The radiative heating of small particles in a flammable atmosphere by laser light may lead to ignition and explosion. The mechanisms of ignition and detonation of quiescent methane/air mixtures caused by a radiatively heated inert particle involves a set of chemical reactions among the gas-phase species. A system of ordinary differential equations that comprises the net reaction rates of the species, which are initially present in the system, and the products of their reversible reactions is solved for the entire inflammability range of methane with air under isothermal conditions and within the temperature region of interest (800-1000 K). Two criteria tests are carried out to identify the chain initiating reaction. The first criterion tests the contribution a given reaction made to the main chain branching while the second criterion tests its contribution to the total heat release. It is found that the reaction, O₂ + CH₄→HO₂ + CH₃ satisfies the criteria at all grid points of the calculation. A simplified kinetic scheme is adopted and a system of differential equations, representing the net reaction rates of all species included in the scheme is solved. The data are used in the explosion-delay time calculations.

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Gamma-rays from relatively distant supernova may cause an increase of the NO inventory in the atmosphere, which in turn may lead to a reduction of O₃ and a world-wide change in climate. Such an effect may be detectable in the temperature data obtained by the method of isotopic tree thermometers.

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Recently, many methods for simulating natural phenomena on the basis of fluid simulation have been proposed. A method for simulating was also proposed, but the shapes of the simulated depend on many simulation parameters. Therefore, creating the desired shape for an explosion as specified by the user is difficult. In this paper, we propose a method for controlling explosion simulations in order to form the desired shapes. Our method optimizes the initial intensity distribution of an explosion and controls the simulation to minimize the difference between the target shape and the shape of the simulated explosion. We use a predictive approach to control the explosion simulation accurately. Using the proposed method, animations of controlled into specified shapes can be generated.

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In accidental gas , blast waves propagate toward the surroundings after the bursting of the vessel or building, in which gas occur. The strength of the blast wave depends not only on explosion behavior, but also bursting strength. This phenomenon has not been thoroughly examined. In the present experimental study, blast waves from hydrogen–air deflagrations in plastic vessels with various strengths were measured and flame behavior was recorded by digital high-speed video cameras. The measured peak overpressure and impulse of blast waves were compared with those of blast waves from unconfined gas . Furthermore, these were compared with the calculated values of blast waves from bursting vessels without combustion reaction. Peak overpressure appeared when the vessels burst. The peak overpressure and impulse depended on the strengths of vessels, and were larger than those from unconfined gas and bursting vessels without combustion reaction.

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Phyllosilicates were present in the volcanic ashes from several 1982-1983 eruptions of Kusatsu-Shirane Volcano . Pyrophyllite, kaolin and smectite were present as major clay minerals. Hydrothermally altered rocks collected from the western flank showed that, the basement rocks of this volcano were altered to form silica minerals, alunite and various clay minerals such as pyrophyllite, kaolin and smectite. The presence of pyrophyllite in the volcanic ashes indicates that the probably have taken at a depth corresponding to the basement rocks. On the other hand, samples of air-fall tephra from 1897 and 1925 eruptions contained little or no pyrophyllite suggesting that these likely occurred in the volcanic rocks of Kusatsu-Shirane Volcano. Based on the distribution and amounts of clay minerals in the volcanic ejectas, the depth of during repeated eruptions may be inferred.

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Experiments on high speed bulging are presented under various die diameters and sheet thicknesses, and the results are compared with the analytical results of the first report. The final deflections of the sheets can be estimated by the impulse of the pressure pulse measured by Hopkinson pressure bar. The process of the bulging measured by a high speed camera differs from the analytical one; the differences between them are discussed by the theory on wave propagation and reflection. Supplementary experiments on two dimensional bulging of rectangular sheets are made and the effect of the cavitation beneath the sheet on the bulging is examined.

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This paper addresses ontologies of intentional and unintentional processes. Specifically, a methodology for developing processes ontologies is described. Typically, domain ontologies are developed in an ad-hoc fashion, without the reasons and justifications of the class structure. To resolve this issue, we propose a methodology based on Formal Concept Analysis (FCA) as a way to assist the development of a domain ontology. FCA is an analysis technique for knowledge processing based on applied lattice and order theory. The methodology is illustrated with the development of an explosion ontology.

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Usu volcano has erupted seven times since 1663. The last three eruptions occurred during the 20th century (1910, 1943 and 1977) and were observed by standard instruments. Although the three eruptions displayed different surface manifestations, they were, similarly, volcanisms derived from dacitic magmas.
n this paper, the three eruptions are compared mainly from the viewpoint of magma movements before and during the eruptions on the basis of geophysical data, i.e. explosive, seismic and thermal activities, ground deformations, and level changes in aquifers. Post-eruption activities are also comparatively reviewed.
Some phenomena related to the three eruptions are reinterpreted: for the 1910 eruption, the cryptodome model of the upheaval is rejected, and the tectonic structure of the craterlet line is proposed; for the 1943 and the 1977 eruptions, the ratios between seismic energy release and deformation are discussed; for the 1977 eruption, a tilt model of the sector deformation is proposed and relationships between anomalous changes in the aquifer level and ground upheavals are discussed.
Magnitudes of the three eruptions are estimated. Tentatively, the 1943 and 1977 eruptions are roughly of the same order of magnitude and the 1910 eruption is one order of magnitude smaller.

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To reveal the flame propagation characteristics of the deposited coal dust explosion driven by airflow carrying the coal dust, the horizontal glass tube explosion apparatus is used for experimental testing. The greater the degree of coal dust metamorphism, the smaller the propagation distance and duration of the explosion flame. The propagation distance and duration of the explosion flame first increase, then decrease as the weight of the deposited coal dust increases due to the limited space in the glass tube, local turbulence disturbance, and insufficient oxygen concentration. As the particle size of the deposited coal dust increases, the flame duration of lignite and long-flame coal decrease, but the flame duration of non-stick coal and gas coal increase. Inert rock dust effectively hinders the coal dust explosion, confirming that spreading inert rock dust around the tunnels effectively reduces the explosion of suspended and deposited coal dust.

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Laboratory investigations of noble gas trapping in amorphous water ice have been used to predict the noble gas composition of comets and infer on the origin of volatile elements within planetary bodies. However, the recent measurement of the noble gas composition of ice sublimating from comet 67P/Churyumov-Gerasimenko by the Rosetta mission calls for novel experiments regarding the mechanisms of noble gas trapping and evolution in cometary ice analogues. Here, we investigated the ionization dynamics of Xe atoms interacting with water ice using the recently developed Resonant Two-Step Laser Ablation Mass Spectrometry (2S-LAI-MS). Xenon-water mixed ice was ablated with an infrared beam set on the maximum absorption wavelength for water (λ = 2948 nm) at which xenon atoms are kept neutral. Subsequent multiple ionization of xenon and oxygen resulted in periodic Coulomb

of Xeⁿ⁺ components (n ∈ [1;6]) and ionized water degradation products (OH⁺, H⁺, O⁺, O²⁺, O³⁺). Such could only be detected when Xe and water were mixed together in ice, and not when separated in two overlaid layers. This paper discusses the potential mechanisms accounting for the generation of Coulomb in these experiments and its relevance to cometary ice at closer distances to perihelion. We conclude that multiple ionization of xenon and oxygen in our experiment may be due to electron impact processes resembling cometary electron and ion bombardment, whereby energetic particles of hundreds of eV to a few keV are accelerated towards the comet’s nucleus. Electron and ion bombardment could induce significant chemical modifications to, and potentially outgassing from, the cometary surface.

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At Sakurajima volcano, strombolian eruptions forerun vulcanian , and volcanian are often followed by continuous ash eruptions. Change in the mode of its eruptive activity is drastic and release of volatiles from magma corresponding to its eruptive activity is examined by determination of fluorine and chlorine in volcanic ash. The F contents of all the ash samples are markedly higher than the arithmetic mean value of Japanese volcanic rocks (ca. 300 μg/g). Further, the water-soluble Cl contents of almost all the ash samples are also extremely higher than those of Japanese volcanic rocks (less than 50 μg/g). This is attributed to fixation of F and Cl in hot gas onto the volcanic ash particles in the crater and/or eruption plumes. The differences in those contents among the “strombolian eruption”-, “vulcanian explosion”- and “continuous ash eruption” groups are significant, which implies that hot gas rich in F and Cl are issued during strombolian eruptions, while those halogens are less concentrated in hot gas after strombolian eruptions. The water-insoluble Cl content of the“strombolian eruption” group is significantly higher than those of the other groups. This result implies that Cl and the other volatiles are intensely released from magma during the doming period before vulcanian eruptions. Yet, it is inferred that continuous ash eruption is the final phase of vulcanian one.

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Vapor are a major safety concern in the severe accident management of nuclear power plants. Here, we investigated the self-triggering mechanism and the occurrence conditions for spontaneous vapor analytically. A spontaneous vapor explosion is assumed to occur when a vapor film between a hot and a cold liquid naturally collapse. We modeled a simple system consisting of a hot liquid droplet in a pool of cold liquid. The stability of perturbed oscillations in a vapor film was then investigated analytically. The model included the effect of thermal radiation on this stability for high temperature melts. The analytical results show that the stability of a vapor film is significantly affected by the emissivity of thermal radiation and by the heat transfer coefficient for the condensation of the vapor to the subcooled cold liquid. Furthermore, as the hot liquid temperature increases, thermal radiation causes the temperature region in which the vapor film is stable to increase in size. Comparisons were then made between our analytical results and those from large-scale experiments in which vapor were studied for water and molten core materials in lightwater reactors. They showed that our model explains the tendency of the occurrence of vapor in those experiments.

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In this paper, a case study has been made on the characteristics of earthquakes and , mainly through the polarization method, estimating the epicentral azimuths and incident angles in the case of shallow- and deep-focus earthquakes as well as based on three-component signal-to-noise ratios. We have found that it is possible to determine the epicenter and incident angle of an earthquake or an explosion by three-component single-station polarization analysis, especially using body waves like Pn, and in some cases, stable and accurate results are obtained. We made a theoretical discussion on the polarization properties of shear waves, and found that multievents which take place occasionally within can be discerned by azimuth and motion pattern monitoring.

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Propagation paths are calculated for weak hydromagnetic shock waves (fast mode) from a point source lower than 3000km above the sea level. It is shown that the shock waves of this type have a tendency to propagate easily in the direction of the geomagnetic meridian. The results are compared with the observed geomagnetic disturbances due to the small scale high altitude nuclear explosion (Argus III). A qualitative agreement is obtained between the theoretical and the observational results.

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