Management of coal dust explosions in United States\u27 coal mines using bag type passive explosion barriers

The most significant and powerful hazard that exists in an underground coal mine is a coal dust explosion. A coal dust explosion has the potential to propagate throughout a mine resulting in massive damage to the mine and equipment, as well as tragic loss of life. An assessment of current global regulations and practices uncovered four main control methods utilized to prevent coal dust explosions in coal mines world-wide. The United States is one of the few countries that does not regulate or employ all four of these safety practices. Additionally, a review of past research into coal dust explosions and their prevention and mitigation uncovered scientific need for the use of explosion barriers as an additional line of defense against deadly coal dust explosions since the early 1900s. This research project was developed to investigate the possibility of implementing the fourth prevention strategy in the United States, the use of explosion activated barriers as the last line of defense against the propagation of a coal dust explosion. The goal of this thesis was twofold. The first component was to demonstrate that explosion impulse, as opposed to explosion pressure, is the primary factor in the complete operation of the bag barrier system; meaning the rupturing of the bag, the release of the contained stone dust, and the dispersal of the released dust. The second component was to demonstrate that the bag barrier system can be effectively implemented into American underground coal mines. This goal was achieved through the careful examination and analysis of historical mine explosions and mine explosion prevention research, explosive testing of the bag barrier system, and trial bag barrier installations in operating coal mines --Abstract, page iii

Modeling of Deformation and Texture Development of Copper in a 120° ECAE Die

A flow line function is proposed to describe the material deformation in ECAE for a 120\degree die. This new analytical approach is incorporated into a viscoplastic self-consistent polycrystal code to simulate the texture evolution in Route A of copper and compared to experimental textures as well as to those corresponding to simple shear

Comprehensive thermal analysis of a high stability Cu-Zr-Al bulk metallic glass subjected to high-pressure torsion

Bulk metallic glass of Cu38Zr54Al8 nominal composition was synthesized by copper mold casting into 6 mm diameter rods. Disks of the as-cast glass were subjected to severe plastic deformation by high-pressure torsion for different number of revolutions. The microstructure and the thermal behavior of the as-cast, isothermally annealed and deformed glass have been investigated by X-ray diffraction and differential scanning calorimetry, respectively. Continuous heating experiments revealed a two-stage devitrification event with excellent glass forming parameters, such as glass transition (T-g = 671 K), supercooled liquid region ( increment T-x = 80 K), reduced glass transition (T-r = 0.57) and gamma parameter (gamma = 0.41). Power law crystal growth during diffusion-controlled homogeneous nucleation was observed for isothermal annealings. Glassy state was preserved almost in the entire sample volume of the as-cast alloy during the high-pressure torsion process, corresponding to the extreme stability of the Cu38Zr54Al8 alloy against deformation-induced devitrification. This is in accordance with the transition of the reversible specific heat from the glassy to supercooled liquid state measured by modulated calorimetry. It was also concluded that glassy structure is more ordered in the severely deformed state

Explosive Dust Test Vessel Comparison using Pulverized Pittsburgh Coal

Explosions of coal dust are a major safety concern within the coal mining industry. The explosion and subsequent fires caused by coal dust can result in significant property damage, loss of life in underground coal mines and damage to coal processing facilities. The United States Bureau of Mines conducted research on coal dust explosions until 1996 when it was dissolved. In the following years, the American Society for Testing and Materials (ASTM) developed a test standard, ASTM E1226, to provide a standard test method characterizing the “explosibility” of particulate solids of combustible materials suspended in air. The research presented herein investigates the explosive characteristic of Pulverized Pittsburgh Coal dust using the ASTM E1226-12 test standard. The explosibility characteristics include: maximum explosion pressure, (Pmax); maximum rate of pressure rise, (dP/dt)max; and explosibility index, (Kst). Nine Pulverized Pittsburgh Coal dust concentrations, ranging from 30 to 1,500 g/m3 , were tested in a 20-Liter Siwek Sphere. The newly recorded dust explosibility characteristics are then compared to explosibility characteristics published by the Bureau of Mines in their 20 liter vessel and procedure predating ASTM E1126-12. The information presented in this paper will allow for structures and devices to be built to protect people from the effects of coal dust explosions

Quantum Sensing for Detection of Zinc-Triggered Free Radicals in Endothelial Cells

Oxidative stress originating from the overproduction of free radicals poses a major threat to cell fate, therefore it is of great importance to address the formation of free radicals in cells subjected to various pathological stimuli. Here we investigate the free radical response of endothelial cells to biodegradable zinc. In addition to the standard free radical assays, relaxometry was used for determining the production of free radicals in cells exposed to non-physiological concentrations of zinc ions. The cellular morphology, intracellular zinc accumulation, as well as the levels of reactive oxygen/nitrogen species, are determined using standard fluorescent methods. For endothelial cells subjected to 50% zinc extracts, deviations from the normal cell shape and cell agglomeration tendency are observed. The culture medium containing the highest amount of zinc ions caused nuclei fragmentation, blebbing, and cell shrinkage, indicating cell death. A potential explanation for the observed phenomena is an overproduction of free radicals. In the case of 1% and 10% zinc extracts, the formation of free radicals is clearly confirmed by relaxometry, while the results obtained by using fluorescent techniques are unambiguous. It is revealed that high concentrations of zinc ions released from biodegradable samples induce a deleterious effect on endothelial cells.</p

Evaluating worker-centered smart interventions on the shop floor

This paper presents the evaluation strategy and the first results we obtained when we used the FACTS4WORKERS evaluation framework. The purpose of the framework is to prove whether the project interventions achieve the expected results, which are: improving workers’ job satisfaction, increasing innovation and problem solving skills as well as enhancing productivity. Because of the diversity of the industrial partners and of the workplaces where the interventions are going to be implemented, the different languages, legal and cultural environments the framework was conceived as general as possible to be adapted to any particular case. We present here one example for using the framework, the first results of these measurements and the feedback the evaluation provides both for supporting the decisions about the interventions and about the framework itself

Characterization of defect structures in nanocrystalline materials by X-ray line profile analysis

X-ray line profile analysis is a powerful alternative tool for determining dislocation densities, dislocation type, crystallite and subgrain size and size-distributions, and planar defects, especially the frequency of twin boundaries and stacking faults. The method is especially useful in the case of submicron grain size or nanocrystalline materials, where X-ray line broadening is a well pronounced effect, and the observation of defects with very large density is often not easy by transmission electron microscopy. The fundamentals of X-ray line broadening are summarized in terms of the different qualitative breadth methods, and the more sophisticated and more quantitative whole pattern fitting procedures. The efficiency and practical use of X-ray line profile analysis is shown by discussing its applications to metallic, ceramic, diamond-like and polymer nanomaterials