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Instrumentation and Measurement, IEEE Transactions on

Issue 2 • Date Apr 1992

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Displaying Results 1 - 25 of 25
  • Measurement and evaluation of two-phase flow parameters

    Page(s): 298 - 303
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (492 KB)  

    The fuzzy set theory and the flow-imaging technique were applied to measure the flow pattern and void fraction of two-phase flow. The flow pattern was identified online by using `fuzzy identification', and an instrument system based on the flow-imaging technique was developed for online flow pattern measurement as well. The void fraction was evaluated online by `fuzzy multifactorial evaluation'. The void fraction was also measured online by an instrument system based on the flow-imaging technique. The experimental results show that the developed methods are satisfactory View full abstract»

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  • A potentiostat based on a voltage-controlled current source for use with amperometric gas sensors

    Page(s): 308 - 310
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    Amperometric gas-sensing devices develop a current that is proportional to the concentration of gas that is supplied to them. The circuit that maintains electrochemical stability in the sensor as well as buffering the current output is called a potentiostat. Some sensors used for gas sensing have very large electrode capacitances, which can result in instability with conventional potentiostat designs. The responses of two potentiostat designs to a gas were compared. One is based on conventional use of a current-to-voltage converter (CVC); the second is a new design which uses a voltage-controlled current source (VCCS). A frequency analysis of the VCCS potentiostat design is included View full abstract»

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  • A low-cost frequency multiplier for synchronous sampling of periodic signals

    Page(s): 203 - 207
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    The theory of digital signal processing indicates clearly that the measurements performed on periodic signals by means of digital techniques are affected by an error due to the nonsynchronization between the sampling frequency and the signal frequency. The authors present a low-cost device, based on a frequency multiplier, that allows the generation of sampling pulses synchronized with the signal frequency. The behavior of this device is analyzed in order to assure its ability to work with input signals in the frequency range typical of the mains. As an example of the application of this device, the results of the Fourier analysis of a multifrequency signal are given, showing the high accuracy that can be attained View full abstract»

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  • New method for reactive power and energy measurement

    Page(s): 280 - 285
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (420 KB)  

    The properties of an electronic reactive power and energy measurement method based on a frequency-controlled power-to-pulse-rate conversion are analyzed. The reactive power and energy measurements can be efficiently performed by using a simple integrating circuit as a phase shifter, and frequency-controlled analog-to-pulse-rate converter. A low value of the output pulse rate should not be considered as an inherent disadvantage of the method. By introducing a phase-locked loop in order to achieve high pulse-rate output, the benefit of high resolution is added to the method. The improved electronic structure for the measurement can be implemented in the design of reactive power and energy standards. For precision var-hour meters based on the proposed method, it is possible to have an efficient error-checking and adjustment procedure. The proposed method allows reactive power and energy measurement to be made in single- and poly-phase, symmetrical and unsymmetrical, and balanced and unbalanced networks View full abstract»

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  • A 100-Msps sampling analog-to-digital converter chip set

    Page(s): 208 - 211
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    The authors describe a 100-Msps sampling analog-to-digital converter (ADC) chip set that can be used for a wideband high-resolution digital storage oscilloscope (DSO). A high conversion rate and a 500-MHz sampling bandwidth with an 8-b effective resolution are obtained by a combination of three Si-bipolar chips and two GaAs-diode chips. the ADC uses a pipelined two-step subranging architecture that uses two cascade wideband track-and-hold (T/H) circuits. The design features of the T/H circuits and the residual amplifier are also presented View full abstract»

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  • Measurement and analysis for stripline material parameters using network analyzers

    Page(s): 286 - 290
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    The characterization of material parameters for dielectrics used in the construction of stripline and related structures is presented. The measured scattering parameters of transmission-line samples are used to predict the characteristics of the dielectric materials used in the construction in addition to effects due to rough dielectric-conductor interfaces. The measurements have been performed using a network analyzer with the `thru-reflect-line' calibration technique. The calibration process, the structure of the transmission-line sample, and the frequency-domain model are reviewed. Measured results are presented with predicted values for the dielectric constant and loss tangent of dielectric materials common in thick-film structures View full abstract»

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  • Optimization and analysis of a capacitive contactless angular transducer

    Page(s): 311 - 315
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    A capacitive angular transducer under development for industrial and military applications is described. An operational description based on the physical configuration of the transducer is presented in terms of a lumped parameter model. From the model, analytical operational performance criteria, i.e. frequency response and accuracy, are developed, analyzed, and supported with experimental data. Model results are used to develop criteria for the instrumentation interface and operational specifications for the transducer system View full abstract»

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  • Process data chemometrics

    Page(s): 262 - 268
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB)  

    A data analysis technique successfully applied in spectroscopy to reduce a large quantity of data into meaningful information, called chemometrics, is discussed. Data when properly interpreted by statistical data analysis tools and fundamental and heuristic models yield meaningful information. The use of chemometrics as a multivariate analyzer to provide a composite measurement of the state of a chemical process operation is examined. An application of this analyzer on a Du Pont plant is presented, and two measures to detect and identify important process shifts are introduced View full abstract»

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  • Measurement problems arising from the use of a recursive algorithm for model identification of electrical systems

    Page(s): 240 - 245
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    The use of parameter estimation techniques in practical applications requires accurate analysis of the associated measurement and computation problems. With reference to an already proposed model identification procedure, the authors deal with the experimental tests carried out in order to highlight problems and to find the most appropriate solutions. In particular, a synchronization method is described, and some suggestions concerning the optimal working conditions of all the necessary devices are reported View full abstract»

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  • EMI shielding measurements of conductive polymer blends

    Page(s): 291 - 297
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    Shielding efficiencies for a number of blends containing a variety of conductive fillers, including intrinsically conductive polymers, have been measured in the near field with a dual-chamber box and in the far field with a transmission line fixture. Although all samples satisfied the classical good-conductor approximation, most of them exhibited a crossover from being electrically thin (thickness<skin depth) to being electrically thick (thickness>skin depth) over the frequency range of interest, 1 MHz to 3 GHz. The theoretical relations for both near-field and far-field shielding which are prevalent in the literature do not accurately describe this region of crossover. The authors have derived expressions which describe the behavior accurately over the entire range of interest. Far-field shielding efficiencies as high as 70 dB at 1 GHz were measured for purely organic composites consisting of an intrinsically conductive polymer, polyaniline, dispersed in a thermoplastic matrix View full abstract»

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  • Simultaneous measurements of dynamic values using the transit time method

    Page(s): 251 - 255
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    The problem of simultaneous and accurate measurements of two dynamic values, time dependencies of flow velocity and ultrasound velocity in the flow, is analyzed. In order to measure two dynamic values simultaneously a theory of the transit time method has developed, and the theoretical model of a microprocessor-based measuring system has been derived. The ways to improve the accuracy and information of such dual-channel measurement systems have been examined. It is shown that invariance between two channels of a measurement system can be achieved when dynamic, nonlinear, parametric models of these channels are identified in real time during the process of measurement, and when the multipulse irradiation of flow is used. The results of computer simulation of transit time method dynamic errors are represented. A method of minimizing these errors has been proposed View full abstract»

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  • Analysis of symmetrical six-port junction when configured as a six-port reflectometer

    Page(s): 193 - 197
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    The symmetrical six-port junction (together with a directional coupler and four power detectors) has in the ideal case been shown to be suitable for use as a six-port reflectometer. The author presents formulas that can predict the performance of such a reflectometer when the symmetrical six-port junction is nonideal. The results obtained indicate that in the presence of junction imperfections, it may be possible to effect some improvement in the performance of the reflectometer by a simple restructuring of the system configuration View full abstract»

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  • Calibration of an electronic multisensor system for measuring high pressures

    Page(s): 269 - 273
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    An electronic system for measuring high pressures is considered. Its functioning is based on three fiber-optic transducers whose static characteristics are nonmonotonic and significantly influenced by temperature. A method for static calibration of this system is proposed, based on the use of spline functions of one variable. Its applicability in the considered case is demonstrated using synthetic data generated after an idealized model of the transducers. A method for valuation of the quality of calibration is also proposed and used for quantitative characterization of the impact of the number and errors of the data used for calibration on the quality of calibration View full abstract»

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  • Filtering capabilities and convergence of the Van-Cittert deconvolution technique

    Page(s): 246 - 250
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (412 KB)  

    The authors demonstrate the application of the Van-Cittert technique in iterative frequency-domain deconvolution. The technique is shown to have built-in filtering capabilities which can be used successfully to produce optimum deconvolution estimates. The Bennia-Riad optimization criterion for iterative deconvolution is jointly used with the Van-Cittert technique to optimize the number of iterations required to achieve acceptable (optimum) deconvolution results. An experimental example is provided to illustrate the application of the deconvolution technique and the optimization criterion View full abstract»

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  • Scale-model design of a submillimeter-wave planar diode mixer

    Page(s): 198 - 202
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    The design of a planar diode submillimeter-wave mixer is presented in which scale models play an important role. By constructing larger scale models of mixer components, the design process is simplified by making component changes easier and by making the measurements easier with the aid of a network analyzer. Separate scale model measurements were used to find optimum diode geometry, a wide bandwidth transition from circular waveguide to shielded microstrip, a DC return bondwire, and a microstrip low-pass filter. After combining the results from these measurements to form a mixer circuit model, the combined effect of the various components was studied, and adjustments were made to present an optimum impedance to the diode terminals. Tests of the design at 345 GHz confirm the accuracy of the scale model design procedure. Design information presented on the different components will be useful for developing future planar diode mixers View full abstract»

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  • Some theorems on Walsh transforms of quantizer differential and integral nonlinearity

    Page(s): 218 - 225
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    Methods for diagnosing weight coefficient tolerances of quantizers are derived, based on the assumption of known and available data about the quantizer's nonlinearities. Two of the methods are direct and based on the Householder orthogonalization, applied to an overdetermined equation system containing data about differential or integral nonlinearities. The remaining two methods are indirect and are based on two theorems that use the Walsh transformation on the quantizer's differential or integral nonlinearities. The language MATLAB has been used to good effect for simulation of these techniques View full abstract»

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  • The influence of windowing on the accuracy of multifrequency signal parameter estimation

    Page(s): 256 - 261
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    The author investigates the influence of windowing on the accuracy of a frequency-domain procedure suitable for real-time estimations of multifrequency signal parameters. Imposing very weak assumptions about the statistical description of the noise, simple and accurate expressions for the estimator variances are established. They allow both the evaluation of the result accuracy and the design of the measurement procedure. Simulation results confirm the validity of the presented analysis View full abstract»

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  • Embedded instrumentation for evaluating task sharing performance in a distributed computing system

    Page(s): 316 - 321
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    An example of application-level performance measurement on a distributed computing system using software-based instrumentation is considered. Embedded software instrumentation for measuring the performance of a decentralized adaptive task-sharing algorithm in a distributed computing system is described. For the application considered, the simplicity and flexibility provided by software-based instrumentation are demonstrated, and its limitations are discussed. Quantitative results obtained from the implementation on an experimental distributed computing system consisting of VAX stations connected by a local area network are presented View full abstract»

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  • Both active and reactive power and energy transfer standard

    Page(s): 274 - 279
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (580 KB)  

    A thermal converter to DC voltage, with 10-ppm accuracy and a frequency range of 0-200 kHz, which can be used for active power measurements, has been developed using an infrared thermal converter. Moreover, a proposal for implementing, with lower accuracy, the converter for energy and reactive power is also illustrated View full abstract»

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  • Testing of commercial optical media

    Page(s): 304 - 307
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    Data integrity is a primary concern for the users of any data storage medium. For optical data storage, the integrity is directly related to the performance and defect level of the storage media and to how they change as the media age. While media materials and thin-film stack designs are chosen with the goal of achieving high data integrity and reliability, variations in the media manufacturing processes themselves often can determine how the media will behave. These variations can be found through detailed and careful characterization testing. The authors describe some of the test methods used for characterizing rewritable media and discuss some results obtained while surveying commercially available media View full abstract»

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  • The interpolated fast Fourier transform: a comparative study

    Page(s): 226 - 232
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    The properties of five interpolating fast Fourier transform (IFFT) methods (IFFT) are studied with respect to their systematic errors and their noise sensitivity, for a monofrequency signal. It is shown that windows with small spectral side lobes do not always result in a better overall performance of the IFFT method and that time-domain estimators can be more efficient than the analyzed IFFT methods View full abstract»

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  • Automated swept-angle bistatic scattering measurements using continuous wave radar

    Page(s): 185 - 192
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    The establishment of the IEEE Electromagnetic Modeling Software Committee and the Department of Defense sponsored Electromagnetic Code Consortium indicates the electromagnetics community is interested in validating general electromagnetic modeling software. An important part of this validation is obtaining reliable bistatic scattering measurements on canonical scatterers. The author describes a simple system well suited for such measurements. The system is capable of measuring bistatic scattering from near backscatter through forward scatter. At X-band frequencies, scattering levels of -50 dBsm in the backscattering region and -20 dBsm near forward scatter can be measured to an accuracy of ±1 dB. This fully automated indoor system fixes the target and direction of illumination and sweeps the receive antenna to collect data as a direct function of bistatic angle. A broad band, coherent, continuous wave radar is used to obtain both amplitude and phase of the component of the total field aligned with the receive antenna polarization. The system design, calibration procedures, and measurement accuracy are considered View full abstract»

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  • Parametric identification of two-port models in the frequency domain

    Page(s): 233 - 239
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (508 KB)  

    The authors treat the problem of parametric estimation of linear time-invariant dynamic two-port models (e.g. the short-circuit admittance matrix) from experimental data. A multivariate frequency-domain Gaussian maximum likelihood estimator is proposed to estimate the unknown coefficients occurring in the rational two-port model. It takes the perturbing noise of all the measured voltages and currents into account. The covariance matrix of the noise is assumed to be known, e.g. from measurements. The estimates and their covariance matrix are obtained as the result of an optimization procedure. The value of the minimized loss function and the covariance matrix of the estimates can be used to determine the model structure. The ability of the estimator to handle real measurement problems is demonstrated by means of experimental results. Using the estimated two-part parameters of an unloaded band-pass filter, it was possible to predict the transfer function of the loaded filter within an error of ±0.01 dB on the magnitude and ±0.1° on the phase View full abstract»

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  • Video display terminal fringing magnetic field measurements

    Page(s): 178 - 184
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    Possible occupational health or public health risks due to video display terminals (VDTs) are addressed. The authors note the errors of current jargon and correctly define the terms needed to describe the fringing magnetic flux density near any magnetically deflected, raster scan, cathode ray tube display. Theory and preliminary measurements have shown that the ELF AC electric field related to VDT display electronics is small, and the electromagnetic field strength at any frequency is truly negligible as an occupational health risk near any cathode ray tube display. Application of Maxwell's equations shows that the commonly used pickup coil responds to the derivative of magnetic flux density. The transducer needs an integrator to respond properly to the sawtooth waveforms of deflection fields. Correct measurements of VDT fringing magnetic fields are presented. A Swedish test method is briefly discussed. The conclusion from this work is strong. Theory and these measurements show there is not a verifiable occupational health risk from the fringing ELF electric or magnetic fields or any frequency electromagnetic fields near VDTs View full abstract»

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  • A semifixed frequency method for evaluating the effective resolution of A/D convertors

    Page(s): 212 - 217
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    A detailed description of a novel algorithm for the `effective bit' test in noncoherent conditions is presented. This algorithm can offer absolute convergence and has the potential for faster implementation than existing methods. A flow diagram for the algorithm and its implementation using the MATLAB package is included. The metrological reliability of input data is checked. An adopted ZEROIN program and Householder orthogonalization are applied to estimate the starting point of an iterative process, and Newton's method is involved in a final calculation for the best-fit curve to the input data 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