Nanomagnetic logic: compact modeling of field-coupled computing devices for system investigations

In this paper we investigate error rates of nanomagnetic logic devices with perpendicular magnetization by compact modeling. Two different types of nanomagnets for information propagation and logic computing are introduced. The switching behavior of field-coupled nanomagnets is measured and analyzed. A compact model is derived from physics and experimental results are applied to the magnetic compact model. General requirements for fabrication parameters and clocking fields for reliable operation are extracted. We perform simulations and measurements on single devices to demonstrate the accuracy of the macromodel. Simulations on complex systems show that the error rate of a field-coupled magnetic system strongly depends on the variation of the switching field and the strength of the coupling field between the nanomagnets. The error rate of a 1-bit full adder is investigated for varying dot parameters. The results demonstrate the importance of fast simulation tools for investigations on the design of nanomagnetic computing devices and systems.     

向家坝—上海、锦屏—苏南±800 kV直流线路同走廊时平行接近距离和房屋拆迁范围的确定

向家坝—上海、锦屏—苏南两单回±800 kV直流线路规划沿线同走廊平行走线,在走廊狭窄地区,合理确定它们之间的平行接近距离,对减少房屋拆迁、充分利用走廊资源非常重要。文章根据±800 kV直流线路的电场分布规律,采用加权平均方法控制混合合成电场,并针对线路所经区域的不同分别进行讨论,确定了直流线路在导线取最小对地高度下的最小接近距离和房屋拆迁范围,讨论了增加导线高度对直流线路接近距离和房屋拆迁范围的影响。文中的研究可为合理选取导线高度和线路接近距离提供理论依据。     

Simulation of Field Coupled Computing Architectures Based on Magnetic Dot Arrays

In this paper, we demonstrate that field-coupled nanomagnets can be used for digital information processing. The operation of logic devices is based on a QCA-like architecture, where information propagates by magnetostatic interaction between individual magnetic dots. Micromagnetic simulations indicate that simple logic gates function properly. Efficient design tools, based on the single-domain approximation are developed.     

Effect of Tower Displacement of Parallel Transmission Lines on the Magnetic Field Distribution

The effect of tower displacement of two parallel transmission lines on the magnetic field distribution is extensively studied. Two parallel lines with the same working voltage and having the same span, where artificial tower displacement is made, are modeled and the analysis of the magnetic field distribution is conducted. Natural tower displacements resulting from two parallel transmission lines with different span lengths and different voltages are also simulated to investigate the effect of displacement distance on the field distribution under and around these lines. Typical parallel lines of 275- and 132-kV, running in Kuwait, are modeled for both types of displacement and lateral magnetic field profiles are developed and analyzed. In addition to the effect of tower displacement value on the magnetic field distribution, the effects of one line disconnection, spacing between the parallel lines, phase conductors arrangements and the transmission line loading are examined. The magnetic vector potential concept, as extended to multiconductor transmission lines is used to model and calculate the magnetic field distribution under and around the parallel lines for the different mentioned operating conditions. The presented graphs are useful for setting the maximum allowable line current magnitude, for existing lines, corresponding to a certain safe level of the magnetic field at the edge of right of way.     

Simulation of Power Gain and Dissipation in Field-Coupled Nanomagnets

Coupled nanomagnetic dots were proposed as a promising way to realize computing devices. This paper investigates power flow phenomena in these structures. Using micromagnetic simulations we will demonstrate that the power dissipation of those devices is close to the theoretical lowest limit of any computation and that coupled nanomagnets exhibit power gain, i.e. they are active devices. These results suggest that magnetic computing could be a functionally equivalent replacement of transistor-based circuits in signal processing applications, where robust, low-power operation is crucial.     

电力系统防护石墨炸弹的电磁预警系统方案探讨

防护石墨炸弹对电力系统的攻击是战时保障重要地区供电的重要防护工作之一。运用ANSYS软件仿真模拟石墨纤维对输电线周围电磁场的影响,研究发现,可以根据预警范围的需要,在输电线路中轴线的适当位置安装相距12 m的电场或磁场传感器,以此判断是否有石墨纤维攻击。当有石墨纤维攻击时,发出预警信号,并采取防御措施。     

光纤电流差动保护通信时钟设置

在线路保护中越来越多的采用电流差动保护作为主保护,电流差动保护需要将大量数据信息从线路一侧传向另一侧,误码的大小对保护性能指标影响很大。差动保护装置时钟设定影响通信数据,为尽量减少误码对差动保护的影响,应根据不同的通道方式,采用不同的最佳时钟设置。文章主要分析了差动保护传输数据及不同通道应采用的时钟设置方式。     

NiCuZn铁氧体磁片在NFC天线中的应用及仿真分析

采用线圈式结构设计了近场通信(NFC)天线,并将NiCuZn铁氧体柔性磁片应用于NFC天线系统。利用HFSS仿真软件,研究了天线介质基板厚度、线圈走线宽度、铜线间距以及柔性磁片等对天线回波损耗、谐振频率以及磁场分布的影响。结果表明,天线的走线宽度、走线间距、介质板厚度等参数会影响天线的输入阻抗从而改变谐振频率,最佳的基板厚度0.8 mm、走线宽度a=0.5 mm、走线间距b=1 mm;金属片会导致NFC天线谐振频率偏移,而NiCuZn铁氧体柔性磁片能有效防止金属对天线磁场的干扰以及谐振频率偏移。     

Underground cable magnetic field simulation and management using new design configurations

This paper addresses one of the most important sources of magnetic fields: underground power cables. New design configurations for one, two, three and four cables per phase are presented from a magnetic field perspective. Different management techniques are studied in detail. Judicious placement of cable phases in multiconductor lines to reduce the field effect is implemented by computer modeling and simulations. The state-of-the-art magnetic field simulation package PCFIELD developed by EPRI is used to quantify and present the tool used to manage the field values. The new design configuration cases are very useful from a magnetic field point of view and have low cost schemes that can be easily implemented.     

高压交流海缆电气参数对线路对称性的影响

海南电网拟通过单回500kV交流线路与广东电网实现互联,联网线路采用的海底电缆不实施换位引起的相间差异即为线路不对称的根源,故需要明确海缆段参数是否需要补偿及其对整条线路换位塔塔位确立的影响。为此,根据海缆结构及其在海底分布间距的特点,分析了海缆段三相工作电阻和电容的对称性问题,并结合电缆所交链的内外磁链特性计算了海缆三相工作电感值及其两两差值;根据架空线路各相导线所交链的磁链原理推导了架空段线路三相工作电感值及其两两差值。比较海缆段与架空段工作电感值可知,均不换位且分别等间距水平布置下海缆与架空线单位长度三相电感的两两差值对应相等,因此设计联网线路整循环换位时,海缆段等同于架空线路段考虑,不需补偿海缆段参数的不平衡。     

优化模拟电流法计算超高压输电线路三维磁场

为了获得更准确的输电线路下方磁场的三维分布,使用智能优化算法对模拟电流法中模拟电流的个数与位置参数进行 寻优,解决了普通模拟电流法中模拟电流的位置和个数只能依靠经验来确定的问题,从而提高计算精度。 建立基于输电线路实 际物理形状的三维计算模型,通过不同方法计算上海市松江区洞泾-泗泾 500 kV 线路的三维磁场分布。 将计算结果与实际测 量结果进行对比,结果表明优化模拟电流法的计算误差为 4. 54%,比传统计算方法的 12. 21%降低了 7. 67%。 为优化模拟电流 法计算输电线路的磁场分布提供理论基础,并对高压输电线路的建设有理论指导意义。     

Electromagnetic compatibility of a traction power-supply system and infrastructure elements in areas with high traffic

Electric traction systems are improved as part of the process of updating the entire system that converts the power that is consumed by the transportation process. Application of dc converters to a three-phase alternating current, the use of thyristor converters of the dc voltage level, the creation of highly efficient algorithms for computer control of electric-power conversion, and substitution of commutator dc motors for brushless three-phase ac motors lie at the core of technological improvement of electric traction systems and are now widely used in a number of industrialized countries. This paper proposes new traction power-supply systems for areas with high traffic, which require additional wires to be laid and multiconductor lines to be used. The requirements are formulated, and a methodology for grounding the electromagnetic compatibility of multiconductor lines of traction power supply and infrastructure elements is discussed. It is shown that electromagnetic coupling of lines takes place under conditions of both electric and magnetic effects between two or more electrically long lines. In electrically long lines, the voltages and currents cannot be considered independent of each other. They are interconnected through the impedance of the respective line (similarly to how electrical and magnetic fields of electromagnetic waves are linked with each other through the impedance of space). The studies and analysis that were carried out showed t6hat it is possible to simulate the propagation of electromagnetic waves along multiconductor traction power-supply lines, which allow determining not only the currents and voltages at any given point of a multiconductor line, but also simultaneously induced voltages at an adjacent line. All this allows highly accurate checking of the electromagnetic compatibility of the traction network and longitudinal power supply lines with communication lines and track circuits in areas with high traffic.     

基于磁场测量的配电网单相接地选线及定位新方法

输电线路发生接地故障时,架空线下方磁场能反映线路故障信息。输电线路短路电流大小不同,线路下方磁场相应地不同,即输电线路下方磁场的变化能够完全反映线路中电流的变化,磁场可以应用到电力系统保护中。配电网多为单端电源供电方式,针对配电网的复杂性及传统定位方法精度不高提出了一种基于磁场的非接触式故障选线及定位的新方法。利用磁阻传感器非接触测量杆塔下方磁场,根据磁场的幅值和相位选出故障线路,确定故障点位置。磁阻传感器测量精度高,成本低,故障距离可以确定在两个杆塔之间。利用MATLAB建立线路模型,仿真验证了理论的可行性。     

CES中不同绕制拓扑松耦合旋转励磁变压器性能及分析

针对混合动力汽车用同步电机,其内部的电刷和滑环带来电接触的劣势不可避免.本文提出一种新型励磁系统,它无需电刷和滑环,称为非接触励磁系统(CES).相对旋转部分和相对静止部分同时存在于变压器中.设计毗连型和嵌套型两种针对CES的变压器绕制拓扑进行研究.通过模型建立确定了两种拓扑的最优工作气隙.毗连型和嵌套型绕制拓扑均可以...     

电力变压器励磁涌流和故障电流仿真研究

在研究电力变压器励磁涌流和故障电流特性的基础上 ,应用电磁暂态程序 (EMTP) ,采用不同的模型和方法对变压器励磁涌流和故障电流进行了全面系统的仿真计算和分析。结果表明 ,EMTP能够根据不同的条件和要求有效地实现对变压器励磁涌流和故障电流的仿真     

Accurate measurement method of the position of a buried line

A conventional method to measure the position of a buried line has been used. This method is based on the measurements of magnetic field around a line which conducts a current. However, the pitfall is that the magnetic field generated by an induced current in a secondary line allows considerable measurement errors. This paper describes a novel method to exclude such errors caused by the induced current. While the magnetic field generated by the current in the primary line is in phase with the current, that generated by the induced current delays more than 90° compared to that of the current in the primary line because of a reluctance component of the secondary line. Hence, the 90° component of the magnetic field results from the induced current. This component is measured by a solenoid coil and a lock-in amplifier; the 0° component is measured also and corrected by using the 90° component. Thus, the net magnetic field generated by the current in the primary line is calculated. It is used to determine the correct position of the primary line. The new method is tested by using two buriéd lines and is proved to be useful.     

TDI CCD全景航空相机行转移信号产生方法

TDI CCD全景相机照相时需要给TDI CCD施加行转移信号,为了达到相机照相分辨率要求,需保证像速度与电荷转移速度匹配,一般采用固定频率行转移信号或者采用编码器随动产生行转移信号。分析了上述2种方法的不足,提出了以速率陀螺值为基准的行转移信号产生的方法,即根据速率陀螺数据计算分频倍率,依此对高频时钟分频产生行转移信号,并分析了行转移信号的频率偏差对像移的影响。在环境实验室对该方法进行了验证：利用长焦距精密平行光管模拟目标,把相机固定在振动平台上模拟载体的振动环境,相机对靶标成像,分辨率达到62lp／mm。对比了振动平台静止、振动2种情况下相机拍照图像的分辨率,验证了该方法的可行性。     

基于HPLC通信的配电场域网时间精准同步策略

配电场域网内各节点高精准的时间同步,是实现其业务实时性与精益化的重要技术支撑。针对基于高速电力线宽带载波通信的配电场域网,文中设计了一种时间逐级逐步精准同步策略。首先,通信主站通过远程通信网对场域网中心节点实时校时,使其成为场域网主时钟;其次,依托该场域网低时延性、广播机制和网络基准时间,对网内各节点时钟的时间和频率进行精准监测并获得其偏差;然后,通过重新标定节点时钟温补系数方式调整时钟频率,使节点时间在一个校时周期内逐步达到同步;最后,在实验室和应用现场对该场域网时间同步性能进行测试。测试结果显示,该场域网时间同步准确度在±0.23 s/d以内,比窄带电力线载波配电场域网提高了28%,且避免了在时间同步过程中出现时间空档或时间重复现象。     

Transmission lines magnetic field management feasibility under cost constraints

The scientific issues concerning the relationship between electromagnetic fields and adverse health effects are very complex and difficult to interpret. Epidemiologic data are limited and many results to date are based on small studies with methodological limitations. As a result, there are large differences in the way that these studies are evaluated and interpreted, both within the scientific community in general, and among scientists and Agencies within the federal governments and utilities bodies.This paper contains studies of electromagnetic fields around 138 kV and 230-kV transmission lines and the practical solutions to the field reduction predicted by computer simulation. Chosen were transmission lines 1 and 2 of 138 kV and 230 kV where the data was collected near areas that may be of concern to human occupants. Line 1 consists of two transmission lines of three phase lines. Data was collected with EMDEX II gauss meter approved by EPRI. Analysis of initial measurements was done and compared with simulated data using Southern California Edison's FIELDS program. Feasibility of three new rephasing configurations are evaluated based on the magnitude of magnetic field reduction, the economics, and the practicality. At the edge of the right-of-way, simulation shows a 40 to 80% reduction in magnetic fields. This study demonstrates that rephasing, where applicable, is an effective method to manage magnetic field distribution within, at the edge of, and outside of the transmission line right-of-way. Advantages of each method are presented in this paper with a detail configuration of each simulation, including cost analysis of implementation of such designs.     

Magnetically induced swing movement of overhead power line conductors in a transition span subsequent to an initial fault

An initial electric fault can result in strong magnetic torque exerted on overhead power line conductors, which will make them swing and may bring them to close proximity or in contact with one another, causing a subsequent fault. Computer simulations have been developed for the analysis of the subsequent fault and presented in the authors’ earlier work for level spans and inclined spans that are both of uniform power line construction. However, in practice, a power line topology may require a transition from one power line structure to another. Such a required transition can be realized by a transition span. In this paper, we present a dynamic analysis of swing movement of power line conductors in a transition span subsequent to an initial fault, to track the smallest distance between the conductors, which is an important factor useful for predicting the probability of the subsequent fault. The analysis is much more complex than that for level spans and inclined spans. To address the complexity, we employ coordinate system transformations and establish a common coordinate system, then make use of it in the dynamic analysis. Sample numerical results are presented, analyzed, and checked with the energy conservation law requirement.