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.

Stroke-based transfer function design

Abstract: In this paper we propose a user interface for the design of 1D transfer functions. The user can select a feature of interest by drawing one or more strokes directly onto the volume rendering near its silhouette. Based on the stroke(s), our algorithm performs a histogram analysis in order to identify the desired feature in histogram space. Once the feature of interest has been identified, we automatically generate a component transfer function, which associates optical properties with the previously determined intervals in the domain of the data values. By supporting direct interaction techniques, which are performed in the image domain, the transfer function design becomes more intuitive compared to the specification performed in the histogram domain. To be able to modify and combine the previously generated component transfer functions conveniently, we propose a user interface, which has been inspired by the layer mechanism commonly found in image processing software. With this user interface, the optical properties assigned through a component function can be altered, and the component functions to be combined into a final transfer function can be selected.

External Calibration of SIR-B Imagery with Area-Extended and Point Targets

Abstract: Data takes on two ascending orbits of the Shuttle Imaging Radar-B (SIR-B) over an agricultural test site in west-central Illinois were used to establish end-to-end transfer functions for conversion of the digital numbers on the 8-bit image to values of the radar backscattering coefficient ?0 (m2/m2) in dB. The transfer function for each data take was defined by the SIR-B response to an array of six calibrated point targets of known radar cross section (transponders) and to a large number of area-extended targets also with known radar cross section as measured by externally calibrated, truck-mounted scatterometers. The radar cross section of each transponder at the SIR-B center frequency was measured on an antenna range as a function of the local angle of incidence. Two truck-mounted scatterometers observed 20-80 agricultural fields daily at 1.6 GHz with HH-polarization and at azimuth viewing angles and incidence angles equivalent to those of the SIR-B. The form of the transfer function is completely defined by the SIR-B receiver and the incoherent averaging procedure incorporated into production of the standard SIR-B image product. Assuming that the processing properly accounts for the antenna gain, all transfer function coefficients are known except for the thermal noise power and a system " constant" that has been shown to vary as a function of uncommanded changes in the effective SIR-B transmit power.

Robust Controllers for Regular Linear Systems with Infinite-Dimensional Exosystems

Abstract: We construct two error feedback controllers for robust output tracking and disturbance rejection of a regular linear system with nonsmooth reference and disturbance signals. We show that for sufficiently smooth signals the output converges to the reference at a rate that depends on the behavior of the transfer function of the plant on the imaginary axis. In addition, we construct a controller that can be designed to achieve robustness with respect to a given class of uncertainties in the system, and we present a novel controller structure for output tracking and disturbance rejection without the robustness requirement. We also generalize the internal model principle for regular linear systems with boundary disturbance and for controllers with unbounded input and output operators. The construction of controllers is illustrated with an example where we consider output tracking of a nonsmooth periodic reference signal for a two-dimensional heat equation with boundary control and observation, and with periodi...

Apparatus and method for analyzing passive circuits using reduced-order modeling of large linear subcircuits

Abstract: A method and apparatus for generating and analyzing a reduced-order model of a linear circuit. The method and apparatus generates the symmetric multi-port transfer function of an RLC circuit. The invention employs a novel symmetric block-Lanczos-type procedure, termed SyMPVL for Symmetric Matrix Pade via Lanczos, to reduce original circuit matrices to a pair of banded symmetric matrices. When the circuit comprises only two of the three RLC components, the matrices are also positive definite. These matrices are typically much smaller than the original circuit matrices and determine a reduced-order model of the original multi-port transfer function of the circuit. The reduced transfer function represents a matrix-Pade approximation of the original multi-port matrix transfer function.

Realization Using the Fornasini-Marchesini Model for Implementations in Distributed Grid Sensor Networks

Abstract: A method for distributed information processing in grid sensor networks using the Fornasini-Marchesini (FM) local state space model has been proposed in the literature recently. The method can be used to implement linear systems in grid sensor networks. It can be shown that, the system matrices of the FM state space model have to satisfy particular conditions for the system to be implementable in real time in a sensor network. This constraint limits the type of systems implementable in real time on sensor networks. A necessary and sufficient condition for a causal transfer matrix to be realizable in the constrained FM model is established. A realization algorithm to derive an FM model that satisfies the desired condition, given an admissible causal transfer matrix, is also derived. The corresponding problem for the realization of noncausal transfer matrices is also addressed.