Optimization design of the stratospheric airship’s power system based on the methodology of orthogonal experiment

The optimization design of the power system is essential for stratospheric airships with paradoxical requirements of high reliability and low weight. The methodology of orthogonal experiment is presented to deal with the problem of the optimization design of the airship’s power system. Mathematical models of the solar array, regenerative fuel cell, and power management subsystem (PMS) are presented. The basic theory of the method of orthogonal experiment is discussed, and the selection of factors and levels of the experiment and the choice of the evaluation function are also revealed. The proposed methodology is validated in the optimization design of the power system of the ZhiYuan-2 stratospheric airship. Results show that the optimal configuration is easily obtained through this methodology. Furthermore, the optimal configuration and three sub-optimal configurations are in the Pareto frontier of the design space. Sensitivity analyses for the weight and reliability of the airship’s power system are presented.     

改进白骨顶鸡优化算法的WSN网络覆盖

为解决二维无线传感器网络随机部署产生的节点分布不均、覆盖率低的问题,提出一种融合元启发式算法的网络部署方案。该方案以节点部署空间作为约束条件、网络覆盖范围作为目标函数对二维网络覆盖模型进行数学建模。针对白骨顶鸡优化算法全局探索能力不强且在迭代后期容易陷入局部最优的缺点,该方案引入复合突变策略和随机反向策略对原算法进行改进。在二维网络覆盖模型进行的仿真测试结果表明:部署改进白骨顶鸡优化算法的二维无线传感器网络不仅网络覆盖率更高,节点也更加均匀,验证了改进白骨顶鸡优化算法解决节点部署问题的有效性和实用性。     

求非线性整数规划的逐次下降方法

In this paper, a new method named as the gradually descent method was proposed to solve the discrete global optimization problem. With the aid of an auxiliary function, this method enables to convert the problem of finding one discrete minimizer of the objective function f to that of finding another at each cycle. The auxiliary function can ensure that a point, except a prescribed point, is not its integer stationary point if the value of objective function at the point is greater than the scalar which is chosen properly. This property leads to a better minimizer of f found more easily by some classical local search methods. The computational results show that this algorithm is quite efficient and reliable for solving nonlinear integer programming problems.     

Reliability based multiobjective optimization for design of structures subject to random vibrations

Based on a multiobjective approach whose objective function （OF） vector collects stochastic reliability performance and structural cost indices, a structural optimization criterion for mechanical systems subject to random vibrations is presented for supporting engineer＇s design. This criterion differs from the most commonly used conventional optimum design criterion for random vibrating structure, which is based on minimizing displacement or acceleration variance of main structure responses, without considering explicitly required performances against failure. The proposed criterion can properly take into account the design-reliability required performances, and it becomes a more efficient support for structural engineering decision making. The multiobjective optimum （MOO） design of a tuned mass damper （TMD） has been developed in a typical seismic design problem, to control structural vibration induced on a multi-storey building structure excited by nonstationary base acceleration random process A numerical example for a three-storey building is developed and a sensitivity analysis is carried out. The results are shown in a useful manner for TMD design decision support.     

高职数控专业复合化教学体系探索

高职数控专业复合化教学体系的构建,首先应明确定位专业培养目标、实践能力目标,然后有针对性地确定能力目标、实践教学的方法和内容,再根据子目标的作用与相互联系,合理设置教学顺序。其实施过程以就业为导向,以职业能力培养为主线,将理论教学内容有效融合到实践教学各环节中,如实验教学、校内实训、校外实习、课程设计、毕业设计等。     

基于增材制造技术的颈动脉仿生血管模型研究现状

系统总结了国内外现有的仿生血管增材制造技术,主要包括微制造技术、间接挤出打印技术、直接挤出打印技术、光固化打印技术和基于模具制造技术,发现这些技术构建的仿生血管表现出从单通道矩形流道形态到分叉圆形流道形态的发展轨迹,并详细分析了这些技术在构建颈动脉仿生血管方面存在的优势和不足。随着复合材料和增材制造技术的持续优化,有望成功构建出真正临床意义上的颈动脉仿生血管模型。     

区域“经济-资源-环境”系统混沌控制模型

为了对区域“经济 -资源 -环境”(Ec-R-Ev)复合系统实现面向协调管理 ,建立了其整体协调度优化模型 .采用结合优化方法与混沌特性分析的自学习方法 ,在系统优化目标和稳定性之间达到平衡 .提出了一种基于协调的复合系统混沌控制模型     

Multi-objective aerodynamic optimization design of high-speed train head shape

To improve the aerodynamic performance of high-speed trains (HSTs) running in the open air, a multi-objective aerodynamic optimization design method for the head shape of a HST is proposed in this paper. A parametric model of the HST was established and seven design variables of the head shape were extracted. Sample points and their exact values of optimization objectives were obtained by an optimal Latin hypercube sampling (opt. LHS) plan and computational fluid dynamic (CFD) simulations, respectively. A Kriging surrogate model was constructed based on the sample points and their optimization objectives. Taking the total aerodynamic drag force and the aerodynamic lift force of the tail coach as the optimization objectives, the multi-objective aerodynamic optimization design was performed based on a non-dominated sorting genetic algorithm-II (NSGA-II) and the Kriging model. After optimization, a series of Pareto-optimal head shapes were obtained. An optimal head shape was selected from the Pareto-optimal head shapes, and the aerodynamic performance of the HST with the optimal head shape was compared with that of the original train in conditions with and without crosswinds. Compared with the original train, the total aerodynamic drag force is reduced by 2.61% and the lift force of the tail coach is reduced by 9.90% in conditions without crosswind. Moreover, the optimal train benefits from lower fluctuations in aerodynamic loads in crosswind conditions.     

Pro/E和ANSYS在结构设计中的应用研究

随着计算机软硬件技术的发展,一个完整的零件设计过程可以通过CAD/CAM技术来完成。而最具代表性的应用软件是Pro/E和ANSYS。Pro/E拥有强大的实体和曲面造型功能,而ANSYS具有完善的有限元分析功能,将两者结合起来使用,可以大大减少人力、物力和财力的消耗,并缩短设计周期。     

A study of airfoil parameterization,modeling, and optimization based on the computational fluid dynamics method

An excellent airfoil with a high lift-to-drag ratio may decrease oil consumption and enhance the voyage. Based on NACA 0012, an improved airfoil is explored in this paper. The class/shape function transformation has been proved to be a good method for airfoil parameterization, and in this paper it is modified to improve imitation accuracy. The computational fluid dynamics method is applied to obtain numerically the aerodynamic parameters of the parameterized airfoil, and the result is proved credible by comparison with available experimental data in the open literature. A polynomial-based response surface model and the uniform Latin hypercube sampling method are employed to decrease computational cost. Finally, the nonlinear programming by quadratic Lagrangian method is utilized to modify the multi-island genetic algorithm, which has an improved optimization effect than the method used on its own. The obtained result shows that the modified class/shape function transformation method produces a better imitation of an airfoil in the nose and tail regions than the original method, and that it will satisfy the tolerance zone of the model in a wind tunnel. The response surface model based on the uniform Latin hypercube sampling method gives an accurate prediction of the lift-to-drag ratio with changes in the design variables. The numerical result of the flow around the airfoil shows reasonable agreement with the experimental data graphically and quantitatively. Ultimately, an airfoil with better capacity than the original one is acquired using the multi-island genetic algorithm based nonlinear programming by quadratic Lagrangian optimization method. The pressure contours and lift-to-drag ratio along with the attack angle have been compared with those of the original airfoil, and the results demonstrate the strength of the optimized airfoil. The process for exploring an improved airfoil through parameterization to optimization is worth referencing in future work.     

无约束全局最优化中的无参数填充函数

The filled function method is an approach for finding a global minimum of multi-dimensional functions.With more and more relevant research,it becomes a promising way used in unconstrained global optimization.Some filled functions with one or two parameters have already been suggested.However,there is no certain criterion to choose a parameter appropriately.In this paper,a parameter-free filled function was proposed.The definition of the original filled function and assumptions of the objective function given by Ge were improved according to the presented parameter-free filled function.The algorithm and numerical results of test functions were reported.Conclusions were drawn in the end.     

信息技术与实践课程有效整合的应用研究——以国际贸易专业实训课程为例

要实现高职国际经济与贸易专业人才培养目标,行之有效的手段就是在实训教学中运用基于信息技术的平台软件.文章在宏观上研究了实践课程应用信息技术的背景、成效、存在的问题以及效用最大化的对策和途径;在微观上,研究了基于信息技术的教学模式、教学策略、实践教学设计、实训软件功能和实践教学效果.     

基于课堂教学的无线表决系统的通信设计

随着信息技术的发展,应用于教学的技术装备也在不断发展。技术装备的应用不仅活跃了课堂教学气氛,也为教学质量的提高提供了保证。根据多年的教学经验发现,师生间的良好互动是充分发挥装备作用的前提,而要实现这一目的,良好的通信必不可少。本文对无线表决系统的功能进行了分析,从通信模块程序设计方面入手,实现通信功能的设计。     

基于权因子变动和约束优化的NURBS曲线形状修改

提出了一种通过约束优化改变控制顶点相应的权因子, 进行NURBS曲线形状修改的新方法. 运用该方法可使得修改后的NURBS曲线满足给定的几何约束, 如单点约束和多点约束. 同时引入了一些自由参数,可以在不破坏几何约束的条件下能进一步改变NURBS曲线的形状,而且能使修改后的曲线形状更自然.由于推导出了明确的公式来计算修改后曲线新的权因子, 因而该方法简单且易于编写程序. 实例表明该方法适用于CAD软件系统.     

地铁车站顶板上翻梁结构设计优化

为了解决地铁车站顶板上翻梁构造引起的上方基坑回填施工困难和管线覆土厚度不足等问题,对地铁车站顶板结构设计进行优化。在充分利用地铁车站结构空间效应和组合梁结构优势的基础上,结合顶板构造特点和施工工艺要求,采用H型钢混凝土组合梁代替传统钢筋混凝土梁,并进行了承载能力和正常使用极限状态验算。结构设计优化结果表明,在降低梁高的前提下,采用组合梁方案既可以提高梁-柱节点的整体性,改善顶板的抗裂性,也为改善车站基坑回填施工条件、提高施工质量创造有利条件。     

家用咖啡机设计要素探析

结合相关理论和企业实际案例,从设计要素技术支持中的结构、功能出发,以设计要素分析中的造型、材料、色彩为突破点,探析家用咖啡机的设计要素。研究表明,结构是基础,功能是属性,造型是导向,材料是提升,色彩是美化。     

Upper bound solution of supporting pressure for a shallow square tunnel based on the Hoek-Brown failure criterion

To analyze the stability of a shallow square tunnel, a new curved failure mechanism, representing the mechanical characteristics and collapsing form of this type of tunnel, is constructed. Based on the upper bound theorem of limit analysis and the Hoek-Brown nonlinear failure criterion, the supporting pressure derived from the virtual work rate equation is regarded as an objective function to achieve optimal calculation. By employing variational calculation to optimize the objective function, an upper bound solution for the supporting pressure and the collapsing block shape of a shallow square tunnel are obtained. To evaluate the validity of the failure mechanism proposed in this paper, the solutions computed by the curved failure mechanism are compared with the results calculated by the linear multiple blocks failure mechanism when the Hoek-Brown nonlinear failure criterion is converted into the Mohr-Coulomb linear criterion. The influences of rock mass parameters on the supporting pressure and collapsing block shape are discussed.     

Single gate optimization for plastic injection mold

This paper deals with a methodology for single gate location optimization for plastic injection mold. The objective of the gate optimization is to minimize the warpage of injection molded parts, because warpage is a crucial quality issue for most injection molded parts while it is influenced greatly by the gate location. Feature warpage is defined as the ratio of maximum displacement on the feature surface to the projected length of the feature surface to describe part warpage. The optimization is combined with the numerical simulation technology to find the optimal gate location, in which the simulated annealing algorithm is used to search for the optimum. Finally, an example is discussed in the paper and it can be concluded that the proposed method is effective.     

工程陶瓷加工技术的应用与发展研究

为了研究工程陶瓷加工技术的发展方向,从工程陶瓷的机械加工技术与特种加工技术2方面,分析了工程陶瓷各种加工技术在实际中的应用,综述了部分国内外专家的研究成果,探讨了各种加工技术的优缺点,提出复合加工技术应是今后的主要发展方向之一的观点,具有一定的实际指导作用。     

An adaptive ant colony system algorithm for continuous-space optimization problems

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