- 标题
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- 实验方案
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Electrochemical Coupled Analysis of a Micro Piezo-Driven Focusing Mechanism
摘要： In order to improve the response speed and output force of the camera focusing mechanism, the authors proposed a novelty micro focusing mechanism based on piezoelectric driving, which has the characteristics of rapid response, high precision positioning and large displacement focusing. In this paper, the operating principle of the proposed focusing mechanism is presented. Using the piezoelectric output characteristic, the movable tooth drive theory and the screw drive theory, the electromechanical coupling mechanical model and equations of the piezoelectric focusing mechanism are established. Through MATLAB simulation, the output characteristics of the piezoelectric focusing mechanism are calculated. The results indicate that the maximum thrust force of the lens and the maximum output torque of the movable tooth drive for the piezoelectric focusing mechanism are 562.5 N and 1.16 Nm, respectively. Furthermore, the driving voltage directly affects the output performance of the piezoelectric focusing mechanism. These results can be utilized both to optimize the dimensions and improve the overall performance of the piezo‐driven focusing mechanism.
关键词： focusing mechanism,piezo‐driven,numerical analysis,electrochemical coupled
更新于2025-09-23 15:19:57
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Thermal Poling of Optical Fibers: A Numerical History
摘要： This review gives a perspective of the thermal poling technique throughout its chronological evolution, starting in the early 1990s when the first observation of the permanent creation of a second order non-linearity inside a bulk piece of glass was reported. We then discuss a number of significant developments in this field, focusing particular attention on working principles, numerical analysis and theoretical advances in thermal poling of optical fibers, and conclude with the most recent studies and publications by the authors. Our latest works show how in principle, optical fibers of any geometry (conventional step-index, solid core microstructured, etc) and of any length can be poled, thus creating an advanced technological platform for the realization of all-fiber quadratic non-linear photonics.
关键词： thermal poling,numerical analysis,non-linear photonics,optical fibers
更新于2025-09-19 17:13:59
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Modeling of Keyhole-Induced Pore Formation in Laser-Arc Hybrid Welding of Aluminum Alloy with a Horizontal Fillet Joint
摘要： A three-dimensional transient model is proposed to investigate the weld pool dynamic behavior in laser + metal inert gas (MIG) hybrid fillet welding of aluminum alloy in the horizontal position, which allows for the joint configuration and coupling of the keyhole, droplet and weld pool as well as the heat and mass exchange between gas and liquid phases and is able to simulate the temperature distribution, fluid flow and formation process of a keyhole-induced pore in hybrid welding with a horizontal fillet joint. The weld porosity is also measured using x-ray nondestructive testing technology. Keyhole behavior and the formation mechanism of keyhole-induced porosity were analyzed. The calculated results are in generally good agreement with the experimental ones. A clockwise vortex always exists at the middle part of the weld pool. The formation and growth of the molten metal bulge on the keyhole wall are responsible for the occurrence of a gas bubble, which has a variation in size and shape and can be split during welding. The keyhole collapses easily at its middle or upper part in horizontal fillet welding, and the capture of the bubble by the upper molten pool boundary enhances the possibility of porosity formation to some degree. The keyhole-induced pore is mainly formed at the regions near the keyhole bottom and the upper fusion line of the weld pool.
关键词： horizontal fillet joint,numerical analysis,aluminum alloy,hybrid welding,pore formation
更新于2025-09-19 17:13:59
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Analysis of Elliptical Waveguides With Anisotropic Dielectric Layers
摘要： Our main objective is to extend the discrete mode matching (DMM) method to analyze multilayered elliptical fibers or transmission lines with elliptical dielectric layers. We generate the formulation for the full-wave equivalent circuit (FWEC) and derive the hybrid matrix elements for the dielectric layers in an elliptical coordinate system and then obtain the system equation of the structure. To demonstrate the technique, we analyze elliptical waveguides and compare the results with the data obtained by other authors and by commercial software.
关键词： numerical analysis,conformal,Multilayered microwave structures,anisotropic media
更新于2025-09-16 10:30:52
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Numerical Study on Windbreaks with Different Porosity in Photovoltaic Power Plants
摘要： In recent years, more and more attention has been paid to clean energy. Large-scale photovoltaic power plants are increasing. Photovoltaic power generation will be destroyed at a high wind speed, affecting the efficiency of power generation. Based on the computational fluid dynamics technology and the use of porous media model, this paper uses Fluent to numerically analyze the windbreaks of photovoltaic power generation. The influence of the inlet wind speed and the porosity of the windbreaks on the differential pressure across the photovoltaic panels was studied. The results show that with the increase of wind speed, the differential pressure of the photovoltaic panel is also increasing; installing the windbreaks with a porosity of 0, the differential pressure of the PV panel decreases. In addition, the pressure drop of the photovoltaic panel can be reduced by 50%-68% due to the effect of the windbreaks at different wind speeds; the porosity of the windbreaks panel is the better at 0.25-0.5, compared with the windbreaks without installation, the differential pressure of the photovoltaic support bracket decreased by 18.75%-35.84%.
关键词： Porosity,Photovoltaic power plants,Windbreaks,Numerical analysis
更新于2025-09-12 10:27:22
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Numerical and experimental investigation of thermo-fluid flow and element transport in electromagnetic stirring enhanced wire feed laser beam welding
摘要： The introduction of electromagnetic stirring to laser beam welding can bring several beneficial effects e.g. element homogenization and grain refinement. However, the underlying physics has not been fully explored due to the absence of quantitative data of heat and mass transfer in the molten pool. In this paper, the influence of electromagnetic stirring on the thermo-fluid flow and element transport in the wire feed laser beam welding is studied numerically and experimentally. A three-dimensional transient heat transfer and fluid flow model coupled with dynamic keyhole, magnetic induction and element transport is developed for the first time. The results suggest that the Lorentz force produced by an oscillating magnetic field and its induced eddy current shows an important influence on the thermo-fluid flow and the keyhole stability. The melt flow velocity is increased by the electromagnetic stirring at the rear and lower regions of molten pool. The keyhole collapses more frequently at the upper part. The additional elements from the filler wire are significantly homogenized because of the enhanced forward and downward flow. The model is well verified by fusion line shape, high-speed images of molten pool and measured element distribution. This work provides a deeper understanding of the transport phenomena in the laser beam welding with magnetic field.
关键词： Laser beam welding,Element transport,Thermo-fluid flow,Numerical analysis,Magnetohydrodynamics
更新于2025-09-12 10:27:22
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Analysis and optimization of passive cooling approach for free-standing photovoltaic panel: Introduction of slits
摘要： One of the major issues related to market available silicon based photovoltaic (PV) technologies is the performance drop caused by relatively high PV panel operating temperatures. The proper cooling of PV panels can reduce performance degradation and increase the lifetime of convectional PV panels. This paper investigates architecture modifications to market available silicon PV panels with the introduction of slits on the PV panel surface, which enables the passive cooling of PV panels. Two different arrangements of slits were numerically investigated and followed with the optimization approach. A developed numerical model was derived from the referent numerical model that was experimentally validated. For each considered scenario, a detailed flow and thermal analysis was performed which included optimization regarding minimum average PV cell temperatures. The considered slit types differ with slit orientation, i.e. parallel to PV panel tilt-axis (type-A) and perpendicular to PV panel tilt-axis (type-B). In both cases, a detailed analysis and optimization required ~100 CFD simulations to investigate the effects of different slit sizes and all wind directions. Overall, using the considered slit modifications, the average PV cell temperature could be decreased up to 3 °C, where effective cooling with the proposed modification is only reasonable for wind speeds up to 5 m/s.
关键词： Energy conversion efficiency,Renewable energy,Photovoltaics,Numerical analysis,Passive cooling
更新于2025-09-11 14:15:04
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A Novel Dispersive Time-Domain Interaction Code for Helix TWT by Collocated Space and Staggered Time Scheme Pseudospectral Analytical Time-Domain Method
摘要： Remarkable advantages are achieved by techniques such as pseudospectral analytical time-domain (PSATD) method in numerical simulations. Examples are, but not limited to discretization effects reduction (e.g., numerical dispersion error) and geometrical dispersion consideration. In this paper, a novel well-organized version [a newly presented particle-wave interaction code (PaWaIC)], employing collocated space and staggered time scheme PSATD method is introduced: PaWaIC-PSATD-CSST. Validity of the new code is investigated. It is shown that a more accurate phase velocity is realized by PaWaIC-PSATD-CSST in comparison with PaWaIC-pseudospectral arbitrary order finite-difference time-domain (PaWaIC-PSAOFDTD) code for an identical time step and grid size. The fast single-run capability of this novel code for simulating pulse response of wideband tubes is also presented.
关键词： traveling-wave tube (TWT),Numerical analysis,pseudospectral,pulse amplification,time-domain analysis
更新于2025-09-10 09:29:36
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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018 –ECCE Asia) - Niigata, Japan (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - Enhancement of Driving Capability of Gate Driver Using GaN HEMTs for High-Speed Hard Switching of SiC Power MOSFETs
摘要： A high-speed gate driver based on GaN-HEMTs push-pull configuration has been proposed to drive a SiC power MOSFET at high switching frequency. In this study, we investigate the influences of parasitic inductances of the GaN HEMTs on the output voltage of the GaN-based gate driver. The parasitic inductances at the gate, source, and drain terminals of the GaN HEMTs are analyzed with SPICE simulation. It is found that the parasitic inductances at the gate and source terminals of the GaN HEMT have almost no influences on the output waveform of the gate driver, while the parasitic inductances at the drain terminal of the GaN HEMT produce large voltage oscillations of the output voltage.
关键词： numerical analysis,GaN-based gate driver,high-frequency switching,parasitic inductance
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Improved Power Coefficient of Sensitivity in a Series-Parallel Circuit of Thermal Converters
摘要： The power coefficient of sensitivity is a useful measure that can provide a deep insight into the improvement of the low-frequency ac–dc transfer difference. We have, therefore, derived the power coefficient of series–parallel connected thermal converters (TC) arranged in an m × m matrix, as a low-frequency ac-dc transfer standard. The obtained power coefficient of the m × m series–parallel connected TCs is found to decrease proportional to 1/m2, without any decrease in the sensitivity. The experimental results are in close agreement with the results of the analysis.
关键词： electrical variable measurement,numerical analysis,thermal converter,thermal voltage converter,AC–DC difference
更新于2025-09-10 09:29:36