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Instrumentation and Measurement, IEEE Transactions on

Issue 5 • Date Oct 1996

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Displaying Results 1 - 11 of 11
  • An acoustic sensor system for determination of macroscopic surface roughness

    Page(s): 879 - 884
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    In this paper, an alternative technique for the measurement of roughness of road surfaces is proposed. This noncontact method is based on the scattering of acoustic waves from the road surface and measuring the normalized Fourier spectrum of the scattered wave in the specular direction. Surfaces prepared with different size aggregates ranging from 2.36 mm to 25 mm were analyzed. The roughness parameter of a surface increases linearly with increasing aggregate size. The proposed method can possibly be extended to perform in situ surface roughness measurements from a moving vehicle View full abstract»

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  • On-line fault detection and diagnosis obtained by implementing neural algorithms on a digital signal processor

    Page(s): 894 - 899
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB)  

    A measurement instrument for on-line fault detection and diagnosis is proposed. It is based on the implementation of a neural network algorithm on a processor specialized in digital signal processing and provided with suitable data acquisition and generation units. Two specific implementations are detailed. The former uses the neural-network to simulate on-line the correct system behavior, thus allowing the fault detection to be achieved by comparing the neural network output with the measured one. The latter uses the neural network to classify on-line the system as correct or faulty, thus allowing the fault detection and diagnosis to be achieved simultaneously. These two implementations are applied to detect on-line and diagnose faults on a real system in order to point out different fields of application and to highlight the performance of the measurement apparatus View full abstract»

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  • Measuring the distance and orientation of a planar surface using nonstructured lighting-3-D measurement system for indoor mobile robots

    Page(s): 885 - 893
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1072 KB)  

    This paper describes a novel method for measuring the distances to planar surfaces and their orientations. The measurement system consists of a TV camera and two ordinary lamps. The lamps are switched on alternately, and images under each lighting condition are taken. If the two light sources are arranged at appropriate positions with respect to the camera, the peak positions in the two images directly give the surface orientation and the perpendicular distance to the plane. By measuring the two peak positions, this method promises to speed up the acquisition of geometrical information on an entire scene considerably because the distance and orientation can be obtained without analyzing range maps. Since the equipment setup is very simple, the proposed technique will be useful, for example, for real-world robotic applications such as navigation of indoor mobile robots. The experimental results on the error of measurement show that the method is sufficient for such purposes View full abstract»

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  • Dynamic clamp for pull-in time reduction

    Page(s): 907 - 909
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    A dynamic clamp aimed at reducing the pull-in time of a digital phase-locked-loop circuit being fed by intermittent signals is presented. This clamp is useful when the phase-locked loop (PLL) is used as a frequency multiplier, and is based on the assumption that the input signal frequency will not change significantly during the period of disconnection. Details on the additional circuitry required to achieve this goal are given, and experimental results are included View full abstract»

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  • Right-cyclic Hadamard coding schemes and fast Fourier transforms for use in computing spectrum estimates in Hadamard-transform spectrometry

    Page(s): 860 - 864
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB)  

    Two computationally efficient spectrum-recovery schemes were recently developed for use by Hadamard-transform spectrometers that have static and dynamic nonidealities in their encoding masks. These methods make use of a left-cyclic Hadamard encodement scheme and the ability to express the left-cyclic WD matrix in factored form as WD =STD. The matrix WD describes the dynamic characteristics of and the encodement scheme for the mask. This paper focuses on the use of a right-cyclic Hadamard pattern to encode the mask and computationally efficient methods that can be used to obtain the spectrum-estimate. The major advantage of right-cyclic over left-cyclic encodement schemes is due to the resulting right-cyclic nature of both W D and WD-1. Fast algorithms, such as a fast Fourier transform (FFT) or a Trench algorithm, that take advantage of the right-cyclic nature of WD can be used to obtain WD-1 directly. In general, the number of mask elements is not an integer power of two, and non-radix-2 FFT's must be used to compute WD-1. Since WD-1 is right-cyclic, the vector-matrix product of WD-1 and the measurement vector can be expressed as a circular correlation and implemented indirectly via FFT's. With appropriate zero-padding of the vectors, radix-2 FFT's can be used for this computation. Various algorithms were used at each step in the overall computation of the spectrum-estimate, and the total computation times are presented and compared. The size of the mask is important in determining which algorithms are the most efficient in recovering the spectrum-estimate View full abstract»

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  • Measurement of maximum time interval error for telecommunications clock stability characterization

    Page(s): 900 - 906
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    Maximum time-interval error (MTIE) is historically one of the main time-domain quantities considered for the specification of clock stability requirements in telecommunications standards. In this paper, MTIE is first introduced according to its formal definition. Then, the main issue of its experimental measurement is pointed out: the heavy computational effort in most cases of practical interest. Therefore, two suitable methods to face up to this issue are herein discussed, summarizing the state of the art of MTIE measurement techniques in telecommunications. A new effective technique is proposed, with the aim to provide an easy but accurate way to test the compliance of telecommunications clocks with MTIE standard masks. Several results, measuring clocks deployed in telecommunications networks, are provided View full abstract»

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  • A high-performance calibration-free charge balancing analog-to-digital converter

    Page(s): 847 - 853
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB)  

    This paper describes a robust charge-balancing analog-to-digital converter (ADC) for dc-voltage measuring applications. The converter, utilizing a continuous-time chopper-stabilized pulse-width modulator, has achieved an absolute accuracy of 20 bits at room temperature, without any trimming or calibration. Within a temperature range of -50°C to 125°C, the accuracy changes with a temperature coefficient of 0.05 ppm/°C. The modulator is implemented by employing commercial discrete components View full abstract»

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  • High-stability current control in the 10 A range

    Page(s): 865 - 871
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (628 KB)  

    This paper reports on the design and evaluation of a high-stability current control developed for energizing the C-field magnet of the high-field cesium standard experiment, currently in progress at the Politecnico di Torino. This source must supply about 0.8 kW dc power with a current stability in the 10-7 range for more than 1 h View full abstract»

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  • Computationally efficient spectrum-recovery methods which compensate for static and dynamic nonidealities in electrooptic masks used in Hadamard-transform spectrometry

    Page(s): 854 - 859
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    A Hadamard-transform spectrometer having no moving parts can be implemented by placing a stationary electrooptic mask in the optical path of a dispersive monochromator. However, two kinds of nonidealities-static and dynamic-associated with the electrooptic mask can cause distortions in the recovered spectrum-estimates. Two system models and corresponding recovery schemes have been developed previously that incorporate the effects of both types of nonidealities. This paper focuses on representing the dynamic nonidealities of the mask by a right-cyclic matrix TD, obtaining TD in practice, and computing TD-1 by computationally efficient moans, thus completing the development of fast implementations of the two previously reported recovery schemes. These computationally efficient recovery schemes were applied to simulated and experimental data, with examples of results presented and discussed View full abstract»

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  • Large-area, real-time imaging system for surface acoustic wave devices

    Page(s): 872 - 878
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1532 KB)  

    A system for imaging the particle displacement envelope of vibrational (transverse) modes of surface acoustic wave (SAW) devices is described. The modes are being imaged using a schlieren method for visualizing the acoustic power flow with a beam-expanded helium-neon (HeNe) laser. The optical arrangement uses internal reflection from within the quartz substrate to achieve high-efficiency acousto-optic diffraction of the laser light. The use of a CCD camera coupled with a frame grabber and a computer with image calculator software establishes an imaging system for large-area, real-time visualization, recording, accurate measurement, and analysis of vibrational modes of SAW devices. These methods are part of an effort to determine the relationship between acceleration sensitivity and transverse variations in the acoustic-mode shape in SAW resonators. Use of the system in imaging a 98 MHz SAW device is presented as an example View full abstract»

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  • Capacitors with very low loss: cryogenic vacuum-gap capacitors

    Page(s): 841 - 846
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    We report on measurements of capacitors with about 1 pF of capacitance, which have unmeasurably small leakage at very low frequencies, placing a lower bound of about 1019Ω on the parallel resistance at an effective frequency of 1 mHz. These measurements are made possible by two themes: the use of vacuum-gap capacitors (i.e., no dielectric material, operated in vacuum), and detection of leakage using single electron tunneling (SET) electrometers, which have very high input impedance. We also report on good achieved results in time stability and lack of frequency and voltage dependence 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
Milano 20133 Italy
alessandro.ferrero@polimi.it
Phone: 39-02-2399-3751
Fax: 39-02-2399-3703