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Effects of postmetallization annealing on interface properties of Al <sub/>2</sub> O <sub/>3</sub> /GaN structures
摘要： In this study, we investigated the e?ects of postmetallization annealing (PMA) on the interface properties of GaN metal–oxide–semiconductor (MOS) structures using Al2O3 prepared by atomic layer deposition. Excellent capacitance–voltage (C–V ) characteristics without frequency dispersion were observed in the MOS sample after PMA in N2 ambient at 300–400 °C. The PMA sample showed state densities of only at most 4 ' 1010 cm%1 eV%1. A geometric phase analysis of transmission electron microscopy images after PMA revealed a uniform distribution of the lattice constant near the Al2O3/GaN interface, leading to the improved bond termination and bonding order con?guration along the interface.
关键词： atomic layer deposition,capacitance–voltage characteristics,Al2O3/GaN structures,interface properties,postmetallization annealing
更新于2025-09-23 15:21:01
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Real-time emulation of photovoltaic energy using adaptive state feedback control
摘要： The current paper presents an experimental validation of photovoltaic (PV) source emulation using a real-time dSpace controller. The PV source emulator is a nonlinear power electronic device used to provide in real-time the electrical behavior of PV panels by tracking the PV current–voltage (I–V) characteristic. It aims to deliver nearly the same current and voltage as an actual PV module without depending on atmospheric conditions. This innovative tool is able to aid researchers in PV systems to perform their tests and measurements at the desired weather parameters without time, space and cost constraints. The proposed PV emulator is based on a simple and efficient adaptive state feedback control that ensures good accuracy and high dynamic response compared to the existing commercial PV emulators based on the programmable power supply, which improves significantly the static and dynamic performances of existing PV emulators.
关键词： PV characteristics,Real-time emulation,dSpace controller,PV emulator,Adaptive state feedback control
更新于2025-09-23 15:21:01
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Structure stability, bond characteristics and microwave dielectric properties of co-substituted NdNbO4 ceramics
摘要： Structure-property relationship of co-substituted (Mg2+1/4Mo6+3/4)5+, (Al3+1/3Mo6+2/3)5+, (Si4+1/2Mo6+1/2)5+, (Zr4+1/2Mo6+1/2)5+ for Nb5+ in NdNbO4 ceramics was investigated systematically. The remarkable differences in dielectric properties of each composition originated from their bond characteristics and structure stability. The elongated/compressed bonds have an effect on the cell volume and polarization. And the average bond covalency of Nb-O bond was responsible for the development of permittivity. Q×f values and the total lattice energy went up to maximum when (Si0.5Mo0.5) occupied Nb-site. Variations of lattice energy together with Nb-O bond energy suggest that a more stable structure was obtained through co-substitution. The optimal microwave dielectric properties is: εr=18.97, Q×f=49466GHz, τf=7.34 ppm/℃ for NdNb0.97(Si0.5Mo0.5)0.03O4, sintered at 1250℃.
关键词： bond characteristics,Rietveld refinement,NdNbO4,microwave dielectric properties
更新于2025-09-23 15:21:01
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A Photovoltaic Array Fault Diagnosis Method Considering the Photovoltaic Output Deviation Characteristics
摘要： There are a large number of photovoltaic (PV) arrays in large-scale PV power plants or regional distributed PV power plants, and the output of different arrays fluctuates with the external conditions. The deviation and evolution information of the array output are easily covered by the random fluctuations of the PV output, which makes the fault diagnosis of PV arrays difficult. In this paper, a fault diagnosis method based on the deviation characteristics of the PV array output is proposed. Based on the current of the PV array on the DC (direct current) side, the deviation characteristics of the PV array output under different arrays and time series are analyzed. Then, the deviation function is constructed to evaluate the output deviation of the PV array. Finally, the fault diagnosis of a PV array is realized by using the probabilistic neural network (PNN), and the effectiveness of the proposed method is verified. The main contributions of this paper are to propose the deviation function that can extract the fault characteristics of PV array and the fault diagnosis method just using the array current which can be easily applied in the PV plant.
关键词： photovoltaic array,deviation characteristics,fault diagnosis,probabilistic neural network
更新于2025-09-23 15:21:01
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Towards non-destructive individual cell I-V characteristic curve extraction from photovoltaic module measurements
摘要： In this work, a non-destructive, automated procedure to extract the I-V characteristics of individual cells of fully encapsulated photovoltaic (PV) modules is proposed. The approach is able to correctly identify and extract the electrical parameters of underperforming cells, due for example to defects or degradation. The approach uses multiple I-V measurements on the PV module assuming specific levels of shading on the individual cells. The single circuit models for the cells are obtained through the solution of an inverse fitting problem. The approach was validated in a simulated environment through statistical analysis, with the cell parameters based on real silicon PV devices. The computational complexity of the approach is also investigated and validation examples with different configurations of PV modules, including bypass diodes are presented. The approach was validated on several tests to assess noise robustness, flexibility in terms of cells non-uniformities and scalability towards larger systems, resulting in a lean and accurate procedure for I-V curves extraction. The proposed methodology can be potentially utilised for automated quality assurance and fault assessment of PV modules, investigation of degradation mechanisms of cells in PV modules, or quantitative validation of other optical imaging techniques such as luminescence imaging and infrared thermography.
关键词： Automated procedure,I-V characteristics,Bypass diodes,Non-destructive testing,Degradation,Photovoltaic modules
更新于2025-09-23 15:21:01
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Memory characteristics of microcavity dielectric barrier discharge
摘要： The nonlinear resistance characteristics of microcavity dielectric barrier discharge are mainly studied in the paper. A simulation model of microcavity dielectric barrier discharge is herein built to study the relationship between voltage and current in the process of discharge, and thus its I–V characteristic curve can be obtained. The I–V characteristics of the memristor are analyzed and compared with the I–V characteristics of the dielectric barrier discharge; it can be found that the I–V characteristics of the microcavity dielectric barrier discharge are similar to the characteristics of the memristor by analyzing them. The memory characteristics of microcavity dielectric barrier discharge are further analyzed.
关键词： memristor,memory characteristics,microcavity dielectric barrier discharge,I–V characteristic
更新于2025-09-23 15:21:01
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Effect on Local Structure and Phase Transition of Perovskite-Type [N(CH3)4]2Zn1-xCuxBr4 (x?=?0, 0.5, 0.7, and 1) Crystals with the Various Doping of Cu2+ Ions
摘要： This study focused on how the local structures in pure [N(CH3)4]2ZnBr4 crystal are affected by the partial replacement of Zn2+ ions with Cu2+ ions. The structures and phase transition temperatures TC of perovskite-type [N(CH3)4]2Zn1-xCuxBr4 (x = 0, 0.5, 0.7, and 1) mixed crystals were almost unchanged by the partial doping of Cu2+ ions. The environments for the local structures of [N(CH3)4]2Zn1-xCuxBr4 mixed systems were studied according to differences in the chemical shifts of the 1H magic angle spinning (MAS) NMR, 13C cross-polarization (CP)/MAS NMR, and 14N NMR spectra. The 1H and 13C NMR results showed that the local environments of 1H and 13C nuclei near TC are not affected by substituting Zn2+ ions with Cu2+ ions, whereas the 14N NMR results showed that the local environment is affected near TC. Consequently, the main indicators of the phase transition in [N(CH3)4]2Zn1-xCuxBr4 are related to the ferroelastic characteristics with different orientations.
关键词： phase transition,ferroelastic characteristics,NMR spectroscopy,perovskite structures,Metal-organic hybrids
更新于2025-09-23 15:21:01
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AIP Conference Proceedings [Author(s) 3RD INTERNATIONAL SCIENCES, TECHNOLOGY & ENGINEERING CONFERENCE (ISTEC) 2018 - MATERIAL CHEMISTRY - Penang, Malaysia (17–18 April 2018)] - Influence of calcination temperature on the characteristic and sonophotocatalytic activities of Fe-doped TiO2 particles
摘要： In this study, 3 wt% Fe-doped TiO2 particles were prepared by sol-gel method using tetrabutyl titanate and iron (III) nitrate nonahydrate as precursors. Calcination of the prepared samples was carried out at temperature of 200, 400, 600 and 800 °C for 2 h. The effect of calcination temperature on the composition, structure and morphology of Fe-doped TiO2 were characterized using Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Spectroscope (EDX) and X-ray Diffractometer (XRD). The FESEM images revealed changes in particle size from 34 to 148 nm for samples calcined at 200 to 800 °C, respectively. Meanwhile, XRD results demonstrated the presence of rutile phase in catalysts which were calcined above 600 °C. Sonophotocatalytic degradation of paracetamol using ultraviolet (UV) light and ultrasonic irradiation was performed to investigate the influence of calcination temperature on the catalytic activity of Fe-doped TiO2. Among all the calcined catalysts, the Fe-doped TiO2-600 achieved the highest degradation efficiency (74%) due to the presence of mixed anatase and rutile phases. This proved that calcination temperature is a critical parameter which affects the characteristics and catalytic activity of Fe-doped TiO2 catalyst in the sonophoto-degradation process.
关键词： Paracetamol,Sonophotocatalytic,Heat treatment,Fe-doped TiO2,Characteristics
更新于2025-09-23 15:21:01
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Optical characteristics of overstressed nanosecond discharge in atmospheric pressure air between chalcopyrite electrodes
摘要： The results of the investigation of the optical characteristics of a high-current nanosecond discharge in atmospheric pressure air between chalcopyrite electrodes (CuInSe2 and CuSbSe2 compounds) in conditions of overstressed discharge gap are presented. When using electrodes with a relatively large radius of curvature of the working part (3 mm) and a special system for isolating a part of the surface of the electrodes, a relatively uniform nanosecond discharge was obtained in millimeter intervals. Electrical and optical (spectral and temporal) discharge characteristics were investigated. Based on the solution of the Boltzmann equation for the electron energy distribution function, the parameters of the air plasma with small additions of the vapor of easily ionized impurity, in the form of copper vapor, were simulated.
关键词： optical characteristics,chalcopyrite electrodes,overstressed nanosecond discharge,air plasma
更新于2025-09-23 15:21:01
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Teleoperation system for a mobile robot arm with visual servomechanism based on turning radius determination using angle information of image
摘要： This paper considers the development of a teleoperation system for a mobile robot arm with visual servo mechanism. The robot to be operated mainly consists of a mobile robot and a robot arm with USB camera. The robot is teleoperated according to the control command which is generated by combining the manual operation with the autonomous control via the vision system based on the USB camera images. In this paper, a control method of determining the turning radius of the mobile robot is proposed based on the angle information of image corresponding to the error of a target position from the reference one. To evaluate the proposed teleoperation system, experiments of pressing a button were conducted by using an actual robot. It was verified from the experimental results that sufficiently high success rate of teleoperation could be obtained by the proposed method.
关键词： Angle-pixel characteristics,Turning radius,Teleoperation,Visual servo,Mobile robot
更新于2025-09-23 15:21:01