小生境遗传算法的多刚体系统动力学参数优化设计

在分析多刚体系统动力学参数优化问题特点的基础上,针对用传统优化方法和标准遗传算法求解这一类问题时存在的问题,提出了一种改进的小生境遗传算法。采用最优保存策略和高斯变异算子,保证算法的稳定收敛和提高算法在每个峰值附近的局部搜索能力。将该方法用于5自由度汽车悬架系统动力学参数优化设计问题,结果表明该方法在收敛速度和获得全局最优解方面部有很大提高。     

基于遗传-二次规划法的封闭差动人字齿轮传动系统混合优化设计

采用变位齿轮正传动方式,建立了以减轻传动系统重量为优化目标的封闭差动人字齿轮传动系统优化数学模型。利用MATLAB优化工具箱中的遗传算法和二次规划算法优化函数进行混合优化。研究结果表明:把遗传算法的结果作为二次规划法优化的初值,解决了二次规划法优化优化设计变量初值难于确定问题;与单纯采用遗传算法或二次规划算法相比,该混合优化方法计算的优化值明显改善,系统重量显著降低;该优化方法为获得大规模的非线性约束优化设计精确的全局最优解提供了一种简单可行的解决办法。     

基于免疫算法的装配序列规划问题求解

针对装配序列规划问题提出了一种模拟生物免疫系统的免疫算法,并给出了亲和力计算、抗体生成、免疫选择、记忆细胞更新等的具体实现方法.实例仿真结果表明,免疫算法在装配序列规划问题的求解中充分体现了免疫系统的多样性、免疫自我调节、免疫记忆和分布式并行等特点.免疫算法较遗传算法具有更强的全局搜索能力和更快的收敛速度,有效地改善了全局收敛性能和收敛速度.     

混合动力汽车能量管理策略的四步骤设计方法

以行星齿轮结构的混合动力汽车的动力系统为研究对象,提出了一套能量管理策略的四步骤设计方法。第一步,引入混杂动态系统理论来描述既有离散事件动态系统特征又有连续变量动态系统特征的混合动力系统;第二步,利用序列二次项规划算法和动态规划算法分别求解出最佳功率分配和最佳工作模式切换序列的基本规律;第三步,建立基于规则和模糊规则的能量管理策略;第四步,利用遗传算法对第三步已经建立的工作模式切换规则和功率分配的模糊控制规则中的参数进行优化,以获得更佳的控制效果。     

几何约束求解的新方法--基于共轭梯度法的混合遗传算法

将几何约束问题转化为数值优化问题.综合遗传算法的全局搜索能力和共轭梯度法的局部搜索能力,提出了一种混合算法.将此混合算法应用于几何约束求解中.实验表明该算法具有全局最优性和收敛性.     

遗传算法在机械工程优化设计中的应用研究

根据遗传算法的基本理论,并结合机械工程优化设计的特点,对传统遗传算法的遗传操作作出改进,提出了一种将柯西机和遗传算法相结合的改进遗传算法,并应用于机械工程优化设计问题的全局最优解求解。计算实例说明,改进的遗传算法不仅增强了传统遗传算法的全局收敛性,能够有效地求得优化问题的全局极小点,而且还提高算法进行后期的收敛速度。     

混合动力汽车动力传动系统控制策略优化研究

模糊控制策略应用在混合动力汽车上有鲁棒性和非线性能力强、实时性好的优势,但是控制策略的制定主要根据专家经验,具有一定主观性,一般情况下无法获得全局最优。将遗传算法应用于求解混合动力汽车控制策略参数优化问题。以某并联式混合动力汽车为原型,设计模糊控制策略,并采用遗传算法以最小化油耗和排放为目标对控制策略进行优化。仿真结果表明,应用遗传算法经过离线参数优化可以找到一组全局最优的参数,使得油耗和排放都有明显降低。     

动态惩罚函数非线性规划遗传算法及在汽车变速器中的应用

针对传统遗传算法在求解非线性规划问题时局部搜索能力较弱,惩罚函数求解精度不高的缺陷,将非线性规划算法引入到遗传算法中,提出一种基于动态惩罚函数的非线性规划遗传算法,将遗传算法的全局寻优能力和非线性规划算法的局部寻优能力结合起来,并引入动态惩罚函数,根据不可行点到可行域的距离和可行度自适应的调整惩罚项的值,从而能够快速求出全局最优解。介绍了动态惩罚函数的设计、改进遗传算法的关键技术和流程。最后,以某型号汽车变速器的优化设计验证了算法的合理性。与传统遗传算法相比,改进后的遗传算法解的质量、收敛速度明显提高,因而为遗传算法的改进提供了一种新的思路。     

机器人逆运动学的模拟退火自适应遗传算法

对5自由度关节型机器人的运动特点进行分析,并建立该机构的运动模型.在基本遗传算法的基础上,针对求解串联机器人运动学逆解的特殊性,为了消除遗传算法易陷入局部最优或早熟问题,提出一种新颖的改进遗传算法,采用模拟退火和自适应策略,保证其收敛性并加快收敛速度.仿真结果表明,该算法求解精度高,收敛速度快,且稳定性好.     

遗传算法在混合动力汽车控制策略优化中的应用

提出了一种基于浮点数编码遗传算法的混合动力汽车控制策略参数优化新方法。以一辆实际混合动力汽车样车的逻辑门限控制策略为例，分析并建立了控制策略参数优化的有约束非线性规划模型，其目标函数包含最小化油耗和排放。提出了采用稳态进化模型和浮点数编码遗传算法的参数优化方法，用于求解一组最优的控制策略参数。仿真结果表明，该方法可以找到一组全局最优的参数，将其用作离线参数优化，可以大大缩短控制器的实车标定时间。     

新型行星混联式混合动力系统匹配与优化

以一种新型行星混联式混合动力系统作为研究对象,通过对电机、离合器与发动机的协调控制,可方便地实现高低速状态下的纯电驱动、发动机直驱、混合驱动及制动能量回收4种工作模式的切换。为了评估其燃油经济性和动力性,参照国内某品牌混合动力客车性能参数,对发动机、ISG电机、发电机和双行星排齿轮机构的基本性能参数进行匹配。通过集成了CRUISE与MATLAB的ISIGHT的优化平台,进行行星混联式混合动力总成匹配参数的优化。优化匹配仿真结果表明:在保证整车动力性的前提下,燃油经济性较优化前提高了19.3%。     

Fuzzy-model-based hybrid predictive control

In this paper we present a method of hybrid predictive control (HPC) based on a fuzzy model. The identification methodology for a nonlinear system with discrete state-space variables based on combining fuzzy clustering and principal component analysis is proposed. The fuzzy model is used for HPC design, where the optimization problem is solved by the use of genetic algorithms (GAs). An illustrative experiment on a hybrid tank system is conducted to demonstrate the benefits of the proposed approach.     

Advances in hybrid laser joining

This paper presents vibration reduction control of a voice coil motor (VCM)-driven actuator for SPM applications. We had developed a VCM nanoscanner. The scanner has flexure hinges structure. However, the VCM nanoscanner has some problems of thermal drift and small damping compared to the PZT driven nanoscanner. Especially, the small damping coefficient of the VCM nanoscanner causes mechanical vibration when the control input signal is near to the resonance frequencies of the scanner. Additionally, disturbance to the VCM scanner and electronic noise in the sensor also causes the mechanical vibration when they are near to the resonant frequencies. The mechanical vibration reduces the servo bandwidth as well as the accuracy, which deteriorates the AFM image of the samples. We design input shaping prefilter to reduce the signal applied to the VCM nanoscanner and electronic noise in the sensor whose frequency is close to the resonant frequency of the VCM nanoscanner. We measure the time and frequency response of the VCM scanner without using the prefilter and with using the prefilter. Finally, the topology images of a bare wafer are measured and compared using the AFM.     

Coaxial lower hybrid plasma source

We report the development of a coaxial radio frequency plasma source capable of producing pulsed plasmas of moderately high density (10(13)-10(14) cm(-3)). This device may be useful either as a general purpose laboratory plasma source or as an auxilliary source for a variety of fusion applications, such as providing target plasmas for mirror machines or producing cold plasma blankets to help isolate the hot plasma core of a toroidal plasma from the walls.     

High accuracy FIONA-AFM hybrid imaging

Multi-protein complexes are ubiquitous and play essential roles in many biological mechanisms. Single molecule imaging techniques such as electron microscopy (EM) and atomic force microscopy (AFM) are powerful methods for characterizing the structural properties of multi-protein and multi-protein-DNA complexes. However, a significant limitation to these techniques is the ability to distinguish different proteins from one another. Here, we combine high resolution fluorescence microscopy and AFM (FIONA-AFM) to allow the identification of different proteins in such complexes. Using quantum dots as fiducial markers in addition to fluorescently labeled proteins, we are able to align fluorescence and AFM information to ≥8 nm accuracy. This accuracy is sufficient to identify individual fluorescently labeled proteins in most multi-protein complexes. We investigate the limitations of localization precision and accuracy in fluorescence and AFM images separately and their effects on the overall registration accuracy of FIONA-AFM hybrid images. This combination of the two orthogonal techniques (FIONA and AFM) opens a wide spectrum of possible applications to the study of protein interactions, because AFM can yield high resolution (5-10 nm) information about the conformational properties of multi-protein complexes and the fluorescence can indicate spatial relationships of the proteins in the complexes.     

An improved hybrid multi-objective parallel genetic algorithm for hybrid flow shop scheduling with unrelated parallel machines

In this paper, we address the hybrid flow shop scheduling problems with unrelated parallel machines, sequence-dependent setup times and processor blocking to minimize the makespan and maximum tardiness criteria. Since the problem is strongly NP-hard, we propose an effective algorithm consisting of independent parallel genetic algorithms by dividing the whole population into multiple subpopulations. Each subpopulation will be assigned with different weights to search for optimal solutions in different directions. To further cover the Pareto solutions, each algorithm is combined with a novel local search step and a new helpful procedure called Redirect. The proposed Redirect procedure tries to help the algorithm to overcome the local optimums and to further search the solution space. When a population stalls over a local optimum, at first, the algorithm tries to achieve a better solution by implementing the local search step based on elite chromosomes. As implementing the local search step is time-consuming, we propose a method to speed up the searching procedure and to further increase its efficiency. If the local search step failed to work, then the Redirect procedure changes the direction and refreshes the population. Computational experiments indicate that our proposed improving procedures are thriving in achieving better solutions. We have chosen two measures to evaluate the performance of our proposed algorithms. The obtained results clearly reveal the prosperity of our proposed algorithm considering both measures we have chosen.     

基于模糊理论的混合布局设备单元划分

针对设备混合布局方案设计过程中忽略了设备单元划分的不足,运用模糊理论以设备间在某种特性上的模糊关系为依据进行设备单元划分,并通过置信水平λ的变化率找出最优的模糊聚类.以某日化企业面膜生产车间为例,详细阐述了如何利用模糊理论进行设备单元划分,对解决类似问题具有一定的借鉴作用.     

混合式降压型PFC变流器的研究

针对降压型功率因数校正(Buck PFC)变流器输入电流存在固有死区、功率因数低、谐波失真严重的问题,提出了一种Buck PFC变流器与辅助变流器相结合的混合式降压型PFC变流器,通过在输入电压瞬时值低于输出电压时让辅助变流器工作的办法,弥补了输入电流死区,保持Buck PFC变流器输出电压低、低输入电压下仍能保持高效率等优点的同时显著改善了其输入电流波形。研究结果表明,混合式降压型PFC变流器在90 V最低交流输入电压下的功率因数为0.99,相比于Buck PFC变流器提高0.09;115 V交流输入电压下总谐波失真仅为8%,相比于Buck PFC变流器降低20%左右;效率相比于Buck PFC变流器仅下降0.5%。