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COMPACT BROADBAND END-FIRE ANTENNA WITH METAMATERIAL TRANSMISSION LINE
摘要： A broadband end-?re antenna loaded with magneto-electro-dielectric metamaterial (MED-MTM) is presented in this paper. Based on a planar printed structure, many periodic structures are investigated in antenna design. The metal patch is embedded with a C-shaped complementary split-ring resonator (CSRR) array, and many cross slots are etched on the ground plane. The zeroth-order resonance (ZOR) and ?rst-order resonance (FOR) can be excited. As a result of electromagnetic coupling e?ect, the C-shaped patch and ground plane compose metamaterial transmission line (MTL). For potential applications, the broadband and end-?re antenna can work with a 53.5% (3.81–6.59 GHz) impedance bandwidth. The proposed antenna achieves size reduction, gain improvement and bandwidth enhancement.
关键词： transmission line,end-?re antenna,ZOR,FOR,CSRR,metamaterial,broadband
更新于2025-09-10 09:29:36
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Fast method for analysing nonlinear composite right/left-handed transmission lines based on finite-difference time-domain method
摘要： In this study, a new finite-difference time-domain (FDTD) scheme is presented for analysing nonlinear composite right/left-handed (CRLH) transmission lines, with reduction of the central processing unit time. A step by step analysis is demonstrated to solve the equations for nonlinear CRLH transmission lines based on the FDTD method. The proposed method is applied to a nonlinear CRLH transmission line as an example and the results are confirmed by those of the conventional FDTD method. The comparisons reveal that the presented solution efficiently decreases by about 82% of the computational time consumption.
关键词： finite-difference time-domain (FDTD),computational time reduction,nonlinear composite right/left-handed (CRLH) transmission lines
更新于2025-09-10 09:29:36
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Characterization of grain boundary disconnections in SrTiO3 part I: the dislocation component of grain boundary disconnections
摘要： High-resolution transmission electron microscopy is often used to characterize grain boundaries, but it is usually limited to special high symmetry boundaries with a high density of coincident sites. For these ‘special’ boundaries, both crystals can be brought into a low-index zone-axis with the boundary plane parallel to the incident electron beam. In this case the atomistic structure of the boundary can be solved, which is not possible for other, more general grain boundaries. In the present study, general grain boundaries in SrTiO3 were analyzed using aberration-corrected transmission electron microscopy and scanning transmission electron microscopy. These boundaries included at least one type of disconnection (i.e., defects that can have a step and/or a dislocation component). Since the dislocation component of disconnections along general grain boundaries cannot be fully resolved using the methods currently available, a plane matching approach was used to compare disconnections at different boundaries. Using this approach, the dislocation component of the disconnections was partially characterized and was found to have an edge component mainly parallel to {100} and {110}, close to normal to the macroscopic grain boundary plane. The step component of the disconnections was found to be aligned mainly parallel to the same crystallographic planes ({100} and {110}).
关键词： scanning transmission electron microscopy,grain boundaries,transmission electron microscopy,SrTiO3,disconnections
更新于2025-09-09 09:28:46
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Theoretical Analysis of Moving Reference Planes Associated with Unit Cells of Nonreciprocal Lossy Periodic Transmission-Line Structures
摘要： This paper presents a theoretical analysis of moving reference planes associated with unit cells of non-reciprocal lossy periodic transmission-line structures (NRLSPTLSs) by the equivalent bi-characteristic-impedance transmission line (BCITL) model. Applying the BCITL theory, only the equivalent BCITL parameters (characteristic impedances for waves propagating in forward and reverse directions and associated complex propagation constants) are of interest. An infinite NRLSPTLS is considered first by shifting a reference position of unit cells along TLs of interest. Then, a semi-infinite terminated NRLSPTLS is investigated in terms of associated load reflection coefficients. It is found that the equivalent BCITL characteristic impedances of the original and shifted unit cells are mathematically related by the bilinear transformation. In addition, the associated load reflection coefficients of both unit cells are mathematically related by the bilinear transformation. However, the equivalent BCITL complex propagation constants remain unchanged. Numerical results are provided to show the validity of the proposed theoretical analysis.
关键词： bilinear transformation,Unit cell,periodic transmission-line structure,bi-characteristic-impedance transmission line (BCITL)
更新于2025-09-09 09:28:46
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Impact of Selected Input Features for Lightpath Feasibility Validation Using Artificial Neural Networks
摘要： The new advents of 5G and Internet of Things (IoT) will impact the traf?c, both in volume and dynamicity, at unprecedented rates. As a result, optical transport networks should become more responsive to the traf?c changes as well as to operate more closely to optimality. Therefore, the implementation of a self-driving network is being proposed as a way to achieve these targets. One of the key challenges in this environment is the automatic provisioning of lightpaths. In order to provision a lightpath, Quality of Transmission (QoT) needs to be estimated, which involves complex and time consuming computations. This work proposes the use of arti?cial neural networks (ANN) to speed up lightpath feasibility validation without performing full validation per request (slow) nor keeping a full database of feasible lightpaths (memory consuming). Moreover, we evaluate the impact of input features selection and number of neurons in the obtained accuracy.
关键词： transport networks,arti?cial neural networks,machine learning,Quality of Transmission
更新于2025-09-09 09:28:46
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Complexities of atomic structure at CdO/MgO and CdO/Al 2O 3 interfaces
摘要： We report the interface structures of CdO thin films on (001)-MgO and (0001)-Al2O3 substrates. Using aberration corrected scanning transmission electron microscopy, we show that epitaxial growth of (001)-CdO||(001)-MgO occurs with a lattice misfit greater than 10%. A high density of interface misfit dislocations is found to form. In combination with molecular dynamics simulations, we show that dislocation strain fields form and overlap in very thin heterostructures of CdO and MgO (< 3 nm). On the c-Al2O3 substrate, we find that CdO grows with a surface normal of [025]. We show that three rotation variants form due to the symmetry of the sapphire surface. These results contribute insights into the epitaxial growth of these rock-salt oxides.
关键词： CdO,epitaxial growth,Al2O3,scanning transmission electron microscopy,molecular dynamics simulations,MgO,interface structures
更新于2025-09-09 09:28:46
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Height Estimation of Electric Power Transmission Tower Based on Tomography SAR Imaing Method using Staring Spotlight Mode Terrasar-X Data
摘要： Tomography SAR (TomoSAR) imaging can distinguish different scatterers in the same pixel using their spatial frequency spectrum difference. Sparse scatterers case located in one pixel can be imaged using high resolution spectral estimation algorithm or compressed sensing (CS) algorithm. For the pixel where the top position of the electric power transmission tower is located, it can be seen this sparse scatterers case. In this paper, TomoSAR imaging methods based on MUSIC algorithm, ESPRIT algorithm and CS algorithm are used to calculate the height of the electric power transmission tower, respectively. TerraSAR-X data is used for experiment. The experimental results demonstrate the ESPRIT algorithm has better accuracy than the other two algorithms for the height estimation of the study electric power transmission tower. Basically, this accuracy can meet the requirement in practical applications.
关键词： electric power transmission tower,Tomography SAR
更新于2025-09-09 09:28:46
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Terahertz Gyrotrons with Unique Parameters
摘要： Development of high power THz sources play important role for development advance technologies in physics, chemistry, biology, medicine. The main goal of this report is present together data about gyrotron development and the most striking examples of modern applications. The paper describes some features of THz tubes. The key information about pulsed and CW tubes is given. The described gyrotrons demonstrate (in some specific combinations) extremely low voltage and beam current, narrow frequency spectrum, wide range frequency tuning. Novel schemes of high frequency gyrotrons are analyzed. Examples of gyrotron based experiments for spectroscopy, data transmission and localized gas discharge are presented.
关键词： spectroscopy,data transmission,THz sources,gyrotrons,gas discharge
更新于2025-09-09 09:28:46
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Dynamics of gold nanoparticle clusters observed with liquid-phase electron microscopy
摘要： The dynamics of processes of nanoparticles such as diffusion, attraction and repulsion, and self-assembly of structures of nanoparticles at the solid-liquid interfaces differ significantly from those occurring for bulk conditions and their fundamental physical rules are still unknown. Here, we used liquid phase scanning transmission electron microscopy (LP-STEM) to study several aspects of nanoparticle dynamics of colloidal chitosan coated gold nanoparticle (TCHIT-AuNP) clusters in a liquid layer enclosed between two SiN membranes. We found that upon beam irradiation using an electron flux of 0.9 e?/s?2, the AuNPs assembled in clusters that shifted and rotated with time. The newly formed clusters could join and form larger clusters via a mechanism of oriented attachment. By increasing the electron flux to 6.2 e?/s?2, we observed the fragmentation of some of the clusters and TCHIT-AuNPs were exchanged between clusters. At the highest electron flux studied 25 e?/s?2, we observed AuNPs moving at a very slow speed compared to Brownian motion in liquid even though they were not permanently attached or pinned to the liquid-enclosing membrane. Experiments using branched polyethylenimine (BPEI) coated AuNPs were carried out for comparison.
关键词： nanoparticle clustering,nanoparticle dynamics,solid-liquid interface,gold nanoparticles,scanning transmission electron microscopy,liquid-phase electron microscopy
更新于2025-09-09 09:28:46
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Effect of conduction band non-parabolicity on the intersubband transitions in ZnO/Mg <sub/>x</sub> Zn <sub/>1-x</sub> O quantum well heterostructures
摘要： In this paper, we have calculated the electronic states and the coefficient of transmission in ZnO/MgxZn1-xO quantum well structures (QW), with 20% of Magnesium in both the parabolic and the non-parabolic cases. Our calculations are performed in the context of the approximation of the envelope function formalism, and using the finite difference method. The results show that the intersubband transition energy increases rapidly with well width until Lw=5nm and becomes almost constant (specially transitions E13 et E23). Wavelength λ23 decreases with well width until Lw=5nm and becomes constant. The non-parabolicity effect is more pronounced for small QW (Lw ≤ 5nm) and less marked in narrow and large QW. Also, we are studied the coefficient of transmission. We notice that when the height of barrier increases the coefficient of transmission decreases. It will be necessary to provide more energy to the electron so that it can cross the barrier. We also notice the variations related to a phenomenon of reflection quantum.
关键词： transmission coefficient,intersubband transitions,quantum well,ZnO/MgxZn1-xO,non-parabolicity
更新于2025-09-09 09:28:46