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151.
This paper introduces a combustion model of heat transfer and fuel consumption for the propagation of a fire front on a point cloud surface. The heat transfer includes the heat advection by the airflow as well as diffusion, chemical reaction, and heat loss to generate complex, but controllable heat flows with a designed airflow velocity. For the stable heat advection, we solve a semi‐Lagrangian method on point samples using discrete exponential maps to trace the position from which the wind blows while preserving the geodesic distance. We also propose angular Voronoi weights for a discrete Laplace‐Beltrami operator that shows better isotropic diffusion on the inhomogeneous distribution of point clouds than the cotangent or moving least‐squares schemes. We demonstrate a diversity of burning scenarios by incorporating factors affecting the fire spreading such as buoyancy and object geometries in the airflow velocity fields, or by synthesizing patterns. 相似文献
152.
Takuya Otani Kenji Hashimoto Takaya Isomichi Akira Natsuhara Masanori Sakaguchi Yasuo Kawakami 《Advanced Robotics》2013,27(22):1197-1206
In previous studies, various stabilizing control methods for humanoids during the stance phase while hopping and running were proposed. Although these methods contribute to stability while hopping and running, it is possibility that the control during the flight phase could also affect the stability. In this study, we investigated whether the control during the flight phase can affect the stability of a humanoid while running. To achieve stable hopping, we developed a control system that accounts for the angular momentum of the whole body during the flight phase. In this system, the angular momentum generated by the motion of the lower body in each time interval is calculated during the flight phase, and the trunk joints are controlled to generate the angular momentum necessary to compensate for the deviation of the waist posture, which is used as the reference point for the motion coordinate system of the robot. Once the proposed control system was developed and simulated, we found that the hopping duration in the unconstrained state was extended. 相似文献
153.
改进的自适应神经模糊推理系统的角度传感器误差补偿方法 总被引:1,自引:0,他引:1
角度传感器测量精度控制在工程应用中非常重要, 直接影响其实际应用的效果. 当被测物理量和角度传感器输出之间为复杂非线性关系时, 传统方法已难以获得满意的结果. 本文引入了一种基于改进的自适应神经模糊推理系统的误差补偿方法, 阐述了模型建立过程与步骤, 并对一个16位绝对式光电编码器进行了精度检测与误差补偿. 实验结果证明, 与多项式拟合法和BP神经网络相比, 改进的自适应神经模糊推理系统可显著提高光电编码器的测量精度; 相比于补偿前, 补偿后光电编码器测量精度可至少提高7.5倍. 相似文献
154.
Sandip Ghosh Chowdhury Amit Mondal Jen Gubicza Gyrgy Krllics rpd Fodor 《Materials Science and Engineering: A》2008,490(1-2):335-342
The evolution of microstructure and texture in Al6082 precipitation-hardened alloy during equal-channel angular pressing (ECAP) was studied. It was found that although the dislocation density and the subgrain size saturated after 1 pass, the size of grains bounded by high angle boundaries reached its minimum value only after 4 passes. Furthermore, the grain orientation distribution changes between 4 and 8 passes, indicating the development of grain boundary structure even after the saturation of the parameters of the microstructure. As a result of this evolution, the initial texture of the commercial alloy was diminished after 8 passes and the grain orientation distribution became to be close to random case. 相似文献
155.
基于无传感器信息,结合先进的数据处理技术和特征提取方法对数控机床导轨水平倾角进行测量,实现导轨水平倾角的无传感器测量。与传统的测量装置相比,无传感器信号信噪比更高,不仅能在空载下测量,还可以在机床加工过程中测量。 相似文献
156.
In order to utilize the advantage of low density and overcome the disadvantages of poor corrosion resistance and low strength, the laminated composites of Mg alloys fabricated by different methods have attracted extensively attentions. In this paper, the equal channel angular extrusion (ECAE), which has been widely used to fabricate ultrafine grain bulk materials, was introduced to fabricate the Mg–3Al–1Zn/Al (AZ31/Al) laminated composites at different temperatures. After fabrication and annealing treatment at different temperatures, the microstructural evolution and phase constitution near the joining interface of AZ31/Al composites were evaluated using optical and scanning electron microscope as well as X-ray diffraction (XRD). The results indicated that the higher annealing temperature promoted the formations of thicker bonding layers and more reaction phases near the joining interface, which mainly included Mg2Al3 and Mg17Al12 phases. The AZ31/Al laminated composite fabricated at 300 °C revealed thicker diffusion layer than that fabricated at 200 °C after anneal under the same condition, and the appropriate technological parameters of fabricating AZ31/Al laminated composites were also discussed. 相似文献
157.
Mark Spivack 《Journal of Modern Optics》2017,64(17):1768-1776
The moments of a plane wave scattered at low grazing angles from a one-dimensional perfectly reflecting rough surface are considered. The mean intensity and autocorrelation of the scattered field and the corresponding angular spectrum are obtained to second order in surface height. The derivations are based on an operator expansion of the extended (two-way) parabolic integral equation solution. The resulting operator series describes successively higher-order surface interactions between forward and backward going components. The expressions derived may be regarded as backscatter corrections to those obtained via the standard (one-way) parabolic integral equation method. 相似文献
158.
全站仪自由设站在工程施工测量中具有更大的灵活性和敏捷性。探讨全站仪自由设站的作业原理、作业方法、作业精度,并以具体的工程案例验证全站仪自由设站在工程施工测量中的可行性。 相似文献
159.
160.