基于无人机的高层住宅最后“一百米”配送优化

针对城市高层住宅顾客对上门配送服务的需求，借助无人机停放平台，考虑包裹异质性以及无人机在不同配送阶段的精确能耗，构建以无人机飞行成本和能耗成本最小为目标，以无人机容量、电池组容量等为约束的高层住宅无人机上门配送模型，解决“垂直位置最后一百米配送”问题。基于此模型，设计带变邻域下降(VND)搜索的混合蚁群算法(HACO-VND)，引入4个算子进行变邻域下降搜索，为了提高算法的求解性能，提出两种局部搜索算子组合，根据顾客点数量使用不同的算子组合。实验结果表明，HACO-VND算法较CPLEX在求解精度与求解时间方面更优，特别是在大中型算例中表现出较佳性能。参数分析表明，高层住宅楼层数越多，无人机单次 飞行的能耗利用率越大，无人机容量与电池组容量共同对配送方案产生影响。为以后无人机送货上门服务方面的研究提供参考和思路。     

Influence of initial heeling angle on ship roll motion response北大核心CSCD

[目的]系统地研究初始横倾角对随机横浪下船舶横摇运动响应的影响。[方法]以路径积分法为基础,通过数值求解控制横摇运动微分方程概率属性的Fokker-Planck方程,得到横摇运动响应的概率分布。[结果]结果显示,初始横倾角对船舶横摇运动响应谱的影响有限,但对横摇角概率分布以及横摇运动响应极值分布的影响十分明显,且会造成船舶安全性的显著恶化。[结论]路径积分法可作为研究随机海浪下船舶横摇运动特性的有效数值方法。     

基于可靠性方框图与蒙特卡洛仿真的船舶配电网可靠性分析方法

国船舶工业发展迅速,尤其在近几年迎来了跨越式的发展。船舶建设工业的发展能充分体现一个国家的经济和国防建设水平。但船舶配电网拓扑结构与陆上电网不尽相同,其运行环境非常恶劣,供电连续性和可靠性成为衡量船舶生命力的重要指标,同时也深刻影响大型船舶的平均寿命。因此,可靠性研究在船舶建设中发挥着越来越重要的作用。本研究以典型大型船舶中压配电网结构为研究对象,在全系统元件正常运行时相互独立的情况下,重点研究不可维修与可维修下的系统可靠度、MTBF、可用度、停运时间和失效数等,并进行详细的分析与讨论。首先,本文综合考察各种可靠性分析方法的适用性和准确性,选择利用可靠性框图、最小路集分析法计算并分析不可维修情况下系统的可靠度、平均故障间隔时间等可靠性指标；接着,本文简述了配电网的多种维修任务类型,并采用最小路集法与蒙特卡洛仿真法相结合的方法计算并分析可维修系统的可用度、停电时间、失效数等指标。本文研究结果对船舶配电网的设计、建造、运行和维修等具有积极的意义。     

海洋核动力平台全频段舱室噪声预报与降噪方案研究

随着新规范对船舶及海上工作平台提出了更高要求，舱室噪声的控制及优化设计越来越受到人们的关注。本文首先对全频段舱室噪声预报软件——VA One软件统计能量分析理论及软件概况进行了阐述，其次应用该软件对海洋核动力平台进行几何建模与仿真计算。通过对舱室仿真计算结果与标准指标要求的对比分析，在设计阶段提出了海洋核动力平台舱室空气噪声综合治理降噪方案，该措施可以缩短建造周期、降低制造成本，提高海洋核动力平台的舒适性与安全性，具有十分重要的经济效益和社会效益。     

减振降噪技术的应用设计

本文针对某型号测量船主要噪声振动源采取相应技术措施进行减振降噪综合治理研究，其中主机采用低频大载荷隔振器的单层隔振、辅机采用浮筏隔振装置、机座采用局部阻尼处理等措施。由于该船采用了先进的浮筏技术及其他隔振措施，在提高船上测量系统读取数值精度的同时，大大改善了船上水声设备测绘工作环境和船员的生活环境，提高了该船的设备使用寿命和船员体力极限。本船自噪声在低航速时已淹没在海洋背景噪声之中。特别是该船减振降噪装置在系统的声学匹配设计方面取得了进展，经实船验证，效果良好，证明该设计方法可行，对减振降噪技术在各型舰船上的工程应用开发研究有一定借鉴作用。     

应用巴列特统计方法降低工程成本的实践

文章简述了巴列特（Pareto）统计分配法的基本要点，并结合天津港南疆工作船码头工程的施工实例，应用巴列特法进行了分析，明确了该工程中节省成本的重点项目、内容及节省成本的贡献率，从而有针对性地制定了相应的成本控制和节约措施，经过实践，收到了较好的效果。     

Fluxes of dissolved inorganic carbon in three estuarine systems of the Cantabrian Sea (north of Spain)

The diffusive and in situ fluxes of dissolved inorganic carbon (DIC) and total alkalinity (TA) have been measured and an estimation has been made of the water–atmosphere fluxes of CO₂ in three estuarine systems of the Cantabrian Sea during the spring of 1998. Each of these systems undergoes a different anthropogenic influence. The diffusive fluxes of dissolved inorganic carbon and total alkalinity obtained present values ranging between 0.54–2.65 and 0.0–2.4 mmol m⁻² day⁻¹, respectively. These ranges are in agreement with those of other coastal systems. The in situ fluxes are high and extremely variable (35–284 mmol TA m⁻² day⁻¹, 43–554 mmol DIC m⁻² day⁻¹ and 22–261 mmol dissolved oxygen (DO) m⁻² day⁻¹), because the systems studied are very heterogeneous. The values of the ratio of the in situ fluxes of TA and DIC show on average that the rate of dissolution of CaCO₃ is 0.37 times that of organic carbon oxidation. Equally, the interval of variation of the relationship between the benthic fluxes of inorganic carbon and oxygen (F_DIC/F_DO) is very wide (0.3–13.9), which demonstrates the different contributions made by the processes of aerobic and anaerobic degradation of the organic matter, as well as by the dissolution–precipitation of CaCO₃. The water–atmosphere fluxes of CO₂ present a clear dependence on the salinity. The brackish water of these systems (salinity<20), where maximum fluxes of 989 mmol m⁻² day⁻¹ have been estimated, act as a source of CO₂ to the atmosphere. The more saline zones of the estuary (salinity>30) act as a sink of CO₂, with fluxes between −5 and −10 mmol m⁻² day⁻¹.     

生活小区管道直饮水的工艺及经济分析

分析了生活小区管道直饮水的净水工艺,对工艺流程各单元的原理和作用进行了阐述,并进行了经济分析,和桶装直饮水比较,管道直饮水的价格较低,表明生活小区管道直饮水系统有较大的发展空间。     

Organic carbon budget for the Gulf of Bothnia

We calculated input of organic carbon to the unproductive, brackish water basin of the Gulf of Bothnia from rivers, point sources and the atmosphere. We also calculated the net exchange of organic carbon between the Gulf of Bothnia and the adjacent marine system, the Baltic Proper. We compared the input with sinks for organic carbon; permanent incorporation in sediments and mineralization and subsequent evasion of CO₂ to the atmosphere. The major fluxes were riverine input (1500 Gg C year^− 1), exchange with the Baltic Proper (depending on which of several possible DOC concentration differences between the basins that was used in the calculation, the flux varied between an outflow of 466 and an input of 950 Gg C year^− 1), sediment burial (1100 Gg C year^− 1) and evasion to the atmosphere (3610 Gg C year^− 1). The largest single net flux was the emission of CO₂ to the atmosphere, mainly caused by bacterial mineralization of organic carbon. Input and output did not match in our budget which we ascribe uncertainties in the calculation of the exchange of organic carbon between the Gulf of Bothnia and the Baltic Proper, and the fact that CO₂ emission, which in our calculation represented 1 year (2002) may have been overestimated in comparison with long-term means. We conclude that net heterotrophy of the Gulf of Bothnia was due to input of organic carbon from both the catchment and from the Baltic Proper and that the future degree of net heterotrophy will be sensible to both catchment export of organic carbon and to the ongoing eutrophication of the Baltic Proper.     

FAO 核心子系统安全完整性等级 评价方法研究

为探究如何更加实际地评价全自动运行(FAO)系统核心子系统功能的安全完整性等级(SIL),通过研究欧 洲电工标准化委员会(CENELEC)标准中风险模型的构造,给出风险降低因素(RRF)的定义;通过定义的风险降低 因素,建立可容忍事故率(TAR)与可容忍危害率(THR)的换算关系,进而评估出 FAO 系统核心子系统功能次级危 害的可容忍危害率;最后通过其与安全完整性等级的对应关系,得到核心子系统功能的安全完整性等级。应用结 果表明：结合实际的 FAO 工程项目应用成果,给出风险降低因素中各要素的具体示例,可供借鉴;与直接采用 可容忍事故率保守估计安全完整性等级的方法相比,在考虑风险降低因素后评估得到的安全完整性等级更接近实 际情况。