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271.
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ABSTRACTThe transportation sector is the greatest contributor to air pollution. With the booming demand for transportation, reducing the pollution has become one of the main concerns of researchers. EPA emission standards are designed to protect air quality and human health. Diesel Euro 5 NOx has become a matter of disquiet since it has been found that NOx emissions are significantly exceeding the standard limit. This paper presents a study to estimate the disparity in real-world NOx emission levels resulted from all diesel Euro 5 passenger cars (PC) and light commercial vehicles (LCV) that are present in Ireland. NOx emission levels calculated based on laboratory test results, on-road measurements and the COPERT 4 model were compared. Additionally, NOx emission levels from the defective Volkswagen models have been calculated to quantify the effect of the Volkswagen scandal on Ireland. Impacts of excess NOx emissions on health and cost have also been presented. 相似文献
273.
The lack of a proper integration of strategic Air Traffic Management decision support tools with tactical Air Traffic Control interventions usually generates a negative impact on the Reference Business Trajectory adherence, and in consequence affects the potential of the Trajectory-Based Operations framework. In this paper, a new mechanism relaying on Reference Business Trajectories as a source of data to reduce the amount of Air Traffic Controller interventions at the tactical level while preserving Air Traffic Flow Management planned operations is presented. Artificial Intelligence can enable Constraint Programming as it is a powerful paradigm for solving complex, combinatorial search problems. The proposed methodology takes advantage of Constraint Programming and fosters adherence of Airspace User’s trajectory preferences by identifying tight interdependencies between trajectories and introducing a new mechanism to improve the aircraft separation at concurrence events considering time uncertainty. The underlying philosophy is to capitalize present degrees of freedom between layered Air Traffic Management planning tools, when sequencing departures at the airports by considering the benefits of small time stamp changes in the assigned Calculated Take-Off Time departures and to enhance Trajectory-Based Operations concepts. 相似文献
274.
In this paper, we consider a coordinated multi-aircraft 4D (3D space plus time) trajectories planning problem which is illustrated by planning 4D trajectories for aircraft traversing an Air Traffic Control (ATC) sector. The planned 4D trajectories need to specify each aircraft’s position at any time, ensuring conflict-free and reducing fuel and delay costs, with possible aircraft maneuvers such as speed adjustment and flight level change. Different from most existing literature, the impact of buffer safety distance is also under consideration, and conflict-free is guaranteed at any given time (not only at discrete time instances). The problem is formulated as a pure-strategy game with aircraft as players and all possible 4D trajectories as strategies. An efficient maximum improvement distributed algorithm is developed to find equilibrium at which every aircraft cannot unilaterally improve further, without enumerating all possible 4D trajectories in advance. Proof of existence of the equilibrium and convergence of the algorithm are given. A case study based on real air traffic data shows that the algorithm is able to solve 4D trajectories for online application with estimated 16.7% reduction in monetary costs, and allocate abundant buffer safety distance at minimum separation point. Scalability of the algorithm is verified by computational experiments. 相似文献
275.
用第一性原理研究了RCrO4(R=Er和Tm)氧化物的电子能带结构和半金属铁磁性,发现锆石相的RCrO4是优质的半金属铁磁材料,具有达到0.35eV的半金属能隙。为了研究磁相互作用的机制,采用密度泛函理论和广义梯度近似计算电子能带结构、态密度和自发磁矩,发现其磁性来源于R的f轨道电子、Cr的d轨道电子和O的p轨道电子的自旋极化。穿过费米能级的能带主要来源于R(4f)-O(2p)-Cr(3d)的杂化能级,并对磁性和电子输运性质起着关键作用。 相似文献
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用硫酸钠添加剂的方法改善低活性粉煤灰,可以提高二灰碎石的早期强度、减少裂缝、缩短施工周期,并保证施工质量。但添加硫酸钠以后二灰碎石强度的成因和机理尚有许多未知因素,需有待于进一步研究。 相似文献
279.
研制了一种新颖的应用于网络遥操作机器人系统的网络视频流传输系统,该系统基于C/S模型并采用MPEG4视频编码器对图像进行编解码,实现了机器人现场视频的实时采集、编码、传输和播放。此外,对网络遥操作机器人系统的视频、音频和力信息的传输同步问题展开了研究。实验证明所研制的系统不仅能保证机器人现场图像传输的实时性,而且能较好地实现多信息的同步。 相似文献
280.
船舶电力系统中交流配电网零线故障的诊断 总被引:1,自引:0,他引:1
戴雅丽 《武汉船舶职业技术学院学报》2009,8(5):31-33
船舶电力系统中采用的三相四线制交流配电网中零线故障时有发生,为了保证船舶电力系统的供电连续性及最大可能地缩短船舶停电时间,本文结合一起零线故障的实际情况,运用电路理论分析了零线故障产生的机理及其危害性,指出三相四线制交流配电网零线接地的重要性,并提出了防止此类事故的基本措施和具体方法。 相似文献