磁通门铁芯涡流效应磁场计算与HSPICE仿真

在交变磁场下,针对铁磁材料中涡流效应对磁滞回线的影响在传统分析计算中存在的难题,提出一种基于HSPICE的磁通门铁芯涡流磁场计算和仿真方法.磁通门铁芯用考虑磁滞现象的Jiles动态模型描述,运用欧姆定律和毕奥-萨伐尔定律得到涡流产生的寄生磁场,再将寄生磁场与激励磁场叠加代入Jiles动态模型,即得到涡流对磁滞回线影响的数学模型.最后,利用HSPICE进行仿真验证,结果表明:在0.5 Hz、50 Hz、200 Hz和500 Hz 4种不同频率电压源激励下得到的铁芯磁滞回线波形,与实验结果拟合较好.     

计算机数值积分技术在磁滞回线测量中的应用

基于传统瓦特计和计算机数值积分技术制作了一个超导材料磁滞回线测量设备,介绍了测试原理和制作过程,完成了Bi2223/Ag带材磁滞回线测试,表明采用传统瓦特计法和计算机数值积分测试超导材料磁滞回线的方法简单实用。     

铁磁材料居里温度测量的BP神经网络分析

利用BP神经网络对铁磁材料居里温度实验数据进行了拟合与处理,结果显示该方法处理结果精度高,拟合效果好.     

基于逆磁致伸缩效应的残余应力检测方法

根据铁磁材料的逆磁致伸缩效应，研究了基于这一效应的磁各向异性四极探头型传感器检测铁磁材料残余应力的方法，并进行了20^＃钢压缩试件的典型实验，实验证明了这种方法是可行的。     

基于巴克豪森效应的钢板内部缺陷检测方法

阐述了巴克豪森信号用于缺陷检测的原理.根据趋肤效应,提出通过改变交变磁场的频率来调节磁场的穿透深度,实现对铁磁性材料逐层扫描,来完成铁磁材料内部较深缺陷的检测.同时提出用小波多分辨率分析方法进行信号处理.对 A3 钢板的系列实验结果表明:该方法可实现对钢板内空气隙缺陷的检测和定位;用小波多分辨率分析方法处理信号的效果要...     

基于LabVIEW的铁磁材料漏磁检测技术研究

为实现铁磁材料缺陷的无损检测,提高材料的可靠性,根据其磁学性质,搭建了漏磁场的测量平台,在LabVIEW平台下通过控制步进电机和驱动数据采集卡实现霍尔传感器对漏磁信号的实时检测,同时对漏磁数据进行实时显示、处理和保存,并通过小波变换和微分消除漏磁数据噪声、直观显示缺陷信息.实验表明:基于LabVIEW的漏磁检测技术可以实现缺陷漏磁数据的采集、实时显示和消噪处理,实现对铁磁材料缺陷的精确检测.     

光学电流传感器灵敏度的提高

利用法拉第磁光效应可构成光学电流传感器（ＯＣＴ）。选择高Ｖｅｒｄｅｔ常数的传感材料，增加光束环绕电流的环路数是提高ＣＣＴ灵敏度的主要方法。采用比较测量法来消除温度对高Ｖｅｒｄｅｔ常数铁磁材料的影响，介绍了反向双环路结构传感头，并对其进行了实验测试。     

软磁环磁滞回线测量中的定标

介绍了磁滞回线测量中的定标方法,与标样参数进行对比,分析了误差来源。给出了磁滞回线测量原理,并对传统的测量电路进行了改进。     

图解铁磁交流稳压器

交流稳压器通常是利用铁磁非线性特性构成,属于铁磁稳压器,它是由铁磁饱和元件再加谐振电容构成的稳压器。1、铁磁饱和现象一个线圈通过电流时,线圈中便有磁场产生,描述这个磁场有两个物理量,一个是磁场强度,用H来表示,它与线圈的圈数和流过线圈的电流强度的乘积(又称安匝数)有关;另一个是磁感应强度(又称磁通密度),用B来表示,B的大少除与安匝数有关外,还与线圈中的介质有关。如果介质是空气,那么H和B数值相等,如果介质是铁磁材料时,同一线圈流过同样的电流     

电力变压器铁心剩磁检测及消除

从铁磁材料固有的磁滞现象角度分析变压器铁心产生剩磁的原因、原理,以及剩磁对变压器和电力系统运行可能带来的负面影响。提出变压器有无剩磁的检测方法,并探讨如何消除剩磁。     

Dissipativity of a nonresonant pendulum with ferromagnetic friction

The dissipativity of nonresonant pendulums with ferromagnetic friction is proved for sufficiently wide hysteresis loops, and a simple closed-form estimate is given. The absence of subharmonics of large amplitudes is proved for an arbitrarily narrow loop.     

Optimal loop storage allocation for argument-fetching dataflow machines

In this paper, we consider the optimal loop scheduling and minimum storage allocation problems based on the argument-fetching dataflow architecture model. Under the argument-fetching model, the result generated by a node is stored in a unique location which is addressable by its successors. The main contribution of this paper includes: for loops containing no loop-carried dependences, we prove that the problem of allocating minimum storage required to support rate-optimal loop scheduling can be solved in polynomial time. The polynomial time algorithm is based on the fact that the constraint matrix in the formulation is totally unimodular. Since the instruction processing unit of an argument-fetching dataflow architecture is very much like a conventional processor architecture without a program counter, the solution of the optimal loop storage allocation problem for the former will also be useful for the latter.     

一种基于InSb磁敏电阻器的接近开关

介绍了锑化铟(InSb)磁阻式接近开关的工作原理,设计了信号处理电路,并对其动态性能进行了测试.实验结果表明:径向间距为4 mm时,接近开关动作距离大于8 mm,回差距离小于0.06 mm,重复定位精度优于0.04mm,可适用于工作频率0～5 kHz范围内的铁磁性物质检测.该接近开关灵敏度高,开关动态特性较好,且结构简...     

A novel reluctance actuator employing an embedded ferromagnetic foil

In this paper we present a reluctance actuator which contains laser cut ferromagnetic structures for flux guidance made of Mumetal foil. By means of analytic calculations and numeric simulations it is shown that much higher magnetic forces are achievable by using the Mumetal foil compared to electroplated ferromagnetic alloys like nickel–iron. Furthermore, the processing of such foils and the integration of foil structures into the actuator are described.     

一种面向3D场景的实时自动路径搜索方法

提出一种应用于实时渲染3D场景中的路径搜索实现方法，该方法以3D虚拟场景模型中的多边形为基本对象，根据多边形的拓扑关系，将虚拟场景抽象成连通图形式的中间结果。在这个中间结果中，根据场景地形的通用性属性，利用启发式搜索进行路径搜索，并在路径搜索中有效的任务调度机制优化渲染循环中的路径搜索性能。与传统方法比较，该方法不需要在场景中额外增加人工标记，具有良好计算通用性与性能。     

动态可重构环境下循环计算的位宽优化

动态可重构技术允许根据计算的运行时情况对硬件处理单元进行重构，使其位宽适合计算的需要。而且，对代表计算密集型任务的循环计算进行位宽的动态优化可达到提高处理性能，减少所消耗的芯片资源和功耗的目的。本文构造了一个处理框架对循环计算的位宽进行动态的优化，包括对循环计算的位宽变化情况进行理论和运行时的分析，以及构造1个位宽管理算法选择重构的时机和对配置文件进行调度。通过对实验结果的分析，证明了我们的方案具有较好的性能。     

Influence maximization with limit cost in social network

Social networking service (SNS) applications are changing the way information spreads in online communities. As real social relationships are projected into SNS applications, word of mouth has been an important factor in the information spreading processes of those applications. By assuming each user needs a cost to accept some specific information, this paper studies the initial "seed user" selection strategy to maximize information spreading in a social network with a cost budget. The main contributions of this paper are: 1) proposing a graphic SEIR model (gSEIR) by extending the epidemic compartmental model to simulate the dynamic information spreading process between individuals in the social network; 2) proposing a formal definition for the influence maximization problem with limit cost (IMLC) in social networks, and proving that this problem can be transformed to the weighted set-cover problem (WSCP) and thus is NP-Complete; 3) providing four different greedy algorithms to solve the IMLC problem; 4) proposing a heuristic algorithm based on the method of Lagrange multipliers (HILR) for the same problem; 5) providing two parts of experiments to test the proposed models and algorithms in this paper. In the first part, we verify that gSEIR can generate similar macro-behavior as an SIR model for the information spreading process in an online community by combining the micro-behaviors of all the users in that community, and that gSEIR can also simulate the dynamic change process of the statuses of all the individuals in the corresponding social networks during the information spreading process. In the second part, by applying the simulation result from gSEIR as the prediction of information spreading in the given social network, we test the effectiveness and efficiency of all provided algorithms to solve the influence maximization problem with cost limit. The result show that the heuristic algorithm HILR is the best for the IMLC problem.     

Loop Staggering,Loop Compacting:Restructuring Techniques for Thrashing Problem

Parallel loops account for the greatest amount of parallelism in numerical programs.Executing nested loops in parallel wit low run-time overhead is thus very important for achieving high performance in paralleo processing systems.However,in parallel processing systems with caches of local memories in memory hierarchies,“thrashing problemmay” may arise when data move back and forth frequently between the caches or local memories in different processors.The techniques associated with parallel compiler to solve the problem are not completely developed.In this paper,we present two restructuring techniques called loopg staggering,loop staggering and compacting,with which we can not only eliminate the cache or local memory thrashing phemomena significantly,but also exploit the potential parallelism existing in outer serial loop.Loop staggering benefits the dynamic loop scheduling strategies,whereas loop staggering and compacting is good for static loop scheduling strategies,Our method especially benefits parallel programs,in which a parallel loop is enclosed by a serial loop and array elements are repeatedly used in the different iterations of the parallel loop.