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Topic: LTI system theory


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In the News (Mon 12 Nov 18)

  
  PlanetMath: linear time invariant system
State-space equations, which is commonly used in modern control theory and mechanical systems.
Note that all transfer functions are LTI systems, but not all state-space equations are LTI systems.
This is version 8 of linear time invariant system, born on 2004-05-20, modified 2006-09-16.
planetmath.org /encyclopedia/LinearTimeInvariantLTISystems.html   (183 words)

  
 Wavelet Digest, Vol. 1, Nr. 7.   (Site not responding. Last check: 2007-10-13)
Wavelet theory is extended with the new mother mapper operator that efficiently maps a wavelet transform with respect to one mother wavelet to a new wavelet transform with respect to a different mother wavelet.
LTI systems are represented by the one-dimensional (1D)impulse response.
This is analogous to the LTI system model in which the output is a weighted sum of translated replicas of the input signal; with the weights being the LTI system model, the impulse response.
www.ucalgary.ca /~morrow/Wavelets/msg00007.html   (1596 words)

  
 Speed Loop Bandwidth effects on Process Line Eigenvalues
System eigenvalues (or natural frequencies) are defined as the roots of the characteristic polynomial of a system of linear time-invariant (LTI) differential equations.
Given that tension regulation in strip processing systems is performed by an outer tension major loop that cascades into a speed minor loop, the eigenvalues of SPS’s that are obtained without the inclusion of the closed speed loops are not useful to the control system engineer responsible for the design of SPS tension regulators.
If an LTI linear system analysis is used to determine the SPS eigenvalues it can be considered a worst case analysis if the eigenvalues are computed to determine the minimum bandwidth of the speed regulators required to satisfy Observation 2.b.
www.apicsllc.com /apics/Ie_ias97/Ie_ias97s.htm   (1336 words)

  
 LTI system theory - Wikipedia, the free encyclopedia
The output of the system is simply the convolution of the input to the system with the system's impulse response.
Equivalently, any LTI system can be characterized in the frequency domain by the system's transfer function, which is the Laplace transform of the system's impulse response (or Z transform in the case of discrete-time systems).
For all LTI systems, the eigenfunctions, and the basis functions of the transforms, are complex exponentials.
en.wikipedia.org /wiki/LTI_system_theory   (2534 words)

  
 Basics of Discrete-Time Signals and Systems   (Site not responding. Last check: 2007-10-13)
For a rational LTI discrete-time system, the ratio of the Z transform of the output to the Z transform of the input is the same for all possible input sequences.
From continuous-time system theory we know that the imaginary axis in the s plane marks the boundary between the stable region for the poles of H(s) (the left half of the s plane) and the unstable region (the right half of the s plane).
This is the mathematical manifestation of aliasing in discrete-time systems.
www.ece.unh.edu /courses/ece707_3/Docs/Z-Transform/Ztransform.html   (1399 words)

  
 LTI Approach to Adaptive Narrow-Band Feedforward Control
The LTI approach embodied in the unified theory makes it possible to apply established LTI theoretical concepts to the adaptive-feedforward-control design problem, and thus to design stable, high-performance controllers while avoiding the complexities and risks associated with nonlinear and/or time-varying control loops.
The theory is characterized as "unified" because it produces, as special cases, all known instances of LTI adaptive feedforward systems previously reported in the literature.
The theory generalizes the previous results by showing this class of LTI adaptive systems to be considerably larger than it was known to be.
www.nasatech.com /Briefs/Mar98/NPO20184.html   (690 words)

  
 Psychology System Theory   (Site not responding. Last check: 2007-10-13)
The book discusses the popularity of mechanical trading systems, the dangers in system development psychology system theory and how to avoid them, how backtesting of trading systems aid in position sizing, other risk quantification tools, psychology system theory and methods of improving rates of return on investment without significantly increasing risk.
Open system (system theory) - In thermodynamics, an open system is one whose border is permeable to both energy and mass.
LTI system theory - In electrical engineering, specifically in circuits, signal processing, and control theory, LTI system theory investigates the response of a linear, time-invariant system to an arbitrary input signal.
kansascitysports.usamsoc.com /psychologysystemtheory.html   (1058 words)

  
 Disc Drive Spindle Servos
A common nonlinear approach to improve the classical PI system is to clamp and hold the integrator during spin-up.
It should be noted that the solution is only optimal for an LTI system and only in the sense that it minimizes J. This can be written in a general form for a multi-input multi-output controller as equation 19.
In a system with quantization and saturation f(x(k)) is nonlinear.
www.aptronix.com /fuzzynet/applnote/disc.htm   (2799 words)

  
 System response   (Site not responding. Last check: 2007-10-13)
is intimately connected to the response of the system in both the frequency and...
system, the result of the LTI transformation is known as the impulse response...
Now, when a person enters the system, the goal is fitting the system to the resident rather than the other way around.
ferutoblog.tripod.com /system_response.html   (1478 words)

  
 CMU/Language Technologies Institute:Research
The LTI's machine translation efforts within this program are aimed at generating the highest-quality translation by improving statistical, example-based, and transfer-based machine translation systems and producing a multi-engine combination of their outputs which outperforms any single translation system used in the combination.
LTI Question Answering software extracts information from documents in large, open-domain corpora to answer questions in subject areas that are not known in advance.
These systems were instrumental in pushing the technology forward and in proving that tutorial dialogue systems are feasible and useful in realistic educational contexts, although not always provably better on a pedagogical level than the more challenging alternatives to which they have been compared.
www.lti.cs.cmu.edu /Research/cmt-projects.html   (4168 words)

  
 BioMed Central | Full text | Quantifying robustness of biochemical network models
By saying that a system is robust we imply that a particular function or characteristic of the system is preserved despite changes in the operating environment of the system.
Feedback – both negative and positive – control systems are ubiquitous in most biological networks [24] and one of the reasons for using feedback is that it reduces sensitivity of a system's behaviour to its parameter values.
Provided that the homogeneous system is exponentially stable (and this is guaranteed by the existence of a stable limit cycle) and that v is not "too large", the perturbed system's state will remain in a neighbourhood of the origin if the f(x,p) in the original equation is reasonably well behaved in k.
www.biomedcentral.com /1471-2105/3/38   (5067 words)

  
 CMU/LTI: LTISeminar
This prototype PEP system is evaluated by experiments with human decision-making agents who can manipulate the environment to achieve their goals.
The adequacy of the linguistic analysis is reflected by the results obtained at the implementational/computational level, namely the improvement of the space efficiency of the system and its maintainability.
LTI is part of the School of Computer Science at Carnegie Mellon University.
www.cs.cmu.edu /afs/cs.cmu.edu/project/lti-web/LTISeminar/abstract-fall00.html   (2060 words)

  
 A Brief History of Ultra Wideband   (Site not responding. Last check: 2007-10-13)
Instead of characterizing a linear, time-invariant (LTI) system by the more conventional means of a swept frequency response (i.e., amplitude and phase measurements versus frequency), an LTI system could alternatively be fully characterized by its response to an impulsive excitation -- the so-called impulse response h(t).
However, it was not until the advent of the sampling oscilloscope (Hewlett-Packard c.1962) and the development of techniques for subnanosecond (baseband) pulse generation, to provide suitable approximations to an impulse excitation, that the impulse response of microwave networks could be directly observed and measured.
With all the system blocks in place, a short range radar sensor was developed as a pre-collision sensor for the airbag then being touted for use in cars (1972).
www.multispectral.com /history.html   (3668 words)

  
 System Linera Processing » Signal Liear System Motion - Equation System   (Site not responding. Last check: 2007-10-13)
- Liear Systems: where the a_is are elements of the base field of (P) is an example of a Linera system, This can be thought of as being the vector space of elements (a_1,, a_r) or even the projectivisation of Motion Liear design.
- Liear Systems: where the a_is are elements of the base field of (P) is an example of a Linera system, This can be thought of as being the vector space of elements (a_1,, a_r) or even the projectivisation of Processing design.
Linear systems satisfy the properties of superposition and scaling: given two valid inputsas well as their respective outputsthen a linear system must satisfyfor any scalar values and.
www.newschamp.net /education/linear-system.htm   (753 words)

  
 Blind references
The problems caused by deleting are substantial--if you later add the heading again, LTI will not send the matching AR, because according to their copy of your catalog, you have it already.
Apologies to LTI users who are not also III users, but as this thread came up on the LTI list I thought it worthwhile adding a comment here.
Checking blind references as reported by the system is time-consuming but I think worthwhile; in the process we often find and correct a heading used wrongly in a bibliographic record.
home.earthlink.net /~adturner1980/ltiusers/id6.html   (1378 words)

  
 LINEAR SYSTEMS THEORY - EE585
The purpose of this course is to provide the students with the basic tools of modern linear systems theory: stability, controllability, observability, realization theory, state feedback, state estimation, separation theorem, etc.   We develop the continuous and discrete-time cases in parallel.
In 2.5 assume that the system is linear.
In 2.21, assume that the system it at rest for y = q = 0, i.e., that for this configuration the forces exerted by the springs cancel gravity.
www-scf.usc.edu /~hespanha/EE585   (1902 words)

  
 Distortion Isolation in the Time Domain
This, of course, assumes that the system is "approximately linear", and can be said to even have an impulse response when measured at levels low enough to not significantly distort; and at levels high enough to avoid measurement and ambient noise.
The file is played through the system in a dry run, so the user can turn up the volume to the desired levels (usually to where he thinks he hears some objectionable effects) and can adjust the input gain levels of the measurement system (in the "Levels Form") to optimize its dynamic range.
This impulse response should be made immediately before the acquisition of the actual output of the system, to reduce the possibility of changes in air pressure, microphone position, or electronic component drift causing error in the calculated LTI portion.
www.libinst.com /distortion_isolation_in_the_time.htm   (3095 words)

  
 Graduate Studies : Birzeit University : Palestine   (Site not responding. Last check: 2007-10-13)
Thermodynamic equilibrium and statistical mechanics, ensemble theory, partition functions, applications to ideal gas and crystals, theories of simple liquids, Monte Carlo and molecular dynamics simulations, reaction dynamics from a microscopic viewpoint.
An overview of real time systems and their applications, terminology, problems and architectures, sensors and actuators, modeling of real-time systems, real-time operating system kernels, architecture of micro-controllers, real-time communications, scheduling algorithms, and applications.
Signals, Gram-Schmidt orthogonalization, linear time invariant systems (LTI), the sampling theorem, modeling of discrete systems in t, z, and w-domain, design and implementation of FIR and IR digital filters, linear filtering methods algorithms, DFT discrete convolution, FFT-algorithms, spectrum estimation, multirate DSP, linear prediction, optimal filters, Least square methods.
www.birzeit.edu /academics/faculties/comp-science   (995 words)

  
 4th Continuous Discrete Edition Signal System   (Site not responding. Last check: 2007-10-13)
Discrete system - A discrete system or discrete-time system, as opposed to a continuous-time system, is one in which the signals are sampled periodically.
It is usually used to connote an analog sampled system, rather than a digital sampled system, which uses quantized values.
That's the ruling of the world and the computer systems, the lack of paper-based methods of counting votes would have to be extended gradually.
so98.iasoft.org /4thcontinuousdiscreteeditionsignalsystem.html   (1378 words)

  
 [No title]
The goal of the course is to teach basic DSP theory as well as principles specific to the implementation of DSP algorithms on a fixed-point processor.
DSP system theory: common notation linear, time-invariant (LTI) system theory, sampling theory, quantization and finite word length effects, FIR filters and convolution, basic Fourier analysis and frequency response, IIR filters, z-transforms, fixed-point arithmetic, and fixed-point filters.
In a typical university course, there is a great emphasis on the underlying theory, with applications being presented primarily to motivate the theory.
www.ece.gatech.edu /research/labs/cadsp/Publications/MD8-1.doc   (2591 words)

  
 Signals, Systems, and Control Demonstrations
System Properties The user applies input signals to a selected, unknown system - either continuous time or discrete time - to determine whether the system is linear, time invariant, causal, stable, and memoryless.
A Java applet that invites the user to select an LTI system, sketch an input signal with the mouse, and observe the output signal in real time.
Then drag open-loop system poles and zeros with the mouse to track the reference while rejecting the disturbance and noise.
www.jhu.edu /~signals/index.html   (1295 words)

  
 [No title]
A time-delay system:      EMBED Equation.3  Spectral density functions: Autospectral density function (autospectrum): The autospectral density function Sxx(f) of a random signal X(t) is a measure of its frequency distribution.
In addition, the autocorrelation function approaches the sine wave process as the bandwidth decreases, a conclusion that can easily be drawn using LTI system theory for deterministic systems.
LTI Systems Introduction: LTI systems are analyzed using the correlation/spectral technique.
www.csus.edu /indiv/n/ngw/EEE-243/Corr_Spectral.doc   (1354 words)

  
 Tutorial for Control System Toolbox for MATLAB by Finn Haugen, TechTeach
Given a closed-loop system with negative feedback and loop transfer function k*L0(s), where k is a constant.
The system is to be controlled by state-feedback: u=-Gx where G is a matrix of gains.
In this case, it is assumed that the system is given by a discrete-time state-space model in the form of an LTI-object.
techteach.no /publications/control_system_toolbox   (3089 words)

  
 CAIMS2005: Signal Processing
In this theme, signal processing is also put in the context of the emerging autonomic computing (AC) [3,4] systems which are evolving earnestly because the cost-performance of hardware improvements (speed and capacity) have lead to escalating complexity of software (features and interfaces).
Since many real-world physical systems are time varying, complex (high-dimensional), nonlinear, statistically nonstationary, non-Gaussian, nonlocal, sometimes chaotic, and subjected to unwanted signals (noise), the classical SSP must be augmented by ISP.
In contrast to the well-established LTI system theory, the nonlinear scale invariant (NSI) system theory and applications are still developing.
www.umanitoba.ca /institutes/iims/caims2005_theme_signal.shtml   (820 words)

  
 Electrical & Computer Engineering  College of Engineering  - University of Massachusetts Dartmouth
Topics include time domain analysis of discrete-time linear time-invariant (LTI) systems, solution of difference equations, system function and digital filters, stability and causality, discrete-time Fourier series, discrete-time Fourier transform and discrete Fourier transforms, z-transforms, sampling and the sampling theorem, discrete-time state equations, and communication systems.
Circuit theory and its relationship to electromagnetics is presented as an approximate form of Maxwell’s equations.
Topics include the propagation of uniform plane electromagnetic waves in free space and in various media (including wave reflection and refraction, and skin effect), transmission-line theory using frequency- and time-domain analysis, analysis of waveguides and electromagnetic resonators, and fundamentals of radiation and antennas.
www.umassd.edu /engineering/ece/courses/lvl_300.cfm   (802 words)

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