Finding Symbolic and All Numerical Solutions for Design Optimization Based on Monotonicity Analysis and Solving Polynomial Systems

A method for determining symbolic and all numerical solutions in design optimization based on monotonicity analysis and solving polynomial systems is presented in this paper. Groebner Bases of the algebraic system equivalent to the subproblem of the design optimization is taken as the symbolic (analytical) expression of the optimum solution for the symbolic optimization, i.e. the problem with symbolic coefficients. A method based on substituting and eliminating for determining Groebner Bases is also proposed, and method for finding all numerical optimum solutions is discussed. Finally an example is given, demonstrating the strategy and efficiency of the method.

Stability analysis of underground engineering based on multidisciplinary design optimization

Aiming at characteristics of underground engineering,analyzed the feasibility of Multidisciplinary Design Optimization (MDO) used in underground engineering,and put forward a modularization-based MDO method and the idea of MDO to resolve problems in stability analysis,proving the validity and feasibility of using MDO in underground engi- neering.Characteristics of uncertainty,complexity and nonlinear become bottle-neck to carry on underground engineering stability analysis by MDO.Therefore,the application of MDO in underground engineering stability analysis is still at a stage of exploration,which need some deep research.

Numerical and Experimental Analysis of A Ducted Propeller Designed by A Fully Automated Optimization Process Under Open Water Condition

A fully automated optimization process is provided for the design of ducted propellers under open water conditions, including 3D geometry modeling, meshing, optimization algorithm and CFD analysis techniques. The developed process allows the direct integration of a RANSE solver in the design stage. A practical ducted propeller design case study is carried out for validation. Numerical simulations and open water tests are fulfilled and proved that the optimum ducted propeller improves hydrodynamic performance as predicted.

Failure mechanism of directional roof cutting and design method optimization

Directional roof cutting(DRC)is one of the key techniques in non-pillar coal mining with self-formed entries(NCMSE)mining method.Due to the inability to accurately measure the expansion coefficient of the goaf rock mass,the implementation of this technology often encounters design challenges,leading to suboptimal results and increased costs.This paper establishes a structural analysis model of the goaf working face roof,revealing the failure mechanism of DRC,and clarifies the positive role of DRC in improving the stress of the roadway surrounding rock and reducing the subsidence of the roof through numerical simulation experiments.On this basis,the paper further analyses the roadway pressure and roof settlement under different DRC design heights,and ultimately proposes an optimized design method for the DRC height.The results indicate that the implementation of DRC can significantly optimize the stress environment of the working face roadway surrounding rock.At the same time,during the application of DRC,three scenarios may arise:insufficient,reasonable,and excessive DRC height.Insufficient height will significantly reduce the effectiveness of the technology,while excessive height has little impact on the implementation effect but will greatly increase construction costs and difficulty.Engineering verification shows that the optimized DRC design method proposed in this paper reduces the peak stress of the protective coal pillar in the roadway by 27.2%and the central subsidence of the roof by 41.8%,demonstrating excellent application results.This method provides technical support for the further promotion of NCMSE mining method.

Aerodynamic design optimization by using a continuous adjoint method

This paper presents the fundamentals of a continuous adjoint method and the applications of this method to the aerodynamic design optimization of both external and internal flows.General formulation of the continuous adjoint equations and the corresponding boundary conditions are derived.With the adjoint method,the complete gradient information needed in the design optimization can be obtained by solving the governing flow equations and the corresponding adjoint equations only once for each cost function,regardless of the number of design parameters.An inverse design of airfoil is firstly performed to study the accuracy of the adjoint gradient and the effectiveness of the adjoint method as an inverse design method.Then the method is used to perform a series of single and multiple point design optimization problems involving the drag reduction of airfoil,wing,and wing-body configuration,and the aerodynamic performance improvement of turbine and compressor blade rows.The results demonstrate that the continuous adjoint method can efficiently and significantly improve the aerodynamic performance of the design in a shape optimization problem.

Containership Structural Design and Optimization Based on Knowledge-Based Engineering and Gaussian Process

Knowledge-based engineering(KBE) has made success in automobile and molding design industry, and it is introduced into the ship structural design in this paper. From the implementation of KBE, the deterministic design solutions for both rules design method(RDM) and interpolation design method(IDM) are generated. The corresponding finite element model is generated. Gaussian process(GP) is then employed to build the surrogate model for finite element analysis, in order to increase efficiency and maintain accuracy at the same time, and the multi-modal adaptive importance sampling method is adopted to calculate the corresponding structural reliability.An example is given to validate the proposed method. Finally, the reliabilities of the structures' strength caused by uncertainty lying in water corrosion, static and wave moments are calculated, and the ship structures are optimized to resist the water corrosion by multi-island genetic algorithm. Deterministic design results from the RDM and IDM are compared with each separate robust design result. The proposed method shows great efficiency and accuracy.

Optimization design of anti-seismic engineering measures for intake tower based on non-dominated sorting genetic algorithm-Ⅱ

High-rise intake towers in high-intensity seismic areas are prone to structural safety problems under vibration.Therefore,effective and low-cost anti-seismic engineering measures must be designed for protection.An intake tower in northwest China was considered the research object,and its natural vibration characteristics and dynamic response were first analyzed using the mode decomposition response spectrum method based on a three-dimensional finite element model.The non-dominated sorting genetic algorithm-II(NSGA-II)was adopted to optimize the anti-seismic scheme combination by comprehensively considering the dynamic tower response and variable project cost.Finally,the rationality of the original intake tower antiseismic design scheme was evaluated according to the obtained optimal solution set,and recommendations for improvement were proposed.The method adopted in this study may provide significant references for designing anti-seismic measures for high-rise structures such as intake towers located in high-intensity earthquake areas.

Sequential ensemble optimization based on general surrogate model prediction variance and its application on engine acceleration schedule design

The Efficient Global Optimization(EGO)algorithm has been widely used in the numerical design optimization of engineering systems.However,the need for an uncertainty estimator limits the selection of a surrogate model.In this paper,a Sequential Ensemble Optimization(SEO)algorithm based on the ensemble model is proposed.In the proposed algorithm,there is no limitation on the selection of an individual surrogate model.Specifically,the SEO is built based on the EGO by extending the EGO algorithm so that it can be used in combination with the ensemble model.Also,a new uncertainty estimator for any surrogate model named the General Uncertainty Estimator(GUE)is proposed.The performance of the proposed SEO algorithm is verified by the simulations using ten well-known mathematical functions with varying dimensions.The results show that the proposed SEO algorithm performs better than the traditional EGO algorithm in terms of both the final optimization results and the convergence rate.Further,the proposed algorithm is applied to the global optimization control for turbo-fan engine acceleration schedule design.

基础隔震结构附加变化型调谐质量惯容阻尼器的优化设计研究

在强震作用下基础隔震结构的隔震层将发生非常大的水平变形。已有研究表明采用在基础隔震结构的隔震层附加变化型调谐质量阻尼器(VTMD)的混合控制策略能够有效降低隔震层的水平变形需求,然而该混合控制策略最大的缺陷在于需要很大的调谐质量。考虑到惯容装置具有明显的质量放大效应,本文提出将惯容装置(Inerter)与VTMD中的阻尼器并联,从而形成具有较小调谐质量的变化型调谐质量惯容阻尼器(VTMDI),并将其附加在基础隔震结构的隔震层,基于随机振动的分析框架开展了VTMDI参数的优化设计研究。研究表明直接将基础隔震结构的上部结构层间变形作为优化目标的传统优化策略并不经济有效。为此,本文提出了一种基于两步优化法的优化策略,该优化策略首先确保附加VTMDI的基础隔震结构相对于附加相同阻尼的基础隔震结构具有更优的控制效果;然后确保附加VTMDI的基础隔震结构的上部结构层间变形最小。通过动力时程分析结果表明:两种优化策略都能有效降低隔震层的水平变形和上部结构的层间变形,同时不会导致调谐质量出现过大的运动行程,基于两步优化法的优化策略更为经济有效。

铁路工程建设可持续供应链网络集成优化研究

随着国家对铁路工程项目可持续发展的日益重视,迫切需要先进且集成的供应链网络设计方案理论与方法来提高供应链效率、可持续绩效以及资源利用率。实施可持续供应链网络设计已成为实现铁路工程可持续发展的重要途径,而供应商选择、物流设施选址、路径规划、库存管理以及工程废弃物回收再利用等决策是铁路工程供应链管理的核心与关键问题。针对我国铁路工程建设供应链管理特点,从可持续视角研究铁路工程建设供应链网络设计集成优化问题,提出两阶段的求解框架:其中,第1阶段基于可持续指标体系运用模糊TOPSIS方法确定最佳供应商选择;第2阶段针对物流设施选址、库存控制策略与网络最佳流量分配的集成决策问题,构建了基于模糊规划的多周期多目标供应链网络集成决策优化模型。该优化模型考虑了运输过程的不确定性,以供应链总成本、碳排放量最小以及社会效益最大为优化目标。针对上述多周期多目标优化模型的特征,设计了改进的宽容分层序列算法进行求解。最后,基于我国丰雄商铁路工程建设项目进行案例研究,验证了上述求解框架与算法的有效性,并针对单位运价、单位运输碳排放量以及弃置率3个关键参数进行了敏感性分析。研究结果表明:1)批量折扣策略可以在联合采购中节省大量成本;2)运输模式与路径优化对系统的效率和可持续绩效有决定性影响;3)与管理学手段相比,推进新能源的使用是降低碳排放量最有效的措施;4)社会效益的提高不可避免地需要更高的成本,政府合理的补贴政策是提高企业积极性的关键举措;5)长远来看,铁路工程项目中的废弃物回收利用是实现可持续工程建设的重要途径,其技术和应用的发展都应受到重视。

基于Kriging模型与FORM的钢板组合梁桥结构优化设计

考虑材料参数的不确定性以及设计变量多重约束条件的影响,提出了基于可靠性分析的钢板组合梁桥结构优化设计方法。首先,利用拉丁超立方试验设计(Latin hypercube design,LHD)构建试验组合方案,并通过有限元分析获取试验设计组合下的最大挠度响应值。基于获取的训练样本,构建能够表征结构最大挠度值与随机输入之间映射关系的Kriging代理模型。基于建立的代理模型,以钢结构截面积最小化为目标函数,建立符合规范要求与可靠度约束的优化数学模型,并采用一阶可靠性方法(first order reliability method,FORM),实现设计变量优化。通过比较具有相同设计变量上限,但下限分别为初始值的80%和70%两种优化设计方案,评估了两者在相同阈值以及不同阈值下设计变量的优化结果。最后对方案二在阈值为17 mm下的优化结果进行极限状态验算。结果表明:两个优化设计方案在阈值为17 mm下的优化结果更具合理性,并且方案二在同一阈值下具有更高的优化程度。随着阈值增加,优化程度增加,且腹板高度在较大阈值下对结果影响更大,而翼缘宽度在较小阈值下影响更大。

基于拓扑优化的SPMT驮梁支架轻量化设计

为解决用于跨线桥拆除的自行式模块化运输车(Self-propelled Modular Transporter, SPMT)驮梁支架结构冗余、重量偏大、制造及安装复杂等问题,依托京哈高速公路跨线桥拆除工程,在“16根标准节段钢管立柱+32道联结系杆”驮梁支架初步设计方案的基础上,以体积最小化为优化目标,利用Abaqus软件的拓扑优化模块开展驮梁支架轻量化设计研究,并对轻量化驮梁支架与初步设计的应力、位移及稳定性进行对比分析。结果表明:优化后的驮梁支架体积减少19.8%,支架联结系杆减少至12道,钢管立柱节段数量简化为2节段,节段长度提升至4 m,构件组拼联结接头数量减少约2/3,总重量较初步设计降低1.44 t;在最不利荷载工况下,驮梁支架优化前、后应力变化较小,最大位移差值在2 mm以内,且满足临界荷载系数大于4的稳定性要求。工程实践证明,轻量化驮梁支架力学性能满足要求,虽然安全系数小幅降低,但结构安全性与优化前基本一致;轻量化驮梁支架在施工现场组拼工作量及组拼时间均有所减少,经济效益显著。

Design method of optimal control schedule for the adaptive cycle engine steady-state performance

The alternative working modes and flexible working states are the outstanding features of an adaptive cycle engine, with a proper control schedule design being the only way to exploit the performance of such an engine. However, unreasonable design in the control schedule causes not only performance deterioration but also serious aerodynamic stability problems. Thus, in this work,a hybrid optimization method that automatically chooses the working modes and identifies the optimal and smooth control schedules is proposed, by combining the differential evolution algorithm and the Latin hypercube sampling method. The control schedule architecture does not only optimize the engine steady-state performance under different working modes but also solves the control-schedule discontinuity problem, especially during mode transition. The optimal control schedules are continuous and almost monotonic, and hence are strongly suitable for a control system, and are designed for two different working conditions, i.e., supersonic and subsonic throttling,which proves that the proposed hybrid method applies to various working conditions. The evaluation demonstrates that the proposed control method optimizes the engine performance, the surge margin of the compression components, and the range of the thrust during throttling.

建筑结构设计优化方法在房屋结构设计中的运用分析

建筑不仅要有非常好的使用价值,同时还要具有一定的艺术美感,这就要求对现有房屋结构设计进行进一步优化。房屋建筑领域中结构上的投入是整体投入中比较多的部分,所占比重相对较高,不断优化结构设计不仅可以确保房屋质量安全,同时还能有效减少项目资金投入,帮助企业增加经济效益及相关收益。据此,文章从多角度针对房屋结构设计中结构设计优化方法的运用展开一系列分析,希望可以为同行业人士的研究带来一些帮助。

混凝土抗裂性能评估的新方法及其应用研究

混凝土作为现代建筑行业的主要建筑材料,其抗裂性能对结构安全稳定具有关键性影响。本研究提出一种混凝土抗裂性能评估的新方法,并探讨其在实际工程应用中的效果。首先,通过分析混凝土裂缝的成因与机理,选取了影响裂缝发展的多种关键参数。其次,基于实验数据和现有评价体系,构建了一个综合性能指标,用于量化评估混凝土抗裂性能。在此基础上,采用数学建模和优化算法对评价体系进行了优化,并验证了该方法的有效性。最后,将新方法应用于多个具体实际工程案例,包括混凝土梁、柱、板等结构体系,并对比分析了新旧评价方法在实际应用中的差异及优越性。

粒子群算法在工程优化设计中的应用

将粒子群算法与惩罚函数法相结合,建构一种离散粒子群算法,解决工程上非线性约束离散变量优化设计问题。为实现离散变量与连续变量的转化,构造了相应的扩张函数,提出惩罚因子的确定策略。通过容器设计算例验证,粒子群算法方法优于文献所列方法。应用粒子群算法、惩罚函数法及所提出的策略对波纹管工程实例进行优化设计,其单位重量下整体波纹管的补偿量比在用产品提高了79.96%,与理论解接近,进一步证明了离散粒子群算法及策略在处理工程非线性约束离散优化设计问题时的有效性,其为工程上类似优化设计提供借鉴。

基于应变能的结构拓扑优化设计

基于在优化结构边界和孔洞周围附加人工材料的思路,结合传统渐进结构优化法和单元应变能分析,研究了基于应变能的结构拓扑优化方法,给出了结构拓扑优化的基本原理,导出了具有单元增、删功能的渐进结构优化基本公式。对具有各向同性的均质材料的桥墩和桥梁结构进行了仿真设计,结果显示结构的最大与最小应变能的差距显著减小,其拓扑解类似于工程中出现的结构,表明该方法的基本原理可行、有效。

双线盾构越江隧道合理间距优化与分析

以上海复兴东路双线盾构越江隧道为背景,利用Marc有限元软件,通过建立盾构隧道江中段的三维弹塑性有限元模型,对隧道不同间距的情况进行了模拟分析,并着重研究后建隧道施工对先建隧道的影响,得出了该隧道合理间距的建议值,为隧道间距的优化设计提供了依据。然后在施工工程中对先建隧道的内力和变形及作用在先建隧道上的荷载等进行了监测,并将监测结果与数值模拟的优化结果进行了比较分析,验证了有限元模型的有限性。得出了一些有意义的结论,对类似工程具有重要的参考价值。

车身结构概念设计集成系统的实现

为了弥补车身在概念设计阶段所产生的缺陷,提出了集车身几何建模、分析、优化于一体的集成设计系统VCD-ICAE。该系统支持"分析驱动设计"的新概念设计思想,以计算机辅助工程技术为核心,融合模板技术、参数化技术和优化技术,对车身结构概念设计的整个过程进行有效的支持,能够自动、快速地建立参数化车身几何模型和有限元网格模型,准确、有效地进行车身强度和模态的计算和校核,并实现以车身总体性能为设计目标的参数优化和形状优化,为用户提供最优的产品设计方案。介绍了该软件的特点、功能和结构流程,以某车型为实例,验证了该软件的有效性。

某型发动机喷管的多学科设计优化

以某型发动机喷管为研究对象,在iSIGHT软件平台上利用单级优化算法对其进行多学科设计优化,目标为权衡喷管推力和质量的综合改善。采用了较为稳健的组合优化策略,依次进行试验设计、全局探索和局部寻优。优化目标函数是通过对多个优化目标的线性加权平均获得的。改进的计算结果表明了MDO在喷管设计中的可行性和实用性。