Correlating and Predicting the Solubilities of Solid n-Alkanes in Supercritical Ethane Using Carnahan-Starling-van der Waals Model

The solubilities of some solid n-alkanes in supercritical ethane were correlated and predicted in this paper using the Carnahan-Starling-van der Waals model with a density-dependent parameter of a12.At a given temperature,the linear fit of the parameter of a12and the density of the supercritical solvent was used for solubility correlation,resulting in an average absolute average relative deviation(AARD)of 8.68%,which was between the values of the semiempirical models and the other compressed gas models used in this article.In the linear fit of the parameter of a12and the density of the solvent,the regressed slope m and intercept n of the linear fit can be correlated with the carbon atom number of solid n-alkanes and then the solubilities of solid n-alkanes in supercritical ethane can be predicted with the intercept n and slope m.The average AARD in solubility prediction was 26.99%.

Time Delay Induced Oscillation: An Example on a Class of <i>n</i>Coupled Van Der Pol Oscillators Model with Delays

In this paper, a class of n coupled van der Pol oscillator model with delays is considered. By employing an analysis approach, some sufficient conditions to guarantee the existence of stability and oscillations for themodel are obtained. Examples are provided to demonstrate the results.

Impulsive Control for T-S Fuzzy Model Based Chaotic Systems Consisting of Van der Pol Oscillators Coupled to Linear Oscillators

This paper proposes an impulsive control scheme for chaotic systems consisting of Van der Pol oscillators coupled to linear oscillators （VDPL） based on their Takagi-Sugeno （T-S） fuzzy models. A T-S fuzzy model is utilized to represent the chaotic VDPL system. By using comparison method, a general asymptotical stability criterion by means of linear matrix inequality （LMI） is derived for the T-S fuzzy model of VDPL system with impulsive effects. The simulation results demonstrate the effectiveness of the proposed scheme.

Study and Modeling of the Grinding Kinetics of Reactive Rocks in a Cement Laboratory

This article focuses on the study of crushing rocks that can replace clinker in low-carbon cement. A laboratory ball mill was used, varying the duration of the grinding. It has been observed that the specific surface of rocks changes in a nonlinear way with time, due to the agglomeration of particles. To this end, a mathematical model describing this evolution, which considers van der Waals forces, has been proposed. And finally, the model was adjusted regarding the experimental data. The results found show that the present model is more accurate than the classical models, because it considers the agglomeration phenomenon.

分布式能源利用的经济性与环境影响研究——基于DER-CAM模型

分布式供能系统是一种先进的供能系统,具有高效、环保、经济等特点,在降低建筑能耗方面潜力巨大。采用DER-CAM模型模拟我国不同气候区的商业建筑分布式能源的经济性与环境影响,得到多技术集成优化能有效减排降本、政策引导与经济刺激会促进分布式能源技术应用等启示,为我国能源合理规划、适宜技术选择以及提升能源效率及经济性提供参考。

Van der Waals状态方程可压缩多流体流动的PPM方法

基于流体体积分数的混合型多流体数值模型,将Piecewise Parabolic Method(PPM)方法应用于可压缩多流体流动的数值模拟,采用双波近似求解多流体van der Waals状态方程的Riemann问题.模拟高密度比且含有激波的可压缩多流体流动,典型的纯界面平移问题模拟结果表明,在接触间断的界面附近,压力和速度没有任何的振荡且界面数值耗散都被控制在2-3个网格之内;一维和二维算例表明,该数值方法可以有效地处理接触间断、激波和多维滑移线等物理问题,并能够比其它多流体数值方法更精细地模拟多流体交界面.

The periodic oscillations in the ENSO recharge–discharge oscillator model

A class of recharge–discharge oscillator model for the El Ni？o/Southern Oscillation （ENSO） is considered. A stable limit cycle is obtained by transforming the ENSO model into the van der Pol-Duffing equation. We proved that there exists periodic oscillations in the ENSO recharge–discharge oscillator model.

Advanced Deterioration Diagnosis Model for Building External Wall Tiles

In 1981 Taiwan entered a period of intense construction, meaning that today many buildings are more than 30 years old. Lack of maintenance has led to frequent safety incidents involving external walls. This study focuses on a deterioration diagnostic model for external wall tiles of aged buildings, using both stage 1 and stage 2 diagnostic methods. The visual test results are categorized based on impact on public safety, and renovation strategies are proposed. Stage 1 diagnosis mainly adopted the DER visual inspection deterioration assessment method. For enhance the accuracy, this research adopted the Infrared Thermal Imaging detection method to double confirm the visual inspection results. After producing an external wall tile Condition Indicator (CI). For stage 1 diagnostic results that fall in a gray area, stage 2 diagnosis was carried out using a tap tone test, followed by fast Fourier transform and pattern recognition to analyze the tapping results. Finally, the study provides a deterioration evaluation criteria for external wall tiles replacement recommendations and a standard operating procedure for deterioration diagnosis. The study also recommends directions for future amendment of regulations, and provides a basis of reference for the government in determining urban renewal, renovation and maintenance strategies.

Simplified Coarse-Grained Dynamic Model for Real Gases

A simplified model is proposed for an easy understanding of the coarse-grained technique and for achieving a first approximation to the behavior of gases. A mole of a gas substance, within a cubic container, is represented by six particles symmetrically moving. The impacts of particles on container walls, the inter-particle collisions, as well as the volume of particles and the inter-particle attractive forces, obeying a Lennard-Jones curve, are taken into account. Thanks to the symmetry, the problem is reduced to the nonlinear dynamic analysis of a SDOF oscillator, which is numerically solved by a step-by-step time integration algorithm. Five applications of proposed model, on Carbon Dioxide, are presented: 1) Ideal gas in STP conditions. 2) Real gas in STP conditions. 3) Condensation for small molar volume. 4) Critical point. 5) Iso-kinetic energy curves and iso-therms in the critical point region. Results of the proposed model are compared with test data and results of the Van der Waals model for real gases.

Zn-RG体系van der Waals势的理论研究

为了对满壳层原子双原子分子间的van der Waals势函数进行必要的补充,从稀有气体同核双原子分子He2、Ne2、Ar2、Kr2、Xe2以及同核双原子分子Zn2的TT势参数出发,应用TT势模型和势参数的组合规则计算得到了Zn-RG体系各分子基态的van der Waals势,并给出了各分子的光谱参数。计算结果与先前的理论和实验值进行了比较,Zn-He、Zn-Ne、Zn-Ar分子的结果与Bera的CCSD(T)结果符合的较好。最后,针对提高计算结果的精确性问题提出了今后研究的方向。

乙醇和环己烷液体混合物的内压

测定了25～65℃温度范围内乙醇和环己烷液体混合物的热压力系数,它们都很好地遵守我们先前提出的修正van der Waals模型.从模型参数B/A^2,可以得到乙醇自缔合的破坏与浓度间的定量关系.混合物的内压不仅取决于两个纯组分的内压,而且还与相互作用参数A_(12)

液体内压的预测和新溶解度参数值

The modified van der Waals’model which has only one molecular size-dependent parameter is used to calculate the internal pressures of liquids.It is found that the model parameter has very good linear relation with the molar volume of liquids at normal boiling point.A group contribution method is established for the molar volume of liquids at normal boiling point.Therefore the internal pressures of various liquids can be predicted.On the basis of the generalized Gibbs free energy model for mixing of liquids,proposed by our previous work,a new solubility parameter had been defined,which is equal to the ratio of the cohesive energy density with the square root of internal pressure.This definition is more strict and its range of application is more exten sive than classical Hildebrand solubility parameter.In present work,the values of new solubility parameter for 170 solvents at 298.15 K are obtained.

泥膜形成与状态划分细观分析及模型试验研究

泥水盾构施工中泥浆在高压作用下侵入土层形成不同状态的泥膜,泥膜的形成机理复杂,但其状态划分依据相对简单。基于离散元程序YADE编制了流体与颗粒相互作用及粒间长程引力作用模型,从粒径比、粒间范德华力、流体初始流速以及泥浆颗粒密度几个方面分析了泥浆侵入土层初始恒速阶段的堆积状态,确定土层最紧密堆积对应的泥膜状态理论下限值。采用静置后的泥浆侵入土层模型试验分析了两组土层粒径的泥膜状态,表明粒径比对泥膜状态的影响与离散元分析结果、泥膜状态划分理论相吻合。初步建立了泥膜形成过程的宏细观联系,弥补了传统过滤理论和离散元法未考虑颗粒侵入土层动态形成泥膜的不足。

一种新的兔症状性脑血管痉挛模型的建立

目的 建立一种结果可靠而制作简单的蛛网膜下腔出血（ＳＡＨ）后症状性脑血管痉挛（ＣＶＳ）模型。方法 双侧颈总动脉结扎后顶骨钻孔２次注血，观察动物神经功能和饮食改变情况，采用激光多普勒法（ＬＤＦ）测量局部脑血流量（ｒＣＢＦ）。结果 ＳＡＨ后动物进食量下降，神经功能出现障碍，ｒＣＢＦ下降、结论 兔颈总动脉结扎、顶骨钻孔２次注血可以制成结果可靠而操作简便的症状性脑血管痉挛模型。

乙醇在正己烷中的解缔与超额焓

测定了不同温度和浓度下乙醇与正己烷液体混合物的热压力系数及内压,并用修正的vanderWaals模型关联了这些实验数据,从模型参数B/A2得到了一个乙醇自缔合随组成而遭破坏程度的公式.根据这个公式设想了一个醇与烃的混合模型,建立了混合物的超额焓方程,它能够满意地描述上述混合物的超额焓随组成的变化规律。

高温高密度氢(氘)的物态方程——离解效应研究

高温高压下流体氢将发生离解化学反应,形成具有相互作用的氢分子和氢原子混合体系,此时粒子间的相互作用复杂。利用单组分流体近似的范德瓦尔斯混合模型,将混合物粒子间的相互作用等效为单组分粒子间相互作用,从而简化了对体系的统计热力学处理;并由自由能函数极小化确定化学平衡时各组分含量、体系的内能、压强。研究了温度在10 000 K以下、密度在0.6 g/cm3以下(相应摩尔体积大于3.3 cm3/mol)区间的热致离解和压致离解现象对流体氢(氘)状态方程的影响。所得结果与双组分流体变分理论计算以及第一原理的分子动力学模拟、蒙特卡罗模拟结果以及二级轻气炮实验数据进行了比较,它们之间的一致性表明:用单组分流体近似的范德瓦尔斯混合模型处理氢(氘)分子的离解区域的物态方程是成功的。

基于数理推导的砂岩地层渗透率计算新模型

为提高砂岩油气藏渗透率测井计算精度,降低渗透率解释模型区域局限性,基于薄膜孔隙模型,通过数理推导,建立了砂岩储层渗透率计算新模型。该模型揭示了渗透率和单位体积与束缚水饱和度之差的平方成正比的新认识。基于岩心资料,通过与Timur模型及区域拟合模型计算结果的对比分析,验证了新模型具有精度高、适用性强的特点。该研究为砂岩油气藏渗透率测井计算提供了新途径。

一种新型仿壁虎爬行机器人的粘附阵列设计

分析了壁虎与表面间的微尺度粘附接触作用模型,在此基础上设计了一种具有主动控制能力的仿壁虎微纳米粘附阵列.给出了粘附阵列各设计参数,并介绍了微纳米阵列的加工工艺方法.

并列双圆柱涡激振动的经验性模型研究

建立一种新的预报并列双圆柱涡激振动响应的经验性模型,根据特定间距比条件下旋涡脱落频率出现分支的现象,提出以两个具有不同固有频率的尾流振子来共同描述结构的近壁尾涡动力特性,同时两个振子均满足van der Pol方程,进而得到结构振子和流体振子的耦合方程组。使用该模型分别对中高质量比和低质量比的并列圆柱涡激振动问题进行数值计算,结果表明,结构的位移响应和最大振动幅值等变化规律与实验结果趋势一致,数值基本吻合。

简化接触模型的月壤离散元数值分析

根据月壤其颗粒级配可归类于粉质砂土。针对真实月壤所处的环境(无水、低重力场、低气压等),将Perko等2001年提出的月壤颗粒间的范德华力植入离散元分析软件PFC2D中,模拟了刚性边界下加入该模型与未加该模型试样的双轴压缩试验,研究了颗粒间范德华力对试样的宏观力学特性与微观颗粒接触的影响。结果表明,颗粒间的范德华力对试样的抗剪强度、体应变以及颗粒平均配位数都有显著的影响。