Computer model for vedavati ground water basin. Part 1. Well field model

It is shown that a leaky aquifer model can be used for well field analysis in hard rock areas, treating the upper weathered and clayey layers as a composite unconfined aquitard overlying a deeper fractured aquifer. Two long-duration pump test studies are reported in granitic and schist regions in the Vedavati river basin. The validity of simplifications in the analytical solution is verified by finite difference computations.     

Computer model for vedavati ground water basin. Part 3. Irrigation potential

An estimate of the irrigation potential over and above the existing utilisation was made based on the ground water potential in the Vedavati river basin. The estimate is based on assumed crops and cropping patterns as per existing practice in the various taluks of the basin. Irrigation potential was estimated talukwise based on the available ground water potential identified from the simulation study. It is estimated that 84,100 hectares of additional land can be brought under irrigation from ground water in the entire basin.     

基于四川西昌中强震数据的区域地震动预测模型

为了探讨基于有限的本地数据建立区域性地震动预测模型的可行性,面向建设西部地震科学实验场的需求,基于中强震数据较丰富的四川西昌附近21次地震的1 250条地震动,分析了区域性预测模型中距离项、震源项以及场地项的特征,标定了模型系数,建立了符合西昌地区地震动特征的预测模型.结果表明:西昌地区的地震动加速度反应谱在近场短周期...     

河网水动力及综合水质模型的研究

采用Preissmann 4点隐式差分格式离散一维圣维南方程组,应用三级联解法求解河网水动力数学模型。基于河道-节点-河道算法的河网水质模型的求解特点,在WASP的水质模型理论基础上,建立了河网非稳态水动力综合生态水质数学模型,考虑了多个污染物变量的耦合计算、变量之间的相互转化和迁移。利用模型对4个河网算例进行验证。验证表明,水位和流量过程计算值与实测值吻合很好,各水质变量的计算值和实测值也符合较好,可见模型是合理可靠的,为河网的水质预测和管理提供了一个较为简便实用的工具。     

Modeling of coalescence of dispersed surface cracks. Part 2. Simulation model for multiple fracture

Abstarct A simulation model for multiple fracture has been developed that reproduces random processes of initiation, growth, and coalescence of dispersed surface cracks. The model is based on the method of statistical simulation (Monte Carlo method) and on the fracture regularities determined experimentally. The main factor responsible for fracture is found to be the coalescence of dispersed cracks, especially at the final stage, which accounts for about 30% of the total life. The ultimate state of a structure is defined by the condition according to which the length of the largest of the available damages is bigger than the calculated value of the maximum crack length.Translated from Problemy Prochnosti, No. 1, pp. 108–117, January–February, 2005.     

三维宽浅河道水流数学模型研究

针对宽浅河道水流的特点,建立了一个基于分层积分降维数值解法的三维浅水紊流数值模型。通过对弯道水流的验证计算,其计算成果和试验值能较好地吻合。笔者等建立的数学摸型特别适合用来解决宽浅河道及河口水流问题。     

Computer Experiment on Deformation of Nanocrystals of the Chromium-Niobium System. Part 2. Mechanical Properties

Molecular-dynamic simulation of the process of stretching of chromium and niobium nanocrystals and chromium-niobium bicrystals was performed to a pair-potential approximation. The authors obtained and analyzed the dependences of the potential energy, the number of pair interactions, work of deformation, stress, reduction in the cross-sectional area, and Poissons ratio on the strain with various orientations of nanocrystals with respect to the tensile force. They calculated the characteristics of elasticity, yielding, and strength of nanocrystals.__________Translated from Problemy Prochnosti, No. 2, pp. 5 – 18, March – April, 2005     

PVA致密膜在异丙醇水溶液中的溶胀平衡模型

根据Flory-Huggins模型和Wilson方程,建立了聚乙烯醇(PVA)膜渗透汽化分离异丙醇水溶液过程的溶胀平衡数学模型,模型计算值与实验值吻合良好.水与PVA膜的相互作用参数小于异丙醇与PVA膜的相互作用参数,说明水在PVA膜中优先吸附溶解,PVA膜可作为优先透水膜实现异丙醇水溶液的分离.异丙醇与水之间的相互作用参数随溶液中异丙醇浓度的升高而增大,说明异丙醇含量越高,膜的溶胀选择性越好,越有利于水在膜中的溶解透过,渗透汽化分离效果越好.模型计算结果表明,随溶液中异丙醇浓度的升高,PVA膜中水浓度逐渐下降,而异丙醇浓度先升高,当溶液中异丙醇摩尔分率超过0.1后趋于稳定,与实验结果一致.     

A 2‐D meshless model for jointed rock structures

According to the characteristic structural features of jointed rock structures, a meshless model is proposed for the mechanics analysis of jointed rock structures based on the moving least‐squares interpolants. In this model, a jointed rock structure is regarded as a system of relatively intact rock blocks connected by joints or planes of discontinuity; these rock blocks are modelled by general shaped anisotropic blocks while these joints and planes of discontinuity are modelled by interfaces. The displacement field of each block is constructed by the moving least‐squares interpolants with an array of points distributed in the block. To deal with the discontinuities of rock structures, the displacement fields are constructed to be discontinuous between blocks. The displacement fields and their gradients are continuous in each block, hence no post processing is required for the output of strains and stresses. The finite element mesh is totally unnecessary, so the time‐consuming mesh generation is avoided. The rate of convergence can exceed that of finite elements significantly, and a high resolution of localized steep gradients can be achieved. Furthermore, the discontinuities of rock structures are also fully taken into consideration. The present method is developed for two‐dimensional linear elastic analysis of jointed rock structures, and can be extended to three‐dimensional and non‐linear analysis. Copyright © 2000 John Wiley & Sons, Ltd.     

浅海负跃层海底单参数模型研究

海底反射特性在浅海声传播中起着决定性的影响。用小掠射角下海底反射损失随掠射角变化率Fd B构建单参数模型可很好地描述浅海海底特性。对单参数模型进行深入研究和改进,建立了在浅海负跃层条件下描述水下声场的海底单参数模型,并利用数值仿真和海上实验数据,对浅海负跃层海底单参数模型水下声场预报的正确性进行了验证。     

Variation of constants in the extended standard model. Part 2. Experimental constraints on the possible variations

The paper discusses possible signs of time variation in the constants for the extended standard model. Existing experimental constraints on the magnitude of the changes are given in order to allow for the possible effects on the metrological characteristics of primary standards for the units of physical quantities. Translated from Izmeritel'naya Tekhnika, No. 9, pp. 15–19, September, 2008.     

Rate-Dependent Elasto-Viscoplastic Constitutive Model for Industrial Powders. Part 2: Model Evaluation

The PSU-EVP model's constitutive parameters for alumina powder are presented. The PSU-EVP model was also used to back-predict the triaxial test data obtained for MZF and alumina powders using constitutive parameters such as the initial voids ratio (e₀), compression index (λ), and spring-back index (κ). In the case of MZF powder, 8 out of 12 back-prediction cases had average relative difference (ARD) values below 20%. In the case of alumina powder, 7 out of 11 back-prediction cases had ARD values below 20%. Based on the back-prediction results, it was concluded that the PSU-EVP model gave fairly good results for most triaxial test data collected at 0.62 MPa/minute and 6.21 MPa/minute. However, the back-prediction results obtained at 20.7 MPa/minute had high ARD values. A sensitivity analysis was done to study the effect of changes in parameter values on the hydrostatic triaxial compression (HTC) and conventional triaxial compression (CTC) back-prediction results. From the sensitivity analysis,±10% (standard deviation variation from ±0.8σ to ±2.3σ) changes in λ and e₀ mean values had marked effect on the HTC results. However, changes in the λ, κ, and e₀ mean values do not produce any noticeable effect on the CTC prediction results. Overall, the PSU-EVP model can be considered to be the first step towards the development of a more robust and accurate model for prediction of stresses and strains in a dry powder compression process.     

Enhanced layerwise model for laminates with imperfect interfaces - Part 2: Experimental validation and failure prediction

In this paper, the layerwise model for laminates with imperfect interfaces and enhanced in Part 1 of this work is confronted with experimental results. The model calculations are validated by comparing its sliding predictions in double lap adhesive joints to the sliding measurements performed in a previous paper. The model predictions agree with the experimental results. Finally, the model is applied to the failure analysis in double lap joints and T-peel joints exhibiting adherend, adhesive and cohesive failures. The model calculations and pertinent failure criteria provide accurate predictions and may become a helpful tool suitable to the design of adhesive joints.     

Transient heat transfer model for normal zone propagation. Part 1 — theory of a bare helium-cooled superconductor

The paper presents a physical model, involving no adjustable parameters of transient heat transfer for normal zone propagation in a composite helium-cooled superconductor. Evaluations are given showing that the main contribution to transient heat flux is made by transverse heat conduction in the coolant. When the zone front passes through a fixed point, the temperature at that point increases drastically, a great temperature gradient appears in coolant which results in transient cooling of the superconductor. The zone propagation equation becomes an integro-differential with a convolution integral. The transient heat transfer intensity is characterized by the introduced dimensionless parameter ?.The problem has been solved analytically for the model with constant coefficients and jump-wise heat release. Formulae have been obtained for the propagation and recovery velocities describing the effect of transient heat transfer (via parameter ?).     

Development of a mathematical model for the effect of temperature and relative humidity on the water vapour permeability of plastic films

The water vapour permeability constants of three flexible films (LDPE, PET and a laminate of both films) were determined at 20, 30 and 40 °C and from 55 to 90% relative humidities. The relationship between permeability and temperature followed the Arrhenius model for the three films. The relative humidity also influenced the permeability of the films. A mathematical model describing permeance (P/X - the permeability of laminates or films) as a function of external relative humidity and temperature was developed. The model can be used to predict the permeance of the three films at different temperatures and relative humidities.     

A solvation model for vapor-liquid equilibria in the system H2O-NaOH from 10 to 85 wt%

Vapor-liquid equilibria in the electrolyte system water-sodium hydroxide are described by using a so-called solvation model. In such a model the formation of ion clusters is assumed, consisting of either of the ions Na⁺ or OH^– being surrounded by water molecules, the number of which depends on the overall molar concentration of sodium hydroxide. Activities of the various components in the liquid phase are modeled by local composition models like the nonrandom two-liquid equation (NRTL) and the Wilson's equation. The vapor phase, assumed to consist of water only, is modeled by the equation of state (EOS) of Wagner and Saul. The models include seven parameters fitted to 230 experimental data points taken from the literature in the range 0.18 kPa to 8 M Pa, 273 to 623 K, and 10 to 85 wt% NaOH. The system's pressure resulting from aT x p calculation procedure can be represented with a mean relative deviation of 1.3%.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

虹桥机场2号航站楼空调冷冻水系统手动调试

对虹桥机场2号航站楼空调冷冻水系统及其手动调试方法进行介绍,并分析采用直供式水系统的优点。     

Physico-Phenomenological Model of Metal Resistance to Plastic Deformation for the Calculation of the Processes of Metal Plastic Working. Part 2. Particular Cases of the Model and Its Experimental Validation

Particular cases of the model with reference to cold, warm, and hot deformation conditions have been considered. Parameters of the model have been determined by means of experimental stress–strain curves. For a group of low-carbon, medium-carbon, and low-alloy steels, it has been shown that the proposed model describes satisfactorily resistance to deformation in a wide temperature and strain-rate range with allowance for the effect of the loading history, which is related to the strain-rate time dependence.