A modified stiffness spreading method for layout optimization of truss structures

The stiffness spreading method (SSM) was initially proposed for layout optimization of truss structures,in which an artificial elastic material of low modulus is uniformly distributed in the design domain to create connections between discrete members.In this paper,a modified stiffness spreading method is proposed by replacing the artificial elastic material with auxiliary bars to connect real members of the truss structure.Since the background continuum mesh for the elastic material is no longer required,the computational cost is significantly reduced.Like SSM,the new method is advantageous in that an initial design may consist of disconnected bars allocated in the design domain,and mathematical programming methods can be applied for the efficient solution of the formulated optimization problem.A number of solution strategies are also developed to achieve more practical designs with lower computational cost.Numerical examples of both 2-D and 3-D truss structures are presented to demonstrate the feasibility,robustness and effectiveness of the proposed method.

Key Techniques and Applications of Adaptive Growth Method for Stiffener Layout Design of Plates and Shells

The application of the adaptive growth method is limited because several key techniques during the design process need manual intervention of designers. Key techniques of the method including the ground structure construction and seed selection are studied, so as to make it possible to improve the effectiveness and applicability of the adaptive growth method in stiffener layout design optimization of plates and shells. Three schemes of ground structures, which are comprised by different shell elements and beam elements, are proposed. It is found that the main stiffener layouts resulted from different ground structures are almost the same, but the ground structure comprised by 8-nodes shell elements and both 3-nodes and 2-nodes beam elements can result in clearest stiffener layout, and has good adaptability and low computational cost. An automatic seed selection approach is proposed, which is based on such selection rules that the seeds should be positioned on where the structural strain energy is great for the minimum compliance problem, and satisfy the dispersancy requirement. The adaptive growth method with the suggested key techniques is integrated into an ANSYS-based program, which provides a design tool for the stiffener layout design optimization of plates and shells. Typical design examples, including plate and shell structures to achieve minimum compliance and maximum bulking stability are illustrated. In addition, as a practical mechanical structural design example, the stiffener layout of an inlet structure for a large-scale electrostatic precipitator is also demonstrated. The design results show that the adaptive growth method integrated with the suggested key techniques can effectively and flexibly deal with stiffener layout design problem for plates and shells with complex geometrical shape and loading conditions to achieve various design objectives, thus it provides a new solution method for engineering structural topology design optimization.

Multi-Branch Cable Harness Layout Design Based on Genetic Algorithm with Probabilistic Roadmap Method

Current studies on cable harness layouts have mainly focused on cable harness route planning.However,the topological structure of a cable harness is also extremely complex,and the branch structure of the cable harness can affect the route of the cable harness layout.The topological structure design of the cable harness is a key to such a layout.In this paper,a novel multi-branch cable harness layout design method is presented,which unites the probabilistic roadmap method(PRM)and the genetic algorithm.First,the engineering constraints of the cable harness layout are presented.An obstacle-based PRM used to construct non-interference and near to the surface roadmap is then described.In addition,a new genetic algorithm is proposed,and the algorithm structure of which is redesigned.In addition,the operation probability formula related to fitness is proposed to promote the efficiency of the branch structure design of the cable harness.A prototype system of a cable harness layout design was developed based on the method described in this study,and the method is applied to two scenarios to verify that a quality cable harness layout can be efficiently obtained using the proposed method.In summary,the cable harness layout design method described in this study can be used to quickly design a reasonable topological structure of a cable harness and to search for the corresponding routes of such a harness.

Topological Optimization Method for Aeronautical Thin-Walled Component Fixture Locating Layout

Fixture locating layout has a direct and influential impact on aeronautical thin-walled component(ATWC)manufacturing quality.The purpose is to develop a topological optimization method for ATWC fixture locating layout to minimize the manufacturing deformation.Firstly,a topological optimization model that takes the stiffness of ATWC as the objective function and the volume of the locating structure as the constraint is established.Secondly,ATWC and the locating structure are regarded as an integrated entity,and the variable-density method based topological optimization approach is adopted for the optimization of the locating structure using ABAQUS topology optimization module(ATOM).Thirdly,through a subsequent model reconstruction referring to the obtained topological structure,the optimal fixture locating layout is achieved.Finally,a case study is conducted to verify the proposed method and the comparison results with firefly algorithm(FA)coupled with finite element analysis(FEA)indicate that the number and positions of the locators for ATWC can be optimized simultaneously and successfully by the proposed topological optimization model.

A Spacecra Equipment Layout Optimization Method for Diverse and Competitive Design

The spacecraequipment layout optimization design(SELOD)problems with complicated performance con-straints and diversity are studied in this paper.The previous literature uses the gradient-based algorithm to obtain optimized non-overlap layout schemes from randomly initialized cases eectively.However,these local optimal solutions are too dicult to jump out of their current relative geometry relationships,signi􀀀cantly limiting their further improvement in performance indicators.Therefore,considering the geometric diversity of layout schemes is put forward to alleviate this limitation.First,similarity measures,including modi􀀀ed cosine similarity and gaussian kernel function similarity,are introduced into the layout optimization process.Then the optimization produces a set of feasible layout candidates with the most remarkable dierence in geometric distribution and the most representative schemes are sampled.Finally,these feasible geometric solutions are used as initial solutions to optimize the physical performance indicators of the spacecra,and diversi􀀀ed layout schemes of spacecraequipment are generated for the engineering practice.The validity and eectiveness of the proposed methodology are demonstrated by two SELOD applications.

Layout Design-Based Research on Optimization and Assessment Method for Shipbuilding Workshop

The research study proposes to examine a three-dimensional visualization program, emphasizing on improving genetic algorithms through the optimization of a layout design-based standard and discrete shipbuilding workshop. By utilizing a steel processing workshop as an example, the principle of minimum logistic costs will be implemented to obtain an ideological equipment layout, and a mathematical model. The objectiveness is to minimize the total necessary distance traveled between machines. An improved control operator is implemented to improve the iterative efficiency of the genetic algorithm, and yield relevant parameters. The Computer Aided Tri-Dimensional Interface Application （CATIA） software is applied to establish the manufacturing resource base and parametric model of the steel processing workshop. Based on the results of optimized planar logistics, a visual parametric model of the steel processing workshop is constructed, and qualitative and quantitative adjustments then are applied to the model. The method for evaluating the results of the layout is subsequently established through the utilization of AHP. In order to provide a mode of reference to the optimization and layout of the digitalized production workshop, the optimized discrete production workshop will possess a certain level of practical significance.

Development of Fixture Layout Optimization for Thin-Walled Parts:A Review

An increasing number of researchers have researched fixture layout optimization for thin-walled part assembly during the past decades.However,few papers systematically review these researches.By analyzing existing literature,this paper summarizes the process of fixture layout optimization and the methods applied.The process of optimization is made up of optimization objective setting,assembly variation/deformation modeling,and fixture layout optimization.This paper makes a review of the fixture layout for thin-walled parts according to these three steps.First,two different kinds of optimization objectives are introduced.Researchers usually consider in-plane variations or out-of-plane deformations when designing objectives.Then,modeling methods for assembly variation and deformation are divided into two categories:Mechanism-based and data-based methods.Several common methods are discussed respectively.After that,optimization algorithms are reviewed systematically.There are two kinds of optimization algorithms:Traditional nonlinear programming and heuristic algorithms.Finally,discussions on the current situation are provided.The research direction of fixture layout optimization in the future is discussed from three aspects:Objective setting,improving modeling accuracy and optimization algorithms.Also,a new research point for fixture layout optimization is discussed.This paper systematically reviews the research on fixture layout optimization for thin-walled parts,and provides a reference for future research in this field.

Optimal design for buckets layout based on muck removal analysis of TBM cutterhead

The layout of the buckets for tunnel boring machine(TBM)directly affects the muck removal efficiency of cutterhead during excavation.In order to improve the muck removal performance for TBM,the optimal design of bucket layout was investigated.The whole muck transfer process was simulated by discrete-element method(DEM),including the muck falling,colliding,pilling up,shoveling and transferring into the hopper.The muck model was established based on size distribution analysis of muck samples from the water-supply tunnel project in Jilin Province,China.Then,the influence of the bucket number and the interval angle between buckets on muck removal performance was investigated.The results indicated that,as the number of buckets increased from four to eight,the removed muck increased by 29%and the residual volume decreased by 40.5%,and the process became steadier.Different interval angles between buckets were corresponding to different removed muck irregularly,but the residual muck number increased generally with the angles.The optimal layout of buckets for the cutterhead in this tunnel project was obtained based on the simulation results,and the muck removal performance of the TBM was verified by the actual data in the engineering construction.

我国畜牧业空间集聚特征及演化趋势分析

畜牧业区域优化合理布局是农业供给侧改革以及高质量发展的必然要求,该文利用全国各省畜产品产量面板数据,采用空间自相关方法分析畜牧业地理集聚特征,并对其形成原因进行剖析。研究发现:中国畜牧业呈现明显的集聚特征,各省份畜牧业发展受邻近省份发展的影响较为显著;产业空间集聚呈现非均衡特征,东、中部以“高-高”集聚为主,西部以“低-低”集聚特征为主;畜牧业布局相对稳定,未来一段时间内将继续保持现状。基于此,该文提出推动适度规模经营,发展专业化、市场化、一体化产业链,完善畜牧业配套体系等政策建议。

组合桥面板切应力分布规律及横向剪力钉布置

根据组合桥面板截面的切应力、剪力流分布规律,在混凝土板和钢顶板完全连接的条件下,理论推导出混凝土板和钢顶板的剪力流承担比例,证明组合桥面板层间纵向剪力小于采用组合梁公式得到的计算值.层间完全连接和通过弹簧单元模拟剪力钉离散连接开展的有限元计算均支持这一观点,验证了组合桥面板截面的竖向剪力主要由腹板承担的观点的正确性.探究横向上剪力钉的布置方式.结果表明,组合桥面板应沿横向全宽布置剪力钉,在腹板两侧进行加密,腹板正上方不宜布设剪力钉.

洪涝风险与发展潜力视角下村庄居民点布局优化——以福建省长汀县为例

全球气候变化加剧和城镇化快速推进使得洪涝灾害发生频率和破坏性显著升高,为应对洪涝灾害利用风险评估指导村庄居民点布局优化,以福建省长汀县为例,运用模糊综合评价方法划定洪涝风险等级区,通过双重目标决策法对村庄灾害风险和发展潜力进行综合评价,并基于引力模型确定村庄迁移方案。结果表明,长汀县洪涝灾害高风险区域主要分布在以汀州镇与大同镇为主体的集中建设区及以部分村庄居民点,针对高风险村庄居民点,以“避灾”为导向提出了村庄迁移合并方案,实现了村庄居民点布局的适灾和减灾优化调整。对于区域防控洪涝灾害、减少灾害损失具有重要作用,对山地村庄空间防灾减灾规划实施有较强指导意义。

贵州省地热流体资源可开采资源量研究

综合贵州省地热研究相关成果资料,分析贵州省地热流体资源赋存条件及地热水资源分布特征,以此为基础将贵州省划分为110个地热资源量估算区,参照省内地热流体资源主要集中在断裂带周边的实际特点,采用设计布井法、泉(井)流量统计法和比拟法对贵州地热流体可开采资源量进行估算。结果表明:贵州地热流体资源的形成和分布,受省内地质构造特点及其在全国构造所处部位的控制,地热资源成因类型可划分为沉积盆地传导型地热储和隆起山地断裂对流型地热储,总体热储温度一般小于90℃,为低温地热资源;估算出贵州省地热流体可开采资源总量为23190.37 m^(3)/a,其中设计布井法估算的资源量为15926.22 m^(3)/a,天然温泉可开采资源量1183.34 m^(3)/a,地热井可开采资源量6080.80 m^(3)/a,总热能906933.97 Kw,年开采累计可利用热能量476.68×10^(8)MJ。所估算的地热流体可采资源量可为贵州省地热资源的勘查开发规划提供参考依据。

基于遗传算法改进的SLP方法的门诊空间优化研究

以安徽一家三甲医院为例,建立结合人流和功能空间关系等信息的参数化优化模型。基于Grasshopper软件,从不同患者人流路径的最小值、空间关系积分的最大值的视角,结合系统布置设计法(SLP)和遗传算法来优化门诊空间布局,并进行模拟验证,根据实际数据提出优化方法,减轻建筑师在设计阶段的负担。

考虑运营成本和用户体验的电动汽车充电站布局优化模型

针对电动汽车充电站布局优化问题,综合考虑充电站建设运营成本和交通流量变化情况下的用户体验,据此建立充电站布局优化模型。先分析充电站城市土地转让成本、基建及充电设备成本、运营成本各项构成要素,并建立相应的数学模型,再结合交通拥堵指数建立用户体验数学模型,最终以满足充电站建设运营成本最低和用户体验最优为预期目标,建立充电站布局优化模型。引入Tent混沌映射对初始解空间进行均布化,采用AVOA优化算法对该模型进行问题求解。仿真结果表明:与对比文献模型相比,新的充电站选址方案与随机产生的需求点距离更近、更平均;在典型测试场景下,新选址方案可有效降低配电网络的网损率、提升充电站效能,并能为用户提供更优的用户体验,充分说明该模型能够较好解决充电站优化布局问题。

多种布设方式下交流220 kV线路瓷绝缘子劣化判别的仿真与实测研究

为提高线路瓷质绝缘子劣化带电检测的准确性,本文研究了布设方式和劣化程度对高压交流绝缘子串电压分布特征的影响。首先,建立交流220 kV瓷绝缘子串在不同布设方式下单电压分布的有限元仿真计算模型,并仿真分析绝缘子串电压分布的特征。然后,结合实际测量得到的山东省交流220 kV输电线路绝缘子串电压分布,验证仿真计算结果与实测结果的一致性。结果表明:输电电路杆塔塔型、绝缘子串片数及布置方式、劣化绝缘子位置及劣化程度等因素对绝缘子串电压分布特征及劣化判别有较大影响,其中不同塔型最大分布电压差可达到35%。不同布置方式最大分布电压差可达到18%,通过分布电压下降比例可判断不同位置绝缘子劣化情况。

兼顾空间公平和效率的苏州市中心城区社区公园布局测度研究

【目的】社区公园分布面广量大,密切关乎居民生活,聚焦其兼顾空间公平和效率的布局测度难题,以实现社区公园公平配置和高效服务,进而满足城市存量提质改造和增量结构调整的需求。【方法】以苏州市中心城区为例,基于多源数据、居住区分析单元和城市尺度构建测度指标体系,引入CRITIC-熵权法,测度社区公园布局兼顾空间公平和效率的综合指数。【结果】1)中心城区综合指数较低,社区公园与居民分布呈现离散状态,且存在供需错配。2)市辖区综合指数存在明显差异,呈现为姑苏区>工业园区>相城区>吴中区>高新区,空间效率是综合指数的基础,可以保障空间公平的落实;空间公平是提高综合指数的关键,可以推动空间效率的提升。3)构建的测度指标体系及方法能够解决空间效率、空间公平相互关联又矛盾的难题,既可表征二者各自的水平,又能兼顾体现对立统一的相互作用关系。【结论】拓展了社区公园布局的研究视角,为社区公园布局的科学测度提供指标和方法借鉴,助力社区公园调控优化与规划决策。

电动缸举升机构伺服性能的亚全局并行优化设计

针对电动缸举升伺服机构的非线性环节对武器站伺服性能的影响,基于应用背景开展了伺服性能优化方法的研究。针对可设计非线性环节中的增益波动、间隙宽度、不平衡力矩和摩擦力矩进行了作用机理分析;基于机构布局和控制器参数建立了运动学、动力学和控制策略的数学模型、设计约束和目标优化函数;提出了亚全局并行优化方法,对可设计非线性环节进行了基于内点法的多目标优化,解决了局部串行优化的局部最优问题;对基于PI控制器+DOB观测器的复合控制策略进行了单独设计,解决了机械惯量参数、控制器参数和观测器名义模型不匹配的问题。经验证,亚全局并行优化方法的优化结果在整体上更佳,且更加贴合工程实际。

徐州中央国际广场东塔核心筒斜墙收进结构设计

随着楼层的升高,建筑功能发生变化,建筑设计对核心筒尺寸有了缩小的的需求。根据已有工程经验,存在几种常见的缩小核心筒尺寸的方法,徐州中央国际广场东塔采用斜墙的方式实现核心筒内收。该方式使结构及相关构件的受力性能具有一定的特殊性,结构设计中采取了有针对性的结构布置,并且对相关构件的受力性能进行研究,主要包括楼板、楼面梁、扶壁墙以及核心筒外墙的墙肢和连梁等,同时根据受力性能提出相关构件和结构的设计方法。结果表明:经过合理的设计,采用斜墙收进的核心筒结构在抗侧刚度、变形等指标以及罕遇地震作用下的抗震性能均能满足要求,说明斜墙收进是一种合理的结构处理方式。

基于网格矩阵法求解雷达组网优化布站性能指标研究

针对起伏地形环境下雷达布站存在探测盲区难以精确求解组网优化布站性能指标的问题,基于实地数字高程模型数据,提出使用网格矩阵法进行求解,并对网格分辨率变化对精准度的影响进行了探索研究。仿真结果表明,网格分辨率与求解精度和平均计算耗时均成正比,当网格分辨率选择恰当时,性能指标与标准值之间的误差小于5%,为精确求解组网优化布站性能指标提供了新方法。

星源照射多基地雷达系统目标定位建模及精度分析

星源照射多基地雷达系统由一个星载发射源与多个接收站组成,这种一发多收的雷达系统定位精度较单星定位精度高。因为工作体制和构型原因,一发多收雷达系统的定位精度受多种因素影响。为理清多基地雷达系统定位精度的影响因素,文中给出一种典型的一发多收雷达系统定位模型;其次,从几何稀释因子(GDOP)角度出发,对比不同接收站数量对定位精度的影响,发现雷达系统接收站数量为三收或四收时系统效费比较高;然后,研究了不同探测构型所对应的一发三收雷达系统定位精度,发现顶角为120°的Y形布局方式下系统定位精度最优;最后,给出了系统定位精度随目标高度的变化。