Reliability modeling and performance of variable link-capacitynetworks

The discussion by R. Schanzer (see ibid., vol.44, p.620-1, 1995) tries to correct the algorithms of P.K. Varshney, et al. (see ibid., vol.43, p.378-82, 1994) and K.K Aggarwal (see ibid., vol.37, p.65-9, 1988). But Schanzer doesn't explain why those algorithms have difficulty in calculating the maximum flow. This paper explains the problem and gives a correction of the algorithm so that the basic problem can be solved     

Stochastic modeling and estimation of multispectral image data

Multispectral images consist of multiple channels, each containing data acquired from a different band within the frequency spectrum. Since most objects emit or reflect energy over a large spectral bandwidth, there usually exists a significant correlation between channels. Due to often harsh imaging environments, the acquired data may be degraded by both blur and noise. Simply applying a monochromatic restoration algorithm to each frequency band ignores the cross-channel correlation present within a multispectral image. A Gibbs prior is proposed for multispectral data modeled as a Markov random field, containing both spatial and spectral cliques. Spatial components of the model use a nonlinear operator to preserve discontinuities within each frequency band, while spectral components incorporate nonstationary cross-channel correlations. The multispectral model is used in a Bayesian algorithm for the restoration of color images, in which the resulting nonlinear estimates are shown to be quantitatively and visually superior to linear estimates generated by multichannel Wiener and least squares restoration.     

可变R-L-C元件的SPICE模拟行为建模

一些仿真器没有包含LRC元件的ABM方程,采用本文所述的简单子电路,可以根据复杂的分析表达式（包括逻辑表达式）创建无源元件,比如建立非线性电容、时变电阻等.     

Stochastic kinematic modeling and feature extraction for gait analysis

This research presents a new model-based approach toward the three-dimensional (3-D) tracking and extraction of gait and human motion. We suggest the use of a hierarchical, structural model of the human body that introduces the concept of soft kinematic constraints. These constraints take the form of a priori, stochastic distributions learned from previous configurations of the body exhibited during specific activities; they are used to supplement an existing motion model limited by hard kinematic constraints. We use time-varying parameters of the structural model to measure gait velocity, stance width, stride length, stance times, and other gait variables with multiple degrees of accuracy and robustness. To characterize tracking performance, we also introduce a novel geometric model of expected tracking failures. We demonstrate and quantify the performance of the suggested models using multi-view, video sequences of human movement captured in a complex home environment.     

无线电波传播中的随机射线及其应用

对建模无线电波传播的随机射线进行了详细的阐述,从随机网格信道引出随机射线的概念,介绍了随机射线的产生背景和分类,并给出一种产生随机射线的数学模型随机桥过程。使用最大熵原理得到发生后次反射随机射线的概率分布。最后介绍使用随机射线建模超宽带室内信道的多径传播轨,在此基础上可以得到信道特性建模的基本随机变量,以及无线电波传播的概率模型等应用。     

Compact modeling of CMOS transistors under variable uniaxial stress

This paper presents a novel implementation of variable uniaxial mechanical stress model to be used with DC circuit simulation, e.g. using BSIM3v3 transistor model. Based on transistor measurements under various uniaxial stress conditions two stress-dependent parameters are identified, namely the carriers mobility and to a lesser extend the carrier saturation velocity. The effect of the parasitic source/drain resistance on the piezoresistive coefficient determination is addressed in detail. Using the fundamental piezoresistive coefficients, the model has implemented a general relation to calculate the coefficients for arbitrary directions of current and stress in the (0 0 1) silicon (Si) plane. The extended transistor model allows for simulating the effect of uniaxial stress on any MOSFET geometry, under different operation conditions and for any combination of the drain current and stress orientations in the (0 0 1) silicon (Si) plane. The method proposed in this paper is validated by static and dynamic stress-dependent simulations and comparison with experimental data. The method is simulator-independent and can be adapted to other bulk CMOS technologies including SOI processes.     

Stochastic geometry modeling and energy efficiency analysis of millimeter wave cellular networks

Current wireless networks face unprecedented challenges because of the exponentially increasing demand for mobile data and the rapid growth in infrastructure and power consumption. This study investigates the optimal energy efficiency of millimeter wave (mmWave) cellular networks, given that these networks are some of the most promising 5G-enabling technologies. Based on the stochastic geometry, a mathematical framework of coverage probability is proposed and the optimal energy efficiency is obtained with coverage performance constraints. Numerical results show that increasing the base station density damages coverage performance exceeding the threshold. This work demonstrates an essential understanding of the deployment and dynamic control of energy-efficient mmWave cellular networks.     

Stochastic context-free grammars and hidden Markov models for modeling of bursty channels

In order to design good error-control schemes for bursty channels and also to facilitate performance analysis, it is important to develop accurate and simple statistical channel error models for the channels of interest. We propose two novel generative methods to model the end-to-end error profile of radio channels described by long well-defined error bursts interleaved with long error-free intervals. The first method makes use of the power of stochastic context-free grammars to model palindromes. The second utilizes simple hidden Markov models with specific structures, which are suggested by the ideas presented in the first method. Both methods achieve much better performance than previously proposed approaches without introducing more complexity. Although the complexity of the second method is slightly greater than that of the first, its advantage is that it can be easily applied in decoding implementations specifically tailored to deal with bursty channels.     

An overview of manufacturing yield and reliability modeling forsemiconductor products

This paper presents an overview of yield, reliability, burn-in, cost factors, and fault coverage as practiced in the semiconductor manufacturing industry. Reliability and yield modeling can be used as a foundation for developing effective stress burn-in, which in turn can warranty high-quality semiconductor products. Yield models are described and their advantages and disadvantages are discussed. Both yield reliability relationships and relation models between yield and reliability are thoroughly analyzed in regard to their importance to semiconductor products     

Stochastic interconnect modeling, power trends, and performancecharacterization of 3-D circuits

Three-dimensional (3-D) technology promises higher integration density and lower interconnection complexity and delay. At present, however, not much work on circuit applications has been done due to lack of insight into 3-D circuit architecture and performance. One of the purposes of realizing 3-D integration is to reduce the interconnect complexity and delay of two dimensions (2-D), which are widely considered as the barriers to continued performance gains in future technology generations. Thus, understanding the interconnect and its related issues, such as the impact on circuit performance, is key to 3-D circuit applications. In this paper, we present a stochastic 3-D interconnect model and study the impact of 3-D integration on circuit performance and power consumption. To model 3-D interconnect, we divide 3-D wires into two parts (horizontal wires and vertical wires) and derive their stochastic distributions. Based on those distributions, we estimate the delay distribution. We show that 3-D structures effectively reduce the number of long delay nets, significantly reduce the number of repeaters, and dramatically improve circuit performance. With 3-D integration, circuits can be clocked at frequencies much higher (double or even triple) than 2-D     

基于SHAKF滤波器的MEMS陀螺随机误差建模补偿

MEMS陀螺随机漂移误差是制约惯性导航精度的关键因素。本文针对标准kalman滤波器陀螺漂移处理方法中,随机动态系统的结构参数和噪声统计特性参数不准确的问题,采用自适应SHAKF(Sage-Husa Adaptive Kalman Filter)滤波器进行参数实时估计,提高陀螺漂移精度。基于此思想,建立了ARMA随机误差模型,搭建了MEMS陀螺组件实验系统,通过高精度三轴转台静态测试采集陀螺数据。Aallan方差分析表明,零偏不稳定性经线性KF滤波后提升17.4%,经自适应SHAKF滤波后提升26.2%。     

Stochastic geometry modeling and analysis of downlink coverage and rate in small cell network

Telecommunication Systems - Due to the massive wireless traffic demand in fifth generation (5G) network, small cell have been attracted growing attention as a key solution and scalable approach for...     

基于几何和纹理混合的工业产品三维建模

基于风格化的特征形状或外观样式的三维建模是产品设计客观需求,为此本研究提出了一种基于程序化建模方法的工业产品三维建模软件设计。所述建模方法首先将产品三维模型分割为基础功能模型和样式特征模型,其次搜索基础模型和样式模型的所有可能组合,最后通过采用变形技术将模型在纹理和几何水平上组合。评估结果表明,该建模软件能够输出满足用户感官需求的风格化设计产品,且具有良好的系统性能。     

基于变跟踪点的红外场景仿真原理及关键技术研究

由于基于固定跟踪点的红外场景仿真技术不能真实考核导引头对目标要害部位的识别及跟踪性能,这无法满足第四代红外成像制导空空导弹的新要求。本文针对基于固定跟踪点红外场景仿真存在的问题进行了分析,提出了基于变跟踪点的红外场景仿真原理,并对影响变跟踪点红外场景仿真工程应用的关键误差因素进行建模及定量仿真分析,指出了变跟踪点红外场景仿真误差的敏感因素,可为变跟踪点红外场景仿真的工程化应用提供技术参考。     

Stochastic geometry based models for modeling cellular networks in urban areas

Recently a new approach to modeling cellular networks has been proposed based on the Poisson point process (PPP). Unlike the traditional, popular hexagonal grid model for the locations of base stations, the PPP model is tractable. It has been shown by Andrews et al. (in IEEE Trans Commun 59(11):3122–3134, 2011) that the hexagonal grid model provides upper bounds of the coverage probability while the PPP model gives lower bounds. In this paper, we perform a comprehensive comparison of the PPP and the hexagonal grid models with real base station deployments in urban areas worldwide provided by the open source project OpenCellID. Our simulations show that the PPP model gives upper bounds of the coverage probabilities for urban areas and is more accurate than the hexagonal grid model. In addition, we show that the Poisson cluster process is able to accurately model the base station location distribution.     

Analytical modeling of Transmission Control Protocol NewReno using Generalized Stochastic Petri Nets

This paper presents a novel analytical model of Transmission Control Protocol (TCP) using a generalized stochastic Petri net (GSPN). Extensive simulation work has been done for the performance evaluation of TCP NewReno protocol. In view of the limitations of the simulation technique, we present an analytical approach using GSPN. A GSPN is a useful mathematical tool that solves continuous time Markov chains for complex systems and evaluates the stationary behavior. In this paper, we analyze the slow‐but‐steady variant of TCP NewReno. The model captures the behavioral aspects of the slow start and the congestion avoidance phase together with the fast retransmit and recovery capabilities of TCP NewReno. Performance metrics such as throughput, goodput, and task completion time of the system are obtained. The effect of variation in the model parameters on the performance is studied. The results are validated using the network simulator, and their accuracy is verified by evaluating the confidence interval. The performance of the proposed model is compared with that of TCP Reno. The performance of the proposed model is also compared with one of the previous models. The numerical illustrations and comparison of the proposed technique with simulation validates the accuracy, efficiency, and competence of the GSPN technique. While GSPN modeling for TCP is investigated in depth for the TCP NewReno and TCP Reno variant in this paper, other protocols could be also analyzed similarly. Copyright © 2013 John Wiley & Sons, Ltd.     

基于虚拟现实技术的工业产品造型设计

为了使用虚拟现实(VR)技术对工业产品进行外观建模,以便利用其先进的人机交互技术来提高产品造型设计的工作效率,提出基于虚拟现实技术的工业产品造型设计方法。首先对工业产品造型设计的影响因素和美学法则进行分析,并构建了虚拟设计环境的总体框架;然后建立了立体视觉模型并采用Vega虚拟现实开发平台创建虚拟环境;最后给出了虚拟环境下产品造型的效果分析。通过将虚拟技术应用于产品造型设计能够在产品制造前对产品造型及人机交互效果进行评价和改进,从而达到缩短开发周期的目的,降低产品的生产成本。