Proposal of Fault Diagnosis of Analog Circuits by Combining Operation-Region Model and X–Y Zoning Method: Case Study

We propose a method of diagnosing analog circuits that is achieved by combining an operation-region model and an X–Y zoning method. The X–Y zoning method can be used to detect faults in analog circuits by using the relationship between circuit inputs and outputs. The operation-region model can be used to analyze/model circuit behaviors by utilizing changes in the operation regions of MOS transistors in a circuit. Operation regions are obtained from transistor node voltages at sampling time corresponding to a particular excitation of the input value and the corresponding output value. Since we developed a data processing method to handle data discretely, we could implement a procedure for diagnosis based on the preset test, which is a method of diagnosing digital circuits. We demonstrated the effectiveness of our method by applying it to ITC’97 benchmark circuits with hard and soft faults. We found that the diagnostic resolution is one for every fault.     

大功率半导体激光器步进加速老化研究

介绍了半导体激光器寿命测试的理论依据,给出了由电流应力决定的寿命测试的数学模型,据此对AlGaInAs/AlGaAs/GaAs 808nm大功率半导体激光器进行常温电流步进加速老化实验。由步进加速老化的理论依据及数学模型推算出了步进加速寿命实验时间折算公式,利用步进加速寿命实验时间折算公式推算出了器件在额定应力条件下工作的寿命结果;根据实验后器件的失效模式分析,与恒定应力加速老化方式下的实验结果相对比分析,确认该步进加速实验方法可以适用于半导体激光器的加速老化。     

嵌入式智能云控制系统的原理与设计

云是用语言值表示的某个定性概念与其定量表示之间的不确定性转换模型.基于云模型的定性知识推理,以概念为基本表示,从数据库中挖掘出定性知识,构造规则发生器.多条定性规则构成规则库,当输入一个特定的条件激活多条定性规则时,通过推理引擎,实现带有不确定性的推理和控制.以往实现云控制器,主要依赖计算机及相关软件,限制了其进一步的推广应用.针对基于Quartus Ⅱ设计软件和Nios Ⅱ处理器的可编程片上系统进行设计开发,将云控制器在目标电路板的FPGA芯片中进行系统集成,实现以嵌入式云控制器为核心的智能控制系统,具有接口灵活、扩展性强、便于实现等优点.为基于云模型的智能控制系统的工业化应用,提供了硬件设计基础.     

云推理在雷达干扰效果评估中的应用

鉴于雷达干扰效果评估在干扰资源优化分配中的重要地位,一种基于云模型定性规则推理的干扰效果评估方法被提出。首先对属性云模型进行参数设置,生成了一系列用云表示的基本概念集;然后基于云不确定性关联知识挖掘方法,构建了推理规则库,使得属性间的内在关联被突显出来;最后建立了基于云不确定性推理的干扰效果评估模型。通过实例,将云推理与模糊推理和概率推理进行比较,结果表明所建模型是合理的、可行的,该方法摆脱了以往概念层次的硬划分,实现了数据的软操作,通过定性推理过程,对数据对象进行定性概念的推理,实现了更符合人类思维活动的推理过程,具有更好的可操作性和可理解性。     

Evaluation of effective stress times and stress levels from mission profiles for semiconductor reliability

Lifetime and duty cycles of automotive electronics are increasing, inducing new challenges to reliability predictions and testing. For qualification purposes, the automotive industry generates various time-dependent mission profiles with various stressors and varying stress levels according to different use cases.We present a theoretical model, describing the common approach, to reduce the stressors from time-dependent mission profiles to the two single parameters “effective stress level” and “effective stress time” for equivalent reliability testing. In a first step, the cumulative exposure (CE) model is shown to describe the future reliability behaviour after steplike stress level changes. Taking into account the individual characteristic lifetimes T₆₃ of the corresponding Weibull distributions, in a second step, an effective T₆₃ lifetime can be derived. For this calculation, periodic stress cycles are defined and transformed into an equivalent effective stress level. This procedure confirms the industry-wide used approach of dealing with effective stress levels for reliability testing.For the experimental validation metal-oxide-semiconductor (MOS) capacitors are fabricated and stressed by voltage and temperature. The received reliability data fit the theoretical predictions within the statistical variations.     

温度步进应力加速寿命试验研究

提出了一种温度步进威力加速寿命试验的方法,并分别基于阿伦尼斯模型、基本GM（1,1）模型、残差修正GM（1,1）模型对温度步进应力条件下特征寿命的点估计进行了讨论,最后用3种不同的方法对给出的实例进行了求解,说明了该方法在工程应用上的可行性和有效性。     

Accelerated life tests analyzed by a piecewise exponentialdistribution via generalized linear models

Efficient industrial experiments for the reliability analysis of manufactured products consist of subjecting the units to accelerated life tests where, for each pre-fixed stress level, the experiment ends after the failure of a certain pre-fixed proportion of units or a certain test time is reached. This paper estimates the mean life of the units under usual working conditions, based on censored data obtained from units under stress conditions. This problem is approached through a generalized linear model and related inferential techniques, considering the very flexible class of failure distributions, piecewise exponential model and a log-linear stress-response relationship. The general framework has as particular cases, among others, the power law model, the Arrhenius model and the generalized Eyring model. A numerical example illustrates the methodology     

The role of lead in growing Ga1−X InXAsYSb1−Y solid solutions by liquid-phase epitaxy

The electrical properties of Ga_1?X In_XAs_YSb_1?Y (X=0.14–0.27) solid solutions grown from a Pb-containing solution-melt were investigated for the first time. Three acceptor levels were found to exist, specifically, a shallow level with the activation energy E _A1≈0.008–0.015 eV, and two deep levels E _A2≈0.024–0.033 eV and E _A3≈0.07 eV. It is demonstrated that the use of Pb makes it possible to obtain undoped solid solutions with a low concentration of defects and impurities and with high carrier mobility.     

Adaptive robust motion control of SISO nonlinear systems with implementation on linear motors

For the purpose of controlling an X–Y table driven by linear motors with a high precision, an adaptive robust motion tracking control method is first introduced. The controller is developed based upon a class of SISO nonlinear systems whose nonlinear part can be linearly parameterized. The advantage of such a controller is that parametric uncertainties and unknown disturbances can be dealt with, which is essential for a high precision of the control of linear-motor-driven X–Y table. With the prior knowledge of the bounds of the system parameters, a discontinuous projection is utilized in the adaptive law to ensure the boundedness of the parameters estimates. The algorithm is then implemented on a real X–Y table driven by the linear motors. In the modeling of such a system, fiction effects are also considered, which is useful for the derivation of the adaptive law. Experiments on the X–Y table are carried out and the results show excellent tracking performance of the system.     

电网云测试服务平台的设计与应用

随着大数据、云计算等技术的快速发展以及在国内外企业的成功实践,如何引入云计算技术,对传统测试模式进行创新,实现传统软件测试模式向云测试模式的转换,成为企业对于软件质量保证的关键.针对云平台具备处理能力强、存储容量大、安全可靠、适度分散的能力,电网云测试服务平台将满足先进性、实用性、安全性等特点,采用“测试即服务”的应用模式,为企业提供内外部云测试服务.列举了移动测试在云平台上的应用,验证了电网云测试服务平台的可用性,并对平台的优势进行了简要分析.     

大数据典型相关分析的云模型方法

针对传统大数据典型相关分析（CCA, canonical correlation analysis）方法的高复杂度在面临大数据PB级数据规模时不再适应的现状,提出了一种基于云模型的大数据CCA方法。该方法在云计算架构的基础上,通过云运算将各端点云合并为中心云,并据此产生中心云滴,以中心云滴作为大数据的不确定性复原小样本,在其上施以CCA运算,中心云滴的较小数据量提高了运算效率。在真实数据集上的实验结果验证了该方法的有效性。     

Versatile analog squarer and multiplier free from body effect

This paper proposes the analog CMOS squarer and the four-quadrant analog CMOS multiplier. The major advantages of the proposed circuits are low voltage supply, multifunction of output, and insensitive to the threshold voltage variation caused by body effect. The versatile squarer has two inputs (V _in and I _in ). Its output can be the square of V _in or the square of I _in . The versatile four-quadrant multiplier has four inputs (V _X , I _X , V _Y , and I _Y ). Its output can be the product of V _X and V _Y , the product of I _X and I _Y , the product of V _X and I _Y , or the product of V _Y and I _X . Therefore, the proposed circuits can be applied more than conventional circuits and have good performance. Second-order effects and frequency response are analyzed. Simulation results have verified the workability of the circuits. Experimental results are done to confirm the operation of the circuits.     

Accelerated stress testing of a-Si:H pixel circuits for AMOLED displays

Electronics reliability testing is traditionally carried out by accelerating the failure mechanisms using high temperature and high stress, and then predicting the real-life performance with the Arrhenius model. Such methods have also been applied to organic light-emitting diode (OLED) testing to predict lifetimes of tens of thousands of hours. However, testing the active matrix OLED thin-film transistor (TFT) backplane is a unique and complex case where standard accelerated testing cannot be directly applied. This is because the failure mechanism of pixel circuits is governed by multiple material and device effects, which are compounded by the self-compensating nature of the circuits. In this paper, we define and characterize the factors affecting the primary failure mechanism and develop a general method for accelerated stress testing of TFT pixel circuits in a-Si AMOLED displays. The acceleration factors derived are based on high electrical and temperature stress, and can be used to significantly reduce the testing time required to guarantee a 30 000-h display backplane lifespan.     

An advanced area scaling approach for semiconductor burn-in

In semiconductor manufacturing, early life failures are avoided by putting the produced items under accelerated stress conditions before delivery. The products’ early life failure probability p is assessed by means of a burn-in study, in which a sample of the stressed items is investigated for early failures. The aim is to prove a target failure probability of the produced devices and release stress testing of the whole population. Given the failure probability level on a reference product, the failure probabilities of so-called follower products with different chip sizes are then obtained by means of area scaling. Classically, area scaling is done with respect to the whole area of the chips. Nevertheless, semiconductors can be partitioned into different chip subsets, which can have different likelihoods of failures. In this paper, we propose a novel area scaling model for the chip failure probability p, which enables us to scale the chip subsets separately from each other. The main idea is to adapt the classical estimators of the failure probabilities of the chip partitions according to the number of failures on the different chip subsets. This leads to a more appropriate estimation of the failure probabilities of the follower products and helps to improve the efficiency of burn-in testing.     

Particle swarm optimization based feedforward controller for a XY PZT positioning stage

Compensations for cross-axis coupling effect and hysteretic nonlinearity of a novel XY piezo-actuated positioning stage are presented in this study. The piezo-actuated stage utilizes a monolithic flexure-based mechanism (FBM) to achieve translations in X- and Y-axes instead of using stacked mechanisms. A hysteresis model with crossover term is proposed to alleviate the cross coupling effect between X- and Y-stages during precision positioning tasks. System identifications using real-coded genetic algorithm (RGA) and clonal selection algorithm (CSA) are compared with particle swarm optimization (PSO). The results show that PSO provides better performance than the others. Therefore, a feedforward controller with cross-axis coupling compensation is studied and the used for the piezo-actuated FBM to enhance the precision of the coarse positioning stage. The experimental results confirm that the proposed controller can achieve precision tracking tasks with submicron precision.     

Electronic and optical properties of AlAs/Al<Subscript>x</Subscript>Ga<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>As(110) superlattices

Electronic states in the conduction band of (AlAs)_M(Al_xGa_1?xAs)_N(110) superlattices are investigated for various M and N. It is shown that electronic properties of these structures are mainly determined by electrons of two pairs of valleys, namely, either Γ-X ^Z or X ^X –X ^Y . Calculations based on the developed model of joining the envelope functions were carried out. Miniband spectra, symmetry, and localization of wave functions, as well as probabilities of miniband-to-miniband infrared absorption, are determined and analyzed. It is shown that, in the case of the X ^X –X ^Y pair of valleys, the absorption probabilities are high not only for polarization of light along the growth axis of the superlattice but also for the normal incidence of an optical wave on the structure surface.     

Calibration algorithms for an electron beam metrology system

This paper discusses the general deflection system calibration problem that occurs in electron beam lithography and metrology systems.These systems generally have an X, Y stage whose position can be measured, but not set to a high degree of accuracy.The calibration problem involves aligning the coordinate system associated with electron beam deflection system to that of the X, Y stage, and measuring the deflection system sensitivity.Current commercially available examples of these systems include the Cambridge Instruments EBMF-6 electron beam lithography system and the EBMT-5 electron beam metrology system.     

云模型在灰色评估中的应用研究

针对灰色评估法中隶属函数难以确定的问题,引入云模型,简要推导了云模型的一些特性曲线,在此基础上将云模型应用到白化权函数中,采用云模型中概念生成的方法来生成基于云模型的评估灰类。通过对白化权值的大样本求均值的方法来计算评估系数,避免了较大误差的影响。将该评估方法应用到雷达模拟器中,证明了方法的可行性,为云理论的进一步应用提供了一种扩展的思路。     

Weibull accelerated life testing with unreported early failures

Situations arise in life testing where early failures go unreported, e.g. a technician believes an early failure is “his fault” or “premature” and must not be recorded. Consequently, the reported data come from a truncated distribution and the number of unreported early failures is unknown. Inferences are developed for a Weibull accelerated life-testing model in which transformed scale and shape parameters are expressed as linear combinations of functions of the environment (stress). Coefficients of these combinations are estimated by maximum likelihood methods which allow point, interval, and confidence bound estimates to be computed for such quantities of interest for a given stress level as the shape parameter, the scale parameter, a selected quantile, the reliability at a particular time, and the number of unreported early failures. The methodology allows lifetimes to be reported as exact, right censored, or interval-valued, and to be subject optionally to testing protocols which establish thresholds below which lifetimes go unreported. A broad spectrum of applicability is anticipated by virtue of the substantial generality accommodated in both stress modeling and data type     

Analysis of Hot Topics in Cloud Computing

In the field of cloud computing, topics such as computing resource virtualization, differences between grid and cloud computing, relationship between high-performance computers and cloud computing centers, and cloud security and standards have attracted much research interest. This paper analyzes these topics and highlights that resource virtualization allows information services to be scalable, intensive, and specialized; grid computing involves using many computers for large-scale computing tasks, while cloud computing uses one platform for multiple services; high-performance computers may not be suitable for a cloud computing; security in cloud computing focuses on trust management between service suppliers and users; and based on the existing standards,standardization of cloud computing should focus on interoperability between services.