نتایج جستجو برای: nyquist criterion

تعداد نتایج: 81430  

Journal: :IEEE Trans. Contr. Sys. Techn. 2003
Alireza Karimi Daniel Garcia Roland Longchamp

A new method for PID controller tuning based on Bode’s integrals is proposed. It is shown that the derivatives of amplitude and phase of a plant model with respect to frequency can be approximated by Bode’s integrals without any model of the plant. This information can be used to design a PID controller for slope adjustment of the Nyquist diagram and improve the closed-loop performance. Besides...

Journal: :Journal of physics. Condensed matter : an Institute of Physics journal 2005
Andrej Vilfan Erwin Frey

Autonomous oscillations in biological systems may have a biochemical origin or result from an interplay between force-generating and visco-elastic elements. In molecular motor assemblies the force-generating elements are molecular engines and the visco-elastic elements are stiff cytoskeletal polymers. The physical mechanism leading to oscillations depends on the particular architecture of the a...

Journal: :Biomedical optics express 2013
J C Ramirez-San-Juan E Mendez-Aguilar N Salazar-Hermenegildo A Fuentes-Garcia R Ramos-Garcia B Choi

Laser Speckle Contrast Imaging (LSCI) is an optical technique used to generate blood flow maps with high spatial and temporal resolution. It is well known that in LSCI, the speckle size must exceed the Nyquist criterion to maximize the speckle's pattern contrast. In this work, we study experimentally the effect of speckle-pixel size ratio not only in dynamic speckle contrast, but also on the ca...

1999
Sanghoon Lee Alan C. Bovik

Utilizing the nonuniform resolution property of the human visual system, foveated video can provide high visual quality relative to non-foveated video by allocating more bits to the central foveation area. In this paper, we present a motion estimation and compensation algorithm for foveated video and measure the performance using a new measure of visual delity termed foveal mean absolute distor...

2002
Gerd Sommerkorn Andreas Richter Walter Wirnitzer

This paper addresses real-time multiple-input-multiple-output (MIMO) radio channel sounding. To avoid expensive transmitter-receiver chains antenna multiplexing is well suited for that application. However, the sequential measurement principle entails different time lags between the antenna channels. We show how the observed impulse responses can be aligned using classical interpolation methods...

Journal: :CoRR 2013
Guangliang Chen Atul Divekar Deanna Needell

Compressive sensing is a methodology for the reconstruction of sparse or compressible signals using far fewer samples than required by the Nyquist criterion. However, many of the results in compressive sensing concern random sampling matrices such as Gaussian and Bernoulli matrices. In common physically feasible signal acquisition and reconstruction scenarios such as superresolution of images, ...

2007
Martin Houde John E. Vaillancourt

We address the question of astronomical image processing from data obtained with array detectors. We define and analyze the cases of evenly, regularly, and irregularly sampled maps for idealized (i.e., infinite) and realistic (i.e., finite) detectors. We concentrate on the effect of interpolation on the maps, and the choice of the kernel used to accomplish this task. We show how the normalizati...

Journal: :Journal of Optics 2022

Abstract Compressed sensing applied to optical microscopy enables imaging with a number of measurements below the Nyquist criterion. The illumination basis selected, often unstructured for randomness considerations, influences performance image reconstruction algorithms. Here, we show through modelling based on multimode fiber that an composed series uniformly spaced foci provides improved robu...

2014
Junwen Zhang Jianjun Yu Yuan Fang Nan Chi

Spectrum efficient data transmission is of key interest for high capacity optical communication systems considering the limited available bandwidth. Transmission of the high speed signal with higher-order modulation formats within the Nyquist bandwidth using coherent detection brings attractive performance advantages. However, high speed Nyquist signal generation with high order modulation form...

2001
J. Alexander Richard M. Murray

Control of vehicle formations has emerged as a topic of significant interest to the controls community. In this paper, we merge tools from graph theory and control theory to derive stability criteria for vehicle formations. The interconnection between vehicles (i.e., which vehicles are sensed by other vehicles) is modeled as a graph, and the eigenvalues of the Laplacian matrix of the graph are ...

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