关于加强电力施工企业内部控制活动的探讨

从施工合同的签订、材料的采购、分包工程的控制、工程工期的控制、废料的回收和工程尾款的回收等施工工程几个阶段的内部控制活动进行阐述,找到加强企业内部管理,提高电力施工企业竞争力的有效途径.     

Simulations of electromagnetic processes in an asynchronous traction drive of automatic electric braking of an electric train

This paper shows the possibility and effectiveness of using an electric brake of motor railcar rolling stock with an asynchronous traction drive as an automatic brake. Since electric braking is unaffected by low temperatures and it can provide high efficiency protection from wheel slipping and skidding when integrated into a traction drive control system, as well as control braking torque with a high speed. Many motor axes and, hence, high power railcar rolling stock can provide less braking distance at electric braking than does pneumatic braking, which is especially important for emergency braking. However, an electric brake can be used as an automatic one only if it can be driven even in the case of loss of power from the catenary or diesel generator. The possibility in principle and the workability of using an electric brake as an automatic one are analyzed on the basis of mathematical simulations. The electromagnetic processes in an asynchronous traction drive under such conditions are considered, and the actuation time of an electric brake in the absence of supplied power is determined.     

Where do ideas come from? [Retrospectroscope]

The dictionary defines an idea as a mental image. However, for an idea to mature, the mental image needs some stimulus. Coupled with the stimulus has to be the motivation to pursue an investigation. Then there is the need for some experiment to explain an observation. Some relevant discoveries of famous people in science and medicine are discussed, as excellent examples of an idea and its maturation.     

Protecting ideas---Careers in intellectual property and patents [Career Building Blocks]

Patent law is the body of law governing the protection of rights to an invention made by an inventor and/or patent owner (such as a company or other organization which has obtained rights to a patent). Such an invention stems from an idea and may or may not result in a tangible product. Patent law protects the idea, and the owner of such an idea can prevent others from making, using, and selling a product that uses that idea by means of one or more associated patents. In the current global economic scenario, protection of intellectual property means protection from theft of potential profits that an individual or an organization can possibly make by commercialization of a patent and/or a family of patents related to a particular technology.     

大规模混联水库群调度规则研究

根据聚合分解的思想,以能量的形式将水库水电站群聚合成一个等效水库,分析了等效水库各能量因子的物理特性和统计特性,建立了等效水库的调度函数模型,采用逐步回归分析提取调度规则;建立以时段末蓄能最大为目标的出力分配模型,采用遗传算法求解该模型,将通过调度函数得到的时段总决策分配到各个水库水电站.在综合考虑库群各水电站自身约束...     

Linear phase tracking in a coherence modulation electrical sensorsystem using integrated LiNbO3 modulator/demodulator

We report an interferometric sensor system, based on coherence modulation of light and LiNbO₃ integrated optics technology. We describe a phase detection scheme designed to retrieve the absolute phase variations produced by a sensor system where the sensor signal is electronically applied to an electro-optic modulator. The system consists of an imbalanced LiNbO₃ Mach-Zehnder transducer fed by a self-powered charge generating sensor, and an optoelectronic central processing unit including a second electrooptic Mach-Zehnder working as an optical demodulator and featuring a matched path-imbalance. Electrical feedback is applied to this second interferometer in an active demodulation scheme, allowing a linear tracking of the signal phase up to 7-π radians     

The technique of finite-impulse-response filtering applied todigital protection and control of medium voltage power system

A method is presented with which to design a FIR filter based upon two objectives: to allow an easy computation and to be as close as possible to a given frequency response. With the help of an example, an original method is proposed to evaluate the complete sequence of a digital relaying algorithm, based on FIR filtering. It is shown how such an algorithm can be used, not only for protection but also for each function of an integrated protection and control system     

运用区间数逼近算法的电能质量评估研究

首先对电能质量指标实测数据进行了区间估计;其次对电能质量指标进行了熵权系数确定;最后建立了区间数逼近评估模型对电能质量进行客观的评估.通过实例表明,基于熵权区间数逼近的算法能够对不同时段的电能质量进行整体评估.     

运用静态反馈分析设计离散饱和线性系统

给出了控制饱和单输入状态反馈系统是全局渐近稳定还是区域渐近稳定的充分性条件,且对区域渐近稳定的情况计算其不变吸引椭球,运用Ricatti方程迭代法设计控制器以使所得椭球尽量大;对多输入控制饱和系统输出反馈系统,给出其吸引域的描述;最后用算例说明方法的有效性。     

Eyeing a real-time human-computer interface to assist those with motor disabilities

The objective of this study was to design an adaptive, real-time assistive system as an alternate HCI that will give computer access to individuals with severe motor disabilities by means of eye gazing only. It focused on the implementation of an algorithm to smooth out abrupt and unwanted jerky behavior of the mouse cursor due to the saccadic nature of the eye movement via the configuration of an artificial neural network that minimizes the jitter effect based on user characteristics. These characteristics were extracted via the creation of user profiles through an embedded graphical interface.     

A Microcomputer-Controlled Experiment: Root Locus Design

An introductory control systems laboratory which uses a microcomputer to provide an automated and highly flexible set of experiments is presented. Most of the important theoretical concepts which are presented in an introductory course in control systems are illustrated through experiments on an electromechanical system. Particular attention is given to an experiment which illustrates the use of the root locus diagram in the design of control systems.     

Traffic Engineering an Operational Network with the TOTEM Toolbox

We explain how the TOTEM toolbox can be used to engineer an operational network. TOTEM is an open source TOolbox for Traffic Engineering Methods which covers IP- based and MPLS-based intradomain traffic engineering (TE) algorithms, but also interdomain TE. In this paper, we use the toolbox as an off-line simulator to optimise the traffic of an operational network. To help an operator choose between an IP-based or MPLS-based solution, or find the best way to load- balance a network for a given traffic, our case study compares several IP and MPLS routing algorithms, evaluates the impact of hot-potato routing on the intradomain traffic matrix, and analyses the worst-case link failure. This study reveals the power of a toolbox that federates many traffic engineering algorithms.     

Prototyping for Industrial Applications [Industry forum]

An FPGA is a good vehicle for creating a prototyping system for checking out an industrial product concept and functionality. High nonrecurring engineering (NRE) cost makes an ASIC suitable only for very high-volume products, such as handheld game terminals and cellular phones. For medium-volume products, the HardCopy ASIC is a lower-cost and lower-power replacement for an FPGA. The HardCopy ASIC is a custom device that is created by incorporating the advantages of an ASIC into an FPGA by removing the resources that are not required in the final device. The power and performance of Hard-Copy ASICs are comparable to those of standard-cell ASICs. Altera's design software enables a single-toolset transition from an FPGA to the HardCopy ASIC.     

智能电网信息化应用能力指标体系的评估算法

随着国家智能电网建设的推进,亟需研究一套行之有效的评价体系和评估方法,对智能电网进行科学、合理、全面的评价,以便为智能电网的发展规划提供科学指导,为智能电网的运行管理提供决策依据。文章系统研究了智能电网信息化应用能力指标体系的评估方法,从5个层次构建了智能电网信息化应用能力评价指标体系,建立了基于层次分析法的指标体系评估模型,并提出了层次分析法中随机成对比较矩阵生成的一个抽样方法,最后,给出了智能电网信息化应用能力的评估算法。     

Unbalanced magnetic pull induced by arbitrary eccentric motion of cage rotor in transient operation. Part 1: Analytical model

Eccentric rotor motion of an electric motor induces an unbalanced magnetic pull. This eccentricity force may couple the electromagnetic system with the flexural vibration modes of the shaft. This paper presents an analytic model for this eccentricity force allowing an arbitrary rotor motion and transient operation. The general equations were simplified for the constant flux and steady-state operation. These simplified equations correspond well to the results presented earlier.     

Unbalanced magnetic pull induced by arbitrary eccentric motion of cage rotor in transient operation. Part 2: Verification and numerical parameter estimation

Eccentric rotor motion of an electric motor induces an unbalanced magnetic pull. This eccentricity force can be described using a simple parametric model with physical parameters. This model allows an arbitrary rotor motion and transient operation. This paper presents an effective method to estimate the parameters from simulation results of electromagnetic fields. Further, the numerical results verify the form of the proposed parametric model in steady-state operation.     

A unique instructional tool for visualizing equipotentials and itsuse in an introductory fields course

Charge Master, an IBM PC-compatible software package that aids in visualizing equipotentials produced by systems of point charges, is described. It accomplishes this via an educational game and an option that plots equipotentials. An assignment designed to accompany the software and its use in an introductory EM fields course are also described. The software has been well received by students     

Suppression of flicker in an arc-furnace supply system by an activecapacitance-a novel voltage stabilizer in power systems

Recently, a good deal of attention has been paid to series active filters (SAF) as an isolator between source and load as a means of avoiding an anti-resonance, or series resonance. Here, the authors propose a novel control strategy to stabilize power system voltage in which an SAF operates as an active capacitor and compensates for voltage drops due to a source impedance. The authors have conducted a simulation and an experiment based on the strategy. The research showed satisfactory results and the authors conclude that the strategy could be applied to flexible AC transmission systems (FACTS)     

Engineering licenses are not for everyone

A license to practice engineering is a privilege granted by a state to call oneself an “engineer” and to practice “engineering” before the public. In most states, these are protected terms having very specific meaning to the public. To become licensed as an “engineer”, an individual has to be willing to meet a minimum standard of education, experience, and examination to demonstrate their technical competence and their concern for the welfare of the public. The educational requirement is provided by an institution offering an engineering program that has been reviewed and accredited by the Accreditation Board for Engineering and Technology (ABET). The degree awarded by such an institution allows one to claim that one is a graduate of an accredited engineering program but not that one is an engineer. The experience requirement is satisfied by engaging in the “practice of engineering” as defined in the empowering statutes of each state engineering licensing board. The examination requirement is met by passing two eight-hour national examinations prepared by the National Council of Examiners for Engineering and Surveying (NCEES), which are offered twice each year. The philosophy and content of the national examinations is the subject of this article