Blast Wave Mitigation from the Straight Tube by Using Water Part I - Small Scale Experiment

2018 ◽  
Vol 910 ◽  
pp. 149-154 ◽  
Author(s):  
Tomotaka Homae ◽  
Yuta Sugiyama ◽  
Kunihiko Wakabayashi ◽  
Tomoharu Matsumura ◽  
Yoshio Nakayama
Keyword(s):  
Blast Wave ◽  
Cross Section ◽  
Small Scale ◽  
Straight Tube ◽  
Vertical Shaft ◽  
Blast Pressure ◽  
Storage Chamber ◽  
Scale Experiment

A subsurface magazine has an explosive storage chamber, a horizontal passageway, and a vertical shaft for vent. It was proposed and legislated in Japan. The authors found that small amount of water on the floor of its storage chamber mitigated the blast pressure remarkably. The mechanism of the mitigation has been studied, however, it is not still well understood. In this study, the explosion in a transparent, square cross section, and straight tube was carried out to examine the mechanism of blast-wave mitigation by water. The arrangement and amount of water in the tube were varied for five ways. The dependence of mitigation effect on the arrangement and amount of water was evaluated by measuring the blast pressures in the tube and outside the tube. The results of this study concluded that the mitigation of blast wave by water is mainly due to the interaction between the explosion and the water very near the explosion point. On the contrary, the water at other part of the tube was found to strengthen the blast pressure.

scholarly journals Blast mitigation by water in a bag on a tunnel floor

2018 ◽  
Vol 192 ◽  
pp. 02039
Author(s):  
Tomotaka Homae ◽  
Yuta Sugiyama ◽  
Kei Shimura ◽  
Kunihiko Wakabayashi ◽  
Tomoharu Matsumura ◽  
...  
Keyword(s):  
Blast Wave ◽  
Cross Section ◽  
Glass Beads ◽  
Lead Azide ◽  
Straight Tube ◽  
Ratio Analysis ◽  
Cross Section Area ◽  
Tunnel Floor ◽  
Section Area ◽  
End Wall

Mitigation of blast wave, caused by explosion of explosives, from a straight tube using water in a bag (water bag) was evaluated. The length of the tube was 330 mm and the cross-section area was 30 x 30 mm2. One end of the tube was closed. The water bag was placed on the floor or closed end wall of the tube near the explosive. The thickness of water was 3 mm. A specially designed small detonator, which contains lead azide of 100 mg, was ignited near the closed end wall of the tube. The blast pressure outside the tube was measured and examined. The blast wave was remarkably mitigated by the water bag. Equivalent ratio analysis revealed that the glass beads absorbed 33%-45% of explosion energy.

Study of Destruction Mechanism of Floating-Roof Oiltank under Combustible Gaseous Explosion in a Small Scale Experiment

2011 ◽  
Vol 137 ◽  
pp. 65-71 ◽  
Author(s):  
Sheng Zhuo Lu ◽  
Wei Wang
Keyword(s):  
Blast Wave ◽  
Gaseous Mixture ◽  
Blast Loading ◽  
Damage Mechanism ◽  
Small Scale ◽  
Wave Loading ◽  
Destruction Mechanism ◽  
Order Of Magnitude ◽  
Scale Experiment ◽  
Safety Strategy

The number of accidental explosions has recently increased, and more researchers focus attention on damage mechanism and safety strategy of structures. The aim of this paper is to assess the mechanical effects of an accidental explosion of a gaseous mixture and the floating-roof oiltank dynamic response subjected to external blast wave loading. For this purpose, the research is based upon an experimental study at laboratory scale. It shows that the pressure induced by blast wave on the structures rose immediately and altered dynamically. The top of the oiltank surface towards blast loading is in a tensile state with the maximum strain. It is the vulnerable place to resist the gaseous blast loading. Meanwhile, the inner liquid could induce the compression wave, and collided with the structures of the oiltank intensively. Compared with the blast wave pressure on the front, the back wall pressure transmitted by liquid collision had the same order of magnitude and longer actuation duration than the former.

Generation and analysis of biogas from kitchen waste at a small scale

2020 ◽  
pp. 140-148
Author(s):  
Md. Kumail Naqvi ◽  
Mrinal Anthwal ◽  
Ravindra Kumar
Keyword(s):  
Food Waste ◽  
Total Solid ◽  
Small Scale ◽  
Cow Dung ◽  
Retention Period ◽  
Household Level ◽  
Replacement Model ◽  
The Everyday ◽  
Scale Experiment ◽  
Small Period

Biogas is the product of anaerobic vitiation of biodegradable matter. This paper focuses on the need of alternative and green sources of energy at a household level and how biogas produced from the everyday organic waste has the potential and possibility to replace LPG cylinders at houses, shops etc. and empower us to step towards an eco-friendly future. The purpose this small-scale experiment has been to find the perfect input matter that is easy to acquire and which produces the maximum amount of gas from minimum input and within small period of waste retention. Four different types of input waste material containing different quantities of cow dung and kitchen food waste were studied through individual experimental setups. Waste was mixed and kept at room temperature and the pH and total solid concentration of the samples were recorded on regular intervals. From the experiment it was found that the optimum yield of biogas at a small scale, based on the parameters such as retention period, pH and total solid con-centration can be obtained by the use of food waste form households and kitchens. The exact composition has been discussed in this paper. The energy generated by the small-scale generator has also been compared to that of an LPG cylinder and an LPG replacement model has also been presented.

Small Scale Vertical Shaft Lime Kiln

1999 ◽  
Author(s):  
Kelvin Mason ◽  
Neville Hill ◽  
Otto Ruskulis ◽  
Alex Mugova ◽  
Peter Tawodzera ◽  
...  
Keyword(s):  
Small Scale ◽  
Vertical Shaft ◽  
Lime Kiln

Evaluating Visualisations in Voting Advice Applications

2020 ◽  
Vol 11 (1) ◽  
pp. 1-21
Author(s):  
Bastiaan Bruinsma
Keyword(s):  
Small Scale ◽  
First Results ◽  
Scale Experiment ◽  
Voting Advice Applications

AbstractWhile the design of voting advice applications (VAAs) is witnessing an increasing amount of attention, one aspect has until now been overlooked: its visualisations. This is remarkable, as it are those visualisations that communicate to the user the advice of the VAA. Therefore, this article aims to provide a first look at which visualisations VAAs adopt, why they adopt them, and how users comprehend them. For this, I will look at how design choices, specifically those on matching, influence the type of visualisation VAAs not only do but also have to, use. Second, I will report the results of a small-scale experiment that looked if all users comprehend similar visualisations in the same way. Here, I find that this is often not the case and that the interpretations of the users often differ. These first results suggest that VAA visualisations are wrongly underappreciated and demand closer attention of VAA designers.

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.

Non-Linear Stress Analysis of Complex Umbilical Cross-Sections

2002 ◽  
Author(s):  
Svein Sævik ◽  
Knut I. Ekeberg
Keyword(s):  
Cross Section ◽  
Axial Force ◽  
Plastic Material ◽  
Axial Strain ◽  
Development Program ◽  
Full Scale ◽  
Small Scale ◽  
Applied Theory ◽  
Element Formulation ◽  
Material Models

Nexans Norway is, together with Marintek, currently developing a software for detailed analysis of complex umbilical cross-section designs. The software development project combines numerical methods with small-scale testing of involved materials, as well as full-scale testing of a wide variety of umbilical designs, essential for calibration and verification purposes. Each umbilical design is modelled and comparisons are made with respect to global behaviour in terms of: • Axial strain versus axial force; • Axial strain versus torsion; • Torsion versus torsion moment for various axial force levels; • Moment versus curvature for different tension levels. The applied theory is based on curved beam and curved axisymmetric thin shell theories. The problem is formulated in terms of finite elements applying the Principle of Virtual Displacements. Each body of the cross-section interacts with the other bodies by contact elements which are formulated by a penalty formulation. The contact elements operate in the local surface coordinate system and include eccentricity, surface stiffness and friction effects. The software is designed to include the following functionality: • Arbitrary geometry modelling including helical elements wound into arbitrary order; • The helical elements may include both tubes and filled bodies; • Elastic, hyper-elastic, and elastic-plastic material models; • Initial strain; • Contact elements, including friction; • Tension, torsion, internal pressure, external pressure, bending and external contact loading (caterpillars, tensioners, etc.). The paper focuses on the motivation behind the development program including a description of the different activities. The theory is described in terms of kinematics, material models and finite element formulation. A test example is further presented comparing predicted behaviour with respect to full-scale test results.

scholarly journals Seed production of lemon balm and the quality of its seeds in the middle of the Volga region

2019 ◽  
pp. 34-36
Author(s):  
Ilya Alexandrovich Khapugin
Keyword(s):  
Seed Production ◽  
Weather Conditions ◽  
Mineral Fertilizers ◽  
Small Scale ◽  
Melissa Officinalis ◽  
Seed Productivity ◽  
Lemon Balm ◽  
Maximum Productivity ◽  
Scale Experiment

The influence of mineral fertilizers on seed productivity and quality of obtained seeds of lemon balm (Melissa officinalis L.) was studied in the field small-scale experiment under conditions of unstable moistening of the Mordovia Republic. As a result, it was found that seed productivity varied depending on weather conditions and the types of fertilizers introduced. It was shown that the maximum productivity of Melissa officinalis plants was on the variant with the use of phosphorus-potassium fertilizers at a dose of P60K90 (71.2±78.5 g/m2 in 2017 and 48.8±4.3 g/m2 in 2018), while it exceeded the control variant by 74-91 %. The total germination of seeds of Melissa officinalis practically did not change over the years, and was in the range of 37-39 %. Separation of seeds according to the degree of aging allowed to increase germination 11.4-13.3 %.  

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