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Escape Rate in the Bistable sawtooth System Driven by Correlated Multiplicative and Additive White Noises

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Chinese Physics Letters 2001年第2期18卷 175-177页

作者： YOU Jing-Yun CAO Li WU Da-Jin LIANG Gui-Yun State Key Laboratory of Laser Technology Huazhong University of Science and TechnologyWuhan 430074 CCAST(World Laboratory) P.O.Box 8730Beijing 100080 Department of Physics Huazhong University of Science and TechnologyWuhan 430074

We study the escape problem of a bistable sawtooth system driven by correlated multiplicative and additive white *** analytic representation of the relative escape rate is *** novel phenomena are found from the calculation result;“suppression platform”appears in the relative escape rate when the noise correlation coefficientλis ***,for small positive values ofλ,the relative escape rate exhibits“suppression platform”and then“resonant activation”with the increasing noise strength ratio R.

关键词： sawtooth noise activation

Flow of Generalized Burgers’ Fluid Induced by sawtooth Pulses Stress with Quadratic Edges

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Journal of Applied Mathematics and Physics 2018年第6期6卷 1258-1277页

作者： Qamar Sultan Zaib Un Nisa Mudassar Nazar Centre for Advanced Studies in Pure and Applied Mathematics Bahauddin Zakariya University Multan Pakistan School of Mathematical Sciences University of Science and Technology of China Hefei China

This paper presents the unsteady magnetohydrodynamic (MHD) flow of a generalized Burgers’ fluid between two side walls perpendicular to a plate. The flow is generated from rest at time ?induced by stress applied on the bottom plate. The stress is assumed to be like sawtooth pulses with quadratic edges. The solutions obtained by means of the Laplace, and Fourier cosine and sine transforms are presented as a sum between the corresponding Newtonian and non-Newtonian contributions. Graphs are sketched for various parameters of interest.

关键词： Generalized Burgers’ Fluid sawtooth Pulses Stress Fourier Cosine and Sine Transforms

Observations of mode frequency increase and the appearance of ITB during the m/n=1/1 kink mode in EAST high electron temperature long pulse operation

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Plasma Science and Technology 2023年第2期25卷 68-76页

作者：晁燕张威胡立群耿康宁徐立清张涛臧庆周天富 Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031People's Republic of China University of Science and Technology of China Hefei 230026People's Republic of China Institute for Fusion Theory and Simulation School of PhysicsZhejiang UniversityHangzhou 310027People's Republicof China

A new long-pulse high electron temperature(Te)regime has been achieved on experimental advanced superconducting tokamak by pure radio frequency *** this new scenario,there are mainly two confinement states involving two magneto-hydrodynamic(MHD)modes,one of which is identified as m/n=1/1 kink mode(where m and n are the poloidal and toroidal mode numbers,respectively).The frequency evolution of the kink mode is investigated through the three-dimensional,toroidal,and nonlinear Hall-MHD code *** firstly find that the frequency of the m/n=1/1 kink mode significantly increases during each sawtooth crash and then confirmed it through the experimental *** simulation results indicate that the increase of the mode frequency is mainly due to the significant increase of the electron diamagnetic frequency nearby the reconnection *** have also observed the internal transport barrier(ITB)during the m/n=1/1 kink *** further investigate this m/n=1/1 kink mode in this new regime,the multi-scale interactions between the m/n=1/1 kink mode and turbulence are discussed.

关键词： sawtooth electron diamagnetic drift ITB multi-scale interaction

Numerical analysis of the optimized performance of the electron cyclotron wave system in a HL-2M tokamak

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Chinese Physics B 2016年第4期25卷 214-221页

作者：李景春龚学余董家齐王俊尹岚 School of Nuclear Science and Technology University of South China Hengyang 421001 China Southwestern Institute of Physics P 0 Box 432 Chengdu 610041 China School of Mathematics and Physics University of South China Hengyang 421001 China

The capabilities of current drive, neoclassical tearing mode （NTM） stabilization, and sawtooth control are analyzed for the electron-cyclotron wave （ECW） system in a HL-2M tokamak. Better performance of the upper launcher is demonstrated in comparison with that of a dropped upper launcher, in terms of JEc/Jbs for NTM stabilization and 1ECCD/（Aptor）2 for sawtooth control. 1-MW ECW power is enough for the 3/2 NTM stabilization, and 1.8-MW ECW power is required to suppress 2/1 NTM in a single null divertor equilibrium with 1.2-MA toroidal current with the upper launcher. Optimization simulation of electron-cyclotron current drive （ECCD） is carried out for three mirrors in an equatorial port, indicating that the middle mirror has a good performance compared with the top and bottom mirrors. The results for balanced co- and counter-ECCD in an equatorial port are also presented.

关键词： HL-2M electron-cyclotron current drive neoclassical tearing modes sawtooth

Soft X-ray Tomography on HT-7

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Plasma Science and Technology 2009年第4期11卷 472-476页

作者：陈开云胡立群丁玥马天鹏段艳敏 Institute of Plasma Physics Chinese Academy of Sciences Department of Modern Physics University of Science and Technology of China Foundation Department The North University for Ethnics

The soft X-ray imaging system on HT-7 is introduced. Fourier-Bessel expansion method is used to reconstruct the soft X-ray emission distribution. Simulation results show that the inversion accuracy is associated with the angular expansion limit and the hot core displacement. In addition, tomographic results of sawtooth oscillations in a typical low hybrid current drive （LHCD） plasma are presented. It is shown that the reconstructions are reliable to analyze the perturbative mode and the evolution.

关键词： tomography sawtooth soft X-ray

The impact of toroidal mode coupling on high-density discharges in J-TEXT

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Plasma Science and Technology 2024年第12期26卷 1-8页

作者： Peng DENG Wenzhe MAO Zhipeng CHEN Yinan ZHOU Peng SHI Zhoujun YANG Li GAO Tao LAN Jinlin XIE Hong LI Zian WEI Adi LIU Chu ZHOU Weixing DING Wandong LIU Ge ZHUANG School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230026People’s Republic of China State Key Laboratory of Advanced Electromagnetic Technology International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma PhysicsSchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074People’s Republic of China Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People’s Republic of China

Density limit has long been a widely studied issue influencing the operating range of *** rapid growth of the m/n=2/1(where m and n are poloidal and toroidal mode numbers,respectively)tearing mode is generally regarded as a primary precursor to the density limit *** this experiment,the coupling of the m/n=1/1 mode and the m/n=2/1 mode in highdensity plasma was *** a sawtooth cycle,the frequencies of the two modes gradually converge until they become *** that,toroidal coupling occurs between the 1/1 and 2/1 modes,resulting in a mutually fixed phase *** the occurrence of toroidal coupling,the 2/1 mode is *** to the disruption,the cessation of the 1/1 and 2/1 mode coupling,along with the rapid growth in the amplitude of the 2/1 mode,can be ***,under the same parameters,comparing discharges with or without the 1/1 mode,it is found that the presence of the 1/1 mode leads to higher plasma density and temperature parameters.

关键词： toroidal coupling tearing mode density limit sawtooth

Stick-Slip Tower-Shaped Piezoelectric Actuator

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Transactions of Nanjing University of Aeronautics and Astronautics 2015年第2期32卷 156-162页

作者：陈乾伟鞠全勇黄卫清时运来 School of Mechatronic Engineering Jinling Institute of Technology State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics

Since stick-slip actuators present the advantage of allowing long displacements(several centimeters or even more)at a high speed with an ultra high resolution(<5nm),a new type of stick-slip piezoelectric actuator is p... 详细信息

Since stick-slip actuators present the advantage of allowing long displacements(several centimeters or even more)at a high speed with an ultra high resolution(sawtooth input voltage,driving foot of the stator is able to generate a tangential asymmetrical vibration on the top,and the slider is thus pushed to move.A prototype and its testing equipment are fabricated and *** that,the testing of vibration mode and mechanical characteristics as well as stepping characteristics are *** results show that under the condition that the sawtooth input voltage is400VP-Pand the pre-pressure is *** of the actuator reaches its maximum 1.2mm/s at the frequency of 8000 Hz and drops to its minimum 35nm/s at the frequency of *** the excitation signal is the single-phase sawtooth stepping signal,the tower-shaped actuator can directionally move forward or backward step by *** when excited by the sawtooth stepping signal with 1Hz and 300VP-Pduring 1cycle(200ms),the actuator has a minimum stepping distance of 22 nm.

关键词： piezoelectric actuator stick-slip sawtooth stepping

Upper Sun River Drainage Basin Origin Determined by Topographic Map Interpretation Techniques: Lewis and Clark and Teton Counties, Montana, USA

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Open Journal of Geology 2019年第5期9卷 257-277页

作者： Eric Clausen Independent Researcher Jenkintown PA

A new and fundamentally different regional geomorphology paradigm in which massive south- and southeast-oriented meltwater floods flowed across the entire Missouri River drainage basin is tested by interpreting detailed topographic maps of the Montana upper Sun River drainage basin region by trying to explain origins of previously unexplained or poorly explained erosional landforms located upstream from Sun River Canyon (which cuts across Montana’s north-to-south oriented sawtooth Range). Mountain passes, through valleys, and other drainage divide low points along what are today high mountain ridges, including the North American east-west continental divide, are interpreted to be evidence of drainage routes that once crossed the region. These drainage divide crossings suggest that prior to erosion of present-day upper Sun River drainage basin valleys, massive floods moved in south directions across what are today the north-oriented Middle and South Fork Flathead River drainage basins into today’s upper Sun River drainage basin area and carved a complex of diverging and converging channels into what was probably a low relief surface now represented by the crests of the region’s highest mountain ridges. Further, the map evidence shows how a diverging complex of south- and southeast-oriented upstream Sun River drainage basin flood flow channels changed flow direction to cross the sawtooth Range in a northeast direction before converging on the Montana plains at a location downstream from Sun River Canyon. The observed upper Sun River drainage basin area topographic map evidence is consistent with the new geomorphology paradigm predictions, in which massive south-oriented meltwater floods flowing across the rising rim of a continental ice sheet created deep “hole” (created by deep ice sheet erosion and ice sheet weight caused crustal warping) are diverted to flow in northeast and north directions into and across deep “hole” space being opened up by ice sheet melting.

关键词： Dearborn River Flathead River Missouri River Montana sawtooth Range Mountain Pass Origin New Geomorphology Paradigm Transverse Drainage

SPATIAL RESOLUTION HARD X-RAY MEASUREMENT ON CT-68 TOKAMAK

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Chinese Physics Letters 1988年第10期5卷 469-472页

作者： QI Xiazhi WANG Long Institute of Physics Academia SinicaBeijing

The hard X-ray emissions from different chords of plasma column and at the limiter have been detected by a detector array on CT-6B *** experimental results show that the hard X-ray emission is correlative with MHD activity in the *** measured signals are in the same phase as that of soft X-ray from the outer region near q=I resonant surface when sawtooth oscillation occus,indicating that the most part of runway electrons is generated in the region.

关键词： sawtooth TOKAMAK tokamak