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有限长磁偶极线和磁粉探伤——磁粉探伤原理之二 被引量:13
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作者 仲维畅 《无损检测》 北大核心 1991年第4期96-100,共5页
关键词 偶极线 磁粉探伤 浅裂纹
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略论电偶极线 被引量:1
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作者 赵强 《物理与工程》 2016年第2期70-71,共2页
本文首先仿照电偶极子模型的定义给出了电偶极线模型的定义,然后导出了电偶极线的电势公式和电场公式,最后利用电偶极线模型求出了沿垂直于轴方向均匀极化的长圆柱体周围的电场.
关键词 偶极线 线化强度 等效 精确解
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同轴偶极半波天线
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作者 董德春 《曲靖师范学院学报》 1995年第6期35-39,共5页
同轴偶极半波天线是一种性能优良,但又容易制作,成本低廉的天线.本文对它的结构作了简单描述,并应用电磁场理论算出了它的辐射电阻,方向角.作者还通过实验测定了频带宽度.
关键词 同轴半波线 辐射电阻 方向角 频带宽度
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感应法地下管线探测中的一个问题 被引量:3
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作者 阮百尧 《物探与化探》 CAS CSCD 1997年第5期382-385,393,共5页
通过对地下管线中的感应电流形成机理分析,本文认为,当地下介质导电性很差时,地下管线以磁偶极线为主;而当地下介质存在一定的导电性时,管线则等效于电流线。
关键词 电磁感应 地下管线 电流线 偶极线 感应法探测
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Design of a Metasurface Antenna Based on Characteristic Mode Theory
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作者 HE Huan 《电讯技术》 北大核心 2024年第10期1561-1568,共8页
A novel metasurface antenna consisting of 5×5 rectangular patch elements is presented.Thestructure with and without the central element are both analyzed by the Characteristic Mode Theory(CMT).The developed mutua... A novel metasurface antenna consisting of 5×5 rectangular patch elements is presented.Thestructure with and without the central element are both analyzed by the Characteristic Mode Theory(CMT).The developed mutually orthogonal principal modes of the optimized periodic patch structure areexcited by a center-feed dipole.A differential feeding network is employed to realize impedance matching.Prototype with profile height of 0.07λ_(0)(λ_(0)is the wavelength in free space at the lowest operatingfrequency)is fabricated and assembled to verify the simulation results.The measured results show that thereflectance coefficient of proposed matesurface antenna is less than-10 dB in the whole operating bandrange from 4.2 GHz to 5.5 GHz,a relative bandwidth of 26.8%is achieved,and the maximummeasured realized gain is more than 9 dBi with a maximum radiation efficiency of 90%.The designprovides a guideline on the application of characteristic modes(CMs)to radiation problems. 展开更多
关键词 metasurface antenna characteristic mode theory dipole antenna realized gain
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不共轴圆柱形电容器电容的计算 被引量:2
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作者 石东平 《西南民族学院学报(自然科学版)》 1996年第3期363-365,共3页
利用“移荷保场”方法,求得不共轴圆柱形电容器的电容.与保角变换法相比。
关键词 移荷保场 电容 圆柱形电容器 偶极线
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Wideband dipole logging based on segmen linear frequency modulation excitation 被引量:1
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作者 Cao Xue-Shen Chen Hao +3 位作者 Li Ping He Hong-Bin Zhou Yin-Qiu Wang XJu-Ming 《Applied Geophysics》 SCIE CSCD 2018年第2期197-207,362,共12页
A wideband dipole signal is required for dipole dispersion correction and nearborehole imaging. To obtain the broadband flexural wave dispersion, we use a nonlinear frequency modulation (NLFM) signal and propose a s... A wideband dipole signal is required for dipole dispersion correction and nearborehole imaging. To obtain the broadband flexural wave dispersion, we use a nonlinear frequency modulation (NLFM) signal and propose a segment linear frequency modulation (SLFM) signal as the dipole excitation signal to compensate for the excitation intensity. The signal-to-noise ratio (SNR) of the signal over the entire frequency band is increased. The finite-difference method is used to simulate the responses from a Ricker wavelet, a linear frequency modulation (LFM) signal, an NLFM signal, and an SLFM signal in two borehole models of a homogeneously hard formation and a radially stratified formation. The dispersion and radial tomography results at low SNR of the sound source signals are compared. Numerical modeling suggests that the energy of the flexural waves excited by the Ricker wavelet source is concentrated near the Airy phase. In this case, the dispersion is incomplete and information regarding the formation near or far from the borehole cannot be obtained. The LFM signal yields dispersion information near the Airy phase and the high-frequency range but not in the low-frequency range. Moreover, the information regarding the formation far from the borehole is not accurate. The NLFM signal extends the frequency range of the flexural waves by compensating for the excitation intensity and yields information regarding the formation information, but it is not easy to obtain. The SLFM signal yields the same results as the NLFM signal and is easier to implement. Consequently, the dipole detection range expands and the S-wave velocity calculation accuracy improves. 展开更多
关键词 Dipole acoustic logging DISPERSION frequency modulation finite difference
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Fabrication of THz Dipole Antenna Using Lift-off Method
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作者 SHOU Xiang BAI Lu-gang +1 位作者 SU Hong-yan GAN Ben-xin 《Semiconductor Photonics and Technology》 CAS 2009年第4期247-251,共5页
The microfabrication technique for THz dipole antenna,"lift-off" was studied in this paper.Its procedure has been examined in detail,and discreetly tweaked.Particularly,Chlorobenzene is suggested to assist t... The microfabrication technique for THz dipole antenna,"lift-off" was studied in this paper.Its procedure has been examined in detail,and discreetly tweaked.Particularly,Chlorobenzene is suggested to assist the formation of undercut indispensible for fulfilling "lift-off".The experimental results of fabricated antennas confirm the effectiveness of this method. 展开更多
关键词 terahertz dipole antenna LIFT-OFF MICROFABRICATION
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Nonlinear Absorption-Gain Response and Population Dynamics in a Laser-Driven Four-Level Dense Atomic System
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作者 LI Jia-Hua LIU Ji-Bing LUO Jin-Ming XIE Xiao-Tao 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第6期1102-1106,共5页
We theoretically investigate the response of nonlinear absorption and population dynamics in optically dense media of four-level atoms driven by a single-mode probe laser, via taking the density-dependent near dipoled... We theoretically investigate the response of nonlinear absorption and population dynamics in optically dense media of four-level atoms driven by a single-mode probe laser, via taking the density-dependent near dipoledipole (NDD) interactions into consideration. The influence of the NDD effects on the absorption of the probe field and population dynamics is predicted via numerical calculations. It is shown that the NDD effects can reduce gradually to transient absorption with the increase of the strengths of the NDD interactions, and transient amplification can be achieved. In the steady-state limit, the probe field exhibits transparency for strong NDD interactions. Alternatively, the population entirely remains at the ground state due to the NDD effects. 展开更多
关键词 absorption spectra population dynamics near dipole-dipole interactions
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Nonlinear Absorption and Dispersion Response in Optically Dense Media Driven by a Single-Mode Laser
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作者 LI Jia-Hua LIU Ji-Bing XIE Xiao-Tao LUO Jin-Ming 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第1X期130-134,共5页
Taking the density-dependent near dipole-dipole (NDD) interaction into consideration, we theoretically investigate the response of nonlinear absorption and dispersion in optically dense media of three-level atoms dr... Taking the density-dependent near dipole-dipole (NDD) interaction into consideration, we theoretically investigate the response of nonlinear absorption and dispersion in optically dense media of three-level atoms driven by a single-mode probe laser. The influence of the NDD effects on the absorption and dispersion spectra of the probe field is predicted via numerical calculations. It is shown that the NDD effects reduce gradually to transient absorption and amplification with the increase of the strengths of the NDD interaction, but do not change the steady-state behavior. Due to the presence of the NDD effects, steady-state absorption spectra exhibit asymmetric double-peak structure and overall shifts when a continuous-wave (cw) probe field is applied. However, frequency dispersion spectra are insensitive to them near the zero detuning. 展开更多
关键词 absorption spectra dispersion spectra near dipole-dipole interactions
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A Detailed Study of Pre-scission γ Emission as a Probe of Nuclear Dissipation
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作者 WU Feng YE Wei CHEN Na 《Communications in Theoretical Physics》 SCIE CAS CSCD 2007年第4X期710-712,共3页
Using a Langevin equation coupled with a statistical model, we calculate pre-scission giant dipole resonance (GDR) γ-ray multiplicity of nuclei 194 pb, 200Pb, 206Pb, and 200 Os. It is demonstrated that with increas... Using a Langevin equation coupled with a statistical model, we calculate pre-scission giant dipole resonance (GDR) γ-ray multiplicity of nuclei 194 pb, 200Pb, 206Pb, and 200 Os. It is demonstrated that with increasing the isospin asymmetry of these fissioning nuclei the sensitivity of the emitted γ multiplicity to the nuclear viscosity coefficient is decreased significantly. For 200Os nuc/eus, this γ-ray emission is no longer sensitive to the magnitude of the viscosity coefficient. In addition, the effect of the isospin asymmetry on the γ rays as a probe of nuclear dissipation is reduced with increasing angular momentum. These results suggest that to obtain a more accurate information of the viscosity coemfficient by the measurement of pre-scission GDR γ-ray multiplicity it is better to choose those compound systems with small isospin asymmetry and low spin. 展开更多
关键词 giant dipole resonance γ-ray multiplicity nuclear dissipation isospin asymmetry effect Langevin equation
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Ab Initio Calculation on Spectroscopic Properties and Radiative Lifetimes of Low-Lying Excited States of NaK
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作者 Shi-yang Zhang Feng Xie +5 位作者 Feng-dong Jia Xiao-kang Li Ru-quan Wang Rui Li Yong Wu Zhi-ping Zhong 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2019年第6期667-673,I0002,共8页
We performed high-level ab initio calculations on electronic structure of Na K. The potential energy curves (PECs) of 10 Λ-S states correlated with the three lowest dissociation limits have been calculated. On the ba... We performed high-level ab initio calculations on electronic structure of Na K. The potential energy curves (PECs) of 10 Λ-S states correlated with the three lowest dissociation limits have been calculated. On the basis of the calculated PECs, the spectroscopic constants of the boundΛ-S states are obtained, which are in good agreement with experimental results. The maximum vibrational quantum numbers of the singlet ground state X^1Σ^+ and the triplet ground state a^3Σ^+ have been analyzed with the semiclassical scattering theory. Transition properties including transition dipole moments, Franck-Condon factors, and radiative lifetimes have been investigated. The research results indicate that such calculations can provide fairly reliable estimation of parameters for the ultracold alkali diatomic molecular experiment. 展开更多
关键词 Ultracold dipolar molecule Transition dipole moment Spectroscopic constants Potential curves
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Reflecting and transmitting effect of a planar unidirectionally conducting screen
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作者 鄂鹏 江滨浩 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2009年第2期242-246,共5页
The reflecting and transmitting effects of a planar unidirectionally conducting screen are analyzed based on the accurate closed-form expression for electric field of an arbitrarily oriented electric dipole.For a dipo... The reflecting and transmitting effects of a planar unidirectionally conducting screen are analyzed based on the accurate closed-form expression for electric field of an arbitrarily oriented electric dipole.For a dipole oriented along the wire elements of the screen,the screen acts as a perfectly electrically conducting plane.For a dipole perpendicular to the wire elements,the fields reflected by the screen can be interpreted as the contribution of an image dipole and image transmission-line current source,while the transmitted field is arisen from image transmission-line source.The expressions of related surface waves are derived and can be compared with previous results. 展开更多
关键词 electromagnetic fields unidirectionally conducting screen reflection and transmission electric dipole
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An equivalent magnetic dipoles model for quantitative damage recognition of broken wire
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作者 谭继文 战卫侠 +2 位作者 李春静 文妍 舒杰 《Journal of Coal Science & Engineering(China)》 2005年第2期99-102,共4页
By simplifying saturatedly magnetized wire-rope to magnetic dipoles of the same magnetic field strength, an equivalent magnetic dipoles model is developed and the measuring principle for recognising damage of broken w... By simplifying saturatedly magnetized wire-rope to magnetic dipoles of the same magnetic field strength, an equivalent magnetic dipoles model is developed and the measuring principle for recognising damage of broken wire was presented. The relevant calculation formulas were also deduced. A composite solution method about nonlinear optimization was given. An example was given to illustrate the use of the equivalent magnetic dipoles method for quantitative damage recognition, and demonstrates that the result of this method is consistent with the real situation, so the method is valid and practical. wire-rope, damage of broken wires, quantitative recognition, equivalent magnetic dipoles, simulate 展开更多
关键词 wire-rope damage of broken wires quantitative recognition equivalent magnetic dipoles simulate
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两圆柱形带电导体周围的静电场
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作者 吴慧能 顾国锋 《广西物理》 2004年第3期22-24,27,共4页
运用配置法讨论两无限长平行圆柱形带电导体周围的静电场 ,导出其电势及导体表面的电荷面密度 。
关键词 静电场 圆柱形导体 配置法 偶极线 电势 电荷面密度 电容
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Study on HPM Power Measurement by Dipole Aatenna 被引量:2
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作者 周恒 樊玉伟 舒挺 《Chinese Physics C》 SCIE CAS CSCD 北大核心 2008年第z1期307-309,共3页
In order to reduce the gain of a receiving antenna in HPM power measurement,especially in lower frequency, a low gain dipole antenna of L band is designed.By theoretical analysis and numerical simulation,the optimized... In order to reduce the gain of a receiving antenna in HPM power measurement,especially in lower frequency, a low gain dipole antenna of L band is designed.By theoretical analysis and numerical simulation,the optimized results of the antenn are obtained:its central frequency is 1.75GHz,the variety of gain is less than 1.1dB in frequency band 1.70—1.80GHz,the estimated value of the power capacity of the antenna is 0.1MW,which can satisfy the demand of corresponding measurement. 展开更多
关键词 HPM dipole attenna GAIN power capacity
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Analysis of dipole-like ultra high frequency RFID tags close to metallic surfaces 被引量:3
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作者 Ling-fei MO Hong-jian ZHANG Hong-liang ZHOU 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2009年第8期1217-1222,共6页
It is a challenge for passive RFID tags to be mounted on the surface of metal because the parameters of tag antennas,such as the impedance matching,the radiation efficiency and the radiation pattern,are seriously affe... It is a challenge for passive RFID tags to be mounted on the surface of metal because the parameters of tag antennas,such as the impedance matching,the radiation efficiency and the radiation pattern,are seriously affected by the metallic surface.This paper presents the characteristics of the dipole-like antennas of ultra high frequency(UHF) radio frequency identification(RFID) tags that are placed close to metallic surfaces.The finite element method(FEM) and method of moment(MoM) were used to simulate the changes of the antenna parameters near the metallic surface.Two typical dipole-like antennas close to the metallic surface,a closed loop antenna and a loaded meander antenna,were modeled,and the performance was evaluated.Experiment was carried out and the results were in good agreement with the simulation,showing that a distance of 0.05λ~0.1λ(λ is the free space wavelength) from the metallic surface could make the dipole-like UHF RFID tag performance be acceptable. 展开更多
关键词 Radio frequency identification (RFID) TAG Metallic surface Finite element method (FEM) Method of moment (MoM)
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Characteristics of on-chip dipole antenna using diamond for intra-chip wireless interconnect
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作者 HE XiaoWei ZHANG MinXuan LI JinWen 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第4期1035-1043,共9页
In this paper,a 2-mm long on-chip dipole antenna pair on silicon substrate is simulated to investigate the transmission characteristics.A novel technique is proposed by employing a 0.35-mm thick diamond layer between ... In this paper,a 2-mm long on-chip dipole antenna pair on silicon substrate is simulated to investigate the transmission characteristics.A novel technique is proposed by employing a 0.35-mm thick diamond layer between silicon substrate and heat sink to improve antenna performance.The simulated transmission gain of this antenna pair with 1 mm separation on a 10-Ω cm silicon substrate increases by 9 dB at 20 GHz.A modified plane wave model involving diamond layer is also presented to explain gain improvement.Effects of dielectric variety,diamond thickness,substrate resistivity and antenna pair separation on transmission gain have been studied.The results indicate that thinner diamond layer along with high resistivity substrate is preferred.Our method makes integrated dipole antennas well suitable for intra-chip wireless interconnection which is known as a future solution to replace critical wiring interconnection. 展开更多
关键词 dipole antenna DIAMOND transmission gain wireless interconnect
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Dynamics of Charged Particles Around a Magnetized Black Hole with Pseudo–Newtonian Potential
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作者 王颖 伍歆 孙威 《Communications in Theoretical Physics》 SCIE CAS CSCD 2013年第10期433-438,共6页
The linear stability of equilibria of charged particles moving near a compact object with a dipole magnetic field and a pseudo-Newtonian potential is analyzed detalledly. An optimal fourth-order force gradient symplec... The linear stability of equilibria of charged particles moving near a compact object with a dipole magnetic field and a pseudo-Newtonian potential is analyzed detalledly. An optimal fourth-order force gradient symplectic method, as a global symplectic integrator that can simultaneously solve both the equations of motion and the variational equations, is used to calculate fast Lyapunov indicators. In this way, dynamical structures are described, and parameter domains for causing chaos are found. 展开更多
关键词 pseudo-Newtonian potential CHAOS symplectic integrator
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An Accurate Calculation of Potential Energy Curves and Transition Dipole Moment for Low-Lying Electronic States of CO
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作者 芦鹏飞 闫磊 +2 位作者 俞重远 高玉峰 高涛 《Communications in Theoretical Physics》 SCIE CAS CSCD 2013年第2期193-198,共6页
In this paper, potential energy curves for the X1∑+, a3П, a'∑+, da△, A1П and I∑- states of CO have been calculated using complete active space se1f-consistent field and multi-reference configuration interacti... In this paper, potential energy curves for the X1∑+, a3П, a'∑+, da△, A1П and I∑- states of CO have been calculated using complete active space se1f-consistent field and multi-reference configuration interaction methods. The calculations have been performed at 108 nuclear separations from 0.7 to 4.0 A by the aug-cc-PVSZ basis set. Spectroscopic constants for the six low-lying electronic states are found in good agreement with experimental data. The vibrational states of the X1∑+ and A1П states are also calculated, which are reliable and accurate by comparison with the experimental data and the other theoretical values. The transition dipole moment (TDM) shows that the TDM of the two states (X1∑+→A1П)are reduced strongly with increase of bond length. 展开更多
关键词 potential energy curves transition dipole moment electronic state
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