Abstract: The coal plough equipment of traditional choice method has subjective capriciousness question, This paper discuss and analyze the assessment of mining method by entropy value law and gray connection theory, carries on the quantification recursive operation according to the normalizing formula, calculates all levels of membership function separately, it has established the coal plough way gray connection decision-making model. we research and analyze Yangquan coal mining to prove the model, it provide Selection of coal plough decision-making method.
Abstract: Tolerancing is one of the most crucial foundations for industry development and an index of product quality and cost. As tolerance allocation is based on manufacturing costs, this paper proposes a comprehensive method for optimal tolerance allocation with minimum manufacturing cost subject to constraints on dimensional chains and machining capabilities. The general reciprocal power and exponential cost-tolerance models with equality constraints as well as the worst-case and statistical tolerancings are employed in this method. A closed-form solution for the optimization problem by applying Lagrange multipliers is derived. The optimal tolerance allocation problem for reciprocal exponential cost-tolerance model by introducing Lambert W function is demonstrated. For constrained minimization problems with only equality constraints, the optimum design can be obtained by solving simultaneous equations without differentiating. An example is illustrated to demonstrate this approach. The result also shows that tolerance can be allocated economically and accurately using this method. The contribution of this paper is to solve the optimal tolerancing allocation problem by an efficient and robust method with simultaneous active constraints.
Abstract: A program for frequency optimal design of structure composed of bar, beam, plate is developed based on finite analysis system ZR that finite element model, including mesh generation of truss element, beam element and plate element, is automatically generated. Because of integrated with three dimensional CAD, specification of boundary conditions and design variables can be finished based on the three dimensional CAD model, so user need not deal with nodal and element of finite model in the procedure of forming finite model and specifying mathematical problem for optimization. This paper introduces a new method how to insert the frequency sensitivity analysis process into the structural analysis program, integrate mathematical optimization method and design structure based frequency optimization. The program is applied to the optimal design of actual engineering. The results are acceptable.
Abstract: This work is focused on the reduction of the aerodynamic resistance of a microbus. The approach is the three dimensional (3-D) numerical simulation. The RNG k–ε turbulence models are adopted in the computation. Based on the model of SC6350 Chang’an microbus and the improved rear shape, the aerodynamic characteristics of both models at different speeds are studied. Flow maps drawn on the basis of the computed results can offer a reliable method to study the flow field around a microbus. The computed results can give a reference for study of the aerodynamic resistance reduction on a microbus for energy saving. And the results of the optimized shape can provide a theoretical basis for the related research.
Abstract: The simple genetic algorithm (SGA) is taken as the global search method, and the traditional direct search method for mixed-discrete variables as the local search method. The improved (hybrid) genetic algorithm (IGA) is obtained by improving the SGA. And through the introduction of penalty constraints, the problem dealing with the constraints in GA is successfully resolved. A mathematical model for structural optimization of aqueduct is established, and computer software is developed for structural optimization of large-scale aqueduct based on IGA. Using this program, the Shuangji River aqueduct is optimized and Rectangle-sectioned aqueduct design plan is obtained. Compared with the original design plan, optimal design is very economical and was adopted by Design Institute.
Abstract: With the advancement of science and technology and the fast change of buyer requirements, the short-life products have been shortened at large, some formerly long-life products gradually turn to value deterioration products. The ratio of value deterioration products to modern products is getting higher and higher. This paper develops a deterministic economic order quantity EOQ inventory model, where the demand rate depends on the on-hand inventory when inventory level exceeds certain quantity , otherwise the demand rate is constant. The effects of obsolescence are taken into account, for it is related to the demand rate. The results are discussed through two numerical examples. A sensitivity analysis of the optimal solution with respect to parameters of the system is carried out.
Abstract: The present study focuses on the aerodynamics of pickup trucks. The CFD software FLUENT was used to simulate flow field around a pickup truck in this paper. Numerical simulation was taken on a 1/5th pickup truck model. The surface pressure distribution, the wake velocity distribution of the special profiles and the flow structures were obtained. The research indicted that there was a recirculation flow region over the bed for pickup truck. The cab shear layer did not interact directly with the tailgate, flowing above the top of the tailgate. There was a downwash flow in the symmetry plane behind the tailgate with no reverse flow region in the symmetry plane, and the formation of two smaller recirculation flow regions was on both sides of the symmetry plane. Mean flow fields in the near wake of the cab showed a weak pair of counter-rotating vortices behind the cab. In the cross-flow planes behind the tailgate, the mean flow fields show strong counter-rotating vortices behind the tailgate. Instantaneous flow fields in the cross-flow planes of the pickup truck near wake showed compact vortex structures located randomly in space.
Abstract: Several groups of people, representing owner, contractor, designer and consultant, and supervisor of a proposed tunnel, are involved in tunnel construction. As a complex and extra long tunnel is constructed in a tight time schedule, the influence of non-technical factors on the construction of the tunnel is generally much significant. Friendly and effective cooperation between the involved groups are vital to a successful tunnel project. In this paper, we examine the impact of non-technical factors in tunnel construction, in terms of the working procedure of the involved groups in China. The non-technical problems encountered in tunnel construction may be coped with by following a well planned quality controlling cooperation pattern. The improved education of tunnel engineers, in terms of both technical and ethical thoughts, can help to bridge and smooth the interests of the involved groups and technological know-how.
Abstract: The topology optimization and analysis were studied on the area of piston pin boss for a high-speed gasoline engine based on the variable density topology optimization method. Firstly, the model of the variable density topology optimization was founded. Then, the topology optimization and topology deconstruction on the piston pin boss were carried out by using Hyper Works. In this process, the minimum mass of piston was pursued as an objective function and the displacements of specified nodes on the piston skirt were made as constraints. Based on the topology optimization, the piston configuration of curved rod frame was designed. The complex stress of the piston before and after optimization was calculated respectively by ANSYS. The calculation results indicate that the piston mass can be lightened by 30% through optimizing under the same level of maximal stress, with satisfying the strength requirements. Therefore, the aim of piston lightweight is achieved, and there is no stress concentration in the area of the optimizing piston pin boss, which is propitious to the deformation compatibility of the piston pin boss.
Abstract: Reliability Analysis is applied into tower structural design and influence of uncertain factors is considered into the design. The reliability robust optimization mathematical model of tower structure is established by combining the reliability optimization designing theory with the robust design method and injecting reliability sensitivity into the design model. The reliability sensitivity is added to the reliability-based optimization design model and the stiffness reliability-based robust design is reduced to a multi-objection optimization. Take the lattice tower structure for example, after designing, it shows not only lighter weigh, saving in material, simplifying construction, but also improving its safety and stability. The example proves the method to be effective.