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Instrumentation and Measurement, IEEE Transactions on

Issue 8 • Date Aug. 2012

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Displaying Results 1 - 25 of 35
  • Table of contents

    Page(s): C1 - 2077
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  • IEEE Transactions on Instrumentation and Measurement publication information

    Page(s): C2
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  • Editorial [Special section on measurement fundamentals]

    Page(s): 2078
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  • Analysis of Key Comparisons Incorporating Knowledge About Bias

    Page(s): 2079 - 2084
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (165 KB) |  | HTML iconHTML  

    A method is proposed for analyzing key comparison data. It is based on the assumption that each laboratory participating in the comparison exercise obtains independent and consistent estimates of the measurand and that, in addition, each laboratory provides an estimate of the quantity that collects all systematic effects that the laboratory took into account. The unknown value of the latter quantity, subtracted from its estimate, is defined as the laboratory's bias. The uncertainties associated with the estimates of the measurand and with the vanishing biases' estimates are also assumed to be reported. In this paper, we show that the information provided in this way may be of help for judging the performances of the laboratories in their correction of systematic effects. This is done by developing formulas for the final (consensus) estimates and uncertainties of the measurand and of the biases. Formulas for the final estimates and uncertainties of the pairwise differences between the biases are also developed. An example involving simulated key comparison data makes apparent the benefits of the proposed approach. View full abstract»

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  • A Simple Nonparametric Preprocessing Technique to Correct for Nonstationary Effects in Measured Data

    Page(s): 2085 - 2094
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    The general approach for modeling systems assumes that the measured signals are (weakly) stationary, i.e., the power spectrum is time invariant. However, the stationarity assumption is violated when: 1) transient effects due to experimental conditions are dominant; 2) data are missing due to, for instance, sensor failure; or 3) the amplitude of the excitation signals smoothly varies over time due to, for instance, actuator problems. Although different methods exist to deal with each of these nonstationary effects specifically, no unified approach is available. In this paper, a new and general technique is presented to handle nonstationary effects, based on processing overlapping subrecords of the measured data. The proposed method is a simple preprocessing step where the user does not need to specify which nonstationary effect is present, nor the time interval where the nonstationary effect appears. The merits of the proposed approach are demonstrated on an operational wireless system suffering from interrupted link effects. View full abstract»

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  • Toward an Interdisciplinary Probabilistic Theory of Measurement

    Page(s): 2095 - 2106
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB) |  | HTML iconHTML  

    Measurement plays a key role in science and technology in which it is a privileged way of gathering information from the real world and of validating scientific models. Is it possible to achieve a unified measurement theory for the different disciplines, ranging from physics to psychology, in which it is involved? A basic kernel for such a theory is surveyed and discussed. A probabilistic approach is followed in order to consider uncertainty as an inherent feature. View full abstract»

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  • Measurement Fundamentals: A Pragmatic View

    Page(s): 2107 - 2115
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    Measurements are more and more required in an increasing variety of human activities to acquire reliable information useful for effectively supporting decision-making processes. Furthermore, the entities whose properties are to be measured and the measuring systems are becoming increasingly complex, hardly to be modeled and managed. In this rapidly evolving scenario, several issues concerning the fundamentals of measurement science and technology arise. The purpose of this paper is to discuss some aspects of the crucial question about which evaluation processes can be considered measurements. Rather than focusing on formal conditions or technological constraints, we propose a pragmatic characterization of measurement, under the assumption that a better comprehension of the concept can be achieved by identifying and discussing the basic features which justify the reliability attributed to measurement results. With such an interdisciplinary approach, this work aims at promoting a broad discussion among interested researchers, even working in different scientific disciplines, so to increase the synergies among different research areas and to improve the body of knowledge about measurement fundamentals. View full abstract»

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  • Measurement Uncertainty: Literature Review and Research Trends

    Page(s): 2116 - 2124
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    This paper reviews and analyzes studies concerning measurement uncertainty, examining 114 papers published between 2004 and 2010 in the following international journals: IEEE Transactions on Instrumentation and Measurement, Measurement, Flow Measurement and Instrumentation, and Precision Engineering. The papers were classified according to six different approaches identified during the research and six different methods of calculating uncertainty used by the authors of the researched articles. This paper provides a short summary of the state of the art of measurement uncertainty, analyzes the research scenario on the theme, and, finally, brings suggestions on future work based on the analysis. View full abstract»

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  • Measurements for the Future—A Complete SI From Physical Constants

    Page(s): 2125 - 2131
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    Basing the SI units entirely on the values of fundamental physical constants involves extremely difficult metrology. It is desirable that the reproducibilities of a newly defined kilogram and of a thermodynamic temperature scale are at least equal to those of the present artifact kilogram and the water triple-point temperature. This paper discusses the benefits of an updated SI, the principal difficulties in attaining it, and why the effort expended is justified. View full abstract»

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  • Detecting a Time-Varying Behavior in Frequency Response Function Measurements

    Page(s): 2132 - 2143
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    This paper provides data-driven tools to detect and quantify approximately the influence of the time variation of a system under test in classical frequency response function (FRF) measurements. To achieve this, the best linear time-invariant approximation of a linear time-varying system is defined and is estimated using existing FRF estimators. An analysis of the residuals of the latter estimation reveals the frequency band in which the contributions from the time variation dominates the disturbing measurement noise and, thus, is significant. All concepts are illustrated on a simulation and real measurement examples. View full abstract»

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  • Measurement, Models, and Uncertainty

    Page(s): 2144 - 2152
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    Against the tradition, which has considered measurement able to produce pure data on physical systems, the unavoidable role played by the modeling activity in measurement is increasingly acknowledged, particularly with respect to the evaluation of measurement uncertainty. This paper characterizes measurement as a knowledge-based process and proposes a framework to understand the function of models in measurement and to systematically analyze their influence in the production of measurement results and their interpretation. To this aim, a general model of measurement is sketched, which gives the context to highlight the unavoidable, although sometimes implicit, presence of models in measurement and, finally, to propose some remarks on the relations between models and measurement uncertainty, complementarily classified as due to the idealization implied in the models and their realization in the experimental setup. View full abstract»

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  • From Errors to Probability Density Functions. Evolution of the Concept of Measurement Uncertainty

    Page(s): 2153 - 2159
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    The concept of uncertainty in measurement stems from that of (probable) error and is intimately intertwined with it. Both concepts can be viewed as measures of the quality of a measurement or, better, of the corresponding estimate. There is an endless list of misunderstandings, false beliefs, and misinterpretations on this subject. People tend also to use the same word with different meanings. In this paper, while giving an overview of the evolution of the concept, from the initial unawareness of the need for a quality assessment (still present in many areas) to the present views, the author also tries to shed some light and some clarity on the most popular and debated misunderstandings, particularly about the concepts of error, true quantity value(s), and measured quantity value. The author is the convener of the Joint Committee for Guides in Metrology Working Group 1 (Guide to the expression of uncertainty in measurement). The opinion expressed in this paper does not necessarily represent the view of this working group. View full abstract»

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  • Quantum AC Voltage Standards

    Page(s): 2160 - 2166
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    Standards based on the Josephson effect are being increasingly utilized for generation of quantum-accurate ac waveforms. These standards fall into two broad categories: those whose output is generated as a stepwise-approximated sine wave via programmable Josephson arrays and those with a true sinusoidal output generated by pulses supplied to Josephson junctions. This paper presents a survey of the present state of quantum ac sources and discusses future implementation of these systems for improved ac metrology. We focus mainly on developments at the National Institute of Standards and Technology but also summarize relevant work elsewhere. View full abstract»

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  • Uncertainty: Only One Mathematical Approach to Its Evaluation and Expression?

    Page(s): 2167 - 2178
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB) |  | HTML iconHTML  

    This paper considers the well-known concept of uncertainty of a measurement result and discusses the mathematical approach adopted for its evaluation and expression by the present standard documents and, in particular, the Guide to the Expression of Uncertainty in Measurement. The practical limitations introduced by the assumptions of this mathematical approach are discussed, and the requirements of a new mathematical approach capable of overcoming the present limitations are drawn. A different mathematical approach, based on the theory of evidence and originally developed by the authors in recent years, is presented and discussed, with some new findings and observations. View full abstract»

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  • Impact of the Model on the Accuracy of Synchrophasor Measurement

    Page(s): 2179 - 2188
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    Phasor measurement units (PMUs) are becoming one of the key issues of power network monitoring. They have to be able to perform accurate estimations of quantities of interest either under steady-state or transient conditions. Among all the sources which may contribute to the uncertainty introduced by PMUs, this paper analyzes the impact of the phasor estimation models on the accuracy of these devices, focuses on algorithms proposed in the literature for the estimation of dynamic phasors, and studies their performances under several different conditions. View full abstract»

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  • A Real-Time Visual Inspection System for Discrete Surface Defects of Rail Heads

    Page(s): 2189 - 2199
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (852 KB) |  | HTML iconHTML  

    Discrete surface defects impact the riding quality and safety of a railway system. However, it is a challenge to inspect such defects in a vision system because of illumination inequality and the variation of reflection property of rail surfaces. This paper puts forward a real-time visual inspection system (VIS) for discrete surface defects. VIS first acquires a rail image by the image acquisition system, and then, it cuts the subimage of rail track by the track extraction algorithm. Subsequently, VIS enhances the contrast of the rail image using the local normalization (LN) method, which is nonlinear and illumination independent. At last, VIS detects defects using the defect localization based on projection profile (DLBP), which is robust to noise and very fast. Our experimental results demonstrate that VIS detects the Type-II defects with a recall of 93.10% and Type-I defects with a recall of 80.41%, and the proposed LN method and DLBP algorithm are better than the related well-established approaches. Furthermore, VIS is very fast with a linear computational time complexity, and it can be in real time to run on a 216-km/h test train under our experimental setup. View full abstract»

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  • Health Condition Monitoring of Machines Based on Hidden Markov Model and Contribution Analysis

    Page(s): 2200 - 2211
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    Degradation parameter from normal to failure condition of machine part or system is needed as an object of health monitoring in condition-based maintenance (CBM). This paper proposes a hidden Markov model (HMM) and contribution-analysis-based method to assess the machine health degradation. A dynamic principal component analysis (DPCA) is used to extract effective features from vibration signals, where inherent signal autocorrelation is considered. A novel machine health assessment indication, HMM-based Mahalanobis distance is proposed to provide a comprehensible indication for quantifying machine health states. A variable-replacing-based contribution analysis method is developed to discover the effective features that are responsible for the detection and assessment of machine health degradation in its whole life. The experimental results based on a bearing test bed show the plausibility and effectiveness of the proposed methods, which can be considered as the machine health degradation monitoring model. View full abstract»

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  • Low-Power Die-Level Process Variation and Temperature Monitors for Yield Analysis and Optimization in Deep-Submicron CMOS

    Page(s): 2212 - 2221
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    This paper reports design, efficiency, and measurement results of the process variation and temperature monitors for yield analysis and enhancement in deep-submicron CMOS circuits. Additionally, to guide the verification process with the information obtained through monitoring, two efficient algorithms based on an expectation-maximization method and adjusted support vector machine classifier are proposed. The monitors and algorithms are evaluated on a prototype 12-bit analog-to-digital converter fabricated in standard single poly six-metal 90-nm CMOS. View full abstract»

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  • Health Monitoring of Cooling Fans Based on Mahalanobis Distance With mRMR Feature Selection

    Page(s): 2222 - 2229
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (466 KB) |  | HTML iconHTML  

    Cooling fans are widely used for thermal management in electronic products. The failure of cooling fans may cause electronic products to overheat, which can shorten the product's life, cause electronic components to burn, and even result in catastrophic consequences. Thus, there is a growing interest in health monitoring and anomaly detection for cooling fans in electronic products. A novel method for the health monitoring of cooling fans based on Mahalanobis distance with minimum redundancy maximum relevance features is proposed in this paper. A case study of anomaly detection in cooling fans is carried out. The proposed method helps to avoid multicollinearity and tracks the degradation trends of the cooling fans. The results show that the proposed approach is feasible. View full abstract»

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  • In Situ Moisture Content Monitoring Sensor Detecting Mutual Coupling Magnitude Between Parallel and Perpendicular Dipole Antennas

    Page(s): 2230 - 2241
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    This paper presents an in situ moisture content sensor based on a switched-polarization dipole antenna that detects the magnitude of mutual coupling between perpendicular and parallel polarizations. Three aspects of the sensor development are presented: a new closed-form calculation of mutual impedance of perpendicular polarization dipole antenna, an antenna design, and an investigation of performance enhancement. As the sensor detects only the magnitude of mutual coupling, it is low cost and low profile and needs less processing time. Thus, it is suitable for a closed-loop drying system. Our study has shown that the values of the dielectric constants measured by this sensor are comparable to the reference values from the transmission line technique in the previous work. However, there are significant differences in the values of the dielectric loss factors because the structure of the presented sensor is not a closed boundary like the transmission line sensor. Therefore, error compensation has been developed to correct the results. This sensor, in a closed-loop drying system, has shown good performance for in situ monitoring and real-time monitoring. Consequently, it is very suitable for monitoring the moisture content of paddy (rough rice). View full abstract»

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  • Quantitative Evaluation of Impacts of Random Errors on ALS Accuracy Using Multiple Linear Regression Method

    Page(s): 2242 - 2252
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    The formulas for error propagation from the random error sources to the three-dimensional (3-D) coordinate errors of laser footprints of an airborne laser scanning (ALS) system were deduced. Based on large-scale sample data, multiple linear regression experiments were carried out to obtain the standardized regression coefficients of the random errors for the 3-D coordinate errors under different flight heights (from 500 to 6000 m above ground level). The standardized regression coefficients were used to quantitatively evaluate the impacts of the random errors and to sort the impacts on the order of importance. The variation of the impacts of the random errors with increasing flight height and tilt angle of the mirror was also analyzed. The experimental results provide an important guide for error budget of various sensors in the ALS system so as to effectively suppress or compensate significant errors and to improve the performance of the ALS system. View full abstract»

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  • A 2–20-GHz Analog Lag Correlator for Radio Interferometry

    Page(s): 2253 - 2261
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (770 KB) |  | HTML iconHTML  

    We present the design and testing of a 2-20-GHz continuum-band analog lag correlator with 16 frequency channels for astronomical interferometry. The correlator has been designed for future use with a prototype single-baseline interferometer operating at 185-275 GHz. The design uses a broad-band Wilkinson divider tree with integral thin-film resistors implemented on an alumina substrate, and custom-made broad-band InGaP/GaAs Gilbert Cell multipliers. The prototype correlator has been fully bench-tested, together with the necessary readout electronics for acquisition of the output signals. The results of these measurements show that the response of the correlator is well behaved over the band. An investigation of the noise behavior also shows that the signal-to-noise ratio of the system is not limited by the correlator performance. View full abstract»

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  • Estimation of Attitude and External Acceleration Using Inertial Sensor Measurement During Various Dynamic Conditions

    Page(s): 2262 - 2273
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    This paper proposes a Kalman filter-based attitude (i.e., roll and pitch) estimation algorithm using an inertial sensor composed of a triaxial accelerometer and a triaxial gyroscope. In particular, the proposed algorithm has been developed for accurate attitude estimation during dynamic conditions, in which external acceleration is present. Although external acceleration is the main source of the attitude estimation error and despite the need for its accurate estimation in many applications, this problem that can be critical for the attitude estimation has not been addressed explicitly in the literature. Accordingly, this paper addresses the combined estimation problem of the attitude and external acceleration. Experimental tests were conducted to verify the performance of the proposed algorithm in various dynamic condition settings and to provide further insight into the variations in the estimation accuracy. Furthermore, two different approaches for dealing with the estimation problem during dynamic conditions were compared, i.e., threshold-based switching approach versus acceleration model-based approach. Based on an external acceleration model, the proposed algorithm was capable of estimating accurate attitudes and external accelerations for short accelerated periods, showing its high effectiveness during short-term fast dynamic conditions. Contrariwise, when the testing condition involved prolonged high external accelerations, the proposed algorithm exhibited gradually increasing errors. However, as soon as the condition returned to static or quasi-static conditions, the algorithm was able to stabilize the estimation error, regaining its high estimation accuracy. View full abstract»

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  • Feasibility Study and Performance Analysis of a Gyroless Orientation Tracker

    Page(s): 2274 - 2282
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (677 KB) |  | HTML iconHTML  

    Inertial orientation tracking systems commonly use three types of sensors: accelerometers, magnetometers, and gyroscopes. The angular rate signal is used to obtain a dead reckoning estimate, whereas the gravitational and local magnetic field measures allow us to apply a correction and to obtain a drift-free result. Considering the present market of inertial MEMS sensors, the current consumption of gyroscopes represents a major part of the power budget of wireless inertial sensor nodes, which should be minimized given the mobility of the application. This paper introduces an orientation tracking algorithm, based on an unscented Kalman filter, that does not require angular rate data for tracking human movements up to 450 °/s , which is a reasonable value for many applications. Since accelerometers measure other accelerations beside gravity and magnetometers are prone to magnetic disturbances, adaptive techniques are applied in order to reduce the influence on the estimations. The performance of the system is quantitatively analyzed and compared to an estimator that includes angular rate information. View full abstract»

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  • A New Regularized Adaptive Windowed Lomb Periodogram for Time–Frequency Analysis of Nonstationary Signals With Impulsive Components

    Page(s): 2283 - 2304
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1693 KB) |  | HTML iconHTML  

    This paper proposes a new class of windowed Lomb periodogram (WLP) for time-frequency analysis of nonstationary signals, which may contain impulsive components and may be nonuniformly sampled. The proposed methods significantly extend the conventional Lomb periodogram in two aspects: 1) The nonstationarity problem is addressed by employing the weighted least squares (WLS) to estimate locally the time-varying periodogram and an intersection of confidence interval technique to adaptively select the window sizes of WLS in the time-frequency domain. This yields an adaptive WLP (AWLP) having a better tradeoff between time resolution and frequency resolution. 2) A more general regularized maximum-likelihood-type (M-) estimator is used instead of the LS estimator in estimating the AWLP. This yields a novel M-estimation-based regularized AWLP method which is capable of reducing estimation variance, accentuating predominant time-frequency components, restraining adverse influence of impulsive components, and separating impulsive components. Simulation results were conducted to illustrate the advantages of the proposed method over the conventional Lomb periodogram in adaptive time-frequency resolution, sparse representation for sinusoids, robustness to impulsive components, and applicability to nonuniformly sampled data. Moreover, as the computation of the proposed method at each time sample and frequency is independent of others, parallel computing can be conveniently employed without much difficulty to significantly reduce the computational time of our proposed method for real-time applications. The proposed method is expected to find a wide range of applications in instrumentation and measurement and related areas. Its potential applications to power quality analysis and speech signal analysis are also discussed and demonstrated. View full abstract»

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Aims & Scope

Papers are sought that address innovative solutions to the development and use of electrical and electronic instruments and equipment to measure, monitor and/or record physical phenomena for the purpose of advancing measurement science, methods, functionality and applications.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Prof. Alessandro Ferrero
Dipartimento di Elettrotecnica
Piazza Leonardo da Vinci 32
Politecnico di Milano
Milano 20133 Italy
alessandro.ferrero@polimi.it
Phone: 39-02-2399-3751
Fax: 39-02-2399-3703