基于支持向量机方法的医学图像分割

医学图像分割是图像分割研究领域的难点问题。支持向量机方法被看作是对传统学习分类方法的一个好的替代,特别在小样本、高维情况下,具有较好的泛化性能。论文采用支持向量机方法对医学图像进行分割研究。实验结果表明,支持向量机方法是一种很有前景的医学图像分割技术。     

船用中速柴油机加载过程油气匹配控制策略研究船用中速柴油机加载过程油气匹配控制策略研究

根据柴油机加载过程转速调节受增压空气压力抑制的特点, 研究了船用中速柴油机瞬态加载过程用压气机叶片端高压空气喷射方式进行补气的增压压力变化特性, 并根据柴油机力矩不均衡产生的动态变化特点, 结合适应柴油机时滞特性的比例-积分-微分（PID）控制方法, 形成了柴油机瞬态加载过程油气匹配的调速控制策略。经某船用中速柴油机台架试验验证证实, 采用加载过程压气机叶片端高压空气喷射方式进行补气的油气匹配控制策略, 使柴油机0%~50%负荷加载过程瞬态调速率从4.9%优化至3.8%, 稳定时间从3.1 s优化至2.0 s; 50%~100%负荷加载过程瞬态调速率从2.9%优化至2.3%, 稳定时间从2.4 s优化至1.8 s。     

Influence of additives and concentration of WC nanoparticles on properties of WC−Cu composite prepared by electroplating

The effects of additives (polyethylene glycol (PEG), sodium dodecyl sulfate (SDS)) and WC nano-powder on the microstructure, relative density, hardness and electrical conductivity of electroplated WC−Cu composite were investigated. The preparation mechanism was also studied. The microstructure of samples was analyzed by XRD, SEM, EDS, TEM and HRTEM. The synergistic effect of PEG and SDS made the WC−Cu composite more compact during the electroplating process. The hardness of WC−Cu composites increased with the increase in WC content, while the electrical conductivity decreased with the increase in WC content. The density of samples tended to increase initially and then decreased with increase in the additive content. When the electroplating solution contained 10 g/L WC nano- powder, 0.2 g/L PEG and 0.1 g/L SDS, the WC−Cu composite exhibited hardness of HV 221 and electric conductivity of 53.7 MS/m. Therefore, the results suggest that WC−Cu composite with excellent properties can be obtained by optimizing the content of additives and WC particles.     

船舶三维管路智能布局优化算法

针对船舶在三维环境下管路布局约束多，工程规则难以量化，难以确定合适的优化评价函数等问题，提出一种新的船舶管路自动布局方法。首先，采用轴平行包围盒法（AABB）对船体和船内设备进行简化，将其离散成空间节点并赋予初始信息素和能量值，对空间障碍物进行标记，并对主要的敷管规则给出了具体的量化形式；其次，将快速扩展随机树（RRT）算法和蚁群优化（ACO）算法进行结合，引入方向选择策略、避障策略和变步长策略，提升了算法搜索效率和成功率，通过建立优化评价函数，利用ACO对路径进行循环迭代优化，以期得到满足工程规则的综合最优解；最后，采用计算机模拟的船舱空间布局环境进行管路自动敷设仿真实验，验证了所提方法的有效性和实用性。     

基于博弈论的散货港口堆场堆位分配算法

针对散货港口因堆场面积有限，在货物进港作业时，如何在进出港货物动态变化的情况下兼顾作业效率并安排货物在堆场中合理堆放的问题，提出了一种基于博弈论的散货港口堆场堆位分配算法（BSAABG）。首先，将堆位分配行为建模为动态博弈，并运用满足均衡分析该博弈。假设每票货物对分配所得效益都有一个预期，当所有货物都达到预期时博弈即达到满足均衡。然后，使用基于博弈论的散货堆场堆位分配算法BSAABG求解之前建立的该模型，从理论上证明算法的收敛性。实验结果表明，当货物票数为20时，基于博弈论的散货堆场堆位分配算法BSAABG的货物平均满足度比人工分配方法（用贪心算法（GA）模拟）和基于规则的堆位分配算法（SABR）分别提高了62.5%和18.2%，堆场分配效益是贪心算法（GA）的6.83倍，是SABR的3.22倍。可见所提算法能够有效地提高货物的平均满足度和堆场分配效益。     

动态需求跟踪中多义关键词的语义判断方法

虽然与信息检索（IR）方法相比，基于本体的动态需求跟踪方法能提高跟踪链的精度，但构建一个合理、有效的本体特别是领域本体是一个相当复杂和繁琐的过程。为了减小构建领域本体带来的时间成本和人力成本，通过将修饰词和通用本体相结合，提出基于修饰词本体的关键词语义判断方法（MOKSJM）。首先，对关键词和修饰词的搭配关系进行分析；然后，采用修饰词本体结合规则的方式来确定关键词的语义，以避免关键词的多义性对动态需求跟踪结果造成的偏差；最后，根据上述分析的结果，对关键词语义作出调整，并通过相似度得分来体现其语义。修饰词在需求文档、设计文档等中数量较少，因此建立修饰词本体所带来的时间成本和人力成本相对较小。实验结果表明，MOKSJM与基于领域本体的动态跟踪方法在召回率相当时，精度差距更小；与向量空间模型（VSM）方法相比，MOKSJM能有效提高需求跟踪结果的精度。     

An anchorage planning strategy with safety and utilization considerations

Heavy maritime traffic and the subsequent increase in vessel density in anchorages have recently become a focal issue in maritime traffic safety. In this study, we consider the problem of determining the optimal berth locations of incoming vessels in an anchorage area with the goals of maximizing utilization and minimizing the risk of accidents. We introduce novel performance metrics aimed at measuring achievement of these two goals. In this context, we propose a multi-objective optimization strategy and benchmark it against current state-of-the-art anchorage planning algorithms using real-world data as well as Monte Carlo simulations. Our results indicate that the proposed strategy yields much safer berth locations while maintaining similar utilization levels.     

In-plane shear behaviour of fibre composite sandwich beams using asymmetrical beam shear test

The in-plane shear behaviour of a new generation composite sandwich beam made up of glass fibre skins and modified phenolic core material was investigated to determine its application as shear loading component in a structural beam. Iosipescu shear test was conducted to characterise the shear properties of the fibre composite skins and the phenolic core material. The fibre composite sandwich beams were then tested under asymmetrical beam shear to determine its behaviour under in-plane shear loading. The results show that the in-plane shear behaviour of the composite sandwich beam is similar to that of the skins. A theoretical prediction of the in-plane shear strength of the composite sandwich beam was proposed and showed a good agreement with the experimental results. Based on the results of the study, the asymmetrical shear test is recommended as a test method for determining the shear properties of sandwich structures with high strength core materials.     

大跨多塔悬索桥纵向地震碰撞反应参数研究

针对大跨桥梁在地震作用下伸缩缝处的碰撞现象,以一座大跨三塔悬索桥为工程背景,建立了考虑墩柱弹塑性的空间非线性碰撞模型,采用非线性时程法详细分析了碰撞刚度、碰撞初始间隙等因素对碰撞效应的影响.分析结果表明:碰撞刚度在可能范围内取值,碰撞效应的变化不明显,碰撞刚度不是敏感参数;碰撞初始间隙是一个敏感参数,其大小对于碰撞效应有一定的影响,初始间隙比的变化对主引桥相对位移和引桥梁端位移影响比较明显.