Correction to effective index method for rectangular dielectricwaveguides

A new method for obtaining the propagation characteristics of dielectric waveguides is presented. The method is based on a linear combination of three approximations. A comparison with a rigorous analytical method shows that the method presented is very accurate, even in the cutoff region. The method is easy to implement and requires minimal computational effort     

微脉冲激光雷达探测大气气溶胶定标反演新方法

利用一种新的自适应定标反演方法在有效探测高度内确定标定值,反演微脉冲激光雷达(MPL)回波信号,并同另外一台激光雷达系统在相同时间、相同地点的探测结果进行了对比。对比结果显示利用该方法得到的结果能够同大气实际情况吻合地较好。应用该算法对连续12h的观测(共25组)数据进行批处理,结果正确反映了当时的天气状况。这说明该算法应用于MPL信号处理时具有很好的稳定性。     

一种新的激光扫描仪多回波处理电路设计

针对目前激光扫描仪多回波处理所用高采样率A/D采样电路的设计难度大、成本高的问题,提出一种新的多回波处理电路实现方法。首先简述了典型A/D采样电路的一般设计方法。其次提出了一种主要由高速比较器、时间延迟电路、脉冲产生电路、脉宽测量电路、加法电路以及一个现场可编程门阵列(FPGA)共同组成的新的多回波处理方法,并对重要模块的设计进行了阐述。最后通过实验验证了该电路可有效处理双脉冲回波。该电路设计成本较低,相对A/D采样电路设计难度较小。     

Design of low-delay FIR QMF banks using the Lagrange-multiplierapproach

A new approach for the design of two-channel perfect reconstruction FIR filter banks with short reconstruction delays is presented. A low-order filter is first designed and the objective function of the filter bank is formulated as a quadratic programming problem with linear constraints. The Lagrange-multiplier method is then used to design a higher-order filter. The method is simple, efficient, and flexible and leads to a closed-form solution. A design example is included to illustrate the advantages of the method     

New method of resistance measurement

A new method of resistance measurement is reported. A transistor-resistor negative-resistance device has been used for resistance measurements in the range 103?107 ?, with an accuracy within ± 1%. The performance of this new method is compared the with conventional 4-point voltmeter-ammeter method.     

A full-wave analysis method for open microstrip structures

A method for analyzing characterisitcs of open microstrip disk structures is presented. The method is based on the spectral domain immittance matrix approach, and all the wave phenomena associated with the structures are incorporated. The method provides a number of unique and convenient features both in analytical and numerical phases. A numerical example illustrating the usefulness of the method is included. Some numerical results are compared with experimental data.     

纵向应力法制作双波长布喇格光栅

介绍了一种用一个均匀相位模板制作双波长布喇格光栅的方法;对这种方法制作的双波长布喇格光栅进行了理论分析,用矩阵分析法,对其进行了数值模拟.采用了移动曝光技术,通过调节所加应力的大小、光栅长度及曝光次数可以控制两个布喇格波长的间隔和反射率;写制了一个双波长光栅,两个透射峰均为19.5 dB,两个布喇格波长的间隔为0.78 nm.     

A NEW METHOD OF DECONVOLUTION IN THE FREQUENCY DOMAIN

A new deconvolution method has been presented in this paper. Like conventional Discrete Fourier Transform(DFT) method, it is also a frequency domain method. Since there are only DFT, IDFT and multiplication calculations in the new method, the singular problem appeared in the conventional DFT method can be avoid, and the deconvolution problem can always be solved with the new method. The relationship between the presented method and conventional DFT method is discussed. A numerical example is also presented to illustrate the new method.     

基于相似性的剩余寿命预测：鲁棒性与不确定性研究

基于相似性的剩余寿命预测方法是近年来兴起的一类部件寿命预测方法。关于该方法预测结果的鲁棒性及不确定性研究尚未见报道,然而上述性质对于广泛应用该方法具有重要意义。首先,介绍了基于相似性的剩余寿命预测方法的主要思想,并介绍了一种基于相似性的剩余寿命预测方法（简称方法A）,提出一种基于历史样本估计来预测不确定性的方法;而后,基于一个广泛应用的随机衰退模型,在比较方法A的预测结果与某基于时间序列预测的剩余寿命预测方法结果的过程中,探究了方法A预测结果的鲁棒性;最后,基于同样的数据,运用所建议的方法,考察了方法A预测结果的不确定性。     

电磁问题的改进型矩量法

本文提出了一种新型的矩量法求解技术－改进型矩量法。在对电磁问题的数值分析中，这一方法提供了一个有别于矩量法的新思路，也提供了一个减少所使用计算机内存和缩短计算时间的新途径，用这一理论方法计算了若干天线实例。其计算结果与已知公开发表的结果相比较，或与所加工硬件的实测结果相比较，一致性良好。     

Model-Based Satellite Image Fusion

A method is proposed for pixel-level satellite image fusion derived directly from a model of the imaging sensor. By design, the proposed method is spectrally consistent. It is argued that the proposed method needs regularization, as is the case for any method for this problem. A framework for pixel neighborhood regularization is presented. This framework enables the formulation of the regularization in a way that corresponds well with our prior assumptions of the image data. The proposed method is validated and compared with other approaches on several data sets. Lastly, the intensity-hue-saturation method is revisited in order to gain additional insight of what implications the spectral consistency has for an image fusion method.     

Determination of coupling coefficient of DFB lasers by a newly proposed method

A new method of estimating the coupling coefficient of DFB lasers is proposed. A sub/main-mode spectral intensity ratio below the threshold current is employed in this method, instead of the stop-bandwidth used in the conventional method. It is demonstrated both theoretically and experimentally that the new method is capable of more accurate determination of the coupling coefficient of DFB lasers with phase-shifted corrugations.     

Antenna-reflector combination operating in the Fresnel region atmicrowave and millimeter-wave bands

A method for calculating antenna-reflector combination gain for rectangular reflectors operating in the Fresnel region is derived instead of an approximate method based on an equi-area circular reflector. The scope of microwave application of the method is discussed, and reflector-equipped microwave links in operation are examined using the new method. A field test result using 50-GHz radio equipment with four types of reflectors shows good agreements with the theoretical calculations     

Efficient parametric yield optimization of VLSI circuit by uniform design sampling method

A novel yield estimation and optimization method is proposed based on uniform design sampling (UDS) method, which is one kind of quasi-Monte Carlo method. Compared with primitive statistical methods based on Monte Carlo sampling method, this new method needs only few circuit simulations to have a valuable estimation and is immune to the number of statistical variables. Furthermore, owing to simple algorithm to generate samples, the UDS method adds no computational complexity. A comparison of UDS method with the popular Monte Carlo based method–Latin hypercube sampling method is made in this paper to show the efficiency of the new method. Finally, several examples are presented to demonstrate the advantages of the proposed method over those available.     

基于FDTD的运动导体目标电磁散射仿真

提出了一种基于散射模型的等价相对边界条件。将该等价相对边界条件与传统FDTD方法相结合提出了求解运动导体目标电磁散射问题的方法。并将该方法用于计算运动的无限大导体表面的电磁散射问题，计算结果与文献所给方法的计算结果吻合很好，验证了该方法求解运动导体目标电磁散射问题的正确性和有效性。用该方法计算了运动三维导体目标的雷达散射截面。     

Multimode moment method formulation for waveguide discontinuities

A computationally efficient method for analyzing waveguide discontinuities is presented. The method is based on Galerkin's moment method formulation. The generalized scattering matrix of a waveguide discontinuity is derived. A generalized equivalent circuit is constructed which gives physical insight to the problem. The method is found to be several times faster than the well-known mode matching technique. The accuracy of the proposed method is demonstrated by comparing the numerical result with the measured return loss of a multisection iris-coupled filter     

A method for calculating eigenmodes of shielded waveguides with a complex smoothly varying shape of the cross section

A method is proposed that can be used for calculating eigenmodes of shielded waveguides with an arbitrary smooth dependence of the waveguide parameters on the transverse coordinate. A system of differential equations with boundary conditions is obtained to which the solution of the problem can be reduced. The method is tested with the use of the example of homogeneously and partly filled shielded waveguides. The efficiency of the method is demonstrated through comparison with known results.     

旋转波片法在低应力测量中的应用

本文提出用旋转λ/2波片和分析片来代替转动物体的新方法,解决了用电光调制法测定某些物体低应力值时,物体很难转动的难题.     

A field theoretical comparison of FDTD and TLM

A field theoretical derivation of the three-dimensional TLM method with expanded node and of the three-dimensional TLM method with asymmetrical condensed node is given. In the derivation, the Method of Moments is applied to Maxwell's equations. The wave amplitudes are related to the tangential field components at the boundaries of the TLM cell. The same approach is applied to derive the FDTD method from Maxwell's equations. A complete dispersion analysis is given for the two TLM methods as well as for the FDTD method     

余弦调制滤波器组的原型滤波器设计

该文提出了一种近似重构的余弦调制滤波器组的原型滤波器设计方法。该方法将原型滤波器表示成A(z2)B(z)的形式(其中B(z)是最平坦FIR滤波器),通过优化低阶FIR滤波器A(z)的通带边缘频率,间接设计原型滤波器。文中给出的设计例子表明,该方法可获得很高阻带衰减的滤波器组。