Analysis, design, and practical considerations for 500 W power factor correctors

This paper presents analysis, design, and practical considerations for 500 W boost power factor correctors (PFCs). The boost PFCs with three active soft-switching cells, which are boost, forward and flyback, and a passive soft-switching cell are first discussed. The operating principle and performance characteristics of the PFCs are then presented in detail, from which the boost with a flyback soft-switching cell and that with a passive soft-switching cell are designed and implemented. Performance comparison among these PFCs is also presented. Hardware measurements are used to verify the theoretical discussion. The presented information can provide designers a good application reference.     

面向产品开发活动的细胞交互模型研究

为实现产品开发活动交互的自主性和多样性,更好地支持产品开发过程管理与优化,在对细胞的交互机理、物质能量及信息的输入输出渠道研究的基础上,基于Petri网构建了面向产品开发的细胞交互元模型,给出了模型的定义及变迁规则.以汽车油泵单向阀测试装置开发过程为实例,验证了建模方法的有效性.     

Low observable target motion analysis using amplitude information

In conventional passive and active sonar system, target amplitude information (AI) at the output of the signal processor is used only to declare detections and provide measurements. We show that the AI can be used in passive sonar system, with or without frequency measurements, in the estimation process itself to enhance the performance in the presence of clutter where the target-originated measurements cannot be identified with certainty, i.e., for “low observable” or “dim” (low signal-to-noise ratio (SNR)) targets. A probabilistic data association (PDA) based maximum likelihood (ML) estimator for target motion analysis (TMA) that uses amplitude information is derived. A track formation algorithm and the Cramer-Rao lower bound (CRLB) in the presence of false measurements, which is met by the estimator even under low SNR conditions, are also given. The CRLB is met by the proposed estimator even at 6 dB in a cell (which corresponds to 0 dB for 1 Hz bandwidth in the case of a 0.25 Hz frequency cell) whereas the estimator without AI works only down to 9 dB. Results demonstrate improved accuracy and superior global convergence when compared with the estimator without AI. The same methodology can be used for bistatic radar     

Controlled-Quantity Concept in Small-Signal Analysis of Switching Power Cells

The notion of a controlled quantity of a switching power cell leads to a set of six (characteristic) coefficients containing all the information on the small-signal, low-frequency behavior of any linearizable cell and defining a universal linear equivalent model of the cell. The result is a dramatic simplification of the small-signal analysis and systematization of the cells. As an illustration, three sets of characteristic coefficients of a boost cell are given: operating in heavy mode and with duty ratio, operating with maximum inductor current, and operating with the period of the switching frequency as the controlled quantity.     

基于STDP奖励调节的类脑面向目标导航

动物具有优秀的空间自主定位导航能力，能够实现在无先验环境信息下的导航定位和导航决策过程。针对智能体在连续空间中面向目标导航问题，研究了一种基于生物学放电时间依赖可塑性学习规则的智能体面向目标导航算法。首先分析了动物面向目标导航决策过程中的生理学机理，在此基础上，构建了基于脉冲神经网络的位置细胞和动作细胞模型。动作细胞间权值采用横向竞争模型更新，通过环境奖励信号的更新，采用放电时间依赖可塑性学习规则对位置细胞前馈动作细胞模型的突触权重进行权值调节，利用动作细胞群的脉冲放电现象表征智能体运动方向和速度。最后，对所提算法进行了仿真实验验证。仿真结果表明，所提出的类脑面向目标导航算法能够在单障碍环境中实现30 ms左右的规划速度，相比传统强化学习Q学习方法平均路径规划长度缩短了15.9%。     

一类二维非结构网格DSMC方法的实现策略及其应用

研究了一类二维非结构网格DSMC方法的实现策略。在数据结构方面，设计了局部化的数据组织方式，节约了内存与计算时间。发展了一种跟踪模拟分子迁移的算法，该算法仅需少量的逻辑运算与代数运算，不仅可以快速跟踪模拟分子在网格之间的迁移，而且可以准确判别分子与物面是否相互作用，搜索过程中的附带信息给出了分子与物面碰撞的精确时间与位置，避免了重新计算。引入碰撞距离的思想，既减少存储又保证正确的模拟结果。在程序编制过程中，我们充分展现了Fortran90高级语言的主要特性，引入动态数组、指针、链表以及派生类型数据，编制了计算程序。最后对过渡流域高超声绕流进行了数值试验。     

Pattern Recognition with Time Interval Modulation Information Coding

The theoretical channel capacity of a switching device is far in excess of that utilized in a binary-coded system. One of the motivations of our research has been the attempt to increase the channel capacity by representing information by the interval between pulses instead of the presence or absence of pulses. A second motivation is the desire to find a practical use for microelectronic devices now under development which may encompass a billion gates in a cubic inch. The third motivation is the similarity between the nervous system and a Time Interval Modulation Information Coding system (TIMIC). In our initial studies we have utilized an operational element, called "sumister," which is essentially a model of an artificial neuron interpreted as a decision-making threshold device with the ability of temporal and spacial summation and short-term memory. Five basic component networks have been designed, the ON cell, the OFF cell, a conjunctive network, an object-detection network, and an autocorrelation network. These are combined into moving-object detection networks and a metaphase-chromosome detection network.     

SERF陀螺仪研究进展及关键技术

SERF(Spin Exchange Relaxation Free)陀螺仪利用电子自旋在惯性空间的定轴性敏感载体转动信息,具有超高精度、小体积的特点,已成为国内外惯性技术领域的研究热点之一.本文介绍了SERF陀螺仅的基本原理,回顾了SERF陀螺仪的国内外发展历程,指出SERF陀螺仪发展需要解决原子气室抗弛豫、核自旋磁场补偿闭环和高精度的信号检测三个关键技术,并展望了SERF陀螺仪在未来潜在的应用前景.     

未来航空电子信息技术发展需求分析

从多平台OODA的任务运行出发,分析了未来航空电子信息技术主要面向多平台信息的高效组织与管理,其发展趋势是充分利用人工智能技术,将战场数据转换为信息,将信息演进为知识,从而形成具有反馈机制的环路来引导多平台航空电子体系更快的获取信息.本文分别从多域多维信息的高效获取,多异构平台分布式信息处理,高效智能的信息组织,清晰准...     

惯性卫星紧组合导航系统仿真分析

针对SINS/Satellites进行松组合的不足,直接利用卫星信号接收机原始测量信息(伪距、伪距率),实现紧组合,来提高组合导航系统的精度和抗干扰性。文中详细推导了紧组合导航系统的伪距、伪距率误差模型,以伪距、伪距率差作为输入进行反馈,不仅当可见星数目小于4颗的时候,可以进行反馈,保证了一定的导航精度,而且可以用INS提供导航信息辅助接收机快速捕获卫星信号,这就提高了组合导航系统的容错能力。设计了SINS卫星紧组合导航系统的Kalman滤波器,并进行仿真验证,结果表明,SINS卫星紧组合较松组合有明显优势。     

自适应笛卡尔网格Ghost Cell方法研究

在笛卡尔网格中,利用Ghost Cell方法处理浸入边界,模拟二维无粘可压缩流。针对静止物体,比较了各种不同的Ghost Cell边界条件下的熵误差,总压误差,以及阻力系数。此外为提高激波分辨率,将Ghost Cell方法与基于叉树结构的自适应笛卡尔网格算法相结合,数值结果显示本文的方法是切实可行的。     

论IT技术下的会计信息处理模式重构

会计信息供给的监管和规范不能单纯地拘泥于制度完善和道德规范,而更应该结合系统论,在会计信息的确认、计量、处理、披露等方面,充分利用现代IT技术,建立基于事项理论、事件驱动和XBRL技术的会计信息供给模式.从而减少会计信息供给者参与信息编制的环节和程度,在一定程度上控制供给者的信息操纵空间,解决会计信息不对称的问题.     

基于多源信息融合分析的 导弹贮存寿命评估方法

对于长期贮存的导弹,通常能获取的贮存信息仅为贮存期内的年检数据与少量的例行试验数据,贮存信息相对匮乏,对导弹贮存寿命与可靠性评估工作非常不利。为解决这种工程实践中存在的实际问题,发展了一种采用工程加速贮存与地面鉴定试验相结合的加速贮存信息获取方法,获取典型单机与简单系统贮存信息。将典型单机与非金属材料加速贮存信息与地面鉴定试验信息、现场贮存信息、贮存环境数据以及例行试验信息等数据信息融合处理,建立基于多源信息融合的贮存信息数据库。在此基础上,建立基于现场贮存信息与加速试验信息融合分析的导弹贮存寿命与可靠性评估方法,并给出导弹在现有贮存时间下,继续贮存一定年限的可靠度。     

基于同步双口SRAM的原子磁强计磁共振相位提取系统设计

针对原子磁强计磁共振激励信号相位提取过程中,数据量大、实时性强、同步要求高等特点,设计了一种基于同步双口SRAM的磁共振相位信息提取系统。首先利用FPGA控制高速同步采样AD进行数据转换;然后经同步双口SRAM实现数据的高速缓存和同步读写;最后由DSP经外部中断触发定时读取缓存的数据,并进行数字锁相处理,提取相位信息。实验结果表明:该系统对频率为35~350kHz之间的正弦信号相位提取稳定度达到0.006°,满足原子磁强计静态噪声小于20pT的应用要求。     

Voltage-based maximum power point tracking control of PV system

Photovoltaic (PV) generators exhibit nonlinear v-i characteristics and maximum power (MP) points that vary with solar insulation. An intermediate converter can therefore increase efficiency by matching the PV system to the load and by operating the solar cell arrays (SCAs) at their maximum power point. An MP point tracking algorithm is developed using only SCA voltage information thus leading to current sensorless tracking control. The inadequacy of a boost converter for array voltage based MP point control is experimentally verified and an improved converter system is proposed. The proposed converter system results in low ripple content, which improves the array performance and hence a lower value of capacitance is sufficient on the solar array side. Simplified mathematical expressions for a PV source are derived. A signal flow graph is employed for modeling the converter system. Current sensorless peak power tracking effectiveness is demonstrated through simulation results. Experimental results are presented to validate the proposed method     

机载嵌入式计算机通用操作系统故障管理软件设计

提出了一种对机载嵌入式计算机中常见操作系统故障的监控和记录方法,结合记录操作系统和处理器的状态信息,同时考虑到在多种操作系统、处理器上的适应性,设计一套具有操作系统故障监控和状态信息记录功能的通用操作系统故障管理软件,提高机载嵌入式计算机的可维护性。     

机载嵌入式计算机通用操作系统故障管理软件设计

提出了一种对机载嵌入式计算机中常见操作系统故障的监控和记录方法,结合记录操作系统和处理 器的状态信息,同时考虑到在多种操作系统、处理器上的适应性,设计一套具有操作系统故障监控和状态信息 记录功能的通用操作系统故障管理软件,提高机载嵌入式计算机的可维护性。     

The Information Content of Synthetic Aperture Radar Images of Terrain

A statistical model is developed that portrays an imaging radar as a noisy communication channel with multiplicative noise, and the model is used to evaluate the average amount of information that can be extracted about a target from its radar image. The average information content is also used to define a measure of radiometric resolution for radar images. It is shown that the information content and the resolution capabilities of an imaging radar reach a limit beyond which an increase in scene dynamic range does not improve the information content or the resolution. This limitation results from the multiplicative nature of the noise introduced in the imaging process.     

基于CSDB的装甲装备IETM技术研究

引入S1000D国际规范制作IETM,体现了装备全寿命信息管理(CALS)的思想。CSDB是S1000D规范的核心概念,所存储的技术信息能实现"一次生成、多次使用"的目标,存储有DM、PM等信息对象,负责信息对象的存储和管理工作。研究了基于CSDB的装备IETM技术,对加快装甲装备保障信息化建设的作用和意义重大。     

Event-triggered cooperative target tracking in wireless sensor networks

Since the issues of low communication bandwidth supply and limited battery capacity are very crucial for wireless sensor networks, this paper focuses on the problem of event-triggered cooperative target tracking based on set-membership information filtering. We study some fundamental properties of the set-membership information filter with multiple sensor measure-ments. First, a sufficient condition is derived for the set-membership information filter, under which the boundedness of the outer ellipsoidal approximation set of the estimation means is guaranteed. Second, the equivalence property between the parallel and sequential versions of the set-membership information filter is presented. Finally, the results are applied to a 1D event-triggered target tracking scenario in which the negative information is exploited in the sense that the measurements that do not satisfy the triggering conditions are modelled as set-membership mea-surements. The tracking performance of the proposed method is validated with extensive Monte Carlo simulations.