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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.
Opachich, Y P,Comin, A,Bartelt, A F,Young, A T,Scholl, A,Feng, J,Schmalhorst, J,Shin, H J,Engelhorn, K,Risbud, S H,Reiss, G,Padmore, H A IOP Pub 2010 Journal of Physics, Condensed Matter Vol.22 No.15
<P>The demagnetization dynamics of the Heusler alloy Co<SUB>2</SUB>MnSi was studied using picosecond time-resolved x-ray magnetic circular dichroism. The sample was excited using femtosecond laser pulses. In contrast to the sub-picosecond demagnetization of the metal ferromagnet Ni, substantially slower demagnetization with a time constant of 3.5 ± 0.5 ps was measured. This could be explained by a spin-dependent band gap inhibiting the spin-flip scattering of hot electrons in Co<SUB>2</SUB>MnSi, which is predicted to be half-metallic. A universal demagnetization time constant was measured across a range of pump power levels. </P>
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>
A MEASUREMENT OF THE COSMIC MICROWAVE BACKGROUND B-MODE POLARIZATION WITH POLARBEAR
ADE, P.A.R.,AKIBA, Y.,ANTHONY, A.E.,ARNOLD, K.,ATLAS, M.,BARRON, D.,BOETTGER, D.,BORRILL, J.,CHAPMAN, S.,CHINONE, Y.,DOBBS, M.,ELLEFLOT, T.,ERRARD, J.,FABBIAN, G.,FENG, C.,FLANIGAN, D.,GILBERT, A.,GRA The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2
POLARBEAR is a ground-based experiment located in the Atacama desert of northern Chile. The experiment is designed to measure the Cosmic Microwave Background B-mode polarization at several arcminute resolution. The CMB B-mode polarization on degree angular scales is a unique signature of primordial gravitational waves from cosmic inflation and B-mode signal on sub-degree scales is induced by the gravitational lensing from large-scale structure. Science observations began in early 2012 with an array of 1.274 polarization sensitive antenna-couple Transition Edge Sensor (TES) bolometers at 150 GHz. We published the first CMB-only measurement of the B-mode polarization on sub-degree scales induced by gravitational lensing in December 2013 followed by the first measurement of the B-mode power spectrum on those scales in March 2014. In this proceedings, we review the physics of CMB B-modes and then describe the Polarbear experiment, observations, and recent results.
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.
NEW TAYLOR-LIKE EXPANSIONS FOR FUNCTIONS OF TWO VARIABLES AND ESTIMATES OF THEIR REMAINDERS
S.S. DRAGOMIR,FENG QI,G. HANNA,P. CERONE 한국산업응용수학회 2005 Journal of the Korean Society for Industrial and A Vol.9 No.2
In this article, a generalisation of Sard's inequality for Appell polynomials is obtained. Estimates for the remainder are also provided.