基于非结构化控制流的进化测试方法

结构性测试中,进化测试是一种高效的自动生成高质量测试用例的技术.然而,当程序中出现非结构化特征时,在面向节点的测试标准下,其效率极其低下甚至不及随机测试生成方法.在考虑循环体内部出现跳转(goto、retum)语句的情况下,提出了一种适应度计算方法.该方法在结合传统进化测试适应度计算的基础上,充分考虑了循环次数对于进化搜索的影响.实验结果表明,本适应度函数可以很好地引导进化搜索,并以较小的代价生成测试用例.     

常用的基于控制流的测试充分性准则

本文介绍了几种在软件测试中常用的基于控制流的测试充分性评价准则。这些测试充分性准则适用于用过程式语言、面向对象语言编写的程序。测试人员可用这些准则判断究竟测试了多少代码,还有多少代码未测试到。     

BP神经网络隐层单元数的确定方法及实例

针对BP神经网络隐层单元数不易确定的问题,提出一种在传统的经验公式基础上快速确定隐层单元数的方法。该方法首先借助经验公式确定隐层单元数的取值范围,然后将其扩大,在这个扩大的范围内寻找最优值。以BP神经网络预测交通流量为例,解释说明了具体的步骤,以及网络模型的隐层结构对模型仿真精度的影响。结果表明,采用该方法可快速决定隐层单元数,在实例中采用16个隐层单元数为最佳。     

Investigation of viscosity effect on droplet formation in T-shaped microchannels by numerical and analytical methods

Both numerical and analytical models have been developed to explore the viscosity effect of the continuous phase on drop formation at a T-shaped junction in immiscible liquids. The effects of the generalized power law coefficient, the power law exponent and the yield stress on the mechanism of drop breakup, final drop size and frequency of drop formation are studied by using the numerical three-dimensional volume of fluid model. Droplets coalescence in Bingham fluids is observed in the beginning transient period. The effect of yield stress on drop extension is also discussed. Predictions of drop size by using an analytical force balance show satisfactory agreement with simulation results for Newtonian and power law fluids with different viscosity ratios. The approximation error associated with the analytical model for Bingham fluids is also acceptable. This analytical model can greatly shorten the prediction time as compared with the numerical model, which is helpful for on-line control.     

MEMS-based gas flow sensors

Micro-electro-mechanical system (MEMS) devices integrate various mechanical elements, sensors, actuators, and electronics on a single silicon substrate in order to accomplish a multitude of different tasks in a diverse range of fields. The potential for device miniaturization made possible by MEMS micro-fabrication techniques has facilitated the development of many new applications, such as highly compact, non-invasive pressure sensors, accelerometers, gas sensors, etc. Besides their small physical footprint, such devices possess many other advantages compared to their macro-scale counterparts, including greater precision, lower power consumption, more rapid response, and the potential for low-cost batch production. One area in which MEMS technology has attracted particular attention is that of flow measurement. Broadly speaking, existing micro-flow sensors can be categorized as either thermal or non-thermal, depending upon their mode of operation. This paper commences by providing a high level overview of the MEMS field and then describes some of the fundamental thermal and non-thermal micro-flow sensors presented in the literature over the past 30 years or so.     

一种货运列车编组调度模型及算法研究

根据货运列车编组调度的基本要求,建立了配流模型。利用编组场待编组车节信息,结合到达场列车的实时信息,设计了信息反馈模型。根据配流模型和反馈模型,对列车进行解体和组编,考虑了军需物资和灾需物资的车辆信息,通过调整模型参数,使得模型继续适用那些由于铁路中断,需要绕行的货运列车。改变了传统算法只考虑局部车组信息,而忽视全局车组信息的弊端。因此,该模型具有灵活性。研究了基本的编组调度算法,使用贪心算法和动态规划算法相结合来求解,并分析了该算法的可行性。     

基于曲率流的点模型编辑方法*

为了对点模型表面进行保细节的自由形状编辑,提出了一种基于曲率流的点模型形状编辑方法。该方法定义了基于平均曲率流的光顺算子,通过此光顺算子获得点模型不同光滑程度的曲面表示。运用对应曲面上点之间的向量差进行相应几何细节的抽取,在相邻的曲面表示之间将几何细节剥离出来。用户可以在不同的曲面上进行自由形状编辑,而无须关心几何细节。在变形后的曲面上再将相应的几何细节映射回去,实现对模型保细节的变形。实验结果表明该方法是一种有效的点模型造型算法,在变形的同时,有效地保持了模型表面的细节特征。     

同兴垃圾发电厂DCS控制系统

重庆同兴垃圾发电厂采用的是德国马丁公司(原法国阿尔斯通公司)的逆推式炉排焚烧技术。本文叙述了焚烧技术的工艺流程、DCS控制系统的硬件构成及功能。以全厂集中操作与各工段分散控制相结合的系统运行模式,实现了垃圾焚烧发电厂整体生产过程的监控和低成本运行,提高了垃圾焚烧发电机组的自动化和管理水平。     

基于ADAM5510的新型失重秤设计

通过对老式失重秤工作原理的介绍,分析了老式失重秤在流量测量过程中的误差来源,提出一种基于ADAM5510为控制器的新型失重秤的方法。并阐述了其工作原理及控制方案。实践证明,对于提高失重秤的称重精度和计量精度效果明显。