An Almost Sure Result on Sampling of Bandlimited Random Signals

The Shannon-Nyquist sampling theorem for deterministic signals is a fundamental result in the field of telecommunication and signal processing, and many re- sults on this topic have been obtained. However, very few results on random signals have been published, after Kol- mogorov mentioned the importance of Shannon-formula for stochastic signals in 1956. In this paper, following the almost sure result for bandlimited stochastic processes pro- posed by Seip in 1990, we give an almost sure result of the classical sampling theorem for bandlimited random signals with local average sampling.     

On Sequenial Tests of the Bincknial Distribution

In this paper, we consider the detailed characteristics of the standard sequential test of a simple hypothesis versus a single alternative for the case of the binomial distribution. A method is developed which permits evaluation of the associated probabilities of acceptance and/or rejection of the null hypothesis at each stage. From this information, the quantitative features of the test (Operating Characteristic and test termination probability) are completely determined. Curves are presented to facilitate assessment of the sequential procedure in practical cases. A sequential test is compared with a fixed sample size test having approximately the same Operating Characteristic. Wald's approximation for the average sample number is compared with exact values.     

Effective sampling strategy to detect food and feed contamination: Herbs and spices case

Sampling plans for food safety hazards are aimed to be used to determine whether a lot of food is contaminated (with microbiological or chemical hazards) or not. One of the components of sampling plans is the sampling strategy. The aim of this study was to compare the performance of three different sampling strategies, being simple random sampling (SRS), stratified random sampling (STRS), and systematic sampling (SS), with each other for their probability of detecting a heterogeneously distributed contamination in a lot of herbs or spices (i.e., a dry food product). To this end, a simulation model was developed, and applied to different scenarios for contamination level and numbers of samples collected. In addition, as a case study, the sampling plan of a company processing herbs and spices was evaluated using the simulation model. Results showed that the effectiveness of the sampling plan is influenced by the sampling strategy. With expected low contamination levels the SS strategy performs better than the two other strategies. At higher expected contaminated levels, the STRS strategy is preferred.     

Application and validation of a statistically derived risk-based sampling plan to improve efficiency of inspection and enforcement

The statistically derived risk-based sampling plan for surveillance sample assignments of chemical and biological hazards was designed using binomial probability distribution. The binomial statistics was applied to the past 3-year data to estimate a confidence interval and a sample size aiming to improve efficiency and effectiveness of the agency's sampling and inspectional activities. The accuracy of the statistical models and computed estimates were validated in the following years. The ranges of confidence interval and sample size appeared to be significantly influenced by a level of the violation rate of feed product samples, an acceptable error, a number of the analyzed samples, and a statistical significance level. The violation rates of feed products for target analytes (aflatoxins, fumonisins, Salmonella, and dioxin) in the validation data were lower than those of the average 3-year data in most feed products. Besides, the actual violation rates of the validation samples did not exactly fall within the anticipated range of the confidence interval estimates. Such a discrepancy is considered introduced by several factors such as sample size adequacy, skewed distribution of a target analyte in feed products, and unique analyte/product combination. The overall study results indicate that the risk-based plan of work would provide a more effective and efficient risk management tool to help improve the oversight of the feed industry and the compliance to feed safety standards.     

Situating Fortaleza: Urban space and uneven development in northeastern Brazil

The academic literature on Brazilian cities focuses overwhelmingly upon the metropolises of Rio de Janeiro and São Paulo. While fruitful in its own right, this research confronts scholars of Latin American cities elsewhere with two ongoing limitations: (1) Despite estimates that nearly one quarter of Brazil’s urban population inhabits the conurbation of Rio and São Paulo, at least 75% of urban space in Brazil, an area populated by roughly 120 million people, is consistently overlooked; and (2) the findings from these two megacities are often (and unfairly) extrapolated across other urban contexts in Brazil, perpetuating lingering misgivings about the overall ‘nature’ of Brazilian cities.In this paper, I consider the Northeast of Brazil, drawing upon my own research from the favela (slum) community of Pirambu, located in the city of Fortaleza, to help understand urban development outside of the Rio/São Paulo corridor. By considering historical circumstances, geographic specificity, theoretical implications, and the course of Brazilian development, I highlight informal urban growth in an oft-overlooked region of Latin America while, at the same time, revealing many of the geographic attributes that give Rio and São Paulo their truly exceptional character. My goal in this work is not to refute the work of others, but rather to underscore the importance of geographic context to socio-spatial processes of urban development.     

Sampling based uncertainty analysis of station blackout in PSB VVER integral test facility

Best estimate accident analysis with uncertainty evaluation is being encouraged in the present licensing scenarios of nuclear power plants. This paper deals with uncertainty and sensitivity analysis for station blackout in PSB VVER integral test facility under the framework of coordinated research project of IAEA. Nodalization was developed using best estimate system code RELAP5/MOD3.2 and its steady state and transient level qualifications are achieved. Sampling based approaches are used to carry out uncertainty and sensitivity/importance analysis. The objective of the analysis is to get confidence for uncertainty methodology by comparing with the experimental results and extend its applicability to NPPs. Uncertainty analysis is carried out by selecting nine important input parameters with specified ranges and its uniform distributions. A design matrix of 45 × 9 is generated for variations of input parameters with the Latin Hypercube Sampling and 45 code runs were taken. Linear regression was also carried out to quantify the effect of each individual input parameter on output parameters in terms of standard rank regression coefficients. Uncertainty band in output parameters is defined between 95th and 5th percentile value. It is observed that most of the experimental values and code calculated reference values are lying within the uncertainty band. For most of the parameters, width of uncertainty band increases with transient progression time.     

Probabilistic simulation of cable performance and water based protection in cable tunnel fires

Nuclear power plants contain a significant amount of fire load in form of electrical cables. The performance of the cables is interesting both from the fire development and system failure viewpoints. In this work, cable tunnel fires are studied using numerical simulations, focusing on the fire spreading along power cables and the efficiency of the water suppression in preventing the cable failures. Probabilistic simulations are performed using Monte Carlo technique and the Fire Dynamics Simulator (FDS) as the deterministic fire model. The primary fire load, i.e. the power cables are modelled using the one-dimensional pyrolysis model, for which the material parameters are estimated from the experimental data. Two different water suppression systems are studied. The simulation results indicate that using either suppression system decreased the heat release rate in the tunnel to less than 10% of the non-suppressed case. Without water suppression, the cables of the second sub-system were damaged in almost all fires, but when either of the studied water suppression systems was used, the probability of the cable failures was decreased to less than 1%. This result indicates that in current scenario, the probability of losing both sub-systems is determined directly by the suppression system unavailability.     

宽带雷达中频回波长脉冲压缩采样重构中的分段重叠处理及其机理分析

宽带雷达中频回波在频域上稀疏。根据压缩感知理论,可对其进行压缩采样并从压缩采样结果中以很高的概率重构出原信号。中频回波压缩采样的重构需要的矩阵尺寸由中频回波的长度决定。在长脉冲情况下,重构所需的矩阵尺寸大,占用内存资源过多,处理速度慢。针对此问题,论文将分段重叠处理引入重构过程。论文首先详细给出了引入分段重叠处理之后的重构方法,接着通过严格数学推导,证明了频谱泄漏与局部时域序列的关系具有如下特点:远离谱峰的谱值受时域序列两端的影响要强于靠近谱峰的谱值,利用该特点说明了分段重叠处理抑制误差的机理。实测数据实验表明了分段重叠处理在重构质量上优于分段不重叠处理,在对存储资源的要求上远低于不分段处理。     

A numerical integration-based yield estimation method for integrated circuits

A novel integration-based yield estimation method is developed for yield optimization of integrated circuits.This method tries to integrate the joint probability density function on the acceptability region directly. To achieve this goal,the simulated performance data of unknown distribution should be converted to follow a multivariate normal distribution by using Box-Cox transformation(BCT).In order to reduce the estimation variances of the model parameters of the density function,orthogonal array-based modified Latin hypercube sampling (OA-MLHS) is presented to generate samples in the disturbance space during simulations.The principle of variance reduction of model parameters estimation through OA-MLHS together with BCT is also discussed.Two yield estimation examples,a fourth-order OTA-C filter and a three-dimensional(3D) quadratic function are used for comparison of our method with Monte Carlo based methods including Latin hypercube sampling and importance sampling under several combinations of sample sizes and yield values.Extensive simulations show that our method is superior to other methods with respect to accuracy and efficiency under all of the given cases.Therefore,our method is more suitable for parametric yield optimization.     

摩托车典型道路载荷谱采集及分析

通过应变片的粘贴和测试系统的组建,在海南试验场耐久5号道上采集到了不同路面的载荷谱,并通过对其时域和频域的处理,统计了lx-200型摩托车某些测点在路面随机激励下的时域特征值,分析了在不同路面上摩托车的振动情况,并通过不同测点特征值的对比分析,得出该车具有较好的减震性;分析了响应能量随路面状况的变化规律、总结了各典型路面的激振频率。判断了各典型路面对摩托车舒适性的影响,为摩托车的总成、零部件的模拟试验及平顺性分析提供了重要的基础数据。