Realistic statistical worst-case simulations of VLSI circuits

A simple and cost-effective method for evaluating the parametric product manufacturability of VLSI circuits is presented. The method, named gradient analysis, enables designers to predict the standard deviation of the circuit performance from measured or specified design parameter variations. This method, with a minimum extra design cost, avoids the overdesign associated with the traditional prediction of the worst-case performance of VLSI circuits. Gradient analysis also provides designers with information on the sensitivity of the circuit performance variations to the design parameter variations. In this way the key design parameters for process monitoring and control are identified. Experimental qualification of the method is discussed based on development and production data of VLSI products such as high-speed 1.2 μm 64 K CMOS static RAMs (SRAMs),     

A theory of automatic parameter selection for feature extraction with application to feature-based multisensor image registration.

This paper generalizes the previously developed automated edge-detection parameter selection algorithm of Yitzhaky and Peli. We generalize the approach to arbitrary multidimensional, continuous or discrete parameter spaces, and feature spaces. This generalization enables use of the parameter selection approach with more general image features, for use in feature-based multisensor image registration applications. We investigate the problem of selecting a suitable parameter space sampling density in the automated parameter selection algorithm. A real-valued sensitivity measure is developed which characterizes the effect of parameter space sampling on feature set variability. Closed-form solutions of the sensitivity measure for special feature set relationships are derived. We conduct an analysis of the convergence properties of the sensitivity measure as a function of increasing parameter space sampling density. For certain parameter space sampling sequence types, closed-form expressions for the sensitivity measure limit values are presented. We discuss an approach to parameter space sampling density selection which uses the sensitivity measure convergence behavior. We provide numerical results indicating the utility of the sensitivity measure for selecting suitable parameter values.     

基于MFCC0的语音端点检测方法

MFCC是语音识别中常用的特征参数，根据MFCC分量对语音端点的敏感性，提出利用平常舍去的识别特征参数分量MFCC0作为语音端点检测的参量．接着根据MFCC0的特性设计了一种新的端点检测方法，该方法简单且无需增加额外的计算量．实验结果表明，基于该方法的语音识别系统不仅可以通过端点检测大大压缩数据量，而且提高了系统的识别率．     

The effect of the signal-to-noise ratio in CBED patterns on the accuracy of lattice parameter determination

A method of higher-order Laue zone line position measurement in convergent-beam electron diffraction (CBED) is proposed based on Hough transformation. A thorough analysis of the errors introduced by this measurement procedure is performed and their influence on the accuracy of lattice parameter determination is estimated. A criterion is derived which enables the accuracy to be predicted before experimental measurements are made and, thus, allows the selection of the best CBED geometry for parameter measurement.     

Statistical model of an undermoded reverberation chamber

Weibull distribution is adopted to model the electric field component of a Reverberation Chamber (RC). Its first property is to include the asymptotic laws, such as Rayleigh and exponential, and its main advantage lies in the fact that the Weibull shape parameter enables a model of the departure from overmoded to undermoded RC regime. Applications are given, such as an RC modal finite element modeling and a Monte Carlo simulation: they prove that the Weibull two-parameter distribution correctly models the quality factor influence. Moreover, the relevance of the use of this extreme value distribution is illustrated.     

Orthogonal transform for estimating the number of targets in a radar resolution cell

The problem of estimating the number of moving targets in a resolution cell is considered. An orthogonal transform is described which enables this parameter to be derived. The application of the method is disscussed with reference to an experiment using real data.     

The ΣΔ-BIST Method Applied to Analog Filters

This paper describes the -BIST method, defined as an analog BIST circuit in the context of mixed signal systems. The test procedure is based on the reuse of existing analog circuits configured as sigma-delta modulators in the analog domain. The test procedure reuses most of existing blocks in a mixed signal system, and thus has small area overhead. Test sensitivity is very high, detecting small component deviations. Moreover, the proposed test technique can be applied to continuous or sampled time circuits, and the test procedure can be developed in the field. The paper explains the method and presents practical results to validate the proposed approach.     

Adaptive reversible data hiding scheme based on integer transform

In this paper, we present a new reversible data hiding algorithm based on integer transform and adaptive embedding. According to the image block type determined by the pre-estimated distortion, the parameter in integer transform is adaptively selected in different blocks. This allows embedding more data bits into smooth blocks while avoiding large distortion generated by noisy ones, and thus enables very high capacity with good image quality. For instance, by the proposed method, we can embed as high as 2.17 bits per pixel into Lena image with a reasonable PSNR of 20.71 dB. Experimental results demonstrate that the proposed method outperforms some state-of-the-art algorithms, especially for high capacity case.     

A methodology to determine gains of induction motor flux observersbased on a theoretical parameter sensitivity analysis

A method to compute gains of induction machine flux observers, based on a theoretical sensitivity analysis taking the magnetic saturation into account, with the aim to minimize the observer sensitivity to electrical parameter uncertainties is proposed in this paper. It is shown for a reduced order observer, that the sensitivity to parameter uncertainties may be independent of the reference frame, when a modification is introduced in the classical determination of the slip frequency. It is also shown how to extend the proposed method to a full order observer. The theoretical study is completed by experiments on a 750 W induction machine (using DSP TMS320C31) which confirms the theoretical results     

一种基于噪声模型的小波系数量化补偿方法

本文提出一种基于噪声模型的小波系数量化补偿方法,在小波变换域上对零截断系数采用简单的噪声模型进行补偿,解码端根据模型参数,合成随机纹理,改善因系数零截断量化造成的随机纹理失真,从而提高解码图像的主观视觉质量.实验结果表明,模型参数编码只需0.013bpp.在相同编码比特率的情况下,与JPEG2000缺省编码方法相比,图像主观质量得到很大改善.     

传输线网络瞬态响应灵敏度分析方法

针对传输线网络瞬态响应灵敏度分析问题,提出了一种采用快速傅里叶变换的灵敏度分析方法。方法从描述整个传输线网络特性的电路方程出发,将传输线网络瞬态响应灵敏度转化为求解传输线网络瞬态响应以及网络参数矩阵对电路参数的偏导数,实现了传输线网络任意节点瞬态响应对任意网络参数的灵敏度分析。该方法无需对耦合传输线进行解耦,能够分析任意类型传输线及任意负载。算例结果表明,方法正确有效。     

A novel method for designing chirp characteristics inelectroabsorption MQW optical modulators

We propose a novel method to control the chirp parameter characteristics in electroabsorption (EA) multiquantum-well (MQW) optical modulators. We demonstrate that a large decrease of absorption on the short wavelength side enables us to achieve a negative chirp parameter that is independent of the extinction characteristics. This is achieved by enhancing the decrease in the absorption by higher states, which can be brought about by a shallow heavy-hole band discontinuity. It is also experimentally shown that a negative chirp operation from a near-zero-bias voltage in GaInAsP MQW optical modulators is realized by applying this new concept     

A simple estimation of transverse response of high-g accelerometers by a free-drop-bar method

In this research, a simple free-drop-bar method was proposed to evaluate the transient transverse response (or the transverse sensitivity) of a high-g accelerometer with full-scale of 50,000g. Four different metal bars with different lengths and diameters were used in the dynamical impact experiments. It shows that the transverse response depends on the dimension (aspect ratio) of the round metal bar used. The bar with small diameter is favored due to its low distortion and attenuation of wave. For the same device, the bar with small diameter less than 16 mm gives the very low transverse response about 3%, which approaches the results measured by the sinusoidal vibration method. While the thick bar with 20 mm in diameter gives high transverse response about 10%. When performed in the usual drop-hammer equipment, the transverse response even reaches 24%. Stress analysis shows that the transverse response is proportional to the diameter squared of round metal bar used. It is demonstrated that this method is easy to implement with higher repeatability and reliability. In addition to the transverse response, the parameter such as the sensitivity can also be evaluated using the free-drop-bar method.     

Minimizing the average cost of paging and registration: A timer-based method

Methods of balancing call registration and paging are developed in this paper. Given that the probability distribution on the user location as a function of time is either known or can be calculated, previous work shows the existence of lower bounds on the average cost of paging. Here these bounds are used in conjunction with a Poisson incoming-call arrival model to formulate the paging/registration optimization problem in terms oftimeout parameters, _m ; the maximum amount of time to wait before registering given the last known location wasm. Timer-based methods, as opposed to location-based methods, do not require the user to record and process location information during the time between location updates. This feature might be desirable for minimizing mobile transceiver use during idle periods. We then consider uniform motion processes where a spatial translation of starting location produces an identical spatial translation of the associated time-varying probability distribution. This leads to a universal timeout parameter which may be readily calculated. We study and the minimum cost of paging/registration for a simple model of user motion and compare our results to an earlier method of location-based paging/registration cost minimization.     

Stokes参数数字化求解的误差分析

Stokes参数是描述极化波的强度量纲,在电磁测量、合成孔径雷达、辐射计中均有广泛应用.文中提出了求解Stokes参数的数字化方法,具有带宽高、稳定性高等特点.针对将模拟信号采样量化后求解Stokes参数的方法,本文分别就自相关和互相关两种计算过程,详细分析并给出了数字量化对最终亮温的误差贡献.文中证明了高于3bit量化引入的亮温误差小于1*10^-5K,进一步给出了量化后的系统灵敏度,分析了由数字量化产生的亮温灵敏度偏差.当量化位数为3bit时,数字相关系统灵敏度可以达到理想模拟相关系统的95%.本文为不同应用条件下,满足不同精度时,如何选择特定量化位数与量程提供了依据.     

星载SAR系统参数设计过程自动化方法研究

针对星载合成孔径雷达（Synthetic Aperture Radar，SAR）系统参数设计过程中部分参数仍需手工选取，并且系统根据设计结果无法做出反应的问题。本文提出了一种星载SAR系统参数自动化设计的方法。首先，针对脉冲重复频率（Pulse Repetition Frequency，PRF）和波位位置等重要参数进行了优化选取设计。然后，利用比例?积分?微分（Proportion?Integral?Differential，PID）控制器对系统参数结果作自动化调节。仿真和实验结果表明，与传统的星载SAR系统参数设计方法相比，该方法具有便捷高效、易于实现的特点，提高了星载SAR系统设计过程中参数选取的自动化程度，实现了当系统技术指标的评测结果不满足用户要求时的参数自动调节。     

Analysis and Optimization of an Adaptive Selective-Repeat Scheme for Time-Varying Channels with Feedback Errors

In this article, an adaptive SR ARQ scheme is analyzed and optimized in a time-varying channel environment with unreliable feedback. Two-state Markov models are assumed for both the forward and the returnchannel.This enables the time behaviour of the entire system to be modelledby a Markov chain. To have an easy-to-implement scheme, we choose the smaller packet size to be half of the bigger one. Thus, there is only oneindependent design parameter related to packet size. The other two parametersare associated with channel sensing. The performance of the adaptive schemeis measured by its average throughput, which is upper-bounded by the throughput of the so-called ideal adaptive scheme. This upper bound is very useful in the optimization of the packet size and other design parameters. From the results, it can be concluded that the selection of the packet size is at least as critical as the optimization of the other parameters. The feedback errors degrade the throughput of the scheme, but their effect on the parameter optimization turns out to be almost negligible.     

Study on the response characteristics of adaptive focusing system for flying optics

The ABCD law of parameter q for fundamental-mode Gaussian beam is deduced in this paper. The result shows that the changes of focal length and focal depth are not related to the orders of the Gaussian beam modes when focus lens moves along optical axis in a large range, indicating that the ABCD law of parameter q can be used for any order modes. A laser focusing setup is designed, and the response characteristics of oil pressure system therein are also studied.     

Supporting mobile multimedia in integrated services networks

Owing to widespread user mobility, limited radio resources, and changing network characteristics, supporting multimedia communications in a mobile internetworking environment is a challenging problem. In this paper, we present an adaptive reserved service framework for use in integrated services networks to support mobile connections carrying multimedia traffic. Integrated in the framework are an anticipatory handoff control mechanism which enables fast handoff, and an adaptive link partitioning scheme which enhances handoff success. Besides, bandwidth reservations in the wireline network are dynamically adjusted based on resource availability in the wireless networks. An accompanying reservation protocol not only facilitates distributed control of mobile connections but also provides network feedback to mobile hosts.An earlier version of this paper appeared in the First International Conference on Mobile Computing and Networking, 1995.     

Making Decisions Under Uncertainty — Implications for High Technology Investments

Businesses are continuously confronted with decisions that have to be made under different degrees of uncertainty. The project investment strategy adopted by a company will have a major impact on its future growth and profitability. Managing a company is therefore primarily about managing uncertainties and understanding the relationships between the risk and the opportunities in each business proposal.This paper discusses the inadequacies of net present value (NPV) modelling in dealing with the management of uncertainties, which are common in high-tech investments. NPV modelling deals with uncertainties by increasing the discount rate, which reduces the probability of approving the project. However, by including management options into the project valuation process the value of the project may increase substantially and therefore have an impact on the decision to go ahead or not. We discuss how the application of real options is superior to an NPV approach as it enables the investor to put concrete value on the project uncertainties. The key is flexibility in dealing with the uncertainties by having various options in place that can be exercised as new information emerges. The options derive their value from the fact that they put a floor under possible project losses.We apply the binomial tree method to the valuation of various options associated with high-tech investments, including the option to defer, expand or contract a project. We also consider the value associated with a mixture of equity and debt financing of high-tech, high-risk research projects.