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  • 1
    Publication Date: 1998-03-01
    Print ISSN: 0021-9142
    Electronic ISSN: 2195-0571
    Topics: Physics
    Published by Springer
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  • 2
    Publication Date: 1997-01-01
    Print ISSN: 0931-1890
    Electronic ISSN: 1432-2285
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Springer
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  • 3
    Publication Date: 2019-07-13
    Description: This paper describes the application of the Least Mean Square (LMS) algorithm in tandem with the Filtered-X Least Mean Square algorithm for controlling a science instrument's line-of-sight pointing. Pointing error is caused by a periodic disturbance and spacecraft vibration. A least mean square algorithm is used on-orbit to produce the transfer function between the instrument's servo-mechanism and error sensor. The result is a set of adaptive transversal filter weights tuned to the transfer function. The Filtered-X LMS algorithm, which is an extension of the LMS, tunes a set of transversal filter weights to the transfer function between the disturbance source and the servo-mechanism's actuation signal. The servo-mechanism's resulting actuation counters the disturbance response and thus maintains accurate science instrumental pointing. A simulation model of the Upper Atmosphere Research Satellite is used to demonstrate the algorithms.
    Keywords: Spacecraft Design, Testing and Performance
    Type: Space Flight Mechanics; Feb 01, 1995 - Feb 28, 1995; Albuquerque, NM; United States|Journal of the Astronautical Sciences; 46; 1; 83-90
    Format: text
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  • 4
    ISSN: 0931-1890
    Keywords: Key words Tree transpiration ; Hydraulic resistance ; Hydraulic capacitance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The use of stem sap flow data to estimate diurnal whole-tree transpiration and canopy stomatal conductance depends critically upon knowledge of the time lag between transpiration and water flux through the stem. In this study, the time constant for water movement in stems of 12-year-old Pinus taeda L. individuals was estimated from analysis of time series data of stem water flux and canopy transpiration computed from mean daytime canopy conductance, and diurnal vapor pressure deficit and solar radiation measurements. Water uptake through stems was measured using a constant-heat sapflow probe. Canopy transpiration was correlated to stem uptake using a resistance-capacitance equation that incorporates a time constant parameter. A least-squares auto-regression determined the parameters of the resistance-capacitance equation. The time constants for ten loblolly pine trees averaged 48.0 (SE = 2.0) min and the time lag for the diurnal frequency averaged 47.0 (SE = 2.0) min. A direct-cross correlation analysis between canopy transpiration and sap flow time series showed maximum correlation at an approximately 30 min lag. Residuals (model-predicted minus actual stem flow data) increased with increasing soil moisture depletion. While the time constants did not vary significantly within the range of tree sizes studied, hydraulic resistance and capacitance terms were individually dependent on stem cross-sectional area: capacitance increased and resistance decreased with stem volume. This result may indicate an inverse adjustment of resistance and capacitance to maintain a similar time constant over the range of tree sizes studied.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of intelligent and robotic systems 5 (1992), S. 283-298 
    ISSN: 1573-0409
    Keywords: Back error propagation ; camera calibration ; computer vision ; flexible work cell ; neural network ; robotics ; sensor integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The problem of camera calibration from the perspective of hand-eye integration (henceforth referred to as the Camera-Robot (CR) problem), is addressed in this paper. Mapping results obtained from a least-squares fit using pseudo-inverse technique and a three layer neural network are compared. The calibration matrix is developed to map the image coordinates of an IRI D256 vision processor equipped with a CCD camera directly on to the coordinates for an IBM 7540 SCARA manipulator. One transformation is obtained by performing a least-squares fit using pseudo-inverse technique on a set of one hundred data points which relates two-dimensional (2D) image coordinates to corresponding twodimensional robot coordinates. The CR problem is also approached by using the same data points on a neural network. The results not only demonstrate the ability of neural networks to ‘learn’ the transformation to a reasonable accuracy, but also from the basis for a relatively simple method of adaptive self-calibration of robot-vision systems. In a broader sense, the proposed method can be used to calibrate a variety of robotic sensors that are typically used in a flexible manufacturing environment.
    Type of Medium: Electronic Resource
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