A* algorithm and ant colony optimization (ACO) are more widely used in path planning among global path planning algorithms. The optimization process is analyzed and summarized from the principles and characteristics of the two algorithms, A* algorithm is mainly optimized in terms of point selection and improvement of heuristic function; and ACO is mainly investigated in terms of transfer probability and pheromone positive feedback for improvement and optimization. Taking a single algorithm solving complex optimization problems difficulties into consideration, a splitting strategy can be used. So that local path or intelligent path optimization algorithms are incorporated in global path planning to improve search efficiency and optimization quality.
suggested the initial direction of using LF captures to remove reflections.• The idea to identify background and reflection edges based on their relative depths to camera focus was co-developed by Dr. Jie Chen and me. The means to recover backgrounds and reflections from their partial edges identified was devised by me. • Experiments were carried out by me. Data used were collected/synthesized by me.
The paper analyzes the length variety of the crystal gain and sub-crystal gain of magnesium alloy materials during the strain amplitude augmentation in the linearity stage of the material deformation, and then based on G-L model derives the mathematical model of the damping variety durign the strain amplitude augmentation in the linearity strain stage of the magnesium alloys. Consequently, magnesium alloy damping mechanism is studied theoretically. It is proved that the magnesium alloy material has the advantages of high damping capacities. In addition, a comparison test in terms of damping performance is made between magnesium alloy and other alloys, which further confirms the high damping of magnesium alloy and the rightness of the theoretical deduced conclusion.
<abstract> <p>This paper proposes an approach for the topological design of continuum structures with global stress constraints considering self-weight loads. The rational approximation of material properties is employed to describe the material distribution for overcoming the parasitic effect for low densities. The structure volume is used as the objective function to be minimized. The local stress constraints for all elements are aggregated into a global stress constraint using the improved <italic>P</italic>-norm method. A model for the stress-constrained topology optimization of continuum structures considering the self-weight loads is established. The projection filtering method is adopted to avoid numerical instability, and the topology optimization problems are solved using the method of moving asymptotes. Several numerical examples are presented to demonstrate the validity of the proposed method. The structures obtained by the proposed method can have better performance. The effects of different norm parameters, stress constraints and mesh densities on the topological structures are analyzed.</p> </abstract>
Accurate determination of flow stress and friction factor is the guarantee of accuracy for finite element analysis of metal extrusion. Firstly, flow stress equation parameters for materials test were initially decided in order to perform finite element analogy. Then, the simulation values and experiment values were compared and the iterative optimization algorithm was used to amend the parameters. The objective was that value error of simulation and experiment values was controlled within tolerance. Finally, accurate flow stress and friction factor were determined. In rod-rod composite extrusion experiment of pure lead,it is determined by inverse analysis that the material strength coefficient is 11.9, strain hardening exponent is 0.127,and friction factor is 0.18. The comparison of the load-stroke curve between simulation and experiment and pure lead upsetting test contribute to confirm that the measured data is accurate. The results show that inverse analysis is a precise, simple and practical method for measuring flow stress and friction factor.
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