The laws describing modern guidance systems are based on the methods of optimal control. This note compares an angular guidance law optimized by the adjoint technique and a metric law comprising an optimal estimator c...
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The laws describing modern guidance systems are based on the methods of optimal control. This note compares an angular guidance law optimized by the adjoint technique and a metric law comprising an optimal estimator connected to a terminal controller forcing the estimated miss distance to zero. The terms of comparison are miss distance and realizability. An analytical solution is given for one specific but significant case.
A simple iterative algorithm has been presented for selecting terminal penalty weighting matrices for linear-quadratic control problems. The algorithm selects a weighting matrix which yields acceptable system performa...
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A simple iterative algorithm has been presented for selecting terminal penalty weighting matrices for linear-quadratic control problems. The algorithm selects a weighting matrix which yields acceptable system performance, while avoiding the large changes in magnitude in final values of the feedback gains. The algorithm is made computationally efficient by using closed-form solutions for the time-varying Riccati equation and the closed-loop system response. The method is heuristic, but offers a systematic approach to terminal weight selection.
This paper addresses the issue of "conservatism" in the time-domain stability robustness bounds obtained by the Lyapunov approach. A state transformation is employed to improve the upper bounds on the linear...
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A useful technique for discrete-time system modeling and control consists of block-diagonalizing the system state matrix. The present paper proposes a new iterative algorithm for accomplishing this objective, and make...
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A useful technique for discrete-time system modeling and control consists of block-diagonalizing the system state matrix. The present paper proposes a new iterative algorithm for accomplishing this objective, and makes a comparison with other algorithms available in the literature.
The applicability of the iterative numerical algorithm of the pulse-spectrum technique (PST) to solve inverse problems of two-dimensional linear diffusion equations is demonstrated. Numerical simulations are carried o...
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The applicability of the iterative numerical algorithm of the pulse-spectrum technique (PST) to solve inverse problems of two-dimensional linear diffusion equations is demonstrated. Numerical simulations are carried out to test the feasibility and to study the general characteristics of this technique without the real measurement data. It is found that PST also gives excellent results and is as robust as for solving the inverse problem of the one-dimensional linear diffusion equation.
The synthesis of a bandpass bandlimited signal with independent AM and PM channels is considered, where the bandwidth of each of the two information signals is required to be less than or equal to half the bandwidth o...
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The synthesis of a bandpass bandlimited signal with independent AM and PM channels is considered, where the bandwidth of each of the two information signals is required to be less than or equal to half the bandwidth of the bandpass signal. A simple iterative algorithm for generation of the bandpass signal is proposed, and sample results are presented. It is shown that this approach may be useful in simultaneous amplitude phase transmission systems even when the number of iterations is small.
This article describes the numerical solution of the elliptic partial differential equations governing three-dimensional fluid flow in strongly curved rectangular ducts by the use of a fully coupled block-implicit sol...
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This article describes the numerical solution of the elliptic partial differential equations governing three-dimensional fluid flow in strongly curved rectangular ducts by the use of a fully coupled block-implicit solution algorithm. It is observed that the coupled solution of the momentum and continuity equations converges rapidly and reduces the required computing time by a factor of 2. 5 over a decoupled solution. The flowfield calculated here is in good agreement with the experimental data and with previous calculations.
There are many applications that require computation of the geodetic coordinates as a function of Earth-Centered Earth-Fixed (ECEF) coordinates in real time (such as the NAVSTAR Global Positioning System). Therefore, ...
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There are many applications that require computation of the geodetic coordinates as a function of Earth-Centered Earth-Fixed (ECEF) coordinates in real time (such as the NAVSTAR Global Positioning System). Therefore, it is highly desirable to find efficient algorithms that can be used in real-time applications. The intent of this Note is to present a new algorithm that is comparable in efficiency to the best described in the literature from the standpoint of the number of elementary operations required per iteration. The proposed method does not require a square-root evaluation within the iterative portion of the algorithm.
The dynamic stability of diffusion flames is studied by generalizing the Burke-Schumann formulation valid for steady-state diffusion flames to the unsteady case and by carrying out a classical linearized stability ana...
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The dynamic stability of diffusion flames is studied by generalizing the Burke-Schumann formulation valid for steady-state diffusion flames to the unsteady case and by carrying out a classical linearized stability analysis, taking care to handle correctly the conditions at the unsteady flame. This article distinguishes between self-excited and damped disturbances by dealing with unsteady transport effects in a limited way. The objective is to extract the needed information without resorting to a full numerical solution of the problem.
This paper extends earlier work by the authors on optimizing an elastic system and its active control. Maneuvers from an initial to a final state in a finite time interval are considered. An active generalized control...
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