Mixture equations of state: Composition dependence

This paper discusses theoretical models for the composition dependence of equations of state and compares the quality of predictions against experimental thermodynamic property data. The mean density approximation (MDA) and the van der Waals one-fluid (VDW1) model are compared with hybrid mixing rules (HMR), in which rigorous composition dependence is used for the second and third virial coefficients and the conformai solution model is used for equation-of-state density terms beyond the third virial term. It is found that when values of unity are used for all binary and three-body unlike interaction parameters, calculated densities for methane-normal heptane mixtures have average absolute deviations of 3.54% for MDA, 4.04% for VDW1, and 2.59% for HMR. When vapor-liquid equilibrium calculations were performed for the methane-normal heptane system, average absolute deviations of calculatedK values from experimental values were 16.7% for methane and 36.4% for normal heptane using HMR, whereas when conformal solution model (CSM) mixing rules were used, the results were 34.8% for methane and 66.7% for normal heptane. When the binary interaction parameter for the characterization of interaction energies is determined, it is found to be less sensitive to state conditions in the case of HMR than either MDA or VDW1. These preliminary results suggest the potential of mixture equation-of-state methods which utilize rigorous composition dependence for the lower-order virial coefficients.Paper presented at the Second U.S.-Japan Joint Seminar on Thermophysical Properties, June 23, 1988, Gaithersburg, Maryland, U.S.A.     

New Group-Contribution Method for Predicting Temperature-Dependent Properties of Pure Organic Compounds

A new method for predicting temperature-dependent properties of organic compounds is presented. It is a combination of a group-contribution method with the novel non-random hydrogen-bonding (NRHB) equation-of-state theory. First-order and second-order groups are used to predict the three characteristic scaling constants of the NRHB model. With these scaling constants, one is able to estimate/predict temperature-dependent properties of pure organic compounds such as vapor pressure, liquid density, heat of vaporization and more, in a wide range of temperatures. The influence parameter, κ, which is needed for the estimation of surface tension at any given temperature, is also predicted by the same group-contribution method     

可拓语义下汉代铜镜纹样的创新设计研究

目的 挖掘汉代铜镜纹样文化性内涵及中国传统纹样再设计价值,并将之创新应用于现代产品包装设计中。方法 首先,分析汉代铜镜纹样的社会属性和艺术属性,运用可拓语义分析的设计方法,提取纹样意向词汇并建构可拓表征模型,获得铜镜纹样文化语义设计区间;其次,辅助图解思维,将词汇语义转换为图解语义,进行语义表达分析和量值获取;最后,形状文法代入图解获得新纹样,与铜镜单元纹样结合生成有辨识度和设计价值的新纹样因子,并展开新纹样因子在产品包装上的设计实践。结论 可拓学相关理论可以将隐性知识转化为可显性表示和理性评价的文化基元,该方法为汉代铜镜纹样文化性内涵的内挖与外显提供可行路径,为中国传统纹样在现代产品包装设计领域中的再现提供一种延续性方法。     

Transport properties of 1,1,1,2-tetrafluoroethane (R134a)

New equations for the thermal conductivity and the viscosity of R134a that are valid in a wide range of pressures and temperatures are presented. They were obtained through a theoretically based, critical evaluation of the available experimental data, which showed considerable inconsistencies between data sets, in particular in the vapor phase. In the critical region the observed enhancement in the thermal conductivity is well represented by a crossover model for the transport properties of fluids. Since thermodynamic properties enter into the calculation of the critical enhancement of the transport properties, a new fundamental equation for the critical region was developed also.Paper dedicated to Professor Joseph Kestin.     

天然气超声流量计健康状态评价方法初探

目的天然气计量用超声流量计性能诊断主要采用设定参数阈值的诊断方法,为降低误报、漏报等情况,建立了基于生成对抗神经网络(generated adjoint neural network,GAN)和高维非线性无监督学习的超声流量计健康状态系统诊断方法。 方法采用GAN对原始数据进行学习、生成和扩充,保障超声流量计健康状态诊断建模的数据基础,提取超声流量计在运行过程中的健康状态参数并对其进行时序分析,采用高维非线性无监督聚类学习方法,结合超声流量计失效模式分析,对超声流量计设备进行在线的健康状态诊断。 结果结合超声流量计工作原理和现场实际采集数据,对生成的故障数据集进行了验证。 结论能够准确识别超声流量计当前状态,显著解决传统阈值法误报率、漏报率高的问题,为超声流量计健康诊断的统一管理与开发给予支撑。      

EBPSK调制通信系统中非线性检测的研究

主要讨论扩展的二元相移键控（EBPSK）调制通信系统中的检测技术,以实现高频谱利用率的同时降低能耗。针对高效调制信号码元间差异性较小的特点,接收机利用特殊的冲击滤波器（SIF）将相位变化转化为寄生调幅,增加码元间的差异性,提高能量利用率。同时,引入了支持向量机（SVM）非线性检测方法,解决EBPSK系统中门限检测性能难以达到最优的问题,并给出了维数较少的统一特征向量选取方法。为了减少计算量,选择适用于EBPSK系统的SVM核函数并优化计算方法。仿真结果表明,SVM非线性检测在较少的特征向量维数和低采样率的条件下,可获得最多7 dB的信噪比增益。因而,在EBPSK调制通信系统中选择SVM方法不仅可以提升检测性能,而且抗干扰能力更强,对采样率的鲁棒性更好。     

智能仿生腿的研究

首先在总结智能假腿发展的基础上，针对其新的发展趋势，引出智能仿生腿的概念和研究内容，并探讨了基于基本步态模式和有限状态机的仿生腿步态规划方法，全功能仿生膝关节的设计和稳定性分析；其次研究了仿生腿的控制以及生物信号在仿生腿中的应用；最后指出了智能仿生腿在信息交互、感知、能源动力等方面的发展动向．     

关于一起火灾延伸调查责任追究的思考

文章结合一起火灾事故案例,对火灾延伸调查现状展开定性分析,就具体追责情形、如何落实责任追究及后续整改问题进行初步探讨,对进一步落实火灾延伸调查,优化调查中的各项流程,切实深入推进火灾“一案三查”,将调查结果转化为提高社会火灾防控能力具有一定的现实意义。     

Characteristics of Ions Emitted from Laser-Induced Silver Plasma

In this work, study of laser-induced ions is presented. The plasma was produced by focusing a Nd：YAG laser, with a wavelength of 1064 nm, a pulsed width of 9-14 ns, a power of 1.1 MW and energy of 10 mJ, on silver target in vacuum （10-3 Torr= 1.3332 Pa）. The characteristics of ion streams were investigated by CR-39 detectors located at angles of 0°, 30°, 60° and 90° with respect to normal of the target. The distance between the silver target and each detector was 11 cm. The energy of silver ions was found ranging from 1.5 eV to 1.06E4 eV. There was a high concentration of ions with low energy as compared to those with high energy, showing the energy distribution amongst the ions. The flux of ions was maximum in the axial direction which was decreasing with the angle increase with respect to normal of the target, and finally became minimum in the radial direction. Hence the silver ions have shown anisotropic behaviour.