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.     

IGBT寿命评估中解析预测模型综述

对近几年国内外的绝缘栅双极型晶体管(IGBT)可靠性研究中的寿命预测解析模型进行了分析。将其分为两类:基于结温的IGBT寿命预测模型和基于多变量的IGBT寿命预测模型,主要包括Conffin-Manson模型、Lesit模型、Norris-Landzberg模型和Bayerer模型。分析和讨论了这几种寿命预测模型,总结了相应模型的优缺点及构建方法,提出了其发展趋势和方向。     

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.     

光纤的筛选试验和寿命估算

本文讨论了长光纤的机械可靠性。简略介绍了两种光纤强度筛选的基准筛选试验设备及其方法,并从理论上分析了筛选试验后的光纤强度。最后,对筛选试验后的光纤寿命进行了估算,给出了光纤经三个等级的筛选应变后的寿命设计图。     

Session-Key Generation Using Human Passwords Only

We present session-key generation protocols in a model where the legitimate parties share only a human-memorizable password, and there is no additional set-up assumption in the network. Our protocol is proven secure under the assumption that enhanced trapdoor permutations exist. The security guarantee holds with respect to probabilistic polynomial-time adversaries that control the communication channel (between the parties), and may omit, insert, and modify messages at their choice. Loosely speaking, the effect of such an adversary that attacks an execution of our protocol is comparable with an attack in which an adversary is only allowed to make a constant number of queries of the form "is w the password of Party A." We stress that the result holds also in case the passwords are selected at random from a small dictionary so that it is feasible (for the adversary) to scan the entire directory. We note that prior to our result, it was not known whether or not such protocols were attainable without the use of random oracles or additional set-up assumptions.     

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.     

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...     

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。     

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...     

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.     

Estimation of Soil Moisture and Faraday Rotation From Bare Surfaces Using Compact Polarimetry

The potential of compact polarimetry (CP) mode at longer wavelengths in a space environment for surface parameter estimation is investigated. CP consists of transmitting a single polarization while receiving two polarizations. At longer wavelengths, one of the main challenges associated with CP from space is Faraday rotation (FR) estimation and correction. In this paper, an estimation procedure for FR is presented, which relies on the scattering properties of bare surfaces. The selection of the bare surfaces is based on a new parameter, the conformity coefficient computed from CP measurements. This parameter is shown to be FR invariant. Once estimated, the FR can be corrected over the whole image. A simple approximation to $sigma_{ rm HH}^{rm o}$ and $sigma_{rm VV}^{rm o}$ based on CP measurements over bare soil surfaces is presented, from which soil moisture can be estimated using the 1995 Dubois algorithm. The results obtained using CP are shown to be in good agreement with those obtained from the standard Dubois algorithm using fully polarimetric data. This implies that, for soil moisture, CP can be used instead of HH and VV dual-polarized measurements.      

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.