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Instrumentation and Measurement, IEEE Transactions on

Issue 3 • Date Jun 1999

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Displaying Results 1 - 20 of 20
  • A novel approach for temperature estimation in squirrel-cage induction motor without sensors

    Publication Year: 1999 , Page(s): 753 - 757
    Cited by:  Papers (9)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    In this paper, the authors present a coupled thermal and electromechanical model for squirrel-cage induction motor simulation and analyses. The effect of iron saturation, rotor parameter variation due to current displacement (skin-effect) and temperature variations of both stator and rotor resistances are taking into account simultaneously. A new device for the temperature measurement in the stationary as well as rotating parts of electric machines is built. The unique construction of the device for continuous rotor temperature monitoring is briefly described. This device is a part of a complete acquisition system, which is used for precise testing and investigating of a coupled thermal and electromechanical phenomena. An original thermal observer based on the direct stator temperature measurement under normal running condition with no additional sensors is proposed View full abstract»

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  • Calibration of a microwave system for measuring grain moisture content

    Publication Year: 1999 , Page(s): 778 - 783
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    This paper relates to a microwave system for grain moisture content determination which is based on simultaneous measurements of two parameters: attenuation and phase shift, of the electromagnetic wave transmitted through the layer of material. The calibration of such a system consists of identifying a function modeling the relationship between these parameters and the measured moisture content, taking into account an influence quantity-temperature T. Two algorithms for calibration are proposed and studied. The results of calibration show that the moisture of hard red winter wheat can be determined with uncertainty less than 0.5% moisture, at the 95% confidence level, in the moisture range of 10% to 19% at grain temperatures between -1°C and 42°C, independent of the grain bulk density View full abstract»

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  • A spectroscopic detecting system for measuring the temperature distribution of silver breaking arc using a CCD color camera

    Publication Year: 1999 , Page(s): 678 - 683
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    This paper describes a spectroscopic detecting system that utilizes a CCD color camera to observe the distributions of two spectral intensities along the axis of an arc column. Following this, the distributions of Ag I 421 nm and Ag I 547 mm spectra observed along the axis of an arc column and the arc temperature calculated from the two spectra when silver contacts interrupt a circuit of dc 50 V and 3.3 A are presented. The spectral intensities of excited silver atoms are strongest near the cathode and become weaker with distance from the cathode contact. The temperature in the cross section of an arc column is highest in the axis of the arc column. The temperature along the axis of arc column is highest near the cathode and becomes weaker with distance from the cathode. Furthermore, in this study it is clarified that CN band spectra exist near the anode contact View full abstract»

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  • Q-factor measurements of open resonators in the millimeter-wave range including coupling losses

    Publication Year: 1999 , Page(s): 688 - 692
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (84 KB)  

    The unloaded quality factor as well as the coupling coefficient of open resonators are determined by evaluating measured complex reflection coefficients. The cavity is described by an equivalent circuit, the parameters of this circuit are calculated by means of a least-square fit of the simulated to the measured reflection coefficients. The solution is obtained using the Householder-algorithm, which promises very fast and stable computation. This approach is capable of evaluating quality-factor measurements for each type of resonator, even with losses in the coupling aperture. Its validity is illustrated by measurements in the cm- and mm-wave range View full abstract»

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  • An automated guarded bridge system for the comparison of 10 kΩ standard resistors

    Publication Year: 1999 , Page(s): 673 - 677
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    An automated guarded resistance bridge has been specifically developed at the National Institute of Standards and Technology (NIST) for the calibration of high-quality 10 kΩ standard resistors. The system is designed to compare up to 30 nominally equal, four-terminal resistors with a resolution and combined relative standard uncertainty of 0.01×10-6 and 0.02×10-6, respectively. It features a self-balancing detector circuit, and a programmable coaxial connector switch for selecting resistors. With a few minor modifications, the system is capable of comparing other nominally equal resistors in the range 100 Ω to 1 MΩ View full abstract»

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  • Distributed data processing in a telemetric system for monitoring civil engineering constructions

    Publication Year: 1999 , Page(s): 773 - 777
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (76 KB)  

    The selected aspects of design methodology of a telemetric system for monitoring civil engineering constructions-using fiber-optic strain sensors-are considered. Particular attention is paid to the design decisions concerning the choice of a method for sensor calibration and measurand reconstruction, resulting requirements for computing power and their consequence on the distribution of data processing in the considered telemetric system. The results of this study may be applied for designing a specific telemetric system with fiber-optic sensors of strain View full abstract»

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  • A computer-assisted range image registration system for nuclear waste cleanup

    Publication Year: 1999 , Page(s): 758 - 762
    Cited by:  Papers (5)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1164 KB)  

    Building a three-dimensional (3-D) computer-based representation of a large or complex scene from a set of range images requires assembling the range images so that they are spatially registered. This paper will present a technique for finding a homogeneous transformation between a pair of range images while making use of both range and intensity information obtained using a laser range scanner. A demonstrated application featuring this technique consists of building a 3-D representation of a nuclear dumpsite, which then serves to help control a teleoperated nuclear waste remediation system View full abstract»

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  • A simulation tool for virtual laboratory experiments in a WWW environment

    Publication Year: 1999 , Page(s): 741 - 746
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (84 KB)  

    Virtual instruments and distributed systems are of great interest to create advanced and flexible teaching and experimentation environments for measurement technologies at limited costs. Availability of simple and efficient technological supports to dissemination and remote use of virtual systems becomes attractive to increase the access to experimental practice without regard to the number of students and their location as well as the variety of instruments and measurement procedures directly available for experimentation View full abstract»

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  • Thin structure deflection measurement

    Publication Year: 1999 , Page(s): 705 - 710
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    Deflection curvature is easily observed during bending of thin structures. There are, however, few practical means available for measuring it. As a consequence, curvature measurements are extremely rare. Strain is usually the preferred measurand of choice. This preference is disadvantageous in the case of thin structures because strain can then be so small that very high resolution sensors are required despite the apparently large deflection curvature. A method of measuring such curvature is presented in this paper. Its conceptual advantages over strain measurement include: (1) position-invariant readings throughout the structural section; (2) sameness of the true and apparent measurands irrespective of the microstructural effects introduced by the sensor; (3) higher sensitivity in the case of thin structures View full abstract»

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  • Prototype fiber optic liquid crystalline sensor for pressure monitoring

    Publication Year: 1999 , Page(s): 684 - 687
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (92 KB)  

    This paper presents results of initial tests performed on a new prototype fiber optic liquid crystalline sensor for hydrostatic pressure monitoring, which employs pressure-induced deformations in twisted nematic liquid crystal cells. The prototype pressure sensor is based on polarization effects occurring in the reflective configuration of the liquid crystal cells under the Mauguin limit. Results indicate that the prototype sensor offers high response to pressure with reduced temperature sensitivity and, depending on the replaceable liquid crystalline sensing element, can be adjusted for monitoring of low hydrostatic pressures up to 4 MPa View full abstract»

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  • Automated system for noise-measurements on low-ohmic samples and magnetic sensors

    Publication Year: 1999 , Page(s): 730 - 735
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (88 KB)  

    An automated system for electronic noise measurements on metal films is presented. This new system, controlled by a personal computer which utilizes National Instruments' LabVIEW software, is designed to measure low frequency noise as a function of an externally imposed magnetic field and as a function of a dc bias current in low-ohmic samples and magnetic sensors. With this system we are able to measure continuously for several days, during which the measured spectra are collected, processed and stored for further analysis View full abstract»

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  • Subspace-based identification of power transformer models from frequency response data

    Publication Year: 1999 , Page(s): 700 - 704
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (100 KB)  

    A recent frequency-domain, subspace-based algorithm is used in the identification of two power transformers. The results indicate that the subspace-based identification algorithms can be used without modification even when the dynamic range of frequency response data is large View full abstract»

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  • New distortion measurement method for booster amplifiers

    Publication Year: 1999 , Page(s): 770 - 772
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (48 KB)  

    The usual method of distortion measurement of an amplifier in a feedback loop involves breaking the loop, which may change the dc and (nonlinear) interstage loading conditions. A new method is presented and proven with theory and experiment, permitting distortion measurement of a final or booster stage within an amplifier. The new method does not require breaking of the feedback loop. Measurements are carried out with linear and nonlinear loudspeaker load View full abstract»

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  • Laser range imaging using the self-mixing effect in a laser diode

    Publication Year: 1999 , Page(s): 693 - 699
    Cited by:  Papers (19)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (372 KB)  

    In this work, we implemented a three-dimensional (3-D) laser range imaging system using the well-known self-mixing effect in a frequency-modulated semiconductor laser diode. The system generates 3-D point sets of a scene, using a single semiconductor laser diode serving both as the light source and as the detector. The experimental imaging accuracy was measured to be 0.87 mm at a distance of 0.55 m after some filtering. This paper focuses on the theoretical description of the self-mixing effect by presenting a survey of the existing literature as it applies to our specific implementation, followed by some experimental results View full abstract»

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  • Thermal flow measurements at Gr/Re2≫1 by silicon anemometry

    Publication Year: 1999 , Page(s): 724 - 729
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB)  

    We present the first characteristics of air flow measurements in the mixed convective region with strong buoyancy effects (Gr/Re2 ≫1), using a thermal silicon double-Wheatstone-bridge vector sensor. The alternating direction method is applied to eliminate additive drift influences. The upper limit on the mixed convective region is experimentally defined to be given by Gr/Re2=[0.3-0.8]. Flow velocity measurements of down to 1 mm/s (Reynolds ≈ 0.3) are realized with an accuracy better than 98% View full abstract»

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  • Multilevel computed hemodynamic parameter maps from dynamic perfusion MRI

    Publication Year: 1999 , Page(s): 711 - 720
    Cited by:  Papers (2)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1200 KB)  

    A rapid time-series of T2*-weighted magnetic resonance (MR) images acquired during the first pass of a bolus injection of a paramagnetic MR contrast agent provides a basis for estimating cerebral perfusion. The concentration versus time of the contrast agent is calculated in a single image plane on a pixel-wise basis. A number of hemodynamic parameters can be extracted from the integral of the concentration-time curve, hence a method for obtaining an efficient and accurate estimate of the area under the curve is essential for the assessment of perfusion images. A new, automatic, multilevel processing method for calculating area under the concentration-time curve is proposed. In the first level of processing, the signal-to-noise ratio (SNR) is estimated for every pixel, and, if satisfactory, the limit points of integration are determined. An averaging filter is applied on the concentration-time curve, and the slope of the output of the filter Is calculated. The thresholds for initial and final integration points are determined next and are used to obtain limit points of integration. At this level, some pixels may be left without computed limits. These are determined at the next level of processing, using the median filter applied on the pixel neighborhood limit points. After determining limit points, the conventional method for integration is used to obtain the area under the curve. Tests of the proposed method are described for both simulated and real data. The simulated data are based on the gamma-variate function, with white noise added. The parameters used are obtained from fitting the gamma-variate function for regions within white matter, gray matter and cerebrospinal fluid in real perfusion images. The results obtained by the proposed estimator compare very favorably with the theoretical values for the particular cases studied. The performance of the proposed method for measuring cerebral hemodynamic parameters is also discussed when applied to perfusion studies in patients performed on a GE Signa 1.5 T, Advantage, whole body scanner. The results compare well with a previously used procedure based on slice-averaged time of arrival of the contrast bolus and manually determined limiting points. The new method automatizes the integration limit selection procedure efficiently, and is based on local, rather than global calculations. The procedure is simple and fast, and can perform numerical integration of 128*256 pMRI images in less than a second on a Sun SPARC 2 workstation View full abstract»

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  • Modeling the spectrometric microtransducer

    Publication Year: 1999 , Page(s): 747 - 752
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    Numerical correction of spectrograms is based on the use of mathematical models of the relationship between a spectrum to be measured and the data obtained by means of a spectrometer. In this paper, a method for mathematical modeling of the spectrometric microtransducer is proposed and discussed. This method is based on decomposition of the spectrometer into functional blocks and on gray-box modeling of those blocks. The input-output model of the spectrometric microtransducer of the spectrometer is obtained by combining the mathematical models of its functional blocks. An example of modeling of the spectrometric microtransducer of the spectrometer SD1000 (by Ocean Optics) is given. Conclusions, concerning the applicability of the results of modeling in the designer's practice, are drawn View full abstract»

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  • The efficiency of methods for measuring A/D converter linearity

    Publication Year: 1999 , Page(s): 763 - 769
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB)  

    In this paper, the efficiency of three methods commonly used to measure the linearity characteristics of precision Nyquist-rate analog-to-digital (A/D) converters is evaluated. The efficiency of each method, which is determined by the time required to obtain linearity estimates at a specified level of accuracy, is compared to the maximum efficiency that is theoretically achievable, as given by the Cramer-Rao bound. Simulation results are presented for two open-loop measurement methods, the tally and weight method and the code density method, demonstrating that the code density method obtains an efficiency close to the theoretical optimum over a wide range of measurement times and converter noise levels, whereas the tally and weight method falls short of the optimum for converters with noise levels exceeding ¼ LSB. The efficiency of the servo loop method, a common closed-loop method for measuring linearity, is similarly evaluated, and is found to fall short of the maximum efficiency that is theoretically achievable in the closed-loop configuration. A modified closed-loop measurement method is described that obtains an efficiency close to the theoretical optimum through the use of maximum-likelihood estimation View full abstract»

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  • Identification of continuous-time systems with missing data

    Publication Year: 1999 , Page(s): 736 - 740
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    This paper treats the identification of continuous-time systems with missing data in the input and output signals. A frequency-domain solution based on an extended transfer function model is given. The basic idea of the approach is to treat the missing data as unknown parameters in the identification problem. No particular pattern for the missing data is assumed. The method is illustrated on simulation and real measurement examples View full abstract»

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  • Reproducibility of transmission line measurement of bipolar I-V characteristics of MOSFETs

    Publication Year: 1999 , Page(s): 721 - 723
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (60 KB)  

    Reproducibility of transmission line (TL) measurement of bipolar current-voltage (I-V) characteristics of grounded gate MOSFET's has been examined. It is observed that the reproducibility is related to the duration of the pulses generated by the transmission line, and a longer pulse duration gives a better reproducibility. For a short pulse duration, it is more difficult to reproduce the I-V characteristics in the triggering region than in other regions (i.e., the pretriggering and snapback regions) 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.

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