甲烷-空气最小点火能量预测理论模型

 最小点火能是可燃气体危险性辨识的重要参数之一。为从理论上得到混合气体的最小点火能,建立了可燃气体火花点火的物理模型,给出了通过数值模拟得到的可燃气体最小点火能量的预测方法,采用该方法得到了甲烷-空气混合气火花点火的临界温度及最小点火能量。结果表明：甲烷-空气混合气的最小点火能量与浓度呈U型关系,浓度为8.5%的预混气的最小点火能量计算值为0.39 mJ,与实验值0.4 mJ吻合较好。     

Nuclear Level Density with Non-zero Angular Momentum

The statistical properties of interacting fermions have been studied for various angular momentum with the inclusion of pairing interaction. The dependence of the critical temperature on angular momentum for several nuclei, have been studied. The yrast energy as a function of angular momentum for 28Si and 24 Mg nuclei have been calculated up to 60.0 MeV of excitation energy. The computed limiting angular momenta are compared with the experimental results for ^26Al produced by ^12C＋ 14N reaction. The relevant nuclear level densities for non-zero angular momentum have been computed for ^44Ti and ^136 Ba nuclei. The results are compared with their corresponding values obtained from the approximate formulas.     

Influence of Solvent-Solvent and Solute-Solvent Interaction Properties on Solvent-Mediated Potential

A recently proposed universal calculational recipe for solvent-mediated potential is applied to calculate excess potential of mean force between two large Lennard-Jones （LJ） or hard core attractive Yukawa particles immersed in small LJ solvent bath at supercritical state. Comparison between the present prediction with a hypernetted chain approximation adopted for solute-solute correlation at infinitely dilute limit and existing simulation data shows high accuracy for the region with large separation, and qualitative reliability for the solute particle contact region. The calculational simplicity of the present recipe allows for a detailed investigation on the effect of the solute-solvent and solvent-solvent interaction details on the excess potential of mean force. The resultant conclusion is that gathering of solvent particles near a solute particle leads to repulsive excess PMF, while depletion of solvent particles away from the solute particle leads to attractive excess PMF, and minor change of the solvent-solvent interaction range has large influence on the excess PMF.     

静水压作用下Nb3Sn多晶体超导临界温度退化的耦合模型

Nb3Sn超导材料主要用于强磁场超导磁体的制造。力学变形诱导的其超导临界性能退化给强磁场超导磁体装置的电磁性能指标和安全运行造成了极其不利的影响。针对静水压作用下，Nb3Sn单晶体和多晶体表现出的不同退化行为，本文基于Maki De Gennes（MDG）关系式，建立了描述Nb3Sn单晶体变形-超导临界温度耦合响应的本构关系，并借助于多晶体有限元方法，对静水压作用下Nb3Sn多晶体超导临界温度退化响应进行了预测，预测结果与实验结果定性吻合。模型实现了从Nb3Sn单晶体到Nb3Sn多晶体变形-超导临界温度退化响应曲线的一致性预测。研究结果有助于提高对Nb3Sn高场超导材料变形-超导电性能耦合行为的认识，为发展描述运行工况下Nb3Sn超导材料力-电磁-热多物理场多尺度耦合行为的建模与数值计算方法提供了一定的基础；同时，相关结果对于特殊工况下高场超导磁体性能的评估和高应变耐受性超导材料的制备也具有一定的指导作用。     

回热器功产生的临界温度梯度研究

热声机械作为一种能量转化装置，能够不通过运动部件将热量转变成压力波输出，实现这一功能的关键部件就是回热器，本文讨论了丝网型回热器能在纯行波状态下起振的临界温度梯度与结构参数及运行参数的关系。     

A Method for Determining the Phase Transition Point of the Bose-Einstein Condensation by Judging the Fitting Errors

In this paper, We demonstrate an approach to determine the phase transition point and critical temperature of Bose-Einstein condensation. During the fitting sequence of time-of-flight images, for just one picture we take four kinds of different calculations instead of only one. By calculating the quantitative least-square errors, which have always been neglected before, we find out that this value can act as a criterion to judge the status of atom clouds. Using this criterion, we can not only discriminate the status around the phase transition point, but can also find the critical point precisely. Also with this method, we can achieve the totally automatical running of calculating programs without human＇s judgments.     

高临界温度超导材料超导性能的检测

高温超导体临界温度Ｔｃ的高低是超导材料性能良好与否的重要判据。本文根据超导体的基本特性（零电阻现象和完全抗磁性）讨论了临界温度Ｔｃ的两种测量方法：电阻法（即四引线法）和电磁感应法，并介绍了获得低于正常液氮沸点温度（７７Ｋ）的减压降温技术。文中给出了对ＹＢａ＿２Ｃｕ＿３Ｏ＿（７－δ）的两种测量方法的条件利结果。     

Rapidly Estimating Natural Gas Compressibility Factor

Natural gases containing sour components exhibit different gas compressibility factor(Z) behavior than do sweet gases.Therefore,a new accurate method should be developed to account for these differences.Several methods are available today for calculating the Z-factor from an cquation of state. However,these equations are more complex than the foregoing correlations,involving a large number of parameters,which require more complicated and longer computations.The aim of this study is to develop a simplified calculation method for a rapid estimating Z-factor for sour natural gases containing as much as 90% total acid gas.In this article,two new correlations are first presented for calculating the pseudo- critical pressure and temperature of the gas mixture as a function of the gas specific gravity.Then,a simple correlation on the basis of the standard gas compressibility factor chart is introduced for a quick estimation of sweet gases' compressibility factor as a function of reduced pressure and temperature.Finally,a new corrective term related to the mole fractions of carbon dioxide and hydrogen sulfide is developed.     

New Monte Carlo Simulations to a Generalized XY Model

A new combination Monte Carlo （MC） technique of the classical Metropolis algorithm and the Swendsen Wang cluster algorithm is proposed. Upon application of the MC technique, the thermodynamic properties of a generalized two-dimensional XY model with chiral Dzyaloshinski-Moriya （DM） interactions are simulated for various DM interactions. The specific heat, order parameter and the integrated correlation time are simulated, We find that there exists a high-temperature Kosterlitz-Thouless-type phase transition related to strong DM spin ehiralities. As the DM strength increases the critical temperature of the Kosterlitz-Thouless phase transition increases, It is shown that the combination algorithm is faster than the Metropolis algorithms.     

普遍色散关系下的热波长

指出目前教科书和文献所用的热波长概念仅适用于非相对论性系统，而本文引进了普遍热波长的概念。由此可使理想量子气体的热力学函数表示成统一的简洁形式，并进一步揭示了热波长的物理内涵。另外还导出玻色－爱因斯坦凝聚温度和费米温度间的普遍关系。