卫星通信网仿真业务源建模研究

该文首先提出从单用户业务和汇聚业务两方面建模卫星通信网络承载业务的方案。其次,建立了单用户业务源的统一参考模型,给出了描述各种主要业务类型特性的模型参数。然后,分析了汇聚业务的相关特性,给出了描述汇聚业务流自相似特性的几种模型,并对模型进行了比较分析。     

利用开源的数据挖掘平台WEKA进行文本分类仿真实验

煤矿企业自动化系统使用的文本分类中的一个关键问题就是分类方法的选择。为了对常用的分类方法进行性能的综合评价,分析了朴素贝叶斯(NB)、决策树(DT)、支持向量机(SVM)这3种常用的文本分类方法,并利用开源的数据挖掘平台WEKA进行仿真实验。     

数据挖掘语言应用现状研究

数据挖掘系统需要的一个功能是支持临时和交互式数据挖掘的能力,以支持方便灵活而有效的知识发现。可以设计数据挖掘查询语言来支持这一功能,除了数据挖掘查询语言,数据挖掘语言也包括数据挖掘建模语言与通用数据挖掘语言,文章将分别阐述它们的特点,并进行比较。     

基于AutoCAD的FLAC3D地下工程快速建模方法研究

 FLAC3D网格建模主要采用命令驱动模式。在模型工程地质条件较复杂的情况下,其建立三维网格模型的效率明显降低。针对采矿工程领域的数值模拟计算问题,研究了AutoCAD平面图形向FLAC3D模型转换的方法。利用AutoCAD建立了FLAC3D模型,并给出了详细的方法与步骤,实现了利用FLAC3D分析问题时方便、快捷地建立复杂地质模型。     

基于MicroMine的三维可视化地质建模研究

以某铜矿为研究对象,结合大量的矿山地质资料,基于Micro Mine矿业软件系统,建立了矿床的三维可视化模型,并对矿床的资源储量进行了估算与评价,估算结果准确、可靠,矿床三维可视化模型可为矿山开采技术方案的可行性研究提供基础技术平台.     

井-震结合进行河流相储层非均质性表征——以渤海湾盆地黄河口凹陷渤中263油田为例

针对渤海湾盆地黄河口凹陷渤中263油田明化镇组下段浅水三角洲水下分流河道多期次砂体表现出的强烈非均质性,综合应用井-震数据、采用多种方法进行储层平面非均质性定量描述,并体现到地质建模和井位部署中,以降低储量风险、落实潜力、优化开发井位、指导ODP方案(整体开发方案)的编制和决策。岩石物理分析发现,该油田以密度反演为主的拟阻抗可以很好地反映砂、泥岩的变化。通过阻抗体上提取的振幅和相干信息,可以识别平面岩相变化、废弃河道、点坝以及小断层分布。这些信息可以在属性模拟时约束平面渗透率变化。对于强不连续位置,还可以设置虚拟断层以表征砂体内部的不连通性。利用短时窗傅氏变换频谱分解技术以及差异频谱所反映的吸收衰减现象,在频率域通过调谐振幅的成像特征研究了储层横向变化规律,定量求取了砂体厚度,并成功检测了含油气砂体。     

Troubleshooting in geoelectrical prospecting using real‐coded genetic algorithm with chromosomal extrapolation

This work presents a genetic operator developed from mathematical methods of curve extrapolation applied in solving problems in geoelectrical prospection. This operator will assist the production of fitter individuals in the population of a genetic algorithm in which inherent patterns of the best individuals of each generation are recognized. The proposed operator in conjunction with a real‐coded genetic algorithm is compared to five alternative optimization techniques known and used in the application to problems in geoelectrical prospection. Copyright © 2014 John Wiley & Sons, Ltd.     

An advanced VHDL‐AMS PiN diode model: towards simulation‐based design of power converters

This paper focuses on the modeling of a power PiN diode. The focal point basis is the dependence on temperature. The PiN diode remains a difficult device to model mainly during switching transients. An advanced PiN diode temperature‐dependent model is developed and implemented in VHDL‐AMS. Heterogeneous simulation scheme including the circuit wiring parasitic components, the probe effects and the dependent diode models is successfully simulated using SIMPLORER simulator. Experimental data of several commercial PiN diodes are compared to simulation results at different temperature levels. A good rate of consistency is found. Copyright © 2014 John Wiley & Sons, Ltd.     

Numerical modeling and optimization of laser soldering for Micro‐USB electric connector

The laser soldering process was introduced in Micro‐USB electronic packaging in this paper. Numerical modeling and analysis was used for laser process parameter design, because experimental measurements of peak temperature and soldering stress are expensive and often intractable. Accurate knowledge of the residual stress and distortion is a prerequisite for the reliability of the electric connector. The present work proposes a three‐dimensional transient heat transfer model of Micro‐USB package laser soldering process. The calculated thermal cycles and distribution are subsequently used to calculate the distortion and thermal stresses. Meanwhile, the effect of process parameters on residual stress and pin distortion was discussed, and the tensile strength, microstructure, and residual stresses of laser soldering were tested. It can be concluded that the proper laser soldering parameters and power can improve the mechanical property of solder joints on Micro‐USB connector. Copyright © 2014 John Wiley & Sons, Ltd.     

Analysis of geosynthetic tubes filled with several liquids with different densities

A two dimensional model of a geosynthetic tube sitting on a rigid horizontal foundation and filled with several separated liquids with different densities is proposed. The material from which the tube is made is a special synthetic fabric which is inextensible, perfectly flexible, and leakproof. Such a model is useful for modeling a consolidations process in the tube filled with a slurry. The equilibrium equations of the model are formulated. Unknown values like the pressure on the top and bottom of the tube, the tension in the geosynthetic fabric, the length of the contact zone between the tube and the rigid foundation are searched with respect to the given perimeter, the volumes and densities of liquids. Such a problem is solved by the Newton’s method. The initial approximation is obtained by solving a simplified problem with one liquid with the average density. The problem is implemented in a MATLAB code for geosynthetic tubes filled with two, three, and four liquids with different densities. The tubes filled with two different liquids are studied in more detail. The graphs of the relations are compared with the graphs for the tube filled with the single liquid whose density is the average of the densities of the liquids. The comparison enables to discuss the influence of the consolidation process on the height, the contact zone, the pressures and the tension of the tube. The results of the proposed model for a tube filled with a single liquid are compared with another model.