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Sampled-data Observer Design for a Class of Stochastic Nonlinear Systems Based on the Approximate Discrete-time Models 被引量:2
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作者 Xinxin Fu Yu Kang Pengfei Li 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2017年第3期507-511,共5页
In this paper,we studied the approximate sampleddata observer design for a class of stochastic nonlinear systems.Euler-Maruyama approximation was investigated in this paper because it is the basis of other higher prec... In this paper,we studied the approximate sampleddata observer design for a class of stochastic nonlinear systems.Euler-Maruyama approximation was investigated in this paper because it is the basis of other higher precision numerical methods,and it preserves important structures of the nonlinear systems.Also,the form of Euler-Maruyama model is simple and easy to be calculated.The results provide a reference for sampled-data observer design method for such stochastic nonlinear systems,and may be useful to many practical control applications,such as tracking control in mechanical systems.And the effectiveness of the approach is demonstrated by a simulation example. 展开更多
关键词 Approximation model exponentially bounded sampled-data observer stochastic nonlinear
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A novel excitation controller using support vector machines and approximate models 被引量:1
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作者 Xiaofang YUAN Yaonan WANG Shutao LI 《控制理论与应用(英文版)》 EI 2008年第3期239-245,共7页
This paper proposes a novel excitation controller using support vector machines (SVM) and approximate models. The nonlinear control law is derived directly based on an input-output approximation method via Taylor ex... This paper proposes a novel excitation controller using support vector machines (SVM) and approximate models. The nonlinear control law is derived directly based on an input-output approximation method via Taylor expansion, which not only avoids complex control development and intensive computation, but also avoids online learning or adjustment. Only a general SVM modelling technique is involved in both model identification and controller implementation. The robustness of the stability is rigorously established using the Lyapunov method. Several simulations demonstrate the effectiveness of the proposed excitation controller. 展开更多
关键词 Support vector machines Nonlinear control approximate model Neural networks IDENTIFICATION
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A novel robust adaptive controller for EAF electrode regulator system based on approximate model method
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作者 李磊 毛志忠 《Journal of Central South University》 SCIE EI CAS 2012年第8期2158-2166,共9页
The electrode regulator system is a complex system with many variables, strong coupling and strong nonlinearity, while conventional control methods such as proportional integral derivative (PID) can not meet the req... The electrode regulator system is a complex system with many variables, strong coupling and strong nonlinearity, while conventional control methods such as proportional integral derivative (PID) can not meet the requirements. A robust adaptive neural network controller (RANNC) for electrode regulator system was proposed. Artificial neural networks were established to learn the system dynamics. The nonlinear control law was derived directly based on an input-output approximating method via the Taylor expansion, which avoids complex control development and intensive computation. The stability of the closed-loop system was established by the Lyapunov method. The current fluctuation relative percentage is less than ±8% and heating rate is up to 6.32 ℃/min when the proposed controller is used. The experiment results show that the proposed control scheme is better than inverse neural network controller (INNC) and PID controller (PIDC). 展开更多
关键词 approximate model electric arc furnaces nonlinear control normalized radial basis function neural network (NRBFNN)
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Assembly-oriented reliability analysis method for the top-connection structure of a nuclear fuel assembly
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作者 Ying-Dong Liu Wen-Qiang Li +2 位作者 Jia-Hao Chen Si-Tong Ling Chang-Fu Wan 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2023年第6期155-170,共16页
The nuclear fuel assembly is the core component of a nuclear reactor.In a pressurized water reactor fuel assembly,the top-connection structure connects the top nozzle to the guide thimble.Its performance reliability i... The nuclear fuel assembly is the core component of a nuclear reactor.In a pressurized water reactor fuel assembly,the top-connection structure connects the top nozzle to the guide thimble.Its performance reliability is essential for the stability of the nuclear fuel assembly.In this study,an assembly-oriented reliability analysis method for top-connection structures is presented by establishing an assembly-oriented top-connection structure parameter modeling method and a nonlinear contact gap and penetration correction method.A reliability model of the top-connection assembly structure,including multiple stochastic design variables,was constructed,and the overall reliability of the top-connection assembly structure was obtained via a Kriging model and Monte Carlo simulation.The acquired experimental data were consistent with real-world failure conditions,which verified the practicability and feasibility of the reliability analysis method proposed in this study. 展开更多
关键词 ASSEMBLY Top-connection structure Parametric model Approximation model Structural reliability
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APPROXIMATION TECHNIQUES FOR APPLICATION OF GENETIC ALGORITHMS TO STRUCTURAL OPTIMIZATION 被引量:1
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作者 金海波 丁运亮 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2003年第2期147-154,共8页
Although the genetic algorithm (GA) has very powerful robustness and fitness, it needs a large size of population and a large number of iterations to reach the optimum result. Especially when GA is used in complex str... Although the genetic algorithm (GA) has very powerful robustness and fitness, it needs a large size of population and a large number of iterations to reach the optimum result. Especially when GA is used in complex structural optimization problems, if the structural reanalysis technique is not adopted, the more the number of finite element analysis (FEA) is, the more the consuming time is. In the conventional structural optimization the number of FEA can be reduced by the structural reanalysis technique based on the approximation techniques and sensitivity analysis. With these techniques, this paper provides a new approximation model-segment approximation model, adopted for the GA application. This segment approximation model can decrease the number of FEA and increase the convergence rate of GA. So it can apparently decrease the computation time of GA. Two examples demonstrate the availability of the new segment approximation model. 展开更多
关键词 approximation techniques segment approximation model genetic algorithms structural optimization sensitivity analysis
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EFFICIENT METHOD FOR MULTIDISCIPLINARY DESIGN OPTIMIZATION BY CONSIDERING UNCERTAINTY
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作者 贺谦 李元生 +2 位作者 敖良波 温志勋 岳珠峰 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2010年第3期213-218,共6页
A new reliability-based multidisciplinary design optimization (RBMDO) framework is proposed by combining the single-loop-based reliability analysis (SLBRA) method with multidisciplinary feasible (MDF) method. Th... A new reliability-based multidisciplinary design optimization (RBMDO) framework is proposed by combining the single-loop-based reliability analysis (SLBRA) method with multidisciplinary feasible (MDF) method. The Kriging approximate model with updating is introduced to reduce the computational cost of MDF caused by the complex structure. The computational efficiency is remarkably improved as the lack of iterative process during reliability analysis. Special attention is paid to a turbine blade design optimization by adopting the proposed method. Results show that the method is much more efficient than the commonly used double-loop based RBMDO method. It is feasible and efficient to apply the method to the engineering design. 展开更多
关键词 multidisciplinary design optimization multidisciplinary feasible method single loop method reliability analysis Kriging approximate model
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IMPROVED AERODYNAMIC APPROXIMATION MODEL WITH CASE-BASED REASONING TECHNIQUE FOR MDO OF AIRCRAFT
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作者 白振东 刘虎 +1 位作者 柴雪 武哲 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2008年第3期187-193,共7页
To increase the efficiency of the multidisciplinary optimization of aircraft, an aerodynamic approximation model is improved. Based on the study of aerodynamic approximation model constructed by the scaling correction... To increase the efficiency of the multidisciplinary optimization of aircraft, an aerodynamic approximation model is improved. Based on the study of aerodynamic approximation model constructed by the scaling correction model, case-based reasoning technique is introduced to improve the approximation model for optimization. The aircraft case model is constructed by utilizing the plane parameters related to aerodynamic characteristics as attributes of cases, and the formula of case retrieving is improved. Finally, the aerodynamic approximation model for optimization is improved by reusing the correction factors of the most similar aircraft to the current one. The multidisciplinary optimization of a civil aircraft concept is carried out with the improved aerodynamic approximation model. The results demonstrate that the precision and the efficiency of the optimization can be improved by utilizing the improved aerodynamic approximation model with ease-based reasoning technique. 展开更多
关键词 AIRCRAFT aerodynamic approximation model case-based reasoning multidisciplinary optimization(MDO)
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A structural topological optimization method for multi-displacement constraints and any initial topology configuration 被引量:9
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作者 J. H. Rong J. H. Yi 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第5期735-744,共10页
In density-based topological design, one expects that the final result consists of elements either black (solid material) or white (void), without any grey areas. Moreover, one also expects that the optimal topolo... In density-based topological design, one expects that the final result consists of elements either black (solid material) or white (void), without any grey areas. Moreover, one also expects that the optimal topology can be obtained by starting from any initial topology configuration. An improved structural topological optimization method for multidisplacement constraints is proposed in this paper. In the proposed method, the whole optimization process is divided into two optimization adjustment phases and a phase transferring step. Firstly, an optimization model is built to deal with the varied displacement limits, design space adjustments, and reasonable relations between the element stiffness matrix and mass and its element topology variable. Secondly, a procedure is proposed to solve the optimization problem formulated in the first optimization adjustment phase, by starting with a small design space and advancing to a larger deign space. The design space adjustments are automatic when the design domain needs expansions, in which the convergence of the proposed method will not be affected. The final topology obtained by the proposed procedure in the first optimization phase, can approach to the vicinity of the optimum topology. Then, a heuristic algorithm is given to improve the efficiency and make the designed structural topology black/white in both the phase transferring step and the second optimization adjustment phase. And the optimum topology can finally be obtained by the second phase optimization adjustments. Two examples are presented to show that the topologies obtained by the proposed method are of very good 0/1 design distribution property, and the computational efficiency is enhanced by reducing the element number of the design structural finite model during two optimization adjustment phases. And the examples also show that this method is robust and practicable. 展开更多
关键词 Topological optimization Displacement constraint Continuum structure Design space adjustment Rational approximation material model
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Monte Carlo simulation of in-plane spin-polarized transport in GaAs/GaAlAs quantum well in the three-subband approximation 被引量:2
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作者 孔令刚 刘晓彦 +3 位作者 杜刚 王漪 康晋锋 韩汝琦 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第3期654-658,共5页
We develop a Monte Carlo (MC) tool incorporated with the three-subband approximation model to investigate the in-plane spln-polarized transport in GaAs/GaAlAs quantum well. Using the tool, the effects of the electro... We develop a Monte Carlo (MC) tool incorporated with the three-subband approximation model to investigate the in-plane spln-polarized transport in GaAs/GaAlAs quantum well. Using the tool, the effects of the electron occupation of higher subbands and the intersuhband scattering on the spin dephasing have been studied. Compared with the corresponding results of the simple one-snbband approximation model, the spin dephasing length is reduced four times under 0.125 kV/cm of driving electric field at 300K by the MC tool incorporated with the three-subband approximation model, indicating that the three-subbarld approximation model predicts significantly shorter spin dephasing length with temperature increasing. Our simulation results suggest that the effects of the electron occupation of higher subbands and the intersubband scattering on the spln-dependent transport of GaAs 2-dhuensional electron gas need to be considered when the driving electric field exceeds the moderate value and the lattice temperature is above 100K. The simulation by using the MC tool incorporated with the three-subband approximation model also indicates that, under a eertain driving electric field and lattice temperature, larger channel widths cause spins to be depolarized faster. Ranges of the three components of the spins are different for three different injected spin polarizations due to the anisotropy of spin-orbit interaction. 展开更多
关键词 Monte Carlo spin dephasing spin-polarized transport three-subband approximation model
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Control synthesis for a class of nonlinear systems based on partition of unity 被引量:2
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作者 Dongfang HAN Yinhe WANG Siying ZHANG 《控制理论与应用(英文版)》 EI 2007年第2期145-151,共7页
A partition-of-unity-based approach is proposed to derive an approximate model for a class of nonlinear systems. The precision of the approximate model is analyzed by using the modulus of continuity of continuous func... A partition-of-unity-based approach is proposed to derive an approximate model for a class of nonlinear systems. The precision of the approximate model is analyzed by using the modulus of continuity of continuous functions. The system stability of the approximate model is analyzed by using Lyapunov stability theory. A design algorithm for constructing tracking controllers with tracking performance related to tracking error is given based on the approximate model and the partition of unity method. 展开更多
关键词 Partition of unity approximate model Modulus of continuity H∞ tracking controller
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A Comparison of Two Canopy Radiative Models in Land Surface Processes 被引量:1
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作者 戴秋丹 孙菽芬 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2007年第3期421-434,共14页
This paper compares the predictions by two radiative transfer models-the two-stream approximation model and the generalized layered model (developed by the authors) in land surface processes -for different canopies ... This paper compares the predictions by two radiative transfer models-the two-stream approximation model and the generalized layered model (developed by the authors) in land surface processes -for different canopies under direct or diffuse radiation conditions. The comparison indicates that there are significant differences between the two models, especially in the near infrared (NIR) band. Results of canopy reflectance from the two-stream model are larger than those from the generalized model. However, results of canopy absorptance from the two-stream model are larger in some cases and smaller in others compared to those from the generalized model, depending on the cases involved. In the visible (VIS) band, canopy reflectance is smaller and canopy absorptance larger from the two-stream model compared to the generalized model when the Leaf Area Index (LAI) is low and soil reflectance is high. In cases of canopies with vertical leaf angles, the differences of reflectance and absorptance in the VIS and NIR bands between the two models are especially large. Two commonly occurring cases, with which the two-stream model cannot deal accurately, are also investigated. One is for a canopy with different adaxial and abaxial leaf optical properties; and the other is for incident sky diffuse radiation with a non-uniform distribution. Comparison of the generalized model within the same canopy for both uniform and non-uniform incident diffuse radiation inputs shows smaller differences in general. However, there is a measurable difference between these radiation inputs for a canopy with high leaf angle. This indicates that the application of the two-stream model to a canopy with different adaxial and abaxial leaf optical properties will introduce non-negligible errors. 展开更多
关键词 generalized canopy radiative transfer model two-stream approximation model canopy reflectance canopy absorptance
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Optimal Matching Analysis of Net Buoyancy and Pitching Angle for Underwater Gliders 被引量:1
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作者 YANG Ming LIANG Yan +1 位作者 WANG Yan-hui YANG Shao-qiong 《China Ocean Engineering》 SCIE EI CSCD 2022年第5期697-706,共10页
Control parameter optimization is an efficient way to improve the endurance of underwater gliders(UGs),which influences their gliding efficiency and energy consumption.This paper analyzes the optimal matching between ... Control parameter optimization is an efficient way to improve the endurance of underwater gliders(UGs),which influences their gliding efficiency and energy consumption.This paper analyzes the optimal matching between the net buoyancy and the pitching angle and proposes a segmented control strategy of Petrel-L.The optimization of this strategy is established based on the gliding range model of UG,which is solved based on the approximate model,and the variations of the optimal control parameters with the hotel load are obtained.The optimization results indicate that the segmented control strategy can significantly increase the gliding range when the optimal matching between the net buoyancy and the pitching angle is reached,and the increase rate is influenced by the hotel load.The gliding range of the underwater glider can be increased by 10.47%at a hotel load of 0.5 W.The optimal matching analysis adopted in this study can be applied to other UGs to realize endurance improvement. 展开更多
关键词 optimal matching analysis underwater glider approximate model technology gliding range model
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Active control and experiment study of a flexible hub-beam system 被引量:1
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作者 Guoping Cai Youyou Teng C. W. Lira 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第2期289-298,共10页
The first-order approximation coupling (FOAC) model was proposed recently for dynamics and control of flexible hub-beam systems. This model may deal with system dynamics for both low and high rotation speed, while t... The first-order approximation coupling (FOAC) model was proposed recently for dynamics and control of flexible hub-beam systems. This model may deal with system dynamics for both low and high rotation speed, while the classical zeroth-order approximation coupling (ZOAC) model is only available for low rotation speed. This paper assumes the FOAC model to present experimental study of active positioning control of a flexible hub-beam system. Linearization and nonlinear control strategies are both considered. An experiment system based on a DSP TMS320F2812 board is introduced. The difference between linearization and nonlinear control strategies are studied both numerically and experimentally. Simulation and experimental results indicate that, linearized controller can make the system reach an expected position with suppressed vibration of flexible beam, but the time taken to position is longer than expected, whereas nonlinear controller works well with precise positioning, suppression of vibration and time control. 展开更多
关键词 Flexible hub-beam system First-order approximation coupling (FOAC) model Linearizationcontrol Nonlinear control Experiment
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θ-improved limited tolerance relation model of incomplete information system for evaluation of water conservancy project management modernization 被引量:4
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作者 Yu-qin GAO Guo-hua FANG Ya-qin LIU 《Water Science and Engineering》 EI CAS CSCD 2013年第4期469-477,共9页
The modernization of water conservancy project management is a complicated engineering system involving a management system, a management method, management personnel, the exertion of social, economic, and ecological ... The modernization of water conservancy project management is a complicated engineering system involving a management system, a management method, management personnel, the exertion of social, economic, and ecological effects, and so on. However, indices for evaluating the modernization of water conservancy project management are usually unobtainable in practical applications. Conducting appropriate extension of the classical rough set theory and then applying it to an incomplete information system are the key to the application of the rough set theory Based on analysis of some extended rough set models in incomplete information systems, a rough set model based on the θ-improved limited tolerance relation is put forward. At the same time, upper approximation and lower approximation are defined under this improved relation. According to the evaluation index system and management practices, the threshold for θ is defined. An example study indicates the practicability and maneuverability of the model. 展开更多
关键词 Key words: modernization of water conservancy project management O-improved limitedtolerance relation model upper and lower approximations threshold
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HIGH CYCLE FATIGUE RELIABILITY ANALYSIS ON ROTOR HUB BASED ON APPROXIMATION TECHNIQUE
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作者 姜年朝 倪俊 +3 位作者 周光明 张逊 戴勇 张志清 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2013年第4期335-342,共8页
A high cycle fatigue reliability analysis approach to helicopter rotor hub is proposed under working load spectrum. Automatic calculation for the approach is implemented through writing the calculating programs. In th... A high cycle fatigue reliability analysis approach to helicopter rotor hub is proposed under working load spectrum. Automatic calculation for the approach is implemented through writing the calculating programs. In the system, the modification of geometric model of rotor hub is controlled by several parameters, and finite element method and S-N curve method are then employed to solve the fatigue life by automatically assigned parameters. A database between assigned parameters and fatigue life is obtained via Latin Hypercube Sampling (LHS) on toler- ance zone of rotor hub. Different data-fitting technologies are used and compared to determine a highest-precision approximation for this database. The parameters are assumed to he independent of each other and follow normal distributions. Fatigue reliability is then computed by the Monte Carlo (MC) method and the mean-value first order second moment (MFOSM) method. Results show that the approach has high efficiency and precision, and is suit- able for engineering application. 展开更多
关键词 helicopters rotor hub PARAMETERIZATION high cycle fatigue RELIABILITY approximate model
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Production of projectile and target-vacancy in near-symmetric collisions of 60–100 MeV Cu^(9+) ions with thin Zn target
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作者 郭义盼 杨治虎 +3 位作者 杜树斌 常宏伟 夏清良 徐秋梅 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第3期169-173,共5页
We report studies on both target and projectile K-shell ionization by collisions of Cu9+ ions on the thin Zn target in the energy range of 60-100 MeV. In this work, the relative ratio for the production of the target... We report studies on both target and projectile K-shell ionization by collisions of Cu9+ ions on the thin Zn target in the energy range of 60-100 MeV. In this work, the relative ratio for the production of the target to projectile K-vacancy is measured. The result shows that it almost remains stable over this energy range and has good consistency with the predictions by vacancy transfer via the 2po-lscr rotational coupling, which gives experimental evidence for K-vacancy sharing between two partners. Furthermore, the discussion for comparisons between the experimental ionization cross sections and the possible theoretical estimations is presented. These comparisons suggest that the experimental data agree well with those predicted by the Binary-Encounter approximation (BEA) model but are not in good agreement with the modified BEA calculations. It allows us to infer that the direct ionization (and/or excitation) is of importance to initial K-vacancy production before 2po-lso transitions in the present collision condition. 展开更多
关键词 vacancy sharing ionization cross sections Binary-Encounter approximation model
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Anomalous transport driven by ion temperature gradient instability in an anisotropic deuterium-tritium plasma
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作者 Debing ZHANG Limin YU +2 位作者 Erbing XUE Xianmei ZHANG Haijun REN 《Plasma Science and Technology》 SCIE EI CAS CSCD 2022年第2期45-56,共12页
In this work,the anomalous transport driven by the ion temperature gradient instability is investigated in an anisotropic deuterium-tritium(D-T)plasma.The anisotropic factorα,defined as the ratio of perpendicular tem... In this work,the anomalous transport driven by the ion temperature gradient instability is investigated in an anisotropic deuterium-tritium(D-T)plasma.The anisotropic factorα,defined as the ratio of perpendicular temperature to parallel temperature,is introduced to describe the temperature anisotropy in the equilibrium distribution function.The linear dispersion relation in local kinetic limit is derived,and then numerically evaluated to study the dependence of mode frequency on the anisotropic factorαof D and the fraction of T particleεTby choosing three sets of typical parameters,denoted as the cyclone base case,ITER and CFETR cases.Based on the linear results,the mixing length model approximation is adopted to analyze the quasi-linear particle and energy fluxes for D and T.It is found that choosing smallαand largeεTis beneficial for the confinement of particle and energy for D and T.This work may be helpful for the estimation of turbulent transport level in the ITER and CFETR devices. 展开更多
关键词 deuterium-tritium plasma ion temperature gradient instability temperature anisotropy turbulent transport mixing length model approximation
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The Mixed Spin-1/2 and Spin-1 Ising–Heisenberg Model in the Mean-Field Approximation: a New Approach
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作者 Erhan Albayrak 《Chinese Physics Letters》 SCIE CAS CSCD 2018年第3期84-88,共5页
Thermodynamic properties of the mixed spin-1 and spin-1/2 Ising-Heisenberg model are studied on a honeycomb lattice using a new approach in the mean-field approximation to analyze the effects of longitudinal Dz and tr... Thermodynamic properties of the mixed spin-1 and spin-1/2 Ising-Heisenberg model are studied on a honeycomb lattice using a new approach in the mean-field approximation to analyze the effects of longitudinal Dz and transverse Dx crystal fields. The phase diagrams are calculated in detail by studying the thermal variations of the order parameters, i.e., magnetizations and quadrupole moments, and compared with the literature to assess the reliability of the new approach. It is found that the model yields both second- and first-order phase transitions, and tricritical points. The compensation behavior of the model is also investigated for the sublattice magnetizations, and longitudinal and transverse quadrupolar moments. The latter type of compensation is observed in the literature but its possible importance is overlooked. 展开更多
关键词 Heisenberg Model in the Mean-Field Approximation The Mixed Spin-1/2 and Spin-1 Ising a New Approach
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Modeling Common-Mode Current Due to Asymmetric Aging of Machine Winding Insulation
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作者 Jin Zhao Aaron D.Brovont 《Complex System Modeling and Simulation》 2023年第2期118-128,共11页
Machine stator winding insulation degradation is one of the main results of machine aging.It is non-negligible once this degradation process becomes asymmetric between phases.The traditional way to determine the insul... Machine stator winding insulation degradation is one of the main results of machine aging.It is non-negligible once this degradation process becomes asymmetric between phases.The traditional way to determine the insulation state of health is a partial discharge test.However,this method requires the system offline,which causes production loss and extra administrative burden.This paper presents an idea for better characterizing the insulation machine’s state of health using common-mode(CM)behavior in the machine-drive system.With the help of circuit decomposition methods and modeling tools,the CM quantities due to asymmetric aging show a unique characteristic that distinguishes itself from other differential-mode(DM)quantities in the equivalent circuit.It is shown effective to represent the asymmetric aging effect from the detection of system leakage current.This paper provides an analytical method to quantify this characteristic from mathematical approaches,and a proper approximation has been made on the CM equivalent model(CEM)such that the CM behavior is accurately characterized.The proposed method will serve the purpose of predicting machine abnormal behavior using the simple RLC circuit.Researchers can adapt this method to quantify and characterize the machine insulation state of health(SOH). 展开更多
关键词 common-mode equivalent circuit machine decomposition machine stator winding insulation health model approximation
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EA模型在海洋的速度横向时空互相关函数中的应用
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作者 梁长荣 尚晓东 +2 位作者 陈桂英 何晓舟 童彭尔 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2024年第3期54-60,共7页
椭圆近似(EA)模型是从单个点的时间波动数据中推断空间波动数据的重要方法,它已在室内实验剪切场的纵向时空互相关函数C(r,τ)得到验证并被广泛应用.在这里,我们研究了EA模型在海洋流场中的有效性,并介绍了其在横向时空互相关函数G(r,τ... 椭圆近似(EA)模型是从单个点的时间波动数据中推断空间波动数据的重要方法,它已在室内实验剪切场的纵向时空互相关函数C(r,τ)得到验证并被广泛应用.在这里,我们研究了EA模型在海洋流场中的有效性,并介绍了其在横向时空互相关函数G(r,τ)中的应用.结果表明,EA模型在海洋的速度场中是有效的,即G(r,τ)具有G(r_(E),0)的尺度形式,其中r_(E)=[(r-Uτ)^(2)+(Vτ)^2]^(1/2),U和V是与内波垂直相速度相关的两个特征速度.基于EA模型,我们可以获得海洋的垂直波数能谱,并估计海洋的泰勒微尺度和雷诺数. 展开更多
关键词 Elliptical approximation model Spatial fluctuations Temporal fluctuations Space-time cross-correlation functions Taylormicro-scale
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