Optimum Environmental Load Design Criterion for Marine Structures Based on Investment and Benefit Analysis

Marine structures operating in natural ocean environment are subjected to various stochastic loads. For design of the marine structures, the most important task is to determine environmental load design criterion. This paper presents a method to determine the optimum environmental load design criterion for marine structures. This method is based on the investment and benefit analysis and it can reach the design purpose of decreasing total costs during the service life of the structures and increasing economic benefits.

Nonlinear Finite Element Analysis and Optimum Design of Spot-Welded Joints and Weld-Bonded Joints

Resistance spot welding and hybrid weld bonding have wide applications in the body work construction within the automobile industry. The integrity of the spot welds and applied adhesives determines the body assembly rigidity and dynamic performance. Incorporating contact nonlinearity and geometric nonlinearity, finite element analysis (FEA) have been carried out to investigate the structural stiffness and strength of both spot-welded and weld-bonded assemblies. Topology optimization has been performed to reveal the distributions of material effectiveness in the overlap regions and suggest a feasible method for removing underutilized material for weight reduction. Design optimization has been conducted with an aim to reduce the maximum von Mises stress in the assembly to minimum by choosing optimum values for a set of design variables, including the weld spacing, weld diameter and overlap width.

Optimum Designing of Gas Distribution Networks of Ilam Province by Using GIS Network and Spatial Analysis

Undoubtedly, pipeline transport is considered as significant economical artery of country and national valuable resources, so it is necessary to use latest technologies, major standards and instructions and the best human resources in designing, operation and supervision in construction and also protection of it. Also, all authorities and involved of construction and operation of gas industries installation should observe safety criteria, health and environment and aware of them ever. In fact, in designing of these programs, in addition to technical and economical points, environmental characteristics should be considered in order to their construction has minimum damage to environment. On the other hand, common and traditional approaches of pipeline routing are based on using costly and time-consuming methods. In these methods, it is not easily to use all effective parameters in determining optimum way. According to capability of analysis of network spatial information systems in incorporation of spatial data, for using all effective parameters in routing, this environment is used, therefore weighted overlay analysis (Boleyn, index and fuzzy) and shortest path are modeled for finding optimum path of pipeline in GIS environment.

Optimization Design and Finite Element Analysis of Core Cutter

The hydro-hammer sampler is a new type of sampler compared with traditional ones. An important part of this new offshore sampler is that the structure of the core cutter has a significant effect on penetration and core recovery. In our experiments, a commercial finite element code with a capability of simulating large-strain frictional contact between two or more solid bodies is used to simulate the core cutter-soil interaction. The effects of the cutting edge shape, the diameter and the edge angle on penetration are analyzed by non-liner transient dynamic analysis using a finite element method （FEM）. Simulation results show that the cutter shape clearly has an effect on the penetration and core recovery. In addition, the penetration of the sampler increases with an increase in the inside diameter of the cutter, but decreases with an increase in the cutting angle. Based on these analyses, an optimum structure of the core cutter is designed and tested in the north margin of the Dalian gulf. Experiment results show that the penetration rate is about 16.5 m/h in silty clay and 15.4 m/h in cohesive clay, while the recovery is 68% and 83.3% resoectively.

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.

Multi-stage optimum design of magazine type automatic tool changer arm

To enhance machining efficiency,tool change time has to be reduced.Thus,for an automatic tool changer attached to a machining center,the tool change time is to be reduced.Also the automatic tool changer is a main part of the machining center as a driving source.The static attributes of the automatic tool changer using the commercial code,ANSYS Workbench V12,were tried to interpret.And the optimum design of automatic tool changer arm was proposed by performing the multi-stage optimum design.The shape optimization of the automatic tool changer was proposed and the result was verified to obtain acceptable improvements.It is possible to obtain an optimized model in which the maximum deformation,maximum stress,and mass are reduced by 10.46%,12.89% and 9.26%,respectively,compared with those of the initial model.Also,the results between conventional method by the design of experiments and proposed method by the multi-stage optimum design method were compared.

OPTIMUM DESIGN BASED ON RELIABILITY IN STOCHASTIC STRUCTURE SYSTEMS

The optimum design method based on the reliability is presented to the stochastic structure systems （i. e., the sectional area, length, elastic module and strength of the structural member are random variables ） under the random loads. The sensitivity expression of system reliability index and the safety margins were presented in the stochastic structure systems. The optimum vector method was given. First, the expressions of the reliability index of the safety margins with the improved first-order second-moment and the stochastic finite element method were deduced, and then the expressions of the systemic failure probability by probabilistic network evaluation technique（PNET） method were obtained. After derivation calculus ,the expressions of the sensitivity analysis for the system reliability were obtained. Moreover, the optimum design with the optimum vector algorithm was undertaken. In the optimum iterative procedure, the gradient step and the optimum vector step were adopted to calculate. At the last, a numerical example was provided to illustrate that the method is efficient in the calculation, stably converges and fits the application in engineering.

Optimum Design for Offshore Platform Structural Reliability

In this paper, the main problems concerning reliability design of offshore platform structure are described and the general steps for the use of Safety Coefficient Method are presented.

Finite Element Analysis of the 2 m Telescope Assemble

To improve the performance of the 2 m telescope, the optimum design is applied to the telescope assemble. Referring to the telescope assemble with the dimetric truss, a group of reasonable sizes of the telescope assemble are found by optimization methods and modal analysis, which will raise the resonant frequency by 4.21 %. As a result, the telescope assemble is less likely to resonate. Besides, the dynamic response module in ANSYS is utilized to analyze the modal type, harmonic vibration response and random vibration response of the telescope assemble. By the calculation of ANSYS, finite dement analysis （FEA） method proves that the performance of the telescope assemble is mildly enhanced by means of optimum design.

Probabilistic Performance-Based Optimum Seismic Design Framework: Illustration and Validation

In the field of earthquake engineering,the advent of the performance-based design philosophy,together with the highly uncertain nature of earthquake ground excitations to structures,has brought probabilistic performance-based design to the forefront of seismic design.In order to design structures that explicitly satisfy probabilistic performance criteria,a probabilistic performance-based optimum seismic design(PPBOSD)framework is proposed in this paper by extending the state-of-the-art performance-based earthquake engineering(PBEE)methodology.PBEE is traditionally used for risk evaluation of existing or newly designed structural systems,thus referred to herein as forward PBEE analysis.In contrast,its use for design purposes is limited because design is essentially a more challenging inverse problem.To address this challenge,a decision-making layer is wrapped around the forward PBEE analysis procedure for computer-aided optimum structural design/retrofit accounting for various sources of uncertainty.In this paper,the framework is illustrated and validated using a proof-of-concept problem,namely tuning a simplified nonlinear inelastic single-degreeof-freedom(SDOF)model of a bridge to achieve a target probabilistic loss hazard curve.For this purpose,first the forward PBEE analysis is presented in conjunction with the multilayer Monte Carlo simulation method to estimate the total loss hazard curve efficiently,followed by a sensitivity study to investigate the effects of system(design)parameters on the probabilistic seismic performance of the bridge.The proposed PPBOSD framework is validated by successfully tuning the system parameters of the structure rated for a target probabilistic seismic loss hazard curve.The PPBOSD framework provides a tool that is essential to develop,calibrate and validate simplified probabilistic performance-based design procedures.

Optimum Design of Highway Excavation Slope Angle: Evidence from Dawu Section of Jingzhu Highway

The optimum design of the highway excavation slope angle is one of the most important problems to the highway construction and to the slope improvement. The Dawu Section of Jingzhu (Beijing Zhuhai) Highway is taken as an example to illustrate the study method for excavation slope angle design. The analysis of the engineering condition from different angles with different factors shows that the stability of the slope is calculated by using residual pushing force and the Sarma method. Then the sensitive analysis of the slope stability is conducted by using residual pushing force method. Finally, the optimum angle of design is presented on the precondition of ensuring the whole stability of slope and the economic reasonability. The study results show that the most sensitive factors are the shear strength parameter and the seismic force, and that the optimum excavation slope angle is 60°.

Optimum structural design of full-scale steel buildings using drift-tribe-charged system search

In this paper,the potential of utilizing improved metaheuristic approaches in optimal design of building structures is concerned.In this regard,the drift-tribe-charged system search algorithm is proposed that the position and velocity updating processes of the charged system search is developed by implementing the mathematical presentation of the free-electron model utilized for metal conductors.In addition,the searching phase of the developed algorithm is also divided into three separate phases in order to improve the convergence capability of the algorithm.By means of these modifications,the exploitation and exploration rates of the standard algorithm are enhanced.In order to determine the ability of the proposed improved metaheuristic method considering some complex optimization problems,a 10-story steel building structure with 1026 structural members alongside a 60-story structure with 8272 members are utilized as numerical examples.The overall capability of the developed metaheuristic approach is compared with other metaheuristics.A total number of 30 independent runs have been conducted for each of the standard and proposed methods while a statistical analysis is also conducted for comparative purposes.The obtained optimum results demonstrated that the proposed metaheuristic approach is capable of preparing better outcomes than other metaheuristics.

Optimal Design of Surface Structure of a Magnetic Head

Currently, the surface structure of a magnetic head has been transferred from a positive to a negative model. In order to increase magnetic storage density and to decrease the flight height, the surface structure of a head needs to be optimized continually. In the present paper, the influence of surface structure of a negative magnetic head on its flight attitude is analyzed in brief by both theoretical analysis and numerical simulation. Firstly, based on theoretical analysis, one-dimensional model of optimal design is built whose results play an important role in guiding for the two-dimensional model. Secondly, to analyze the impacts of different slructures of negative pressure heads, the original head structure is divided into five zones; the impacts of different zones on both pressure distribution and load carrying capacity were detailed analyzed by numerical analysis. Thirdly, remain the leading-head structure of the negative head, and optimized tail-end structure can be gained by the regional planning strategy to control the gas film pressure distribution. With layout strategy, three kinds of structures of the head were designed. The results show that the tail-end structure impacts on the flight performances significantly and the middle boss plays a major role on positive pressure, while the bilateral bosses lying in either side play assistant regulating role. The structures of bilateral bosses have slightly impact on pressure distribution. The results also show that an optimum tail structure can meet the needs of a lower flight height and a larger magnetic storage density.

Optimal Design of Tapered Roller Bearings Based on Multi⁃Physics Objectives Using Evolutionary Algorithms

Rolling element bearing is the most common machine element in rotating machinery.An extended life is among the foremost imperative standards in the optimal design of rolling element bearings,which confide on the fatigue failure,wear,and thermal conditions of bearings.To fill the gap,in the current work,all three objectives of a tapered roller bearing have been innovatively considered respectively,which are the dynamic capacity,elasto-hydrodynamic lubrication(EHL)minimum film⁃thickness,and maximum bearing temperature.These objective function formulations are presented,associated design variables are identified,and constraints are discussed.To solve complex non⁃linear constrained optimization formulations,a best⁃practice design procedure was investigated using the Artificial Bee Colony(ABC)algorithms.A sensitivity analysis of several geometric design variables was conducted to observe the difference in all three objectives.An excellent enhancement was found in the bearing designs that have been optimized as compared with bearing standards and previously published works.The present study will definitely add to the present experience based design followed in bearing industries to save time and obtain assessment of bearing performance before manufacturing.To verify the improvement,an experimental investigation is worthwhile conducting.

混合基础隔震体系优化设计及性能

为解决基础隔震结构中隔震层位移需求过大的问题,提出了一种基础隔震结构(Base Isolated Structure,BIS)+串并联调谐质量阻尼器惯容器(Tuned Tandem Mass Damper-Inerter, TTMDI)的混合隔震体系。采用Bouc-Wen滞回模型模拟隔震层的非线性力-变形行为,基于随机等效线性化和模式搜索优化算法并考虑地震动模型,在频域内建立了BIS+TTMDI体系的优化设计框架。分别从鲁棒性、有效性、刚度和阻尼系数、冲程及对地震频率敏感性方面对BIS+TTMDI体系的性能进行评估,并与BIS+调谐质量阻尼器(Tuned Mass Damper, TMD)、串并联调谐质量阻尼器(TunedTandemMassDamper,TTMD)和调谐质量阻尼器惯容器(TunedMass Damper-Inerter, TMDI)进行比较。通过对近场地震动下某七层混合基础隔震结构(包括BIS+TTMDI和BIS+TMDI体系)的动力弹塑性分析,评价了其减/隔震性能。结果表明:BIS+TTMDI体系具有最好的减/隔震性能和强鲁棒性;而且在BIS+TTMDI体系中TTMDI的总阻尼需求不到BIS+TMDI体系中TMDI的一半,因而更为经济实用。

考虑SSI效应时TMD的减震优化设计

土-结构相互作用(SSI)效应可能会对地震作用下调谐质量阻尼器(TMD)的有效性产生重要影响,因此本文研究了考虑SSI效应时TMD对高层建筑的抗震控制性能。针对一个质量分布均匀、层刚度随高度呈线性分布的40层benchmark结构,以结构顶层均方根位移最小为优化目标,采用改进粒子群算法对其在不同地基土条件以及地震波激励下的调谐质量阻尼器参数进行优化设计。优化结果表明,忽略SSI效应可能会造成地震激励下高层结构中TMD减震性能的不恰当估计,TMD的优化参数与地基土类型和地震波种类紧密相关。优化后的TMD可以有效降低结构顶层位移响应且不增加其峰值加速度,优化后的TMD耗散了绝大部分地震输入能量,并大大降低了结构能量。

航空电子设备安装支架的刚度与频率优化设计

航空电子设备用于飞行中的数据采集,通常使用安装支架固定于机头雷达罩,研究安装支架的刚度和一阶频率性能,避免设备支架在飞行过程中出现塑性变形和共振现象,对提高飞行稳定性具有重要的工程意义。在惯性载荷下对安装支架进行静强度和模态分析,采用一种灵敏度分析方法确定安装支架的设计变量,以结构总质量最小为优化目标,在保证安装支架的刚度和一阶模态性能的前提下对支架各个构件的厚度进行优化设计,并对优化后的安装支架结构进行振动试验。结果表明:优化后的安装支架结构刚度基本保持不变,一阶频率提高了18.09%,质量减少了19.33%,改进设计满足设备安装要求。

眼动实验在交互界面设计中的研究进展与趋势

对国内外眼动实验应用在交互界面设计中的文献进行可视化的分析,得到总体性认识,从而客观解读交互界面设计的发展趋势。采用文献法与内容分析法,把2000-2022年中国知网(CNKI)以及WebiofScence核心合集数据库中的相关文献作为数据来源,通过VOSvewer、Ctespace工具对文献进行可视化分析。研究发现,国内外研究热度同步呈现上升趋势,但研究热点既有联系又有区别。国内涉猎范围广泛,界面眼动实验与多学科交叉融合。而国外则在临床医学等高价值方向进行纵向深入的研究。界面设计范围不断扩大,关注用户,设计元素不断细化。在后续研究中,国内可以从临床医学等高价值方向纵向深度发展,同时加强与先进计算机技术的结合。

床垫提手缝制工序作业分析与优化

目前我国大部分家具生产企业仍是采用半自动化设备,以人机配合操作生产为主,因此要快速地提高企业效益需要运用工业工程理论对企业生产进行优化。针对自动化程度较低的床垫提手缝制工序,采用摄像法和秒表法进行岗位观测记录,运用“5W1H”分析法和人机操作分析方法,对床垫提手缝制工序存在的问题进行总结和优化。该岗位存在操作工序冗长、返工现象频繁、物料堆放混乱等问题,针对以上问题以提高工序人机利用率为目的提出了优化方案,以期提升企业生产效益。