scholarly journals A Combination of Spatial Domain Filters to Detect Surface Ocean Current from Multi-Sensor Remote Sensing Data

2022 ◽  
Vol 14 (2) ◽  
pp. 332
Author(s):  
Mohammed Abdul Athick AS ◽  
Shih-Yu Lee
Keyword(s):  
Heat Flux ◽  
Remote Sensing Data ◽  
Total Heat ◽  
Sea Surface ◽  
Ocean Current ◽  
Surface Currents ◽  
Total Heat Flux ◽  
Data Set ◽  
Surface Ocean ◽  
Natural Break

This research investigates the applicability of combining spatial filter’s algorithm to extract surface ocean current. Accordingly, the raster filters were tested on 80–13,505 daily images to detect Kuroshio Current (KC) on weekly, seasonal, and climatological scales. The selected raster filters are convolution, Laplacian, north gradient, sharpening, min/max, histogram equalization, standard deviation, and natural break. In addition, conventional data set of sea surface currents, sea surface temperature (SST), sea surface height (SSH), and non-conventional data such as total heat flux, surface density (SSD), and salinity (SSS) were employed. Moreover, controversial data on ocean color are included because very few studies revealed that chlorophyll-α is a proxy to SST in the summer to extract KC. Interestingly, the performance of filters is uniform and thriving for seasonal and on a climatological scale only by combining the algorithms. In contrast, the typical scenario of identifying Kuroshio signatures using an individual filter and by designating a value spectrum is inapplicable for specific seasons and data set. Furthermore, the KC’s centerlines computed from SST, SSH, total heat flux, SSS, SSD, and chlorophyll-α correlate with sea surface currents. Deviations are observed in the various segments of Kuroshio’s centerline extracted from heat flux, chlorophyll-α, and SSS flowing across Tokara Strait from northeast Taiwan to the south of Japan.

Aero-Thermal Investigation of Tip Leakage Flow in a Film Cooled Industrial Turbine Rotor

2008 ◽  
Author(s):  
S. K. Krishnababu ◽  
H. P. Hodson ◽  
G. D. Booth ◽  
G. D. Lock ◽  
W. N. Dawes
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Mass Flow ◽  
Turbine Rotor ◽  
Total Heat ◽  
Leakage Flow ◽  
Total Heat Flux ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Flow And Heat Transfer

A numerical investigation of the flow and heat transfer characteristics of tip leakage in a typical film cooled industrial gas turbine rotor is presented in this paper. The computations were performed on a rotating domain of a single blade with a clearance gap of 1.28% chord in an engine environment. This standard blade featured two coolant and two dust holes, in a cavity-type tip with a central rib. The computations were performed using CFX 5.6, which was validated for similar flow situations by Krishnababu et al., [18]. These predictions were further verified by comparing the flow and heat transfer characteristics computed in the absence of coolant ejection with computations previously performed in the company (SIEMENS) using standard in-house codes. Turbulence was modelled using the SST k-ω turbulence model. The comparison of calculations performed with and without coolant ejection has shown that the coolant flow partially blocks the tip gap, resulting in a reduction of the amount of mainstream leakage flow. The calculations identified that the main detrimental heat transfer issues were caused by impingement of the hot leakage flow onto the tip. Hence three different modifications (referred as Cases 1 to 3) were made to the standard blade tip in an attempt to reduce the tip gap exit mass flow and the associated impingement heat transfer. The improvements and limitations of the modified geometries, in terms of tip gap exit mass flow, total area of the tip affected by the hot flow and the total heat flux to the tip, are discussed. The main feature of the Case 1 geometry is the removal of the rib and this modification was found to effectively reduce both the total area affected by the hot leakage flow and total heat flux to the tip while maintaining the same leakage mass flow as the standard blade. Case 2 featured a rearrangement of the dust holes in the tip which, in terms of aero-thermal-dynamics, proved to be marginally inferior to Case 1. Case 3, which essentially created a suction-side squealer geometry, was found to be inferior even to the standard cavity tip blade. It was also found that the hot spots which occur in the leading edge region of the standard tip and all modifications contributed significantly to the area affected by the hot tip leakage flow and the total heat flux.

scholarly journals Round robin study of total heat flux gauge calibration at fire laboratories

2004 ◽  
Author(s):  
William M Pitts ◽  
Annageri V Murthy ◽  
John L deRis ◽  
Jean-Remy R Filtz ◽  
Kjell Nygard ◽  
...  
Keyword(s):  
Heat Flux ◽  
Round Robin ◽  
Total Heat ◽  
Total Heat Flux

scholarly journals On Capabilities of Tracking Marine Surface Currents Using Artificial Film Slicks

2019 ◽  
Vol 11 (7) ◽  
pp. 840 ◽  
Author(s):  
Ivan Kapustin ◽  
Olga Shomina ◽  
Alexey Ermoshkin ◽  
Nikolay Bogatov ◽  
Alexander Kupaev ◽  
...  
Keyword(s):  
Water Film ◽  
Remote Sensing Data ◽  
Sea Surface ◽  
Application Of Surfactants ◽  
Surface Currents ◽  
Band Formation ◽  
Suggested Approach ◽  
Marine Currents ◽  
Sar Imagery ◽  
Film Spreading

It is known that films on the sea surface can appear due to ship pollution, river and collector drains, as well as natural biological processes. Marine film slicks can indicate various geophysical processes in the upper layer of the ocean and in the atmosphere. In particular, slick signatures in SAR-imagery of the sea surface at low and moderate wind speeds are often associated with marine currents. Apart from the current itself, other factors such as wind and the physical characteristics of films can significantly influence the dynamics of slick structures. In this paper, a prospective approach aimed at measuring surface currents is developed. The approach is based on the investigation of the geometry of artificial banded slicks formed under the action of marine currents and on the retrieval of the current characteristics from this geometry. The developed approach is applied to quasi stationary slick bands under conditions when the influence of the film spreading effects can be neglected. For the stationary part of the slick band where transition processes of the band formation, e.g., methods of application of surfactants on water, film spreading processes, possible wind transformation etc., become negligible, some empirical relations between the band geometrical characteristics and the characteristics of the surface currents are obtained. The advantage of the approach is a possibility of getting information concerning the spatial structure of marine currents along the entire slick band. The suggested approach can be efficient for remote sensing data verification.

scholarly journals Numerical Simulation of Thawing Process in Frozen Soil

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Zhaoyu Yan ◽  
Wei Pan ◽  
Junjie Fang ◽  
Zihui Liu
Keyword(s):  
Numerical Simulation ◽  
Heat Flux ◽  
Liquid Water ◽  
Minimum Temperature ◽  
Frozen Soil ◽  
Total Heat ◽  
Water Volume ◽  
Total Heat Flux ◽  
Volume Curve ◽  
Thawing Process

Permafrost has been thawing faster due to climate change which would release greenhouse gases, change the hydrological regimes, affect buildings above, and so on. It is necessary to study the thawing process of frozen soil. A water-heat coupling model for frozen soil thawing is established on Darcy’s law and Heat Transfer in Porous Media interfaces in Comsol Multiphysics 5.5. Three curves of total liquid water volume, minimum temperature, and total heat flux in the thawing process are obtained from a numerical simulation. The distributions of liquid water, temperature, and pressure based on time are simulated too. The liquid water distribution is consistent with the total liquid water volume curve. The temperature distribution is confirmed by the minimum temperature and total heat flux curve. The pressure distribution represents ice in the frozen soil that generates negative pressure during the melting process. The numerical simulation research in this article deepens the understanding of the internal evolution in the process of frozen soil thawing and has a certain reference value for subsequent experimental research and related applications.

Energy balance from images in humid climate – SEBAL and METRIC

Agrometeoros ◽  
2018 ◽  
Vol 25 (2) ◽  
Author(s):  
Juliano Schirmbeck ◽  
Denise Cybis Fontana ◽  
Débora Regina Roberti ◽  
Lucimara Wolfarth Schirmbeck
Keyword(s):  
Heat Flux ◽  
Soil Cover ◽  
Sensible Heat Flux ◽  
Remote Sensing Data ◽  
Grain Production ◽  
Subtropical Region ◽  
Humid Climate ◽  
Data Set ◽  
Reference Measurements ◽  
Metric Model

Evapotranspiration is an important phenomenon to agriculture; therefore, this work aims at verifying the suitability of the SEBAL and METRIC models to estimate latent heat flux using remote sensing data from grain cultivation areas in the northwestern subtropical region of Rio Grande do Sul. This region stands out for grain production. The analyzed data set consisted of 84 dates distributed over a 3-year period of areas planted with soy, corn, oats, wheat, and vetch crops. The data estimated from the remote images were compared with the reference measurements acquired in a micrometeorological station using the Eddy Covariance technique. Both models presented satisfactory results. However, the LE estimated by the METRIC model had the lowest error for all 3 types of soil cover analyzed. The best performance of the METRIC model is attributed to the fact that it does not require extreme water condition, i.e. for LE equal to zero, to determine the hot pixel when estimating the sensible heat flux, unlike the SEBAL model.

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