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  • Other Sources  (15)
  • MAN/SYSTEM TECHNOLOGY AND LIFE SUPPORT  (7)
  • OCEANOGRAPHY  (4)
  • MACHINERY  (2)
  • PHYSICS (GENERAL)  (1)
  • SPACECRAFT PROPULSION AND POWER  (1)
  • 1985-1989  (15)
  • 1989  (10)
  • 1987  (5)
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  • Other Sources  (15)
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  • 1985-1989  (15)
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  • 1989  (10)
  • 1987  (5)
  • 1988  (1)
  • 1
    Publication Date: 2011-08-19
    Description: An interferometric radar altimeter is proposed to provide wide-swath high-resolution ocean topography. Several system design issues of such an interferometric altimeter are presented. Tradeoffs between processing of the interferometric signal using the so-called amplitude approach and the so-called phase approach are shown. The systematic errors associated with uncertainties in the interferometer baseline and the attitude of interferometer orientation are also discussed. Described is an approach using the measurements at orbit cross-over regions, together with the topography measurements from a traditional nadir-looking altimeter that are not contaminated by the baseline and attitude noises. Preliminary simulation results show that such an approach can generate an acceptable error level if the ocean surface does not change appreciably between the observations.
    Keywords: OCEANOGRAPHY
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  • 2
    Publication Date: 2011-08-19
    Description: The paper reports on an on-going effort at the JPL to estimate the accuracy of ocean state parameters which have been obtained from the specular point probability density function (pdf) of the ocean surface. This pdf is obtained by the deconvolution of the return waveform of oceanographic altimeters such as Seasat, Geosat, or Topex.
    Keywords: OCEANOGRAPHY
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  • 3
    Publication Date: 2011-08-19
    Description: A new method of calculating the electric field scattered from two-dimensional conducting rough surfaces is presented. This method uses the operator conjugate gradients technique and the extended boundary condition equation. This avoids the build-up of round-off errors encountered in the inversion of large matrices. It also avoids the singularities of the integral kernels usually encountered in the method of moments. Techniques for improving the rate of convergence by applying physical constraints are discussed. This method is presently being used to calculate the polarization signatures from simulated ocean-like surfaces.
    Keywords: OCEANOGRAPHY
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  • 4
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    Publication Date: 2011-08-19
    Description: The three most successful models for describing scattering from random rough surfaces are the Kirchhoff approximation (KA), the small-perturbation method (SPM), and the two-scale-roughness (or composite roughness) surface-scattering (TSR) models. In this paper it is shown how these three models can be derived rigorously from one perturbation expansion based on the extinction theorem for scalar waves scattering from perfectly rigid surface. It is also shown how corrections to the KA proportional to the surface curvature and higher-order derivatives may be obtained. Using these results, the scattering cross section is derived for various surface models.
    Keywords: PHYSICS (GENERAL)
    Type: Radio Science (ISSN 0048-6604); 24; 681-693
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  • 5
    Publication Date: 2011-08-19
    Description: An evaluation of the deconvolution method for estimating ocean surface parameters from ocean altimeter waveforms is presented. It is shown that this method presents a fast, accurate way of determining the ocean surface parameters from noisy altimeter data. Three parameters may be estimated by using this method, including the altimeter-height error, the ocean-surface standard deviation, and the ocean-surface skewness. By means of a Monte Carlo experiment, an 'optimum' deconvolution algorithm and the accuracies with which the above parameters may be estimated using this algorithm are determined. Then the influence of instrument effects, such as errors in calibration and pointing-angle estimation, on the estimated parameters is examined. Finally, the deconvolution algorithm is used to estimate height and ocean-surface parameters from Seasat data.
    Keywords: OCEANOGRAPHY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 9761-977
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  • 6
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    Publication Date: 2019-07-13
    Description: This paper describes the architecture and Ada language implementation of a process-level run-time control subystem for the Jet Propulsion Laboratory (JPL) telerobot system. The concept of run-time control in a combined robot-teleoperation environment is examined and the telerobot system at JPL is described. An Ada language implementation of the JPL Telerobot Run-Time Controller (RTC) is described by highlighting the functional behavior of the subsystem, defining the internal modules, and providing a functional flow time sequence of internal module activity.
    Keywords: MAN/SYSTEM TECHNOLOGY AND LIFE SUPPORT
    Type: Intelligent robots and computer vision; Oct 28, 1986 - Oct 31, 1986; Cambridge, MA; United States
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  • 7
    Publication Date: 2019-07-12
    Description: Set of three reports describes work on Protoflight Manipulator Assembly (PFMA). "Performance Characteristics of Protoflight Manipulator Assembly" presents parameters of PFMA after refurbishment of operating components. "End Effector and Task Board Development for the Protoflight Manipulator Assembly" describes special tools and adaptations allowing PFMA to be used for servicing equipment. "Modular Software Development for the Protoflight Manipulator Assembly" documents interface and control software for PFMA.
    Keywords: MACHINERY
    Type: MFS-27067 , NASA Tech Briefs (ISSN 0145-319X); 13; 9; P. 97
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  • 8
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    Publication Date: 2019-07-12
    Description: Forward and inverse dynamics solved using Kalman filtering and Bryson-Frazier smoothing. Dynamics of serial-link robot arm solved by using recursive techniques from linear filtering and smoothing theory. Solutions of dynamical equations give forces, moments, and accelerations at joints between links, and multilink inertia matrix and its inverse. Theoretical developments lay foundation for use of filtering and smoothing techniques in design of robot controls.
    Keywords: MACHINERY
    Type: NPO-17040 , NASA Tech Briefs (ISSN 0145-319X); 11; 7; P. 85
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  • 9
    Publication Date: 2019-07-13
    Description: The paper reports the ongoing development of a telerobot demonstrator. The demonstrator is implemented as a laboratory-based research testbed, and will show proof-of-concept for supervised automation of space assembly, servicing, and repair operations. The demonstrator system features a hierarchically layered intelligent control architecture which enables automated planning and run-time sequencing of complex tasks by a supervisory human operator. The demonstrator also provides a full bilateral force-reflecting hand control teleroperations capability. The operator may switch smoothly between the automated and teleroperated tasking modes in run-time, either on a preplanned or operator-designated basis.
    Keywords: MAN/SYSTEM TECHNOLOGY AND LIFE SUPPORT
    Type: AAS PAPER 87-045 , Guidance and control 1987; Jan 31, 1987 - Feb 04, 1987; Keystone, Co; United States
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  • 10
    Publication Date: 2019-07-13
    Description: A description is given of a pulse-width-modulated buck-boost converter designed to interface a 500 Wh inertial energy storage system operating from 70 to 140 VDC to a constant bus of 150 VDC. Implementation of hysteresis feedback control provides excellent voltage regulation. The design is based on a 300-Wh, 94 percent Wh efficient prototype and is currently being optimized to yield 97 percent overall watt-hour efficiency.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: IECEC-89; Aug 06, 1989 - Aug 11, 1989; Washington, DC; United States
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