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Biomechanical behaviors of dragonfly wing:relationship between configuration and deformation

Chinese Physics B 2012年第3期21卷 294-303页

作者：任淮辉王习术陈应龙李旭东 Department of Engineering Mechanics AMLTsinghua University

In this paper, the natural structures of a dragonfly wing, including the corrugation of the chordwise cross-section, the sandwich mierostructure veins, and the junctions between the vein and the membrane, have been investigated with experimental observations, and the morphological parameters of these structural features are measured. The experimental result indicates that the corrugated angle among the longitudinal veins ranges from 80° to 150°, and the sandwiched microstructure vein mainly consists of chitin and protein layers. Meanwhile, different finite element models, which include models I and I＊ for the planar forewings, models II and II＊ for the corrugated forewings, and a submodel with solid veins and membranes, are created to investigate the effects of these structural features on the natural frequency/modal, the dynamical behaviors of the flapping flight, and the deformation mechanism of the forewings. The numerical results indicate that the corrugated forewing has a more reasonable natural frequency/modal, and the first order up-down flapping frequency of the corrugated wing is closer to the experimental result （about 27.00 Hz）, which is significantly larger than that of the planar forewing （10.94 Hz）. For the dynamical responses, the corrugated forewing has a larger torsional angle than the planar forewing, but a lower flapping angle. In addition, the sandwich microstructure veins can induce larger amplitudes of torsion deformation, because of the decreasing stiffness of the whole forewing. For the submodel of the forewing, the average stress of the chitin layer is much larger than that of the protein layer in the longitudinal veins. These simulative methods assist us to explain the flapping flight mechanism of the dragonfly and to design a micro aerial vehicle by automatically adjusting the corrugated behavior of the wing.

关键词： aerodynamics corrugation warping deformation finite element analysis

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A computational framework for Karl Popper's logic of scientific discovery

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Science China(Information Sciences) 2018年第4期61卷 97-106页

作者： Wei LI Yuefei SUI State key Laboratory of Software Development Environment Beihang University key Laboratory of Intelligent Information Processing Institute of Computing TechnologyChinese Academy of Sciences

Belief revision is both a philosophical and logical problem. From Popper’s logic of scientific discovery, we know that revision is ubiquitous in physics and other sciences. The AGM postulates and Rcalculus are approaches from logic, where the R-calculus is a Gentzen-type concrete belief revision *** deduction is undecidable in first-order logic, we apply approximate deduction to derive an R-calculus that is computational and has finite injury. We further develop approximation algorithms for SAT problems to derive a feasible R-calculus based on the relation between deduction and satisfiability. In this manner, we provide a full spectrum of belief revision: from philosophical to feasible revision.

关键词： belief revision logic of scientific discovery approximate deduction approximation algorithms feasible computation

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Diode Laser Optically Injected by Resonance of a Monolithic Cavity

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Chinese Physics Letters 2011年第11期28卷 128-130页

作者： PENG Yu ZHAO Yang LI Ye YANG Tao CAO Jian-Ping FANG Zhan-Jun ZANG Er-Jun Center of Time and Frequency Metrology National Institute of Metrology18 Beisanhuan East Rd.Beijing 100013 Department of Precision Instruments and Mechanology Tsinghua UniversityBeijing 100084

We demonstrate a self-injection locking extended cavity diode laser(ECDL)using resonant optical feedback from the p-polarization of a monolithic folded Fabry–Perot parallel cavity(MFC).The full width at half maximum of the MFC resonance is 31 *** the help of a narrow-linewidth reference laser,the linewidth of the ECDL is measured to be about 7 *** frequency of the laser could be tuned at 160MHz with an amplitude of 40V by a PZT mounted on the monolithic cavity and the voltage tuning coefficient is about 4 MHz/V.

关键词： polarization tuning Optically

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Terahertz Direct Detection Characteristics of a Superconducting NbN Bolometer

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Chinese Physics Letters 2011年第1期28卷 50-53页

作者： REN Yuan MIAO Wei YAO Qi-Jun ZHANG Wen SHI Sheng-Cai Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 Graduate School of the Chinese Academy of Sciences Beijing 100049

We report the terahertz direct detection characteristics of a spiral antenna coupled NbN superconducting hot- electron bolometer （HEB） at a bath temperature of 4.2K. Thermal conductance determined from resistance transition curves with different bias currents is found to be 3 × 10 7 W/K. The device shows a read-out circuit limited noise equivalent power （NEP） of 4.5 × 10-12 W/Hz/2 at 4.2 K with a home-made transimpedance amplifier operating at room temperature.

关键词： Superconductivity Instrumentation and measurement

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SOCIAL LEARNING WITH TIME-VARYING WEIGHTS

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Journal of Systems Science & Complexity 2014年第3期27卷 581-593页

作者： LIU Qipeng FANG Aili WANG Lin WANG Xiaofan Department of Automation Shanghai Jiao Tong Universityand Key Laboratory of System Control and Information ProcessingMinistry of Education of China

This paper investigates a non-Bayesian social learning model, in which each individual updates her beliefs based on private signals as well as her neighbors＇ beliefs. The private signM is involved in the updating process through Bayes＇ rule, and the neighbors＇ beliefs are embodied in through a weighted average form, where the weights are time-varying. The authors prove that agents eventually have correct forecasts for upcoming signals, and all the beliefs of agents reach a consensus. In addition, if there exists no state that is observationally equivalent to the true state from the point of view of all agents, the authors show that the consensus belief of the whole group eventually reflects the true state.

关键词： Consensus social learning social networks time-varying weights.

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Experiments on trapping ytterbium atoms in optical lattices

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Chinese Physics B 2013年第10期22卷 262-266页

作者：周敏陈宁张晓航黄良玉姚茂飞田洁高琪蒋海灵唐海瑶徐信业 State key Laboratory of Precision Spectroscopy and Department of Physics East China Normal University

Experiments on trapping ytterbium atoms in various optical lattices are presented. After the two-stage cooling, first in a blue magneto-optical trap and then in a green magneto-optical trap, the ultracold 171 Yb atoms are successfully loaded into one-, two-, and three-dimensional optical lattices operating at the Stark-free wavelength, respectively. The temperature, number, and lifetime of cold 171 Yb atoms in one-dimensional lattice are measured. After optimization, the one-dimensional lattice with cold 171Yb atoms is used for developing an ytterbium optical clock.

关键词： laser cooling and trapping optical lattices ytterbium atoms atomic optical clocks

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Multi-target pursuit formation of multi-agent systems

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Chinese Physics B 2011年第1期20卷 698-707页

作者：闫敬关新平罗小元 Institute of Electrical Engineering Yanshan University School of Electronic and Electric Engineering Shanghai Jiaotong University

The main goal of this paper is to design a team of agents that can accomplish multi-target pursuit formation using a developed leader-follower strategy. It is supposed that every target can accept a certain number of agents. First, each agent can automatically choose its target based on the distance from the agent to the target and the number of agents accepted by the target. In view of the fact that all agents are randomly dispersed in the workplace at the initial time, we present a numbering strategy for them. During the movement of agents, not every agent can always obtain pertinent state information about the targets. So, a developed leader-follower strategy and a pursuit formation algorithm are proposed. Under the proposed method, agents with the same target can maintain a circle formation. Furthermore, it turns out that the pursuit formation algorithm for agents to the desired formation is convergent. Simulation studies are provided to illustrate the effectiveness of the proposed method.

关键词： multi-agent systems pursuit formation leader-follower

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Influence of the environmental noise on determining the period of a torsion pendulum

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Chinese Physics B 2015年第3期24卷 72-77页

作者：罗杰田苑邵成刚王典洪 Faculty of Mechanical and Electronic Information China University of Geosciences School of Physics Huazhong University of Science and Technology

The environmental noise can restrict the accuracy of period estimation since the torsion pendulum is sensitive to weak forces. Two typical models for the environmental noise are proposed to make an evaluation. Generally, the stationary environmental noise is modeled as a white noise, and contributes to the period uncertainty as a function of the initial amplitude, the quality factor, the variance of noise and the time length. As to a sudden sharp disturbance acting on the pendulum, a narrow impulse model is constructed. It results in a sharp jump in the phase difference, which can be excluded with the 3σ criterion for a correction. An experimental data analysis for the measurement of the gravitational constant G with the time-of-swing method shows that the period uncertainty due to the environmental noise is about one and a half times the fundamental thermal noise limit. Though this result is dependent on the ambient environment, the analysis is instructive to improve the measurement accuracy of experiments.

关键词： period estimation environmental noise thermal noise limit uncertainty

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Quantum proxy signature scheme with public verifiability

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Science China(Physics,Mechanics & Astronomy) 2011年第10期54卷 1828-1832页

作者： ZHOU JingXian ZHOU YaJian NIU XinXin YANG YiXian key Laboratory of Network and Information Attack & Defence Technology of MOE Beijing University of Posts and Telecommunications Beijing 100876 China

In recent years, with the development of quantum cryptography, quantum signature has also made great achievement. However,the effectiveness of all the quantum signature schemes reported in the literature can only be verified by a designated ***, its wide applications are limited. For solving this problem, a new quantum proxy signature scheme using EPR quantumentanglement state and unitary transformation to generate proxy signature is presented. Proxy signer announces his public key whenhe generates the final signature. According to the property of unitary transformation and quantum one-way function, everyone canverify whether the signature is effective or not by the public key. So the quantum proxy signature scheme in our paper can be publicverified. The quantum key distribution and one-time pad encryption algorithm guarantee the unconditional security of this *** results show that this new scheme satisfies strong non-counterfeit and strong non-disavowal.

关键词： quantum cryptography proxy signature quantum one-way function public verifiably

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Polarisation-sensitive four-wave mixing and soliton self-frequency shift effect in the highly birefringent photonic crystal fibre

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Chinese Physics B 2010年第7期19卷 344-349页

作者：苑金辉桑新柱余重秀忻向军李曙光周桂耀侯蓝田 key Laboratory of Information Photonics and Optical Communications Ministry of EducationInstitute of Optical Communication and OptoelectronicsBeijing University of Posts and Telecommunications Institute of Infrared Optical Fibers and Sensors College of Information Science and EngineeringYanshan University

By adjusting the polarisation state of the pump at 805 nm parallel to slow （x） and fast （y） axes of the highly birefringent photonic crystal fibre with zero dispersion wavelengths 790 nm and 750 nm, this paper demonstrates the efficient polarisation-sensitive four wave mixing involved in pump, anti-Stokes and Stokes signals and soliton self- frequency shift effects induced by the phase-matching between red-shifted solitons and blue-shifted dispersive waves. If the reduction of coupling efficiency to the circular pump laser mode or other circular fibres due to asymmetry of the core is neglected, more than 98% of the total input power is kept in a single linear polarisation. Controlled dispersion characteristic of the doublet of fundamental guided-modes results in achieving light field strongly confined in principal axes of photonic crystal fibre, and enhancing the corresponding nonlinear-optical process through the remarkable nonlinear birefringence.

关键词： highly birefringent photonic crystal fibre four wave mixing soliton self-frequency shift phase-matching

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