排序方式: 共有78条查询结果,搜索用时 46 毫秒
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作战实验是军事研究的一种重要手段,是军事科技向作战能力转化的桥梁和催化器,对军事理论与实践的发展有着重要的作用。随着信息技术、网络技术和计算机技术的发展和国情军情的现实需要,我军实施联合火力打击作战实验既有充分的必要性也有现实的需求性。论以此为背景对我军实施联合火力打击作战实验的必要性、分类和实验流程进行了论述。 相似文献
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《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(12):1876-1901
Vehicle–track interaction at railway crossings is complex due to the discontinuity of the crossings. In this study, the effect of the local crossing geometry, the track alignment, and the wheel profiles on the wheel transition behaviour is investigated using the multi-body system software package VI-Rail. The transition behaviour is evaluated based on the location of the transition point along the crossing (and the location of impact), the contact pressure and the energy dissipation during the wheel–rail contact. A detailed parametric study of the crossing geometry has been performed, through which the most effective parameters for defining the crossing geometry are identified. These parameters are the cross-sectional shape of the nose rail, which can be tuned by one variable, and the vertical distance between the top of the wing rail and the nose rail. Additionally, a parametric study on the interaction influence of the crossing geometry, the track alignment and the wheel profile is performed using the design of experiments method with a two-level full factorial design. The longitudinal height profile of the crossing and the wheel profile are the most significant factors. 相似文献
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《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(9):807-817
The present study proposes an objective handling qualities evaluation method using driver-in-the-loop analysis. The driving simulator experiments were performed for various driving conditions, drivers and vehicle dynamics. The response characteristics of the driver model and the closed-loop system were analyzed. The analysis revealed the driving strategies clearly, indicating the importance of closed-loop analysis. Using the identified driver model and its strategies, a cost function of the handling qualities was constructed. The cost function can be used to estimate the handling qualities analytically from the vehicle dynamics. The proposed method was validated by comparison with the handling qualities evaluation rated by the driver's comments. 相似文献
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Several industry leaders and governmental agencies are currently investigating the use of Unmanned Aerial Vehicles (UAVs), or ‘drones’ as commonly known, for an ever-growing number of applications from blue light services to parcel delivery. For the specific case of the delivery sector, drones can alleviate road space usage and also lead to reductions in CO2 and air pollution emissions, compared to traditional diesel-powered vehicles. However, due to their unconventional acoustic characteristics and operational manoeuvres, it is uncertain how communities will respond to drone operations. Noise has been suggested as a major barrier to public acceptance of drone operations in urban areas. In this paper, a series of audio-visual scenarios were created to investigate the effects of drone noise on the reported loudness, annoyance and pleasantness of seven different types of urban soundscapes. In soundscapes highly impacted by road traffic noise, the presence of drone noise lead to small changes in the perceived loudness, annoyance and pleasantness. In soundscapes with reduced road traffic noise, the participants reported a significantly higher perceived loudness and annoyance and a lower pleasantness with the presence of the same drone noise. For instance, the reported annoyance increased from 2.3 ± 0.8 (without drone noise) to 6.8 ± 0.3 (with drone noise), in an 11-point scale (0-not at all, 10-extremely). Based on these results, the concentration of drone operations along flight paths through busy roads might aid in the mitigation of the overall community noise impact caused by drones. 相似文献
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对捷达电喷发动机在外特性和4 000r/min负荷特性下燃用93#汽油、乙醇汽油(E10,E20)、甲醇汽油(M15,M30)和液化石油气(LPG)时的排放性能进行了试验研究,主要测试了CO,HC和NOx3种常规污染物.试验结果表明:发动机燃用M30可降低显著降低NOx和HC的排放质量浓度;发动机燃用LPG时,CO的排放质量浓度明显低于其他燃料. 相似文献
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李曼林 《大连铁道学院学报》2010,(1):49-52
采用MPX-2000盘销式摩擦磨损试验机,对调质处理、高频淬火处理、软氮化处理、硬氮化处理、激光淬火处理5种滑动摩擦副表面强化工艺措施进行了表面抗咬合性能和表面耐磨损性能对比试验.试验研究结果表明,激光淬火处理和软氮化处理工艺对滑动摩擦副表面强化效果好与较好,可用于高速重载且重要的零部件表面强化.硬氮化处理工艺表面强化效果中等,可用于中等载荷条件下零件表面强化.调质处理工艺对滑动摩擦副表面强化效果较差,可用于载荷较小的非重要零部件表面强化.高频淬火处理工艺试件的抗咬合能力差,不宜采用. 相似文献
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