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991.
Meccanica - In this paper, we develop a framework of time optimization path planning for robotic manipulators surrounded by static obstacles. Our approach is based on the recursive dynamics method... 相似文献
992.
有限质点法是以向量式力学为基础,用有限数量的质点来模拟结构的变形行为,质点的运动由牛顿运动定律来计算。在有限质点法中,质点通过构件相连,构件约束着质点的运动,并且其内力由质点的运动变量来描述。基于向量式力学的基本思想和非线性梁理论,提出了一种新的有限质点法,该方法在共旋单元坐标系中描述梁的非线性变形。以空间梁系结构为例,推导了计算构件内力的非线性公式,并考虑了弯扭耦合变形。通过两个连续欧拉角的变换公式得到共旋坐标系的旋转矩阵。与传统的有限质点法相比,本文提出的方法避免了刚体虚转动分析。通过四个结构的数值求解,验证了本文方法在计算结构大变形响应时具有较高的精度。 相似文献
993.
基于红外图像的行人检测技术在夜间场景监控、汽车夜间辅助驾驶等相关领域具有重要的作用,然而受红外图像分辨率低、信噪比高等因素影响,当前的很多方法性能不佳。提出了一种基于图像特征通道的红外行人检测算法。利用快速特征金字塔技术在红外图像上进行了滑动窗口检测。实验结果证明,相对于其他常规算法,该算法在实时性和鲁棒性上都有很大的提升。 相似文献
994.
The Reynolds averaged N-S equation and dynamic equation for nanoparticles are numerically solved in the two-phase flow around cylinders, and the distributions of the concentration M0 and geometric mean diameter dg of particles are given. Some of the results are validated by comparing with previous results. The effects of particle coagulation and breakage and the initial particle concentration m00 and size d0 on the particle distribution are analyzed. The results show that for the flow around a single cylinder, M0 is reduced along the flow direction. Placing a cylinder in a uniform flow will promote particle breakage. For the flow around multiple cylinders, the values of M0 behind the cylinders oscillate along the spanwise direction, and the wake region in the flow direction is shorter than that for the flow around a single cylinder. For the initial monodisperse particles, the values of dg increase along the flow direction and the effect of particle coagulation is larger than that of particle breakage. The values of dg fluctuate along the spanwise direction; the closer to the cylinders, the more frequent the fluctuations of dg values. For the initial polydisperse particles with d0 = 98 nm and geometric standard deviation σ = 1.65, the variations of dg values along the flow and spanwise directions show the same trend as for the initial monodisperse particles, although the differences are that the values of dg are almost the same for the cases with and without considering particle breakage, while the distribution of dg along the spanwise direction is flatter in the case with initial polydisperse particles. 相似文献
995.
A series of new thiophene-containing triaryl pyrazoline derivatives, 3a–3t, were synthesized and evaluated regarding PI3K inhibition activity and anti-tumor potency based on a trial of introducing significant moieties, including pyrazoline and thiophene, and simplifying the parallel ring structures. Most of the tested compounds indicated potent PI3K inhibitory potency, with this series of compounds showing more potency for PI3Kγ than PI3Kα. The top hit 3s seemed more potent than the positive control LY294002 on inhibiting PI3Kγ (IC50 values: 0.066 μM versus 0.777 μM) and more selective from PI3Kα (Index values: 645 versus 1.74). It could be inferred that the combination of para- and meta-, as well as the modification of the electron-donating moieties, led to the improvement in potency. The anti-proliferation inhibitory activity and the enzymatic inhibition potency indicated consistent tendencies. The top hit 3s could inhibit the phosphorylation of Akt by inhibiting PI3K through the PI3K-Akt-mTOR pathway. The molecular docking simulation indicated that the binding pattern of 3s into PI3Kγ was preferable than that of PI3Kα, with more hydrogen bond, more π-involved interactions, and fewer π-sulfur interactions. The information in this work is referable for the further development of selective inhibitors for specific isoforms of PI3K. 相似文献
996.
997.
998.
活性碳纳米管的制备及其在有机电解液中的电容性能研究 总被引:1,自引:0,他引:1
以KOH为活化剂对碳纳米管进行化学活化制备双电层电容器用高比表面积活性碳纳米管. 采用TEM和N2吸附法表征活性碳纳米管的结构, 采用恒流充放电、循环伏安、交流阻抗等评价其在1 mol•L-1 Et4NBF4/PC中的电容性能. 随活化剂用量增大、活化温度升高和活化时间的延长, 活性碳纳米管的比表面积和比电容都呈增大的趋势. 活化剂用量为3∶1, 800 ℃活化4 h制备的活性碳纳米管的比表面积663 m2•g-1, 比活化前提高了3倍, 其比电容达57.2 F• g-1, 比活化前提高了2倍. 将活性碳纳米管的比电容与其比表面积相关联, 发现两者之间具有非常好的线性关系, 并分析了原因. 相似文献
999.
Jia Rong Li~* Li Jun Zhang Xi Quan Yang Qing Li Dong Wang Chun Xia Wang Da Xin Shi Qi Zhang School of Chemical Engineering Environment Beijing Institute of Technology Beijing China 《中国化学快报》2008,(1)
Two different skeletons of heterocyclic compounds,quinoline and quinazolinone analogs could be obtained by a novel one-pot synthesis from substituted 3-amino-1 H-benzo[f]chromene-2-carbonitrile derivatives and cyclohexanone in DMF in the catalyst of anhydrous zinc chloride under reflux.A plausible mechanism was proposed. 相似文献
1000.
The Cu/SiO2 catalyst prepared by incipient wetness method exhibited very high activity and selectivity for the vapor-phase synthesis of JV-butylaniline from aniline and 1-butanol. When Cu loading was 0.70 mmol/g-SiO2 and the catalyst precursor was calcined at 500 ℃, 1-butanol conversion reached 99%, and the selectivity of JV-butylaniline exceeded 97%. 相似文献