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oe1(光电查) - 科学论文

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出版时间
  • 2019
  • 2018
研究主题
  • Heat Trap
  • outgassing
  • lifetime
  • Carbon nanotubes
  • current stability
  • cathode
  • thermionic emission
  • photovoltaic
  • monocrystalline
  • Heat mapping
应用领域
  • Nanomaterials and Technology
  • Electrical Engineering and Automation
机构单位
  • University of British Columbia
  • Univesitas Budi Luhur
  • Institut Teknologi Sepuluh Nopember
386 条数据
?? 中文（中国） ▾

  • Optimization of process parameter of Laser beam machining of high strength steels: a review

    摘要： Metal cutting forms the basis of industry its relevance among products of everyday life due its high strength application in structural, aviation, aerospace, military, naval purpose etc. Based on recent study it is found that many high strength steel are cut using lasers and it has given exceptional result as compared to other Non conventional machining process it is important to know how the cutting is affecting the material properties and which parameters are responsible for such change. The various parameters and their effects are shown in the given study which is analyzed by different researchers along the course of time. The material and thickness and different optimization techniques by different researchers is also shown.

    关键词： Macro structural changes,CO2,Control parameters,laser beam cutting (LBC),Heat Affected Zone (HAZ),Micro

    更新于2025-09-12 10:27:22

  • Enhanced Physical and Thermal Performance of Expanded Graphite-Based Heat Sink for LED Radiator

    摘要： An experimental study was carried out to investigate the heat transfer characteristics of Cu and Al–modified expanded graphite heat sinks. In this study, the heat sinks were composed of expanded graphite as an active material, Cu and Al as heat transfer enhancement material and resin as a binder. Graphite with high purity was obtained via treated with different amount of Na2CO3. The as-prepared heat sinks were characterized by XRD, pH, SEM, electrical resistivity, bending strength and thermal analysis. The metal Al modified expanded graphite composite heat sink in our experiment exhibited a good rate of capability in physical and thermal performances. Sample GA5-300 showed highest thermal diffusivity and thermal conductivity.

    关键词： Expanded graphite,Heat transfer,Thermal diffusivity and conductivity

    更新于2025-09-12 10:27:22

  • Heat-Affected Zone Investigation During the Laser Beam Drilling of Hybrid Composite Using Statistical Approach

    摘要： In the present work, basalt–glass hybrid composite has been fabricated and machined using laser beam drilling, to predict a safe machining zone pertaining to high drill quality with minimum heat-affected zone and maximum hole circularity. The prediction of the zone has been done by mathematical modeling using response surface methodology. The obtained zone has also been validated by performing more experiments. Moreover, the dependency of hole circularity and heat-affected zone on input parameters has also been discussed. From the results, it is evident that the obtained zone is capable of minimizing the heat-affected zone with acceptable hole circularity. Moreover, the behavior of input parameters is non-monotonic in nature.

    关键词： Precise drilling,Heat-affected zone,Basalt–glass composite,Hybrid composite

    更新于2025-09-12 10:27:22

  • Effect of Welding Speed on the Prediction Accuracy of Residual Stress in Laser Welded 1.2?mm Thick Dual Phase Steel

    摘要： Post-weld residual stress and distortion are significant issues in laser welding as they reduce fatigue strength and toughness. In the present work, cold rolled dual phase steel sheets of 1.2 mm thickness were laser welded in both bead on plate and butt configurations. The optimum heat input was observed to be approximately 25 kJ/m for visually defect free weld with narrow weld bead and through-thickness penetration. A novel attempt was made to increase the welding speed whilst maintaining the optimum heat input. It was observed that, high welding speed led to high residual stress, resulting in longitudinal cracks, whereas the speed at a limiting value of 0.08 m/s was found to be beneficial longitudinal cracks. Literature suggests researchers have for welding without already proposed different mathematical models on keyhole mode laser welding that can predict the residual stress and deformation. However, most of them failed to predict it repetitively, especially for thin sheets. This work tried to find the range of the rationality of this argument. For low-speed condition, residual stress values was substantially wide, making it difficult to predict actual residual stress with the aid of mathematical models. The range of residual stress values was found to be much lower for the optimum heat input and high-speed condition, resulting into better prediction accuracy. Residual stress values were also validated using kernel average misorientation (KAM) study.

    关键词： Heat input,Dual phase steel,Kernel average misorientation,Residual stress,Laser welding,Key-hole mode,Welding speed,Weld longitudinal crack

    更新于2025-09-12 10:27:22

  • Advancing photovoltaics and thermophotovoltaics with supradegeneracy

    摘要： An ongoing challenge facing photovoltaics (PV) and thermophotovoltaics (TPV) is to improve the relatively poor efficiency with which they convert blackbody radiation into electricity. Analysis indicates that a recently proposed phenomenon from statistical mechanics – supradegeneracy – might boost this efficiency and increase system power densities. Supradegeneracy might also expand the palette of attractive PV/TPV materials, allow lower operating temperatures for TPVs, and thereby increase their robustness, reliability, and lifespan. Laboratory tests of the supradegeneracy concept have begun.

    关键词： Photovoltaics,Second law of thermodynamics,Thermophotovoltaics,Waste heat,Supradegeneracy

    更新于2025-09-12 10:27:22

  • Heat accumulation effects in laser processing of diamond-like nanocomposite films with bursts of femtosecond pulses

    摘要： In this paper, we have investigated the burst mode (BM) ablation and surface structuring of diamondlike nanocomposite (DLN) a-C:H:Si:O films with femtosecond laser pulses (wavelength λ = 515 nm, pulse duration τ = 320 fs, and pulse repetition rate f = 100 kHz) under different scanning conditions (single spots and linear structures). The pulse separation in the bursts is 25 ns (intraburst frequency f = 40 MHz), and the pulse number is varied from 1 to 8. The ablation depth and specific ablation rates (μm3/μJ) are found to be higher for the burst mode compared to single-pulse irradiation, increasing with the pulse number in the burst. The obtained experimental data of the higher ablation efficiency are shown to correlate with computer simulations of the BM ablation. In correlation with the ablation findings, Raman spectra of single spots and microgrooves have evidenced a growing graphitization of the amorphous film structure with the pulse number in the bursts (at an equal energy deposited into the films). Contact-mode atomic force microscopy (AFM) is applied to reveal an influence of the BM processing on the surface properties (nanoscale relief, friction) of laser-structured films. Based on the ablation and Raman data analysis, AFM examination of ablated/redeposited layers, and computer simulations of the burst mode ablation, the heat accumulation is identified as the main factor responsible for the enhanced ablation efficiency during the BM processing of DLN films. In addition, results of the high precision surface microstructuring of DLN films in the burst mode are presented.

    关键词： heat accumulation,diamondlike nanocomposite films,surface structuring,femtosecond laser pulses,burst mode ablation

    更新于2025-09-12 10:27:22

  • Quercetin encapsulated biodegradable plasmonic nanoparticles for photothermal therapy of hepatocellular carcinoma cells

    摘要： Photothermal therapy (PTT) is emerging as an effective treatment modality for cancer due to its non-invasive nature. However, the pro-inflammatory necrotic cell death during PTT limits its successful clinical application. Here, we have developed quercetin (QE) loaded biodegradable plasmonic nanoparticles that can specifically induce apoptosis in cancer cells after PTT. We have synthesized gold-coated liposome (LiposAu) and QE loaded gold-coated liposome (QE-LiposAu) nanoparticles by in situ reduction of chloroauric acid with ascorbic acid in the presence of bare liposomes (Lipos) or QE loaded liposomes (QE-Lipos), respectively. The gold coating was confirmed by transmission electron microscopic analysis, dynamic light scattering, and zeta potential measurements. LiposAu and QE-LiposAu nanoparticles showed a similar level of temperature rise upon 750 nm near-infrared (NIR) laser (650 mW, 3 W cm-2) irradiation. The photothermal conversion efficiency of QE-LiposAu nanoparticles was determined to be ~75%. The efficacy of PTT was found to be dependent on the internalization efficiency of LiposAu nanoparticles in cancer cells. Importantly, QE-LiposAu nanoparticles showed increased PTT efficacy over LiposAu nanoparticles in hepatocellular carcinoma cells (Huh-7). Moreover, QE-LiposAu nanoparticles induced apoptosis-mediated cell death after the PTT, and the extent of apoptosis was significantly higher than the LiposAu nanoparticles in Huh-7 cells. Further, QE-LiposAu nanoparticles-mediated PTT depolymerized microtubules network, suppressed Hsp70 expression, and caused DNA damage. QE-LiposAu nanoparticles were also found to be hemocompatible. The results together suggested that biodegradable QE-LiposAu nanoparticles are promising photothermal agents for cancer therapy.

    关键词： heat shock protein,liposome,microtubule,apoptosis,gold nanoparticles,DNA damage,Photothermal therapy

    更新于2025-09-12 10:27:22

  • Effect of Heat Treatment on Microstructure and Properties of FGH4096M Superalloy Processed by Selective Laser Melting

    摘要： A self-designed nickel-based superalloy, designated as FGH4096M, was prepared by selective laser melting (SLM). Different heat treatments were performed to improve the mechanical properties of the SLM alloy through optimizing the microstructures and the features of γ′ precipitates. Compared with the as-deposited alloy, the columnar grains with dendritic structures and equiaxed structures were retained in the alloy after direct aging, but a large amount of tertiary γ′ phase precipitated, especially around the sub-grain boundaries, resulting in the highest tensile strength but the lowest elongation. During solid solution and aging treatment (SSA), the recovery and recrystallization occurring in the alloy facilitated the grains to be equiaxed with the increase of solution temperature. For lower solution temperature (below 1100 ℃), the secondary γ′ precipitates decreased with the increase of solution temperature, while the tertiary γ′ precipitates from the subsequent aging process gradually increased; for higher solution temperature over 1100 ℃, exceeding the complete dissolution temperature of the γ′ phase, only tertiary γ′ precipitates from the subsequent aging process were uniformly distributed in the alloy. After double solid solution (1170 ℃ + 1050 ℃) + aging heat treatment (DSSA), there were three sizes of γ′ precipitates in the alloy. In general, the SLM + SSA (1130 ℃) alloy obtained the best comprehensive properties, which could be related to the homogenized microstructures and the uniform and dense distribution of single sized tertiary γ′ precipitates in the alloy.

    关键词： Microstructure,Nickel-based superalloy,Selective laser melting,Tensile,γ′ phase,Heat treatment

    更新于2025-09-12 10:27:22

  • Study of heat treatment impact on the surface defects appearance on samples obtained by selective laser melting of Ti-6Al-4V during chemical polishing

    摘要： Among advantages of selective laser melting (SLM) there are some problems in titanium alloys surface roughness after the sintering. Present work illustrates results of roughness measurements of Ti-6Al-44V titanium alloy samples after selective laser melting, heat treatment, mechanical brushing and acid polishing. It was found that surface roughness of SLM samples depends on heat treatment and chemical polishing modes; the biggest roughness is noted after the oil quenching from 950 (cid:1)C with subsequent aging at 650 (cid:1)C during 120 min. The best surface quality was obtained after annealing for 2 h at 650 (cid:1)C, water quenching at 950 (cid:1)C, mechanical brushing and chemical polishing.

    关键词： Chemical polishing,Titanium alloy,Heat treatment,Selective laser melting,Surface roughness

    更新于2025-09-12 10:27:22

  • Demand-Side Management of Air-Source Heat Pump and Photovoltaic Systems for Heating Applications in the Italian Context

    摘要： Matching demand pro?le and solar irradiance availability is necessary to meet space heating and domestic hot water needs by means of an air-source heat pump and photovoltaic system in a single-family house. Demand-side management, with smart control of the water storage set-point, is a simple but effective technique. Several studies in the literature pursue demand-side matching and self-consumption goals through system adjustments based on the model predictive control. This study proposes a rule-based control strategy, based on instantaneous photovoltaic (PV) power production, with the purpose of enhancing the self-consumption. This strategy exploits the building’s thermal capacitance as a virtual battery, and the thermal storage capacity of the system by running the heat pump to its limit when PV surplus power is available, and by eventually using an electric heater in order to reach higher temperatures. Results of annual dynamic simulations of a building and its heating system show that the proposed rule-based control strategy is able to reduce signi?cantly the energy exchanges between the system and the grid. Despite the enlarged renewable energy share, economic analysis points out the pursuit of the self-consumption goal may lead to a diminution of the economic advantage in the Italian context (Italian weather data and the electric power pricing scheme).

    关键词： net-metering,demand-side management,photovoltaic,self-consumption,air-source heat pump

    更新于2025-09-11 14:15:04