One-pixel-wide closed boundary identification

An appropriate space of one-pixel-wide closed (OPWC) boundary configurations is explicitly defined and an automatic algorithm to obtain OPWC contour estimates from a segmented image is presented. The motivation is to obtain a reasonable starting estimate for a Markov chain Monte Carlo-based (McMC-based) boundary optimization algorithm.     

The dominant mode in closed V-groove guide

The structure of closed V-groove guide is similar to that of open one, but it can prevent energy from leaking out of the guide. In this paper, the dominant mode in the closed V-groove guides are analysed by using the approach of equivalent network with transverse resonance. The results have important practical values in design, manufacture and application of V-groove guide.     

Energy considerations in open and closed waveguides

Energy relations derived for a lossless closed uniform and periodic structure show that the total complex Poynting vector integrated over the cross section is identically zero for the case of an arbitrary complex wave. These results are also applicable to open structures provided certain conditions are satisfied. The application of these results in the field of leaky wave antennas is discussed. Two illustrative examples, those of the sinusoidally modulated reactance surface and the sheath helix, are worked out. It is shown that although the slope of the dispersion curve can no longer be associated with the direction of net power flow, the knowledge of the slope may still be helpful in selecting certain modes for representing a given source.     

The dominant mode in closed circular groove guide

The structure of closed circular groove guide is similar to that of open circular groove guide, but it can prevent energy from leaking out of the guide. In this paper, the dominant mode in closed circular groove guide is considered. The characteristic equation is derived and solved and the results are discussed.     

A closed slot-line resonator filter

A microwave bandpass filter made from three-dimensional (3-D) slot-line resonators is described. This structure readily lent itself to the design and realization of a 16-pole filter. By concentrating the losses on the resonant element, very high Q can be achieved by using low surface resistance material, such as high temperature superconductor, for the slot-line resonator. The filter is five to ten times smaller than previous generation 3-D filters made using high temperature superconductors.     

一种DCT域的闭环数字水印技术

本文提出了一种DCT域的闭环数字水印技术，水印的嵌入是一个闭环过程。水印嵌入的初始强度由视觉系统结合JPEG量化表确定，并根据性能分析的结果不断调整水印的嵌入，如果性能分析结果满足某种检测要求或者水印的嵌入已经影响了图像的显示质量，相应调整水印嵌入的强度，以实现水印的最佳嵌入。本文证明了所提出的闭环水印过程具有收敛性，还对检测过程中的似然函数的分布规律进行了分析，得到正确检测率和错误检测概率的表达式，可作为闭环系统的判决条件。实验结果证明这种闭环水印技术比传统DCT域的水印技术性能好。     

相控阵雷达系统建模中的天线仿真技术

在对相控阵雷达系统建模仿真工作中,相控阵天线建模仿真是其中的关键所在。首先研究和探讨了平面相控阵天线仿真数学模型,给出了方向图数学函数。接着介绍了相控阵雷达系统建模中天线建模仿真的两种主要方法,多通道阵元级合成方法和方向图数据载入法。阵元合成法基于方向图数学函数给出了常规和差多通道的仿真算法,方向图载入法研究了如何对数据文件进行双线性插值来计算任意角度的增益。最后利用多通道阵元级合成方法进行了天线方向图建模仿真,通过仿真结果表明该算法的正确性,并说明两者仿真方法的适用条件。     

An ON-resistance closed form for VDMOS devices

An analytical ON-resistance expression for different designs of VDMOS (vertically diffused metal-oxide-semiconductor) devices which takes into consideration the two-dimensional (2-D) nature of the current flow is obtained. This expression differs from other models that overestimate this resistance for large cell spacings. This formulation is in close agreement with experimental points obtained from the interdigitated fabricated structures and with 2-D simulations. Moreover, the effect of a two-level oxide thickness on the ON resistance has been investigated for the interdigitated case     

Studies on the closed circular groove guide

When the circular-groove guide is closed at the two side ends by metal, its dispersion characteristic is studied in this paper, and theoretical values are presented. The eigen-weighted boundary integral equation method was used here.     

Performance of closed loop transmit diversity in a Rayleigh fading channel

In this paper, the closed loop transmit diversity technology for the Wideband Code Division Multiple Access（WCDMA） systems is investigated in a multipath Rayleigh fading channel. The RAKE receiver model and the weighing vector algorithm are presented. The performance is theoretically analyzed in terms of the average maximal Signal-to-Noise Ratio（SNR） gain available over the Space-Time block coding based Transmit Diversity（STTD） technology. Theoretic analysis and simulation results show that the closed loop transmit diversity can provide a 3dB performance gain over the open loop scheme in a single path fading channel, while the performance gain decreases dramatically with the increasing inherent multipath diversity of the wireless channel.     

Potential distribution inside a closed cavity in terms of surface potentials

An analytical expression for the potential distribution inside certain cavities is obtained. This expression is based on the equipotential surface considerations as produced by two confining surfaces at a time. The results obtained for several geometries agree to better than 93 percent with the results obtained numerically using the finite difference formulation.     

Ray methods for modal fields in general closed and open propagationenvironments

The author presents a systematic methodology for using modal solutions in nonseparable geometries. Ray parametrization is used as a technique for constructing approximate modal wave fields to treat guiding and ducting environments with varying transverse and longitudinal properties. Ideal modes are decoupled from, and propagate independently of, other modes in the set. When the channel does not conform with separability in one of the basic coordinate systems, ideal modes defined for separable conditions become coupled. If the departure from separability is weak, one may define adiabatic modes (AMs) that adapt smoothly, without coupling to other AMs, to the slow nonseparable longitudinal variations, retaining their distinct spectral identity throughout. Each AM fails in its own cutoff region, across which its wavefield changes from being propagating to becoming evanescent, and it must there be extended into an intrinsic mode (IM) which has greater spectral content     

Modeling QRS complex in dECG

It is proposed to model the derivative of electrocardiogram (ECG) signal, which we refer to as dECG, instead of the ECG signal. It is shown that the QRS complex in the dECG signal can be represented in the frequency domain by an all-pole model of appropriate order, the coefficients of the model being determined using the covariance method of linear prediction applied over an analysis interval that includes the QRS complex and that is centered about the R-peak. Modeling of dECG, instead of ECG, gives a better spectral representation of the QRS complex.     

Manifold Modeling in Machine Learning

Journal of Communications Technology and Electronics - Predictive Modeling problems deal with high-dimensional data; however, the curse of dimensionality presents an obstacle to the use of many...     

Modeling of Recombination in HgCdTe

Minority carrier recombination lifetime calculations for narrow-gap semiconductors are of direct practical interest in establishing whether a material’s recombination is extrinsically or intrinsically limited, and therefore in guiding research and development programs regarding material quality improvements. We describe efforts to obtain accurate electronic band structures of HgCdTe alloy-based materials with infrared energy gaps and employ them to evaluate Auger recombination lifetimes. We use a 14-band k · p formalism to compute and optimize electronic band structures, and use the obtained electronic energies and matrix elements directly in the numerical evaluation of Auger and radiative lifetimes.     

Modeling metastable states in ASIC

The metastable behavior is unavoidable in sequential circuits. It is therefore important to characterize the circuit elements with this respect. The response time method correlates the additional delay due to the onset of metastability with the MTBF; it has been used to determine the failure window of MOSAIC3 flip-flops (emitter width 1μm, transition frequency 15GHz). The double sampling method allows a more accurate investigation of the metastability conditions. It has been applied to HDC gate arrays (CMOS, 1μm drawn channel length). Based upon the experimental results, a simulation model has been introduced in the ASIC library.     

Modeling Thermal Effects in Nanodevices

In order to investigate the role of self-heating effects on the electrical characteristics of nanoscale devices, we implemented a 2D Monte Carlo device simulator that includes the self-consistent solution of the energy balance equations for both acoustic and optical phonons. The acoustic and optical phonon temperatures are fed back into the electron transport solver through temperature-dependent scattering tables. The electrothermal device simulator was used in the study of different generations of nanoscale fully depleted silicon-on-insulator devices that are either already in production or will be fabricated in the next five to ten years. We find less degradation due to self-heating in very short channel device structures due to the increasing role of nonstationary velocity-overshoot effects which are less sensitive to the local temperature.     

汽车电磁兼容中的建模挑战

随着汽车向智能化和互联化发展,汽车电磁兼容性(EMC)变得越来越重要.相较于传统的在最后阶段解决电磁兼容问题,将EMC设计和风险控制纳入早期设计阶段至关重要,可以有效实现这一目标的仿真技术也变得愈发关键.通过仿真还可以研究许多电磁兼容问题,如模块级和系统级的电磁干扰(EMI)测试的不一致问题.但由于计算资源、计算机算法的限制以及关键信息的缺乏,汽车电磁兼容的仿真往往具有很大的挑战性.本文以电机驱动系统对安装在混合动力电动汽车(HEV)上的射频天线的射频干扰为例,说明了混合动力车辆级仿真面临的挑战,提出了一种分而治之的解决方案,并验证了其有效性.     

Modeling multiple-longitudinal-mode dynamics in semiconductorlasers

We present a time-dependent coupled-wave equation analysis for simulating both single- and multilongitudinal-mode dynamics in semiconductor lasers, while incorporating frequency-dependent gain in a particularly simple way. In our first application, we analyze the response of Fabry-Perot semiconductor lasers to feedback levels ranging from -60 to -30 dB. This allows us to anchor, continuously, from single-mode phenomena at weak feedback levels to multimode behavior at stronger feedback levels. To our knowledge, this is the first simulation of multilongitudinal-mode dynamics that are induced in a laser at feedback levels exceeding -30 dB, Feedback-induced phenomena provide a significant test of both the single-mode and multimode capabilities of our coupled-wave model. In our second application, we analyze a modern, large-scale device for which multiple longitudinal modes, as well as compound cavity modes, are a significant possibility. Specifically, we consider facet-coating requirements for a new class of monolithic master-oscillator power-amplifier (MOPA) devices