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Value Iteration-Based Cooperative Adaptive Optimal Control for Multi-Player Differential Games With Incomplete Information

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 690-697页

作者： Yun zhang Lulu zhang Yunze cai the Department of Automation Shanghai Jiao Tong UniversityShanghai 200240 the Key Laboratory of System Control and Information Processing Ministry of Education of ChinaShanghai 200240China

This paper presents a novel cooperative value iteration(VI)-based adaptive dynamic programming method for multi-player differential game models with a convergence *** players are divided into two groups in the learning process and adapt their policies *** method removes the dependence of admissible initial policies,which is one of the main drawbacks of the PI-based ***,this algorithm enables the players to adapt their control policies without full knowledge of others’ system parameters or control *** efficacy of our method is illustrated by three examples.

关键词： Adaptive dynamic programming incomplete information multi-player differential game value iteration

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Viscosity, heat conductivity, and Prandtl number effects in the Rayleigh-Taylor Instability

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Frontiers of physics 2016年第6期11卷 183-196页

作者： Feng Chen Ai-Guo Xu guang-cai zhang School of Aeronautics Shah Dong Jiaotong University Jinan 250357 China National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P.O. Box 8009-26 Beijing 100088 China Center for Applied Physics and Technology MOE Key center for High Energy Density Physics Simulations College of Engineering Peking University Beijing 100871 China

The two-dimensional Rayleigh-Taylor instability problem is simulated with a multiple-relaxation-time discrete Boltzmann model with a gravity term. Viscosity, heat conductivity, and Prandtl number effects are probed from macroscopic and nonequilibrium viewpoints. In the macro sense, both viscosity and heat conduction show a significant inhibitory effect in the reacceleration stage, which is mainly achieved by inhibiting the development of the Kelvin-Helmholtz instability. Before this, the Prandtl number effect is not sensitive. Viscosity, heat conductivity, and Prandtl number effects on nonequilibrium manifestations and the degree of correlation between the nonuniformity and the nonequilibrium strength in the complex flow are systematically investigated.

关键词： discrete Boltzmann model/method multiple-relaxation-time Rayleigh-Taylor instability nonequilibrium

Essential Players in Cooperative Games with Graph Communication Structure

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Journal of the Operations Research Society of China 2024年第1期12卷 93-108页

作者： guang zhang Jing-Yi Ge Business School University of Shanghai for Science and TechnologyShanghai200093China

A class of cooperative games with graph communication structure is studied in this paper by considering some important players,namely essential *** the assumption that only connected coalitions containing essential players are able to cooperate and obtain their worths,the class of graph games with essential players is proposed as well as an allocation *** proposed value follows the spirit of the Myerson value defined by applying the Shapley value on a modified *** properties,feasible component efficiency,the inessential component property,and fairness,are provided to fully characterize this value,where feasible component efficiency and fairness follows the same ideas of component efficiency and fairness for classical graph games,and the inessential component property says that the total payoffs of the players in a non-feasible component is ***,some computational aspects of the proposed value and comparisons with disjunctive permission value for games with permission structure are also studied,respectively.

关键词： Cooperative game Graph structure Essential player Myerson value Computation Permission structure

Conduction-convection coupled heat transfer around a hollow cylinder under different buoyancy forces

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Chinese Journal of Aeronautics 2024年第4期37卷 216-228页

作者： Wanyu zhang Jingyi WU guang YANG Institute of Refrigeration and Cryogenics Shanghai Jiao Tong UniversityShanghai 200240China

In order to clarify the effect of a buoyancy force on conduction–convection coupled heat transfer in a hollow cylinder, the flow and thermal characteristics were analyzed using an RNG k-ε turbulence model. The Reynolds number was fixed at 1.014 × 10^(6), and the Rayleigh number varied from 1.122 × 10^(10)to 1.088 × 10^(11). Results have shown that, when considering the effect of an opposed buoyancy force, increasing the Rayleigh number has a positive impact on the rate of change and uniformity of the cylinder temperature. The temperature distributions along the axial and circumferential directions are similar for different Rayleigh numbers, but extreme values *** the axial direction, the maximum temperature is obtained at the interface between the variable-diameter part and the constant-diameter part. The maximum dimensionless temperature value decreases to 0.12 when the Rayleigh number increases to 1.088 × 10^(11). Along the circumferential direction, the temperature distribution is affected by the buoyancy force, which results in the temperature of the upper part being higher than that of the lower part. After nondimensionalization of the temperature and time, a correlation was proposed to illustrate the transient heat transfer process quantitatively. The standard deviation of the maximum relative temperature, representing the temperature uniformity, was also calculated. It was found that the difference in the direction of the buoyancy force made a huge difference. Compared with the opposed buoyancy force, the maximum dimensionless temperature is almost two times higher with an assisted buoyancy force. Similarly, the heat transfer coefficient with an assisted buoyancy force is half of that with an opposed buoyancy force. Overall, an assisted buoyancy force plays a negative role in terms of thermal characteristics. The flow field around the hollow cylinder was also illustrated to reveal the mechanism of the buoyancy force on magnitude and direction aspects

关键词： Buoyancy Conduction-convection heat transfer Transient analysis Hollow cylinder Non-dimensionalization

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Segment-wise learning control for trajectory tracking of robot manipulators under iteration-dependent periods

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Science China(Information Sciences) 2024年第3期67卷 155-166页

作者： Fan zhang Deyuan MENG Kaiquan cai The Seventh Research Division Beihang University School of Automation Science and Electrical Engineering Beihang University School of Electronics and Information Engineering Beihang University

This paper is concerned with the amplitude boundedness problem of adaptive iterative learning control(AILC) for robot manipulators operating with iteration-dependent periods. By introducing virtual memory slots for storing historical data, a practical AILC method is proposed to achieve the segmentwise learning. This method requires less memory storage for historical information of previous iterations,especially in comparison with that of the conventional AILC methods using point-wise learning *** is shown that not only the energy boundedness but also the amplitude boundedness of estimates and inputs of practical AILC can be guaranteed. Moreover, the practical AILC method can achieve the perfect tracking objective regardless of iteration-dependent periods when the robot manipulators have a persistent full learning property. In addition, a solution to the visual manipulator platform is provided and deployed based on Coppeliasim and Matlab, which helps to show the amplitude boundedness of learning results and the perfect tracking performances of the proposed practical AILC method for robot manipulators.

关键词： amplitude boundedness iteration-dependent period iterative learning control robot manipulator segment-wise virtual memory slot

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Reveal the lost entanglement for accelerated atoms in the high-dimensional spacetime

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Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 48-57页

作者： Jiatong Yan Baocheng zhang Qingyu cai School of Mathematics and Physics China University of GeosciencesWuhan 430074China Physics Department Brown UniversityProvidenceRhode Island 02912USA Center for Theoretical Physics Hainan UniversityHaikou 570228China School of Information and Communication Engineering Hainan UniversityHaikou 570228China Peng Huanwu Center for Fundamental Theory Hefei 230026China

When atoms are accelerated in the vacuum,entanglement among atoms will degrade compared with the initial situation before the *** this study,we propose a novel and interesting view that the lost entanglement can be recovered completely when the high-dimensional spacetime is exploited,in the case that the acceleration is not too large,since the entanglement loss rate caused by the large acceleration is faster than the recovery *** also calculate the entanglement change caused by the anti-Unruh effect and found that the lost entanglement could just be recovered part by the anti-Unruh effect,and the anti-Unruh effect could only appear for a finite range of acceleration when the interaction time scale is approximately shorter than the reciprocal of the energy gap in two dimensional *** limit case of zero acceleration is also investigated,which gives an analytical interpretation for the increase or recovery of entanglement.

关键词： entanglement acceleration high-dimensional spacetime

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Two-dimensional Multiple-Relaxation-Time Lattice Boltzmann model for compressible and incompressible flows

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Frontiers of physics 2014年第2期9卷 246-254页

作者： Feng Chen Ai-Guo Xu guang-cai zhang Yong-Long Wang School of Aeronautics Shan Dong Jiaotong University Jinan 250357 China . .. National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P. O. Box 8009-26 Beijing 100088 China Institute of Condensed Matter Physics School of Science Linyi University Linyi 276005 China

In the paper we extend the Multiple-Relaxation-Time （MRT） Lattice Boltzmann （LB） model pro- posed in [Europhys. Lctt., 2010, 90： 54003] so that it is suitable also for incompressible flows. To decrease tile artificial oscillations, the convection term is discretized by the flux linfiter scheme with splitting technique. A new model is validated by some well-known benchmark tests, including Rie- mann problem and Couette flow, and satisfying agreements are obtained between the sinmlation results and *** ones. In order to show the merit of LB model over traditional methods, the non-equilibrium characteristics of system are solved. The simulation results are consistent with the physical analysis.

关键词： lattice Boltzmann method multiple-relaxation-time flux limiter technique Prandtlnumbers effect non-equilibrium characteristic

Physical modeling of multiphase flow via lattice Boltzmann method： Numerical effects, equation of state and boundary conditions

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Frontiers of physics 2012年第4期7卷 481-490页

作者： Yan-Biao Gan Ai-Guo Xu guang-cai zhang Ying-Jun Li North China Institute of Aerospace Engineering Langfang 065000 China National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P. O. Box 8009-26 Beijing 100088 China State Key Laboratory for GeoMechanics and Deep Underground Engineering SMCEChina University of Mining and Technology (Beijing) Beijing 100083 China

The aims of the present paper are threefold. First, we further study the fast Fourier transform thermal lattice Boltzmann （FFT-TLB） model for van der Waals （VDW） fluids proposed in Phys. Rev. E, 2011, 84（4）： 046715. We analyze the merits of the FFT approach over the traditional finite difference scheme and investigate the effects of smoothing factors on accuracy and stability in detail. Second, we incorporate the VDW equation of state with flexible parameters into the FFT- TLB model. As a result, the revised model may be used to handle multiphase flows with various critical densities and temperatures. Third, we design appropriate boundary conditions for systems with solid walls. These improvements, from the views of numerics and physics, significantly extend the application scope of the model in science and engineering.

关键词： van der Waals fluids lattice Boltzmann method FFT equation of state

Discrete Boltzmann model for implosion- and explosion- related compressible flow with spherical symmetry

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Frontiers of physics 2018年第5期13卷 31-44页

作者： Ai-Guo Xu guang-cai zhang Yu-Dong zhang Pei Wang Yang-Jun Ying National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P.O. Box 8009-26 Beijing 100088 China Center for Applied Physics and Technology MOE Key Center for High Energy Density Physics Simulations College of Engineering Peking University Beijing 100871 China Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing 210094 China

To kinetically model implosion- and explosion-related phenomena, we present a theoretical framework for constructing a discrete Boltzmann model （DBM） with spherical symmetry in spherical coordinates. To achieve this goal, a key technique is to use local Cartesian coordinates to describe the particle velocity in the kinetic model. Therefore, geometric effects, such as divergence and convergence, are described as a ＂force term＂. To better access the nonequilibrium behavior, even though the corre- sponding hydrodynamic model is one-dimensional, the DBM uses a discrete velocity model （DVM） with three dimensions. A new scheme is introduced so that the DBM can use the same DVM regard- less of whether or not there are extra degrees of freedom. As an example, a DVM with 26 velocities is formulated to construct the DBM at the Navier-Stokes level. Via the DBM, one can study simulta- neously the hydrodynamic and thermodynamic nonequilibrium behaviors in implosion and explosion processes that are not very close to the spherical center. The extension of the current model to a multiple-relaxation-time version is straightforward.

关键词： discrete Boltzmann model compressible flows spherical symmetry geometric effects thermodynamic nonequilibrium