Papers by Keyword: Optimum

Paper TitlePage

Authors: Guo Qiang Li, Yong Qin Liu, Wen Jiang Liu
Abstract: As the optimum of extremum value control system drifts faster it may make bigger error for pre-estimating statically the optimum, it is particularly remarkable if the transfer function of the linear part is with a high order dynamic element. In this paper, a method based on LS(least squares) is presented to pre-estimate dynamically the optimum of extremum value control system. The linear part of controlled plant could be approximated by a cascade of 1st order dynamic element and a pure time delay element as the controlled model is simplified it is successfully resolved for pre-estimating dynamically the optimum of extremum value control system with a high order element by LS.
Authors: You Xin Luo, Wei Yue Xiao
Abstract: The non-equal-interval direct optimum Verhulst GM(1,1) model was built which extended equal interval to non-equal-interval and suited for general data modeling and estimating parameters of direct Verhulst GM(1,1)by optimizing the background value and modified x(n) be taken as initial value. The new model need not pre-process the primitive data, accumulated generating operation (AGO) and inverse accumulated generating operation (IAGO). It was not only suited for equal interval data modeling, but also for non-equal interval data modeling. The new model chooses the modified nth component of X(0) as the starting conditions of the grey differential model. As the new information is fully used, the accuracy of fitting is higher. The example showed that the new model was simple and practical. The new model was worth expanding and applying in test data processing or test on-line monitoring and social science and engineering science.
Authors: Fathallah Elsayed, Hui Qi, Li Li Tong, Mahmoud Helal
Abstract: Recently, submersible pressure hulls with fiber-reinforced multilayer constructions have been developed as substitutes for classical metallic ring-stiffened pressure hulls. The strength and stability is its top priority. In this paper, the optimum design of elliptical composite deep-submerged pressure hull under hydrostatic pressure is investigated based on the finite element analysis to minimize the buoyancy factor of the submersible pressure hull according to the design requirements. Minimize the buoyancy factor of a submarine pressure hull under hydrostatic pressure is proposed as an objective function and the constraints based on the failure strength and the buckling strength of the hulls are considered. The thickness and the fiber orientation angles in each layer, the radii of the ellipse, the stringers dimensions and the operating depth are taken as design variables. Additionally, a sensitivity analysis is performed to study the influence of the design variables up on the Tsai-Wu failure. Results of this study provide a valuable reference for designers of composite underwater vehicles.
Authors: Yong Hua Yang, Jie Wu
Abstract: The mathematical model of optimal design for prestressed structures is established and a two-level algorithm based on hybrid variables is proposed. At the first level, the prestressed forces are chosen to be the design variables and the optimal design for prestressed forces based on continuous variable is carried out. At the second level, the cross-sectional areas are chosen to be the design variables and the discrete sizing optimization is carried out under fixed prestressed forces, the local constrains are satisfied with one-dimensional search algorithm, the integral constrains are satisfied with the relative difference quotient algorithm, and the efficiency of the relative difference quotient algorithm is greatly improved by introducing the assumption of statically determinant structures. The numerical example shows the correctness and effectiveness of the method.
Authors: Mojdeh Shirazi Manesh, Seyed Mohammadali Motavallian, Parviz Fattahi
Abstract: Adaptive Response Surface Methodology (ARSM) is a new developed method sequentially estimates the optimum of a complex function in a gradually reduced design space. In this paper, previously developed approach in ARSM has been compare and contrast with a new approach proposed by authors: using inherited Latin Hypercube Design (LHD) points and generating new Maximin LHD points by solving facility location problems in each iteration. Minimum of the response surface which is a second order approximate model based on LHD points in each iteration is an estimation of the real optimum of the complex function. The computation results reveal that the new suggested approach demonstrate more precise estimation of minimum with less number of function calls compare to the ARSM with random LHDs which is an improvement in the efficiency and accuracy of ARSM.
Authors: Feng Jie Wang
Abstract: The effect of extraction temperature,extraction time,alcohol concentration, ratio of material to liquid (g/ml)on extraction yield of natural yellow pigment from waste almond shell were studied. The optimum conditions were determined by L9 (34) the orthogonal test . The optimum extraction conditions are the extraction temperature at 75°C;the extraction time for 2h; the extraction agent concentration of 20%ethanol ; the material-liquid ration (g/ml) 1:15.The extraction yield of natural yellow pigment from almond shell is 6.25%,The order of effects are extraction temperature>extraction time>ratio of material to liquid(g/ml)>alcohol concentration.This research provides the theoretical basis for the industrial production of the extraction of natural almond shell pigment and provides a new way for the re-use of the abandoned almond shell.
Authors: Xiao Sheng Song, Guo Qiang Xu
Abstract: The influence of fly ash content, water-cement ratio, sand ratio and polycarboxylic acid type water-reducer dosage on the early-strength and performance of C50 concrete is investigated combined with engineering application. The concrete mixture ratio is optimized by the orthogonal experimental design. Concrete strength, slump and slump loss are verified by experiments. Application results show the designed concrete mixture ratio reaches the expected requirements
Authors: Tie Bin Wu, Tao Yun Zhou, Wen Li, Gao Feng Zhu, Yun Lian Liu
Abstract: A particle swarm algorithm (PSO) based on boundary buffering-natural evolution was proposed for solving constrained optimization problems. By buffering the particles that cross boundaries, the diversity of populations was intensified; to accelerate the convergence speed and avoid local optimum of PSO, natural evolution was introduced. In other words, particle hybridization and mutation strategies were applied; and by combining the modified feasible rules, the constrained optimization problems were solved. The simulation results proved that the method was effective in solving this kind of problems.
Authors: Guo Qiang Li, Yong Qin Liu, Wen Jiang Liu
Abstract: As to the optimum of extremum value controlled plant, if the transfer function of its linear part is only with the high order dynamic elements, the optimum of extremum value control system could be dynamically pre-estimated by using the method based on correlation identification we presented, the pre-estimating method has the estimate speed quickly, anti-jamming ability strong, accurate, highly effective and so on the merits. However, if the controlled plant is simultaneously with high order dynamic elements and a large time delay element, the method could not be used directly to pre-estimate dynamically the optimum of the extremum value control system. A new improved pre-estimating method is presented so as to resolve the problem above. After we have in detail analyzed the derivation process of the pre-estimating method we presented, Fully taking into account the effects of large time-delay element, a number of conditions have been improved, the algorithm based on correlation identification has been extended, the optimum of extremum value control system with a large time delay element is well resolved by the extended algorithm.
Authors: Guang Fu Li, Long Shan Wang
Showing 1 to 10 of 14 Paper Titles