The degree of intelligence of the law of Biot-Savart

The author shows that the law of Biot-Savart is capable of giving the magnetic flux density due to DC currents in complete circuits or segments of circuits. The charge accumulations at the ends of such segments are automatically accounted for in this law. In such cases, the law of Biot-Savart is equivalent to the complete form of Maxwell's equation with the displacement current included. It is concluded that the law of Biot-Savart is more generation and contains more information than is generally assumed     

分布式发电系统对继电保护灵敏度影响规律

研究了分布式电源(DG)对过流保护灵敏度的影响规律,提出了多DG配电网的过流保护修正方案.利用单位电流法和多端口网络法对DG接入配电网后的等效电路进行了计算和分析,理论和仿真证明:单一DG对保护灵敏度的影响规律是由DG短路阻抗和接入位置决定的二次型;多DG接入系统对保护分支电流的影响特性近似看作各DG影响特性曲线的叠加;以系统短路阻抗中点为基准点,两侧按照DG短路容量顺序接入对保护分支电流的影响最小.对反时限过流保护的动作特性曲线进行正向修正和反向校核,使其保持正确的配合关系和配合裕度,从而消除DG对配电网过流保护的影响.     

A systematic class AB state space synthesis method based on MOSFET square law and translinear square‐root cells

A new state space Class AB synthesis method for the design of square‐root domain filter based on the MOSFET square law is proposed in this study. Those circuits designed by the proposed Class AB systematic synthesis method have the advantages of Class AB circuit structure and translinear circuits. Two alternative design procedures were suggested for designing new circuits. Proposed synthesis technique is applied for designing of a first order all‐pass filter and a third order low‐pass filter. Circuits are simulated in PSpice using 0.35 µm CMOS technology parameters. Time domain and frequency domain analysis of the proposed filters are performed, and simulation results of those are also presented. The simulation results show that the proposed synthesis technique is appropriate for the design of different types of filters and has the advantages of Class AB circuit structure. Copyright © 2015 John Wiley & Sons, Ltd.     

Optimal design of third‐order microstrip bandpass filters by direct synthesis technique (DST)

To design microstrip filters is not easy for the sake of their distributed‐element effect. Undoubtedly, to understand their physical mechanism is very important to their design. In this paper, one effective approach to design some third‐order microstrip bandpass filters with each of 2 transmission zeros at each side of the passband is discussed. Lumped‐element equivalent circuits are used to represent these microstrip filters. Then, these lumped‐element equivalent circuits can be synthesized by direct synthesis technique we recently proposed, so that it is likely to calculate initial structural parameters of these microstrip filters and then facilitate their design. Verified by the measured results of the filter designed through the approach in this paper, the performance of the filters is close to ideal frequency responses. Furthermore, another third‐order microstrip bandpass filter is presented, in which open‐circuited stubs at input/output ports are introduced to suppress one specified harmonic to improve out‐of‐band attenuation.     

A Proposed Architecture for Polarization-Switching D/A Converter (PDAC)

The integration of ferroelectric capacitors with very large-scale integrated (VLSI) circuits on semiconductor wafers has been commercially viable for about one and a half decades. The primary applications of ferroelectric integrated circuits have been oriented to non-volatile memories and Gigabit dynamic random access memories (DRAMs). One potential application for ferroelectric capacitors is polarization-switching digital-to-analog converters (PDACs). In principle, PDACs make use of ferroelectric switching; i.e., spontaneous polarization is used as a new medium for data conversion other than the conventional conversion media such as voltage, current and charge. PDACs are analogous to charge-redistribution data converters that make use of charge and are implemented with normal linear capacitors. In addition to using a novel data-conversion medium, polarization-switching data converters require a novel architecture for circuit implementation. Presented here is a proposed architecture for PDACs. SPICE simulations verify the functionality of an 8-bit bipolar PDAC.     

Georg Simon Ohm (of Ohm's law)

Georg Simon Ohm was a famous German scientist in the 19th century. His name was probably spoken more often than any other scientific name by electrical engineers during the Romantic Era of Electrical Engineering. This article gives a brief history of his life and his work that led to his discovery of what is known as Ohm's law.     

Analogue circuits fault dictionary—new approaches and implementation

The d.c. fault dictionary approach has been found very useful for diagnosing hard failures (open circuits and short circuits) in non-linear analogue circuits. In this paper we present the use of several techniques to enhance the capability of the d.c. fault dictionary. These include (1) modelling all non-linearities by piecewise linear characteristics, (2) solving the piecewise linear resistive network by Lemke's complementary pivot algorithm, (3) using multilevel logic operation to compile an integer-code fault dictionary which totally eliminates any post-test calculations. the automatic generation of a fault dictionary for a video amplifier by the use of the computer program HAFDIC is described.     

基于新型趋近律的PMSM反演滑模控制

在永磁同步电机(PMSM)矢量控制系统中,针对传统的PI控制器控制精度不足、超调量大、易受外界扰动影响的问题,本文提出了一种反演滑模控制器替换传统的PI控制器,该反演滑模控制器是由反演法与滑模控制理论相结合产生的,且在趋近律设计方面引入双曲正切函数和系统状态变量,从而形成一种新型趋近律,代替传统的指数趋近律,提高系统的收敛速度,减小滑模抖振现象。在MATLAB/Simulink中搭建仿真模型,仿真结果表明,该方法使系统对电机的转速有着良好的控制效果,与PI控制、传统滑模控制以及变指数滑模控制相比较,具有较好的动态响应性能,转速超调量分别减少了22.15%、18%和2.75%,系统抗扰动能力提高,具有较强的稳定性。     

A fast method for process reliability analysis of CNFET-based digital integrated circuits

Due to aggressive technology scaling in electronic of digital integrated circuits, the circuit reliability is becoming an ever-increasing challenge. In nanoscale technologies, the physical and chemical properties of materials are fundamentally different compared to the larger scales. Therefore, it is necessary to revise the conventional reliability assessment techniques considering their applicability to nanoscale integrated circuits. This paper presents a method for evaluating the circuit reliability at the transistor level of abstraction considering the physical characteristics of the transistors. The proposed method considers various parameters, including the probability of different types of a transistor failure, the topology of logic gates and the logical values of the applied input vectors. Experimental results show that the proposed approach provides accurate transistor-level circuit reliability evaluations (with < 4% inaccuracy) as compared to a reference method based on Monte Carlo HSPICE simulations in addition to more than 800 times speedup. Moreover, to show the comprehensiveness and extensibility of the proposed reliability analysis method for the technologies beyond conventional MOSFETs, it is applied to carbon nanotube field-effect transistor (CNFET) technology as one of the most promising candidates for future CMOS circuits. The obtained results re-acknowledge that in order to achieve a more accurate reliability estimation approach for CNFET circuits, it is necessary to consider the open and short failure probability values individually instead of considering them in the form of a single transistor failure probability.     

Thermoelectric rectification in a graphene-based triangular ballistic rectifier (G-TBR)

A four-terminal ballistic rectifier demonstrating voltage rectification for both electrical (AC/DC) as well as thermal (temperature gradient) inputs is presented. The thermoelectric behavior of the graphene triangular ballistic rectifier (G-TBR) is based on its nonlinear electrical response. The responsivity and noise equivalent power of the device are calculated to be 8870 mV/W and 1.59 nW/Hz^1/2, respectively, at a back-gate voltage of 5 V. The rectified thermal voltage between two isothermal output (lower and upper) terminals is estimated to be 2.8 µV at a temperature gradient of 150 K. Further, the electric and thermoelectric output of the proposed G-TBR is validated by analytical modeling. Such G-TBRs could be used in the future in energy harvesting application to use heat produced by electronic circuitry, integrated circuits (ICs), etc.

     

磁流体密封技术在SF6负荷开关中的应用

摘要:应用磁流体密封技术研制出配用于FLN36-12型SF_6负荷开关的转动密封组件;该转动密封组件具有工作温度宽、零泄漏、零摩擦等优异性能,既克服了传统结构转动密封组件的缺点,又扩展了12kVSF_6负荷开关的使用范围。     

Elementary Relations between G(s) and G(z)

This paper presents an elementary consideration of the relationship between G(s) on the s-plane, and G(z) on the z-plane, where G(z)=?L-1 G(s). Two simple circuits are used as examples, and the magnitudes and phases on the two planes are compared. A simple cardboard-template method of calculation is employed.     

Litigating fear: electrical and magnetic fields (EMF) and the law

A large number of persons in the United States and Europe believe that EMF causes human illness. These illnesses include childhood leukemia, other cancers, high blood pressure, the aggravation of other diseases, and electrical sensitivity syndrome. EMF has become a legal issue as people seek compensation for alleged injuries and try to have power lines relocated away from their homes. This column discusses the problem of making good legal decisions about complex scientific problems such as EMF. Topics discussed include: the history; the Denver study; fear and the law; proving negatives and the law; economic consequences of fear; and fear and the public utility consequences. The author concludes that so far, the courts and most state public-utility regulatory commissions have acted reasonably when dealing with EMF. They have recognized that the potential risk is very small, if there is any risk at all, and that the potential harm from regulation is very high. This is a precarious balance, however, and it could easily be upset by either trial judges allowing EMF cases to be litigated or a state public-utility commission giving in to public pressure and declaring EMF a threat to health. Scientists and others who understand these problems should speak out and try to shape public opinion to diminish the suffering that comes from irrational fears and the social dislocations that follow bad policy choices     

Network Analogs of Maxwell's Field Equations in One and Two Dimensions

Network analogs are developed representing Maxwell's equations in the time domain for one and two spatial dimensions. Maxwell's equations are first cast into matrix form. Then the connection between these matrices and the branch node incidence matrix of the equivalent network is made. Next, the relationship between the field variables (electric and magnetic fields) and the across and through variables (currents and voltages) of the network is demonstrated, resulting in Ohm's law for electromagnetic fields in the time domain. Although not required for the derivation, the connected graphs (electrical circuits) of the network analogs are shown. Finally, the appropriate network analog is applied to the practical problem of determining the transient response of a dipole antenna to an incident electromagnetic field.     

Comments, with reply, on `Comparison of Ampere's law (ACL) and thelaw of Biot-Savart (LBS)' by H.A. Kalhor

The commenters agree with the author of the above-named work (ibid., vol.E-31, p.236-8, Aug. 1988) that the application of Ampere's circuital law can cause confusion in the minds of students. However, it is argued that section III of the original paper further confuses the issue and creates problems that are worse than the one being solved. In addition several minor errors in the original paper are corrected. In replying, the original author points out that for presentation to students, the treatment in section IV of the original is clearer and more easily understandable     

论等耗量微增率和等网损微增率与最优潮流的关系

等耗量微增率准则和等网损微增率准则是经典的电力系统经济运行准则。等耗量微增率准则是电力系统有功负荷分布的最优准则,等网损微增率准则是电力系统无功电源分布的最优准则．而电力系统最优潮流则是近年来经济的调度运行理论。从理论上对等耗量微增率和等网损微增率与最优潮流进行了分析和推导,通过对目标函数的比较、约束条件的比较、物理含义的分析以及仿真算例的证明,表明最优潮流包含了等耗量微增率和等网损微增率．是这2个准则在电力系统中的进一步灵活运用。     

A fractional adaptation law for sliding mode control

This paper presents a novel parameter tuning law that forces the emergence of a sliding motion in the behavior of a multi‐input multi‐output nonlinear dynamic system. Adaptive linear elements are used as controllers. Standard approach to parameter adjustment employs integer order derivative or integration operators. In this paper, the use of fractional differentiation or integration operators for the performance improvement of adaptive sliding mode control systems is presented. Hitting in finite time is proved and the associated conditions with numerical justifications are given. The proposed technique has been assessed through a set of simulations considering the dynamic model of a two degrees of freedom direct drive robot. It is seen that the control system with the proposed adaptation scheme provides (i) better tracking performance, (ii) suppression of undesired drifts in parameter evolution, (iii) a very high degree of robustness and improved insensitivity to disturbances and (iv) removal of the controller initialization problem. Copyright © 2008 John Wiley & Sons, Ltd.     

An Intelligent Universal Virtual Laboratory (UVL)

The Universal Virtual Laboratory (UVL) is a realistic, real-time, electrical engineering virtual laboratory. The software developed targets individuals who do not have adequate mobility of their upper bodies to perform laboratory experiments. To provide a more realistic and enhanced learning experience, the users of the virtual laboratory are allowed the freedom to build and test a wide variety of realistic electrical circuits, and be able to perform curriculum-based experiments. Typically, this laboratory would accompany an introductory electrical circuits course sequence. The virtual laboratory also contains an intelligent lab assistant that can guide the student and answer student queries.     

The use and abuse of insulated/isolated grounding

Various issues concerning insulated/isolated grounding (IG) are addressed. It is unclear whether the IG form of grounding is effective in reducing the effects of common-mode noise on AC supply circuits. Its effects also may be undesirable under some conditions of installation where the observed noise may actually be seen to increase. Solid grounding (SG) can be expected to behave in a manner similar to that of the IG form. The length of the IG circuit or SG circuit can have a considerable effect on the amount of common-mode noise being conducted on the circuit. Large open-loop areas in affected wiring circuits are prone to common-mode noise currents being induced into them from radiated fields. Such loop areas generally must be reduced in order to improve matters. IG and SG forms of grounding may not be helpful in resolving these kinds of problems, while HF forms of grounding, bonding, and shielding are. Zero signal reference grids and planes are recommended as the primary mechanism for common-mode noise current control when they can be installed in a practical manner. It is also noted that the use of flexible metal conduit or liquid-tight flexible metal conduit on IG circuits creates special conditions where an additional ESGC must be installed for the proper safety grounding and bonding of the conduit itself     

一种基于先验信息的 WiFi 室内定位方法

多种室内定位技术中,基于WiFi的定位在基于位置的服务(location based service,LBS)中有着巨大的应用潜力。提出一种新的室内WiFi定位方法,结合分级定位结构,能够有效利用人员行走模式先验信息。该方法在预备粗定位阶段通过上一时刻的位置推断可能区域,通过信号指纹检测器判断可能区域是否正确,通过再次粗定位阶段重新推算可能区域。在精定位阶段,该方法通过最大后验概率密度方法得到位置估计。利用开源数据集进行实验,证明了所提方法相比传统的3种方法(无先验的最大后验、先验kNN和无先验kNN方法),定位精度分别提高了3%、5%和7%。