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自追踪、数据化和社交性:移动互联时代的时间管理 被引量:12
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作者 孙文峥 《现代传播(中国传媒大学学报)》 CSSCI 北大核心 2021年第7期158-163,共6页
以时间管理为导向的移动软件和应用分为"要事清单"和"时间约束"两种类型。在高效利用时间成为个人日常生活管理原则的同时,移动互联时代进一步强化了人们对于克制、专注、有序的追求。使用软件组织和规划时间,是人... 以时间管理为导向的移动软件和应用分为"要事清单"和"时间约束"两种类型。在高效利用时间成为个人日常生活管理原则的同时,移动互联时代进一步强化了人们对于克制、专注、有序的追求。使用软件组织和规划时间,是人们希冀于通过进入一种技术化的时间语言和时间秩序,将生活回归序列化的现代性时间框架之中,并在此基础上实现自我在时间上的"能够"和整体生活的全方位建构。此外,人们的时间体验日益数据化,数据开始成为影响自我认知、与他者展开互动和审视生活的一个重要因素。 展开更多
关键词 时间管理 要事清单 时间约束 自追踪
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基于PWM自追踪的零转换降压转换器设计
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作者 徐俊武 张姨平 熊博文 《组合机床与自动化加工技术》 北大核心 2021年第12期147-150,共4页
针对传统降压转换器电流电压应力大、开关损耗严重和电能转换效率低所造成的电磁干扰等诸多不良影响的问题。对零转换PWM电路的控制策略进行了研究,提出了PWM自动追踪算法,采用该算法设计了零转换降压转换器。首先,设计拓扑结构中谐振... 针对传统降压转换器电流电压应力大、开关损耗严重和电能转换效率低所造成的电磁干扰等诸多不良影响的问题。对零转换PWM电路的控制策略进行了研究,提出了PWM自动追踪算法,采用该算法设计了零转换降压转换器。首先,设计拓扑结构中谐振电路与主开关并联从而优化负载电压电流峰值,然后,改善检测器触发器进而提高转换器的换流效率。最后,基于MATLAB平台搭建仿真实验和设计搭建了100 W/10 kHz小功率样机对转换器的各项功能进行实验验证,实验结果验证了所设计的转换器可以有效减少电流电压应力、降低损耗和提高电能转换效率。 展开更多
关键词 PWM自追踪 降压转换器 控制策略 零转换自检
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免调整自追踪太阳能发电系统的设计与研究
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作者 叶金虎 阴辉 邓国悦 《机电技术》 2018年第1期2-4,共3页
针对传统的固定式太阳能板在进行光电转换时,存在太阳光利用率不充分的情况,研究设计了一种自动追日光伏系统:利用四象限光敏传感器及STC15F2K60S2单片机组成的控制模块,对双轴直流电机进行实时控制,以保证太阳能采集板进行水平方向和... 针对传统的固定式太阳能板在进行光电转换时,存在太阳光利用率不充分的情况,研究设计了一种自动追日光伏系统:利用四象限光敏传感器及STC15F2K60S2单片机组成的控制模块,对双轴直流电机进行实时控制,以保证太阳能采集板进行水平方向和垂直方向的双向旋转。系统实现了太阳光线对太阳能板的垂直照射,从而能最大程度吸收太阳光,提高光伏板的光电转换效率。 展开更多
关键词 免调整 自追踪 太阳能 发电
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一种双轴式自追踪光伏太阳能支撑装置的设计 被引量:1
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作者 刘文正 戴文来 +1 位作者 李娜 李发家 《机械工程师》 2019年第10期79-81,共3页
为了提高光伏太阳能的发电效能,提出了一种双轴式自追踪光伏太阳能支撑装置,通过离合器的开关实现装置的水平旋转与俯仰调节。文中对装置的总体结构进行设计并进行分析计算,通过机构仿真验证了机构的可行性。
关键词 双轴式 自追踪 支撑装 机构仿真
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Transport phenomena and keyhole evolution process in laser welding of stainless steel 被引量:1
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作者 LIU Jiang-wei ZENG Ping-wang +1 位作者 RAO Zheng-hua ZHANG Tian-li 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第8期2088-2099,共12页
Knowledge of transport phenomena and keyhole evolution is important for controlling laser welding process. However, it is still not well understood by far due to the complex phenomena occurring in a wide temperature r... Knowledge of transport phenomena and keyhole evolution is important for controlling laser welding process. However, it is still not well understood by far due to the complex phenomena occurring in a wide temperature range. A transient 3D model including heat transfer, fluid flow and tracking of free surface is built in this study. The transport phenomena are investigated by calculating the temperature and velocity fields. The 3D dynamic keyhole evolution process is revealed through tracking free surface using volume-of-fluid method. The results show that the keyhole deepening speed decreases with laser welding process before the quasi-steady state is reached. The plasma can greatly affect the keyhole depth through absorbing a great amount of laser energy and thus lowering the recoil pressure. Moreover, the relationship between keyhole depth and weld penetration is also discussed. This paper can help to better understand the dynamics in molten pool and then improve laser welding process. 展开更多
关键词 laser welding keyhole evolution weld pool dynamics free surface tracking weld penetration
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Design of robust fuzzy controller for ship course-tracking based on RBF network and backstepping approach 被引量:4
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作者 ZHANG Song-tao REN Guang 《Journal of Marine Science and Application》 2006年第3期5-10,共6页
This study presents an adaptive fuzzy neural network (FNN) control system for the ship steering autopilot. For the Norrbin ship steering mathematical model with the nonlinear and uncertain dynamic characteristics, an ... This study presents an adaptive fuzzy neural network (FNN) control system for the ship steering autopilot. For the Norrbin ship steering mathematical model with the nonlinear and uncertain dynamic characteristics, an adaptive FNN control system is designed to achieve high-precision track control via the backstepping approach. In the adaptive FNN control system, a FNN backstepping controller is a principal controller which includes a FNN estimator used to estimate the uncertainties, and a robust controller is designed to compensate the shortcoming of the FNN backstepping controller. All adaptive learning algorithms in the adaptive FNN control system are derived from the sense of Lyapunov stability analysis, so that system-tracking stability can be guaranteed in the closed-loop system. The effectiveness of the proposed adaptive FNN control system is verified by simulation results. 展开更多
关键词 fuzzy neural network ship course-tracking adaptive control backstepping approach
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Three-dimensional microstructure simulation of Ni-based superalloy investment castings 被引量:7
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作者 PAN Dong XU QingYan LIU BaiCheng 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2011年第5期851-855,共5页
An integrated macro and micro multi-scale model for the three-dimensional microstructure simulation of Ni-based superalloy investment castings was developed, and applied to industrial castings to investigate grain evo... An integrated macro and micro multi-scale model for the three-dimensional microstructure simulation of Ni-based superalloy investment castings was developed, and applied to industrial castings to investigate grain evolution during solidification. A ray tracing method was used to deal with the complex heat radiation transfer. The rnicrostructure evolution was simulated based on the Modified Cellular Automaton method, which was coupled with three-dimensional nested macro and micro grids. Experi- ments for Ni-based superalloy turbine wheel investment casting were carried out, which showed a good correspondence with the simulated results. It is indicated that the proposed model is able to predict the microstructure of the casting precisely, which provides a tool for the optimizing process. 展开更多
关键词 MICROSTRUCTURE SIMULATION Ni-based superalloy investment casting
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