基于遗传算法的船体分段装配优化

优化装配序列对提高造船生产效率具有非常重要的意义。选择典型的船体分段为研究对象,首先结合生产实际将装配结构层次化,生成子装配体以缩短遗传算法中染色体的长度,加快算法向最优解的收敛速度,提高装配规划效率;然后应用遗传算法得到船体分段最优装配序列;最后利用CATIA软件对分段进行建模,并完成分段虚拟装配过程的仿真演示。实例分析结果验证了应用遗传算法的可行性与有效性,显示其有助于优化船体分段装配顺序。     

一种中分自卸汽车列车控制系统的设计

本论文介绍了一种可实现多卸货次序的中分自卸汽车列车,它通过电控气、气控液的方式分别控制汽车列车两货箱侧箱板开启、底板中部突起进行卸货,前、后箱卸货次序不受限制,避免了传统自卸车对车厢长度要求高、稳定性差、对卸货场地要求严格、无法加装全挂列车等缺点,使货物堆放更到位,避免二次转运造成的资源浪费,提高了卸货效率。     

A multi-path progression model for synchronization of arterial traffic signals

To contend with congestion and spillback on commuting arterials, serving as connectors between freeway and surface-street flows, this paper presents three multi-path progression models to offer progression bands for multiple critical path-flows contributing to the high volume in each arterial link. The first proposed model is a direct extension of MAXBAND under a predetermined phasing plan, but using the path-flow data to yield the progression bands. The second model further takes the phase sequence at each intersection as a decision variable, and concurrently optimizes the signal plans with offsets for the entire arterial. Due to the competing nature of multi-path progression flows over the same green duration, the third model is proposed with a function to automatically select the optimal number of paths in their bandwidths maximization process. The results of extensive simulation studies have shown that the proposed models outperform conventional design methods, such as MAXBAND or TRANSYT, especially for those arterials with multiple heavy path-flows. The research results from this study have also reflected the need to collect more traffic pattern data such as major path-flow volumes, in addition to the typical intersection volume counts.     

基于疲劳驱动力能量损伤参数修正的非线性疲劳寿命预测

针对疲劳驱动力能量模型中变幅载荷间交互因子难以确定的问题,考虑载荷大小次序、载荷间的干涉以及疲劳损伤程度等因素对变幅载荷作用下损伤累积规律的影响,在引入能量准则确定损伤参数的基础上,将变幅载荷应力比、载荷循环比、疲劳损伤程度引入载荷间交互因子的计算,建立分别采用载荷循环次数比和实时疲劳损伤对交互因子进行修正的改进非线性疲劳寿命预测模型。根据Q235B和铝合金2种常用材料的焊接接头在多级变幅载荷作用下的试验数据,对改进的疲劳寿命预测模型的预测能力进行验证。结果表明:在变幅载荷作用下,改进的疲劳寿命预测模型能有效地对焊接结构的疲劳寿命进行预测,相比其他模型更接近于试验结果,且模型中仅含有2个比较容易通过试验确定的常规参数,无需引入其他参数,便于应用于实际工程结构的分析及设计。     

Development of signal optimization models for asymmetric two-leg continuous flow intersections

Despite extensive studies have been reported to address the operational issues of full Continuous Flow Intersection (CFI) in the literature, the asymmetric two-leg CFI, which is more applicable in practice, has not received adequate attentions yet. To satisfy such need, this study develops two signal optimization models for asymmetric CFI based on its unique geometric features. The first proposed model, following a two-step procedure, determines the cycle length, phase design and sequence, and green split in the first step and optimizes intersection offset in the second step. To benefit both intersections’ capacity maximization and signal progression design by optimizing phase plan and sequence, the second proposed model takes the Mixed-Integer-Linear-Programming (MILP) technique to concurrently optimize all signal control variables. With extensive case studies on a field site in Maryland, the simulation results prove that the proposed models can effectively provide signal progression to critical path-flows and prevent the potential queue spillover on the short turning bays/links. Further comparisons between the two proposed models reveal that the second model is more flexible in designing phase plan but the first model performs better in reducing link queue length.     

循环移位扩频水声通信技术研究磁

直接序列扩频通信系统因为其优良的相关性能,能够在较低的信噪比条件下进行可靠地工作,而拥有良好的抗多径和抗干扰的能力。这对于水声通信信息的无误码传输都是极为可贵的。可是,常规的直接序列扩频水声通信系统的通信速率很低,针对这一特点,论文研究了循环移位扩频水声通信方式,它在保证一定抗干扰能力的前提下成倍数提高直接序列扩频通信系统的通信速率。     

一种基于混沌序列的短时猝发水声通信方法

传统的水声通信发射信号持续时间长,隐蔽性差和抗干扰能力差。文中设计了一种短时猝发的扩频通信方法,用优选后的混沌序列作为多进制扩频通信的伪随机序列,并将同步信号和数据信息分别放置在不同的子通道上,极大地压缩了发射信号时长。仿真结果表明该方法能大大提高水声通信的抗扰和隐蔽性能。     

电气化铁道对电能质量影响的割集分析法

从分析电气化铁道对电网电能质量影响的需求出发,采用割集原理为局部电网建立了适合进行电能质量评估的模型,并利用模拟短路的方法得到了外部电网的广义多端口诺顿等值电路参数。在此基础上考虑多个干扰源共同作用下,评估了胶济电气化铁道负序与谐波对山东电网电能质量的影响。     

基于改进r-组合映射编码并行组合扩频通信系统的分析

介绍一种基于r-组合映射关系[1]的并行组合扩频通信系统,通过仿真发现该映射关系不能正确映射信源为全'0'时的信息数据,系统的误码性能不够理想.会产生错误平层.提出一种改进r-组合映射算法.解决了原r-组合映射算法映射不完全的问题.编码和交织技术是改善系统误码性能的有效方法,分析构造了一种编码并行组合扩频通信系统(coded-PC/SS),进一步改善了并行组合扩频系统的误码性能.在改进r-组合编码并行组合扩频系统下,通过仿真分析平衡Gold序列、m序列和Walsh序列对并行组合扩频通信系统性能的影响,得出平衡god序列更适合于并行组合扩频通信.     

交流电气化铁道牵引供电系统的综合补偿

为了保证电气化铁道牵引供电系统的功率因数、负序、网压和谐波符合国家规定的标准,以往的做法是在牵引供电系统中采取各种方式或装置分别进行补偿。本文提出采用一种可分相控制的SVC来实现综合补偿,并论证了它的可行性和优越性。