A Two-Dimensional Brans—Dicke Star Model with Exotic Matter and Dark Energy

A two-dimensional Brans-Dicke star model with exotic matter and dark energy is studied in this paper,the field equation and balance equation are derived at finite temperature,the analytic solutions of these equations canbe used to calculate the mass of star.In addition,we find that star's mass has a minimum when matter state parameterγ→0.

A Theoretical Study on Energy of a Gaseous System Vis-a-Vis Mass and Temperature

To study various properties of a gas has been a subject of rational curiosity in pneumatic sciences. A gaseous system, in general, is studied by using four measurable parameters namely, the pressure, volume, number of moles and temperature. In the present work, an attempt is made to study the variation of energy of an ideal gas with the two measurable parameters, the mass and temperature of the gas. Using the well known ideal gas equation, PV = nRT where symbols have their usual meanings and some simple mathematical operations widely used in physics, chemistry and mathematics in a transparent manner, an equation of state relating the three variables, the energy, mass and temperature of an ideal gas is obtained. It is found that energy of an ideal gas is equal to the product of mass and temperature of the gas. This gives a direct relationship between the energy, mass and temperature of the gas. Out of the three variables, the energy, mass and temperature of an ideal gas, if one of the parameters is held constant, the other two variables can be measured. At a constant temperature, when the power or energy is stabilized, the increase in the mass of the gas may affect the new works and an engine can therefore be prevented from overheating.

A Fermi Energy-Incorporated Framework for Dealing with the Temperature- and Magnetic Field-Dependent Critical Current Densities of Superconductors and Its Application to Bi-2212

It is well known that the critical current density of a superconductor depends on its size, shape, nature of doping and the manner of preparation. It is suggested here that the collective effect of such differences for different samples of the same superconductor is to endow them with different values of the Fermi energy—a single property to which may be attributed the observed variation in their critical current densities. The study reported here extends our earlier work concerned with the generalized BCS equations [Malik, G.P. (2010) Physica B, 405, 3475-3481;Malik, G.P. (2013) WJCMP, 3,103-110]. We develop here for the first time a framework of microscopic equations that incorporates all of the following parameters of a superconductor: temperature, momentum of Cooper pairs, Fermi energy, applied magnetic field and critical current density. As an application of this framework, we address the different values of critical current densities of Bi-2212 for non-zero values of temperature and applied magnetic field that have been reported in the literature.

Equation of state for solids considering cohesive energy and anharmonic effect and its application to MgO

A simple equation of state （EOS） in wide ranges of pressure and temperature is constructed within the MieGruneisen Debye framework. Instead of the popular Birch-Murnaghan and Vinet EOS, we employ a five-parameter cold energy expression to represent the static EOS term, which can correctly produce cohesive energy without any spurious oscillations in the extreme compression and expansion regions, We developed a Pade approximation-based analytic Debye quasiharmonic model with high accuracy which improves the performance of EOS in the low temperature region. The anharmonic effect is taken into account by using a semi-empirical approach. Its reasonability is verified by the fact that the total thermal pressure tends to the lowest-order anharmonic expansion in the literature at low temperature, and tends to ideal-gas limitation at high temperature, which is physically correct. Besides, based on this approach, the anharmonic thermal pressure can be expressed in the Griineisen form, which is convenient for applications. The proposed EOS is used to study the thermodynamic properties of MgO including static and shock compression conditions, and the results are very satisfactory as compared with the experimental data.

The Application of Thermomechanical Dynamics (TMD) to the Analysis of Nonequilibrium Irreversible Motion and a Low-Temperature Stirling Engine

We applied the method of Thermomechanical Dynamics (TMD) to a low-temperature Stirling engine, and the dissipative equation of motion and time-evolving physical quantities are self-consistently calculated for the first time in this field. The thermomechanical states of the heat engine are in Nonequilibrium Irreversible States (NISs), and time-dependent thermodynamic work W(t), internal energy E(t), energy dissipation or entropy Qd(t), and temperature T(t), are precisely studied and computed in TMD. We also introduced the new formalism, Q(t)-picture of thermodynamic heat-energy flows, for consistent analyses of NISs. Thermal flows in a long-time uniform heat flow and in a short-time heat flow are numerically studied as examples. In addition to the analysis of time-dependent physical quantities, the TMD analysis suggests that the concept of force and acceleration in Newtonian mechanics should be modified. The acceleration is defined as a continuously differentiable function of Class C2 in Newtonian mechanics, but the thermomechanical dynamics demands piecewise continuity for acceleration and thermal force, required from physical reasons caused by frictional variations and thermal fluctuations. The acceleration has no direct physical meaning associated with force in TMD. The physical implications are fundamental for the concept of the macroscopic phenomena in NISs composed of systems in thermal and mechanical motion.

A Model for Temperature Infl uence on Concrete Hydration Exothermic Rate (Part one: Theory and Experiment)

Recent achievements in concrete hydration exothermic models based on Arrhenius equation have improved computation accuracy for mass concrete temperature field. But the properties of the activation energy and the gas constant （Ea/R） have not been well studied yet. From the latest experiments it is shown that Ea/R obviously changes with the hydration degree without fixed form. In this paper, the relationship between hydration degree and Ea/R is studied and a new hydration exothermic model is proposed. With those achievements, the mass concrete temperature field with arbitrary boundary condition can be calculated more precisely.

Analysis of surface temperature bias over the Tibetan plateau in the CAS FGOALS-f3-L model

The Chinese Academy of Sciences Flexible Global Ocean-Atmosphere-Land System atmospheric component model(FGOALS-f3-L)participated in Phase 6 of the Coupled Model Intercomparison Project,but its reproducibility of surface temperature(T_(s))over the Tibetan Plateau(TP)as a key climatically sensitive region remains unclear.This study evaluates the capability of FGOALS-f3-L in reproducing the climatological T_(s)over the TP relative to the Climate Forecast System Reanalysis.The results show that FGOALS-f3-L can reasonably capture the spatial pattern of T_(s)but underestimates the annual mean T_(s)for the whole TP.The simulated T_(s)for the whole TP shows a cold bias in winter and spring and a warm bias in summer and autumn.Further quantitative analysis based on the surface energy budget equation shows that the surface albedo feedback(SAF)term strongly contributes to the annual,winter,and spring mean cold bias in the western TP and to the warm bias in the eastern TP.Compared with the SAF term,the surface sensible and latent heat flux terms make nearly opposite contributions to the T_(s)bias and considerably offset the bias due to the SAF term.The cloud radiative forcing term strongly contributes to the annual and seasonal mean weak cold bias in the eastern TP.The longwave radiation term associated with the overestimated water vapor content accounts for a large portion of the warm bias over the whole TP in summer and autumn.Improving land surface and cloud processes in FGOALS-f3-L is critical to reduce the T_(s)bias over the TP.

High temperature deformation behavior and mechanism of spray deposited Al-Fe-V-Si alloy

Al-8.5Fe-1.3V-1.7Si alloy was prepared by spray deposition and hot extrusion. The high temperature plastic deformation behavior of the spray deposited Al-8.5Fe-1.3V-1.7Si alloy was investigated in the strain rate range of 2.77×10-4-2.77×10-2 s-1 and temperature range of 350-550 ℃ by Gleebe-1500 thermomechanical simulator. The mechanism of the high temperature plastic deformation of the alloys was studied by TEM associated with the analysis of Rosler-Artz physical constitutive relationship based on the model of dislocation detaching from dispersion particles. The results show that Al-Fe-V-Si alloy has low strain hardening coefficient, and even exhibits work softening. Stress exponent n and activation energy Q were calculated based on Zener-Hollomon relation and Rosler-Artz physical model respectively. The Rosler-Artz physical model can give a good prediction for the abnormal behavior of high temperature deformation of spray deposited Al-Fe-V-Si alloy, that is, n larger than 8 and Q higher than 142 kJ/mol. However, because of the highly refined microstructure, the high temperature deformation behavior of spray deposited Al-Fe-V-Si alloy deviates more or less from the law predicted by using Rosler-Artz physical model.

Healing Temperature of Hybrid Structures Based on Genetic Algorithm

The healing temperature of suspen-dome with stacked arches(SDSA)and arch-supported single-layer lattice shell structures was investigated based on the genetic algorithm. The temperature field of arch under solar radiation was derived by FLUENT to investigate the influence of solar radiation on the determination of the healing temperature. Moreover, a multi-scale model was established to apply the complex temperature field under solar radiation. The change in the mechanical response of these two kinds of structures with the healing temperature was discussed. It can be concluded that solar radiation has great influence on the healing temperature, and the genetic algorithm can be effectively used in the optimization of the healing temperature for hybrid structures.

From Pressure-Volume Relationship to Volume-Energy Relationship: A Thermo-Statistical Model for Alveolar Micromechanics

The connective tissue fiber system and the surfactant system are essential and interdependent components of lung elasticity. Despite considerable efforts over the last decades, we are still far from understanding the quantitative roles of either the connective tissue fiber or the surfactant systems. Through thermo-statistic considerations of alveolar micromechanics, the author introduced a thermo-statistic state function “entropy” to analyze the elastic property of pulmonary parenchyma based on the origami model of alveolar polyhedron. By use of the entropy for alveolar micromechanics, from the logistic equation for the static pressure (P)-volume (V) curves including parameters a, b, c, and k (V - a = b/[1+ exp{-k (P - c)}]), a set of equations was obtained to define the internal energy of lungs (UL) and its corresponding lung volume (VL). Then, by use of parameters a, b, c, and k, an individual volume-internal energy (VL - UL) diagram was constructed from reported data in patients on mechanical ventilation. Each VL - UL diagram constructed was discussed that its minimal value Uo = c (a + b/2) and its shape parameter b/k represent quantitatively the energy of tissue force and the energy of surface force. Furthermore, by use of the VL - UL relationship, the hysteresis of lungs estimated by entropy production was discussed as dependent on the difference in the number of contributing pulmonary lobules. That is, entropy production might be a novel quantitative indicator to estimate the dynamics of the bronchial tree. These values obtained by combinations of parameters of the logistic P-V curve seem useful indicators to optimize setting a mechanical ventilator. Thus, it is necessary to develop easy tools for fitting the individual sigmoid pressure-volume curve measured in the intensive care unit to the logistic equation.

温度场的有限差分计算——以一维温度场为例

已有关于温度场的研究多是从热传导方程出发的,且大多未考虑材料性能随温度的变化.从能量平衡的角度研究温度场,能有效考虑热对流边界条件和材料性能随温度变化的问题.为了更好地还原实际情况,首先,基于能量平衡的原理,采用有限差分法建立了瞬态传热问题的有限差分方程;其次,考虑材料性能随温度的变化,使用MATLAB进行编程计算温度场;最后,给出算例,并通过与相应的ABAQUS有限元模拟结果对比,证明该方法能有效处理此类问题.研究发现:在升温环境中,是否考虑材料热工参数随温度变化不影响温度分布规律,但影响温度大小;当考虑材料性能随温度变化时,计算得到的物体内部温度高于不考虑材料性能变化时的温度;环境温度采用国际标准升温曲线时,在边界处物体内部温度变化与环境温度变化形式相同,均呈对数形式;在远离边界的物体内部,温度变化幅度随着离边界距离的增大而减小,温度变化呈指数形式.

一种量子级联激光器能带电子温度计算新方法

基于电子动能与温度的关系以及费米黄金定律,对速率方程进行了优化,使其能够计算电子温度,进而实现了更为精准的速率方程求解。与已有的动能平衡法比较,该方法对能带电子温度变化过程进行了详细的描述,故无需采用优化算法求解,所以可以避免因陷入局部最优解而带来的多次计算的收敛值一致性较差的问题。计算结果表明,该方法在选取不同的初始温度时,通过自洽求解,即可解出各能级电子温度,且均可获得一致性较好的收敛值。

热源厂房通风有效性的数值分析

采用k-ε紊流模型,利用ANSYS计算软件,对某热源厂房的自然通风进行数值计算,将生产线上的散热量作为能量方程的附加源项,预测厂房内的速度场和温度场。预测结果表明:降低进风口的标高以及减少通风障碍物对风流的影响,可增加作业区的有效风量,从而提高厂房的通风效果。厂房的通风改造实施后,验证了数值模拟的结果。热源厂房通风的有效性可以采用能量利用系数来衡量,也可以采用有效风量率和有效空间的速度不均匀性系数来衡量。

圆轴承三维温度场的研究

联立求解了广义雷诺方程、三维能量方程、三维固体热传导方程及载荷平衡方程 ,并考虑粘度随温度及压力、密度随粘度及压力的变化 ,在油膜与轴瓦界面使用热流连续性边界条件 ,得到了圆轴承油膜及轴瓦的三维温度场。结果表明最高温度并不出现在油膜与轴瓦交界面 ,不同圆周位置沿膜厚方向的最高温度出现位置不同。证实了考虑三维温度得到的轴承的润滑性能与考虑二维温度得到的轴承润滑性能有很大的差异。采用 Newton- Raphson法求解广义雷诺方程和载荷平衡方程 ,采用快速扫描法求解由有限差分离散的能量方程和热传导方程 ,在计算中发现所使用的算法收敛速度快 。

圆轴承三维热流体动力润滑的研究

联立求解了广义雷诺方程、三维能量方程、三维固体热传导方程及载荷平衡方程 ,并考虑粘度随温度及压力、密度随粘度及压力的变化 ,在油膜与轴瓦界面使用热流连续性边界条件 ,得到了圆轴承油膜及轴瓦的三维温度场。结果表明最高温度并不出现在油膜与轴瓦交界面 ,不同圆周位置沿膜厚方向的最高温度出现位置不同。证实了考虑三维温度得到的轴承的润滑性能与考虑二维温度得到的轴承润滑性能有很大的差异。采用Newton-Raphson法求解广义雷诺方程和载荷平衡方程 ,采用快速扫描法求解由有限差分离散的能量方程和热传导方程 ,在计算中发现所使用的算法收敛速度快 ,大大节约了计算时间。

Arrhenius方程应用新方法研究

提出了一种快速评价电子元器件的新方法,该方法具有快速、准确、成本低、效率高等优点。利用Arrhenius方程,能快速准确地确定元器件退化的失效敏感参数和退化机理;可对单样品求出与失效机理相关的失效激活能和寿命;通过多样品试验,可得到寿命分布、寿命加速特性和失效率等可靠性参数。以DC/DC电源变换器和高频小功率管3DG130为例,通过实验与现场数据的对比,证明了新方法的正确性和有效性。该方法适用于失效率优于10-7/h(λ<10-7/h)的高可靠性产品的定量评价。

稠油粘温特性及流变特性分析

采用RS75旋转粘度计对稠油的粘温特性及流变特性进行了测量及研究。结果表明,稠油的粘温特性在测量区间内（80~20℃）较好地符合Arrhenius方程;温度越低,稠油粘度对温度变化越敏感;不同温度区间稠油的活化能不同,低温区间（36.5~20.3℃）内的活化能比高温区间（80.0~55.9℃）内的活化能增长了45%;反常点温度为35℃,当温度高于35℃时,稠油表现为牛顿流体,温度低于35℃时,稠油表现为非牛顿流体;在非牛顿流体区,稠油不具有触变性。

考虑温度变化的地下水运动方程及其在储能模型中的应用

从建立一般条件下的多孔介质液相动量守恒方程出发,较严密地推导了考虑温度变化的地下水运动方程,并在此基础上提出了一个新的含水层储能模型。该模型用于上海第二承压含水层群井储能试验,取得了令人满意的结果,从而证明高温差条件下对地下水运动方程进行修正是必要的,具有重要的理论和现实意义。

工业纯钛TA1热压缩变形行为及本构方程

为了实现工业纯钛TA1的数值模拟,制定合理的自由锻工艺参数,利用Gleeble-1500D热模拟实验机对工业纯钛TA1在变形温度为700、800、900和950℃和应变速率为0.01、0.1、1和5 s-1条件下的流变应力行为进行研究,最大变形程度为真应变0.7。结果表明:工业纯钛TA1在热压缩变形过程中,出现了动态回复与再结晶;流变应力随温度的升高而降低,随变形速率的减小而降低;在高的变形温度与低的应变速率下,工业纯钛TA1容易出现软化;求得了热变形激活能(Q)和双曲正弦形式的Arrhenius本构方程。

二维三温能量方程组离散求解的两个新预处理技术

二维三温能量方程离散后得到的稀疏线性代数方程组中,系数矩阵各行的对角占优性相差十分悬殊,矩阵元素相差也十分大.针对前一问题,提出了改善对角占优性的一个新比例化方法.针对后一问题,利用每次舍弃前计算多个行的技术提出了多行ILUT预条件方法.最后,将对角占优性改善技术、多行ILUT与对角元比例化技术、RCM排序联合使用于实际的能量方程离散求解中,取得了较好的加速效果.