- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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MICRO WAVE PATTERNS BY VIBRATING-LENS ASSISTED LASER MACHINING
摘要： Surfaces with superimposed patterns offer, in many applications, numerous advantages over traditional smooth surfaces since they profoundly affect functional behavior, e.g., friction, wettability, etc. Different shapes and sizes of surface patterns were fabricated by traditional laser machining, however, micro wave patterns are difficult to generate by this process. In this paper, vibrating-lens assisted laser machining is proposed to generate such patterns and to extend its capabilities. A model, based on the traditional heat-flow principle, was built to ascertain the energy distribution in the process and predict the shape of the wavy patterns generated. A specially developed experimental setup was used for model validation. Sinusoidal wave patterns were analyzed as an example to demonstrate geometrical feature under different parameters and the feasibility of the process. The feasibility of the proposed theoretical and experimental methodologies was illustrated through a comparative analysis of experimental and simulation scenarios.
关键词： Pattern simulation,Surface topography,Vibrating-lens,Laser machining,Traditional heat-flow principle
更新于2025-09-11 14:15:04
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Simulation and analysis of the time evolution of laser power and temperature in static pulsed XPALs
摘要： A theoretical model is established to describe the thermal dynamics and laser kinetics in a static pulsed exciplex pumped Cs–Ar laser (XPAL). The temporal behaviors of both the laser output power and temperature rise in XPALs with a long-time pulse and multi-pulse operation modes are calculated and analyzed. In the case of long-time pulse pumping, the results show that the initial laser power increases with a rise in the initial operating temperature, but the laser power decreases quickly due to heat accumulation. In the case of multi-pulse operation, simulation results show that the optimal laser output power can be obtained by appropriately increasing the initial temperature and reducing the thermal relaxation time.
关键词： theoretical model,simulation,exciplex lasers
更新于2025-09-11 14:15:04
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Nitrogen-Doped Graphene Quantum Dots as Metal-Free Photocatalysts for Near-Infrared Enhanced Reduction of 4-Nitrophenol
摘要： Our paper mainly introduces a novel path planning method for non-ideal sphere-pipe intersecting curve robot welding based on laser scanning. This method integrates the generation of laser scanning trajectory, the processing of scanning data, and the path planning of non-ideal sphere-pipe joint welding. First, the paper perfects the ideal sphere-pipe intersection model and represents the parametric equation of ideal intersecting curve, which can cover all the intersection ways for sphere-pipe joints. Since the spheres and pipes applied in actual production are not standard, this paper adopts the scheme of scanning and identifying weld seam using the laser displacement sensor and gives the laser sensor scanning trajectory by analyzing the direction and attitude of space welds. In this paper, by sampling and filtering the distance data obtained from laser sensor, a novel weld point identification algorithm suitable for the above scanning trajectory is proposed. In response to the constantly changing of sphere-pipe joints’ weld inclination and attitude, this paper adopts the robot-positioner welding scheme and introduces a novel algorithm for solving the position of two external axes. The ADAMS simulation experiments prove that this scheme can effectively avoid the adverse effects of the uphill and downhill welding on the welding quality.
关键词： Non-ideal sphere-pipe intersecting curve,Weld seam identification,ADAMS simulation,Robot welding
更新于2025-09-11 14:15:04
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Species discrimination and individual tree detection for predicting main dendrometric characteristics in mixed temperate forests by use of airborne laser scanning and ultra-high-resolution imagery
摘要： This study aims to investigate the combined use of two types of remote sensing data — ALS derived and digital aerial photogrammetry data (based on imagery collected by airborne UAV sensors) — along with intensive field measurements for extracting and predicting tree and stand parameters in even-aged mixed forests. The study is located in South West Romania and analyzes data collected from mixed-species plots. The main tree species within each plot are Norway spruce (Picea abies L. Karst.) and Beech (Fagus sylvatica L.). The ALS data were used to extract the digital terrain model (DTM), digital surface model (DSM) and normalized canopy height model (CHM). Object-Based Image Analysis (OBIA) classification was performed to automatically detect and separate the main tree species. A local filtering algorithm with a canopy-height based variable window size was applied to identify the position, height and crown diameter of the main tree species within each plot. The filter was separately applied for each of the plots and for the areas covered with Norway spruce and beech trees, respectively (i.e. as resulted from OBIA classification). The dbh was predicted based on ALS data by statistical Monte Carlo simulations and a linear regression model that relates field dbh for each tree species with their corresponding ALS-derived tree height and crown diameter. The overall RMSE for each of the tree species within all the plots was 5.8 cm for the Norway spruce trees, respectively 5.9 cm for the beech trees. The results indicate a higher individual tree detection rate and subsequently a more precise estimation of dendrometric parameters for Norway spruce compared to beech trees located in spruce-beech even-aged mixed stands. Further investigations are required, particularly in the case of choosing the best method for individual tree detection of beech trees located in temperate even-aged mixed stands.
关键词： Monte Carlo simulation,ALS,Forest inventory,UAV,OBIA
更新于2025-09-11 14:15:04
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Generation of high-charge electron beam in a subcritical-density plasma through laser pulse self-trapping
摘要： To maximize the charge of a high-energy electron beam accelerated by an ultra-intense laser pulse propagating in a subcritical plasma, the pulse length should be longer than both the plasma wavelength and the laser pulse width, which is quite different from the standard bubble regime. In addition, the laser–plasma parameters should be chosen to produce the self-trapping regime of relativistic channeling, where the diffraction divergence is balanced by the relativistic nonlinearity such that the laser beam radius is unchanged during pulse propagation in a plasma over many Rayleigh lengths. The condition for such a self-trapping regime is the same as what was empirically found in several previous simulation studies in the form of the pulse width matching condition. Here, we prove these findings for a subcritical plasma, where the total charge of high-energy electrons reaches the multi-nC level, by optimization in a 3D PIC simulation study and compare the results with an analytic theory of relativistic self-focusing. A very efficient explicitly demonstrated generation of high-charge electron beams opens a way to a high-yield production of gammas, positrons, and photonuclear particles.
关键词： relativistic channeling,high-charge electron beam,subcritical-density plasma,laser pulse self-trapping,3D PIC simulation
更新于2025-09-11 14:15:04
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Accurate characterization of weld appearance induced by T-joint laser stake-welding by integration of ANFIS approach and numerical simulation
摘要： The geometrical appearance of weld bead is critically important in terms of directly determining the quality and reliability of T-joints laser stake-welding process. In this regard, this paper puts forward an innovative hybrid modeling scheme integrating the adaptive neural fuzzy interface system (ANFIS) with three-dimensional numerical simulation to accurately characterize the weld bead appearance. First, an ANFIS-based model is developed to identify the weld characteristics by experimental observation and provide the key parameters of hybrid heat source involved in the weld numerical simulation. Second, the weld bead geometry, i.e., weld penetration depth, surface weld width and interface weld width are all computed utilizing the numerical simulation method. The proposed numerical model exhibits good agreements with the experimental results in regard to forecasting the weld characteristics. In the end, the role of various welding conditions on the formation mechanism and T-joints bead profiles of the laser stake-welding are elucidated through the simulation model. The simulated results would help provide a much better understanding of the critical factors which does affect the weld appearance, and lay a solid foundation for optimizing of welding parameters and obtaining a high-quality weld.
关键词： T-joints,weld appearance,numerical simulation,ANFIS model,Laser stake-welding
更新于2025-09-11 14:15:04
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A Simulated Study of Building Integrated Photovoltaics (BIPV) as an Approach for Energy Retrofit in Buildings
摘要： Building envelopes can play a significant role in controlling energy consumption, especially in hot regions because of the wide variety of envelope materials and technologies that have been developed. Currently, because of the high rise in energy prices, especially with the high demand of fossil energy in the building sector worldwide, using curtain walls for maintaining adequate lighting in public buildings could lead to higher energy consumption because of the continuous exposure to the sun in hot regions. For this reason, studying the use of renewable or smart alternatives in the building sector to ensure a cleaner, greener environment by deploying sustainable technology in order to reduce energy demand and support economic long-term solutions would be important for solving such a problem. This paper aims at studying the use of renewable energy technologies and alternatives; represented in new building integrated photovoltaics (BIPVs) technology that could be integrated within building skin to reduce energy demand. The methodology follows a quantitative comparative approach, using an energy simulation software to study two different types of BIPV technology (BISOL Premium BXO 365 Wp monocrystalline and BXU 330 Wp, polycrystalline) on an existing building by retrofitting a part of its curtain wall. This is to conclude the energy saving percentage and feasibility of both alternatives.
关键词： building envelopes,energy efficiency,BIPVs technology,BIPVs feasibility,energy simulation
更新于2025-09-11 14:15:04
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Scale Accuracy Evaluation of Image-Based 3D Reconstruction Strategies Using Laser Photogrammetry
摘要： Rapid developments in the field of underwater photogrammetry have given scientists the ability to produce accurate 3-dimensional (3D) models which are now increasingly used in the representation and study of local areas of interest. This paper addresses the lack of systematic analysis of 3D reconstruction and navigation fusion strategies, as well as associated error evaluation of models produced at larger scales in GPS-denied environments using a monocular camera (often in deep sea scenarios). Based on our prior work on automatic scale estimation of Structure from Motion (SfM)-based 3D models using laser scalers, an automatic scale accuracy framework is presented. The confidence level for each of the scale error estimates is independently assessed through the propagation of the uncertainties associated with image features and laser spot detections using a Monte Carlo simulation. The number of iterations used in the simulation was validated through the analysis of the final estimate behavior. To facilitate the detection and uncertainty estimation of even greatly attenuated laser beams, an automatic laser spot detection method was developed, with the main novelty of estimating the uncertainties based on the recovered characteristic shapes of laser spots with radially decreasing intensities. The effects of four different reconstruction strategies resulting from the combinations of Incremental/Global SfM, and the a priori and a posteriori use of navigation data were analyzed using two distinct survey scenarios captured during the SUBSAINTES 2017 cruise (doi: 10.17600/17001000). The study demonstrates that surveys with multiple overlaps of nonsequential images result in a nearly identical solution regardless of the strategy (SfM or navigation fusion), while surveys with weakly connected sequentially acquired images are prone to produce broad-scale deformation (doming effect) when navigation is not included in the optimization. Thus the scenarios with complex survey patterns substantially benefit from using multiobjective BA navigation fusion. The errors in models, produced by the most appropriate strategy, were estimated at around 1% in the central parts and always inferior to 5% on the extremities. The effects of combining data from multiple surveys were also evaluated. The introduction of additional vectors in the optimization of multisurvey problems successfully accounted for offset changes present in the underwater USBL-based navigation data, and thus minimize the effect of contradicting navigation priors. Our results also illustrate the importance of collecting a multitude of evaluation data at different locations and moments during the survey.
关键词： navigation fusion,laser scalers,uncertainty estimation,structure-from-motion,Monte Carlo simulation,laser spot detection,metrology,underwater 3D reconstruction,multiobjective BA,scale drift evaluation,photogrammetry
更新于2025-09-11 14:15:04
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The Effect of Adsorbent Layer Thickness and Gallium Concentration on the Efficiency of a Dual-Junction Copper Indium Gallium Diselenide Solar Cell
摘要： The split of the sunlight spectrum by the bandgap energy of multi-junction solar cells is a highly effective way to increase solar cell ef?ciency. The reason is that the energy of photons is effectively absorbed, and there is a reduction in solar cell loss. In this contribution, we report on the performance of a double-junction copper gallium diselenide/copper indium gallium diselenide (CGS/CIGS) solar cell with a cadmium sul?de (CdS) buffer layer simulator. The J–V characteristics and the external quantum ef?ciency were simulated under AM1.5 illumination. Increased ef?ciency was seen as a result of the change in the thickness of layers and different molar ratio amounts of gallium, and the optimal amount of each factor was obtained. In this study, a single CGS solar cell was used as the top cell and a single CIGS solar cell as the bottom cell in the tandem con?guration, which showed conversion ef?ciencies of 16.175% and 15.696%, respectively. Finally, solar cell ef?ciency of 32.3% was obtained in the double-junction state, an increase of 6% compared with the reference cell.
关键词： CGS/CIGS double-junction solar cells,Numerical simulation,ef?ciency,four-terminal solar cell
更新于2025-09-11 14:15:04
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[IEEE 2018 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Hong Kong, China (2018.11.5-2018.11.9)] 2018 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Perovskite solar cell efficiency improvements: new device simulation
摘要： Trihalide perovskite photovoltaic (PV) solar cells have a promise to be connected into tandems with inorganic PV systems. In this paper we present p-i-n GaAs & PV cells in either in-series way or parallel connection. Comparisons made for two types of tandems by a non-monolithic connection of two experimental sub-cells and results are being discussed based on simulation analysis. It is shown that parallel connection is always more preferable when the subcells photocurrent is not balanced Total efficiency over 20 % is demonstrated for GaAs shadding effect of by MAPbI3 film, with achieved Jsc 41 mA/cm2 and high Voc, cell has better FF.
关键词： simulation,perovskite photovoltaic solar cell,tandem structure
更新于2025-09-11 14:15:04