A neural networks based model of inverse hysteresis

A novel and simple approach based on transformation using neural networks is proposed in this paper to model the inverse behavior of hysteresis. In this approach, a continuous transformation is used to construct an elementary inverse hysteresis operator (EIHO), which can extract the change tendency of inverse hysteresis. Then based on the EIHO, an expanded input space is constructed to transform the multi-valued mapping of inverse hysteresis into a one-to-one mapping. Based on the constructed expanded input space, a neural network is employed to approximate the inverse hysteresis. Both experiment and simulation are implemented to validate the effectiveness of the proposed approach. These results indicate that the proposed approach has derived satisfactory modeling performance.     

LiFePO4纳米管的制备与表征

采用溶胶凝胶法在氧化铝模板中成功的制备了LiFePO4一维纳米管阵列．扫描电子显微镜和透射电子显微镜表征结果表明所制备的LiFePO4纳米管具有单分散性,互相平行,高度有序。综合选区电子衍射、X射线衍射以及X光线能谱表征结果,所制备的LiFePO4纳米管为单一的橄榄石型结构．这种在室温和温和条件下合成的一维LiFePO4纳米管,可以做为新型的锂离子电池正极材料．     

Hysteresis modeling of synchronous reluctance motor considering PWM input voltage

This paper deals with the hysteresis characteristics analysis in PWM fed synchronous reluctance motor (SynRM) using a coupled finite element method (FEM) and Preisach's modeling, which is presented to analyze the characteristics under the effect of saturation and hysteresis loss. With regard to the PWM characteristics, a vector control inverter is combined with an analysis tool. Also, a moving mesh technique is used with regard to rotation due to velocity. The focus of this paper is the applied method of Preisach modeling for rotating machines and the characteristics analysis of a SynRM using the proposed method of analysis. For the propriety of proposed method of analysis, TMS320C31 DSP-installed experimental devices are used. And then, computer simulation and experimental result for the i–λ loci, speed, current response, show the propriety of the proposed method. The characteristic analysis is performed in relation to the maximum efficiency condition for a SynRM in simulation and experiment.     

Efficient vector hysteresis modeling using rotationally coupled step functions

Vector hysteresis models are usually used as sub-modules of field computation software tools. When dealing with a massive field computation problem, computational efficiency and practicality of such models become crucial. In this paper, generalization of a recently proposed computationally efficient vector hysteresis model based upon interacting step functions is presented. More specifically, the model is generalized to cover vector hysteresis modeling of both isotropic and anisotropic magnetic media. Model configuration details as well as experimental testing and simulation results are given in the paper.     

基于UML的战时装备维修保障行动建模研究

针对战时装备维修保障行动建模仿真与优化分析对军事概念模型的需求,提出了一种面向保障力量运用的战时装备维修保障行动概念建模方法,分别从保障指挥行动和保障分队行动两个方面,运用统一建模语言,将组织结构静态建模与行为过程动态建模相结合,构建了战时装备维修保障行动概念模型体系,为下一步开展仿真实验分析奠定了军事概念模型基础。     

State of charge estimation of Li-ion batteries in an electric vehicle based on a radial-basis-function neural network

The on-line estimation of the state of charge(SOC) of the batteries is important for the reliable running of the pure electric vehicle in practice.Because a nonlinear feature exists in the batteries and the radial-basis-function neural network(RBF NN) has good characteristics to solve the nonlinear problem,a practical method for the SOC estimation of batteries based on the RBF NN with a small number of input variables and a simplified structure is proposed.Firstly,in this paper,the model of on-line SOC estimation with the RBF NN is set.Secondly,four important factors for estimating the SOC are confirmed based on the contribution analysis method,which simplifies the input variables of the RBF NN and enhances the real-time performance of estimation.Finally,the pure electric buses with LiFePO 4 Li-ion batteries running during the period of the 2010 Shanghai World Expo are considered as the experimental object.The performance of the SOC estimation is validated and evaluated by the battery data from the electric vehicle.     

基于单粒子模型与偏微分方程的锂离子电池建模与故障监测

锂离子电池内部结构是一种复杂的分布参数系统, 如果为了降低计算难度而使用常微分方程描述锂离子电池, 可能会引入系统误差, 降低系统模型的可信度, 需要使用偏微分方程建立分布参数系统的精确模型. 本文提出了一种基于单粒子模型和抛物型偏微分方程的锂离子电池系统建模与故障监测系统设计方法, 当锂离子浓度实测值与理想值的残差大于预设门槛时判定分布参数系统处于故障状态. 通过一个仿真实例进行了锂离子电池系统建模和故障诊断实验, 实验证明基于单粒子模型和偏微分方程的锂离子电池故障监测系统具有更高的精确度和可信度.     

Transverse hysteretic damping characteristics of a serpentine belt: Modeling and experimental investigation

In this paper, the transverse dynamic hysteretic damping characteristics (HDC) of a serpentine belt are investigated. The variable stiffness and variable damping model (VSDM) constituted of a variable-stiffness spring and a variable-damping damper is developed to estimate the HDC of the belt. A test rig is designed to test the force–displacement hysteresis damping curve and resonance frequencies of serpentine belts with different lengths under diverse loading conditions. The force–displacement hysteresis damping curve getting from the experiment is then used to determine the transverse stiffness and damping coefficients needed for the VSDM. The experiment particularly shows that the orientation of the hysteresis curve swings left and right around each natural frequency as it is a symmetrical point. This interesting phenomenon is explicated in detail with the loss angle which is calculated by two methods. Moreover, two sub-analytical models included in the VSDM are proposed to model the dependence of transverse dynamic stiffness and damping coefficient of a belt on belt length, pretension and excitation frequency. A comparison of the hysteresis curves obtained from the VSDM and experiment indicates that they are in good agreement.     

基于薄层单元与弹簧单元的滚动直线导轨副动力学建模

针对某大型光机装置中使用的LM型直线导轨-滑块的结合面,采用薄层单元与弹簧单元模拟其接触面,建立了大行程传输结构模拟件的有限元模型。通过模型修正方法,根据模态试验结果对薄层单元弹性模量以及弹簧刚度进行了识别。模型修正后,结构前三阶模态频率计算结果与试验结果最大差别为2.23%,地脉动载荷下各测点位移响应计算结果与试验结果最大差别为7.61%。计算结果与试验结果具有较好的一致性,验证了模型的有效性。     

纳米颗粒的表面效应和电极颗粒间挤压作用对锂离子电池电压迟滞的影响

硅作为锂离子电池电极材料之一,其应力效应尤为突出,进而将影响电池性能.本文建立了电化学反应-扩散-应力全耦合模型,并研究了恒压充放电条件下扩散诱导应力、表面效应和颗粒间挤压作用对电压迟滞的影响.结果发现,应力及其导致的电压迟滞程度与颗粒尺寸相关.在大颗粒(颗粒半径r 100 nm)中,扩散诱导应力是导致电势迟滞效应的主要因素,这将导致电池能量耗散.对于纳米级小颗粒(r 100 nm)而言,表面效应占据主导,表面效应虽然能缓解电压迟滞,同时却会使驱动电化学反应部分的过电势回线下移,造成锂化容量衰减.本文综合考虑了扩散诱导应力和表面效应,得出:半径为10 nm的颗粒将会使电极具备较好的综合性能.此外,对于硅电极而言,颗粒间挤压作用会使应力回线向压应力状态演化,进而导致锂化容量的衰减.计算结果表明,在电极设计中,对孔隙率设定下限值有助于提升电极性能.     

基于LTC6803和NRF24L01的动力电池检测系统

为了满足磷酸铁锂动力电池电压、温度参数采集实时性和准确性的要求以及摆脱检测系统的线束,设计了一种基于LTC6803和NRF24L01的动力电池检测系统并进行了实验测试。该系统主要由数据发送端和数据接收端两部分组成,数据发送端采用LTC6803电池监测芯片和数字化温度传感器DS18b20实现对动力电池电压、温度的精确检测,数据接收端利用上位机软件对数据集中存储和管理,通过NRF24L01射频模块完成数据发送端和接收端的无线通讯。实验结果表明：该检测系统具有性能可靠、使用方便、测量精度高等优点,完全满足工业现场的使用要求,具有较好的实用效果。     

3维电介质击穿模型在雷电防护系统评估试验中的应用

 采用荷电圆盘雷云解析模型作激励源,利用电介质击穿模型进行了地闪先导放电高分辨力3维数值模拟,得到了50 m分辨力的地闪放电图样与先导近地500 m时的地面电场分布（峰值-164.9 kV·m_-1）,结果与实际观测值相符。模拟中通过高维样条插值实现了计算空间与评估区域的分辨力转换（50 m到1 m）,构建评估模型,可以进行雷电防护系统的数值评估试验。用该方案对一种雷电防护系统概念模型进行了试验,结果显示：系统10 m高、-1.5 MV激励的条件下,5 m高处的雷击概率以系统为中心随距离增加而增大,系统投影区域雷击概率为0;由于先导激励地面电场的非对称性,保护区范围各向分布极不均匀。通过此方案可以得到系统作用下精细的雷击概率分布,适用于雷电防护系统效能评估。     

Design and multistability analysis of five-value memristor-based chaotic system with hidden attractors

A five-value memristor model is proposed, it is proved that the model has a typical hysteresis loop by analyzing the relationship between voltage and current. Then, based on the classical Liu–Chen system, a new memristor-based four-dimensional(4D) chaotic system is designed by using the five-value memristor. The trajectory phase diagram, Poincare mapping, bifurcation diagram, and Lyapunov exponent spectrum are drawn by numerical simulation. It is found that, in addition to the general chaos characteristics, the system has some special phenomena, such as hidden homogenous multistabilities, hidden heterogeneous multistabilities, and hidden super-multistabilities. Finally, according to the dimensionless equation of the system, the circuit model of the system is built and simulated. The results are consistent with the numerical simulation results, which proves the physical realizability of the five-value memristor-based chaotic system proposed in this paper.     

Interpreting a period-adding bifurcation scenario in neural bursting patterns using border-collision bifurcation in a discontinuous map of a slow control variable

<正>To further identify the dynamics of the period-adding bifurcation scenarios observed in both biological experiment and simulations with the differential Chay model,this paper fits a discontinuous map of a slow control variable of the Chay model based on simulation results.The procedure of period adding bifurcation scenario from period k to period k + 1 bursting(k = 1,2,3,4) involved in the period-adding cascades and the stochastic effect of noise near each bifurcation point is also reproduced in the discontinuous map.Moreover,dynamics of the border-collision bifurcation are identified in the discontinuous map,which is employed to understand the experimentally observed period increment sequence.The simple discontinuous map is of practical importance in the modeling of collective behaviours of neural populations like synchronization in large neural circuits.     

夹断开关对“荧光-1”实验装置电流特性的影响

主要探讨了夹断开关对“荧光-1”实验装置输出电流特性的影响,利用Pspice软件对其在装置中起到的作用进行功能建模并分析其参数影响,同时开展初步调试实验并分析多组夹断开关导通性能及其同步性对负载电流的影响。仿真与实验结果表明:夹断开关可有效改善负载电流脉宽,可使脉宽从原有3 μs展宽至100 μs,其导通电阻与电感参数均能明显影响电流幅值与脉宽。由实验波形结合仿真可知,夹断开关实际导通电阻约4 mΩ, 两支路耦合电感分别约为60,125 nH,调试结果验证了夹断开关功能建模的正确性及其对脉宽展宽的有效性。     

Micromagnetic modeling studies on the effects of stress on magnetization reversal and dynamic hysteresis

The complex behaviors of magnetic materials subjected to magneto-electro-mechanical coupled fields call for a better understanding of the mechanism of multi-fields coupling. In this paper, micromagnetic modeling is carried out to study the effect of stress on hysteresis loops and dynamic magnetization reversal. The time-dependent Landau–Lifshitz–Gilbert equation which governs the evolution of magnetization is solved using the fast Fourier transform technique in reciprocal space. The simulation results show that the stress changes the distribution of easy directions and, therefore, leads to the change of magnetic properties. Moreover, the positive product of the stress and saturation magnetostriction coefficients increases the coercivity, hence, increases the area enclosed by the hysteresis loop. A stress-induced magnetization reversal is investigated.     

雷达天线控制系统频域辨识与仿真方法研究

雷达天线控制系统仿真是雷达系统目标跟踪动态仿真中一个重要环节。为解决雷达天线控制系统仿真中滞后误差大、动态效果差等问题,依据某雷达天线控制系统性能实际测试结果,以典型系统模型作为研究对象,利用频域最小二乘法完成模型参数辨识,建立系统模型,并对辨识模型进行验证。在此基础上,采用基于时域的增广矩阵法对系统进行了数字快速仿真分析。结果表明,辨识模型满足精度,且增广矩阵法能够有效快速地完成系统数字仿真,对天线控制系统建模以及快速动态仿真研究具有一定的参考价值。     

新型可燃性气体报警仪的研制

介绍新型可燃性气体报警仪的设计,可用于对丙烷、丁烷、氢气及其他可燃性气体的检测,用于检测可燃气体爆炸性;采用C8051F020单片机,通过2M007型电阻式气敏传感器采集信号,经过放大电路放大,传入单片机,进行模数转换,采用算术平均滤波对数据过滤,再通过一系列的数据处理,显示可燃性气体浓度,通讯方式采用以sim300通讯模块的GPRS通讯的新型可燃性气体报警系统;软件设计采用C语言编程,灵活方便、具有强大的移植性;如空气中可燃性气体浓度超标,开始报警,显示屏上显示出大于阀值的可燃性气体浓度,且通过无线通讯使手机也正常收到了报警短信;该系统功能齐全,操作简便,具有很高的应用价值。