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761.
为了提高机器人的越障能力,设计了一种新型探测车Rabbit,该车装有4个轮爪式车轮.介绍了轮爪式车轮的原理,以及Rabbit样机移动系统和控制系统的设计,并通过实验对其进行了运动性能分析.结果表明:Rabbit可以在各种地形中自如运动,如台阶路面、斜坡路面、多障碍路面和月球模拟土壤中等.Rabbit还可以越过高度为车轮半径1.4倍的台阶,并能越过斜度为40°的斜坡,性能优于普通圆形车轮.该轮爪式探测车适用于行星探测或野外探测. 相似文献
762.
为提高逆向工程中点云、三角网格等数据的索引效率,提出一种R*-树结点自适应聚类分簇算法,采用均匀分布数据作为参考点集,基于间隙统计法及k-均值算法获得使结点相似度之和开始收敛的自然簇数,进而实现R*-树的结点自适应聚类分簇.实验证明,该算法可实现各类复杂几何对象的R*-树结点分簇问题,并能降低R*-树结点分簇的参数依赖性,减少结点重合度,提高R*-树空间数据查询效率. 相似文献
763.
在波音737-300型飞机的维护中,飞机起飞爬升时引气压力低是一个多发的、易重复的故障.从引气和机翼防冰系统的工作原理出发,通过发动机大功率状态下的机翼防冰系统操作测试来快速有效地确定引气系统中的失效部件.多次的验证测试表明,这个方法是易行的、高效的. 相似文献
764.
Song Fu Fengming He Xudong Gu Binbin Ni Zheng Xiang Jiang Liu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(8):2091-2098
As an important loss mechanism of radiation belt electrons, electromagnetic ion cyclotron (EMIC) waves show up as three distinct frequency bands below the hydrogen (H+), helium (He+), and oxygen (O+) ion gyrofrequencies. Compared to O+-band EMIC waves, H+- and He+-band emissions generally occur more frequently and result in more efficient scattering removal of <~5?MeV relativistic electrons. Therefore, knowledge about the occurrence of these two bands is important for understanding the evolution of the relativistic electron population. To evaluate the occurrence pattern and wave properties of H+- and He+-band EMIC waves when they occur concurrently, we investigate 64 events of multi-band EMIC emissions identified from high quality Van Allen Probes wave data. Our quantitative results demonstrate a strong occurrence dependence of the multi-band EMIC emissions on magnetic local time (MLT) and L-shell to mainly concentrate on the dayside region of L?=?~4–6. We also find that the average magnetic field amplitude of H+-band waves is larger than that of He+-band waves only when L?<?4.5 and AE1?<?300?nT, and He+-band emissions are more intense under all other conditions. In contrast to 5 events that have average H+-band amplitude over 2 nT, 19 events exhibit >2 nT He+-band amplitude, indicating that the He+-band waves can be more easily amplified than the H+-band waves under the same circumstances. For simultaneous occurrences of the two EMIC wave bands, their frequencies vary with L-shell and geomagnetic activity: the peak wave frequency of H+-band emissions varies between 0.25 and 0.8 fcp with the average between 0.25 and 0.6 fcp, while that of He+-band emissions varies between 0.03 and 0.23 fcp with the average between 0.05 and 0.15 fcp. These newly observed occurrence features of simultaneous H+- and He+-band EMIC emissions provide improved information to quantify the overall contribution of multi-band EMIC waves to the loss processes of radiation belt electrons. 相似文献
765.
Kyo-Young Song Hyun-Joo Oh Jaewon Choi Inhye Park Changwook Lee Saro Lee 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
The aim of this study was to identify landslide-related factors using only remotely sensed data and to present landslide susceptibility maps using a geographic information system, data-mining models, an artificial neural network (ANN), and an adaptive neuro-fuzzy interface system (ANFIS). Landslide-related factors were identified in Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite imagery. The slope, aspect, and curvature of topographic features were calculated from a digital elevation model that was made using the ASTER imagery. Lineaments, land-cover, and normalized difference vegetative index layers were also extracted from the imagery. Landslide-susceptible areas were analyzed and mapped based on occurrence factors using the ANN and ANFIS. The generalized bell-shaped built-in membership function of the ANFIS was applied to landslide susceptibility mapping. Analytical results were validated using landslide test location data. In the validation results, the ANN model showed 80.42% prediction accuracy and the ANFIS model showed 86.55% prediction accuracy. These results suggest that the ANFIS model has a better performance than does the ANN in predicting landslide susceptibility. 相似文献
766.
This work aims to investigate local stress distribution, damage evolution and failure of notched composite laminates under in-plane loads. An analytic method containing uniformed boundary equations using a complex variable approach is developed to present layer-by-layer stresses around the notch. The uniformed boundary equations established in series together with conformal mapping functions are capable of dealing with irregular boundary issues around the notch and at infinity. Stress results are employed to evaluate the damage initiation and propagation of notched composites by progressive damage analysis(PDA). A user-defined subroutine is developed in the finite element(FE) model based on coupling theories for mixed failure criteria and damage mechanics to efficiently investigate damage evolution as well as failure modes. Carbon/epoxy laminates with a stacking sequence of [45°/0°/ 60°/90°]sare used to investigate surface strains, in-plane load capacity and microstructure of failure zones to provide analytic and FE methods with strong validation. Good agreement is observed between the analytic method, the FE model and experiments in terms of the stress(strain) distributions, damage evaluation and ultimate strength, and the layerby-layer stress components vary according to a combination effect of fiber orientation and loading type, causing diverse failure modes in individuals. 相似文献
767.
航空火力控制技术是将飞机、目标及武器之间所构成的作战态势与攻击瞄准操纵结合在一起,充分发挥人机效能的一种综合技术。本文对航空火控技术的发展进行了深入的分析和探讨,并结合火控系统一线工作的经验,对我国航空火控系统的发展方向提出了看法。 相似文献
768.
769.
770.
大流量航空发动机高空模拟进气压力智能与复合控制技术 总被引:2,自引:0,他引:2
在航空发动机高空模拟过渡态考核试验中,要同时实现进气压力的稳定和快速控制非常困难.针对系统实际工况及被控对象的特点,本项目成功开展了进气压力智能与复合控制技术专项研究,并进行了关键技术总结.实际结果表明,采用该技术后,进气压力控制系统能实现高精度和快速度的高效统一. 相似文献