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再论汉代犁耕系驾法 被引量:2
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作者 史晓雷 《山东农业大学学报(社会科学版)》 2018年第4期1-9,共9页
2014年刘兴林发表《汉代犁耕驾牛方式和用具的初步研究》一文,对汉代犁耕系驾法得出若干认识。利用新的图像资料及农具史、物质文化史、科技史既有成果,对该文提出商榷意见。没有确切证据表明汉代犁耕二牛抬杠法是另用独立的绳将衡(杠)... 2014年刘兴林发表《汉代犁耕驾牛方式和用具的初步研究》一文,对汉代犁耕系驾法得出若干认识。利用新的图像资料及农具史、物质文化史、科技史既有成果,对该文提出商榷意见。没有确切证据表明汉代犁耕二牛抬杠法是另用独立的绳将衡(杠)与二牛颈索相连,更可能的方式是颈索两端分别与衡绑缚。汉代已经出现单牛双辕犁,其系驾法一种是在牛颈上搭横木式轭状物,两侧系辕牵引;另一种方式暂不明确。汉代牛马犋耕系驾法,目前明确的一种是不用衡,马用犁盘驾辕。汉代单牛独辕犁采用偏系法之说,缺乏依据。 展开更多
关键词 汉代 犁耕 牛耕 系驾法
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论秦始皇陵铜马车系驾构件中靷的结构和作用
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作者 周默轩 《自然科学史研究》 CSSCI CSCD 北大核心 2020年第4期453-466,共14页
秦始皇陵铜马车的出土有利于澄清许多原来关于系驾法的模糊认识,其中靷的发现使人们对其功能有了更多了解,并引发了关于“轭靷式系驾法”的讨论。文章重新从力学角度分析了秦始皇陵铜马车中靷各部分的作用,认为靷的主要功能在于承力、... 秦始皇陵铜马车的出土有利于澄清许多原来关于系驾法的模糊认识,其中靷的发现使人们对其功能有了更多了解,并引发了关于“轭靷式系驾法”的讨论。文章重新从力学角度分析了秦始皇陵铜马车中靷各部分的作用,认为靷的主要功能在于承力、平衡、减振及防止辀拔脱等,是曳车的重要系驾构件,论证了靷构成的整体结构可以单独构成一种系驾方式。靷及其附件的结构设计体现了古人的智慧,是中国古代对畜力利用的重要技术创造。 展开更多
关键词 秦始皇陵铜马车 轭靷式系驾法
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Dynamical Correction of Control Laws for Marine Ships’ Accurate Steering 被引量:1
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作者 Evgeny I. Veremey 《Journal of Marine Science and Application》 2014年第2期127-133,共7页
The objective of this work is the analytical synthesis problem for marine vehicles autopilots design. Despite numerous known methods for a solution, the mentioned problem is very complicated due to the presence of an ... The objective of this work is the analytical synthesis problem for marine vehicles autopilots design. Despite numerous known methods for a solution, the mentioned problem is very complicated due to the presence of an extensive population of certain dynamical conditions, requirements and restrictions, which must be satisfied by the appropriate choice of a steering control law. The aim of this paper is to simplify the procedure of the synthesis, providing accurate steering with desirable dynamics of the control system. The approach proposed here is based on the usage of a special unified multipurpose control law structure that allows decoupling a synthesis into simpler particular optimization problems. In particular, this structure includes a dynamical corrector to support the desirable features for the vehicle's motion under the action of sea wave disturbances. As a result, a specialized new method for the corrector design is proposed to provide an accurate steering or a trade-off between accurate steering and economical steering of the ship. This method guaranties a certain flexibility of the control law with respect to an actual environment of the sailing;its corresponding turning can be realized in real time onboard. 展开更多
关键词 marine ships control law dynamical corrector accurate steering autopilot sea wave
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A unified approach of observability analysis for airborne SLAM
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作者 方强 黄新生 《Journal of Central South University》 SCIE EI CAS 2013年第9期2432-2439,共8页
An unmanned aerial vehicle (UAV) is arranged to explore an unknown environment and to map the features it finds when GPS is denied.It navigates using a statistical estimation technique known as simultaneous localiza... An unmanned aerial vehicle (UAV) is arranged to explore an unknown environment and to map the features it finds when GPS is denied.It navigates using a statistical estimation technique known as simultaneous localization and mapping (SLAM) which allows for the simultaneous estimation of the location of the UAV as well as the location of the features it sees.Obscrvability is a key aspect of the state estimation problem of SLAM.However,the dimension and variables of SLAM system might be changed with new features.To solve this issue,a unified approach of observability analysis for SLAM system is provided,through reorganizing the system model.The dimension and variables of SLAM system keep steady,then the PWCS theory can be used to analyze the local or total observability,and under special maneuver,some system states,such as the yaw angle,become observable.Simulation results validate the proposed method. 展开更多
关键词 unmanned aerial vehicle (UAV) simultaneous localization and mapping (SLAM) inertial navigation system (INS) OBSERVABILITY extend Kalman filter (EKF)
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