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871.
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针对空中航线选择优化问题,分析了空中交通流的特点。结合航班在航线上等待点空中盘旋的情况,考虑从求解空中飞行时间最短的角度,建立了航线网络中航班最小费用流问题的数学模型,给出了求解这种最小费用流的算法。通过航线网络的简单算例,求出了最佳航线以及相应航线流量,说明了模型和算法的具体应用。 相似文献
874.
1937至1945年抗战时期的抗战语境对我国的翻译实践产生了很大的影响。本文从赞助人的视角剖析Andre Lefevere的操纵论对抗战时期我国译介活动的影响和操纵,指出赞助人对翻译活动有其推动作用。也分析其对翻译过度操纵的局限性,以及翻译研究不应忽视对翻译本体的认知与把握。 相似文献
875.
Lift on circulation control (CC) circular cylinder is calculated via numerical simulations based on 2D real- izable k-e epsilon viscous model and compared with experimental data. The simulation result shows an acceptable agreement with tested data. With the proved grid and simulation method, series of simulations are conducted to study the effect of parameters on lift. Single slotted tail booms under different clown wash velocities are optimized with the principle of generating maximum total moment around the main rotor shaft with same total power con- sumption. The results show that larger jet flow velocity, or smaller blow angle, or larger diameter of the cross section can help generating larger lift while enhancing the attachment of both the jet flow and down wash flow. Multiple slotted tail boom is better because it increases lift with same total slot width, and can increase lift by in- creasing total slot width without causing separation, also it helps generating high steady lift at a big rank of slot at- tack angles. To mount a guide vane (GV) at the exit of the slot, or shape the upper slot wall like a smooth-GV, or design the slot with an edge fillet is not recommended because it reduces the velocity of both the jet flow and the upstream of the attached downwash flow. Compared with other shapes of the slots, arcs-profiled slot performs better because of larger jet flow velocity and smaller blow angle. In order to generate the largest moment with same total power consumed by the entire NOTARTM system, total width of the slots and slot attack angle should be optimized according to velocity of down wash flow. 相似文献
876.
刘武 《中国民航飞行学院学报》2013,(6):50-53
根据近几年飞行学生ICAO英语OPI测试中反映出的问题,从两个方面反思了基础英语阶段飞行学生英语听说课教学的目标、内容与原则,以及教学实践中的问题与对策。 相似文献
877.
The reliability of global navigation satellite system (GNSS) positioning degrades when satellite signals are interfered. Such degradation is hard to be deteced by a micro-electro mechanical system (MEMS) based inertial system(INS)/GNSS, integrating navigation system with a conventional Kalman filtering, which results in poten- tial integrity problem of the system. Hence, an algorithm combining wireless fidelity (WiFi) signal with a federa- ted Kalman filter (FKF) is proposed to identify the system integrity in dense urban navigation. The criterion of the system integrity detection is created followed by the derivation of the integrity coefficient. The field test shows that integrity changes can be captured by applying WiFi, and the maximum positioning error is reduced by 67~ without compensation of inertial sensors in integrity deterioration. 相似文献
878.
航空公司航班正常率是评价航空服务质量的一个重要指标,提高地面运行效率是提高航班正常率的重要因素之一。分析了zH航空公司地面运行管理中存在的问题,并以波音737快速过站保障流程的优化为例,阐述如何利用网络计划理论对保障流程进行优化,以提高保障效率。 相似文献
879.
To better understand the formation of H2O2 in the ozonation of nitrobenzene and its role for the oxidation,a batch reactor of nitrobenzene ozonation was set up.The variables such as pH value,ozone dosage,and the presence of hydroxyl radical scavenger were investigated.The results showed that high accumulations of H2O2 were generally formed at low pH values and low ozone dosages.Moreover,H2O2 mainly formed after nitrobenzene was oxidized by hydroxyl radical during ozonation of the intermediates,such as p-nitrophenol,which reacted with ozone quickly in water.A small amount of additional H2O2 enhanced the nitrobenzene removal slightly.The kinetic study showed that nitrobenzene degradation fitted with pseudo-second-order kinetics well in the experiment.The kinetic constant values correlated linearly with the concentrations of H2O2 added.Thus,it is expected that the H2O2 formed in oxidation of nitrobenzene may initiate ozone decomposition to form hydroxyl radical and finally enhance the degradation of aromatic compounds to a certain extent. 相似文献
880.
针对典型的镍基高温合金材料GH4169开展珩磨试验,研究了主轴转速、往复速度、每往复进给量、油石粒径对材料去除率的影响规律。结果表明:主轴转速对材料去除率影响较小,其余三因素均对材料去除率有显著影响,其中每往复进给量和油石粒径的影响最为显著,且材料去除率与三者均呈现正相关关系。进行多元线性回归拟合出经验公式。同时还发现,适当提高网纹交叉角可以提高珩磨材料去除率。对加工余量一定且粗糙度要较高的内孔珩磨进行了工艺优化,实现了更高的加工效率。 相似文献