tailieunhanh - Báo cáo hóa học: " Physically Inspired Models for the Synthesis of Stiff Strings with Dispersive Waveguides"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Physically Inspired Models for the Synthesis of Stiff Strings with Dispersive Waveguides | EURASIP Journal on Applied Signal Processing 2004 7 964-977 2004 Hindawi Publishing Corporation Physically Inspired Models for the Synthesis of Stiff Strings with Dispersive Waveguides I. Testa Dipartimento di Scienze Fisiche Universita di Napoli Federico II Complesso Universitario di Monte S. Angelo 80126 Napoli Italy Email G. Evangelista Dipartimento di Scienze Fisiche Universita di Napoli Federico II Complesso Universitario di Monte S. Angelo 80126 Napoli Italy Email S. Cavaliere Dipartimento di Scienze Fisiche Universita di Napoli Federico II Complesso Universitario di Monte S. Angelo 80126 Napoli Italy Email cavaliere@ Received 30 June 2003 Revised 17 November 2003 We review the derivation and design of digital waveguides from physical models of stiff systems useful for the synthesis of sounds from strings rods and similar objects. A transform method approach is proposed to solve the classic fourth-order equations of stiff systems in order to reduce it to two second-order equations. By introducing scattering boundary matrices the eigenfrequencies are determined and their n1 2 dependency is discussed for the clamped hinged and intermediate cases. On the basis of the frequency-domain physical model the numerical discretization is carried out showing how the insertion of an all-pass delay line generalizes the Karplus-Strong algorithm for the synthesis of ideally flexible vibrating strings. Knowing the physical parameters the synthesis can proceed using the generalized structure. Another point of view is offered by Laguerre expansions and frequency warping which are introduced in order to show that a stiff system can be treated as a nonstiff one provided that the solutions are warped. A method to compute the all-pass chain coefficients and the optimum warping curves from sound samples is discussed. Once the optimum warping characteristic is found the length of the dispersive delay line to be .