可靠性分析的改进加权响应面法

为了克服响应面法(Response surface method简称RSM)在计算大规模工程时效率低下和计算可靠性指标敏感度时偶尔误差大的问题,提出一个高效率的改进加权响应面方法.此方法首先构造一次响应面函数,然后在可能存在失效点的被缩小范围内采用轴向采样来得到样本点,构造二次响应面函数;通过从之前的样本组里增加新的样本点,给予靠近失效点的样本点更高的权重来更新响应面函数.通过几个算例表明:比较双加权响应面方法,此方法具有更高的准确性和计算效率.     

多随机变量响应面法在结构可靠性分析中的应用

基于样条函数拟合曲面响应面法,给出确定实验点和拟合响应面的方法,提出一种适用于响应面的一次二阶矩优化算法.算例表明,所提出的拟合曲面响应面算法具有使用简单和计算精度高的特点.     

结构可靠度分析的响应面法和随机响应面法的比较

从拟合功能函数方法、计算精度与效率、收敛性等方面对响应面法和随机响应面法进行了系统地分析.算例表明:与响应面法相比,随机响应面法实现了真正意义上的非侵入式分析.响应面法采用二次多项式响应面函数仅仅在验算点附近能较好地拟合真实功能函数,而随机响应面法采用高阶Hermite随机多项式,能在整个空间上很好地拟合真实功能函数.当随机变量个数较少时,随机响应面法的计算精度和效率均优于响应面法.并且随机响应面法可进行自身的收敛性分析,确定最优阶次的计算结果作为精确解,其收敛性也优于响应面法.     

轿车侧碰中车门抗撞性的快速优化

针对汽车侧面碰撞时吸收能量的重要部件——车门结构,进行了快速抗撞性优化设计。将提高车门结构吸能量作为优化目标,选择主要部件的板厚为设计变量,建立抗撞性优化问题的数学模型。基于均匀试验设计方法快速合理地分布样本点。根据多项式响应面方法构造原优化问题的高精度近似模型。采用粒子群优化算法对近似模型进行优化设计。优化结果证明了本文提出的快速抗撞性优化设计方案的可行性及有效性,对车辆被动安全分析具有较高的工程应用价值。     

Design optimization of transonic compressor stage using CFD and response surface model

In order to shorten the design period, the paper describes a new optimization strategy for computationally expensive design optimization of turbomachinery, combined with design of experiment (DOE), response surface models (RSM), genetic algorithm (GA) and a 3-D Navier-Stokes solver(Numeca Fine). Data points for response evaluations were selected by improved distributed hypercube sampling (IHS) and the 3-D Navier-Stokes analysis was carried out at these sample points. The quadratic response surface model was used to approximate the relationships between the design variables and flow parameters. To maximize the adiabatic efficiency, the genetic algorithm was applied to the response surface model to perform global optimization to achieve the optimum design of NASA Stage 35. An optimum leading edge line was found, which produced a new 3-D rotor blade combined with sweep and lean, and a new stator one with skew. It is concluded that the proposed strategy can provide a reliable method for design optimization of turbomachinery blades at reasonable computing cost.     

基于自适应采样的复杂模型全局近似

针对复杂模型近似处理的问题,提出自适应采样结合曲面曲率的全局近似方法.采用自适应设计域分割采样方法获取新增采样点,逐步提高源模型的响应面近似模型精度.引入判定响应面近似模型精度,提出利用几何方法计算曲面曲率,并结合启发式直接搜索算法（DIRECT）搜索响应面模型上的最大曲率点及设计域最佳分割位置.所提方法可以运用于其他响应面模型,并适合用于大设计域、大数据源模型的近似处理.函数源模型及复杂电动车模型的近似处理测试结果表明,所提方法具有实用性和有效性.     

响应面方法及其在桥梁体系可靠度分析中的应用

提出将响应面方法和非线性有限元分析结合起来对桥梁上部结构的体系可靠度进行分析的新方法.首先,在试验设计的基础上应用通用的非线性有限元分析程序对桥梁结构进行体系承载力极限分析,然后,利用响应面方法推求桥梁结构体系承载力的响应面,最后利用可靠度分析程序计算桥梁结构的体系可靠度指标和失效概率.通过对一单跨叠合桥梁进行算例分析,证明了所建议方法的有效性.     

表面响应算法及其在MRI主磁体优化设计中的应用

通过将基于径向基函数的表面响应模型和改进的遗传算法相结合，提出了一种电磁场逆问题优化策略的新方法；该方法一方面利用表面响应模型能够大大节省目标函数评价的时间，另一方面通过改进遗传算法能加速收敛，从而节省了寻优时间.这一方法已应用于永磁完全开放式磁共振成像仪主磁体结构的优化设计.此外，给出了一种产生薄片型磁场的永磁全开放式磁共振成像仪主磁体结构.计算实例表明，所提出的算法能实现多变量寻优，且能大大节省计算时间，易于编程实现.     

自适应加权最小二乘支持向量机回归及应用

针对软测量建模样本中数据难以避免存在粗差、以及粗差数据对模型性能的影响,提出了一种自适应加权最小二乘支持向量机(AWLS-SVM)回归建模方法。AWLS-SVM基于建模样本数据,根据最小二乘支持向量机回归模型的拟合残差确定各样本的残差权值,根据样本的空间分布确定杠杆权值,进而通过迭代运算,自适应确定各建模样本的权值,在有效减小粗差点对模型性能影响的同时,保留了其所提供的有效信息。仿真实验表明,AWLS-SVM能有效克服粗差样本数据的影响,其模型的预测性能明显优于LS-SVM和径向基函数网络。最后,应用AWLS-SVM建立粗对苯二甲酸中4-CBA含量软测量模型,获得满意结果。     

响应面方法及其在食品工业中的应用

响应面方法是利用合理的试验设计并通过对实验数据进行一定的处理,建立影响因素与响应值之间的函数关系,得到一个回归方程,通过对回归方程进行分析,选择最优工艺参数.这种方法已广泛应用于粮油食品、化学化工等方面的工艺配方设计及加工工艺条件的优化.本文就响应面方法的优点、试验设计的方法以及实验数据的处理进行了简单的阐述,对其应用的限制因素进行一一说明,并就具体应用列举了一个简单的实例.     

Parametric optimization of friction stir welding process of age hardenable aluminum alloys-ANFIS modeling

A comparative approach was performed between the response surface method(RSM) and the adaptive neuro-fuzzy inference system(ANFIS) to enhance the tensile properties, including the ultimate tensile strength and the tensile elongation, of friction stir welded age hardenable AA6061 and AA2024 aluminum alloys. The effects of the welding parameters, namely the tool rotational speed, welding speed, axial load and pin profile, on the ultimate tensile strength and the tensile elongation were analyzed using a three-level, four-factor Box-Behnken experimental design. The developed design was utilized to train the ANFIS models. The predictive capabilities of RSM and ANFIS were compared based on the root mean square error, the mean absolute error, and the correlation coefficient based on the obtained data set. The results demonstrate that the developed ANFIS models are more effective than the RSM model.     

Improved response surface method based on sample point selection strategies

In the reliability analysis of complex structures,response surface method(RSM)has been suggested as an efficient technique to estimate the actual but implicit limit state function.A set of sample points are needed to fit to the implicit function.It has been noted that the accuracy of RSM depends highly on the so-called sample points.However,the technique for point selection has had little attention.In the present study,an improved response surface method(IRSM)based on two sample point selection techniques,named the direction cosines projected strategy(DCS)and the limit step length iteration strategy(LSS),is investigated.Since it uses the sampling points selected to be located in the region close to the original failure surface,and since it needs only one response surface,the IRSM should be accurate and simple in practical structural problems.Applications to several typical examples have helped to elucidate the successful working of the IRSM.     

新型开放式超导MRI主磁体结构优化设计

针对超导磁共振成像（MRI）装置对磁体结构开放性的设计要求,提出了一种开放式超导MRI磁体结构.为了实现高磁场强度、高磁场均匀度以及低成本等设计目标,对设计的磁体结构进行了多目标优化.运用正交试验（OD）法确定影响磁体性能指标的关键设计变量,在此基础上,提出一种结合表面响应法和遗传算法的自适应优化策略,找出全局最优解,完成了主磁体结构的优化设计.实验结果表明,设计的超导型MRI主磁体不仅提供了一定的开放成像空间,同时也满足成像区磁场强度及均匀度等方面的设计要求.     

A unified approach to kinematic synthesis of mechanism by adaptive curve fitting

A unified approach to kinematic synthesis of mechanism is presented in this paper. Firstly a new approach to adaptive curve fitting is presented, which leads the normal fitting error to be minimum for a series of given discrete points, including a plane curve fitting, a spherical curve fitting and a ruled surface fitting in terms of invariants of ruled surface. Approximate characteristic points and lines are defined, such as an approximate circle point, an approximate slide point, an approximate spherical cone point and an approximate constant axis with an approximate spherical image cone point and an approximate striction curve. Then, the ruled surface fitting will be converted into a space curve fitting and a spherical curve fitting by differential geometry. Based on these definitions and the adaptive curve fitting approaches, the unified mathematical model is set up for the kinematic synthesis of mechanism from planar, spherical to spatial motion. Finally, a planar mechanism or a spatial mechanism ca     

基于区域分割与约束逼近的二次曲面重建

从散乱数据中有效地分离出特征与约束是表达原始产品设计意图的关键.基于点的连通性及同一特征曲面数据点估算法矢、曲率的相似性,并在特征曲面拟合误差控制下实现了空间散乱数据二次曲面数据的自动分离;应用二次曲面的几何参数表达建立了二次曲面整体约束逼近的最优化数学模型,将几何约束情况下的二次曲面重建转化为数学模型的求解,使重建的CAD模型可有效再现二次曲面之间的几何约束.工程应用实例表明:该方法稳定可靠,可显著提高反求工程CAD建模效率及重建模型精度.     

Vibration reliability analysis for aeroengine compressor blade based on support vector machine response surface method

To ameliorate reliability analysis efficiency for aeroengine components, such as compressor blade, support vector machine response surface method(SRSM) is proposed. SRSM integrates the advantages of support vector machine(SVM) and traditional response surface method(RSM), and utilizes experimental samples to construct a suitable response surface function(RSF) to replace the complicated and abstract finite element model. Moreover, the randomness of material parameters, structural dimension and operating condition are considered during extracting data so that the response surface function is more agreeable to the practical model. The results indicate that based on the same experimental data, SRSM has come closer than RSM reliability to approximating Monte Carlo method(MCM); while SRSM(17.296 s) needs far less running time than MCM(10958 s) and RSM(9840 s). Therefore,under the same simulation conditions, SRSM has the largest analysis efficiency, and can be considered a feasible and valid method to analyze structural reliability.     

基于响应面和遗传算法的翼型优化设计方法研究

文章针对气动优化设计中高效率和高精度的矛盾,综合响应面方法和遗传算法的优点和不足,采用多项式响应面模型代替原始遗传算法中计算量庞大的目标特性分析模型,建立了多项式响应面模型和遗传算法相结合的翼型优化设计方法,在采用N-S方程进行气动求解达到较高的精度情况下,求解次数显著减少,优化效率大大提高。研究了设计变量对优化设计效率的影响,文中方法在较少设计变量、较少N-S方程求解次数情况下,即可得到满意的优化设计结果。设计区间对响应面模型精度的影响显著,合适的设计区间既可保证模型精度,减少响应面预测结果和CFD计算结果的偏差,又可获得最佳优化结果。文中方法适用于翼型的单设计点和多设计点优化设计问题,具有原理简单、适应面宽、快速易行,且精度高等特点,可广泛应用于工程设计问题中。     

响应面模型在耐压壳优化设计中的应用研究

针对有限元模型应用于优化设计时效率低的问题,提出了一个环肋圆柱壳结构优化设计策略.该策略用APDL语言建立参数化结构有限元分析模型,并根据设计要求选取设计变量,用试验设计的方法在设计变量空间里选取样本点并进行结构分析,得到各样本点的响应.最后用这些样本点和响应建立起结构质量和应力的二阶多项式模型,并对响应面模型采用罚函数法进行优化获得最优解.结果表明,所提方法提高了结构的强度利用率,缩短了优化时间,研究结果对实际应用有参考价值.     

HCPE连杆优化设计的响应面近似方法研究

为提高设计效率和实现液压约束活塞发动机（hydraulicconfinedpistonengine,HCPE）协同优化,对HCPE连杆优化设计的响应面近似方法进行研究,建立了HCPE连杆优化设计的响应面二阶模型,并对连杆响应面二阶模型计算结果与有限元分析结果进行比较,结果表明,误差较小,在5％以内。通过优化,与原始体积相比,连杆体积减小了约20．03％。运用响应面近似方法可缩短计算时间,降低计算成本,为HCPE协同优化提供了理论依据。     

基于随机抽取一致性的稳健点云平面拟合

针对常用的平面拟合方法在点云数据存在误差或异常值时产生拟合不稳定的现象,提出了结合最小二乘法的随机抽取一致性(random sample consensus,RANSAC)平面拟合算法.该方法先用RANSAC算法检测并剔除异常数据点,再利用最小二乘法将得到的有效数据点拟合,计算平面模型参数.实验中,分别采用该算法和最小二乘法、特征值法对仿真数据进行平面拟合,且采用本文提出的算法,分别对含有不同程度误差和异常值的点云数据进行拟合计算.研究结果表明:该算法适用于存在误差和异常值的点云数据拟合,能稳定地得到较好的平面参数估值,具有较强的稳健性.