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Use of 3-D magnetic resonance electrical impedance tomography in detecting human cerebral stroke: a simulation study 被引量:2
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作者 高诺 朱善安 贺斌 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE EI CAS CSCD 2005年第5期438-445,共8页
We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electri... We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electrical Impedance Tomography (MREIT) approach is based on the J-Substitution algorithm and is expanded to imaging 3-D subject conductivity distribution changes. Computer simulation studies have been conducted to evaluate the present MREIT imaging approach. Simulations of both types of cerebral stroke, hemorrhagic stroke and ischemic stroke, were performed on a four-sphere head model. Simulation results showed that the correlation coefficient (CC) and relative error (RE) between target and estimated conductivity distributions were 0.9245±0.0068 and 8.9997%±0.0084%, for hemorrhagic stroke, and 0.6748±0.0197 and 8.8986%±0.0089%, for ischemic stroke, when the SNR (signal-to-noise radio) of added GWN (Gaussian White Noise) was 40. The convergence characteristic was also evaluated according to the changes of CC and RE with different iteration numbers. The CC increases and RE decreases monotonously with the increasing number of iterations. The present simulation results show the feasibility of the proposed 3-D MREIT approach in hemorrhagic and ischemic stroke detection and suggest that the method may become a useful alternative in clinical diagnosis of acute cerebral stroke in humans. 展开更多
关键词 Magnetic resonance electrical Impedance Tomography CONDUCTIVITY Acute cerebral stroke Hemorrhagic stroke Ischemic stroke Current density imaging
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Polarization-Insensitive Magnetic Quadrupole-Shaped and Electric Quadrupole-Shaped Fano Resonances Based on a Plasmonic Composite Structure 被引量:1
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作者 董晨 李宝 +5 位作者 李韩笑 刘慧 陈孟琪 李冬冬 闫长春 张道华 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第7期68-71,共4页
A combined structure with the unit cell consisting of four sub-units with 90° rotation in turn is designed. Each of sub-units is composed of two gold rods in transverse arrangement and one gold rod in longitudina... A combined structure with the unit cell consisting of four sub-units with 90° rotation in turn is designed. Each of sub-units is composed of two gold rods in transverse arrangement and one gold rod in longitudinal arrangement. Simulating electromagnetic responses of the structure, we verify that the structure exhibits the double Fano resonances, which originate from the coupling between magnetic quadrupoles and electric dipoles and the coupling between electric quadrupoles and electric dipoles. Simulation results also demonstrate that the structure is polarization-insensitive and shows an analogue of electromagnetically induced transparency at the two Fano resonances. Such a plasmonic structure has potential applications in photoelectric elements. 展开更多
关键词 of is it in Polarization-Insensitive Magnetic Quadrupole-Shaped and electric Quadrupole-Shaped Fano resonances Based on a Plasmonic Composite Structure MODE that on
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Electricity resonance-induced phase transition of water confined in nanochannels
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作者 Yunqiu Ma Zhigao Zhao +2 位作者 Shaoqian Hao Jianlong Kou Jiang-Xing Chen 《Communications in Theoretical Physics》 SCIE CAS CSCD 2024年第5期159-165,共7页
The phase transition of water molecules in nanochannels under varying external electric fields is studied by molecular dynamics simulations.It is found that the phase transition of water molecules in nanochannels occu... The phase transition of water molecules in nanochannels under varying external electric fields is studied by molecular dynamics simulations.It is found that the phase transition of water molecules in nanochannels occurs by changing the frequency of the varying electric field.Water molecules maintain the ice phase when the frequency of the varying electric field is less than 16 THz or greater than 30 THz,and they completely melt when the frequency of the varying electric field is 24 THz.This phenomenon is attributed to the breaking of hydrogen bonds when the frequency of the varying electric field is close to their inherent resonant frequency.Moreover,the study demonstrates that the critical frequency varies with the confinement situation.The new mechanism of regulating the phase transition of water molecules in nanochannels revealed in this study provides a perspective for further understanding of the phase transition of water molecules in nanochannels,and has great application potential in preventing icing and deicing. 展开更多
关键词 electricity resonance phase transition water molecules molecular dynamics simulations
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A quantum-enhanced magnetometer using a single high-spin nucleus in silicon
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作者 Tao Xin Ke Zhang Jun Li 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第9期110-115,共6页
Quantum enhanced metrology has the potential to go beyond the standard quantum limit and eventually to the ultimate Heisenberg bound.In particular,quantum probes prepared in nonclassical coherent states have recently ... Quantum enhanced metrology has the potential to go beyond the standard quantum limit and eventually to the ultimate Heisenberg bound.In particular,quantum probes prepared in nonclassical coherent states have recently been recognized as a useful resource for metrology.Hence,there has been considerable interest in constructing magnetic quantum sensors that combine high resolution and high sensitivity.Here,we explore a nanoscale magnetometer with quantum-enhanced sensitivity,based on 123Sb(I=7/2)nuclear spin doped in silicon,that takes advantage of techniques of spin-squeezing and coherent control.With the optimal squeezed initial state,the magnetic field sensitivity may be expected to approach 6 aT·Hz^(−1/2)·cm^(−3/2) and 603 nT·Hz^(−1/2) at the single-spin level.This magnetic sensor may provide a novel sensitive and high-resolution route to microscopic mapping of magnetic fields as well as other applications. 展开更多
关键词 quantum magnetometer silicon quantum qubit nuclear electrical resonance
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A planar left-handed metamaterial based on electric resonators 被引量:1
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作者 陈春晖 屈绍波 +3 位作者 王甲富 马华 王新华 徐卓 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第3期210-215,共6页
A planar left-handed metamaterial(LHM) composed of electric resonator pairs is presented in this paper. Theoretical analysis, an equivalent circuit model and simulated results of a wedge sample show that this materi... A planar left-handed metamaterial(LHM) composed of electric resonator pairs is presented in this paper. Theoretical analysis, an equivalent circuit model and simulated results of a wedge sample show that this material exhibits a negative refraction pass-band around 9.6GHz under normal-incidence and is insensitive to a change in incidence angle. Furthermore, as the angle between the arm of the electric resonators and the strip connecting the arms increases, the frequency range of the pass-band shifts downwards. Consequently, this LHM guarantees a relatively stable torlerence of errors when it is practically fabricated. Moreover, it is a candidate for designing multi-band LHM through combining the resonator pairs with different angles. 展开更多
关键词 planar left-handed metamaterial electric resonator multi-band metamaterial
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Triad resonant wave interactions in electrically charged jets
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作者 S.ORIZAGA D.N.RIAHI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2017年第8期1127-1148,共22页
Nonlinear instability in electrically charged jets is studied using the governing electro-hydrodynamic equations describing stretching and thinning of a liquid jet. A jet flow system subject to both space and time evo... Nonlinear instability in electrically charged jets is studied using the governing electro-hydrodynamic equations describing stretching and thinning of a liquid jet. A jet flow system subject to both space and time evolving disturbances is considered. At the linear stage, the Rayleigh and conducting jet flow instability modes are uncovered.Nonlinear instability in the flow is explored via triad resonant waves which uncover favorable operating modes not previously detected in the linear study of the problem. In particular, the jet radius is significantly reduced, and the electric field of the jet is properly oriented under the nonlinear study. It is found that taking into account the resonance triad modes provides a better mathematical description of a jet that stretches and thins due to tangential electric field effects. Both linear and nonlinear instability results in the jet flow system are presented and discussed. 展开更多
关键词 electrically resonant instability hydrodynamic triad Rayleigh governing thinning radius favorable
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Metamaterial absorbers realized in an X-band rectangular waveguide
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作者 黄勇军 文光俊 +5 位作者 李建 钟靖平 王平 孙元华 O.Gordon 朱卫仁 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第11期474-478,共5页
In this paper, we demonstrate six types of metamaterial absorbers (MMAs) by measuring their absorptivities in an X-band (8 12 GHz) rectangular waveguide. Some of the MMAs have been demonstrated previously by using... In this paper, we demonstrate six types of metamaterial absorbers (MMAs) by measuring their absorptivities in an X-band (8 12 GHz) rectangular waveguide. Some of the MMAs have been demonstrated previously by using the free space measurement method, and the others are proposed firstly in this paper. The measured results show that all of the six MMAs exhibit high absorptivities above 98%, which have similar absorbing characteristics to those measured in the free space. The numerically obtained surface current densities for each MMA show that the absorbing mechanism is the same as that under the free space conditions. Such a demonstration method is superior to the conventional free space measurement method due to the small-scale test samples required, the simple measure device, and its low cost. Most importantly, the proposed method opens a way to enable MMAs to be used in microwave applications such as matched terminations. 展开更多
关键词 METAMATERIAL ABSORBER electric resonator rectangular waveguide
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Broadband visible light absorber based on ultrathin semiconductor nanostructures
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作者 Lin-Jin Huang Jia-Qi Li Man-Yi Lu +2 位作者 Yan-Quan Chen Hong-Ji Zhu Hai-Ying Liu 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第1期254-259,共6页
It is desirable to have electromagnetic wave absorbers with ultrathin structural thickness and broader spectral absorption bandwidth with numerous applications in optoelectronics.In this paper,we theoretically propose... It is desirable to have electromagnetic wave absorbers with ultrathin structural thickness and broader spectral absorption bandwidth with numerous applications in optoelectronics.In this paper,we theoretically propose and numerically demonstrate a novel ultrathin nanostructure absorber composed of semiconductor nanoring array and a uniform gold substrate.The results show that the absorption covers the entire visible light region,achieving an average absorption rate more than 90%in a wavelength range from 300 nm to 740 nm and a nearly perfect absorption from 450 nm to 500 nm,and the polarization insensitivity performance is particularly great.The absorption performance is mainly caused by the electrical resonance and magnetic resonance of semiconductor nanoring array as well as the field coupling effects.Our designed broadband visible light absorber has wide application prospects in the fields of thermal photovoltaics and photodetectors. 展开更多
关键词 ultrathin nanostructures electrical resonance magnetic resonance polarization insensitivity
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Harmonic suppressed bandpass filter using composite right/left handed transmission line 被引量:1
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作者 Jian-gang LIANG He-xiu XU 《Journal of Zhejiang University-Science C(Computers and Electronics)》 SCIE EI 2012年第7期552-558,共7页
A wideband composite right/left handed transmission line (CRLH TL) in conjunction with its corresponding equivalent circuit model is studied based on a cascaded complementary single split ring resonator (CCSSRR).The c... A wideband composite right/left handed transmission line (CRLH TL) in conjunction with its corresponding equivalent circuit model is studied based on a cascaded complementary single split ring resonator (CCSSRR).The characterization is performed by theory analysis,circuit simulation,and full-wave electromagnetic (EM) simulation.The negative refractive index (NRI) and backward wave propagation performance of the CRLH TL are demonstrated.For application,a bandpass filter (BPF) with enhanced out-of-band selectivity and harmonic suppression operating at the wireless local area network (WLAN) band is designed,fabricated,and measured by combining the CRLH TL with a complementary electric inductive-capacitive resonator (CELC).Three CELC cells with wideband stopband performance in the conductor strip and ground plane,respectively,are utilized in terms of single negative permeability.The design concept has been verified by the measurement data. 展开更多
关键词 Composite right/left handed transmission line Cascaded complementary split single ring resonator Bandpass filter Complementary electric inductive-capacitive resonator (CELC) Negative permeability
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