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R&D Status of High-current Accelerators at IFP
J. J. Deng,J. S. Shi,W. P. Xie,L. W. Zhang,K. Z. Zhang,S. P. Feng,J. Li,M. Wang,Y. He,L. S. Xia,Z. Y. Dai,H. T. Li,L. Wen,S. F. Chen,X. Li,Q. G. Lai,M. H. Xia,Y. C. Guan,S. Y. Song,L. Chen 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.61
High-current accelerators have many important applications in Z-pinches, high-power microwaves, and free electron lasers, imploding liners and radiography and so on. Research activities on Zpinches, imploding liners, radiography at the Institute of Fluid Physics (IFP) are introduced. Several main high-current accelerators developed and being developed at IFP are described, such as the Linear Induction Accelerator X-Ray Facility Upgrade (LIAXFU, 12 MeV, 2.5 kA, 90 ns), the Dragon-I linear induction accelerator (20 MeV, 2.5 kA, 60 ns), and the Primary Test Stand for Z-pinch (PTS, 10 MA, 120 ns). The design of Dragon-II linear induction accelerator (20 MeV, 2.5 kA, 3 × 60 ns) to be built will be presented briefly.
Garitte, B.,Nguyen, T. S.,Barnichon, J. D.,Graupner, B. J.,Lee, C.,Maekawa, K.,Manepally, C.,Ofoegbu, G.,Dasgupta, B.,Fedors, R.,Pan, P. Z.,Feng, X. T.,Rutqvist, J.,Chen, F.,Birkholzer, Jens,Wang, Q. Springer 2017 Environmental Earth Sciences Vol.76 No.9
<P>Coupled thermal-hydrological-mechanical (THM) processes in the near field of deep geological repositories can influence several safety features of the engineered and geological barriers. Among those features are: the possibility of damage in the host rock, the time for re-saturation of the bentonite, and the perturbations in the hydraulic regime in both the rock and engineered seals. Within the international cooperative code-validation project DECOVALEX-2015, eight research teams developed models to simulate an in situ heater experiment, called HE-D, in Opalinus Clay at the Mont Terri Underground Research Laboratory in Switzerland. The models were developed from the theory of poroelasticity order to simulate the coupled THM processes that prevailed during the experiment and thereby to characterize the in situ THM properties of Opalinus Clay. The modelling results for the evolution of temperature, pore water pressure, and deformation at different points are consistent among the research teams and compare favourably with the experimental data in terms of trends and absolute values. The models were able to reproduce the main physical processes of the experiment. In particular, most teams simulated temperature and thermally induced pore water pressure well, including spatial variations caused by inherent anisotropy due to bedding.</P>
Research on transmission paths of a coupled beam-cylindrical shell system by power flow analysis
G. P. Feng,Z. Y. Zhang,Y. Chen,H. X. Hua 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.8
A power flow analysis based on a substructure approach is performed to exhibit vibration transmission in a complex coupled beam-cylindrical shell system. The system is divided into a shell substructure and a beam substructure, which are coupled by three spring-dampers. The theoretical receptance function of each substructure with a free-free interface condition is formulated by modal analysis to describe the dynamical behavior. On the basis of the receptance functions of the two substructures as well as synthesis through the geometrical compatibility and force balance conditions at the coupling interfaces, the dynamic characteristics of the coupled system are calculated. Both the input and transmitted powers within the system are estimated, and the influences of the excitation locations, the stiffness and loss factor of the spring-dampers on the vibration transmission are investigated as well.
Numerical investigation on residual stress in photovoltaic laminates after lamination
Q. Z. Zhang,B. F. Shu,M. B. Chen,Q. B. Liang,C. Fan,Z. Q. Feng,P. J. Verlinden 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.2
A series of simulations were carried out to investigate the residual stress induced in the photovoltaic laminate during the cooling processafter lamination with a global model and several submodels. The simulations focus separately on the effects of the cooling rate, thecell layout and anisotropy on the residual stress and deformation of the photovoltaic laminate in a comparative manner with the finiteelement method. The results have shown that significant stress concentration and twist occurs in the interconnection region in the cell. Inaddition, different cooling rates, cell layouts and anisotropy only influence the largest stress rather than the stress distribution and deformation. Therefore, the results of a uniform stationary isotropic model with fewer cells can provide enough insight into the stress distributionin real photovoltaic laminates and the modified largest first principal stress can be used for design and verification.
S.-Z. Feng,L.-Y. Chen,J. Li,P.-H. Mao,R.-J. Zhang,X.-F. Li,Y.-X. Zheng 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.II
In this work, a series of SiO$_x$/SiO$_2$ superlattices were prepared, by using reactive evaporation, with different thicknesses of the SiO$_x$ layers. After being annealed at 1100 $^\circ$C, composite thin films with the nano-crystals of silicon (nc-Si) embedded in the SiO$_2$ layers were formed. The optical properties of the films were measured by using the spectroscopic ellipsometric (SE) method in the photon energy range from 1.5 to 4.5 eV at three different incidence angles of 65$^\circ$, 70$^\circ$ and 75$^\circ$. In terms of the ellipsometric data, the effective medium approximation (EMA) with the four-parameter Lorentz oscillator model was used to fit the spectra and to extract the optical dispersion of the nc-Si particles. We found that the dielectric functions of the composite films strongly depended on the volume fraction of nc-Si and the constant of the SiO$_2$ layers, which changed with the composition in the investigated spectrum range
Buckling of axial compressed cylindrical shells with stepwise variable thickness
H.G. Fan,Z.P. Chen,W.Z. Feng,F. Zhou,X.L. Shen,G.W. Cao 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.1
This paper focuses on an analytical research on the critical buckling load of cylindrical shells with stepwise variable wall thickness under axial compression. An arctan function is established to describe the thickness variation along the axial direction of this kind of cylindrical shells accurately. By using the methods of separation of variables, small parameter perturbation and Fourier series expansion, analytical formulas of the critical buckling load of cylindrical shells with arbitrary axisymmetric thickness variation under axial compression are derived. The analysis is based on the thin shell theory. Analytic results show that the critical buckling load of the uniform shell with constant thickness obtained from this paper is identical with the classical solution. Two important cases of thickness variation pattern are also investigated with these analytical formulas and the results coincide well with those obtained from other authors. The cylindrical shells with stepwise variable wall thickness, which are widely used in actual engineering, are studied by this method and the analytical formulas of critical buckling load under axial compression are obtained. Furthermore, an example is presented to illustrate the effects of each strake’s length and thickness on the critical buckling load.
Buckling of axial compressed cylindrical shells with stepwise variable thickness
Fan, H.G.,Chen, Z.P.,Feng, W.Z.,Zhou, F.,Shen, X.L.,Cao, G.W. Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.1
This paper focuses on an analytical research on the critical buckling load of cylindrical shells with stepwise variable wall thickness under axial compression. An arctan function is established to describe the thickness variation along the axial direction of this kind of cylindrical shells accurately. By using the methods of separation of variables, small parameter perturbation and Fourier series expansion, analytical formulas of the critical buckling load of cylindrical shells with arbitrary axisymmetric thickness variation under axial compression are derived. The analysis is based on the thin shell theory. Analytic results show that the critical buckling load of the uniform shell with constant thickness obtained from this paper is identical with the classical solution. Two important cases of thickness variation pattern are also investigated with these analytical formulas and the results coincide well with those obtained from other authors. The cylindrical shells with stepwise variable wall thickness, which are widely used in actual engineering, are studied by this method and the analytical formulas of critical buckling load under axial compression are obtained. Furthermore, an example is presented to illustrate the effects of each strake's length and thickness on the critical buckling load.
L. XIONG,G. W. TENG,Z.-P. YU,W. X. ZHANG,Y. FENG 한국자동차공학회 2016 International journal of automotive technology Vol.17 No.4
In this paper, a novel direct yaw control method based on driver operation intention for stability control of a distributed drive electric vehicle is proposed. It was discovered that the vehicle loses its stability easily under an emergency steering alignment (EA) problem. An emergent control algorithm is proposed to improve vehicle stability under such a condition. A driver operation intention recognition module is developed to identify the driving conditions. When the vehicle enters into an EA condition, the module can quickly identify it and transfer the control method from normal direct yaw control to emergency control. Two control algorithms are designed. The emergency control algorithm is applied to an EA condition while the adaptive control algorithm is applied to other conditions except the EA condition. Both simulation results and real vehicle results show that: The driver module can accurately identify driving conditions based on driver operation intention. When the vehicle enters into EA condition, the emergent control algorithm can intervene quickly, and it has proven to outperform normal direct yaw control for better stabilization of vehicles.