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21.
A Novel Navigation Method for Autonomous Mobile Vehicles 总被引:3,自引:0,他引:3
This paper presents a novel navigation method for Autonomous Mobile Vehicle in unknown environments. The proposed navigator consists of an Obstacle Avoider (OA), a Goal Seeker (GS), a Navigation Supervisor (NS) and an Environment Evaluator (EE). The fuzzy actions inferred by the OA and the GS are weighted by the NS using the local and global environmental information and fused through fuzzy set operation to produce a command action, from which the final crisp action is determined by defuzzification. The EE tunes the supports of the fuzzy sets for the OA and the NS; therefore, the capability of the navigation method is enhanced. Simulation shows that the navigator is able to perform successful navigation task in various unknown or partially known environments, and it has satisfactory ability in tackling moving obstacles. More importantly, it has smooth action and exceptionally good robustness to sensor noise. 相似文献
22.
本文以智能配电网自动化系统为背景,对智能配电网自动化系统的内容、功能和整体结构进行了说明,并从近年来各地区配电网的实际运行情况出发,分析和总结影响配电网安全运行的主要因素,研究和论证配电网发展领域实现自动化的重要组成部分——用户分界开关成套设备,并对设备中采用的"看门狗"技术进行了详细的介绍及应用描述,针对如何在现有配电网络基础上完善配电网管理模式和管理手段的问题,提出了从根本上提高配电网科学化管理水平的全面解决方案。分界开关在10kV馈电架空线路和地缆网线路上的应用,可大幅度减少无故障线路的连带性事故停电,缩小故障停电范围和用户停电时间,从而提高用户的供电可靠性,产生极大的经济和社会效益。 相似文献
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Detecting Hot Road Mobility of Vehicular Ad Hoc Networks 总被引:1,自引:1,他引:0
Daqiang Zhang Hongyu Huang Jingyu Zhou Feng Xia Zhe Chen 《Mobile Networks and Applications》2013,18(6):803-813
Vehicular Ad Hoc Networks (VANETs) can provide value-added services to both drivers and passengers with on-board vehicular communication systems. Node mobility and volatile wireless connection in VANETs affect inter-contact time (T I ) between mobile nodes, which greatly degrades the performance of vehicular applications. Nevertheless, the node spatial distribution in VANETs is another important factor especially in real applications. It positively affects the inter-contact time of vehicular nodes. By leveraging it, we can significantly improve the performance of data transmissions and inter-vehicle communication. To this end, we investigate the data collected from around 4,000 taxisin Shanghai and propose in this paper an efficient hot road mobility model. We find that most taxis distribute on some hot roads, which makes the node spatial distribution follow the power law. Based on this observation, we propose the concepts of indirect contact and heterogeneous inter-contact time (T H ) to reveal how hot roads can change the distribution of inter-contact time. We find that the tail distribution of T H also appears the power law, and both node spatial distribution and T H distribution decay at least as the power law. We further propose a model for detecting vehicle mobility in hot roads, which can generates synthetic traces that captures both spatial and temporal features of nodes in VANETs. 相似文献
27.
This paper describes the results of structural, electronic and elastic properties of silicon nitride(in its high-pressure P61 and P62 phases) through the first-principles calculation combined with an ultra-soft pseudopotential. The computed equilibrium lattice constants agree well with the experimental data and the theoretical results. The strongest chemical bond(N–Si bond) shows a covalent nature with a little weaker ionic character. P61-Si3N4 is more stable than P62-Si3N4 due mainly to the fact that the shorter N–Si bond in the P61 phase allows stronger electron hybridizations. We have also predicted the phase stability of Si3N4 using the quasi-harmonic approximation, in which the lattice vibration and phonon effect are both considered. The results show that the β→P61 phase transition is very likely to occur at 42.9 GPa and 300 K. The reason why the β→P61→δ phase transitions had never been observed is also discussed. 相似文献
28.
本文主要采用密度泛函理论框架下的赝势平面波方法结合超软赝势计算研究氮化硅半导体材料(新发现的结构: P61和P62相)的晶胞结构、电子结构和弹性性质。计算得到的点阵常数与实验值和前人的理论值符合的相当好。该半导体材料中最强的化学键是N-Si键,N-Si键主要以共价键形式出现,同时含有微弱的离子键特征。研究还发现P61相比P62相更稳定,这是由于P61相中的N-Si键的键长较短,因此共价键更强。接着,本文通过准谐近似方法计算研究了氮化硅半导体的相变规律。在计算过程中考虑了晶格振动、声子效应和非谐效应对体系性质的影响。本文研究发现 β→P61 相变很可能在42.9GPa压强和300K温度下被观测到。另外,以前的实验研究没有观测到 β→P61→δ相变的原因在本文中也进行了讨论。 相似文献
29.
To start with, an analytical layer-element (i.e., a symmetric stiffness matrix), which describes the relationship between the generalized displacements and the stress levels of a layer subjected to non-axisymmetric loading, is exactly derived in the transformed domain by the application of a Laplace–Hankel transform with respect to variables t and r, a Fourier expansion with respect to variable θ, and a Laplace transform and its inversion with respect to variable z, based on the governing equations of Biot’s consolidation of multi-layered saturated poroelastic materials with anisotropic permeability. The analytical layer-element experiences considerable improvement in computation efficiency and stability, since it only contains negative exponential functions in its elements. In addition, a global stiffness matrix for multi-layered saturated poroelastic media is obtained by assembling the interrelated layer-elements based on the continuity conditions between adjacent layers. By introducing the boundary conditions and solving the global stiffness matrix, the solutions in the Laplace–Hankel transformed domain are obtained, and the final solutions can be recovered by a numerical inversion of the Laplace–Hankel transform. Finally, numerical examples are presented to verify the theory and to study the effect of the property of anisotropic permeability on vertical displacements and excess pore pressure. The calculation results show that the property of anisotropic permeability has a great influence on the process of consolidation. 相似文献
30.
Dr. Paolo Beuzer Dr. James J. La Clair Prof. Hu Cang 《Chembiochem : a European journal of chemical biology》2016,17(11):999-1003
Although the development of super‐resolution microscopy dates back to 1994, its applications have been primarily focused on visualizing cellular structures and targets, including proteins, DNA and sugars. We now report on a system that allows both monitoring of the localization of exogenous small molecules in live cells at low resolution and subsequent super‐resolution imaging by using stochastic optical reconstruction microscopy (STORM) on fixed cells. This represents a powerful new tool to understand the dynamics of subcellular trafficking associated with the mode and mechanism of action of exogenous small molecules. 相似文献