Parameters of dust-gas cloud spread resulting from a caving-in explosion

2012 ◽  
pp. 529-532
Author(s):  
K Trubetskoy ◽  
S Victorov ◽  
V Zakalinsky ◽  
A Kochanov ◽  
M Etkin
Keyword(s):  
Gas Cloud

scholarly journals Intelligent Mobile Wireless Network for Toxic Gas Cloud Monitoring and Tracking

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3625
Author(s):  
Mateusz Krzysztoń ◽  
Ewa Niewiadomska-Szynkiewicz
Keyword(s):  
Data Exchange ◽  
Mobility Model ◽  
Model Parameters ◽  
Toxic Substances ◽  
Cloud Detection ◽  
Gas Dispersion ◽  
Gas Concentration ◽  
Cloud Monitoring ◽  
Optimal Values ◽  
Gas Cloud

Intelligent wireless networks that comprise self-organizing autonomous vehicles equipped with punctual sensors and radio modules support many hostile and harsh environment monitoring systems. This work’s contribution shows the benefits of applying such networks to estimate clouds’ boundaries created by hazardous toxic substances heavier than air when accidentally released into the atmosphere. The paper addresses issues concerning sensing networks’ design, focussing on a computing scheme for online motion trajectory calculation and data exchange. A three-stage approach that incorporates three algorithms for sensing devices’ displacement calculation in a collaborative network according to the current task, namely exploration and gas cloud detection, boundary detection and estimation, and tracking the evolving cloud, is presented. A network connectivity-maintaining virtual force mobility model is used to calculate subsequent sensor positions, and multi-hop communication is used for data exchange. The main focus is on the efficient tracking of the cloud boundary. The proposed sensing scheme is sensitive to crucial mobility model parameters. The paper presents five procedures for calculating the optimal values of these parameters. In contrast to widely used techniques, the presented approach to gas cloud monitoring does not calculate sensors’ displacements based on exact values of gas concentration and concentration gradients. The sensor readings are reduced to two values: the gas concentration below or greater than the safe value. The utility and efficiency of the presented method were justified through extensive simulations, giving encouraging results. The test cases were carried out on several scenarios with regular and irregular shapes of clouds generated using a widely used box model that describes the heavy gas dispersion in the atmospheric air. The simulation results demonstrate that using only a rough measurement indicating that the threshold concentration value was exceeded can detect and efficiently track a gas cloud boundary. This makes the sensing system less sensitive to the quality of the gas concentration measurement. Thus, it can be easily used to detect real phenomena. Significant results are recommendations on selecting procedures for computing mobility model parameters while tracking clouds with different shapes and determining optimal values of these parameters in convex and nonconvex cloud boundaries.

scholarly journals Is High-Velocity Cloud Complex C Associated with the Galactic Warp?

2003 ◽  
Vol 20 (3) ◽  
pp. 263-269 ◽  
Author(s):  
Daisuke Kawata ◽  
Christopher Thom ◽  
Brad K. Gibson
Keyword(s):  
High Latitude ◽  
High Velocity ◽  
Large Magellanic Cloud ◽  
Alternative Interpretation ◽  
North Polar ◽  
Gas Cloud ◽  
Cloud Complex ◽  
Galactic Warp ◽  
Velocity Cloud ◽  
Spiral Arm

AbstractWe test the hypothesis that high-velocity gas cloud Complex C is actually a high-latitude spiral arm extension in the direction of the Galactic warp, as opposed to the standard interpretation — that of a once extragalactic, but now infalling, gas cloud. A parallel Tree N-body code was employed to simulate the tidal interaction of a satellite perturber with the Milky Way. We find that a model incorporating a perturber of the mass of the Large Magellanic Cloud on a south to north polar orbit, crossing the disk at ˜15 kpc, does yield a high-velocity, high-latitude extension consistent with the spatial, kinematical, and column density properties of Complex C. Unless this massive satellite remains undiscovered because of either a fortuitous alignment with the Galactic bulge (feasible within the framework of the model), or the lack of any associated baryonic component, we conclude that this alternative interpretation appears unlikely.

STUDY OF GAS FUEL LEAKAGE AND EXPLOSION IN THE ENGINE ROOM OF A SMALL LNG-FUELED SHIP

2021 ◽  
Vol 161 (A3) ◽  
Author(s):  
Q G Zheng ◽  
W Q Wu ◽  
M Song
Keyword(s):  
Injury Risk ◽  
Engine Fuel ◽  
Limited Region ◽  
Gas Dispersion ◽  
Engine Room ◽  
Flammable Gas ◽  
Gas Fuel ◽  
Fuel Leakage ◽  
Gas Cloud ◽  
The Given

The engine fuel piping in LNG-fuelled ships’ engine room presents potential gas explosion risks due to possible gas fuel leakage and dispersion. A 3D CFD model with chemical reaction was described, validated and then used to simulate the possible gas dispersion and the consequent explosions in an engine room with regulations commanded ventilations. The results show that, with the given minor leaking of a fuel pipe, no more than 1kg of methane would accumulate in the engine room. The flammable gas clouds only exit in limited region and could lead to explosions with an overpressure about 12 mbar, presenting no injury risk to personnel. With the given major leaking, large region in the engine room would be filled with flammable gas cloud within tens of seconds. The gas cloud might lead to an explosion pressure of about 1 bar or higher, which might result in serious casualties in the engine room.

Study of Gas Fuel Leakage and Explosion in the Engine Room of a Small LNG-Fuelled Ship

2019 ◽  
Vol 161 (A3) ◽  
Keyword(s):  
Injury Risk ◽  
Engine Fuel ◽  
Limited Region ◽  
Gas Dispersion ◽  
Engine Room ◽  
Flammable Gas ◽  
Gas Fuel ◽  
Fuel Leakage ◽  
Gas Cloud ◽  
The Given

The engine fuel piping in LNG-fuelled ships’ engine room presents potential gas explosion risks due to possible gas fuel leakage and dispersion. A 3D CFD model with chemical reaction was described, validated and then used to simulate the possible gas dispersion and the consequent explosions in an engine room with regulations commanded ventilations. The results show that, with the given minor leaking of a fuel pipe, no more than 1kg of methane would accumulate in the engine room. The flammable gas clouds only exit in limited region and could lead to explosions with an overpressure about 12 mbar, presenting no injury risk to personnel. With the given major leaking, large region in the engine room would be filled with flammable gas cloud within tens of seconds. The gas cloud might lead to an explosion pressure of about 1 bar or higher, which might result in serious casualties in the engine room.

scholarly journals 3D moving mesh simulations of Galactic center cloud G2

2013 ◽  
Vol 9 (S303) ◽  
pp. 318-319 ◽  
Author(s):  
P. C. Fragile ◽  
P. Anninos ◽  
S. D. Murray
Keyword(s):  
Feeding Rate ◽  
Galactic Center ◽  
Equations Of State ◽  
Accretion Rate ◽  
Three Dimensional ◽  
Light Curves ◽  
Moving Mesh ◽  
Future Evolution ◽  
Sgr A ◽  
Gas Cloud

AbstractUsing three-dimensional, moving-mesh simulations, we investigate the future evolution of the recently discovered gas cloud G2 traveling through the galactic center. From our simulations we expect an average feeding rate onto Sgr A* in the range of (5−19) × 10−8M⊙ yr−1 beginning in 2014. This accretion varies by less than a factor of three on timescales ∼ 1 month, and shows no more than a factor of 10 difference between the maximum and minimum observed rates within any given model. These rates are comparable to the current estimated accretion rate in the immediate vicinity of Sgr A*, although they represent only a small (< 10%) increase over the current expected feeding rate at the effective inner boundary of our simulations (racc = 750 RS ∼ 1015 cm). We also explore multiple possible equations of state to describe the gas. In examining the Br-γ light curves produced from our simulations, we find that all of our isothermal models predict significant (factor of 10) enhancements in the luminosity of G2 as it approaches pericenter, in conflict with observations. Models that instead allow the cloud to heat as it is compressed do better at matching observations.

The effects of pipe length on gas cloud explosion characteristics in the contraction pipe

2021 ◽  
pp. 1-14
Author(s):  
Xue Li ◽  
Ning Zhou ◽  
Bing Chen ◽  
Yingying Xu ◽  
Xuwei Li ◽  
...  
Keyword(s):  
Pipe Length ◽  
Gas Cloud
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