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Effect of laser beam incidence angle on cladding morphology in laser cladding process
摘要： The change of angle θ between laser cladding powder plane and substrate plane will lead to changes in cladding layer's geometric morphology. Therefore, we established a quantitative numerical prediction model for cladding layer geometry. In this model, we consider the variation of θ, the laser energy attenuation rate and the temperature rise of the powder particles. At the same time, the simulation results were verified by experiments. The results show that when θ is in the range of 50°~90°, the initial temperature is 298 K, the scanning speed is 3.75 mm/s, and the laser spot diameter is 4.5 mm, the Fe#1 powder cladding can achieve better forming effect on Q235. In general, with the decrease of θ, the height of the cladding layer decreases and the width of the layer increases. However, when θ is less than 50°, the quality of the formed morphology significantly deteriorated. The experimental results are in good agreement with the simulation results, which verifies the validity and reliability of the model. This work provides a theoretical reference for further understanding the relationship between the laser cladding morphology and the incident angle.
关键词： Numerical simulation,Laser cladding,Geometric morphology,Laser incident angle
更新于2025-09-23 15:19:57
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[IEEE 2018 28th International Telecommunication Networks and Applications Conference (ITNAC) - Sydney, Australia (2018.11.21-2018.11.23)] 2018 28th International Telecommunication Networks and Applications Conference (ITNAC) - Analysis of the effects of multiple reflection paths on high speed VLC system performance
摘要： In the recent past, research in visible light communication (VLC) has gained a lot interest due to its distinct characteristics in supporting high-speed data transmission and illumination simultaneously. To implement a reliable VLC system, few parameters have to be considered for communication channels such as distance between transmitter and receiver, data rate, line of sight (LOS) and non-line of sight (NLOS) communication paths, signal power and delay of the channel. In this paper, we designed and simulated a LOS and NLOS multipath VLC model using single and multiple LEDs. Basic on-off keying (OOK) modulation scheme and available conventional LED configuration have been considered to analyze the effects of field of view (FOV) and the reflection of the light signal on received power level. Moreover, BER and quality of transmission were measured for single and multipath transmissions considering distance, incident and irradiance angles.
关键词： BER,LED refraction,Visible Light Communication,multi-channel,FOV,irradiance and incident angle
更新于2025-09-19 17:15:36
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Ultraviolet to near infrared titanium nitride broadband plasmonic absorber
摘要： In this paper, we theoretically design and numerically verify a broadband plasmonic absorber that works continuously in ultraviolet to near-infrared region. Different from the traditional metal-insulator-metal (MIM) three-layer structure, our perfect absorber is based on insulator-metal-insulator-metal (IMIM) four-layer structure. This perfect absorber owns a 280 nm ultra-thin thickness, a configuration of refractory metal titanium nitride and high-melting-point insulator silica equips it with strong thermal stability. The novel titanium nitride ring-square array layer combines the absorption of different wavelength bands so that the absorber can achieves a continuous absorption of more than 90% from wavelength 200–1200 nm. Using Finite-difference time-domain (FDTD) method, we get a calculated average absorption rate as 94.85%, which includes a 99.40% maximum absorption at wavelength 270 nm and a 90.30% minimum absorption at 390 nm. In addition, this perfect absorber demonstrates polarization independence under normal incidence and large incident angle insensitivity under oblique incidence, which has significant application potentials in many areas such as solar energy collection, photothermal conversion, and invisibility cloak.
关键词： Broadband absorber,Ultraviolet to near infrared,Polarization independence,Plasmonic,Large incident angle insensitivity
更新于2025-09-19 17:13:59
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Accurate Output Forecasting Method for Various Photovoltaic Modules Considering Incident Angle and Spectral Change Owing to Atmospheric Parameters and Cloud Conditions
摘要： Because semiconductors absorb wavelengths dependent on the light absorption coefficient, photovoltaic (PV) energy output is affected by the solar spectrum. Therefore, it is necessary to consider the solar spectrum for highly accurate PV output estimation. Bird’s model has been used as a general spectral model. However, atmospheric parameters such as aerosol optical depth and precipitable water have a constant value in the model that only applies to clear days. In this study, atmospheric parameters were extracted using the Bird’s spectrum model from the measured global spectrum and the seasonal fluctuation of atmospheric parameters was examined. We propose an overcast spectrum model and calculate the all-weather solar spectrum from clear to overcast sky through linear combination. Three types of PV modules (fixed Si, two-axis tracking Si, and fixed InGaP/GaAs/InGaAs triple-junction solar cells) were installed at the University of Miyazaki. The estimated performance ratio (PR), which takes into account incident angle and spectral variations, was consistent with the measured PR. Finally, the energy yield of various PVs installed across Japan was successfully estimated.
关键词： output forecasting,incident angle,energy yield,photovoltaic,precipitable water,aerosol optical depth
更新于2025-09-19 17:13:59
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Photovoltaic performance of one axis multiple-position sun-tracked PV panels
摘要： In this article, the photovoltaic performance of one-axis multiple-positions sun-tracked photovoltaic panels (MP-PV) is investigated based on solar geometry and dependence of photovoltaic conversion efficiency on the incident angle (IA) of solar rays on PV panels. For such PV system, the azimuth angle (AZA) of PV panels is daily adjusted several times (M) from eastward in the morning to westward in the afternoon by rotating PV panels about inclined north-south axis (INSA) to ensure the projected incident angle (PIA) of solar rays on the plane perpendicular to INSA is always less than the specified angle θa. Results show that, the annual electricity generation (AEG) of MP-PV increases with the increase of M, but such increase is not noticeable when M>5. For MP-PV with the tilt-angle (β) of INSA being yearly fixed (1T-MP-PV), the optimal θa of 3P-,5P- and 7P-PV for maximizing AEG are respectively 24o, 15o and 11.5o, and their AEGs are respectively about 92%, 94% and 95% of that from similar 2-axis tracked PV panels (2A-PV). Whereas for MP-PV with the β being yearly adjusted four times at three tilts (3T-MP-PV), the optimal θa of 3P-, 5P- and 7P-PV are respectively about 22.5o, 14.5o and 11o, and the Pa are respectively about 96%, 98% and 99% of that of similar 2A-PV systems.
关键词： photovoltaic conversion efficiency,azimuth angle,annual electricity generation,solar geometry,sun-tracked PV panels,incident angle,photovoltaic performance
更新于2025-09-16 10:30:52
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Photovoltaic Effect Related to Methylammonium Cation Orientation and Carrier Transport Properties in High-Performance Perovskite Solar Cells
摘要： Solar cells based on organic-inorganic hybrid halide perovskites (OIHHP) have been widely studied due to their increasing power conversion efficiency (PCE). Extensive research has been conducted in electrical, optical properties and device fabrication. However, in terms of material science, the photovoltaic effects of OIHHP are still not well understood. Here, we theoretically investigate the photovoltaic phenomena of MAPbI3 (MA=CH3NH3+) under standard AM 1.5G sunlight illumination, considering the MA cation orientation, light incident angle, polarization and photon energy, using Keldysh non-equilibrium Green’s function formalism combined with density functional theory calculations. It is found that the short-circuit current density Jsc has a maximum value of 383.149 A/m2 when the MA orientation is parallel to the transport direction, whereas it is negligible when the MA orientation is orthogonal to the transport direction. In addition, full consideration is also given to the direction of incidence of sunlight and its polarization state. Nevertheless, of all factors considered, MA orientation plays the decisive role, for Jsc still has a respectable value of 364.112 A/m2 even for a 90-degree sunlight incident angle relative to the transport direction, so long as the MAs are aligned in the transport direction. The increase in the photocurrent is attributed to an increase in the transmission coefficient of low-energy holes, as well as improvement of the velocities and mobilities of electrons and holes in MAPbI3-based device with [001] MA orientation. The results suggest that the design of high-performance OIHHP-based solar cells and photoelectronic devices should carefully consider the crystal orientation and MA cation orientation relative to the transport direction as they directly affect carriers transport properties.
关键词： photon energy,polarization angle,cation orientation,transport properties,photocurrent,incident angle
更新于2025-09-12 10:27:22
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Refractory Ultra-Broadband Perfect Absorber from Visible to Near-Infrared
摘要： The spectral range of solar radiation observed on the earth is approximately 295 to 2500 nm. How to widen the absorption band of the plasmonic absorber in this range has become a hot issue in recent years. In this paper, we propose a highly applicable refractory perfect absorber with an elliptical titanium nanodisk array based on a silica–titanium–silica–titanium four-layer structure. Through theoretical design and numerical demonstration, the interaction of surface plasmon resonance with the Fabry–Perot cavity resonance results in high absorption characteristics. Our investigations illustrate that it can achieve ultra-broadband absorption above 90% from a visible 550-nm wavelength to a near-infrared 2200-nm wavelength continuously. In particular, a continuous 712-nm broadband perfect absorption of up to 99% is achieved from wavelengths from 1013 to 1725 nm. The air mass 1.5 solar simulation from a ?nite-difference time domain demonstrates that this absorber can provide an average absorption rate of 93.26% from wavelengths of 295 to 2500 nm, which can absorb solar radiation ef?ciently on the earth. Because of the high melting point of Ti material and the symmetrical structure of this device, this perfect absorber has excellent thermal stability, polarization independence, and large incident-angle insensitivity. Hence, it can be used for solar cells, thermal emitters, and infrared detection with further investigation.
关键词： large incident-angle insensitivity,ultra-broadband,perfect absorber,refractory
更新于2025-09-04 15:30:14