Measuring the environmental efficiency of the global aviation fleet

This research analyses the environmental footprint of the airline industry in an attempt to highlight potential paths for improvement. We develop a directional economic-environmental distance function (DEED) which accounts for the production of both desirable and undesirable output and the potential for constrained increases in input utilization. This research applies the modeling framework to analyze the potential to reduce noise and airborne pollutants emitted by aircraft–engine combinations given the current state of aeronautical technology. The global aircraft–engine market is viewed from the regulatory perspective in order to compare the single environmental and operational efficient frontier to that of the airline carriers, and environmental objectives. The results of DEED are then applied in order to substitute the fleets serving Schipol, Amsterdam and Arlanda, Stockholm airports in June 2010 with the benchmark aircraft. The results highlight the inefficiencies of the current airline fleets and that the IPCC values of externalities are a magnitude of TEN too low to encourage changes in the global fleet hence the need for government intervention.     

基于OFDM的移动蜂窝系统中分布式带宽借复用机制

为了提高未来基于OFDM的移动蜂窝系统的频谱效率,尤其在小区/扇区间流量不均匀的情况下,本文基于两种传统的扇区结构(菱形扇区和五边形扇区)提出一种分布式带宽借复用DBBR(Distributed Bandwidth Borrowing and Reusing)算法。算法利用离基站较近的用户有着较好信道条件的特点,那些带宽不够的扇区以无功率控制的方式借复用相邻扇区中空闲的带宽和离基站较近的用户所使用的带宽,以此提高扇区的吞吐量。理论分析和仿真结果表明相对于传统的三扇区结构,该算法使扇区的平均吞吐量有20%左右的提升,同时说明加入功率控制也不会带来系统吞吐量更多的改善。     

Analysis of the operational energy efficiency for inland river ships

This paper looks at the energy consumption and green house gas emissions of inland river shipping, and compares them with the performance of seagoing ships. The analysis is based on a case study of container shipping on the Yangtze River, China. Data were collected under both calm water and real navigation conditions, and energy efficiency operation indices under these conditions are calculated and analyzed. We find that the navigation environment can influence significantly the operational energy efficiency of inland river ships.     

基于数据包络分析的高速公路指路标志地名数研究

随着路网的复杂化，指路标志信息量过载导致交通事故发生的现象日益显著。为了全面、系统地确定高速公路互通区指路标志的合理地名数，为高速公路指路标志的设置提供相应的改进建议，基于数据包络分析（DEA）方法，从驾驶人角度选取了反映其对指路标志认知反应水平的代表性指标，构建了高速公路互通区指路标志地名数研究的宏观模型。使用眼动仪和脑电仪在相关场景中进行室内驾驶模拟试验，以获取被试在不同地名数指路标志场景下的眼动行为、脑电以及驾驶行为数据。利用模型进行数据分析，得到驾驶人在地名数为4，5，6，7，8，9六种场景下，对指路标志认知反应的综合效率均值分别为0.983，0.956，0.902，0.796，0.699和0.617，再针对不同的指标集，进行指标敏感性分析，获取驾驶人在6种场景下的综合效率指数。通过试验发现：随着地名数的增多，驾驶人对指路标志认知反应的综合效率均值呈现下降趋势，当信息量超过其认知阈值时，系统综合效率值会迅速下降；不同地名数指路标志场景下，导致驾驶人认知反应效率低的原因存在差异，在对指路标志版面设计时应有针对性地予以改进；不同驾驶人对指路标志认知反应效率存在差异，所对应的标志地名数合理阈值也存在轻微差异，但总体上从驾驶人认知反应的角度考虑，高速公路指路标志的地名数阈值为6个。该研究从驾驶人对指路标志认知反应的角度，使用DEA方法构建了全面、系统的指标体系对指路标志的地名数进行了探析，为中国高速公路互通区指路标志的版面设置提供了参考。     

机车车辆通风用新型空气过滤器的研制

对机车车辆通风用的传统空气过滤器存在的问题进行分析,介绍一种适合机车车辆通风用新型空气过滤器的结构特点、过滤机理、主要性能及试验情况等。     

Theory and experimental research on six-track steering vehicles

The structural characteristics and steering behaviour of a six-track vehicle are described in this paper. Kinematic analysis for skid steering of a six-track vehicle under steady-state conditions on firm ground is conducted, with the relationship between thrust force and speed instantaneous centre of the track–terrain interface taken into consideration. A mechanical model for steady steering of a six-track vehicle is also presented based on the kinematic analysis. In this model, the steering inaccuracy and efficiency are defined to evaluate steering performance. The steering performance of a six-track vehicle is numerically simulated to analyse the effect of the structural parameters and deflection angles on tracks. A virtual prototype model is established based on the multi-body dynamics software RecurDyn for steering simulation and the findings coincide well with theoretical results. The theory and the virtual prototype simulations presented are verified by a power test of a bucket-wheel excavator. The method for analysing the steering performance of a six-track vehicle proposed in this paper provides a basis for designing a six-track vehicle.     

基于同块同压原则的盾构推拼同步技术模型试验研究

为解决长距离隧道单台盾构掘进施工工期过长问题，以上海市域铁路机场联络线3标盾构区间为示范应用工程，在不改变盾构驾驶人员操作习惯的前提下，研发一种对盾构推进油缸压力进行闭环主动控制的推拼同步施工技术，以维持推进系统稳定的总顶推力矢量。同时，给出基于同块同压原则缺失顶力的再分配计算方法，并通过构建相似比为1/2的大型试验平台对成套技术进行试验验证。试验结果表明： 原型盾构推进系统总顶推力误差控制为±4%； 盾构姿态水平和垂直偏差控制为±12 mm； 盾构推进速度控制为设定速度的（-6，+6） mm/min； 管片结构抗压安全系数达2.13。     

Heavy-duty trucking and the energy efficiency paradox: Evidence from focus groups and interviews

Theory suggests that profit maximizing firms have an incentive to incorporate cost-effective technologies into their products. However, simple net present value calculations comparing upfront costs of fuel-saving technologies to future savings suggest this is not always the case. This puzzle is commonly referred to as the “energy efficiency paradox.” A growing number of empirical studies examine why households may under-invest in energy efficiency. Fewer studies examine similar undervaluation by businesses. We explore investment decisions within the heavy-duty trucking sector for fuel-saving technologies via focus groups and interviews to gain insight into what factors might explain apparent underinvestment in fuel-saving technologies. We find some evidence that market failures related to lack of information about technology performance and network externalities contribute to slow adoption of some technologies. However, information about new technologies for tractors seems to generate limited spillovers. There is also some evidence of split incentives between owners and drivers, though companies have invested in a variety of technologies and approaches in an attempt to address these effects. Other factors important in trucking investment decisions that are not classic market failures include tradeoffs between fuel economy and other valued truck attributes, as well as uncertainty and risk associated with new technologies if decision-makers are loss averse.     

桥面融雪除冰能量桩热泵系统换热效率现场试验

基于能量桩的桥面工程主动式融雪除冰技术作为一种新型桥面融雪除冰技术，具有环保、节能等技术优势。依托江阴市征存路观风桥市政桥梁工程，开展能量桩供热桥面板的换热效率与热-力响应特性现场试验。在桩基础和桥面板中分别预埋聚乙烯管作为换热管，通过水泵驱动换热管中的流体循环，提取浅层地温能供热桥面板；沿桩身深度方向和在桥面板中布设了温度-应变传感器，用于监测试验过程中相应位置的温度和应变。试验分析冬季工况下，一根20 m的能量桩供热20 m²的桥面板时，流体、桥面板、桩的温度变化以及桥面板和能量桩的热致应力分布。研究结果表明：根据现场试验条件，环境温度为-4℃时，20 m能量桩供热20 m²桥面板可保证桥面板表面温度始终高于0℃，即平均每延米能量桩热泵系统可保障1 m²桥面板不冻结；温度的改变使得能量桩和桥面板中产生热致应力，桩身最大轴向热致应力出现在桩深10 m （50%桩长）处，约为-1.05 MPa，为混凝土抗拉强度（2.0 MPa）的52.2%，桩身最大轴向热致应力的温度响应约为0.205 MPa·℃^-1；桥面板中最大热致应力为0.77 MPa，为混凝土抗压强度（26.8 MPa）的2.9%，热致应力的温度响应为0.086 MPa·℃^-1；能量桩上部受到最大正摩阻力为21.1 kPa，下部受到最大负摩阻力为13.3 kPa；试验结束时桩顶热致位移为-0.239 mm，约0.03%桩径。     

考虑能源类型的城市出租车运营效率评价研究

以分析西安市燃气型、电动型及甲醇型3种能源类型出租车在运营中的既有期望运营投入和非期望运营投入，既有期望产出和非期望产出为基础，本文构建基于DEA-Malmquist的考虑能源类型的出租车运营效率评价模型。从西安市出租车管理处提取西安市 2020 年 9~12 月期间 14946辆出租车的GPS轨迹数据，并随机选取1000辆甲醇型出租车、1000 辆电动型出租车及 1000辆燃气型出租车作为样本进行实例分析。通过处理3000辆出租车GPS数据，得到乘客在工作日和双休日不同时段的出行需求和特征，分析3种不同能源类型出租车的运营效率差异。所得结论可为西安政府部门对不同能源类型出租车的管理运营提供决策支持。