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Modeling and Simulation of the Magnetic Method for High Voltage Direct Current Inspection Robot
Xian-jin Xu,Cheng-hui Liu,Yu Yan,Hao-da Chen,Lei Fang,Yun-long Wang,Long-hui Wu 한국자기학회 2018 Journal of Magnetics Vol.23 No.3
In order to solve the slipping problem of a two-arm-wheel combined inspection robot, a maglev system based on the magnetic field of a high voltage direct current (HVDC) is proposed. The magnetic system comprises of two parts: a magnetic levitation system and a magnetic drive system. The levitation component overcomes the gravity of the robot by the Ampere force generated by current-carrying coils in the magnetic field of HVDC. The drive component utilizes the Ampere force generated by current-carrying coils in the magnetic field of HVDC as the driving force. Simulation results of the model are compared with the calculated values. The results show that the magnetic levitation method and the magnetic drive method are theoretically feasible, and the model is accurate and effective, which is of great practical significance to the physical realization of the inspection robot.
PROPER EFFICIENCY FOR SET-VALUED OPTIMIZATION PROBLEMS AND VECTOR VARIATIONAL-LIKE INEQUALITIES
Long, Xian Jun,Quan, Jing,Wen, Dao-Jun Korean Mathematical Society 2013 대한수학회보 Vol.50 No.3
The purpose of this paper is to establish some relationships between proper efficiency of set-valued optimization problems and proper efficiency of vector variational-like inequalities under the assumptions of generalized cone-preinvexity. Our results extend and improve the corresponding results in the literature.
Proper efficiency for set-valued optimization problems and vector variational-like inequalities
Xian Jun Long,Jing Quan,Dao-Jun Wen 대한수학회 2013 대한수학회보 Vol.50 No.3
The purpose of this paper is to establish some relationships between proper efficiency of set-valued optimization problems and proper efficiency of vector variational-like inequalities under the assumptions of generalized cone-preinvexity. Our results extend and improve the corresponding results in the literature.
Connectedness and compactness of weak efficient solutions for vector equilibrium problems
Xian Jun Long,Jian Wen Peng 대한수학회 2011 대한수학회보 Vol.48 No.6
In this paper, without assumption of monotonicity, we study the compactness and the connectedness of the weakly efficient solutions set to vector equilibrium problems by using scalarization method in locally convex spaces. Our results improve the corresponding results in [X. H. Gong, Connectedness of the solution sets and scalarization for vector equilibrium problems, J. Optim. Theory Appl. 133 (2007), 151-161].
CONNECTEDNESS AND COMPACTNESS OF WEAK EFFICIENT SOLUTIONS FOR VECTOR EQUILIBRIUM PROBLEMS
Long, Xian Jun,Peng, Jian Wen Korean Mathematical Society 2011 대한수학회보 Vol.48 No.6
In this paper, without assumption of monotonicity, we study the compactness and the connectedness of the weakly efficient solutions set to vector equilibrium problems by using scalarization method in locally convex spaces. Our results improve the corresponding results in [X. H. Gong, Connectedness of the solution sets and scalarization for vector equilibrium problems, J. Optim. Theory Appl. 133 (2007), 151-161].
Characterization and uncertainty of uplift load-displacement behaviour of belled piers
Lu, Xian-long,Qian, Zeng-zhen,Zheng, Wei-feng,Yang, Wen-zhi Techno-Press 2016 Geomechanics & engineering Vol.11 No.2
A total of 99 full-scale field load tests at 22 sites were compiled for this study to elucidate several issues related to the load-displacement behaviour of belled piers under axial uplift loading, including (1) interpretation criteria to define various elastic, inelastic, and "failure" states for each load test from the load-displacement curve; (2) generalized correlations among these states and determinations to the predicted ultimate uplift resistances; (3) uncertainty in the resistance model factor statistics required for reliability-based ultimate limit state (ULS) design; (4) uncertainty associated with the normalized load-displacement curves and the resulting model factor statistics required for reliability-based serviceability limit state (SLS) design; and (5) variations of the combined ULS and SLS model factor statistics for reliability-based limit state designs. The approaches discussed in this study are practical and grounded realistically on the load tests of belled piers with minimal assumptions. The results on the characterization and uncertainty of uplift load-displacement behaviour of belled piers could be served as to extend the early contributions for reliability-based ULS and SLS designs.
Long-He Xu,Xing-Si Xie,Xintong Yan,Zhong-Xian Li 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.71 No.1
A modified mechanical model of pre-pressed spring self-centering energy dissipation (PS-SCED) brace is proposed, and the hysteresis band is distinguished by the indication of relevant state variables. The MDOF frame system equipped with the braces is formulated in an incremental form of linear acceleration method. A multi-objective genetic algorithm (GA) based brace parameter optimization method is developed to obtain an optimal solution from the primary design scheme. Parameter sensitivities derived by the direct differentiation method are used to modify the change rate of parameters in the GA operator. A case study is conducted on a steel braced frame to illustrate the effect of brace parameters on node displacements, and validate the feasibility of the modified mechanical model. The optimization results and computational process information are compared among three cases of different strategies of parameter change as well. The accuracy is also verified by the calculation results of finite element model. This work can help the applications of PS-SCED brace optimization related to parameter sensitivity, and fulfill the systematic design procedure of PS-SCED brace-structure system with completed and prospective consequences.
Hysteretic behavior studies of self-centering energy dissipation bracing system
Long-He Xu,Xiaowei Fan,Dengcheng Lu,Zhong-Xian Li 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.6
This paper presents a new type of pre-pressed spring self-centering energy dissipation (PS-SCED) bracing system that combines friction mechanisms between the inner and outer tube members to provide the energy dissipation with the pre-pressed combination disc springs installed on both ends of the brace to provide the selfcentering capability. The mechanics and the equations governing the design and hysteretic responses of the bracing system are outlined, and a series of validation tests of components comprising the self-centering mechanism of combination disc springs, the friction energy dissipation mechanism, and a large scale PS-SCED bracing specimen were conducted due to the low cyclic reversed loadings. Experimental results demonstrate that the proposed bracing system performs as predicted by the equations governing its mechanical behaviors, which exhibits a stable and repeatable flag-shaped hysteretic response with excellent self-centering capability and appreciable energy dissipation, and large ultimate bearing and deformation capacities. Results also show that almost no residual deformation occurs when the friction force is less than the initial pre-pressed force of disc springs.
Model predictive control strategies for protection of structures during earthquakes
Long-He Xu,Zhong-Xian Li 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.2
This paper presents a theoretical study of a model predictive control (MPC) strategy employed in semi-active control system with magnetorheological (MR) dampers to reduce the responses of seismically excited structures. The MPC scheme is based on a prediction model of the system response to obtain the control actions by minimizing an objective function, which can compensate for the effect of time delay that occurred in real application. As an example, a 5-story building frame equipped with two 20 kN MR dampers is presented to demonstrate the performance of the proposed MPC scheme for addressing time delay and reducing the structural responses under different earthquakes, in which the predictive length l = 5 and the delayed time step d = 10, 20, 40, 60, 100 are considered. Comparison with passive-off, passive-on, and linear quadratic Gaussian (LQG) control strategy indicates that MPC scheme exhibits good control performance similar to the LQG control strategy, both have better control effectiveness than two passive control methods for most cases, and the MPC scheme used in semi-active control system show more effectiveness and robustness for addressing time delay and protecting structures during earthquakes.