A novel approach to piecewise analytic agricultural machinery path reconstruction

Before analysing machinery operation in fields, it has to be coped with the problem that the GPS signals of GPS receivers located on the machines contain measurement noise, are time-discrete, and the underlying physical system describing the positions, axial and absolute velocities, angular rates and angular orientation of the operating machines during the whole working time are unknown. This research work presents a new three-dimensional mathematical approach using kinematic relations based on control variables as Euler angular velocities and angles and a discrete target control problem, such that the state control function is given by the sum of squared residuals involving the state and control variables to get such a physical system, which yields a noise-free and piecewise analytic representation of the positions, velocities, angular rates and angular orientation. It can be used for a further detailed study and analysis of the problem of why agricultural vehicles operate in practice as they do.     

A survey on coverage path planning for robotics

Coverage Path Planning (CPP) is the task of determining a path that passes over all points of an area or volume of interest while avoiding obstacles. This task is integral to many robotic applications, such as vacuum cleaning robots, painter robots, autonomous underwater vehicles creating image mosaics, demining robots, lawn mowers, automated harvesters, window cleaners and inspection of complex structures, just to name a few. A considerable body of research has addressed the CPP problem. However, no updated surveys on CPP reflecting recent advances in the field have been presented in the past ten years. In this paper, we present a review of the most successful CPP methods, focusing on the achievements made in the past decade. Furthermore, we discuss reported field applications of the described CPP methods. This work aims to become a starting point for researchers who are initiating their endeavors in CPP. Likewise, this work aims to present a comprehensive review of the recent breakthroughs in the field, providing links to the most interesting and successful works.     

长深高速（唐山段）全程监控系统建设研究与实践

高速公路全程监控技术,在保证高速公路安全畅通的同时,为高速公路的养护及堵截漏逃费行为提供了较为重要的辅助手段,减少并及时处理交通事故,使监控系统功能发挥实现最大化,研究实践全程监控系统在公路建设中具有极其重要的现实意义。本文以长深高速公路唐山段全程监控工程为例,从实践层面介绍了全程监视系统工程经验与体会,并对主要技术特点进行了分析,阐述了现代智能交通领域中高速公路全程监控的新特点和构成。     

手机前模整体电极自动编程优化策略研究

以UG为自动编程工具．制定了适合电极高速加工的自动编程工艺方案，重点对改善不合格刀路的优化策略进行了详细说明．实现了产品的高速、高质量加工．对此类电极的数控加工提供了很好的借鉴和参考。     

S109FA机组汽轮机高压通流部分故障分析

针对S109FA机组中汽轮机在运行10 000 h后出现带负荷能力下降的情况进行了研究和分析,先后排除了高压主汽联合阀MSCV滤网堵塞、阀芯脱落等因素,根据试验数据,并运用排除法最后确认原因为高压缸内通流面积减小,通流受阻,导致机组不能带到额定负荷.并提出了预防监测的措施.     

基于改进 RRT ∗ 算法的智能轮椅全局路径规划研究

现实环境中智能轮椅大多数处在复杂场景下工作,其自主导航时对路径安全性等要求较高。 渐进最优随机搜索树 RRT ∗ 算法 基本满足移动机器人最优路径规划,但由于智能轮椅本体较大,容易与环境较近接触,因此可对环境模型进行膨胀并定义不同搜索步 长,使其规划出的路径远离障碍物。 其次为保证用户在使用智能轮椅导航时能够获得更高的舒适性,更高效的到达目的地,而借用启 发式约束采样思想和人工势场中引力场思想修剪此算法规划时的冗余节点,从而减小系统运行内存,随后结合轮椅的最小转弯半径, 提出最小段路径曲率约束策略和三次 B 样条曲线算法对路径进行平滑处理,使其更加适合轮椅行驶。 最终在 MATLAB 和 Gazebo 仿真 平台对改进前后算法对比实验,并将本文算法应用与智能轮椅实体上,试验结果表明,该算法能够有效解决智能轮椅全局路径规划问 题,能够明显提升全局路径规划效率,具有一定安全性,可为其移动机器人领域提供有效参考。     

A Spectral-SAR Model for the Anionic-Cationic Interaction in Ionic Liquids: Application to Vibrio fischeri Ecotoxicity

Within the recently launched the spectral-structure activity relationship (S-SAR) analysis, the vectorial anionic-cationic model of a generic ionic liquid is proposed, along with the associated algebraic correlation factor in terms of the measured and predicted activity norms. The reliability of the present scheme is tested by assessing the Hansch factors, i.e. lipophylicity, polarizability and total energy, to predict the ecotoxicity endpoints of wide types of ionic liquids with ammonium, pyridinium, phosphonium, choline and imidazolium cations on the aquatic bacteria Vibrio fischeri. The results, while confirming the cationic dominant influence when only lipophylicity is considered, demonstrate that the anionic effect dominates all other more specific interactions. It was also proved that the S-SAR vectorial model predicts considerably higher activity for the ionic liquids than for its anionic and cationic subsystems separately, in all considered cases. Moreover, through applying the least norm-correlation path principle, the complete toxicological hierarchies are presented, unfolding the ecological rules of combined cationic and anionic influences in ionic liquid toxicity.     

Stress paths and mechanical behavior of a sandstone in hollow cylinder tests

A series of hollow cylindrical triaxial tests was performed to investigate the potential effect of stress paths on the mechanical behavior of the Pei-Tou sandstone. The tests were carried out with a computer-controlled loading system. The axial loading, outer and inner confining pressures, and torque applied to the specimen were controlled according to a preselected stress path. The stress path moved from the hydrostatic stress axis in principal-stress space and elongated on an octahedral plane, while maintaining a constant angle θ against the projection of the major principal stress axis on the octahedral plane. The proposed hollow cylinder test is shown to be able to follow any designed stress paths in the principal stress space. Thus, it may be used to investigate the effect of stress paths on the mechanical behavior of rock and to construct its failure surface.     

加纳布维水电站调相运行系统设计简介

从水轮发电机组调相、压水系统的设计计算、控制流程、止漏环冷却、补气等环节对加纳布维水电站调相系统设计进行详细介绍,为其它水电站调相运行系统的设计提供参考。