A Novel Approach to Reduce the Environmental Footprint of Maritime Shipping

Maritime shipping is a strategic sector with a strong international vocation and management. The need to define regulations valid for many different countries w...     

润滑机理对汽车发动机性能的影响综述

发动机作为汽车中最为复杂精密的机电一体部件,长时间处于高温、高压、高磨损运行工况,且需要满足长寿命、高效率、低能耗、强动力、低污染等一系列标准指标,而汽车发动机运转时零件间的摩擦以及燃烧等产生的颗粒都会对其性能造成恶劣影响,所以润滑对于发动机性能提升尤为重要。综述当前汽车发动机润滑机理,分析润滑油在使用过程中对发动机动力、油耗和排放的影响,并且在最后设想一种新的润滑机理,以弥补发动机的制造缺陷和颗粒的影响,改善汽车发动机的关键性能。     

结构增强型高强密水铺装材料设计及性能试验研究

增加水泥桥面铺装下层的模量,有利于提升沥青铺装结构的耐久性.现从水泥桥面沥青铺装层路用性能出发,提出了针对结构增强型沥青混合料的设计方法.通过沥青改性与级配优化,开发了适用于水泥桥面铺装下层的结构增强型沥青混合料,并开展了性能试验研究.结果 表明:研发的高强密水沥青混合料可以有效提高路面的抗车辙性、低温抗裂性、水稳定性...     

精轧螺纹吊底平台在大体积高桩墩台中的应用与创新

从工程实际出发,对墩台施工水上作业平台工艺进行对比分析,介绍精轧螺纹吊底平台的工艺特点、原理、流程及操作要点。结合全直桩基墩台结构特点,对桩基与上部结构连接方式的设计进行创新,在钢管桩外侧设置4块扇形钢板,并围焊成环形,与精轧螺纹吊底平台共同形成一种新型组合支承结构,提高吊底和底模的周转率,加快工程进度,确保大体积高桩墩台施工的安全和质量,经济和技术效益明显。可为类似墩台施工、钢管桩与上部结构连接方式设计提供参考。     

战场抢修多目标多分队调度优化研究

基于多目标的战场抢修分队调度优化问题一直以来是装备指挥管理部门关注的问题之一.通过约束转换,确立了采用遗传算法进行多目标优化调度的模型,并详细地说明了遗传操作方法的设计,实例验证了遗传算法在多目标多分队调度问题处理过程中的有效性.     

接触网检测车振动补偿研究

针对接触检测车实际工况,分析了检测车车体振动的动力学特性,建立了基于运动规律的数学模型,论述了训练样本得出检测车拉出值振动补偿函数的原理和方法。     

A logit-based model for measuring the effects of transportation infrastructure on land value

Mutual interactions between transportation and land use have long been debated. Despite progress made in computational technology, the study of these interactions is not adequately developed. The most important aspect of such interactions is given by the changes in land values due to changes in transportation infrastructures. We consider the behavioural features of these interactions along with the constraints on the land and/or zoning restrictions and propose a reliable model for the first time to predict land value changes with respect to changes in transportation facilities and accessibility. The proposed model is a logit-based mathematical programming methodology where the relative price of land is predicted with respect to transportation accessibility, neighbourhood amenities, location premium, availability of land, and zoning regulations. A real-world case study is used to exhibit the applicability of the proposed methodology and demonstrate the efficacy of the algorithms and procedures.     

Adapting without Retreating: Responses to Shoreline Change on an Inlet-Associated Coastal Beach

Coastal barrier systems around the world are experiencing higher rates of flooding and shoreline erosion. Property owners on barriers have made significant financial investments in physical protections that shield their nearby properties from these hazards, constituting a type of adaptation to shoreline change. Factors that contribute to adaptation on Plum Island, a developed beach and dune system on the North Shore of Massachusetts, are investigated here. Plum Island experiences patterns of shoreline change that may be representative of many inlet-associated beaches, encompassing an equivocal and dynamically shifting mix of erosion and accretion. In the face of episodic floods and fleeting erosive events, and driven by a combination of strong northeast storms and cycles of erosion and accretion, the value of the average Plum Island residence increases by 34% for properties on the oceanfront where protection comprises a publicly constructed soft structure. Even in the face of state policies that ostensibly discourage physical protection as a means of adaptation, coastal communities face significant political and financial pressures to maintain existing protective structures or to allow contiguous groups of property owners to build new ones through collective action. These factors mitigate against adapting to shoreline change by retreating from the coast, thereby potentially increasing the adverse effects of coastal hazards.     

喷油器的改进对球型燃烧室柴油机排放的影响

通过减小喷油器针阀、弹簧座和弹簧等运动件的质量 ,达到减小喷油器运动惯量的目的 ;通过减小压力室直径 ,达到减小压力室容积的目的。最后将带有新设计的低惯量小压力室喷油器的柴油机进行排放性能测试 ,结果表明柴油机排放得到了改善 ,从而证实了这种方法的有效性     

A local model for the simulation of two–dimensional spilling breaking waves

A numerical model for the simulation of two dimensional spilling breaking waves is described. It is derived from a previous model which, in turn, takes its underlying ideas from the Cointe and Tulin theory of steady breakers. With respect to the former model, the present one is local, i.e., the inception, extension, and geometry of the breakers are determined through the local shape of the water surface. The model has been implemented in a RANSE code, which was developed for the simulation of ship flows, through a modification in the boundary conditions. This yields a simple and effective way to reproduce the breakers influence on the underlying flow. The resulting code has been used to simulate the flow past a submerged hydrofoil. The numerical results are compared with those of the previous model and with the experimental data obtained by Duncan.