We present numerical results of a comparative study of codes for nonlinear and nonconvex mixed-integer optimization. The underlying algorithms are based on sequential quadratic programming (SQP) with stabilization by ...
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We present numerical results of a comparative study of codes for nonlinear and nonconvex mixed-integer optimization. The underlying algorithms are based on sequential quadratic programming (SQP) with stabilization by trust-regions, linear outer approximations, and branch-and-bound techniques. The mixed-integer quadraticprogramming subproblems are solved by a branch-and-cut algorithm. Second order information is updated by a quasi-Newton update formula (BFGS) applied to the Lagrange function for continuous, but also for integer variables. We do not require that the model functions can be evaluated at fractional values of the integer variables. Thus, partial derivatives with respect to integer variables are replaced by descent directions obtained from function values at neighboring grid points, and the number of simulations or function evaluations, respectively, is our main performance criterion to measure the efficiency of a code. Numerical results are presented for a set of 100 academic mixed-integer test problems. Since not all of our test examples are convex, we reach the best-known solutions in about 90 % of the test runs, but at least feasible solutions in the other cases. The average number of function evaluations of the new mixed-integer SQP code is between 240 and 500 including those needed for one-or two-sided approximations of partial derivatives or descent directions, respectively. In addition, we present numerical results for a set of 55 test problems with some practical background in petroleum engineering.
Mathematical programs with vanishing constraints constitute a new class of difficult optimization problems with important applications in optimal topology design of mechanical structures. Vanishing constraints usually...
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Mathematical programs with vanishing constraints constitute a new class of difficult optimization problems with important applications in optimal topology design of mechanical structures. Vanishing constraints usually violate standard constraint qualifications, which gives rise to serious difficulties in theoretical and numerical treatment of these problems. In this work, we suggest several globalization strategies for the active-set Newton-type methods developed earlier by the authors for this problem class, preserving superlinear convergence rate of these methods under weak assumptions. Preliminary numerical results demonstrate that our approach is rather promising and competitive with respect to the existing alternatives.
This paper describes multi-agent based optimal power flow solution in which total production cost is used as the problem objective to be minimized. In this work, simulation of peer-to-peer device coordination has been...
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ISBN:
(纸本)9781457705472;9781457705465
This paper describes multi-agent based optimal power flow solution in which total production cost is used as the problem objective to be minimized. In this work, simulation of peer-to-peer device coordination has been developed using Java Agent Development (JADE) software package. JADE provides a FIPA-compliant agent platform and a package to develop multi-agent systems used in this paper. Six agent types are established. They are i) load agent ii) power generating plants agent, iii) transformer tap-setting agent iv) reactive power agent v) optimal load-flow agent and vi) management agent. In this paper each agent has been modeled as an intelligent agent, which joins to a container to form the multi agent system for solving optimal power flow problems. In this paper, the standard IEEE 6-bus test power system was employed. The results of this proposed system showed that the use of multi-agent systems enables possibility of applying optimal power flow in real-world applications.
This paper presents a sequential tuning of Power System Stabilizers (PSSs) for improving the damping of low frequency electro- mechanical oscillations in a multi-machine power system using parameter - constrained nonl...
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ISBN:
(纸本)9789881925244
This paper presents a sequential tuning of Power System Stabilizers (PSSs) for improving the damping of low frequency electro- mechanical oscillations in a multi-machine power system using parameter - constrained nonlinear optimization algorithm. This algorithm deals with optimization problem using a sequential quadratic programming. The main objective of this procedure is to shift the undamped poles to the left hand side of the s-plane. In the proposed work, the parameters of each PSS controller are determined by sequentially using non-linear optimization technique. The objective of the coordinated parameter tuning is to globally optimize the overall system damping performance by maximize the damping of all both local and inter area modes of oscillations. The results obtained from sequential coordinating tuning method validate the improvement in damping of the overall power system oscillations in an optimal manner. The time domain simulation results of multi-machine power system validate the effectiveness of the proposed approach. In this paper, 10- machine 39- bus New England system is used as the test system. Investigations revealed that the dynamic performance of the system with sequentially tuned PSS is superior to that obtained from the conventionally optimized PSS.
This article presents a general nonlinear formulation for the topology optimization of planar truss structures. The novelty of this article is that element intersection is described in terms of a continuous intersecti...
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This article presents a general nonlinear formulation for the topology optimization of planar truss structures. The novelty of this article is that element intersection is described in terms of a continuous intersection factor. The Heaviside function is used to map the element cross-sectional area to intersection properties. Therefore, the intersection feature is described by a continuous and differentiable function. The topology optimization model is hence set as a ground-structure method by simultaneously including constraints on element intersection and cinematic stability of nodes. The latter is also described by a continuous function. Three test cases are presented to demonstrate the validity of the proposed approach. Unlike mixed integer programming, the number of design cycles does not change much as the number of design variables increases.
In this work, comparative study for dynamic response is carried out for optimized single link flexible robotic manipulator under various types of excitations. Manipulator is considered as an Euler-Bernoulli beam and s...
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ISBN:
(纸本)9783037852620
In this work, comparative study for dynamic response is carried out for optimized single link flexible robotic manipulator under various types of excitations. Manipulator is considered as an Euler-Bernoulli beam and shape is optimized for circular area of cross-section. Finite element method is used to obtain fundamental frequency and sequential quadratic programming (SQP) is used for its maximization.
This paper proposes a hybrid method QPSO-SQP, which combines a quantum-inspired particle swarm evolution algorithm(QPSO) and the sequential quadratic programming (SQP) method to solve large-scale economic dispatch pro...
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ISBN:
(纸本)9783642245527
This paper proposes a hybrid method QPSO-SQP, which combines a quantum-inspired particle swarm evolution algorithm(QPSO) and the sequential quadratic programming (SQP) method to solve large-scale economic dispatch problems(EDPs). Due to the combination of quantum rotation gates and the updating mechanism of PSO, the QPSO has strong search ability and fast convergence speed, therefore it is employed as a global searcher to obtain good solutions for EDPs. As SQP is a gradient-based nonlinear programming method, it is used as a local optimizer to fine tune the best result of the QPSO. The proposed QPSO-SQP is applied to two large-scale EDPs to validate its effectiveness. The experiment results show that the proposed QPSO-SQP can obtain high-quality solutions and produce a satisfactory performance among most existing techniques.
Mathematical programs with vanishing constraints constitute a new class of difficult optimization problems with important applications in optimal topology design of mechanical structures. Vanishing constraints usually...
详细信息
Mathematical programs with vanishing constraints constitute a new class of difficult optimization problems with important applications in optimal topology design of mechanical structures. Vanishing constraints usually violate standard constraint qualifications, which gives rise to serious difficulties in theoretical and numerical treatment of these problems. In this work, we suggest several globalization strategies for the active-set Newton-type methods developed earlier by the authors for this problem class, preserving superlinear convergence rate of these methods under weak assumptions. Preliminary numerical results demonstrate that our approach is rather promising and competitive with respect to the existing alternatives.
According to the nonlinear, multivariable and multi-constraint features of the reentry trajectory optimization problem of airbreathing hypersonic vehicles, a suboptimal solution method is developed. The reentry trajec...
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ISBN:
(纸本)9783037852958
According to the nonlinear, multivariable and multi-constraint features of the reentry trajectory optimization problem of airbreathing hypersonic vehicles, a suboptimal solution method is developed. The reentry trajectory generation is converted to a nonlinear programming (NLP) problem by using Gauss pseudospectral method (GPM). The state and control variables on Gauss nodes are chosen as parameters to be optimized and the minimum total heat absorption is chosen as the optimal performance index. Then the sequential quadratic programming (SQP) method is used to solve the NLP problem. The states of optimized trajectory are compared with the states obtained by the integral of kinetic equations. By simulating on an example of airbreathing hypersonic vehicles, it is demonstrated that the above method is not sensitive to the estimate of motion states and is easier to converge. And the method is effective to solve trajectory optimization problems.
In order to implement the bi-level optimization strategy-collaborative optimization (CO) to bridge design, bridge optimization design process is subdivided into three subsystems in terms of component-oriented decompos...
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ISBN:
(纸本)9783037852798
In order to implement the bi-level optimization strategy-collaborative optimization (CO) to bridge design, bridge optimization design process is subdivided into three subsystems in terms of component-oriented decomposition: superstructure subsystem, bearing subsystem and substructure subsystem. For system level, target function is formulated with the total direct construction cost, and inequality constraints induced relaxation factors are adopted to relax the intersubsystem consistency constraints. For subsystems, target functions are formulated with discrepancy expressions and constraints are formulated according to corresponding codes demands respectively. The feasibility and validity of the proposed approach are examined with an optimization process of reinforcement concrete box girder bridge. Optimization results from proposed approach are compared with that from mono-discipline optimization. The proposed approach shows high computing efficiency than mono-discipline optimization methods when achieving same optimization results.
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