Viscosity of Some Binary Mixtures of Arenes

The viscosity of 12 binary mixtures of benzene+toluene, +ethylbenzene, +isopropylbenzene, +tert-butylbenzene; toluene+ethylbenzene, +isopro- pylbenzene, +tert-butylbenzene; ethylbenzene+isopropylbenzene; isopropylbenzene+tert-butylbenzene; o-xylene+m-xylene; m-xylene+p-xylene; and p-xylene+o-xylene has been measured over the entire range of composition. The viscosity deviations and excess Gibbs energy of activation G ^*E of viscous flow based on Eyring's theory have been calculated. The results have been analyzed in terms of the change in the structure of pure component molecules. The viscosity data have been correlated with the equations of Grunberg and Nissan; Hind, McLaughlin, and Ubbelohde; Tamura and Kurata; Katti and Chaudhri; McAllister; and Heric and Brewer. The Prigogine–Flory–Patterson– Bloomfield–Dewan (PFPBD) theory has been applied to analyze the excess viscosity of the present binary mixtures.     

Prediction of Magnetic Susceptibilities in Diamagnetic Binary Fluid Mixtures

A model is proposed to predict magnetic susceptibilities in diamagnetic binary fluid mixtures. The model predictions are compared to experimental information for nine binary systems including polar and non-polar compounds. The predictions are also compared to the results obtained from the traditional Boyer-Donzelot equation. For all systems analyzed, the model predicted magnetic susceptibilities closer to the experimental values than those predicted from the Boyer-Donzelot equation. The deviations from the experimental values decrease when the binary system exhibits a positive excess magnetic susceptibility.     

耗能减震结构的摄动分析方法

针对用振型分解法对耗能减震结构进行反应分析中存在的计算精度差且耗时的问题,提出了求解振动方程特征值问题的改进一阶摄动的高精度模态展开法,并推导了强行解耦的振型分解的一阶摄动修正公式。最后通过算例证明,提出的摄动分析法是有效的。     

On Effective Energy Reflectance of Particulate Materials

This paper investigates the effective energy reflectance of materials comprised of a continuous matrix embedded with fine-scale particles of different electric permittivity and magnetic permeability. The specific objective is to determine under what conditions will increasing the particulate volume fraction initially increase (or decrease) the overall reflectance from a pure-matrix base state and, with further increase in volume fraction, reverse the trend, i.e. decrease (or increase) the effective reflectance. The importance of this condition is that it indicates when the correlation of a specific level of reflectance to a specific volume fraction of particles may not be unique, even when the properties of the particles and matrix are fixed.     

Materials Sliding Wear Model Based on Energy Dissipation

A mathematical model is developed to correlate the volumetric wear of materials with the dissipation energy in sliding contacts. In the analysis, the wear of contacting materials originating from the energy loss due to friction process in the contact is studied. Two mechanisms responsible for energy loss at contact are considered. The first is the amount of energy spent to import plastic deformation and the second is the elastic energy of the particulate. The energy loss due to elastic and plastic deformation is calculated. The statistical loss of energy is calculated for two rough surfaces by the assumption that there is negligible change in the statistical parameters of the surface during wear. The model can be useful to predict the service lifetime of components and eventually structures. The results showed that the amount of dissipated energy and the volumetric loss increased with increasing normal load. Also, changing the normal load changed the rate of energy dissipation per unit sliding distance.     

岩石变形破坏过程中的能量传递和耗散研究

岩石变形破坏的过程是和外界产生能量交换的过程。从理论上分析了用能量方法研究岩石破坏问题的合理性,以及岩石在变形过程中弹性能、塑性能、表面能、辐射能、动能之间相互转化的过程、计算原理、以及对岩石破坏所起的不同作用。并分别从宏观和微观的角度研究了在不同的变形阶段中岩石能量耗散与释放问题。在宏观上,岩石变形前期以弹性应变能的方式存储外界提供的能量,同时又通过损伤演化等向外界耗散能量;变形的后期以剧烈的能量释放为主。微观上,存在多种引起岩石应变硬化和应变软化的机制,岩石存储能量还是向外界释放能量取决于这些微观机制竞争的最后结果,基于此推导了岩石变形中能量的传递方程,用试验研究了能量的转化和平衡,以及耗散能和释放能之间的比例关系。结果表明能量耗散导致岩石强度的降低,而能量释放是造成岩石灾变破坏的真正原因。从能量耗散与释放的观点研究岩石的破坏,可以从本质上把握岩石变形和破坏的物理机理,寻找岩石破坏的真正原因,为实际工程提供参考。     

SMA耗能器的阻尼性能试验研究

设计并制作了伸缩式形状记忆合金耗能阻尼器，并对此器件进行了试验研究。试验结果与理论分析结果吻合程度较好，表明器件的设计是合理的、加工制作的工艺满足了理论要求，为该器件的工程实际应用积累了实践经验。     

二元氮－氟里昂低温混合工质的最佳配比分析

从高技术应用的要求出发，论述了纯质及氮－烃类混合工质的不足，用ＰＲ方程分析了成分配比对二元氮－氟里昂混合工质节流循环特性的影响，指出合理的成分配比对二元氮－氟里昂混合工质是十分必要的。并以不同温度下的△Ｈ＿Ｔ为目标函数，优化计算了一些二元氮，氟里昂低温混合工质的最佳成分配比。     

Discrete Element Modeling (DEM) of the Vertically Vibrated Particle Bed

Discreet element modeling (DEM) is a computational tool used for detailed exploration of dynamic particle bed behaviors. One such application is the analysis of finely sized particle mixtures under the influence of external forces such as vertical vibration, which is difficult, if barely at all accessible for detailed experimental analysis. Here, we examined the differential density dynamic particle bed behaviors, by the application of a modified two dimensional DEM-fluid model that incorporates the gravity and fluid effects, to replicate some of the important experimental based observations of segregation, heaping, tilting, high density particles on top and bottom, and partition cell separation. The simulation results compared favorably with the reported literature on the density segregation attributes such as high density particles on top at vertical vibration frequency of 6.3 and 7 Hz with corresponding dimensionless acceleration magnitude of 1.6 and 2, convection currents at vertical vibration frequency of 30, 40, and 30 with corresponding dimensionless acceleration magnitude of 3.5, 4, and 3, layer separation at vertical vibration frequency of 7 Hz with corresponding dimensionless acceleration magnitude 2 and partition cell separation at vertical vibration frequency of 45 Hz and corresponding dimensionless acceleration magnitude of 2.25 for simulated glass and bronze particle mixture properties.     

螺栓接头非线性模型及其波能耗散

建立了在高频情况下一维构件的波传播模型，针对工程中常见的螺栓连接梁结构，讨论了波在其中传播的特性及能量耗散问题，提出了一种简化的非线性接头模型。分析与实验结果表明：这种非线性模型更能接近实际。波通过梁的螺栓连接时，存在着能量耗散，螺栓松紧程度对能量耗散有较大的影响。在共振频率处，连接部分发生较大的折射。     

Viscosity of Binary Mixtures of Alkyl Acetates with Hexane, Tetrachloromethane, and Trichloromethane

The viscosity for binary mixtures of methyl acetate (MA), ethyl acetate (EA), n-amyl acetate (nAA), isoamyl acetate (iAA), decyl acetate (DeA), and dodecyl acetate (DoA) with hexane and of MA, EA, nAA, and iAA with tetrachloromethane and trichloromethane has been measured at 303.15 K over the entire range of composition. The viscosity data have been correlated with the equations of Grunberg and Nissan; Hind, McLaughlin, and Ubbelohde; Tamura and Kurata; Katti and Chaudhri; McAllister; Heric and Brewer; and Auslaender. The viscosity deviations and excess Gibbs energy of activation G*^E of viscous flow based on Eyring's theory have been calculated. The results have been analyzed in terms of disruption of dipolar association of alkyl acetate and molecular interaction between alkyl acetate and chloromethane.     

PEPT Investigation of Particle Separation in a Novel Vertically Vibrated Particle Separator

Separation of particle mixtures in micron size range is of concern to many industrial processes. The experimental work presented in this article has looked into the operational assessment of a novel vertical vibration driven particle separator by using a positron emission particle tracking (PEPT) technique. In addition to PEPT, a smoke blanket visualization technique was used to track the intestinal air movements during the course of vibration induced particle separation. Three different finely sized glass and bronze particle mixtures that formed an average particle bed heights of 20, 40, 60, 80, and 100 mm in separation cells of thickness 20 and 40 mm were used to investigate the particle separation behavior. For a range of operating conditions, the results showed in favor of low particle bed heights (below 40 mm), lower vibration frequency (30 ± 10% Hz) and a small partition separation gap size of 5 mm for optimum separation of bronze particles in the presence of air.     

Segregation Quantification of Two-Component Particulate Mixtures: Effect of Particle Size,Density, Shape,and Surface Texture

Segregation, which occurs during handling, processing, and storage of particulate material, is highly dependent on properties such as particle size, size distribution (for continuous mixtures) or size ratio (for binary mixtures), particle density, shape, and surface texture. Quantification of the relationship of material properties to segregation becomes an important link in understanding and controlling segregation. Due to lack of well-developed equipment in the market, quantification of segregation of multicomponent particulate mixtures is currently a challenge. In this study, the effects of particle size, density, shape, and surface texture of two-component particulate mixtures (glass beads and mash poultry feed) on segregation were quantified with the use of the second generation of primary segregation shear cell (PSSC-II) developed at Penn State. It was concluded that (1) irregularly shaped (nonspherical) coarse particles or higher porosity of coarse component of a binary mixture lead to higher segregation potential; (2) the higher the density and smoother the surface of the fine component of a binary mixture, the higher the segregation potential; and (3) the fine particle properties, to a certain extent, determine the particle size–related effects such as absolute size and size ratios, i.e., if fine particle properties of a binary mixture change, the size-related effect on segregation potential would definitely change.     

Segregation Quantification of Two-Component Particulate Mixtures: Effect of Particle Size, Density, Shape, and Surface Texture

Segregation, which occurs during handling, processing, and storage of particulate material, is highly dependent on properties such as particle size, size distribution (for continuous mixtures) or size ratio (for binary mixtures), particle density, shape, and surface texture. Quantification of the relationship of material properties to segregation becomes an important link in understanding and controlling segregation. Due to lack of well-developed equipment in the market, quantification of segregation of multicomponent particulate mixtures is currently a challenge. In this study, the effects of particle size, density, shape, and surface texture of two-component particulate mixtures (glass beads and mash poultry feed) on segregation were quantified with the use of the second generation of primary segregation shear cell (PSSC-II) developed at Penn State. It was concluded that (1) irregularly shaped (nonspherical) coarse particles or higher porosity of coarse component of a binary mixture lead to higher segregation potential; (2) the higher the density and smoother the surface of the fine component of a binary mixture, the higher the segregation potential; and (3) the fine particle properties, to a certain extent, determine the particle size-related effects such as absolute size and size ratios, i.e., if fine particle properties of a binary mixture change, the size-related effect on segregation potential would definitely change.     

Prediction of Critical Properties of Binary Mixtures Using the PRSV-2 Equation of State

The aim of this work is to test the value of the Peng–Robinson–Stryjek–Vera (PRSV-2) equation of state for predicting the critical behavior of binary mixtures. A procedure adopted by Heidemann and Khalil, based on the Helmholtz free energy, has been followed. The resulting two complex nonlinear equations have been solved simultaneously for the critical temperature and volume, while the critical pressure is calculated from the PRSV-2 equation of state itself. Three forms of binary-interaction parameters have been tried: the zero-type, conventional one-parameter type, and Margules two-parameter type. The optimum values of the binary interaction parameters, based on minimizing the sum of the squares of the relative errors between predicted and experimental critical temperatures, have been calculated for 20 polar and nonpolar systems. The Margules two-parameter type gives the best results, but its mathematical derivation is cumbersome and it requires more computation time. The standard and the average of the absolute relative deviations in critical properties are included. The predicted critical temperatures and pressures agree well with the experimental results, and are always better than those predicted by the group-contribution method. The deviations in the predicted critical volumes using any of the tested binary-interaction parameter types are relatively large compared to those using the group-contribution method.     

不同太阳能热源下混合工质ORC系统性能分析

工质性质是影响有机朗肯循环(organic Rankine cycle,ORC)系统性能的重要因素之一。在不同热源温度下,对采用R601、R245fa作为组分的9种不同质量配比工质的ORC系统热力性和经济性进行计算,然后采用灰色关联法对系统性能进行分析及综合评价,并与纯工质的性能进行对比。研究表明,混合工质系统的热力学指标与温度滑移大小近似成反比。当温度滑移大于5K时,纯工质性能更优,且经济性也优于混合工质系统。综合来看,热源温度一定时,灰色关联度随着蒸发温度的升高呈现先增大后减小的趋势;混合工质R601/R245fa(0.1/0.9)的温度滑移最小,其性能也最优。采用R601和R245fa混合作为工质的系统在热源温度为160℃时,灰色关联度最大,系统性能更优。     

Temperature Dependence of the Volumetric Properties of Binary Mixtures Containing Polyethers and 1-Propanol

Excess molar volumes (V ^E _m ) were measured at 288.15, 298.15, and 308.15 K and atmospheric pressure as a function of composition with a continuous dilution dilatometer for the binary mixtures of 1-propanol [CH₃CH₂CH₂OH] with glymes [CH₃O(CH₂CH₂O) _m CH₃, m=1,2,3, and 4]. With these results and other thermodynamic data from the literature, the following mixing quantities have been reported over the complete range of concentration or at equimolar concentration: , volume expansivity; ^E , excess volume expansivity; (V ^E _m /T) _P , and (H ^E /P) _T at 298.15 K. The Prigogine–Flory–Patterson theory (PFP) of liquid mixtures has been applied to estimate interaction, free-volume, and internal-pressure contributions to V ^E _m and to estimate the different mixing quantities for the mixtures. The calculated values using the PFP theory were then compared at 298.15 K with the experimentally obtained results. The PFP theory predicts excess volume V ^E _m values rather well, while the calculated value of (V ^E _m /T) _P and (H ^E /P) _T by using the Flory theory show general variation with the chain length of the glyme. The (V ^E _m /T) _P and (H ^E /P) _T show deviations between theoretical and experimental values that are slightly larger in systems with lower glyme.     

Monte Carlo Simulations of Binary Lennard–Jones Mixtures: A Test of the van der Waals One-Fluid Model

Monte Carlo simulations in the canonical ensemble have been performed in the liquid and supercritical regions of a binary Lennard–Jones mixture with differences in size parameters of 6.4% and energy parameters of 37%. The results are compared with a recent fundamental equation of state employing the van der Waals one-fluid model and new simulation data at the corresponding state conditions of the pure Lennard–Jones fluid. The van der Waals one-fluid model describes the mixture properties well at high densities, while at low densities the predicted internal energies and isochoric heat capacities are too low.     

Phase Behaviors of Binary Hard-Sphere Mixtures Using Simple Analytical Equations of State

Recently, we have proposed a unified analytical equation of state (EOS) for solid–liquid–vapor states of matter, and have examined the thermodynamic properties of argon, carbon dioxide, and methane, as well as binary mixtures of methane and carbon dioxide. Also it has been demonstrated that the EOS can be applied for the solid–fluid transition of hard spheres, by eliminating the attractive part of the EOS. The present work is an extension of the earlier calculations for identical hard spheres, and here we examine the phase behavior of binary hard-sphere mixtures. The hard-sphere EOS employed in this study is

挠性胶管的阻尼减振机理初探

建立了挠性胶管阻尼耗能的简化模型。以此为基础分析了挠性胶管的阻尼耗能的一般规律,并得出了一些新的结论。