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.

Observer design and detection for nonlinear descriptor systems

Abstract: A nonlinear observer is considered for a class of continuous nonlinear descriptor systems subject to unknown inputs and faults. This class is partly characterized by globally Lipschitz nonlinearities, and a member system may be singular and possibly non-causal. The observer structure chosen makes it useful for both state estimation for feedback controls and residual generation for fault detection. Results on the existence of solutions are given and some useful bounds are derived which are important in the observer design, which is based on a transformed system and on the solution of a Riccati equation. The existence, convergence properties and robustness of the observer are investigated by the use of a quadratic Lyapunov function. Conditions are given for a bound to hold on the norm of the transfer function relating the residual error to the disturbance (linear case). A design algorithm is given and applied to the estimation of the states of a flexible joint robot.

Imaging properties of scanning holographic microscopy

Abstract: Scanning heterodyne holography is an alternative way of capturing three-dimensional information on a scattering or fluorescent object We analyze the properties of the images obtained by this novel imaging process We describe the possibility of varying the coherence of the system from a process linear in amplitude to a process linear in intensity by changing the detection mode We illustrate numerically the properties of the three-dimensional point-spread function of the system and compare it with that of a conventional imaging system with equal numerical aperture We describe how it is possible, by an appropriate choice of the reconstruction algorithm, to obtain an ideal transfer function equal to unity up to the cutoff frequency, even in the presence of aberrations Some practical implementation issues are also discussed

Robust boundary control of an axially moving string by using a PR transfer function

Abstract: In this note, a scheme for the vibration suppression of a translating string using a positive real (PR) transfer function is investigated. The transverse vibration of the string is controlled by hydraulic touch-rolls located at the right end of the string. The mathematical model of the system, which consists of a hyperbolic partial differential equation (PDE) describing the dynamics of the moving string and an ordinary differential equation (ODE) for the actuator dynamics, is derived by using Hamilton's principle for translating continua. The transfer function of the proposed boundary controller is a nonproper but PR function. The asymptotic stability of the closed-loop system in the presence of output disturbance is proved.

On identifiability of linear time-delay systems

Abstract: Identifiability analysis is developed for linear time-delay systems with delayed states, control inputs, and measured outputs, all with a finite number of lumped delays. These systems are governed by linear functional differential equations with uncertain time-invariant parameters and delays. It is shown that the transfer function of such a system admits the online identification if a sufficiently nonsmooth input signal is applied to the system. Sufficiently nonsmooth signals are constructively defined by imposing different smoothness properties on the control input and the state of the system. The required nonsmoothness property is verified independently of any underlying time-delay system.

Inductorless realization of an all-pass transfer function using the current conveyor

Abstract: The use of the second-generation current conveyor as the active element in realizing all-pass transfer functions is illustrated by two circuits.