Backscattering from Two-Dimensionally Periodic Half Space: Polarization Dependence

Backscattering characteristics, concentrated on polarized aspects, are described by a theoretical model of two-dimensionally periodic medium and space-harmonic interactions are illustrated by numerical results.     

A Genetic Algorithm Approach to Optimize Parameters in Infrared Guidance System

In the infrared guidance system, the gray level threshold is key for target recognition. After thresholding, a target in the binary image is distinguished from the complex background by three recognition features. Using a genetic algorithm, this paper seeks to find the optimal parameters varied with different sub-images to compute the adaptive segmentation threshold. The experimental results reveal that the GA paradigm is an efficient and effective method of search.     

内电层分割的一般方法

提出了印制电路板(PCB)设计时内电层分割的一般性方法,并就其使用集合论的方法给予了较严格的数学证明.通过重复4个简单的步骤,这种方法对任意情形的内电层分割给与了相同的对待,简单、规范并且容易操作.应用表明,它解决了PCB设计人员在分割内电层时的困难和麻烦,并且有助于开发EDA软件自动完成分割.     

A Coordinate-Free Approach to Wave Reflection from a Uniaxially Anisotropic Medium

This paper presents a coordinate-free method of solving the problem of electromagnetic wave reflection from the surface of a uniaxially anisotropic medium. Based on the direct manipulation of vectors, dyadics, and their invariants, the method eliminates the use of coordinate systems. It facilitates solutions and provides results in a greater generality. The paper contains the following results in coordinate-free forms: a) the dispersion equations; b) me directions of field vectors; c) the Poynting vectors (ray vectors) and group velocities d) the' laws of reflection and refraction; and e) the transmition and reflection coefficients. The results are valid for the incident wave having any polarization, and the optic axis of the uniaxial medium being arbitrarily oriented with respect to the interface and the plane of incidence.     

评估通信网综合性能的一种新的方法--多级模糊树法

本文提出了一种新的模糊综合评判方法：多级模糊树法ＭＦＴ（ＭｕｌｔｉｌｅｖｅｌＦｕｚｚｙＴｒｅｅ），并利用它对通信网的综合性能进行模糊综合评判。文中首先描述了ＭＦＴ的基本思想，然后确定了影响通信网不同性能级别的因素论域及各因素的分级表，再利用统计法算出各因素的权，最后采用ＭＦＴ评估出通信网的综合性能指标。     

A General Approach to Energy Optimization of Hybrid Electric Vehicles

This paper approaches the problem of optimizing energy consumption onboard hybrid vehicles in a general way, considering the main issues to be solved in their conceptuality and, therefore, that are often abstracted from the actual structure of the particular drive train that the authors considered. The methods that were described are a harmonization of those used by the authors over the last several years; therefore, although being rather general, they are far from describing the state of the art of scientific literature on this topic. Both parallel and series structures are covered; for either structure, the effect of different functions on management strategies (e.g., pure-electric drive and plug-in recharge capabilities) are discussed. Some more details are supplied in the Case Studies section of this paper, where some of the authors' past experiences are reconsidered in terms of the general approach proposed in this paper.     

A General Approach to Sampled-Data Modeling for Power Electronic Circuits

A general sampled-data representation of the dynamics of arbitrary power electronic circuits is proposed to unify existing approaches. It leads, via compact and powerful notation, to disciplined modeling and straightforward derivation of small-signal models that describe perturbations about a nominal cyclic steady state. Its usefulness is further illustrated by considering the representation and analysis of a class of symmetries in circuit operation. The results of the application of this methodology to modeling the small-signal dynamics of a series resonant converter are described. The results correlate well with simulation results obtained on the Massachusetts Institute of Technology's Parity Simulator. What is of greater significance is the fact that the small-signal model is obtained in a completely routine way, starting from a general formulation and working down to the actual circuit; this contrasts with the circuit-specific analyses that are more typical of the power electronics literature. The automatability of this procedure is also discussed, and it is pointed out that the key ingredients for automatic generation of dynamic models from a circuit specification are now available.     

信息技术安全通用评估方法

随着信息技术的迅速发展和日益普及,信息安全显得日益突出,世界各国也越来越关注信息技术产品或系统的安全问题,对信息技术安全性进行测试、评估,成为保证信息技术产品或系统安全性的重要手段。但如何进行测评认证却是一个十分复杂的问题,国际标准化组织与国际电工委员会组织制定了信息技术安全评估通用准则,     

An Approach to Guidance Motion by Gait-Training Equipment in Semipassive Walking

Recently, population aging and declining birth rate have become very serious, and people who lack walking capability have truly increased in Japan. To address this issue, gait training has become a requirement for them. Although some training systems have been researched in the past, a training system that entails guidance of walking has not been researched well. This paper focuses on guidance of walking, and it is aimed to develop a training system that utilizes the activity and passivity of the trainee. In addition, rhythmic walking, which takes walking stability and trainee safety into account, is aimed for. In this paper, an improved electric wheelchair is used as gait-training equipment (GTE); then, the trainee is towed by the GTE, and walking is guided. In this paper, a targeted walking cycle is predefined, and the GTE must distinguish the cycle in order to guide walking. Therefore, this paper uses the center of gravity (COG) of the trainee as the index. Thus, the GTE tows the trainee when the swing leg moves more forward than the stance leg; then, rhythmic walking can be guided. In addition, this paper proposes a method to control the GTE by a proportional-differential controller based on virtual compliance that is composed of mass, spring, and damper. The gait training can be safely achieved by deciding the desired position and velocity of the GTE from the tow force through virtual compliance. In this paper, the validity of the proposed method is verified by numerical simulation and experiment. The validity of the proposed system is verified by using a four-link robot whose geometric expression is known as the trainee; then, the application of the proposed method will be extended to a human trainee by only adjusting the parameters.     

Unified Approach to Wave Diffraction by Space-Time Periodic Anisotropic Media

The diffraction properties of electromagnetic waves propagating in a planar anisotropic medium with tensor permittivity which is modulated periodically with respect to space and time are analyzed by extending the previous theory for time-invariant anisotropic dielectric gratings. The method applies to any isotropic or anisotropic medium, any polarization of the incident plane wave, and any orientation of the grating vector. The analysis is formulated in a unified matrix form so that calculations can be performed systematically. As numerical examples of the general analysis, the optical diffractions by an acoustic wave in a birefringent crystal and by a cholesteric liquid crystal are treated, where the approximate two-wave analysis is also derived and the accuracy is discussed by comparison with the rigorous analysis.     

周期性有耗介质结构的电磁散射研究

本文介绍一种新的涂层隐身方法:周期涂覆方法,它与均匀涂覆方法相比,能够在不增加散射体厚度的情况下,使用现有单层有耗材料,使目标的隐身特性得以较大改善。本文运用快速傅氏变换和迭代法对一些具体例子进行了计算,并与实验结果进行了比较。     

电磁波在周期性结构星型波导中的传输特性

提出一种新型波导结构,在二维周期性结构平板介质中引入两条线缺陷形成星型波导,在波导中加入介电常数不同的介质点阵形成缺陷,采用时域有限差分法(FDTD)对该结构的导波特性进行数值模拟。计算结果表明,该星型结构波导的透射频谱比入射波频谱的带宽更窄,说明此结构具有窄带滤波作用。当改变该星型波导中缺陷结构介电常数取值时,透射过该波导的电磁波中心频率随缺陷介质介电常数的增大而减小,呈良好的线性关系。当改变中心介质柱直径时,透射电磁波的中心频率随缺陷介质柱直径的增大而减小。这种周期性结构星型波导可作为一种窄带滤波和选频器件。     

一种通用的仿射不变特征区域提取方法

本文利用尺度-空间理论和自相关矩阵的局部形状提出了一种通用的提取仿射不变特征区域的方法.首先,在尺度-空间中对图像的归一化高斯微分求三维局部极大值获得特征点和特征尺度位置,然后在特征点的特征尺度上用自相关矩阵刻画局部的灰度变化,提取的椭圆区域即为仿射不变特征区域.在此通用方法框架下构造了Harris3D、Laplace3D、Hessian3D和Localjet43D四种仿射不变特征区域算法.实验结果表明这四种算法都具有照度、旋转和尺度不变性.用本文设计的一种仿射不变性仿真实验方法验证了算法的仿射不变性.比较四种算法发现除了Harris3D性能稍差外其他三种算法性能接近.     

A Unified Approach to Serial Search Spread-Spectrum Code Acquisition--Part I: General Theory

The purpose of this two-part paper is threefold: 1) Part I discusses the code-acquistion problem in some depth and 2) also provides a general extension to the approach of analyzing serial-search acquisition techniques via transform-domain flow graphs; 3) Part II illustrates the applicability of the proposed theoretical framework by evaluating a matchedfilter (fast-decision rate) noncoherent acquisition receiver as an example. The theory is formulated in a general manner which allows for significant freedom in the receiver modeling. The statistics of the acquisition time for the single-dwell [2], [3] andN-dwell [5] systems are shown to be special cases of this unified approach.     

基于校验矩阵构造BCM网格的一般方法

BCM是在不牺牲信道带宽的前提下，为提高数字传输系统的可靠性而使编码和调制实现最佳联合的一种有效途径，只有构造适当的BCM网格，才有可能采用Viterbi算法以较低的复杂度实现最大似然比译码。本文基于分组码的校验矩阵，提出了一种构造BCM网格的一般方法，该方法克服了以往BCM的Viterbi译码只局限在某些特殊情形的不足，对构成BCM的成分码数目，复杂性和次序未作任何限制，在理论上，可适用于任意的BCM网格译码器的构造。利用MQAM调制星座设计了多种BCM方案，并进行了计算机仿真。仿真结果表明：采用这种一般方法构造的Viterbi译码网格和以前采用特殊方法构造的网格一样，能在高斯信道中可获得最大似然比译码，在瑞利、莱斯信道中也可获得较高的译码性能。     

中等功率通用型变频器电路设计要点分析

随着变频器在现代工业中的广泛应用,变频器技术的研究也越来越受到重视。变频器电路是变频器中的重要组成部分,因此,对变频器电路的研究有着重要的意义。本文主要介绍了中等功率通用变频器电路设计三个方面的关键技术;主电路、IGBT驱动电路和控制电路。     

A General Approach for Computation and Interpretation of Dilution Curves

A short appraisal is made of computerized methods utilized in the evaluation of dilution curves. Based on requirements of experimental and clinical studies, a general on-line real-time approach is proposed that increases information retrieval from standard curves. A simple, hybrid scheme tests for exponential or other declines if desired. The point for curve extrapolation is determined by the test that also controls the character of the extrapolated curve. Information obtained from the test itself can define characteristics of the decline and thereby yield insight into the character of the system itself.