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Response of plasma rotation to resonant magnetic perturbations in J-TEXT tokamak
Yan, W,Chen, Z Y,Huang, D W,Hu, Q M,Shi, Y J,Ding, Y H,Cheng, Z F,Yang, Z J,Pan, X M,Lee, S G,Tong, R H,Wei, Y N,Dong, Y B IOP 2018 Plasma physics and controlled fusion Vol.60 No.3
<P>The response of plasma toroidal rotation to the external resonant magnetic perturbations (RMP) has been investigated in Joint Texas Experimental Tokamak (J-TEXT) ohmic heating plasmas. For the J-TEXT’s plasmas without the application of RMP, the core toroidal rotation is in the counter-current direction while the edge rotation is near zero or slightly in the co-current direction. Both static RMP experiments and rotating RMP experiments have been applied to investigate the plasma toroidal rotation. The core toroidal rotation decreases to lower level with static RMP. At the same time, the edge rotation can spin to more than 20 km s<SUP>−1</SUP> in co-current direction. On the other hand, the core plasma rotation can be slowed down or be accelerated with the rotating RMP. When the rotating RMP frequency is higher than mode frequency, the plasma rotation can be accelerated to the rotating RMP frequency. The plasma confinement is improved with high frequency rotating RMP. The plasma rotation is decelerated to the rotating RMP frequency when the rotating RMP frequency is lower than the mode frequency. The plasma confinement also degrades with low frequency rotating RMP.</P>
Aerodynamic force characteristics and galloping analysis of iced bundled conductors
Lou, Wenjuan,Lv, Jiang,Huang, M.F.,Yang, Lun,Yan, Dong Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.18 No.2
Aerodynamic characteristics of crescent and D-shape bundled conductors were measured by high frequency force balance technique in the wind tunnel. The drag and lift coefficients of each sub-conductor and the whole bundled conductors were presented under various attack angles of wind. The galloping possibility of bundled conductors is discussed based on the Den Hartog criterion. The influence of icing thickness, initial ice accretion angle and sub-conductor on the aerodynamic properties were investigated. Based on the measured aerodynamic force coefficients, a computationally efficient finite element method is also implemented to analyze galloping of iced bundled conductors. The analysis results show that each sub-conductor of the bundled conductor has its own galloping feature due to the use of aerodynamic forces measured separately for every single sub-conductors.
Design of a 4-W Envelope Tracking Power Amplifier With More Than One Octave Carrier Bandwidth
Yan, J. J.,Chin Hsia,Kimball, D. F.,Asbeck, P. M. IEEE 2012 IEEE journal of solid-state circuits Vol.47 No.10
<P>This paper presents a high-efficiency broadband envelope-tracking power amplifier with operation at carrier frequencies from 500 to 1750 MHz. The RF power amplifier (RFPA) is provided by a single-chip gallium-nitride (GaN) integrated circuit (IC) whose design included a broadband output match achieved by operating directly into a load resistance of 50 Ω and broadband input match achieved using a feedback network. Under single-tone excitation, the Class-AB GaN PA IC provides output power above 12 W with greater than 50% drain efficiency and more than 10-dB gain at 40-V drain bias. When placed in envelope tracking configuration, using a representative WCDMA modulated signal with 4-MHz bandwidth and 6.6-dB peak-to-average power ratio, the ET PA achieved 4 W of average output power at its peak average drain efficiency of 31% at 752 MHz (including the power dissipation of the envelope modulator). The RFPA individually was measured to have an average drain efficiency of 58.5% for the WCDMA signal. Across the 500-1750-MHz band, using the WCDMA signal, greater than 25% average drain efficiency with more than 10 dB of gain was measured.</P>
Wang, Li,Ren, Yi,Gao, Yaozong,Tang, Zhen,Chen, Ken-Chung,Li, Jianfu,Shen, Steve G F,Yan, Jin,Lee, Philip K M,Chow, Ben,Xia, James J,Shen, Dinggang Published for the American Association of Physicis 2015 Medical physics Vol.42 No.10
<P>A significant number of patients suffer from craniomaxillofacial (CMF) deformity and require CMF surgery in the United States. The success of CMF surgery depends on not only the surgical techniques but also an accurate surgical planning. However, surgical planning for CMF surgery is challenging due to the absence of a patient-specific reference model. Currently, the outcome of the surgery is often subjective and highly dependent on surgeon's experience. In this paper, the authors present an automatic method to estimate an anatomically correct reference shape of jaws for orthognathic surgery, a common type of CMF surgery.</P>
Cloning and characterization of a novel GIGANTEA gene in sweet potato
Tang, W.,Yan, H.,Su, Z.x.,Park, S.C.,Liu, Y.j.,Zhang, Y.g.,Wang, X.,Kou, M.,Ma, D.f.,Kwak, S.S.,Li, Q. Gauthier-Villars ; Elsevier Science Ltd 2017 Vol. No.
<P>The transition from vegetative to reproductive growth, a key event in the lifecycle of a plant, is affected by environmental stresses. The flowering-time regulator GIGANTEA (GI) may be contributing to susceptibility of the regulation of photoperiodic flowering, circadian rhythm control, and abiotic stress resistance in Arabidopsis. However, the role of GI in sweet potato remains unknown. Here, we isolated and characterized a GI gene (IbGI) from sweet potato (Ipomoea batatas [LI Lam). The IbGI cDNA sequence was isolated based on information from a sweet potato transcriptome database. IbGI mRNA transcript levels showed robust circadian rhythm control during the light-dark transition, and the expression of IbGI was stronger in leaves and roots than in stems. IbGI protein is predominantly localized to the nucleus. IbGI expression was upregulated by high temperature, drought, and salt stress but downregulated by cold stress. Overexpressing IbGI in the Arabidopsis gi-2 mutant background rescued its late flowering phenotype and reduced its salt tolerance. Taken together, these results indicate that IbGI shares functions in regulating flowering, the circadian rhythm, and tolerance to some stresses with other GI orthologs. (C) 2017 Elsevier Masson SAS. All rights reserved.</P>
Analysis of the Magnetic Properties of RFe₁₁Ti and RFe₁₁TiH (R=Tb,Ho)
S. W. Xu,Y. Yan,H. M. Jin,X. F. Wang,W. Q. Wang,F. Su 한국자기학회 2003 Journal of Magnetics Vol.8 No.4
The values of crystalline-electric-field parameters A㎚ for RFe₁₁TiHx (R=Tb,Ho) (x=0,1) are obtained by fitting calculations to the magnetization curves along the crystal axes at 4.2 K and higher temperatures. The insertion of H element in RFe₁₁Ti significantly affects CEF parameters A㎚. By using exchange field 2μ_BHex derived by inelastic neutron scattering and fitted A㎚, the calculations reproduce the experimental curves well.
Efficiency Enhancement of mm-Wave Power Amplifiers Using Envelope Tracking
Yan, J J,Presti, C D,Kimball, D F,Young-Pyo Hong,Chin Hsia,Asbeck, P M,Schellenberg, J IEEE 2011 IEEE microwave and wireless components letters Vol.21 No.3
<P>This letter presents a 44 GHz GaAs MMIC-based power amplifier (PA) which uses envelope tracking (ET) techniques for efficiency enhancement. Digital pre-distortion (DPD) is also employed to achieve high linearity. For a 7.6 dB PAPR 64QAM 20 MHz bandwidth signal (data rate 120 Mb/s) at an output power of 23.8 dBm, the measured EVM was 2.0% and ACPR1 was better than -40 dBc. Power efficiency enhancement of more than 5.7 times for the final MMIC stage (from 1.22% to 7%) was measured, using an external drain modulator. To the authors' best knowledge, this is the first time envelope tracking has been applied to PAs in the millimeter wave regime.</P>
Wang, Li,Chen, Ken Chung,Gao, Yaozong,Shi, Feng,Liao, Shu,Li, Gang,Shen, Steve G. F.,Yan, Jin,Lee, Philip K. M.,Chow, Ben,Liu, Nancy X.,Xia, James J.,Shen, Dinggang Published for the American Association of Physicis 2014 Medical physics Vol.41 No.4
<P>Cone-beam computed tomography (CBCT) is an increasingly utilized imaging modality for the diagnosis and treatment planning of the patients with craniomaxillofacial (CMF) deformities. Accurate segmentation of CBCT image is an essential step to generate three-dimensional (3D) models for the diagnosis and treatment planning of the patients with CMF deformities. However, due to the poor image quality, including very low signal-to-noise ratio and the widespread image artifacts such as noise, beam hardening, and inhomogeneity, it is challenging to segment the CBCT images. In this paper, the authors present a new automatic segmentation method to address these problems.</P>