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Aerospace and Electronic Systems, IEEE Transactions on

Issue 5 • Date Sept. 1985

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Displaying Results 1 - 25 of 27
  • Table of contents

    Publication Year: 1985 , Page(s): c1
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  • IEEE Aerospace and Electronic Systems Society

    Publication Year: 1985 , Page(s): c2
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  • From the Editors

    Publication Year: 1985 , Page(s): 593
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  • Stochastic Dynamic System Suboptimal Control with Uncertain Parameters

    Publication Year: 1985 , Page(s): 594 - 600
    Cited by:  Papers (1)
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    The control of a linear system with random coefficients is studied here. The cost function is of a quadratic form and the random coefficients are assumed to be partially observable by the controller. By means of the stochastic Bellman equation, the optimal control of stochastic dynamic models with partially observable coefficients is derived. The optimal control is shown to be a linear function of the observable states and a nonlinear function of random parameters. The theory is applied to an optimal control design of an aircraft landing in wind gust. View full abstract»

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  • Transient Nonstationary Behavior of a Delay Line Discriminator

    Publication Year: 1985 , Page(s): 601 - 609
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    The development of numerical methods for studying the transient nonstationary behavior of a delay line discriminator is presented. Expressions are developed for the mean and the variance of the output noise process. For the cases where the output is stationary, power density spectra are found. View full abstract»

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  • Improved Carrier Tracking by Smoothing Estimators

    Publication Year: 1985 , Page(s): 610 - 618
    Cited by:  Papers (2)
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    Smoothing as a way to improve the carrier phase estimation is proposed and analyzed. The performance of first-and second-order Kalman optimum smoothers are investigated. This perfomance is evaluated in terms of steady-state covariance error computation, dynamic tracking, and noise response. It is shown that with practical amounts of memory, a second-order smoother can have a position error due to an acceleration or jerk step input less than any prescribed maximum. As an example of importance to the NASA deep space network (DSN), a second-order smoother can be used to track the Voyager spacecraft at Uranus and Neptune encounters with significantly better performance than a second-order phaselocked loop. View full abstract»

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  • Surge and Noise Generation in a Forward DC-to-DC Converter

    Publication Year: 1985 , Page(s): 619 - 630
    Cited by:  Papers (15)
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    Switching surge and noise voltages are analyzed under the common-mode condition in a forward dc-to-dc converter. The analysis is performed by partitioning the switching time into several states and introducing the high-frequency equivalent circuits. The equivalent circuits include not only inductive and capacitive parameters, but also the parameters related to the switching speed of the transistor and the recovery characteristics of the diode. As a result, the effects of these various parameters on the surge and noise generation are made clear quantitatively. View full abstract»

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  • Nonlinear Adaptive Control of a Synchronous Machine

    Publication Year: 1985 , Page(s): 631 - 643
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    A nonlinear adaptive controller for a load-commutated brushless dc machine that allows the machine to develop high torque over a wide range of operating conditions, while satisfying voltage and current constraints on both stator and field circuits, is presented. The approach taken is fundamentally different from past work in that a nonlinear control is formulated from the steady-state model of the synchronous machine. Adaptive algorithms are presented for both the unknown load and motor cases. View full abstract»

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  • Nickel-Cadmium Batteries as Capacitive Filters for Pulsed Loads

    Publication Year: 1985 , Page(s): 644 - 653
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    This investigation consisted of several tests of specially fabricated nickel-cadmium batteries having circular disk-type electrodes. These batteries were evaluated as filter elements between a constant current power supply and a 5 Hz pulsed load demanding approximately twice the power supply current during the load on a portion of the cycle. Short tests lasting 104 cycles were conducted at up to a 21 C rate and an equivalent energy density of over 40 J/Ib. In addition, two batteries were subjected to 10h dischar cycles, one at a 6.5 C rate and the other at a 13 C rate. Assuming an electrode-to-battery weight ratio of 0.5, these tests represent an energy density of about 7 and 14 J/Ib, respectively. Energy density, efficiency, capacitance, average voltage, and available capacity were tracked during these tests. After 10y capacity degradation was negligible for one battery and about 20 percent for the other. Cadmium electrode failure may be the factor limiting lifetime at extremely low depth of discharge cycling. The output was examined and a simple equivalent circuit was proposed. View full abstract»

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  • Interference Canceler Array with Reference Generating Loop

    Publication Year: 1985 , Page(s): 654 - 662
    Cited by:  Patents (1)
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    Adaptive arrays utilizing an internally generated reference signal to drive least mean square (LMS) weight determining loops have experienced difficulty arising from phase shifts induced by the reference generating circuits. The phenomenon observed is that the expected value of the weights oscillate in the steady state modulating the incoming signal. A scheme is reported which avoids this problem. It differs from earlier methods in that the reference generator has no infinite limiter so that the amplitude of the reference is not constant and in that one element is left unweighted. Alternative schemes were considered wherein the reference signal is drawn from all the array elements or from the weighted elements only. Only the latter is fully reported here, and is found superior. It is shown that in the presence of a desired signal and independent element noise, the processing scheme proposed produces weights whose expected values converge to a constant nonoscillatory state provided certain mild constraints are satisfied. In particular, if a cos ¿ ¿ 1, a being the gain and ¿ the phase shift of the filter in the reference generator, the weights converge. In addition, the steady state signal-to-noise power ratio (SNR) is determined. It is found that with a cos ¿ close to unity the SNR is that of an (N-1) element array coherently combined, where N is the number of elements. The SNR falls off with departures of a and ¿ from 1 and 0, respectively, but not drastically. View full abstract»

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  • Multidimensional Algebraic Polynomial Approximation

    Publication Year: 1985 , Page(s): 663 - 669
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    A computational algorithm to approximate an n-dimensional function of the form F(x,y,z, ...) by an algebraic polynomial in the least square (LSQ) sense is described. The basis of this algorithm is that the n-dimensional function can be approximated by a set of polynomials in each one of the independent variables x,y,z, ... . This technique is illustrated by deriving the algebraic polynomial approximation in the LSQ sense for three-dimensional functions of the form F(x,y,z). View full abstract»

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  • Error Covariance Analysis of a Karhunen-Loeve Random Field Estimator

    Publication Year: 1985 , Page(s): 670 - 687
    Cited by:  Papers (3)
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    An error covariance analysis of a two-dimensional Karhunen-Loeve random field estimator (KLE) for gridded gravity data is presented without actually using the data. Attention is focused particularly on the north-south deflection component of the disturbance vector so that the rms value of its residual error may not exceed 3 percent of the signal rms for grid spacing of not less than 5 nm, when signal-to-noise ratio in the data is varied within reasonable limits. To achieve this rather stringent goal, a discrete KLE derived entirely from a two-dimensional grid configuration is needed. The KLE for geodesy applications was developed initially by Bose. Using continuous measurements and the orthogonality relations of the Karhunen-Loeve (KL) eigenvectors in a continuous domain, continuous KL gain coefficients ßmnj and consequently the continuous KL gain vector Kmn were obtained; thus a satisfactory continuous KLE was achieved. However the discrete version of the KLE was then given by keeping the old (continuous) ßmnj, and simply computing the KL eigenvectors on the grid coordinates to evaluate the discrete KL gain vector Kmn. Clearly this is not a satisfactory discrete KLE since , ßmnj are not constants but rather depend on the measurement noise variances. So if the measurements are now going to be discrete, one must rederive ßmnj for this situation. View full abstract»

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  • Batch Recursive Data Compression Schemes for INS Error Estimation

    Publication Year: 1985 , Page(s): 688 - 697
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    Application of new data compression schemes to aided inertial navigation systems is presented. The need for data compression is motivated by the fact that the external aiding system generates frequent but inaccurate position measurements, which have to be processed by a processor whose computation capability is limited. Two new data compression techniques are presented and their efficiency is demonstrated through covariance simulation runs as well as computational complexity analysis. These schemes are characterized by their ability to process batches of measurements recursively and efficiently. It is demonstrated that the resulting estimation accuracy is comparable to that produced by a Kalman filter which processes optimally the same amount of data, while the required computational effort is reduced. View full abstract»

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  • Torque, Speed, and Position Control of Induction Machines Using the DQ Model

    Publication Year: 1985 , Page(s): 698 - 710
    Cited by:  Papers (1)
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    New nonlinear controllers for torque, speed, and shaft position of inverter fed induction machines are developed. The controllers are novel because they are based on the full DQ model of the machine and hence account for the nonlinear characteristics of induction machines. In addition, a multivariable control algorithm based on the DQ model is considered. Simulation results for the single input controllers are presented. View full abstract»

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  • The Proper Computation of the Matrix Pseudoinverse and its Impact in MVRO Filtering

    Publication Year: 1985 , Page(s): 711 - 724
    Cited by:  Papers (6)
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    There have been two new algorithms of fairly recent origin offered for the calculation of the matrix pseudoinverse. Unfortunately, nonpathological counterexamples can be constructed, as offered herein, that demonstrate the questionable nature of these two algorithms; however, a resolution is offered here to help prevent possible uncritical propagation of the questionable algorithms. As a rigorous alternative, a well-established technique (endorsed by numerical analysts) is reviewed for calculating the correct matrix pseudoinverse using a computer. Additionally, this technique possesses existent independently verified/validated and assessible software code for a convenient implementation. However, historical loose ends in calculating the associated condition number are singled out here as cause for concern and as a topic for future resolution and refinement. Finally, as the primary motivation for considering these issues, an application example is offered from estimation theory in the implementation and analysis of a minimum variance reduced-order (MVRO) filter having proper performance that critically hinges on the correct computation of the matrix pseudoinverse. While examples of applying MVRO to navigation applications were provided almost a decade ago, a clear indication of the somewhat restrictive conditions of applicability were wanting and so are elucidated here since there appears to be a resurgence of interest in this analytic technique. Another contribution is in providing a tally of the drawbacks to be incurred in using MVRO as well as its previously publicized benefits. View full abstract»

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  • On Sampling the Envelope of a Bandlimited Signal

    Publication Year: 1985 , Page(s): 725 - 728
    Cited by:  Papers (1)
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    For x(t) a generalized bandpass signal, either deterministic or zero-mean, wide sense stationary Gaussian, bandlimited to the frequency region characterized by 0 ¿¿0 - ¿/2 ¿|¿|¿ ¿0 +¿/2 ¿ ¿ with positive frequency bandwidth ¿ > 0, it is shown that the squared envelope of x(t) is lowpass and bandlimited to |¿| ¿¿. This contrasts with earlier results which gave the bandwidth of the squared envelope as 2¿. One consequence of the lower bandwidth is that the squared envelope (and thus the nonnegative envelope itself) can be reconstructed from its samples taken at a rate of ¿/w samples/s. View full abstract»

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  • Hansen's Method Applied to the Inversion of the Incomplete Gamma Function, with Applications

    Publication Year: 1985 , Page(s): 728 - 731
    Cited by:  Papers (2)
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    Hansen's method for obtaining the threshold for a speciried false alarm probability following noncoherent integration after square law detection is applied to finding the inverse of the incomplete gamma function. The method is algebraic and direct, circumventing the necessity for repeated evaluation of an integral or of a finite series. The method is applied to finding any specified percentile of the chi-square distribution and to finding the required signal-to-noise ratio for a specified detection probability of a Swerling II target. View full abstract»

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  • Erratam: Radiation Supported Space Mirror & Ground Radiation Pattern

    Publication Year: 1985 , Page(s): 731
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  • Emendation to "Two Methods of Spectral Estimation for SARSAT Signals"

    Publication Year: 1985 , Page(s): 731
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  • Emendations to "Adaptive Tracker Field-of-View Variation via Multiple Model Filtering"

    Publication Year: 1985 , Page(s): 731 - 732
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  • Emendations to "Particle Velocity Estimation using Kalman Filtering"

    Publication Year: 1985 , Page(s): 732
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  • M. Barry Cariton Award for 1985

    Publication Year: 1985 , Page(s): 733
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  • Information for authors

    Publication Year: 1985 , Page(s): 734
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  • Automation and Robotics for the Space Station: Recommendations

    Publication Year: 1985 , Page(s): 735 - 743
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    On January 25, 1984, President Reagan announced a United States program to place a permanent space station in orbit in 1992. The Congressional bill appropriating the funding for this program requires that a significant portion of the program funds be for the development of new automation and robotics technologies not in use on existing spacecraft. To assist it in developing plans to meet this requirement, NASA established an Automation and Robotics Panel in August 1984. This paper presents verbatim the Executive Summary of the Panel's report to NASA. It should be recognized that this report to NASA is advisory only, and that for a variety of reasons, including funding, what is actually implemented will certainly differ in many respects from the recommendations. Nevertheless, the report represents the thinking of a prestigious group of scholars and practitioners in automation and robotics, and many of the recommendations undoubtedly will be implemented. A summary of the NASA recommendations will be published following their official release. View full abstract»

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  • Call for Pioneer Award Nominations

    Publication Year: 1985 , Page(s): 743-a
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Aims & Scope

IEEE Transactions on Aerospace and Electronic Systems focuses on the equipment, procedures, and techniques applicable to the organization, installation, and operation of functional systems designed to meet the high performance requirements of earth and space systems.

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Meet Our Editors

Editor-in-Chief
Lance Kaplan
Army Research Laboratory