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Search Results: 1 - 10 of 29335 matches for " Gang Song "
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Spin filter and spin valve in ferromagnetic graphene
Yu Song,Gang Dai
Physics , 2015, DOI: 10.1063/1.4921668
Abstract: We propose and demonstrate that a EuO-induced and top-gated graphene ferromagnetic junction can be simultaneously operated as a spin filter as well as a spin valve. We attribute such a remarkable result to a coexistence of a half-metal band and a common energy gap for opposite spins in ferromagnetic graphene. We show that, both the spin filter and the spin valve can be effectively controlled by a back gate voltage, and they survive for practical metal contacts and finite temperature. Specifically, larger single spin currents and on-state currents can be reached with contacts with work functions similar to graphene, and the spin filter can operate at higher temperature than the spin valve.
The K?hler-Ricci flow on surfaces of positive Kodaira dimension
Jian Song,Gang Tian
Mathematics , 2006, DOI: 10.1007/s00222-007-0076-8
Abstract: The existence of K\"ahler-Einstein metrics on a compact K\"ahler manifold has been the subject of intensive study over the last few decades, following Yau's solution to Calabi's conjecture. The Ricci flow, introduced by Richard Hamilton has become one of the most powerful tools in geometric analysis. We study the K\"ahler-Ricci flow on minimal surfaces of Kodaira dimension one and show that the flow collapses and converges to a unique canonical metric on its canonical model. Such a canonical is a generalized K\"ahler-Einstein metric. Combining the results of Cao, Tsuji, Tian and Zhang, we give a metric classification for K\"aher surfaces with a numerical effective canonical line bundle by the K\"ahler-Ricci flow. In general, we propose a program of finding canonical metrics on canonical models of projective varieties of positive Kodaira dimension.
Canonical measures and Kahler-Ricci flow
Jian Song,Gang Tian
Mathematics , 2008,
Abstract: We show that the Kahler-Ricci flow on an algebraic manifold of positive Kodaira dimension and semi-ample canonical line bundle converges to a unique canonical metric on its canonical model. It is also shown that there exists a canonical measure of analytic Zariski decomposition on an algebraic manifold of positive Kodaira dimension. Such a canonical measure is unique and invariant under birational transformations under the assumption of the finite generation of canonical rings.
The Kahler-Ricci flow through singularities
Jian Song,Gang Tian
Mathematics , 2009,
Abstract: We prove the existence and uniqueness of the weak Kahler-Ricci flow on projective varieties with log terminal singularities. It is also shown that the weak Kahler-Ricci flow can be uniquely continued through divisorial contractions and flips if they exist. We then propose an analytic version of the Minimal Model Program with Ricci flow.
Bounding scalar curvature for global solutions of the Kahler-Ricci flow
Jian Song,Gang Tian
Mathematics , 2011,
Abstract: We show that the scalar curvature is uniformly bounded for the normalized Kahler-Ricci flow on a Kahler manifold with semi-ample canonical bundle. In particular, the normalized Kahler-Ricci flow has long time existence if and only if the scalar curvature is uniformly bounded, for Kahler surfaces, projective manifolds of complex dimension three, and for projective manifolds of all dimensions if assuming the abundance conjecture.
Progress of High Voltage Trenched and Implanted 4H-SiC Vertical JFET  [PDF]
Gang Chen, Song Bai, Yonghong Tao, Yun Li
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B243
Abstract:

A silicon carbide (SiC) vertical channel junction field effect transistor (VJFET) was fabricated based on in-house SiC epitaxial wafer with trenched and implanted method. Its forward drain current is in excess of 3.12 A (170 W/cm2) with a current gain of ID/IG = 19746 at gate bias VG = 3 V and drain bias VD = 5.5 V. The SiC VJFET device’s related specific on-resistance 54 mΩ·cm2. The BV gain is 250 V with Vg from -10 V to -4 V and is 350 V with Vg from -4 V to -2 V. Self-aligned floating guard rings provide edge termination that blocks 3180V at a gate bias of ?14 V and a drain-current density of 1.53 mA/cm2.

Natural Radioactivity in Miscanthus floridulu Plant from the Uranium Tailing Pile at Guangdong, South China  [PDF]
Gang Song, Qiuping Zhu, Minxing Lu, Diyun Chen, Yongheng Chen
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.29095
Abstract:

Large amounts of uranium waste rocks and tailings resulting from the exploitation and treatment of uranium ore at the Northern Guangdong mine (South China) have been accumulated in dams (tailing ponds). To reduce the dispersion of natural radionuclides into the environment, some dams were revegetated with arbor, bush and sward. Besides these plants, Miscanthus floridulu is the dominant plant growing in some of the dams. The uptake and distribution of naturally occurring uranium (238U), thorium (232Th), radium (226Ra) and potassium (40K) by Miscanthus floridulu plant from different sample sites of uranium mine were studied under native conditions. The bioconcentration factors (BCFs) of soil to Miscanthus floridulu above-ground and root were calculated and observed to be in the range of 0.14 to 7.74 and 2.71 to 17.83 for 238U, 0 to 3.02 and 0 to 3.29 for 232Th, 0.15 to 79.76 and 1.01 to 50.22 for 226Ra and 3.00 to 8.41 and 2.69 to 11.22 for 40K, respectively. The transfer factors (TFs) of Miscanthus floridulu root to aboveground were also calculated and observed to be in the range of 0.01 to 0.73 for 238U, 0 to 0.99 for 232Th, 0.08 to 1.50 for 226Ra and 0.57 to 1.94 for 40K, respectively. The results showed that, Miscanthus floridulu is 238U and 226Ra-accumulating plant with significant absorption and accumulation characteristics.

On Strong Convergence by the Hybrid Method for Equilibrium and Fixed Point Problems for an Inifnite Family of Asymptotically Nonexpansive Mappings
Gang Cai,Chang song Hu
Fixed Point Theory and Applications , 2009, DOI: 10.1155/2009/798319
Abstract: We introduce two modifications of the Mann iteration, by using the hybrid methods, for equilibrium and fixed point problems for an infinite family of asymptotically nonexpansive mappings in a Hilbert space. Then, we prove that such two sequences converge strongly to a common element of the set of solutions of an equilibrium problem and the set of common fixed points of an infinite family of asymptotically nonexpansive mappings. Our results improve and extend the results announced by many others.
Experiment and Analysis on Flue Gas Low Temperature Corrosion Monitoring  [PDF]
Xiaona Song, Changshun Zhang, Pei Li, Jun Zheng, Yanping Hu, Xiaoxia Hou, Gang Xu
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B262
Abstract:

Thermal loss of exhaust flue gas accounts for the largest proportion of the total boiler thermal loss. Nowadays in China, the exhaust gas temperature in many thermal power plants is much higher than the designed value, thus, the recycle and reuse of the waste heat of tail flue gas is necessary. However, lower exhaust gas temperature will aggravate low temperature corrosion of the tail heating surface, which also causes huge economic losses. In order to solve this problem, this paper designs a monitoring experiment platform of flue gas low temperature corrosion, which can measure the corrosion condition of different materials by different flue gas compositions and temperature corrosion speeds. Besides, effects of low temperature corrosion factors are analyzed to find the best exhaust gas temperature and the surface material of tail heating surface.

Cell Size Dependent Responses of Phytoplankton Assemblages to Nitrate and Phosphate Additions in Surface Waters of the Northern South China Sea  [PDF]
Rong Yi, Yehui Tan, Shengfu Wang, Pingping Shen, Zhixin Ke, Liangmin Huang, Xingyu Song, Gang Li
Open Journal of Marine Science (OJMS) , 2014, DOI: 10.4236/ojms.2014.42008
Abstract:

Bioavailability of nitrogen (N) and phosphorus (P) is known to affect marine phytoplankton physiology, thus influencing their primary productivity; and it’s of general interest to see how the N or/and P additions affect the differently cell-sized phytoplankton assemblages. Data from the northern South China Sea showed that P addition increased up to 6 times of total chl a content within 24 h in the estuarine water; and N+P addition increased more than 20 times of chl a within 144 h in the pelagic water. The P addition powered 18.0% and 149% increase in the carbon fixation of larger (>3 μm) and smaller (<3 μm) cell assemblies from the estuarine water, respectively; while the limited effects were observed between them in the pelagic water. Additions of N and P interactively increased the carbon fixation of both cell-sized assemblies in the pelagic water, but only small cell-sized fraction in the estuarine water. Moreover, the estuarine phytoplankton cells appeared to respond faster to the nutrient additions than the pelagic ones, and the smaller cells respond to a greater extent than their larger counterparts in the estuarine water but not in the pelagic water.

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