聚合物液体的状态方程

本文分析介绍了三个最广泛使用的聚合物液体状态方程，Ｆｌｏｒｙ、ＳＬ和ＳＳ方程及作者开发的三个新方程ＳＨＴ、ＳＨＴＦ和ＯＣＭ的理论基础和假设，并用１５个聚合物液体、１７个大分子量烃液体和６个常用有机溶剂的Ｐ－Ｖ－Ｔ数据作了比较。结果表明，ＯＣＭ方程精度最好，其他方程精度按ＳＳ、ＳＨＴ、ＳＨＴＦ、Ｆｌｏｒｙ、ＳＬ依次变差。结论是开放胞腔更接近液体的真实结构，空穴的引入可以改进胞腔理论的计算精度，Ｌ－Ｊ位能可以较好地反映液体中分子间的作用力。     

岩盐结构氧化锌物态方程的分子动力学模拟

The equation of state of ZnO with rocksalt phase under high pressure and high temperature was calculated by using the molecular dynamics method with effective pair potentials which consist of the Coulomb, dispersion, and repulsion interaction. It was shown that molecular dynamics simulation is very successful in accurately reproducing the measured molar volumes of the rocksalt phase of ZnO over a wide range of temperatures and pressures. The simulated P-V -T data matched experimental results up to 10.4 GPa and 1273 K. In addition, the linear thermal expansion coe±cient, isothermal bulk modulus and its pressure derivative were also calculated and compared with available experimental data and the latest theoretical results at ambient condition. At extended temperature and pressure ranges, the P-V -T relationship, linear thermal expansion coe±cient, and isothermal bulk modulus were predicted up to 2273 K and 50 GPa. The detailed knowledge of thermodynamic behavior and equations of state at extreme conditions are of fundamental importance to the understanding of the physical properties of ZnO.     

液体饱和蒸气压测定实验仪器的改进

利用U型水银压力计做“电接点定压计” ,集多组缓冲瓶于一身 ,实现了集成供压自动化。实验证明该集成化仪器方便、易用 ,在基础实验中具有应用的实际意义     

Model Equations of State for Liquid Alkali Metals

Abstract

The structure of a model equation of state for the liquid alkali metals is proposed, in response to the observed failure of the principle of corresponding states, and limited tests are presented.     

A methodology to define the Cubic Equation of State of a simple fluid

A method to define the Cubic Equation of State (CES) of a simple substance is presented in this work. CES is constructed with only three parameters of the fluid, namely, the critical compressibility Z_c≡P_cv_c/RT_c, the acentric factor ω ≡ − log  (P^(sat)/P_c) − 1 (where P^(sat) is the saturated vapor pressure), and the saturated vapor volume v^(sat) at the temperature T^(sat)/T_c = 0.7 (where T_c is the critical temperature, v_c is the critical volume, and P_c is the critical pressure). The resulting CES is unique for each substance and, in general, it is different from other known CES in the literature.     

Cubic Spline Method for Solving Second-Order Differential Equations Theory and application to the Thomas-Fermi Model for Ions

A cubic spline method is described which can be used to generate solutions to arbitrary second-order differential equation. The principle advantage is that this method provides accurate solutions which are cast in an analytic form, thus allowing the solutions to be applied to other problems. The method is applied to the solution of the Thomas-Fermi equation for singly and doubly ionized ions, and to the solution of the Schrödinger equation for the ground and first excited states of alkali metal atoms.     

A Robust, Real-Time Voice Activity Detection Algorithm for Embedded Mobile Devices

When an Automatic Speech Recognition (ASR) system is applied in noisy environments, Voice Activity Detection (VAD) is crucial to the performance of the overall system. The employment of the VAD for ASR on embedded mobile systems will minimize physical distractions and make the system convenient to use. Conventional VAD algorithm is of high complexity, which makes it unsuitable for embedded mobile devices; or of low robustness, which holds back its application in mobile noisy environments. In this paper, we propose a robust VAD algorithm specifically designed for ASR on embedded mobile devices. The architecture of the proposed algorithm is based on a two-level decision making strategy, where there is an interaction between a lower features-based level and subsequent decision logic based on a finite-state machine. Many discriminating features are employed in the lower level to improve the robustness of the VAD. The two-level decision strategy allows different features to be used in different states and reduces the cost of the algorithm, which makes the proposed algorithm suitable for embedded mobile devices. The evaluation experiments show the proposed VAD algorithm is robust and contribute to the overall performance gain of the ASR system in various acoustic environments.     

6个聚合物胞腔理论状态方程的分子参数比较

利用Ｚｏｌｌｅｒ提供的ＰＢＤ和ＰＩ两种聚合物系列样品的Ｐ－Ｖ－Ｔ数据，对Ｃｅｌｌ、Ｆｌｏｒｙ、ＳＳ、ＳＨＴ、ＳＨＴＦ和ＯＣＭ６个状态方程的分子参数及其随链结构变化的规律作了比较，得到了一些有益的结论。     

多组分体系单级萃取平衡的Newton-Raphson算法

提出了一种多组分体系串级萃取动态仿真中的单级萃取平衡和物料计算的新同了有机相萃取量,水相洗涤量和混合萃取比等限制条件下两相组成关系的２λ元非线性方程组,构造以水相中某一组分的平衡含量为变量的目标函数,采用Ｎｅｗｔｏｎ－Ｒａｐｈｓｏｎ迭代求解,并以萃取平衡和物料平衡得到该级其它所有组分在两相的含量。     

物理化学中状态函数计算公式的归纳

主要以基本方程、微分式和积分式三种形式,归纳了物理化学状态函数的计算公式。对相类似的公式归类,通过比较便于学生学习和掌握。     

Autopiquer - a Robust and Reliable Peak Detection Algorithm for Mass Spectrometry

We present a simple algorithm for robust and unsupervised peak detection by determining a noise threshold in isotopically resolved mass spectrometry data. Solving this problem will greatly reduce the subjective and time-consuming manual picking of mass spectral peaks and so will prove beneficial in many research applications. The Autopiquer approach uses autocorrelation to test for the presence of (isotopic) structure in overlapping windows across the spectrum. Within each window, a noise threshold is optimized to remove the most unstructured data, whilst keeping as much of the (isotopic) structure as possible. This algorithm has been successfully demonstrated for both peak detection and spectral compression on data from many different classes of mass spectrometer and for different sample types, and this approach should also be extendible to other types of data that contain regularly spaced discrete peaks.

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Graphical Abstract ?

     

酸碱体系pH统一公式及Mathematica精确求算

酸碱体系pH计算是大学分析化学理论课程学习的重点难点,教材涉及繁多的计算公式和近似条件,局限于常见的简单体系。采用酸离解常数（Ka）对酸、碱、两性物质的酸碱反应平衡进行统一描述,建立质子平衡方程,推导得到适用于所有酸碱体系的pH计算统一公式,并使用Mathematica数学软件,便捷地解决精确求解的问题。学习通法通式,并采用计算机精确计算pH,有助于学生整体掌握分析化学理论课程中pH计算的理论基础及解决复杂体系精确计算问题。     

A Novel Algorithm for the Numerical Integration of Systems of Ordinary Differential Equations Arising in Chemical Problems

Simulation of large networks of chemical reactions via the numerical integration of large systems of ordinary differential equations is of growing importance in real-world problems. We propose an attractive novel numerical integration method, that is largely independent from ill-conditioning and is suitable for any nonlinear problem; moreover, the method, being exact for linear problems, is especially precise for quasi-linear problems, the most frequent kind in the real world. The method is based on a new approach to the computation of a matrix exponential, includes an automatic correction of rounding errors, is not too expensive computationally, and lends itself to a short and robust software implementation that can be easily inserted in large simulation packages. A preliminary numerical verification has been performed, with encouraging results, on two sample problems. The full source listing (in standard C language) of an academic version of the algorithm is freely available on request (e-mail address: Valerio.Parisi@roma2.infn.it), together with a very simple but very stiff chemical problem.     

Cubic and Columnar Supramolecular Architectures of Rod–Coil Molecules in the Melt State

The liquid crystalline behavior of compounds 1 (n = 7, 12, 15) differs significantly from that exhibited for conventional rodlike molecules. They organize into layered smectic, bicontinuous cubic or hexagonal columnar mesophases depending on the temperature or the volume fraction of coil segments.     

基于灰狼算法的近红外光谱变量选择方法研究

基于群体智能的灰狼优化(GWO)算法具有参数少、结构简单、易于实现的优点,但在光谱领域的应用较少。该研究将GWO算法引入近红外光谱的变量筛选中,以玉米数据为例,考察了GWO算法中狼群性能、迭代次数、狼群数量及运算效率,并建立了偏最小二乘(PLS)模型对玉米样品中蛋白质、脂肪、水分以及淀粉含量的测定。结果显示,GWO算法运算效率很高,经过参数调优后建立PLS模型,其蛋白质、脂肪、水分及淀粉的保留变量数分别为19、19、14、34,预测均方根误差(RMSEP)从全波长PLS建模的0.245 8、0.122 4、0.339 8、1.105 8分别下降到0.147 7、0.080 1、0.176 2、0.739 8,分别下降了40%、35%、48%、33%,相关系数也相应地提高。因此,GWO算法不仅优化速度快,选择变量数少,还可以显著提高PLS模型的预测精度,是一种近红外光谱变量选择的有效方法。     

Supersaturation,the Spinodal,and Their Prediction Using Equations of State

Abstract

The equations of state of Redlich-Kwong, Soave, BWR, Schmidt-Wenzel, and Harmens-Knapp have been tested and compared in their ability to predict the spinodal and the experimental limits of superheat of pure liquids. The results indicate that only the Peng-Robinson, Soave and BWR equations are capable of predicting reduced kinetic limits of supersaturation above the experimental ones.     

High Pressure Solubility of Light Gases (CH4, C2H6, C3H8, H2S,CO2, N2, Xe,Ar and Kr) and Certain Gas Mixtures in Water from Cubic Equations of State

Journal of Solution Chemistry - Using Henry’s law constant, we applied a previously developed approach to the Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) equations of...     

Experimental Equations of State for Some Organic Liquids Between 273 and 333 K and Up to 280 MPa

Abstract

Five non-linear and three polynomial isothermal equations of state for liquids have been tested for their performance in describing the data of the density and the isothermal compressibility of benzene and cyclohexane from 288 to 323 K up to the melting pressures, and of methanol and ethanol between 273 and 333 K up to 280 MPa. It is found that the best representation is given by an expansion in temperature and density and the second best by the Usual Tait equation. The coefficients of these two equations for the four organic liquids are obtained by fitting the experimental data by a least squares analysis.