CAD应用中的问题之一——关于CAD软件二次开发的研究

本文首先对目前ＣＡＤ／ＣＡＭ应用中存在的问题进行了分析，指出了二次开发问题的重要性；其次对ＣＡＤ二次开发方法进行了论述；最后介绍了我们所开发的二次开发系统。     

VB和AutoCAD间的数据通信技术

文中介绍了流行的Ｗｉｎｄｏｗｓ应用程序开发工具语言ＶＢ和流行的ＣＡＤ软件包ＡｕｔｏＣＡＤ间的三种数据通信技术,以实例详细地阐述了ＶＢ和ＡｕｔｏＣＡＤ间的ＡｃｔｉｖｅＸ接口技术,为以后ＶＢ程序员进行ＡｕｔｏＣＡＤ二次开发开放了ＡｕｔｏＣＡＤ的制定和开发模式,解决了ＶＢ和ＡｕｔｏＣＡＤ间数据接口的难题。     

CIMCAD二维绘图软件的国标化

介绍了对原ＣＩＭＣＡＤ绘图软件进行二次开发，实施标注国标化的改造，形成一个图纸标注符合我国现行标准的国标化软件：ＧＢＣＩＭＣＡＤ；总结了该软件的功能特点，以及在二次开发过程中遇到的一些技术关键及解决途径。     

汽车电器计算机辅助测试

对汽车电器ＣＡＴ系统的多任务，高可靠和具有柔性等特点进行了分析，并以汽车组合开关微电脑测量系统为例，介绍了ＣＡＴ系统的硬件体系结构，ＤＯＳ下多任务测量软件的设计方法和提高测试可靠性的技术措施。     

铝门窗设计,报价及下料系统

介绍一个计算机辅助铝门窗设计、工程报价及优化下料的ＣＡＤ软件。该系统在ＤＳＯ及ＡｕｔｏＬＩＳＰ语言，Ｔｕｂｏ ＰＡＳＣＡＬ语言的基础上，成功的对ＡｕｔｏＣＡＤ软件进行了二次开发。系统开发紧紧抓住铝门窗企业“设计－下料－生产”这条主线，实现了对铝门窗生产加工，备料，成本核算等基础信息的管理，构造出了上有待业特点的ＣＡＤ系统。     

汽车摩托车减振器CAD系统的研制

本文介绍了在微机上开发汽车摩托车减振器ＣＡＤ系统的方法,从理论上对汽车摩托车减振器的设计进行了有益的探讨,并针对一些ＡｕｔｏＣＡＤ二次开发中的技术问题给予阐述。     

在AutoCAD二次开发中Windows风格对话框的使用

介绍了ＡｕｔｏＣＡＤ Ｃ语言开发系统进行了二次开发时，使用Ｗｉｎｄｏｗｓ风格的对话框的编程方法和步骤，并给出了部分程序说明。     

AutoCAD for Windows下液压阀图形数据库的开发

本文介绍了在ＡｕｔｏＣＡＤＲ１２ｆｏｒＷｉｎｄｏｗｓ下如何利用ＡＤＳ开发液压阀的数据库系统以及动态参数化绘图环境，并由此对ＡｕｔｏＣＡＤｆｏｒＷｉｎｄｏｗｓ环境下的二次开发技术进行了讨论。     

电机产品CAD集成环境的设计与实现

该文介绍了电机产品ＣＡＤ集成环境的结构、特点和设计方法;开发了一个基于图形界面的电机产品ＣＡＤ集成环境软件ＥＭＩＥ。软件考虑了与各种分立的电机ＣＡＤ程序的接口,具有较好的通用性,为实现电机产品ＣＡＤ软件的标准化提供了一个新思路。     

基于AutoCAD的组件化程序设计方法

组件化是现代开放软件系统的得要特征之一。本文介绍了ＡＤＳ和ＡＲＸ环境下的ＡｕｔｏＣＡＤ二次开发方法，着重论述基于ＡｕｔｏＣＡＤ的组件化程度设计方法，通过对有限元建模软件ＡｔｕｏＦＥＭ结构体系的剖析，说明了线件化程序设计方法的具体实现与意义。     

Bounds on the multi-clients incremental computing for homogeneous decreasing computation sequences

This paper studies the performance of network-based incremental computing under various message sequences. We show the bounds on the time needed to compute the tasks requested by multiple clients. Our simulation result shows that the expected performance of random message sequences is close to the optimal performance.     

Task assignment in multiple server farms using preemptive migration and flow control

Existing task assignment policies proposed for assigning tasks in stand-alone server farms are not efficient in multiple server farm environments because they have not been designed to exploit the properties of such environments. With the emergence of high speed networks and operating systems that have features such as preemptive migration, the importance of designing task assignment policies for assigning tasks in multiple server farms has increased. Such policies can result in better overall performance compared to those that optimise performance in stand-alone server farms.This paper proposes a task assignment policy suitable for assigning tasks in multiple server farms. The proposed policy, called Multi-Cluster Task Assignment based on Preemptive Migration (MCTPM) is based on a multi-tier host architecture that reduces the variance of task sizes in host queues by processing tasks with similar sizes using a set of hosts that have a distinct task size range. MCTPM controls the traffic flow into server farms via a global dispatching device so as to optimise the performance. MCTPM supports preemptive task migration between servers in the same farm and between servers in different farms.Performance analysis of the proposed policy indicates that significant performance improvements are possible under a wide range of workload scenarios. For example, MCTPM outperforms existing policies such as MC-Random, MC-TAGSPM and MC-MTTPM by factors of 190, 5 and 10.5 respectively under certain scenarios.     

Redundant data transmission in control/estimation over lossy networks

In lossy networks the probability of successful communication can be significantly increased by transmitting multiple copies of a same message through independent channels. In this paper we show that communication protocols that exploit this by dynamically assigning the number of transmitted copies of the same data can significantly improve the control performance in a networked control system with only a modest increase in the total number of transmissions. We develop techniques to design communication protocols that exploit the transmission of multiple packets while seeking a balance between stability/estimation performance and communication rate. An average cost optimality criterion is employed to obtain a number of optimal protocols applicable to networks with different computational capabilities. We also discuss stability results under network contention when multiple nodes utilize these protocols.     

Timing analysis of concurrent programs running on shared cache multi-cores

Memory accesses form an important source of timing unpredictability. Timing analysis of real-time embedded software thus requires bounding the time for memory accesses. Multiprocessing, a popular approach for performance enhancement, opens up the opportunity for concurrent execution. However due to contention for any shared memory by different processing cores, memory access behavior becomes more unpredictable, and hence harder to analyze. In this paper, we develop a timing analysis method for concurrent software running on multi-cores with a shared instruction cache. Communication across tasks is by message passing. Our method progressively improves the lifetime estimates of tasks that execute concurrently on multiple cores, in order to estimate potential conflicts in the shared cache. Possible conflicts arising from overlapping task lifetimes are accounted for in the hit-miss classification of accesses to the shared cache, to provide safe execution time bounds. We show that our method produces lower worst-case response time (WCRT) estimates than existing shared-cache analysis on a real-world embedded application. Furthermore, we also exploit instruction cache locking to improve WCRT. By locking some beneficial memory blocks into L1 cache, the WCET of the tasks and L2 cache conflicts are reduced, resulting in better WCRT. Experiments demonstrate that significant WCRT reduction is achieved through cache locking.     

MPI for Python: Performance improvements and MPI-2 extensions

MPI for Python provides bindings of the message passing interface (MPI) standard for the Python programming language and allows any Python program to exploit multiple processors.     

基于Nucleus Plus操作系统的多实例模式的实现

在对TD_LTE射频一致性测试仪表的开发中,针对同时建立多个承载的需求,引入了多实例管理模式。着重介绍了项目协议栈中基于Nucleus Plus操作系统多实例模式的实现机制。该机制中包含了系统的内存池、队列、任务等组件的初始化,其多实例管理模块有效地完成了消息的路由,同时采用优化后的分区内存池对消息和各实例数据内存进行分配和释放,使内存分配中产生的内碎片降到最低。     

Matrix criterion robust linear quadratic control problem

This paper studies a robust linear quadratic (LQ) control problem with multiple quadratic performance indices. Specifically, a linear model is assumed to be available for each of a prespecified set of operating points of a system. A vector-valued quadratic control performance index is given at each operating point. It is then desired to find the constant feedback gains of a linear controller to obtain satisfactory control performance over all the operating points. This is a realistic case involving the minimization of a vector criterion of vector criteria, i.e. a matrix-valued criterion. The matrix-valued criterion gives insight into standard robust LQ design, and leads to several related vector minimization problems, and to natural procedures for computing a satisfactory non-inferior solution to the matrix-valued minimization problem.     

数据访问的事务处理中间件中等待时间的研究

数据访问的事务处理中间件主要用于分布式的数据库访问的事务处理，采用两阶段提交技术。在两阶段提交中当协调者把任务分支分配到所有的参与者后，需要在等待一定的时间再发出准备消息。等待时间的大小会对分布式系统的并发性产生影响，为了提高系统的并发性，需要对提交等待时间进行估计。该论文对于数据访问的事务处理中间件任务的类型较少的特点，提出了一种对于提交等待时间进行较准确估计的方法，且针对不同类型的数据访问(单个操作和批量操作)采用不同的时间估计，提出了长事务的概念。     

基于1553B总线的先进飞机电气终端的仿真

该文对基于MIL-STD-1553B数据总线的先进飞机配电系统的结构和功能进行了分析,重点论述了仿真系统的结构及仿真软件的实现.配电自动化过程是个多任务并发过程,如何协调各任务的运行,提高系统运行效率,是仿真软件的关键.该文从仿真软件的功能出发,论述了系统任务的划分,并结合Windows消息驱动机制和多线程概念,提出了一种Windows环境下实现多任务管理的方法;同时,该文从实时数据库和线程安全类概念出发,论述了一种用于管理系统运行过程中公用数据的简易的内存数据库管理系统,两者的结合很好地解决了上述问题.调试结果表明,系统运行可靠,达到了功能要求,性能良好,具有很好的仿真效果.