A bi-objective dynamic programming approach for airline green fleet planning

Ensuring a fleet of green aircraft is a basic step in mitigating aviation pollution issues that are expected to be worsen in the coming years due to rapid air traffic growth. This study proposed a novel methodology in green fleet planning in which both profit and green performance of airline are considered simultaneously and explicitly. To do this, a Green Fleet Index (GFI) is derived as an indicator to quantify the green performance of airline’s fleet. It measures the degree of airline compliance with a standard requirement in terms of emission, noise, and fuel consumption. A bi-objective dynamic programming model is then formulated to find optimal aircraft acquisition (lease or purchase) decision by minimizing GFI and maximizing profit. Several interesting results are obtained: (1) considering environmental issue as secondary objective yields a greener fleet; (2) airline’s profit is affected, but could be recovered from environmental cost savings; (3) increasing load factor is an effective operational improvement strategy to enhance airline’s green performance and raise profit level. It is anticipated that the framework developed in this study could assist airlines to make a smart decision when considering the need to be green.     

Comparing rail fuel efficiency with truck and waterway

This paper presents a railroad energy efficiency model used to estimate the fuel economies for classes of trains transporting various commodities. Comparable procedures are used to estimate truck and waterway fuel consumption. The results show that coal unit trains are 4.5–5.0 times more energy efficient than movements in the largest trucks allowed in the eastern and western regions of the US, unit grain train movements in the central US are 4.6 times more fuel efficient, soda ash unit train and non-unit train shipments are 4.9 and 3.2 times more efficient, and ethanol unit train and non-unit train movements are 4.8 and 3.0 times more efficient. In terms of barge traffic, coal unit train and non-unit train are 1.3 and 0.9 times as energy efficient in the eastern US, grain unit train and non-unit train movements are 1.7 and 1.0 times more efficient from Minneapolis to the Gulf of Mexico, and grain unit train and non-unit train movements are 1.0 and 0.7 times more fuel efficient from the Upper Ohio River to the Gulf of Mexico.     

温度对旋转钻进破岩功耗的影响研究

岩石在常温、常压下的变形破坏理论已非常成熟，但随着钻探深度不断的增加，岩石将要面临高地温、高围压的环境，这些因素将直接影响钻进过程。通过研究旋转钻进过程中能量的传递转移，建立岩石破碎的简化模型，利用单位体积破岩能耗来探究温度对钻进过程的影响。研究结果表明:随着钻进深度的增加，在一定的围压作用下，温度升高而岩石的弹性模量却逐渐减小，压入深度随温度升高呈抛物线形上升，破岩功耗随温度呈曲线上升，并在经过阀值温度400℃后趋于平缓。     

Combustion development of a Bi-Fuel engine

Environmental improvement and energy issues are increasingly becoming more important as worldwide concerns. Natural gas is a good alternative fuel that can help to improve these issues because of its large quantity and clean burning characteristics. This paper provides the experimental performance results of a Bi-Fuel engine that uses Compressed Natural Gas as its Primary fuel and gasoline as its secondary fuel. This engine is a modification of the basic 1.4-liter gasoline engine. Generally, on the unmodified base engine, torque and power for CNG fuel are considerably lower than gasoline fuel. In this paper, the influence of fuels on wall temperature, performance and emissions are investigated.     

工艺中的泄漏检测对产品质量控制的重要性

文章阐明了密封性测试在批量生产方式的汽车制造业中的重要性,介绍了广泛使用的压力法和流量法泄漏检测的基本原理,着重通过实例说明了根据不同检漏方法开发的泄漏测试设备的特点及其在生产中的适用性,并据此对企业在密封工序工艺规划中的设备选择原则进行了分析。通过对用于燃油系统中的脱附试验装置的介绍,进一步表明了基于合理方案研制的专用密封性检测设备能为产品质量提供可靠的保证。     

小型液压挖掘机回转过程能量消耗与节能研究

为了使小型液压挖掘机在回转过程中降低能量消耗,对小型液压挖掘机在重载工况下以不同转动惯量回转时的能量消耗特性进行分析,利用Pro/E软件建立了整机的三维模型,利用AME-sim软件建立了液压系统仿真模型,通过ADAMS和AMEsim软件对模型进行联合仿真,并进行试验研究,得到小型液压挖掘机在回转过程中由转动惯量变化引起的能量消耗和系统压力变化的规律。结果表明:在重载工况下以小转动惯量回转时,采用柴油机停缸技术,可以使平均燃油消耗下降15%。     

智能网联技术应用于混合动力汽车探析

文章简要介绍了混合动力汽车和智能网联技术的研究现状,阐明了混合动力汽车与智能网联技术相结合的意义。着重论述了在智能网联环境下混合动力汽车进行能量管理的优势以及混合动力汽车实现智能网联的技术要求,最后对未来二者的依托发展进行了展望。     

The Pollution-Routing Problem

The amount of pollution emitted by a vehicle depends on its load and speed, among other factors. This paper presents the Pollution-Routing Problem (PRP), an extension of the classical Vehicle Routing Problem (VRP) with a broader and more comprehensive objective function that accounts not just for the travel distance, but also for the amount of greenhouse emissions, fuel, travel times and their costs. Mathematical models are described for the PRP with or without time windows and computational experiments are performed on realistic instances. The paper sheds light on the tradeoffs between various parameters such as vehicle load, speed and total cost, and offers insight on economies of ‘environmental-friendly’ vehicle routing. The results suggest that, contrary to the VRP, the PRP is significantly more difficult to solve to optimality but has the potential of yielding savings in total cost.     

江城居民茶叶消费心理与行为调查分析

本文采用问卷调查的方式,对武汉居民在茶叶购买动机、购买行为和购后的满意度等方面进行了分析,总结了江城茶叶市场的消费特点和消费趋势,为茶叶生产经营者提供参考。     

RT-flex主机的应用及特殊电气故障的排除

主机试验是船舶系泊试验中最重要的试验之一,在实验及调试过程中出现的问题也很特殊,解决并处理好这些问题对于船舶的系泊及航行试验的顺利进行起着至关重要的作用.总结了RT-flex电喷系列主机在试验现场发现的电气问题及解决的方案,供技术人员参考.