SPATIAL DISTRIBUTION OF AIR FLOW AND CO2 CONCENTRATION IN A NATURALLY VENTILATED DAIRY BUILDING

2014 ◽  
Vol 13 (9) ◽  
pp. 2193-2200 ◽  
Author(s):  
Merike Fiedler ◽  
Chayan K. Saha ◽  
Christian Ammon ◽  
Werner Berg ◽  
Christiane Loebsin ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Air Flow ◽  
Co2 Concentration

scholarly journals Multi-Year Comparison of CO2 Concentration from NOAA Carbon Tracker Reanalysis Model with Data from GOSAT and OCO-2 over Asia

2020 ◽  
Vol 12 (15) ◽  
pp. 2498
Author(s):  
Farhan Mustafa ◽  
Lingbing Bu ◽  
Qin Wang ◽  
Md. Arfan Ali ◽  
Muhammad Bilal ◽  
...  
Keyword(s):  
Time Series ◽  
Spatial Distribution ◽  
Atmospheric Carbon Dioxide ◽  
Carbon Budget ◽  
Co2 Concentration ◽  
Mitigation Strategies ◽  
Spatial Correlations ◽  
Western Asia ◽  
Carbon Dioxide Co2 ◽  
Good Agreement

Accurate knowledge of the carbon budget on global and regional scales is critically important to design mitigation strategies aimed at stabilizing the atmospheric carbon dioxide (CO2) emissions. For a better understanding of CO2 variation trends over Asia, in this study, the column-averaged CO2 dry air mole fraction (XCO2) derived from the National Oceanic and Atmospheric Administration (NOAA) CarbonTracker (CT) was compared with that of Greenhouse Gases Observing Satellite (GOSAT) from September 2009 to August 2019 and with Orbiting Carbon Observatory 2 (OCO-2) from September 2014 until August 2019. Moreover, monthly averaged time-series and seasonal climatology comparisons were also performed separately over the five regions of Asia; i.e., Central Asia, East Asia, South Asia, Southeast Asia, and Western Asia. The results show that XCO2 from GOSAT is higher than the XCO2 simulated by CT by an amount of 0.61 ppm, whereas, OCO-2 XCO2 is lower than CT by 0.31 ppm on average, over Asia. The mean spatial correlations of 0.93 and 0.89 and average Root Mean Square Deviations (RMSDs) of 2.61 and 2.16 ppm were found between the CT and GOSAT, and CT and OCO-2, respectively, implying the existence of a good agreement between the CT and the other two satellites datasets. The spatial distribution of the datasets shows that the larger uncertainties exist over the southwest part of China. Over Asia, NOAA CT shows a good agreement with GOSAT and OCO-2 in terms of spatial distribution, monthly averaged time series, and seasonal climatology with small biases. These results suggest that CO2 can be used from either of the datasets to understand its role in the carbon budget, climate change, and air quality at regional to global scales.

scholarly journals Macroscopic Effects of Surface Roughness in Confined Air-Flow

2002 ◽  
Author(s):  
M’hamed Boutaous ◽  
Patrick Bourgin
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Surface Roughness ◽  
Spatial Distribution ◽  
Surface Topography ◽  
Air Flow ◽  
Threshold Value ◽  
Squeeze Flow ◽  
Real Surface ◽  
Plastic Films

The general framework deals with the winding of thin plastic films. It is well known by the man-of-the art that the “windability” of plastic films is mainly governed by their surface topography. One key issue is then to optimize their surface topography so that to improve the quality of the wound roll. In a previous work, we proposed a simple model which considers the flow of an air layer squeezed between a solid smooth substrate and a plastic film sample : it was shown experimentally that the macroscopic characteristics of the flow are connected to the film roughness, but how? To answer this question, we assimilate the confined air flow to a flow through a periodic array of cylinders. A mathematical model based on homogenization techniques was proposed, where the heights of the cylinders, their diameter and their spatial distribution are the governing parameters. In the present paper, we propose pertinent parameters which describes the real surface roughness of plastic films fairly well. The measurements were carried out by using a 3D roughness measurement device. The first observation is that the films roughness distribution is not uniform, but forms “packages” (agglomerates) giving place to large packs of roughness. We made a sampling at different levels expressed by the percentage of peaks exceeding some given height. The heights of the peaks over a threshold value are averaged and the corresponding averaged value will be regarded as the initial gap in the squeeze flow model. Now, the networks of cylinders is built as follows : • The cylinder diameters is the averaged width of the large peaks, • The distance between the cylinder axes is the mean value of the spatial distribution of the peaks. Thus, for each type of film, the threshold value will be the only adjustable parameter. Introducing these parameters into the mathematical model which predicts the evolution of the squeezed air layer and comparing to the experimental data, the following results are obtained: (1) It is possible to adjust one single parameter so that to obtain a very good agreement between the experimental data and the theoretical results. (2) The smoother the film, the more important the highest peaks are in terms of air leakage.

Experiments on Front- and Aft- Disk Cavity Ingestion in a Subscale 1.5-Stage Axial Turbine

2016 ◽  
Author(s):  
J. Balasubramanian ◽  
M. Michael ◽  
R. P. Roy ◽  
Y. W. Kim ◽  
H. K. Moon
Keyword(s):  
Air Flow ◽  
Co2 Concentration ◽  
Initial Step ◽  
Labyrinth Seal ◽  
Radial Clearance ◽  
Tracer Gas ◽  
Experimental Conditions ◽  
Flow Rates ◽  
Static Pressure Distribution ◽  
Mass Flow Rates

This paper describes experiments performed in a subscale 1.5-stage axial air turbine in which ingestion of mainstream air into the front and aft disk cavities was measured. The front disk cavity is upstream of the rotor, the aft disk cavity is downstream of the rotor. Both disk cavities contain a labyrinth seal at a radially inboard location; this seal divides the cavity into a ‘rim cavity’ and an ‘inner cavity’. The front rim cavity features a double seal with radial clearance and axial overlap at its periphery; the aft rim cavity double seal possesses axial gap. Results are reported for three experiment sets, each set defined by the main air flow rate and rotor speed. Furthermore, each set comprises four different purge air flow rates. The initial step in each experiment was the measurement of time-average static pressure distribution in the main gas annulus and the disk cavities to establish the steady-state pressure differentials that contribute to ingestion into and egress from the cavities. This was followed by the measurement of tracer gas (CO2) concentration distribution in the disk cavities to quantify the ingestion. In addition to the pressure and concentration (in terms of sealing effectiveness) results, the mass flow rates of ingested main air into the front and aft rim cavities are reported for the various experimental conditions. Both inner cavities were found to be completely sealed against ingestion. Ingestion and egress discharge coefficients based on an orifice model are reported for the front and aft double rim seals; their trends are quite different from those of single rim seals with axial overlap and radial clearance reported earlier.

Lithography below 100 nm

1983 ◽  
Vol 41 ◽  
pp. 96-99
Author(s):  
L. D. Jackel
Keyword(s):  
Spatial Distribution ◽  
Electron Beam ◽  
Electron Scattering ◽  
Electron Beam Lithography ◽  
Substrate Material ◽  
Local Electron ◽  
Electron Dose ◽  
Positive Resist ◽  
Exposure Process

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile” , also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.

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