scholarly journals Impact of Selected Electrical Cables Slope on Flame Out Time and Flame Spread

2019 ◽  
Vol 27 (44) ◽  
pp. 41-47
Author(s):  
Aleš Nečas ◽  
Jozef Martinka ◽  
Igor Wachter ◽  
Tomáš Štefko ◽  
Martina Hladová ◽  
...  
Keyword(s):  
Cross Section ◽  
Flame Spread ◽  
Horizontal Plane ◽  
Spread Rate ◽  
Cable System ◽  
Vertical Orientation ◽  
Electrical Cable ◽  
Horizontal Orientation ◽  
Electrical Cables ◽  
The Impact

Abstract The aim of the research described in this paper was to study the impact of the electrical cables slope on the flame out time and the flame spread rate. Measured cables were thermally loaded by methanol flame (diameter of the container was 106 mm) at seven different slopes with respect to the horizontal plane (the slopes were 0° – horizontal orientation, 15°, 30°, 45°, 60°, 75° and 90° - vertical orientation). The first tested electrical cable was a copper three-core power one resistant to the flame spread with circuit integrity of the cable system during 30 minutes under fire (cross-section of each core was 1.5 mm2). The second tested electrical cable was a copper two-core signal one resistant to the flame spread with circuit integrity of the cable system during 30 minutes under fire (cross-section of each core was 0.5 mm2). The first electrical cable did not show reaction to fire class. The reaction to fire class of the second tested cable was B2ca, s1, d1, a1. The obtained results proved that slope had virtually no impact on the flame out time and the flame spread over the tested cable surface (tested cables of all slopes stopped burning after 1 to 5 seconds after methanol flame burned out). Likewise, the flame spread was only negligibly beyond the border of flame action for each cable slope.

scholarly journals Temperature Field Evolution in Wood Samples During the Flame Spread Experiments

2014 ◽  
Vol 9 (1) ◽  
pp. 16-24
Author(s):  
Lucie Hasalová ◽  
Petr Vaněk ◽  
Milan Jahoda
Keyword(s):  
Cross Section ◽  
Flame Spread ◽  
Rectangular Cross Section ◽  
Small Scale ◽  
Temperature Profiles ◽  
Internal Temperature ◽  
Upward Flame Spread ◽  
Horizontal Orientation ◽  
Square Prism ◽  
Computational Fluid Dynamics Cfd

Abstract Vertical, horizontal and 45° upward flame spread experiments over the small scale beech and pine wood samples were performed. Wood samples were of two geometries - square cross section prisms (15 x 15 mm) and a thin rectangular cross section prisms (5 x 40 mm) - and of three different lengths - 10, 15 and 30 cm. Samples were ignited by a heptane source fire extinguished immediately when the wood samples ignited. During the flame spread an internal temperature profiles along the centreline of the samples were measured by a set of thermocouples. Flame spread was observed in all sample positions except the horizontal orientation of the beech and pine square prism samples. Experimental data will serve for a validation of the pyrolysis models in the Computational Fluid Dynamics (CFD) flame spread models.

scholarly journals Fire behaviors along timber linings affixed to tunnel walls in mines

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0260655
Author(s):  
Ke Gao ◽  
Zimeng Liu ◽  
Changfa Tao ◽  
Zhiqiang Tang ◽  
Yisimayili Aiyiti ◽  
...  
Keyword(s):  
Cross Section ◽  
Flame Spread ◽  
Maximum Temperature ◽  
Spread Rate ◽  
Smoke Movement ◽  
Fire Dynamics ◽  
Flame Spreading ◽  
Wind Speeds ◽  
Flame Spread Rate ◽  
Tunnel Cross Section

Timber linings are applied as primary supports in the tunnel fault and fracture zones of mines. These linings are essential to prevent broken rock from falling during the occurrence of exogenous fires. In this study, experiments and numerical simulations were carried out using a fire dynamics simulator to investigate the flame-spread rate, flame characteristics, smoke movement, and spread process of timber-lining fires under different wind speeds of 0, 0.25, 0.5, and 0.75 m/s. It was found that cross-section flame spreading follows the three-stage sidewall-ceiling-sidewall pattern. Moreover, the average flame-spread rate increases along the vertical flame-spreading direction and decreases when the flame reaches the timber-lining corners. Moreover, the flame lengths underneath the timber-lining ceiling in the x-direction are longer than those in the y-direction. As the wind speed increases, the normalized flame lengths R(f) in the two directions decrease, and the maximum temperature underneath the ceiling decreases. In addition, the maximum temperature in the three tunnel sections of interest is first recorded in the tunnel cross-section in the initial fire stage. Higher wind speeds correspond to farther distances of the maximum-temperature points of the three timber-lining sections from the fire source.

Postnatal Change in Angle between the Tympanic Annulus and Surrounding Structures

1997 ◽  
Vol 106 (1) ◽  
pp. 33-36 ◽  
Author(s):  
Akihiro Ikui ◽  
Masaharu Sudo ◽  
Isamu Sando ◽  
Shuji Fujita
Keyword(s):  
Horizontal Plane ◽  
Three Dimensional ◽  
Internal Auditory Canal ◽  
Oval Window ◽  
Developmental Relationships ◽  
Vertical Orientation ◽  
Horizontal Canal ◽  
Horizontal Orientation ◽  
Dimensional Reconstruction ◽  
Temporal Bones

Postnatal developmental relationships in human ears were studied by a computer-aided three-dimensional reconstruction and measurement method. We measured the angle, in reference to the horizontal plane, between the tympanic annulus, the oval window, and the internal auditory canal (IAC) in 20 normal temporal bones obtained from individuals between 1 day old and 76 years old. The horizontal plane was defined as the plane sloped 30° infero-anteriorly from the plane of the horizontal canal in each specimen. The plane of the tympanic annulus changed from a nearly horizontal orientation (34.2° from the horizontal plane) in neonates to a more vertical orientation (63.3° from the horizontal plane) in adults. The tympanic annulus and oval window planes remained at the same angle to each other (11.9° ± 5.1°) throughout postnatal development, as did the plane of the tympanic annulus and the LAC (68.6° ± 5.3°). These findings have implications for ear surgeons, especially those operating on young children.

scholarly journals Mechanical Behaviour of Unshelled Moringa oleifera Seeds at Varying Moisture Contents

2021 ◽  
Vol 2 (1) ◽  
pp. 88-103
Author(s):  
Samson NDUKWE ◽  
Nnaemeka NWAKUBA ◽  
Nkechi NGWANGWA
Keyword(s):  
Compressive Strength ◽  
Moisture Content ◽  
Moringa Oleifera ◽  
Block Design ◽  
Vertical Orientation ◽  
Moisture Contents ◽  
Horizontal Orientation ◽  
Rupture Energy ◽  
The Impact ◽  
Yield Force

The determination of mechanical properties of unshelled Moringa oleifera seeds was studied under compression test at varying orientations and moisture contents for postharvest equipment design. A completely randomized block design (CRBD) was applied in designing the experiment. The impact of varying moisture content levels of (10.25, 17.33, 24.47, and 32.34% dry basis) on the applied force at bio-yield and rupture, deformation, energy at rupture, crushing strength, and elastic modulus of the seed samples were investigated. Polynomial functions of the 2nd order with coefficients of correlation ranging between 0.642 ≤ R2 ≤ 0.999 gave the best fit and described the resulting relationships between the studied properties with respect to moisture levels at the two loading axes. Results obtained showed that the seed samples had maximum values of 80.3 N, 110 N and 257.2 J, for bio-yield force, rupture and rupture energy respectively at (10.25% d.b., in the horizontal orientation; whereas minimum values of 31.5 N, 54.9 N and 51.3 J for bio-yield force, rupture force and rupture energy occurred at (32.34% d.b.) respectively in the vertical orientation. Also, the maximum compressive strength of 5.8 N mm-2 in the horizontal orientation of the seed samples at 10.25% d.b. whereas the minimum compressive strength (2.5 N mm-2) occurred in the vertical orientation at 10.25% d.b. moisture content. The sample exhibited less resistive strength to crushing in the horizontal position as the moisture increased; whereas in the vertical position, the cell’s vertical edges provide some form of shield against external pressure which resulted in increased crushing resistance per contact area of the sample.

scholarly journals Thermodynamic and Kinetic Characteristics of Combustion of Discrete Polymethyl Methacrylate Plates with Different Spacings in Concave Building Facades

Polymers ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 167
Author(s):  
Weiguang An ◽  
Lujun Peng ◽  
Minglun Cai ◽  
Kaiyang Hu ◽  
Song Li ◽  
...  
Keyword(s):  
Polymethyl Methacrylate ◽  
Flame Spread ◽  
Structure Factor ◽  
Turning Point ◽  
Fire Risk ◽  
Flame Height ◽  
Hazard Evaluation ◽  
Spread Rate ◽  
Building Facades ◽  
Flame Spread Rate

Polymethyl methacrylate plates are widely applied to buildings, producing significant fire hazards. It lacks a theoretical basis for the fire risk assessment of polymethyl methacrylate in concave building facades. Therefore, experimental methods are used to investigate combustion characteristics of discrete polymethyl methacrylate plates in a concave building facade. Influences of fuel coverage and structure factor are investigated, which is scant in previous works. When structure factor is invariable, average flame height increases first and then decreases as fuel coverage increases, and the turning point is between 0.64 and 0.76. In total, three different patterns of pyrolysis front propagation are first observed for different fuel coverages. Flame spread rate first increases and then decreases as fuel coverage rises, and the turning point is also between 0.64 and 0.76. When fuel coverage is invariable, the flame spread rate first increases and then decreases with increasing structure factor, and the turning point is 1.2. A model for predicting the flame spread rate of discrete polymethyl methacrylate is also developed. The predicted values are consistent with experimental results. Fuel spread rate of discrete polymethyl methacrylate rises as the fuel coverage increases. The above results are beneficial for thermal hazard evaluation and fire safety design of polymethyl methacrylate used in buildings.

scholarly journals Charged current Drell-Yan production at N3LO

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Claude Duhr ◽  
Falko Dulat ◽  
Bernhard Mistlberger
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Production Cross Section ◽  
Production Cross ◽  
Hadron Collider ◽  
Charge Asymmetry ◽  
Charged Current ◽  
Leading Order ◽  
Neutrino Pair ◽  
The Impact

Abstract We present the production cross section for a lepton-neutrino pair at the Large Hadron Collider computed at next-to-next-to-next-to-leading order (N3LO) in QCD perturbation theory. We compute the partonic coefficient functions of a virtual W± boson at this order. We then use these analytic functions to study the progression of the perturbative series in different observables. In particular, we investigate the impact of the newly obtained corrections on the inclusive production cross section of W± bosons, as well as on the ratios of the production cross sections for W+, W− and/or a virtual photon. Finally, we present N3LO predictions for the charge asymmetry at the LHC.

scholarly journals Mechanical Properties of Spruce Wood Extracted from GLT Beams Loaded by Fire

2021 ◽  
Vol 13 (10) ◽  
pp. 5494
Author(s):  
Lucie Kucíková ◽  
Michal Šejnoha ◽  
Tomáš Janda ◽  
Jan Sýkora ◽  
Pavel Padevět ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Cross Section ◽  
Negative Impact ◽  
Tensile Tests ◽  
Thermal Recovery ◽  
Bending Test ◽  
Small Scale ◽  
Spruce Wood ◽  
The Impact

Heating wood to high temperature changes either temporarily or permanently its physical properties. This issue is addressed in the present contribution by examining the effect of high temperature on residual mechanical properties of spruce wood, grounding on the results of full-scale fire tests performed on GLT beams. Given these tests, a computational model was developed to provide through-thickness temperature profiles allowing for the estimation of a charring depth on the one hand and on the other hand assigning a particular temperature to each specimen used subsequently in small-scale tensile tests. The measured Young’s moduli and tensile strengths were accompanied by the results from three-point bending test carried out on two groups of beams exposed to fire of a variable duration and differing in the width of the cross-section, b=100 mm (Group 1) and b=160 mm (Group 2). As expected, increasing the fire duration and reducing the initial beam cross-section reduces the residual bending strength. A negative impact of high temperature on residual strength has also been observed from simple tensile tests, although limited to a very narrow layer adjacent to the charring front not even exceeding a typically adopted value of the zero-strength layer d0=7 mm. On the contrary, the impact on stiffness is relatively mild supporting the thermal recovery property of wood.

The impact cross section of ErF3 centers in ZnS thin film

1988 ◽  
Vol 40-41 ◽  
pp. 786-787
Author(s):  
Baozhu Luo ◽  
Jiaqi Yu ◽  
Guozhu Zhong
Keyword(s):  
Thin Film ◽  
Cross Section ◽  
The Impact

scholarly journals Decomposition Analysis of Void Reactivity Coefficient for Innovative and Modified BWR Assemblies

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Andrius Slavickas ◽  
Raimondas Pabarčius ◽  
Aurimas Tonkūnas ◽  
Gediminas Stankūnas
Keyword(s):  
Cross Section ◽  
Safety Concern ◽  
Functional Module ◽  
Decomposition Analysis ◽  
Fuel Burnup ◽  
Mox Fuel ◽  
High Enrichment ◽  
Reactivity Coefficient ◽  
The Impact ◽  
Irradiation Cycle

The decomposition analysis of void reactivity coefficient for innovative BWR assemblies is presented in this paper. The innovative assemblies were loaded with high enrichment UO2and MOX fuels. Additionally the impact of the moderation enhancement on the void reactivity coefficient through a full fuel burnup discharge interval was investigated for the innovative assembly with MOX fuel. For the numerical analysis the TRITON functional module of SCALE code with ENDF/B-VI cross section library was applied. The obtained results indicate the influence of the most important isotopes to the void reactivity behaviour over a fuel burnup interval of 70 GWd/t for both UO2and MOX fuels. From the neutronic safety concern positive void reactivity coefficient values are observed for MOX fuel at the beginning of the fuel irradiation cycle. For extra-moderated assembly designs, implementing 8 and 12 water holes, the neutron spectrum softening is achieved and consequently the lower void reactivity values. Variations in void reactivity coefficient values are explained by fulfilled decomposition analysis based on neutrons absorption reactions for separate isotopes.

Effect of Sample Width on Downward Flame Spread over Typical Energy Conservation Material at a High Elevation Area

2014 ◽  
Vol 664 ◽  
pp. 199-203 ◽  
Author(s):  
Wei Guang An ◽  
Lin Jiang ◽  
Jin Hua Sun ◽  
K.M. Liew
Keyword(s):  
Mass Loss ◽  
Flame Spread ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
High Elevation ◽  
Flame Height ◽  
Spread Rate ◽  
Flame Spread Rate ◽  
Sample Width ◽  
Downward Flame Spread

An experimental study on downward flame spread over extruded polystyrene (XPS) foam at a high elevation is presented. The flame shape, flame height, mass loss rate and flame spread rate were measured. The influences of width and high altitude were investigated. The flame fronts are approximately horizontal. Both the intensity of flame pulsation and the average flame height increase with the rise of sample width. The flame spread rate first drops and then rises with an increase in width. The average flame height, mass loss rate and flame spread rate at the higher elevation is smaller than that at a low elevation, which demonstrates that the XPS fire risk at the higher elevation area is lower. The experimental results agree well with the theoretical analysis. This work is vital to the fire safety design of building energy conservation system.

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