有谁会Laplace Transform?

hauzi302

谁可以解释一下给我听，Laplace怎样apply在其他地方？

katami

In DSP, there are 2 kinds of digital filters, FIR and IIR. To design these filters correctly, u need to know the "coefficients" of these filters. To calculate the value of coefficients, using MATLAB, u need to do DFT (for FIR) or z-domain (for IIR). z-domain can be reached by Laplace transform.

FIR filters does not have a feedback, meaning, it does not concern changing of values with time. Thus, using DFT to calculate coefficients in the frequency domain is the way to do it.

IIR filters has a feedback, the reason to have a feedback is to reduce the 'taps' of the filters. Lesser taps, smaller design. Since time is a concern (ie. feedback), DFT is not appropriate because calculation is done in frequency domain, not time-domain. Laplace transform provides a z-domain that can calculate coefficients based on value of the past provided by the feedback. Examples of IIR filters designs are Butterworth, Tschebyshev, elliptical, Bessel, adaptive IIR (Kalman) filters.

Laplace transform also has important application in sensing & control engineering like robots, missile trajectory applications because these systems needs feedbacks to operate.

[ 本帖最后由 katami 于 19-10-2006 01:50 PM 编辑 ]

bomber27

Laplace transform在电路里很好用的。
一般有inductor或capacitor的电路都能用laplace transform，非常方便

jej1887

Laplace transform在考试的时候最好用，因为它可以被用来作考试题目。而且很有挑战性。

mictiong85

LAPLACE transformation可应用在机械的振动运动上。

akito

5/(s+2)^3

这题有可能transform的到吗?

[ 本帖最后由 akito 于 12-3-2007 07:43 PM 编辑 ]

yaahoo

5/(s+2)^3 的‘原函数’可以用性质：L(t^n*f(t))=(-1)^n*[d^n/ds^n]f(s)找到。

Laplace变换的主要用途,如果说是为了解楼上所提到的各个领域中所出现的微分方程式应该也不太夸张吧!