scholarly journals The Radiative Transfer Characteristics of the O2 Infrared Atmospheric Band in Limb-Viewing Geometry

2019 ◽  
Vol 11 (22) ◽  
pp. 2702 ◽  
Author(s):  
Weiwei He ◽  
Kuijun Wu ◽  
Yutao Feng ◽  
Di Fu ◽  
Zhenwei Chen ◽  
...  
Keyword(s):  
Thermal Characteristics ◽  
Spectroscopic Properties ◽  
Upper Atmosphere ◽  
Transfer Model ◽  
Spectral Brightness ◽  
Spectral Parameters ◽  
Line Shapes ◽  
Compositional Structures ◽  
Important Means ◽  
Significant Region

The O2(a1Δg) emission near 1.27 μm provides an important means to remotely sense the thermal characteristics, dynamical features, and compositional structures of the upper atmosphere because of its photochemistry and spectroscopic properties. In this work, an emission–absorption transfer model for limb measurements was developed to calculate the radiation and scattering spectral brightness by means of a line-by-line approach. The nonlocal thermal equilibrium (non-LTE) model was taken into account for accurate calculation of the O2(a1Δg) emission by incorporating the latest rate constants and spectral parameters. The spherical adding and doubling methods were used in the multiple scattering model. Representative emission and absorption line shapes of the O 2 ( a 1 Δ g , υ ′ = 0 ) → O 2 ( X Σ g 3 , υ ″ = 0 ) band and their spectral behavior varying with altitude were examined. The effects of solar zenith angle, surface albedo, and aerosol loading on the line shapes were also studied. This paper emphasizes the advantage of using infrared atmospheric band for remote sensing of the atmosphere from 20 up to 120 km, a significant region where the strongest coupling between the lower and upper atmosphere occurs.

The O2(b1Σ) dayglow emissions: application to middle and upper atmosphere remote sensing1This article is part of a Special issue that honours the work of Dr. Donald M. Hunten FRSC who passed away in December 2010 after a very illustrious career.

2012 ◽  
Vol 90 (8) ◽  
pp. 769-784 ◽  
Author(s):  
Jeng-Hwa Yee ◽  
R. DeMajistre ◽  
F. Morgan
Keyword(s):  
Remote Sensing ◽  
Cross Sections ◽  
Upper Atmosphere ◽  
Lower Atmosphere ◽  
Spectral Parameters ◽  
Sources And Sinks ◽  
Atmospheric Remote Sensing ◽  
Compositional Structures ◽  
Important Means ◽  
Band Transition

The O2atmospheric band transition is observed in the altitude region between ∼40 and 200 km in the dayglow and between ∼80 and 100 km in the nightglow. Wallace and Hunten (J. Geophys. Res. 73, 4813 (1968)) presented the first detailed analysis of the sources and sinks of this O2airglow emitting state. Because of its extended altitude coverage, bright signal, and spectral and photometric properties, this emission provides an important means to remotely sense the thermal, dynamical, and compositional structures of the upper atmosphere. In this paper we present a photochemical and emission–absorption model that calculates the spectral brightnesses of the four brightest vibrational manifolds of this band system that, for the first time, extends from the mesosphere to the thermosphere. This model incorporates the latest rate constants, cross sections, and spectral parameters relevant to this emission, some of which were not considered in previous remote sensing retrieval applications. The model results are compared with our previous rocket experiments to assess the utility of this emission for upper atmospheric remote sensing and to identify key future measurement challenges. This model, together with improved instrument capabilities, permits us to study the atmosphere from 40 up to 200 km, a region where the strongest coupling between the lower atmosphere and upper atmosphere occurs.

scholarly journals Resonance characteristics of transmissive optical filters based on metal/dielectric/metal structures

2020 ◽  
Vol 44 (2) ◽  
pp. 219-228
Author(s):  
D.V. Nesterenko
Keyword(s):  
Resonance Line ◽  
Structural Parameters ◽  
Propagation Constant ◽  
Field Enhancement ◽  
Optical Filters ◽  
Transfer Model ◽  
Optical Processing ◽  
Line Shapes ◽  
Fabry Perot ◽  
Normal Light

The resonance characteristics of the Fabry-Pérot resonator modes supported by metal/dielectric/metal planar structures are studied in the case of absorbing media for near-to-normal light incidence. Approximations based on rigorous solution and field-transfer model for the field and resonance line shapes in spectra are attributed to the class of Fano and Lorentz resonances. The analytical expressions are obtained for the propagation constant and field enhancement of the mode, width, height and slope of resonance line shapes in spectra as functions of structural parameters. With estimation of field characteristics of the fabricated loss structures based on aluminum and quartz, the peaks in the transmission spectra can be attributed to the excitation of Fabry-Pérot modes. Fundamental characterization of Fabry-Pérot resonances may find applications in optical processing and sensing.

Interfacial Heat Flux Estimation in a Funnel Shaped Mould and Analysis of Solidification Characteristics in Thin Slab Continuous Casting

2021 ◽  
Author(s):  
Pedduri Jayakrishna ◽  
Ananda Vaka ◽  
Saurav Chakraborty ◽  
Suvankar Ganguly ◽  
Prabal Talukdar
Keyword(s):  
Heat Flux ◽  
Continuous Casting ◽  
Molten Steel ◽  
High Speed ◽  
Thermal Characteristics ◽  
Submerged Entry Nozzle ◽  
Casting Process ◽  
Transfer Model ◽  
Thin Slab ◽  
Slab Continuous Casting

Abstract An inverse heat transfer model based on Salp Swarm optimization algorithm is developed for prediction of heat flux at the hot faces of a mould in thin slab continuous casting. The industrial mould considered in this work is a funnel-shaped mould having complex arrangement of cooling slots and holes. Significant variations of heat flux along the casting direction, as well as across the width are observed. Subsequently, the obtained heat flux profile estimated by the inverse method is used to analyse the fluid flow and thermal characteristics of the solidifying steel strand inside the mould. Three different recirculatory zones are present due to molten steel flow, affecting the thermal and solidification characteristics significantly. The effect of these recirculatory flows on remelting phenomenon, and consequent formation of thinner shell at the mould outlet leading to quality control issues in the casting process have been discussed. Another practical issue of depression in the wide face shell thickness at the mould outlet has been identified, and its cause has been related to the location of the Submerged Entry Nozzle and the high speed of the molten steel inflow.

scholarly journals Performance analysis of new structure heat exchanger based on field synergy and numerical simulation

2021 ◽  
Vol 260 ◽  
pp. 01019
Author(s):  
Xinpu Song ◽  
Feng Zhang ◽  
Jin Yu ◽  
Dongsheng Xi ◽  
Mengdi Chen
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Exchanger ◽  
High Efficiency ◽  
Cross Flow ◽  
Transfer Model ◽  
Field Synergy ◽  
Coupled Heat Transfer ◽  
Heat Transfer Efficiency ◽  
Important Means

High efficiency heat exchanger is always a hot topic, and field synergy theory is introduced as an important means to optimize the heat transfer efficiency. Based on the field synergy theory, a new type of heat exchanger is proposed in this paper, in which, the cold and hot fluid presents reverse cross flow law. Through the verification of the test and numerical simulation results, a reasonable numerical simulation model and method are obtained. Then, the flow and heat transfer conditions of the new structure heat exchanger are simulated by the verified numerical simulation technology. The conclusion is as follows: K-ε turbulence model and coupled heat transfer model can be effectively used in the numerical simulation of heat exchanger. And the reverse cross convection heat exchanger can effectively improve the uniformity of water temperature distribution in the heat exchanger.

Thermo-Hydraulic Research for Supercritical Water Reactor During Power-Raising Phase of Startup

2017 ◽  
Author(s):  
Li Zichao ◽  
Zhou Tao ◽  
Zhou Lanyu ◽  
Liu Liang ◽  
Chen Juan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Supercritical Water ◽  
Water Flow Rate ◽  
Thermal Characteristics ◽  
Transfer Model ◽  
Feed Water ◽  
Heat Transfer Deterioration ◽  
Power Increase ◽  
Water Reactors ◽  
Sliding Pressure

Thermal characteristics during startup of CSR1000 are directly related to the security of supercritical water reactors. The heat transfer model during power-raising phase is built according to the sliding pressure mode of CSR1000 and thermal characteristics of coolant and moderator are analyzed. The results show that, during the temperature-raising phase of startup, Coolant and moderator temperatures in inner assemblies increase with core power increase only. With increases of core power and feed-water flow rate, Coolant and moderator temperatures remain unchanged during power-raising phase. Thermal properties of the coolant change in the pseudo-critical temperature and the heat transfer deterioration occurs.

scholarly journals Evaluation of SSMIS Upper Atmosphere Sounding Channels for High-Altitude Data Assimilation

2013 ◽  
Vol 141 (10) ◽  
pp. 3314-3330 ◽  
Author(s):  
Karl W. Hoppel ◽  
Stephen D. Eckermann ◽  
Lawrence Coy ◽  
Gerald E. Nedoluha ◽  
Douglas R. Allen ◽  
...  
Keyword(s):  
High Altitude ◽  
Large Scale ◽  
Upper Atmosphere ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Brightness Temperatures ◽  
Broadband Emission ◽  
Geomagnetic Fields ◽  
Microwave Imager ◽  
New Community

Abstract Upper atmosphere sounding (UAS) channels of the Special Sensor Microwave Imager/Sounder (SSMIS) were assimilated using a high-altitude version of the Navy Global Environmental Model (NAVGEM) in order to investigate their potential for operational forecasting from the surface to the mesospause. UAS radiances were assimilated into NAVGEM using the new Community Radiative Transfer Model (CRTM) that accounts for Zeeman line splitting by geomagnetic fields. UAS radiance data from April 2010 to March 2011 are shown to be in good agreement with coincident temperature measurements from the Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER) instrument that were used to simulate UAS brightness temperatures. Four NAVGEM experiments were performed during July 2010 that assimilated (i) no mesospheric observations, (ii) UAS data only, (iii) SABER and Microwave Limb Sounder (MLS) mesospheric temperatures only, and (iv) SABER, MLS, and UAS data. Zonal mean temperatures and observation − forecast differences for the UAS-only and SABER+MLS experiments are similar throughout most of the mesosphere, and show large improvements over the experiment assimilating no mesospheric observations, proving that assimilation of UAS radiances can provide a reliable large-scale constraint throughout the mesosphere for operational, high-altitude analysis. This is confirmed by comparison of solar migrating tides and the quasi-two-day wave in the mesospheric analyses. The UAS-only experiment produces realistic tidal and two-day wave amplitudes in the summer mesosphere in agreement with the experiments assimilating MLS and SABER observations, whereas the experiment with no mesospheric observations produces excessively strong mesospheric winds and two-day wave amplitudes.

scholarly journals Effects of Nonuniform Incident Illumination on the Thermal Performance of a Concentrating Triple Junction Solar Cell

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Fahad Al-Amri ◽  
Tapas Kumar Mallick
Keyword(s):  
Solar Cell ◽  
Triple Junction ◽  
Cooling System ◽  
Incident Light ◽  
Thermal Characteristics ◽  
Surface Radiation ◽  
Transfer Model ◽  
Cell Temperature ◽  
Junction Solar Cell ◽  
Level I

A numerical heat transfer model was developed to investigate the temperature of a triple junction solar cell and the thermal characteristics of the airflow in a channel behind the solar cell assembly using nonuniform incident illumination. The effects of nonuniformity parameters, emissivity of the two channel walls, and Reynolds number were studied. The maximum solar cell temperature sharply increased in the presence of nonuniform light profiles, causing a drastic reduction in overall efficiency. This resulted in two possible solutions for solar cells to operate in optimum efficiency level: (i) adding new receiver plate with higher surface area or (ii) using forced cooling techniques to reduce the solar cell temperature. Thus, surface radiation exchanges inside the duct and Re significantly reduced the maximum solar cell temperature, but a conventional plain channel cooling system was inefficient for cooling the solar cell at medium concentrations when the system was subjected to a nonuniform light distribution. Nonuniformity of the incident light and surface radiation in the duct had negligible effects on the collected thermal energy.

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