Topic
Transfer function
About: Transfer function is a research topic. Over the lifetime, 14362 publications have been published within this topic receiving 214983 citations. The topic is also known as: system function & network function.
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01 Jan 1995
TL;DR: This paper presents an introduction to magnetic circuit analysis SPICE for basic circuits, the convolution method resonant and bandpass circuits magnetically coupled circuits and transformers and the principles of basic filtering Fourier series with applications to electronic circuits.
Abstract: Lapice transfrom analysis- basics Laplace transfrom analysis - circuit applications Laplace transform analysis - transfer function applications time domain circuit response computations the convolution method resonant and bandpass circuits magnetically coupled circuits and transformers two-ports analysis of interconnected two-ports principles of basic filtering Fourier series with applications to electronic circuits. Appendices: introduction to magnetic circuit analysis SPICE for basic circuits.
92 citations
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TL;DR: In this paper, a statistical method for modeling the linear and quadratically nonlinear relationship between fluctuations monitored at two points in space or time in a turbulent medium is presented, which is valid for non-Gaussian "input" and "output" signals.
92 citations
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TL;DR: It is proved that a impedance passive system is well-posed if and only if it is proper, and that, just as in the finite-dimensional case, if the authors apply negative output feedback to a proper impedance Passive system, then the resulting system is (energy) stable.
Abstract: Let U be a Hilbert space. By an ℒ (U)-valued positive analytic function on the open right half-plane we mean an analytic function which satisfies the condition . This function need not be proper, i.e., it need not be bounded on any right half-plane. We study the question under what conditions such a function can be realized as the transfer function of an impedance passive system. By this we mean a continuous-time state space system whose control and observation operators are not more unbounded than the (main) semigroup generator of the system, and, in addition, there is a certain energy inequality relating the absorbed energy and the internal energy. The system is (impedance) energy preserving if this energy inequality is an equality, and it is conservative if both the system and its dual are energy preserving. A typical example of an impedance conservative system is a system of hyperbolic type with collocated sensors and actuators. We give several equivalent sets of conditions which characterize when a system is impedance passive, energy preserving, or conservative. We prove that a impedance passive system is well-posed if and only if it is proper. We furthermore show that the so-called diagonal transform (which may be regarded as a slightly modified feedback transform) maps a proper impedance passive (or energy preserving or conservative) system into a (well-posed) scattering passive (or energy preserving or conservative) system. This implies that, just as in the finite-dimensional case, if we apply negative output feedback to a proper impedance passive system, then the resulting system is (energy) stable. Finally, we show that every proper positive analytic function on the right half-plane has a (essentially unique) well-posed impedance conservative realization, and it also has a minimal impedance passive realization.
91 citations
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TL;DR: In this article, a non-stationary generalization of the spectral representation theorem is proposed to derive unconditional statistics of interest in groundwater flow and transport applications, which can accomodate boundary conditions, spatially variable mean gradients, measurement conditioning, and other sources of nonstationarity.
Abstract: Stochastic analyses of groundwater flow and transport are frequently based on partial differential equations which have random coefficients or forcing terms. Analytical methods for solving these equations rely on restrictive assumptions which may not hold in some practical applications. Numerically oriented alternatives are computationally demanding and generally not able to deal with large three-dimensional problems. In this paper we describe a hybrid solution approach which combines classical Fourier transform concepts with numerical solution techniques. Our approach is based on a nonstationary generalization of the spectral representation theorem commonly used in time series analysis. The generalized spectral representation is expressed in terms of an unknown transfer function which depends on space, time, and wave number. The transfer function is found by solving a linearized deterministic partial differential equation which has the same form as the original stochastic flow or transport equation. This approach can accomodate boundary conditions, spatially variable mean gradients, measurement conditioning, and other sources of nonstationarity which cannot be included in classical spectral methods. Here we introduce the nonstationary spectral method and show how it can be used to derive unconditional statistics of interest in groundwater flow and transport applications.
91 citations
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TL;DR: In this paper, a two-control-volume model is employed for honeycomb-stator/smooth-rotor seals, with a conventional control-volume used for the throughflow and a capacitance-accumulator model for the honeycomb cells.
Abstract: A two-control-volume model is employed for honeycomb-stator/smooth-rotor seals, with a conventional control-volume used for the throughflow and a capacitance-accumulator model for the honeycomb cells. The control volume for the honeycomb cells is shown to cause a dramatic reduction in the effective acoustic velocity of the main flow, dropping the lowest acoustic frequency into the frequency range of interest for rotordynamics. In these circumstances, the impedance functions for the seals cannot be modeled with conventional (frequency-independent) stiffness, damping, and mass coefficients. More general transform functions are required to account for the reaction forces, and the transfer functions calculated here are a lead-lag term for the direct force function and a lag term for the cross-coupled function. Experimental measurements verify the magnitude and phase trends of the proposed transfer functions. These first-order functions are simple, compared to transfer functions for magnetic bearings or foundations. For synchronous response due to imbalance, they can be approximated by running-speed-dependent stiffness and damping coefficients in conventional rotordynamics codes. Correct predictions for stability and transient response will require more general algorithms, presumably using a state-space format.
91 citations