矮塔斜拉桥斜拉索设计参数优化分析

为分析矮塔斜拉桥的受力性能,以太原河汾大跨度矮塔斜拉桥为工程案例,针对斜拉索设计参数,选择斜拉索面积,斜拉索间距以及无索区长度作为分析参数,分别选取受力性能最差的斜拉索应力、主梁跨中挠度以及主梁截面最不利应力三个指标作为目标函数,定义结构综合目标函数W。根据正交试验方法的参数分析,确定了矮塔斜拉桥斜拉索最优参数组合,同时采用极差分析法对结构综合目标W进行分析,获得斜拉索设计参数对矮塔斜拉桥受力性能的敏感性及显著性。结果表明,矮塔斜拉桥斜拉索设计参数最优组合为:斜拉索面积为原设计的1.2倍、斜拉索间距4.0 m、无索区长度30 m,较原设计方案主梁应力减小了9.9%,主梁挠度减小了3.0%,斜拉索应力减小了7.4%;综合结构主要力学指标来看,参数敏感性程度由强到弱依次为斜拉索间距、斜拉索面积以及无索区长度。

区间参数优化反分析在水利工程中的应用

研究了区间参数摄动法和区间参数优化反分析法,提出了区间参数单调性优化反分析法.基于可变容差优化反分析法,开发了区间优化反分析程序.通过分析得出结论:(1)可利用区间数概念合理解决监测资料中分离分量相关性的问题;(2)可利用工程结构中位移为待反分析材料参数的增函数或减函数的测点位移的上、下限,来反演得到不确定性材料参数的上、下限;(3)工程算例分析表明,区间参数摄动优化反分析法和区间参数单调性优化反分析法都能得到令人满意的参数区间.

用于无线传输系统的低噪声功率放大器的参数分析及优化

在无线传输系统中,低噪声功率放大器(LNA)是一个重要的组成部分。对低噪声功率放大器的设计,1 dB压缩点(P1 dB)和3阶截取点(IP3)是其2个关键参数,对他们进行正确的分析和优化是非常必要的。结合相关研究的新进展,首先对这2个参数的相关定义进行了介绍,然后通过举例分析及软件(Ansoft designer)仿真,得出如何选择和优化这2个参数。得出的结论对低噪声功率放大器的设计具有一定的指导意义。

柴油机-泥浆泵运行参数优化分析

目前川庆钻探工程公司在用的柴油机-液力变矩器机组普遍存在效率低、油耗高等问题,文章通过对使用最广泛的柴油机、液力变矩器进行特性和传动动力分析,并根据川渝地区典型区块各井段的钻井设计规律,对动力需求进行计算,按照柴油机-变矩器-泥浆泵的联动特性,从泥浆泵泵冲和柴油机转速方面对机泵参数进行优化分析,得出不同井段的机泵优化参数,确保柴油机、变矩器和泥浆泵都处于最佳工况运行,达到减少设备故障、降低油耗、提高钻井时效的目的。

隧道固-液-气轴向不耦合装药参数分析及优化

本文针对目前山区公路隧道和地铁区间隧道中掏槽眼围岩爆破中使用的水-空气装药结构,以钻孔爆破的爆轰理论和岩石断裂力学理论为基础,建立了爆破应力波传导介质为固-液-气三种相组成的轴向不耦合爆破计算模型。本文分析了隧道掌子面掏槽眼炮孔的孔内气压随炸药起爆时间的改变、掏槽眼周边围岩的应力场的时空变化情况以及炮孔围岩裂纹尖端的应力强度因子,同时将重庆市轨道交通十号线二期三标段南坪地铁车站施工通道现场的围岩参数作为理论模型的验算依据,建立ANSYS有限元模型并进行了相应算例分析,研究了轴向情况下的不耦合装药系数对炮孔产生的爆破效果的影响,同时以有限元数值模拟方法对在实际爆破施工中遭遇裂隙岩体情况下的炮孔半径等爆破参数也进行了优化。

克深区块超深井钻井关键技术参数优化分析

在充分研究克深区块地层及钻井特点的基础上,针对其两大钻井关键技术及参数,分别就克深地区超深井实钻PDC钻头型号按井段及层段进行了优化统计分析,归纳出了适合该地区的适岩PDC钻头型号;国产油基泥浆在热滚和抗盐污稳定性测试实验的基础上,运用归一化方法将各性能指标进行了优化统计分析,给出了符合当前经济效益和技术支持的维护处理容限阈值;提速工具方面就涡轮复合钻具进行了优化统计分析,确定了涡轮复合钻具在该地区超深井中的提速优越性.这将对克深区块超深井钻井工程提供一定的技术参考,也将为该地区进行高效的勘探开发工作具有明确的指导意义.

面向装配结构的拓扑优化参数影响分析

随着当前精密与超精密加工技术水平的提升,单个机械零部件的加工质量已经能够满足精度要求,但是现有的装配结构的质量却难以保障。为了提高面向装配结构连接性能拓扑优化方法的鲁棒性,同时给加工制造提供多种拓扑优化布局,以弹性装配结构为优化对象,对装配接触结构拓扑优化过程中优化参数对优化过程的影响进行分析。基于不同过滤半径对优化结果的影响规律,引入“各向异性过滤”方法,消除了装配体拓扑优化过程中出现的“界面效应”。另外为提高所优化结构的可加工制造性,引入两种最小长度控制方法,对两者的优化效果进行对比分析讨论,最终保证拓扑优化设计结果的可加工制造性。最后分析了光滑Heavside函数中锐度因子与阈值参数对优化结果的影响机制。

基于PEST的RZWQM2模型参数优化与验证

根据糯玉米-冬小麦田间喷灌试验不同处理结果,利用独立的自动参数估计软件PEST对RZWQM2模型进行参数优化,并分析了24个模型参数的综合敏感度。通过控制不同观测变量(土壤含水率、土壤氮素含量、作物叶面积指数、产量)模拟差异函数值在目标函数中的比重,优化目标方程,确定模型参数,并用田间试验数据对模型进行验证。结果表明,在不同观测变量的模拟差异函数值最接近条件下,冬小麦出叶间隔特性参数、冬小麦春化作用敏感特性参数及糯玉米出叶间隔特性参数等3个参数对模型整体模拟效果影响最大。相比试错法而言,基于PEST优化的RZWQM2模型能够更准确地模拟糯玉米-冬小麦轮作系统中水分、氮素及作物生长情况。

基于海面辐射传输模型参数优化的黄色物质浓度遥感反演

根据水体辐射传输原理以及国内外学者研究成果,利用经验模式优化分析海面辐射传输模型的参数a和bb,提出通过海面辐射传输模型的逆运算获取水体黄色物质浓度的半物理半经验反演算法。基于辐射传输模型与可靠经验模型的黄色物质浓度反演算法所得结果之间的R2=0.832,RMSE=18.67。检验结果表明:基于海面辐射传输模型的黄色物质浓度反演算法是基本可行的。利用该算法与CCD数据反演研究区海域2011年3月、8月、10月、12月的黄色物质浓度,并探讨黄色物质浓度在该区域的时空分布规律。

艉轴密封装置Ω弹簧组的多参数优化设计

Ω弹簧组作为艉轴密封装置的重要组成部件,其结构补偿能力直接影响艉轴密封装置的密封效果.基于零阶算法,以单片弹簧的特征厚度、宽度、中圆半径和顶圆半径为设计变量,对Ω弹簧组进行多参数优化分析.通过有限元优化设计,分析求解Ω弹簧组各设计参数的响应以及径向刚度的最优解,优化后的刚度值比优化前的增加了11.5%.并对优化前后的Ω弹簧组分别进行谐响应分析,验证了Ω弹簧组径向刚度的优化设计对改变Ω弹簧组频率补偿能力的有效性,进而改善其结构补偿能力.

Molecular reconstruction model based on structure oriented lumping and group contribution methods

Molecular management is a promising technology to face challenges in the refining industry, such as more stringent requirements for product oil and heavier crude oil, and to maximize the value of every molecule in petroleum fractions. To achieve molecular management in refining processes, a novel model that is based on structure oriented lumping(SOL) and group contribution(GC) methods was proposed in this study. SOL method was applied to describe a petroleum fraction with structural increments, and GC method aimed to estimate molecular properties. The latter was achieved by associating rules between SOL structural increments and GC structures. A three-step reconstruction algorithm was developed to build a representative set of molecules from partial analytical data. First, structural distribution parameters were optimized with several properties. Then, a molecular library was created by using the optimized parameters. In the final step, maximum information entropy(MIE) method was applied to obtain a molecular fraction. Two industrial samples were used to validate the method, and the simulation results of the feedstock properties agreed well with the experimental data.

Analysis on the Interaction of Parameters of Single-contaminant Regeneration Recycling Water Systems

Method for constructing the optimal water supply line and formulas for calculating the targets for single-contaminant regeneration recycling water systems are improved to apply to the situation of variational pararneters in this article. Based on these extending methods, the effect of varying freshwater consumption and regenerated water flow rate on the optimizing results are investigated. The interactions of parameters of regeneration recycling systems are summarized. Finally, all the conclusions are illustrated from the results of mathematical programming through an example.

Optimal control of cobalt crust seabedmining parameters based on simulated annealing genetic algorithm

Under the condition of the designated collection ratio and the interfused ratio of mullock, to ensure the least energy consumption, the parameters of collecting head （the feed speed, the axes height of collecting head, and the rotate speed） are chosen as the optimized parameters. According to the force on the cutting pick, the collecting size of the cobalt crust and bedrock and the optimized energy consumption of the collecting head, the optimized design model of collecting head is built. Taking two hundred groups seabed microtopography for grand in the range of depth displacement from 4.5 to 5.5 era, then making use of the improved simulated annealing genetic algorithm （SAGA）, the corresponding optimized result can be obtained. At the same time, in order to speed up the controlling of collecting head, the optimization results are analyzed using the regression analysis method, and the conclusion of the second parameter of the seabed microtopography is drawn.

Mechanism Design and Motion Analysis of Heavy⁃Load Transfer Robot with Parallel Four⁃Bar Mechanism

Heavy-load transfer robots are widely used in automobile production and machinery manufacturing to improve production efficiency.In order to meet the needs of large billet transfer,a 4-DOF transfer robot is designed in this paper,which consists of parallel four-bar mechanisms.The Jacobian matrix referring to the mapping matrix from the joint velocity to the operating space velocity of the transfer robot can be solved by the differential-vector method.The mean value of the Jacobian matrix condition number in the workspace is used as the global performance index of the robot velocity and the optimization goal.The constraint condition is established based on the actual working condition.Then the linkage length optimization is carried out to decrease the length of the linkage and to increase the global performance index of velocity.The total length of robot rods is reduced by 6.12%.The global performance index of velocity is improved by 45.15%.Taking the optimized rod length as the mechanism parameter,the distribution of the motion space of the transfer robot is obtained.Finally,the results show that the proposed method for establishing the Jacobian matrix of the lower-mobility robot and for the optimization of the rods based on the velocity global performance index is accurate and effective.The workspace distribution of the robot meets the design requirements.

Analyzing the Relation Between Earthquakes and Active Faults Based on the Parameter Optimization Model

The gestation and occurrence of strong earthquakes are closely related to fault activity, which is not only revealed by abundant experimentation and seismism but also proved by modern seismology. On the Chinese mainland, the relation between earthquake activity and active faults is one of the bases for partitioning potential seismic sources, analyzing the seismotectoulcs and estimating location of strong earthquakes.Due to the nonuniformity of earth media, instability of observation systems and disturbance of the environment, etc, the variety of observational data is complicated, that is, there is no absolutely ＂normal＂ or ＂abnormal＂, and seismic anomalies can be divided into many mutually exdusive＂ abnormal states＂. In different conditions of combined time-spacestrength, determining seismic anomalies by different monomial forecast methods and its efficiency could be different due to the uncertainty of a precursor itself or complexity of the relationship between a precursor and earthquake gestation. It is very difficult to discover and dispose of this difference in actual application in a ＂two-state＂ model. But in a ＂multi-state＂ model, the difference can be easily reflected and the optimal combination of forecasting parameters for a forecast method can also be determined easily. Based on the ＂multi-state＂ precursory model and the optimization method for parameters of earthquake forecast model under the condition of optimal forecast efficiency, the relationship of the spatial location of earthquake with M ≥ 6.0 and active faults in three seismic belts are analyzed. The results demonstrate that in the Hetao Seismic Belt, seismicity is mostly concentrated in the range of 20 km along the fault, the optimization model can forecast the location of potential earthquakes of M ≥ 6.0 near the faults with a relatively high accuracy and the reliability is 0.5 ; while in the Qilian Mt. Seismic Belt, the reliability only reaches 0.14 when we use the model to estimate earthquakes within 30 km range along the faults. The ＂multi-state＂ precursory model, the efficiency-evaluating model and the parameter selection of individual earthquake forecast model based on optimal efficiency are of certain revelatory and practicable meanings for developing knowledge about precursors, investigating the laws of earthquake preparation and searching for optimal forecasting methods.

Optimization on springback reduction in cold stretch forming of titanium-alloy aircraft skin

An optimization method was presented for cold stretch forming of titanium-alloy aircraft skin to determine process parameters and to reduce springback.In the optimization model,a mathematical formulation of stress difference was developed as an indicator of the degree of springback instead of implicit springback analysis.Explicit finite element method(FEM)was used to analyze the forming process and to provide the stress distribution for calculating the amount of the stress indicator.In addition,multi-island genetic algorithm(MGA)was employed to seek the optimal loading condition.A case study was performed to demonstrate the potential of the suggested method.The results show that the optimization design of process parameters effectively reduces the amount of springback and improves the part shape accuracy.It provides a guideline for controlling springback in stretch forming of aircraft skin.

Optimization of parameters, characterization and thermal property analysis of hafnium ethoxide synthesized by electrochemical method

Hafnium ethoxide was synthesized using electrochemical method.Optimization experiments were used to optimizevarious parameters namely Et4NBr concentration(c):0.01?0.06mol/L,solution temperature(t):30?78°C,polar distance(D):2.0?4.0cm and current density(J):100?400A/m2.The electrolytic products obtained under optimum conditions of c=0.04mol/L,t=78°C,D=2.0cm and J=100A/m2were further isolated by vacuum distillation under5kPa.The product was characterized byFourier transform infrared(FT-IR)spectra,nuclear magnetic resonance(NMR)spectra.The results indicated that the product washafnium ethoxide.ICP analysis suggested that the content of hafnium ethoxide in the final product exceeded99.997%.Thermalproperties of the product were analyzed by TG/DTG.The vaporization enthalpy of hafnium ethoxide was found to be79.1kJ/mol.The result confirmed that hafnium ethoxide was suitable for the preparation of hafnium oxide by atomic layer deposition.

深基坑支护结构变形预报

通过现场量测的深基坑围护结构变形信息资料,结合参数优化反分析技术及弹性地基梁有限元计算,建立了深基坑开挖中支护结构变形的预报方法。该方法可对深基坑开挖中支护结构变形做出评估,指导施工。

Multidimensional CAE methods for car body structure optimization

The computer aided engineering(CAE) analysis technique has become one of the most important means in modern automobile development due to its remarkably computing capability.With the development of CAE bussiness software and intensive research on automotive development process,the CAE technique,which was only used as an auxiliary validation tool in the later product development in the past,is gradually used in each stage of product development now.Furthermore,accurate and fast analysis data can be supplied effectively.Especially in current CAE application, based on some optimization technologies such as sensitivity,feature and topology,the parametric design gradually enables a CAE engineer to be free from the condition which a convention analysis usually lags behind a design,and makes it be parallel to or even anterior to the design.Under the circumstance,the CAE resources can be maximized in each project development department,thereby promoting the project progress and quality,and creating a new philosophy of 'analysis-driven design'.

Parameters optimization and nonlinearity analysis of grating eddy current displacement sensor using neural network and genetic algorithm

A grating eddy current displacement sensor(GECDS) can be used in a watertight electronic transducer to realize long range displacement or position measurement with high accuracy in difficult industry conditions.The parameters optimization of the sensor is essential for economic and efficient production.This paper proposes a method to combine an artificial neural network(ANN) and a genetic algorithm(GA) for the sensor parameters optimization.A neural network model is developed to map the complex relationship between design parameters and the nonlinearity error of the GECDS,and then a GA is used in the optimization process to determine the design parameter values,resulting in a desired minimal nonlinearity error of about 0.11%.The calculated nonlinearity error is 0.25%.These results show that the proposed method performs well for the parameters optimization of the GECDS.