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人造海水侵蚀对棉单纱性能影响 被引量:1
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作者 陈慧 《现代纺织技术》 北大核心 2015年第6期5-8,共4页
通过自制海水对棉单纱进行侵蚀实验,观察分析海水侵蚀对棉纤维的微观形貌及棉单纱的强伸度、捻度、极限氧指数与毛羽指数的影响。研究表明,棉纤维经过海水的侵蚀,纵向表面出现了无规律分布、凸凹不平的孔穴。棉单纱的断裂强力、捻度... 通过自制海水对棉单纱进行侵蚀实验,观察分析海水侵蚀对棉纤维的微观形貌及棉单纱的强伸度、捻度、极限氧指数与毛羽指数的影响。研究表明,棉纤维经过海水的侵蚀,纵向表面出现了无规律分布、凸凹不平的孔穴。棉单纱的断裂强力、捻度与极限氧指数与毛羽指数随侵蚀时间的增加而逐渐降低,而纱线的断裂伸长率随侵蚀时间的增加而逐渐增大。棉单纱的强伸性能、捻度、极限氧指数随时间的变化的最大速率取值区间均在70-110h。棉单纱毛羽长度越长,经海水处理后,下降幅度越大。 展开更多
关键词 棉单纱 自制海水 微观形貌 侵蚀 毛羽指数
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Nonlinear trajectory tracking control of a new autonomous underwater vehicle in complex sea conditions 被引量:9
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作者 高富东 潘存云 +1 位作者 韩艳艳 张湘 《Journal of Central South University》 SCIE EI CAS 2012年第7期1859-1868,共10页
Autonomous underwater vehicles (AUVs) navigating in complex sea conditions usually require a strong control system to keep the fastness and stability. The nonlinear trajectory tracking control system of a new AUV in c... Autonomous underwater vehicles (AUVs) navigating in complex sea conditions usually require a strong control system to keep the fastness and stability. The nonlinear trajectory tracking control system of a new AUV in complex sea conditions was presented. According to the theory of submarines,the six-DOF kinematic and dynamic models were decomposed into two mutually non-coupled vertical and horizontal plane subsystems. Then,different sliding mode control algorithms were used to study the trajectory tracking control. Because the yaw angle and yaw angle rate rather than the displacement of the new AUV can be measured directly on the horizontal plane,the sliding mode control algorithm combining cross track error method and line of sight method was used to fulfill its high-precision trajectory tracking control in the complex sea conditions. As the vertical displacement of the new AUV can be measured,in order to achieve the tracking of time-varying depth signal,a stable sliding mode controller was designed based on the single-input multi-state system,which took into account the characteristic of the hydroplane and the amplitude and rate constraints of the hydroplane angle. Moreover,the application of dynamic boundary layer can improve the robustness and control accuracy of the system. The computational results show that the designed sliding mode control systems of the horizontal and vertical planes can ensure the trajectory tracking performance and accuracy of the new AUV in complex sea conditions. The impacts of currents and waves on the sliding mode controller of the new AUV were analyzed qualitatively and quantitatively by comparing the trajectory tracking performance of the new AUV in different sea conditions,which provides an effective theoretical guidance and technical support for the control system design of the new AUV in real complex environment. 展开更多
关键词 complex sea condition autonomous underwater vehicle (AUV) trajectory tracking sliding mode control
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