基于参数测量、分析的断路器同步操作控制器研制

本文提出了一种基于永磁机构的同步开关的原理、实现及实际应用.该系统采用高速和高精度A/D采集与多处理器设计,可实现对10KV电网电参数的监测、分析,并按控制策略实现断路器最佳投切点的动态选取.系统参数和状态可通过键盘设置和查询,并由液晶屏显示结果.同传统的断路器投切相比,该系统能够有效地减少断路器投切过程中的暂态过程,因而具有实际应用价值.     

抑制10kV电容器组投切操作过电压及涌流的新方法

采用高压大功率可控硅与真空断路器配合使用,完成对电容器组投切操作的新方法。实验结果表明,该方法能有效地抑制电容器投切过程中的操作过电压和涌流,从根本上解决了单一真空断路器投切电容器的不足。     

基于PLC的矿热炉低压无功补偿监控系统的研制

为提高大型矿热炉的工作效率,使矿热炉具有良好的经济技术指标,介绍一种针对矿热炉的自动无功补偿监控系统,该系统中的PLC从电量采集模块获得无功功率、功率因数、谐波参数等电网运行参数,控制其输出节点动态调节电容投切的数量,实现功率因数补偿,通过RS485总线实现远程计算机联网.该系统已在冶炼企业得到成功应用,并通过现场运行证明了该系统的稳定性.     

真空断路器投切电容器的研究现状

本文概述了真空断路器投切电容器组的研究现状,包括断路器投切电容器的事故案例,投切时过电压和重燃产生的原因,以及应该采取的措施,同时介绍了真空断路器投切电容器组的同步分合闸（选相投切）技术,选相投切的精度和影响精度的因数,最后对全文进行了总结,提出了选相投切技术的优越性,为下一步深入研究真空断路器选相投切技术提供参考。     

低压配电网无功优化补偿的实现

针对电网电能质量恶化的问题，以及目前无功补偿装置存在的缺点，为了满足无功优化补偿系统的总体设计要求，采用16位工业级微处理器INTEL80C196kc为核心的单点智能无功优化控制器。该控制器具备自动调整相关控制系统参数以实现控制目标的能力，实现先投先切和循环投切的功能。并且可以避免投切振荡和过补偿，很好的实现无功优化补偿。     

基于嵌入式的无功补偿控制系统设计

为提高尢功补偿系统的实时性和控制精度,设计了一种基于ARMll处理器S3C6410的无功补偿控制系统.该系统采用了实时多任务、可移植、可裁剪的嵌入式μC/OS-Ⅱ操作系统.为解决电容投切振荡所引起的电压波动问题,改进了传统的模糊控制投切策略;为防止无功不平衡所引起的过欠补偿问题,采用了共分补相结合的投切方式.该系统可自动采样计算实现无功自动调节,具有可靠性高、实时性好、投切振荡少的特点,应用前景广阔.     

基于dsPIC30F的相控开关控制器研究

为了减小电容投切所产生的谐波、涌流等暂态过程的危害,提出了一种基于DSP的相控开关控制器,自适应的控制断路器在电压电流的零点投切电容组.控制器采用新型DSP产品dsPIC30F6014芯片为核心.该芯片计算能力强、外围器件丰富,使系统设计得以简化,可靠性提高.仿真测试表明,该系统达到设计要求,工作稳定可靠.     

数据中心供电双电源自动投切系统设计

为更好保证电力系统运行安全,提出数据中心供电双电源自动投切系统设计.结合数据中心供电双电源结构特征,对系统硬件设备及结构配置进行创新优化,并对数据中心供电双电源自动投切系统软件模块功能进行完善升级,简化数据中心供电双电源自动投切控制和运行步骤,最后通过实验证实,数据中心供电双电源自动投切系统在实际应用过程中具有较高的实...     

电磁型开关触头动作的智能控制

采用单片机为核心的电磁型开关、断路器等元件的触头智能过零控制方案,用于延长开关、断路器等元件的使用寿命以及电力拖动等实现无过渡过程或弱过渡过程的投切.     

基于CAN总线的低压智能断路器的设计

低压断路器是供配电系统中一种重要的开关电器.本文介绍以M68HC908GP32单片机为核心的智能断路器的软件设计与硬件实现.该断路器通过拨码开关完成整定电流、脱扣时间、瞬动倍数等参数的设定.通过cAN总线与上位机相连实现通信功能,可由上位机设定断路器的参数,并使上位机获得断路器的各种参数信息,控制断路器的工作状态.     

Emulating an operating system on top of another

In this paper, we present the design of an operating-system emulator. This software interface provides the services of one operating system (Oberon) on a machine running a different operating system (Macintosh), by mapping the functions of the first onto equivalent calls to the second. The construction of this emulator proceeded in four distinct phases, documented here through examples from each of these phases. We believe that our four-phase approach can be beneficial whenever a larger software system needs to be adapted from one architecture onto another. In conclusion, we relate some of the lessons learned and propose guidelines for similar engineering projects.     

基于本体的操作系统安全策略生成模型

随着操作系统安全问题增多,用户对于操作系统的安全需求不断涌现,但是目前能够将用户的安全需求转换成现有操作系统上可配置的安全策略的方法很少。通过建立安全属性和系统调用的匹配关系,将安全属性作为授权系统调用的约束,提出一种基于本体的面向目标的操作系统安全策略生成模型。该模型可支持以白名单形式描述的安全需求的细化,将安全分析者的经验加入到模型中,在推理机的支持下,帮助执行从用户安全需求到具体安全策略的推理,和安全策略一致性检测。具体应用案例说明了该方法的可行性。     

A non-general-purpose operating system

A time-sharing system was developed in order to improve a minicomputer's utilization. Because the facilities provided by the system are not identical to those of a general purpose time-sharing system, additional advantages accrue:

• The system is implement able on a small machine.
• The implementation effort is small.
• A certain class of programs can now be implemented more easily than would be possible under a general purpose time-sharing system.

     

嵌入式Forth操作系统实时调度算法研究

针对目前嵌入式Forth操作系统中缺乏实时调度机制的问题,对基于Forth虚拟机架构的嵌入式操作系统中多任务调度的关键技术进行了研究。采用Forth虚拟机技术,新定义了一种中断任务类型来处理实时突发事件,并给出了一种新的任务调度算法来调度 Forth系统中终端任务、后台任务以及中断任务顺利运行。实验结果表明,改进后的 Forth 系统能够通过实时调度处理突发事件,并且实时响应度高,尤其适用于对实时性有要求的嵌入式环境中,以满足日趋复杂的嵌入式环境对高效操作系统和 Forth 技术的应用需求。     

Improving operating system security

Existing operating system security models implicity measure security with an invalid measurement function, by assuming that denial of access necessarily increases security. Security should be measured against the level of security desired by the owners of the information. A system that is too restrictive can result in breaches of security, as well as a system that is not restrictive enough. This paper shows how this concept should be incorporated into existing security models by applying conventional security access limits to executing files. This new system adds the flexibility to control access according to users and applications. The changes are shown to yield better security than existing operating system security applications. The model has four major improvements over existing models. First, the model considers the implications of user preferences and their reaction to inflexible systems. Second, the paper identifies the lack of granularity as a significant difficulty with existing theories. Third, it explicitly describes a measurement function that allows discussion of the level of security provided by different models. Fourth, the paper shows how the model can stop a Trojan Horse, even in the presence of “covert channels”.     

An operating system independent WORM archival system

We describe the organization of a general purpose data archival system for Write-Once, Read-Many (WORM) optical disks. The system has been designed for large-scale and long-term data storage and retrieval. The archival system is independent of the operating system, flat, self-consistent, does not use any write cache on magnetic disk, and allows the exploitation of auxiliary information on magnetic disk, which can be rebuilt immediately in case of a crash, to speed up file retrieval. A library in C language, called pODLIB, has been implemented as a portable interface to the archival system.     

The Linux operating system

The enormous consumer market for IBM PCs and compatibles has made them affordable. Now, with a free operating system called Linux, these inexpensive machines can be converted into powerful workstations for teaching, research and software development. For professionals who use Unix-based workstations at work, Linux permits virtually identical working environments on their personal home machines. For cost-conscious educational institutions-especially in developing nations-Linux can create world-class computing environments from inexpensive, easily maintained PC clones. And for university students-especially in science and engineering-Linux provides an essentially cost-free path into Unix and X Windows     

16-bit operating systems

16-bit microprocessors have only recently begun to be considered for applications. Now the advantages they can offer for colour graphics and input without keyboards make them competitive with the already established 8-bit devices. This review of 16-bit operating systems covers design features, functions, resources and various problems that arise when several processes occur in one operating system.     

A network operating system for microcomputers

The design philosophy of this portable network operating system is based on the client-server model, and uses layering techniques based on the network architecture proposed by Mimica and Marsden. The PNOS uses a uniform interprocess communications mechanism to handle both interhost and intrahost communications, using the concept of ports. It has been designed for implementation as a ‘guest layer’, using an existing operating system base, thus retaining the system call conventions of the base operating system. In this way, the great majority of application software and utilities written for the base operating system can still be used with PNOS. The pilot version has been implemented over CP/M 80. Issues such as the design of suitable supporting high-level protocols, and handling of different naming conventions, are for further study.     

实时操作系统CPU使用率监测的软件容错研究

在硬件实时操作系统中,系统CPU的使用率是系统性能的一项重要指标,如果任务占据了系统的全部CPU,其它任务将无法继续运行,给系统带来灾难性后果。 通过分析实时操作系统中软件运行的特点,系统设计需要采取一定容错策略,以提高系统可靠性和容错能力。在μC/ OS-Ⅱ实时操作系统下对飞行控制软件中的任务进行实时监测。首先给出在μC/ OS Ⅱ实时操作系统下CPU使用率的计算方法,合理提出CPU的监测周期。其次,给出对CPU使用率异常的故障检测算法,对故障进行故障处置,提高系统的容错能力。最后,通过在MPC5674飞行控制计算机中编写嵌入式飞行控制软件来验证四种对CPU使用率异常的处置方法。仿真结果表明,实时操作系统中CPU的软件容错方法可以有效提高系统可靠性和容错能力。