Author

# Rufus Oldenburger

Other affiliations: Woodward, Inc.

Bio: Rufus Oldenburger is an academic researcher from Purdue University. The author has contributed to research in topics: Nonlinear system & Signal. The author has an hindex of 11, co-authored 37 publications receiving 528 citations. Previous affiliations of Rufus Oldenburger include Woodward, Inc..

##### Papers

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151 citations

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TL;DR: The theory of stabilization developed in this paper explains experimental results reported by R. Oldenburger in 1957, with the aid of Fourier series the designer can determine the periodic signal to be inserted at one point in a loop to yield a desired stabilizing input to a nonlinear element in the loop.

Abstract: The hunt (self-oscillations) of a physical system may often be removed by the introduction of an appropriate stabilizing signal which changes the open loop gain of a closed loop system in a non-linear manner. The theory of stabilization developed in this paper explains experimental results reported by R. Oldenburger in 1957. With the aid of Fourier series the designer can determine the periodic signal to be inserted at one point in a loop to yield a desired stabilizing input to a nonlinear element in the loop. This is illustrated by sinusoidal and triangular inputs to a nonlinear element. An example where a limiter is the only nonlinearity, is employed to illustrate the theory. The input-output characteristics of non-linear elements are in practice always modified by the presence of extra signals such as "noise." Further, nonlinearities are always present in physical systems. The effect of extra signals on nonlinearities and system performance is thus of concern in the general study of physical systems, regardless of whether or not the problem of stability is involved. The results of this paper for the problem of stability extend readily to the problem of system performance for arbitrary disturbances. This paper is to be published in the Proceedings of the First IFAC Moscow Congress by Butterworth Scientific Publications, in 1960.

77 citations

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TL;DR: In this article, the dynamic response of hydraulic line studied from basic water hammer equations, using infinite products, is studied from the point of view of a water hammer equation and infinite products.

Abstract: Dynamic response of hydraulic line studied from basic water hammer equations, using infinite products

48 citations

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48 citations

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01 May 1959

TL;DR: In this paper, a theory is developed to explain the effect of stabilizing feedback loops in states of self-oscillation, which is applied to a system which is linear except for a limiter.

Abstract: FEEDBACK loops, in states of self-oscillation, can often be stabilized by the introduction of an appropriate signal. In this paper a theory is developed to explain this phenomenon. The theory is applied to a system which is linear except for a limiter. Experimental results for the system showing the removal of the hunt by a stabilizing signal are given in a previous paper.1

26 citations

##### Cited by

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TL;DR: This paper provides the first proof of stability of an extremum seeking feedback scheme by employing the tools of averaging and singular perturbation analysis and allows the plant to be a general nonlinear dynamic system whose reference-to-output equilibrium map has a maximum and whose equilibria are locally exponentially stabilizable.

1,222 citations

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TL;DR: In this paper, it was shown that the two main parameters governing the propagation of sound waves in gases contained in rigid cylindrical tubes, are the shear wave number, s = R ρ s ω / μ, and the reduced frequency, k = ωR/a 0, and that most of the most significant analytical solutions for the propagation constant, Γ, as given in the literature, can be expressed as simple expressions in terms of these two parameters.

334 citations

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29 Jul 2010TL;DR: Extremum seeking is a form of adaptive control where the steady-state input-output characteristic is optimized, without requiring any explicit knowledge about this input output characteristic other than that it exists and that it has an extremum as discussed by the authors.

Abstract: Extremum seeking is a form of adaptive control where the steady-state input-output characteristic is optimized, without requiring any explicit knowledge about this input-output characteristic other than that it exists and that it has an extremum. Because extremum seeking is model free, it has proven to be both robust and effective in many different application domains. Equally being model free, there are clear limitations to what can be achieved. Perhaps paradoxically, although being model free, extremum seeking is a gradient based optimization technique. Extremum seeking relies on an appropriate exploration of the process to be optimized to provide the user with an approximate gradient, and hence the means to locate an extremum. These observations are elucidated in the paper. Using averaging and time-scale separation ideas more generally, the main behavioral characteristics of the simplest (model free) extremum seeking algorithm are established.

309 citations

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TL;DR: A review of literature on transient phenomena in liquid-filled pipe systems is presented in this paper, where waterhammer, cavitation, structural dynamics and fluid-structure interaction (FSI) are the subjects dealt with.

286 citations

04 Jan 1974

TL;DR: In this article, it was shown that the two main parameters governing the propagation of sound waves in gases contained in rigid cylindrical tubes, are the shear wave number, s = R ρ s ω / μ, and the reduced frequency, k = ωR/a 0.

Abstract: It is shown that the two main parameters governing the propagation of sound waves in gases contained in rigid cylindrical tubes, are the shear wave number, s = R ρ s ω / μ , and the reduced frequency, k = ωR/a 0 . It appears possible to rewrite the most significant analytical solutions for the propagation constant, Γ, as given in the literature, as simple expressions in terms of these two parameters. With the aid of these expressions the various solutions are put in perspective and their ranges of applicability are indicated. It is demonstrated that most of the analytical solutions are dependent only on the shear wave number, s , and that they are covered completely by the solution obtained for the first time by Zwikker and Kosten (1949) . The full solution of the problem has been obtained by Kirchhoff (1868) in the form of a complicated, complex transcendental equation. In the present paper this equation is rewritten in terms of the mentioned basic parameters and brought in the attractive form F =0, which is solved numerically by using the Newton-Raphson procedure. As first estimate in this procedure the value ofaccording to the solution of Zwikker and Kosten is taken. Results are presented for a wide range of s and k values.

282 citations