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Nonlinear frequency analysis of buckled nanobeams in the presence of longitudinal magnetic field

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Acta Mechanica Solida Sinica 2017年第5期30卷 465-473页

作者： Xi-Ping Sun yuan-Zhuo Hong Hu-Liang dai Lin Wang Tianjin Research Institute Water Transport Engineering M.O.TTest Detection Center of Water Transport EngineeringTianjin 300456China Department of Mechanics Huazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory for Engineering Structural Analysis and Safety Assessment Wuhan 430074China

The nonlinear free vibration around the postbuckling configuration of nonlocal nanobeams with pinned-pinned boundary conditions are analytically investigated, considering the ge- ometric nonlinearity arising from the mid-plane stretching and particularly the effect of a longitudinal magnetic field. When the applied axial force is small, the nanobeam is stable and its free vibration is around the straight equilibrium position. As the axial force becomes large and is beyond a certain critical value （critical axial force）, however, either positive or negative non-trivial equilibrium configuration occurs and the free vibration is around the buckled configuration. The governing equation for the nanobeam before buckling exhibits a cubic nonlinearity while for a buckled nanobeam it contains both cubic and quadratic non- linearities. Based on the nonlinear governing equations, approximate analytical solutions for the postbuckling configuration in terms of the applied axial force are evaluated, show- ing that the magnetic field parameter has a great effect on the critical axial force, buckled displacement and linear frequencies of the nanobeam system. More interestingly, the non- linear frequency is found to be generally higher than the linear frequency in the case of prebuckling regime while it could be lower than the linear one in the case of postbuck- ling regime. The nonlinear frequency can be significantly influenced by the magnetic field, the nonlinear coefficient associated with the mid-plane stretching, and the initial vibration amplitude.

关键词： Nonlocal nanobeamPostbucklingNonlinear frequencyMagnetic fieldVibration

X-RAY STUDY ON TITANIUM NITRIDE FILMS DEPOSITED BY VCAD METHOD

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Transactions of Nonferrous Metals Society of China 1992年第1期2卷 65-68页

作者： Liu Xingcheng yuan Zhenhai dai Dahuan Guangzhou Research Institute of Nonferrous Metals 51005Guangzhou China

TiN films deposited by the VCAD method at the substrate of stainless steel and superhigh speed tool steels are uniform and *** colour,orientation and lattice parameter depend on deposited condition The lattice structure of deposited film,the change of the lattice parameter and its preferred orientation were studied by the XRD method,different behaviours of TiNx film were *** lattice parameter of TiNx films is increased with the nitrogen content and The colour of TiNx film is strongly related to the content of Nitrogen *** change of preferred orientation depends mainly on the Bias.

关键词： VCAD method TiN Film X-ray

Evidence for Anticancer Effects of Chinese Medicine Monomers on Colorectal Cancer

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Chinese Journal of Integrative Medicine 2022年第10期28卷 939-952页

作者： GUO Tian-hao LI yuan-yuan HONG Sheng-wei CAO Qian-yu CHEN Heng XU yuan dai Guo-liang SHAO Gang The First Clinical Medical College Nanjing University of Chinese MedicineNanjing(210023)China Department of Clinical Pharmacology Afﬁliated Hospital of Nanjing University of Chinese MedicineNanjing(210029)China

Colorectal cancer is one of the most commonly occurring cancers worldwide. Although clinical reports have indicated the anticancer effects of Chinese herbal medicine, the multiple underlying molecular and biochemical mechanisms of action remain to be fully characterized. Chinese medicine(CM) monomers, which are the active components of CM, serve as the material basis of the functional mechanisms of CM. The aim of this review is to summarize the current experimental evidence from in vitro, in vivo, and clinical studies for the effects of CM monomers on colorectal cancer prevention and treatment, providing some useful references for future research.

关键词： colorectal cancer Chinese medicine monomer anticancer effect experimental evidence

Postcapture stabilization of space robots considering actuator failures with bounded torques

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Chinese Journal of Aeronautics 2018年第10期31卷 2034-2048页

作者： Xiaokui YUE Teng ZHANG Honghua dai Xin NING Jianping yuan National Key Laboratory of Aerospace Flight Dynamics (AFDL) Northwestern Polytechnical University School of Astronautics Northwestern Polytechnical University Department of Mechanical Engineering University of Alberta

Space robotics is regarded as one of the most impressing approaches for space debris removal missions. Due to the residual momentum of debris, it is essential to stabilize the base rapidly after capture. This paper presents a novel control strategy for stabilization of a space robot in postcapture considering actuator failures and bounded torques. In the control strategy, the motion of the manipulator is not regarded as a disturbance to the base; in contrast, it is utilized to compensate for the limitation of the control torques by means of an inverse dynamical model of the system. Different scenarios where actuators are external mechanisms or momentum exchange devices have been carried out, and for actuator failures, both single-and two-actuator failures have been considered. Regarding to the performance of actuators, control torques are bounded. In cases that either single or two actuators have failed, the base can be stabilized kinematically when actuators are external mechanisms, but can only be stabilized dynamically when only momentum exchange devices are used. Finally, a space robot with a seven-degree-of-freedom manipulator in postcapture is studied to verify the validity and feasibility of the proposed control scheme. Simulation results show that the whole system can be stabilized rapidly.

关键词： Actuator failure Attitude control Bounded torque Postcapture Space robot

Adaptive fuzzy compensation based composite nonlinear feedback controller design for robot manipulators

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High Technology Letters 2019年第4期25卷 426-433页

作者： Jiang yuan Gong Chenglong dai Jiyang College of Information Engineering Nanchang Hangkong UniversityNanchang 330063P.R.China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049P.R.China

In order to suppress the influence of uncertain factors on robot system and enable an uncertain robot system to track the reference input accurately,a strategy of combining composite nonlinear feedback(CNF)control and adaptive fuzzy control is studied,and a robot CNF controller based on adaptive fuzzy compensation is *** key of this strategy is to use adaptive fuzzy control to approach the uncertainty of the system online,as the compensation term of the CNF controller,and make full use of the advantages of the two control methods to reduce the influence of uncertain factors on the performance of the *** convergence of the closed-loop system is proved by feedback linearization and Lyapunov *** final simulation results confirm the effectiveness of this plan.

关键词： robot uncertainty composite nonlinear feedback(CNF) adaptive fuzzy control system convergence

A Simple Approach to Control the Growth of Non-spherical Gold Nanoparticles

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Chinese Chemical Letters 2003年第11期14卷 1163-1166页

作者： Hong yuan Ru Xiu CAI dai Wen PANG College of Chemistry and Molecular Sciences Wuhan UniversityWuhan 430072

A simple method to prepare the non-spherical gold particles was developed. The result solution included trigonal, truncated trigonal, hexagonal layers, and a pseudo-pentagonal shaped gold nanocrystals. The key factor is to control the relative rates of nucleation and cluster growth in this method. These attributes make seeding growth method as a useful tool in the fabrication of colloidal metal materials. A longitudinal plasmon resonance of 866 nm was observed, which is in the near-IR spectral regions (600-1000 nm). The excellent optical properties as near-IR labels are used to develop highly sensitive analysis method.

关键词： Controlled synthesis shaped nanoparticles gold.

Forehead sEMG signal based HMI for hands-free control

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The Journal of China Universities of Posts and Telecommunications 2014年第3期21卷 98-105页

作者： ZHANG Yi ZHU Xiang dai Ling-ling LUO yuan National Engineering Research and Development Center for Information Accessibility Chongqing University of Posts and Telecommunications

A hands-free method is proposed to control an electric powered wheelchair （EPW） based on surface electromyography （sEMG） signals. A CyberLink device is deployed to obtain and analyze forehead sEMG signals generated by the facial movements. The autoregressive （AR） model is used to extract sEMG features. Then, the back-propagation artificial neural network （BPANN） is proposed to recognize different facial movement patterns and improved by Bayesian regularization and Levenberg-Marquardt （LM） algorithm. A sEMG based human-machine interface （HMI） is designed to map facial movement patterns into corresponding control commands. The experimental results show that the method is simple, real-time and have a high recognition rate.

关键词： intelligent wheelchair sEMG HMI AR model BP artificial neural network

Effect of the grain boundary character distribution on the sulfur corrosion behaviour and mechanisms of copper windings under different high temperatures

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High Voltage 2024年第3期9卷 566-580页

作者： Xu dai yuan yuan Jiang Zhou Guoyong Liu Tao Zhu Huiying Xiang Qi Yu Xue Gao Ruijin Liao State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqingChina College of Materials Science and Engineering Chongqing UniversityChongqingChina Dongfang Electric Machinery Co. LtdDeyangChina

As a typical failure phenomenon in transformers,sulfur corrosion has garnered significant attention in the field of high-voltage *** boundary character distribution(GBCD)copper windings have been introduced to enhance sulfur corrosion resistance by slowing down intergranular *** this study,the sulfur corrosion behaviour and mechanisms of the GBCD copper windings under various temperatures were experi-mentally and theoretically *** show that GBCD can enhance the corrosion resistance of copper in liquid *** the increase in temperatures,the insulating properties of oil and papers in traditional copper windings experience notable degradation,while GBCD copper windings show more stable insulating *** addition,modelling of grain boundary energy indicates that the grain boundary structure of GBCD copper windings has a lower average interface energy of 0.170 eV/Å***-culations of reaction thermodynamics show that GBCD copper windings possess a higher failure temperature(135.2℃)and inhibition degree(activation energy)of the sulfur corrosion(32,557.62 J/mol),revealing the stability and enhanced sulfur corrosion resis-tance at elevated temperatures.

关键词： corrosion grain copper

A Simple and Efficient Algorithm to Identify the Chirality of Polymer Knots Based on the Alexander Polynomial

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Chinese Journal of Polymer Science 2024年第12期42卷 2030-2037,I0012页

作者： Qi-yuan Qiu Yong-Jian Zhu Zhong-Tao Wu Liang dai Department of Physics City University of Hong KongHong Kong999077China Shenzhen Research Institute City University of Hong KongShenzhen518057China Department of Mathematics The Chinese University of Hong KongHong Kong999077China

Recent experimental observations of knotting in DNA and proteins have stimulated the simulation studies of polymer *** studies usually identify knots in polymer conformations through the calculation of the Alexander ***,the Alexander polynomial cannot directly discriminate knot chirality,while knot chirality plays important roles in many physical,chemical,and biological *** this work,we discover a new relationship for knot chirality and accordingly,develop a new algorithm to extend the applicability of the Alexander polynomial to the identification of knot *** algorithm adds an extra step in the ordinary calculation of the Alexander *** extra step only slightly increases the computational *** correctness of our algorithm has been proved mathematically by *** implication of this algorithm in physical research has been demonstrated by our studies of the tube model for polymer *** this algorithm,we would be unable to obtain the tubes for polymer knots.

关键词： Polymerentanglement Polymer knot Polymerconformation Tubemodel Monte Carlo simulation