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Generation of Broadband High Harmonics through Linear Mode Conversion in Inhomogeneous Plasmas

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Chinese Physics Letters 2010年第4期27卷 178-181页

作者：徐慧盛政明郑君夏云杰 Shandong Provincial Key Laboratory of Laser Polarization and Information Technology Department of Physics Qufu Normal University Qufu 273165 Department of Physics Shanghai Jiaotong University Shanghai 200240 Beijing national Laboratory for Condensed Matters Institute of Physics Chinese Academy of Sciences Beijing 100080

The generation of high order harmonics from an inhomogeneous ovderdense plasma target irradiated by an ultrashort intense laser pulse is studied by numerical simulation. During such interaction, ultrafast electron bunches are generated and excite electron plasma oscillations as they pass through the overdense target. These plasma oscillations will emit high-frequency electromagnetic emission by linear mode conversion. Instead of the integer harmonies generation, the emission appears with a broadband and even continuous spectrum corresponding to the electron plasma frequency range of the inhomogeneous plasma density.

关键词： Plasma physics

Instability and Death of Spiral Wave in a Two-Dimensional Array of Hindmarsh-Rose Neurons

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Communications in Theoretical Physics 2010年第2期53卷 382-388页

作者：王春妮马军唐军李延龙 School of science Lanzhou University of Technology Department of Physics Central China Normal University College of science China University of Mining and Technology

Spiral wave could be observed in the excitable media, the neurons are often excitable within appropriateparameters. The appearance and formation of spiral wave in the cardiac tissue is linked to monomorphic ventriculartachycardia that can denervate into polymorphic tachycardia and ventricular fibrillation. The neuronal system oftenconsists of a large number of neurons with complex connections. In this paper, we theoretically study the transitionfrom spiral wave to spiral turbulence and homogeneous state (death of spiral wave) in two-dimensional array of theHindmarsh-Rose neuron with completely nearest-neighbor connections. In our numerical studies, a stable rotating spiralwave is developed and selected as the initial state, then the bifurcation parameters are changed to different values toobserve the transition from spiral wave to homogeneous state, breakup of spiral wave and weak change of spiral wave,respectively. A statistical factor of synchronization is defined with the mean field theory to analyze the transition fromspiral wave to other spatial states, and the snapshots of the membrane potentials of all neurons and time series of meanmembrane potentials of all neurons are also plotted to discuss the change of spiral wave. It is found that the sharpchanging points in the curve for factor of synchronization vs. bifurcation parameter indicate sudden transition fromspiral wave to other states. And the results are independent of the number of neurons we used.

关键词： spiral wave: factor of synchronization Hindmarsh-Rose neurons bifurcation

PARALLEL SIMULTANEOUS STABILIZATION OF A SET OF PORT-CONTROLLED HAMILTONIAN SYSTEMS SUBJECT TO ACTUATOR SATURATION

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Journal of Systems science & Complexity 2011年第1期24卷 120-139页

作者： Airong WEI Yuzhen WANG Xiaoming HU School of Control science and Engineering Shandong University Jinan 250061 ChinaOptimization and Systems Theory Royal Institute of Technology SE-10044 Stockholm Sweden School of Control science and Engineering Shandong University Jinan 250061 China Optimization and Systems Theory Royal Institute of Technology SE-100 44 Stockholm Sweden ACCESS Linnaeus Center Royal Institute of Technology SE-100 44 Stockholm Sweden

This paper investigates parallel simultaneous stabilization （PSS） of a set of multi-input nonlinear Port-Controlled Hamiltonian （PCH） systems subject to actuator saturation （AS）, and proposes a number of results on the design of PSS controllers for the PCH systems with AS. Firstly, the case of two PCH systems with AS is studied. Exploring the special property of the saturation nonlinearity and the structural properties of dissipative Hamiltonian system, the two systems are combined to generate an augmented PCH system, with which some results on the control design are then obtained. When there are external disturbances in the two systems, a robust PSS controller is designed for the systems. Secondly, the case of more than two PCH systems with AS is investigated, and several new results are proposed for the PSS problem. Finally, two illustrative examples are presented to show that the stabilization controllers obtained in this paper work very well.

关键词： Actuator saturation PCH system robust parallel simultaneous stabilization

The Stability of Schrdinger Equation with Boundary Control Matched Disturbance

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Journal of Systems science & Complexity 2017年第6期30卷 1258-1269页

作者： ZHANG Xiaoying CHAI Shugen School of Mathematical sciences Shanxi University Department of Mathematics Shanxi Agriculture University

This paper studies the stability of Schr¨odinger equation with boundary control matched disturbance. The time-varying gain extended state observer is utilized to estimate disturbance and state. Meanwhile, the authors get a continuous controller by the active disturbance rejection control strategy, which shows that the closed-loop system of Schr¨odinger equation is asymptotically *** results are illustrated by simulation examples.

关键词： Active disturbance rejection control extended state observer SchrSdinger equation stability.

Attribute-Based Signature with Policy-and-Endorsement Mechanism

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Journal of Computer science & Technology 2010年第6期25卷 1293-1304页

作者：王怀习朱岩冯荣权 Stephen S.Yau LMAM School of Mathematical SciencesPeking University Electronic Engineering Institute Institute of Computer science and Technology Peking University Key Laboratory of Network and Software Security Assurance (Peking University) Ministry of Education Information Assurance Center and School of Computing Informatics and Decision Systems Engineering Arizona State University

In this paper a new signature scheme,called Policy-Endorsing Attribute-Based Signature,is developed to correspond with the existing Ciphertext-Policy Attribute-Based *** signature provides a policy-and-endorsement *** this mechanism a single user,whose attributes satisfy the predicate,endorses the *** signature allows the signer to announce his endorsement using an access policy without having to reveal the identity of the *** security of this signature,selfless anonymity and existential unforgeability,is based on the Strong Diffie-Hellman assumption and the Decision Linear assumption in bilinear map groups.

关键词： cryptography fine-grained access control attribute-based signature policy-and-endorsement selfless anonymity existential unforgeability

Formation Mechanisms and Geomorphic Evolution of the Erlian Mudflow Fans, Eastern Guide Basin of the Upper Reaches of Yellow River

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Acta Geologica Sinica(English Edition) 2016年第2期90卷 578-589页

作者： ZHAO Wuji YIN Zhiqiang XU Qiang QIN Xiaoguang School of the Earth sciences and Resources China University of Geosciences Beijing 100083 China China Institute of Geo-environment Monitoring Beijing 100081 China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology Chengdu 610059 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

Several argillaceous platforms lie along the Yellow River（YR） of the eastern Guide Basin, northeastern Tibetan Plateau, and their compositions, formation processes, and geomorphic evolution remain debated. Using field survey data, sample testing, and high-resolution remote sensing images, the evolution of the Erlian mudflow fans are analyzed. The data show significant differences between fans on either side of the YR. On the right bank, fans are dilute debris flows consisting of sand and gravel. On the left bank, fans are viscosity mudflows consisting of red clay. The composition and formation processes of the left bank platforms indicate a rainfall-induced pluvial landscape. Fan evolution can be divided into two stages： early-stage fans pre-date 16 ka B.P., and formed during the last deglaciation; late-stage fans post-date 8 ka B.P.. Both stages were induced by climate change. The data indicate that during the Last Glacial Maximum, the northeastern Tibetan Plateau experienced a cold and humid climate characterized by high rainfall. From 16–8 ka, the YR cut through the Erlian early mudflow fan, resulting in extensive erosion. Since 8 ka, the river channel has migrated south by at least 1.25 km, and late stage mudflow fan formation has occurred.

关键词： the upper reaches of Yellow River Guide Basin mud-flow fan forming mechanism geomorphic evolution

Intermediate Energy Reactions Versus Heavy-Ion Fusion: Light Particle Emission and Post-Saddle Friction in the Presence of Deformation Effects

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Communications in Theoretical Physics 2019年第6期71卷 697-701页

作者： Na Chen Wei Ye School of Applied Mathematics Nanjing University of Finance&EconomicsNanjing210023China Department of Physics Southeast UniversityNanjing210096China

A decaying nucleus undergoes a change in deformation when it fissions. This affects the particle emission in the fission process. Using the dynamical Langevin model, we investigate the role of deformation in the sensitivity of post-saddle neutrons and light charged particles(LCPs) to the post-saddle friction strength(β) for heavy nuclei240 Am produced with different initial conditions:(i) a low excitation energy E*and a large spin ?(provided via a fusion mechanism) and(ii) a high E*and a large ? as well as a higher E*but a small ?(provided in peripheral and near-central intermediate energy heavy-ion reactions, respectively). It is shown that deformation obviously enhances the sensitivity of post-saddle neutrons to β at intermediate-energy peripheral collisions and that for case(i), the drop of LCPs emission due to deformation makes post-saddle LCPs to be almost insensitive to β, but for case(ii) LCPs still have a significant change with β. Furthermore, we find that post-saddle LCPs display a greater sensitivity to β for near-central collisions than for peripheral collisions. These results suggest that given the deformation effects, to better probe post-saddle dissipation properties with neutrons(LCPs) in experiments, it is best to choose those excited heavy nuclear systems populated in peripheral(near-central) collisions at intermediate energies.

关键词： post-saddle friction deformation excitation energy light particles stochastic model

THE MAXIMUM PRINCIPLE FOR PARTIALLY OBSERVED OPTIMAL CONTROL OF FORWARD-BACKWARD STOCHASTIC SYSTEMS WITH RANDOM JUMPS

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Journal of Systems science & Complexity 2011年第6期24卷 1083-1099页

作者： Hua XIAO School of Mathematics and Statistics Shandong University at Weihai Weihai 264209 China School of Mathematics Shandong University Jinan 250100 China

This paper studies the problem of partially observed optimal control for forward-backward stochastic systems which are driven both by Brownian motions and an independent Poisson random measure. Combining forward-backward stochastic differential equation theory with certain classical convex variational techniques, the necessary maximum principle is proved for the partially observed optimal control, where the control domain is a nonempty convex set. under certain convexity assumptions, the author also gives the sufficient conditions of an optimal control for the aforementioned optimal optimal problem. To illustrate the theoretical result, the author also works out an example of partial information linear-quadratic optimal control, and finds an explicit expression of the corresponding optimal control by applying the necessary and sufficient maximum principle.

关键词： Forward-backward stochastic differential equations maximum principle partially observed optimal control random jumps.

Residual Based A Posteriori Error Estimates for Convex Optimal Control Problems Governed by Stokes-Darcy Equations

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Numerical Mathematics(Theory,Methods and Applications) 2012年第4期5卷 602-634页

作者： Ming Cui Ningning Yan Schools of Mathematics Shandong UniversityJinan 250100China LASG Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China LSEC Institute of Systems ScienceAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China

In this paper,we derive a posteriori error estimates for finite element approximations of the optimal control problems governed by the Stokes-Darcy *** obtain a posteriori error estimators for both the state and the control based on the residual of the finite element *** is proved that the a posteriori error estimate provided in this paper is both reliable and efficient.

关键词： Optimal control Stokes-Darcy equations a posteriori error estimate