100,058 research outputs found
Bubble-domain circuit wafer evaluation coil set
Coil structures have been designed to permit nondestructive testing of bubble wafers. Wafers can be electrically or optically inspected and operated from quasi-static frequency to maximum device operating frequency
SU3 isoscalar factors
A summary of the properties of the Wigner Clebsch-Gordan coefficients and
isoscalar factors for the group SU3 in the SU2U1 decomposition is
presented. The outer degeneracy problem is discussed in detail with a proof of
a conjecture (Braunschweig's) which has been the basis of previous work on the
SU3 coupling coefficients. Recursion relations obeyed by the SU3 isoscalar
factors are produced, along with an algorithm which allows numerical
determination of the factors from the recursion relations. The algorithm
produces isoscalar factors which share all the symmetry properties under
permutation of states and conjugation which are familiar from the SU2 case. The
full set of symmetry properties for the SU3 Wigner-Clebsch-Gordan coefficients
and isoscalar factors are displayed.Comment: 20 pages, LaTeX (earlier version incomplete
Research in and application of state variable feedback design of guidance control systems for aerospace vehicles Progress report
Weighted least squares parameter estimation, Kalman filter, and random search problems for aerospace guidance control system desig
Lateral static and dynamic aerodynamic parameters of the Kestrel aircraft (XV-6A) extracted from flight data
Flight test data have been used to extract the lateral static and dynamic aerodynamic parameters of the Kestrel aircraft. The aircraft configurations included thrust-jet angles of 0 deg, 15 deg, and 30 deg, and the test Mach numbers were 0.43, 0.62, and 0.82. The results showed that most of the parameters varied linearly with trim normal-force coefficient. The directional stability parameter showed a small increase with increasing trim normal-force coefficient and also with nozzle deflection. The effective-dihedral parameter, the damping-in-roll parameter, and damping-in-yaw parameter all increased (became more negative) with increasing trim normal-force coefficient. For the latter three parameters, the effect of nozzle deflection was dependent on the trim normal-force coefficient
Extraction from flight data of lateral aerodynamic coefficients for F-8 aircraft with supercritical wing
A parameter-extraction algorithm was used to determine the lateral aerodynamic derivatives from flight data for the F-8 aircraft with supercritical wing. The flight data used were the recorded responses to aileron or rudder pulses for Mach numbers of 0.80, 0.90, and 0.98. Results of this study showed that a set of derivatives were determined which yielded a calculated aircraft response almost identical with the response measured in flight. Derivatives extracted from motion resulting from rudder inputs were somewhat different from those resulting from aileron inputs. It was found that the derivatives obtained from the rudder-input data were highly correlated in some instances. Those from the aileron input had very low correlations and appeared to be the more reliable
The control of nonlinear stochastic control systems under discounted performance criteria
Control algorithm for optimization of nonlinear stochastic processes with discounted performance criteri
Longitudinal aerodynamic parameters of the Kestrel aircraft (XV-6A) extracted from flight data
Flight-test data have been used to extract the longitudinal aerodynamic parameters of a vectored-thrust aircraft. The results show that deflecting the thrust past 15 has an effect on the pitching-moment derivatives and tends to reduce the static stability. The trend toward reduction in the longitudinal stability also been noted by the pilots conducting the flight tests
Evaluation of space SAR as a land-cover classification
The multidimensional approach to the mapping of land cover, crops, and forests is reported. Dimensionality is achieved by using data from sensors such as LANDSAT to augment Seasat and Shuttle Image Radar (SIR) data, using different image features such as tone and texture, and acquiring multidate data. Seasat, Shuttle Imaging Radar (SIR-A), and LANDSAT data are used both individually and in combination to map land cover in Oklahoma. The results indicates that radar is the best single sensor (72% accuracy) and produces the best sensor combination (97.5% accuracy) for discriminating among five land cover categories. Multidate Seasat data and a single data of LANDSAT coverage are then used in a crop classification study of western Kansas. The highest accuracy for a single channel is achieved using a Seasat scene, which produces a classification accuracy of 67%. Classification accuracy increases to approximately 75% when either a multidate Seasat combination or LANDSAT data in a multisensor combination is used. The tonal and textural elements of SIR-A data are then used both alone and in combination to classify forests into five categories
Sound Source Localization in a Multipath Environment Using Convolutional Neural Networks
The propagation of sound in a shallow water environment is characterized by
boundary reflections from the sea surface and sea floor. These reflections
result in multiple (indirect) sound propagation paths, which can degrade the
performance of passive sound source localization methods. This paper proposes
the use of convolutional neural networks (CNNs) for the localization of sources
of broadband acoustic radiated noise (such as motor vessels) in shallow water
multipath environments. It is shown that CNNs operating on cepstrogram and
generalized cross-correlogram inputs are able to more reliably estimate the
instantaneous range and bearing of transiting motor vessels when the source
localization performance of conventional passive ranging methods is degraded.
The ensuing improvement in source localization performance is demonstrated
using real data collected during an at-sea experiment.Comment: 5 pages, 5 figures, Final draft of paper submitted to 2018 IEEE
International Conference on Acoustics, Speech and Signal Processing (ICASSP)
15-20 April 2018 in Calgary, Alberta, Canada. arXiv admin note: text overlap
with arXiv:1612.0350
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