Field Programmable Analog Arrays for Conditioning Ultrasonic Sensors

This paper proposes the use of field programmable analog arrays (FPAAs) as adaptive conditioning blocks for ultrasonic sensors. The uncertainty achievable through this technique, in fact, results very sensitive to the measurement conditions, due to the attenuation affecting the echo during its propagation. Indeed, FPAAs emulate analog circuits whose characteristics have to be dynamically tuned according to different operating conditions. Actually, the signal provided by the ultrasonic sensor is properly processed in order to improve the overall measurement accuracy. In this paper, the prototype of a distance meter based on time-of-flight (TOF) measurement is presented in order to evidence the advantages gained by FPAA features in processing the sensor output to compensate echo attenuation and distortion versus target distance. The prototype working is supervised by a digital signal controller (DSC) whose tasks are: 1) driving the ultrasonic transducer; 2) performing the echo acquisition; 3) tuning on the fly the FPAA features; 4) evaluating the TOF; 5) measuring the target distance; and 6) delivering the final result to the end user. This paper is completed by the results achieved in a number of experimental tests allowing interesting considerations to be drawn. In particular, the experiments confirm the prototype reliability and effectiveness also with ultrasonic echoes characterized by very low signal-to-noise ratios.     

Derivation of the internal coupling relations of an analog circuits via sensitivity approach

Abstract

A method of specifying the internal coupling relation of components in a circuit is presented. This coupling relation is very useful for improving the efficiency of on‐line fault simulation when a self‐testing approach is adopted. The proposed method is based on the concept of sensitivity. In fact, the coupling relation problem ends up with a sensitivity analysis of a given pseudo circuit. The coupling relation is studied on the component level. The component we treated here may be a two‐terminal component, a multiple‐terminal component, a subcircuit module or an ^TC chip.     

基于K-means聚类与概率神经网络的模拟电路故障诊断方法

模拟电路已广泛应用于航空电子系统,模拟电路的失效会影响系统的功能,引起系统故障,甚至引发灾难性的安全事故。为快速准确地实现模拟电路的故障诊断,该文引入概率神经网络方法,并针对传统概率神经网络方法中的诊断准确性、诊断效率问题,提出基于K-means与概率神经网络的模拟电路故障诊断方法,定义聚类有效性指标,采用K-means聚类分析与有效性指标分析相结合的方式,选取聚类中心作为模式层神经元训练概率神经网络模型,从而降低模型的复杂程度,大大减少故障诊断时间。最后,以有源滤波电路为对象,通过与传统概率神经网络方法以及随机概率神经网络方法的对比分析,验证该文方法在故障诊断准确性以及故障诊断效率上的优越性能。     

Testing Analog and Mixed-Signal Circuits With Built-In Hardware—A New Approach

This paper aims to develop an approach to test analog and mixed-signal embedded-core-based system-on-chips (SOCs) with built-in hardware. In particular, oscillation-based built-in self-test (OBIST) methodology for testing analog components in mixed-signal circuits is implemented in this paper. The proposed OBIST structure is utilized for on-chip generation of oscillatory responses corresponding to the analog-circuit components. A major advantage of the OBIST method is that it does not require stimulus generators or complex response analyzers, which makes it suitable for testing analog circuits in mixed-signal SOC environments. Extensive simulation results on sample analog and mixed-signal benchmark circuits and other circuits described by netlist in HSPICE format are provided to demonstrate the feasibility, usefulness, and relevance of the proposed implementations     

Oscillation-test methodology for low-cost testing of active analogfilters

The oscillation-test strategy is a low cost and robust test method for mixed-signal integrated circuits. Being a vectorless test method, it allows one to eliminate the analog test vector generator. Furthermore, as the oscillation frequency is considered to be digital, it can be precisely analyzed using pure digital circuitry and can be easily interfaced to test techniques dedicated to the digital part of the circuit under test (CUT). This paper describes the design for testability (DFT) of active analog filters based on oscillation-test methodology. Active filters are transformed to oscillators using very simple techniques. The tolerance band of the oscillation frequency is determined by a Monte Carlo analysis taking into account the nominal tolerance of all circuit under test components. Discrete practical realizations and extensive simulations based on CMOS 1.2 μm technology parameters affirm that the test technique presented for active analog filters ensures high fault coverage and requires a negligible area overhead. Finally, the DFT techniques investigated are very suitable for automatic testable filter synthesis and can be easily integrated in the tools dedicated to automatic filter design     

Validation of reliability computational models using Bayes networks

This paper proposes a methodology based on Bayesian statistics to assess the validity of reliability computational models when full-scale testing is not possible. Sub-module validation results are used to derive a validation measure for the overall reliability estimate. Bayes networks are used for the propagation and updating of validation information from the sub-modules to the overall model prediction. The methodology includes uncertainty in the experimental measurement, and the posterior and prior distributions of the model output are used to compute a validation metric based on Bayesian hypothesis testing. Validation of a reliability prediction model for an engine blade under high-cycle fatigue is illustrated using the proposed methodology.     

Ambiguity groups and testability

An efficient method has been developed for determining component ambiguity groups which arise in analog circuit testing. The method makes use of the sensitivity model of the circuit. The ambiguity groupings are shown to depend on the test points selected and the measurement accuracy and are therefore a useful tool for determining where to add or delete test points. The concept of ambiguity groups can be used to refine the testability measure of a circuit. An example that demonstrates the effects of ambiguity groups on parameter estimation and performance prediction is presented     

Analog system-level fault diagnosis based on a symbolic method inthe frequency domain

Concurrently, a symbolic approach for analog system-level fault. Diagnosis and a systematic approach to maximize the fault location capability are proposed. This unified approach is realized as a result of combining the simulation before test (SBT) fault dictionary diagnosis method with a symbolic approach. The traditional SBT fault dictionary method is often costly aid inefficient because of a high number of simulations, but it can become very efficient when a symbolic approach is employed. This symbolic approach only requires one analysis for circuit topology to generate the network transfer function and a parameter substitution to obtain the frequency response (or time response) of the system. An efficient program is developed to deal with the frequency responses of the system to provide the optimum testing point set, and to automatically generate the fault dictionary. The “distance” between the measurement data and the frequency responses from the fault dictionary is evaluated to determine the diagnosis results. A practical example is presented in order to illustrate the main features of this proposed analog system fault diagnosis approach     

Defining an accurate MFS solution for 2.5D acoustic and elastic wave propagation

This paper proposes a simple methodology to assess the accuracy of the method of fundamental solutions (MFS) when applied to 2.5D acoustic and elastic wave propagation. The proposed technique is developed in the frequency domain. It copes with the precision uncertainty difficulty presented by the MFS solution through its dependency on the number and position of virtual sources and collocation points.The methodology relies on the correlation between the errors registered along surfaces, where boundary or continuity conditions are known a priori, with those obtained along the system domain. Circular cylindrical domains are modeled to illustrate the efficiency of the proposed methodology, since in this case analytical solutions are available.A numerical example is used to illustrate the application of the methodology to a more complex case. An elastic column exhibiting an embedded curved crack, with null thickness, is used to illustrate the applicability of the proposed technique. Since, there are no known analytical solutions; the results provided by the traction boundary element method (TBEM) are used as reference solutions.     

A methodology for cellular manufacturing design

A two-phase methodology is presented as an aid to organizing job shop production in a cellular manufacturing system. The first phase (selection/assignment phase) selects the machines to be kept on the shop floor and assigns parts to the machines retained. The second phase (partition/reassignment phase) establishes a partition of the set of parts and corresponding cells of machines and reassigns some of the operations with a view to eliminating some intercell material movements. This phase is repeated until a partition meeting the operator's requirements is obtained. The results obtained with this method on several examples found in the literature are consistently equivalent to or even better than those hitherto proposed, in terms of intercell moves.     

力传感器的动态重复性,线性度与性能改进的研究

提出了传感器的动态重复性与动态线性度的计算方法，介绍了用有源模拟滤波器改善力传感器动态性能的方法，包括力传感器动态数学模型、动态补偿模拟滤波的设计方法、力传感器动态模拟器及其电路、滤波器的电路、动态性能改善的实验结果。     

A complete scheme of built-in self-tests (BIST) structure for faultdiagnosis in analog circuits and systems

The implementation of BIST in analog circuits is investigated, and a complete BIST scheme is proposed. This scheme can be included in any analog or mixed analog-digital circuit and can check its responses by following selected testing procedures. A CMOS chip supporting the proposed BIST structure is designed to facilitate the application of the scheme in a variety of analog circuits. Results from the application of the BIST scheme on active circuits are given, showing its effectiveness and its convenience     

Load behaviour prediction under blackout conditions using a fuzzy expert system

This paper proposes a method to forecast load behaviour during restoration of power systems after total or partial blackouts. Load behaviour after blackouts can be anomalous and differ significantly from that during normal operation conditions. A heuristic top-down approach was adopted to develop the forecasting method, using an expert system based on linguistic variables and fuzzy logic rules as its central core. The approach addresses the main aspects of load behaviour during re-energisation and is capable of representing physical phenomena. The proposed methodology was tested with data from real electrical power substations and these test results are presented     

Dual Experimental Approach for Thermal Impacts on Electromagnetic Behavior of Electronic Circuit Board Configurations

Some effects of physical parameters, such as temperature, on electromagnetic emission or susceptibility of electronic circuit boards are nonnegligible and can be enforced by new integrated complex electronic structures. This paper describes experimental improvements proposed on near-field and radiated-mode test setups, including the temperature parameter. New experimental investigations and methodology are driven to estimate the real external thermal impacts on electromagnetic behavior and compliance. With pertinent characterization results, a review of wideband frequency modifications of electromagnetic compatibility (EMC) responses on electronic configurations with active digital devices and a printed circuit board (PCB) wire network is presented and analyzed.     

Software reliability analysis for safety-critical and control systems

The transition from analog to digital safety-critical instrumentation and control (I&C) systems has introduced new challenges for software experts to deliver increased software reliability. Since the 1970s, researchers are continuing to propose software reliability models for reliability estimation of software. However, these approaches rely on the failure history for the assessment of reliability. Due to insufficient failure data, these models fail to predict the reliability of safety critical systems. This paper utilizes the Bayesian update methodology and proposes a framework for the reliability assessment of the safety-critical systems (SCSs). The proposed methodology is validated using experiments performed on real data of 12 safety-critical control systems of nuclear power plants.     

Characteristic analysis and design of a B14 rotary ultrasonic motor for a robot arm taking the contact mechanism into consideration.

The ultrasonic motor (USM) has many merits for use in a robot arm application. Therefore, the disk-type traveling wave B14 rotary ultrasonic motor (RUSM) is proposed in this paper for that application. Up to the present time, the analysis and design of the USM have been almost always performed using rough analytic methods or using commercial analysis tools. As a result, it was impossible to achieve an exact analysis and design of the USM. In order to address this problem, this paper proposes the analysis and design methodology of the B14 RUSM using a numerical method (3-D FEM) combined with an analytic method taking the contact mechanism into consideration in a linear operation. This methodology is applicable to many other kinds of USMs that use similar mechanisms. In addition, the mechanical system and the driving circuit of the B14 RUSM are designed and prototyped. Finally, the proposed analysis and design methodology is validated by comparing its outcomes with the experimental data. Also, the appropriateness of the suggested RUSM for the application of a robot arm was verified.     

Characteristic analysis and design of a B14 rotary ultrasonic motor for a robot arm taking the contact mechanism into consideration

The ultrasonic motor (USM) has many merits for use in a robot arm application. Therefore, the disk-type traveling wave B₁₄ rotary ultrasonic motor (RUSM) is proposed in this paper for that application. Up to the present time, the analysis and design of the USM have been almost always performed using rough analytic methods or using commercial analysis tools. As a result, it was impossible to achieve an exact analysis and design of the USM. In order to address this problem, this paper proposes the analysis and design methodology of the B₁₄ RUSM using a numerical method (3-D FEM) combined with an analytic method taking the contact mechanism into consideration in a linear operation. This methodology is applicable to many other kinds of USMs that use similar mechanisms. In addition, the mechanical system and the driving circuit of the B₁₄ RUSM are designed and prototyped. Finally, the proposed analysis and design methodology is validated by comparing its outcomes with the experimental data. Also, the appropriateness of the suggested RUSM for the application of a robot arm was verified     

Fast-response power factor detector

In this paper, a new power factor measurement method is proposed. The proposed method is implemented by an analog electronic circuit. Its response time is less than a half-cycle. The test results show that it can measure the power factor of the measured load quickly and accurately, and its response time is superior to the conventional power factor measurement methods     

Methodology of virtual instrument time analysis

This paper proposes a new approach to the virtual instrument (VI) time analysis. The main assumptions and issues are presented. A methodology of the VI time parameter assessment and measurement is proposed. The verification of the methodology is discussed. The premises for future research are outlined.