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Effect of Media on the Electric Field of a Rhombic Nanostructure Array

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Chinese Physics Letters 2010年第6期27卷 217-220页

作者： ZHU Shao-Li ZHOU Wei Precision Engineering and Nanotechnology Centre School of Mechanical and Aerospace Engineering Nanyang Technological University 50 Nanyang Avenue Singapore 639798

Electric field distribution is an important parameter for nanostructure arrays in nanobiosensing appfications. It can influence the sensitivity and the resolution of nanobiosensors. We focus on the effect of media on the electric field distribution of a rhombic silver nanostructure array. The finite-difference time-domain algorithm- based numerical calculation method is used to monitor the electric field distribution of the silver nanostructures when the refractive index of the medium around the nanostructure array is changed. The calculated results show that tuning the refractive index of the medium around silver can have a considerable influence on the electric field distribution in the reflection and transmission directions. This effect can be used to increase the extinction efficiency and to improve the resolution of the spectra for nanobiosensing.

关键词： ELECTRIC fields NANOSTRUCTURES RHOMBIC antennas BIOSENSORS SENSITIVITY analysis FINITE differences TIME-domain analysis numerical calculations

Measurement of L X-Ray Intensity Ratios for^92U and ^90Th Elements Using Photoionization in an External Magnetic Field

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Chinese Physics Letters 2007年第3期24卷 668-671页

作者： D.Demir Y. Sahin Department of Physics Faculty of Arts and Science Ataturk University 25240 Erzurum Turkey

L x-ray intensity ratios Le/Lγ, Lα/L7 and Lβ/Lγ for ^92U and ^90Th are measured by using 59.5keV incident photon energy at 110° and 125° scattering angles. The samples are located in the external magnetic field of intensities ±0.15T, ±0.30T, ±0.45T, ±0.60T and ±0.75T. The experimental results obtained for B = 0 are compared with the theoretical values calculated using Scofield＇s tables based on the Hartree Slater theory. The contribution to the alignment of the external magnetic field is discussed. It is observed that the L x-ray intensity ratios decrease with the increasing magnetic field intensity.

关键词： PHOTOIONIZATION MAGNETIC fields PHOTONS SCATTERING (Physics) numerical calculations HARTREE-Fock approximation

Characteristics of Wave-Particle Interaction in a Hydrogen Plasma

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Chinese Physics Letters 2008年第9期25卷 3511-3514页

作者：贺慧勇陈良旭厉江帆 School of Physics and Electronic Sciences Changsha University of Science and Technology Changsha 410076 State Key Laboratory of Space Weather PO Box 8701 Beijing 100080

We study the characteristics of cyclotron way,particle interaction in a typical hydrogen plasma. The numerical calculations of minimum resonant energy Emin, resonant wave frequency ω, and pitch angle diffusion coefficient Dαα for interactions between R-mode/L-mode and electrons/protons are presented. It is found that Emin decreases with ω for R-mode/electron, L-mode/proton and L-mode/electron interactions, but increase with ω for R-mode/proton interaction. It is shown that both R-mode and L-mode waves can efficiently scatter energetic （10 keV-100 keV） electrons and protons and cause precipitation loss at L = 4, indicating that perhaps waveparticle interaction is a serious candidate for the ring current decay.

关键词： HYDROGEN plasmas CYCLOTRONS numerical calculations ELECTRONS PROTONS PRECIPITATION (Chemistry) DIFFUSION

Electronic Structure and Elastic Properties of Ti3AlC from First-Principles calculations

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Chinese Physics Letters 2009年第11期26卷 168-170页

作者：杜宇雷 Department of Materials Science and Engineering Nanjing University of Science and Technology Nanjing 210094

We perform a first-principles study on the electronic structure and elastic properties of TiaA1C with an antiperovskite structure. The absence of band gap at the Fermi level and the finite value of the density of states at the Fermi energy reveal the metallic behavior of this compound. The elastic constants of Ti3AlC are derived yielding c11 = 356 GPa, c12 = 55 GPa, c44 = 157 GPa. The bulk modulus B, shear modulus G and Young＇s modulus E are determined to be 156, 151 and 342 GPa, respectively. These properties are compared with those of Ti3AlC2 and Ti2AlC with a layered structure in the Ti-Al-C system and FeaAlC with the same antiperovskite structure.

关键词： ELECTRONIC structure ELASTICITY TITANIUM compounds numerical calculations PEROVSKITE ENERGY gaps (Physics) ENERGY levels (Quantum mechanics)

Large-scale model test study on the water pressure resistance of construction joints of karst tunnel linings

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Frontiers of Structural and Civil Engineering 2023年第8期17卷 1249-1263页

作者： Meng HUANG Mingli HUANG Ze YANG Yuan SONG Zhien ZHANG School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China Enterprise Key Laboratory Tianjin Municipal Engineering Design and Research InstituteTianjin 300392China School of Civil Engineering and Architecture Anhui University of Science and TechnologyHuainan 232001China

Model tests and numerical calculations were adopted based on the New Yuanliangshan tunnel project to investigate the water pressure resistance of lining construction joints in high-pressure and water-rich karst tunnels.A large-scale model test was designed and conducted,innovatively transforming the external water pressure of the lining construction joint into internal water *** effects of the embedded position and waterstop type on the water pressure resistance of the construction joint were analyzed,and the reliability of the model test was verified via numerical *** results show that using waterstops can significantly improve the water pressure resistance of lining construction *** water pressure resistance of the lining construction joint is positively correlated with the lining thickness and embedded depth of the *** addition,the type of waterstop significantly influences the water pressure resistance of lining construction *** test results show that the water pressure resistance of the embedded transverse reinforced waterstop is similar to that of the steel plate waterstop,and both have more advantages than the rubber *** water pressure resistance of the construction joint determined via numerical calculations is similar to the model test results,indicating that the model test results have high accuracy and *** study provides a reference for similar projects and has wide applications.

关键词： karst tunnel lining construction joint water pressure resistance large-scale model test numerical calculations

Schottky Barrier Formation at a Carbon Nanotube-Scandium Junction

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Chinese Physics Letters 2009年第2期26卷 233-235页

作者：何裕张明张进宇王燕余志平 Institute of Microelectronics Tsinghua University Beijing 100084

Recent experiment shows that scandium （Sc） can make a good performance contact with carbon nanotubes （CNTs） to fabricate n-type field effect transistor （n-FET）. We study the Schottky barrier （SB） of scandium （Sc） and palladium （Pd） with a （8,0） single-wall CNT （SWCNT） using first-principles calculation. It is found that the p-type SB height （SBH） of the Pd-CNT contact is about 0.34 eV, which is in good agreement with the experimental data. For the Sc-CNT contact, an n-type contact is formed and the SBH is about O.08eV in agreement with the experimental observations. Our calculation demonstrates that by contacting CNT with Pd and Sc, p-FET and n-FET can be fabricated, respectively. The dipole effect at the interface is used to explain our result.

关键词： SCHOTTKY-barrier diodes CARBON nanotubes SCANDIUM SEMICONDUCTOR junctions FIELD-effect transistors PALLADIUM numerical calculations

Spin Transport in a Magnetic Superlattice with Broken Two-Fold Symmetry

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Chinese Physics Letters 2010年第6期27卷 167-170页

作者： HUO Qiu-Hong WANG Ru-Zhi CHEN Si-Ying XUE Kun YAN Hui Laboratory of Thin Film Materials College of Materials Science and Engineering Beijing University of Technology Beijing 100124 School of Optoelectronics Beijing Institute of Technology Beijing 100081 Australian Research Council Centre of Excellence for Quantum Computer Technology and School of Physics University of New South Wales Sydney New South Wales 2052 Australia

We theoretically investigate the spin-dependent electron transport properties in a magnetic superlattice （MSL） with broken two-fold symmetry. An abnormal barrier in the MSL can break the two-fold symmetry of the system when it is not located at the two-fold symmetry center. A two-fold symmetry breaking factor is introduced to describe the two-fold symmetry breaking degree. Our numerical calculations show that the transmission, the conductance and the spin polarization are non-trivially dependent on the two-fold symmetry breaking factor. When the factor is large enough, the polarization almost approaches 100% in a proper Fermi energy range. However, for two mutually mirror-symmetric MSLs with the same factor, their polarizations may be either similar or distinct. These features provide some clues to the design and applications of MSL-based spin filters or spin-dependent tunneling electron devices.

关键词： ELECTRON transport MAGNETIC materials SUPERLATTICES BROKEN symmetry (Physics) numerical calculations FERMI surfaces TUNNELING (Physics)

Design of a TE10-TE30 Rectangular Mode Converter for 4.6 GHz LHCD Launcher in the Experimental Advanced Superconducting Tokamak

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Chinese Physics Letters 2009年第2期26卷 188-191页

作者：王晓洁刘甫坤赵连敏贾华刘红宝匡光力 Institute of Plasma Physics Chinese Academy of Sciences PO BOX 1126 Hefei 230031

A compact rectangular TE10-TE30 mode converter is developed for the lower hybrid current drive （LHCD） launcher on the Experimental Advanced Superconducting Tokamak （EAST） at 4.6 GHz. The converter with periodic width perturbation aims to divide the microwave power into three sub-waveguides in the poloidal direction. We present the design and numerical calculation of the mode converter. calculations are performed on the ripple wall converter by codes based on numerical solving the coupled-mode differential equations and on the simulation of the High Frequency Structure Simulator （HFSS） package. The resulting conversion efficiency from TE10 mode to TE30 mode exceeds 95% within the bandwidth from 4.56 GHz to 4.64 GHz, and the return loss of the oversized transducer can be considerably decreased to 0.068% by means of a capacitive button embedded in the E-plane of the waveguide.

关键词： ELECTRIC current converters -- Design & construction TOKAMAKS numerical calculations DIFFERENTIAL equations SIMULATION methods & models TRANSDUCERS WAVEGUIDES

Calculation of Higher-Order Foldy-Wouthuysen Transformation Hamiltonian

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Chinese Physics Letters 2014年第6期31卷 77-81页

作者：梅雪松赵树民乔豪学 School of Physics and Technology Wuhan University Wuhan 430072 College of Physics and Technology Hebei University Baoding 071000 Division of Theoretical and Interdisciplinary Research State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071

The Foldy-Wouthuysen Hamiltonian of a light atomic system that has an ma^8 contribution to energy levels is calculated. The case of a Dirac-Coulomb field is discussed. The results can be used for relativistic and radiative corrections to energy levels in the low-energy part. A divergent operator δ^2（r） emerges. This is probably due to the nature of the point-like charge source. The effective method of radiation calculation may be re-checked.

关键词： ATOMIC physics RESEARCH HAMILTONIAN systems HAMILTONIAN graph theory ENERGY levels (Quantum mechanics) QUANTUM theory numerical calculations