31 research outputs found
12. Encyclopaedias
No full textGuide to traditional Chinese encyclopeadiasA survey of the most important traditional Chinese encyclopaedias, including detailed discussions of studies and indexes related to them. Major encyclopaedias discussed include Bei-Tang shuchao, Yiwen leiju, Chuxue ji, Boshi liutie shileiji, Taiping yulan, Cefu yuangui, Yongle da dian, Gujin tushu jicheng, as well as the Shitong
From the Five Dynasties to the Northern Song: The Policies toward the Southern Tang Employed by the Emperors Taizu and Shizong during the Later Zhou Period and the Change in These Policies
No full textInterstate relations during the Five Dynasties and Ten Kingdoms periods had been regulated by the so-called “world order” that was centered on rule from the Zhongyuan 中原 region. However, this perception was influenced by the recognition of historical materials compiled in the Northern Song Dynasty. Thus, attempts at elucidating interstate relations at the time need to be made, to the extent possible, using actual documents exchanged between these states and their rulers.
Therefore, this paper focuses on the interactions between the states of the Later Zhou and the Southern Tang. A large number of citations are taken from the Cefu Yuangui 册府元龜, which mentions the war between these two states that lasted from 956 to 958 as well as the peace negotiations and subsequent postwar process. The Southern Tang utilized documents in a form known as biao 表, a memorial to the throne, while the Later Zhou utilized documents with an opening phrase of either “The Emperor respectfully asks” (Huangdi jingwen 皇帝敬問) or “The Emperor respectfully asks by letter” (Huangdi zhishu jingwen 皇帝致書敬問). In the Five Dynasties period, the zhishu 致書 (to write a letter) format indicating the equality of sender and recipient was commonly used in documents exchanged between states and rulers, but the correspondence mentioned above between the Later Zhou and the Southern Tang is an exception to this general rule.
By tracing the changes in the relationship between these two countries, this paper attempts to elucidate the specifics of the transition period from the Five Dynasties to the Northern Song. The first section presents a view of the circumstances during the reign of the Later Zhou Emperor Taizu 太祖 and points out that statements made at the time avoided negativity and placed greater priority on the stability of trade in the border region. The second section presents an overview of documents that were sent to the Southern Tang by Emperor Shizong 世宗. Finally, the third section presents a description of the fact that the Southern Tang demanded to become a “foreign vassal” (waichen 外臣) of the Later Zhou, that the Later Zhou replied to this demand using the Huangdi jingwen format; but the Later Zhou was not particular about making the Southern Tang a vassal state. Therefore, Shizong sometimes used the phrase Huangdi zhishu jingwen to show respect to the Southern Tang. This case symbolizes the late Five Dynasties period during which the “unification” of China was not necessarily considered yet.journal articl
Modeling and Optimization of Wheel-Propeller-Leg Integrated Driving Mechanism for an Amphibious Robot
No full textAn optimal visual servo trajectory planning method for manipulators based on system nondeterministic model
No full textWhen a manipulator captures its target by a visual servo system, uncertainties can arise because of mechanical system and visual sensors exist error. This paper proposes an intelligent method to predict the successful rate for a manipulator to capture its target with motion and sensor errors. Because the mapping between the joint space of the manipulator and the Cartesian space at the end of the manipulator is nonlinear, when there is a bounded error of the manipulator's joint, the error range of the end motion is constantly changing with the different joint positions. And at the same time, the visual servo camera will also measure the target from different positions and postures, so as to produce measurement results with different error ranges. The unknown time-varying error property not only greatly affects the stability of the closed-loop control but also causes the capture failure. The purpose of this paper is to estimate the success probability of different capture trajectories by establishing the nondeterministic model of manipulator control system. First, a system model including motion subsystem and feedback subsystem was established with system error described by Gaussian probability. And then Bayesian estimation was introduced into the system model to estimate the executing state of the predefined trajectory. Linear least quadratic regulators (LQR) control is used to simulate the input correction in the closed-loop control between motion subsystem and feedback subsystem. At last, the successful probability of capturing the target is established by the Gaussian distribution at the end point of the trajectory with geometric relationship calculation between tolerance range and error distribution. The effectiveness and practicability of the proposed method are proved by simulation and experiment
Research on visual multi-target based pose estimation algorithm for ARV underwater docking
No full textOn-line self-calibration method for unattended manipulators based on Gaussian motion model and visual system
No full textPurpose-For some special manipulators such as the ones work at the space station, nuclear or some other unmanned environments, the overload, collision, vibration, temperature change or release of the internal stress would affect the structural parameters. And thus the operation precision might constantly decrease in long-term use. In these unmanned environments, the unattended manipulators should calibrate itself when they execute high precision operations or proceed self-maintenances. The purpose of this paper is to propose an automatic visual assistant on-line calibration (AVOC) method based on multi-markers.
Design/methodology/approach-A camera fixed on the end of the manipulator is used to measure one to three identification points, which forms an unstable multi-sensor eye-in-hand system. A Gaussian motion method which combines the linear quadratic regulator control and extended Kalman filter together is proposed to make the manipulator track the planned trajectories when its inaccurate structural parameters form uncertain motion errors. And a Monte-Carlo method is proposed to form a high precision and stable signal acquisition when the visual system has measurement errors and intermittent signal feedback. An automatic sampling process is adopted to select the optimal measurement points basing on their variances.
Findings-Data analysis and experiment results prove the efficiency and feasibility of the method proposed in this paper. With this method, the positioning accuracy is largely promoted from about 2 mm to 0.04-0.05 mm.
Originality/value-Experiments were carried out successfully on a manipulator in a life sciences glove box that will work at the Chinese space station. It is a low cost and efficient manipulator calibration method. The whole autonomic calibration process takes less than 10 min and requires no human intervention. In addition, this method not only can be used in the calibration of other unmanned articulated manipulator that works in deep ocean, nuclear industry or space but also be useful for the maintenance work in modern factories owing a lot of industrial robots
Station-Keeping Control of Autonomous and Remotely-Operated Vehicles for Free Floating Manipulation
No full textThis paper investigates the station-keeping control of autonomous and remotely-operated vehicles (ARVs) for free-floating manipulation under model uncertainties and external disturbances. A modified adaptive generalized super-twisting algorithm (AGSTA) enhanced by adaptive tracking differentiator (ATD) and reduced-order extended state observer (RESO) is proposed. The ATD is used to obtain the smooth reference signal and its derivative. The RESO is used to estimate and compensate for the model uncertainties and external disturbances in real-time, which enhances the robustness of the controller. The modified AGSTA ensures the fast convergence of the system states and maintains them in a predefined neighborhood of origin without overestimating control gains. Besides, the proposed new variable gain strategy completely avoids the control gains vibrating near the set minimum value. Thanks to the RESO, the proposed controller is model-free and can be easily implemented in practice. The stability of the closed-loop system is analyzed based on Lyapunov’s direct method in the time domain. Finally, the proposed control scheme is applied to the station-keeping control of Haidou-1 ARV, and the simulation results confirm the superiority of the proposed control scheme over the original AGSTA
A time-efficient CFD approach for hydrodynamic coefficient determination and model simplification of submarine
No full textManeuverability Is one of the most important performance characteristics of submarines. Hydrodynamic model is increasingly relied on as a design approach to determine the inherent motion behavior of a proposed submarine before construction. Standard submarine motion equations are the most used hydrodynamic model, in which more than 100 coefficients need to be estimated. These coefficients have to be determined by captive model tests, semi-empirical method and potential flow method on the basis of existing approach. The separately determining approach makes It difficult to assess model reliability. This paper proposes a time-efficient approach for the estimation of hydrodynamic coefficients using computational fluid dynamics (CFD) method. Instead of a repetitive and time-consuming process, the proposed spatial captive motion could provide all necessary information for determination of all required coefficients in only one simulation. Linear regression, based on the least square method, is employed to determine coefficients in hydrodynamic model. Statistical investigation, correlation and significance analysis, indicates that the standard submarine motion equations can be further simplified when submarine moving forward with small perturbations along other directions. The final simplified motion equations have much fewer components than the original model while fitting accuracy remained. Validation results prove that spatial captive motion simulation and the simplification approach employed in this paper are effective and reliable. It should have a large scope in further maneuverability research
Inhibition of interleukin-6 function attenuates the central sensitization and pain behavior induced by osteoarthritis
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