behavior of the ppPEO films was studied. The melting temperature of ppPEO was found to decrease with increasing plasma power. This was explained by a decrease of the order in the crystals due to formation of chemical defects during the plasma process.

  11. Specific heat and entropy change at the first order phase transition of La(Fe-Mn-Si)13-H compounds

    Science.gov (United States)

    Basso, Vittorio; Küpferling, Michaela; Curcio, Carmen; Bennati, Cecilia; Barzca, Alexander; Katter, Matthias; Bratko, Milan; Lovell, Edmund; Turcaud, Jeremy; Cohen, Lesley F.

    2015-08-01

    In this paper, we present the results of an experimental investigation on the magnetocaloric properties of hydrogenated La(Fe-Mn-Si)13-H with Mn substituting Fe to finely tune the transition temperature. We measured the specific heat under magnetic field cp(H, T) and the magnetic field induced isothermal entropy change Δs(H, T) of a series of compounds by direct Peltier calorimetry. Results show that increasing Mn from 0.06 to 0.46 reduces the transition temperature from 339 K to 270 K whilst the total entropy change due to a 1.5 T field is depressed from 18.7 J kg-1 K-1 to 10.2 J kg-1 K-1 and the thermal hysteresis similarly is reduced from 1.5 K to zero. In the paper, we interpret the results in terms of a magnetic phase transition changing from the first to the second order with increasing Mn content, and we discuss the value of the results for magnetic cooling applications.

  12. Alternating current calorimeter for specific heat capacity measurements at temperatures below 10 K and pressures up to 10 GPa.

    Science.gov (United States)

    Umeo, Kazunori

    2016-06-01

    A developed alternating current calorimeter for measuring the absolute value of specific heat C of a very small sample under a pressure up to 10 GPa and low temperature below 10 K is described. A Bridgman anvil cell made of tungsten carbide with a top diameter of 3 mm is used. A hollow at the top prevents expansion of the sample space over the anvil top. Two chip resistors, which act as a thermometer and a heater, are mounted on the outer part of a copper-beryllium gasket with a frying pan-like shape. Thus, the thermometer is not pressurized. In order to isolate the gasket from the anvil thermally, diamond powder with a grain size of 0.25 μm is placed on the anvil top. Two jumps of C at the superconducting transitions of Pb (3.3 mg) and In (5.0 mg) are observed under various pressures up to 9 GPa, as clearly as those at the ambient pressure.

  13. Exact Solution to the Extended Zwanzig Model for Quasi-Sigmoidal Chemically Induced Denaturation Profiles: Specific Heat and Configurational Entropy

    Directory of Open Access Journals (Sweden)

    G. E. Aguilar-Pineda

    2014-01-01

    Full Text Available Temperature and chemically induced denaturation comprise two of the most characteristic mechanisms to achieve the passage from the native state N to any of the unstructured states Dj in the denatured ensemble in proteins and peptides. In this work we present a full analytical solution for the configurational partition function qs of a homopolymer chain poly-X in the extended Zwanzig model (EZM for a quasisigmoidal denaturation profile. This solution is built up from an EZM exact solution in the case where the fraction α of native contacts follows exact linear dependence on denaturant’s concentration ζ; thus an analytical solution for L in the case of an exact linear denaturation profile is also provided. A recently established connection between the number ν of potential nonnative conformations per residue and temperature-independent helical propensity ω complements the model in order to identify specific proteinogenic poly-X chains, where X represents any of the twenty naturally occurring aminoacid residues. From qs, equilibrium thermodynamic potentials like entropy and average internal energy 〈E〉 and thermodynamic susceptibilities like specific heat C are calculated for poly-valine (poly-V and poly-alanine (poly-A chains. The influence of the rate at which native contacts denature as function of ζ on thermodynamic stability is also discussed.

  14. Studies of Nucleation and Growth, Specific Heat and Viscosity of Undercooled Melts of Quasicrystal and Polytetrahedral-Phase Forming Alloys

    Science.gov (United States)

    Kelton, K. F.; Gangopadhyay, Anup K.; Lee, G. W.; Hyers, Robert W.; Rathz, T. J.; Robinson, Michael B.; Rogers, Jan R.

    2003-01-01

    From extensive ground based work on the phase diagram and undercooling studies of Ti-Zr-Ni alloys, have clearly identified the composition of three different phases with progressively increasing polytetrahedral order such as, (Ti/Zr), the C14 Laves phase, and the i-phase, that nucleate directly from the undercooled liquid. The reduced undercooling decreases progressively with increasing polytetrahedral order in the solid, supporting Frank s hypothesis. A new facility for direct measurements of the structures and phase transitions in undercooled liquids (BESL) was developed and has provided direct proof of the primary nucleation of a metastable icosahedral phase in some Ti-Zr-Ni alloys. The first measurements of specific heat and viscosity in the undercooled liquid of this alloy system have been completed. Other than the importance of thermo-physical properties for modeling nucleation and growth processes in these materials, these studies have also revealed some interesting new results (such as a maximum of C(sup q, sub p) in the undercooled state). These ground-based results have clearly established the necessary background and the need for conducting benchmark nucleation experiments at the ISS on this alloy system.

  15. Structure, magnetism, specific heat, and dielectric properties of Eu{sub 2}Ta{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Kolodiazhnyi, T., E-mail: kolodiazhnyi.taras@nims.go.jp; Sakurai, H.; Matsushita, Y. [National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan)

    2014-11-17

    Polycrystalline Eu{sub 2}Ta{sub 2}O{sub 7} containing layered perovskite slabs was prepared and analyzed. Eu{sub 2}Ta{sub 2}O{sub 7} crystallizes in the orthorhombic centrosymmetric Cmcm space group (with unit cell: a = 3.95156(9), b = 27.0775(6), and c = 5.68279(13) Å) isomorphous with high-temperature Sr{sub 2}Ta{sub 2}O{sub 7}. Dielectric measurements reveal that, in contrast to Sr{sub 2}Ta{sub 2}O{sub 7} which is ferroelectric below 166 K, Eu{sub 2}Ta{sub 2}O{sub 7} remains paraelectric down to at least 0.45 K and shows no magneto-dielectric coupling. Magnetic data in the 2–400 K range indicate an antiferromagnetic phase transition with a sharp susceptibility peak at 2.71(5) K. Further analysis using specific heat measurements reveals that the second magnetic phase transition occurs at 1.10(5) K and dominates the spin entropy of the Eu{sup 2+} 4f{sup 7} ions. The possible origin of the two successive magnetic phase transitions in Eu{sub 2}Ta{sub 2}O{sub 7} requires further studies.

  16. Specific heat of the dilute antiferromagnetic system Fe{sub x}Zn{sub 1-x}F{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, L L L; Araujo, L R S; Machado, F L A; Montenegro, F C; Rezende, S M, E-mail: flam@df.ufpe.b [Departamento de Fisica, Universidade Federal de Pernambuco, Cidade Universitaria, 50670-901, Recife, Pernambuco (Brazil)

    2010-01-01

    The specific heat (c{sub p}) of the dilute antiferromagnet Fe{sub x}Zn{sub 1-x}F{sub 2} has been measured in absence of external magnetic fields for x = 0, 0.26, 0.31, 0.34, 0.36, 0.38, 0.41, 0.45, 0.56, 0.88, 0.97, and 1.0. For x > 0.45, a sharp peak associated to the antiferromagnetic (AF) phase transition at T{sub N}(x) is the only observed feature. For 0.31 {<=} x {<=} 0.41, this peak becomes smaller with decreasing x and a rounded bump appears at higher temperatures T. Closer to the percolation concentration (x{sub p} = 0.24), the peak characteristic of the AF phase transition disappears and the rounded bump becomes the only observed feature. The low-T c{sub p} behavior confirms a crossover from AF long range order at large x to a spin glass behavior close to x{sub p}. At intermediate x, the low-T joint signature of both phenomena indicates a coexistence of AF order and a cluster-glass phase. The x-dependence of the Neel temperature was accounted for using a simple phenomenological model.

  17. Application of semi-analytical mathematical approach for thermal analysis of convective-radiative fin with variable specific heat

    Directory of Open Access Journals (Sweden)

    J. Dutta

    2016-09-01

    Full Text Available This research paper depicts the application of highly powerful and accurate semi-analytical methods, Differential transformation method (DTM to portray the non linear temperature distribution of convective-radiative fin with variable specific heat. With the help of DTM, the nonlinear terms appeared in governing equations are reduced to recurrence relation with non-dimensional terms. A longitudinal fin of constant rectangular profile through which air flows in transverse direction at ambient temperature has been considered for present analysis. The governing differential equation and corresponding boundary conditions are decided based on the heat transfer in longitudinal fin. The governing equation is non-dimensionalised for successful application of DTM with generalised terms. The results of temperature distribution in fin have been obtained for a range of values of several parameters of DTM. The results have indicated that DTM is efficient and convenient tool for analysing nonlinear differential equations of several environments. Present results have been compared and analysed with other analytical methods available in literature.

  18. Flexible Capitalism

    DEFF Research Database (Denmark)

    Approaching “work” as at heart a practice of exchange, this volume explores sociality in work environments marked by the kind of structural changes that have come to define contemporary “flexible” capitalism. It introduces anthropological exchange theory to a wider readership, and shows how...... the perspective offers new ways to enquire about the flexible capitalism’s social dimensions. The essays contribute to a trans-disciplinary scholarship on contemporary economic practice and change by documenting how, across diverse settings, “gift-like” socialities proliferate, and even sustain the intensified...

  19. Specific heat measurements of Ba0.68 K0.32 Fe2 As2 single crystals: evidence for a multiband strong-coupling superconducting state

    NARCIS (Netherlands)

    Popovich, P.; Boris, A.V.; Dolgov, O.V.; Golubov, A.A.; Sun, S.L.; Lin, C.T.; Kremer, R.K.; Keimer, B.

    2010-01-01

    The specific heat of high-purity Ba0.68 K0.32 Fe2 As2 single crystals with the highest reported superconducting Tc =38.5  K was studied. The electronic specific heat Cp below Tc shows two gap features, with Δ1≈11  meV and Δ2≈3.5  meV obtained from an α-model analysis. The reduced gap value, 2Δmax

  20. A study of the disorder in heavily doped Ba1-xLaxF2+x by neutron scattering, ionic conductivity and specific heat measurements

    DEFF Research Database (Denmark)

    Andersen, Niels Hessel; Clausen, Kurt Nørgaard; Kjems, Jørgen;

    1986-01-01

    The ionic disorder in single crystals of the fluorite-type solid solutions Ba1-xLaxF2+x (with x=0.209 and x=0.492) has been studied in the temperature range from room temperature to 800 degrees C by diffuse neutron scattering, ionic conductivity, and specific heat measurements. From the diffuse...... coincide at approximately 650 degrees C. At this temperature no clear anomaly is observed in the specific heat. Based on these findings the authors propose a conduction mechanisms where F- ions are moving through the lattice by means of rearrangements of the 222 clusters....

  1. Specific heat and heat conductivity of BaTiO{sub 3} polycrystalline films in the thickness range 20-1100 nm

    Energy Technology Data Exchange (ETDEWEB)

    Strukov, B A [Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Davitadze, S T [Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Kravchun, S N [Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Taraskin, S A [Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Goltzman, M [Ioffe Physico-Technical Institution RAS, St Petersburg 194021 (Russian Federation); Lemanov, V V [Ioffe Physico-Technical Institution RAS, St Petersburg 194021 (Russian Federation); Shulman, S G [Ioffe Physico-Technical Institution RAS, St Petersburg 194021 (Russian Federation)

    2003-07-02

    Thermal properties - specific heat and heat conductivity coefficient - of polycrystalline BaTiO{sub 3} films on massive substrates were studied as a function of the temperature and the film thickness by the ac-hot probe method. The anomalies of specific heat with the film thickness decreasing from 1100 to 20 nm revealed the reduction of T{sub c} and excess entropy of the ferroelectric phase transition which becomes diffused. The critical thickness of the film at which T{sub c} = 0 has been estimated as 2.5 nm.

  2. Magnetic and specific heat properties of a new Gd-doped ZnCr{sub 2}Se{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Maciążek, E., E-mail: ewa.maciazek@us.edu.pl [University of Silesia, Institute of Chemistry, Szkolna 9, 40-006 Katowice (Poland); Karolus, M.; Kubisztal, M. [University of Silesia, Institute of Material Science, 75 Pułku Piechoty 1A, 41-500 Chorzów (Poland); Jendrzejewska, I.; Sitko, R. [University of Silesia, Institute of Chemistry, Szkolna 9, 40-006 Katowice (Poland); Groń, T.; Ślebarski, A.; Fijałkowski, M. [University of Silesia, Institute of Physics, Uniwersytecka 4, 40-006 Katowice (Poland)

    2015-11-15

    The series of chromium selenides Gd-doped ZnCr{sub 2}Se{sub 4} (from 0.07 Gd to 0.21 Gd) was synthesized in polycrystalline form using ceramic method from stoichiometric amounts of elements. The phase and structure determination by X-ray diffraction showed the main cubic normal spinel structure and traces amount of phases ZnSe and the selenium. Magnetic measurements showed an antiferromagnetic order for all compositions with the Neél temperature T{sub N}∼22 K, a change of slope at the first critical field H{sub c1} of about 11.5 kOe for T = 2 K characteristic for a metamagnetic transition, a breakdown of the helical spin arrangement at the second critical field H{sub c2} of about 60 kOe for T = 2 K, and splitting of the zero-field-cooling and field-cooling susceptibilities below the freezing temperature T{sub f} = 7.3 K suggesting magnetic frustration. Specific heat measurements exhibited first-order anomalies at T{sub N}. These effects are interpreted in terms of the superexchange integrals for the first two coordination spheres including structural defects and non-stoichiometry. - Highlights: • ZnCr{sub 2}Se{sub 4} spinel compounds doped by Gd were successfully synthesized. • All compounds show AFM order below T{sub N}∼22 K and spin-glass behaviour below 7.3 K. • Gd-substitution weakens the FM magnetic interactions, causing the magnetic frustration.

  3. Effects of anisotropy and magnetic fields on the specific heat of a quasi-two-dimensional Boltzmann gas in an elliptical parabolic quantum dot

    Institute of Scientific and Technical Information of China (English)

    Zhai Zhi-Yuan; Li Yu-Qi; Pan Xiao-Yin

    2012-01-01

    We investigate the effects due to anisotropy and magnetic field interaction for a quasi-two-dimensional Boltzmann gas in an elliptical parabolic quantum dot.The specific heat is studied with varying temperature,anisotropy,and magnetic field strength.The cases without and with the inclusion of the spin Zeeman interaction are considered.

  4. Specific heat of rabbit blood measured by cooling method%冷却法测定家兔血液的比热

    Institute of Scientific and Technical Information of China (English)

    贾斌; 李建军; 温光楠

    2001-01-01

    目的 家兔血液比热是热稀释法测量家兔心输出量的重要修正系数.方法 根据牛顿冷却定律,采用同一容器盛装兔血或水,若两者温度与体积都基本相同,则水与兔血的散热规律基本相同,水的比热已知,便可求出兔血的比热;又利用同一系统测得标准100g·L-1NaCl溶液的比热值,求得测量系统误差,对所测兔血比热进行修正.结果 对测得的多组兔血比热数据进行合理筛选后,得到新鲜兔血测量值:0.886±0.022,经误差修正得到家兔血液比热:0.849±0.022;陈旧兔血测量值:1.020±0.021,经误差修正后:0.997±0.021.结论 冷却法测定家兔血液比热方法可靠,数据处理合理,结果可信.%AIM To determine specific heat of rabbit blood for calculatingcardiac output of rabbits by thermodilution. METHODS According to Newton's law of cooling, specific heat of rabbit blood was measured from that of water, by comparing the speed of temperature change of them measured respectively in the same system. The measured specific heat of rabbit blood was corrected with systematic error of specific heat of 100 g·L-1 NaCl solution measured in the same system. RESULTS Specific heat of fresh whole blood of rabbits was 0.886±0.022; After correction, 0.849±0.022; Blood after being stored, the specific heat changed, 1.020±0.021,and 0.997±0.021 after correction. CONCLUSION Corrected specific heat value of fresh blood is more reasonable, and the calculated cardiac output might be more accurate.

  5. The Effect of Moisture Content and Temperature on the Specific Heat Capacity of Nut and Kernel of Two Iranian Pistachio Varieties

    Directory of Open Access Journals (Sweden)

    A.R Salari Kia

    2014-04-01

    Full Text Available Pistachio has a special ranking among Iranian agricultural products. Iran is known as the largest producer and exporter of pistachio in the world. Agricultural products are imposed under different thermal treatments during storage and processing. Designing all these processes requires thermal parameters of the products such as specific heat capacity. Regarding the importance of pistachio processing as an exportable product, in this study the specific heat capacity of nut and kernel of two varieties of Iranian pistachio (Kalle-Ghochi and Badami were investigated at four levels of moisture content (initial moisture content (5%, 15%, 25% and 40% w.b. and three levels of temperature (40, 50 and 60°C. In both varieties, the differences between the data were significant at the 1% of probability; however, the effect of moisture content was greater than that of temperature. The results indicated that the specific heat capacity of both nuts and kernels increase logarithmically with increase of moisture content and also increase linearly with increase of temperature. This parameter has altered for nut and kernel of Kalle-Ghochi and Badami varieties within the range of 1.039-2.936 kJ kg-1 K-1, 1.236-3.320 kJ kg-1 K-1, 0.887-2.773 kJ kg-1 K-1 and 0.811-2.914 kJ kg-1 K-1, respectively. Moreover, for any given level of temperature, the specific heat capacity of kernels was higher than that of nuts. Finally, regression models with high R2 values were developed to predict the specific heat capacity of pistachio varieties as a function of moisture content and temperature

  6. 温度对发射药比热容影响规律研究%Temperature Dependence of the Specific Heat Capacity of Propellant

    Institute of Scientific and Technical Information of China (English)

    胡哲; 江劲勇; 路桂娥; 葛强; 王韶光; 贾昊楠

    2015-01-01

    目的 确定发射药比热容参数.方法 选用发射药9/7单基药、SF-3和GATo推进剂为研究对象,利用热重分析仪研究发射药的热分解特性,确定实验温度区间.利用差示扫描量热仪采用动态温度调制法对温度区间内发射药比热容进行测量,对发射药比热容变化规律进行分析,并计算热力学函数.结果 发射药的比热容随温度升高而逐渐变大.结论 在进行发射药热模拟计算时,从安全角度出发,应该使用常温下发射药比热容.%Objective To determine the specific heat capacity parameter of propellant. Methods 9/7 single-base propellant,SF-3 and GATo were selected as the research objects. The thermal decomposition characteristics of propellant were studied using thermogravimetric analyzer, and the experimental temperature zone of propellant was determined. The specific heat capacity of propellant in the temperature range was measured by the method of dynamic temperature modulation using DSC, and the changing law was analyzed for the specific heat capacity of propellant. Thermodynamic functions of propellant were calculated. Results The results showed that the specific heat capacity gradually increased with the rising temperature. Conclusion In the process of thermal simulation of propellant, from the safety point of view, the specific heat capacity of propellant at room temperature should be used.

  7. Flexible Electronics Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Flexible Electronics Research Facility designs, synthesizes, tests, and fabricates materials and devices compatible with flexible substrates for Army information...

  8. Compositional Dependence of Electronic Specific Heat in AlCuCo Decagonal Quasicrystals: Evidence for the Hume-Rothery Mechanism of Phase Formation

    Institute of Scientific and Technical Information of China (English)

    FAN Zhen-Jun; JING Xiu-Nian; ZHANG Dian-Lin

    2005-01-01

    @@ There is no consensus whether the electron density of states of decagonal quasicrystals has a pseudogap at the Fermi energy similar to that of the icosahedron phase. We answer this question by measuring the electronic specific heat coefficient of AlCuCo decagonal single-quasicrystals over a wide range of composition. While the average valence electron number per atom, e/a, for all the resultant samples changes only within 1.5%, from ~ 1.92 to less than 1.95. The specific heat coefficient decreases by 15% with the increasing e/a. The large change and the negative slope give strong evidence for Hume-Rothery mechanism of the decagonal phase.

  9. The low temperature specific heat and electrical transport, magnetic properties of Pr0.65Ca0.35MnO3

    Science.gov (United States)

    Han, Zhiyong

    2017-02-01

    The magnetic properties, electrical transport properties, and low temperature specific heat of polycrystalline perovskite manganese oxide Pr0.65Ca0.35MnO3 have been investigated experimentally. It is found that there exists cluster glass state in the sample at low temperature besides the antiferromagnetic insulating state. With the increase of magnetic field, antiferromagnetic insulating state converts to ferromagnetic metal state and the Debye temperature decreases gradually. In addition, the low temperature electron specific heat in zero magnetic field is obviously larger than that of ordinary rare-earth manganites oxide and this phenomenon is related to the itinerant electrons in ferromagnetic cluster state and the disorder in Pr0.65Ca0.35MnO3.

  10. Non-isothermal Decomposition Kinetics,Specific Heat Capacity and Adiabatic Time-to-explosion of 1-Amino-1-hydrazino-2,2-dinitroethylene (AHDNE)

    Institute of Scientific and Technical Information of China (English)

    XU,Kangzhen; ZHAO,Fengqi; SONG,Jirong; CHANG,Chunran; LI,Meng; WANG,Yaoyu; HU,Rongzu

    2009-01-01

    The thermal behavior and non-isothermal kinetics of the exothermic decomposition reaction of 1-amino-1-hydrazino-2,2-dinitroethylene (AHDNE) were studied with DSC and TG/DTG methods.The kinetic equation obtained is dα/dT=1019.29(1-α)exp(-1.88×104/T)/β.The critical temperature of thermal explosion is 98.16 ℃.The specific heat capacity of AHDNE was determined,and the standard molar specific heat capacity is 211.86 J·mol-1·K-1 at 298.15 K.The adiabatic time-to-explosion of AHDNE was also calculated to be 59.21 s.AHDNE is unstable and has much lower thermostability than 1,1-diamino-2,2-dinitroethylene (FOX-7).

  11. Observation of the crossover from two-gap to single-gap superconductivity through specific heat measurements in neutron-irradiated MgB2.

    Science.gov (United States)

    Putti, M; Affronte, M; Ferdeghini, C; Manfrinetti, P; Tarantini, C; Lehmann, E

    2006-02-24

    We report specific heat measurements on neutron-irradiated MgB2 samples, for which the critical temperature is lowered to 8.7 K, but the superconducting transition remains extremely sharp, indicative of a defect structure extremely homogeneous. Our results evidence the presence of two superconducting gaps in the temperature range above 21 K, while single-gap superconductivity is well established as a bulk property, not associated with local disorder fluctuations, when Tc decreases to 11 K.

  12. Low-temperature specific heat and resistance for the heavy-electron metals CeCu6-xMx (M=Ni,Zn)

    Institute of Scientific and Technical Information of China (English)

    Jiang Li-Xia; Meng Ji-Bao; Xia Zhao-Yang; Chen Zhao-Jia; Luo Jian-Lin; Wang Nan-Lin

    2004-01-01

    The specific heat and resistance of CeCu6-xMx (M=Ni,Zn) have been studied in the concentration range where they still retain the orthorhombic structure. The coefficient c of-lnT term in resistance R = R0+bT-clnT, as well as the γ, have been found to vary in opposite directions with increasing x for Ni and Zn substitutions. The physical mechanism is discussed.

  13. Ratio-Based Gradual Aggregation of Data

    DEFF Research Database (Denmark)

    Iftikhar, Nadeem

    2012-01-01

    cause data management and data storage issues. However, non-flexible and ineffective means of data aggregation not only reduce performance of database queries but also lead to erroneous reporting. This paper presents flexible and effective ratio-based methods for gradual data aggregation in databases...

  14. Balance and flexibility.

    Science.gov (United States)

    2003-12-01

    The 'work-life balance' and flexible working are currently key buzz terms in the NHS. Those looking for more information on these topics should visit Flexibility at www.flexibility.co.uk for a host of resources designed to support new ways of working, including information on flexible workers and flexible rostering, the legal balancing act for work-life balance and home working.

  15. Structure, magnetic susceptibility, and specific heat of the spin-orbital-liquid candidate FeS c2S4 : Influence of Fe off-stoichiometry

    Science.gov (United States)

    Tsurkan, V.; Prodan, L.; Felea, V.; Filippova, I.; Kravtsov, V.; Günther, A.; Widmann, S.; Krug von Nidda, H.-A.; Deisenhofer, J.; Loidl, A.

    2017-08-01

    We report structure, susceptibility, and specific heat studies of stoichiometric and off-stoichiometric poly- and single crystals of the A -site spinel compound FeS c2S4 . In stoichiometric samples, no long-range magnetic order is found down to 1.8 K. The magnetic susceptibility of these samples is field independent in the temperature range 10-400 K and does not show irreversible effects at low temperatures. In contrast, the magnetic susceptibility of samples with iron excess shows substantial field dependence at high temperatures and manifests a pronounced magnetic irreversibility at low temperatures with a difference between zero-field cooled (ZFC) and field cooled (FC) susceptibilities and a maximum at 10 K, reminiscent of a magnetic transition. Single-crystal x-ray diffraction of the stoichiometric samples revealed a single phase spinel structure without site inversion. In single crystalline samples with Fe excess, in addition to the main spinel phase, a second ordered single-crystal phase was detected with the diffraction pattern of a vacancy-ordered superstructure of iron sulfide, close to the 5C polytype F e9S10 . Specific heat studies reveal a broad anomaly, which evolves below 20 K in both stoichiometric and off-stoichiometric crystals. We show that the low-temperature specific heat can be well described by considering the low-lying spin-orbital electronic levels of F e2 + ions. Our results demonstrate significant influence of excess Fe ions on intrinsic magnetic behavior of FeS c2S4 and provide support for the spin-orbital liquid scenario proposed in earlier studies for the stoichiometric compound.

  16. The specific heat of the electron-doped La-1038 compound (Ca0.85La0.15)10(FeAs)10(Pt3As8).

    Science.gov (United States)

    Kim, J S; Stürzer, T; Johrendt, D; Stewart, G R

    2013-04-01

    The specific heat of polycrystalline (Ca0.85La0.15)10(FeAs)10(Pt3As8), an electron-doped iron-based superconductor (T(c)(onset) = 34.6 K) with Ca/La ions and Pt3As8 separating the FeAs layers, was measured between 0.4 and 48 K.This compound has been recently reported to represent an electron-doped variant of the non-superconducting 10-3-8 phase, featuring a superconducting transition in the range of that of the 10-4-8 phase. This family of compounds is unique among the iron pnictide superconductors discovered to date due to the second metal pnictide layer, Pt3As8, present in the structure competing with the familiar FeAs layer for the electron from the Ca/La. This superconductor is further unusual in that it has a rather low crystalline symmetry (triclinic) for such a high superconducting transition temperature. The specific heat γ is found to be approximately 26 mJ/(Ca/La mol)K(2), comparable to 122 iron-based superconductors electron-doped on the Fe sites and a factor of two smaller than 122 compounds hole-doped on the cation site, e.g., Ba(1-x)K(x)Fe2As2. The present work also investigates the discontinuity in the specific heat at T(c), ΔC, to compare with the global trend, established by Bud'ko, Ni and Canfield (BNC), of ΔC/T(c) versus T(c) found for essentially all iron-based superconductors. The result is a value lower than the BNC trend by a factor of ten, consistent with a severely broadened superconducting transition.

  17. Apparent specific heat of a spin glass ( Au Fe 6 at %) in presence of a remanent magnetization and associated energy and magnetization relaxations

    Science.gov (United States)

    Berton, A.; Chaussy, J.; Odin, J.; Peyrard, J.; Prejean, J. J.; Souletie, J.

    1981-01-01

    We present measurements of the relaxations of the remanent magnetization and of the energy flux on the same samples of Au Fe spin glass (4 at % and 6 at %) at several temperatures below the temperature T G of the susceptibility cusp. The observed relaxations can be expressed in terms of the unique composite variable T ℓnt/τ which implies the existence of thermally activated asymetrical double well potentials. A consequency of this observation is the existence of a time and temperature contribution to the specific heat which is investigated directly and compared with expectation.

  18. Self consistently calibrated photopyroelectric calorimeter for the high resolution simultaneous absolute measurement of the specific heat and of the thermal conductivity

    Directory of Open Access Journals (Sweden)

    U. Zammit

    2012-03-01

    Full Text Available High temperature resolution study of the specific heat and of the thermal conductivity over the smecticA-nematic and nematic-isotropic phase transitions in octylcynobephenyl liquid crystal using a new photopyroelectric calorimetry configuration are reported, where, unlike previously adopted ones, no calibration is required other than the procedure used during the actual measurement. This makes photopyroelectric calorimetry suitable for “absolute” measurements of the thermal parameters like most other existing conventional calorimetric techniques where, however, the thermal conductivity cannot be measured.

  19. High-resolution specific-heat data of YBa{sub 2}Cu{sub 3}O{sub x} up to 400 K

    Energy Technology Data Exchange (ETDEWEB)

    Meingast, C.; Wolf, T.; Pankoke, V.; Heid, R.; Bohnen, K.P. [Forschungszentrum Karlsruhe, Inst. fuer Festkoerperphysik (Germany); Inaba, A. [Research Center for Molecular Thermodynamics, Graduate School of Science, Osaka Univ., Toyonaka (Japan)

    2007-07-01

    Very accurate (0.1 percent) adiabatic specific heat measurements up to 400 K have been made on YBa{sub 2}Cu{sub 3}O{sub x} samples with oxygen contents x=6.7, 6.9 and 7.0. The oxygen deficient samples clearly show an anomaly due to the oxygen ordering above room temperature. In order to analyze this oxygen-ordering contribution, as well as the electronic contribution, in detail, the phonon contribution, obtained by first-principles electronic structure calculations, was subtracted from the data. This subtraction works quite well, which demonstrates the quality of both the measured and calculated heat capacities. (orig.)

  20. De Haas{endash}van Alphen effect, magnetic transitions, and specific heat in the heavy-fermion system UCd{sub 11}

    Energy Technology Data Exchange (ETDEWEB)

    Cornelius, A.L.; Arko, A.J.; Sarrao, J.L.; Harrison, N. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1999-06-01

    We have used high pulsed magnetic fields to 50 T to observe de Haas{endash}van Alphen oscillations in the heavy fermion antiferromagnet UCd{sub 11}, which has a stongly enhanced value of the electronic specific-heat coefficient ({gamma}=803 mJ/molthinspK{sup 2}). The low-temperature magnetization shows the existence of two magnetic phase transitions. The presence of quantum oscillations above the first transition indicates that UCd{sub 11} has a coherent Fermi liquid, although there is little or no change in the Fermi-surface topology on passing through the second transition. {copyright} {ital 1999} {ital The American Physical Society}

  1. Specific heat measurements on amorphous and nanocrystalline Al{sub 88}Y{sub 5}Ni{sub 5}Co{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Blazquez, J.S.; Millan, M.; Conde, C.F. [Dpto. Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, 41080, Sevilla (Spain); Conde, A. [Dpto. Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, 41080, Sevilla (Spain)], E-mail: conde@us.es; Latuch, J.; Kulik, T. [Faculty of Materials Science and Engineering, Warsaw University of Technology, ul. Woloska 141, 02-507, Warsaw (Poland)

    2009-06-10

    Specific heat at constant pressure, C{sub P}, was measured on amorphous and nanocrystalline Al{sub 88}Y{sub 5}Ni{sub 5}Co{sub 2} alloys from differential scanning calorimetry experiments. Linear behavior of C{sub P} versus temperature from 323 to 423 K is explained by conduction electrons contribution and dilatation correction factor. Results indicate that the Fermi energy increases as nanocrystallization progresses, although the estimated values are clearly lower than those found for crystalline Al.

  2. The magnetic susceptibility, specific heat and dielectric constant of hexagonal YMnO3, LuMnO3 and ScMnO3

    Science.gov (United States)

    Tomuta, D. G.; Ramakrishnan, S.; Nieuwenhuys, G. J.; Mydosh, J. A.

    2001-05-01

    We report the magnetic susceptibility, specific heat and dielectric constant for high-purity polycrystalline samples of three hexagonal manganites: YMnO3, LuMnO3 and ScMnO3. These materials can exhibit a ferroelectric transition at very high temperatures (TFE>700 K). At lower temperatures there is magnetic ordering of the frustrated Mn3+ spins (S = 2) on a triangular Mn lattice (YMnO3: TN = 71 K LuMnO3: TN = 90 K and ScMnO3: TN = 130 K). The transition is characterized by a sharp kink in the magnetic susceptibility at TN below which it continues to increase due to the frustration on the triangular lattice. The specific heat shows one clear continuous phase transition at TN, which is independent of external magnetic field up to 9 T with an entropy content as expected for Mn3+ ions. The temperature-dependent dielectric constant displays a distinct anomaly at TN.

  3. Specific heats and thermodynamic critical fields in Zn-doped YBa2Cu3O(7-x) according to an induced-pairing model

    Science.gov (United States)

    Eagles, D. M.

    1993-01-01

    Electronic specific heats and thermodynamic critical fields are calculated in a mean-field version of an induced-pairing model for superconductivity, and compared with results of Loram et al. (1990) on YBa2(Cu(1-y)Zn(y))3O(7-x). This model involves induction of pairing of holes in a wideband by strongly bound electronlike pairs. It is assumed that the planar hole concentration for no Zn addition is close to, but slightly higher than, that for the maximum Tc, and that it increases by 0.015 per planar Cu ion for each increase of y by 0.01. Parameters of the model are taken to be the same as in a previous publication in which energy gaps were discussed, except that an effective hybridization parameter is adjusted for each Zn concentration to give agreement with the observed Tc. Results are presented for y = 0.0, 0.01, and 0.03. The agreement with experiment is good for thermodynamic critical fields, and is fair for specific heats. For specimens with larger y, with relatively low T(c)s, it is argued that the model should be supplemented to include effects of a BCS-type interaction amongst the wideband carriers.

  4. Field-dependent specific heat study of the spin-Peierls transition in TTF- AuS4C4(CF3)4 a)

    Science.gov (United States)

    Northby, J. A.; Greidanus, F. J. A. M.; Huiskamp, W. J.; de Jongh, L. J.; Jacobs, I. S.; Interrante, L. V.

    1982-11-01

    The compound TTF-AuS4C4(CF3)4 is one of the very few existing examples of the spin-Peierls transition, in which a system of 1D antiferromagnetic chains dimerizes spontaneously as a consequence of magnetoelastic coupling with the surrounding lattice. We have studied the spectific heat anomaly accompanying the SP transition for this compound as a function of an applied magnetic field. Our H=0 data differ considerably from those obtained earlier by Wei et al., and in fact remove the discrepancy found by them between their results for TTF-AuS4C4(CF3)4 and the isomorphous TTF-CuS4C4(CF3)4. The differences between the two experiments are probably due to thermal relaxation effects. The combination of the specific heat data now available confirms the conclusion drawn from our previous field-dependent differential susceptibility studies on the Au compound, namely that the SP transition involves a considerable degree of short-range order, starting to develop below T=1.2 Tsp. We have been able to follow the specific heat anomaly for fields up to the multicritical point in the H-T phase diagram.

  5. Specific heats of LaAg, GdAg and Gd/sub 2/O/sub 3/ from 0. 5 to 22 K

    Energy Technology Data Exchange (ETDEWEB)

    Hill, R.W.; Cosier, J.; Hukin, D.A. (Oxford Univ. (UK). Clarendon Lab.)

    1983-05-30

    Specific heat measurements on monoclinic Gd/sub 2/O/sub 3/ show a cooperative peak at 3.8 K. The entropy associated with this peak is the full 2R ln 8 expected for the Gd/sup 3 +/ ions. Measurements on GdAg are affected by the presence of small inclusions of Gd/sub 2/O/sub 3/, but it proves possible to allow for these and to deduce values for the electronic specific heat constant ..gamma.. which is 11.4 +- 1.7 mJ mol/sup -1/ K/sup -2/. For LaAg, ..gamma..= 9.9 +- 0.2 mJ mol/sup -1/ K/sup -2/. The lattice heat capacities are analysed in terms of a Debye temperature which is found to vary strongly with temperature; the low-temperature limiting values are 208 K and 160 K for GdAg and LaAg respectively.

  6. Evaluation of specific heat peak and half-width for magnetic regenerative materials (RCuO) of 4K refrigerator; 4K reitoki yo jisei chikureizai kagobutsu (RCuO) no hinetsu piku to hannehaba no hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, S.; Nakane, H.; Hashimoto, T.; Sakagami, H. [Kogakuin Univ., Tokyo (Japan); Okamura, M. [Toshiba Corp., Tokyo (Japan); Numazawa, T. [National Research Inst. for Metals, Tokyo (Japan)

    1999-11-10

    For material selection in the multistory structure regeneration vessel of the GM refrigerating machine, we have the meaning in which specific heat peak value and half-value width of material are important. It announced specific heat peak-half-value width characteristics of rare earth magnetic material RSb. For the purpose of searching new regeneration material it improves a refrigerating capacity of refrigerating machine for 4K, it evaluated R{sub 2}BaCuO{sub 5} mainly noticed as superconducting material and R{sub 2}Cu{sub 2}O{sub 5} specific heat peak and half-value width as a magnetic material, which covered the specific heat characteristics of helium in low temperature. (NEDO)

  7. Phonon, magnon and electron contributions to low temperature specific heat in metallic state of La0.85Sr0.15MnO3 and Er0.8Y0.2MnO3 manganites

    Indian Academy of Sciences (India)

    Dinesh Varshney; Irfan Mansuri; E Khan

    2013-12-01

    The reported specific heat \\ () data of the perovskite manganites, La0.85Sr0.15MnO3 and Er0.8Y0.2MnO3, is theoretically investigated in the temperature domain 3 ≤ ≤ 50 K. Calculations of \\ () have been made within the three-component scheme: one is the fermion and the others are boson (phonon and magnon) contributions.Lattice specific heat is well estimated fromthe Debye temperature for La0.85Sr0.15MnO3 and Er0.8Y0.2MnO3 manganites. Fermion component as the electronic specific heat coefficient is deduced using the band structure calculations. Later on, following double-exchange mechanism the role of magnon is assessed towards specific heat and found that at much low temperature, specific heat shows almost T3/2 dependence on the temperature. The present investigation allows us to believe that electron correlations are essential to enhance the density of states over simple Fermi-liquid approximation in the metallic phase of both the manganite systems. The present numerical analysis of specific heat shows similar results as those revealed from experiments.

  8. Abstract: Magnetic solitons' contribution to the specific heat of (CH3)4NMnCl3 in an external magnetic field

    Science.gov (United States)

    Borsa, F.

    1982-03-01

    It has been shown theoretically that linear magnetic systems with planar anisotropy should display nonlinear excitations, i.e., sine-Gordon solitons upon application of a magnetic field perpendicular to the chain axis. Experimental evidence for ID magnetic solitons has been presented for TMMC from neutron scattering and NMR measurements.1 The classical statistical mechanics of this system predict a soliton contribution to the free energy and thus to the specific heat.2 In order to test experimentally the thermodynamic relevance of magnetic solitons, I performed measurements of specific heat in single crystal TMMC in an external magnetic field up to 10 Tesla, applied both perpendicular and parallel to the chain. The measurements were performed with an adiabatic calorimeter in the temperature range 1.5-15 °K. The results show an extra contribution for H⊥c not present for H∥c. This contribution displays a broad maximum which scales approximately as H/T in agreement with the theory. The maximum occurs just above the peak in the specific heat which is observed in correspondence to the three-dimensional transition temperature, and it can be clearly resolved only for H⩾5.0 T. The soliton energy obtained by fitting the experiments to the classical theory is Es = 2.0 H for H = 5.39 T and Es = 1.8 H for H = 10 T to be compared with the theoretical value of Es = gμBHS = 3.35 H and with the value obtained by neutron scattering at H = 3.2 T, i.e., Es = 2.6 H. The discrepancy between theory and experiment is discussed in terms of renormalization corrections and of a possible soliton instability occurring for fields between 3 and 5 T. a)Permanent address: Institut di Fisica, Universita di Pavia, 27100 Pavia, Italy. 1J. P. Boucher, L. P. Regnault, J. Rossad Miguod, J. P. Renard, J. Bouillot, and W. G. Stirling, J. Appl. Phys. 52, 1956 (1981). 2K. M. Leung, D. Hone, D. L. Mills, P. S. Riseborough, and S. E. Trullinger, Phys. Rev. B 21, 4017 (1980).

  9. Low-temperature specific heat and possible gap to magnetic excitations in the Heisenberg pyrochlore antiferromagnet Gd2Sn2O7

    Science.gov (United States)

    Del Maestro, Adrian; Gingras, Michel J. P.

    2007-08-01

    The Gd2Sn2O7 pyrochlore Heisenberg antiferromagnet displays a phase transition to a four sublattice Néel ordered state at a critical temperature Tc˜1K . The low-temperature state found via neutron scattering corresponds to that predicted by a classical model that considers nearest-neighbor antiferromagnetic exchange and long-range dipolar interactions. Despite the seemingly conventional nature of the ordered state, the specific heat Cv has been found to be described in the temperature range 350mK⩽T⩽800mK by an anomalous power law Cv˜T2 . A similar temperature dependence of Cv has also been reported for Gd2Ti2O7 , another pyrochlore Heisenberg material. Such behavior is to be contrasted with the typical T3 behavior expected for a three-dimensional antiferromagnet with conventional long-range order which is then generally accompanied by an exp(-Δ/T) behavior at lower temperature where anisotropy effects induce a gap Δ to collective spin excitations. Such anomalous T2 behavior in Cv has been argued to be correlated to an unusual energy dependence of the density of states which also seemingly manifests itself in low-temperature spin fluctuations found in muon spin relaxation experiments. In this paper, we report calculations of Cv that consider spin-wave-like excitations out of the Néel order observed in Gd2Sn2O7 via neutron scattering. We argue that the parametric Cv∝T2 does not reflect the true low-energy excitations of Gd2Sn2O7 . Rather, we find that the low-energy excitations of this material are antiferromagnetic magnons gapped by single-ion and dipolar anisotropy effects, and that the lowest temperature of 350mK considered in previous specific heat measurements accidentally happens to coincide with a crossover temperature below which magnons become thermally activated and Cv takes an exponential form. We argue that further specific heat measurements that extend down to at least 100mK are required in order to ascribe an unconventional description of

  10. Flexible spintronic devices on Kapton

    DEFF Research Database (Denmark)

    Bedoya-Pinto, Amilcar; Donolato, Marco; Gobbi, Marco;

    2014-01-01

    of bending angle (r = 5 mm) have been achieved without degradation of the device performance, reaching room-temperature tunneling magnetoresistance ratios of 12% in bended Co/Al2O3/NiFe junctions. In addition, a suitable route to pattern high-quality nanostructures directly on the polyimide surface......Magnetic tunnel junctions and nano-sized domain-wall conduits have been fabricated on the flexible substrate Kapton. Despite the delicate nature of tunneling barriers and zig-zag shaped nanowires, the devices show an outstanding integrity and robustness upon mechanical bending. High values...... is established. These results demonstrate that Kapton is a promising platform for low-cost, flexible spintronic applications involving tunnel junction elements and nanostructurization. ...

  11. Dip-Hump Temperature Dependence of Specific Heat and Effects of Pairing Fluctuations in the Weak-Coupling Side of a P-Wave Interacting Fermi Gas

    Science.gov (United States)

    Inotani, Daisuke; van Wyk, Pieter; Ohashi, Yoji

    2016-12-01

    We investigate the specific heat CV at constant volume in the normal state of a p-wave interacting Fermi gas. Including p-wave pairing fluctuations within the strong-coupling theory developed by Nozières and Schmitt-Rink, we show that, in the weak-coupling side, CV exhibits a dip-hump behavior as a function of the temperature. While the dip is associated with the pseudogap phenomenon near Tc, the hump structure is found to come from the suppression of Fermi quasiparticle scattering into a p-wave molecular state in the Fermi degenerate regime. Since the latter phenomenon does not occur in the ordinary s-wave interacting Fermi gas, it may be viewed as a characteristic phenomenon associated with a p-wave pairing interaction.

  12. DSC、MDSC测定物质比热容的比较%Comparison of differential scanning calorimetry and modulated differential scanning calorimetry in measurement of specific heat capacities

    Institute of Scientific and Technical Information of China (English)

    鲁红; 冯大春; 杨继佑

    2011-01-01

    实验用TA公司具有DSC、MDSC两种模式、具备先进Tzero技术的热流型DSCQ200热分析仪测定物质的比热容.对如何运用传统方法及调制方法测定物质的比热容进行了详细阐述;以氯化钾、苯甲酸、去离子水为测试样,对两种方法所得实验结果进行了分析比较.%The specific heat capacities of potassium choride, benzoic acid and deionized water samples were measured by DSCQ 200 tbermal analyzer in two different method (differential scanning calorimetry. DSC, and modulated differential scanning calorimetry. MDSC), The results obtained by two methods are compared.The questions in the application of DSC and MDSC are discussed in detail.

  13. Calculation of the paramagnetic susceptibility and specific heat in UGa{sub 2} and UPd{sub 2}Al{sub 3} from ab initio crystal field theory

    Energy Technology Data Exchange (ETDEWEB)

    Richter, M.; Forstreuter, J.; Koepernik, K.; Eschrig, H. [Univ. of Technol., Dresden (Germany). MPG Res. Group Electron Systems; Divis, M. [Univ. of Technol., Dresden (Germany). MPG Res. Group Electron Systems]|[Karlova Univ., Prague (Czechoslovakia). Dept. of Metal Physics; Steinbeck, L. [Univ. of Technol., Dresden (Germany). MPG Res. Group Electron Systems]|[York Univ. (United Kingdom). Dept. of Physics

    1997-02-01

    In the framework of the self-interaction corrected local density approximation, ab initio calculations have been carried out to obtain crystal field parameters for the paramagnetic state of UGa{sub 2} and UPd{sub 2}Al{sub 3}. In two sets of calculations localized 5f states with occupation two and three, respectively, have been assumed. Using these parameters and adjusted anisotropic molecular field constants, the paramagnetic susceptibility for both compounds and the Schottky contribution to the specific heat in UPd{sub 2}Al{sub 3} have been obtained by crystal field model calculations. Very good agreement between theoretical and experimental data is found for 5f{sup 2} occupation in UGa{sub 2}. For UPd{sub 2}Al{sub 3}, the 5f{sup 2} assumption yields qualitatively reasonable results as well, but it does not explain the T = 50 K maximum in the experimental data. (orig.).

  14. Calculation of the paramagnetic susceptibility and specific heat in UGa 2 and UPd 2Al 3 from ab initio crystal field theory

    Science.gov (United States)

    Richter, Manuel; Diviš, Martin; Forstreuter, Jörg; Koepernik, Klaus; Steinbeck, Lutz; Eschrig, Helmut

    1997-02-01

    In the framework of the self-interaction corrected local density approximation, ab initio calculations have been carried out to obtain crystal field parameters for the paramagnetic state of UGa 2 and UPd 2Al 3. In two sets of calculations localized 5f states with occupation two and three, respectively, have been assumed. Using these parameters and adjusted anisotropic molecular field constants, the paramagnetic susceptibility for both compounds and the Schottky contribution to the specific heat in UPd 2Al 3 have been obtained by crystal field model calculations. Very good agreement between theoretical and experimental data is found for 5f 2 occupation in UGa 2. For UPd 2Al 3, the 5f 2 assumption yields qualitatively reasonable results as well, but it does not explain the T = 50 K maximum in the experimental data.

  15. Effects of different pretreatments on specific heat of forage maize%不同前处理对饲料玉米比热的影响

    Institute of Scientific and Technical Information of China (English)

    王红英; 李倪薇; 高蕊; 杨洁; 康宏彬

    2012-01-01

    为了明确以玉米为原料的配方饲料在调质、膨化、冷却过程中传热传质的基本特性,该文利用差示量热扫描仪(differential scanning calorimeter,DSC)测比热的方法,研究了自然干燥条件下,不同的烘干温度(45~105℃)、含水率(12%~16%,湿基计)、粉碎粒度(0.2~0.6 mm)等前处理因素对玉米比热的影响.采用3因素5水平2次正交旋转设计,通过回归分析和响应面分析,建立了玉米比热基于烘干温度、含水率(湿基计)、粉碎粒度的数学模型.研究结果表明:所得同归方程拟合情况良好,当烘干温度为45℃、含水率为12%(湿基计)、粉碎粒度为0.6mm时,玉米的比热值最小为2051J/(kg·K).此模型的建立可为不同处理条件下玉米比热值的直接获得提供理论方法与依据,为不同配方饲料的湿热加工特性研究提供参考.%In order to determine the heat and mass transfer properties of corn-based feedstuff's during the process of conditioning, extrusion and cooling, the effects of drying temperature (45-105℃), moisture content (12%-16%) wet basis, particle size (0.2-0.6 mm) on the specific heat of corn grain were investigated using a continuous differential scanning calorimeter (DSC) method. The experiments in three factors with five levels were designed by quadratic orthogonal rotation approach. A model of specific heat of corn grain versus dry temperature, moisture content and particle size was established by regression analysis and response surface methodology (RSM). The results showed that the minimum specific heat of corn grain was obtained(2051 J/(kg·K)) under the processing condition of drying temperature 45℃, moisture content 12% wet basis , and particle size 0.6 mm. This model can be used to evaluate the specific heat of corn grain processing in different conditions and to provide a reference for thermal processing of similar feedstuffs.

  16. Magnetic properties of PrX 2 compounds (X = Pt, Rh, Ru, Ir) studied by hyperfine specific heat, magnetization and neutron-diffraction measurements

    Science.gov (United States)

    Greidanus, F. J. A. M.; de Jongh, L. J.; Huiskamp, W. J.; Fischer, P.; Furrer, A.; Buschow, K. H. J.

    1983-04-01

    Magnetic ordering phenomena in rare-earth intermetallic compounds can be unravelled most advantageously in the case of simple crystallographic structure and when a combination of microscopic techniques is applied. Here we shall present the temperature and magnetic field dependence of the magnetic moment of the cubic PrX 2 compounds (X = Pt, Rh, Ru, Ir), as inferred from hyperfine specific-heat, magnetization and neutron-diffraction measurements. The results are compared with a mean-field calculation, taking crystalline electric field and bilinear (dipolar) exchange interactions into account. Adopting experimental values of the Lea, Leask and Wolf parameters x and W from inelastic neutron scattering results, we find satisfactory agreement between our magnetic data and the mean-field theory. An observed discrepancy of about 15% between the calculated and measured saturation values of the spontaneous magnetization can be explained by the presence of quadrupolar interactions.

  17. Invertible flexible matrices

    Science.gov (United States)

    Justino, Júlia

    2017-06-01

    Matrices with coefficients having uncertainties of type o (.) or O (.), called flexible matrices, are studied from the point of view of nonstandard analysis. The uncertainties of the afore-mentioned kind will be given in the form of the so-called neutrices, for instance the set of all infinitesimals. Since flexible matrices have uncertainties in their coefficients, it is not possible to define the identity matrix in an unique way and so the notion of spectral identity matrix arises. Not all nonsingular flexible matrices can be turned into a spectral identity matrix using Gauss-Jordan elimination method, implying that that not all nonsingular flexible matrices have the inverse matrix. Under certain conditions upon the size of the uncertainties appearing in a nonsingular flexible matrix, a general theorem concerning the boundaries of its minors is presented which guarantees the existence of the inverse matrix of a nonsingular flexible matrix.

  18. Global Sourcing Flexibility

    DEFF Research Database (Denmark)

    Ørberg Jensen, Peter D.; Petersen, Bent

    2013-01-01

    sourcing flexibility. Here we draw on prior research in the fields of organizational flexibility, international business and global sourcing as well as case examples and secondary studies. In the second part of the paper, we discuss the implications of global sourcing flexibility for firm strategy......Recent studies show that flexibility is a key concern for firms that engage in the global sourcing of services. In this conceptual paper, we seek to explore two central aspects of global sourcing flexibility: In the first part of the paper, we provide a definition of the construct of global...... and operations against the backdrop of the theory-based definition of the construct. We discuss in particular the importance of global sourcing flexibility for operational performance stability, and the trade-off between specialization benefits, emerging from location and service provider specialization, versus...

  19. Call centres: constructing flexibility

    OpenAIRE

    Arzbächer, Sandra; Holtgrewe, Ursula; Kerst, Christian

    2002-01-01

    "The development of call centres as a flexible interface between firms and their environments has been seen as exemplary or even symptomatic of flexible capitalism (Sennett 1998). We are going to point out that they do not just stand for organisational change but also for changes of institutions towards deregulation. Employers and managers hoped for gains of flexibility, decreasing labour costs, and market gains by an expanded 24-hour-service. Surveillance and control by flexib...

  20. Pneumatic flexible shaft couplings

    OpenAIRE

    2007-01-01

    Main effort of every design engineer is reduction of torsional oscillation in any mechanical system. At present this problem can be solved by means of a suitable modification of dynamic properties of flexible shaft couplings according to dynamics in the given systems. But the dynamic properties of nowadays-applied flexible couplings arenot unchangeable because of aging and fatigue processes occurring in flexible coupling elements. Result of this fact causes detuning of mechanical system. Taki...

  1. Versatile Flexible Graphene Multielectrode Arrays.

    Science.gov (United States)

    Kireev, Dmitry; Seyock, Silke; Ernst, Mathis; Maybeck, Vanessa; Wolfrum, Bernhard; Offenhäusser, Andreas

    2016-12-23

    Graphene is a promising material possessing features relevant to bioelectronics applications. Graphene microelectrodes (GMEAs), which are fabricated in a dense array on a flexible polyimide substrate, were investigated in this work for their performance via electrical impedance spectroscopy. Biocompatibility and suitability of the GMEAs for extracellular recordings were tested by measuring electrical activities from acute heart tissue and cardiac muscle cells. The recordings show encouraging signal-to-noise ratios of 65 ± 15 for heart tissue recordings and 20 ± 10 for HL-1 cells. Considering the low noise and excellent robustness of the devices, the sensor arrays are suitable for diverse and biologically relevant applications.

  2. Versatile Flexible Graphene Multielectrode Arrays

    Directory of Open Access Journals (Sweden)

    Dmitry Kireev

    2016-12-01

    Full Text Available Graphene is a promising material possessing features relevant to bioelectronics applications. Graphene microelectrodes (GMEAs, which are fabricated in a dense array on a flexible polyimide substrate, were investigated in this work for their performance via electrical impedance spectroscopy. Biocompatibility and suitability of the GMEAs for extracellular recordings were tested by measuring electrical activities from acute heart tissue and cardiac muscle cells. The recordings show encouraging signal-to-noise ratios of 65 ± 15 for heart tissue recordings and 20 ± 10 for HL-1 cells. Considering the low noise and excellent robustness of the devices, the sensor arrays are suitable for diverse and biologically relevant applications.

  3. Flexible implementation of rigid solar cell technologies.

    Energy Technology Data Exchange (ETDEWEB)

    Hollowell, Andrew E.

    2010-08-01

    As a source of clean, remote energy, photovoltaic (PV) systems are an important area of research. The majority of solar cells are rigid materials with negligible flexibility. Flexible PV systems possess many advantages, such as being transportable and incorporable on diverse structures. Amorphous silicon and organic PV systems are flexible; however, they lack the efficiency and lifetime of rigid cells. There is also a need for PV systems that are light weight, especially in space and flight applications. We propose a solution to this problem by arranging rigid cells onto a flexible substrate creating efficient, light weight, and flexible devices. To date, we have created a working prototype of our design using the 1.1cm x 1cm Emcore cells. We have achieved a better power to weight ratio than commercially available PowerFilm{reg_sign}, which uses thin film silicon yielding .034W/gram. We have also tested our concept with other types of cells and verified that our methods are able to be adapted to any rigid solar cell technology. This allows us to use the highest efficiency devices despite their physical characteristics. Depending on the cell size we use, we can rival the curvature of most available flexible PV devices. We have shown how the benefits of rigid solar cells can be integrated into flexible applications, allowing performance that surpasses alternative technologies.

  4. Reversibly Bistable Flexible Electronics

    KAUST Repository

    Alfaraj, Nasir

    2015-05-01

    Introducing the notion of transformational silicon electronics has paved the way for integrating various applications with silicon-based, modern, high-performance electronic circuits that are mechanically flexible and optically semitransparent. While maintaining large-scale production and prototyping rapidity, this flexible and translucent scheme demonstrates the potential to transform conventionally stiff electronic devices into thin and foldable ones without compromising long-term performance and reliability. In this work, we report on the fabrication and characterization of reversibly bistable flexible electronic switches that utilize flexible n-channel metal-oxide-semiconductor field-effect transistors. The transistors are fabricated initially on rigid (100) silicon substrates before they are peeled off. They can be used to control flexible batches of light-emitting diodes, demonstrating both the relative ease of scaling at minimum cost and maximum reliability and the feasibility of integration. The peeled-off silicon fabric is about 25 µm thick. The fabricated devices are transferred to a reversibly bistable flexible platform through which, for example, a flexible smartphone can be wrapped around a user’s wrist and can also be set back to its original mechanical position. Buckling and cyclic bending of such host platforms brings a completely new dimension to the development of flexible electronics, especially rollable displays.

  5. Organizational flexibility estimation

    OpenAIRE

    Komarynets, Sofia

    2013-01-01

    By the help of parametric estimation the evaluation scale of organizational flexibility and its parameters was formed. Definite degrees of organizational flexibility and its parameters for the Lviv region enterprises were determined. Grouping of the enterprises under the existing scale was carried out. Special recommendations to correct the enterprises behaviour were given.

  6. Flexible magnetoimpidence sensor

    KAUST Repository

    Kavaldzhiev, Mincho

    2015-05-01

    Recently, flexible electronic devices have attracted increasing interest, due to the opportunities they promise for new applications such as wearable devices, where the components are required to flex during normal use[1]. In this light, different magnetic sensors, like microcoil, spin valve, giant magnetoresistance (GMR), magnetoimpedance (MI), have been studied previously on flexible substrates.

  7. Flexible 'zoning' aids adaptability.

    Science.gov (United States)

    Corben, Simon

    2013-09-01

    Simon Corben, business development director at Capita Symonds' Health team, examines how 'clever use of zoning' when planning new healthcare facilities could improve hospital design, increase inherent flexibility, and reduce lifetime costs, and argues that a 'loose-fit, non-bespoke approach' to space planning will lead to 'more flexible buildings that are suitable for conversion to alternative uses'.

  8. Flexible ferroelectric organic crystals

    Science.gov (United States)

    Owczarek, Magdalena; Hujsak, Karl A.; Ferris, Daniel P.; Prokofjevs, Aleksandrs; Majerz, Irena; Szklarz, Przemysław; Zhang, Huacheng; Sarjeant, Amy A.; Stern, Charlotte L.; Jakubas, Ryszard; Hong, Seungbum; Dravid, Vinayak P.; Stoddart, J. Fraser

    2016-10-01

    Flexible organic materials possessing useful electrical properties, such as ferroelectricity, are of crucial importance in the engineering of electronic devices. Up until now, however, only ferroelectric polymers have intrinsically met this flexibility requirement, leaving small-molecule organic ferroelectrics with room for improvement. Since both flexibility and ferroelectricity are rare properties on their own, combining them in one crystalline organic material is challenging. Herein, we report that trisubstituted haloimidazoles not only display ferroelectricity and piezoelectricity--the properties that originate from their non-centrosymmetric crystal lattice--but also lend their crystalline mechanical properties to fine-tuning in a controllable manner by disrupting the weak halogen bonds between the molecules. This element of control makes it possible to deliver another unique and highly desirable property, namely crystal flexibility. Moreover, the electrical properties are maintained in the flexible crystals.

  9. Flexible ferroelectric organic crystals

    Science.gov (United States)

    Owczarek, Magdalena; Hujsak, Karl A.; Ferris, Daniel P.; Prokofjevs, Aleksandrs; Majerz, Irena; Szklarz, Przemysław; Zhang, Huacheng; Sarjeant, Amy A.; Stern, Charlotte L.; Jakubas, Ryszard; Hong, Seungbum; Dravid, Vinayak P.; Stoddart, J. Fraser

    2016-01-01

    Flexible organic materials possessing useful electrical properties, such as ferroelectricity, are of crucial importance in the engineering of electronic devices. Up until now, however, only ferroelectric polymers have intrinsically met this flexibility requirement, leaving small-molecule organic ferroelectrics with room for improvement. Since both flexibility and ferroelectricity are rare properties on their own, combining them in one crystalline organic material is challenging. Herein, we report that trisubstituted haloimidazoles not only display ferroelectricity and piezoelectricity—the properties that originate from their non-centrosymmetric crystal lattice—but also lend their crystalline mechanical properties to fine-tuning in a controllable manner by disrupting the weak halogen bonds between the molecules. This element of control makes it possible to deliver another unique and highly desirable property, namely crystal flexibility. Moreover, the electrical properties are maintained in the flexible crystals. PMID:27734829

  10. (abstract) Determination of the Specific Heat and Total Hemispherical Total Emissivity of the Highly Undercooled Zr(sub 41.2)Ti(sub 13.8)Cu(sub 12.5)Ni(sub 10.0)Be(sub 22.5) Alloy

    Science.gov (United States)

    Busch, R.; Kim, Y. J.; Johnson, W. L.; Rulison, A. J.; Rhim, W. K.

    1995-01-01

    High temperature high vacuum electrostatic levitation was combined with DSC experiments to determine the specific heat C(sub p) of the undercooled Zr(sub 41.2)Ti(sub 13.8)Cu(sub 12.5)Ni(sub 10.0)Be(sub 22.5) liquid as a function of temperature. The containerless approach made it possible to undercool the melt to the glass transition temperature without inducing nucleation. Because the cooling process was purely radiative, noncontact temperature measurement techniques could be used to determine the specific heat to total hemispherical emissivity ratio, C(sub p)/epsilon(sub t), for the undercooled liquid region. Using C(sub p) values which were independently obtained by DSC, epsilon(sub t) could be determined. With knowledge of C(sub p) of the undercooled liquid it was possible to determine other thermodynamic properties such as Gibbs free energy and entropy as a function of undercooling.

  11. Electronic properties of UX{sub 3} (X=Ga, Al, and Sn) compounds in high magnetic fields: Transport, specific heat, magnetization, and quantum oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Cornelius, A.L.; Arko, A.J.; Sarrao, J.L.; Thompson, J.D.; Hundley, M.F.; Booth, C.H. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545 (United States); Harrison, N. [National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Oppeneer, P.M. [Institute of Theoretical Physics, University of Technology, D-01062 Dresden (Germany)

    1999-06-01

    We have performed measurements of the specific heat and resistivity in static magnetic fields up to 12 T, as well as magnetic measurements in a static field of 0.1 T and in pulsed fields up to 50 T on high-quality UX{sub 3} (X=Ga, Al, and Sn) single crystals. The behavior of the electronic specific heat coefficients in applied field {gamma}(B) either remains nearly constant or increases as {ital B} increases and is inconsistent with the expectations of the single-impurity model. For UGa{sub 3}, different de Haas{endash}van Alphen (dHvA) frequencies are observed above and below a magnetic transition at a field B{sub M}{approximately}12 T at T{approximately}0.5 K, indicating that a major reconstruction of the Fermi surface occurs. Neither USn{sub 3} nor UAl{sub 3} exhibited a magnetic transition in fields to 50 T, and only a single weak dHvA frequency was observed in these compounds. The difference between the behavior of the UX{sub 3} compounds can be attributed to the degree of hybridization of the 5f orbitals with the conduction electron orbitals. UGa{sub 3} behaves as an itinerant 5f-electron system, while UAl{sub 3} has a tendency to localization, but is still relatively delocalized. USn{sub 3} is a heavy fermion compound. Concurrent to our experimental investigations we have performed calculations of the energy band structures of the three compounds. Owing to the delocalized 5f behavior of UGa{sub 3}, and also of UAl{sub 3}, we find that an itinerant, energy band approach explains the dHvA frequencies of antiferromagnetic UGa{sub 3} and paramagnetic UAl{sub 3} reasonably well. For UGa{sub 3} an unusual sensitivity of the magnetic moment to the magnetic structure and the lattice parameter occurs, providing evidence that UGa{sub 3} is an unique example of an itinerant uranium-based antiferromagnet. thinsp {copyright} {ital 1999} {ital The American Physical Society}

  12. Thermal Diffusivity and Specific Heat Measurements of Titanium Potassium Perchlorate Titanium Subhydride Potassium Perchlorate 9013 Glass 7052 Glass SB-14 Glass and C-4000 Muscovite Mica Using the Flash Technique

    Energy Technology Data Exchange (ETDEWEB)

    Specht, Paul Elliott [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cooper, Marcia A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-02-01

    The flash technique was used to measure the thermal diffusivity and specific heat of titanium potassium perchlorate (TKP) ignition powder (33wt% Ti - 67wt% KP) with Ventron sup- plied titanium particles, TKP ignition powder (33wt% Ti - 67wt% KP) with ATK supplied titanium particles, TKP output powder (41wt% Ti - 59wt% KP), and titanium subhydride potassium perchlorate (THKP) (33wt% TiH 1.65 - 67wt% KP) at 25°C. The influence of density and temperature on the thermal diffusivity and specific heat of TKP with Ventron supplied titanium particles was also investigated. Lastly, the thermal diffusivity and specific heats of 9013 glass, 7052 glass, SB-14 glass, and C-4000 Muscovite mica are presented as a function of temperature up to 300° C.

  13. Thermal Diffusivity and Specific Heat Measurements of Titanium Potassium Perchlorate Titanium Subhydride Potassium Perchlorate 9013 Glass 7052 Glass SB-14 Glass and C-4000 Muscovite Mica Using the Flash Technique.

    Energy Technology Data Exchange (ETDEWEB)

    Specht, Paul Elliott; Cooper, Marcia A.

    2015-02-01

    The flash technique was used to measure the thermal diffusivity and specific heat of titanium potassium perchlorate (TKP) ignition powder (33wt% Ti - 67wt% KP) with Ventron sup- plied titanium particles, TKP ignition powder (33wt% Ti - 67wt% KP) with ATK supplied titanium particles, TKP output powder (41wt% Ti - 59wt% KP), and titanium subhydride potassium perchlorate (THKP) (33wt% TiH 1.65 - 67wt% KP) at 25 o C. The influence of density and temperature on the thermal diffusivity and specific heat of TKP with Ventron supplied titanium particles was also investigated. Lastly, the thermal diffusivity and specific heats of 9013 glass, 7052 glass, SB-14 glass, and C-4000 Muscovite mica are presented as a function of temperature up to 300 o C.

  14. Predicting hospital failure with the financial flexibility index.

    Science.gov (United States)

    Cleverley, W O

    1985-05-01

    In an environment of increasing financial risk, hospital managers are looking for ways to predict financial difficulties before they occur. One response is the financial flexibility index. This index, which uses 10 financial ratios, measures the inflow and outflow of funds to determine the financial flexibility of the institution and identify problem areas before financial failure occurs.

  15. Specific Heat in Zero and Applied Magnetic Field of Overdoped Ba1-xKxFe2As2: Analysis of The Multigap Behavior and Anisotropies

    Science.gov (United States)

    Stewart, G. R.; Kim, J. S.; Liu, Yong; Lograsso, Thomas A.

    2015-03-01

    Specific heat measurements down to 0.4 K and up to Hc2 on single crystals of two different compositions of overdoped Ba1-xKxFe2As2 with Tc values of 5.9 K (x ~0.93) and 8.9 K (x ~0.85) are reported. The possibility of mixed/crossover behavior in the pairing symmetry in this composition range has been discussed in the literature. The zero field data analysis for both samples results in essentially the same two gap values: 2 Δ/kTc = 0.9 and 3.5 while the field data indicate pronounced non-linearity in γ vs H both as the lower gap is suppressed by about 1 T but also in higher fields up to Hc2 ~ 5.5 T. Analysis of the field data to investigate the gap anisotropies will be presented. Work at Florida supported by US DOE, BES Contract No. DE-FG02-86ER45268 and at Ames by US DOE, BES Contract No. DE-AC02-07CH11358.

  16. Investigation of a CDDW Hamiltonian to Explore Possibility of Magneto-Quantum Oscillations in Electronic Specific Heat of Hole-Doped Cuprates

    Directory of Open Access Journals (Sweden)

    Partha Goswami

    2010-01-01

    Full Text Available We investigate a chiral d-density wave (CDDW mean field model Hamiltonian in the momentum space suitable for the hole-doped cuprates, such as YBCO, in the pseudogap phase to obtain the Fermi surface (FS topologies, including the anisotropy parameter(́ and the elastic scattering by disorder potential (|0|. For ́=0, with the chemical potential =−0.27 eV for 10% doping level and |0|≥|| (where ||=0.25 eV is the first neighbor hopping, at zero/non-zero magnetic field (, the FS on the first Brillouin zone is found to correspond to electron pockets around antinodal regions and barely visible patches around nodal regions. For ́≠0, we find Pomeranchuk distortion of FS. We next relate our findings regarding FS to the magneto-quantum oscillations in the electronic specific heat. Since the nodal quasiparticle energy values for =0 are found to be greater than for |0|≥||, the origin of the oscillations for nonzero corresponds to the Fermi pockets around antinodal regions. The oscillations are shown to take place in the weak disorder regime (|0|=0.25eV only.

  17. Thermolysis, nonisothermal decomposition kinetics, specific heat capacity and adiabatic time-to-explosion of [Cu(NH3)4](DNANT)2 (DNANT= dinitroacetonitrile).

    Science.gov (United States)

    Zhang, Yu; Wu, Hao; Xu, Kangzhen; Zhang, Wantao; Ren, Zhaoyu; Song, Jirong; Zhao, Fengqi

    2014-02-20

    A new energetic copper complex of dinitroacetonitrile (DNANT), [Cu(NH3)4](DNANT)2, was first synthesized through an unexpected reaction. The thermal decomposition of [Cu(NH3)4](DNANT)2 was studied with DSC and TG/DTG methods. The gas products were analyzed through a TG-FTIR-MS method. The nonisothermal kinetic equation of the exothermic process is dα/dT = 10(10.92)/β4(1 - α)[-ln(1 - α)](3/4) exp(-1.298 × 10(5)/RT). The self-accelerating decomposition temperature and critical temperature of thermal explosion are 217.9 and 221.0 °C. The specific heat capacity of [Cu(NH3)4](DNANT)2 was determined with a micro-DSC method, and the molar heat capacity is 512.6 J mol(-1) K(-1) at 25 °C. Adiabatic time-to-explosion of Cu(NH3)4(DNANT)2 was also calculated to be about 137 s.

  18. Strong-Coupling Properties of a p-Wave Interacting Fermi Gas on the Viewpoint of Specific Heat at Constant Volume

    Science.gov (United States)

    Inotani, Daisuke; van Wyk, Pieter; Ohashi, Yoji

    2017-02-01

    We theoretically investigate the specific heat CV at constant volume in the normal state of a p-wave interacting Fermi gas. Including fluctuations in the p-wave Cooper channel within the framework of the strong-coupling theory developed by Nozières and Schmitt-Rink, we clarify how CV as a function of temperature varies, as one moves from the weak-coupling regime to the strong-coupling limit. In the weak-coupling regime, CV is shown to be enhanced by p-wave pairing fluctuations, near the superfluid phase transition temperature Tc. Similar enhancement of CV(T ≃ Tc) is also obtained in the strong-coupling regime, which, however, reflects that system is close an ideal Bose gas of p-wave two-body bound molecules. Using these results, we classify the normal state into (1) the normal Fermi gas regime, (2) the p-wave molecular Bose gas regime, and (3) the region between the two, where p-wave pairing fluctuations are dominant. Since the current experiments can only access the normal phase of a p-wave interacting Fermi gas, our results would be useful for experiments to understand strong-coupling properties of this Fermi system above Tc.

  19. Electronic specific heat coefficient and magnetic properties of L2{sub 1} phase in Co{sub 2}YGa (Y = Cr, Mn and Fe) Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Umetsu, R Y; Endo, N; Kainuma, R; Fukamichi, K [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Sendai 980-8577 (Japan); Fujita, A; Ishida, K [Department of Materials Science, Graduate School of Engineering, Tohoku University, 02 Aoba-yama, Sendai 980-8579 (Japan); Sakuma, A, E-mail: rie@tagen.tohoku.ac.j [Department of Applied Physics, Graduate School of Engineering, Tohoku University, 08 Aoba-yama, Sendai 980-8579 (Japan)

    2010-01-01

    The electronic specific heat coefficient {gamma}, and the high field susceptibility {chi}{sub hf} of the L2{sub 1} phase in Co-based Heusler alloys were investigated in order to relate these properties to the spin polarization P. The {gamma}-values of Co{sub 2}CrGa, Co{sub 2}MnGa and Co{sub 2}FeGa alloys are comparable to the theoretical values of the total density of states at the Fermi energy. The value of {chi}{sub hf} for Co{sub 2}CrGa alloy having a high spin polarization of about 95% is significantly low on the order of 10{sup -4} {mu}{sub B}/f.u.-T. In contrast, {chi}{sub hf} for Co{sub 2}FeGa alloy having a theoretical P value of 37% is one order larger than that for Co{sub 2}CrGa alloy. These results imply that there is a relation between {chi}{sub hf} and P of the present Co-based Heusler alloys.

  20. Painful Flexible Flatfoot.

    Science.gov (United States)

    Sheikh Taha, Abdel Majid; Feldman, David S

    2015-12-01

    Flatfoot is commonly encountered by pediatric orthopedic surgeons and pediatricians. A paucity of literature exists on how to define a flatfoot. The absence of the medial arch with a valgus hindfoot is the hallmark of this pathology. Flatfoot can be flexible or rigid. This review focuses on the diagnosis and treatment of the flexible flatfoot. Most flatfeet are flexible and clinically asymptomatic, and warrant little intervention. If feet are symptomatic, treatment is needed. Most patients who require treatment improve with foot orthotics and exercises. Only feet resistant to conservative modalities are deemed surgical candidates. The presence of a tight heel cord is often found in patients who fail conservative management.

  1. Flexible Support Stanchion

    Energy Technology Data Exchange (ETDEWEB)

    Rudland, D.L.; /Fermilab

    1987-05-11

    Figure 1 shows the assembly drawing of the Central Calorimeter Cryostat Flexible Support Stanchion. Figures 2 and 3 show the Flexible Support STanchion in detail. These Stanchions support the cryostat safely, reduce the heat load to the cryostat from the ambient by a factor of more than ten, provide a spring like action that reduce the loads created by thermal contraction of the cryostat and position the cryostate accurately. Table 1 shows all of the details of the Flexible Support system for the C.C. Cryostat.

  2. Specific heat, differential susceptibility and electrical resistivity of PrX2 (X = Ir, Pt, Rh and Ru) laves phase compounds at temperatures 1.4 K < T < 40 K

    Science.gov (United States)

    van Dongen, J. C. M.; van der Linden, H. W. M.; Greidanus, F. J. A. M.; Nieuwenhuys, G. J.; Mydosh, J. A.; Buschow, K. H. J.

    1980-01-01

    Specific heat and differential susceptibility data of PrX 2 (X = Ir, Pt, Rh, and Ru) compounds reveal phase transitions at Tc = (11.2 ± 0.5) K, (7.7 ± 0.5) K, (7.9 ± 0.5) K and (33.9 ± 0.5) K for X = Ir, Pt, RhandRu, resp. The electrical resistivity drops markedly below Tc, and the dϱ/d T versus T curve is similar to that of the specific heat.

  3. Intermittent Swimming with a Flexible Propulsor

    Science.gov (United States)

    Akoz, Emre; Zeyghami, Samane; Moored, Keith

    2016-11-01

    Some animals propel themselves by using an intermittent swimming gait known as a burst-and-glide or a burst-and-coast motion. These swimmers tend to have a more pronounced pitching of their caudal fins than heaving leading to low non-dimensional heave-to-pitch ratios. Recent work has shown that when this ratio is sufficiently low the efficiency of an intermittently heaving/pitching airfoil can be significantly improved over a continuously oscillating airfoil. However, fish that swim with an intermittent gait, such as cod and saithe, do not have rigid fins, but instead have highly flexible fins. To examine the performance and flow structures of an intermittent swimmer with a flexible propulsor, a fast boundary element method solver strongly coupled with a torsional-spring structural model was developed. A self-propelled virtual body combined with a flexible-hinged pitching airfoil is used to model a free-swimming animal and its flexible caudal fin. The duty cycle of the active to the coasting phase of motion, the torsional spring flexibility and the forcing frequency are all varied. The cost-of-transport and the swimming speed are measured and connected to the observed wake patterns. Supported by the Office of Naval Research under Program Director Dr. Bob Brizzolara, MURI Grant Number N00014-14-1-0533.

  4. Flexible Word Classes

    DEFF Research Database (Denmark)

    2013-01-01

    • First major publication on the phenomenon • Offers cross-linguistic, descriptive, and diverse theoretical approaches • Includes analysis of data from different language families and from lesser studied languages This book is the first major cross-linguistic study of 'flexible words', i.e. words...... that cannot be classified in terms of the traditional lexical categories Verb, Noun, Adjective or Adverb. Flexible words can - without special morphosyntactic marking - serve in functions for which other languages must employ members of two or more of the four traditional, 'specialised' word classes. Thus......, flexible words are underspecified for communicative functions like 'predicating' (verbal function), 'referring' (nominal function) or 'modifying' (a function typically associated with adjectives and e.g. manner adverbs). Even though linguists have been aware of flexible world classes for more than...

  5. Flexible displays, rigid designs?

    DEFF Research Database (Denmark)

    Hornbæk, Kasper

    2015-01-01

    Rapid technological progress has enabled a wide range of flexible displays for computing devices, but the user experience--which we're only beginning to understand--will be the key driver for successful designs....

  6. Flexibility in insulin prescription

    Directory of Open Access Journals (Sweden)

    Sanjay Kalra

    2016-01-01

    Full Text Available This communication explores the concept of flexibility, a propos insulin preparations and insulin regimes used in the management of type 2 diabetes. The flexibility of an insulin regime or preparation is defined as their ability to be injected at variable times, with variable injection-meal time gaps, in a dose frequency and quantum determined by shared decision making, with a minimal requirement of glucose monitoring and health professional consultation, with no compromise on safety, efficiency and tolerability. The relative flexibility of various basal, prandial and dual action insulins, as well as intensive regimes, is compared. The biopsychosocial model of health is used to assess the utility of different insulins while encouraging a philosophy of flexible insulin usage.

  7. COUPLING EFFECT OF FLEXIBLE JOINT AND FLEXIBLE LINK ON DYNAMIC SINGULARITY OF FLEXIBLE MANIPULATOR

    Institute of Scientific and Technical Information of China (English)

    GAO Zhihui; YUN Chao; BIAN Yushu

    2008-01-01

    The coupling effect of the flexible joint and the flexible link on the dynamic singularity of the flexible manipulator is addressed. Firstly, the dynamic equations of a flexible manipulator with a flexible joint and a flexible link are derived. Secondly, the relationship and property between the flexible joint and the flexible link are analyzed. It shows that the flexible joint's amplitude will increase abruptly, thereby the dynamic singularity occurs if the frequency of a flexible joint is near or equal to some natural frequency of a flexible link. Finally, some numerical simulations which will verify the correctness of the theoretical analysis, are carried out. The results are fundamental for the design of a flexible manipulator and for the avoidance of the dynamic singularity.

  8. Unexpected behavior of ultra-thin films of blends of polystyrene/poly(vinyl methyl ether) studied by specific heat spectroscopy

    Science.gov (United States)

    Madkour, Sherif; Szymoniak, Paulina; Schick, Christoph; Schönhals, Andreas

    2017-05-01

    Specific heat spectroscopy (SHS) employing AC nanochip calorimetry was used to investigate the glassy dynamics of ultra-thin films (thicknesses: 10 nm-340 nm) of a polymer blend, which is miscible in the bulk. In detail, a Poly(vinyl methyl ether) (PVME)/Polystyrene (PS) blend with the composition of 25/75 wt. % was studied. The film thickness was controlled by ellipsometry while the film topography was checked by atomic force microscopy. The results are discussed in the framework of the balance between an adsorbed and a free surface layer on the glassy dynamics. By a self-assembling process, a layer with a reduced mobility is irreversibly adsorbed at the polymer/substrate interface. This layer is discussed employing two different scenarios. In the first approach, it is assumed that a PS-rich layer is adsorbed at the substrate. Whereas in the second approach, a PVME-rich layer is suggested to be formed at the SiO2 substrate. Further, due to the lower surface tension of PVME, with respect to air, a nanometer thick PVME-rich surface layer, with higher molecular mobility, is formed at the polymer/air interface. By measuring the glassy dynamics of the thin films of PVME/PS in dependence on the film thickness, it was shown that down to 30 nm thicknesses, the dynamic Tg of the whole film was strongly influenced by the adsorbed layer yielding a systematic increase in the dynamic Tg with decreasing the film thickness. However, at a thickness of ca. 30 nm, the influence of the mobile surface layer becomes more pronounced. This results in a systematic decrease in Tg with the further decrease of the film thickness, below 30 nm. These results were discussed with respect to thin films of PVME/PS blend with a composition of 50/50 wt. % as well as literature results.

  9. A Wang-Landau study of the phase transitions in a flexible homopolymer

    Science.gov (United States)

    Seaton, D. T.; Wüst, T.; Landau, D. P.

    2009-04-01

    Using Wang-Landau sampling we study the characteristic behavior of a flexible homopolymer (off-lattice) for chain lengths up to N=300. The Hamiltonian consists of a Lennard-Jones potential between all monomers, and an additional FENE potential between bonded monomers. From the resultant density of states, we calculate thermodynamic properties for a wide range of temperatures, including low temperatures that are inaccessible to traditional Monte Carlo algorithms. Peaks in the specific heat and radius of gyration indicate the coil-globule and solid-liquid transitions. With a careful implementation of the algorithm, we find no evidence of a liquid-liquid transition.

  10. Heavily doped M1−xUxF2+2x fluorites studied by quasielastic neutron scattering(M=Ba) and specific heat measurements (M=Pb)

    DEFF Research Database (Denmark)

    Andersen, Niels Hessel; Clausen, Kurt Nørgaard; Kjems, Jørgen

    1983-01-01

    The thermal generation of defects in pure and doped Pb1−xUxF2+2x (x=0, 0.05and0.10) has been studied by specific heat measurements between 475 k and 875 k. A simple phenomenological mean field thermodynamic model has been developed and used to interpret the data. At low temperatures the result...

  11. Wetting of flexible fibre arrays.

    Science.gov (United States)

    Duprat, C; Protière, S; Beebe, A Y; Stone, H A

    2012-02-23

    Fibrous media are functional and versatile materials, as demonstrated by their ubiquity both in natural systems such as feathers and adhesive pads and in engineered systems from nanotextured surfaces to textile products, where they offer benefits in filtration, insulation, wetting and colouring. The elasticity and high aspect ratios of the fibres allow deformation under capillary forces, which cause mechanical damage, matting self-assembly or colour changes, with many industrial and ecological consequences. Attempts to understand these systems have mostly focused on the wetting of rigid fibres or on elastocapillary effects in planar geometries and on a fibre brush withdrawn from an infinite bath. Here we consider the frequently encountered case of a liquid drop deposited on a flexible fibre array and show that flexibility, fibre geometry and drop volume are the crucial parameters that are necessary to understand the various observations referred to above. We identify the conditions required for a drop to remain compact with minimal spreading or to cause a pair of elastic fibres to coalesce. We find that there is a critical volume of liquid, and, hence, a critical drop size, above which this coalescence does not occur. We also identify a drop size that maximizes liquid capture. For both wetting and deformation of the substrates, we present rules that are deduced from the geometric and material properties of the fibres and the volume of the drop. These ideas are applicable to a wide range of fibrous materials, as we illustrate with examples for feathers, beetle tarsi, sprays and microfabricated systems.

  12. Pneumatic flexible shaft couplings

    Directory of Open Access Journals (Sweden)

    Jaroslav HOMIŠIN

    2007-01-01

    Full Text Available Main effort of every design engineer is reduction of torsional oscillation in any mechanical system. At present this problem can be solved by means of a suitable modification of dynamic properties of flexible shaft couplings according to dynamics in the given systems. But the dynamic properties of nowadays-applied flexible couplings arenot unchangeable because of aging and fatigue processes occurring in flexible coupling elements. Result of this fact causes detuning of mechanical system. Taking into consideration the above-mentioned situation, we suggest for mechanical systems application of a newly developed pneumatic couplings that have constant characteristicfeatures during the whole current operation and thus they have a positive influence on the system running.

  13. Designing structural supply chain flexibility

    OpenAIRE

    Mulinski, Ksawery Jan

    2012-01-01

    In a continuously changing business environment the role of supply chain flexibility is constantly increasing. A flexible supply chain can ensure survival in quickly changing market conditions as well as enable sustainable growth. This thesis explores the topic of supply chain flexibility with focus on structural flexibility due to scarcity of previous research in that area. The purpose of the research is to answer a question: how can companies design structural supply chain flexibility? In a...

  14. Flexible polymer waveguide tunable lasers.

    Science.gov (United States)

    Kim, Kyung-Jo; Kim, Jun-Whee; Oh, Min-Cheol; Noh, Young-Ouk; Lee, Hyung-Jong

    2010-04-12

    A flexible polymeric Bragg reflector is fabricated for the purpose of demonstrating widely tunable lasers with a compact simple structure. The external feedback of the Bragg reflected light into a superluminescent laser diode produces the lasing of a certain resonance wavelength. The highly elastic polymer device enables the direct tuning of the Bragg wavelength by controlling the imposed strain and provides a much wider tuning range than silica fiber Bragg gratings or thermo-optic tuned polymer devices. Both compressive and tensile strains are applied within the range from -36000 microepsilon to 35000 microepsilon, so as to accomplish the continuous tuning of the Bragg reflection wavelength over a range of up to 100 nm. The external feedback laser with the tunable Bragg reflector exhibits a repetitive wavelength tuning range of 80 nm with a side mode suppression ratio of 35 dB.

  15. Adhesion Transition of Flexible Filaments

    Science.gov (United States)

    Evans, Arthur; Lauga, Eric

    2009-03-01

    As forays into fabrication and self-assembly venture to increasingly small length scales, the role of adhesion events between material elements of the system must be closely scrutinized. This area of study is typically dominated by investigations into capillary adhesion, but relatively recent interest in carbon nanotubes and biomimetic devices have spurred interest in intermolecular forces as another source of micro- and nano-scale adhesion. We present here a far-field model for ``dry'' adhesion. We consider a small number N of flexible beams interacting with each other via a typical Lennard-Jones 6-12 potential, and describe the behavior of the system as the ratio of bending rigidity to beam-beam attraction is reduced. Applications ranging from fibrillar systems to the comparatively stiff carbon nanotubes are discussed.

  16. Thin flexible intercalation anodes

    Energy Technology Data Exchange (ETDEWEB)

    Levy, S.C.; Cieslak, W.R.; Klassen, S.E.; Lagasse, R.R.

    1994-10-01

    Poly(acrylonitrile) fibers have been pyrolyzed under various conditions to form flexible carbon yarns capable of intercalating lithium ions. These fibers have also been formed into both woven and non woven cloths. Potentiostatic, potentiodynamic and galvanostatic tests have been conducted with these materials in several electrolytes. In some tests, a potential hold was used after each constant current charge and discharge. These tests have shown some of these flexible materials to reversibly intercalate lithium ions to levels that are suitable for use as a practical battery anode.

  17. Flexible energy systems

    DEFF Research Database (Denmark)

    Lund, Henrik

    2003-01-01

    The paper discusses and analyses diffent national strategies and points out key changes in the energy system in order to achieve a system which can benefit from a high percentage of wind and CHP without having surplus production problems, introduced here as a flexible energy system....

  18. Flexible Classroom Furniture

    Science.gov (United States)

    Kim Hassell,

    2011-01-01

    Classroom design for the 21st-century learning environment should accommodate a variety of learning skills and needs. The space should be large enough so it can be configured to accommodate a number of learning activities. This also includes furniture that provides flexibility and accommodates collaboration and interactive work among students and…

  19. Flexible Language Interoperability

    DEFF Research Database (Denmark)

    Ekman, Torbjörn; Mechlenborg, Peter; Schultz, Ulrik Pagh

    2007-01-01

    of the language. In this paper, we present a highly flexible yet efficient approach to hosting multiple programming languages on an object-oriented virtual machine. Our approach is based on extending the interface of each class with language-specific wrapper methods, offering each language a tailored view...

  20. Flexible Mental Calculation.

    Science.gov (United States)

    Threlfall, John

    2002-01-01

    Suggests that strategy choice is a misleading characterization of efficient mental calculation and that teaching mental calculation methods as a whole is not conducive to flexibility. Proposes an alternative in which calculation is thought of as an interaction between noticing and knowledge. Presents an associated teaching approach to promote…

  1. Flexible cultural repertoires

    DEFF Research Database (Denmark)

    Lindegaard, Marie Rosenkrantz; Zimmermann, Francisca

    2017-01-01

    rejection of crime-involved youth. Young men who perform flexible cultural repertoires, by incorporating and shifting between gang and decent repertoires, experience low victimization due to their adaptation to crime-involved youth. Findings emphasize the importance of detailed investigations of the way...

  2. Flexible metal bellows

    CERN Multimedia

    1975-01-01

    A set of flexible metal bellows being fatigue-tested by repeated offset motion. Such bellows assemblies were used in the SPS vacuum system at places where , for instance, beam stoppers and collimators had to be moved frequently in and out of the beam path.

  3. Flexible Query Answering Systems

    DEFF Research Database (Denmark)

    This book constitutes the refereed proceedings of the 12th International Conference on Flexible Query Answering Systems, FQAS 2017, held in London, UK, in June 2017. The 21 full papers presented in this book together with 4 short papers were carefully reviewed and selected from 43 submissions...

  4. Wave-induced dynamics of flexible blades

    CERN Document Server

    Luhar, M

    2015-01-01

    We present an experimental and numerical study that describes the motion of flexible blades, scaled to be dynamically similar to natural aquatic vegetation, forced by wave-induced oscillatory flows. For the conditions tested, blade motion is governed primarily by two dimensionless variables: (i) the Cauchy number, $Ca$, which represents the ratio of the hydrodynamic forcing to the restoring force due to blade stiffness, and (ii) the ratio of the blade length to the wave orbital excursion, $L$. For flexible blades with $Ca \\gg 1$, the relationship between drag and velocity can be described by two different scaling laws at the large- and small-excursion limits. For large excursions ($L \\ll 1$), the flow resembles a unidirectional current and the scaling laws developed for steady-flow reconfiguration studies hold. For small excursions ($L \\gg 1$), the beam equations may be linearized and a different scaling law for drag applies. The experimental force measurements suggest that the small-excursion scaling applies...

  5. Role of Pectoral Fin Flexibility in Robotic Fish Performance

    Science.gov (United States)

    Bazaz Behbahani, Sanaz; Tan, Xiaobo

    2017-08-01

    Pectoral fins play a vital role in the maneuvering and locomotion of fish, and they have become an important actuation mechanism for robotic fish. In this paper, we explore the effect of flexibility of robotic fish pectoral fins on the robot locomotion performance and mechanical efficiency. A dynamic model for the robotic fish is presented, where the flexible fin is modeled as multiple rigid elements connected via torsional springs and dampers. Blade element theory is used to capture the hydrodynamic force on the fin. The model is validated with experimental results obtained on a robotic fish prototype, equipped with 3D-printed fins of different flexibility. The model is then used to analyze the impacts of fin flexibility and power/recovery stroke speed ratio on the robot swimming speed and mechanical efficiency. It is found that, in general, flexible fins demonstrate advantages over rigid fins in speed and efficiency at relatively low fin-beat frequencies, while rigid fins outperform flexible fins at higher frequencies. For a given fin flexibility, the optimal frequency for speed performance differs from the optimal frequency for mechanical efficiency. In addition, for any given fin, there is an optimal power/recovery stroke speed ratio, typically in the range of 2-3, that maximizes the speed performance. Overall, the presented model offers a promising tool for fin flexibility and gait design, to achieve speed and efficiency objectives for robotic fish actuated with pectoral fins.

  6. Flexible composite film for printed circuit board

    Science.gov (United States)

    Yabe, K.; Asakura, M.; Tanaka, H.; Soda, A.

    1982-01-01

    A flexible printed circuit for a printed circuit board in which layers of reaction product composed of a combination of phenoxy resin - polyisocyanate - brominated epoxy resin, and in which the equivalent ratio of those functional groups is hydroxyl group: isocyanate group: epoxy group - 1 : 0.2 to 2 : 0.5 to 3 are laminated on at least one side of saturated polyester film is discussed.

  7. Adding flexibility to physician training.

    Science.gov (United States)

    Mahady, Suzanne E

    2011-05-02

    Demographic changes among junior doctors are driving demand for increased flexibility in advanced physician training, but flexible training posts are lacking. Suitable flexible training models include flexible full-time, job-share and part-time positions. Major barriers to establishing flexible training positions include difficulty in finding job-share partners, lack of funding for creating supernumerary positions, and concern over equivalence of educational quality compared with full-time training. Pilot flexible training positions should be introduced across the medical specialties and educational outcomes examined prospectively.

  8. Aggregating energy flexibilities under constraints

    DEFF Research Database (Denmark)

    Valsomatzis, Emmanouil; Pedersen, Torben Bach; Abello, Alberto

    2016-01-01

    The flexibility of individual energy prosumers (producers and/or consumers) has drawn a lot of attention in recent years. Aggregation of such flexibilities provides prosumers with the opportunity to directly participate in the energy market and at the same time reduces the complexity of scheduling...... the energy units. However, aggregated flexibility should support normal grid operation. In this paper, we build on the flex-offer (FO) concept to model the inherent flexibility of a prosumer (e.g., a single flexible consumption device such as a clothes washer). An FO captures flexibility in both time...

  9. Structural, magnetic and specific heat studies of Bi1-xLaxMn2O5 (x=0, 0.1, 0.2 and 0.3) multiferroics

    Science.gov (United States)

    Sagar, E.; Kumar, N. Pavan; Reddy, P. Venugopal

    2016-12-01

    A series of multiferroic materials with the compositional formula Bi1-xLaxMn2O5 (x=0, 0.1, 0.2 and 0.3) in single phase were prepared by the solid state reaction technique. After characterizing the samples structurally, a systematic investigation of specific heat and magnetization studies were carried out over the temperature range, 2-300 K. Based on these studies, it has been observed that the magnetization versus temperature plots of all the samples are found to split in the ZFC and FC modes and the observed behavior is explained on the basis of magnetic inhomogeneity. Finally, using the specific heat data, the magnetic entropy values were calculated using Einstein model.

  10. Specific heat and correlation between resistivity and thermoelectric power of GdBa{sub 2}(Cu{sub 1-x}Mn{sub x}){sub 3}O{sub 7-{delta}} HTSC system for x {<=} 0.02

    Energy Technology Data Exchange (ETDEWEB)

    Gahtori, Bhasker [Superconductivity and Cryogenics Division, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India)], E-mail: bhaskergahtori@yahoo.co.in; Agarwal, S.K. [Superconductivity and Cryogenics Division, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Chakraborty, Tirthankar [Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata 700032 (India); Rao, Ashok [Department of Physics, Manipal Institute of Technology, Manipal 576104 (India); Kuo, Y.-K. [Department of Physics, National Dong-Hwa University, Hualien 974, Taiwan (China)

    2009-01-01

    In this communication we present some theoretical results of specific heat and thermoelectric power of the superconductor GdBa{sub 2}(Cu{sub 1-x}Mn{sub x}){sub 3}O{sub 7-{delta}} (for x {<=} 0.02). A model based on separate electronic and phononic contributions is used for the interpretation of the specific heat data while a narrow band model is used for the analysis of thermoelectric power. On the basis of these models two main conclusions have been drawn about the relative effects of different Mn contents: (1) the observed fluctuation effects near T{sub c} whose strength increases with increasing Mn content and (2) Mn produces mainly electronic effects for lower Mn contents, while for higher doping levels (x > 0.0075) Mn predominantly causes carrier-Mn scattering process.

  11. FLEXIBLE GEIGER COUNTER

    Science.gov (United States)

    Richter, H.G.; Gillespie, A.S. Jr.

    1963-11-12

    A flexible Geiger counter constructed from materials composed of vinyl chloride polymerized with plasticizers or co-polymers is presented. The counter can be made either by attaching short segments of corrugated plastic sleeving together, or by starting with a length of vacuum cleaner hose composed of the above materials. The anode is maintained substantially axial Within the sleeving or hose during tube flexing by means of polystyrene spacer disks or an easily assembled polyethylene flexible cage assembly. The cathode is a wire spiraled on the outside of the counter. The sleeving or hose is fitted with glass end-pieces or any other good insulator to maintain the anode wire taut and to admit a counting gas mixture into the counter. Having the cathode wire on the outside of the counter substantially eliminates the objectional sheath effect of prior counters and permits counting rates up to 300,000 counts per minute. (AEC)

  12. Flexible Metasurface Holograms

    CERN Document Server

    Burch, James; Chen, Xianzhong; Di Falco, Andrea

    2016-01-01

    Metasurface holograms are typically fabricated on rigid substrates. Here we experimentally demonstrate broadband, flexible, conformable, helicity multiplexed metasurface holograms operating in the visible range, offering increased potential for real life out-of-the-lab applications. Two symmetrically distributed holographic images are obtained when circularly polarized light impinges on the reflective-type metasurface positioned on non- planar targets. The two off-axis images with high fidelity are interchangeable by controlling the helicity of incident light. Our metasurface features the arrangement of spatially varying gold nanorods on a flexible, conformable epoxy resist membrane to realize a Pancharatnam- Berry phase profile. These results pave the way to practical applications including polarization manipulation, beam steering, novel lenses, and holographic displays.

  13. Flexible Laser Metal Cutting

    DEFF Research Database (Denmark)

    Villumsen, Sigurd; Jørgensen, Steffen Nordahl; Kristiansen, Morten

    2014-01-01

    This paper describes a new flexible and fast approach to laser cutting called ROBOCUT. Combined with CAD/CAM technology, laser cutting of metal provides the flexibility to perform one-of-a-kind cutting and hereby realises mass production of customised products. Today’s laser cutting techniques...... possess, despite their wide use in industry, limitations regarding speed and geometry. Research trends point towards remote laser cutting techniques which can improve speed and geometrical freedom and hereby the competitiveness of laser cutting compared to fixed-tool-based cutting technology...... such as punching. This paper presents the concepts and preliminary test results of the ROBOCUT laser cutting technology, a technology which potentially can revolutionise laser cutting....

  14. Flexible training under threat.

    Science.gov (United States)

    Houghton, Anita; Eaton, Jennifer

    2002-10-01

    As the number of women in medicine and the general demand for a better work-life balance rises, flexible training is an increasingly important mechanism for maintaining the medical workforce. The new pay deal, together with entrenched cultural attitudes, are potential threats. Ways forward include more substantive part-time posts, more part-time opportunities at consultant level, and using positive experiences as a way of tackling attitudes in the less accepting specialties.

  15. Flexible Land Administration

    DEFF Research Database (Denmark)

    Enemark, Stig

    2014-01-01

    Security of tenure is widely considered to be the missing piece of the puzzle when it comes to eradication of poverty. And, as explained in the previous issue of Geoinformatics, the European Union is now placing land rights at the heart of EU development policy. This article presents a way forwar...... in terms of building flexible and "fit-for-purpose" land administration systems in developing countries. This will ensure security of tenure for all and sustainable management of the use of land....

  16. More flexibility for DESY

    CERN Multimedia

    2003-01-01

    In the future, budgeting at DESY will be more efficient. The 16 associated research centers are to be granted a wider margin in matters of finance and human resources. The Budget Committee of the German Bundestag has agreed to abstain from mandatory staff appointments. The current pre-determined "job pyramid" will be replaced by a more flexible mechanism, so that the conclusion of fixed labor contracts can more closely follow the needs of research (1 page).

  17. Industrial Fuel Flexibility Workshop

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2006-09-01

    On September 28, 2006, in Washington, DC, ITP and Booz Allen Hamilton conducted a fuel flexibility workshop with attendance from various stakeholder groups. Workshop participants included representatives from the petrochemical, refining, food and beverage, steel and metals, pulp and paper, cement and glass manufacturing industries; as well as representatives from industrial boiler manufacturers, technology providers, energy and waste service providers, the federal government and national laboratories, and developers and financiers.

  18. Flexible Land Administration

    DEFF Research Database (Denmark)

    Enemark, Stig

    2014-01-01

    Security of tenure is widely considered to be the missing piece of the puzzle when it comes to eradication of poverty. And, as explained in the previous issue of Geoinformatics, the European Union is now placing land rights at the heart of EU development policy. This article presents a way forwar...... in terms of building flexible and "fit-for-purpose" land administration systems in developing countries. This will ensure security of tenure for all and sustainable management of the use of land....

  19. Flexible Data Link

    Science.gov (United States)

    2015-04-01

    reconfiguring the waveform characteristics (on-the-fly) based on the engagement environment. Therefore, flexibility was the highest priority in the design of...the aircraft to a ground antenna . Utilizing the threshold system requirements (100 km range), we calculate the multipath of the aircraft as it...approaches the ground antenna . Figure 3: Multipath scenario #1 The calculation of the reflected path (denoted as A + C in Figure 3) is found through the

  20. Designing structural supply chain flexibility

    NARCIS (Netherlands)

    Mulinski, Ksawery Jan

    2012-01-01

    In a continuously changing business environment the role of supply chain flexibility is constantly increasing. A flexible supply chain can ensure survival in quickly changing market conditions as well as enable sustainable growth. This thesis explores the topic of supply chain flexibility with focus

  1. Flexible Scheduling: Making the Transition

    Science.gov (United States)

    Creighton, Peggy Milam

    2008-01-01

    Citing literature that supports the benefits of flexible scheduling on student achievement, the author exhorts readers to campaign for flexible scheduling in their library media centers. She suggests tips drawn from the work of Graziano (2002), McGregor (2006) and Stripling (1997) for making a smooth transition from fixed to flexible scheduling:…

  2. Designing structural supply chain flexibility

    NARCIS (Netherlands)

    Mulinski, Ksawery Jan

    2012-01-01

    In a continuously changing business environment the role of supply chain flexibility is constantly increasing. A flexible supply chain can ensure survival in quickly changing market conditions as well as enable sustainable growth. This thesis explores the topic of supply chain flexibility with focus

  3. Measuring and Comparing Energy Flexibilities

    DEFF Research Database (Denmark)

    Valsomatzis, Emmanouil; Hose, Katja; Pedersen, Torben Bach

    2015-01-01

    Flexibility in energy supply and demand becomes more and more important with increasing Renewable Energy Sources (RES) production and the emergence of the Smart Grid. So-called prosumers, i.e., entities that produce and/or consume energy, can offer their inherent flexibilities through so......-called demand response and thus help stabilize the energy markets. Thus, prosumer flexibility becomes valuable and the ongoing Danish project TotalFlex [1] explores the use of prosumer flexibility in the energy market using the concept of a flex-offer [2], which captures energy flexibilities in time and...... induced by time and amount individually, and by their com- bination. To this end, we introduce several flexibility measures that take into account the combined effect of time and energy on flex-offer flexibility and discuss their respective pros and cons through a number of realistic examples....

  4. Flexible Volumetric Structure

    Science.gov (United States)

    Cagle, Christopher M. (Inventor); Schlecht, Robin W. (Inventor)

    2014-01-01

    A flexible volumetric structure has a first spring that defines a three-dimensional volume and includes a serpentine structure elongatable and compressible along a length thereof. A second spring is coupled to at least one outboard edge region of the first spring. The second spring is a sheet-like structure capable of elongation along an in-plane dimension thereof. The second spring is oriented such that its in-plane dimension is aligned with the length of the first spring's serpentine structure.

  5. Flexible composite radiation detector

    Science.gov (United States)

    Cooke, D. Wayne; Bennett, Bryan L.; Muenchausen, Ross E.; Wrobleski, Debra A.; Orler, Edward B.

    2006-12-05

    A flexible composite scintillator was prepared by mixing fast, bright, dense rare-earth doped powdered oxyorthosilicate (such as LSO:Ce, LSO:Sm, and GSO:Ce) scintillator with a polymer binder. The binder is transparent to the scintillator emission. The composite is seamless and can be made large and in a wide variety of shapes. Importantly, the composite can be tailored to emit light in a spectral region that matches the optimum response of photomultipliers (about 400 nanometers) or photodiodes (about 600 nanometers), which maximizes the overall detector efficiency.

  6. Composite Flexible Blanket Insulation

    Science.gov (United States)

    Kourtides, Demetrius A. (Inventor); Pitts, William C. (Inventor); Goldstein, Howard E. (Inventor); Sawko, Paul M. (Inventor)

    1991-01-01

    Composite flexible multilayer insulation systems (MLI) were evaluated for thermal performance and compared with the currently used fibrous silica (baseline) insulation system. The systems described are multilayer insulations consisting of alternating layers of metal foil and scrim ceramic cloth or vacuum metallized polymeric films quilted together using ceramic thread. A silicon carbide thread for use in the quilting and the method of making it are also described. These systems are useful in providing lightweight insulation for a variety of uses, particularly on the surface of aerospace vehicles subject to very high temperatures during flight.

  7. Flexible plasma linear antenna

    Science.gov (United States)

    Zhao, Jiansen; Wang, Shengzheng; Wu, Huafeng; Liu, Yue; Chang, Yongmeng; Chen, Xinqiang

    2017-02-01

    In this work, we introduce a type of plasma antenna that was fabricated using flexible materials and excited using a 5-20 kHz alternating current (ac) power supply. The results showed that the antenna characteristics, including the impedance, the reflection coefficient (S11), the radiation pattern, and the gain, can be controlled rapidly and easily by varying both the discharge parameters and the antenna shapes. The scope for reconfiguration is greatly enhanced when the antenna shape is changed from a monopole to a helix configuration. Additionally, the antenna polarization can also be adjusted by varying the antenna shapes.

  8. Asymmetric Flexible Supercapacitor Stack

    Directory of Open Access Journals (Sweden)

    Leela Mohana Reddy A

    2008-01-01

    Full Text Available AbstractElectrical double layer supercapacitor is very significant in the field of electrical energy storage which can be the solution for the current revolution in the electronic devices like mobile phones, camera flashes which needs flexible and miniaturized energy storage device with all non-aqueous components. The multiwalled carbon nanotubes (MWNTs have been synthesized by catalytic chemical vapor deposition technique over hydrogen decrepitated Mischmetal (Mm based AB3alloy hydride. The polymer dispersed MWNTs have been obtained by insitu polymerization and the metal oxide/MWNTs were synthesized by sol-gel method. Morphological characterizations of polymer dispersed MWNTs have been carried out using scanning electron microscopy (SEM, transmission electron microscopy (TEM and HRTEM. An assymetric double supercapacitor stack has been fabricated using polymer/MWNTs and metal oxide/MWNTs coated over flexible carbon fabric as electrodes and nafion®membrane as a solid electrolyte. Electrochemical performance of the supercapacitor stack has been investigated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy.

  9. Screen-printed flexible MRI receive coils.

    Science.gov (United States)

    Corea, Joseph R; Flynn, Anita M; Lechêne, Balthazar; Scott, Greig; Reed, Galen D; Shin, Peter J; Lustig, Michael; Arias, Ana C

    2016-03-10

    Magnetic resonance imaging is an inherently signal-to-noise-starved technique that limits the spatial resolution, diagnostic image quality and results in typically long acquisition times that are prone to motion artefacts. This limitation is exacerbated when receive coils have poor fit due to lack of flexibility or need for padding for patient comfort. Here, we report a new approach that uses printing for fabricating receive coils. Our approach enables highly flexible, extremely lightweight conforming devices. We show that these devices exhibit similar to higher signal-to-noise ratio than conventional ones, in clinical scenarios when coils could be displaced more than 18 mm away from the body. In addition, we provide detailed material properties and components performance analysis. Prototype arrays are incorporated within infant blankets for in vivo studies. This work presents the first fully functional, printed coils for 1.5- and 3-T clinical scanners.

  10. 不同原料组分的配合饲料比热模型%Model of formula feed specific heat based on different components of feed ingredients

    Institute of Scientific and Technical Information of China (English)

    王红英; 高蕊; 李军国; 杨洁; 康宏彬

    2013-01-01

    During the processes of conditioning, extrusion and cooling,the consistency and stability of feed products are the most important problems at present. In order to determine the heat and mass transfer properties of formula feed in these processes, the effects of different components of feed ingredients on specific heat were investigated using the continuous differential scanning calorimeter (DSC) method. With the help of a computer program, the apparatus provided different energy fluxes for the active cell containing texting sample and the reference cell containing air, in order to keep the two cells at the same temperature. By analyzing the energy differences between them, the specific heat of a sample could be obtained for the specific heat capacity of raw materials which had a great influence on the feed production. Up to now, there were many research reports on onefold raw material specific heat, however, the studies on formula feed specific heat were very limited. The works in this study took piglet formula feed as an example. The experiments in three factors with five levels were designed by a quadratic orthogonal rotation approach to attempt to determining the specific heat of the mixture of maize (46%-70%), soybean meal (9%-18%) and whey powder (2%-10%). Maize and soybean meal shared a larger proportion in piglet formula feed than other feed ingredients, while whey powder was a type of thermo-sensitive substance that had a great influence on specific heat. The result showed that the specific heat increased with an increase of heating temperature for each onefold raw material, but the whey powder appeared to peak at 58.8℃,which may be the glass transition temperature of whey powder. This situation influenced microstructure and it was harmful to the nutritional quality of whey powder and the palatability of pellet feed. Based on the experiments, a model of specific heat of maize,soybean meal and whey powder mass fraction was established by regression

  11. The Flexibility Hypothesis of Healing.

    Science.gov (United States)

    Hinton, Devon E; Kirmayer, Laurence J

    2017-03-01

    Theories of healing have attempted to identify general mechanisms that may work across different modalities. These include altering expectations, remoralization, and instilling hope. In this paper, we argue that many forms of healing and psychotherapy may work by inducing positive psychological states marked by flexibility or an enhanced ability to shift cognitive sets. Healing practices may induce these states of cognitive and emotional flexibility through specific symbolic interventions we term "flexibility primers" that can include images, metaphors, music, and other media. The flexibility hypothesis suggests that cognitive and emotional flexibility is represented, elicited, and enacted through multiple modalities in healing rituals. Identifying psychological processes and cultural forms that evoke and support cognitive and emotional flexibility provides a way to understand the cultural specificity and potential efficacy of particular healing practices and can guide the design of interventions that promote resilience and well-being.

  12. 纳米SiO2在低熔点熔盐中的分散对其比热容的影响%Effect of Nanoparticles Dispersion on Enhancing the Specific Heat of the Low Melting Point Salt

    Institute of Scientific and Technical Information of China (English)

    吴玉庭; 张璐迪; 马重芳; 李英

    2016-01-01

    为提高低熔点熔盐Ca(NO3)2-KNO3-NaNO3-LiNO3的比热容,采用超声振荡法将低熔点熔盐与30 nm的SiO2纳米粒子复合制备出低熔点熔盐纳米流体,研究了纳米粒子对低熔点盐比热容的影响及制备过程中影响纳米粒子分散的关键因素:超声振荡时间和超声振荡频率.采用同步热分析仪( DSC)测量熔盐比热容;采用扫描电镜表征低熔点熔盐纳米流体的微观表面结构,观察纳米粒子分布情况.研究结果表明:分散均匀的SiO2纳米粒子可以提高低熔点盐纳米流体的比热容,纳米熔盐比热容平均值达到1.86 J/( g·K)左右,在200~350益温度范围内,比热容提高率为14%~22%,并通过实验验证了超声波分散法是制备熔盐纳米流体的一种稳定可靠的方法.%In order to enhance specific heat capacity of the low melting point salt ( Ca ( NO3 ) 2-KNO3-NaNO3-LiNO3 ) , low melting point salt( LMPS) nanofluid was prepared by adding SiO2 nanoparticles with size of 20 nm into the low melting point salt with using ultra-sonication. The influence of nanoparticles dispersion on enhancing specific heat of the low melting point salt was investigated by experiments. Two factors of ultra-sonication ( time for sonication and frequency ) were researched. The specific heat capacity was measured by using a differential scanning Calorimetry ( DSC ) , and the microstructures following solidification was observed by using a scanning electron microscope ( SEM) . Results show that the specific heat of the LMPS nanofluid is significantly improved, when nanoparticles disperse evenly in the LMPS nanofluid. The average specific heat of the LMPS nanofluid is 1. 868 J/( g·K ) and the enhancement of the specific heat is 14% ~22% in 200~350℃. Moreover, it is verified the fact that the ultra-sonication is a stable method of preparing LMPS nanofluid.

  13. Flexible cultural repertoires

    DEFF Research Database (Denmark)

    Lindegaard, Marie Rosenkrantz

    2016-01-01

    Despite extensive studies of street culture and the risks of offending and victimization in urban marginalized areas, little is known about the role of cultural repertoires for variation in victimization risks among young men not involved in crime. Based on two ethnographic studies, conducted...... varying cultural repertoires, in particularly heterogeneous flexible repertoires, influence offending and victimization patterns among young men in high-risk settings....... independently of the authors in neighbouring township areas of Cape Town, we offer insights into patterns of victimization among young men not involved in crime who live and attend school in the townships. Young men who perform decent cultural repertoires are highly exposed to victimization due to their moral...

  14. Conformational flexibility of aspartame.

    Science.gov (United States)

    Toniolo, Claudio; Temussi, Pierandrea

    2016-05-01

    L-Aspartyl-L-phenylalanine methyl ester, better known as aspartame, is not only one of the most used artificial sweeteners, but also a very interesting molecule with respect to the correlation between molecular structure and taste. The extreme conformational flexibility of this dipeptide posed a huge difficulty when researchers tried to use it as a lead compound to design new sweeteners. In particular, it was difficult to take advantage of its molecular model as a mold to infer the shape of the, then unknown, active site of the sweet taste receptor. Here, we follow the story of the 3D structural aspects of aspartame from early conformational studies to recent docking into homology models of the receptor. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 376-384, 2016.

  15. Cubic-tetragonal phase transition in Ca{sub 0.04}Sr{sub 0.96}TiO{sub 3}: a combined specific heat and neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Gallardo, M C [Departamento de Fisica de la Materia Condensada, Instituto de Ciencia de Materiales de Sevilla, Universidad de Sevilla-CSIC, PO Box 1065, 41080 Sevilla (Spain); Becerro, A I [Departamento de Quimica Inorganica, Instituto de Ciencia de Materiales de Sevilla, Universidad de Sevilla-CSIC, Avenida Americo Vespucio s/n, 41092 Sevilla (Spain); Romero, F J [Departamento de Fisica de la Materia Condensada, Instituto de Ciencia de Materiales de Sevilla, Universidad de Sevilla-CSIC, PO Box 1065, 41080 Sevilla (Spain); Cerro, J del [Departamento de Fisica de la Materia Condensada, Instituto de Ciencia de Materiales de Sevilla, Universidad de Sevilla-CSIC, PO Box 1065, 41080 Sevilla (Spain); Seifert, F [Bayerisches Geoinstitut, Universitaet Bayreuth, 95440-Bayreuth (Germany); Redfern, S A T [Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge (United Kingdom)

    2003-01-22

    The specific heat corresponding to the tetragonal-to-cubic transition in Ca{sub 0.04}Sr{sub 0.96}TiO{sub 3} perovskite has been measured by conduction calorimetry. The order parameter of the transition has been obtained by means of neutron diffraction at low temperatures. Comparison of calorimetric data with the evolution of the order parameter indicates that this transition seems to follow a mean field Landau potential as in SrTiO{sub 3}. The linear behaviour of the excess of entropy versus temperature suggests that a 2-4 Landau potential is sufficient to describe the transition.

  16. Effect of variable thermal conductivity and specific heat capacity on the calculation of the critical metal hydride thickness for Ti1.1CrMn

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rokni, Masoud

    2014-01-01

    High pressure metal hydrides have been recently considered as one of the most promising hydrogen solid storage options for on - board applications. Unfortunately the high purchasing costs related to these materials and the complexity related to building a scaled high pressure tank system...... model is applied to the metal hydride system, with Ti 1.1 CrMn as the absorbing alloy, to predict the weight fraction of absorbed hydrogen and solid bed temperat ure . Dependencies of thermal conductivity and specific heat capacity upon pressure and hydrogen content respectively , are accounted for...

  17. Magnetoelectric Nanocomposites for Flexible Electronics

    KAUST Repository

    Al-Nassar, Mohammed Y.

    2015-09-01

    Flexibility, low cost, versatility, miniaturization and multi-functionality are key aspects driving research and innovation in many branches of the electronics industry. With many anticipated emerging applications, like wearable, transparent and biocompatible devices, interest among the research community in pursuit for novel multifunctional miniaturized materials have been amplified. In this context, multiferroic polymer-based nanocomposites, possessing both ferroelectricity and ferromagnetism, are highly appealing. Most importantly, these nanocomposites possess tunable ferroelectric and ferromagnetic properties based on the parameters of their constituent materials as well as the magnetoelectric effect, which is the coupling between electric and magnetic properties. This tunability and interaction is a fascinating fundamental research field promising tremendous potential applications in sensors, actuators, data storage and energy harvesting. This dissertation work is devoted to the investigation of a new class of multiferroic polymer-based flexible nanocomposites, which exhibits excellent ferromagnetism and ferroelectricity simultaneously at room temperature, with the goal of understanding and optimizing the origin of their magnetoelectric coupling. The nanocomposites consist of high aspect ratio ferromagnetic nanowires (NWs) embedded inside a ferroelectric co-polymer, poly(vinylindene fluoride-trifluoroethylene), P(VDF-TrFE) matrix. First, electrochemical deposition of ferromagnetic NWs inside anodic aluminum oxide membranes is discussed. Characterization of electrodeposited iron, nickel and highly magnetostrictive iron-gallium alloy NWs was done using XRD, electron and magnetic force microscopy. Second, different nanocomposite films have been fabricated by means of spin coating and drop casting techniques. The effect of incorporation of NWs inside the ferroelectric polymer on its electroactive phase is discussed. The remanent and saturation polarization as well

  18. Dynamics of flexible fibers in shear flow

    Energy Technology Data Exchange (ETDEWEB)

    Słowicka, Agnieszka M.; Wajnryb, Eligiusz; Ekiel-Jeżewska, Maria L., E-mail: mekiel@ippt.pan.pl [Institute of Fundamental Technological Research, Polish Academy of Sciences, Pawińskiego 5b, 02-106 Warsaw (Poland)

    2015-09-28

    Dynamics of flexible non-Brownian fibers in shear flow at low-Reynolds-number are analyzed numerically for a wide range of the ratios A of the fiber bending force to the viscous drag force. Initially, the fibers are aligned with the flow, and later they move in the plane perpendicular to the flow vorticity. A surprisingly rich spectrum of different modes is observed when the value of A is systematically changed, with sharp transitions between coiled and straightening out modes, period-doubling bifurcations from periodic to migrating solutions, irregular dynamics, and chaos.

  19. Building Highly Flexible Polyelectrolyte Nanotubes

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ Flexibility of polyelectrolyte nanotubes is necessary if they are to be exploited in applications such as developing photoelectric devices with strong mechanical properties. In a recent attempt, high flexibility has been observed from such nanotubes prepared by a research team headed by Prof. Li Junbai of the CAS Institute of Chemistry (ICCAS).

  20. On flexible and rigid nouns

    DEFF Research Database (Denmark)

    Rijkhoff, Jan

    2008-01-01

    , Non-Verb, Modifier), there are also flexible word classes within the rigid lexical category Noun (Set Noun, Sort Noun, General Noun). Members of flexible word classes are characterized by their vague semantics, which in the case of nouns means that values for the semantic features Shape...

  1. On flexible and rigid nouns

    DEFF Research Database (Denmark)

    Rijkhoff, Jan

    2010-01-01

    This article argues that in addition to the major flexible lexical categories in Hengeveld’s classification of parts of speech systems (Contentive, Non-Verb, Modifier), there are also flexible word classes within the rigid lexical category Noun (Set Noun, Sort Noun, General Noun). Members...

  2. Function Machines & Flexible Algebraic Thought.

    Science.gov (United States)

    Davis, Gary E.; McGowen, Mercedes A.

    This paper explores how college students understand ideas of functions, and which representations are productive for them in promoting their ability to work flexibly across representations. The study used pre- and post-test scores, and triangulations via student self evaluations, to generate a hypothesis related to flexible thinking and success in…

  3. Sensor Technologies on Flexible Substrates

    Science.gov (United States)

    Koehne, Jessica

    2016-01-01

    NASA Ames has developed sensor technologies on flexible substrates integrated into textiles for personalized environment monitoring and human performance evaluation. Current technologies include chemical sensing for gas leak and event monitoring and biological sensors for human health and performance monitoring. Targeted integration include next generation EVA suits and flexible habitats.

  4. Retirement Flexibility and Portfolio Choice

    NARCIS (Netherlands)

    Adema, Y.; Bonenkamp, J.; Meijdam, A.C.

    2011-01-01

    This paper explores the interaction between retirement flexibility and portfolio choice in an overlapping-generations model. We analyse this interaction both in a partial-equilibrium and general-equilibrium setting. Retirement flexibility is often seen as a hedge against capital-market risks which

  5. Flexible Coupling Corrects Shaft Misalinements

    Science.gov (United States)

    Mayo, R. A.

    1983-01-01

    Proposed flexible coupling provides nearly error free measurements of shaft rotation in presence of misalinements between shaft and position sensing transducer. Intended to be used in situations in which input or output shaft is mounted on flexible joint. Its function is to insure equal input and output angular velocities by forcing input and output shafts to remain parallel.

  6. Thermal entanglement and sharp specific-heat peak in an exactly solved spin-1/2 Ising-Heisenberg ladder with alternating Ising and Heisenberg inter-leg couplings

    Science.gov (United States)

    Rojas, Onofre; Strečka, J.; de Souza, S. M.

    2016-11-01

    The spin-1/2 Ising-Heisenberg two-leg ladder accounting for alternating Ising and Heisenberg inter-leg couplings in addition to the Ising intra-leg coupling is rigorously mapped onto to a mixed spin-(3/2,1/2) Ising-Heisenberg diamond chain with the nodal Ising spins S = 3 / 2 and the interstitial spin-1/2 Heisenberg dimers. The latter effective model with higher-order interactions between the nodal and interstitial spins is subsequently exactly solved within the transfer-matrix method. The model under investigation exhibits five different ground states: ferromagnetic, antiferromagnetic, superantiferromagnetic and two types of frustrated ground states with a non-zero residual entropy. A detailed study of thermodynamic properties reveals an anomalous specific-heat peak at low enough temperatures, which is strongly reminiscent because of its extraordinary height and sharpness to an anomaly accompanying a phase transition. It is convincingly evidenced, however, that the anomalous peak in the specific heat is finite and it comes from vigorous thermal excitations from a two-fold degenerate ground state towards a macroscopically degenerate excited state. Thermal entanglement between the nearest-neighbor Heisenberg spins is also comprehensively explored by taking advantage of the concurrence. The threshold temperature delimiting a boundary between the entangled and disentangled parameter space may show presence of a peculiar temperature reentrance.

  7. Single-crystal growth of Pb{sub 2}V{sub 3}O{sub 9} and the Bose-Einstein condensed state of triplons studied by thermal conductivity, specific heat and magnetization measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kawamata, T [Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako 351-0198 (Japan); Sugawara, N; Uesaka, M; Kaneko, N; Koike, Y [Department of Applied Physics, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Kajiwara, T [Department of Chemistry, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578 (Japan); Yamane, H [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Koyama, K; Kudo, K; Kobayashi, N, E-mail: tkawamata@riken.j [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2009-03-01

    We have succeeded in growing large-size single crystals of the quasi-one-dimensional S = 1/2 spin-dimer system Pb{sub 2}V{sub 3}O{sub 9} by the floating-zone method, and also investigated the thermal conductivity, specific heat and magnetization in magnetic fields. In high magnetic fields, it has been found that the suppression of the thermal conductivity by the application of magnetic field is relaxed. This behavior is caused by the enhancement of the thermal conductivity due to triplons and/or phonons owing to the extension of the mean free path of triplons and/or phonons in the Bose-Einstein condensed (BEC) state of field-induced triplons. We have estimated the critical field H{sub c}(T) between the BEC state of triplons and the gapped normal state from the thermal conductivity, specific heat and magnetization measurements and obtained the value of the critical exponent oslash; approx 2.0 in [H{sub c}(T) - H{sub c}(0)] propor to T{sup o}e using H{sub c}(T)'s at low temperatures.

  8. Magnetic, specific heat and electrical transport properties of Frank-Kasper cage compounds RTM2Al20 [R  =  Eu, Gd and La; TM  =  V, Ti

    Science.gov (United States)

    Kumar, K. Ramesh; Nair, Harikrishnan S.; Christian, Reinke; Thamizhavel, A.; Strydom, André M.

    2016-11-01

    Single crystals of Frank-Kasper compounds RTM2Al20 (R  =  Eu, Gd and La; TM  =  V and Ti) were grown by self-flux method and their physical properties were investigated through magnetization (M), magnetic susceptibility (χ), specific heat (C P) and electrical resistivity (ρ) measurements. Powder x-ray diffraction studies and structural analysis showed that these compounds crystallize in the cubic crystal structure with the space group Fd\\bar{3}m . The magnetic susceptibility for the compounds EuTi2Al20 and GdTi2Al20 showed a sudden jump below the Néel temperature T N indicative of plausible double magnetic transition. Specific heat (C P) and electrical resistivity (ρ) measurements also confirm the first-order magnetic transition (FOMT) and possible double magnetic transitions. Temperature variation of heat capacity showed a sharp phase transition and huge C P value for the (Eu/Gd)Ti2Al20 compounds’ full width at half-maximum (FWHM) (text{P}}-γ T\\right)/{{T}3} versus T plot showed a maximum near 27 K for all the compounds indicating the presence of low frequency Einstein modes of vibrations. Resistivity measurements showed that all the samples behave as normal Fermi liquid type compounds and ρ (T) due to electron-phonon scattering follows Bloch-Grüneisen-Mott relation in the paramagnetic region.

  9. Functional aspects of protein flexibility

    DEFF Research Database (Denmark)

    Teilum, Kaare; Olsen, Johan G; Kragelund, Birthe B

    2009-01-01

    Proteins are dynamic entities, and they possess an inherent flexibility that allows them to function through molecular interactions within the cell, among cells and even between organisms. Appreciation of the non-static nature of proteins is emerging, but to describe and incorporate...... this into an intuitive perception of protein function is challenging. Flexibility is of overwhelming importance for protein function, and the changes in protein structure during interactions with binding partners can be dramatic. The present review addresses protein flexibility, focusing on protein-ligand interactions....... The thermodynamics involved are reviewed, and examples of structure-function studies involving experimentally determined flexibility descriptions are presented. While much remains to be understood about protein flexibility, it is clear that it is encoded within their amino acid sequence and should be viewed...

  10. [Flexible root posts].

    Science.gov (United States)

    Vadachkoriia, N R; Mandzhavidze, N A; Gumberidze, N Sh

    2009-02-01

    The article discusses the current state of restoration techniques of root canal treatment. Nowadays, technical progress allows manufacturers to develop flexible fiberglass posts, aspiring not only to an excellent aesthetics and mechanical properties (first of all, in comparison with metal and cast posts), but also to maintenance of their radio density and a wide range of forms. Growth of fiberglass posts popularity testifies to their clinical efficiency that also is confirmed by results of long-term researches. Introduction of fiberglass posts in a dental practice has rendered huge influence on restoration techniques of root canal treatment. Convincing factors of fiberglass posts superiority provide restoration the appearance similar with the natural dentition; possess close to dentine elasticity; creation of monolithic structure with hard tooth tissues and composite cement, posts, in case of need, can be easily adjusted on length, adhesive linkage of posts gives them additional stability. Modern researches have confirmed that only elastic, namely carbon fiber and the fiberglass posts made of modern technologies possess similar physical properties, as tooth structure. They can create reliable biomimetic design; solve a complex of aesthetic and functional restoration problems.

  11. Orthogonal flexible Rydberg aggregates

    Science.gov (United States)

    Leonhardt, K.; Wüster, S.; Rost, J. M.

    2016-02-01

    We study the link between atomic motion and exciton transport in flexible Rydberg aggregates, assemblies of highly excited light alkali-metal atoms, for which motion due to dipole-dipole interaction becomes relevant. In two one-dimensional atom chains crossing at a right angle adiabatic exciton transport is affected by a conical intersection of excitonic energy surfaces, which induces controllable nonadiabatic effects. A joint exciton-motion pulse that is initially governed by a single energy surface is coherently split into two modes after crossing the intersection. The modes induce strongly different atomic motion, leading to clear signatures of nonadiabatic effects in atomic density profiles. We have shown how this scenario can be exploited as an exciton switch, controlling direction and coherence properties of the joint pulse on the second of the chains [K. Leonhardt et al., Phys. Rev. Lett. 113, 223001 (2014), 10.1103/PhysRevLett.113.223001]. In this article we discuss the underlying complex dynamics in detail, characterize the switch, and derive our isotropic interaction model from a realistic anisotropic one with the addition of a magnetic bias field.

  12. Orthogonal flexible Rydberg aggregates

    CERN Document Server

    Leonhardt, K; Rost, J M

    2015-01-01

    We study the link between atomic motion and exciton transport in flexible Rydberg aggregates, assemblies of highly excited light alkali atoms, for which motion due to dipole-dipole interaction becomes relevant. In two one-dimensional atom chains crossing at a right angle adiabatic exciton transport is affected by a conical intersection of excitonic energy surfaces, which induces controllable non-adiabatic effects. A joint exciton/motion pulse that is initially governed by a single energy surface is coherently split into two modes after crossing the intersection. The modes induce strongly different atomic motion, leading to clear signatures of non-adiabatic effects in atomic density profiles. We have shown how this scenario can be exploited as an exciton switch, controlling direction and coherence properties of the joint pulse on the second of the chains [K.~Leonhardt {\\it et al.}, Phys.~Rev.~Lett. {\\bf 113} 223001 (2014)]. In this article we discuss the underlying complex dynamics in detail, characterise the ...

  13. Financial Key Ratios

    Directory of Open Access Journals (Sweden)

    Tănase Alin-Eliodor

    2014-08-01

    Full Text Available This article focuses on computing techniques starting from trial balance data regarding financial key ratios. There are presented activity, liquidity, solvency and profitability financial key ratios. It is presented a computing methodology in three steps based on a trial balance.

  14. Offer/Acceptance Ratio.

    Science.gov (United States)

    Collins, Mimi

    1997-01-01

    Explores how human resource professionals, with above average offer/acceptance ratios, streamline their recruitment efforts. Profiles company strategies with internships, internal promotion, cooperative education programs, and how to get candidates to accept offers. Also discusses how to use the offer/acceptance ratio as a measure of program…

  15. Compression Ratio Adjuster

    Science.gov (United States)

    Akkerman, J. W.

    1982-01-01

    New mechanism alters compression ratio of internal-combustion engine according to load so that engine operates at top fuel efficiency. Ordinary gasoline, diesel and gas engines with their fixed compression ratios are inefficient at partial load and at low-speed full load. Mechanism ensures engines operate as efficiently under these conditions as they do at highload and high speed.

  16. Specialized ratio analysis.

    Science.gov (United States)

    Wyer, J C; Salzinger, F H

    1983-01-01

    Many common management techniques have little use in managing a medical group practice. Ratio analysis, however, can easily be adapted to the group practice setting. Acting as broad-gauge indicators, financial ratios provide an early warning of potential problems and can be very useful in planning for future operations. The author has gathered a collection of financial ratios which were developed by participants at an education seminar presented for the Virginia Medical Group Management Association. Classified according to the human element, system component, and financial factor, the ratios provide a good sampling of measurements relevant to medical group practices and can serve as an example for custom-tailoring a ratio analysis system for your medical group.

  17. Ratio-Based Gradual Aggregation of Data

    DEFF Research Database (Denmark)

    Iftikhar, Nadeem

    2012-01-01

    cause data management and data storage issues. However, non-flexible and ineffective means of data aggregation not only reduce performance of database queries but also lead to erroneous reporting. This paper presents flexible and effective ratio-based methods for gradual data aggregation in databases....... Gradual data aggregation is a process that reduces data volume by converting the detailed data into multiple levels of summarized data as the data gets older. This paper also describes implementation strategies of the proposed methods based on standard database technology.......Majority of databases contain large amounts of data, gathered over long intervals of time. In most cases, the data is aggregated so that it can be used for analysis and reporting purposes. The other reason of data aggregation is to reduce data volume in order to avoid over-sized databases that may...

  18. IR Sensor Synchronizing Active Shutter Glasses for 3D HDTV with Flexible Liquid Crystal Lenses

    OpenAIRE

    Jeong In Han

    2013-01-01

    IR sensor synchronizing active shutter glasses for three-dimensional high definition television (3D HDTV) were developed using a flexible liquid crystal (FLC) lens. The FLC lens was made on a polycarbonate (PC) substrate using conventional liquid crystal display (LCD) processes. The flexible liquid crystal lens displayed a maximum transmission of 32% and total response time of 2.56 ms. The transmittance, the contrast ratio and the response time of the flexible liquid crystal lens were superio...

  19. Swarming: flexible roaming plans.

    Science.gov (United States)

    Partridge, Jonathan D; Harshey, Rasika M

    2013-03-01

    Movement over an agar surface via swarming motility is subject to formidable challenges not encountered during swimming. Bacteria display a great deal of flexibility in coping with these challenges, which include attracting water to the surface, overcoming frictional forces, and reducing surface tension. Bacteria that swarm on "hard" agar surfaces (robust swarmers) display a hyperflagellated and hyperelongated morphology. Bacteria requiring a "softer" agar surface (temperate swarmers) do not exhibit such a dramatic morphology. For polarly flagellated robust swarmers, there is good evidence that restriction of flagellar rotation somehow signals the induction of a large number of lateral flagella, but this scenario is apparently not relevant to temperate swarmers. Swarming bacteria can be further subdivided by their requirement for multiple stators (Mot proteins) or a stator-associated protein (FliL), secretion of essential polysaccharides, cell density-dependent gene regulation including surfactant synthesis, a functional chemotaxis signaling pathway, appropriate cyclic (c)-di-GMP levels, induction of virulence determinants, and various nutritional requirements such as iron limitation or nitrate availability. Swarming strategies are as diverse as the bacteria that utilize them. The strength of these numerous designs stems from the vantage point they offer for understanding mechanisms for effective colonization of surface niches, acquisition of pathogenic potential, and identification of environmental signals that regulate swarming. The signature swirling and streaming motion within a swarm is an interesting phenomenon in and of itself, an emergent behavior with properties similar to flocking behavior in diverse systems, including birds and fish, providing a convenient new avenue for modeling such behavior.

  20. Flexible armored blanket development

    Energy Technology Data Exchange (ETDEWEB)

    Roth, E.S.

    1978-05-01

    An exploratory development contract was undertaken on December 23, 1977 which had as its purpose the development and demonstration of a flexible armored blanket design suitable for providing ballistic protection to nuclear weapons during shipment. Objectives were to design and fabricate a prototype blanket which will conform to the weapon shape, is troop-handleable in the field, and which, singly or in multiple layers, can defeat a range of kinetic energy armor piercing (AP) ammunition potentially capable of damaging the critical portion of the nuclear weapon. Following empirical testing, including the firing of threat ammunition under controlled laboratory and field test conditions, materials were selected and assembled into two blanket designs, each weighing approximately 54 kg/m{sup 2} (11 lbs/ft{sup 2}) and estimated to cost from $111 to $180 per ft{sup 2} in production. A firing demonstration to evidence blanket performance against terrorist/light infantry weapons, heavy infantry weapons, and aircraft cannon was conducted for representatives of the DOD and interested Sandia employees on April 12, 1978. The blankets performed better than anticipated defeating bullets up to 7.62 mm x 51 mm AP with one layer and projectiles up to 23 mm HEI with two layers. Based on these preliminary tests it is recommended that development work be continued with the following objectives: (1) the selection by the DOD of priority applications, (2) the specific design and fabrication of sufficient quantities of armored blankets for field testing, (3) the evaluation of the blankets by DOD operational units, with reports to Sandia Laboratories to enable final design.

  1. Guideline Implementation: Processing Flexible Endoscopes.

    Science.gov (United States)

    Bashaw, Marie A

    2016-09-01

    The updated AORN "Guideline for processing flexible endoscopes" provides guidance to perioperative, endoscopy, and sterile processing personnel for processing all types of reusable flexible endoscopes and accessories in all procedural settings. This article focuses on key points of the guideline to help perioperative personnel safely and effectively process flexible endoscopes to prevent infection transmission. The key points address verification of manual cleaning, mechanical cleaning and processing, storage in a drying cabinet, determination of maximum storage time before reprocessing is needed, and considerations for implementing a microbiologic surveillance program. Perioperative RNs should review the complete guideline for additional information and for guidance when writing and updating policies and procedures.

  2. Dimensionless ratios: Characteristics of quantum liquids and their phase transitions

    Science.gov (United States)

    Yu, Yi-Cong; Chen, Yang-Yang; Lin, Hai-Qing; Römer, Rudolf A.; Guan, Xi-Wen

    2016-11-01

    Dimensionless ratios of physical properties can characterize low-temperature phases in a wide variety of materials. As such, the Wilson ratio (WR), the Kadowaki-Woods ratio, and the Wiedemann-Franz law capture essential features of Fermi liquids in metals, heavy fermions, etc. Here we prove that the phases of many-body interacting multicomponent quantum liquids in one dimension (1D) can be described by WRs based on the compressibility, susceptibility, and specific heat associated with each component. These WRs arise due to additivity rules within subsystems reminiscent of the rules for multiresistor networks in series and parallel—a novel and useful characteristic of multicomponent Tomonaga-Luttinger liquids (TLL) independent of microscopic details of the systems. Using experimentally realized multispecies cold atomic gases as examples, we prove that the Wilson ratios uniquely identify phases of TLL, while providing universal scaling relations at the boundaries between phases. Their values within a phase are solely determined by the stiffnesses and sound velocities of subsystems and identify the internal degrees of freedom of said phase such as its spin degeneracy. This finding can be directly applied to a wide range of 1D many-body systems and reveals deep physical insights into recent experimental measurements of the universal thermodynamics in ultracold atoms and spins.

  3. Flexible Learning in a Digital World.

    Science.gov (United States)

    Collis, Betty; Moonen, Jef

    2002-01-01

    Defines flexible learning and describes components of flexible learning in higher education, including technology, pedagogy or instructional approach, implementation strategies, and institutional framework. Considers factors constraining learning flexibility; changing student characteristics; and the need for lifelong learning, particularly in the…

  4. Difference and ratio plots

    DEFF Research Database (Denmark)

    Svendsen, Anders Jørgen; Holmskov, U; Bro, Peter

    1995-01-01

    hitherto unnoted differences between controls and patients with either rheumatoid arthritis or systemic lupus erythematosus. For this we use simple, but unconventional, graphic representations of the data, based on difference plots and ratio plots. Differences between patients with Burkitt's lymphoma...... and systemic lupus erythematosus from another previously published study (Macanovic, M. and Lachmann, P.J. (1979) Clin. Exp. Immunol. 38, 274) are also represented using ratio plots. Our observations indicate that analysis by regression analysis may often be misleading....

  5. A positive mood, a flexible brain

    OpenAIRE

    Betzel, Richard F.; Satterthwaite, Theodore D.; Gold, Joshua I.; Bassett, Danielle S.

    2016-01-01

    Flexible reconfiguration of human brain networks supports cognitive flexibility and learning. However, modulating flexibility to enhance learning requires an understanding of the relationship between flexibility and brain state. In an unprecedented longitudinal data set, we investigate the relationship between flexibility and mood, demonstrating that flexibility is positively correlated with emotional state. Our results inform the modulation of brain state to enhance response to training in h...

  6. Aggregating and Disaggregating Flexibility Objects

    DEFF Research Database (Denmark)

    Siksnys, Laurynas; Valsomatzis, Emmanouil; Hose, Katja

    2015-01-01

    In many scientific and commercial domains we encounter flexibility objects, i.e., objects with explicit flexibilities in a time and an amount dimension (e.g., energy or product amount). Applications of flexibility objects require novel and efficient techniques capable of handling large amounts...... energy data management and discuss strategies for aggregation and disaggregation of flex-objects while retaining flexibility. This paper further extends these approaches beyond flex-objects originating from energy consumption by additionally considering flex-objects originating from energy production...... and aiming at energy balancing during aggregation. In more detail, this paper considers the complete life cycle of flex-objects: aggregation, disaggregation, associated requirements, efficient incremental computation, and balance aggregation techniques. Extensive experiments based on real-world data from...

  7. Two-dimensional flexible nanoelectronics

    National Research Council Canada - National Science Library

    Akinwande, Deji; Petrone, Nicholas; Hone, James

    2014-01-01

    .... With the discovery of hexagonal boron nitride as an ideal dielectric, the materials are now in place to advance integrated flexible nanoelectronics, which uniquely take advantage of the unmatched...

  8. Flexible Transparent Electronic Gas Sensors.

    Science.gov (United States)

    Wang, Ting; Guo, Yunlong; Wan, Pengbo; Zhang, Han; Chen, Xiaodong; Sun, Xiaoming

    2016-07-01

    Flexible and transparent electronic gas sensors capable of real-time, sensitive, and selective analysis at room-temperature, have gained immense popularity in recent years for their potential to be integrated into various smart wearable electronics and display devices. Here, recent advances in flexible transparent sensors constructed from semiconducting oxides, carbon materials, conducting polymers, and their nanocomposites are presented. The sensing material selection, sensor device construction, and sensing mechanism of flexible transparent sensors are discussed in detail. The critical challenges and future development associated with flexible and transparent electronic gas sensors are presented. Smart wearable gas sensors are believed to have great potential in environmental monitoring and noninvasive health monitoring based on disease biomarkers in exhaled gas.

  9. Flexible sensors based on nanoparticles.

    Science.gov (United States)

    Segev-Bar, Meital; Haick, Hossam

    2013-10-22

    Flexible sensors can be envisioned as promising components for smart sensing applications, including consumer electronics, robotics, prosthetics, health care, safety equipment, environmental monitoring, homeland security and space flight. The current review presents a concise, although admittedly nonexhaustive, didactic review of some of the main concepts and approaches related to the use of nanoparticles (NPs) in flexible sensors. The review attempts to pull together different views and terminologies used in the NP-based sensors, mainly those established via electrical transduction approaches, including, but, not confined to: (i) strain-gauges, (ii) flexible multiparametric sensors, and (iii) sensors that are unaffected by mechanical deformation. For each category, the review presents and discusses the common fabrication approaches and state-of-the-art results. The advantages, weak points, and possible routes for future research, highlighting the challenges for NP-based flexible sensors, are presented and discussed as well.

  10. Flexible protection for metal bellows

    Science.gov (United States)

    Kimble, K. G.

    1970-01-01

    RTV silicone is used with a braided wire sheath surrounding the metal bellows in fluid transfer systems. It demonstrated best overall performance in flexibility and shock absorbing tests, high temperature, low temperature, and salt spray.

  11. Neural Correlates of Attentional Flexibility during Approach and Avoidance Motivation

    Science.gov (United States)

    Calcott, Rebecca D.; Berkman, Elliot T.

    2015-01-01

    Dynamic, momentary approach or avoidance motivational states have downstream effects on eventual goal success and overall well being, but there is still uncertainty about how those states affect the proximal neurocognitive processes (e.g., attention) that mediate the longer-term effects. Attentional flexibility, or the ability to switch between different attentional foci, is one such neurocognitive process that influences outcomes in the long run. The present study examined how approach and avoidance motivational states affect the neural processes involved in attentional flexibility using fMRI with the aim of determining whether flexibility operates via different neural mechanisms under these different states. Attentional flexibility was operationalized as subjects’ ability to switch between global and local stimulus features. In addition to subjects’ motivational state, the task context was manipulated by varying the ratio of global to local trials in a block in light of recent findings about the moderating role of context on motivation-related differences in attentional flexibility. The neural processes involved in attentional flexibility differ under approach versus avoidance states. First, differences in the preparatory activity in key brain regions suggested that subjects’ preparedness to switch was influenced by motivational state (anterior insula) and the interaction between motivation and context (superior temporal gyrus, inferior parietal lobule). Additionally, we observed motivation-related differences the anterior cingulate cortex during switching. These results provide initial evidence that motivation-induced behavioral changes may arise via different mechanisms in approach versus avoidance motivational states. PMID:26000735

  12. Neural Correlates of Attentional Flexibility during Approach and Avoidance Motivation.

    Directory of Open Access Journals (Sweden)

    Rebecca D Calcott

    Full Text Available Dynamic, momentary approach or avoidance motivational states have downstream effects on eventual goal success and overall well being, but there is still uncertainty about how those states affect the proximal neurocognitive processes (e.g., attention that mediate the longer-term effects. Attentional flexibility, or the ability to switch between different attentional foci, is one such neurocognitive process that influences outcomes in the long run. The present study examined how approach and avoidance motivational states affect the neural processes involved in attentional flexibility using fMRI with the aim of determining whether flexibility operates via different neural mechanisms under these different states. Attentional flexibility was operationalized as subjects' ability to switch between global and local stimulus features. In addition to subjects' motivational state, the task context was manipulated by varying the ratio of global to local trials in a block in light of recent findings about the moderating role of context on motivation-related differences in attentional flexibility. The neural processes involved in attentional flexibility differ under approach versus avoidance states. First, differences in the preparatory activity in key brain regions suggested that subjects' preparedness to switch was influenced by motivational state (anterior insula and the interaction between motivation and context (superior temporal gyrus, inferior parietal lobule. Additionally, we observed motivation-related differences the anterior cingulate cortex during switching. These results provide initial evidence that motivation-induced behavioral changes may arise via different mechanisms in approach versus avoidance motivational states.

  13. Neural Correlates of Attentional Flexibility during Approach and Avoidance Motivation.

    Science.gov (United States)

    Calcott, Rebecca D; Berkman, Elliot T

    2015-01-01

    Dynamic, momentary approach or avoidance motivational states have downstream effects on eventual goal success and overall well being, but there is still uncertainty about how those states affect the proximal neurocognitive processes (e.g., attention) that mediate the longer-term effects. Attentional flexibility, or the ability to switch between different attentional foci, is one such neurocognitive process that influences outcomes in the long run. The present study examined how approach and avoidance motivational states affect the neural processes involved in attentional flexibility using fMRI with the aim of determining whether flexibility operates via different neural mechanisms under these different states. Attentional flexibility was operationalized as subjects' ability to switch between global and local stimulus features. In addition to subjects' motivational state, the task context was manipulated by varying the ratio of global to local trials in a block in light of recent findings about the moderating role of context on motivation-related differences in attentional flexibility. The neural processes involved in attentional flexibility differ under approach versus avoidance states. First, differences in the preparatory activity in key brain regions suggested that subjects' preparedness to switch was influenced by motivational state (anterior insula) and the interaction between motivation and context (superior temporal gyrus, inferior parietal lobule). Additionally, we observed motivation-related differences the anterior cingulate cortex during switching. These results provide initial evidence that motivation-induced behavioral changes may arise via different mechanisms in approach versus avoidance motivational states.

  14. FLEXIBLE FLATFOOT IN CHILDREN (REVIEW)

    OpenAIRE

    Владимир Маркович Кенис; Юрий Алексеевич Лапкин; Руслан Халилович Хусаинов; Андрей Викторович Сапоговский

    2014-01-01

    Flatfoot is one of the most common musculoskeletal conditions in the daily practice of pediatric orthopedists. Despite of numerous studies, diagnostic criteria and principles of management remain controversial. Flexible flatfoot - is visually detectable decrease in the height of the longitudinal arch of the foot, which can be spontaneously corrected by active or passive motion and not accompanied by any contracture of foot and ankle. Flexible flatfoot is a benign condition which is normal for...

  15. Value of Flexibility - Phase 1

    Science.gov (United States)

    2010-09-25

    flexibility could also change the calculus of how we determine when to start a new program vice modifying an existing one. Flexibility could even help...decades ago by Steward as a ‖framework for formally identifying and tracking relationships between design variables‖ [ Steward , 1981]. Keese [2007...Paper presented at the 6th Conference on Systems Engineering Research, Los Angeles, CA. Shreve, S. E. (2004). Stochastic calculus for finance. New

  16. Flexible packaging for PV modules

    Science.gov (United States)

    Dhere, Neelkanth G.

    2008-08-01

    Economic, flexible packages that provide needed level of protection to organic and some other PV cells over >25-years have not yet been developed. However, flexible packaging is essential in niche large-scale applications. Typical configuration used in flexible photovoltaic (PV) module packaging is transparent frontsheet/encapsulant/PV cells/flexible substrate. Besides flexibility of various components, the solder bonds should also be flexible and resistant to fatigue due to cyclic loading. Flexible front sheets should provide optical transparency, mechanical protection, scratch resistance, dielectric isolation, water resistance, UV stability and adhesion to encapsulant. Examples are Tefzel, Tedlar and Silicone. Dirt can get embedded in soft layers such as silicone and obscure light. Water vapor transmittance rate (WVTR) of polymer films used in the food packaging industry as moisture barriers are ~0.05 g/(m2.day) under ambient conditions. In comparison, light emitting diodes employ packaging components that have WVTR of ~10-6 g/(m2.day). WVTR of polymer sheets can be improved by coating them with dense inorganic/organic multilayers. Ethylene vinyl acetate, an amorphous copolymer used predominantly by the PV industry has very high O2 and H2O diffusivity. Quaternary carbon chains (such as acetate) in a polymer lead to cleavage and loss of adhesional strength at relatively low exposures. Reactivity of PV module components increases in presence of O2 and H2O. Adhesional strength degrades due to the breakdown of structure of polymer by reactive, free radicals formed by high-energy radiation. Free radical formation in polymers is reduced when the aromatic rings are attached at regular intervals. This paper will review flexible packaging for PV modules.

  17. Flexible solar-array mechanism

    Science.gov (United States)

    Olson, M. C.

    1972-01-01

    One of the key elements of the flexible rolled-up solar array system is a mechanism to deploy, retract, and store the flexible solar-cell arrays. The selection of components, the design of the mechanism assembly, and the tests that were performed are discussed. During 6 months in orbit, all mission objectives were satisfied, and inflight performance has shown good correlation with preflight analyses and tests.

  18. Flexible Learning Spaces Evaluation Report

    OpenAIRE

    Bullimore, A.; Reader, K.; Sultany, A

    2013-01-01

    City University, London is tackling the challenge of ensuring the learning spaces provided are able to meet the anticipated increase in technology usage and prevalent pedagogies. There is no longer a standard classroom design that will achieve this goal and therefore it is imperative to pilot and explore a variety of flexible learning spaces. This report feeds back on an\\ud evaluation of two flexible learning space approaches piloted in the autumn term of 2012 as alternatives to traditional c...

  19. Floating zone growth and magnetic and specific heat properties of La0.67Ca0.33Mn1-xFexO3 (x=0.00, 0.04) single crystals

    Institute of Scientific and Technical Information of China (English)

    Kou Zhi-Qi; Ma Xiao; Di Nai-Li; Li Qing-An; Cheng Zhao-Hua

    2005-01-01

    Single crystals of La0.67Ca0.33MnO3 and La0.67Ca0.33Mn0.96Fe0.04O3 were obtained by floating zone method.Laue diffraction pattern and rocking curve of the single crystals show that their quality is good. The magnetic behaviours of these compounds have been studied. Fe doping significantly depresses the magnetic contribution to the total specific heat Cp, but slightly influences the lattice contribution at temperatures above 50K. The peak of CP shifts towards high temperatures with increasing magnetic field. Both single crystals exhibit the first-order magnetic transition around the Curie temperature.

  20. Developmental constraints on behavioural flexibility.

    Science.gov (United States)

    Holekamp, Kay E; Swanson, Eli M; Van Meter, Page E

    2013-05-19

    We suggest that variation in mammalian behavioural flexibility not accounted for by current socioecological models may be explained in part by developmental constraints. From our own work, we provide examples of constraints affecting variation in behavioural flexibility, not only among individuals, but also among species and higher taxonomic units. We first implicate organizational maternal effects of androgens in shaping individual differences in aggressive behaviour emitted by female spotted hyaenas throughout the lifespan. We then compare carnivores and primates with respect to their locomotor and craniofacial adaptations. We inquire whether antagonistic selection pressures on the skull might impose differential functional constraints on evolvability of skulls and brains in these two orders, thus ultimately affecting behavioural flexibility in each group. We suggest that, even when carnivores and primates would theoretically benefit from the same adaptations with respect to behavioural flexibility, carnivores may nevertheless exhibit less behavioural flexibility than primates because of constraints imposed by past adaptations in the morphology of the limbs and skull. Phylogenetic analysis consistent with this idea suggests greater evolutionary lability in relative brain size within families of primates than carnivores. Thus, consideration of developmental constraints may help elucidate variation in mammalian behavioural flexibility.

  1. Oxide Heteroepitaxy for Flexible Optoelectronics.

    Science.gov (United States)

    Bitla, Yugandhar; Chen, Ching; Lee, Hsien-Chang; Do, Thi Hien; Ma, Chun-Hao; Qui, Le Van; Huang, Chun-Wei; Wu, Wen-Wei; Chang, Li; Chiu, Po-Wen; Chu, Ying-Hao

    2016-11-30

    The emerging technological demands for flexible and transparent electronic devices have compelled researchers to look beyond the current silicon-based electronics. However, fabrication of devices on conventional flexible substrates with superior performance are constrained by the trade-off between processing temperature and device performance. Here, we propose an alternative strategy to circumvent this issue via the heteroepitaxial growth of transparent conducting oxides (TCO) on the flexible mica substrate with performance comparable to that of their rigid counterparts. With the examples of ITO and AZO as a case study, a strong emphasis is laid upon the growth of flexible yet epitaxial TCO relying muscovite's superior properties compared to those of conventional flexible substrates and its compatibility with the present fabrication methods. Besides excellent optoelectro-mechanical properties, an additional functionality of high-temperature stability, normally lacking in the current state-of-the-art transparent flexitronics, is provided by these heterostructures. These epitaxial TCO electrodes with good chemical and thermal stabilities as well as mechanical durability can significantly contribute to the field of flexible, light-weight, and portable smart electronics.

  2. Ratios of Normal Variables

    Directory of Open Access Journals (Sweden)

    George Marsaglia

    2006-05-01

    Full Text Available This article extends and amplifies on results from a paper of over forty years ago. It provides software for evaluating the density and distribution functions of the ratio z/w for any two jointly normal variates z,w, and provides details on methods for transforming a general ratio z/w into a standard form, (a+x/(b+y , with x and y independent standard normal and a, b non-negative constants. It discusses handling general ratios when, in theory, none of the moments exist yet practical considerations suggest there should be approximations whose adequacy can be verified by means of the included software. These approximations show that many of the ratios of normal variates encountered in practice can themselves be taken as normally distributed. A practical rule is developed: If a < 2.256 and 4 < b then the ratio (a+x/(b+y is itself approximately normally distributed with mean μ = a/(1.01b − .2713 and variance 2 = (a2 + 1/(b2 + .108b − 3.795 − μ2.

  3. Ratios of Normal Variables

    Directory of Open Access Journals (Sweden)

    George Marsaglia

    2006-05-01

    Full Text Available This article extends and amplifies on results from a paper of over forty years ago. It provides software for evaluating the density and distribution functions of the ratio z/w for any two jointly normal variates z,w, and provides details on methods for transforming a general ratio z/w into a standard form, (a+x/(b+y , with x and y independent standard normal and a, b non-negative constants. It discusses handling general ratios when, in theory, none of the moments exist yet practical considerations suggest there should be approximations whose adequacy can be verified by means of the included software. These approximations show that many of the ratios of normal variates encountered in practice can themselves be taken as normally distributed. A practical rule is developed: If a < 2.256 and 4 < b then the ratio (a+x/(b+y is itself approximately normally distributed with mean μ = a/(1.01b - .2713 and variance σ2 = (a2 + 1/(b2 + .108b - 3.795 μ2.

  4. Physics-based Morphology Analysis and Adjoint Optimization of Flexible Flapping Wings

    Science.gov (United States)

    2016-08-30

    parametric space including aspect ratio, direction of flexibility (chord-wise, span-wise, etc.). Aerodynamic performance has been evaluated by looking at lift...their interaction in a vast parametric space including aspect ratio, direction of flexibility (chord-wise, span-wise, etc.). Aerodynamic performance...with powerful smoothers like line-Gauss-Siedel or MSIP, they can lead to a numerical solution of the pressure Poisson equation which scales almost

  5. Specific heat of holmium and YNi{sub 2}B{sub 2}C. Criticalbehaviour and superconducting properties; Spezifische Waerme von Holmium und YNi{sub 2}B{sub 2}C. Kritisches Verhalten und supraleitende Eigenschaften

    Energy Technology Data Exchange (ETDEWEB)

    Bekkali, Abdelhakim

    2010-01-04

    Object of the thesis is the study of the specific heat of holmium and YNi{sub 2}B{sub 2}C in the temperature ranges from 50 to 200 KI respectively from 380 mK to 20 K in magnetic fields up to 9 T. In the present thesis the criticalbehaviour of YNi{sub 2}B{sub 2}C and properties of the superconducting state of tne non-magnetic rare-earth nickel borocarbide YNi{sub 2}B{sub 2}C are studied by means of a self-developed measurement apparatur of the specific heat using the quasi-adiabatic heating-pulse method as well as of holmium by means of the relaxation method. In this thesis reliable statements about the critical exponents on monocrystalline holmium could be made. The study on holmium proves that the critical behaviour of the specific heats cannot be described in the framework of the predictions of the chiral universality classes. By means of measurements of the specific heat in this thesis could be confirmed that YNi{sub 2}B{sub 2}C is a multiband superconductor. The positive curvature of the boundary line below T{sub c} in the phase diagram yields a first hint to the many-band character of YNI{sub 2}B{sub 2}C. In the zero-field the electronic specific heat in the superconducting state c{sub es}(T) can be not explained in the framework of the pure BCS theory. At low temperatures a residual contribution by normally conducting electrons could be detected, which hints to a not completely opened energy gap. A possible explanation would be that a band (or several bands) with low charge-carrier concentration not contribute to the superconductivity. This result agrees with de Haas-van Alphen measurements on isostructural superconducting LuNi{sub 2}B{sub 2}C monocrystals, which suggest the many-band character of the superconductivity as well as a vanishing energy gap in one band. The fluctuation behaviour of the specific heat of YNi{sub 2}B{sub 2}C in the neighbourhood of the superconducting-normally conducting transition agrees well with that of the 3D-XY model. [German

  6. Flexible subterahertz metamaterial absorber fabrication using inkjet printing technology

    Science.gov (United States)

    Lee, Dongju; Sung, Hyuk-Kee; Lim, Sungjoon

    2016-07-01

    In this study, a flexible metamaterial (MM) absorber was designed at 0.1 THz and fabricated using inkjet printing technology. The unit cell of the MM absorber was designed using a finite element method-based full-wave simulation. The unit cell comprised square rings, and it was printed with silver nanoparticle ink on flexible Kapton polyimide film. The fabrication processes were performed using a material printer. The absorber's reflection coefficient was measured using a vector network analyzer and a WR-10 waveguide. The absorption ratio was 93.5 % at 0.102 THz. Therefore, we demonstrated the possibility of inkjet printing at a subterahertz band.

  7. Potential support ratios

    DEFF Research Database (Denmark)

    Kjærgaard, Søren; Canudas-Romo, Vladimir

    2017-01-01

    , the prospective potential support ratio usually focuses on the current mortality schedule, or period life expectancy. Instead, in this paper we look at the actual mortality experienced by cohorts in a population, using cohort life tables. We analyse differences between the two perspectives using mortality models......, historical data, and forecasted data. Cohort life expectancy takes future mortality improvements into account, unlike period life expectancy, leading to a higher prospective potential support ratio. Our results indicate that using cohort instead of period life expectancy returns around 0.5 extra younger...

  8. Flexibility of MIP Technology

    Institute of Scientific and Technical Information of China (English)

    Tang Jinlian; Gong Jianhong; Xu Youhao

    2015-01-01

    The lfexibility of MIP technology to meet market demand is mainly introduced in this study. Their commercial application and technical principle are analyzed too. The MIP technology with wide feed adaptability can form a good com-bination with other technologies. The MIP technology has been applied extensively in China. Based on this platform, the CGP, MIP-LTG and MIP-DCR technologies have been developed, which can further improve the lfexibility of MIP tech-nology. Based on its novel reaction control technique with a sole sequential two-zone riser, the MIP users can easily switch to different operating modes between producing either more clean gasoline and propylene or diesel through changing the catalysts and varying the operating conditions. That offers MIP users with enough production lfexibility and a rational pro-duction arrangement to meet the market demand. The MIP-DCR technology with less dry gas and coke yields can provide a more lfexible operating mode since the catalysts to oil ratio has become an independent variable.

  9. Gender Ratio in Dyslexia.

    Science.gov (United States)

    Miles, T. R.; Haslum, M. N.; Wheeler, T. J.

    1998-01-01

    A study involving 11,804 British children (age 10) found that when specified criteria for dyslexia were used, 269 children qualified as dyslexic. These included 223 boys and 46 girls, for a ratio of 4.51 to 1. Difficulties in interpreting these data are discussed and a defense of the criteria is provided. (Author/CR)

  10. The rectilinear Steiner ratio

    Directory of Open Access Journals (Sweden)

    PO de Wet

    2005-06-01

    Full Text Available The rectilinear Steiner ratio was shown to be 3/2 by Hwang [Hwang FK, 1976, On Steiner minimal trees with rectilinear distance, SIAM Journal on Applied Mathematics, 30, pp. 104– 114.]. We use continuity and introduce restricted point sets to obtain an alternative, short and self-contained proof of this result.

  11. Research on High-Specific-Heat Dielectrics

    Science.gov (United States)

    1990-01-31

    Reference Na2W207 + Na2WO4 (4) PbO, PbF2 + MoO3 (5) Bi2O3 (6) -12- [I I EXPERIENTAL PROCEDURE AND RESULTS In this section we will fully describe the...Fabrication," The Journal of Materials Education, ., 71-118 (1987). 2) J.11 Adair. Private Communication . 3) J.H. Adair, A.J. Rose, and L.G. McCoy...P., Maier, J., and Rabenau, A., Solid State Commun . k, 735 (1988). Murugaraj, P., Maier, J., and Rabenau, A., Solid State Commun . 71, 167 (1989). -68

  12. Research on High-Specific-Heat Dielectrics.

    Science.gov (United States)

    1987-05-11

    corresponds to -106- g% MA 6’’ I0S5.- - - - - - ~ P~’WVV, .- - .~-. :- the Q-band microwave frequencies and the values for Bpp agree with those obtained...system is driven into a paramagnetic state ’ the external magneQic field, i.e. a kind of spin- f5 ,-. transition. % - % % a,,,Lo) I1 1 T 7t:-v/8 (L/Lo) 2

  13. Effects of prosthetic foot forefoot flexibility on gait of unilateral transtibial prosthesis users.

    Science.gov (United States)

    Klodd, Elizabeth; Hansen, Andrew; Fatone, Stefania; Edwards, Mark

    2010-01-01

    Five solid-ankle experimental prosthetic feet were used in this double-blind randomized crossover study to determine the effects of forefoot flexibility on gait of 14 unilateral transtibial prosthesis users. Flexibility in experimental feet was altered by changing the number of flexural hinges in their forefoot sections. When experimental prosthetic foot conditions were compared, measured prosthetic ankle dorsiflexion range of motion increased as much as 3.3° with increasing flexibility (p foot's anterior moment arm (measured as the effective foot length ratio) increased as much as 23% of the foot length with decreasing flexibility (p foot with the greatest flexibility (p = 0.001). The results of this study suggest solid-ankle prosthetic foot designs with overly flexible forefoot sections can cause a "drop-off" effect in late stance phase and during the transition of loading between prosthetic and contralateral limbs.

  14. Mapping brain activity with flexible graphene micro-transistors

    CERN Document Server

    Blaschke, Benno M; Guimerà-Brunet, Anton; Weinert, Julia; Rousseau, Lionel; Heimann, Axel; Drieschner, Simon; Kempski, Oliver; Villa, Rosa; Sanchez-Vives, Maria V; Garrido, Jose A

    2016-01-01

    Establishing a reliable communication interface between the brain and electronic devices is of paramount importance for exploiting the full potential of neural prostheses. Current microelectrode technologies for recording electrical activity, however, evidence important shortcomings, e.g. challenging high density integration. Solution-gated field-effect transistors (SGFETs), on the other hand, could overcome these shortcomings if a suitable transistor material were available. Graphene is particularly attractive due to its biocompatibility, chemical stability, flexibility, low intrinsic electronic noise and high charge carrier mobilities. Here, we report on the use of an array of flexible graphene SGFETs for recording spontaneous slow waves, as well as visually evoked and also pre-epileptic activity in vivo in rats. The flexible array of graphene SGFETs allows mapping brain electrical activity with excellent signal-to-noise ratio (SNR), suggesting that this technology could lay the foundation for a future gene...

  15. Characterization of Flexible RF Microcoil Dedicated to Surface Mri

    CERN Document Server

    Woytasik, M; Raynaud, J -S; Poirier-Quinot, M; Dufour-Gergam, E; Grandchamp, J -P; Darrasse, L; Robert, P; Gilles, J -P; Martincic, E; Girard, O

    2007-01-01

    In Magnetic Resonance Imaging (MRI), to achieve sufficient Signal to Noise Ratio (SNR), the electrical performance of the RF coil is critical. We developed a device (microcoil) based on the original concept of monolithic resonator. This paper presents the used fabrication process based on micromoulding. The dielectric substrates are flexible thin films of polymer, which allow the microcoil to be form fitted to none-plane surface. Electrical characterizations of the RF coils are first performed and results are compared to the attempted values. Proton MRI of a saline phantom using a flexible RF coil of 15 mm in diameter is performed. When the coil is conformed to the phantom surface, a SNR gain up to 2 is achieved as compared to identical but planar RF coil. Finally, the flexible coil is used in vivo to perform MRI with high spatial resolution on a mouse using a small animal dedicated scanner operating at in a 2.35 T.

  16. Mapping brain activity with flexible graphene micro-transistors

    Science.gov (United States)

    Blaschke, Benno M.; Tort-Colet, Núria; Guimerà-Brunet, Anton; Weinert, Julia; Rousseau, Lionel; Heimann, Axel; Drieschner, Simon; Kempski, Oliver; Villa, Rosa; Sanchez-Vives, Maria V.; Garrido, Jose A.

    2017-06-01

    Establishing a reliable communication interface between the brain and electronic devices is of paramount importance for exploiting the full potential of neural prostheses. Current microelectrode technologies for recording electrical activity, however, evidence important shortcomings, e.g. challenging high density integration. Solution-gated field-effect transistors (SGFETs), on the other hand, could overcome these shortcomings if a suitable transistor material were available. Graphene is particularly attractive due to its biocompatibility, chemical stability, flexibility, low intrinsic electronic noise and high charge carrier mobilities. Here, we report on the use of an array of flexible graphene SGFETs for recording spontaneous slow waves, as well as visually evoked and also pre-epileptic activity in vivo in rats. The flexible array of graphene SGFETs allows mapping brain electrical activity with excellent signal-to-noise ratio (SNR), suggesting that this technology could lay the foundation for a future generation of in vivo recording implants.

  17. Flexible graphene-PZT ferroelectric nonvolatile memory

    Science.gov (United States)

    Lee, Wonho; Kahya, Orhan; Tat Toh, Chee; Özyilmaz, Barbaros; Ahn, Jong-Hyun

    2013-11-01

    We report the fabrication of a flexible graphene-based nonvolatile memory device using Pb(Zr0.35,Ti0.65)O3 (PZT) as the ferroelectric material. The graphene and PZT ferroelectric layers were deposited using chemical vapor deposition and sol-gel methods, respectively. Such PZT films show a high remnant polarization (Pr) of 30 μC cm-2 and a coercive voltage (Vc) of 3.5 V under a voltage loop over ±11 V. The graphene-PZT ferroelectric nonvolatile memory on a plastic substrate displayed an on/off current ratio of 6.7, a memory window of 6 V and reliable operation. In addition, the device showed one order of magnitude lower operation voltage range than organic-based ferroelectric nonvolatile memory after removing the anti-ferroelectric behavior incorporating an electrolyte solution. The devices showed robust operation in bent states of bending radii up to 9 mm and in cycling tests of 200 times. The devices exhibited remarkable mechanical properties and were readily integrated with plastic substrates for the production of flexible circuits.

  18. FLEXIBLE BUDGET OF SPORT COMPETITIONS

    Directory of Open Access Journals (Sweden)

    Dragan Vukasović

    2009-11-01

    Full Text Available Manager of sport competition has right to decide and also to take responsibility for costs, income and financial results. From economic point of wiev flexible budget and planning cost calculations is top management base for analyzing success level of sport competition. Flexible budget is made before sport competition with few output level, where one is always from static plan-master plan. At the end of competition when we have results, we make report of plan executing and we also analyzing plan variances. Results of comparation between achieved and planning level of static budget can be acceptable if achieved level is approximate to budget level or if we analyzing results from gross or net income. Flexible budget become very important in case of world eco- nomic crises

  19. Inorganic semiconductors for flexible electronics.

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y.; Rogers, J. A.; Center for Nanoscale Materials; Univ. of Illinois

    2007-08-03

    This article reviews several classes of inorganic semiconductor materials that can be used to form high-performance thin-film transistors (TFTs) for large area, flexible electronics. Examples ranging from thin films of various forms of silicon to nanoparticles and nanowires of compound semiconductors are presented, with an emphasis on methods of depositing and integrating thin films of these materials into devices. Performance characteristics, including both electrical and mechanical behavior, for isolated transistors as well as circuits with various levels of complexity are reviewed. Collectively, the results suggest that flexible or printable inorganic materials may be attractive for a range of applications not only in flexible but also in large-area electronics, from existing devices such as flat-panel displays to more challenging (in terms of both cost and performance requirements) systems such as large area radiofrequency communication devices, structural health monitors, and conformal X-ray imagers.

  20. Global Flexibility, synecdoche of progress

    Directory of Open Access Journals (Sweden)

    Clara Selva Olid

    2014-06-01

    Full Text Available The purpose of this article is to explore the flexibility, its uses, types and new concepts to address and empower the global flexibility as an integral tool to facilitate change, adapt to the environment in an advantageous manner and innovate. In times of economic, social, technological and global chances, like today, partners and organizations are claimed to increase their polyvalence and versatility, in order to move towards new organizational and dedication models. In this context and given the need to have a construct that broadly and inherently meets and baste transversely to the different stakeholders of the organization, its structures and forms and mediation between them emerges global flexibility. Despite the challenge of proposing and permeabilising a new construct, no less what it provides, as it is presented as a natural tool to empower wellbeing within organizational and social life.

  1. Wearable Flexible Sensors: A Review

    KAUST Repository

    Nag, Anindya

    2017-05-18

    The paper provides a review on some of the significant research work done on wearable flexible sensors (WFS). Sensors fabricated with flexible materials have been attached to a person along with the embedded system to monitor a parameter and transfer the significant data to the monitoring unit for further analyses. The use of wearable sensors has played a quite important role to monitor physiological parameters of a person to minimize any malfunctioning happening in the body. The paper categorizes the work according to the materials used for designing the system, the network protocols and different types of activities that were being monitored. The challenges faced by the current sensing systems and future opportunities for the wearable flexible sensors regarding its market values are also briefly explained in the paper.

  2. Three-dimensional Numerical Simulation of the Movement of the Flexible Body under Different Constraints

    Institute of Scientific and Technical Information of China (English)

    JIN Yuzhen; LI Jun; ZHU Linhang; DU Jiayou; JIN Yingzi; LIN Peifeng

    2014-01-01

    For the large deformation of the flexible body may cause the fluid grid distortion,which will make the numerical calculation tedious,even to end,the numerical simulation of the flexible body coupling with the fluid is always a tough problem.In this paper,the flexible body is under two kinds of constrained conditions and the ratio of length-diameter is 1:30.The Reynolds number of the airflow is 513,belonging to the area of low Reynolds number.The control equations of the coupling of flexible body with airflow are built and the adaptive grid control method is adopted to conduct the three-dimensional numerical simulation of the movement of the flexible body.The numerical results show that it is possible to simulate the characteristics of the flexible body's movement in the low Reynolds number airflow when the appropriate control equations are modeled and suitable equation-solving method is adopted.Unconstrained flexible body would turn over forward along the airflow's diffusion direction,while constrained flexible body in the flow field will make periodic rotation motion along the axis of the flexible body,and the bending deformation is more obvious than that of unconstrained flexible body.The preliminary three-dimensional numerical simulation can provide references for further research on the characteristics of the yam movement in high Reynolds number airflow.

  3. Studies Of Residual Flexibility And Vibration Testing

    Science.gov (United States)

    Admire, John R.; Tinker, Michael L.; Bookout, Paul S.; Ivey, Edward W.

    1995-01-01

    Collection of reports presents theoretical and experimental studies in which concept of residual flexibility applied to modal vibration testing and verification of mathematical models of vibrations of flexible structure constrained by another structure. "Residual flexibility" denotes that part of interface flexibility due to mode shapes out of frequency range of test. Studies directed toward assessing residual-flexibility approach as substitute for fixed-base vibrational testing of payloads installed in spacecraft.

  4. Polymer electronics a flexible technology

    CERN Document Server

    Technology, Rapra

    2009-01-01

    The worldwide market for polymer electronic products has been estimated to be worth up to £15 billion by 2015 and the opportunity for new markets could be as high as £125 billion by 2025.'The rapid development of polymer electronics has revealed the possibility for transforming the electronics market by offering lighter, flexible and more cost effective alternatives to conventional materials and products. With applications ranging from printed, flexible conductors and novel semiconductor components to intelligent labels and large area displays and solar panels, products that were previously un

  5. Lost and Found in Flexibility

    DEFF Research Database (Denmark)

    Bødker, Susanne; Christiansen, Ellen

    2002-01-01

    'New work' is characterized by mobility and flexibility and a growing need to facilitate social awareness. The paper discusses how to augment the environment with social awareness and suggest 'awareness-in-transition' as a lable for awareness in mobile work in flexible work environments......, and as locus for building social awareness in the 'new work'. A transition (e.g. taking information from a whiteboard in a meeting room to the desktop of a personal computer)--besides the immediate implications at the functional level--has important interpersonal, intra-personal, and organizational...

  6. Flexible Stamp for Nanoimprint Lithography

    DEFF Research Database (Denmark)

    Nielsen, Theodor; Pedersen, Rasmus H.; Hansen, Ole

    2005-01-01

    The design, fabrication and performance of a flexible silicon stamp for homogenous large area nanoimprint lithography (NIL) are presented. The flexible stamp is fabricated by bulk semiconductor micro machining of a 4-inch silicon wafer and consists of thick anchor like imprint areas connected...... by membranes. The bending stiffness difference between the imprint areas and the membranes ensures that the deformation of the stamp during the imprint process mainly takes place in the membranes, leaving the imprint structures unaffected. By this design the strong demand to the parallelism between stamp...

  7. Balancing energy flexibilities through aggregation

    DEFF Research Database (Denmark)

    Valsomatzis, Emmanouil; Hose, Katja; Pedersen, Torben Bach

    2014-01-01

    One of the main goals of recent developments in the Smart Grid area is to increase the use of renewable energy sources. These sources are characterized by energy fluctuations that might lead to energy imbalances and congestions in the electricity grid. Exploiting inherent flexibilities, which exist...... in both energy production and consumption, is the key to solving these problems. Flexibilities can be expressed as flex-offers, which due to their high number need to be aggregated to reduce the complexity of energy scheduling. In this paper, we discuss balance aggregation techniques that already during...

  8. Global Analysis of Flexible Risers

    DEFF Research Database (Denmark)

    Banke, Lars

    1996-01-01

    and thus resists the loading from the environment in a more suitable way.A flexible pipe is a composite structure, built up of several layers each having a specific function. Due to the flexibility, the response of the pipe in wave induced motions are governed by a complex hydroelastic set of differential...... parameters.The idea is to divide the riser system of riser and end fitting system into a global system including the riser and a local system of the bending stiffener and the end fitting. The forces at top of the riser shall be used as input for the design of the local system.This report introduces a non...

  9. 碳酸镁和碳酸锌的比热容及分解吸热效应研究%On the specific heat capacity and decomposition heat of the basic magnesium carbonate and zinc carbonate hydroxide

    Institute of Scientific and Technical Information of China (English)

    高云升; 杜志明; 王春迎

    2013-01-01

    This paper aims to bring about our experimental results on the study of the specific heat capacity and decomposition heat of the basic magnesium carbonate and zinc carbonate hydroxide. As is known, most of carbonates are prone to decompose by absorbing heat, which accounts for their being used as a coolant. Basic magnesium carbonate and zinc carbonate hydroxide have good environmental performance and chemical stability, which accounts for their popular use in the condensed aerosol fire extinguishing device as a coolant for high-temperature gases. Thermal analysis experiments tell us that the specific heat capacities of basic magnesium carbonate and zinc carbonate hydroxide are 1.249 - 2.099 J/(g·℃) and 1.022 - 1.420 J/(g·℃) respectively in the range of 45 - 150℃ . We have also found the relation curve about the specific heat capacity and the temperature of the two compounds. And, next, we have worked out the decomposition reaction of heat absorption capacities of basic magnesium carbonate and zinc carbonate hydroxide to the differential scanning calorimetry curve s peak area by means of the integral method. The experimental facts state that the basic magnesium carbonate has two endothermic peaks: one is near the 250 ℃ , whose decomposition caloric receptivity is about 266.91 J/g, whereas the other is near the 400 ℃ , whose decomposition caloric receptivity is about 1 512.27 J/g. However, zinc carbonate hydroxide has only one endothermic peak, which is bound to be reached near the 250℃ . Its decomposition caloric receptivity is about 283.91 J/g. Hence, the cooling effect of the basic magnesium carbonate has been found preliminary through testing and measurement, which accounts for its application as a coolant in the condensed aerosol fire extinguishing device. The above results prove that basic magnesium carbonate can serve as an excellent chemical coolant suitable for such a device.%碱式碳酸镁和碱式碳酸锌常用作热气溶胶灭火装置

  10. Acute effects of flexible pole exercise on heart rate dynamics.

    Science.gov (United States)

    de Oliveira, Letícia Santana; Moreira, Patrícia S; Antonio, Ana M; Cardoso, Marco A; de Abreu, Luiz Carlos; Navega, Marcelo T; Raimundo, Rodrigo D; Valenti, Vitor E

    2015-01-01

    Exercise with flexible poles provides fast eccentric and concentric muscle contractions. Although the literature reports significant muscle chain activity during this exercise, it is not clear if a single bout of exercise induces cardiac changes. In this study we assessed the acute effects of flexible pole exercise on cardiac autonomic regulation. The study was performed on 22 women between 18 and 26 years old. We assessed heart rate variability (HRV) in the time (SDNN, RMSSD and pNN50) and frequency (HF, LF and LF/HF ratio) domains and geometric indices of HRV (RRTri, TINN, SD1, SD2 and SD1/SD2 ratio). The subjects remained at rest for 10 min and then performed the exercises with the flexible poles. Immediately after the exercise protocol, the volunteers remained seated at rest for 60 min and HRV was analyzed. We observed no significant changes in time domain (SDNN: p=0.72; RMSSD: p=0.94 and pNN50: p=0.92) or frequency domain indices (LF [nu]: p=0.98; LF [ms(2)]: p=0.72; HF [nu]: p=0.98; HF [ms(2)]: p=0.82 and LF/HF ratio: p=0.7) or in geometric indices (RRTri: p=0.54; TINN: p=0.77; SD1: p=0.94; SD2: p=0.67 and SD/SD2: p=0.42) before and after a single bout of flexible pole exercise. A single bout of flexible pole exercise did not induce significant changes in cardiac autonomic regulation in healthy women. Copyright © 2014 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

  11. Magnetic, specific heat and electrical transport properties of Frank-Kasper cage compounds RTM2Al20 [R  =  Eu, Gd and La; TM  =  V, Ti].

    Science.gov (United States)

    Ramesh Kumar, K; Nair, Harikrishnan S; Christian, Reinke; Thamizhavel, A; Strydom, André M

    2016-11-02

    Single crystals of Frank-Kasper compounds RTM2Al20 (R  =  Eu, Gd and La; TM  =  V and Ti) were grown by self-flux method and their physical properties were investigated through magnetization (M), magnetic susceptibility (χ), specific heat (C P) and electrical resistivity (ρ) measurements. Powder x-ray diffraction studies and structural analysis showed that these compounds crystallize in the cubic crystal structure with the space group [Formula: see text]. The magnetic susceptibility for the compounds EuTi2Al20 and GdTi2Al20 showed a sudden jump below the Néel temperature T N indicative of plausible double magnetic transition. Specific heat (C P) and electrical resistivity (ρ) measurements also confirm the first-order magnetic transition (FOMT) and possible double magnetic transitions. Temperature variation of heat capacity showed a sharp phase transition and huge C P value for the (Eu/Gd)Ti2Al20 compounds' full width at half-maximum (FWHM) (<0.2 K) which is reminiscent of a first-order phase transition and a unique attribute among RTM2Al20 compounds. In contrast, linear variation of C P is observed in the ordered state for (Eu/Gd)V2Al20 compounds suggesting a λ-type transition. We observed clear anomaly between heating and cooling cycle in temperature-time relaxation curve for the compounds GdTi2Al20 (2.38 K) and EuTi2Al20 (3.2 K) which is indicating a thermal arrest due to the latent heat. The temperature variation of S mag for GdTi2Al20 saturates to a value [Formula: see text] while the other magnetic systems exhibited still lower entropy saturation values in the high temperature limit. [Formula: see text] versus T plot showed a maximum near 27 K for all the compounds indicating the presence of low frequency Einstein modes of vibrations. Resistivity measurements showed that all the samples behave as normal Fermi liquid type compounds and [Formula: see text] due to electron-phonon scattering follows Bloch-Grüneisen-Mott relation in

  12. Unsteady flow over flexible wings at different low Reynolds numbers

    Directory of Open Access Journals (Sweden)

    Genç Mustafa Serdar

    2016-01-01

    Full Text Available In this study, unsteady flow around flexible membrane wing which had aspect ratio of 1 (AR=1 was investigated experimentally at various Reynolds numbers (Re = 25000 and Re = 50000. Smoke-wire technique for flow visualization over the flexible membrane wing was utilized in the experiments. Digital Image Correlation system (DIC was used for measuring deformation of AR = 1 flexible membrane wing. Instantaneous deformation measurements of membrane wing were combined with the flow field measurements. In low aspect ratio flexible membrane wings, unsteadiness includes tip vortices and vortex shedding, and the combination of tip vortices. In these types of wings, complex unsteady deformations occurred due to vortex shedding. The results showed that the increasing angle of attack results in increase of membrane deformation. Moreover, it was concluded that analysis of the instantaneous deformation revealed chordwise and spanwise, modes which were due to the shedding of leading-edge vortices as well as tip vortices. Consequently, vibrational mode decreased and maximum standard deviation location approached to the trailing edge by reason of increasing angle of attack.

  13. Unsteady flow over flexible wings at different low Reynolds numbers

    Science.gov (United States)

    Genç, Mustafa Serdar; Özden, Mustafa; Hakan Açikel, Halil; Demir, Hacımurat; Isabekov, Iliasbek

    2016-03-01

    In this study, unsteady flow around flexible membrane wing which had aspect ratio of 1 (AR=1) was investigated experimentally at various Reynolds numbers (Re = 25000 and Re = 50000). Smoke-wire technique for flow visualization over the flexible membrane wing was utilized in the experiments. Digital Image Correlation system (DIC) was used for measuring deformation of AR = 1 flexible membrane wing. Instantaneous deformation measurements of membrane wing were combined with the flow field measurements. In low aspect ratio flexible membrane wings, unsteadiness includes tip vortices and vortex shedding, and the combination of tip vortices. In these types of wings, complex unsteady deformations occurred due to vortex shedding. The results showed that the increasing angle of attack results in increase of membrane deformation. Moreover, it was concluded that analysis of the instantaneous deformation revealed chordwise and spanwise, modes which were due to the shedding of leading-edge vortices as well as tip vortices. Consequently, vibrational mode decreased and maximum standard deviation location approached to the trailing edge by reason of increasing angle of attack.

  14. Fuel Flexibility in Gasification

    Energy Technology Data Exchange (ETDEWEB)

    McLendon, T. Robert; Pineault, Richard L.; Richardson, Steven W.; Rockey, John M.; Beer, Stephen K. (U.S. DOE National Energy Technology Laboratory); Lui, Alain P.; Batton, William A. (Parsons Infrastructure and Technology Group, Inc.)

    2001-11-06

    coal to percent by weight sawdust. The mixtures of interest were: 65/35 subbituminous, 75/25 subbituminous, 85/15 subbituminous, and 75/25 bituminous. Steady state was achieved quickly when going from one subbituminous mixture to another, but longer when going from subbituminous to bituminous coal. The most apparent observation when comparing the base case to subbituminous coal/sawdust mixtures is that operating conditions are nearly the same. Product gas does not change much in composition and temperatures remain nearly the same. Comparisons of identical weight ratios of sawdust and subbituminous and bituminous mixtures show considerable changes in operating conditions and gas composition. The highly caking bituminous coal used in this test swelled up and became about half as dense as the comparable subbituminous coal char. Some adjustments were required in accommodating changes in solids removal during the test. Nearly all the solids in the bituminous coal sawdust were conveyed into the upper freeboard section and removed at the mid-level of the reactor. This is in marked contrast to the ash-agglomerating condition where most solids are removed at the very bottom of the gasifier. Temperatures in the bottom of the reactor during the bituminous test were very high and difficult to control. The most significant discovery of the tests was that the addition of sawdust allowed gasification of a coal type that had previously resulted in nearly instant clinkering of the gasifier. Several previous attempts at using Pittsburgh No. 8 were done only at the end of the tests when shutdown was imminent anyway. It is speculated that the fine wood dust somehow coats the pyrolyzed sticky bituminous coal particles and prevents them from agglomerating quickly. As the bituminous coal char particles swell, they are carried to the cooler upper regions of the reactor where they re-solidify. Other interesting phenomena were revealed regarding the transport (rheological) properties of the

  15. Robotic steering of flexible endoscopes

    NARCIS (Netherlands)

    Rozeboom, Esther

    2016-01-01

    Flexible endoscopes were originally designed for non-invasive inspection of body cavities and hollow organs. Today, they are also used for complex minimal invasive interventions. Control of the endoscope is difficult and complexity rises with interventional procedures. Endoscopists suffer from long

  16. Flexible Bistable Cholesteric Reflective Displays

    Science.gov (United States)

    Yang, Deng-Ke

    2006-03-01

    Cholesteric liquid crystals (ChLCs) exhibit two stable states at zero field condition-the reflecting planar state and the nonreflecting focal conic state. ChLCs are an excellent candidate for inexpensive and rugged electronic books and papers. This paper will review the display cell structure,materials and drive schemes for flexible bistable cholesteric (Ch) reflective displays.

  17. Lifelong Open and Flexible Learning

    DEFF Research Database (Denmark)

    Bang, Jørgen

    2006-01-01

    and Flexible (LOF) learning embracing characteristics as: open learning, distance learning, e-learning, online learning, open accessibility, multimedia support, virtual mobility, learning communities, dual mode (earn & learn) approaches, and the like.In my presentation I will focus on the EADTU strategies...

  18. Flexible Learning: A Luddite View

    Science.gov (United States)

    Baggaley, Jon

    2011-01-01

    This article reflects on the flexible learning concept through the eyes of the 19th-century industrial activists known as the Luddites. During a period of economic uncertainty, the Luddite perspective provides a sensitive justification for a change-free educational environment, and for a backlash in favour of "inflexible learning" (IL). The…

  19. Flexibility in Language and Thought

    Science.gov (United States)

    Srinivasan, Mahesh

    2011-01-01

    Many words can be used flexibly: a book can be physically heavy, but also have provocative content, a "chicken" might live in a coop, but could also be tasty to eat. What do the uses of "polysemous" words such as these reveal about the structure of language and thought? Paper 1 examined 4-year-old children's representations of polysemous words…

  20. Creep behaviour of flexible adhesives

    NARCIS (Netherlands)

    Straalen, IJ.J. van; Botter, E.; Berg, A. van den; Beers, P. van

    2004-01-01

    Since flexible adhesives are used more and more in structural applications, designers should have a better understanding of its behaviour under various conditions as ultimate load, fatigue load, long-term load and environmental conditions. This paper focuses on long-term load conditions and its effe

  1. Flexible working motivates all staff.

    Science.gov (United States)

    2001-04-01

    A recent survey has demolished the myth that work-life balance is only of interest to women with children. The survey, commissioned by Lloyds TSB on behalf of the Employers for Work Life Balance organisation, shows that young workers and men are equally interested in flexible working arrangements that allow them to pursue interests outside of work.

  2. Flexible fixation and fracture healing

    DEFF Research Database (Denmark)

    Schmal, Hagen; Strohm, Peter C; Jaeger, Martin

    2011-01-01

    to the bone surface than external fixator bars. External fixators have the advantage of being less expensive, highly flexible, and technically less demanding. They remain an integral part of orthopaedic surgery for emergent stabilization, for pediatric fractures, for definitive osteosynthesis in certain...

  3. Drops spreading on flexible fibers

    Science.gov (United States)

    Somszor, Katarzyna; Boulogne, François; Sauret, Alban; Dressaire, Emilie; Stone, Howard

    2015-11-01

    Fibrous media are encountered in many engineered systems such as textile, paper and insulating materials. In most of these materials, fibers are randomly oriented and form a complex network in which drops of wetting liquid tend to accumulate at the nodes of the network. Here we investigate the role of the fiber flexibility on the spreading of a small volume of liquid on a pair of crossed flexible fibers. A drop of silicone oil is dispensed at the point of contact of the fibers and we characterize the liquid morphologies as we vary the volume of liquid, the angle between the fibers, and the length and bending modulus of the fibers. Drop morphologies previously reported for rigid fibers, i.e. a drop, a column and a mixed morphology, are also observed on flexible fibers with modified domains of existence. Moreover, at small inclination angles of the fibers, a new behavior is observed: the fibers bend and collapse. Depending on the volume, the liquid can adopt a column or a mixed morphology on the collapsed fibers. We rationalize our observations with a model based on energetic considerations. Our study suggests that the fiber flexibility adds a rich variety of behaviors that can be crucial for industrial applications.

  4. FLEXIBLE FLATFOOT IN CHILDREN (REVIEW

    Directory of Open Access Journals (Sweden)

    Владимир Маркович Кенис

    2014-06-01

    Full Text Available Flatfoot is one of the most common musculoskeletal conditions in the daily practice of pediatric orthopedists. Despite of numerous studies, diagnostic criteria and principles of management remain controversial. Flexible flatfoot - is visually detectable decrease in the height of the longitudinal arch of the foot, which can be spontaneously corrected by active or passive motion and not accompanied by any contracture of foot and ankle. Flexible flatfoot is a benign condition which is normal for childhood. But this term is also used to describe a painful deformity with marked limitation of dorsiflection and “not physiological” flatfoot with unfavorable course and prognosis. Despite of the awareness of the parents, flexible flatfoot does not lead to pain and should not be followed by any kind of treatment. Special shoe modifications and orthopedic insoles are useless in the attempt to improve the foot, but can influence negatively psychological condition and self-estimation. Proper diagnosis of flexible flatfoot is necessary in order to avoid unnecessary treatment and to reveal patients with adverse prognosis and rigid forms of flatfoot which need special approach.

  5. Functional flexibility and team performance

    NARCIS (Netherlands)

    Molleman, E.; Slomp, J.

    1999-01-01

    This study deals with workforce flexibility defined in terms of 'multifunctionality' and 'redundancy'. These concepts refer, respectively, to the number of different tasks a worker has mastered and the number of workers that are qualified to do a specific task. A third factor to be considered is wor

  6. Taming Time with Flexible Work.

    Science.gov (United States)

    Stamps, David

    1995-01-01

    Because of increasing incidence of burnout among midlevel managers, many companies are reducing workload schedules, an arrangement that would have been unthinkable 10 years ago. Surveys have made the case that flexible work arrangements increase employee happiness and, therefore, productivity. (JOW)

  7. Protein stability, flexibility and function

    DEFF Research Database (Denmark)

    Teilum, Kaare; Olsen, Johan G; Kragelund, Birthe B

    2011-01-01

    Proteins rely on flexibility to respond to environmental changes, ligand binding and chemical modifications. Potentially, a perturbation that changes the flexibility of a protein may interfere with its function. Millions of mutations have been performed on thousands of proteins in quests for a de......Proteins rely on flexibility to respond to environmental changes, ligand binding and chemical modifications. Potentially, a perturbation that changes the flexibility of a protein may interfere with its function. Millions of mutations have been performed on thousands of proteins in quests...... for a delineation of the molecular details of their function. Several of these mutations interfered with the binding of a specific ligand with a concomitant effect on the stability of the protein scaffold. It has been ambiguous and not straightforward to recognize if any relationships exist between the stability...... of a protein and the affinity for its ligand. In this review, we present examples of proteins where changes in stability results in changes in affinity and of proteins where stability and affinity are uncorrelated. We discuss the possibility for a relationship between stability and binding. From the data...

  8. Easy and flexible mixture distributions

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Mabit, Stefan L.

    2013-01-01

    We propose a method to generate flexible mixture distributions that are useful for estimating models such as the mixed logit model using simulation. The method is easy to implement, yet it can approximate essentially any mixture distribution. We test it with good results in a simulation study...

  9. Tau hadronic branching ratios

    CERN Document Server

    Buskulic, Damir; De Bonis, I; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Odier, P; Pietrzyk, B; Ariztizabal, F; Chmeissani, M; Crespo, J M; Efthymiopoulos, I; Fernández, E; Fernández-Bosman, M; Gaitan, V; Martínez, M; Orteu, S; Pacheco, A; Padilla, C; Palla, Fabrizio; Pascual, A; Perlas, J A; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Farilla, A; Gelao, G; Girone, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Natali, S; Nuzzo, S; Ranieri, A; Raso, G; Romano, F; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Bonvicini, G; Cattaneo, M; Comas, P; Coyle, P; Drevermann, H; Engelhardt, A; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Jacobsen, R; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Markou, C; Martin, E B; Mato, P; Minten, Adolf G; Miquel, R; Oest, T; Palazzi, P; Pater, J R; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schneider, O; Tejessy, W; Tomalin, I R; Venturi, A; Wachsmuth, H W; Wiedenmann, W; Wildish, T; Witzeling, W; Wotschack, J; Ajaltouni, Ziad J; Bardadin-Otwinowska, Maria; Barrès, A; Boyer, C; Falvard, A; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rossignol, J M; Saadi, F; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Kyriakis, A; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Passalacqua, L; Rougé, A; Rumpf, M; Tanaka, R; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Delfino, M C; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Pepé-Altarelli, M; Dorris, S J; Halley, A W; ten Have, I; Knowles, I G; Lynch, J G; Morton, W T; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Smith, M G; Thompson, A S; Thomson, F; Thorn, S; Turnbull, R M; Becker, U; Braun, O; Geweniger, C; Graefe, G; Hanke, P; Hepp, V; Kluge, E E; Putzer, A; Rensch, B; Schmidt, M; Sommer, J; Stenzel, H; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Colling, D J; Dornan, Peter J; Konstantinidis, N P; Moneta, L; Moutoussi, A; Nash, J; San Martin, G; Sedgbeer, J K; Stacey, A M; Dissertori, G; Girtler, P; Kuhn, D; Rudolph, G; Bowdery, C K; Brodbeck, T J; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Whelan, E P; Williams, M I; Galla, A; Greene, A M; Kleinknecht, K; Quast, G; Raab, J; Renk, B; Sander, H G; Wanke, R; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Bencheikh, A M; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Diaconu, C A; Etienne, F; Thulasidas, M; Nicod, D; Payre, P; Rousseau, D; Talby, M; Abt, I; Assmann, R W; Bauer, C; Blum, Walter; Brown, D; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Jakobs, K; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Wolf, G; Alemany, R; Boucrot, J; Callot, O; Cordier, A; Courault, F; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Musolino, G; Nikolic, I A; Park, H J; Park, I C; Schune, M H; Simion, S; Veillet, J J; Videau, I; Abbaneo, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Rizzo, G; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Triggiani, G; Vannini, C; Verdini, P G; Walsh, J; Betteridge, A P; Blair, G A; Bryant, L M; Cerutti, F; Gao, Y; Green, M G; Johnson, D L; Medcalf, T; Mir, L M; Perrodo, P; Strong, J A; Bertin, V; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Edwards, M; Maley, P; Norton, P R; Thompson, J C; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Marx, B; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Beddall, A; Booth, C N; Boswell, R; Cartwright, S L; Combley, F; Dawson, I; Köksal, A; Letho, M; Newton, W M; Rankin, C; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Feigl, E; Grupen, Claus; Lutters, G; Minguet-Rodríguez, J A; Rivera, F; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Ragusa, F; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Bellantoni, L; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Harton, J L; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Schmitt, M; Scott, I J; Sharma, V; Turk, J; Walsh, A M; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G

    1996-01-01

    From 64492 selected \\tau-pair events, produced at the Z^0 resonance, the measurement of the tau decays into hadrons from a global analysis using 1991, 1992 and 1993 ALEPH data is presented. Special emphasis is given to the reconstruction of photons and \\pi^0's, and the removal of fake photons. A detailed study of the systematics entering the \\pi^0 reconstruction is also given. A complete and consistent set of tau hadronic branching ratios is presented for 18 exclusive modes. Most measurements are more precise than the present world average. The new level of precision reached allows a stringent test of \\tau-\\mu universality in hadronic decays, g_\\tau/g_\\mu \\ = \\ 1.0013 \\ \\pm \\ 0.0095, and the first measurement of the vector and axial-vector contributions to the non-strange hadronic \\tau decay width: R_{\\tau ,V} \\ = \\ 1.788 \\ \\pm \\ 0.025 and R_{\\tau ,A} \\ = \\ 1.694 \\ \\pm \\ 0.027. The ratio (R_{\\tau ,V} - R_{\\tau ,A}) / (R_{\\tau ,V} + R_{\\tau ,A}), equal to (2.7 \\pm 1.3) \\ \\%, is a measure of the importance of Q...

  10. Statistical Analysis and Calculation Model of Flexibility Coefficient of Low- and Medium-Sized Arch Dam

    Directory of Open Access Journals (Sweden)

    Su Huaizhi

    2012-01-01

    Full Text Available The flexibility coefficient is popularly used to implement the macroevaluation of shape, safety, and economy for arch dam. However, the description of flexibility coefficient has not drawn a widely consensus all the time. Based on a large number of relative instance data, the relationship between influencing factor and flexibility coefficient is analyzed by means of partial least-squares regression. The partial least-squares regression equation of flexibility coefficient in certain height range between 30 m and 70 m is established. Regressive precision and equation stability are further investigated. The analytical model of statistical flexibility coefficient is provided. The flexibility coefficient criterion is determined preliminarily to evaluate the shape of low- and medium-sized arch dam. A case study is finally presented to illustrate the potential engineering application. According to the analysis result of partial least-squares regression, it is shown that there is strong relationship between flexibility coefficient and average thickness of dam, thickness-height ratio of crown cantilever, arc height ratio, and dam height, but the effect of rise-span ratio is little relatively. The considered factors in the proposed model are more comprehensive, and the applied scope is clearer than that of the traditional calculation methods. It is more suitable for the analogy analysis in engineering design and the safety evaluation for arch dam.

  11. GASP: A computer code for calculating the thermodynamic and transport properties for ten fluids: Parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. [enthalpy, entropy, thermal conductivity, and specific heat

    Science.gov (United States)

    Hendricks, R. C.; Baron, A. K.; Peller, I. C.

    1975-01-01

    A FORTRAN IV subprogram called GASP is discussed which calculates the thermodynamic and transport properties for 10 pure fluids: parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. The pressure range is generally from 0.1 to 400 atmospheres (to 100 atm for helium and to 1000 atm for hydrogen). The temperature ranges are from the triple point to 300 K for neon; to 500 K for carbon monoxide, oxygen, and fluorine; to 600 K for methane and nitrogen; to 1000 K for argon and carbon dioxide; to 2000 K for hydrogen; and from 6 to 500 K for helium. GASP accepts any two of pressure, temperature and density as input conditions along with pressure, and either entropy or enthalpy. The properties available in any combination as output include temperature, density, pressure, entropy, enthalpy, specific heats, sonic velocity, viscosity, thermal conductivity, and surface tension. The subprogram design is modular so that the user can choose only those subroutines necessary to the calculations.

  12. Prediction of capacity of heat exchanger by thermal network method. Prediction of a capacity of a condenser with effective specific heat model; Netsukairomoho ni yoru kuki chowayo netsukokanki seino no yosoku. Yukohi netsu model wo mochiita gyosukukuki seino no o yosoku

    Energy Technology Data Exchange (ETDEWEB)

    Kaga, K.; Yamada, K.; Koto, S.; Ogushi, T. [Mitsubishi Electric Corp. Tokyo (Japan)

    2000-07-25

    In this paper, thermal network method using effective specific heat model of refrigerant with phase change is proposed for predicting the capacity of a plate fin and tube type heat exchanger. Effective specific heat model suits for obtaining an accurate result of a heat exchanging capacity of a condenser with small number of elements. By comparing calculated results with experiment, it is clarified that an error of calculated capacity of condenser is less than 1% in case that the range of sub-cool degree is from 15K to 22K at outlet of refrigerant flow. (author)

  13. Integrated flexible capacity and inventory management under flexible capacity uncertainty

    OpenAIRE

    Paç, Mehmet Fazıl

    2006-01-01

    Cataloged from PDF version of article. In a manufacturing environment with volatile demand, inventory management can be coupled with dynamic capacity adjustments for handling the fluctuations more effectively. In this study we consider the integrated management of inventory and flexible capacity management under seasonal stochastic demand and uncertain labor supply. The capacity planning problem is investigated from the workforce planning perspective. We consider a manufactu...

  14. Optical Tracking Measurement on Vortex Induced Vibration of Flexible Riser with Short-Length Buoyance Module

    Science.gov (United States)

    Fan, Dixia; Du, Honglin; Triantafyllou, Michael

    2016-11-01

    We address experimentally the vortex induced vibrations (VIV) of long flexible cylinders. We employ optical tracking, using an array of high speed cameras. Compared to strain gauges and accelerometers, this non-intrusive approach, allows direct measurement of the flexible cylinder displacement with far denser spatial distribution. The measurements reveal essential features of flexible cylinder VIV, including complex geometries such as cylinders containing short-length buoyancy modules, with module to cylinder diameter ratio of 1:3.2 and module to bare cylinder length ratio of 1:1. The experiments are conducted with aspect ratio of 170 and 3 different coverage ratios, of 100%, 50% and 20%. The measurements demonstrate bi-frequency response due to excitation from both buoyancy module and bare cylinder, at low Strouhal number, down to values of 0.08, and the generation of traveling wave patterns.

  15. WAGE FLEXIBILITY IN THE CONTEMPORARY SOCIETY

    Directory of Open Access Journals (Sweden)

    TECULESCU Silviu Alexandru

    2010-12-01

    Full Text Available The paper follows to offer the most efficient solutions for the attainment by Romania of the economic development level associated to the Western European countries. It proposes the division of the flexibility of labour market in three components, namely: internal flexibility, external flexibility and wage flexibility. The analysis performed within the present study will emphasize the wage flexibility. Wage flexibility can be classified in four components: a plans of individual and group incentives; b plans of assigning wages out of productivity; c plans of distribution of profits and, respectively, d plans of suggestions. The labour market flexibility, in general, and especially the wage flexibility contributes to the increase of employee motivation at the workplace, aspect which leeds to the growth of labour productivity, through this one being put the bases of the medium- and long-term economic development.

  16. ULTRA BARRIER TOPSHEET (UBT) FOR FLEXIBLE PHOTOVOLTAICS

    Energy Technology Data Exchange (ETDEWEB)

    DeScioli, Derek

    2013-06-01

    This slide-show presents 3M photovoltaic-related products, particularly flexible components. Emphasis is on the 3M Ultra Barrier Solar Films. Topics covered include reliability and qualification testing and flexible photovoltaic encapsulation costs.

  17. Understanding flexible and distributed software development processes

    OpenAIRE

    Agerfalk, Par J.; Fitzgerald, Brian

    2006-01-01

    peer-reviewed The minitrack on Flexible and Distributed Software Development Processes addresses two important and partially intertwined current themes in software development: process flexibility and globally distributed software development

  18. Flexible Temperature Sensors on Fibers

    Directory of Open Access Journals (Sweden)

    Marcin Sloma

    2010-08-01

    Full Text Available The aim of this paper is to present research dedicated to the elaboration of novel, miniaturized flexible temperature sensors for textronic applications. Examined sensors were manufactured on a single yarn, which ensures their high flexibility and good compatibility with textiles. Stable and linear characteristics were obtained by special technological process and applied temperature profiles. As a thermo-sensitive materials the innovative polymer compositions filled with multiwalled carbon nanotubes were used. Elaborated material was adapted to printing and dip-coating techniques to produce NTC composites. Nanotube sensors were free from tensometric effect typical for other carbon-polymer sensor, and demonstrated TCR of 0.13%/K. Obtained temperature sensors, compatible with textile structure, can be applied in rapidly developing smart textiles and be used for health and protections purposes.

  19. Thin, Flexible IMM Solar Array

    Science.gov (United States)

    Walmsley, Nicholas

    2015-01-01

    NASA needs solar arrays that are thin, flexible, and highly efficient; package compactly for launch; and deploy into large, structurally stable high-power generators. Inverted metamorphic multijunction (IMM) solar cells can enable these arrays, but integration of this thin crystalline cell technology presents certain challenges. The Thin Hybrid Interconnected Solar Array (THINS) technology allows robust and reliable integration of IMM cells into a flexible blanket comprising standardized modules engineered for easy production. The modules support the IMM cell by using multifunctional materials for structural stability, shielding, coefficient of thermal expansion (CTE) stress relief, and integrated thermal and electrical functions. The design approach includes total encapsulation, which benefits high voltage as well as electrostatic performance.

  20. The evolution of flexible parenting.

    Science.gov (United States)

    Royle, Nick J; Russell, Andrew F; Wilson, Alastair J

    2014-08-15

    Parenting behaviors, such as the provisioning of food by parents to offspring, are known to be highly responsive to changes in environment. However, we currently know little about how such flexibility affects the ways in which parenting is adapted and evolves in response to environmental variation. This is because few studies quantify how individuals vary in their response to changing environments, especially social environments created by other individuals with which parents interact. Social environmental factors differ from nonsocial factors, such as food availability, because parents and offspring both contribute and respond to the social environment they experience. This interdependence leads to the coevolution of flexible behaviors involved in parenting, which could, paradoxically, constrain the ability of individuals to rapidly adapt to changes in their nonsocial environment. Copyright © 2014, American Association for the Advancement of Science.