某中型校车顶部强度分析与结构改进

依照相关标准和法规,对某型校车车身顶部强度进行静态压溃、准静态压溃和整车跌落的仿真研究,系统评价校车车顶结构的抗压强度特性,并对关键承载结构进行改进。     

某高速艇用柴油机涡流燃烧室节流通道的优化计算分析

基于ECFM－3Z燃烧模型建立高速艇用涡流室柴油主机工作过程模型．在经过台架试验验证模型可靠性的基础上,详细分析了不同连接通道倾斜角下上止点前后5°CA时刻的燃烧室内流场的分布情况和上止点后15°CA时刻缸内的温度分布云图,以及由此得出的涡流燃烧室缸内燃烧过程的变化情况．结果表明：连接通道倾斜角度越大,涡流室内的能量损失越小;主燃室内的混合气速度越高,燃油与空气混合的越好．当倾斜角度由35°增大到45°时,缸内压力升高0.37 MPa,温度上升65 K且燃烧重心提前,NOx 排放上升,碳烟排放下降,功率得到提高．综合考虑,选择45°连接通道倾斜角对高速艇用柴油主机最为有利．研究结果为涡流室柴油机在高速艇上的应用提供参考．     

预应力连续梁桥悬臂施工截面应力监控研究

预应力连续梁桥在悬臂施工过程中截面应力始终处于变化状态,需要对其进行实时监控。结合工程实例,对预应力混凝土连续梁桥悬臂施工过程中控制截面应力的监控原理和方法进行了介绍。主要通过软件模拟分析和施工现场监测,实行理论与实际的对比控制,并对监测结果进行了误差分析,提出了消除误差的几点建议,保证了梁内截面应力满足设计要求和施工安全。     

钢渣薄层罩面沥青混合料试验研究与工程应用

研究了钢渣薄层罩面沥青混合料的路用性能并在实体道路工程中进行了应用。结果表明,钢渣强度和磨光值高,与沥青粘附性强,各项性能指标满足道路集料规范要求。以钢渣代替玄武岩集料制备的薄层罩面沥青混合料SMA-10和OGFC-5的马歇尔稳定度、水稳定性能及动稳定度等路用性能均满足规范要求,并表现出良好的抗变形、抗水损和耐久性能。钢渣薄层罩实体工程施工应用顺利,路面质量和应用效果良好。     

P-201遇水膨胀止水胶在厦门海底隧道中的应用

施工防排水是海底隧道施工成败的核心技术之一,厦门海底隧道设计防水等级为地下工程Ⅰ级防水,要求无渗漏和结构表面无湿渍.文章主要介绍了P-201遇水膨胀止水胶在厦门海底隧道中的应用及其物理性能指标、施工工艺、技术要求等,对同类地下工程防水施工具有一定的借鉴意义.     

Receiver autonomous integrity monitoring availability and fault detection capability comparison between BeiDou and GPS

This paper used the statistical methods of quality control to assess receiver autonomous integrity monitoring （RAIM） availability and fault detection （FD） capability of BeiDou14 （Phase II with 14 satellites）, BeiDou （Phase III with 35 satellites） and GPS （with 31 satellites） for the first time. The three constellations are simulated and their RAIM performances are quantified by the global, Asia-Pacific region and temporal variations respectively. RAIM availability must be determined before RAIM detection. It is proposed that RAIM availability performances from satellites and constellation geometry configuration are evaluated by the number of visible satellites （NVS, NVS 〉 5） and geometric dilution of precision （GDOP, GDOP 〈 6） together. The minimal detectable bias （MDB） and minimal detectable effect （MDE） are considered as a measure of the minimum FD capability of RAIM in the measurement level and navigation position level respectively. The analyses of simulation results testify that the average global RAIM performances for BeiDou are better than that for GPS except global RAIM holes proportion. Moreover, the Asia-Pacific RAIM performances for BeiDou are much better than that for GPS in all indexes. RAIM availability from constellation geometry configuration and RAIM minimum FD capability for BeiDou14 are better than that for GPS in Asia-Pacific region in all cases, but the BeiDou14 RAIM availability from satellites are worse than GPS＇s. The methods and conclusions can be used for RAIM prediction and real-time assessment of all kinds of Global Navigation Satellite Systems （GNSS） constellation.     

Incentives to reduce port inefficiency: a theoretical approach

Over the last decades, the European Union (EU) has devoted a large amount of effort and money to projects aimed at boosting some of its maritime corridors as a modal alternative to road or rail freight transport. However, the overall design of most of these programmes has ex post revealed as very ineffective. This paper suggests that promoting port efficiency might be a more suitable target to increase the modal split of Short Sea Shipping (SSS) than subsidizing firms to transfer cargo from road to sea. But defining ‘port efficiency’ is a complex task and, therefore, granting money directly to port authorities could also generate perverse moral hazard effects, particularly when the improvements are difficult to monitor and many investments are non-refundable. The European Court of Auditors points out that millions of EU public port finance was wasted on empty terminal and other unused infrastructure. The objective of this paper is to design a proper subsidy to promote SSS by encouraging port improvements through a proper system of incentives. As a policy recommendation, in this paper we propose the development of a subsidy per inefficiency-reduction unit.     

基于能效管理的船舶航速系统优化设计

在目前航运业市场低迷、运力过剩的境况下,航运企业愈发重视对燃油成本的控制,对航速节油也有了更多的要求.为此,提出基于能效管理的船舶航速系统优化设计,计算船舶营运的经济航速.并结合航次的航线、航向、航速及每段航线的天气、水文等信息,对船舶营运航速的模型进行不断优化调整,指导船舶航行,为船舶及船岸操作提供决策支持,以达到优化节能的目的.     

有限元分析在客车轻量化设计中的应用

采用HYPERMESH软件建立某大型公路客车的有限元模型,对整车结构使用OPTISTRUCT软件进行有限元分析。依据分析结果,在保证整车结构运行刚度和强度的情况下,对整车结构进行轻量化设计。最后对轻量化结构进行侧翻分析和优化设计,以保证整车上部结构强度的侧翻安全性。     

基于时间硬化模型的路面车辙预估分析

为了对路面结构车辙发展进行定量的预估分析,本文建立了三维路面有限元模型,基于时间硬化的蠕变本构模型对三种典型结构的车辙进行了预估分析。结果表明,基于该模型的预估方法能够有效的模拟车辙发展。