Lifetime Estimation of Wireless Body Area Sensor Networks Using Probabilistic Analysis

A framework is proposed for estimating the lifetime of wireless body area sensor network (WBASN) using probabilistic analysis and Monte Carlo simulation. WBASN implements real-time health monitoring by outfitting patients with wireless, wearable vital sign sensors. In health monitoring, the loss of critical or emergency information is a serious issue so there is a need to ensure quality of service. It is important to have an estimate of the lifetime of the network in order to replace or recharge the batteries because the loss of critical data is not acceptable. The lifetime of the WBASN is defined as the duration of time until the first node fails due to battery depletion. Heart rate and blood glucose are monitored at a central location in a managed health care environment for this evaluation of WBASN performance. A parametric model of a health monitoring network (HMN) is created with sets of random input distributions. Probabilistic analysis is used to determine the timing and distribution of node failure in the HMN.     

Customer-Rush Near Warranty Expiration Limit, and Nonparametric Hazard Rate Estimation From Known Mileage Accumulation Rates

Time or mileage data obtained from warranty claims are generally more accurate for hard failures than for soft failures. For soft failures, automobile users sometimes delay reporting the warranty claim until the warranty coverage is about to expire. This results in an unusually high number of warranty claims near the end of warranty coverage. Because such a phenomenon of customer-rush near the warranty expiration limit occurs due to user behavior rather than due to the vehicle design, it creates a bias in the warranty dataset. Design improvement activities that use field reliability studies based on such data can potentially obtain a distorted picture of the reality, and lead to unwarranted, costly design changes. Research in the area of field reliability studies using warranty data provides several methods for warranty claims resulting from hard failures, and assumes reported time or mileage as actual time or mileage at failure. In this article, the phenomenon of customer-rush near the warranty expiration limit is addressed for arriving at nonparametric hazard rate estimates. The proposed methodology involves situations where estimates of mileage accumulation rates in the vehicle population are available. The claims influenced by soft failures are treated as left-censored, and are identified using information in technician comments about the repair carried out plus, if required, a more involved engineering analysis of field returned parts. Maximum likelihood estimates for the hazard function and their confidence limits are then obtained using Turnbull's iterative procedure. An application example illustrates use of the proposed methodology.     

Optimal Utilization and Effects of Inaccurate Estimation in Mobile Database Failure Restoration

Mobility databases such as home location register and visitor location register are adopted to support mobility management in personal communications services networks. If a visitor location register fails or crashes, the subscribers' services will be seriously degraded due to the loss or corruption of location information. In this paper, we optimize utilization of demand re-registration messages for an adaptive p-persistent backoff database failure restoration scheme. An analytical model is developed and validated with simulations to obtain the optimal utilization using appropriate parameters so that the failed visitor location register is restored with the fastest speed. Some interesting aspects on the performance are studied and their deep insights are observed, such as effects of message sizes on choices of system parameters, effects of the inaccurate estimated number of stations, etc. One observation is that optimizations of utilization and successful transmission probability are two different goals, and a value to achieve the optimal successful transmission probability does not necessarily ensure optimal utilization. Furthermore, we also propose a scheme how to handle the problem with inaccurate (estimated) number of stations.     

Estimation of Respiratory Rate From Photoplethysmogram Data Using Time–Frequency Spectral Estimation

We present a new method that uses the pulse oximeter signal to estimate the respiratory rate. The method uses a recently developed time-frequency spectral estimation method, variable-frequency complex demodulation (VFCDM), to identify frequency modulation (FM) of the photoplethysmogram waveform. This FM has a measurable periodicity, which provides an estimate of the respiration period. We compared the performance of VFCDM to the continuous wavelet transform (CWT) and autoregressive (AR) model approaches. The CWT method also utilizes the respiratory sinus arrhythmia effect as represented by either FM or AM to estimate respiratory rates. Both CWT and AR model methods have been previously shown to provide reasonably good estimates of breathing rates that are in the normal range (12-26 breaths/min). However, to our knowledge, breathing rates higher than 26 breaths/min and the real-time performance of these algorithms are yet to be tested. Our analysis based on 15 healthy subjects reveals that the VFCDM method provides the best results in terms of accuracy (smaller median error), consistency (smaller interquartile range of the median value), and computational efficiency (less than 0.3 s on 1 min of data using a MATLAB implementation) to extract breathing rates that varied from 12-36 breaths/min.     

Surface Reflectance Estimation Using Prior Spatial and Spectral Information

Surface prior-information reflectance estimation (SPIRE) algorithms estimate changes in spectral reflectance using imperfect prior spatial and spectral information. This paper combines spectral and spatial processing to estimate local changes in spectral reflectance between pairs of spectral images under spatially and spectrally varying multiplicative and additive noise, which arise from variations in illumination and atmospheric effects. This approach extends the spatial SPIRE algorithms that were described earlier and utilizes only a prior reflectance image cube and ensembles of typical multiplicative and additive illumination noise spectral vectors that are deduced from images cubes of similar scenes. The method minimizes the impact of environmental noise by replacing with their prior equivalents low-spatial-frequency content and low-order principal components that are known to be noisy based on prior noise spectra. This filtering and substitution process occurs in log space when minimizing the effects of multiplicative noise. Tests on Hyperspectral Digital Imagery Collection Experiment visible near-infrared-shortwave infrared data demonstrated the algorithm's superior ability to estimate absolute reflectance changes under varying illumination conditions. SPIRE performance was nearly identical to the empirical line method (ELM) ground-truth-based atmospheric compensation results and was better than the physics-based Atmospheric removal (ATREM) code overall, particularly, under high clouds and haze. A ldquoSelective SPIRErdquo technique that chooses between combined-spatial/spectral and spectral-only SPIRE reflectance estimates was developed; it maximizes estimation performance on both changed and unchanged pixels. Minimum-distance classification experiments demonstrated Selective SPIRE's superior performance relative to both ATREM and ELM in cross-image supervised classification applications.     

基于GIS的可跨场景人群密度估计方法

Crowd density is an important factor of crowd stability. Previous crowd density estimation methods are highly dependent on the specific video scene. This paper presented a video scene invariant crowd density estimation method using Geographic Information Systems （GIS） to monitor crowd size for large areas. The proposed method mapped crowd images to GIS. Then we can estimate crowd density for each camera in GIS using an estimation model obtained by one camera. Test results show that one model obtained by one camera in GIS can be adaptively applied to other cameras in outdoor video scenes. A real-time monitoring system for crowd size in large areas based on scene invariant model has been successfully used in ＇Jiangsu Qinhuai Lantern Festival, 2012＇. It can provide early warning information and scientific basis for safety and security decision making.     

An Accurate Estimation Algorithm for Failure Probability of Logic Circuits Using Correlation Separation

Journal of Electronic Testing - As the feature size of integrated circuits decreases to the nanometer scale, process fluctuations, aging effects, and particle radiation have an increasing influence...     

Warranty Periods Based on Three Ordered Sample Observations From a Weibull Population

Further investigation is made of the method derived in [7] for calculating, from Weibull failure data, warranty periods for lots to be manufactured in the future. A tabulation is given of warranty periods associated with lots of size n, n = 10, 11,..., 25, for failure data obtained from samples of size m, m = 2, 3,..., n - 3. The specified assurance level is 0.95.     

电子产品平均寿命的区间估计法

利用随机变量函数的分布,研究并证明了电子产品平均寿命的区间估计方法,并从置信区间的本质意义出发．通过极值理论给出了电子产品平均寿命的最小区间的估计方法。最后,用实例说明这种最小区间估计方法比传统方法更具优越性。     

Lifetime Estimation and Measurement for Wireless Ad Hoc Networks

Wireless Personal Communications - Mobile ad-hoc networks (MANET) is a popular choice for “wireless communication network” due to ease of deployment. Nodes in MANET are battery...     

阀控式密封铅酸蓄电池的寿命及失效分析

介绍了各种影响阀控式密封铅酸蓄电池寿命及容量的因素,分析了其失效的原因,并相应的对电池的维护提出了一些建议。     

DC/DC模块中功率器件的寿命预计方法

模拟开关电源DC/DC模块内部电路为开关电源中的功率器件—垂直导电双扩散MOS(VDMOS)和肖特基二极管(SBD)—提供恒定电应力,并对其施加温度应力进行加速寿命试验。采用恒定电应力温度斜坡法(CETRM),对开关电源中功率器件VDMOS和SBD的可靠性进行评价;对其失效机理一致性进行分析,计算其失效激活能;并在失效机理一致的范围内外推正常使用条件下的寿命,为开关电源整体可靠性评价提供依据。     

Estimation of the Phonetic Speech Quality Using the Information Theoretic Approach

The problem of estimation of the speech phonetic quality using a short fragment of the voice signal is formulated. The Kullback–Leibler minimum information discrimination principle is used to propose a novel criterion and develop an algorithm. The dynamic properties of the algorithm are analyzed. The algorithm is employed in the analysis of the functional state of speaker using the voice signal. It is demonstrated that the needed duration of the voice signal is several minutes only.     

Remote Estimation of Crop Chlorophyll Content Using Spectral Indices Derived From Hyperspectral Data

This paper examines the use of simulated and measured canopy reflectance for chlorophyll estimation over crop canopies. Field spectral measurements were collected over corn and wheat canopies in different intensive field campaigns organized during the growing seasons of 2004 and 2005. They were used to test and evaluate several combined indices for chlorophyll determination using hyperspectral imagery (Compact Airborne Spectrographic Imager). Several index combinations were investigated using both PROSPECT-SAILH canopy simulated spectra and field-measured reflectances. The relationships between leaf chlorophyll content and combined optical indices have shown similar trends for both PROSPECT-SAILH simulated data and ground-measured data sets, which indicates that both spectral measurements and radiative transfer models hold comparable potential for the quantitative retrieval of crop foliar pigments. The data set used has shown that crop type had a clear influence on the establishment of predictive equations as well as on their validation. In addition to generating different predictive equations, corn and wheat data yielded contrasting agreement between estimated and measured chlorophyll contents even for the same predictive algorithm. Among the set of indices tested in this paper, index combinations like modified chlorophyll absorption ratio index/optimized soil-adjusted vegetation index (OSAVI), triangular chlorophyll index/OSAVI, moderate resolution imaging spectrometer terrestrial chlorophyll index/improved soil-adjusted vegetation index (MSAVI), and red-edge model/MSAVI seem to be relatively consistent and more stable as estimators of crop chlorophyll content.     

Network Lifetime Maximization for Estimation in Multihop Wireless Sensor Networks

We consider the distributed estimation by a network consisting of a fusion center and a set of sensor nodes, where the goal is to maximize the network lifetime, defined as the estimation task cycles accomplished before the network becomes nonfunctional. In energy-limited wireless sensor networks, both local quantization and multihop transmission are essential to save transmission energy and thus prolong the network lifetime. The network lifetime optimization problem includes three components: i) optimizing source coding at each sensor node, ii) optimizing source throughput of each sensor node, and iii) optimizing multihop routing path. Fortunately, source coding optimization can be decoupled from source throughput and multihop routing path optimization, and is solved by introducing a concept of equivalent 1-bit MSE function. Based on the optimal source coding, the source throughput and multihop routing path optimization is formulated as a linear programming (LP) problem, which suggests a new notion of character-based routing. The proposed algorithm is optimal and the simulation results show that a significant gain is achieved by the proposed algorithm compared with heuristic methods.     

Estimation of Periodically Changing Failure Rate

This paper considers two life testing procedures (progressively censored samples and Bartholomew's experiment) under the assumption that the life of an item follows the exponential distribution. The failure rates are different under n different conditions of usage of the item at regular intervals of time. The maximum likelihood estimates of the n failure rates have been derived along with their asymptotic variances for both types of data (when failure times are recorded and when only the number of items failing in each interval are recorded). A numerical example illustrates the type of data and relevant calculations for the experiment involving progressively censored samples.     

ASP技术访问WEB数据库

ASP(ActiveServerPage)编写前台动态网页 ,它采用封装对象 ,程序调用对象的技术 ,简化编程 ,加强程序间合作。ASP访问后台WEB数据库 ,通过MDAC组件中包含一组称为ActiveXDataObject(ADO)的对象 ,他们对于查看不同平台上的各种数据 (数据库、表单、文本文件 )是必不可少的。     

WhatIs - Technology Information Database

WhatIs - Technology Information Database is a website is designed to provide a search base and a compilation of source material for a wide range of technological information. In this article some examples of the information you can obtain from this website are presented     

数据库规模估算数学模型研究

数据库规模估算是软件规模估算的基础.定义了数据库规模是综合指标的概念,运用文字叙述、表格及图形等方法分析了表类型、表结构、表元组、存储过程等因素对数据库规模的影响,设计了数据库规模估算的数学模型,并对模型中的各个参数进行了详细解释,指出了在软件生命周期前、后阶段进行估算的方法.     

Local Polynomial Fitting in Failure Rate Estimation

The failure rate function is one of the most important functions in reliability analysis as it addresses concepts such as scheduling, maintenance, improved system design, cost analysis, etc. Kernel-based estimation of the failure rate function imposes minimal assumptions on the data, and thus offers large flexibility. Therefore, it is very helpful in reliability analysis where the shape of the failure function is a primary target. However, standard kernel estimates are biased more than usual in the endpoints. Motivated by the advantages that the local linear fitting method provides for estimation of densities near the boundary, we employ the technique to the failure rate setting. We show that it produces estimators that have the same amount of boundary bias as in areas outside the boundary. The mean square error properties of the method are demonstrated, and a practically useful procedure for automatic smoothing parameter selection is developed, and studied both theoretically, and by simulations. The result is displayed graphically by distributional, and real life data.