- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Turbulence and Related Phenomena || The Turbulence Regime of the Atmospheric Surface Layer in the Presence of Shallow Cold Drainage Flows: Application of Laser Scintillometry
摘要： The presence of shallow cold flows in the atmospheric boundary layer (ABL) instigates changes in the turbulent regime of the atmospheric surface layer (ASL). This small scale flow circulation introduces radiative cooling controls over large areas in polar latitudes during winter. In this study, microscale dynamic and turbulent variables have been obtained in the framework of the Winter Boundary Layer Experiment in Fairbanks, Alaska, developed during the winters of 2009/2010 and 2010/2011. Multiscale surface turbulence observations based on Eddy covariance and laser scintillometry were combined with Doppler acoustic sounding to document simultaneous changes in the ABL flow and ASL turbulence. We computed changes in momentum and heat fluxes characterizing intermittent and persistent modes of the drainage flow over three study cases. On the basis of laser scintillometry observations, we argue that a significant source of turbulence aiming at the surface fluxes has origins in the upper level shear-induced thermal turbulence at the top of the ABL.
关键词： stable boundary layer,surface turbulence,optical scintillation,radiative cooling,small scale drainage flows
更新于2025-09-19 17:13:59
-
[IEEE 2019 International Seminar on Research of Information Technology and Intelligent Systems (ISRITI) - Yogyakarta, Indonesia (2019.12.5-2019.12.6)] 2019 International Seminar on Research of Information Technology and Intelligent Systems (ISRITI) - 2D Heat Distribution Mapping of Monocrystalline Type Photovoltaic Placed in Universitas Budi Luhur Jakarta
摘要： Due to exposure to direct sunlight, rooftop PV panels often from heating. Performance of monocrystalline photovoltaic (MCPV) cell/panel is affected by its thermal properties, therefore, this research aims to measure the performance of MCPV through 2-dimensional heat mapping to determine the most efficient cooling scheme for the PV its most optimum performance. The measurement, mapping, and calculation is conducted on an array of experimental rooftop PV panel installed on a building, heat mapping data is taken from 55 points on PV surface. Measurement result shows that the high temperature of the MCPV panel is around 58,6oC – 64,7oC. Based on the results, the recommendation of temperature sensor placement for the cooling process is located at point 23 and 47 .
关键词： photovoltaic,monocrystalline,Heat mapping,optimization,performance,cooling
更新于2025-09-19 17:13:59
-
Double-passage mechanical cooling in a coupled optomechanical system
摘要： We consider a three-mode optomechanical system where two cavity modes are coupled to a common mechanical oscillator. We focus on the resolved sideband limit and illustrate the relation between the significant parameters of the system and the instantaneous-state mean phonon number of the oscillator optical coupling set up a correlation between the two cavity modes, which has significant effect on the cooling process. Using numerical solutions, we find that the inter-cavity coupling will decrease the cooling effect when both cavities have the same effective optomechanical coupling. However, when the effective optomechanical couplings are different, the cooling effect will be strongly improved by selecting appropriate range of inter-cavity coupling.
关键词： Ground-state cooling,Optomechanical system,Quantum optics
更新于2025-09-19 17:13:59
-
[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Research on Fabrication Method of High Stability Long Period Fiber Grating
摘要： We investigate thermal effects of pulmonary cooling which was induced by cold air through an endotracheal tube via a ventilator on newborn piglets. A mathematical model was initially employed to compare the thermal impact of two different gas mixtures, O2-medical air (1:2) and O2-Xe (1:2), across the respiratory tract and within the brain. Following mathematical simulations, we examined the theoretical predictions with O2-medical air condition on nine anesthetized piglets which were randomized to two treatment groups: 1) control group (n = 4) and 2) pulmonary cooling group (n = 5). Numerical and experimental results using O2-medical air mixture show that brain temperature fell from 38.5 ?C and 38.3 ?C ± 0.3 ?C to 35.7 ?C ± 0.9 ?C and 36.5 ?C ± 0.6 ?C during 3 h cooling which corresponded to a mean cooling rate of 0.9 ?C/h ± 0.2 ?C/h and 0.6 ?C/h ± 0.1 ?C/h, respectively. According to the numerical results, decreasing the metabolic rate and increasing air velocity are helpful to maximize the cooling effect. We demonstrated that pulmonary cooling by cooling of inhalation gases immediately before they enter the trachea can slowly reduce brain and core body temperature of newborn piglets. Numerical simulations show no significant differences between two different inhaled conditions, i.e., O2-medical air (1:2) and O2-Xe (1:2) with respect to cooling rate.
关键词： brain,bio-heat transfer,Pulmonary cooling,piglet,numerical simulation
更新于2025-09-19 17:13:59
-
Quantitative trade-off analysis of infrared light absorber effects contributed to photovoltaic cells performance
摘要： It is widely known that organic and inorganic coatings absorb more of the solar spectrum, and due to a considerable share of 45% infrared radiation, the energy efficiency drop by the increasing of temperature should be considered. The purpose of this study is to implement a system to characterize silicon solar cell performance and increasing energy efficiency by imposing such coatings as infrared wave absorber to overcome the Shockley–Queisser limit. In other words, this research efforts to improve cell efficiency (coating effects) in addition to imposing the efficiency decreasing effects (temperature increasing). The core of the study is laboratory and experimental set-up measurements to find an organic absorber with the highest absorbance. Ruthenium-based dye, N719, has shown the best performance in experimental conditions and heat extraction to enhance cell energy efficiency. Due to increased absorption in a solar cell (SC), to control the temperature rise of the system, the fan is used as a cooling system. The imposing of N719 results in increasing energy efficiency by up to 1.38%. It is worth noting that a 1.60% increase in energy efficiency is observed due to temperature reduction by 2 degrees.
关键词： Experimental set-up,Photovoltaic cell,Organic absorbent N719,Cooling system,Energy efficiency
更新于2025-09-19 17:13:59
-
Simulation and Experimental Based Analysis of the Laser Beam Welding of DP Steels
摘要： In this paper, heat affected zone characteristics of DP1000 steels was investigated during diode laser beam welding (LBW). A butt-welded joint of specimen in dimension of 300 x 150 mm each (according to EN15614-11:2002) with 1 mm thickness is used for the experimental purpose. The welding thermal cycle and the cooling circumstances in the HAZ was determined by real experiment and the physical simulation. A Gleeble 3500 thermo-physical simulator was used to physically simulate the coarse grain heat affected zone (CGHAZ) on the base material specimens by the utilization of the thermal cycles for t8/5 =2.5 s. The results of the physical simulation were validated by real welding experiments. The properties of the simulated and the real HAZ was examined by optical microscopic, scanning electron microscope and hardness tests.
关键词： Gleeble 3500 physical simulator,t8/5 cooling time,Laser beam welding (LBW),dual phase (DP) steel,Heat affected zone (HAZ) characterization
更新于2025-09-19 17:13:59
-
Phonon-Mediated and Weakly Size-Dependent Electron and Hole Cooling in CsPbBr <sub/>3</sub> Nanocrystals Revealed by Atomistic Simulations and Ultrafast Spectroscopy
摘要： We combine state-of-the-art ultrafast photoluminescence and absorption spectroscopy and nonadiabatic molecular dynamics simulations to investigate charge-carrier cooling in CsPbBr3 nanocrystals over a very broad size regime, from 0.8 nm to 12 nm. Contrary to the prevailing notion that polaron formation slows down charge-carrier cooling in lead-halide perovskites, no suppression of carrier cooling is observed in CsPbBr3 nanocrystals except for a slow cooling (over ~ 10 ps) of ‘warm’ electrons in the vicinity (within ~ 0.1 eV) of the conduction band edge. At higher excess energies, electrons and holes cool with similar rates, on the order of 1 eV ps-1 carrier-1 and increasing weakly with size. Our ab initio simulations suggest that cooling proceeds via fast phonon-mediated intra-band transitions driven by strong and size-dependent electron-phonon coupling. The presented experimental and computational methods yield the spectrum of involved phonons and may guide the development of devices utilizing hot charge carriers.
关键词： electron-phonon coupling,hot carriers,nonadiabatic molecular dynamics,Charge-carrier cooling,lead-halide perovskite nanocrystal,excited-states dynamics
更新于2025-09-19 17:13:59
-
Precise Potential Observation of a Biased GaAs p-n Junction by <i>in situ</i> Phase-shifting Electron Holography; é????§??°??????GaAs p-n??￥??????é???2??o|é???-??·??????-??°????????￡???????????′è|3?ˉ?;
摘要： 昨今，半導体デバイスの研究開発において，動作中の電位温度 120 K の低温下でバルク試料の一部を薄膜化することにより作製した．この試料を電圧印加用 TEM 試料ホルダーにセットし，外部電源と電気的に接続することで TEM 内試料への電圧印加を可能とした．観察はホログラフィー電子顕微鏡(HF3300EH)を用いて加速電圧 300 kV で実施した．位相シフト法による位相再生には，入射電子線の初期位相をシフトして撮影した50枚のホログラムを用いた．
关键词： pn junction,cooling focused ion beam,electron beam holography
更新于2025-09-19 17:13:59
-
Resolved-Sideband Cooling of a Levitated Nanoparticle in the Presence of Laser Phase Noise
摘要： We investigate the influence of laser phase noise heating on resolved sideband cooling in the context of cooling the center-of-mass motion of a levitated nanoparticle in a high-finesse cavity. Although phase noise heating is not a fundamental physical constraint, the regime where it becomes the main limitation in Levitodynamics has so far been unexplored and hence embodies from this point forward the main obstacle in reaching the motional ground state of levitated mesoscopic objects with resolved sideband cooling. We reach minimal center-of-mass temperatures comparable to Tmin ? 10 mK at a pressure of p ? 3 × 10?7 mbar, solely limited by phase noise. Finally we present possible strategies towards motional ground state cooling in the presence of phase noise.
关键词： levitated nanoparticle,laser phase noise,resolved sideband cooling,ground state cooling,optomechanical cooling
更新于2025-09-16 10:30:52
-
Solar Engineering of Thermal Processes, Photovoltaics and Wind || Solar Cooling
摘要： The use of solar energy to drive cooling cycles has been considered for two related purposes, to provide refrigeration for food preservation and to provide comfort cooling. In Section 15.1 we briefly review some of the literature relating to both of the applications, since there is a common underlying technology. From then on, we concentrate on problems relating to solar air conditioning. In particular, for application in temperate climates, we address questions of the use of flat-plate collectors for both winter heating and summer cooling.
关键词： flat-plate collectors,cooling cycles,refrigeration,comfort cooling,solar air conditioning,solar energy
更新于2025-09-16 10:30:52