二维稳态传热问题的计算机仿真

热量传输现象在工程技术领域中广泛存在,对二维稳态传热情形下温度场分布的研究有重要现实意义。对于复杂几何形状的物体和非线性的边界条件,分析解法显得无能为力;相比之下,建立在有限元基础上的数值计算是有效和准确的。在传热和流体流动问题的数值计算方面,SIMPLE算法被广泛采用。通过VC和Matlab的混合编程用SIMPLE算法实现了对二维稳态传热问题的计算仿真,描述了温度场的分布。     

空调车室气流流场和温度场的数值模拟

空调车室气流流场和温度场研究是空调车室内气流组织设计及车室内舒适环境评价与研究的基础。空调车室的空气流场数值计算是一复杂热边界条件、气固耦合的传热数值计算问题。该文介绍了空调车室内空气流动的数学模型及复杂边界条件的处理，阐述了车室气流流场和温度场数值模拟采用整体求解法所应注意的问题，SIMPLE和SIMPLER算法的比较，以及通用微分方程中各项的处理方式。最后通过ANSYS／FLOYRAN软件对二维的车室内气流流场和温度场进行模拟，论证了此有限元软件在空调车室数值模拟上的可行性。     

A型地铁空调系统及客室内流场数值分析

为给目前国内A型地铁车辆的舒适度设计提供理论参考,针对地铁车辆静压风道结构特点,基于k-ε两方程湍流模型和SIMPLE算法,建立包含空调送风风道和客室的三维计算模型.对计算模型的空气流动和传热状况进行CFD数值计算.计算过程综合考虑车体壁面传热和人体散热等多种传热.分析计算结果得到客室内温度场和速度场的分布规律,并对空调通风设计方案进行量化评估.计算结果表明:客室内人体头部区域温度场分布均匀,平均温度为26.6℃,最大温差为6℃;车厢内有较理想的气流组织形式,速度分布范围为0.50~0.79 m/s,而且客室端部和中部区域人体头部周围速度较大.将计算结果与欧洲EN 14750-1标准进行对比分析,认为乘客的舒适性较好.     

连铸板坯三维瞬态温度场的软件模拟实现

连铸过程实际是一个凝固传热过程.连铸过程中的铸坯温度分布及其变化对于产品质量是非常重要的,人们不断地研究和调整连铸工艺参数.目的就是为了获得理想的温度分布.近年来广大研究者对铸坯凝固的温度场进行了大量深入细致的研究.并开发出了很多温度场模拟的模型和软件.但大都是二维的,只能用于离线工况的静态模拟,不能有效模拟连铸过程中经常存在的非稳态情况.本文建立了板坯连铸传热过程的三维非稳态数学模型,可以实时的反映不同连铸工艺参数对铸坯温度场的瞬态影响,并将计算结果与实测结果进行了比较来说明模型的准确性.为制定合理的二冷制度,和确定动态轻压下的压下位置提供可靠的依据.     

传热与流动的数值计算与彩色图象显示

本文介绍了在应用计算机进行传热与流动过程数值模拟与彩色图象显示方面的一些初步结果,其中包括一维稳态热传导、一维不稳态热传导、二维稳态热传导、二维充分发展通道内的传热与流动、扩散火焰的发展以及流体中夹带颗粒运动的数值分析与显示等。     

一种单自由度液浮陀螺浮子组件的温度场分析

本文在对单自由度液浮陀螺浮子组件进行传热过程分析的基础上，应用有限元软件ANSYS Workbench进行了仿真和计算，得到两种工况下浮子组件三维稳态温度场分布。     

基于MPI的二维稳态温度场的并行计算

作为颗粒离散元软件并行化的前期研究,对二维稳态导热问题的有限差分法求解程序进行了并行化处理.并行算法将计算域划分为若干个子域,并将各子域上的迭代计算任务分配给相应的处理器执行.同时,算法考虑负载平衡,并采用计算和通信的重叠技术,提高并行算法的效率.通过对二维稳态温度场导热问题的串/并行程序在曙光TC2600刀片服务器上的计算结果进行比较分析,验证了该并行方法的有效性.实验结果表明,计算耗时与通信耗时的比值越大,并行效率越高.     

滚动轮胎有限元建模及温度场仿真分析

研究滚动轮胎温度场分布的问题,为了解决温度场试验较难获得轮胎内部温度,重复性差等缺点,以实体轮胎为建模对象,建立了胎体帘线模型与轮胎橡胶材料模型,并将模型在充气压力下的自由模态各阶频率值与试验值相比较,在验证了可行性和正确性的条件下,嵌入了轮胎生热、传热模型以及试验测得的热边界条件,对轮胎稳态温度场进行了仿真,明确了稳态温度场分布图和轮胎内部最高温度与车速间的函数关系及二次拟合公式,并简单分析了轮胎温度分布规律.仿真结果表明,利用有限元法建立的模型及温度场计算是正确的,可为轮胎的结构和配方设计等方面提供了依据.     

核电站堆芯温度场软测量方法研究

核电站堆芯内部温度是反应堆安全运行的重要参数,由于受到测点安装条件的限制,无法直接测量。为解决该问题,在现有压水堆堆芯功率模型的基础上,结合稳态传热热量守恒方程,构建堆芯温度场的计算模型,推算出堆芯内部温度。并通过数值模拟计算结果与堆芯出口实测值的比较,运用数据不确定度作为判断依据,验证了方法的可行性,得到了堆芯内部不同截面的二维温度分布图,为堆芯内部温度的实时监测提供了理论依据。     

光纤环的热致非互易性噪声理论与实验研究

研究了光纤环非稳态传热过程中的非互易相位噪声特性.根据光纤陀螺在实际应用中环境温度的干扰,通过有限差分法,建立了光纤环时变温度场分布模型,对光纤环在非稳态传热过程中的温度场进行了模拟分析.在此基础上,针对不同绕制结构的光纤环,对其温度漂移进行了数值模拟和比较.实验表明,交叉子绕线方案能更好地抑制光纤环热致非互易噪声的影响,从而能提高干涉型光纤陀螺的长期漂移精度.     

A color object recognition scheme: application to cellular sorting

This paper presents a color object recognition scheme which proceeds in three sequential steps: segmentation, features extraction and classification. We mainly focus on the first and the third steps here. A color watershed using global and local criteria is first described. A color contrast value is defined to select the best color space for segmenting color objects. Then, an architecture of binary neural networks is described. Its properties relies on the simplification of the recognition problem, leading to a noticeable increase in the classification rate. We conclude with the abilities of such a recognition scheme and present an automated cell sorting system. Received: 15 June 2001 / Accepted: 1 July 2002 Published online: 23 April 2003 Correspondence to: O. Lezoray (e-mail: Olivier.Lezoray@info.unicaen.fr)     

Priority assignment in real-time active databases

Active databases and real-time databases have been important areas of research in the recent past. It has been recognized that many benefits can be gained by integrating real-time and active database technologies. However, not much work has been done in the area of transaction processing in real-time active databases. This paper deals with an important aspect of transaction processing in real-time active databases, namely the problem of assigning priorities to transactions. In these systems, time-constrained transactions trigger other transactions during their execution. We present three policies for assigning priorities to parent, immediate and deferred transactions executing on a multiprocessor system and then evaluate the policies through simulation. The policies use different amounts of semantic information about transactions to assign the priorities. The simulator has been validated against the results of earlier published studies. We conducted experiments in three settings: a task setting, a main memory database setting and a disk-resident database setting. Our results demonstrate that dynamically changing the priorities of transactions, depending on their behavior (triggering rules), yields a substantial improvement in the number of triggering transactions that meet their deadline in all three settings. Edited by Henry F. Korth and Amith Sheth. Received November 1994 / Accepted March 20, 1995     

Mariposa: a wide-area distributed database system

The requirements of wide-area distributed database systems differ dramatically from those of local-area network systems. In a wide-area network (WAN) configuration, individual sites usually report to different system administrators, have different access and charging algorithms, install site-specific data type extensions, and have different constraints on servicing remote requests. Typical of the last point are production transaction environments, which are fully engaged during normal business hours, and cannot take on additional load. Finally, there may be many sites participating in a WAN distributed DBMS. In this world, a single program performing global query optimization using a cost-based optimizer will not work well. Cost-based optimization does not respond well to site-specific type extension, access constraints, charging algorithms, and time-of-day constraints. Furthermore, traditional cost-based distributed optimizers do not scale well to a large number of possible processing sites. Since traditional distributed DBMSs have all used cost-based optimizers, they are not appropriate in a WAN environment, and a new architecture is required. We have proposed and implemented an economic paradigm as the solution to these issues in a new distributed DBMS called Mariposa. In this paper, we present the architecture and implementation of Mariposa and discuss early feedback on its operating characteristics. Edited by Henry F. Korth and Amith Sheth. Received November 1994 / Revised June 1995 / Accepted September 14, 1995     

IEC101/104规约在生态小水电一体化LCU中的应用

随着电力系统自动化与计算机网络通讯的不断发展,远动规约也在不断变化和发展,根据国际电工委员会制定的IEC60870-5-101和IEC60870-5-104远动规约,我国已经制定了相应的配套标准DL/T634-1997和DL/T634.5104-2002。其中IEC-60870-5-104作为采用标准传输协议子集的IEC60870-5-101的网络访问。文章讨论了采用IEC60870-5-101/104的必要性,介绍了一体化LCU的通讯结构,详细叙述了规约在生态小水电一体化LCU中的通讯实施过程,说明IEC60870-5-101/104两个国际标准,是能满足各种数据类型的传输和保证通信可靠性的方案,给通信数据的处理带来极大的方便。     

面向对象测试技术的研究与应用

面向对象的测试技术是面向对象开发方法的一个重要方面，它对软件质量和软件重用至关重要。本文描述了有关面向对象测试的一些关键问题，提出了一种面向对象的测试方法，给出了利用Rational公司的测试工具TestMate对C＋＋程序进行面向对象测试的样例。     

统计分析在系统级故障诊断中的应用

本文探讨统计分析在系统级故障诊断中的应用,提出两个概率诊断模型,讨论了给出的两个模型的测试算法及有关测试数据的统计推断。     

View-based navigation using an omniview sequence in a corridor environment

View- and appearance-based approaches have recently been attracting the interest of those involved in computer vision research. We have already proposed a visual view-based navigation method using a model of the route called the ”view sequence,” which contains a sequence of front views along a route memorized in the recording run. In this paper, we firstly apply the omnidirectional vision sensor to our view-based navigation method and propose an extended model of a route called the ”omniview sequence.” Secondly we propose a map named the ”view-sequenced map” which represents an entire corridor environment in a building. A method for the automatic acquisition of a view-sequenced map based on the exploration in a corridor using both stereo and omnidirectional vision is also described. Finally experimental results of the autonomous navigation and the map acquisition are presented to show the feasibility of the proposed methods. Correspondence to: Y. Matsumoto (e-mail: yoshio@is.aist-nara.ac.jp)     

Road feature detection and estimation

Crosswalks and stair-cases are useful road features for outdoor navigation. In this paper, crosswalks and stair-cases are detected by looking for groups of concurrent lines, and edges are then partitioned using intensity variation information. To distinguish them, three methods are developed to estimate the pose: a homography search approach using an a priori model, and finding the normal using the vanishing line computed from equally spaced lines and likewise with two vanishing points. These algorithms, with error analysis carried out, have been applied to real images with promising results, and they are also useful in other shape-from-texture applications. Received: 20 January 2001 / Accepted: 5 October 2002 Published online: 23 April 2003 Correspondence to: S. Se (e-mail: sse@mdrobotics.ca)