Finite-difference simulation of green water impact on fixed and moving bodies

A numerical method was developed to predict the water impact pressure caused by green water phenomena. The density function method was employed in the framework of a locally refined overlapping grid system. The simple problem of a rectangular body placed in regular waves was considered and the simulation results were compared with tank experiments. Good agreement with experiment was shown for wave–body interactions and for the pressure values at three different positions on the body. The case of a rectangular body with a vertical wall on the deck was also considered and the comparison showed satisfactory agreement. It was demonstrated that this method could be extended to a moving body problem, in which the body was free to undergo heave, pitch, and surge motions.     

单相交流牵引供电系统关键技术现状及发展

介绍各国主要单相交流牵引供电制式,总结各国为了解决制约单相交流牵引供电系统发展的电分相问题所采取的多种过分相方式,为了解决电能质量问题所采取的各有侧重点的治理措施,对比国内外同相供电技术并指出国外技术中值得我国借鉴之处,最后基于已有关键技术并结合储能和新能源等背景描绘了"绿色"牵引供电系统,为单相交流牵引供电系统的发展提供新思路。     

交叉口单点公共汽车交通优先控制方法研究

开发ITS背景下的公共汽车交通优先控制方法是从根本上改善公交车辆运行情况的需要。满足车辆固有的行驶时刻表是实施公交优先通行申请的重要依据,在本文控制策略中运用绿灯时间延长和相位提前激活两种方法,在兼顾其它车辆运行情况的前提下,给予晚点公交车优先的通行信号。论文最后以厦门市湖滨南路实际交通流量为依托,运用交通仿真方法验证了优先控制策略的实际效果。     

Field tests of a dynamic green driving strategy based on inter-vehicle communication

This paper presents the design and results for field tests regarding the environmental benefits in stop-and-go traffic of an algorithmic green driving strategy based on inter-vehicle communication (IVC), which was proposed in Yang and Jin (2014). The green driving strategy dynamically calculates advisory speed limits for vehicles equipped with IVC devices so as to smooth their speed profiles and reduce their emissions and fuel consumption. For the field tests, we develop a smartphone-based IVC system, in which vehicles’ speeds and locations are collected by GPS and accelerometer sensors embedded in smartphones, and communications among vehicles are enabled by specially designed smartphone applications, a central server, and 4G cellular networks. Six field tests are carried out on an uninterrupted ring road under slow or fast stop-and-go traffic conditions. We compare the performances of three alternatives: no green driving, heuristic green driving, and the IVC-based algorithmic green driving. Results show that heuristic green driving has better smoothing and environmental effects than no green driving, but the IVC-based algorithmic green driving outperforms both. In the future, we are interested in field tests under more realistic traffic conditions.     

Green walking networks for climate change adaptation

Climate change (CC) potentially affects people travel behaviour, due to extreme weather conditions. This is particularly true for pedestrians, that are more exposed to weather conditions. Introducing the effect of this change in transport modelling allows to analyse and plan walking networks taking into consideration the climatic variable. The aim of this work is to develop a tool that can support planning and design of walking networks, by assessing the effects of actions oriented to increase resilience with respect to extreme weather conditions (CC adaptation).An integrated approach is used, thus combining transport and land-use planning concepts with elements of outdoor thermal comfort and network accessibility. Walking networks are analysed through centrality indexes, including thermal comfort aspects into a general cost function of links and weighted nodes. The method has been applied to the walking network inside the Campus of the University of Catania (Italy), which includes different functions and where pedestrian paths are barely used by people. Results confirm that this tool is sensitive to the variables representing weather conditions and it can measure the influence of CC adaptation measures (e.g. vegetation) on walking attitude and on the performance of the walking network.     

A carbon footprint-based closed-loop supply chain model under uncertainty with risk analysis: A case study

The management of products’ end-of-life and the recovery of used products has gained significant importance in recent years. In this paper, we address the carbon footprint-based problem that arises in a closed-loop supply chain where returned products are collected from customers. These returned products can either be disposed of or be remanufactured to be resold as new ones. Given this environment, an optimization model for a closed-loop supply chain (CLSC) in which carbon emission is expressed in terms of environmental constraints, i.e., carbon emission constraints, is developed. These constraints aim to limit the carbon emission per unit of product supplied with different transportation modes. Here, we design a closed-loop network where capacity limits, single-item management and uncertainty on product demands and returns are considered. First, fuzzy mathematical programming is introduced for uncertain modeling. Then, the statistical approach to the possibility to synthesize fuzzy information is utilized. Therefore, using a defined possibilistic mean and variance, we transform the proposed fuzzy mathematical model into a crisp form to facilitate efficient computation and analysis. Finally, the risk caused by violating the estimated resource constraints is analyzed so that decision makers (DMs) can trade off between the expected cost savings and the expected risk. We utilize data from a company located in Iran.     

Challenges and Benefits in the Design of Coastal Walking and Cycling Amenities: Toward a More Integrated Coastal Management Approach

The planning and development of pedestrian and cycling amenities in coastal urban environments is a challenging process because a wide range of policies and considerations must be taken into account. Among these, the concepts of sustainability and more recently, resilience, have been gaining prominence. Green Infrastructure design approaches can integrate aspects of both sustainability and resilience, providing multiple services within single development projects. This study focuses on Dublin and examines a range of amenity projects at various stages of development that relate to the provision of new coastal walking and/or cycle routes. These are initially contextualized at the city level before focusing specifically on challenges and benefits associated with the design and implementation of such projects. Based on our findings, recommendations are made for optimizing the potential of future projects to effectively integrate with other initiatives so as to deliver broader policy objectives. A simple sequential model is presented that should assist developers and decision-makers to take a more integrated, multidisciplinary approach to meeting policy goals when planning and developing coastal amenities. Finally, this is remodeled into a set of considerations that are generally applicable to coastal development proposals of significant scale.     

斜壁结构的水动力收敛方法研究

在分析波浪中的船舶运动或者计算大型结构的水动力系数时,往往采用时域格林函数方法。时域格林函数的一个重要局限性在于它在计算具有倾斜壁面的水动力系数时,结果很容易发散。时域格林函数本身的奇异性以及高频振动特性显然是水动力发散的一个重要原因。但即使该奇异性通过增加粘性以及表面张力的方式使之消失,计算具有斜壁结构的水动力时,发散现象依然存在。因此,该文提出一种滤波方法,除去时域格林函数的高频部分,留下其低频部分,并定义滤波系数,从而使作用于斜壁结构上的水动力值收敛。通过文中结果与频域兴波格林函数法的比较来确定最优滤波系数。结果表明：最优滤波系数几乎与运动幅值无关,但会受到运动频率以及物面形状的影响。     

城市绿色交通建设与发展策略综述

绿色交通系统对改善城市交通拥堵,减少交通能耗、环境污染,提高城市的宜居性等方面有着积极的推动作用。文章从城市规划和土地利用开发、交通需求管理、交通基础设施建设等方面阐述了城市绿色交通的建设与发展策略,为发展、建设城市绿色交通提供思路。     

Evaluating the effects of green port policy: Case study of Kaohsiung harbor in Taiwan

The paper evaluates the effectiveness of strategies designed to reduce these pollutants in port areas, based on a newly developed assessment model to calculate emissions. The case study found that the strategy of reducing the ship’s speed to 12 knots is most effective in cutting fuel consumption and costs, as well as emissions. Adopting an onshore power supply system could reduce CO₂ emission by 57.16% and PM by 39.4%. By adopting the strategies of both reduced speed and cold ironing emissions control, a reduction in emissions of 71% to 91% can be achieved with a 20 nautical mile reduced speed zone. Therefore, the goals of reductions in emissions to improve port areas air quality could be achieved through adopting a green port policy in the future.