一种求解TSP初始化种群问题的方法

为提升求解TSP问题的计算效率和求解精度,针对初始种群构造问题进行研究,提出了域内三角概率选择自适应邻域算法。为使邻域半径能够适应城市的分布情况,设计了一种基于Sigmoid函数的邻域半径自适应函数;为了避免在邻域内盲目随机地选择下一站城市,提出了在邻域内利用三角概率选择模型选择下一个城市。以自动化立体仓库安排出入库作业顺序优化作为TSP研究问题,通过Matlab仿真计算,将该算法和邻域法生成的初始种群进行对比分析,并分别用该算法和随机生成的初始种群作为遗传算法的初始种群进行计算。证明了该算法可快速生成高质量的初始种群,大大提升了求解TSP问题的计算效率和求解精度。     

对置活塞二冲程汽油机缸内滚流的组织与利用

通过三维计算流体力学软件AVL-Fire模拟了对置活塞二冲程（OP2S）缸内直喷汽油机的扫气、混合气形成和燃烧过程,对比分析了3种不同的缸内流动组织方案,包括：平顶活塞加均匀扫气、平顶活塞加非均匀扫气和凹坑活塞加非均匀扫气对气流运动和扫气过程的影响。同时,针对采用非均匀进气腔的平顶活塞和凹坑活塞方案,分析混合气形成和燃烧过程。结果表明：均匀进气方式可组织较强的涡流,有利于扫气效率的提高;非均匀进气方式可组织滚流,有利于提高压缩过程缸内的湍动能。“凹坑活塞加非均匀扫气”的扫气系统更有利于组织滚流和维持缸内湍流强度,并在点火时刻火花塞附近形成可供稳定着火的可燃混合气。凹坑活塞燃烧室相比平顶活塞燃烧室,其缸内湍动能提高了1.5倍,燃油蒸发量提高了10%,有利于形成均匀混合气和加速燃烧过程。     

基于双谱熵模型的故障模式识别

提出利用双谱计算信号的双谱熵,并作为特征参量进行故障模式识别的方法。分析了振动信号双谱的特征,在子空间分布概率下,推导了基于能量分布的双谱熵计算方法。在理论推导分析的基础上,进行了某齿轮箱在4种工况下的振动信号提取实验,建立了齿轮箱故障模式识别BP神经网络。最后将双谱熵特征参量作为输入,对设置了4种故障工况的齿轮箱进行了故障模式识别,成功地判别了4种工况,验证了方法的有效性。     

TC4钛合金等温锻造过程的数值模拟和实验研究

实验研究了TC4钛合金等温锻造的工艺过程,并采用DEFORM-3D有限元软件对其进行数值模拟.结果表明,采用等温锻造工艺成功地锻造出某钛合金复杂结构件,锻件轮廓清晰、表面光洁、尺寸精度高,金属流线分布合理,组织性能超过常规机加工件,其材料用量相对于常规机加工件提高到60%.通过软件模拟,了解锻件成形的应力、应变及金属流动等信息,为工艺的确定和设备的选取提供了理论依据.     

薄壁罐气压胀形参数优化研究

为提高金属薄壁罐气压胀形的成形质量,减少壁厚减薄严重及皱折破裂等成形缺陷,采用数值模拟的方法,分析了摩擦因数、模具圆角半径、坯料厚度、胀形压力对壁厚减薄率、最大应力值、轴向收缩的影响规律,试验验证与数值模拟结果吻合。研究结果对工艺优化和过程控制具有实用意义。     

齿轮超声加工纵向振动系统的设计与实验研究

为了解决齿轮超声加工纵向振动系统设计问题,基于纵向振动动力学方程,利用结合面的力、位移振动耦合与边界条件,提出纵向振动变幅器的非谐振设计方法,推导了频率方程;应用Matlab2011Ra对变幅器未知尺寸、振型分布进行理论数值求解,并利用ANSYS12.0对所设计变幅器进行模态分析与谐响应分析．设计加工了不同模数齿轮的纵向振动变幅器,基于C6140车床搭建了齿轮超声加工纵向振动系统的激光测振仪测试系统,进行谐振实验．变幅器的谐振频率和振幅经理论求解、有限元分析、实验测试对比,各自的最大求解偏差都小于5%,可以满足工程应用需要.研究表明：可应用力、位移耦合非谐振设计方法,完成中小模数齿轮变幅器的纵向振动系统设计,对齿轮超声振动系统设计具有理论指导和工程应用价值．     

基于混合算法的单堆垛机多巷道拣选作业调度研究

针对单堆垛机在多巷道自动化仓库中的拣选路径规划问题,建立了求解含周转箱约束的堆垛机拣选作业最短路径数学模型,提出用遗传模拟退火混合算法进行求解。通过Matlab分别对不同算法进行实例仿真,结果表明：该混合算法克服了遗传算法早熟,以及模拟退火算法收敛性慢的缺点,求出的解更优,收敛速度更快,稳定性更好。该混合算法具有可行性和高效性。     

对置活塞二冲程汽油机活塞运动规律匹配分析

对置活塞二冲程汽油机活塞的相对运动规律,影响扫气过程的扫气正时和扫气持续期,而活塞相对运动规律主要取决于对置活塞运动相位差和曲柄连杆比。在采用MATLAB/Simulink进行对置曲柄连杆机构运动学分析的基础上,通过建立扫气系统的三维流体动力学仿真模型,并利用一维工作过程仿真提供的初始条件和边界条件,开展了对置活塞运动相位差和曲柄连杆比对扫气过程的影响规律研究,获得了较高的扫气效率和捕获率,实现了对置活塞相对运动规律的优化匹配。活塞运动相位差只影响扫气正时而不影响扫气持续期;曲柄连杆比同时影响扫气正时和扫气持续期。在内止点附近,不同的活塞运动相位差影响活塞相对运动速度和最小工作容积;不同的曲柄连杆比只影响活塞相对运动速度而不改变最小工作容积。     

Development of rubberized syntactic foam

This study explored a novel hybrid syntactic foam for composite sandwich structures. A unique microstructure was designed and realized. The hybrid foam was fabricated by dispersing styrene–butadiene rubber latex coated glass microballoons into a nanoclay and milled glass fiber reinforced epoxy matrix. The manufacturing process for developing this unique microstructure was developed. A total of seven groups of beam specimens with varying compositions were prepared. Each group contained 12 identical specimens with dimensions 304.8 mm × 50.8 mm × 15.2 mm. The total number of specimens was 84. Among them, 42 beams were pure foam core specimens and the remaining 42 beams were sandwich specimens with each foam core wrapped by two layers of E-glass plain woven fabric reinforced epoxy skin. Both low velocity impact tests and four-point bending tests were conducted on the foam cores and sandwich beams. Compared with the control specimens, the test results showed that the rubberized syntactic foams were able to absorb a considerably higher amount of impact energy with an insignificant sacrifice in strength. This multi-phase material contained structures bridging over several length-scales. SEM pictures showed that several mechanisms were activated to collaboratively absorb impact energy, including microballoon crushing, interfacial debonding, matrix microcracking, and fiber pull-out; the rubber layer and the microfibers prevented the microcracks from propagating into macroscopic damage by means of rubber pinning and fiber bridge-over mechanisms. The micro-length scale damage insured that the sandwich beams retained the majority of their strength after the impact.     

Electrochemical study of corrosion behavior of graphene coatings on copper and aluminum in a chloride solution

Electrochemical characteristics and corrosion behavior of graphene coatings on Cu and Al in a 0.1 M NaCl solution were investigated. The graphene coatings were deposited on a Cu surface by chemical vapor deposition. Multiple graphene layers were then mechanically transferred from the growth substrate, Cu, onto Al surface by a transfer technique. The corrosion stability of graphene coatings was determined by electrochemical impedance spectroscopy and open circuit potential, while the corrosion rate was evaluated using potentiodynamic sweep measurements. Surface morphologies of the graphene coatings were analyzed by scanning electron microscopy and energy dispersive spectroscopy. Obtained results indicate that Cu coated with graphene grown using chemical vapor deposition shows corrosion-inhibiting properties in 0.1 M NaCl. On the other hand, Al coated with a multilayer graphene film mechanically transferred from the Cu surface exhibits electrochemical characteristics similar to an Al oxide on bare Al. Better protective properties of graphene coating on Cu compared to the graphene coating on Al were observed, probably due to the breakage of Al oxide film, causing the corrosion of Al to proceed rapidly in the presence of chloride electrolyte.