Browsing by Author "LING, SF"

Now showing 1 - 7 of 7

A BOUNDARY-ELEMENT-BASED OPTIMIZATION TECHNIQUE FOR DESIGN OF ENCLOSURE ACOUSTICAL TREATMENTS
(1995-07-01)
YANG, TC
;
TSENG, CH
;
LING, SF
;
機械工程學系
;
Department of Mechanical Engineering
AN OPTIMIZATION PROCEDURE OF IDENTIFICATION OF BOUNDARY PARAMETERS OF CANTILEVER BEAMS WITH FLEXIBLE ROOTS FROM EXPERIMENTAL DATA
(1994)
HOU, YC
;
TSENG, CH
;
LING, SF
;
機械工程學系
;
Department of Mechanical Engineering
CONSTRAINED OPTIMIZATION OF ACTIVE NOISE-CONTROL SYSTEMS IN ENCLOSURES
(1994-06-01)
YANG, TC
;
TSENG, CH
;
LING, SF
;
機械工程學系
;
Department of Mechanical Engineering
An effective software design tool is proposed for solving active noise control problems associated with constraints in which the complex strength and location of the secondary source of an active noise control system in an enclosed space are simultaneously optimized. The boundary element method is adopted to evaluate the sound field in enclosures. Furthermore, the boundary used could be of pressure, velocity, or impedance; in addition, the primary source may be at an arbitrary position. An optimizer based on sequential quadratic programming is selected for its accuracy, efficiency, and reliability. Bounds for design variables and proper constraints on the sound field and secondary source can be specified as required. The powerfulness of the proposed tool is demonstrated by optimizing an active control system for an enclosure. For a rectangular cavity, the optimal location of the secondary source is confirmed by observed simulations as always forming a dipole with the primary source situated at off-resonance excitations and subsequently approaching a mirror image position of the primary source at resonance excitations. The optimal location of the controller is found to change with varied upper bounds of the strength of the secondary source. These findings show a discrepancy from those reported in previous researches based on an unconstrained formulation. Sensitivity analysis at the optimum is also included to provide information of practical concern for implementing optimized active noise control systems.
ENHANCING BRANCH-AND-BOUND METHOD FOR STRUCTURAL OPTIMIZATION
(1995-05-01)
TSENG, CH
;
WANG, LW
;
LING, SF
;
機械工程學系
;
Department of Mechanical Engineering
The branch-and-bound method was originally developed to cope with difficulties caused by discontinuous design variables in linear programming. When the branch-and-bound method is applied to solve nonlinear programming (NLP) problems with a large number of mixed discontinuous and continuous design variables, the slow rate of convergence becomes a major drawback of the method. In this study, a number of enhancements are proposed to speed up the rate of convergence of the conventional branch-and-bound algorithm. Three NLP in the form of truss-design examples are tested to compare the capabilities and efficiency of the proposed enhancements. It is shown that of the five criteria for arranging the order in which the design variables are branched, the criterion of maximum cost difference dramatically reduces the number of branch nodes, thereby reducing the total number of continuous-optimization runs executed. Moreover, neighboring search, a branching procedure restricted in the neighborhood of the continuous optimum, is proven to be effective in speeding up the convergence. Investigation also shows that branching several design variables simultaneously is not as efficient as sequentially branching one variable at a time. The proposed enhancements are incorporated along with a sequential quadratic programming algorithm into a software package that is shown to be very useful in the optimal design of engineering structures.
INTEGRATING AND AUTOMATING FINITE-ELEMENT ANALYSIS AND OPTIMIZATION ON PCS
(1994)
PAN, TC
;
LING, SF
;
TSENG, CH
;
機械工程學系
;
Department of Mechanical Engineering
The development of an interface coupling program on PCs for a finite element analysis software system, SAP90, with an optimization software system, MOST, is presented. By controlling and directing the communications, the interface coupling program integrates the two programs while retaining their versatility and interactive features. The integrated system is applied to a numerical example for the minimization of steady-state dynamic loads transmitted from a vehicle exhaust pipe system. The interface coupling program automates, at a relatively low cost, the usually time-consuming iterative process for optimizing an engineering system, while remaining flexible in structural modelling and efficient in equation solving.
ON THE MANUFACTURING TOLERANCE OF DISK CAM PROFILE
(1993-02-01)
WANG, WH
;
TSENG, CH
;
TSAY, CB
;
LING, SF
;
機械工程學系
For a given rocker-roller cam system, the mathematical expression of the cam profile was first derived from the desired displacement function utilizing theory of gearing and differential geometry. Furthermore, the variance in the cam profile due to cutting tolerance was modelled using the Monte-Carlo method as set of normally-distributed random numbers. Based on these models, the deviation from the desired motion resulting from manufacturing imprecision can be calculated by reversing the procedure. An optimization scheme was then employed to identify the optimal configuration which minimizes the motion deviation. It is found that the kinematic error of the mechanism can be minimized if the pressure angle of the mechanism remains small. Also the usefulness of the methodology developed for designing a rocker-roller cam mechanism taking the fabricating error of the cam profiles into consideration is demonstrated.
OPTIMIZATION OF ACTIVE NOISE CONTROL SYSTEMS IN ENCLOSURES
(1993)
YANG, TC
;
TSENG, CH
;
LING, SF
;
機械工程學系
;
Department of Mechanical Engineering