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Magnetic-Field-Induced Partial-to-Full Penetration Evolution and Its Mechanism During Laser Welding
摘要： The geometry and tensile strength of magnetic-?eld-assisted laser-welded Ti-6Al-4V joints have been studied. Due to the effects of the magnetic ?eld on the melt ?ow behavior during welding, the weld penetration depth increased from 4.27 mm (partial penetration) to 5.00 mm (full penetration) and the curvature of the weld cross-section decreased, improving the weld tensile strength. The fusion zone was enlarged, showing a maximum increase of 53.4% in area when the magnetic ?eld intensity was 90 mT. The increased penetration depth and fusion zone area suggest that application of a magnetic ?eld can improve the energy utilization of the laser during laser butt welding. The mechanism of the magnetic-?eld-induced penetration depth evolution is discussed. This study provides a new energy-saving method to obtain a full-penetration weld using laser welding at lower power.
关键词： Magnetic-field-assisted laser welding,Tensile strength,Energy utilization,Ti-6Al-4V,Weld geometry
更新于2025-11-28 14:24:20
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Photothermal/day lighting performance analysis of a multifunctional solid compound parabolic concentrator for an active solar greenhouse roof
摘要： Currently, the excess light above a light saturation point cannot be harnessed for plant growth in conventional greenhouse covers. In this study, we developed a solid compound parabolic concentrator (CPC) cover for use in greenhouses to convert excess light into heat. Optical simulation software was used to track the sunlight at different incident angles over time. We also conducted experiments to determine the transmittance and heating power of the solid CPC coating under real weather conditions. The maximum instantaneous thermal efficiency and thermal energy of a single solid CPC cover plate were 32.2% and 353 W/m2, respectively. The simulation results were in good agreement with the experimental output power and the trend of the actual transmittance of the covering material. The transmittance of the covering material was low when the midday sun was intense, and the transmittance was relatively high in the morning and afternoon. The variation of red and blue light in the greenhouse with the spectrum was analyzed at the same time. Studies have shown that this new greenhouse covering material can better adjust the brightness, make the illumination in the greenhouse more uniform, and thus improve the thermal environment in the greenhouse. The heat pipes converted excess light into heat, thereby achieving comprehensive utilization of solar light and heat.
关键词： Heat energy utilization,Solid CPC,Solar greenhouse roof,Light transmittance,Solar PT/D system
更新于2025-09-23 15:22:29
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Strategic integration of vehicle-to-home system with home distributed photovoltaic power generation in Shanghai
摘要： The energy utilization optimization strategies in a smart house without and with vehicle to home (V2H) and/or home distributed photovoltaic (HDPV) in Shanghai are investigated in detail for the efficient household energy utilization and the reduction of net electricity expenditure. Such influences as EV travel distances, weather conditions and different PV subsidies are also taken into account. The results show that transferring valley electricity and PV by V2H can not only improve the utilization rate of valley electricity and PV, but also obtain considerable economic benefits. Transferring PV by V2H can get more revenues than transferring valley electricity by V2H. The energy arbitrage of V2H decreases with the increase of the EV travel distance. The HDPV-V2H mode in the case studied can completely cover the electricity demand of the household load in sunny and cloudy days without additional grid electricity while the combination of PV with transferred valley electricity by V2H is enough to support the household load demand in rainy days. The positive return of HDPV still can’t do without the support from government’s subsidy in Shanghai in the coming time. However, the HDPV-V2H mode can improve the benefit of HDPV. Meanwhile, there are a lot of EVs in Shanghai, charging with green power in priority. The HDPV-V2H mode can promote the synergetic development of HDPV and EVs in Shanghai.
关键词： Net electricity expenditure,Home distributed photovoltaic,Energy utilization optimization,Vehicle to home,Photovoltaic subsidy
更新于2025-09-23 15:19:57
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A novel carbon quantum dots (CQDs) modified Cs <sub/>4</sub> PW <sub/>11</sub> O <sub/>39</sub> Fe(III)(H <sub/>2</sub> O) material to achieve high photocatalytic property
摘要： Keggin-type polyoxometalates is a kind of promising photocatalyst with adjustable light absorption range. However, the high recombination rate of photogenerated charge carriers hampered its photocatalytic efficiency. To solve this weakness, novel carbon quantum dots (CQDs) modified Cs4PW11O39Fe(Ⅲ)(H2O) photocatalysts (CQDs/Cs4PW11Fe) have been synthesized via a hydrothermal process. Phase structure, morphology, optical and electronic properties of the as prepared photocatalysts were systematically characterized by XRD, SEM, TEM, DRS and surface photovoltage tests. It could be found that CQDs was well deposited on the surface of Cs4PW11Fe, which has broadened the light absorption of Cs4PW11Fe. The photodegradation efficiencies of the CQDs/Cs4PW11Fe composite photocatalysts for RhB under visible light irradiation were clearly enhanced. Trapping experiments were carried out to detect the photocatalytic mechanisms. The charge transfer and separation efficiencies of the samples were confirmed by electrochemical impedance spectroscopy tests.
关键词： Carbon quantum dots,Organic pollutants,Photocatalysis,Solar energy utilization,Cs4PW11O39Fe(Ⅲ)(H2O)
更新于2025-09-19 17:13:59
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A concentrating solar power system integrated photovoltaic and mid-temperature solar thermochemical processes
摘要： The approach of cascading solar energy utilization provides access to reliable and ample supplies of energy and has thus attracted widespread attention. Currently, the hybridization of a concentrating solar photovoltaic process and a solar thermochemical process is a promising approach. This paper describes and investigates a concentrating solar power system to harvest solar energy. Co-producing photovoltaic electricity and solar thermal fuel is its attractive distinction. The visible spectrum is cast onto concentrating photovoltaics to generate electricity, and the ultraviolet and infrared spectra are used to drive methanol decomposition at approximately 250 °C. A spectral splitting parabolic trough concentrator is developed in which incident solar radiation is first split and then concentrated. Based on the measured optical data of concentrators, photovoltaics and reactor, the solar-to-electricity performance is evaluated in the proposed system. The results show that a satisfied solar-to-electricity efficiency of approximately 31.8% would be realized if monocrystalline silicon photovoltaics is adopted. In comparison to individual systems, the efficiency enhancements of about 15.3% and 6.3% are obtained. The solar-to-electricity efficiency can reach approximately 35.1% by adopting gallium arsenide. Meanwhile, the improved optical performance proves that the approach of first splitting and then concentrating sunlight is feasible and promising. Finally, the results are anticipated to lead to a new approach for improving full-spectrum solar energy utilization and guiding the establishment of a prototype in the near future.
关键词： Full spectrum,Cascading solar energy utilization,Photovoltaic electricity,Concentrating solar power system,Solar thermal fuel
更新于2025-09-16 10:30:52
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Influences of synergy effect between laser and arc on laser-arc hybrid welding of aluminum alloys
摘要： Researchers generally believe that synergy effect between laser and arc enables laser-arc hybrid welding to acquire obvious advantages of efficiency and quality in welding aluminum alloys. However, influences of physical essence of the synergy effect on welding process were not clear. In this study, basic principle of the synergy effect and its influences on welding process were obtained by spectral analysis of hybrid plasma plume and high-speed photographic analysis of welding process. First, the principle of the synergy effect is that laser interacts with arc to render electron energy level to transition. This process emits more photons, which enhance the heat input to the weld materials. The synergy effect is quantified by spectral intensity. It increases with the laser power, and decreases with the arc current and laser-arc distance. It is proportional to the cross section of weld, especially the upper, and beneficial to improve the welding energy utilization. Secondly, the amount of spatter in laser-arc hybrid welding is significantly less than that of arc welding. The bigger weld pool, the downward melt flow, and the reduced droplet transfer force generated by the synergy effect make the transferring droplets more easily absorbed by the weld pool, which stabilizes the transfer process and reduces the generation of spatter. The research results are beneficial for understanding hybrid welding mechanism and optimizing the welding process.
关键词： Synergy effect,Laser-arc hybrid welding,Welding penetration,Welding energy utilization,Spatter
更新于2025-09-12 10:27:22
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Inactivation of airborne bacteria using different UV sources: Performance modeling, energy utilization, and endotoxin degradation
摘要： Airborne bacteria-containing bioaerosols have attracted increased research attention on account of their adverse effects on human health. Ultraviolet germicidal irradiation (UVGI) is an effective method to inactivate airborne microorganisms. The present study models and compares the inactivation performance of three UV sources in the UVGI for aerosolized Escherichia coli. Inactivation efficiency of 0.5, 2.2 and 3.1 logarithmic order was obtained at an exposure UV dose of 370 J/m3 under UVA (365 nm), UVC (254 nm) and UVD (185 nm) sources, respectively. A Beer–Lambert law-based model was developed and validated to compare the inactivation performances of the UV sources, and modeling enabled prediction of inactivation efficiency and analysis of the sensitivity of several parameters. Low influent E. coli concentrations and high UV doses resulted in high energy consumption (EC). The change in airborne endotoxin concentration during UV inactivation was analyzed, and UVC and UVA irradiation showed no marked effect on endotoxin degradation. By contrast, both free and bound endotoxins could be removed by UVD treatment, which is attributed to the ozone generated by the UVD source. The results of this study can provide a better understanding of the air disinfection and airborne endotoxin removal processes.
关键词： Energy utilization,Bioaerosol,Airborne endotoxin,UV germicidal irradiation (UVGI),Model
更新于2025-09-10 09:29:36