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This paper presents an application of the weighted least squares (WLS) method to the design of sharp linear phase finite-impulse response (FIR) digital filters synthesized using a modified frequency-response masking (FRM) structure. In our approach, the original minimax design problem is converted into a WLS problem. The WLS problem is highly nonlinear with respect to the coefficients of the filter. However, it can be decomposed into four linear least squares (LS) problems, each of which can be solved analytically. The design problem is then solved iteratively by using an alternating variable approach. The effectiveness of the method is demonstrated through solving a low-pass linear phase sharp FIR digital filter example. Index Terms--Frequency-response masking (FRM), minimax error, weighted least squares (WLS), alternating variable approach.

In this paper, we formulate a general design of transversal filter structures with maximum relative passband-to-stopband energy ratio subject to complex frequency response constraints in the passband and the stopband as well as additional constraints such as null constraints. These null constraints are important for applications where the suppression of noise at certain frequencies are important. Additional constraints are introduced allowing approximately linear phase and constant group delay in the passband. For a given set of basis functions, the design problem can be formulated as a semi-infinite quadratic optimization problem in the filter coefficients, which are the decision variables to be optimized. In this paper, we focus on the design of digital Laguerre filter and digital finite impulse response (FIR) filter structures. A modified bridging algorithm is developed for searching for the optimum pole of the Laguerre filters. Design examples are given to demonstrate the effectiveness of the proposed algorithm. Index Terms--Bridging method, digital Laguerre filter, group delay constraints, maximum passband-to-stopband energy ratio.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2004.05.028 Byline: X.M. Yang (a)(b), X.Q. Yang (c), K.L. Teo (c) Keywords: Converse duality; Nonlinear programming; Pseudo-invexity; Positive definiteness Abstract: The purpose of this paper is to establish various converse duality results for nonlinear programming with cone constraints and its four dual models introduced by Chandra and Abha [S. Chandra, Abha, A note on pseudo-invex and duality in nonlinear programming, European Journal of Operational Research 122 (2000) 161-165]. Author Affiliation: (a) Department of Mathematics, Chongqing Normal University, Chongqing 400047, China (b) Key Laboratory of Operational Research of Chongqing, Chongqing 400047, China (c) Department of Applied Mathematics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Article History: Received 30 October 2003; Accepted 13 May 2004

A ballistic, coherent transmission system that utilizes the magnetic and electric barriers as Boolen input variables to realize functions similar to the conventional logic gates, is proposed. A device is used to propose construct based on the high-electron-mobility transistor (HEMT) with ferromagnetic (FM) and nonmagnetic (NM) metal gates deposited on top of the HEMT heterostructure.

Solutions to F-convexity under second-order symmetric duality in multiobjective nonlinear programming are examined.

Empirical results of duality theorems, which are used to examine second order F-convexity problems in mathematical programming, are presented.