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Search Results: 1 - 10 of 47659 matches for " Si Wu "
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Computational neuroscience in China
Si Wu,PeiJi Liang
Science China Life Sciences , 2010, DOI: 10.1007/s11427-010-0063-y
Abstract: The ultimate goal of Computational Neuroscience (CNS) is to use and develop mathematical models and approaches to elucidate brain functions. CNS is a young and highly multidisciplinary field. It heavily interacts with experimental neuroscience and such other research areas as artificial intelligence, robotics, computer vision, information science and machine learning. This paper reviews the history of CNS in China, its current status and the prospects for its future development. Examples of CNS research in China are also presented.
Soliton Wall Superlattice in Quasi-One-Dimensional Conductor (Per)2Pt(mnt)2
A. G. Lebed,Si Wu
Physics , 2007, DOI: 10.1103/PhysRevLett.99.026402
Abstract: We suggest a model to explain the appearance of a high resistance high magnetic field charge-density-wave (CDW) phase, discovered by D. Graf et al. [Phys. Rev. Lett. v. 93, 076406 (2004)] in (Per)2Pt(mnt)2. In particular, we show that the Pauli spin-splitting effects improve the nesting properties of a realistic quasi-one-dimensional electron spectrum and, therefore, a high resistance Peierls CDW phase is stabilized in high magnetic fields. In low and very high magnetic fields, a periodic soliton wall superlattice (SWS) phase is found to be a ground state. We suggest experimental studies of the predicted phase transitions between the Peierls and SWS CDW phases in (Per)2Pt(mnt)2 to discover a unique SWS phase.
Unification Theory of Angular Magnetoresistance Oscillations in Quasi-One-Dimensional Conductors
Si Wu,A. G. Lebed
Physics , 2010, DOI: 10.1103/PhysRevB.82.075123
Abstract: We present a unification theory of angular magnetoresistance oscillations, experimentally observed in quasi-one-dimensional organic conductors, by solving the Boltzmann kinetic equation in the extended Brillouin zone. We find that, at commensurate directions of a magnetic field, resistivity exhibits strong minima. In two limiting cases, our general solution reduces to the results, previously obtained for the Lebed Magic Angles and Lee-Naughton-Lebed oscillations. We demonstrate that our theoretical results are in good qualitative and quantitative agreement with the existing measurements of resistivity in (TMTSF)$_2$ClO$_4$ conductor.
Soliton Wall Superlattice Charge-Density-Wave Phase in Quasi-One-Dimensional Conductor (Per)$_2$Pt(mnt)$_2$
Si Wu,A. G. Lebed
Physics , 2009, DOI: 10.1103/PhysRevB.80.035128
Abstract: We demonstrate that the Pauli spin-splitting effects in a magnetic field improve nesting properties of a realistic quasi-one-dimensional electron spectrum. As a result, a high resistance Peierls charge-density-wave (CDW) phase is stabilized in high enough magnetic fields in (Per)$_2$Pt(mnt)$_2$ conductor. We show that, in low and very high magnetic fields, the Pauli spin-splitting effects lead to a stabilization of a soliton wall superlattice (SWS) CDW phase, which is characterized by periodically arranged soliton and anti-soliton walls. We suggest experimental studies of the predicted first order phase transitions between the Peierls and SWS phases to discover a unique SWS phase. It is important that, in the absence of a magnetic field and in a limit of very high magnetic fields, the suggested model is equivalent to the exactly solvable model of Brazovskii, Dzyaloshinskii, and Kirova.
Larkin-Ovchinnikov-Fulde-Ferrell phase in the superconductor (TMTSF)2ClO4: Theory versus experiment
A. G. Lebed,Si Wu
Physics , 2010, DOI: 10.1103/PhysRevA.82.012504
Abstract: We consider a formation of the Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) phase in a quasi-one-dimensional (Q1D) conductor in a magnetic field, parallel to its conducting chains, where we take into account both the paramagnetic spin-splitting and orbital destructive effects against superconductivity. We show that, due to a relative weakness of the orbital effects in a Q1D case, the LOFF phase appears in (TMTSF)$_2$ClO$_4$ superconductor for real values of its Q1D band parameters. We compare our theoretical calculations with the recent experimental data by Y. Maeno's group [S. Yonezawa et al., Phys. Rev. Lett. \textbf{100}, 117002 (2008)] and show that there is a good qualitative and quantitative agreement between the theory and experimental data.
Development of Roller Ends Forced-Contact Model and Cambering Technology for UCM Temper Mill (I)——Development of Roller Ends Forced-Contact Model and the Computational Model of Flatness for UCM temper mill  [PDF]
Zhenhua Bai, Hongxin Si, Xiaodong Shi, Linfang Han, Ruibing Long, Shoumin Wu, Xiujun Li, Dongdong Zhang
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.37088
Abstract: Roller ends forced-contact and overmuch roll consumption are the widespread problems in temper rolling process of thin strip for two-stand UCM temper mill. Fully thinking the equipment and technology characteristics of UCM temper mill, we took the newly-built 1220 UCM temper mill of Baosteel as the research object in this paper. A model of roller ends forced-contact and a calculation model of flatness for UCM temper mill are established after a great deal of site tracing and theoretical researches. On this basis, an optimal mathematical model of roll shape which is suited for UCM temper mill is developed. Working roll curve is the combination of cosine curve and high order curve. The cosine subentry is used to control edge wave, the high order curve subentry is used to control roller ends forced-contact. Furthermore, the chamfering curve of middle roller end is optimized. Those are the innovations. Through the above-mentioned technology, pressure distribution between rollers caused by the shift of middle roll becomes more homogeneous, pressure peak disappeared, working life of roll is improved effectively as well. Relevant technologies have been used to the practice of 1220 UCM temper mill of Baosteel and have achieved good use effects, which is of further extending application value [1].
Development of Roller Ends Forced-Contact Model and Cambering Technology for UCM Temper Mill (II)——Development of cambering technology for UCM temper mill  [PDF]
Zhenhua Bai, Xiaodong Shi, Hongxin Si, Linfang Han, Ruibing Long, Shoumin Wu, Xiujun Li, Dongdong Zhang
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.37089
Abstract: Roller ends forced-contact and overmuch roll consumption are the widespread problems in temper rolling process of thin strip for two-stand UCM temper mill. Fully thinking the equipment and technology characteristics of UCM temper mill, we took the newly-built 1220 UCM temper mill of Baosteel as the research object in this paper. A model of roller ends forced-contact and a calculation model of flatness for UCM temper mill are established after a great deal of site tracing and theoretical researches. On this basis, an optimal mathematical model of roll shape which is suited for UCM temper mill is developed. Working roll curve is the combination of cosine curve and high order curve. The cosine subentry is used to control edge wave, the high order curve subentry is used to control roller ends forced-contact. Furthermore, the chamfering curve of middle roller end is optimized. Those are the innovations. Through the above-mentioned technology, pressure distribution between rollers caused by the shift of middle roll becomes more homogeneous, pressure peak disappeared, working life of roll is improved effectively as well. Relevant technologies have been used to the practice of 1220 UCM temper mill of Baosteel and have achieved good use effects, which is of further extending application value.
Reflection into China’s Business English Teaching Practices Based on GDUFS Graduates’ Employment Status
Wenzhong Zhu,Si Wu,Tingting Guo
International Education Studies , 2009, DOI: 10.5539/ies.v2n3p30
Abstract: GDUFS, as one of China’s top three foreign language universities with the longest history in business English teaching, has accumulated over 20-year experiences in this discipline. This research reflects into its business English teaching practices based on its graduates’ employment status in recent years, and concludes that the students of business English major tend to have higher level of employment status than those of other majors, and their employers are more likely to be consultancy MNCs, commercial banks and other firms. It is suggested that new efforts for reform should be made in disciplinary development, teaching development, curriculum designs and teaching methods.
Effect of Different Irradiation Times on the Occlusion of Dentinal Tubules When Using a Nd:YAG Laser: An in Vitro SEM Study  [PDF]
Xiaoyu Guo, Jinhua Yu, Roger J. Smales, Huifen Chen, Haiyan Si, Younong Wu
Open Journal of Stomatology (OJST) , 2015, DOI: 10.4236/ojst.2015.53011
Abstract: Objective: To evaluate the effect of different irradiation times on the occlusion of dentinal tubules when using Nd:YAG laser. Background data: Dentin hypersensitivity is a frequent problem that has limited treatment success despite many chemical and physical therapies. Methods: Four coronal dentin disks 2 mm thick were cut with a low-speed diamond saw from four freshly extracted intact first molars. The coronal dentin surface of each disk was divided into four regions, each approximately 2 mm × 3 mm. The dentin surfaces were treated with 27% EDTA then the four regions irradiated separately in a randomized pattern with a Nd:YAG laser (120 mJ, 5 Hz), using irradiation times of 0 s, 20 s, 40 s and 60 s, representing laser energies of 0 J/cm2, 200 J/cm2, 400 J/cm2 and 600 J/cm2, respectively. SEM photomicro-graphs were taken at 1500× and 3000× to calculate the dentinal tubule orifice occlusion rates and to measure the tubule diameters, respectively. Results: For the laser irradiation times of 0 s, 20 s, 40 s and 60 s, the corresponding dentinal tubule occlusion rates were 2.05 (SD 0.29)%, 10.01 (1.71)%, 23.58 (2.51)% and 90.23 (2.24)%, respectively; and the tubule diameters were 4.18 (0.32) μm, 3.46 (0.24) μm, 1.69 (0.32) μm and 0.12 (0.02) μm, respectively. There were significant differences among all groups for both measured variables (p ≤ 0.005). Conclusions: Within the limitations of this in Vitro study, when using a Nd:YAG laser at 120 mJ and 5 Hz, an irradiation time of 60 s achieved the best sealing of the coronal dentinal tubule orifices.
Graphene: Kinks, Superlattices, Landau levels, and Magnetotransport
Matthew Killi,Si Wu,Arun Paramekanti
Physics , 2012, DOI: 10.1142/S0217979212420076
Abstract: We review recent work on superlattices in monolayer and bilayer graphene. We highlight the role of the quasiparticle chirality in generating new Dirac fermion modes with tunable anisotropic velocities in one dimensional (1D) superlattices in both monolayer and bilayer graphene. We discuss the structure of the Landau levels and magnetotransport in such superlattices over a wide range of perpendicular (orbital) magnetic fields. In monolayer graphene, we show that an orbital magnetic field can reverse the anisotropy of the transport imposed by the superlattice potential, suggesting possible switching-type device applications. We also consider topological modes localized at a kink in an electric field applied perpendicular to bilayer graphene, and show how interactions convert these modes into a two-band Luttinger liquid with tunable Luttinger parameters. The band structures of electric field superlattices in bilayer graphene (with or without a magnetic field) are shown to arise naturally from a coupled array of such topological modes. We briefly review some bandstructure results for 2D superlattices. We conclude with a discussion of recent tunneling and transport experiments and point out open issues.
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