迭代最小二乘回归方法估算蒙脱石标准生成Gibbs自由能ΔG0f的研究

将迭代最小二乘法应用于硅酸盐矿矿物标准生成Ｇｉｂｂｓ自由能△Ｇ＾０ｆ的估算,以克服早期指数回归方法的一些局限性。     

光学工件高效加工用铁笔结构设计

以现有光学零件常用的加工工艺为基础,分析总结这些工艺所存在的缺陷;针对所存在的问题进行分析,提出新的加工工艺方案,设计新型的加工结构装置。通过加工实验,验证新结构的使用性能和效果。实验结果证实:采用新结构的加工装置,能明显提高产品的生产效率1倍以上,并且能降低人工劳动强度和生产成本等。     

高压下煤对CH4/CO2二元气体吸附等温线的研究

研究了晋城和潞安煤在高压下对纯 CH4,CO2 及其二元混合气体的吸附特性 ,在对混合气体绝对吸附量计算公式推导的基础上 ,对绝对吸附等温线进行了研究 .结果表明 :高压下煤对混合气体的吸附介于纯 CH4和 CO2 之间 ,Gibbs吸附等温线和绝对吸附等温线表现出较大的差异 ;煤对混合气体中 CH4和 CO2 的吸附呈现出不同的吸附特点 ;煤对 CO2 优先吸附 ,并且随着压力的升高 ,煤对 CO2 选择性吸附能力增加 .本研究结果对开展注烟道气提高煤层采收率和煤层埋藏CO2 具有一定的指导作用 .     

噻吩水热裂解平衡计算及反应过程分析

采用乘子法,结合Gibbs自由能最小的概念,计算注蒸汽热采地层条件下,噻吩水热裂解反应体系的平衡组成.根据实验数据和计算结果分析反应过程,认为噻吩水热裂解过程中发生了水解、热解、加氢脱硫、加氢饱和及水煤气转换等反应.平衡计算结果表明,当水/噻吩摩尔进料比小于4时,提高进料比有利于脱硫,并生成更多气体;提高反应温度、降低反应压力有利于提高气体产量,但不利于脱硫.当水/噻吩摩尔进料比大于4时,噻吩平衡转化率达100%,温度、压力、进料比对平衡组成的影响很小.     

Thermodynamics of Al1−xGaxN solid solution: Inclination for phase separation and ordering

Although Al_1−xGa_xN semiconductors are used in lighting, displays and high-power amplifiers, there is no experimental thermodynamic information on nitride solid solutions. Thermodynamic data are useful for assessing the intrinsic stability of the solid solution with respect to phase separation and extrinsic stability in relation to other phases such as metallic contacts. The activity of GaN in Al_1−xGa_xN solid solution is determined at 1100 K using a solid-state electrochemical cell: Ga + Al_1−xGa_xN/Fe, Ca₃N₂//CaF₂//Ca₃N₂, N₂ (0.1 MPa), Fe. The solid-state cell is based on single crystal CaF₂ as the electrolyte and Ca₃N₂ as the auxiliary electrode to convert the nitrogen chemical potential established by the equilibrium between Ga and Al_1−xGa_xN solid solution into an equivalent fluorine potential. Excess Gibbs free energy of mixing of the solid solution is computed from the results. Results suggest an unusual mixing behavior: a mild tendency for ordering at three discrete compositions (x = 0.25, 0.5 and 0.75) superimposed on predominantly positive deviation from ideality. The lattice parameters exhibit slight deviation from Vegard’s law, with the a-parameter showing positive and the c-parameter negative deviation. Although the solid solution is stable in the full range of compositions at growth temperatures, thermodynamic instability is indicated at temperatures below 410 K in the composition range 0.26 ? x ? 0.5. At 355 K, two biphasic regions appear, with terminal solid solutions stable only for 0 ? x ? 0.26 and 0.66 ? x ? 1. The range of terminal solid solubility reduces with decreasing temperature.     

High Temperature Thermodynamics of RE(La,Ce,Pr,Y,Tb)-S-F Systems

ＨｉｇｈＴｅｍｐｅｒａｔｕｒｅＴｈｅｒｍｏｄｙｎａｍｉｃｓｏｆＲＥ（Ｌａ，Ｃｅ，Ｐｒ，Ｙ，Ｔｂ）－Ｓ－ＦＳｙｓｔｅｍｓＨｏｎｇＹａｎｒｕｏ；Ｒ．ＶａｓａｎｔＫｕｍａｒ＊ａｎｄＬｉＬｉａｎｓｈｅｎｇ（洪彦若）（李联生）（ＵｎｉｖｅｒｓｉｔｙｏｆＳｃｉｅ...     

Analytic Convergence Rates and Parameterization Issues for the Gibbs Sampler Applied to State Space Models

In this paper we obtain a closed form expression for the convergence rate of the Gibbs sampler applied to the unobserved states of a first-order autoregression plus noise model. The rate is expressed in terms of the parameters of the model, which are regarded as fixed. For the case where the unconditional mean of the states is a parameter of interest we provide evidence that a 'centred' parameterization of a state space model is preferable for the performance of the Gibbs sampler. These two results provide guidance when the Gaussianity or linearity of the state space form is lost. We illustrate this by examining the performance of a Markov chain Monte Carlo sampler for the stochastic volatility model.     

Evaluation of Non-Ambiguous Critical Micelle Concentration of Surfactants in Relation to Solution Behaviors of Pure and Mixed Surfactant Systems: A Physicochemical Documentary and Analysis

Critical micelle concentration (CMC) is a fundamental physical parameter of surfactant aggregation in solution. The CMC is determined by different methods, tensiometry, conductometry, microcalorimetry, fluorimetry, and so on. However, it is known that though CMC is reported as a single value, in reality, micelle formation occurs over a narrow range of concentration for different experimental procedures produce different results. We shall discuss about a unique procedure of measuring correct CMC applicable to all potential methods used in practice. This is essential for the evaluation of thermodynamic properties of the micelle forming process in pure and mixed states in terms of solution theories. As we in this short documentary want to deal with various aspects of Milton Rosen's research—wherein we have also worked—a few other facets of surfactant chemistry research, besides the micelle formation, are also briefly discussed. In mixed surfactant systems, synergistic effects in various surfactant properties like detergency, foaming, solubilization, and so on are found whereas in some others non-synergistic effects are observed. Dehydration of micelles with an increase in temperature or by the addition of hydrophilic substances may cause clouding to the system. Soluble amphiphilic systems produce Gibbs monolayer at the air/water interface; insoluble amphiphiles form Langmuir monolayers. A documentary of the above aspects will be herein presented and discussed. We mention that this article is neither an original research article nor a review article. This is a mixture of the two: a documentary of both original research and some review of our works presented in memory of Prof. Milton Rosen.     

Measurement accuracy in X-ray computed tomography metrology: Toward a systematic analysis of interference effects in tomographic imaging

In this paper an investigation of interference effects leading to limitations of metrological performance of X-ray computed tomography (CT) used as a coordinate measuring technique is presented. Using reconstruction data, image quality metrics, and calculations of artifact formation, a deeper understanding and explanation of the physical and technical limitations of CT used in dimensional metrology is given. This is demonstrated in a case study using a simple hollow cylinder made of steel as a test object and calibration measurements from a tactile coordinate measuring machine (CMM). Two different threshold determination strategies for surface computation are applied. Within the study it is also shown that CT image properties, threshold determination strategies, and systematic and random measurement errors must have a definite correlation. As a conclusion it is recommended to focus more strongly on the correlation of local CT image quality and data evaluation operations in order to reduce systematic errors in surface computation and to increase repeatability of dimensional CT measurements.