Explosive force production during isometric squats correlates with athletic performance in rugby union players.

PubMed

Tillin, Neale Anthony; Pain, Matthew Thomas Gerard; Folland, Jonathan

2013-01-01

This study investigated the association between explosive force production during isometric squats and athletic performance (sprint time and countermovement jump height). Sprint time (5 and 20 m) and jump height were recorded in 18 male elite-standard varsity rugby union players. Participants also completed a series of maximal- and explosive-isometric squats to measure maximal force and explosive force at 50-ms intervals up to 250 ms from force onset. Sprint performance was related to early phase (≤100 ms) explosive force normalised to maximal force (5 m, r = -0.63, P = 0.005; and 20 m, r = -0.54, P = 0.020), but jump height was related to later phase (>100 ms) absolute explosive force (0.51 < r < 0.61; 0.006 < P < 0.035). When participants were separated for 5-m sprint time (< or ≥ 1s), the faster group had greater normalised explosive force in the first 150 ms of explosive-isometric squats (33-67%; 0.001 < P < 0.017). The results suggest that explosive force production during isometric squats was associated with athletic performance. Specifically, sprint performance was most strongly related to the proportion of maximal force achieved in the initial phase of explosive-isometric squats, whilst jump height was most strongly related to absolute force in the later phase of the explosive-isometric squats.

Simulating the Thermal Response of High Explosives on Time Scales of Days to Microseconds

NASA Astrophysics Data System (ADS)

Yoh, Jack J.; McClelland, Matthew A.

2004-07-01

We present an overview of computational techniques for simulating the thermal cookoff of high explosives using a multi-physics hydrodynamics code, ALE3D. Recent improvements to the code have aided our computational capability in modeling the response of energetic materials systems exposed to extreme thermal environments, such as fires. We consider an idealized model process for a confined explosive involving the transition from slow heating to rapid deflagration in which the time scale changes from days to hundreds of microseconds. The heating stage involves thermal expansion and decomposition according to an Arrhenius kinetics model while a pressure-dependent burn model is employed during the explosive phase. We describe and demonstrate the numerical strategies employed to make the transition from slow to fast dynamics.

Micro-explosion of compound drops

NASA Astrophysics Data System (ADS)

Chen, Chun-Kuei; Lin, Ta-Hui

2014-08-01

Introducing water into spray combustion systems, by either water-in-oil emulsification or supplementary water injection, is one of the major techniques for combustion improvement and NOx reduction. Plentiful researches are available on combustion of water-in-oil emulsion fuel drops. The emulsified liquid is a heterogeneous mixture of immiscible liquids. One component forms the continuous phase and the other component forms the discrete phase. The discrete phase consists of globules of the one fluid that are suspended in the continuous phase fluid. Water-in-oil emulsions are commonly considered for combustion applications because emulsions can result in micro-explosion, thereby reducing the average drop diameter to enhance liquid vaporization, and suppressing the formation of soot and NOx. However, the water addition generally does not exceed about 20% for smooth engine operations[!, 21. The combustion characteristics and micro-explosion of emulsion drop were studied by many researchers. The micro-explosion of water in fuel emulsion drops was caused by very fast growth of superheated water vapor bubbles, its superheat limits must be lower than the boiling point temperature of the fuel. These bubbles were primarily governed by the pressure difference between the superheated vapor and the liquid, and by the inertia imparted to the liquid by the motion of the bubble surface[3 6 In this study, we used a coaxial nozzle to generation the multi-component drop. The different type of water-in-oil fuel drops called the compound drops. Unlike an emulsion drop, a compound drop consists of a water core and a fuel shell, which can originate from the phase separation of emulsion[7, 81 or a water drop colliding with a fuel drop[9, 101 Burning and micro-explosion of compound drops have been found to be distinct from those of emulsion drops[9-111 Wang et al.[9 , 101 studied the combustion characteristics of collision merged alkane-water drops. The merged drops appeared in adhesive and inserted manners. The drop ignition delay time increased with increasing water content. The average burning rate of alkane-water drops decreased with increasing water content. In the burning process, hexadecane-water drops exhibited flash vaporization or flame extinction. Heterogeneous explosion was occasionally observed in drops with trapped air bubbles. The air bubbles were assumed to be the nucleation points of the heterogeneous explosions. Chen and Lin[11 studied the characteristics of water-in-dodecane compound drop with different water content, diameter of drop and environmental oxygen concentration. The vaporization rate increased with increasing environmental oxygen concentration. The compound drops micro-exploded during the burning process in a random way. The number of micro-explosions was majorly influenced by drop diameter, followed by environmental oxygen concentration. Water content had a weaker effect on micro-explosion. As available literature and research results of compound drop burning are scarce, their combustion and micro-explosion behaviors are still poorly understood. In this regard, we changed the drop nature as compound drops to study their combustion characteristics and micro-explosion phenomena.

Thermal explosion violence of HMX-based explosives -- effect of composition, confinement and phase transition using the scaled thermal explosion experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maienschein, J L; Wardell, J F; Reaugh, J E

We developed the Scaled Thermal Explosion Experiment (STEX) to provide a database of reaction violence from thermal explosion of explosives of interest. A cylinder of explosive, 1, 2 or 4 inches in diameter, is confined in a steel cylinder with heavy end caps, and heated under controlled conditions until it explodes. Reaction violence is quantified by micropower radar measurement of the cylinder wall velocity, and by strain gauge data at reaction onset. Here we describe the test concept and design, show that the conditions are well understood, and present initial data with HMX-based explosives. The HMX results show that anmore » explosive with high binder content yields less-violent reactions that an explosive with low binder content, and that the HMX phase at the time of explosion plays a key role in reaction violence.« less

Two-Phase Model of Combustion in Explosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhl, A L; Khasainov, B; Bell, J

2006-06-19

A two-phase model for Aluminum particle combustion in explosions is proposed. It combines the gas-dynamic conservation laws for the gas phase with the continuum mechanics laws of multi-phase media, as formulated by Nigmatulin. Inter-phase mass, momentum and energy exchange are prescribed by the Khasainov model. Combustion is specified as material transformations in the Le Chatelier diagram which depicts the locus of thermodynamic states in the internal energy-temperature plane according to Kuhl. Numerical simulations are used to show the evolution of two-phase combustion fields generated by the explosive dissemination of a powdered Al fuel.

Toward Improved Fidelity of Thermal Explosion Simulations

NASA Astrophysics Data System (ADS)

Nichols, Albert; Becker, Richard; Burnham, Alan; Howard, W. Michael; Knap, Jarek; Wemhoff, Aaron

2009-06-01

We present results of an improved thermal/chemical/mechanical model of HMX based explosives like LX04 and LX10 for thermal cook-off. The original HMX model and analysis scheme were developed by Yoh et.al. for use in the ALE3D modeling framework. The improvements were concentrated in four areas. First, we added porosity to the chemical material model framework in ALE3D used to model HMX explosive formulations to handle the roughly 2% porosity in solid explosives. Second, we improved the HMX reaction network, which included the addition of a reactive phase change model base on work by Henson et.al. Third, we added early decomposition gas species to the CHEETAH material database to improve equations of state for gaseous intermediates and products. Finally, we improved the implicit mechanics module in ALE3D to more naturally handle the long time scales associated with thermal cookoff. The application of the resulting framework to the analysis of the Scaled Thermal Explosion (STEX) experiments will be discussed.

Surface-enhanced Raman scattering detection of ammonium nitrate samples fabricated using drop-on-demand inkjet technology.

PubMed

Farrell, Mikella E; Holthoff, Ellen L; Pellegrino, Paul M

2014-01-01

The United States Army and the first responder community are increasingly focusing efforts on energetic materials detection and identification. Main hazards encountered in theater include homemade explosives and improvised explosive devices, in part fabricated from simple components like ammonium nitrate (AN). In order to accurately detect and identify these unknowns (energetic or benign), fielded detection systems must be accurately trained using well-understood universal testing substrates. These training substrates must contain target species at known concentrations and recognized polymorphic phases. Ammonium nitrate is an explosive precursor material that demonstrates several different polymorphic phases dependent upon how the material is deposited onto testing substrates. In this paper, known concentrations of AN were uniformly deposited onto commercially available surface-enhanced Raman scattering (SERS) substrates using a drop-on-demand inkjet printing system. The phase changes observed after the deposition of AN under several solvent conditions are investigated. Characteristics of the collected SERS spectra of AN are discussed, and it is demonstrated that an understanding of the exact nature of the AN samples deposited will result in an increased ability to accurately and reliably "train" hazard detection systems.

Development of a portable non-contact optical diagnostic system for the detection of δ-HMX

NASA Astrophysics Data System (ADS)

Dale, Andrew J.; Wright, Mark W.; Hughes, Christopher T.; Bowden, Mike D.

2007-09-01

If a HMX-based explosive is subjected to an insult then there is a potential for the insulted β-HMX to undergo a phase change to the more sensitive δ form. AWE has an ongoing programme to develop a science-based model of the response of HMX-based explosives to potential insults. As part of this programme there is a need to identify whether δ-HMX has been formed, as this would subsequently affect the intrinsic safety properties of the formulation. δ-HMX, unlike the more stable β form, exhibits unusual optical properties for an explosive, as it acts as a frequency-doubling material. When illuminated by a high-energy laser pulse areas of the explosive charge that contain δ-HMX emit frequency doubled light. This non-linear optical phenomenon allows for a non-invasive diagnostic to be developed to study creation of the more sensitive δ phase within HMX based formulations. AWE has developed a portable diagnostic system based on this concept to investigate the behaviour of HMX-based explosives after low-speed impacts. The results of the commissioning trials are presented; using both an inert simulant, KDP, to align and prove the system and HMX samples from low-speed impact experiments. The results of these experiments are compared to initial calculations using the Hydrocode EDEN.

Nonequilibrium phase coexistence and criticality near the second explosion limit of hydrogen combustion

NASA Astrophysics Data System (ADS)

Newcomb, Lucas B.; Alaghemandi, Mohammad; Green, Jason R.

2017-07-01

While hydrogen is a promising source of clean energy, the safety and optimization of hydrogen technologies rely on controlling ignition through explosion limits: pressure-temperature boundaries separating explosive behavior from comparatively slow burning. Here, we show that the emergent nonequilibrium chemistry of combustible mixtures can exhibit the quantitative features of a phase transition. With stochastic simulations of the chemical kinetics for a model mechanism of hydrogen combustion, we show that the boundaries marking explosive domains of kinetic behavior are nonequilibrium critical points. Near the pressure of the second explosion limit, these critical points terminate the transient coexistence of dynamical phases—one that autoignites and another that progresses slowly. Below the critical point temperature, the chemistry of these phases is indistinguishable. In the large system limit, the pseudo-critical temperature converges to the temperature of the second explosion limit derived from mass-action kinetics.

Structural-Phase States of Fe-Cu and Fe-Ag Bimetallic Particles Produced by Electric Explosion of Two Wires

NASA Astrophysics Data System (ADS)

Lerner, M. I.; Bakina, O. V.; Pervikov, A. V.; Glazkova, E. A.; Lozhkomoev, A. S.; Vorozhtsov, A. B.

2018-05-01

X-ray phase analysis, transmission electron microscopy, and X-ray microanalysis were used to examine the structural-phase states of Fe-Cu and Fe-Ag bimetallic nanoparticles. The nanoparticles were obtained by the electric explosion of two twisted metal wires in argon atmosphere. It was demonstrated that the nanoparticles have the structure of Janus particles. Presence of the Janus particle structure in the samples indicates formation of binary melt under conditions of combined electric explosion of two wires. Phases based on supersaturated solid solutions were not found in the examined samples. The data obtained allow arguing that it is possible to achieve uniform mixing of the two-wire explosion products under the described experiment conditions.

Gelfand-type problem for two-phase porous media

PubMed Central

Gordon, Peter V.; Moroz, Vitaly

2014-01-01

We consider a generalization of the Gelfand problem arising in Frank-Kamenetskii theory of thermal explosion. This generalization is a natural extension of the Gelfand problem to two-phase materials, where, in contrast to the classical Gelfand problem which uses a single temperature approach, the state of the system is described by two different temperatures. We show that similar to the classical Gelfand problem the thermal explosion occurs exclusively owing to the absence of stationary temperature distribution. We also show that the presence of interphase heat exchange delays a thermal explosion. Moreover, we prove that in the limit of infinite heat exchange between phases the problem of thermal explosion in two-phase porous media reduces to the classical Gelfand problem with renormalized constants. PMID:24611025

Structural-Phase States of Fe–Cu and Fe–Ag Bimetallic Particles Produced by Electric Explosion of Two Wires

NASA Astrophysics Data System (ADS)

Lerner, M. I.; Bakina, O. V.; Pervikov, A. V.; Glazkova, E. A.; Lozhkomoev, A. S.; Vorozhtsov, A. B.

2018-05-01

X-ray phase analysis, transmission electron microscopy, and X-ray microanalysis were used to examine the structural-phase states of Fe-Cu and Fe-Ag bimetallic nanoparticles. The nanoparticles were obtained by the electric explosion of two twisted metal wires in argon atmosphere. It was demonstrated that the nanoparticles have the structure of Janus particles. Presence of the Janus particle structure in the samples indicates formation of binary melt under conditions of combined electric explosion of two wires. Phases based on supersaturated solid solutions were not found in the examined samples. The data obtained allow arguing that it is possible to achieve uniform mixing of the two-wire explosion products under the described experiment conditions.

Conduit Stability and Collapse in Explosive Volcanic Eruptions: Coupling Conduit Flow and Failure Models

NASA Astrophysics Data System (ADS)

Mullet, B.; Segall, P.

2017-12-01

Explosive volcanic eruptions can exhibit abrupt changes in physical behavior. In the most extreme cases, high rates of mass discharge are interspaced by dramatic drops in activity and periods of quiescence. Simple models predict exponential decay in magma chamber pressure, leading to a gradual tapering of eruptive flux. Abrupt changes in eruptive flux therefore indicate that relief of chamber pressure cannot be the only control of the evolution of such eruptions. We present a simplified physics-based model of conduit flow during an explosive volcanic eruption that attempts to predict stress-induced conduit collapse linked to co-eruptive pressure loss. The model couples a simple two phase (gas-melt) 1-D conduit solution of the continuity and momentum equations with a Mohr-Coulomb failure condition for the conduit wall rock. First order models of volatile exsolution (i.e. phase mass transfer) and fragmentation are incorporated. The interphase interaction force changes dramatically between flow regimes, so smoothing of this force is critical for realistic results. Reductions in the interphase force lead to significant relative phase velocities, highlighting the deficiency of homogenous flow models. Lateral gas loss through conduit walls is incorporated using a membrane-diffusion model with depth dependent wall rock permeability. Rapid eruptive flux results in a decrease of chamber and conduit pressure, which leads to a critical deviatoric stress condition at the conduit wall. Analogous stress distributions have been analyzed for wellbores, where much work has been directed at determining conditions that lead to wellbore failure using Mohr-Coulomb failure theory. We extend this framework to cylindrical volcanic conduits, where large deviatoric stresses can develop co-eruptively leading to multiple distinct failure regimes depending on principal stress orientations. These failure regimes are categorized and possible implications for conduit flow are discussed, including cessation of eruption.

Seismic Energy Generation and Partitioning into Various Regional Phases from Different Seismic Sources in the Middle East Region

DTIC Science & Technology

2007-09-20

phases. The power law parameter values were found to be in close agreement with the constants for nuclear explosions in Nevada and chemical explosions in...caused by the difference of lithostatic pressures between top and bottom of a vertical cylindrical explosive source, typical for borehole chemical ...NORSAR recorded several decoupled chemical explosions in large chambers of underground mines in Sweden (Stevens et al., 2003), however a reference

Towards generating a new supernova equation of state: A systematic analysis of cold hybrid stars

NASA Astrophysics Data System (ADS)

Heinimann, Oliver; Hempel, Matthias; Thielemann, Friedrich-Karl

2016-11-01

The hadron-quark phase transition in core-collapse supernovae (CCSNe) has the potential to trigger explosions in otherwise nonexploding models. However, those hybrid supernova equations of state (EOS) shown to trigger an explosion do not support the observational 2 M⊙ neutron star maximum mass constraint. In this work, we analyze cold hybrid stars by the means of a systematic parameter scan for the phase transition properties, with the aim to develop a new hybrid supernova EOS. The hadronic phase is described with the state-of-the-art supernova EOS HS(DD2), and quark matter by an EOS with a constant speed of sound (CSS) of cQM2=1 /3 . We find promising cases which meet the 2 M⊙ criterion and are interesting for CCSN explosions. We show that the very simple CSS EOS is transferable into the well-known thermodynamic bag model, important for future application in CCSN simulations. In the second part, the occurrence of reconfinement and multiple phase transitions is discussed. In the last part, the influence of hyperons in our parameter scan is studied. Including hyperons no change in the general behavior is found, except for overall lower maximum masses. In both cases (with and without hyperons) we find that quark matter with cQM2=1 /3 can increase the maximum mass only if reconfinement is suppressed or if quark matter is absolutely stable.

Training-specific functional, neural, and hypertrophic adaptations to explosive- vs. sustained-contraction strength training.

PubMed

Balshaw, Thomas G; Massey, Garry J; Maden-Wilkinson, Thomas M; Tillin, Neale A; Folland, Jonathan P

2016-06-01

Training specificity is considered important for strength training, although the functional and underpinning physiological adaptations to different types of training, including brief explosive contractions, are poorly understood. This study compared the effects of 12 wk of explosive-contraction (ECT, n = 13) vs. sustained-contraction (SCT, n = 16) strength training vs. control (n = 14) on the functional, neural, hypertrophic, and intrinsic contractile characteristics of healthy young men. Training involved 40 isometric knee extension repetitions (3 times/wk): contracting as fast and hard as possible for ∼1 s (ECT) or gradually increasing to 75% of maximum voluntary torque (MVT) before holding for 3 s (SCT). Torque and electromyography during maximum and explosive contractions, torque during evoked octet contractions, and total quadriceps muscle volume (QUADSVOL) were quantified pre and post training. MVT increased more after SCT than ECT [23 vs. 17%; effect size (ES) = 0.69], with similar increases in neural drive, but greater QUADSVOL changes after SCT (8.1 vs. 2.6%; ES = 0.74). ECT improved explosive torque at all time points (17-34%; 0.54 ≤ ES ≤ 0.76) because of increased neural drive (17-28%), whereas only late-phase explosive torque (150 ms, 12%; ES = 1.48) and corresponding neural drive (18%) increased after SCT. Changes in evoked torque indicated slowing of the contractile properties of the muscle-tendon unit after both training interventions. These results showed training-specific functional changes that appeared to be due to distinct neural and hypertrophic adaptations. ECT produced a wider range of functional adaptations than SCT, and given the lesser demands of ECT, this type of training provides a highly efficient means of increasing function. Copyright © 2016 the American Physiological Society.

Energy Partitioning of Seismic Phases: Current Datasets and Techniques Aimed at Improving the Future of Event Identification

NASA Astrophysics Data System (ADS)

Bonner, J.

2006-05-01

Differences in energy partitioning of seismic phases from earthquakes and explosions provide the opportunity for event identification. In this talk, I will briefly review teleseismic Ms:mb and P/S ratio techniques that help identify events based on differences in compressional, shear, and surface wave energy generation from explosions and earthquakes. With the push to identify smaller yield explosions, the identification process has become increasingly complex as varied types of explosions, including chemical, mining, and nuclear, must be identified at regional distances. Thus, I will highlight some of the current views and problems associated with the energy partitioning of seismic phases from single- and delay-fired chemical explosions. One problem yet to have a universally accepted answer is whether the explosion and earthquake populations, based on the Ms:mb discriminants, should be separated at smaller magnitudes. I will briefly describe the datasets and theory that support either converging or parallel behavior of these populations. Also, I will discuss improvement to the currently used methods that will better constrain this problem in the future. I will also discuss the role of regional P/S ratios in identifying explosions. In particular, recent datasets from South Africa, Scandinavia, and the Western United States collected from earthquakes, single-fired chemical explosions, and/or delay-fired mining explosions have provide new insight into regional P, S, Lg, and Rg energy partitioning. Data from co-located mining and chemical explosions suggest that some mining explosions may be used for limited calibration of regional discriminants in regions where no historic explosion data is available.

Source characterization for an explosion during the 2009 eruption of Redoubt Volcano from very-long-period seismic waves

USGS Publications Warehouse

Haney, Matthew M.; Chouet, Bernard A.; Dawson, Phillip B.; Power, John A.

2013-01-01

The 2009 eruption of Redoubt produced several very-long-period (VLP) signals associated with explosions. We invert for the source location and mechanism of an explosion at Redoubt volcano using waveform methods applied to broadband recordings. Such characterization of the source carries information on the geometry of the conduit and the physics of the explosion process. Inversions are carried out assuming the volcanic source can be modeled as a point source, with mechanisms described by a) a set of 3 orthogonal forces, b) a moment tensor consisting of force couples, and c) both forces and moment tensor components. We find that the source of the VLP seismic waves during the explosion is well-described by either a combined moment/force source located northeast of the crater and at an elevation of 1.6 km ASL or a moment source at an elevation of 800 m to the southwest of the crater. The moment tensors for the solutions with moment and force and moment-only share similar characteristics. The source time functions for both moment tensors begin with inflation (pressurization) and execute two cycles of deflation-reinflation (depressurization–repressurization). Although the moment/force source provides a better fit to the data, we find that owing to the limited coverage of the broadband stations at Redoubt the moment-only source is the more robust and reliable solution. Based on the moment-only solution, we estimate a volume change of 19,000 m3 and a pressure change of 7 MPa in a dominant sill and an out-of-phase volume change of 5000 m3 and pressure change of 1.8 MPa in a subdominant dike at the source location. These results shed new light on the magmatic plumbing system beneath Redoubt and complement previous studies on Vulcanian explosions at other volcanoes.

Toward wearable sensors: optical sensor for detection of ammonium nitrate-based explosives, ANFO and ANNM.

PubMed

Sheykhi, Sara; Mosca, Lorenzo; Anzenbacher, Pavel

2017-05-04

Increasing security needs require compact and portable detection tools for the rapid and reliable identification of explosives used in improvised explosive devices (IEDs). We report of an easy-to-use optical sensor for both vapour-phase and solution-phase identification of explosive mixtures that uses a cross-reactive fluorimetric sensor array comprising chemically responsive fluorimetric indicators composed of aromatic aldehydes and polyethyleneimine. Ammonium nitrate-nitromethane (ANNM) was analyzed by paper microzone arrays and nanofiber sensor mats. Progress toward wearable sensors based on electrospun nanofiber mats is outlined.

Thermal Explosion Violence of HMX-Based and RDX-Based Explosives - Effects of Composition, Confinement, and Solid Phase Using the Scaled Thermal Explosion Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maienschein, J L; Wardell, J F

The Scaled Thermal Explosion Experiment (STEX) has been developed to quantify the violence of thermal explosion under well defined and carefully controlled initial and boundary conditions. Here we present results with HMX-based explosives (LX-04 and PBX-9501) and with Composition B. Samples are 2 inches (50 mm) in diameter and 8 inches (200 mm) in length, under confinement of 7,500-30,000 psi (50-200 MPa), with heating rates of 1-3 C/hr. We quantify reaction violence by measuring the wall velocity in the ensuing thermal explosion, and relate the measured velocity to that expected from a detonation. Results with HMX-based explosives (LX-04 and PBX-9501)more » have shown the importance of confinement and HMX solid phase, with reaction violence ranging from mild pressure bursts to near detonations. By contrast, Composition B has shown very violent reactions over a wide range of conditions.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Willey, Trevor M.; Lauderbach, Lisa; Gagliardi, Franco

HMX-based explosives LX-10 and PBX-9501 were heated through the β-δ phase transition. Ultra-small angle x-ray scattering (USAXS) and molecular diffraction were simultaneously recorded as the HMX was heated. Mesoscale voids and structure dramatically change promptly with the β-δ phase transition, rather than with other thermal effects. Also, x-ray induced damage, observed in the USAXS, occurs more readily at elevated temperatures; as such, the dose was reduced to mitigate this effect. Optical microscopy performed during a similar heating cycle gives an indication of changes on longer length scales, while x-ray microtomography, performed before and after heating, shows the character of extensivemore » microstructural damage resulting from the temperature cycle and solid-state phase transition.« less

The 2008 phreatomagmatic eruption of Okmok volcano, Aleutian Islands, Alaska: Chronology, deposits, and landform changes

USGS Publications Warehouse

Jessica Larsen,; Neal, Christina; Schaefer, Janet R.; Kaufman, Max; Lu, Zhong

2015-01-01

Okmok volcano, Aleutian Islands, Alaska, explosively erupted over a five-week period between July 12 and August 23, 2008. The eruption was predominantly phreatomagmatic, producing fine-grained tephra that covered most of northeastern Umnak Island. The eruption had a maximum Volcanic Explosivity Index (VEI) of 4, with eruption column heights up to 16 km during the opening phase. Several craters and a master tuff cone formed in the caldera as a result of phreatomagmatic explosions and accumulated tephra-fall and surge deposits. Ascending magma continuously interacted with an extensive shallow groundwater table in the caldera, resulting in the phreatomagmatic character of the eruption. Syneruptive explosion and collapse processes enlarged a pre-existing lake, created a second, entirely new lake, and formed new, deep craters. A field of ephemeral collapse pits and collapse escarpments formed where rapid groundwater withdrawal removed material from beneath capping lava flows. This was the first significant phreatomagmatic event in the U.S. since the Ukinrek Maars eruption in 1977.

Method and apparatus for selective capture of gas phase analytes using metal .beta.-diketonate polymers

DOEpatents

Harvey, Scott D [Kennewick, WA

2011-06-21

A process and sensor device are disclosed that employ metal .beta.-diketonate polymers to selectively capture gas-phase explosives and weaponized chemical agents in a sampling area or volume. The metal .beta.-diketonate polymers can be applied to surfaces in various analytical formats for detection of: improvised explosive devices, unexploded ordinance, munitions hidden in cargo holds, explosives, and chemical weapons in public areas.

Sunset Crater, AZ: Evolution of a highly explosive basaltic eruption as indicated by granulometry and clast componentry

NASA Astrophysics Data System (ADS)

Allison, C. M.; Clarke, A. B.; Pioli, L.; Alfano, F.

2011-12-01

Basaltic scoria cone volcanoes are the most abundant volcanic edifice on Earth and occur in all tectonic settings. Basaltic magmas have lower viscosities, higher temperatures, and lower volatile contents than silicic magmas, and therefore generally have a lower potential for explosive activity. However, basaltic eruptions display great variability in eruptive style, from mild lava flows to more energetic explosions with large plumes. The San Francisco Volcanic Field (SFVF) in northern Arizona, active from 6 Ma-present, consists of over 600 volcanoes, mostly alkali basalt scoria cones, and five silicic centers [Wood and Kienle (1990), Cambridge University Press]. The eruption of Sunset Crater in the SFVF during the Holocene was an anomalously large basaltic explosive eruption, consisting of eight tephra-bearing phases and three lava flows [Amos (1986), MS thesis, ASU]. Typical scoria cone-forming eruptions have volumes <0.1km3 DRE, while the Sunset Crater deposit is at least 0.6km3 DRE [Amos (1986)]. The phases vary in size and style; the beginning stages of explosive activity (phases 1-2) were considerably smaller than phases 3-5, classified as subplinian. Due to its young age, the eruptive material is fresh and the deposit is well-preserved. We sampled the first five tephra units at 25 locations, ranging from 6 km to 20 km from the vent, concentrating our efforts in the downwind direction (E and SE of the vent) along the primary dispersal axes of several phases. Notable variations among the first five phases were found from evaluation of juvenile clast componentry, with each phase containing some proportion of red, grey, and glassy to iridescent clasts. The red and grey clasts are sub-rounded to rounded with high sphericity, while the other clasts are highly angular and slightly elongate, with blue-black to gold glassy and iridescent surfaces. The glassy and iridescent clasts likely represent fresh, juvenile ejecta, which were quenched rapidly, whereas the red and grey rounded clasts may be the result of recycling of the cone or vent-fill material. Alternatively, the differences among the populations may represent lateral variations in conduit flow conditions. In general, phases associated with large volumes and large dispersal areas tend to contain larger proportions of the glassy/iridescent clasts. Phase 1 has a large proportion of glassy clasts. Phase 2 has approximately half red and half grey clasts, as well as a small fraction of glassy material. Phase 3, which is the phase with the largest dispersal area, has a similar proportion of glassy clasts as phase 1. Phase 4, the largest by volume at ~0.11km3 DRE [Amos (1986)], has the highest proportion of glassy clasts. Phase 5 is comparable to phase 4 (similar fractions of each clast type), although the glassy surface changes from gold to black as clast size decreases. Each phase is well- to very well-sorted. Future work will include textural analysis of bubbles and crystals to understand the ascent and cooling history of the different clast types, and also to better interpret differences in abundance as related to variations in eruption or vent dynamics.

On the high fidelity simulation of chemical explosions and their interaction with solid particle clouds

NASA Astrophysics Data System (ADS)

Balakrishnan, Kaushik

The flow field behind chemical explosions in multiphase environments is investigated using a robust, state-of-the-art simulation strategy that accounts for the thermodynamics, gas dynamics and fluid mechanics of relevance to the problem. Focus is laid on the investigation of blast wave propagation, growth of hydrodynamic instabilities behind explosive blasts, the mixing aspects behind explosions, the effects of afterburn and its quantification, and the role played by solid particles in these phenomena. In particular, the confluence and interplay of these different physical phenomena are explored from a fundamental perspective, and applied to the problem of chemical explosions. A solid phase solver suited for the study of high-speed, two-phase flows has been developed and validated. This solver accounts for the inter-phase mass, momentum and energy transfer through empirical laws, and ensures two-way coupling between the two phases, viz. solid particles and gas. For dense flow fields, i.e., when the solid volume fraction becomes non-negligible (˜60%), the finite volume method with a Godunov type shock-capturing scheme requires modifications to account for volume fraction gradients during the computation of cell interface gas fluxes. To this end, the simulation methodology is extended with the formulation of an Eulerian gas, Lagrangian solid approach, thereby ensuring that the so developed two-phase simulation strategy can be applied for both flow conditions, dilute and dense alike. Moreover, under dense loading conditions the solid particles inevitably collide, which is accounted for in the current research effort with the use of an empirical collision/contact model from literature. Furthermore, the post-detonation flow field consists of gases under extreme temperature and pressure conditions, necessitating the use of real gas equations of state in the multiphase model. This overall simulation strategy is then extended to the investigation of chemical explosions in multiphase environments, with emphasis on the study of hydrodynamic instability growth, mixing, afterburn effects ensuing from the process, particle ignition and combustion (if reactive), dispersion, and their interaction with the vortices in the mixing layer. The post-detonation behavior of heterogeneous explosives is addressed by using three parts to the investigation. In the first part, only one-dimensional effects are considered, with the goal to assess the presently developed dense two-phase formulation. The total deliverable impulsive loading from heterogeneous explosive charges containing inert steel particles is estimated for a suite of operating parameters and compared, and it is demonstrated that heterogeneous explosive charges deliver a higher near-field impulse than homogeneous explosive charges containing the same mass of the high explosive. In the second part, three-dimensional effects such as hydrodynamic instabilities are accounted for, with the focus on characterizing the mixing layer ensuing from the detonation of heterogeneous explosive charges containing inert steel particles. It is shown that particles introduce significant amounts of hydrodynamic instabilities in the mixing layer, resulting in additional physical phenomena that play a prominent role in the flow features. In particular, the fluctuation intensities, fireball size and growth rates are augmented for heterogeneous explosions vis-a-vis homogeneous explosions, thereby demonstrating that solid particles enhance the perturbation intensities in the flow. In the third part of the investigation of heterogeneous explosions, dense, aluminized explosions are considered, and the particles are observed to burn in two phases, with an initial quenching due to the rarefaction wave, and a final quenching outside the fireball. Due to faster response time scales, smaller particles are observed to heat and accelerate more during early times, and also cool and decelerate more at late times, compared to counterpart larger particle sizes. Furthermore, the average particle velocities at late times are observed to be independent of the initial solid volume fraction in the explosive charge, as the particles eventually reach an equilibrium with the local gas. These studies have provided some crucial insights to the flow physics of dense, aluminized explosives. (Abstract shortened by UMI.)

High Energy Rate Forming Induced Phase Transition in Austenitic Steel

NASA Astrophysics Data System (ADS)

Kovacs, T.; Kuzsella, L.

2017-02-01

In this study, the effects of explosion hardening on the microstructure and the hardness of austenitic stainless steel have been studied. The optimum explosion hardening technology of austenitic stainless steel was researched. In case of the explosive hardening used new idea means indirect hardening setup. Austenitic stainless steels have high plasticity and can be cold formed easily. However, during cold processing the hardening phenomena always occurs. Upon the explosion impact, the deformation mechanism indicates a plastic deformation and this deformation induces a phase transformation (martensite). The explosion hardening enhances the mechanical properties of the material, includes the wear resistance and hardness [1]. In case of indirect hardening as function of the setup parameters specifically the flayer plate position the hardening increased differently. It was find a relationship between the explosion hardening setup and the hardening level.

Refinement of Regional Distance Seismic Moment Tensor and Uncertainty Analysis for Source-Type Identification

DTIC Science & Technology

2011-09-01

a NSS that lies in this negative explosion positive CLVD quadrant due to the large degree of tectonic release in this event that reversed the phase...Mellman (1986) in their analysis of fundamental model Love and Rayleigh wave amplitude and phase for nuclear and tectonic release source terms, and...1986). Estimating explosion and tectonic release source parameters of underground nuclear explosions from Rayleigh and Love wave observations, Air

Examination of rapid phase change in copper wires to improve material models and understanding of burst

NASA Astrophysics Data System (ADS)

Olles, Joseph; Garasi, Christopher; Ball, J. Patrick

2017-11-01

Electrically-pulsed wires undergo multiple phase changes including a postulated metastable phase resulting in explosive wire growth. Simulations using the MHD approximation attempt to account for the governing physics, but lack the material properties (equations-of-state and electrical conductivity) to accurately predict the phase evolution of the exploding (bursting) wire. To explore the dynamics of an exploding copper wire (in water), we employ a digital micro-Schlieren streak photography technique. This imaging quantifies wire expansion and shock waves emitted from the wire during phase changes. Using differential voltage probes, a Rogowski coil, and timing fiducials, the phase change of the wire is aligned with electrical power and energy deposition. Time-correlated electrical diagnostics and imaging allow for detailed validation of MHD simulations, comparing observed phases with phase change details found in the material property descriptions. In addition to streak imaging, a long exposure image is taken to capture axial striations along the length of the wire. These images are used to compare with results from 3D MHD simulations which propose that these perturbations impact the rate of wire expansion and temporal change in phases. If successful, the experimental data will identify areas for improvement in the material property models, and modeling results will provide insight into the details of phase change in the wire with correlation to variations in the electrical signals.

Manipulating explosive sensitivity through structural modifications in a nitrate ester system

NASA Astrophysics Data System (ADS)

Manner, Virginia

2017-06-01

Understanding how condensed phase effects influence sensitivity is essential for developing next generation insensitive high explosives. However, the ability to predictably manipulate explosive sensitivity remains an elusive goal. Explosive sensitivity has been suggested to be governed by multiple factors, from intramolecular effects such as bond dissociation energy, oxygen balance, and the electrostatic potential of reactive functional groups, to larger scale effects, such as crystal structure and hot spot formation. We have developed derivatives of the explosive pentaerythritol tetranitrate (PETN) and examined them experimentally and theoretically, in order to better understand which properties influence sensitivity. With this molecular framework, we can evaluate how small changes to the structure of the molecule influence qualities such as oxygen balance, heat of formation, heat capacity, compressibility, crystal packing, and hydrogen bonding, through techniques such as differential scanning calorimetry, x-ray crystallography, and atomistic simulation. We have also used small-scale sensitivity testing as an initial tool to screen for large and consistent differences in handling sensitivity. We will discuss the many factors that contribute to sensitivity in this series of systematically-modified molecules as well as in existing well-studied explosive systems, such as triaminotrinitrobenzene (TATB) and nitroglycerin (NG). In collaboration with: Thomas Myers, Marc Cawkwell, Edward Kober, Bryce Tappan, Geoffrey Brown, Mary Sandstrom, LOS ALAMOS NATL LAB.

Explosive synchronization as a process of explosive percolation in dynamical phase space

PubMed Central

Zhang, Xiyun; Zou, Yong; Boccaletti, S.; Liu, Zonghua

2014-01-01

Explosive synchronization and explosive percolation are currently two independent phenomena occurring in complex networks, where the former takes place in dynamical phase space while the latter in configuration space. It has been revealed that the mechanism of EP can be explained by the Achlioptas process, where the formation of a giant component is controlled by a suppressive rule. We here introduce an equivalent suppressive rule for ES. Before the critical point of ES, the suppressive rule induces the presence of multiple, small sized, synchronized clusters, while inducing the abrupt formation of a giant cluster of synchronized oscillators at the critical coupling strength. We also show how the explosive character of ES degrades into a second-order phase transition when the suppressive rule is broken. These results suggest that our suppressive rule can be considered as a dynamical counterpart of the Achlioptas process, indicating that ES and EP can be unified into a same framework. PMID:24903808

Thermal Properties of FOX-7

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burnham, A K; Weese, R K; Wang, R

Much effort has been devoted to an ongoing search for more powerful, safer and environmentally friendly explosives. Since it was developed in the late 1990s, 1,1-diamino-2,2-dinitroethene (FOX-7), with lower sensitivity and comparable performance to RDX, has received increasing interest. Preliminary results on the physical and chemical characterization of FOX-7 have shown that it possesses good thermal and chemical stability. It is expected that FOX-7 will be a new important explosive ingredient in high performance, insensitive munition (IM) explosives. One of the major focuses in research on this novel energetic material is a study of its thermal properties. Oestmark et almore » have reported that DSC curves exhibit two minor endothermic peaks as well as two major exothermic peaks. Two endothermic peaks at {approx}116 and {approx}158 C suggest the presence of two solid-solid phase transitions. A third phase change below 100 C has also been reported based on a X-ray powder diffraction (XPD) study. The shapes, areas and observed temperatures of the two decomposition peaks at {approx}235 C and {approx}280 C vary with different batches and sources of the sample, and occasionally these two peaks are merged into one. The factors leading to this variation and a more complete investigation are in progress. Our laboratories have been interested in the thermal properties of energetic materials characterized by means of various thermal analysis techniques. This paper will present our results for the thermal behavior of FOX-7 including the phase changes, decomposition, kinetic analysis and the decomposition products using DSC, TG, ARC (Accelerating Rate Calorimetry), HFC (Heat Flow Calorimetry) and simultaneous TGDTA-FTIR (Fourier Transform Infrared Spectroscopy) Spectroscopy-MS (Mass) measurements.« less

Monitoring/Verification using DMS: TATP Example

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stephan Weeks, Kevin Kyle, Manuel Manard

Field-rugged and field-programmable differential mobility spectrometry (DMS) networks provide highly selective, universal monitoring of vapors and aerosols at detectable levels from persons or areas involved with illicit chemical/biological/explosives (CBE) production. CBE sensor motes used in conjunction with automated fast gas chromatography with DMS detection (GC/DMS) verification instrumentation integrated into situational operations-management systems can be readily deployed and optimized for changing application scenarios. The feasibility of developing selective DMS motes for a “smart dust” sampling approach with guided, highly selective, fast GC/DMS verification analysis is a compelling approach to minimize or prevent the illegal use of explosives or chemical and biologicalmore » materials. DMS is currently one of the foremost emerging technologies for field separation and detection of gas-phase chemical species. This is due to trace-level detection limits, high selectivity, and small size. Fast GC is the leading field analytical method for gas phase separation of chemical species in complex mixtures. Low-thermal-mass GC columns have led to compact, low-power field systems capable of complete analyses in 15–300 seconds. A collaborative effort optimized a handheld, fast GC/DMS, equipped with a non-rad ionization source, for peroxide-based explosive measurements.« less

Toward Improved Fidelity of Thermal Explosion Simulations

NASA Astrophysics Data System (ADS)

Nichols, A. L.; Becker, R.; Howard, W. M.; Wemhoff, A.

2009-12-01

We will present results of an effort to improve the thermal/chemical/mechanical modeling of HMX based explosives like LX04 and LX10 for thermal cook-off The original HMX model and analysis scheme were developed by Yoh et al. for use in the ALE3D modeling framework. The current results were built to remedy the deficiencies of that original model. We concentrated our efforts in four areas. The first area was addition of porosity to the chemical material model framework in ALE3D that is used to model the HMX explosive formulation. This is needed to handle the roughly 2% porosity in solid explosives. The second area was the improvement of the HMX reaction network, which included a reactive phase change model base on work by Henson et al. The third area required adding early decomposition gas species to the CHEETAH material database to develop more accurate equations of state for gaseous intermediates and products. Finally, it was necessary to improve the implicit mechanics module in ALE3D to more naturally handle the long time scales associated with thermal cook-off The application of the resulting framework to the analysis of the Scaled Thermal Explosion (STEX) experiments will be discussed.

Numerical study of blast characteristics from detonation of homogeneous explosives

NASA Astrophysics Data System (ADS)

Balakrishnan, Kaushik; Genin, Franklin; Nance, Doug V.; Menon, Suresh

2010-04-01

A new robust numerical methodology is used to investigate the propagation of blast waves from homogeneous explosives. The gas-phase governing equations are solved using a hybrid solver that combines a higher-order shock capturing scheme with a low-dissipation central scheme. Explosives of interest include Nitromethane, Trinitrotoluene, and High-Melting Explosive. The shock overpressure and total impulse are estimated at different radial locations and compared for the different explosives. An empirical scaling correlation is presented for the shock overpressure, incident positive phase pressure impulse, and total impulse. The role of hydrodynamic instabilities to the blast effects of explosives is also investigated in three dimensions, and significant mixing between the detonation products and air is observed. This mixing results in afterburn, which is found to augment the impulse characteristics of explosives. Furthermore, the impulse characteristics are also observed to be three-dimensional in the region of the mixing layer. This paper highlights that while some blast features can be successfully predicted from simple one-dimensional studies, the growth of hydrodynamic instabilities and the impulsive loading of homogeneous explosives require robust three-dimensional investigation.

Kinetic parameters and nitrate, nitrite changes in bioremediation of Toxic Pentaerythritol Tetranitrate (PETN) contaminated soil

PubMed Central

Sadani, Mohsen; Karami, Mohammad Amin; Teimouri, Fahimeh; Amin, Mohammad Mehdi; Moosavi, Seyed Mahdi; Dehdashti, Bahare

2017-01-01

Background Cleanup of areas contaminated by explosives is a public health concern. Some explosives can be carcinogenic in humans. Pentaerythritol Tetranitrate (PETN), a powerful explosive with very low water solubility, can be easily transported to ground waters. Objective This study was conducted to determine the removal efficiencies of PETN from soil by bioremediation, and obtain kinetic parameters of biological process. Methods This experimental study was conducted at the Environmental Health Engineering Lab (Isfahan University of Medical Sciences, Isfahan, Iran) in 2015–2016. In the present work, bioremediation of the explosive-polluted soils by PETN in anaerobic-aerobic landfarming method was performed. The influence of seeding and biosurfactant addition on bioremediation was also evaluated. The data were analyzed using Microsoft Excel software. Results The results show that, as the initial concentration of PETN increased, the lag phase was increased and the specific growth rate was increased up to 0.1/day in concentration of 50 mg/kg, and then it was decreased to 0.04/day. Subsequent decreases in specific growth rate can cause substrate inhibition. Seeding causes decrease in lag phase significantly. Biosurfactant addition had little to no impact on the length of lag phase, but biosurfactant plus seeding can increase the growth rate to 0.2/day, however, inhibitory effect of the initial concentration was started in very high concentration of PETN (150 mg/kg). Conclusion Biosurfactant addition and seeding together have an impressive effect on biodegradation of PETN, furthermore seeding can enhance active microbial consortium and biosurfactant can improve the poor aqueous solubility of PETN, therefore making the substrate more accessible. PMID:29238507

Response of two-phase droplets to intense electromagnetic radiation

NASA Technical Reports Server (NTRS)

Spann, James F.; Maloney, Daniel J.; Lawson, William F.; Casleton, Kent H.

1993-01-01

The response of two-phase droplets to intense radiant heating is studied to determine the incident power that is required for causing explosive boiling in the liquid phase. The droplets studied consist of strongly absorbing coal particles dispersed in a weakly absorbing water medium. Experiments are performed by confining droplets (radii of 37, 55, and 80 microns) electrodynamically and irradiating them from two sides with pulsed laser beams. Emphasis is placed on the transition region from accelerated droplet vaporization to droplet superheating and explosive boiling. The time scale observed for explosive boiling is more than 2 orders of magnitude longer than published values for pure liquids. The delayed response is the result of energy transfer limitations between the absorbing solid phase and the surrounding liquid.

High-pressure crystal structures of an insensitive energetic crystal: 1,1-diamino-2,2-dinitroethene

DOE PAGES

Dreger, Zbigniew A.; Stash, Adam I.; Yu, Zhi -Gang; ...

2015-12-03

Understanding the insensitivity/stability of insensitive high explosive crystals requires detailed structural information at high pressures and high temperatures of interest. Synchrotron single crystal x-ray diffraction experiments were used to determine the high-pressure structures of 1,1-diamino-2,2-dinitroethene (FOX-7), a prototypical insensitive high explosive. The phase transition around 4.5 GPa was investigated and the structures were determined at 4.27 GPa (α’-phase) and 5.9 GPa (ε-phase). The α’-phase (monoclinic, P2 1/ n), structurally indistinguishable from the ambient α-phase, transforms to the new ε-phase (triclinic, P1). The most notable features of the ε-phase, compared to the α’-phase, are: formation of planar layers and flattening ofmore » molecules. Density functional theory (DFT-D2) calculations complemented the experimental results. Furthermore, the results presented here are important for understanding the molecular and crystalline attributes governing the high-pressure insensitivity/stability of insensitive high explosive crystals.« less

High-pressure crystal structures of an insensitive energetic crystal: 1,1-diamino-2,2-dinitroethene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dreger, Zbigniew A.; Stash, Adam I.; Yu, Zhi -Gang

Understanding the insensitivity/stability of insensitive high explosive crystals requires detailed structural information at high pressures and high temperatures of interest. Synchrotron single crystal x-ray diffraction experiments were used to determine the high-pressure structures of 1,1-diamino-2,2-dinitroethene (FOX-7), a prototypical insensitive high explosive. The phase transition around 4.5 GPa was investigated and the structures were determined at 4.27 GPa (α’-phase) and 5.9 GPa (ε-phase). The α’-phase (monoclinic, P2 1/ n), structurally indistinguishable from the ambient α-phase, transforms to the new ε-phase (triclinic, P1). The most notable features of the ε-phase, compared to the α’-phase, are: formation of planar layers and flattening ofmore » molecules. Density functional theory (DFT-D2) calculations complemented the experimental results. Furthermore, the results presented here are important for understanding the molecular and crystalline attributes governing the high-pressure insensitivity/stability of insensitive high explosive crystals.« less

Overview: MURI Center on spectroscopic and time domain detection of trace explosives in condensed and vapor phases

NASA Astrophysics Data System (ADS)

Spicer, James B.; Dagdigian, Paul; Osiander, Robert; Miragliotta, Joseph A.; Zhang, Xi-Cheng; Kersting, Roland; Crosley, David R.; Hanson, Ronald K.; Jeffries, Jay

2003-09-01

The research center established by Army Research Office under the Multidisciplinary University Research Initiative program pursues a multidisciplinary approach to investigate and advance the use of complementary analytical techniques for sensing of explosives and/or explosive-related compounds as they occur in the environment. The techniques being investigated include Terahertz (THz) imaging and spectroscopy, Laser-Induced Breakdown Spectroscopy (LIBS), Cavity Ring Down Spectroscopy (CRDS) and Resonance Enhanced Multiphoton Ionization (REMPI). This suite of techniques encompasses a diversity of sensing approaches that can be applied to detection of explosives in condensed phases such as adsorbed species in soil or can be used for vapor phase detection above the source. Some techniques allow for remote detection while others have highly specific and sensitive analysis capabilities. This program is addressing a range of fundamental, technical issues associated with trace detection of explosive related compounds using these techniques. For example, while both LIBS and THz can be used to carry-out remote analysis of condensed phase analyte from a distance in excess several meters, the sensitivities of these techniques to surface adsorbed explosive-related compounds are not currently known. In current implementations, both CRDS and REMPI require sample collection techniques that have not been optimized for environmental applications. Early program elements will pursue the fundamental advances required for these techniques including signature identification for explosive-related compounds/interferents and trace analyte extraction. Later program tasks will explore simultaneous application of two or more techniques to assess the benefits of sensor fusion.

Toward an Empirically-Based Parametric Explosion Spectral Model

DTIC Science & Technology

2010-09-01

estimated (Richards and Kim, 2009). This archive could potentially provide 200 recordings of explosions at Semipalatinsk Test Site of the former Soviet...estimates of explosion yield, and prior work at the Nevada Test Site (NTS) (e.g., Walter et al., 1995) has found that explosions in weak materials have...2007). Corner frequency scaling of regional seismic phases for underground nuclear explosions at the Nevada Test Site , Bull. Seismol. Soc. Am. 97

Basaltic Diatreme To Root Zone Volcanic Processes In Tuzo Kimberlite Pipe (Gahcho Kué Kimberlite Field, NWT, Canada)

NASA Astrophysics Data System (ADS)

Seghedi, I.; Kurszlaukis, S.; Maicher, D.

2009-05-01

Tuzo pipe is infilled by a series of coherent and fragmental kimberlite facies types typical for a diatreme to root zone transition level. Coherent or transitional coherent kimberlite facies dominate at depth, but also occur at shallow levels, either as dikes or as individual or agglutinated coherent kimberlite clasts (CKC). Several fragmental kimberlite varieties fill the central and shallow portions of the pipe. The definition, geometry and extent of the geological units are complex and are controlled by vertical elements. Specific for Tuzo is: (1) high abundance of locally derived xenoliths (granitoids and minor diabase) between and within the kimberlite phases, varying in size from sub-millimeter to several tens of meters, frequent in a belt-like domain between 120-200 m depth in the pipe; (2) the general presence of CKC, represented by round-subround, irregular to amoeboid-shaped clasts with a macrocrystic or aphanitic texture, mainly derived from fragmentation of erupting magma and less commonly from previously solidified kimberlite, as well as recycled pyroclasts. In addition, some CKC are interpreted to be intersections of a complex dike network. This diversity attests formation by various volcanic processes, extending from intrusive to explosive; (3) the presence of bedded polymict wall- rock and kimberlite breccia occurring mostly in deep levels of the pipe below 345 m depth. The gradational contact relationships of these deposits with the surrounding kimberlite rocks and their location suggest that they formed in situ. The emplacement of Tuzo pipe involved repetitive volcanic explosions alternating with periods of relative quiescence causing at least partial consolidation of some facies. The volume deficit in the diatreme-root zone after each eruption was compensated by gravitational collapse of overlying diatreme tephra and pre-fragmented wall-rock xenoliths. Highly explosive phases were alternating with weak explosions or intrusive phases, suggesting an external factor to control the explosive behaviour of the magma. The overall constant volatile content of the kimberlite does not explain the observed extreme change in emplacement behaviour. The facies architecture of fragmental facies dominated by vertical elements is similar to that in non- kimberlitic diatremes and indicates deposition from debris jets marking separate and repeated explosive volcanic events. In basaltic pipes, such jets are generated by phreatomagmatic explosions in the explosion chamber(s) of the root zone, causing abundant country rock fragmentation and further efficient mixture of the various particles. Phases of high explosivity formed the finely fragmented kimberlites containing a high percentage of wall-rock xenoliths, while the fluidal-shaped and partly welded texturally variable and wall-rock- poor transitional coherent facies suggest phases of repetitive, hot, and low-energy fragmentation forming kimberlite spatter. Peperite hosted in kimberlite tephra is also typically found in basaltic root zones. Time gaps in between volcanic eruptive periods are indicated by cognate pyroclasts and reworked wall-rock deposits emplaced by sporadic sedimentation events in subterranean cavities under the widening roof of the pipe. The presence of temporary caves in the root zone is proposed also by the occurrence of spherical CKC in deep- seated fragmental kimberlite and by spatter found in transitional coherent rocks. Evidence for caves was mostly preserved at deeper pipe levels advocating continuously recurring processes during the life span of Tuzo.

Stand-off detection of vapor phase explosives by resonance enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Ehlerding, Anneli; Johansson, Ida; Wallin, Sara; Östmark, Henric

2010-10-01

Stand-off measurements on nitromethane (NM), 2,4-DNT and 2,4,6-TNT in vapor phase using resonance Raman spectroscopy have been performed. The Raman cross sections for NM, DNT and TNT in vapor phase have been measured in the wavelength range 210-300 nm under laboratory conditions, in order to estimate how large resonance enhancement factors can be achieved for these explosives. The measurements show that the signal is greatly enhanced, up to 250.000 times for 2,4-DNT and 60.000 times for 2,4,6-TNT compared to the non-resonant signal at 532 nm. For NM the resonance enhancement enabled realistic outdoor measurements in vapor phase at 13 m distance. This all indicate a potential for resonance Raman spectroscopy as a stand-off technique for detection of vapor phase explosives.

Explosive desorption of icy grain mantles in dense clouds

NASA Technical Reports Server (NTRS)

Schutte, W. A.; Greenberg, J. M.

1991-01-01

The cycling of the condensible material in dense clouds between the gas phase and the icy grain mantles is investigated. In the model studied, desorption of the ice occurs due to grain mantle explosions when photochemically stored energy is released after transient heating by a cosmic ray particle. It is shown that, depending on the grain size distribution in dense clouds, explosive desorption can maintain up to about eight percent of the carbon in the form of CO in the gas phase at typical cloud densities.

Communication: Gas-phase structural isomer identification by Coulomb explosion of aligned molecules

NASA Astrophysics Data System (ADS)

Burt, Michael; Amini, Kasra; Lee, Jason W. L.; Christiansen, Lars; Johansen, Rasmus R.; Kobayashi, Yuki; Pickering, James D.; Vallance, Claire; Brouard, Mark; Stapelfeldt, Henrik

2018-03-01

The gas-phase structures of four difluoroiodobenzene and two dihydroxybromobenzene isomers were identified by correlating the emission angles of atomic fragment ions created, following femtosecond laser-induced Coulomb explosion. The structural determinations were facilitated by confining the most polarizable axis of each molecule to the detection plane prior to the Coulomb explosion event using one-dimensional laser-induced adiabatic alignment. For a molecular target consisting of two difluoroiodobenzene isomers, each constituent structure could additionally be singled out and distinguished.

Turbulent Combustion in SDF Explosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhl, A L; Bell, J B; Beckner, V E

2009-11-12

A heterogeneous continuum model is proposed to describe the dispersion and combustion of an aluminum particle cloud in an explosion. It combines the gas-dynamic conservation laws for the gas phase with a continuum model for the dispersed phase, as formulated by Nigmatulin. Inter-phase mass, momentum and energy exchange are prescribed by phenomenological models. It incorporates a combustion model based on the mass conservation laws for fuel, air and products; source/sink terms are treated in the fast-chemistry limit appropriate for such gasdynamic fields, along with a model for mass transfer from the particle phase to the gas. The model takes intomore » account both the afterburning of the detonation products of the C-4 booster with air, and the combustion of the Al particles with air. The model equations were integrated by high-order Godunov schemes for both the gas and particle phases. Numerical simulations of the explosion fields from 1.5-g Shock-Dispersed-Fuel (SDF) charge in a 6.6 liter calorimeter were used to validate the combustion model. Then the model was applied to 10-kg Al-SDF explosions in a an unconfined height-of-burst explosion. Computed pressure histories are compared with measured waveforms. Differences are caused by physical-chemical kinetic effects of particle combustion which induce ignition delays in the initial reactive blast wave and quenching of reactions at late times. Current simulations give initial insights into such modeling issues.« less

Cantilevered probe detector with piezoelectric element

DOEpatents

Adams, Jesse D; Sulchek, Todd A; Feigin, Stuart C

2014-04-29

A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

Cantilevered probe detector with piezoelectric element

DOEpatents

Adams, Jesse D; Sulchek, Todd A; Feigin, Stuart C

2013-04-30

A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

Cantilevered probe detector with piezoelectric element

DOEpatents

Adams, Jesse D [Reno, NV; Sulchek, Todd A [Oakland, CA; Feigin, Stuart C [Reno, NV

2012-07-10

A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

Cantilevered probe detector with piezoelectric element

DOEpatents

Adams, Jesse D.; Sulchek, Todd A.; Feigin, Stuart C.

2010-04-06

A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

Cyclic Explosivity in High Elevation Phreatomagmatic Eruptions at Ocean Island Volcanoes: Implications for Aquifer Pressurization and Volcano Flank Destabilization.

NASA Astrophysics Data System (ADS)

Tarff, R.; Day, S. J.; Downes, H.; Seghedi, I.

2015-12-01

Groundwater heating and pressurization of aquifers trapped between dikes in ocean island volcanoes has been proposed as a mechanism for destabilizing and triggering large-volume flank collapses. Previous modelling has indicated that heat transfer from sustained magma flow through dikes during eruption has the potential to produce destabilizing levels of pressure on time scales of 4 to 400 days, if the aquifers remain confined. Here we revisit this proposal from a different perspective. We examine evidence for pressure variations in dike-confined aquifers during eruptions at high elevation vents on ocean island volcanoes. Initially magmatic, these eruptions change to mostly small-volume explosive phreatomagmatic activity. A recent example is the 1949 eruption on La Palma, Canary Islands. Some such eruptions involve sequences of larger-volume explosive phases or cycles, including production of voluminous low-temperature, pyroclastic density currents (PDC). Here we present and interpret data from the Cova de Paul crater eruption (Santo Antao, Cape Verde Islands). The phreatomagmatic part of this eruption formed two cycles, each culminating with eruption of PDCs. Compositional and textural variations in the products of both cycles indicate that the diatreme fill began as coarse-grained and permeable which allowed gas to escape. During the eruption, the fill evolved to a finer grained, poorly sorted, less permeable material, in which pore fluid pressures built up to produce violent explosive phases. This implies that aquifers adjacent to the feeder intrusion were not simply depressurized at the onset of phreatomagmatic explosivity but experienced fluctuations in pressure throughout the eruption as the vent repeatedly choked and emptied. In combination with fluctuations in magma supply rate, driving of aquifer pressurization by cyclical vent choking will further complicate the prediction of flank destabilization during comparable eruptions on ocean island volcanoes.

Electrical activity during the 2006 Mount St. Augustine volcanic eruptions

USGS Publications Warehouse

Thomas, Ronald J.; Krehbiel, Paul R.; Rison, William; Edens, H. E.; Aulich, G. D.; McNutt, S.R.; Tytgat, Guy; Clark, E.

2007-01-01

By using a combination of radio frequency time-of-arrival and interferometer measurements, we observed a sequence of lightning and electrical activity during one of Mount St. Augustine's eruptions. The observations indicate that the electrical activity had two modes or phases. First, there was an explosive phase in which the ejecta from the explosion appeared to be highly charged upon exiting the volcano, resulting in numerous apparently disorganized discharges and some simple lightning. The net charge exiting the volcano appears to have been positive. The second phase, which followed the most energetic explosion, produced conventional-type discharges that occurred within plume. Although the plume cloud was undoubtedly charged as a result of the explosion itself, the fact that the lightning onset was delayed and continued after and well downwind of the eruption indicates that in situ charging of some kind was occurring, presumably similar in some respects to that which occurs in normal thunderstorms.

Preparation and characterization of polyaniline-copper composites by electrical explosion of wire.

PubMed

Liu, Aijie; Bac, Luong Huu; Kim, Jin-Chun; Liu, Lizhu

2012-07-01

Polyaniline-copper composites with a polyacrylic acid (PAA) were synthesized by electrical explosion of wire. Polyaniline (PANI) and PAA were put into the explosion medium, deionized water (DIW) and ethanol, stirred for 24 hrs and sonicated for 2 hrs. These solutions were used as base liquids for explosion process to fabricate Cu nanoparticle. Optical absorption in the UV-visible region of PANI and PANI/PAA-Cu composites was measured in a range of 200-900 nm. X-ray diffraction was used to analyze the phase of the composites. XRD pattern showed the PANI was amorphous and copper was polycrystalline. Two phases of Cu and Cu2O were formed in aqueous solution while single Cu phase was obtained in ethanol solution. Field emission scanning electron microscope was used to observe the microstructure of the composites. The synthesized composites were extensively characterized by Fourier Transform Infrared (FTIR) spectroscopy and electrical measurements.

Near-Source Scattering of Explosion-Generated Rg: Insight From Difference Spectrograms of NTS Explosions

NASA Astrophysics Data System (ADS)

Gupta, I.; Chan, W.; Wagner, R.

2005-12-01

Several recent studies of the generation of low-frequency Lg from explosions indicate that the Lg wavetrain from explosions contains significant contributions from (1) the scattering of explosion-generated Rg into S and (2) direct S waves from the non-spherical spall source associated with a buried explosion. The pronounced spectral nulls observed in Lg spectra of Yucca Flats (NTS) and Semipalatinsk explosions (Patton and Taylor, 1995; Gupta et al., 1997) are related to Rg excitation caused by spall-related block motions in a conical volume over the shot point, which may be approximately represented by a compensated linear vector dipole (CLVD) source (Patton et al., 2005). Frequency-dependent excitation of Rg waves should be imprinted on all scattered P, S and Lg waves. A spectrogram may be considered as a three-dimensional matrix of numbers providing amplitude and frequency information for each point in the time series. We found difference spectrograms, derived from a normal explosion and a closely located over-buried shot recorded at the same common station, to be remarkably useful for an understanding of the origin and spectral contents of various regional phases. This technique allows isolation of source characteristics, essentially free from path and recording site effects, since the overburied shot acts as the empirical Green's function. Application of this methodology to several pairs of closely located explosions shows that the scattering of explosion-generated Rg makes significant contribution to not only Lg and its coda but also to the two other regional phases Pg (presumably by the scattering of Rg into P) and Sn. The scattered energy, identified by the presence of a spectral null at the appropriate frequency, generally appears to be more prominent in the somewhat later-arriving sections of Pg, Sn, and Lg than in the initial part. Difference spectrograms appear to provide a powerful new technique for understanding the mechanism of near-source scattering of explosion-generated Rg and its contribution to various regional phases.

Study of premixing phase of steam explosion with JASMINE code in ALPHA program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moriyama, Kiyofumi; Yamano, Norihiro; Maruyama, Yu

Premixing phase of steam explosion has been studied in ALPHA Program at Japan Atomic Energy Research Institute (JAERI). An analytical model to simulate the premixing phase, JASMINE (JAERI Simulator for Multiphase Interaction and Explosion), has been developed based on a multi-dimensional multi-phase thermal hydraulics code MISTRAL (by Fuji Research Institute Co.). The original code was extended to simulate the physics in the premixing phenomena. The first stage of the code validation was performed by analyzing two mixing experiments with solid particles and water: the isothermal experiment by Gilbertson et al. (1992) and the hot particle experiment by Angelini et al.more » (1993) (MAGICO). The code predicted reasonably well the experiments. Effectiveness of the TVD scheme employed in the code was also demonstrated.« less

Stratigraphy and textural characteristics of the 1982 83 tephra of Galunggung volcano (Indonesia): implications for volcanic hazards

NASA Astrophysics Data System (ADS)

Gourgaud, A.; Thouret, J.-C.; Bourdier, J.-L.

2000-12-01

The Galunggung volcano in western Java (Indonesia) was the site of historical activity in 1822, 1894, 1918, and 1982-83, located in a pre-historical horseshoe-shaped caldera. In 1982-83, a nine-month-long eruption generated successively (1) ash-and-scoria flows channeled in two valleys and extending 6 km from the vent (vulcanian phase 1), (2) surges and ash falls related to the excavation of a wide maar crater, with ash columns 20 km high (phreatomagmatic phase 2), and (3) ash and scoria falls that built a small cone inside the maar crater (strombolian phase 3). During phreatomagmatic phase 2, there was a significant increase of explosivity. Paradoxically, the magma composition had evolved from andesite to primitive magnesian basalt. Jet-plane incidents were recorded during this period: on the June 24 and July 13, 1982, two Boeing 747 aircraft experienced engine power loss when passing through the plume. The vertical variations of grain sizes and xenolith contents of pyroclasts were measured in the 1982-83 eruptive deposits. We show that a progressive increase of the ratio of xenolith versus juvenile magma before the end of vulcanian phase 1 heralded the increase of explosivity leading towards phreatomagmatic phase 2. In the same way, the decrease of the same ratio at the end of the phreatomagmatic phase 2 heralded the decrease of explosivity and the onset of strombolian phase 3. The transition from phase 1 to phase 2 is also marked by a slight but continuous decrease of the vesicularity index of juvenile clasts. We emphasize the increasing efficiency of groundwater/magma interaction during the eruption. The increasing interaction and renewed explosive activity occurred after a period of rest, during which additional groundwater was supplied in the vicinity of the magma column. The data suggest that it would have been possible to predict as soon as April-May 1982 the transition from vulcanian to phreatomagmatic activity, and consequently the corresponding increase in explosivity.

Toward an Empirically-Based Parametric Explosion Spectral Model

DTIC Science & Technology

2011-09-01

Site (NNSS, formerly the Nevada Test Site ) with data from explosions at the Semipalatinsk Test ...Nevada Test Site ) with data from explosions at the Semipalatinsk Test Site recorded at the Borovoye Geophysical Observatory (BRV). The BRV data archive...explosions at Semipalatinsk Test Site of the former Soviet Union (Figure 4). As an example, we plot the regional phase spectra of one of

Shock Initiated Reactions of Reactive Multiphase Blast Explosives

NASA Astrophysics Data System (ADS)

Wilson, Dennis; Granier, John; Johnson, Richard; Littrell, Donald

2015-06-01

This paper describes a new class of reactive multiphase blast explosives (RMBX) and characterization of their blast characteristics. These RMBXs are non-ideal explosive compositions of perfluoropolyether (PFPE), nano aluminum, and a micron-size high-density reactive metal - Tantalum, Zirconium, or Zinc in mass loadings of 66 to 83 percent. Unlike high explosives, these PFPE-metal compositions release energy via a fast self-oxidized combustion wave (rather than a true self-sustaining detonation) that is shock dependent, and can be overdriven to control energy release rate. The term ``reactive multiphase blast'' refers to the post-dispersion blast behavior: multiphase in that there are a gas phase that imparts pressure and a solid (particulate) phase that imparts momentum; and reactive in that the hot metal particles react with atmospheric oxygen and the explosive gas products to give an extended pressure pulse. The RMBX formulations were tested in two spherical core-shell geometries - an RMBX shell exploded by a high explosive core, and an RMBX core imploded by a high explosive shell. The fireball and blast characteristics were compared to a C-4 baseline charge.

A molecular dynamics study on thin film liquid boiling characteristics under rapid linear boundary heating: Effect of liquid film thickness

NASA Astrophysics Data System (ADS)

Rabbi, Kazi Fazle; Tamim, Saiful Islam; Faisal, A. H. M.; Mukut, K. M.; Hasan, Mohammad Nasim

2017-06-01

This study is a molecular dynamics investigation of phase change phenomena i.e. boiling of thin liquid films subjected to rapid linear heating at the boundary. The purpose of this study is to understand the phase change heat transfer phenomena at nano scale level. In the simulation, a thin film of liquid argon over a platinum surface has been considered. The simulation domain herein is a three-phase system consisting of liquid and vapor argon atoms placed over a platinum wall. Initially the whole system is brought to an equilibrium state at 90 K and then the temperature of the bottom wall is increased to a higher temperature (250K) within a finite time interval. Four different liquid argon film thicknesses have been considered (3 nm, 4 nm, 5 nm and 6 nm) in this study. The boundary heating rate (40×109 K/s) is kept constant in all these cases. Variation in system temperature, pressure, net evaporation number, spatial number density of the argon region with time for different film thickness have been demonstrated and analyzed. The present study indicates that the pattern of phase transition may be significantly different (i.e. evaporation or explosive boiling) depending on the liquid film thickness. Among the four cases considered in the present study, explosive boiling has been observed only for the liquid films of 5nm and 6nm thickness, while for the other cases, evaporation take place.

Eruption dynamics and explosive-effusive transitions during the 1400 cal BP eruption of Opala volcano, Kamchatka, Russia

NASA Astrophysics Data System (ADS)

Andrews, Benjamin J.; Dufek, Josef; Ponomareva, Vera

2018-05-01

Deposits and pumice from the 1400 cal BP eruption of Opala volcano record activity that occurred at the explosive-effusive transition, resulting in intermittent, or stop-start, behavior, where explosive activity resumed following a pause. The eruption deposited distinctive, biotite-bearing rhyolite tephra across much of Kamchatka, and its stratigraphy consists of a lithic-rich pumice fall, overlain by pumice falls and pyroclastic density deposits, with the proportion of the latter increasing with height. This sequence repeats such that the middle of the total deposit is marked by a lithic-rich fall with abundant obsidian clasts. Notably, the eruptive pumice are poorly vesiculated, with vesicle textures that record fragmentation of a partially collapsed magmatic foam. The eruption vent, Baranii Amphitheater is filled with obsidian lavas of the same composition as the rhyolite tephra. Based upon the stratigraphic and compositional relations, we divide the eruption into four phases. Phase I initiated with eruption of a lithic-rich pumice fall, followed by eruption of Plinian falls and pyroclastic density currents. During Phase II, the eruption paused for at least 5-6 h; in this time, microlites nucleated and began to grow in the magma. Phase III essentially repeated the Phase I sequence. Obsidian lavas were emplaced during Phase IV. The pumice textures suggest that the magma ascended very near the threshold decompression rate for the transition between explosive (fast) and effusive (slow) behavior. The pause during Phase II likely occurred as decompression slowed enough for the magma to develop sufficient permeability for gas to escape resulting in collapse of the magmatic foam, stopping the eruption and temporarily sealing the conduit. After about 5-6 h, eruption resumed with, once again, magma decompressing very near the explosive-effusive transition. Phase III ended when the decompression rate slowed and lava dome emplacement began. Distributions of pumice and lithic clasts, and inclusion of data from previous workers, indicate minimum deposit volumes of 0.75 and 0.75-1.15 km3 (DRE) and eruption column heights of 18 and 20 km for Phases I and III, respectively. Phases I-III had a likely total duration of 60-80 h, including a pause in activity of 5-6 h during Phase II. This study demonstrates that analysis of vesicle textures from numerous pumice combined with stratigraphic data can reveal syn-eruptive changes in and links between magma permeability, decompression rate, and eruption style. OP-22-Pum is a typical Opala pumice. XRCT scans reveal that vesicles in pumice without obvious banding in hand sample are highly elongate and strongly aligned in different regions. The first half of the animation shows vesicles (white) and the second half shows the solid portions of the pumice (yellow). The field of view is 930 × 930 × 520 μm. OP-22-PumGlass is a pumice with alternating glassy and pumiceous domains. XRCT scans show that the glassy regions contain only small, sparse vesicles, whereas the pumiceous regions comprise elongate, aligned, and interconnected vesicles. The white domains are vesicles. The field of view is 1300 × 1950 × 520 μm.

Effects of lunar phases on short-term, explosive physical performance among young trained athletes.

PubMed

Yousfi, Narimen; Mejri, Mohamed Arbi; Rouissi, Mehdi; Hammami, Amri; Tabben, Montassar; Chaouachi, Anis; Haddad, Monoem; Chamari, Karim

2018-04-01

Beliefs that lunar phases affect human physiology started in ancient times. Research has recently revealed that a physical fitness index increased in sedentary students at the new moon (NM) and full moon (FM) compared to other moon phases. However, the effect of lunar cycle (moon illumination and gravitational pull) on physical performance in athletes was not examined. Therefore, this study aimed to evaluate whether short-term explosive performance can be influenced by the different phases of the lunar cycle. Fourteen young male Taekwondo athletes (age: 16.9 ± 0.7 years, height: 159.7 ± 50.6 cm, body mass: 62.85 ± 7.84 kg) performed the following tests to assess the explosive physical performance during the different phases of the lunar cycle (NM, FQ (first quarter), FM, and LQ (last quarter)): maximal isometric manual contraction (dominant hand (MIMCD) and non-dominant hand (MIMCND)), maximal back isometric contraction (MBIC), squat jump (SJ), countermovement jump (CMJ), and 10-m sprint (10 m). The testing sessions during the different moon phases were performed in a counterbalanced order. The order of tests remained the same (MIMCD, MIMCND, MBIC, SJ, CMJ, and 10 m), and all sessions were performed in the evening (6:00 to 8:00 p.m.) on the first day of each evaluated lunar phase. Each parameter was measured over two consecutive lunar months in the calendar. Analysis of variance tests showed that there was no significant effect of lunar cycle on all explosive test measures, p > 0.05. Our results failed to identify any effect of lunar phase on evening explosive performance (mainly involving phosphagen pathway-based efforts) among young trained athletes. Therefore, it appears that moon phase/illumination does not affect short-term physical performance in young trained adolescents.

Toward Improved Fidelity of Thermal Explosion Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nichols, A L; Becker, R; Howard, W M

2009-07-17

We will present results of an effort to improve the thermal/chemical/mechanical modeling of HMX based explosive like LX04 and LX10 for thermal cook-off. The original HMX model and analysis scheme were developed by Yoh et.al. for use in the ALE3D modeling framework. The current results were built to remedy the deficiencies of that original model. We concentrated our efforts in four areas. The first area was addition of porosity to the chemical material model framework in ALE3D that is used to model the HMX explosive formulation. This is needed to handle the roughly 2% porosity in solid explosives. The secondmore » area was the improvement of the HMX reaction network, which included the inclusion of a reactive phase change model base on work by Henson et.al. The third area required adding early decomposition gas species to the CHEETAH material database to develop more accurate equations of state for gaseous intermediates and products. Finally, it was necessary to improve the implicit mechanics module in ALE3D to more naturally handle the long time scales associated with thermal cook-off. The application of the resulting framework to the analysis of the Scaled Thermal Explosion (STEX) experiments will be discussed.« less

Explosive Cyclogenesis Over the Eastern United States.

NASA Astrophysics Data System (ADS)

MacDonald, Bruce Calvin

Cases of explosive cyclogenesis occurring over the east central United States are identified and analyzed. Other selected cases of weak or nonintensifying cyclones over the same area are identified and studied for comparative purposes. Signatures of explosively deepening cyclones (bombs) are derived from the analyses, including vertical profiles of vorticity, divergence, and latent heating, and also the relative importance of terms in the vorticity tendency equation and the relative importance of convective and stable latent heating. Composite analyses for the differing phases of bomb development and for regular cyclones are presented. Analyses of individual cases reveal the importance of a low-level jet streak, low-level moisture content, and moisture gradients in the lower troposphere. A numerical model is used to further examine the important processes in explosive cyclogenesis. A mesoscale feature is introduced to improve the prediction of sea -level pressure. This feature is based on the tendency of the large scale height field and vorticity field to adjust concurrently at each time step. The model is also used to provide air parcel trajectories to indicate the importance of parcels with high vorticity and moisture content as an ingredient in explosive cyclogenesis. Sensitivity studies are carried out with the model in order to determine the effect of changes in the initial vorticity and moisture field on cyclogenesis.

Effect of graphite particle size and content on the formation mechanism of detonation polycrystalline diamond

NASA Astrophysics Data System (ADS)

Tong, Y.; Cao, Y.; Liu, R.; Shang, S. Y.; Huang, F. L.

2018-03-01

The formation mechanism of detonation polycrystalline diamond (DPD) generated from the detonation of a mixed RDX/graphite explosive is investigated. It is found experimentally that the DPD conversion rate decreases with both the content and the particle size of the graphite. Moreover, the particle sizes of the generated DPD powder are analyzed, which shows that, with the decrease in the graphite particle size, the mean number diameter of DPD decreases, but the mean volume diameter increases. In addition, with the help of scanning electron microscopy, it is observed that the in situ phase change occurs in the graphite particles, by which the small particles combine to form numerous large DPD particles. Based on both the experimental data and the classical ZND detonation model, we divide such a DPD synthesis process into two stages: In the first stage, the in situ phase change from graphite to diamond is dominant, supplemented by some coalescence growth at high pressure and temperature, which is affected mainly by the detonation performance of the mixed explosive under consideration. In the second stage, the graphitization of DPD caused by the residual heat is dominant, which is affected mainly by the unloading rate of the particle temperature.

The application of single particle aerosol mass spectrometry for the detection and identification of high explosives and chemical warfare agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Audrey Noreen

2006-01-01

Single Particle Aerosol Mass Spectrometry (SPAMS) was evaluated as a real-time detection technique for single particles of high explosives. Dual-polarity time-of-flight mass spectra were obtained for samples of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazinane (RDX), and pentaerythritol tetranitrate (PETN); peaks indicative of each compound were identified. Composite explosives, Comp B, Semtex 1A, and Semtex 1H were also analyzed, and peaks due to the explosive components of each sample were present in each spectrum. Mass spectral variability with laser fluence is discussed. The ability of the SPAMS system to identify explosive components in a single complex explosive particle (~1 pg) without the need formore » consumables is demonstrated. SPAMS was also applied to the detection of Chemical Warfare Agent (CWA) simulants in the liquid and vapor phases. Liquid simulants for sarin, cyclosarin, tabun, and VX were analyzed; peaks indicative of each simulant were identified. Vapor phase CWA simulants were adsorbed onto alumina, silica, Zeolite, activated carbon, and metal powders which were directly analyzed using SPAMS. The use of metal powders as adsorbent materials was especially useful in the analysis of triethyl phosphate (TEP), a VX stimulant, which was undetectable using SPAMS in the liquid phase. The capability of SPAMS to detect high explosives and CWA simulants using one set of operational conditions is established.« less

On mechanism of explosive boiling in nanosecond regime

NASA Astrophysics Data System (ADS)

Çelen, Serap

2016-06-01

Today laser-based machining is used to manufacture vital parts for biomedical, aviation and aerospace industries. The aim of the paper is to report theoretical, numerical and experimental investigations of explosive boiling under nanosecond pulsed ytterbium fiber laser irradiation. Experiments were performed in an effective peak power density range between 1397 and 1450 MW/cm2 on pure titanium specimens. The threshold laser fluence for phase explosion, the pressure and temperature at the target surface and the velocity of the expulsed material were reported. A narrow transition zone was realized between the normal vaporization and phase explosion fields. The proof of heterogeneous boiling was given with detailed micrographs. A novel thermal model was proposed for laser-induced splashing at high fluences. Packaging factor and scattering arc radius terms were proposed to state the level of the melt ejection process. Results of the present investigation explain the explosive boiling during high-power laser interaction with metal.

Board of Regents of the Nevada System of Higher Education, on behalf of the University of Nevada, Reno

DOEpatents

Adams, Jesse D.; Sulchek, Todd A.; Feigin, Stuart C.

2017-07-11

A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

Electrical Signals in Prayer Plants (Marantaceae)? Insights into the Trigger Mechanism of the Explosive Style Movement

PubMed Central

Jerominek, Markus; Claßen-Bockhoff, Regine

2015-01-01

The explosive pollination mechanism of the prayer plants (Marantaceae) is unique among plants. After a tactile stimulus by a pollinator, the style curls up rapidly and mediates pollen exchange. It is still under discussion whether this explosive movement is released electrophysiologically, i.e. by a change in the membrane potential (as in Venus flytrap), or purely mechanically. In the present study, electrophysiological experiments are conducted to clarify the mechanism. Artificial release experiments (chemical and electrical) and electrophysiological measurements were conducted with two phylogenetically distant species, Goeppertia bachemiana (E. Morren) Borchs. & S. Suárez and Donax canniformis (G. Forst.) K. Schum. Electric responses recorded after style release by extracellular measurements are characterised as variation potentials due to their long repolarization phase and lack of self-perpetuation. In both species, chemical and electric stimulations do not release the style movement. It is concluded that the style movement in Marantaceae is released mechanically by relieving the tissue pressure. Accordingly, the variation potential is an effect of the movement and not its cause. The study exemplarily shows that fast movements in plants are not necessarily initiated by electric changes of the membrane as known from the Venus flytrap. PMID:25997015

Electrical signals in prayer plants (marantaceae)? Insights into the trigger mechanism of the explosive style movement.

PubMed

Jerominek, Markus; Claßen-Bockhoff, Regine

2015-01-01

The explosive pollination mechanism of the prayer plants (Marantaceae) is unique among plants. After a tactile stimulus by a pollinator, the style curls up rapidly and mediates pollen exchange. It is still under discussion whether this explosive movement is released electrophysiologically, i.e. by a change in the membrane potential (as in Venus flytrap), or purely mechanically. In the present study, electrophysiological experiments are conducted to clarify the mechanism. Artificial release experiments (chemical and electrical) and electrophysiological measurements were conducted with two phylogenetically distant species, Goeppertia bachemiana (E. Morren) Borchs. & S. Suárez and Donax canniformis (G. Forst.) K. Schum. Electric responses recorded after style release by extracellular measurements are characterised as variation potentials due to their long repolarization phase and lack of self-perpetuation. In both species, chemical and electric stimulations do not release the style movement. It is concluded that the style movement in Marantaceae is released mechanically by relieving the tissue pressure. Accordingly, the variation potential is an effect of the movement and not its cause. The study exemplarily shows that fast movements in plants are not necessarily initiated by electric changes of the membrane as known from the Venus flytrap.

Phased Contrast X-Ray Imaging

ScienceCinema

Miller, Erin

2018-02-07

The Pacific Northwest National Laboratory is developing a range of technologies to broaden the field of explosives detection. Phased contrast X-ray imaging, which uses silicon gratings to detect distortions in the X-ray wave front, may be applicable to mail or luggage scanning for explosives; it can also be used in detecting other contraband, small-parts inspection, or materials characterization.

Local infrasound observations of large ash explosions at Augustine Volcano, Alaska, during January 11–28, 2006

USGS Publications Warehouse

Petersen, Tanja; De Angelis, Silvio; Tytgat, Guy; McNutt, Stephen R.

2006-01-01

We present and interpret acoustic waveforms associated with a sequence of large explosion events that occurred during the initial stages of the 2006 eruption of Augustine Volcano, Alaska. During January 11–28, 2006, 13 large explosion events created ash-rich plumes that reached up to 14 km a.s.l., and generated atmospheric pressure waves that were recorded on scale by a microphone located at a distance of 3.2 km from the active vent. The variety of recorded waveforms included sharp N-shaped waves with durations of a few seconds, impulsive signals followed by complex codas, and extended signals with emergent character and durations up to minutes. Peak amplitudes varied between 14 and 105 Pa; inferred acoustic energies ranged between 2×108 and 4×109 J. A simple N-shaped short-duration signal recorded on January 11, 2006 was associated with the vent-opening blast that marked the beginning of the explosive eruption sequence. During the following days, waveforms with impulsive onsets and extended codas accompanied the eruptive activity, which was characterized by explosion events that generated large ash clouds and pyroclastic flows along the flanks of the volcano. Continuous acoustic waveforms that lacked a clear onset were more common during this period. On January 28, 2006, the occurrence of four large explosion events marked the end of this explosive eruption phase at Augustine Volcano. After a transitional period of about two days, characterized by many small discrete bursts, the eruption changed into a stage of more sustained and less explosive activity accompanied by the renewed growth of a summit lava dome.

Numerical Simulations of Thermobaric Explosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhl, A L; Bell, J B; Beckner, V E

2007-05-04

A Model of the energy evolution in thermobaric explosions is presented. It is based on the two-phase formulation: conservation laws for the gas and particle phases along with inter-phase interaction terms. It incorporates a Combustion Model based on the mass conservation laws for fuel, air and products; source/sink terms are treated in the fast-chemistry limit appropriate for such gas dynamic fields. The Model takes into account both the afterburning of the detonation products of the booster with air, and the combustion of the fuel (Al or TNT detonation products) with air. Numerical simulations were performed for 1.5-g thermobaric explosions inmore » five different chambers (volumes ranging from 6.6 to 40 liters and length-to-diameter ratios from 1 to 12.5). Computed pressure waveforms were very similar to measured waveforms in all cases - thereby proving that the Model correctly predicts the energy evolution in such explosions. The computed global fuel consumption {mu}(t) behaved as an exponential life function. Its derivative {dot {mu}}(t) represents the global rate of fuel consumption. It depends on the rate of turbulent mixing which controls the rate of energy release in thermobaric explosions.« less

Characterization and Thermal Decomposition of Nanometer 2,2', 4,4', 6,6'-Hexanitro-Stilbene and 1,3,5-Triamino-2,4,6-Trinitrobenzene Fabricated by a Mechanical Milling Method

NASA Astrophysics Data System (ADS)

Song, Xiaolan; Wang, Yi; Zhao, Shanshan; An, Chongwei; Wang, Jingyu; Zhang, Jinglin

2018-04-01

Nanometer 2,2', 4,4', 6,6'-hexanitro-stilbene (HNS) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) were fabricated on a high-energy ball mill. The particle sizes of nano-HNS and nano-TATB were 98.4 and 57.8 nm, respectively. An SEM analysis was employed to image the micron morphology of nano-explosives. The particle size distribution was calculated by measuring the size of 300 particles in SEM images. XRD, IR, and XPS analyses were used to confirm whether the crystal phase, molecule structure, and surface elements were changed by the milling process. Thermal decomposition of nano-HNS and nano-TATB was investigated by differential scanning calorimetry (DSC) and thermal-infrared spectrometry online (DSC-IR) analyses. Using DSC traces collected from different heating rates, the kinetic and thermodynamic parameters of thermolysis of raw and nano-explosives were calculated (activation energy (EK), pre-exponential factor (lnAK), rate constant (k), activation heat (ΔH≠), activation free energy (ΔG≠), activation entropy (ΔS≠), critical temperature of thermal explosion (Tb), and critical heating rate of thermal explosion (dT/dt)Tb). The results indicated that nano-explosives were of different kinetic and thermodynamic properties from starting explosives. In addition, the gas products for thermal decomposition of nano-HNS and nano-TATB were detected. Although HNS and TATB are both nitro explosives, the decomposition products of the two were different. A mechanism to explain the difference is proposed.

Phase velocity enhancement of linear explosive shock tubes

NASA Astrophysics Data System (ADS)

Loiseau, Jason; Serge, Matthew; Szirti, Daniel; Higgins, Andrew; Tanguay, Vincent

2011-06-01

Strong, high density shocks can be generated by sequentially detonating a hollow cylinder of explosives surrounding a thin-walled, pressurized tube. Implosion of the tube results in a pinch that travels at the detonation velocity of the explosive and acts like a piston to drive a shock into the gas ahead of it. In order to increase the maximum shock velocities that can be obtained, a phase velocity generator can be used to drag an oblique detonation wave along the gas tube at a velocity much higher than the base detonation velocity of the explosive. Since yielding and failure of the gas tube is the primary limitation of these devices, it is desirable to retain the dynamic confinement effects of a heavy-walled tamper without interfering with operation of the phase velocity generator. This was accomplished by cutting a slit into the tamper and introducing a phased detonation wave such that it asymmetrically wraps around the gas tube. This type of configuration has been previously experimentally verified to produce very strong shocks but the post-shock pressure and shock velocity limits have not been investigated. This study measured the shock trajectory for various fill pressures and phase velocities to ascertain the limiting effects of tube yield, detonation obliquity and pinch aspect ratio.

A two-phase model for aluminized explosives on the ballistic and brisance performance

NASA Astrophysics Data System (ADS)

Kim, Wuhyun; Gwak, Min-cheol; Lee, Young-hun; Yoh, Jack J.

2018-02-01

The performance of aluminized high explosives is considered by varying the aluminum (Al) mass fraction in a heterogeneous mixture model. Since the time scales of the characteristic induction and combustion of high explosives and Al particles differ, the process of energy release behind the leading detonation wave front occurs over an extended period of time. For simulating the performance of aluminized explosives with varying Al mass fraction, HMX (1,3,5,7-tetrahexmine-1,3,5,7-tetrazocane) is considered as a base explosive when formulating the multiphase conservation laws of mass, momentum, and energy exchanges between the HMX product gases and Al particles. In the current study, a two-phase model is utilized in order to determine the effects of the Al mass fraction in a condensed phase explosive. First, two types of confined rate stick tests are considered to investigate the detonation velocity and the acceleration ability, which refers to the radial expansion velocity of the confinement shell. The simulation results of the confined rate stick test are compared with the experimental data for the Al mass fraction range of 0%-25%, and the optimal Al mass fraction is provided, which is consistent with the experimental observations. Additionally, a series of plate dent test simulations are conducted, the results of which show the same tendency as those of the experimental tests with varying Al mass fractions.

Juvenile pumice and pyroclastic obsidian reveal the eruptive conditions necessary for the stability of Plinian eruption of rhyolitic magma

NASA Astrophysics Data System (ADS)

Giachetti, T.; Shea, T.; Gonnermann, H. M.; McCann, K. A.; Hoxsie, E. C.

2016-12-01

Significant explosive activity generally precedes or coexists with the large effusion of rhyolitic lava (e.g., Mono Craters; Medicine Lake Volcano; Newberry; Chaitén; Cordón Caulle). Such explosive-to-effusive transitions and, ultimately, cessation of activity are commonly explained by the overall waning magma chamber pressure accompanying magma withdrawal, albeit modulated by magma outgassing. The tephra deposits of such explosive-to-effusive eruptions record the character of the transition - abrupt or gradual - as well as potential changes in eruptive conditions, such as magma composition, volatiles content, mass discharge rate, conduit size, magma outgassing. Results will be presented from a detailed study of both the gas-rich (pumice) and gas-poor (obsidian) juvenile pyroclasts produced during the Plinian phase of the 1060 CE Glass Mountain eruption of Medicine Lake Volcano, California. In the proximal deposits, a multitude of pumice-rich sections separated by layers rich in dense clasts suggests a pulsatory behavior of the explosive phase. Density measurements on 2,600 pumices show that the intermediate, most voluminous deposits have a near constant median porosity of 65%. However, rapid increase in porosity to 75-80% is observed at both the bottom and the top of the fallout deposits, suggestive of rapid variations in magma degassing. In contrast, a water content of pyroclastic obsidians of approximately 0.6 wt% does remain constant throughout the eruption, suggesting that the pyroclastic obsidians degassed up to a constant pressure of a few megapascals. Numerical modeling of eruptive magma ascent and degassing is used to provide constraints on eruption conditions.

Seismicity and infrasound associated with explosions at Mount St. Helens, 2004-2005: Chapter 6 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

USGS Publications Warehouse

Moran, Seth C.; McChesney, Patrick J.; Lockhart, Andrew B.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

2008-01-01

Six explosions occurred during 2004-5 in association with renewed eruptive activity at Mount St. Helens, Washington. Of four explosions in October 2004, none had precursory seismicity and two had explosion-related seismic tremor that marked the end of the explosion. However, seismicity levels dropped following each of the October explosions, providing the primary instrumental means for explosion detection during the initial vent-clearing phase. In contrast, explosions on January 16 and March 8, 2005, produced noticeable seismicity in the form of explosion-related tremor, infrasonic signals, and, in the case of the March 8 explosion, an increase in event size ~2 hours before the explosion. In both 2005 cases seismic tremor appeared before any infrasonic signals and was best recorded on stations located within the crater. These explosions demonstrated that reliable explosion detection at volcanoes like Mount St. Helens requires seismic stations within 1-2 km of the vent and stations with multiple acoustic sensors.

Surface-Accelerated Decomposition of δ-HMX.

PubMed

Sharia, Onise; Tsyshevsky, Roman; Kuklja, Maija M

2013-03-07

Despite extensive efforts to study the explosive decomposition of HMX, a cyclic nitramine widely used as a solid fuel, explosive, and propellant, an understanding of the physicochemical processes, governing the sensitivity of condensed HMX to detonation initiation is not yet achieved. Experimental and theoretical explorations of the initiation of chemistry are equally challenging because of many complex parallel processes, including the β-δ phase transition and the decomposition from both phases. Among four known polymorphs, HMX is produced in the most stable β-phase, which transforms into the most reactive δ-phase under heat or pressure. In this study, the homolytic NO2 loss and HONO elimination precursor reactions of the gas-phase, ideal crystal, and the (100) surface of δ-HMX are explored by first principles modeling. Our calculations revealed that the high sensitivity of δ-HMX is attributed to interactions of surfaces and molecular dipole moments. While both decomposition reactions coexist, the exothermic HONO-isomer formation catalyzes the N-NO2 homolysis, leading to fast violent explosions.

Explosive synchronization coexists with classical synchronization in the Kuramoto model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Danziger, Michael M., E-mail: michael.danziger@biu.ac.il; Havlin, Shlomo; Moskalenko, Olga I.

2016-06-15

Explosive synchronization has recently been reported in a system of adaptively coupled Kuramoto oscillators, without any conditions on the frequency or degree of the nodes. Here, we find that, in fact, the explosive phase coexists with the standard phase of the Kuramoto oscillators. We determine this by extending the mean-field theory of adaptively coupled oscillators with full coupling to the case with partial coupling of a fraction f. This analysis shows that a metastable region exists for all finite values of f > 0, and therefore explosive synchronization is expected for any perturbation of adaptively coupling added to the standard Kuramoto model.more » We verify this theory with GPU-accelerated simulations on very large networks (N ∼ 10{sup 6}) and find that, in fact, an explosive transition with hysteresis is observed for all finite couplings. By demonstrating that explosive transitions coexist with standard transitions in the limit of f → 0, we show that this behavior is far more likely to occur naturally than was previously believed.« less

AMR Code Simulations of Turbulent Combustion in Confined and Unconfined SDF Explosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhl, A L; Bell, J B; Beckner, V

2009-05-29

A heterogeneous continuum model is proposed to describe the dispersion and combustion of an aluminum particle cloud in an explosion. It combines the gas-dynamic conservation laws for the gas phase with a continuum model for the dispersed phase, as formulated by Nigmatulin. Inter-phase mass, momentum and energy exchange are prescribed by phenomenological models. It incorporates a combustion model based on the mass conservation laws for fuel, air and products; source/sink terms are treated in the fast-chemistry limit appropriate for such gas dynamic fields, along with a model for mass transfer from the particle phase to the gas. The model takesmore » into account both the afterburning of the detonation products of the booster with air, and the combustion of the Al particles with air. The model equations were integrated by high-order Godunov schemes for both the gas and particle phases. Numerical simulations of the explosion fields from 1.5-g Shock-Dispersed-Fuel (SDF) charge in a 6.6 liter calorimeter were used to validate the combustion model. Then the model was applied to 10-kg Al-SDF explosions in a vented two-room structure and in an unconfined height-of-burst explosion. Computed pressure histories are in reasonable (but not perfect) agreement with measured waveforms. Differences are caused by physical-chemical kinetic effects of particle combustion which induce ignition delays in the initial reactive blast wave and quenching of reactions at late times. Current simulations give initial insights into such modeling issues.« less

Phenobarbital-responsive episodic dyscontrol (rage) in dogs.

PubMed

Dodman, N H; Miczek, K A; Knowles, K; Thalhammer, J G; Shuster, L

1992-11-15

Episodic dyscontrol (rage) was diagnosed from the clinical history, electroencephalographic findings, and response to oral treatment with phenobarbital in 3 dogs. Clinical features included a mood change heralding aggressive incidents, explosive aggression directed at people or objects, and a postaggressive phase characterized by lethargy and lack of responsiveness. Abnormal electroencephalographic findings included spike activity in the temporal recordings. All 3 dogs responded well to anticonvulsant medication with phenobarbital.

Continental faunal exchange and the asymmetrical radiation of carnivores.

PubMed

Pires, Mathias M; Silvestro, Daniele; Quental, Tiago B

2015-10-22

Lineages arriving on islands may undergo explosive evolutionary radiations owing to the wealth of ecological opportunities. Although studies on insular taxa have improved our understanding of macroevolutionary phenomena, we know little about the macroevolutionary dynamics of continental exchanges. Here we study the evolution of eight Carnivora families that have migrated across the Northern Hemisphere to investigate if continental invasions also result in explosive diversification dynamics. We used a Bayesian approach to estimate speciation and extinction rates from a substantial dataset of fossil occurrences while accounting for the incompleteness of the fossil record. Our analyses revealed a strongly asymmetrical pattern in which North American lineages invading Eurasia underwent explosive radiations, whereas lineages invading North America maintained uniform diversification dynamics. These invasions into Eurasia were characterized by high rates of speciation and extinction. The radiation of the arriving lineages in Eurasia coincide with the decline of established lineages or phases of climate change, suggesting differences in the ecological settings between the continents may be responsible for the disparity in diversification dynamics. These results reveal long-term outcomes of biological invasions and show that the importance of explosive radiations in shaping diversity extends beyond insular systems and have significant impact at continental scales. © 2015 The Author(s).

Continental faunal exchange and the asymmetrical radiation of carnivores

PubMed Central

Pires, Mathias M.; Silvestro, Daniele; Quental, Tiago B.

2015-01-01

Lineages arriving on islands may undergo explosive evolutionary radiations owing to the wealth of ecological opportunities. Although studies on insular taxa have improved our understanding of macroevolutionary phenomena, we know little about the macroevolutionary dynamics of continental exchanges. Here we study the evolution of eight Carnivora families that have migrated across the Northern Hemisphere to investigate if continental invasions also result in explosive diversification dynamics. We used a Bayesian approach to estimate speciation and extinction rates from a substantial dataset of fossil occurrences while accounting for the incompleteness of the fossil record. Our analyses revealed a strongly asymmetrical pattern in which North American lineages invading Eurasia underwent explosive radiations, whereas lineages invading North America maintained uniform diversification dynamics. These invasions into Eurasia were characterized by high rates of speciation and extinction. The radiation of the arriving lineages in Eurasia coincide with the decline of established lineages or phases of climate change, suggesting differences in the ecological settings between the continents may be responsible for the disparity in diversification dynamics. These results reveal long-term outcomes of biological invasions and show that the importance of explosive radiations in shaping diversity extends beyond insular systems and have significant impact at continental scales. PMID:26490792

Partial inertia induces additional phase transition in the majority vote model.

PubMed

Harunari, Pedro E; de Oliveira, M M; Fiore, C E

2017-10-01

Explosive (i.e., discontinuous) transitions have aroused great interest by manifesting in distinct systems, such as synchronization in coupled oscillators, percolation regime, absorbing phase transitions, and more recently, the majority-vote model with inertia. In the latter, the model rules are slightly modified by the inclusion of a term depending on the local spin (an inertial term). In such a case, Chen et al. [Phys Rev. E 95, 042304 (2017)2470-004510.1103/PhysRevE.95.042304] have found that relevant inertia changes the nature of the phase transition in complex networks, from continuous to discontinuous. Here we give a further step by embedding inertia only in vertices with degree larger than a threshold value 〈k〉k^{*}, 〈k〉 being the mean system degree and k^{*} the fraction restriction. Our results, from mean-field analysis and extensive numerical simulations, reveal that an explosive transition is presented in both homogeneous and heterogeneous structures for small and intermediate k^{*}'s. Otherwise, a large restriction can sustain a discontinuous transition only in the heterogeneous case. This shares some similarities with recent results for the Kuramoto model [Phys. Rev. E 91, 022818 (2015)PLEEE81539-375510.1103/PhysRevE.91.022818]. Surprisingly, intermediate restriction and large inertia are responsible for the emergence of an extra phase, in which the system is partially synchronized and the classification of phase transition depends on the inertia and the lattice topology. In this case, the system exhibits two phase transitions.

Nanosecond laser ablation of target Al in a gaseous medium: explosive boiling

NASA Astrophysics Data System (ADS)

Mazhukin, V. I.; Mazhukin, A. V.; Demin, M. M.; Shapranov, A. V.

2018-03-01

An approximate mathematical description of the processes of homogeneous nucleation and homogeneous evaporation (explosive boiling) of a metal target (Al) under the influence of ns laser radiation is proposed in the framework of the hydrodynamic model. Within the continuum approach, a multi-phase, multi-front hydrodynamic model and a computational algorithm are designed to simulate nanosecond laser ablation of the metal targets immersed in gaseous media. The proposed approach is intended for modeling and detailed analysis of the mechanisms of heterogeneous and homogeneous evaporation and their interaction with each other. It is shown that the proposed model and computational algorithm allow modeling of interrelated mechanisms of heterogeneous and homogeneous evaporation of metals, manifested in the form of pulsating explosive boiling. Modeling has shown that explosive evaporation in metals is due to the presence of a near-surface temperature maximum. It has been established that in nanosecond pulsed laser ablation, such exposure regimes can be implemented in which phase explosion is the main mechanism of material removal.

Development of multi-component explosive lenses for arbitrary phase velocity generation

NASA Astrophysics Data System (ADS)

Loiseau, Jason; Huneault, Justin; Petel, Oren; Goroshin, Sam; Frost, David; Higgins, Andrew; Zhang, Fan

2013-06-01

The combination of explosives with different detonation velocities and lens-like geometric shaping is a well-established technique for producing structured detonation waves. This technique can be extended to produce nearly arbitrary detonation phase velocities for the purposes of sequentially imploding pressurized tubes or driving Mach disks through high-density metalized explosives. The current study presents the experimental development of accelerating, multi-component lenses designed using simple geometric optics and idealized front curvature. The fast explosive component is either Composition C4 (VOD = 8 km/s) or Primasheet 1000 (VOD = 7 km/s), while the slow component varies from heavily amine-diluted nitromethane (amine mass fraction exceeding 20%) to packed metal and glass particle beds wetted with amine-sensitized nitromethane. The applicability of the geometric optic analog to such highly heterogeneous explosives is also investigated. The multi-layered lens technique is further developed as a means of generating a directed mass and momentum flux of metal particles via Mach-disk formation and jetting in circular and oval planar lenses.

Direct Quantum Mechanical Simulations of Shocked Energetic Materials

DTIC Science & Technology

2008-12-01

dynamics (QMD) simulations of shocked pentaerythritol tetranitrate (PETN), a conventional high explosive , and the polymeric cubic gauche phase of...nitrogen (cg-N), proposed as an environmentally acceptable energetic alternative to conventional explosive formulations. These simulations, made...stored structural potential energy can be liberated quickly enough, it is possible that explosion can occur with energies several orders of magnitude

Ultrastructural brain abnormalities and associated behavioral changes in mice after low-intensity blast exposure.

PubMed

Song, Hailong; Konan, Landry M; Cui, Jiankun; Johnson, Catherine E; Langenderfer, Martin; Grant, DeAna; Ndam, Tina; Simonyi, Agnes; White, Tommi; Demirci, Utkan; Mott, David R; Schwer, Doug; Hubler, Graham K; Cernak, Ibolja; DePalma, Ralph G; Gu, Zezong

2018-07-16

Explosive blast-induced mild traumatic brain injury (mTBI), a "signature wound" of recent military conflicts, commonly affects service members. While past blast injury studies have provided insights into TBI with moderate- to high-intensity explosions, the impact of primary low-intensity blast (LIB)-mediated pathobiology on neurological deficits requires further investigation. Our prior considerations of blast physics predicted ultrastructural injuries at nanoscale levels. Here, we provide quantitative data using a primary LIB injury murine model exposed to open field detonation of 350 g of high-energy explosive C4. We quantified ultrastructural and behavioral changes up to 30 days post blast injury (DPI). The use of an open-field experimental blast generated a primary blast wave with a peak overpressure of 6.76 PSI (46.6 kPa) at a 3-m distance from the center of the explosion, a positive phase duration of approximate 3.0 milliseconds (ms), a maximal impulse of 8.7 PSI × ms and a sharp rising time of 9 × 10 -3  ms, with no apparent impact/acceleration in exposed animals. Neuropathologically, myelinated axonal damage was observed in blast-exposed groups at 7 DPI. Using transmission electron microscopy, we observed and quantified myelin sheath defects and mitochondrial abnormalities at 7 and 30 DPI. Inverse correlations between blast intensities and neurobehavioral outcomes including motor activities, anxiety levels, nesting behavior, spatial learning and memory occurred. These observations uncover unique ultrastructural brain abnormalities and associated behavioral changes due to primary blast injury and provide key insights into its pathogenesis and potential treatment. Copyright © 2018 Elsevier B.V. All rights reserved.

Spatial distribution of radionuclides in 3D models of SN 1987A and Cas A

NASA Astrophysics Data System (ADS)

Janka, Hans-Thomas; Gabler, Michael; Wongwathanarat, Annop

2017-02-01

Fostered by the possibilities of multi-dimensional computational modeling, in particular the advent of three-dimensional (3D) simulations, our understanding of the neutrino-driven explosion mechanism of core-collapse supernovae (SNe) has experienced remarkable progress over the past decade. First self-consistent, first-principle models have shown successful explosions in 3D, and even failed cases may be cured by moderate changes of the microphysics inside the neutron star (NS), better grid resolution, or more detailed progenitor conditions at the onset of core collapse, in particular large-scale perturbations in the convective Si and O burning shells. 3D simulations have also achieved to follow neutrino-driven explosions continuously from the initiation of the blast wave, through the shock breakout from the progenitor surface, into the radioactively powered evolution of the SN, and towards the free expansion phase of the emerging remnant. Here we present results from such simulations, which form the basis for direct comparisons with observations of SNe and SN remnants in order to derive constraints on the still disputed explosion mechanism. It is shown that predictions based on hydrodynamic instabilities and mixing processes associated with neutrino-driven explosions yield good agreement with measured NS kicks, light-curve properties of SN 1987A and asymmetries of iron and 44Ti distributions observed in SN 1987A and Cassiopeia A.

Characteristics of a plasma flow field produced by a metal array bridge foil explosion

NASA Astrophysics Data System (ADS)

Junying, WU; Long, WANG; Yase, LI; Lijun, YANG; Manzoor, SULTAN; Lang, CHEN

2018-07-01

To improve the energy utilization efficiency of metal bridge foil explosion, and increase the function range of plasmas, array bridge foil explosion experiments with different structures were performed. A Schlieren photographic measurement system with a double-pulse laser source was used to observe the flow field of a bridge foil explosion. The evolution laws of plasmas and shock waves generated by array bridge foil explosions of different structures were analyzed and compared. A multi-phase flow calculation model was established to simulate the electrical exploding process of a metal bridge foil. The plasma equation of state was determined by considering the effect of the changing number of particles and Coulomb interaction on the pressure and internal energy. The ionization degree of the plasma was calculated via the Saha–Eggert equation assuming conditions of local thermal equilibrium. The exploding process of array bridge foils was simulated, and the superposition processes of plasma beams were analyzed. The variation and distribution laws of the density, temperature, pressure, and other important parameters were obtained. The results show that the array bridge foil has a larger plasma jet diameter than the single bridge foil for an equal total area of the bridge foil. We also found that the temperature, pressure, and density of the plasma jet’s center region sharply increase because of the superposition of plasma beams.

Effects of microscale damage evolution on piezoresistive sensing in nanocomposite bonded explosives under dynamic loading via electromechanical peridynamics

NASA Astrophysics Data System (ADS)

Prakash, Naveen; Seidel, Gary D.

2018-01-01

Polymer bonded explosives can sustain microstructural damage due to accidental impact, which may reduce their operational reliability or even cause unwanted ignition leading to detonation of the explosive. Therefore a nanocomposite piezoresistivity based sensing solution is discussed here that employs a carbon nanotube based nanocomposite binder in the explosive material by which in situ real-time sensing can be obtained. A coupled electromechanical peridynamics code is used to numerically obtain the piezoresistive response of such a material under dynamic conditions, which allows one to capture damage initiation and propagation mechanisms due to stress waves. The relative change in resistance at three locations along the length of the microstructure is monitored, and found to correlate well with deformation and damage mechanisms within the material. This response can depend on many factors, such as carbon nanotube content, electrical conductivity of the grain, impact velocity and fracture properties, which are explored through numerical simulations. For example, it is found that the piezoresistive response is highly dependent on preferential pathways of electrical current , i.e. the phase through which the current flows, which is in turn affected by the conductivity of the grain and the specific pattern of damage. It is found that the results qualitatively agree with experimental data on the dynamic piezoresistive response of nanocomposites and look promising as a sensing mechanism for explosive materials.

48 CFR 252.223-7003 - Change in place of performance-ammunition and explosives.

Code of Federal Regulations, 2014 CFR

2014-10-01

... performance-ammunition and explosives. 252.223-7003 Section 252.223-7003 Federal Acquisition Regulations...—ammunition and explosives. As prescribed in 223.370-5, use the following clause: Change in Place of Performance—Ammunition and Explosives (DEC 1991) (a) The Offeror shall identify, in the “Place of Performance...

48 CFR 252.223-7003 - Change in place of performance-ammunition and explosives.

Code of Federal Regulations, 2010 CFR

2010-10-01

... performance-ammunition and explosives. 252.223-7003 Section 252.223-7003 Federal Acquisition Regulations...—ammunition and explosives. As prescribed in 223.370-5, use the following clause: Change in Place of Performance—Ammunition and Explosives (DEC 1991) (a) The Offeror shall identify, in the “Place of Performance...

48 CFR 252.223-7003 - Change in place of performance-ammunition and explosives.

Code of Federal Regulations, 2011 CFR

2011-10-01

... performance-ammunition and explosives. 252.223-7003 Section 252.223-7003 Federal Acquisition Regulations...—ammunition and explosives. As prescribed in 223.370-5, use the following clause: Change in Place of Performance—Ammunition and Explosives (DEC 1991) (a) The Offeror shall identify, in the “Place of Performance...

48 CFR 252.223-7003 - Change in place of performance-ammunition and explosives.

Code of Federal Regulations, 2013 CFR

2013-10-01

... performance-ammunition and explosives. 252.223-7003 Section 252.223-7003 Federal Acquisition Regulations...—ammunition and explosives. As prescribed in 223.370-5, use the following clause: Change in Place of Performance—Ammunition and Explosives (DEC 1991) (a) The Offeror shall identify, in the “Place of Performance...

48 CFR 252.223-7003 - Change in place of performance-ammunition and explosives.

Code of Federal Regulations, 2012 CFR

2012-10-01

... performance-ammunition and explosives. 252.223-7003 Section 252.223-7003 Federal Acquisition Regulations...—ammunition and explosives. As prescribed in 223.370-5, use the following clause: Change in Place of Performance—Ammunition and Explosives (DEC 1991) (a) The Offeror shall identify, in the “Place of Performance...

INDUSTRIAL AND SCIENTIFIC APPLICATIONS OF NUCLEAR EXPLOSIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Gerald W.

1960-01-19

ABS>Information is given for a series of underground and surface nuclear explosions ranging from 0.055 to 19 kilotons in size. A model of four stages is developed and applied to the case of the Rainier explosion: (1) Nuclear Reaction, microsecond range. (2) Hydrodynamic Phase, millisecond range. (3) Quasi-Static Phase, secondminute range. (4) Longer-Term Phase, minute-year range. Data are given for the growth rate of the Rainier cavity up to 75 msec, partition of energy in the second stage, and distribution of temperature 5 months after the Rainier explosion. The following generalizations were made for tuff soil: Radioactivity can be containedmore » completely underground at depths of D = 400 W/sup 1/3/ or greater, where W is the energy release in kilotons; the cavity initially formed has a radius of R = 50 W/sup 1/3/; and 65 to 80% of the fission-product activity is in dilute (0.1 ppm) glass solution. The purpose and scheme of the three current AEC projects, Gnome, Project Oil Sand, and Project Chariot, are given. Also, some experiments to be done with nuclear explosions are suggested for space research, production of transplutonic isotopes, neutron resonance, other cross sections, earth's structure, and seismology. (D.L.C.)« less

Formation of double front detonations of a condensed-phase explosive with powdered aluminium

NASA Astrophysics Data System (ADS)

Kim, Wuhyun; Gwak, Min-cheol; Yoh, Jack J.

2018-03-01

The performance characteristics of aluminised high explosive are considered by varying the aluminium (Al) mass fraction in a hybrid non-ideal detonation model. Since the time scales of the characteristic induction and combustion of high explosives and Al particles differ, the process of energy release behind the leading detonation wave front occurs over an extended period of time. Two cardinal observations are reported: a decrease in detonation velocity with an increase in Al mass fraction and a double front detonation (DFD) feature when anaerobic Al reaction occurs behind the front. In order to simulate the performance characteristics due to the varying Al mass fraction, the tetrahexamine tetranitramine (HMX) is considered as a base high explosive when formulating the multiphase conservation laws of mass, momentum, and energy exchanges between particles and HMX product gases. While experimental studies have been reported on the effect of Al mass fraction on both gas-phase and solid-phase detonations, the numerical investigations have been limited to only gas-phase detonation for the varying Al particles in the mixture. In the current study, a two-phase model is utilised for understanding the volumetric effects of Al mass fraction in condensed phase detonations. A series of unconfined and confined rate sticks are considered for characterising the performance of aluminised HMX with a maximum Al mass fraction of 50%. The simulated results are compared with the experimental data for 5-25% mass fractions, and the higher mass fraction behaviours are consistent with the experimental observations.

Towards a predictive thermal explosion model for energetic materials

NASA Astrophysics Data System (ADS)

Yoh, Jack J.; McClelland, Matthew A.; Maienschein, Jon L.; Wardell, Jeffrey F.

2005-01-01

We present an overview of models and computational strategies for simulating the thermal response of high explosives using a multi-physics hydrodynamics code, ALE3D. Recent improvements to the code have aided our computational capability in modeling the behavior of energetic materials systems exposed to strong thermal environments such as fires. We apply these models and computational techniques to a thermal explosion experiment involving the slow heating of a confined explosive. The model includes the transition from slow heating to rapid deflagration in which the time scale decreases from days to hundreds of microseconds. Thermal, mechanical, and chemical effects are modeled during all phases of this process. The heating stage involves thermal expansion and decomposition according to an Arrhenius kinetics model while a pressure-dependent burn model is employed during the explosive phase. We describe and demonstrate the numerical strategies employed to make the transition from slow to fast dynamics. In addition, we investigate the sensitivity of wall expansion rates to numerical strategies and parameters. Results from a one-dimensional model show that violence is influenced by the presence of a gap between the explosive and container. In addition, a comparison is made between 2D model and measured results for the explosion temperature and tube wall expansion profiles.

A systematic study of the explosion energy issue in core collapse supernova theory

NASA Astrophysics Data System (ADS)

Yamamoto, Yu

2016-06-01

Massive stars with main sequence masses greater than 8 solar mass (Msun) the main target of CCSNe researches. According to initial mass function (IMF) they occupy about 15As a matter of fact, supernova theorists have failed to reproduce this energetic stellar explosion for about a half century because micro and macro physics are highly complex and are mutual influenced. The theoretical investigation of the explosion mechanism is based on numerical simulations, which will ultimately require computational sources of exsa scales. With recent remarkable developments both in hardware and software, however, more realistic physics are incorporated and research group are beginning to overcome the difficulties, reporting successful explosions in their numerical models. The successful is still partial, unfortunately, since in the most of the cases the explosion energy hardly reaches the typical value (10^51erg). What is worse other groups found no explosion for almost same setups. The robust explosion mechanism has not yet been ascertained and is still a remaining issue. The purpose of this paper is to study how far our understanding of "neutrino heating mechanism", the current paradigm, has reached, or put another way, to expose what kind of physics are still missing to explain observations , such as explosion energy and nickel mass. As already remarked the physics in CCSNe are quite complicated with extremely high Reynolds number, highly uncertain equation of state (EOS) at supra-nuclear densities, copious neutrinos not in thermal nor chemical equilibrium with matter normally. I believe that it is justified to devote a somewhat large number of pages to the introduction. It will be also helpful for understanding the motivation of this paper. Starting with evidence from supernova light curves I will then move to the basics idea of neutrino heating mechanism and summarize some recent developments in various micro and macro physics. Key factors in the theory of massive-star evolutions are also illuminated in the introduction. Other important ingredients that are not directly related with the thesis, such as numerical treatments of neutrino transport, are given in appendices. To find the missing pieces of the current CCSNe theory, I employed an experimental way instead of running "realistic" simulations. In fact, I conducted experimental computations systematically so as to reveal (1) what is the necessary condition of the canonical explosion energy (2) what is the dominant contribution to the explosion energy (3) when the explosion energy is settled to the final value, and, finally, (4) features in pre-explosion structure of the progenitor are critical for the explosion energy. In this paper I paid particular attention to nuclear energies released in association with the production of various elements up to A 56, which are likely to contribute to the energetics of CCSNe. I performed multi-dimension hydrodynamic simulations that can also handle the evolution of elements in both nuclear statistical equilibrium (NSE) and non-equilibrium, taking particular care of transition from one to the other. We take a multi-step strategy: collapse, shock revival and the subsequent evolution until the settlement of explosion energy are treated separately and consecutively; the collapse phase is calculated under spherical symmetry to obtain mass accretion histories for different progenitors; in so doing, the inner part of the core is removed and replaced with the artificial inner boundary; the second phase treats shock revival; we construct steady accretion flows through the stalled shock wave on to the proto neutron star; using these configurations as initial conditions for 1D and 2D simulations, we determine the critical neutrino luminosities for shock revival; the evolutions that follow the shock revival are computed in the last phase, with the mass accretion histories obtained in the first phase being taken into account. In the first of two studies done for the thesis we used a single progenitor of 15Msun provided by a realistic stellar evolution calculation and studied the post-shock revival evolutions, changing the time of shock revival. We run seven 1D and five 2D models. In the second exploration, on the other hand, we pay attention to the progenitor dependence of the dynamics. Instead of using progenitor models from realistic stellar evolution calculations, I construct six pre-collapse models with different masses of Fe core and Si+S layer assuming entropy and electron fraction distributions and varying rather arbitrarily the parameters included. Unlike in the first study, we did not specify the shock revival time explicitly but gave the neutrino luminosity in this study. The explosion energy and nickel mass are calculated for eighteen 1D and eight 2D models, respectively. The two studies demonstrate that early explosions are necessary for strong explosions. It is also found that nuclear recombination energy is a major contributor to the explosion energy which is settled to the final value in 500ms whereas the nickel mass needs much longer times to reach the final value, particularly in 2D. Since the nickel tends to be overproduced in early explosions, enhanced fallbacks in multi-dimensional hydrodynamics seem to be crucial to reproduce the observed values of nickel mass and explosion energy simultaneously. As for the progenitor dependence, we found that light cores with relatively high entropies seem to be favorable for reproducing the canonical explosion by the neutrino heating mechanism. It is interesting that the explosion energy is strongly correlated with the mass accretion rate at shock revival regardless of the spatial dimensions.

Properties of Deflagration Fronts and Models for Type IA Supernovae

NASA Astrophysics Data System (ADS)

Domínguez, I.; Höflich, P.

2000-01-01

Detailed models of the explosion of a white dwarf that include self-consistent calculations of the light curve and spectra provide a link between observational quantities and the underlying explosion model. These calculations assume spherical geometry and are based on parameterized descriptions of the burning front. Recently, the first multidimensional calculations for nuclear burning fronts have been performed. Although a fully consistent treatment of the burning fronts is beyond the current state of the art, these calculations provide a new and better understanding of the physics. Several new descriptions for flame propagation have been proposed by Khokhlov et al. and Niemeyer et al. Using various descriptions for the propagation of a nuclear deflagration front, we have studied the influence on the results of previous analyses of Type Ia supernovae, namely, the nucleosynthesis and structure of the expanding envelope. Our calculations are based on a set of delayed detonation models with parameters that give a good account of the optical and infrared light curves and of the spectral evolution. In this scenario, the burning front first propagates in a deflagration mode and subsequently turns into a detonation. The explosions and light curves are calculated using a one-dimensional Lagrangian radiation-hydro code including a detailed nuclear network. We find that the results of the explosion are rather insensitive to details of the description of the deflagration front, even if its speed and the time from the transition to detonation differ almost by a factor of 2. For a given white dwarf (WD) and a fixed transition density, the total production of elements changes by less than 10%, and the distribution in the velocity space changes by less than 7%. Qualitatively, this insensitivity of the final outcome of the explosion to the details of the flame propagation during the (slow) deflagration phase can be understood as follows: for plausible variations in the speed of the turbulent deflagration, the duration of this phase is several times longer than the sound crossing time in the initial WD. Therefore, the energy produced during the early nuclear burning can be redistributed over the entire WD, causing a slow preexpansion. In this intermediate state, the WD is still bound but its binding energy is reduced by the amount of nuclear energy. The expansion ratio depends mainly on the total amount of burning during the deflagration phase. Consequently, the conditions are very similar under which nuclear burning takes place during the subsequent detonation phase. In our example, the density and temperature at the burning front changes by less than 3%, and the expansion velocity changes by less than 10%. The burning conditions are very close to previous calculations which used a constant deflagration velocity. Based on a comparison with observations, those required low deflagration speeds (~2%-3% of the speed of sound). Exceptions to the similarity are the innermost layers of ~0.03-0.05 Msolar. Still, nuclear burning is in nuclear statistical equilibrium, but the rate of electron capture is larger for the new descriptions of the flame propagation. Consequently, the production of very neutron-rich isotopes is increased. In our example, close to the center Ye is about 0.44, compared to 0.46 in the model with constant deflagration speed. This increases the 48Ca production by more than a factor of 100 to 3.E-6 Msolar. Conclusions from previous analyses of light curves and spectra on the properties of the WD and the explosions will not change, and even with the new descriptions, the delayed detonation scenario is consistent with the observations. Namely, the central density results with respect to the chemical structure of the progenitor and the transition density from deflagration to detonation do not change. The reason for this similarity is the fact that the total amount of burning during the long deflagration phase determines the restructuring of the WD prior to the detonation. Therefore, we do not expect that the precise, microphysical prescription for the speed of a subsonic burning front has a significant effect on the outcome. However, at the current level of uncertainties for the burning front, the relation between properties of the burning front and of the initial white dwarf cannot be obtained from a comparison between observation and theoretical predictions by one-dimensional models. Multidimensional calculations are needed (1) to get inside the relations between model parameters such as central density and properties of the deflagration front and its relation to the transition density between deflagration and detonation and (2) to make use of information on asphericity that is provided by polarization measurements. These questions are essential to test, estimate, and predict some of the evolutionary effects of SNe Ia and their use as cosmological yardsticks.

27 CFR 555.63 - Explosives magazine changes.

Code of Federal Regulations, 2011 CFR

2011-04-01

... business days in advance of using any reconstructed magazine or added magazine for the storage of... 27 Alcohol, Tobacco Products and Firearms 3 2011-04-01 2010-04-01 true Explosives magazine changes... Explosives magazine changes. (a) General. (1) The requirements of this section are applicable to magazines...

27 CFR 555.63 - Explosives magazine changes.

Code of Federal Regulations, 2012 CFR

2012-04-01

... business days in advance of using any reconstructed magazine or added magazine for the storage of... 27 Alcohol, Tobacco Products and Firearms 3 2012-04-01 2010-04-01 true Explosives magazine changes... Explosives magazine changes. (a) General. (1) The requirements of this section are applicable to magazines...

β-δ phase transition during dropweight impact on cyclotetramethylene-tetranitroamine

NASA Astrophysics Data System (ADS)

Czerski, H.; Greenaway, M. W.; Proud, W. G.; Field, J. E.

2004-10-01

The secondary explosive cyclotetramethylene-tetranitroamine (HMX) exists in a variety of crystal structures; the most widely used being the β-phase which is stable at room temperature and pressure. On heating, a more impact sensitive form (δ phase) is produced. The nonlinear optical technique of second harmonic generation (SHG) can be used as a probe of phase since δ-phase HMX generates a second harmonic at 532nm when 1064nm laser light is incident upon it. We present high-speed photography of SHG in HMX samples during dropweight impact and show that this technique can provide good spatial information and time resolution. We find evidence for small areas of δ-phase HMX appearing in the period from 13μs before ignition to 10μs afterwards, demonstrating that the heating on impact is sufficient to overcome the loading conditions and cause the phase change.

Crystallization kinetics of the phase change material GeSb 6Te measured with dynamic transmission electron microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winseck, M. M.; Cheng, H. -Y.; Campbell, G. H.

2016-03-30

GeSb 6Te is a chalcogenide-based phase change material that has shown great ptoential for use in solid-state memory devices. The crystallization kinetics of amorphous thin films of GeSb 6Te during laser crystallization were followed with dynamic transmission electron microscopy, a photo-emission electron microscopy technique with nanosecond-scale time resolution. Nine-frame movies of crystal growth were taken during laser crystallization. The nucleation rate is observed to be very low and the growth rates are very high, up to 10.8 m s –1 for amorphous as-deposited films and significantly higher for an amorphous film subject to sub-threshold laser annealing before crystallization. The measuredmore » growth rates exceed any directly measured growth rate of a phase change material. Here, the crystallization is reminiscent of explosive crystallization of elemental semiconductors both in the magnitude of the growth rate and in the resulting crystalline microstructures.« less

An Anion-Induced Hydrothermal Oriented-Explosive Strategy for the Synthesis of Porous Upconversion Nanocrystals

PubMed Central

Qiu, Peiyu; Sun, Rongjin; Gao, Guo; Zhang, Chunlei; Chen, Bin; Yan, Naishun; Yin, Ting; Liu, Yanlei; Zhang, Jingjing; Yang, Yao; Cui, Daxiang

2015-01-01

Rare-earth (RE)-doped upconversion nanocrystals (UCNCs) are deemed as the promising candidates of luminescent nanoprobe for biological imaging and labeling. A number of methods have been used for the fabrication of UCNCs, but their assembly into porous architectures with desired size, shape and crystallographic phase remains a long-term challenging task. Here we report a facile, anion-induced hydrothermal oriented-explosive method to simultaneously control size, shape and phase of porous UCNCs. Our results confirmed the anion-induced hydrothermal oriented-explosion porous structure, size and phase transition for the cubic/hexagonal phase of NaLuF4 and NaGdF4 nanocrystals with various sizes and shapes. This general method is very important not only for successfully preparing lanthanide doped porous UCNCs, but also for clarifying the formation process of porous UCNCs in the hydrothermal system. The synthesized UCNCs were used for in vitro and in vivo CT imaging, and could be acted as the potential CT contrast agents. PMID:25767613

Small-scale explosive seam welding. [using ribbon explosive encased in lead sheath

NASA Technical Reports Server (NTRS)

Bement, L. J.

1972-01-01

A unique small scale explosive seam welding technique is reported that has successfully joined a variety of aluminum alloys and alloy combinations in thicknesses to 0.125 inch, as well as titanium in thicknesses to 0.056 inch. The explosively welded joints are less than one-half inch in width and apparently have no long length limitation. The ribbon explosive developed in this study contains very small quantities of explosive encased in a flexible thin lead sheath. The evaluation and demonstration of this welding technique was accomplished in three phases: evaluation and optimization of ten major explosive welding variables, the development of four weld joints, and an applicational analysis which included photomicrographs, pressure integrity tests, vacuum effects, and fabrication of some potentially useful structures in aluminum and titanium.

Moment-Tensor Spectra of Source Physics Experiments (SPE) Explosions in Granite

NASA Astrophysics Data System (ADS)

Yang, X.; Cleveland, M.

2016-12-01

We perform frequency-domain moment tensor inversions of Source Physics Experiments (SPE) explosions conducted in granite during Phase I of the experiment. We test the sensitivity of source moment-tensor spectra to factors such as the velocity model, selected dataset and smoothing and damping parameters used in the inversion to constrain the error bound of inverted source spectra. Using source moments and corner frequencies measured from inverted source spectra of these explosions, we develop a new explosion P-wave source model that better describes observed source spectra of these small and over-buried chemical explosions detonated in granite than classical explosion source models derived mainly from nuclear-explosion data. In addition to source moment and corner frequency, we analyze other features in the source spectra to investigate their physical causes.

Microstructural and Phase Composition Differences Across the Interfaces in Al/Ti/Al Explosively Welded Clads

NASA Astrophysics Data System (ADS)

Fronczek, Dagmara Malgorzata; Chulist, Robert; Litynska-Dobrzynska, Lidia; Lopez, Gabriel Alejandro; Wierzbicka-Miernik, Anna; Schell, Norbert; Szulc, Zygmunt; Wojewoda-Budka, Joanna

2017-09-01

The microstructure and phase composition of Al/Ti/Al interfaces with respect to their localization were investigated. An aluminum-flyer plate exhibited finer grains located close to the upper interface than those present within the aluminum-base plate. The same tendency, but with a higher number of twins, was observed for titanium. Good quality bonding with a wavy shape and four intermetallic phases, namely, TiAl3, TiAl, TiAl2, and Ti3Al, was only obtained at the interface closer to the explosive material. The other interface was planar with three intermetallic compounds, excluding the metastable TiAl2 phase. As a result of a 100-hour annealing at 903 K (630 °C), an Al/TiAl3/Ti/TiAl3/Al sandwich was manufactured, formed with single crystalline Al layers. A substantial difference between the intermetallic layer thicknesses was measured, with 235.3 and 167.4 µm obtained for the layers corresponding to the upper and lower interfaces, respectively. An examination by transmission electron microscopy of a thin foil taken from the interface area after a 1-hour annealing at 825 K (552 °C) showed a mixture of randomly located TiAl3 grains within the aluminum. Finally, the hardness results were correlated with the microstructural changes across the samples.

Mechanochemical induced structural changes in sucrose using the rotational diamond anvil cell

NASA Astrophysics Data System (ADS)

Ciezak-Jenkins, Jennifer A.; Jenkins, Timothy A.

2018-02-01

The response of sucrose to high-pressure and shear conditions has been studied in a rotational diamond anvil cell. Previous experiments conducted by Bridgman and Teller showed divergent behavior in regard to the existence of a rheological explosion under mechanochemical stimuli. Raman spectroscopy confirmed the existence of the isostructural Phase I to Phase II transition near 5 GPa. When subjected to high-pressure and shear, Raman spectra of Phase I showed evidence that while the sucrose molecule underwent significant molecular deformation, there was no evidence of a complete chemical reaction. In contrast, Phase II showed a near-total loss of the in-situ Raman signal in response to shear, suggesting the onset of amorphization or decomposition. The divergent behaviors of Phase I and Phase II are examined in light of the differences in the hydrogen bonding and plasticity of the material.

The 2009 eruption of Redoubt Volcano, Alaska

USGS Publications Warehouse

Bull, Katharine F.; Cameron, Cheryl; Coombs, Michelle L.; Diefenbach, Angie; Lopez, Taryn; McNutt, Steve; Neal, Christina; Payne, Allison; Power, John A.; Schneider, David J.; Scott, William E.; Snedigar, Seth; Thompson, Glenn; Wallace, Kristi; Waythomas, Christopher F.; Webley, Peter; Werner, Cynthia A.; Schaefer, Janet R.

2012-01-01

Redoubt Volcano, an ice-covered stratovolcano on the west side of Cook Inlet, erupted in March 2009 after several months of escalating unrest. The 2009 eruption of Redoubt Volcano shares many similarities with eruptions documented most recently at Redoubt in 1966–68 and 1989–90. In each case, the eruptive phase lasted several months, consisted of multiple ashproducing explosions, produced andesitic lava and tephra, removed significant amounts of ice from the summit crater and Drift glacier, generated lahars that inundated the Drift River valley, and culminated with the extrusion of a lava dome in the summit crater. Prior to the 2009 explosive phase of the eruption, precursory seismicity lasted approximately six months with the fi rst weak tremor recorded on September 23, 2008. The first phreatic explosion was recorded on March 15, and the first magmatic explosion occurred seven days later, at 22:34 on March 22. The onset of magmatic explosions was preceded by a strong, shallow swarm of repetitive earthquakes that began about 04:00 on March 20, 2009, less than three days before an explosion. Nineteen major ash-producing explosions generated ash clouds that reached heights between 17,000 ft and 62,000 ft (5.2 and 18.9 km) ASL. During ash fall in Anchorage, the Ted Stevens International Airport was shut down for 20 hours, from ~17:00 on March 28 until 13:00 on March 29. On March 23 and April 4, lahars with fl ow depths to 10 m in the upper Drift River valley inundated parts of the Drift River Terminal (DRT). The explosive phase ended on April 4 with a dome collapse at 05:58. The April 4 ash cloud reached 50,000 ft (15.2 km) and moved swiftly to the southeast, depositing up to 2 mm of ash fall in Homer, Anchor Point, and Seldovia. At least two and possibly three lava domes grew and were destroyed by explosions prior to the final lava dome extrusion that began after the April 4 event. The fi nal lava dome ceased growth by July 1, 2009, with an estimated volume of 72 Mm3

Solid state gas sensors for detection of explosives and explosive precursors

NASA Astrophysics Data System (ADS)

Chu, Yun

The increased number of terrorist attacks using improvised explosive devices (IEDs) over the past few years has made the trace detection of explosives a priority for the Department of Homeland Security. Considerable advances in early detection of trace explosives employing spectroscopic detection systems and other sensing devices have been made and have demonstrated outstanding performance. However, modern IEDs are not easily detectable by conventional methods and terrorists have adapted to avoid using metallic or nitro groups in the manufacturing of IEDs. Instead, more powerful but smaller compounds, such as TATP are being more frequently used. In addition, conventional detection techniques usually require large capital investment, labor costs and energy input and are incapable of real-time identification, limiting their application. Thus, a low cost detection system which is capable of continuous online monitoring in a passive mode is needed for explosive detection. In this dissertation, a thermodynamic based thin film gas sensor which can reliably detect various explosive compounds was developed and demonstrated. The principle of the sensors is based on measuring the heat effect associated with the catalytic decomposition of explosive compounds present in the vapor phase. The decomposition mechanism is complicated and not well known, but it can be affected by many parameters including catalyst, reaction temperature and humidity. Explosives that have relatively high vapor pressure and readily sublime at room temperature, like TATP and 2, 6-DNT, are ideal candidate for vapor phase detection using the thermodynamic gas sensor. ZnO, W2O 3, V2O5 and SnO2 were employed as catalysts. This sensor exhibited promising sensitivity results for TATP, but poor selectivity among peroxide based compounds. In order to improve the sensitivity and selectivity of the thermodynamic sensor, a Pd:SnO2 nanocomposite was fabricated and tested as part of this dissertation. A combinatorial chemistry techniques were used for catalyst discovery. Specially, a series of tin oxide catalysts with continuous varying composition of palladium were fabricated to screen for the optimum Pd loading to maximize specificity. Experimental results suggested that sensors with a 12 wt.% palladium loading generated the highest sensitivity while a 8 wt.% palladium loading provided greatest selectivity. XPS and XRD were used to study how palladium doping level affects the oxidation state and crystal structure of the nanocomposite catalyst. As with any passive detection system, a necessary theme of this dissertation was the mitigation of false positive. Toward this end, an orthogonal detection system comprised of two independent sensing platforms sharing one catalyst was demonstrated using TATP, 2, 6-DNT and ammonium nitrate as target molecules. The orthogonal sensor incorporated a thermodynamic based sensing platform to measure the heat effect associated with the decomposition of explosive molecules, and a conductometric sensing platform that monitors the change in electrical conductivity of the same catalyst when exposed to the explosive substances. Results indicate that the orthogonal sensor generates an effective response to explosives presented at part per billion level. In addition, with two independent sensing platforms, a built-in redundancy of results could be expected to minimize false positive.

Detonation propagation in annular arcs of condensed phase explosives

NASA Astrophysics Data System (ADS)

Ioannou, Eleftherios; Schoch, Stefan; Nikiforakis, Nikolaos; Michael, Louisa

2017-11-01

We present a numerical study of detonation propagation in unconfined explosive charges shaped as an annular arc (rib). Steady detonation in a straight charge propagates at constant speed, but when it enters an annular section, it goes through a transition phase and eventually reaches a new steady state of constant angular velocity. This study examines the speed of the detonation wave along the annular charge during the transition phase and at steady state, as well as its dependence on the dimensions of the annulus. The system is modeled using a recently proposed diffuse-interface formulation which allows for the representation of a two-phase explosive and of an additional inert material. The explosive considered is the polymer-bonded TATB-based LX-17 and is modeled using two Jones-Wilkins-Lee (JWL) equations of state and the ignition and growth reaction rate law. Results show that steady state speeds are in good agreement with experiment. In the transition phase, the evolution of outer detonation speed deviates from the exponential bounded growth function suggested by previous studies. We propose a new description of the transition phase which consists of two regimes. The first regime is caused by local effects at the outer edge of the annulus and leads to a dependence of the outer detonation speed on the angular position along the arc. The second regime is induced by effects originating from the inner edge of the annular charge and leads to the deceleration of the outer detonation until steady state is reached. The study concludes with a parametric study where the dependence of the steady state and the transition phase on the dimensions of the annulus is investigated.

Seismic Masking of an Underground Nuclear Explosion

DTIC Science & Technology

1973-10-31

At this point in the analysis the existence of the Lgl phase (Ewing Jardetzky. and Press. 1957. p.219; Richter. 1958. p. 267; Bath . 1973. P- 76...These ve ocities are taken from the discussion by Bath who goes on to say that the ^ Phase in the records of continental earthquakes at short...the microzone of the masked explosion, but excluded from further study 1. 21 February 1963 CARMEL 2. 12 February 1965 ALPACA Reason for

27 CFR 555.56 - Change in trade name.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 27 Alcohol, Tobacco Products and Firearms 3 2013-04-01 2013-04-01 false Change in trade name. 555.56 Section 555.56 Alcohol, Tobacco Products, and Firearms BUREAU OF ALCOHOL, TOBACCO, FIREARMS, AND EXPLOSIVES, DEPARTMENT OF JUSTICE EXPLOSIVES COMMERCE IN EXPLOSIVES Licenses and Permits § 555.56 Change in trade name. A licensee or permittee...

Hydrophone Investigations of Earthquakes and Explosion Generated High-Frequency Seismic Phases

DTIC Science & Technology

1989-06-30

stacked along three axes, a temperature sensor , a 2- component tiltmeter , and floating point analog-to-digital electronics. It is clamped inside the... sensors within the ocean- sediment-basement column in order to maximize the signal-to-noise ratio and the signal fidelity of various seismic and acoustic...improved by siting the sensors below the ocean-sediment interface. These changes are especially pronounced on horizontal sensors . Although siting the

Development of Novel Decontamination and Inerting Techniques for Explosive Contaminated Facilities, Laboratory Evaluation of Concepts. Phase II. Laboratory Evaluation of Novel Explosives Decontamination Concepts

DTIC Science & Technology

1985-03-01

gallons for Building 2. -... The system must be capable of wit standing caustic corrosion. • Either stainless steel or lined mild steel may be used. As...assumed that spent charcoal could be disposed in some safe manner arid would be re- placed as used. Additional costs were in luded for sampling and analysis...decontamination of all three explosives could be effected by further sequential treatment of the spent explosives decontami- nation solutions with acidic ferrous

Mount St. Helens, 1980 to now—what’s going on?

USGS Publications Warehouse

Dzurisin, Daniel; Driedger, Carolyn L.; Faust, Lisa M.

2013-01-01

Mount St. Helens seized the world’s attention in 1980 when the largest historical landslide on Earth and a powerful explosive eruption reshaped the volcano, created its distinctive crater, and dramatically modified the surrounding landscape. An enormous lava dome grew episodically in the crater until 1986, when the volcano became relatively quiet. A new glacier grew in the crater, wrapping around and partly burying the lava dome. From 1987 to 2003, sporadic earthquake swarms and small steam explosions indicated that magma (molten rock) was being replenished deep underground. In 2004, steam-and-ash explosions heralded the start of another eruption. A quieter phase of continuous lava extrusion followed and lasted until 2008, building a new dome and doubling the volume of lava on the crater floor. Scientists with the U.S. Geological Survey and University of Washington’s Pacific Northwest Seismograph Network maintain constant watch for signs of renewed activity at Mount St. Helens and other Cascade volcanoes. Now is an ideal time for both actual and virtual visitors to Mount St. Helens to learn more about dramatic changes taking place on and beneath this active volcano.

Petrologic characteristics of the 1982 and pre-1982 eruptive products of El Chichon volcano, Chiapas, Mexico.

USGS Publications Warehouse

McGee, J.J.; Tilling, R.I.; Duffield, W.A.

1987-01-01

Studies on a suite of rocks from this volcano indicate that the juvenile materials of the 1982 and pre-1982 eruptions of the volcano have essentially the same mineralogy and chemistry. Data suggest that chemical composition changed little over the 0.3 m.y. sample period. Modally, plagioclase is the dominant phenocryst, followed by amphibole, clinopyroxene and minor phases including anhydrite. Plagioclase phenocrysts show complex zoning: the anorthite-rich zones are probably the result of changing volatile P on the magma and may reflect the changes in the volcano's magma reservoir in response to repetitive, explosive eruptive activity.-R.E.S.

Numerical Simulation of Detonation in Condensed Phase Explosives

DTIC Science & Technology

1998-08-01

34Numerical modelling of shocks in solids with elastic-plastic conditions", Shock Waves, 3: 55-66. 22. Jones, D.A., Oran, E.S. and Guirguis , R. (1990). "A...China Lake, CA 93555-6001, preprint. 55. P.J. Miller , P.J. and G.T. Sutherland, G.T. (1996) Reaction Rate Modelling of PBXN- 110, Shock Compression...report describes the development of a two-dimensional multi-material Eulerian hydrocode to model the effects of detonating condensed phase explosives on

The mixing of particle clouds plunging into water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Angelini, S.; Theofanous, T.G.; Yuen, W.W.

This work addresses certain fundamental aspects of the premixing phase of steam explosions, At issue are the multifield interaction aspects under highly transient, multidimensional conditions, and in presence of strong phase changes. They are addressed in an experiment (the MAGICO-2000) involving well-characterized particle clouds mixing with water, and detailed measurements on both external and internal characteristics of the mixing zone. Both cold and hot (up to 1500{degrees}C) particle clouds are considered in conjunction with saturated and subcooled water pools. The PMALPHA code is used as an aid in interpreting the experimental results, and the exercise reveals good predictive capabilities formore » it.« less

Density analysis of magmatic and phreatomagmatic phases of the 934 AD Eldgjá Eruption, southern Iceland

NASA Astrophysics Data System (ADS)

Moreland, William; Thordarson, Thorvaldur

2014-05-01

Eldgjá is a ~75 km long volcanic fissure vent system associated with the Katla volcanic system in southern Iceland, formed during an eruption in the mid-tenth century. The fissure is of the mixed-cone row type and produced both large lava fields and a widespread basaltic tephra deposit. Proximal tephra fall deposits are up to 4 m thick and contain numerous fall units of varying thickness which run parallel to the fissure, indicating many sources of eruption. The lower-most fall units thicken towards Mýrdalsjökull, demonstrating that the initial explosive phases took place within the glacier. Later fall units generally thicken towards the northeast with dispersal axes indicating origin at the more easterly segments of the Eldgjá vent system and a stepwise migration in an easterly direction. Both magmatic and phreatomagmatic explosive activity occurred along the vent system, where phreatomagmatic activity is confined to fissure segments within the Mýrdalsjökull glacier. Two key sections, chosen to represent magmatic and phreatomagmatic deposits, were logged and sampled for density analysis. A section at Skælingar, half a kilometre southeast of Eldgjá Proper was chosen to represent the magmatic products. It is 3.70 m thick and contains 9 fall-units including a distinct bomb-layer. The phreatomagmatic products are represented by a section from Stóragil, 20 km north-northeast of the Katla caldera and the sampled section is 1.12 m thick. Density analysis involves selecting 100 clasts 8-32 mm in diameter from <5 cm layers within the sub-units of each section. These clasts are then weighed, sealed and then weighed again in water to calculate their volume by Archimedes' principle and therefore their density, from which vesicularity can be calculated. The results were then plotted as histograms and compared with the section logs. The magmatic samples have unimodal, normal vesicularity distributions with typical modal values of 60-70% and a span of ~40%. Several of the samples have weakly negatively skewed distributions - the bomb layer has a plateau-like vesicularity distribution and a span of 51% - indicating that outgassed magma was also involved in the explosive activity. This outgassed portion of the tephra deposits is best explained by the pulsating explosions on the same fissure segment. The section at Stóragil contains both phreatomagmatic and magmatic products. The phreatomagmatic samples exhibit characteristic plateau-like distributions with modal vesicularity between 70-80% and a span of 40-50%. In one of the fall units a gradual change from plateau-like to normal distribution is observed indicating a change from phreatomagmatic to magmatic activity during the course of a single explosive phase. This implies that either gradual change in access of external water to the erupting vents or that the external water source was being exhausted. Thin-sections will be made of clasts in each sample which show extreme vesicularities. SEM photographs will be taken of these and vesicle-size distributions measured by image analysis. These results will also be presented.

27 CFR 555.63 - Explosives magazine changes.

Code of Federal Regulations, 2014 CFR

2014-04-01

... least five business days in advance of using any reconstructed magazine or added magazine for the... 27 Alcohol, Tobacco Products and Firearms 3 2014-04-01 2014-04-01 false Explosives magazine... § 555.63 Explosives magazine changes. (a) General. (1) The requirements of this section are applicable...

27 CFR 555.63 - Explosives magazine changes.

Code of Federal Regulations, 2010 CFR

2010-04-01

... least five business days in advance of using any reconstructed magazine or added magazine for the... 27 Alcohol, Tobacco Products and Firearms 3 2010-04-01 2010-04-01 false Explosives magazine... § 555.63 Explosives magazine changes. (a) General. (1) The requirements of this section are applicable...

27 CFR 555.63 - Explosives magazine changes.

Code of Federal Regulations, 2013 CFR

2013-04-01

... least five business days in advance of using any reconstructed magazine or added magazine for the... 27 Alcohol, Tobacco Products and Firearms 3 2013-04-01 2013-04-01 false Explosives magazine... § 555.63 Explosives magazine changes. (a) General. (1) The requirements of this section are applicable...

The shock Hugoniot of liquid hydrazine in the pressure range of 3.1 to 21.4 GPa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia, B.O.; Persson, P-A.

1996-10-01

Impedance matching was used; the technique was similar to Richard Dick`s. Shock pressures were produced using a plane wave explosive driver with different explosives and different reference materials against liq. hydrazine. Velocity of shock wave in the liquid and free surface velocity of the reference material were measured using different pin contact techniques. The experimental Hugoniot appears smooth, with no indication of a phase change. The shock Hugoniot of liq. hydrazine was compared against 3 other liquid Hugoniots (liq. NH3, water, CCl4) and is closest to that for water and in between NH3 and CCl4. The hydrazine Hugoniot was alsomore » compared to the ``Universal`` Hugoniot for liquids. This universal Hugoniot is not a good approximation for the liq. hydrazine in this pressure range.« less

Wireless sensor for detecting explosive material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lamberti, Vincent E; Howell, Jr., Layton N; Mee, David K

Disclosed is a sensor for detecting explosive devices. The sensor includes a ferromagnetic metal and a molecular recognition reagent coupled to the ferromagnetic metal. The molecular recognition reagent is operable to expand upon absorption of vapor from an explosive material such that the molecular recognition reagent changes a tensile stress upon the ferromagnetic metal. The explosive device is detected based on changes in the magnetic switching characteristics of the ferromagnetic metal caused by the tensile stress.

Modeling compressible multiphase flows with dispersed particles in both dense and dilute regimes

NASA Astrophysics Data System (ADS)

McGrath, T.; St. Clair, J.; Balachandar, S.

2018-05-01

Many important explosives and energetics applications involve multiphase formulations employing dispersed particles. While considerable progress has been made toward developing mathematical models and computational methodologies for these flows, significant challenges remain. In this work, we apply a mathematical model for compressible multiphase flows with dispersed particles to existing shock and explosive dispersal problems from the literature. The model is cast in an Eulerian framework, treats all phases as compressible, is hyperbolic, and satisfies the second law of thermodynamics. It directly applies the continuous-phase pressure gradient as a forcing function for particle acceleration and thereby retains relaxed characteristics for the dispersed particle phase that remove the constituent material sound velocity from the eigenvalues. This is consistent with the expected characteristics of dispersed particle phases and can significantly improve the stable time-step size for explicit methods. The model is applied to test cases involving the shock and explosive dispersal of solid particles and compared to data from the literature. Computed results compare well with experimental measurements, providing confidence in the model and computational methods applied.

A hybrid formulation for the numerical simulation of condensed phase explosives

NASA Astrophysics Data System (ADS)

Michael, L.; Nikiforakis, N.

2016-07-01

In this article we present a new formulation and an associated numerical algorithm, for the simulation of combustion and transition to detonation of condensed-phase commercial- and military-grade explosives, which are confined by (or in general interacting with one or more) compliant inert materials. Examples include confined rate-stick problems and interaction of shock waves with gas cavities or solid particles in explosives. This formulation is based on an augmented Euler approach to account for the mixture of the explosive and its products, and a multi-phase diffuse interface approach to solve for the immiscible interaction between the mixture and the inert materials, so it is in essence a hybrid (augmented Euler and multi-phase) model. As such, it has many of the desirable features of the two approaches and, critically for our applications of interest, it provides the accurate recovery of temperature fields across all components. Moreover, it conveys a lot more physical information than augmented Euler, without the complexity of full multi-phase Baer-Nunziato-type models or the lack of robustness of augmented Euler models in the presence of more than two components. The model can sustain large density differences across material interfaces without the presence of spurious oscillations in velocity and pressure, and it can accommodate realistic equations of state and arbitrary (pressure- or temperature-based) reaction-rate laws. Under certain conditions, we show that the formulation reduces to well-known augmented Euler or multi-phase models, which have been extensively validated and used in practice. The full hybrid model and its reduced forms are validated against problems with exact (or independently-verified numerical) solutions and evaluated for robustness for rate-stick and shock-induced cavity collapse case-studies.

"Fooling fido"--chemical and behavioral studies of pseudo-explosive canine training aids.

PubMed

Kranz, William D; Strange, Nicholas A; Goodpaster, John V

2014-12-01

Genuine explosive materials are traditionally employed in the training and testing of explosive-detecting canines so that they will respond reliably to these substances. However, challenges arising from the acquisition, storage, handling, and transportation of explosives have given rise to the development of "pseudo-explosive" training aids. These products attempt to emulate the odor of real explosives while remaining inert. Therefore, a canine trained on a pseudo-explosive should respond to its real-life analog. Similarly, a canine trained on an actual explosive should respond to the pseudo-explosive as if it was real. This research tested those assumptions with a focus on three explosives: single-base smokeless powder, 2,4,6-trinitrotoluene (TNT), and a RDX-based plastic explosive (Composition C-4). Using gas chromatography-mass spectrometry with solid phase microextraction as a pre-concentration technique, we determined that the volatile compounds given off by pseudo-explosive products consisted of various solvents, known additives from explosive formulations, and common impurities present in authentic explosives. For example, simulated smokeless powders emitted terpenes, 2,4-dinitrotoluene, diphenylamine, and ethyl centralite. Simulated TNT products emitted 2,4- and 2,6-dinitrotoluene. Simulated C-4 products emitted cyclohexanone, 2-ethyl-1-hexanol, and dimethyldinitrobutane. We also conducted tests to determine whether canines trained on pseudo-explosives are capable of alerting to genuine explosives and vice versa. The results show that canines trained on pseudo-explosives performed poorly at detecting all but the pseudo-explosives they are trained on. Similarly, canines trained on actual explosives performed poorly at detecting all but the actual explosives on which they were trained.

Next-Generation MDAC Discrimination Procedure Using Multi-Dimensional Spectral Analyses

DTIC Science & Technology

2007-09-01

explosions near the Lop Nor, Novaya Zemlya, Semipalatinsk , Nevada, and Indian test sites . We have computed regional phase spectra and are correcting... test sites as mainly due to differences in explosion P and S corner frequencies. Fisk (2007) used source model fits to estimate Pn, Pg, and Lg corner...frequencies for Nevada Test Site (NTS) explosions and found that Lg corner frequencies exhibit similar scaling with source size as for Pn and Pg

Shock wave induced condensation in fuel-rich gaseous and gas-particles mixtures

NASA Astrophysics Data System (ADS)

Fomin, P. A.

2018-03-01

The possibility of fuel vapor condensation in shock waves in fuel-rich (cyclohexane-oxygen) gaseous mixtures and explosion safety aspects of this effect are discussed. It is shown, that condensation process can essentially change the chemical composition of the gas. For example, the molar fraction of the oxidizer can increase in a few times. As a result, mixtures in which the initial concentration of fuel vapor exceeds the Upper Flammability Limit can, nevertheless, explode, if condensation shifts the composition of the mixture into the ignition region. The rate of the condensation process is estimated. This process can be fast enough to significantly change the chemical composition of the gas and shift it into the flammable range during the compression phase of blast waves, generated by explosions of fuel-vapor clouds or rapture of pressurized chemical reactors, with characteristic size of a few meters. It is shown that the presence of chemically inert microparticles in the gas mixtures under consideration increases the degree of supercooling and the mass of fuel vapors that have passed into the liquid and reduces the characteristic condensation time in comparison with the gas mixture without microparticles. The fuel vapor condensation should be taken into account in estimation the explosion hazard of chemical reactors, industrial and civil constructions, which may contain fuel-rich gaseous mixtures of heavy hydrocarbons with air.

Broadband Evaluation of DPRK Explosions, Collapse Event, and Induced Aftershocks

NASA Astrophysics Data System (ADS)

Mayeda, K.; Roman-Nieves, J. I.; Wagner, G.; Jeon, Y. S.

2017-12-01

We report on the past 6 declared DPRK nuclear explosions, a collapse event, and recent associated induced shear dislocation sources using long-period waveform modeling, direct regional phases, and stable P-coda and S-coda spectral ratios. We find that the recent September 3rd, 2017 explosion is well modeled with an MM71 explosion source model at normal scale depth, but the previous 5 smaller yield explosions exhibit much larger relative high frequency radiation, strongly suggesting they are all over buried by varying amounts. The collapse event that occurred 8 minutes following the September 3rd DPRK explosion shares significant similarities with a number of NTS collapse events for explosions of comparable yield, both in absolute amplitude and spectral fall-off. A large number of smaller sources have been observed, which from stable coda spectral analysis and waveform modeling, are consistent with shallow shear dislocations likely caused by stress redistribution following the past nuclear explosions. We conclude with testing of a new discriminant that is specific to this region.

Identifying open and closed system behaviors at Tungurahua volcano (Ecuador) using SO2 and seismo-acoustic measurements

NASA Astrophysics Data System (ADS)

Hidalgo, Silvana; Battaglia, Jean; Bernard, Benjamin; Steele, Alexander; Arellano, Santiago; Galle, Bo

2014-05-01

Tungurahua is one of the most active volcanoes in Ecuador. It is located in Central Ecuador, 160 km South of Quito and 8 km South of the touristic town of Baños. Tungurahua had one eruption every century since 1500, with an activity characterized by ash fallouts and pyroclastic and lava flows. The current eruptive period of Tungurahua began in 1999 with multiple episodes of explosive activity that have threatened the local population. The monitoring network is constituted by 5 short period and 5 broadband seismic stations, 4 DOAS permanent instruments, 4 tiltmeters, 2 permanent high resolution GPS, 4 digital cameras and 10 acoustic flow monitors. The correct interpretation of the different data acquired by this network allows a better understanding of the eruptive behavior of Tungurahua in order to provide early warning to the local population. Tungurahua changed its behavior from a continuously erupting volcano, as it was until 2008, to a sporadically erupting one, showing clear quiescence phases lasting from 40 to 184 days, and intense activity phases lasting from 15 to 70 days. Activity phases are characterized by Strombolian and Vulcanian eruptive styles, producing ash fallouts and in a few occasions pyroclastic flows. In terms of hazard to the local population, one of the goals of monitoring Tungurahura is to forecast the onset and evolution of eruptive phases. In particular the occurrence of large Vulcanian explosions which occur when the conduit is closed is a major issue. Since 2010 we focused our study on the relation between SO2 gas emissions, the seismic and acoustic energies of explosions and the tremor amplitudes. The first observation of comparing these different datasets is that the correlation between seismic and SO2 degassing is not straightforward, and actually the relation reflects the conditions at the vent: open or closed. The onset of eruptive phases in open conduit conditions can be identified which leads to an effective eruption forecasting. An example of this behavior is the eruptive phase between December 2009 and March 2010 when SO2 measurements increased 4 days before the amplitude of tremor and 9 days before the occurrence of the first explosions. Conversely, if the vent is closed at the beginning of a phase and no evident seismic precursors are observed forecasting is hardly possible. During an ongoing eruptive phase, the relation between these parameters allows to identify periods when the conduit is totally open as degassing may occur almost without generating any seismicity. Therefore the forecasting of escalating open conduit activity or a partial closing of the system is possible. Such a case was observed and forecasted on December 2011. In this work, we present observational evidence of these mechanisms which are used to identify possible patterns of evolution of the activity, contributing to a more effective volcanic hazard assessment.

Detonation Initiation of Heterogeneous Melt-Cast High Explosives

NASA Astrophysics Data System (ADS)

Chuzeville, Vincent; Baudin, Gerard; Lefrancois, Alexandre; Boulanger, Remi; Catoire, Laurent

2015-06-01

The melt-cast explosives' shock initiation mechanisms are less investigated than pressed and cast-cured ones. If the existence of hot-spots is widely recognized, their formation mechanism is not yet established. We study here two melt-cast explosives, NTO-TNT 60:40 and RDX-TNT 60:40 in order to establish a relation between the microstructure and the reaction rate using a two-phase model based on a ZND approach. Such a model requires the reaction rate, the equations of state of the unreacted phase and of the detonation products and an interaction model between the two phases to describe the reaction zone thermodynamics. The reaction rate law can be written in a factorized form including the number of initiation sites, the explosive's deflagration velocity around hot spots and a function depending on gas volume fraction produced by the deflagration front propagation. The deflagration velocity mainly depends on pressure and is determined from pop-plot tests using the hypothesis of the single curve build-up. This hypothesis has been verified for our two melt-cast explosives. The function depending on gas volume fraction is deduced from microstructural observations and from an analogy with the solid nucleation and growth theory. It has been established for deflagration fronts growing from grain's surface and a given initial grain size distribution. The model requires only a few parameters, calibrated thanks to an inversion method. A good agreement is obtained between experiments and numerical simulations.

Hidden explosives detector employing pulsed neutron and x-ray interrogation

DOEpatents

Schultz, F.J.; Caldwell, J.T.

1993-04-06

Methods and systems for the detection of small amounts of modern, highly-explosive nitrogen-based explosives, such as plastic explosives, hidden in airline baggage. Several techniques are employed either individually or combined in a hybrid system. One technique employed in combination is X-ray imaging. Another technique is interrogation with a pulsed neutron source in a two-phase mode of operation to image both nitrogen and oxygen densities. Another technique employed in combination is neutron interrogation to form a hydrogen density image or three-dimensional map. In addition, deliberately-placed neutron-absorbing materials can be detected.

Hidden explosives detector employing pulsed neutron and x-ray interrogation

DOEpatents

Schultz, Frederick J.; Caldwell, John T.

1993-01-01

Methods and systems for the detection of small amounts of modern, highly-explosive nitrogen-based explosives, such as plastic explosives, hidden in airline baggage. Several techniques are employed either individually or combined in a hybrid system. One technique employed in combination is X-ray imaging. Another technique is interrogation with a pulsed neutron source in a two-phase mode of operation to image both nitrogen and oxygen densities. Another technique employed in combination is neutron interrogation to form a hydrogen density image or three-dimensional map. In addition, deliberately-placed neutron-absorbing materials can be detected.

Structural transformations and properties of titanium-aluminum composite during heat treatment

NASA Astrophysics Data System (ADS)

Pervukhin, L. B.; Kryukov, D. B.; Krivenkov, A. O.; Chugunov, S. N.

2017-08-01

The link between the parameters of heat treatment of a layered titanium-aluminum composite material obtained by explosive welding with the formation of intermetallic compounds in it has been analyzed. The results of measurements of the microhardness of the composite and the thickness of the interlayer of the intermetallic phase obtained using different regimes of heat treatment have been discussed. Special attention has been paid to estimating the composition of the intermetallic phase in the composite prepared by explosive welding.

Defense Small Business Innovation Research Program (SBIR). Volume 1. Army Abstracts of Phase 1 Awards from FY 1988 SBIR Solicitation

DTIC Science & Technology

1989-05-01

CONSTRUCTION). CONCEPT ANALYSIS CORP 14789 KEEL ST PLYMOUTH, MI 48170 CONTRACT NUMBER: DAHO -88-C-0942 DR’S WALDEN & GLANCE TITLE: MISSILE GEOMETRY PACKAGE TOPIC...COUNTING STUDY CAN BE UTILIZED TO EVALUATE THE EFFECTIVENESS OF AN EXPLOSION MONITORING SYSTEM. E SMALL BUSINESS INNOVATION RESEARCH (SBIR) PROGRAM - PHASE... EXPLOSIVE OR GROUND PENETRATING MUNITIONS ARE TO BE EVALUATED. IN THAT CASE THE SYSTEM WILL BE ENHANCED WITH SEISMIC SENSORS. THE SEISMIC SIGNALS MAY

Theory Analysis of Wavelength Dependence of Laser-Induced Phase Explosion of Silicon

DTIC Science & Technology

2008-01-01

formed, they do not have enough time to grow up to the critical radius, thus explosive boiling will not occur. Therefore, little energy provided by the...When the laser irradiance is low, the laser pulse retains its original profile with little attenuation by the plasma. How- ever, when the laser... Fucke , J. Phys. F: Met. Phys. 8, L157 1978. 22V. P. Carey, Liquid-Vapor Phase Phenomena Hemisphere, Washington, FIG. 4. Temporal profiles of laser

Seismicity associated with quiescent-explosive transitions at dome forming eruptions: The July 2008 Vulcanian Explosion of Soufrière Hills Volcano, Montserrat

NASA Astrophysics Data System (ADS)

Rodgers, Mel; Smith, Patrick; Mather, Tamsin A.; Pyle, David M.

2017-04-01

During long-lived dome-forming eruptions volcanoes often transition between quiescent, effusive, and explosive behaviour. Soufrière Hills Volcano (SHV), Montserrat, has been erupting since 1995 and has repeatedly transitioned between these different phases of activity. At SHV many of the largest explosions have occurred either during periods of dome growth, or as major dome collapse events at the end of extrusion phases. However, on the 29th July 2008 a vulcanian explosion marked the transition from a quiescent phase (Pause 3) to explosion and then extrusion. This was one of the largest explosions by volume and the largest to occur outside a period of lava extrusion. The eruption was preceded by one of the most intense seismic swarms ever recorded at SHV. In this study we analysed precursory seismic data to investigate the subsurface volcanic processes that culminated in this eruption. We used spectral and multiplet analysis techniques, and applied a simple parameterization approach to relate monitoring observations (seismic, SO2, visual) to subsurface interpretations. These techniques would be available to most volcano observatories. Our study suggests that an initial VT swarm, coincident with ash-venting events, can be triggered by ascent of decoupled gas ahead of rising magma. A subsequent large LF swarm shows a coincident decrease in spectral content that we interpret as magma ascent through the upper conduit system. An ash-venting event on 27 July (a few hours before peak event rate) may have triggered rapid microlite growth. We observe an increase in the spectral content of the LF swarm that is concurrent with a decrease in event rates, suggesting pressurization of the magmatic system due to inhibited magmatic outgassing. Our results suggest that pressurization of the magmatic system may have occurred in the final 24 h before the vulcanian explosion. We also observe LP and Hybrid events within the same multiplet, suggesting that these events have very similar source processes and should be considered part of the same classification at SHV. Our study demonstrates the potential for using spectral and multiplet analysis to understand subsurface magmatic processes and for investigating the transition between quiescence and eruption.

Phase field model of the nanoscale evolution during the explosive crystallization phenomenon

NASA Astrophysics Data System (ADS)

Lombardo, S. F.; Boninelli, S.; Cristiano, F.; Deretzis, I.; Grimaldi, M. G.; Huet, K.; Napolitani, E.; La Magna, A.

2018-03-01

Explosive crystallization is a well known phenomenon occurring due to the thermodynamic instability of strongly under-cooled liquids, which is particularly relevant in pulsed laser annealing processes of amorphous semiconductor materials due to the globally exothermic amorphous-to-liquid-to-crystal transition pathway. In spite of the assessed understanding of this phenomenon, quantitative predictions of the material kinetics promoted by explosive crystallization are hardly achieved due to the lack of a consistent model able to simulate the concurrent kinetics of the amorphous-liquid and liquid-crystal interfaces. Here, we propose a multi-well phase-field model specifically suited for the simulation of explosive crystallization induced by pulsed laser irradiation in the nanosecond time scale. The numerical implementation of the model is robust despite the discontinuous jumps of the interface speed induced by the phenomenon. The predictive potential of the simulations is demonstrated by means of comparisons of the modelling predictions with experimental data in terms of in situ reflectivity measurements and ex-situ micro-structural and chemical characterization.

Solid-phase microextraction coupled to gas chromatography for the determination of 2,3-dimethyl-2,3-dinitrobutane as a marking agent for explosives.

PubMed

Li, Xiujuan; Zeng, Zhaorui; Zeng, Yi

2007-06-15

This paper investigates the detection of 2,3-dimethyl-2,3-dinitrobutane (DMNB), a marking agent in explosives, by gas chromatography (GC) with electron capture detection using solid-phase microextraction (SPME) as a sample preparation technique. The 25,27-dihydroxy-26,28-oxy (2',7'-dioxo-3',6'-diazaoctyl) oxy-p-tert-butylcalix[4]arene/hydroxy-terminated silicone oil coated fiber was highly sensitive to trap DMNB from ammonium nitrate matrix. The analysis was performed by extracting 2g of explosives for 30s at room temperature and then immediately introducing into the heated GC injector for 1min of thermal desorption. The method showed good linearity in the range from 0.01 to 1.0mug/g. The relative standard deviations for these extractions were <8%. The calculated limit of detection for DMNB (S/N=3) was 4.43x10(-4)mug/g, which illustrates that the proposed systems are suitable for explosive detection at trace level. This is the first report of an SPME-GC system shown to extract marking agent in explosives for subsequent detection in a simple, rapid, sensitive, and inexpensive manner.

Evaluation of Redoubt Volcano's sulfur dioxide emissions by the Ozone Monitoring Instrument

USGS Publications Warehouse

Lopez, Taryn; Carn, Simon A.; Werner, Cynthia A.; Fee, David; Kelly, Peter; Doukas, Michael P.; Pfeffer, Melissa; Webley, Peter; Cahill, Catherine F.; Schneider, David

2013-01-01

The 2009 eruption of Redoubt Volcano, Alaska, provided a rare opportunity to compare satellite measurements of sulfur dioxide (SO2) by the Ozone Monitoring Instrument (OMI) with airborne SO2 measurements by the Alaska Volcano Observatory (AVO). Herein we: (1) compare OMI and airborne SO2 column density values for Redoubt's tropospheric plume, (2) calculate daily SO2 masses from Mount Redoubt for the first three months of the eruption, (3) develop simple methods to convert daily measured SO2 masses into emission rates to allow satellite data to be directly integrated with the airborne SO2 emissions dataset, (4) calculate cumulative SO2 emissions from the eruption, and (5) evaluate OMI as a monitoring tool for high-latitude degassing volcanoes. A linear correlation (R2 ~ 0.75) is observed between OMI and airborne SO2 column densities. OMI daily SO2 masses for the sample period ranged from ~ 60.1 kt on 24 March to below detection limit, with an average daily SO2 mass of ~ 6.7 kt. The highest SO2 emissions were observed during the initial part of the explosive phase and the emissions exhibited an overall decreasing trend with time. OMI SO2 emission rates were derived using three methods and compared to airborne measurements. This comparison yields a linear correlation (R2 ~ 0.82) with OMI-derived emission rates consistently lower than airborne measurements. The comparison results suggest that OMI's detection limit for high latitude, springtime conditions varies from ~ 2000 to 4000 t/d. Cumulative SO2 masses calculated from daily OMI data for the sample period are estimated to range from 542 to 615 kt, with approximately half of this SO2 produced during the explosive phase of the eruption. These cumulative masses are similar in magnitude to those estimated for the 1989–90 Redoubt eruption. Strong correlations between daily OMI SO2 mass and both tephra mass and acoustic energy during the explosive phase of the eruption suggest that OMI data may be used to infer relative eruption size and explosivity. Further, when used in conjunction with complementary datasets, OMI daily SO2 masses may be used to help distinguish explosive from effusive activity and identify changes in lava extrusion rates. The results of this study suggest that OMI is a useful volcano monitoring tool to complement airborne measurements, capture explosive SO2 emissions, and provide high temporal resolution SO2 emissions data that can be used with interdisciplinary datasets to illuminate volcanic processes.

Explosive volcanism may not be an inevitable consequence of magma fragmentation.

PubMed

Gonnermann, Helge M; Manga, Michael

2003-11-27

The fragmentation of magma, containing abundant gas bubbles, is thought to be the defining characteristic of explosive eruptions. When viscous stresses associated with the growth of bubbles and the flow of the ascending magma exceed the strength of the melt, the magma breaks into disconnected fragments suspended within an expanding gas phase. Although repeated effusive and explosive eruptions for individual volcanoes are common, the dynamics governing the transition between explosive and effusive eruptions remain unclear. Magmas for both types of eruptions originate from sources with similar volatile content, yet effusive lavas erupt considerably more degassed than their explosive counterparts. One mechanism for degassing during magma ascent, consistent with observations, is the generation of intermittent permeable fracture networks generated by non-explosive fragmentation near the conduit walls. Here we show that such fragmentation can occur by viscous shear in both effusive and explosive eruptions. Moreover, we suggest that such fragmentation may be important for magma degassing and the inhibition of explosive behaviour. This implies that, contrary to conventional views, explosive volcanism is not an inevitable consequence of magma fragmentation.

Explosion-induced stress changes estimated from vibrating-wire stressmeter measurements near the Mighty Epic event, Nevada Test Site

USGS Publications Warehouse

Ellis, William L.; Kibler, J.D.

1983-01-01

Explosion-induced compressive stress increases near an underground nuclear explosion are believed to contribute significantly to the containment of high-pressure gases within the explosion-produced cavity. These induced compressive stresses are predicted by computer calculations, but have never been adequately confirmed by field measurements, owing primarily to the unique difficulties of obtaining such field data. Vibrating-wire stressmeter measurements made near the Mighty Epic nuclear detonation, however, qualitatively indicate that within 150 meters of the working point, permanent compressive stress increases of several megapascals were present 15 weeks after the event. Additionally, stress-change magnitudes interpreted from the stressmeter data between the 75- and 260-meter range from the working point compare favorably with calculational predictions of the stress changes believed to be present shortly after detonation of the event. The measurements and calculations differ, however, with regard to the pattern of stress change radial and transverse to the explosion source. For the range of the field measurements from the working point, computer models predict the largest compressive-stress increase to be radial to the explosion source, while the field data indicate the transverse component of. stress change to be the most compressive. The significance of time-dependent modification of the initial explosion-induced stress distribution is, however, uncertain with regard to the comparison of the field measurements and theoretical predictions.

Joint seismic-infrasonic processing of recordings from a repeating source of atmospheric explosions.

PubMed

Gibbons, Steven J; Ringdal, Frode; Kvaerna, Tormod

2007-11-01

A database has been established of seismic and infrasonic recordings from more than 100 well-constrained surface explosions, conducted by the Finnish military to destroy old ammunition. The recorded seismic signals are essentially identical and indicate that the variation in source location and magnitude is negligible. In contrast, the infrasonic arrivals on both seismic and infrasound sensors exhibit significant variation both with regard to the number of detected phases, phase travel times, and phase amplitudes, which would be attributable to atmospheric factors. This data set provides an excellent database for studies in sound propagation, infrasound array detection, and direction estimation.

Physical structure changes of solid medium by steam explosion sterilization.

PubMed

Zhao, Zhi-Min; Wang, Lan; Chen, Hong-Zhang

2016-03-01

Physical structure changes of solid medium were investigated to reveal effects of steam explosion sterilization on solid-state fermentation (SSF). Results indicated that steam explosion changed the structure of solid medium at both molecular and three-dimensional structural levels, which exposed hydrophilic groups and enlarged pores and cavities. It was interesting to find that pores where capillary water located were the active sites for SSF, due to the close relationship among capillary water relaxation time, specific surface area and fermentation performance. Therefore, steam explosion sterilization increased the effective contact area for microbial cells on solid medium, which contributed to improving SSF performance. Combined with the previous research, mechanisms of SSF improvement by steam explosion sterilization contained both chemical and physical effects. Copyright © 2015 Elsevier Ltd. All rights reserved.

Identification of Explosives from Porous Materials: Applications Using Reverse Phase High Performance Liquid Chromatography and Gas Chromatography

DOE Office of Scientific and Technical Information (OSTI.GOV)

C.J. Miller; G. Elias; N.C. Schmitt

2010-06-01

High performance liquid chromatography and gas chromatography techniques are well documented and widely used for the detection of trace explosives from organic solvents. These techniques were modified to specifically identify and quantify explosives extracted from various materials taken from people who had recently handled explosives. Documented techniques were modified to specifically detect and quantify RDX, TNT, and PETN from denim, colored flannel, vinyl, and canvas extracted in methanol using no sample cleanup prior to analysis. The methanol extracts were injected directly into several different column types and analyzed by HPLC-UV and/or GC-ECD. This paper describes general screening methods that weremore » used to determine the presence of explosives in unknown samples and techniques that have been optimized for quantification of each explosive from the substrate extracts.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Urtiew, P A; Forbes, J W; Tarver, C M

LX-04 is a widely used HMX-based plastic bonded explosive, which contains 85 weight % HMX and 15 weight % Viton binder. The sensitivity of LX-04 to a single stimulus such as heat, impact, and shock has been previously studied. However, hazard scenarios can involve multiple stimuli, such as heating to temperatures close to thermal explosion conditions followed by fragment impact, producing a shock in the hot explosive. The sensitivity of HMX at elevated temperatures is further complicated by the beta to delta solid-state phase transition, which occurs at approximately 165 C. This paper presents the results of shock initiation experimentsmore » conducted with LX-04 preheated to 190 C, as well as density measurements and small scale safety test results of the {delta} phase HMX at room temperature. This work shows that LX-04 at 190 C is more shock sensitive than LX-04 at 150 C or 170 C due to the volume increase during the {beta} to {delta} solid phase transition, which creates more hot spots, and the faster growth of reaction during shock compression.« less

Tephra from the 1979 soufriere explosive eruption.

PubMed

Sigurdsson, H

1982-06-04

The explosive phase of the 1979 Soufriere eruption produced 37.5 x 10(6) cubic meters (dense-rock equivalent) of tephra, consisting of about 40 percent juvenile basaltic andesite and 60 percent of a nonjuvenile component derived from the fragmentation of the 1971-1972 lava island during phreatomagmatic explosions. The unusually fine grain size, poor sorting, and bimodality of the land deposit are attributed to particle aggregation and the formation of accretionary lapilli in a wet eruption column.

Dense Seismic Recordings of Two Surface-Detonated Chemical Explosions

NASA Astrophysics Data System (ADS)

Koper, K. D.; Hale, J. M.; Burlacu, R.; Goddard, K. J.; Trow, A.; Linville, L. M.; Stein, J. R.; Drobeck, D.; Leidig, M.

2015-12-01

In the summer of 2015 two controlled chemical explosions were carried out near Dugway, Utah. The 2 June 2015 explosion consisted of 30,000 lbs of ammonium nitrate fuel oil (ANFO) and the 22 July 2015 explosion consisted of 60,000 lbs of ANFO. The explosion centroids were 1-2 m above the Earth's surface and both created significant craters in the soft desert alluvium. To better understand the seismic source associated with surface explosions, we deployed an array of wireless, three-component, short-period (5 Hz corner frequency) seismometers for several days around each shot. For the first explosion, 46 receivers were deployed in a "lollipop" geometry that had a sparse ring at a radius of 1 km, and a dense stem with 100 m spacing for distances of 0.5-4.5 km. For the second explosion, 48 receivers were deployed similarly, but with a dense ring spaced in azimuthal increments of 10 degrees at a distance of 1 km, and a sparse stem (~500 m spacing) that extended to a distance of nearly 6 km. A rich variety of phases were recorded including direct P waves, refracted and reflected P waves, nearly monochromatic air-coupled Rayleigh waves, normally dispersed fundamental mode Rayleigh waves (Rg), primary airblast arrivals, some secondary airblast arrivals, and possibly tertiary airblast arrivals. There is also evidence of converted S waves on the radial components and possibly direct S energy on the radial and transverse components, although the transverse energy does not always possess a simple, coherent move-out with distance, implying that it might have a scattering origin. To aid in the phase identification, especially of the apparent SH and Love energy, we are currently performing tau-p, f-k, and particle motion analysis.

Tunable generation and adsorption of energetic compounds in the vapor phase at trace levels: a tool for testing and developing sensitive and selective substrates for explosive detection.

PubMed

Bonnot, Karine; Bernhardt, Pierre; Hassler, Dominique; Baras, Christian; Comet, Marc; Keller, Valérie; Spitzer, Denis

2010-04-15

Among various methods for landmine detection, as well as soil and water pollution monitoring, the detection of explosive compounds in air is becoming an important and inevitable challenge for homeland security applications, due to the threatening increase in terrorist explosive bombs used against civil populations. However, in the last case, there is a crucial need for the detection of vapor phase traces or subtraces (in the ppt range or even lower). A novel and innovative generator for explosive trace vapors was designed and developed. It allowed the generation of theoretical concentrations as low as 0.24 ppq for hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in air according to Clapeyron equations. The accurate generation of explosive concentrations at subppt levels was verified for RDX and 2,4,6-trinitrotoluene (TNT) using a gas chromatograph coupled to an electron capture detector (GC-ECD). First, sensing material experiments were conducted on a nanostructured tungsten oxide. The sensing efficiency of this material determined as its adsorption capacity toward 54 ppb RDX was calculated to be five times higher than the sensing efficiency of a 54 ppb TNT vapor. The material sensing efficiency showed no dependence on the mass of material used. The results showed that the device allowed the calibration and discrimination between materials for highly sensitive and accurate sensing detection in air of low vapor pressure explosives such as TNT or RDX at subppb levels. The designed device and method showed promising features for nanosensing applications in the field of ultratrace explosive detection. The current perspectives are to decrease the testing scale and the detection levels to ppt or subppt concentration of explosives in air.

Experimental evaluation of LPG tank explosion hazards.

PubMed

Stawczyk, Jan

2003-01-31

Liquefied-pressure gases (LPG) are transported and stored in the liquid phase in closed tanks under sufficiently high pressure. In the case of an accident, an abrupt tank unsealing may release enormous quantity of evaporating gas and energy that has a destructive effect on the tank and its surroundings. In this paper, experiments with explosions of small LPG tanks are described. The data acquisition equipment applied in the tests provided a chance to learn dynamics of the process and determine hazard factors. The tests enabled a determination of temperature and pressure at which tanks containing LPG disrupt. The results enable a reconstruction of consecutive phases of the explosion and identification of hazards resulting from damage of the tanks. An explanation of the tank unsealing process with fluid parameters above critical point is given.

Influence of Small Change of Porosity on Shock Initiation of an HMX/TATB/Viton Explosive and Ignition and Growth Modeling

NASA Astrophysics Data System (ADS)

Liu, Yan; Hussain, Tariq; Huang, Fenglei; Duan, Zhuoping

2016-07-01

All solid explosives in practical use are more or less porous. Although it is known that the change in porosity affects the shock sensitivity of solid explosives, the effect of small changes in porosity on the sensitivity needs to be determined for safe and efficient use of explosive materials. In this study, the influence of a small change in porosity on shock initiation and the subsequent detonation growth process of a plastic-bonded explosive PBXC03, composed of 87% cyclotetramethylene-tetranitramine (HMX), 7% triaminotrinitrobenzene (TATB), and 6% Viton by weight, are investigated by shock to detonation transition experiments. Two explosive formulations of PBXC03 having the same initial grain sizes pressed to 98 and 99% of theoretical mass density (1.873 g/cm3) respectively are tested using the in situ manganin piezoresistive pressure gauge technique. Numerical modeling of the experiments is performed using an ignition and growth reactive flow model. Reasonable agreement with the experimental results is obtained by increasing the growth term coefficient in the Lee-Tarver ignition and growth model with porosity. Combining the experimental and simulation results shows that the shock sensitivity increases with porosity for PBXC03 having the same explosive initial grain sizes for the pressures (about 3.1 GPa) applied in the experiments.

Prediction of ground motion and dynamic stress change in Baekdusan (Changbaishan) volcano caused by a North Korean nuclear explosion.

PubMed

Hong, Tae-Kyung; Choi, Eunseo; Park, Seongjun; Shin, Jin Soo

2016-02-17

Strong ground motions induce large dynamic stress changes that may disturb the magma chamber of a volcano, thus accelerating the volcanic activity. An underground nuclear explosion test near an active volcano constitutes a direct treat to the volcano. This study examined the dynamic stress changes of the magma chamber of Baekdusan (Changbaishan) that can be induced by hypothetical North Korean nuclear explosions. Seismic waveforms for hypothetical underground nuclear explosions at North Korean test site were calculated by using an empirical Green's function approach based on a source-spectral model of a nuclear explosion; such a technique is efficient for regions containing poorly constrained velocity structures. The peak ground motions around the volcano were estimated from empirical strong-motion attenuation curves. A hypothetical M7.0 North Korean underground nuclear explosion may produce peak ground accelerations of 0.1684 m/s(2) in the horizontal direction and 0.0917 m/s(2) in the vertical direction around the volcano, inducing peak dynamic stress change of 67 kPa on the volcano surface and ~120 kPa in the spherical magma chamber. North Korean underground nuclear explosions with magnitudes of 5.0-7.6 may induce overpressure in the magma chamber of several tens to hundreds of kilopascals.

Gas chromatographic detection of some nitro explosive compounds in soil samples after solid-phase microextraction with carbon ceramic copper nanoparticle fibers.

PubMed

Farhadi, Khalil; Bochani, Shayesteh; Hatami, Mehdi; Molaei, Rahim; Pirkharrati, Hossein

2014-07-01

In this research, a new solid-phase microextraction fiber based on carbon ceramic composites with copper nanoparticles followed by gas chromatography with flame ionization detection was applied for the extraction and determination of some nitro explosive compounds in soil samples. The proposed method provides an overview of trends related to synthesis of solid-phase microextraction sorbents and their applications in preconcentration and determination of nitro explosives. The sorbents were prepared by mixing of copper nanoparticles with a ceramic composite produced by mixture of methyltrimethoxysilane, graphite, methanol, and hydrochloric acid. The prepared sorbents were coated on copper wires by dip-coating method. The prepared nanocomposites were evaluated statistically and provided better limits of detection than the pure carbon ceramic. The limit of detection of the proposed method was 0.6 μg/g with a linear response over the concentration range of 2-160 μg/g and square of correlation coefficient >0.992. The new proposed fiber has been demonstrated to be a suitable, inexpensive, and sensitive candidate for extraction of nitro explosive compounds in contaminated soil samples. The constructed fiber can be used more than 100 times without the need for surface generation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of high shock pressures and pore morphology on hot spot mechanisms in HMX

NASA Astrophysics Data System (ADS)

Springer, H. K.; Tarver, C. M.; Bastea, S.

2017-01-01

The shock initiation and detonation behavior of heterogeneous solid explosives is governed by its microstructure and reactive properties. New additive manufacturing techniques offer unprecedented control of explosive microstructures previously impossible, enabling us to develop novel explosives with tailored shock sensitivity and detonation properties. Since microstructure-performance relationships are not well established for explosives, there is little material design guidance for these manufacturing techniques. In this study, we explore the effects of high shock pressures (15-38 GPa) with long shock durations and different pore morphologies on hot spot mechanisms in HMX. HMX is chosen as the model material because we have experimental data on many of the chemical-thermal-mechanical properties required for pore collapse simulations. Our simulations are performed using the multi-physics arbitrary Lagrangian Eulerian finite element hydrocode, ALE3D, with Cheetah-based models for the unreacted and the product equation-of-states. We use a temperature-dependent specific heat with the unreacted equation-of-state and a temperature-dependent viscosity model to ensure accurate shock temperatures for subsequent chemistry. The Lindemann Law model is used for shock melting in HMX. In contrast to previous pore collapse studies at lower shock pressures (≤10 GPa) in HMX and shorter post-collapse burning times, our calculations show that shock melting occurs above 15 GPa due to higher bulk heating and a prominent elongated ("jet-like") hot spot region forms at later times. The combination of the elongated, post-collapse hot spot region and the higher bulk heating with increasing pressure dramatically increases the growth rate of reaction. Our calculations show that the reaction rate, dF/dt, increases with increasing shock pressure. We decompose the reaction rate into ignition ((dF/dt)ig) and growth ((dF/dt)gr) phases to better analyze our results. We define the ignition phase to primarily include pore collapse and growth phase to primarily include post-collapse grain burning. We are able to track late-time, post-collapse burning due to the unique loading conditions employed in these calculations. We find that (dF/dt)gr > (dF/dt)ig for all pressures considered. (dF/dt)gr changes more significantly from 25 to 38 GPa (from 0.05/µs to >10-100/µs) than from 15 to 25 GPa (from 0.005/µs to 0.05/µs). There is a three order-of-magnitude difference in the reaction from 15 to 38 GPa just after pore collapse. This is qualitatively consistent with fitting the (macroscopic) Ignition and Growth model to high pressure shock initiation data, where much larger reaction fractions are needed to capture the early stages of reaction. Calculated burn rates demonstrate better agreement with data at intermediate times in the growth phase for 15 to 25 GPa and late times for 30 GPa then at any time in the growth phase for 38 GPa. Our calculations are much higher than burn rate data at the earliest times in the growth phase for all pressures, which may reflect the higher localized pressures and temperatures just after pore collapse in the ignition phase. Our calculations with spherical, conical, and elliptical pores show that the influence of morphology on reaction rate is pressure dependent and the most influential pore shapes at lower pressures aren't the same at higher pressures in the regime studied. Altogether these studies provide the basis for developing microstructure-aware models that can be used to design new explosives with optimal performance-safety characteristics. Such models can be used to guide additive manufacturing of explosives and fully exploit their disruptive nature.

Diagnosing development. II - A study of rapid cyclone development using analyzed data fields

NASA Technical Reports Server (NTRS)

Smith, Phillip; Lupo, Anthony; Zwack, Peter

1991-01-01

A diagnosis is presented of the explosive development phase of a cyclone that occurred over the southeastern U.S. during the 24 hour period 1200 GMT January 20 to 1200 GMT January 21, 1979. The Zwack-Osossi development equation is extended to incorporate geostrophic and ageostrophic forcing of the basic development parameter, geostrophic vorticity tendency. This equation yields reasonable comparability with observed geostrophic vorticity changes and shows positive vorticity advection, latent heat release and thermal advection to be the primary development mechanisms.

Effect of Heat Treatment on the Structure and Properties of Explosion Welded Bimetal Kh20N80 + AD1

NASA Astrophysics Data System (ADS)

Shmorgun, V. G.; Arisova, V. N.; Slautin, O. V.; Taube, A. O.; Bakuntseva, V. M.

2017-05-01

Results of a study of the effect of heat treatment on the microhardness, structure and phase composition of diffusion zone in explosion-welded `refractory nickel alloy Kh20N80 + aluminum alloy AD1' bimetal are presented.

[Aging explosive detection using terahertz time-domain spectroscopy].

PubMed

Meng, Kun; Li, Ze-ren; Liu, Qiao

2011-05-01

Detecting the aging situation of stock explosive is essentially meaningful to the research on the capability, security and stability of explosive. Existing aging explosive detection techniques, such as scan microscope technique, Fourier transfer infrared spectrum technique, gas chromatogram mass spectrum technique and so on, are either not able to differentiate whether the explosive is aging or not, or not able to image the structure change of the molecule. In the present paper, using the density functional theory (DFT), the absorb spectrum changes after the explosive aging were calculated, from which we can clearly find the difference of spectrum between explosive molecule and aging ones in the terahertz band. The terahertz time-domain spectrum (THz-TDS) system as well as its frequency spectrum resolution and measured range are analyzed. Combined with the existing experimental results and the essential characters of the terahertz wave, the application of THz-TDS technique to the detection of aging explosive was demonstrated from the aspects of feasibility, veracity and practicability. On the base of that, the authors advance the new method of aging explosive detection using the terahertz time-domain spectrum technique.

Vacancy-induced initial decomposition of condensed phase NTO via bimolecular hydrogen transfer mechanisms at high pressure: a DFT-D study.

PubMed

Liu, Zhichao; Wu, Qiong; Zhu, Weihua; Xiao, Heming

2015-04-28

Density functional theory with dispersion-correction (DFT-D) was employed to study the effects of vacancy and pressure on the structure and initial decomposition of crystalline 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (β-NTO), a high-energy insensitive explosive. A comparative analysis of the chemical behaviors of NTO in the ideal bulk crystal and vacancy-containing crystals under applied hydrostatic compression was considered. Our calculated formation energy, vacancy interaction energy, electron density difference, and frontier orbitals reveal that the stability of NTO can be effectively manipulated by changing the molecular environment. Bimolecular hydrogen transfer is suggested to be a potential initial chemical reaction in the vacancy-containing NTO solid at 50 GPa, which is prior to the C-NO2 bond dissociation as its initiation decomposition in the gas phase. The vacancy defects introduced into the ideal bulk NTO crystal can produce a localized site, where the initiation decomposition is preferentially accelerated and then promotes further decompositions. Our results may shed some light on the influence of the molecular environments on the initial pathways in molecular explosives.

Dissolution and sorption of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and 2,4,6-trinitrotoluene (TNT) residues from detonated mineral surfaces.

PubMed

Jaramillo, Ashley M; Douglas, Thomas A; Walsh, Marianne E; Trainor, Thomas P

2011-08-01

Composition B (Comp B) is a commonly used military formulation composed of the toxic explosive compounds 2,4,6-trinitrotoluene (TNT), and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Numerous studies of the temporal fate of explosive compounds in soils, surface water and laboratory batch reactors have been conducted. However, most of these investigations relied on the application of explosive compounds to the media via aqueous addition and thus these studies do not provide information on the real world loading of explosive residues during detonation events. To address this we investigated the dissolution and sorption of TNT and RDX from Comp B residues loaded to pure mineral phases through controlled detonation. Mineral phases included nontronite, vermiculite, biotite and Ottawa sand (quartz with minor calcite). High Performance Liquid Chromatography and Attenuated Total Reflectance Fourier Transform Infrared spectroscopy were used to investigate the dissolution and sorption of TNT and RDX residues loaded onto the mineral surfaces. Detonation resulted in heterogeneous loading of TNT and RDX onto the mineral surfaces. Explosive compound residues dissolved rapidly (within 9 h) in all samples but maximum concentrations for TNT and RDX were not consistent over time due to precipitation from solution, sorption onto mineral surfaces, and/or chemical reactions between explosive compounds and mineral surfaces. We provide a conceptual model of the physical and chemical processes governing the fate of explosive compound residues in soil minerals controlled by sorption-desorption processes. Published by Elsevier Ltd.

Structure of the disturbed region of the atmosphere after the nuclear explosion in Hiroshima

NASA Astrophysics Data System (ADS)

Shcherbin, M. D.; Pavlyukov, K. V.; Salo, A. A.; Pertsev, S. F.; Rikunov, A. V.

2013-09-01

An attempt is undertaken to describe the development of the disturbed region of the atmosphere caused by the nuclear explosion over Hiroshima on August 6, 1945. Numerical simulation of the phenomenon is performed using the dynamic equations for a nonconducting inviscid gas taking into account the combustion of urban buildings, phase changes of water, electrification of ice particles, and removal of soot particles. The results of the numerical calculation of the development of the disturbed region indicate heavy rainfall, the formation of a storm cloud with lightning discharges, removal of soot particles, and the formation of vertical vortices. The temporal sequence of these meteorological phenomena is consistent with the data of observations. Because of the assumptions and approximations used in solving the problem, the results are of qualitative nature. Refinement of the results can be obtained by a more detailed study of the approximate initial and boundary conditions of the problem.

Noncontact detection of homemade explosive constituents via photodissociation followed by laser-induced fluorescence.

PubMed

Wynn, C M; Palmacci, S; Kunz, R R; Rothschild, M

2010-03-15

Noncontact detection of the homemade explosive constituents urea nitrate, nitromethane and ammonium nitrate is achieved using photodissociation followed by laser-induced fluorescence (PD-LIF). Our technique utilizes a single ultraviolet laser pulse (approximately 7 ns) to vaporize and photodissociate the condensed-phase materials, and then to detect the resulting vibrationally-excited NO fragments via laser-induced fluorescence. PD-LIF excitation and emission spectra indicate the creation of NO in vibrationally-excited states with significant rotational energy, useful for low-background detection of the parent compound. The results for homemade explosives are compared to one another and 2,6-dinitrotoluene, a component present in many military explosives.

The application of the high-speed photography in the experiments of boiling liquid expanding vapor explosions

NASA Astrophysics Data System (ADS)

Chen, Sining; Sun, Jinhua; Chen, Dongliang

2007-01-01

The liquefied-petroleum gas tank in some failure situations may release its contents, and then a series of hazards with different degrees of severity may occur. The most dangerous accident is the boiling liquid expanding vapor explosion (BLEVE). In this paper, a small-scale experiment was established to experimentally investigate the possible processes that could lead to a BLEVE. As there is some danger in using LPG in the experiments, water was used as the test fluid. The change of pressure and temperature was measured during the experiment. The ejection of the vapor and the sequent two-phase flow were recorded by a high-speed video camera. It was observed that two pressure peaks result after the pressure is released. The vapor was first ejected at a high speed; there was a sudden pressure drop which made the liquid superheated. The superheated liquid then boiled violently causing the liquid contents to swell, and also, the vapor pressure in the tank increased rapidly. The second pressure peak was possibly due to the swell of this two-phase flow which was likely to violently impact the wall of the tank with high speed. The whole evolution of the two-phase flow was recorded through photos captured by the high-speed video camera, and the "two step" BLEVE process was confirmed.

New developments of the CARTE thermochemical code: A two-phase equation of state for nanocarbons

NASA Astrophysics Data System (ADS)

Dubois, Vincent; Pineau, Nicolas

2016-01-01

We developed a new equation of state (EOS) for nanocarbons in the thermodynamic range of high explosives detonation products (up to 50 GPa and 4000 K). This EOS was fitted to an extensive database of thermodynamic properties computed by molecular dynamics simulations of nanodiamonds and nano-onions with the LCBOPII potential. We reproduced the detonation properties of a variety of high explosives with the CARTE thermochemical code, including carbon-poor and carbon-rich explosives, with excellent accuracy.

The classification of explosion-proof protected induction motor into adequate temperature and efficiency class

NASA Astrophysics Data System (ADS)

Brinovar, Iztok; Srpčič, Gregor; Seme, Sebastijan; Štumberger, Bojan; Hadžiselimović, Miralem

2017-07-01

This article deals with the classification of explosion-proof protected induction motors, which are used in hazardous areas, into adequate temperature and efficiency class. Hazardous areas are defined as locations with a potentially explosive atmosphere where explosion may occur due to present of flammable gasses, liquids or combustible dusts (industrial plants, mines, etc.). Electric motors and electrical equipment used in such locations must be specially designed and tested to prevent electrical initiation of explosion due to high surface temperature and arcing contacts. This article presents the basic tests of three-phase explosion-proof protected induction motor with special emphasis on the measuring system and temperature rise test. All the measurements were performed with high-accuracy instrumentation and accessory equipment and carried out at the Institute of energy technology in the Electric machines and drives laboratory and Applied electrical engineering laboratory.

Trace Explosives Signatures from World War II Unexploded Undersea Ordnance

NASA Technical Reports Server (NTRS)

Darrach, M. R.; Chutjian, A.; Plett, G. A.

1998-01-01

Trace explosives signatures of TNT and DNT have been extracted from multiple sediment samples adjacent to unexploded undersea ordnance at Halifax Harbor, Canada. The ordnance was hurled into the harbor during a massive explosion some 50 years earlier, in 1945 after World War II had ended. Laboratory sediment extractions were made using the solid-phase microextraction (SPME) method in seawater and detection using the Reversal Electron Attachment Detection (READ) technique and, in the case of DNT, a commercial gas chromatograph/mass spectrometer (GC/MS). Results show that, after more than 50 years in the environment, ordnance that appeared to be physically intact gave good explosives signatures at the parts per billion level, whereas ordnance that had been cracked open during the explosion gave no signatures at the 10 parts per trillion sensitivity level. These measurements appear to provide the first reported data of explosives signatures from undersea unexploded ordnance.

Monitoring/Verification Using DMS: TATP Example

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kevin Kyle; Stephan Weeks

Field-rugged and field-programmable differential mobility spectrometry (DMS) networks provide highly selective, universal monitoring of vapors and aerosols at detectable levels from persons or areas involved with illicit chemical/biological/explosives (CBE) production. CBE sensor motes used in conjunction with automated fast gas chromatography with DMS detection (GC/DMS) verification instrumentation integrated into situational operationsmanagement systems can be readily deployed and optimized for changing application scenarios. The feasibility of developing selective DMS motes for a “smart dust” sampling approach with guided, highly selective, fast GC/DMS verification analysis is a compelling approach to minimize or prevent the illegal use of explosives or chemical and biologicalmore » materials. DMS is currently one of the foremost emerging technologies for field separation and detection of gas-phase chemical species. This is due to trace-level detection limits, high selectivity, and small size. GC is the leading analytical method for the separation of chemical species in complex mixtures. Low-thermal-mass GC columns have led to compact, low-power field systems capable of complete analyses in 15–300 seconds. A collaborative effort optimized a handheld, fast GC/DMS, equipped with a non-rad ionization source, for peroxide-based explosive measurements.« less

Formation of intermetallics at the interface of explosively welded Ni-Al multilayered composites during annealing

NASA Astrophysics Data System (ADS)

Ogneva, T. S.; Lazurenko, D. V.; Bataev, I. A.; Mali, V. I.; Esikov, M. A.; Bataev, A. A.

2016-04-01

The Ni-Al multilayer composite was fabricated using explosive welding. The zones of mixing of Ni and Al are observed at the composite interfaces after the welding. The composition of these zones is inhomogeneous. Continuous homogeneous intermetallic layers are formed at the interface after heat treatment at 620 °C during 5 h These intermetallic layers consist of NiAl3 and Ni2Al3 phases. The presence of mixed zones significantly accelerates the growth rate of intermetallic phases at the initial stages of heating.

Planar blast scaling with condensed-phase explosives in a shock tube

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jackson, Scott L

2011-01-25

Blast waves are strong shock waves that result from large power density deposition into a fluid. The rapid energy release of high-explosive (HE) detonation provides sufficiently high power density for blast wave generation. Often it is desirable to quantify the energy released by such an event and to determine that energy relative to other reference explosives to derive an explosive-equivalence value. In this study, we use condensed-phase explosives to drive a blast wave in a shock tube. The explosive material and quantity were varied to produce blast waves of differing strengths. Pressure transducers at varying lengths measured the post-shock pressure,more » shock-wave arrival time and sidewall impulse associated with each test. Blast-scaling concepts in a one-dimensional geometry were then used to both determine the energy release associated with each test and to verify the scaling of the shock position versus time, overpressure versus distance, and impulse. Most blast scaling measurements to-date have been performed in a three-dimensional geometry such as a blast arena. Testing in a three-dimensional geometry can be challenging, however, as spherical shock-wave symmetry is required for good measurements. Additionally, the spherical wave strength decays rapidly with distance and it can be necessary to utilize larger (several kg) quantities of explosive to prevent significant decay from occurring before an idealized blast wave has formed. Such a mode of testing can be expensive, require large quantities of explosive, and be limited by both atmospheric conditions (such as rain) and by noise complaints from the population density near the test arena. Testing is possible in more compact geometries, however. Non-planar blast waves can be formed into a quasi-planar shape by confining the shock diffraction with the walls of a shock tube. Regardless of the initial form, the wave shape will begin to approximate a planar front after successive wave reflections from the tube walls. Such a technique has previously been used to obtain blast scaling measurements in the planar geometry with gaseous explosives and the condensed-phase explosive nitroguanidine. Recently, there has been much interest in the blast characterization of various non-ideal high explosive (NIHE) materials. With non-ideals, the detonation reaction zone is significantly larger (up to several cm for ANFO) than more ideal explosives. Wave curvature, induced by charge-geometry, can significantly affect the energy release associated with NIHEs. To measure maximum NIHE energy release accurately, it is desirable to minimize any such curvature and, if possible, to overdrive the detonation shock to ensure completion of chemical reactions ahead of the sonic locus associated with the reaction zone. This is achieved in the current study through use of a powerful booster HE and a charge geometry consisting of short cylindrical lengths of NIHE initiated along the charge centerline.« less

Initial signatures of magnetic field and energetic particle fluxes at tail reconfiguration - Explosive growth phase

NASA Technical Reports Server (NTRS)

Ohtani, S.; Takahashi, K.; Zanetti, L. J.; Potemra, T. A.; Mcentire, R. W.; Iijima, T.

1992-01-01

The initial signatures of tail field reconfiguration observed in the near-earth magnetotail are examined using data obtained by the AMPTE/CCE magnetometer and the Medium Energy Particle Analyzer. It is found that the tail reconfiguration events could be classified as belonging to two types, Type I and Type II. In Type I events, a current disruption is immersed in a hot plasma region expanding from inward (earthward/equatorward) of the spacecraft; consequently, the spacecraft is immersed in a hot plasma region expanding from inward. The Type II reconfiguration event is characterized by a distinctive interval (explosive growth phase) just prior to the local commencement of tail phase.

SUPERLUMINOUS SUPERNOVA SN 2015bn IN THE NEBULAR PHASE: EVIDENCE FOR THE ENGINE-POWERED EXPLOSION OF A STRIPPED MASSIVE STAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nicholl, M.; Berger, E.; Blanchard, P. K.

We present nebular-phase imaging and spectroscopy for the hydrogen-poor superluminous supernova (SLSN) SN 2015bn, at redshift z = 0.1136, spanning +250–400 days after maximum light. The light curve exhibits a steepening in the decline rate from 1.4 mag (100 days){sup −1} to 1.7 mag (100 days){sup −1}, suggestive of a significant decrease in the opacity. This change is accompanied by a transition from a blue continuum superposed with photospheric absorption lines to a nebular spectrum dominated by emission lines of oxygen, calcium, and magnesium. There are no obvious signatures of circumstellar interaction or large {sup 56}Ni mass. We show thatmore » the spectrum at +400 days is virtually identical to a number of energetic SNe Ic such as SN 1997dq, SN 2012au, and SN 1998bw, indicating similar core conditions and strengthening the link between “hypernovae”/long gamma-ray bursts and SLSNe. A single explosion mechanism may unify these events that span absolute magnitudes of −22 < M {sub B} < −17. Both the light curve and spectrum of SN 2015bn are consistent with an engine-driven explosion ejecting 7–30 M {sub ⊙} of oxygen-dominated ejecta (for reasonable choices in temperature and opacity). A strong and relatively narrow O i λ 7774 line, seen in a number of these energetic events but not in normal supernovae, may point to an inner shell that is the signature of a central engine.« less

Rootless tephra stratigraphy and emplacement processes

NASA Astrophysics Data System (ADS)

Hamilton, Christopher W.; Fitch, Erin P.; Fagents, Sarah A.; Thordarson, Thorvaldur

2017-01-01

Volcanic rootless cones are the products of thermohydraulic explosions involving rapid heat transfer from active lava (fuel) to external sources of water (coolant). Rootless eruptions are attributed to molten fuel-coolant interactions (MFCIs), but previous studies have not performed systematic investigations of rootless tephrostratigraphy and grain-size distributions to establish a baseline for evaluating relationships between environmental factors, MFCI efficiency, fragmentation, and patterns of tephra dispersal. This study examines a 13.55-m-thick vertical section through an archetypal rootless tephra sequence, which includes a rhythmic succession of 28 bed pairs. Each bed pair is interpreted to be the result of a discrete explosion cycle, with fine-grained basal material emplaced dominantly as tephra fall during an energetic opening phase, followed by the deposition of coarser-grained material mainly as ballistic ejecta during a weaker coda phase. Nine additional layers are interleaved throughout the stratigraphy and are interpreted to be dilute pyroclastic density current (PDC) deposits. Overall, the stratigraphy divides into four units: unit 1 contains the largest number of sediment-rich PDC deposits, units 2 and 3 are dominated by a rhythmic succession of bed pairs, and unit 4 includes welded layers. This pattern is consistent with a general decrease in MFCI efficiency due to the depletion of locally available coolant (i.e., groundwater or wet sediments). Changing conduit/vent geometries, mixing conditions, coolant and melt temperatures, and/or coolant impurities may also have affected MFCI efficiency, but the rhythmic nature of the bed pairs implies a periodic explosion process, which can be explained by temporary increases in the water-to-lava mass ratio during cycles of groundwater recharge.

Prediction of ground motion and dynamic stress change in Baekdusan (Changbaishan) volcano caused by a North Korean nuclear explosion

PubMed Central

Hong, Tae-Kyung; Choi, Eunseo; Park, Seongjun; Shin, Jin Soo

2016-01-01

Strong ground motions induce large dynamic stress changes that may disturb the magma chamber of a volcano, thus accelerating the volcanic activity. An underground nuclear explosion test near an active volcano constitutes a direct treat to the volcano. This study examined the dynamic stress changes of the magma chamber of Baekdusan (Changbaishan) that can be induced by hypothetical North Korean nuclear explosions. Seismic waveforms for hypothetical underground nuclear explosions at North Korean test site were calculated by using an empirical Green’s function approach based on a source-spectral model of a nuclear explosion; such a technique is efficient for regions containing poorly constrained velocity structures. The peak ground motions around the volcano were estimated from empirical strong-motion attenuation curves. A hypothetical M7.0 North Korean underground nuclear explosion may produce peak ground accelerations of 0.1684 m/s2 in the horizontal direction and 0.0917 m/s2 in the vertical direction around the volcano, inducing peak dynamic stress change of 67 kPa on the volcano surface and ~120 kPa in the spherical magma chamber. North Korean underground nuclear explosions with magnitudes of 5.0–7.6 may induce overpressure in the magma chamber of several tens to hundreds of kilopascals. PMID:26884136

The fluid dynamics of microjet explosions caused by extremely intense X-ray pulses

NASA Astrophysics Data System (ADS)

Stan, Claudiu; Laksmono, Hartawan; Sierra, Raymond; Milathianaki, Despina; Koglin, Jason; Messerschmidt, Marc; Williams, Garth; Demirci, Hasan; Botha, Sabine; Nass, Karol; Stone, Howard; Schlichting, Ilme; Shoeman, Robert; Boutet, Sebastien

2014-11-01

Femtosecond X-ray scattering experiments at free-electron laser facilities typically requires liquid jet delivery methods to bring samples to the region of interaction with X-rays. We have imaged optically the damage process in water microjets due to intense hard X-ray pulses at the Linac Coherent Light Source (LCLS), using time-resolved imaging techniques to record movies at rates up to half a billion frames per second. For pulse energies larger than a few percent of the maximum pulse energy available at LCLS, the X-rays deposit energies much larger than the latent heat of vaporization in water, and induce a phase explosion that opens a gap in the jet. The LCLS pulses last a few tens of femtoseconds, but the full evolution of the broken jet is orders of magnitude slower - typically in the microsecond range - due to complex fluid dynamics processes triggered by the phase explosion. Although the explosion results in a complex sequence of phenomena, they lead to an approximately self-similar flow of the liquid in the jet.

SN 2009ip: CONSTRAINING THE LATEST EXPLOSION PROPERTIES BY ITS LATE-PHASE LIGHT CURVE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moriya, Takashi J., E-mail: moriyatk@astro.uni-bonn.de

We constrain the explosion and circumstellar properties at the 2012b event of SN 2009ip based on its recently reported late-phase bolometric light curve. The explosion energy and ejected mass at the 2012b event are estimated as 0.01 M{sub ⊙} and 2 × 10{sup 49} erg, respectively. The circumstellar medium is assumed to have two components: an inner shell and an outer wind. The inner shell, which is likely created at the 2012a event, has a mass of 0.2 M{sub ⊙}. The outer wind is created by the wind mass loss before the 2012a mass ejection, and the progenitor is estimatedmore » to have had a mass-loss rate of about 0.1 M{sub ⊙} yr{sup −1} with a wind velocity of 550 km s{sup −1} before the 2012a event. The estimated explosion energy and ejected mass indicate that the 2012b event is not caused by a regular SN.« less

Constraining the dynamics of 2014-15 Bardarbunga-Holuhraun intrusion and eruption using seismic noise

NASA Astrophysics Data System (ADS)

Caudron, Corentin; Donaldson, Clare; White, Robert

2016-04-01

The 2010 Eyjafjallajokull volcanic eruption explosively emitted a large quantity of ash in the atmosphere and paralysed the European airspace for weeks. Several seismic scientific studies already contributed to the understanding of this complex eruption (e.g., Tarasewicz et al., 2012). Although an excellent network of seismometers recorded this eruption, some volcanological and seismological aspects are still poorly understood. In order to gain further constraints on the dynamics of this ground-breaking eruptions, we mine the seismic dataset using the seismic ambient noise technique between pairs of stations and the Seismic Amplitude Ratio Analysis (SARA). Our preliminary results reveal a strong contamination of the Cross Correlation Functions (CCF) by the volcanic tremor, particularly above 0.5 Hz even for station pairs located >50 km from the volcano. Although this volcanic tremor precludes the monitoring of the seismic velocities, it literally illuminated the medium. The two phases of the eruptions (i.e., effusive and explosive) are clearly distinguished in these functions due to their different locations. During the explosive phase, an intriguing shift of the main peaks of the cross correlation functions is evidenced (early May 2010). It is remarkably consistent with the downward migration proposed by Tarasewicz et al. (2012) and is interpreted as a migration of the volcanic tremor. SARA methodology, which is continuously imaging and tracking any significant seismicity at a 10-min time scale (Taisne et al., 2010), is applied in the 5-15 Hz frequency band in order to image to continuously migrating microseismicity. The analysis displays several shallow migrations (above 5 km of depth, in March 2010) preceding the effusive phase of the eruption. Interestingly, the results also evidence a fast and deep migration (> 5 km) starting a few hours before the beginning of the explosive phase (13 April 2010). These preliminary results may shed light on the triggering of the explosive eruption.

Quantitative and Qualitative Analyzes of the Explosive Cyclones that Reached the Antarctic Coast in the First Half of 2017

NASA Astrophysics Data System (ADS)

Pires, L. B. M.; Romao, M.; Freitas, A. C. V.

2017-12-01

An explosive cyclone is a kind of extratropical cyclone which shows a drop in pressure of at least 24 hPa in 24 hours. These are usually intense and they have rapid displacement which hinders their predictability. It is likely that climate change is causing an increase in this type of event in the Antarctic coast and, if this increase is confirmed, the regime of winds and temperatures may be changing. If there are more incidences of explosive cyclones, probably the Antarctic winds are becoming more intense and the temperatures in some places are becoming lower and in others are becoming higher. In the northern portion of the Antarctic Peninsula a decrease in temperature already has been recorded over the last 15 years, while a higher incidence of explosive cyclones over the region also has been found during this period. Studies also have suggested that the drop in temperatures in the Antarctic may be associated with the changes in wind direction, but the cause of these wind direction changes is unknown. Explosive cyclones, which change the wind patterns when they reach certain areas therefore may be contributing to this change in the Antarctic climate. This study is part of the "Explosive Cyclones on the Antarctic Coast" (EXCANC) Project conducted by the World Environmental Conservancy organization. This project analyzes data from meteorological stations strategically scattered throughout the coast and operated by various international Antarctic programs, and also utilizes satellite images. Results show that during the first half of 2017 the highest number of events were recorded at the Australian Casey station with 10 cases, followed by the French station of Dumont D'Urville with 7 cases. Halley's English station recorded its first explosive cyclone this year. Intensity analyzes also are shown.

Seismic Analysis of Three Bomb Explosions in Turkey

NASA Astrophysics Data System (ADS)

Necmioglu, O.; Semin, K. U.; Kocak, S.; Destici, C.; Teoman, U.; Ozel, N. M.

2016-12-01

Seismic analysis of three vehicle-installed bomb explosions occurred on 13 March 2016 in Ankara, 12 May 2016 in Diyarbakır and 9 July 2016 in Mardin have been conducted using data from the nearest stations (LOD, DYBB and MAZI) of the Boğaziçi University - Kandilli Observatory and Earthquake Research Institute's (KOERI) seismic network and compared with low-magnitude earthquakes in similar distance based on phase readings and frequency content. Amplitude spectra has been compared through Fourier transformation and earthquake-explosion frequency discrimination has been performed using various filter bands. Time-domain and spectral analysis have been performed using Geotool software provided by CTBTO. Local magnitude (ML) values have been calculated for each explosion by removing instrument-response and adding Wood-Anderson type instrument response. Approximate amount of explosives used in these explosions have been determined using empirical methods of Koper (2002). Preliminary results indicated that 16 tons TNT equivalent explosives have been used in 12 May 2016 Diyarbakır explosion, which is very much in accordance with the media reports claiming 15 tons of TNT. Our analysis for 9 July 2016 Mardin explosion matched the reported 5 tons of explosives. Results concerning 13 March 2016 Ankara explosion indicated that approximately 1,7 ton of TNT equivalent explosives were used in the attack whereas security and intelligence reports claimed 300 kg explosives as a combination of TNT, RDX and ammonium nitrate. The overestimated results obtained in our analysis for the Ankara explosion may be related due to i) high relative effectiveness factor of the RDX component of the explosive ii) inefficiency of Koper (2002) method in lower yields (since the method was developed using explosions with yields of 3-12 tons of TNT), iii) combination of both.

Development of explosively bonded TZM wire reinforced Columbian sheet composites

NASA Technical Reports Server (NTRS)

Otto, H. E.; Carpenter, S. H.

1972-01-01

Methods of producing TZM molybdenum wire reinforced C129Y columbium alloy composites by explosive welding were studied. Layers of TZM molybdenum wire were wound on frames with alternate layers of C129Y columbium alloy foil between the wire layers. The frames held both the wire and foils in place for the explosive bonding process. A goal of 33 volume percent molybdenum wire was achieved for some of the composites. Variables included wire diameter, foil thickness, wire separation, standoff distance between foils and types and amounts of explosive. The program was divided into two phases: (1) development of basic welding parameters using 5 x 10-inch composites, and (2) scaleup to 10 x 20-inch composites.

Source characterization of underground explosions from hydrodynamic-to-elastic coupling simulations

NASA Astrophysics Data System (ADS)

Chiang, A.; Pitarka, A.; Ford, S. R.; Ezzedine, S. M.; Vorobiev, O.

2017-12-01

A major improvement in ground motion simulation capabilities for underground explosion monitoring during the first phase of the Source Physics Experiment (SPE) is the development of a wave propagation solver that can propagate explosion generated non-linear near field ground motions to the far-field. The calculation is done using a hybrid modeling approach with a one-way hydrodynamic-to-elastic coupling in three dimensions where near-field motions are computed using GEODYN-L, a Lagrangian hydrodynamics code, and then passed to WPP, an elastic finite-difference code for seismic waveform modeling. The advancement in ground motion simulation capabilities gives us the opportunity to assess moment tensor inversion of a realistic volumetric source with near-field effects in a controlled setting, where we can evaluate the recovered source properties as a function of modeling parameters (i.e. velocity model) and can provide insights into previous source studies on SPE Phase I chemical shots and other historical nuclear explosions. For example the moment tensor inversion of far-field SPE seismic data demonstrated while vertical motions are well-modeled using existing velocity models large misfits still persist in predicting tangential shear wave motions from explosions. One possible explanation we can explore is errors and uncertainties from the underlying Earth model. Here we investigate the recovered moment tensor solution, particularly on the non-volumetric component, by inverting far-field ground motions simulated from physics-based explosion source models in fractured material, where the physics-based source models are based on the modeling of SPE-4P, SPE-5 and SPE-6 near-field data. The hybrid modeling approach provides new prospects in modeling explosion source and understanding the uncertainties associated with it.

Structure, phase content and mechanical properties of aluminium with hard particles after shock-wave compaction

NASA Astrophysics Data System (ADS)

Kulkov, S.; Vorozhtsov, S.; Turuntaev, I.

2015-04-01

The possibilities to combine metal and metal oxide powders in various compositions open a broad range of mechanical and thermal behavior. When using in nanostructured components the resulting materials might exhibit even more interesting properties, like product effectiveness, tensile strength, wear resistance, endurance and corrosion resistance. Intermetallics like TiAl could be obtained as TiAlx in a quality similar to that obtained from melting where only eutectic mixture can be produced. Similar effects are possible when compacting nanoceramic powders whereas these can be combined with intermetallics. Currently, it is very difficult to produce wires and special shaped parts from high temperature superconducting materials. The compacting by explosives could solve this problem.The present paper uses explosion compacting of Al nanoparticles to create nanocomposite with increased physico-mechanical properties. Russian civil explosive Uglenit was chosen as high energy material (HEM) for shock-wave compaction. The different schemes and conditions were suggested to run the explosion process. Al nanoparticles as produced by electric wire explosion contain 8-10% of aluminum oxide. That aluminum oxide can serve as strengthening material in the final nanocomposite which may be generated in various compositions by explosive compacting. Further modifications of nanocomposites were obtained when including nanodiamonds into the mixture with aluminum nanoparticles with different percentages. The addition of nanodiamonds results in a substantial strengthening effect. The experiments with compacting aluminum nanoparticles by explosives are described in detail including the process variations and conditions. The physico-mechanical properties of the nanocomposites are determined and discussed by considering the applied conditions. Especially, microstructure and phases of the obtained nanocomposites are analyzed by X-ray diffraction.

Flow field topology of transient mixing driven by buoyancy

NASA Technical Reports Server (NTRS)

Duval, Walter M B.

2004-01-01

Transient mixing driven by buoyancy occurs through the birth of a symmetric Rayleigh-Taylor morphology (RTM) structure for large length scales. Beyond its critical bifurcation the RTM structure exhibits self-similarity and occurs on smaller and smaller length scales. The dynamics of the RTM structure, its nonlinear growth and internal collision, show that its genesis occurs from an explosive bifurcation which leads to the overlap of resonance regions in phase space. This event shows the coexistence of regular and chaotic regions in phase space which is corroborated with the existence of horseshoe maps. A measure of local chaos given by the topological entropy indicates that as the system evolves there is growth of uncertainty. Breakdown of the dissipative RTM structure occurs during the transition from explosive to catastrophic bifurcation; this event gives rise to annihilation of the separatrices which drives overlap of resonance regions. The global bifurcation of explosive and catastrophic events in phase space for the large length scale of the RTM structure serves as a template for which mixing occurs on smaller and smaller length scales. Copyright 2004 American Institute of Physics.

Thermochemical properties of nanometer CL-20 and PETN fabricated using a mechanical milling method

NASA Astrophysics Data System (ADS)

Song, Xiaolan; Wang, Yi; An, Chongwei

2018-06-01

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and pentaerythritol tetranitrate (PETN), with mean sizes of 73.8 nm and 267.7 nm, respectively, were fabricated on a high-energy ball-mill. Scanning electron microscope (SEM) analysis was used to image the micron-scale morphology of nano-explosives, and the particle size distribution was calculated using the statistics of individual particle sizes obtained from the SEM images. Analyses, such as X-ray diffractometer (XRD), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS), were also used to confirm whether the crystal phase, molecular structure, and surface elements changed after a long-term milling process. The results were as expected. Thermal analysis was performed at different heating rates. Parameters, such as the activation energy (ES), activation enthalpy (ΔH≠), activation free energy (ΔG≠), activation entropy (ΔS≠), and critical temperature of thermal explosion (Tb), were calculated to determine the decomposition courses of the explosives. Moreover, the thermal decomposition mechanisms of nano CL-20 and nano PETN were investigated using thermal-infrared spectrometry online (DSC-IR) analysis, by which their gas products were also detected. The results indicated that nano CL-20 decomposed to CO2 and N2O and that nano PETN decayed to NO2, which implied a remarkable difference between the decomposition mechanisms of the two explosives. In addition, the mechanical sensitivities of CL-20 and PETN were tested, and the results revealed that nano-explosives were more insensitive than raw ones, and the possible mechanism for this was discussed. Thermal sensitivity was also investigated with a 5 s bursting point test, from which the 5 s bursting point (T5s) and the activation of the deflagration were obtained.

Collection of trace evidence of explosive residues from the skin in a death due to a disguised letter bomb. The synergy between confocal laser scanning microscope and inductively coupled plasma atomic emission spectrometer analyses.

PubMed

Turillazzi, Emanuela; Monaci, Fabrizio; Neri, Margherita; Pomara, Cristoforo; Riezzo, Irene; Baroni, Davide; Fineschi, Vittorio

2010-04-15

In most deaths caused by explosive, the victim's body becomes a depot for fragments of explosive materials, so contributing to the collection of trace evidence which may provide clues about the specific type of device used with explosion. Improvised explosive devices are used which contain "homemade" explosives rather than high explosives because of the relative ease with which such components can be procured. Many methods such as chromatography-mass spectrometry, scanning electron microscopy, stereomicroscopy, capillary electrophoresis are available for use in the identification of explosive residues on objects and bomb fragments. Identification and reconstruction of the distribution of explosive residues on the decedent's body may give additional hints in assessing the position of the victim in relation to the device. Traditionally these residues are retrieved by swabbing the body and clothing during the early phase, at autopsy. Gas chromatography-mass spectrometry and other analytical methods may be used to analyze the material swabbed from the victim body. The histological examination of explosive residues on skin samples collected during the autopsy may reveal significant details. The information about type, quantity and particularly about anatomical distribution of explosive residues obtained utilizing confocal laser scanning microscope (CLSM) together with inductively coupled plasma atomic emission spectrometer (ICP-AES), may provide very significant evidence in the clarification and reconstruction of the explosive-related events. Copyright 2009 Elsevier Ireland Ltd. All rights reserved.

Validation and Refinement of the DELFIC Cloud Rise Module

DTIC Science & Technology

1977-01-15

Explosion Energy Fraction in the Cloud, f 13 2.4.2 Temper&ture of Condensed-Phase Matter 13 2.4.3 Altitude 14 2.4.4 Rise V0elociy 14 2.4.5 Mass and Volume 15...2.4.1 Explosion Energy Fraction in the Cloud. f. The original NRDL water-surface burst model used an energy fraction of 33%. For the first DELFIC...of explosion energy) is used to heat soil and air to their respective initial tempera- tures. The soil mans and both initial temperatures are

Acute Effects of Plyometric Intervention—Performance Improvement and Related Changes in Sprinting Gait Variability.

PubMed

Maćkała, Krzysztof; Fostiak, Marek

2015-07-01

The purpose of this study was to examine the effect of a short high-intensity plyometric program on the improvement of explosive power of lower extremities and sprint performance as well as changes in sprinting stride variability in male sprinters. Fourteen healthy male sprinters (mean ± SD: age: 18.07 ± 0.73 years, body mass: 73 ± 9.14 kg, height: 180.57 ± 8.16 cm, and best 100 m: 10.89 ± 0.23) participated in the experiment. The experimental protocol included vertical jumping such as squat jump, countermovement jump, and horizontal jumps; standing long jump and standing triple jumps to assess lower-body power, maximal running velocity; a 20-m flying start sprint that evaluated variability of 10 running steps and 60-m starting block sprint. All analyzed parameters were obtained using the new technology of OptoJump-Microgate (OptoJump, Italy). The short-term plyometric training program significantly increased the explosive power of lower extremities, both vertical and horizontal jumping improvement. However, the vertical jumps increased much more than the horizontal. The 20-m improvements were derived from an increase of stride frequency from 4.31 to 4.39 Hz because of a decrease of ground contact time from 138 to 133 milliseconds. This did not translate into step length changes. Therefore, the significantly increased frequency of stride (1.8%), which is a specific expression of ground contact time reduction during support phase, resulted in an increase of speed. The training volume of 2 weeks (with 6 sessions) using high-intensity (between 180 and 250 jumps per session) plyometric exercises can be recommended as the short-term strategy that will optimize one's probability of reaching strong improvements in explosive power and sprint velocity performance.

Blast waves from violent explosive activity at Yasur Volcano, Vanuatu

NASA Astrophysics Data System (ADS)

Marchetti, E.; Ripepe, M.; Delle Donne, D.; Genco, R.; Finizola, A.; Garaebiti, E.

2013-11-01

and seismic waveforms were collected during violent strombolian activity at Yasur Volcano (Vanuatu). Averaging ~3000 seismic events showed stable waveforms, evidencing a low-frequency (0.1-0.3 Hz) signal preceding ~5-6 s the explosion. Infrasonic waveforms were mostly asymmetric with a sharp compressive (5-106 Pa) onset, followed by a small long-lasting rarefaction phase. Regardless of the pressure amplitude, the ratio between the positive and negative phases was constant. These waveform characteristics closely resembled blast waves. Infrared imagery showed an apparent cold spherical front ~20 m thick, which moved between 342 and 405 m/s before the explosive hot gas/fragments cloud. We interpret this cold front as that produced by the vapor condensation induced by the passage of the shock front. We suggest that violent strombolian activity at Yasur was driven by supersonic dynamics with gas expanding at 1.1 Mach number inside the conduit.

IMPACT OF NEW GAMOW–TELLER STRENGTHS ON EXPLOSIVE TYPE IA SUPERNOVA NUCLEOSYNTHESIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka

2016-12-20

Recent experimental results have confirmed a possible reduction in the Gamow–Teller (GT{sub +}) strengths of pf-shell nuclei. These proton-rich nuclei are of relevance in the deflagration and explosive burning phases of SNe Ia. While prior GT strengths result in nucleosynthesis predictions with a lower-than-expected electron fraction, a reduction in the GT{sub +} strength can result in a slightly increased electron fraction compared to previous shell model predictions, though the enhancement is not as large as previous enhancements in going from rates computed by Fuller, Fowler, and Newman based on an independent particle model. A shell model parametrization has been developed thatmore » more closely matches experimental GT strengths. The resultant electron-capture rates are used in nucleosynthesis calculations for carbon deflagration and explosion phases of SNe Ia, and the final mass fractions are compared to those obtained using more commonly used rates.« less

APTS and rGO co-functionalized pyrenated fluorescent nanonets for representative vapor phase nitroaromatic explosive detection.

PubMed

Guo, Linjuan; Zu, Baiyi; Yang, Zheng; Cao, Hongyu; Zheng, Xuefang; Dou, Xincun

2014-01-01

For the first time, flexible PVP/pyrene/APTS/rGO fluorescent nanonets were designed and synthesized via a one-step electrospinning method to detect representative subsaturated nitroaromatic explosive vapor. The functional fluorescent nanonets, which were highly stable in air, showed an 81% quenching efficiency towards TNT vapor (∼10 ppb) with an exposure time of 540 s at room temperature. The nice performance of the nanonets was ascribed to the synergistic effects induced by the specific adsorption properties of APTS, the fast charge transfer properties and the effective π-π interaction with pyrene and TNT of rGO. Compared to the analogues of TNT, the PVP/pyrene/APTS/rGO nanonets showed notable selectivity towards TNT and DNT vapors. The explored functionalization method opens up brand new insight into sensitive and selective detection of vapor phase nitroaromatic explosives.

Reaction-diffusion-induced explosive crystallization in a metal-selenium nanometer film structure

NASA Astrophysics Data System (ADS)

Kogai, V. Ya.

2016-03-01

Experimental data for reaction-diffusion-induced explosive crystallization in a nanodimensional metal (Cu, Ag)/selenium structure are presented. It is found that after the metal layer has completely diffused into the amorphous Se film, the electrical potential rises from 0.14 to 1.21 V in the Cu(30 nm)/Se(140 nm) heterolayer and from 0.01 to 1.17 V in the Ag(30 nm)/Se(140 nm) heterolayer. The metals diffusing into the amorphous Se layer interact with Se, forming nuclei of a new phase (CuSe or Ag2Se). The intense growth of the CuSe and Ag2Se crystallization centers results in a considerable liberation of latent energy in the form of phase transformation heat and in explosive growth of CuSe and Ag2Se nanocrystalline particles. The mean size of CuSe and Ag2Se crystallites equals 25 and 50 nm, respectively.

Impact of New Gamow-Teller Strengths on Explosive Type Ia Supernova Nucleosynthesis

NASA Astrophysics Data System (ADS)

Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka; Suzuki, Toshio; Hidaka, Jun; Honma, Michio; Iwamoto, Koichi; Nomoto, Ken'ichi; Otsuka, Takaharu

2016-12-01

Recent experimental results have confirmed a possible reduction in the Gamow-Teller (GT+) strengths of pf-shell nuclei. These proton-rich nuclei are of relevance in the deflagration and explosive burning phases of SNe Ia. While prior GT strengths result in nucleosynthesis predictions with a lower-than-expected electron fraction, a reduction in the GT+ strength can result in a slightly increased electron fraction compared to previous shell model predictions, though the enhancement is not as large as previous enhancements in going from rates computed by Fuller, Fowler, and Newman based on an independent particle model. A shell model parametrization has been developed that more closely matches experimental GT strengths. The resultant electron-capture rates are used in nucleosynthesis calculations for carbon deflagration and explosion phases of SNe Ia, and the final mass fractions are compared to those obtained using more commonly used rates.

Detection and modelling of the ionospheric perturbation caused by a Space Shuttle launch using a network of ground-based Global Positioning System stations

NASA Astrophysics Data System (ADS)

Bowling, Timothy; Calais, Eric; Haase, Jennifer S.

2013-03-01

The exhaust plume of the Space Shuttle during its ascent triggers acoustic waves which propagate through the atmosphere and induce electron density changes at ionospheric heights which changes can be measured using ground-based Global Positioning System (GPS) phase data. Here, we use a network of GPS stations to study the acoustic wave generated by the STS-125 Space Shuttle launch on May 11, 2009. We detect the resulting changes in ionospheric electron density, with characteristics that are typical of acoustic waves triggered by explosions at or near the Earth's surface or in the atmosphere. We successfully reproduce the amplitude and timing of the observed signal using a ray-tracing model with a moving source whose amplitude is directly scaled by a physical model of the shuttle exhaust energy, acoustic propagation in a dispersive atmosphere and a simplified two-fluid model of collisions between neutral gas and free electrons in the ionosphere. The close match between observed and model waveforms validates the modelling approach. This raises the possibility of using ground-based GPS networks to estimate the acoustic energy release of explosive sources near the Earth's surface or in atmosphere, and to constrain some atmospheric acoustic parameters.

The Low-luminosity Type IIP Supernova 2016bkv with Early-phase Circumstellar Interaction

NASA Astrophysics Data System (ADS)

Nakaoka, Tatsuya; Kawabata, Koji S.; Maeda, Keiichi; Tanaka, Masaomi; Yamanaka, Masayuki; Moriya, Takashi J.; Tominaga, Nozomu; Morokuma, Tomoki; Takaki, Katsutoshi; Kawabata, Miho; Kawahara, Naoki; Itoh, Ryosuke; Shiki, Kensei; Mori, Hiroki; Hirochi, Jun; Abe, Taisei; Uemura, Makoto; Yoshida, Michitoshi; Akitaya, Hiroshi; Moritani, Yuki; Ueno, Issei; Urano, Takeshi; Isogai, Mizuki; Hanayama, Hidekazu; Nagayama, Takahiro

2018-06-01

We present optical and near-infrared observations of a low-luminosity (LL) Type IIP supernova (SN) 2016bkv from the initial rising phase to the plateau phase. Our observations show that the end of the plateau is extended to ≳140 days since the explosion, indicating that this SN takes one of the longest times to finish the plateau phase among Type IIP SNe (SNe IIP), including LL SNe IIP. The line velocities of various ions at the middle of the plateau phase are as low as 1000–1500 km s‑1, which is the lowest even among LL SNe IIP. These measurements imply that the ejecta mass in SN 2016bkv is larger than that of the well-studied LL IIP SN 2003Z. In the early phase, SN 2016bkv shows a strong bump in the light curve. In addition, the optical spectra in this bump phase exhibit a blue continuum accompanied by a narrow Hα emission line. These features indicate an interaction between the SN ejecta and the circumstellar matter (CSM) as in SNe IIn. Assuming the ejecta–CSM interaction scenario, the mass loss rate is estimated to be ∼ 1.7× {10}-2 {M}ȯ yr‑1 within a few years before the SN explosion. This is comparable to or even larger than the largest mass loss rate observed for the Galactic red supergiants (∼ {10}-3 {M}ȯ yr‑1 for VY CMa). We suggest that the progenitor star of SN 2016bkv experienced a violent mass loss just before the SN explosion.

Kinetic effects in thermal explosion with oscillating ambient conditions.

PubMed

Novozhilov, Vasily

2018-03-05

Thermal explosion problem for a medium with oscillating ambient temperature at its boundaries is a new problem which was introduced in the preceding publication by the present author. It is directly applicable to a range of practical fire autoignition scenarios (e.g. in the storages of organic matter, explosives, propellants, etc.). Effects of kinetic mechanisms, however, need be further investigated as they are expected to alter critical conditions of thermal explosion. We consider several global kinetic mechanisms: first order reaction, second order reaction, and first order autocatalysis. It is demonstrated that kinetic effects related to reactants consumption do indeed shift respective critical boundaries. Effect of kinetics on oscillatory development of thermal explosion is of particular interest. In line with conclusions of the preceding publication, it is confirmed that temperature oscillations may develop during induction phase of thermal explosion when the effect of reactants consumption is properly taken into account. Moreover, development of thermal explosion instability through the prior oscillations is an inevitable and natural scenario. This fact is confirmed by a number of examples. Besides, effects of the other relevant parameter, Zeldovich number on critical conditions are also investigated.

Changes in Muscle Architecture, Explosive Ability, and Track and Field Throwing Performance Throughout a Competitive Season and After a Taper.

PubMed

Bazyler, Caleb D; Mizuguchi, Satoshi; Harrison, Alex P; Sato, Kimitake; Kavanaugh, Ashley A; DeWeese, Brad H; Stone, Michael H

2017-10-01

The purpose of this study was to examine the effects of an overreach and taper on measures of muscle architecture, jumping, and throwing performance in Division I collegiate throwers preparing for conference championships. Six collegiate track and field throwers (3 hammer, 2 discus, 1 javelin) trained for 12 weeks using a block-periodization model culminating with a 1-week overreach followed by a 3-week taper (ORT). Session rating of perceived exertion training load (RPETL) and strength training volume-load times bar displacement (VLd) were recorded weekly. Athletes were tested pre-ORT and post-ORT on measures of vastus lateralis architecture, unloaded and loaded squat and countermovement jump performance, underhand and overhead throwing performance, and competition throwing performance. There was a statistical reduction in weight training VLd/session (d = 1.21, p ≤ 0.05) and RPETL/session (d = 0.9, p ≤ 0.05) between the in-season and ORT training phases. Five of 6 athletes improved overhead throw and competition throwing performance after the ORT (d = 0.50, p ≤ 0.05). Vastus lateralis muscle thickness statistically increased after the in-season training phase (d = 0.28, p ≤ 0.05) but did not change after the ORT. Unloaded countermovement jump peak force and relative peak power improved significantly after the ORT (d = 0.59, p ≤ 0.05, d = 0.31, p ≤ 0.05, respectively). These findings demonstrate that an overreaching week followed by a 3-week taper is an effective means of improving explosive ability and throwing performance in collegiate track and field throwers despite the absence of detectable changes in muscle architecture.

Electrodics: mesoscale physicochemical interactions in lithium-ion batteries

NASA Astrophysics Data System (ADS)

Mukherjee, Partha P.; Chen, Chien-Fan

2014-06-01

Recent years have witnessed an explosion of interest and research endeavor in lithium-ion batteries to enable vehicle electrification. In particular, a critical imperative is to accelerate innovation for improved performance, life and safety of lithium-ion batteries for electric drive vehicles. Lithium ion batteries are complex, dynamical systems which include a multitude of coupled physicochemical processes encompassing electronic/ionic/diffusive transport in solid/electrolyte phases, electrochemical and phase change reactions and diffusion induced stress generation in multi-scale porous electrode microstructures. While innovations in nanomaterials and nanostructures have spurred the recent advancements, fundamental understanding of the electrode processing - microstructure - performance interplay is of paramount importance. In this presentation, mesoscale physicochemical interactions in lithium-ion battery electrodes will be elucidated.

Signs of magma ascent in LP and VLP seismic events and link to degassing: An example from the 2010 explosive eruption at Merapi volcano, Indonesia

NASA Astrophysics Data System (ADS)

Jousset, Philippe; Budi-Santoso, Agus; Jolly, Arthur D.; Boichu, Marie; Surono; Dwiyono, S.; Sumarti, Sri; Hidayati, Sri; Thierry, Pierre

2013-07-01

The link between seismicity and degassing is investigated during the VEI 4 eruptions of Merapi volcano (Indonesia) in October and in early November 2010. Seismicity comprised a large number and variety of earthquakes including Volcano-Tectonic events, a sustained period of Long Period Seismicity (LPS), i.e., Long-Period events (LP), Very Long Period events (VLP) and tremor. LPS seismicity is ascribed to the excitation of fluid-filled cavity resonance and inertial displacement of fluids and magma. We investigate here LPS that occurred between 17 October and 4 November 2010 to obtain insights into the volcano eruption processes which preceded the paroxysmal phase of the eruption on 4-5 November. We proceed to the moment tensor inversion of a well-recorded large VLP event during the intrusion phase on 17 October 2010, i.e., before the first explosion on 26 October. By using two simplified models (crack and pipe), we find a shallow source for this VLP event at about 1 km to the south of the summit and less than 1 km below the surface. We analyze more than 90 LP events that occurred during the multi-phase eruption (29 October-4 November). We show that most of them have a dominant frequency in the range 0.2-4 Hz. We could locate 48 of those LP events; at least 3 clusters of LP events occurred successively. We interpret these observations as generated by different fluid-filled containers in the summit area that were excited while magma rose. We also observe significant variations of the complex frequency during the course of the eruption. We discuss these changes in terms of a variable ratio of fluid to solid densities and/or by possible conduit geometry change and/or permeability of the conduit or the edifice and/or by resonance of different fluid-containers during the release of more than 0.4 Tg of SO2 and large but unknown masses of other volcanic gases. Finally, we also discuss how the major explosions of the eruption were possibly triggered by passing waves resulting from regional tectonic earthquakes on 3 and 4 November.

Chemical Sensing of Unexploded Ordnance with the Mobile Underwater Survey System (MUDSS)

NASA Technical Reports Server (NTRS)

Darrach, M. R.; Chutjian, A.

1995-01-01

The ability to sense explosives residues in the marine environment is a critical tool for identification and classification of underwater unexploded ordnance (UXO). Trace explosives signatures of TNT and DNT have been extracted from multiple sediment samples adjacent to unexploded undersea ordnance at Halifax Harbor, Canada. The ordnance was hurled into the harbor during a massive explosion fifty years earlier, in 1945 after World War II had ended. Laboratory sediment extractions were made using the solid-phase microextraction (SPME) method in seawater, and detection using the Reversal Electron Attachment Detection (READ) technique and, in the case of DNT, a commercial gas-chromatography/mass spectrometer (GC/MS). Results show that, after more than 50 years in the environment, ordnance which appeared to be physically intact gave good explosives signatures at the parts-per-billion level, whereas ordnance which had been cracked open during the explosion gave no signatures at the 10 parts-per-trillion sensitivity level. These measurements appear to provide the first reported data of explosives signatures from undersea UXOs.

Preliminary SPE Phase II Far Field Ground Motion Estimates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steedman, David W.

2014-03-06

Phase II of the Source Physics Experiment (SPE) program will be conducted in alluvium. Several candidate sites were identified. These include existing large diameter borehole U1e. One criterion for acceptance is expected far field ground motion. In June 2013 we were requested to estimate peak response 2 km from the borehole due to the largest planned SPE Phase II experiment: a contained 50- Ton event. The cube-root scaled range for this event is 5423 m/KT 1/3. The generally accepted first order estimate of ground motions from an explosive event is to refer to the standard data base for explosive eventsmore » (Perrett and Bass, 1975). This reference is a compilation and analysis of ground motion data from numerous nuclear and chemical explosive events from Nevada National Security Site (formerly the Nevada Test Site, or NTS) and other locations. The data were compiled and analyzed for various geologic settings including dry alluvium, which we believe is an accurate descriptor for the SPE Phase II setting. The Perrett and Bass plots of peak velocity and peak yield-scaled displacement, both vs. yield-scaled range, are provided here. Their analysis of both variables resulted in bi-linear fits: a close-in non-linear regime and a more distant linear regime.« less

An introductory characterization of a combat-casualty-care relevant swine model of closed head injury resulting from exposure to explosive blast.

PubMed

Bauman, Richard A; Ling, Geoffrey; Tong, Lawrence; Januszkiewicz, Adolph; Agoston, Dennis; Delanerolle, Nihal; Kim, Young; Ritzel, Dave; Bell, Randy; Ecklund, James; Armonda, Rocco; Bandak, Faris; Parks, Steven

2009-06-01

Explosive blast has been extensively used as a tactical weapon in Operation Iraqi Freedom (OIF) and more recently in Operation Enduring Freedom(OEF). The polytraumatic nature of blast injuries is evidence of their effectiveness,and brain injury is a frequent and debilitating form of this trauma. In-theater clinical observations of brain-injured casualties have shown that edema, intracranial hemorrhage, and vasospasm are the most salient pathophysiological characteristics of blast injury to the brain. Unfortunately, little is known about exactly how an explosion produces these sequelae as well as others that are less well documented. Consequently, the principal objective of the current report is to present a swine model of explosive blast injury to the brain. This model was developed during Phase I of the DARPA (Defense Advanced Research Projects Agency) PREVENT (Preventing Violent Explosive Neurotrauma) blast research program. A second objective is to present data that illustrate the capabilities of this model to study the proximal biomechanical causes and the resulting pathophysiological, biochemical,neuropathological, and neurological consequences of explosive blast injury to the swine brain. In the concluding section of this article, the advantages and limitations of the model are considered, explosive and air-overpressure models are compared, and the physical properties of an explosion are identified that potentially contributed to the in-theater closed head injuries resulting from explosions of improvised explosive devices (IEDs).

Time variation in the reaction-zone structure of two-phase spray detonations.

NASA Technical Reports Server (NTRS)

Pierce, T. H.; Nicholls, J. A.

1973-01-01

A detailed theoretical analysis of the time-varying detonation structure in a monodisperse spray is presented. The theory identifies experimentally observed reaction-zone overpressures as deriving from blast waves formed therein by the explosive ignition of the spray droplets, and follows in time the motion, change in strength, and interactions of these blast waves with one another, and with the leading shock. The results are compared with experimental data by modeling the motion of a finite-size circular pressure transducer through the theoretical data field in an x-t space.

Can North Korean Nuclear Explosions Stir Baekdu (Changbai) Volcano to be Erupted?

NASA Astrophysics Data System (ADS)

Hong, T. K.; Choi, E.; Park, S.; Shin, J. S.

2015-12-01

Potential volcanic eruption in Mt. Baekdu (Changbai) hasbeen a long-lasting concern in the far-eastern Asia.There were several explosive eruptions historically. Themost recent eruption was made in 1903. The eruption in969 is believed to be the most violent with volcanicexplosivity index of 7. The volcano is located in ~130 kmaway from the North Korean nuclear explosion test sitewhere three moderate-size nuclear explosions withmagnitudes of 4.3, 4.7 and 5.1 were conducted in 2006,2009 and 2013. There is increasing concern that a largenuclear explosion may trigger volcanic eruption. Seismicwaveforms are subtle to vary with the crustal structure.The strong ground motions generated by a potential largenuclear explosion are difficult to be simulated forvolcanic regions where complex crustal structures areexpected. We calculate the ground motions by hypotheticallarge nuclear explosions using a nuclear-explosion sourcemodel and the seismic waveforms of prior nuclearexplosions. The validity of the method is examined bycomparing the observed and quasi-synthetic seismicwaveforms of prior nuclear explosions. The peak groundaccelerations (PGA) around the volcano are estimated froma PGA attenuation equation that was determined based onseismic waveforms from natural earthquakes. Thehorizontal and vertical PGAs by an M7.0 undergroundnuclear explosion are expected to reach 0.14 and 0.11m/s2 at the volcano, inducing a dynamic stress in themagma chamber. The induced pressure change in the magmachamber is verified by numerical modeling of dynamicstress changes.

Development and validation of a solid phase extraction sample cleanup procedure for the recovery of trace levels of nitro-organic explosives in soil.

PubMed

Thomas, Jennifer L; Donnelly, Christopher C; Lloyd, Erin W; Mothershead, Robert F; Miller, Mark L

2018-03-01

An improved cleanup method has been developed for the recovery of trace levels of 12 nitro-organic explosives in soil, which is important not only for the forensic community, but also has environmental implications. A wide variety of explosives or explosive-related compounds were evaluated, including nitramines, nitrate esters, nitroaromatics, and a nitroalkane. Fortified soil samples were extracted with acetone, processed via solid phase extraction (SPE), and then analyzed by gas chromatography with electron capture detection. The following three SPE sorbents in cartridge format were compared: Empore™ SDB-XC, Oasis ® HLB, and Bond Elut NEXUS cartridges. The NEXUS cartridges provided the best overall recoveries for the 12 explosives in potting soil (average 48%) and the fastest processing times (<30min). It also rejected matrix components from spent motor oil on potting soil. The SPE method was validated by assessing limit of detection (LOD), processed sample stability, and interferences. All 12 compounds were detectable at 0.02μg explosive/gram of soil or lower in the three matrices tested (potting soil, sand, and loam) over three days. Seven explosives were stable up to seven days at 2μg/g and three were stable at 0.2μg/g, both in processed loam, which was the most challenging matrix. In the interference study, five interferences above the determined LOD for soil were detected in matrices collected across the United States and in purchased all-purpose sand, potting soil, and loam. This represented a 3.2% false positive rate for the 13 matrices processed by the screening method for interferences. The reported SPE cleanup method provides a fast and simple extraction process for separating organic explosives from matrix components, facilitating sample throughput and reducing instrument maintenance. In addition, a comparison study of the validated SPE method versus conventional syringe filtration was completed and highlighted the benefits of sample cleanup for removing matrix interferences, while also providing lower supply cost, order of magnitude lower LODs for most explosives, higher percent recoveries for complex matrices, and fewer instrument maintenance issues. Published by Elsevier B.V.

Predicting the Plate Dent Test Output in Order to Assess the Performance of Condensed High Explosives

NASA Astrophysics Data System (ADS)

Frem, Dany

2017-01-01

In the present study, a relationship is proposed that is capable of predicting the output of the plate dent test. It is shown that the initial density ?; condensed phase heat of formation ?; the number of carbon (C), nitrogen (N), oxygen (O); and the composition molecular weight (MW) are the most important parameters needed in order to accurately predict the absolute dent depth ? produced on 1018 cold-rolled steel by a detonating organic explosive. The estimated ? values can be used to predict the detonation pressure (P) of high explosives; furthermore, we show that a correlation exists between ? and the Gurney velocity ? parameter. The new correlation is used to accurately estimate ? for several C-H-N-O explosive compositions.

Explosive vessel for coupling dynamic experiments to the X-ray beam at the Advanced Photon Source

NASA Astrophysics Data System (ADS)

Owens, Charles; Sanchez, Nathaniel; Sorensen, Christian; Jensen, Brian

2017-06-01

Recent experiments at the Advanced Photon Source have been successful in coupling gun systems to the synchrotron to take advantage of the advanced X-ray diagnostics available including X-ray diffraction and X-ray phase contrast imaging (PCI) to examine matter at extreme conditions. There are many experiments that require explosive loading capabilities, e.g. detonator and initiator dynamics, small angle X-ray scattering (SAXS), ejecta formation, and explosively driven flyer experiments. The current work highlights a new explosive vessel that was designed specifically for use at a synchrotron facility with requirements to confine up to 15 grams of explosives (TNT equivalent), couple the vessel to the X-ray beam line, and reliably position samples remotely. A description of the system and capability will be provided along with the results from qualification testing to bring the system into service (LA-UR-17-21381).

Detonation initiation of heterogeneous melt-cast high explosives

NASA Astrophysics Data System (ADS)

Chuzeville, V.; Baudin, G.; Lefrançois, A.; Genetier, M.; Barbarin, Y.; Jacquet, L.; Lhopitault, J.-L.; Peix, J.; Boulanger, R.; Catoire, L.

2017-01-01

2,4,6-trinitrotoluene (TNT) is widely used in conventional and insensitive munitions as a fusible binder, commonly melt-cast with other explosives such as 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) or 3-nitro-1,2,4-triazol-one (NTO). In this paper, we study the shock-to-detonation transition phenomenon in two melt-cast high explosives (HE). We have performed plate impact tests on wedge samples to measure run-distance and time-to-detonation in order to establish the Pop-plot relation for several melt-cast HE. Highlighting the existence of the single curve buildup, we propose a two phase model based on a Zeldovich, Von-Neumann, Döring (ZND) approach where the deflagration fronts grow from the explosive grain boundaries. Knowing the grain size distribution, we calculate the deflagration velocities of the explosive charges as a function of shock pressure and explore the possible grain fragmentation.

Analysis of Spattering Activity at Halema'uma'u in 2015

NASA Astrophysics Data System (ADS)

Mintz, Bianca G.

The classical explosive basaltic eruption spectrum is traditionally defined by the following end member eruption styles: Hawaiian and Strombolian. The field use of high-speed cameras has enabled volcanologists to make improved quantifications and more accurate descriptions of these classical eruptions styles and to quantify previously undecipherable activity (including activity on the basaltic eruption spectrum between the two defined end members). Explosive activity in 2015 at the free surface of the Halema'uma'u lava lake at Kilauea exhibited features of both sustained (Hawaiian) fountaining and transient (Strombolian) explosivity. Most of this activity is internally triggered by the internal rise of decoupled gas bubbles from below the lake's surface, but external triggering via rock falls, was also observed. Here I identify three styles of bubble bursting and spattering eruptive activity (isolated events, clusters of events, and prolonged episodes) at the lava lake, and distinguished them based on their temporal and spatial distributions. Isolated events are discrete single bubble bursts that persist for a few tenths of seconds to seconds and are separated by repose periods of similar or longer time scales. Cluster of events are closely spaced, repeated events grouped around a narrow point source, which persist for seconds to minutes. Prolonged episodes are groupings of numerous events closely linked in space and time that persist for tens of minutes to hours. Analysis of individual events from high-speed camera images indicates that they are made up of up to three phases: the bubble ascent phase, the bursting and pyroclast ejection phase, and the drain back (and rebound) phase. Based on the numerical parameters established in this study, the 2015 activity was relatively weak (i.e., of low intensity) but still falls in a region between those of continuous Hawaiian fountains and impulsive, short-lived Strombolian explosions, in terms of duration.

Amorphization of cobalt monoxide nanocrystals and related explosive gas sensing applications.

PubMed

Li, L H; Xiao, J; Yang, G W

2015-10-16

Amorphous nanomaterials have attracted attention due to their excellent performances, highly comparable to their crystalline counterparts. Sensor materials with amorphous phases are usually evaluated to be unsuitable for sensors because of poor performance. As a matter of fact, amorphous nanomaterials have rather unique sensor behaviors. Here, we report the amorphousization of cobalt monoxide (CoO) nanocrystals driven by a unique process involved in laser ablation in liquid (LAL). We also established that a fast and nonequilibrium process created by LAL results in the amorphousization of nanocrystals. The as-prepared amorphous CoO (a-CoO) nanoflakes possess a high aspect ratio, which showed good sensing of explosive gases. The fabricated gas sensor can detect CO and H2 at levels as low as 5 and 10 ppm, respectively, at 100 °C. The performance characteristics of this sensor, including high sensitivity, low working temperature, and low detection limit, are superior to those of sensors made with crystalline phase oxides. Meanwhile, a temperature-dependent p-n transition was observed in the sensor's response to CO, suggesting that the sensing properties can be tailored by changing the carrier type, thus tuning the selectivity of sensors to different gases. These findings demonstrate the potential applications of amorphous nanomaterials as gas sensor components.

Shallow-seated explosions in the construction of the Motukorea tuff ring (Auckland, New Zealand): Evidence from lithic and sedimentary characteristics

NASA Astrophysics Data System (ADS)

Agustín-Flores, Javier; Németh, Károly; Cronin, Shane J.; Lindsay, Jan M.; Kereszturi, Gábor

2015-10-01

At least 52 eruption centres are scattered within the 360 km2 Auckland Volcanic Field (AVF). Motukorea, now an island in the Waitemata Harbour, is one of 39 AVF volcanoes that experienced a phreatomagmatic explosive phase, before a magmatic phase. The volcano erupted through a 200-300 m-thick, consolidated, mudstone/sandstone sequence of the Miocene Waitemata Group, which overlies the Waipapa Terrane greywacke basement. Detailed field descriptions of the sedimentary characteristics of the early phreatomagmatic deposits were carried out, along with examination of lithics. The ejecta ring deposit comprises 55 to 60 vol.% lithics, of which Waitemata Group fragments constitute approximately 90 vol.%, whereas < 10 vol.% are Waipapa fragments, suggesting a dominance of shallow fragmentation. The sedimentary characteristics of the stratigraphic sequence at Motukorea suggest a dominance of wet surges at the beginning of the eruption with progression into drier sequences upwards. This is reflected in increasing inter-bedded juvenile-pyroclast-dominated fall deposits up-sequence. These characteristics are attributed to the changing hydrogeological conditions within the diatreme and the host rocks. These findings shed light on the eruption dynamics of phreatomagmatic eruptions through consolidated rocks in the AVF and enable the depiction of a scenario of future eruptions within the field in similar substrates.

Simplified Phased-Mission System Analysis for Systems with Independent Component Repairs

NASA Technical Reports Server (NTRS)

Somani, Arun K.

1996-01-01

Accurate analysis of reliability of system requires that it accounts for all major variations in system's operation. Most reliability analyses assume that the system configuration, success criteria, and component behavior remain the same. However, multiple phases are natural. We present a new computationally efficient technique for analysis of phased-mission systems where the operational states of a system can be described by combinations of components states (such as fault trees or assertions). Moreover, individual components may be repaired, if failed, as part of system operation but repairs are independent of the system state. For repairable systems Markov analysis techniques are used but they suffer from state space explosion. That limits the size of system that can be analyzed and it is expensive in computation. We avoid the state space explosion. The phase algebra is used to account for the effects of variable configurations, repairs, and success criteria from phase to phase. Our technique yields exact (as opposed to approximate) results. We demonstrate our technique by means of several examples and present numerical results to show the effects of phases and repairs on the system reliability/availability.

METHOD 529, DETERMINATION OF EXPLOSIVES AND RELATED COMPOUNDS IN DRINKING WATER BY SOLID PHASE EXTRACTION AND CAPILLARY COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY

EPA Science Inventory

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a military explosive which is known to have contaminated groundwater on and near military installations where it has been used and stored. Historical disposal practices such as open burning and detonation have contributed to envir...

Method and apparatus for optimized sampling of volatilizable target substances

DOEpatents

Lindgren, Eric R.; Phelan, James M.

2004-10-12

An apparatus for capturing, from gases such as soil gas, target analytes. Target analytes may include emanations from explosive materials or from residues of explosive materials. The apparatus employs principles of sorption common to solid phase microextraction, and is best used in conjunction with analysis means such as a gas chromatograph. To sorb target analytes, the apparatus functions using various sorptive structures to capture target analyte. Depending upon the embodiment, those structures may include a capillary tube including an interior surface on which sorptive material (similar to that on the surface of a SPME fiber) is supported (along with means for moving gases through the capillary tube so that the gases come into close proximity to the sorptive material). In one disclosed embodiment, at least one such sorptive structure is associated with an enclosure including an opening in communication with the surface of a soil region potentially contaminated with buried explosive material such as unexploded ordnance. Emanations from explosive materials can pass into and accumulate in the enclosure where they are sorbed by the sorptive structures. Also disclosed is the use of heating means such as microwave horns to drive target analytes into the soil gas from solid and liquid phase components of the soil.

Explosive synchronization transitions in complex neural networks.

PubMed

Chen, Hanshuang; He, Gang; Huang, Feng; Shen, Chuansheng; Hou, Zhonghuai

2013-09-01

It has been recently reported that explosive synchronization transitions can take place in networks of phase oscillators [Gómez-Gardeñes et al. Phys. Rev. Lett. 106, 128701 (2011)] and chaotic oscillators [Leyva et al. Phys. Rev. Lett. 108, 168702 (2012)]. Here, we investigate the effect of a microscopic correlation between the dynamics and the interacting topology of coupled FitzHugh-Nagumo oscillators on phase synchronization transition in Barabási-Albert (BA) scale-free networks and Erdös-Rényi (ER) random networks. We show that, if natural frequencies of the oscillations are positively correlated with node degrees and the width of the frequency distribution is larger than a threshold value, a strong hysteresis loop arises in the synchronization diagram of BA networks, indicating the evidence of an explosive transition towards synchronization of relaxation oscillators system. In contrast to the results in BA networks, in more homogeneous ER networks, the synchronization transition is always of continuous type regardless of the width of the frequency distribution. Moreover, we consider the effect of degree-mixing patterns on the nature of the synchronization transition, and find that the degree assortativity is unfavorable for the occurrence of such an explosive transition.

Core-collapse SNe of type IIP and their progenitors: The case study of PNV J01315945+3328458

NASA Astrophysics Data System (ADS)

Dastidar, Raya; Kumar, Brijesh; Sahu, Devendra Kumar; Misra, Kuntal; Singh, Mridweeka; Gangopadhyay, Anjasha; Anapuma, Gadiyara Chakrapani; Pandey, Shashi Bhushan

2018-04-01

The type II supernovae (SNe) are hydrogen-rich cosmic explosions resulting from the collapse of massive stars. The impetus of studying individual events arises from its cosmological importance and the diverse understanding of the evolution and explosion mechanism of such events. In this work, we present the preliminary photometric and spectroscopic analysis of a recent type IIP explosion, PNV J01315945+3328458 in the galaxy NGC 582. While the initial phases of these energetic events are bright enough to be observed with the 1-2m class telescopes, the supernovae fade below the detection limit of these telescopes in the nebular phase. In addition, the class of sub-luminous events with Mv ˜ -15 or the events occurring at higher redshift, fade below the detection limit of these telescopes very early in their evolution. Large aperture telescopes like the newly installed 3.6m Devasthal Optical Telescope (DOT) will ensure a longer coverage of such events and also to probe deeper into the Universe. With the 3.6m telescope installed in Devasthal (DOT), we plan to study the progenitor environment of CCSNe to infer the metallicity at the explosion site.

Planar solid-phase microextraction-ion mobility spectrometry: a diethoxydiphenylsilane-based coating for the detection of explosives and explosive taggants.

PubMed

Mattarozzi, M; Bianchi, F; Bisceglie, F; Careri, M; Mangia, A; Mori, G; Gregori, A

2011-03-01

A novel diethoxydiphenylsilane-based coating for planar solid-phase microextraction was developed using sol-gel technology and used for ion mobility spectrometric detection of the explosives 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and of the explosive taggant ethylene glycol dinitrate. The trap was characterized in terms of coating thickness, morphology, inter-batch repeatability, and extraction efficiency. An average thickness of 143 ± 13 μm with a uniform distribution of the coating was obtained. Good performances of the developed procedure in terms of both intra-batch and inter-batch repeatability with relative standard deviations <7% were obtained. Experimental design and desirability function were used to find the optimal conditions for simultaneous headspace extraction of the investigated compounds: the optimal values were found in correspondence of a time and a temperature of extraction of 45 min and 40 °C, respectively. Detection and quantitation limits in low nanogram levels were achieved proving the superior extraction capability of the developed coating, obtaining ion mobility spectrometric responses at least two times higher than those achieved using commercial teflon and paper traps.

Explosive synchronization transitions in complex neural networks

NASA Astrophysics Data System (ADS)

Chen, Hanshuang; He, Gang; Huang, Feng; Shen, Chuansheng; Hou, Zhonghuai

2013-09-01

It has been recently reported that explosive synchronization transitions can take place in networks of phase oscillators [Gómez-Gardeñes et al. Phys. Rev. Lett. 106, 128701 (2011)] and chaotic oscillators [Leyva et al. Phys. Rev. Lett. 108, 168702 (2012)]. Here, we investigate the effect of a microscopic correlation between the dynamics and the interacting topology of coupled FitzHugh-Nagumo oscillators on phase synchronization transition in Barabási-Albert (BA) scale-free networks and Erdös-Rényi (ER) random networks. We show that, if natural frequencies of the oscillations are positively correlated with node degrees and the width of the frequency distribution is larger than a threshold value, a strong hysteresis loop arises in the synchronization diagram of BA networks, indicating the evidence of an explosive transition towards synchronization of relaxation oscillators system. In contrast to the results in BA networks, in more homogeneous ER networks, the synchronization transition is always of continuous type regardless of the width of the frequency distribution. Moreover, we consider the effect of degree-mixing patterns on the nature of the synchronization transition, and find that the degree assortativity is unfavorable for the occurrence of such an explosive transition.

Particle momentum effects from the detonation of heterogeneous explosives

NASA Astrophysics Data System (ADS)

Frost, D. L.; Ornthanalai, C.; Zarei, Z.; Tanguay, V.; Zhang, F.

2007-06-01

Detonation of a spherical high explosive charge containing solid particles generates a high-speed two-phase flow comprised of a decaying spherical air blast wave together with a rapidly expanding cloud of particles. The particle momentum effects associated with this two-phase flow have been investigated experimentally and numerically for a heterogeneous explosive consisting of a packed bed of inert particles saturated with a liquid explosive. Experimentally, the dispersion of the particles was tracked using flash radiography and high-speed photography. A particle streak gauge was developed to measure the rate of arrival of the particles at various locations. Using a cantilever gauge and a free-piston impulse gauge, it was found that the particle momentum flux provided the primary contribution of the multiphase flow to the near-field impulse applied to a nearby small structure. The qualitative features of the interaction between a particle and the flow field are illustrated using simple models for the particle motion and blast wave dynamics. A more realistic Eulerian two-fluid model for the gas-particle flow and a finite-element model for the structural response of the cantilever gauge are then used to determine the relative contributions of the gas and particles to the loading.

Discrimination of smokeless powders by headspace SPME-GC-MS and SPME-GC-ECD, and the potential implications upon training canine detection of explosives

NASA Astrophysics Data System (ADS)

Harper, Ross J.; Almirall, Jose R.; Furton, Kenneth G.

2005-05-01

This presentation will provide an odour analysis of a variety of smokeless powders & communicate the rapid SPME-GC-ECD method utilized. This paper will also discuss the implications of the headspace analysis of Smokeless Powders upon the choice of training aids for Explosives Detection Canines. Canine detection of explosives relies upon the dogs" ability to equate finding a given explosive odour with a reward, usually in the form of praise or play. The selection of explosives upon which the dogs are trained thus determines which explosives the canines can and potentially cannot find. Commonly, the training is focussed towards high explosives such as TNT and Composition 4, and the low explosives such as Black and Smokeless Powders are added often only for completeness. Powder explosives constitute a major component of explosive incidents throughout the US, and canines trained to detect explosives must be trained across the entire range of powder products. Given the variability in the manufacture and product make-up many smokeless powders do not share common odour chemicals, giving rise to concerns over the extensiveness of canine training. Headspace analysis of a selection of Smokeless Powders by Solid Phase Microextraction Gas Chromatography using Mass Spectrometry (SPME-GC-MS) and Electron Capture Detectors (SPME-GC-ECD) has highlighted significant differences in the chemical composition of the odour available from different brands. This suggests that greater attention should be paid towards the choice of Powder Explosives when assigning canine training aids.

Final Report: Ionization chemistry of high temperature molecular fluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fried, L E

2007-02-26

With the advent of coupled chemical/hydrodynamic reactive flow models for high explosives, understanding detonation chemistry is of increasing importance to DNT. The accuracy of first principles detonation codes, such as CHEETAH, are dependent on an accurate representation of the species present under detonation conditions. Ionic species and non-molecular phases are not currently included coupled chemistry/hydrodynamic simulations. This LDRD will determine the prevalence of such species during high explosive detonations, by carrying out experimental and computational investigation of common detonation products under extreme conditions. We are studying the phase diagram of detonation products such as H{sub 2}O, or NH{sub 3} andmore » mixtures under conditions of extreme pressure (P > 1 GPa) and temperature (T > 1000K). Under these conditions, the neutral molecular form of matter transforms to a phase dominated by ions. The phase boundaries of such a region are unknown.« less

Method and apparatus for optimized sampling of volatilizable target substances

DOEpatents

Lindgren, Eric R.; Phelan, James M.

2002-01-01

An apparatus for capturing, from gases such as soil gas, target analytes. Target analytes may include emanations from explosive materials or from residues of explosive materials. The apparatus employs principles of sorption common to solid phase microextraction, and is best used in conjunction with analysis means such as a gas chromatograph. To sorb target analytes, the apparatus functions using various sorptive structures to capture target analyte. Depending upon the embodiment, those structures may include 1) a conventional solid-phase microextraction (SPME) fiber, 2) a SPME fiber suspended in a capillary tube (with means provided for moving gases through the capillary tube so that the gases come into close proximity to the suspended fiber), and 3) a capillary tube including an interior surface on which sorptive material (similar to that on the surface of a SPME fiber) is supported (along with means for moving gases through the capillary tube so that the gases come into close proximity to the sorptive material). In one disclosed embodiment, at least one such sorptive structure is associated with an enclosure including an opening in communication with the surface of a soil region potentially contaminated with buried explosive material such as unexploded ordnance. Emanations from explosive materials can pass into and accumulate in the enclosure where they are sorbed by the sorptive structures. Also disclosed is the use of heating means such as microwave horns to drive target analytes into the soil gas from solid and liquid phase components of the soil.

Morphological and structural changes at the Merapi lava dome monitored using Unmanned Aerial Vehicles (UAVs)

NASA Astrophysics Data System (ADS)

Darmawan, H.; Walter, T. R.; Brotopuspito, K. S.; Subandriyo, S.; Nandaka, M. A.

2017-12-01

Six gas-driven explosions between 2012 and 2014 had changed the morphology and structures of the Merapi lava dome. The explosions mostly occurred during rainfall season and caused NW-SE elongated open fissures that dissected the lava dome. In this study, we conducted UAVs photogrammetry before and after the explosions to investigate the morphological and structural changes and to assess the quality of the UAV photogrammetry. The first UAV photogrammetry was conducted on 26 April 2012. After the explosions, we conducted Terrestrial Laser Scanning (TLS) survey on 18 September 2014 and repeated UAV photogrammetry on 6 October 2015. We applied Structure from Motion (SfM) algorithm to reconstruct 3D SfM point clouds and photomosaics of the 2012 and 2015 UAVs images. Topography changes has been analyzed by calculating height difference between the 2012 and 2015 SfM point clouds, while structural changes has been investigated by visual comparison between the 2012 and 2015 photo mosaics. Moreover, a quality assessment of the results of UAV photogrammetry has been done by comparing the 3D SfM point clouds to TLS dataset. Result shows that the 2012 and 2015 SfM point clouds have 0.19 and 0.57 m difference compared to the TLS point cloud. Furthermore, topography, and structural changes reveal that the 2012-14 explosions were controlled by pre-existing structures. The volume of the 2012-14 explosions is 26.400 ± 1320 m3 DRE. In addition, we find a structurally delineated unstable block at the southern front of the dome which potentially collapses in the future. We concluded that the 2012-14 explosions occurred due to interaction between magma intrusion and rain water and were facilitated by pre-existing structures. The unstable block potentially leads to a rock avalanche hazard. Furthermore, our drone photogrammetry results show very promising and therefore we recommend to use drone for topography mapping in lava dome building volcanoes.

Understanding Laterally Varying Path Effects on P/S Ratios and their Effectiveness for Event Discrimination at Local Distances

NASA Astrophysics Data System (ADS)

Pyle, M. L.; Walter, W. R.

2017-12-01

Discrimination between underground explosions and naturally occurring earthquakes is an important endeavor for global security and test-ban treaty monitoring, and ratios of seismic P to S-wave amplitudes at regional distances have proven to be an effective discriminant. The use of the P/S ratio is rooted in the idea that explosive sources should theoretically only generate compressional energy. While, in practice, shear energy is observed from explosions, generally when corrections are made for magnitude and distance, P/S ratios from explosions are higher than those from surrounding earthquakes. At local distances (< 200 km) that might be needed to detect smaller events, however, this discriminant becomes less reliable. While ratios at some stations still show separation between earthquake and explosion populations, at other stations the populations are indistinguishable. There is no clear distance or azimuthal trend for which stations show discriminating abilities and which do not. A number of factors may play a role in differences we see between regional and local discrimination, including source effects such as depth and radiation pattern, and path effects such as laterally varying attenuation and focusing/defocusing from layers and scattering. We use data from the Source Physics Experiment (SPE) to investigate some of these effects. SPE is a series of chemical explosions at the Nevada National Security Site (NNSS) designed to improve our understanding and modeling capabilities of shear waves generated by explosions. Phase I consisted of 5 explosions in granite and Phase II will move to a contrasting dry alluvium geology. We apply a high-resolution 2D attenuation model to events near the NNSS to examine what effect path plays in local P/S ratios, and how well an earthquake-derived model can account for shallower explosion paths. The model incorporates both intrinsic attenuation and scattering effects and extends to 16 Hz, allowing us to make lateral path corrections and consider high-frequency ratios. Preliminary work suggests that while 2D path corrections modestly improve earthquake amplitude predictions, explosion amplitudes are not well matched, and so P/S ratios do not necessarily improve. Further work is needed to better understand the uses and limitation of 2D path corrections for local P/S ratios.

REGIONAL SEISMIC CHEMICAL AND NUCLEAR EXPLOSION DISCRIMINATION: WESTERN U.S. EXAMPLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walter, W R; Taylor, S R; Matzel, E

2006-07-07

We continue exploring methodologies to improve regional explosion discrimination using the western U.S. as a natural laboratory. The western U.S. has abundant natural seismicity, historic nuclear explosion data, and widespread mine blasts, making it a good testing ground to study the performance of regional explosion discrimination techniques. We have assembled and measured a large set of these events to systematically explore how to best optimize discrimination performance. Nuclear explosions can be discriminated from a background of earthquakes using regional phase (Pn, Pg, Sn, Lg) amplitude measures such as high frequency P/S ratios. The discrimination performance is improved if the amplitudesmore » can be corrected for source size and path length effects. We show good results are achieved using earthquakes alone to calibrate for these effects with the MDAC technique (Walter and Taylor, 2001). We show significant further improvement is then possible by combining multiple MDAC amplitude ratios using an optimized weighting technique such as Linear Discriminant Analysis (LDA). However this requires data or models for both earthquakes and explosions. In many areas of the world regional distance nuclear explosion data is lacking, but mine blast data is available. Mine explosions are often designed to fracture and/or move rock, giving them different frequency and amplitude behavior than contained chemical shots, which seismically look like nuclear tests. Here we explore discrimination performance differences between explosion types, the possible disparity in the optimization parameters that would be chosen if only chemical explosions were available and the corresponding effect of that disparity on nuclear explosion discrimination. Even after correcting for average path and site effects, regional phase ratios contain a large amount of scatter. This scatter appears to be due to variations in source properties such as depth, focal mechanism, stress drop, in the near source material properties (including emplacement conditions in the case of explosions) and in variations from the average path and site correction. Here we look at several kinds of averaging as a means to try and reduce variance in earthquake and explosion populations and better understand the factors going into a minimum variance level as a function of epicenter (see Anderson ee et al. this volume). We focus on the performance of P/S ratios over the frequency range from 1 to 16 Hz finding some improvements in discrimination as frequency increases. We also explore averaging and optimally combining P/S ratios in multiple frequency bands as a means to reduce variance. Similarly we explore the effects of azimuthally averaging both regional amplitudes and amplitude ratios over multiple stations to reduce variance. Finally we look at optimal performance as a function of magnitude and path length, as these put limits the availability of good high frequency discrimination measures.« less

Evolution of the Structure of Local Regions of Fused Metal in Explosion-Welded Nickel-Aluminum Composites Under Heat Treatment

NASA Astrophysics Data System (ADS)

Shmorgun, V. G.; Bogdanov, A. I.; Gurevich, L. M.

2016-03-01

The methods of electron, optical, and atomic force microscopy are used to study the structure, morphology and phase composition of local regions of fused metal in an explosion-welded nickel-aluminum composite. It is shown that the diffusion zone formed due to the heat treatment repeats the contour of the fuse in the first stage and then "absorbs" it upon duration of the hold thus leveling the phase composition. ANi2Al3 Aluminide layer forms on the side of nickel and a NiAl3 layer forms on the side of aluminum.

Supranova Events from Spun-up Neutron Stars: An Explosion in Search of an Observation

NASA Astrophysics Data System (ADS)

Vietri, Mario; Stella, Luigi

1999-12-01

We consider a formation scenario for supramassive neutron stars (SMNSs) that takes place through mass and angular momentum transfer from a close companion during a low-mass X-ray binary phase, with the ensuing suppression of the magnetic field. After the end of the mass transfer phase, SMNSs will lose, through magnetic dipole radiation, most of their angular momentum, triggering the star's collapse to a black hole. We discuss the rate of occurrence of these collapses and propose that these stars, because of the baryon-clear environment in which the implosion/explosion takes place, are the originators of gamma-ray bursts.

The effect of explosive percentage on underwater explosion energy release of hexanitrohexaazaisowurtzitane and octogen based aluminized explosives

NASA Astrophysics Data System (ADS)

Jiao, Qingjie; Wang, Qiushi; Nie, Jianxin; Guo, Xueyong; Zhang, Wei; Fan, Wenqi

2018-03-01

To control the explosion energy output by optimizing explosive components is a key requirement in a number of different application areas. The effect of different Al/O Ratio on underwater explosion of aluminized explosives has been studied detailedly. However, the effect of explosive percentage in the same Al/O Ratio is rarely researched, especially for Hexanitrohexaazaisowurtzitane (CL-20) based aluminized explosives. In this study, we performed the underwater explosion experiments with 1.2-kilogram explosives in order to investigate the explosion energy released from CL-20 and Octogen (HMX) based aluminized explosives. The percentage of the explosive varied from 5% to 30% and it is shown that: the shockwave peak pressure (pm) grows gradually; shock wave energy (Es) continues increasing, bubble energy (Eb) increases then decreases peaking at 15% for both formulas, and the total energy (E) and energy release rate (η) peak at 20% for CL-20 and 15% for HMX. This paper outlines the physical mechanism of Eb change under the influence of an aluminium initial reaction temperature and reaction active detonation product percentage coupling. The result shows that CL-20 is superior as a new high explosive and has promising application prospects in the regulation of explosive energy output for underwater explosives.

Towards an Empirically Based Parametric Explosion Spectral Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ford, S R; Walter, W R; Ruppert, S

2009-08-31

Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before been tested. The focus of our work is on the local and regional distances (< 2000 km) and phases (Pn, Pg, Sn, Lg) necessary to see small explosions. We are developing a parametric model of the nuclear explosion seismic source spectrum that is compatible with the earthquake-based geometrical spreading and attenuation models developed using the Magnitude Distance Amplitude Correction (MDAC) techniques (Walter and Taylor, 2002). The explosion parametric model will be particularly important in regions without any priormore » explosion data for calibration. The model is being developed using the available body of seismic data at local and regional distances for past nuclear explosions at foreign and domestic test sites. Parametric modeling is a simple and practical approach for widespread monitoring applications, prior to the capability to carry out fully deterministic modeling. The achievable goal of our parametric model development is to be able to predict observed local and regional distance seismic amplitudes for event identification and yield determination in regions with incomplete or no prior history of underground nuclear testing. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.« less

Dynamic Fracture Behavior of Plastic-Bonded Explosives

NASA Astrophysics Data System (ADS)

Fu, Hua; Li, Jun-Ling; Tan, Duo-Wang; Ifp, Caep Team

2011-06-01

Plastic-Bonded Explosives (PBX) are used as important energetic materials in nuclear or conventional weapons. Arms Warhead in the service process and the ballistic phase, may experience complex process such as long pulse and higher loading, compresson, tension and reciprocating compression - tension, friction with the projectile shell, which would lead to explosive deformation and fracture.And the dynamic deformation and fracture behavior of PBX subsequently affect reaction characteristics and initiation mechanism in explosives, then having influence on explosives safety. The dynamic fracure behavior of PBX are generally complex and not well studied or understood. In this paper, the dynamic fracture of explosives are conducted using a Kolsky bar. The Brazilian test, also known as a indirect tensile test or splitting test, is chosen as the test method. Tensile strength under different strain rates are obtained using quartz crystal embedded in rod end. The dynamic deformation and fracture process are captured in real-time by high-speed digital camera, and the displacement and strain fields distribution before specimen fracture are obtained by digital correlation method. Considering the non-uniform microstructure of explosives,the dynamic fracture behavior of explosive are simulated by discrete element method, the simulation results can reproduce the deformation and fracture process in Brazilian test using a maximum tensile strain criterion.

The concurrence of atmospheric rivers and explosive cyclogenesis in the North Atlantic and North Pacific basins

NASA Astrophysics Data System (ADS)

Eiras-Barca, Jorge; Ramos, Alexandre M.; Pinto, Joaquim G.; Trigo, Ricardo M.; Liberato, Margarida L. R.; Miguez-Macho, Gonzalo

2018-01-01

The explosive cyclogenesis of extratropical cyclones and the occurrence of atmospheric rivers are characteristic features of a baroclinic atmosphere, and are both closely related to extreme hydrometeorological events in the mid-latitudes, particularly on coastal areas on the western side of the continents. The potential role of atmospheric rivers in the explosive cyclone deepening has been previously analysed for selected case studies, but a general assessment from the climatological perspective is still missing. Using ERA-Interim reanalysis data for 1979-2011, we analyse the concurrence of atmospheric rivers and explosive cyclogenesis over the North Atlantic and North Pacific basins for the extended winter months (ONDJFM). Atmospheric rivers are identified for almost 80 % of explosive deepening cyclones. For non-explosive cyclones, atmospheric rivers are found only in roughly 40 % of the cases. The analysis of the time evolution of the high values of water vapour flux associated with the atmospheric river during the cyclone development phase leads us to hypothesize that the identified relationship is the fingerprint of a mechanism that raises the odds of an explosive cyclogenesis occurrence and not merely a statistical relationship. These new insights on the relationship between explosive cyclones and atmospheric rivers may be helpful to a better understanding of the associated high-impact weather events.

Hot spine loops and the nature of a late-phase solar flare

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Xudong; Todd Hoeksema, J.; Liu, Yang

2013-12-01

The fan-spine magnetic topology is believed to be responsible for many curious features in solar explosive events. A spine field line links distinct flux domains, but direct observation of such a feature has been rare. Here we report a unique event observed by the Solar Dynamic Observatory where a set of hot coronal loops (over 10 MK) connected to a quasi-circular chromospheric ribbon at one end and a remote brightening at the other. Magnetic field extrapolation suggests that these loops are partly tracers of the evolving spine field line. Continuous slipping- and null-point-type reconnections were likely at work, energizing themore » loop plasma and transferring magnetic flux within and across the fan quasi-separatrix layer. We argue that the initial reconnection is of the 'breakout' type, which then transitioned to a more violent flare reconnection with an eruption from the fan dome. Significant magnetic field changes are expected and indeed ensued. This event also features an extreme-ultraviolet (EUV) late phase, i.e., a delayed secondary emission peak in warm EUV lines (about 2-7 MK). We show that this peak comes from the cooling of large post-reconnection loops beside and above the compact fan, a direct product of eruption in such topological settings. The long cooling time of the large arcades contributes to the long delay; additional heating may also be required. Our result demonstrates the critical nature of cross-scale magnetic coupling—topological change in a sub-system may lead to explosions on a much larger scale.« less

High-speed multi-frame laser Schlieren for visualization of explosive events

NASA Astrophysics Data System (ADS)

Clarke, S. A.; Murphy, M. J.; Landon, C. D.; Mason, T. A.; Adrian, R. J.; Akinci, A. A.; Martinez, M. E.; Thomas, K. A.

2007-09-01

High-Speed Multi-Frame Laser Schlieren is used for visualization of a range of explosive and non-explosive events. Schlieren is a well-known technique for visualizing shock phenomena in transparent media. Laser backlighting and a framing camera allow for Schlieren images with very short (down to 5 ns) exposure times, band pass filtering to block out explosive self-light, and 14 frames of a single explosive event. This diagnostic has been applied to several explosive initiation events, such as exploding bridgewires (EBW), Exploding Foil Initiators (EFI) (or slappers), Direct Optical Initiation (DOI), and ElectroStatic Discharge (ESD). Additionally, a series of tests have been performed on "cut-back" detonators with varying initial pressing (IP) heights. We have also used this Diagnostic to visualize a range of EBW, EFI, and DOI full-up detonators. The setup has also been used to visualize a range of other explosive events, such as explosively driven metal shock experiments and explosively driven microjets. Future applications to other explosive events such as boosters and IHE booster evaluation will be discussed. Finite element codes (EPIC, CTH) have been used to analyze the schlieren images to determine likely boundary or initial conditions to determine the temporal-spatial pressure profile across the output face of the detonator. These experiments are part of a phased plan to understand the evolution of detonation in a detonator from initiation shock through run to detonation to full detonation to transition to booster and booster detonation.

Relaxed structure of typical nitro explosives in the excited state: Observation, implication and application

NASA Astrophysics Data System (ADS)

Chu, Genbai; Yang, Zuhua; Xi, Tao; Xin, Jianting; Zhao, Yongqiang; He, Weihua; Shui, Min; Gu, Yuqiu; Xiong, Ying; Xu, Tao

2018-04-01

Understanding the structural, geometrical, and chemical changes that occur after an electronic excitation is essential to elucidate the inherent mechanism of nitro explosives. Herein, relaxed structures of typical nitro explosives in the lowest singlet excited state are investigated using time-dependent density functional theory. During the excitation process, the nitro group is activated and relaxes via geometrical change. The five explosives RDX, HMX, CL-20, PETN, and LLM-105 exhibit similar relaxed structures, and the impact sensitivity is related to their excitation energy. High-sensitivity δ-HMX has a lower excitation energy for relaxed structure than β-HMX. This study offers novel insight into energetic materials.

Safe arming system for two-explosive munitions

DOEpatents

Jaroska, Miles F.; Niven, William A.; Morrison, Jasper J.

1978-01-01

A system for safely and positively detonating high-explosive munitions, including a source of electrical signals, a split-phase square-loop transformer responsive solely to a unique series of signals from the source for charging an energy storage circuit through a voltage doubling circuit, and a spark-gap trigger for initiating discharge of the energy in the storage circuit to actuate a detonator and thereby fire the munitions.

Template-directed synthesis of silica nanotubes for explosive detection.

PubMed

Yildirim, Adem; Acar, Handan; Erkal, Turan S; Bayindir, Mehmet; Guler, Mustafa O

2011-10-01

Fluorescent porous organic-inorganic thin films are of interest of explosive detection because of their vapor phase fluorescence quenching property. In this work, we synthesized fluorescent silica nanotubes using a biomineralization process through self-assembled peptidic nanostructures. We designed and synthesized an amyloid-like peptide self-assembling into nanofibers to be used as a template for silica nanotube formation. The amine groups on the peptide nanofibrous system were used for nucleation of silica nanostructures. Silica nanotubes were used to prepare highly porous surfaces, and they were doped with a fluorescent dye by physical adsorption for explosive sensing. These porous surfaces exhibited fast, sensitive, and highly selective fluorescence quenching against nitro-explosive vapors. The materials developed in this work have vast potential in sensing applications due to enhanced surface area. © 2011 American Chemical Society

Rg-Lg coupling as a Lg-wave excitation mechanism

NASA Astrophysics Data System (ADS)

Ge, Z.; Xie, X.

2003-12-01

Regional phase Lg is predominantly comprised of shear wave energy trapped in the crust. Explosion sources are expected to be less efficient for excitation of Lg phases than earthquakes to the extent that the source can be approximated as isotropic. Shallow explosions generate relatively large surface wave Rg compared to deeper earthquakes, and Rg is readily disrupted by crustal heterogeneity. Rg energy may thus scatter into trapped crustal S-waves near the source region and contribute to low-frequency Lg wave. In this study, a finite-difference modeling plus the slowness analysis are used for investigating the above mentioned Lg-wave excitation mechanism. The method allows us to investigate near source energy partitioning in multiple domains including frequency, slowness and time. The main advantage of this method is that it can be applied at close range, before Lg is actually formed, which allows us to use very fine near source velocity model to simulate the energy partitioning process. We use a layered velocity structure as the background model and add small near source random velocity patches to the model to generate the Rg to Lg coupling. Two types of simulations are conducted, (1) a fixed shallow explosion source vs. randomness at different depths and (2) a fixed shallow randomness vs. explosion sources at different depths. The results show apparent couplings between the Rg and Lg waves at lower frequencies (0.3-1.5 Hz). A shallow source combined with shallow randomness generates the maximum Lg-wave, which is consistent with the Rg energy distribution of a shallow explosion source. The Rg energy and excited Lg energy show a near linear relationship. The numerical simulation and slowness analysis suggest that the Rg to Lg coupling is an effective excitation mechanism for low frequency Lg-waves from a shallow explosion source.

Explosion Source Location Study Using Collocated Acoustic and Seismic Networks in Israel

NASA Astrophysics Data System (ADS)

Pinsky, V.; Gitterman, Y.; Arrowsmith, S.; Ben-Horin, Y.

2013-12-01

We explore a joined analysis of seismic and infrasonic signals for improvement in automatic monitoring of small local/regional events, such as construction and quarry blasts, military chemical explosions, sonic booms, etc. using collocated seismic and infrasonic networks recently build in Israel (ISIN) in the frame of the project sponsored by the Bi-national USA-Israel Science Foundation (BSF). The general target is to create an automatic system, which will provide detection, location and identification of explosions in real-time or close-to-real time manner. At the moment the network comprises 15 stations hosting a microphone and seismometer (or accelerometer), operated by the Geophysical Institute of Israel (GII), plus two infrasonic arrays, operated by the National Data Center, Soreq: IOB in the South (Negev desert) and IMA in the North of Israel (Upper Galilee),collocated with the IMS seismic array MMAI. The study utilizes a ground-truth data-base of numerous Rotem phosphate quarry blasts, a number of controlled explosions for demolition of outdated ammunitions and experimental surface explosions for a structure protection research, at the Sayarim Military Range. A special event, comprising four military explosions in a neighboring country, that provided both strong seismic (up to 400 km) and infrasound waves (up to 300 km), is also analyzed. For all of these events the ground-truth coordinates and/or the results of seismic location by the Israel Seismic Network (ISN) have been provided. For automatic event detection and phase picking we tested the new recursive picker, based on Statistically optimal detector. The results were compared to the manual picks. Several location techniques have been tested using the ground-truth event recordings and the preliminary results obtained have been compared to the ground-truth locations: 1) a number of events have been located as intersection of azimuths estimated using the wide-band F-K analysis technique applied to the infrasonic phases of the two distant arrays; 2) a standard robust grid-search location procedure based on phase picks and a constant celerity for a phase (tropospheric or stratospheric) was applied; 3) a joint coordinate grid-search procedure using array waveforms and phase picks was tested, 4) the Bayesian Infrasonic Source Localization (BISL) method, incorporating semi-empirical model-based prior information, was modified for array+network configuration and applied to the ground-truth events. For this purpose we accumulated data of the former observations of the air-to-ground infrasonic phases to compute station specific ground-truth Celerity-Range Histograms (ssgtCRH) and/or model-based CRH (mbCRH), which allow to essentially improve the location results. For building the mbCRH the local meteo-data and the ray-tracing modeling in 3 available azimuth ranges, accounting seasonal variations of winds directivity (quadrants North:315-45, South: 135-225, East 45-135) have been used.

Liquid-phase explosive crystallization of electron-beam-evaporated a-Si films induced by flash lamp annealing

NASA Astrophysics Data System (ADS)

Ohdaira, Keisuke; Matsumura, Hideki

2013-01-01

We succeed in the formation of micrometer-order-thick polycrystalline silicon (poly-Si) films through the flash-lamp-induced liquid-phase explosive crystallization (EC) of precursor a-Si films prepared by electron-beam (EB) evaporation. The velocity of the explosive crystallization (vEC) is estimated to be ˜14 m/s, which is close to the velocity of the liquid-phase epitaxy (LPE) of Si at a temperature around the melting point of a-Si of 1418 K. Poly-Si films formed have micrometer-order-long grains stretched along a lateral crystallization direction, and X-ray diffraction (XRD) and electron diffraction pattern measurements reveal that grains in poly-Si films tend to have a particular orientation. These features are significantly different from our previous results: the formation of poly-Si films containing randomly-oriented 10-nm-sized fine grains formed from a-Si films prepared by catalytic chemical vapor deposition (Cat-CVD) or sputtering. One possible reason for the emergence of a different EC mode in EB-evaporated a-Si films is the suppression of solid-phase nucleation (SPN) during Flash Lamp Annealing (FLA) due to tensile stress which precursor a-Si films originally hold. Poly-Si films formed from EB-evaporated a-Si films would contribute to the realization of high-efficiency thin-film poly-Si solar cells because of large and oriented grains.

Real time recognition of explosophorous group and explosive material using laser induced photoacoustic spectroscopy associated with novel algorithm for time and frequency domain analysis.

PubMed

El-Sharkawy, Yasser H; Elbasuney, Sherif

2018-06-07

Energy-rich bonds such as nitrates (NO 3 - ) and percholorates (ClO 4 - ) have an explosive nature; they are frequently encountered in high energy materials. These bonds encompass two highly electronegative atoms competing for electrons. Common explosive materials including urea nitrate, ammonium nitrate, and ammonium percholorates were subjected to photoacoustic spectroscopy. The captured signal was processed using novel digital algorithm designed for time and frequency domain analysis. Frequency domain analysis offered not only characteristic frequencies for NO 3 - and ClO 4 - groups; but also characteristic fingerprint spectra (based on thermal, acoustical, and optical properties) for different materials. The main outcome of this study is that phase-shift domain analysis offered an outstanding signature for each explosive material, with novel discrimination between explosive and similar non-explosive material. Photoacoustic spectroscopy offered different characteristic signatures that can be employed for real time detection with stand-off capabilities. There is no two materials could have the same optical, thermal, and acoustical properties. Copyright © 2018 Elsevier B.V. All rights reserved.

Textural evolution of magma during the 9.4-ka trachytic explosive eruption at Kilian Volcano, Chaîne des Puys, France

NASA Astrophysics Data System (ADS)

Colombier, M.; Gurioli, L.; Druitt, T. H.; Shea, T.; Boivin, P.; Miallier, D.; Cluzel, N.

2017-02-01

Textural parameters such as density, porosity, pore connectivity, permeability, and vesicle size distributions of vesiculated and dense pyroclasts from the 9.4-ka eruption of Kilian Volcano, were quantified to constrain conduit and eruptive processes. The eruption generated a sequence of five vertical explosions of decreasing intensity, producing pyroclastic density currents and tephra fallout. The initial and final phases of the eruption correspond to the fragmentation of a degassed plug, as suggested by the increase of dense juvenile clasts (bimodal density distributions) as well as non-juvenile clasts, resulting from the reaming of a crater. In contrast, the intermediate eruptive phases were the results of more open-conduit conditions (unimodal density distributions, decreases in dense juvenile pyroclasts, and non-juvenile clasts). Vesicles within the pyroclasts are almost fully connected; however, there are a wide range of permeabilities, especially for the dense juvenile clasts. Textural analysis of the juvenile clasts reveals two vesiculation events: (1) an early nucleation event at low decompression rates during slow magma ascent producing a population of large bubbles (>1 mm) and (2) a syn-explosive nucleation event, followed by growth and coalescence of small bubbles controlled by high decompression rates immediately prior to or during explosive fragmentation. The similarities in pyroclast textures between the Kilian explosions and those at Soufrière Hills Volcano on Montserrat, in 1997, imply that eruptive processes in the two systems were rather similar and probably common to vulcanian eruptions in general.

Identification and evolution of the juvenile component in 2004-2005 Mount St. Helens ash: Chapter 29 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

USGS Publications Warehouse

Rowe, Michael C.; Thornber, Carl R.; Kent, Adam J.R.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

2008-01-01

Petrologic studies of volcanic ash are commonly used to identify juvenile volcanic material and observe changes in the composition and style of volcanic eruptions. During the 2004-5 eruption of Mount St. Helens, recognition of the juvenile component in ash produced by early phreatic explosions was complicated by the presence of a substantial proportion of 1980-86 lava-dome fragments and glassy tephra, in addition to older volcanic fragments possibly derived from crater debris. In this report, we correlate groundmass textures and compositions of glass, mafic phases, and feldspar from 2004-5 ash in an attempt to identify juvenile material in early phreatic explosions and to distinguish among the various processes that generate and distribute ash. We conclude that clean glass in the ash is derived mostly from nonjuvenile sources and is not particularly useful for identifying the proportion of juvenile material in ash samples. High Li contents (>30 μg/g) in feldspars provide a useful tracer for juvenile material and suggest an increase in the proportion of the juvenile component between October 1 and October 4, 2004, before the emergence of hot dacite on the surface of the crater on October 11, 2004. The presence of Li-rich feldspar out of equilibrium (based on Liplagioclase/melt partitioning) with groundmass and bulk dacite early in the eruption also suggests vapor enrichment in the initially erupted dacite. If an excess vapor phase was, indeed, present, it may have provided a catalyst to initiate the eruption. Textural and compositional comparisons between dome fault gouge and the ash produced by rockfalls, rock avalanches, and vent explosions indicate that the fault gouge is a likely source of ash particles for both types of events. Comparison of the ash from vent explosions and rockfalls suggests that the fault gouge and new dome were initially heterogeneous, containing a mixture of conduit and crater debris and juvenile material, but became increasingly homogeneous, dominated by juvenile material, by early January 2005.

Optimization of biological and instrumental detection of explosives and ignitable liquid residues including canines, SPME/ITMS and GC/MSn

NASA Astrophysics Data System (ADS)

Furton, Kenneth G.; Harper, Ross J.; Perr, Jeannette M.; Almirall, Jose R.

2003-09-01

A comprehensive study and comparison is underway using biological detectors and instrumental methods for the rapid detection of ignitable liquid residues (ILR) and high explosives. Headspace solid phase microextraction (SPME) has been demonstrated to be an effective sampling method helping to identify active odor signature chemicals used by detector dogs to locate forensic specimens as well as a rapid pre-concentration technique prior to instrumental detection. Common ignitable liquids and common military and industrial explosives have been studied including trinitrotoluene, tetryl, RDX, HMX, EGDN, PETN and nitroglycerine. This study focuses on identifying volatile odor signature chemicals present, which can be used to enhance the level and reliability of detection of ILR and explosives by canines and instrumental methods. While most instrumental methods currently in use focus on particles and on parent organic compounds, which are often involatile, characteristic volatile organics are generally also present and can be exploited to enhance detection particularly for well-concealed devices. Specific examples include the volatile odor chemicals 2-ethyl-1-hexanol and cyclohexanone, which are readily available in the headspace of the high explosive composition C-4; whereas, the active chemical cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) is not. The analysis and identification of these headspace 'fingerprint' organics is followed by double-blind dog trials of the individual components using certified teams in an attempt to isolate and understand the target compounds to which dogs are sensitive. Studies to compare commonly used training aids with the actual target explosive have also been undertaken to determine their suitability and effectiveness. The optimization of solid phase microextraction (SPME) combined with ion trap mobility spectrometry (ITMS) and gas chromatography/mass spectrometry/mass spectrometry (GC/MSn) is detailed including interface development and comparisons of limits of detection. These instrumental methods are being optimized in order to detect the same target odor chemicals used by detector dogs to reliably locate explosives and ignitable liquids.

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 4. Final report, October 1993-January 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas selected to conduct further environmental analysis. A total of 310 soil samples were collected from the five areas and 13 specific high explosive test sites. The samples were screened for semi-volatile organic compounds, PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were performed and no explosives ormore » degradation products were identified. Semi-volatile organic compounds were in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels, and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 3. Final report, October 1993-January 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas were selected to conduct further environmental analysis. A total of 310 soil samples were collected from the five areas and 13 specific high explosive test sites. The samples were screened for semi-volatile organic compounds, PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were and no explosives ormore » degradation products were identified. Semi-volatile organic compounds were in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels, and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 1. Final report, October 1993-January 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas were selected to conduct further environmental analysis. A total of 310 soil samples were collected from the and 13 specific high explosive test sites. The samples were screened for semi-volatile organic PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were and no explosives or degradation products weremore » identified. Semi-volatile organic compounds were in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels, and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

Phase II. Environmental baseline survey of McCormick Ranch, Kirtland Air Force Base, New Mexico. Part 5. Final report, October 1993-January 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagaraty, G.; Johnson, J.; Middlebrooks, P.

The Phase II EBS results document the extent of environmental contamination believed to be present on McCormick Ranch. Explosive test areas having the greatest potential for containing soil contaminants were identified using several geophysical survey methods: EM 31 terrain conductivity meter, magnetometer/gradiometer, and ground penetrating radar. From the geophysical surveys, five areas were selected to conduct further environmental analysis. A total of 310 soil samples were collected from the areas and 13 specific high explosive test sites. The samples were screened for semi-volatile organic compounds, PETN, TNT, TNT-degradation products, nitrates and radioactivity. Laboratory analyses were performed and no explosives ormore » degradation products were identified. Semi-volatile organic compounds were in 2 samples, manganese was detected in 3 samples, nitrates were discovered below soil action levels and radiation levels were below background. Consequently, it is unlikely that significant contamination exists.« less

Critical exponents of the explosive percolation transition

NASA Astrophysics Data System (ADS)

da Costa, R. A.; Dorogovtsev, S. N.; Goltsev, A. V.; Mendes, J. F. F.

2014-04-01

In a new type of percolation phase transition, which was observed in a set of nonequilibrium models, each new connection between vertices is chosen from a number of possibilities by an Achlioptas-like algorithm. This causes preferential merging of small components and delays the emergence of the percolation cluster. First simulations led to a conclusion that a percolation cluster in this irreversible process is born discontinuously, by a discontinuous phase transition, which results in the term "explosive percolation transition." We have shown that this transition is actually continuous (second order) though with an anomalously small critical exponent of the percolation cluster. Here we propose an efficient numerical method enabling us to find the critical exponents and other characteristics of this second-order transition for a representative set of explosive percolation models with different number of choices. The method is based on gluing together the numerical solutions of evolution equations for the cluster size distribution and power-law asymptotics. For each of the models, with high precision, we obtain critical exponents and the critical point.

Understanding metastable phase transformation during crystallization of RDX, HMX and CL-20: experimental and DFT studies.

PubMed

Ghosh, Mrinal; Banerjee, Shaibal; Shafeeuulla Khan, Md Abdul; Sikder, Nirmala; Sikder, Arun Kanti

2016-09-14

Multiphase growth during crystallization severely affects deliverable output of explosive materials. Appearance and incomplete transformation of metastable phases are a major source of polymorphic impurities. This article presents a methodical and molecular level understanding of the metastable phase transformation mechanism during crystallization of cyclic nitramine explosives, viz. RDX, HMX and CL-20. Instantaneous reverse precipitation yielded metastable γ-HMX and β-CL-20 which undergo solution mediated transformation to the respective thermodynamic forms, β-HMX and ε-CL-20, following 'Ostwald's rule of stages'. However, no metastable phase, anticipated as β-RDX, was evidenced during precipitation of RDX, which rather directly yielded the thermodynamically stable α-phase. The γ→β-HMX and β→ε-CL-20 transformations took 20 and 60 minutes respectively, whereas formation of α-RDX was instantaneous. Density functional calculations were employed to identify the possible transition state conformations and to obtain activation barriers for transformations at wB97XD/6-311++G(d,p)(IEFPCM)//B3LYP/6-311G(d,p) level of theory. The computed activation barriers and lattice energies responsible for transformation of RDX, HMX and CL-20 metastable phases to thermodynamic ones conspicuously supported the experimentally observed order of phase stability. This precise result facilitated an understanding of the occurrence of a relatively more sensitive and less dense β-CL-20 phase in TNT based melt-cast explosive compositions, a persistent and critical problem unanswered in the literature. The crystalline material recovered from such compositions revealed a mixture of β- and ε-CL-20. However, similar compositions of RDX and HMX never showed any metastable phase. The relatively long stability with the highest activation barrier is believed to restrict complete β→ε-CL-20 transformation during processing. Therefore a method is suggested to overcome this issue.

Comparing eruptions of varying intensity at Kilauea via melt inclusion analysis

NASA Astrophysics Data System (ADS)

Ferguson, D. J.; Plank, T. A.; Hauri, E. H.; Houghton, B. F.; Gonnermann, H. M.; Swanson, D. A.; Blaser, A. P.

2013-12-01

Over the past 500 years explosive summit eruptions from Kilauea volcano, Hawaii, have exhibited a range of eruption magnitudes, from large basaltic sub-plinian events to Hawaiian lava fountains of various intensity. Knowledge of the factors controlling such dramatic changes in explosivity and mass discharge rate is vital for understanding the dynamics of explosive basaltic magma systems, but these remain poorly constrained. At Kilauea this information also has important implications for hazard assessment, as future eruptions may be far larger than those observed historically. To investigate the processes associated with eruptions of varying magnitudes we have analyzed the composition and dissolved volatile contents (H2O-CO2-S-Cl-F) of olivine-hosted melt inclusions, sampled from tephra deposits associated with three eruptions of different sizes: a moderate lava-fountain (1959 Episode of Kilauea Iki); an exceptionally high lava-fountain (1500 CE Keanakāko'i reticulite) and a basaltic sub-plinian eruption (1650 CE Keanakāko'i layer 6 scoria). Over this time period (~500 years) we find no major shifts in the major element composition of primary melts feeding the Kilauea magmatic system, and melt inclusions from all eruptions record similar maximum water (~0.7 wt% H2O) and CO2 (~300 ppm) contents, regardless of eruption magnitude. Co-variations between other volatile species, such as CO2 and S, do not support a role for excess volatiles (i.e. CO2) in the larger eruptions via ';gas-fluxing'. Our data therefore suggests that major shifts in eruptive magnitude are unlikely to be linked to either changes in the primary volatile content of the melts or excess gas supplied by open-system degassing of deeper melts. Rather we find evidence for significant variations in the shallow degassing behavior of magmas associated with the larger Keanakāko'i eruptions (sub-plinian and strong lava-fountaining events) compared to that from less vigorous moderate Kilauea Iki lava-fountaining events. On plots of CO2 versus H2O, Kilauea Iki MI's record volatile contents consistent with equilibrium degassing of magma rising from a depth of ~3 km. In contrast, the volatile contents of melts from the more explosive eruptions appear to be strongly affected by degassing processes at shallow depths (< 300 m), indicating variations in the ascent and storage of melts over this time-period. These changes in storage conditions may be linked to variations in the depth of the summit caldera, which was significantly greater during the older more explosive eruptive phases.

Report for borehole explosion data acquired in the 1999 Los Angeles Region Seismic Experiment (LARSE II), Southern California; Part II, Data tables and plots

USGS Publications Warehouse

Murphy, Janice M.; Fuis, Gary S.; Okaya, D.A.; Thygesen, Kristina; Baher, Shirley A.; Rybert, Trond; Kaip, Galen; Fort, Michael D.; Asudeh, Isa; Sell, Russell

2002-01-01

The Los Angeles Region Seismic Experiment (LARSE), a joint project of the U.S. Geological Survey (USGS) and the Southern California Earthquake Center (SCEC), was conducted to produce seismic images of the subsurface in the Los Angeles region. Primary targets were major fault systems and sedimentary basins; the goal of the project was to address the earthquake hazard posed by these geologic features. The first phase of data collection (LARSE 1) was completed in 1994; the second phase (LARSE 2) was completed in 1999. A description of the 1999 survey and an overview of both phase I and II is given in Fuis and others (2001). In this report, we present the technical details for the explosion data collected in 1999.

New possibilities to analyse non-standard explosives and post blast residues in forensic practice

NASA Astrophysics Data System (ADS)

Kotrlý, Marek; Turková, Ivana

2005-05-01

Nonstandard and home-made explosives always pose a considerable threat for security forces in terms of their practically unlimited variability, both in composition and in construction of explosive devises. Electron microscopy - SEM with EDS/WDS is one of the key techniques for an analysis of non-standard explosives and post-blast residues. If the amount of materials allows it, a number of other analytical techniques are utilized, such as XRD that is capable of a direct phase identification of a crystalline substance, namely in mixtures. TLC has constantly proved itself useful for laboratory screening. Furthermore, combinations of FTIR, Raman spectrometry, LC MS, GC MS, XRF, micro XRF and other ones are applied. In the case of identification of post-blast residues, where an investigation is often conducted at the level of separate microscopic particles, the role of SEM is unsubstitutable, whereas the analysis of the organic phase from these often sporadic microparticles has been infeasible until recently. One of the very interesting options appears to be Raman spectrometry technique, which is nowadays obtainable as a supplement to SEM EDX. Newly available is the device that is fully confocal, SEM keeps full functionality and scan range, very high resolution (for green laser resolution 360nm FWHM; 430nm Rayleigh), it is fitted with high quality objective lens, enhances mapping through Raman spectrometry in a volume 250μm x 250μm x 250μm by piezo driven scanner (capacitive feedback linearized) and obtaining a high quality white light image (250μm x 250μm) immediately in the SEM chamber. This technique is currently undergoing intensive testing and it seems that the method could significantly help to address issues with the analysis of organic phases in electron microscopy not only in the case of post-blast residues and explosives.

APTS and rGO co-functionalized pyrenated fluorescent nanonets for representative vapor phase nitroaromatic explosive detection

NASA Astrophysics Data System (ADS)

Guo, Linjuan; Zu, Baiyi; Yang, Zheng; Cao, Hongyu; Zheng, Xuefang; Dou, Xincun

2014-01-01

For the first time, flexible PVP/pyrene/APTS/rGO fluorescent nanonets were designed and synthesized via a one-step electrospinning method to detect representative subsaturated nitroaromatic explosive vapor. The functional fluorescent nanonets, which were highly stable in air, showed an 81% quenching efficiency towards TNT vapor (~10 ppb) with an exposure time of 540 s at room temperature. The nice performance of the nanonets was ascribed to the synergistic effects induced by the specific adsorption properties of APTS, the fast charge transfer properties and the effective π-π interaction with pyrene and TNT of rGO. Compared to the analogues of TNT, the PVP/pyrene/APTS/rGO nanonets showed notable selectivity towards TNT and DNT vapors. The explored functionalization method opens up brand new insight into sensitive and selective detection of vapor phase nitroaromatic explosives.For the first time, flexible PVP/pyrene/APTS/rGO fluorescent nanonets were designed and synthesized via a one-step electrospinning method to detect representative subsaturated nitroaromatic explosive vapor. The functional fluorescent nanonets, which were highly stable in air, showed an 81% quenching efficiency towards TNT vapor (~10 ppb) with an exposure time of 540 s at room temperature. The nice performance of the nanonets was ascribed to the synergistic effects induced by the specific adsorption properties of APTS, the fast charge transfer properties and the effective π-π interaction with pyrene and TNT of rGO. Compared to the analogues of TNT, the PVP/pyrene/APTS/rGO nanonets showed notable selectivity towards TNT and DNT vapors. The explored functionalization method opens up brand new insight into sensitive and selective detection of vapor phase nitroaromatic explosives. Electronic supplementary information (ESI) available: Vapor pressure of TNT and its analogues, fluorescence quenching kinetics, fluorescence quenching efficiencies and additional SEM images. See DOI: 10.1039/c3nr04960d

Broadband seismology and the detection and verification of underground nuclear explosions

NASA Astrophysics Data System (ADS)

Tinker, Mark Andrew

1997-10-01

On September 24, 1996, President Clinton signed the Comprehensive Test Ban Treaty (CTBT), which bans the testing of all nuclear weapons thereby limiting their future development. Seismology is the primary tool used for the detection and identification of underground explosions and thus, will play a key role in monitoring a CTBT. The detection and identification of low yield explosions requires seismic stations at regional distances (<1500 km). However, because the regional wavefield propagates within the extremely heterogeneous crustal waveguide, the seismic waveforms are also very complicated. Therefore, it is necessary to have a solid understanding of how the phases used in regional discriminants develop within different tectonic regimes. Thus, the development of the seismic phases Pn and Lg, which compose the seismic discriminant Pn/Lg, within the western U.S. from the Non-Proliferation Experiment are evaluated. The most fundamental discriminant is event location as 90% of all seismic sources occur too deep within the earth to be unnatural. France resumed its nuclear testing program after a four year moratorium and conducted six tests during a five month period starting in September of 1995. Using teleseismic data, a joint hypocenter determination algorithm was used to determine the hypocenters of these six explosions. One of the most important problems in monitoring a CTBT is the detection and location of small seismic events. Although seismic arrays have become the central tool for event detection, in the context of a global monitoring treaty, there will be some dependence on sparse regional networks of three-component broadband seismic stations to detect low yield explosions. However, the full power of the data has not been utilized, namely using phases other than P and S. Therefore, the information in the surface wavetrain is used to improve the locations of small seismic events recorded on a sparse network in Bolivia. Finally, as a discrimination example in a complex region, P to S ratios are used to determine source parameters of the Msb{w} 8.3 deep Bolivia earthquake.

Preparation of graphene by electrical explosion of graphite sticks.

PubMed

Gao, Xin; Xu, Chunxiao; Yin, Hao; Wang, Xiaoguang; Song, Qiuzhi; Chen, Pengwan

2017-08-03

Graphene nanosheets were produced by electrical explosion of high-purity graphite sticks in distilled water at room temperature. The as-prepared samples were characterized by various techniques to find different forms of carbon phases, including graphite nanosheets, few-layer graphene, and especially, mono-layer graphene with good crystallinity. Delicate control of energy injection is critical for graphene nanosheet formation, whereas mono-layer graphene was produced under the charging voltage of 22.5-23.5 kV. On the basis of electrical wire explosion and our experimental results, the underlying mechanism that governs the graphene generation was carefully illustrated. This work provides a simple but innovative route for producing graphene nanosheets.

Investigation of the Explosive Potential of the Hybrid Propellant Combinations N2O4/PBAN and CTF/PBAN

DTIC Science & Technology

1967-03-01

nitrogen tetroxide (N„0 ) and polybutadyne-aluminum (PBAN), and chlorine trifluoride (CTF) and PBAN. This program consisted of a series of eight...explosive potential of two hybrid propellant combinations; nitrogen tetroxide QLOL) and polybutadyne - aluminum (PBAN) and chlorine triflouride (CTF...or positive-phase impulse yield. FREE AIR OVERPRESSURE: (OR FREE FIELD OVERPRESSURE): The unreflected pressure, in excess of the ambient atmospheric

Volatile Transport by Volcanic Plumes on Earth, Venus and Mars

NASA Technical Reports Server (NTRS)

Glaze, Lori S.; Self, Stephen; Baloga, Steve; Stofan, Ellen R.

2012-01-01

Explosive volcanic eruptions can produce sustained, buoyant columns of ash and gas in the atmosphere (Fig. 1). Large flood basalt eruptions may also include significant explosive phases that generate eruption columns. Such eruptions can transport volcanic volatiles to great heights in the atmosphere. Volcanic eruption columns can also redistribute chemical species within the atmosphere by entraining ambient atmosphere at low altitudes and releasing those species at much higher altitudes.

Hydrodynamic Modeling of Air Blast Propagation from the Humble Redwood Chemical High Explosive Detonations Using GEODYN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chipman, V D

Two-dimensional axisymmetric hydrodynamic models were developed using GEODYN to simulate the propagation of air blasts resulting from a series of high explosive detonations conducted at Kirtland Air Force Base in August and September of 2007. Dubbed Humble Redwood I (HR-1), these near-surface chemical high explosive detonations consisted of seven shots of varying height or depth of burst. Each shot was simulated numerically using GEODYN. An adaptive mesh refinement scheme based on air pressure gradients was employed such that the mesh refinement tracked the advancing shock front where sharp discontinuities existed in the state variables, but allowed the mesh to sufficientlymore » relax behind the shock front for runtime efficiency. Comparisons of overpressure, sound speed, and positive phase impulse from the GEODYN simulations were made to the recorded data taken from each HR-1 shot. Where the detonations occurred above ground or were shallowly buried (no deeper than 1 m), the GEODYN model was able to simulate the sound speeds, peak overpressures, and positive phase impulses to within approximately 1%, 23%, and 6%, respectively, of the actual recorded data, supporting the use of numerical simulation of the air blast as a forensic tool in determining the yield of an otherwise unknown explosion.« less

Dynamic planar solid phase microextraction-ion mobility spectrometry for rapid field air sampling and analysis of illicit drugs and explosives.

PubMed

Guerra-Diaz, Patricia; Gura, Sigalit; Almirall, José R

2010-04-01

A preconcentration device that targets the volatile chemical signatures associated with illicit drugs and explosives (high and low) has been designed to fit in the inlet of an ion mobility spectrometer (IMS). This is the first reporting of a fast and sensitive method for dynamic sampling of large volumes of air using planar solid phase microextraction (PSPME) incorporating a high surface area for absorption of analytes onto a sol-gel polydimethylsiloxane (PDMS) coating for direct thermal desorption into an IMS. This device affords high extraction efficiencies due to strong retention properties at ambient temperature, resulting in the detection of analyte concentrations in the parts per trillion range when as low as 3.5 L of air are sampled over the course of 10 s (absolute mass detection of less than a nanogram). Dynamic PSPME was used to sample the headspace over the following: 3,4-methylenedioxymethamphetamine (MDMA) tablets resulting in the detection of 12-40 ng of piperonal, high explosives (Pentolite) resulting in the detection of 0.6 ng of 2,4,6-trinitrotoluene (TNT), and low explosives (several smokeless powders) resulting in the detection of 26-35 ng of 2,4-dinitrotoluene (2,4-DNT) and 11-74 ng of diphenylamine (DPA).

State relations for a two-phase mixture of reacting explosives and applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kubota, Shiro; Saburi, Tei; Ogata, Yuji

2007-10-15

To assess the assumptions behind the two phase mixture rule for reacting explosives, the shock-to-detonation transition process was calculated for high explosives using a finite difference method. An ignition and growth model and the Jones-Wilkins-Lee (JWL) equations of state were employed. The simple mixture rule assumes that the reacting explosive is a simple mixture of the reactant and product components. Four different assumptions, such as that of thermal equilibrium and isotropy, were adopted to calculate the pressure. The main purpose of this paper is to present the answer to the question of why the numerical results of shock-initiation are insensitivemore » to the assumptions adopted. The equations of state for reactants and products were assessed by considering plots of the specific internal energy E and specific volume V. If the slopes of the constant-pressure lines for both components in the E-V plane are almost the same, it is demonstrated that the numerical results are insensitive to the assumptions adopted. We have found that the relation for the specific volumes of the two components can be approximately expressed by a single curve of the specific volume of the reactant vs that of the products. We discuss this relationship in terms of the results of the numerical simulation. (author)« less

Shock Interaction of Metal Particles in Condensed Explosive Detonation

NASA Astrophysics Data System (ADS)

Ripley, Robert; Zhang, Fan; Lien, Fue-Sang

2005-07-01

For detonation propagation in a condensed explosive with metal particles, a macro-scale physical model describing the momentum transfer between the explosive and particles has yet to be completely established. Previous 1D and 2D meso-scale modeling studies indicated that significant momentum transfer from the explosive to the particles occurs as the leading shock front crosses the particles, thus influencing the initiation and detonation structure. In this work, 3D meso-scale modeling is conducted to further study the two-phase momentum transfer during the shock diffraction and subsequent detonation in liquid nitromethane containing packed metal particles. Detonation of the condensed explosive is computed using an Arrhenius reaction model and a hybrid EOS model that combines the Mie-Gruneisen equation for reactants and the JWL equation for products. The compressible particles are modeled using the Tait EOS, where the material strength is negligible. The effect of particle packing configuration and inter-particle spacing is shown by parametric studies. Finally, a physical description of the momentum transfer is discussed.

The Averno 2 fissure eruption: a recent small-size explosive event at the Campi Flegrei Caldera (Italy)

NASA Astrophysics Data System (ADS)

di Vito, Mauro Antonio; Arienzo, Ilenia; Braia, Giuseppe; Civetta, Lucia; D'Antonio, Massimo; di Renzo, Valeria; Orsi, Giovanni

2011-04-01

The Averno 2 eruption (3,700 ± 50 a B.P.) was an explosive low-magnitude event characterized by magmatic and phreatomagmatic explosions, generating mainly fall and surge beds, respectively. It occurred in the Western sector of the Campi Flegrei caldera (Campanian Region, South Italy) at the intersection of two active fault systems, oriented NE and NW. The morphologically complex crater area, largely filled by the Averno lake, resulted from vent activation and migration along the NE-trending fault system. The eruption generated a complex sequence of pyroclastic deposits, including pumice fall deposits in the lower portion, and prevailing surge beds in the intermediate-upper portion. The pyroclastic sequence has been studied through stratigraphical, morphostructural and petrological investigations, and subdivided into three members named A through C. Member A was emplaced during the first phase of the eruption mainly by magmatic explosions which generated columns reaching a maximum height of 10 km. During this phase the eruption reached its climax with a mass discharge rate of 3.2 106 kg/s. Intense fracturing and fault activation favored entry of a significant amount of water into the system, which produced explosions driven by variably efficient water-magma interaction. These explosions generated wet to dry surge deposits that emplaced Member B and C, respectively. Isopachs and isopleths maps, as well as areal distribution of ballistic fragments and facies variation of surge deposits allow definition of four vents that opened along a NE oriented, 2 km long fissure. The total volume of magma extruded during the eruption has been estimated at about 0.07 km3 (DRE). The erupted products range in composition from initial, weakly peralkaline alkali-trachyte, to last-emplaced alkali-trachyte. Isotopic data and modeling suggest that mixing occurred during the Averno 2 eruption between a more evolved, less radiogenic stored magma, and a less evolved, more radiogenic magma that entered the shallow reservoir to trigger the eruption. The early phases of the eruption, during which the vent migrated from SW to the center of the present lake, were fed by the more evolved, uppermost magma, while the following phases extruded the less evolved, lowermost magma. Integration of the geological and petrological results suggests that the Averno 2 complex eruption was fed from a dyke-shaped shallow reservoir intruded into the NE-SW fault system bordering to the west the La Starza resurgent block, within the caldera floor.

Metal and polymer melt jet formation by the high-power laser ablation

NASA Astrophysics Data System (ADS)

Yoh, Jack J.; Gojani, Ardian B.

2010-02-01

The laser-induced metal and polymer melt jets are studied experimentally. Two classes of physical phenomena of interest are: first, the process of explosive phase change of laser induced surface ablation and second, the hydrodynamic jetting of liquid melts ejected from a beamed spot. We focus on the dynamic link between these two distinct physical phenomena in a framework of forming and patterning of metallic and polymer jets using a high-power Nd:YAG laser. The microexplosion of ablative spot on a target first forms a pocket of hot liquid melt and then it is followed by a sudden volume change of gas-liquid mixture leading to a pressure-induced spray jet ejection into surrounding medium.

Explosives detection and identification using surface plasmon-coupled emission

NASA Astrophysics Data System (ADS)

Ja, Shiou-Jyh

2012-06-01

To fight against the explosives-related threats in defense and homeland security applications, a smarter sensing device that not only detects but differentiates multiple true threats from false positives caused by environmental interferents is essential. A new optical detection system is proposed to address these issues by using the temporal and spectroscopic information generated by the surface plasmon coupling emission (SPCE) effect. Innovative SPCE optics have been designed using Zemax software to project the fluorescence signal into clear "rainbow rings" on a CCD with subnanometer wavelength resolution. The spectroscopic change of the fluorescence signal and the time history of such changes due to the presence of a certain explosive analyte are unique and can be used to identify explosives. Thanks to high optical efficiency, reporter depositions as small as 160-μm in diameter can generate a sufficient signal, allowing a dense array of different reporters to be interrogated with wavelength multiplexing and detect a wide range of explosives. We have demonstrated detection and classification of explosives, such as TNT, NT, NM, RDX, PETN, and AN, with two sensing materials in a prototype.

Phase Stability of Epsilon and Gamma HNIW (CL-20) at High-Pressure and Temperature

NASA Astrophysics Data System (ADS)

Gump, Jared

2007-06-01

Hexanitrohexaazaisowurtzitane (CL-20) is one of the few ingredients developed since World War II to be considered for transition to military use. Five polymorphs have been identified for CL-20 by FTIR measurements (α, β, γ, ɛ, and ζ). As CL-20 is transitioned into munitions it will become necessary to predict its response under conditions of detonation, for performance evaluation. Such predictive modeling requires a phase diagram and basic thermodynamic properties of the various phases at high pressure and temperature. Theoretical calculations have been performed for a variety of explosive ingredients including CL-20, but it was noted that no experimental measurements existed for comparison with the theoretical bulk modulus calculated for CL-20. Therefore, the phase stabilities of epsilon and gamma CL-20 at static high-pressure and temperature were investigated using synchrotron angle-dispersive x-ray diffraction experiments. The samples were compressed and heated using diamond anvil cells (DAC). Pressures and temperatures achieved were around 5GPa and 175^oC, respectively. No phase change (from the starting epsilon phase) was observed under hydrostatic compression up to 6.3 GPa at ambient temperature. Under ambient pressure the epsilon phase was determined to be stable to a temperature of 120^oC. When heating above 125^oC the gamma phase appeared and it remained stable until thermal decomposition occurred above 150^oC. The gamma phase exhibits a phase change upon compression at both ambient temperature and 140^oC. Pressure -- volume data for the epsilon and gamma phase at ambient temperature and the epsilon phase at 75^oC were fit to the Birch-Murnaghan formalism to obtain isothermal equations of state.

Product-sum universality and Rushbrooke inequality in explosive percolation

NASA Astrophysics Data System (ADS)

Sabbir, M. M. H.; Hassan, M. K.

2018-05-01

We study explosive percolation (EP) on an Erdös-Rényi network for product rule (PR) and sum rule (SR). Initially, it was claimed that EP describes discontinuous phase transition; now it is well accepted as a probabilistic model for thermal continuous phase transition (CPT). However, no model for CPT is complete unless we know how to relate its observable quantities with those of thermal CPT. To this end, we define entropy and specific heat, redefine susceptibility, and show that they behave exactly like their thermal counterparts. We obtain the critical exponents ν ,α ,β , and γ numerically and find that both PR and SR belong to the same universality class and obey Rushbrooke inequality.

Explosion Generated Seismic Waves and P/S Methods of Discrimination from Earthquakes with Insights from the Nevada Source Physics Experiments

NASA Astrophysics Data System (ADS)

Walter, W. R.; Ford, S. R.; Pitarka, A.; Pyle, M. L.; Pasyanos, M.; Mellors, R. J.; Dodge, D. A.

2017-12-01

The relative amplitudes of seismic P-waves to S-waves are effective at identifying underground explosions among a background of natural earthquakes. These P/S methods appear to work best at frequencies above 2 Hz and at regional distances ( >200 km). We illustrate this with a variety of historic nuclear explosion data as well as with the recent DPRK nuclear tests. However, the physical basis for the generation of explosion S-waves, and therefore the predictability of this P/S technique as a function of path, frequency and event properties such as size, depth, and geology, remains incompletely understood. A goal of current research, such as the Source Physics Experiments (SPE), is to improve our physical understanding of the mechanisms of explosion S-wave generation and advance our ability to numerically model and predict them. The SPE conducted six chemical explosions between 2011 and 2016 in the same borehole in granite in southern Nevada. The explosions were at a variety of depths and sizes, ranging from 0.1 to 5 tons TNT equivalent yield. The largest were observed at near regional distances, with P/S ratios comparable to much larger historic nuclear tests. If we control for material property effects, the explosions have very similar P/S ratios independent of yield or magnitude. These results are consistent with explosion S-waves coming mainly from conversion of P- and surface waves, and are inconsistent with source-size based models. A dense sensor deployment for the largest SPE explosion allowed this conversion to be mapped in detail. This is good news for P/S explosion identification, which can work well for very small explosions and may be ultimately limited by S-wave detection thresholds. The SPE also showed explosion P-wave source models need to be updated for small and/or deeply buried cases. We are developing new P- and S-wave explosion models that better match all the empirical data. Historic nuclear explosion seismic data shows that the media in which the explosion takes place is quite important. These material property effects can surprisingly degrade the seismic waveform correlation of even closely spaced explosions in different media. The next phase of the SPE will contrast chemical explosions in dry alluvium with the prior SPE explosions in granite and historic nuclear tests in a variety of media.

Analysis of Vulnerability Around The Colima Volcano, MEXICO

NASA Astrophysics Data System (ADS)

Carlos, S. P.

2001-12-01

The Colima volcano located in the western of the Trasmexican Volcanic Belt, in the central portion of the Colima Rift Zone, between the Mexican States of Jalisco and Colima. The volcano since January of 1998 presents a new activity, which has been characterized by two stages: the first one was an effusive phase that begin on 20 November 1998 and finish by the middle of January 1999. On February 10of 1999 a great explosion in the summit marked the beginning of an explosive phase, these facts implies that the eruptive process changes from an effusive model to an explosive one. Suárez-Plascencia et al, 2000, present hazard maps to ballistic projectiles, ashfalls and lahars for this scenario. This work presents the evaluation of the vulnerability in the areas identified as hazardous in the maps for ballistic, ashfalls and lahars, based on the economic elements located in the middle and lower sections of the volcano building, like agriculture, forestry, agroindustries and communication lines (highways, power, telephonic, railroad, etc). The method is based in Geographic Information Systems, using digital cartography scale 1:50,000, digital orthophotos from the Instituto Nacional de Estadística, Geografía e Informática, SPOT and Landsat satellite images from 1997 and 2000 in the bands 1, 2 and 3. The land use maps obtained for 1997 and 2000, were compared with the land use map reported by Suárez in 1992, from these maps an increase of the 5 porcent of the sugar cane area and corn cultivations were observed compared of those of 1990 (1225.7 km2) and a decrease of the forest surface, moving the agricultural limits uphill, and showing also some agave cultivation in the northwest and north hillslopes of the Nevado de Colima. This increment of the agricultural surface results in bigger economic activity in the area, which makes that the vulnerability also be increased to different volcanic products emitted during this phase of activity. The degradation of the soil by the agriculture and forestry, mainly in the east hillslope of the volcano is another factor that generate remoulded material that in the event of an extraordinary rainsfall during an explosive events, could increase the size of the lahar or generate flows of mud that may affect the towns, villages (like Atenquique, which has been affected in 1957 by a large lahar), and could generate strong damages to the communication lines affecting distant places as Guadalajara city and the Port of Manzanillo.

2500 pyroclast puzzle: probing eruptive scenarios at Volcán de Colima, Mexico

NASA Astrophysics Data System (ADS)

Kueppers, U.; Varley, N. R.; Alatorre-Ibarguengoitia, M. A.; Lavallee, Y.; Becker, S.; Berninger, N.; Goldstein, F.; Hanson, J. B.; Kolzenburg, S.; Dingwell, D. B.

2009-12-01

The Colima volcanic complex is comprised by two edifices, the extinct Nevado de Colima to the North and the active Fuego de Colima in the South. Since 1998, a dome-building phase has shown repeated shifts between lava effusion and short-lived explosive activity. Lava extrusion rates were usually low leading to the build-up of domes inside the crater but occasionally, lava spilled over the crater rim and flowed down the flanks. This effusive activity was usually associated with several ash explosions and gas exhalation events per day. In 2005, occasional block-and-ash flows from dome-collapse events travelled down the Western flanks and reached La Lumbre valley. Later that year, violent explosive eruptions destroyed the dome and sent pyroclastic flows to valleys in the South (Monte Grande) and South-East (La Arena). The transition from effusive to short-lived but highly explosive eruptive behaviour presents an interesting opportunity to study pyroclastic flow deposits from different generating mechanisms. Gas at overpressure in bubbly magma is one of the main driving forces of explosive eruptions. The change of the physical properties of evolved magmas after the fragmentation is minor. Therefore, a detailed characterisation of volcanic products reveals much information and is vital for a correct understanding of volcanic deposits. Comparing different units allows constraining the bandwidth of possible eruptive scenarios. Here, we thoroughly characterized the deposits of the above described events on site. In the field, we 1) measured the density distribution of 100 surficial juvenile and lithic clasts at 24 localities (1 * 1 m) across the length and width of the pyroclastic flow deposits; 2) sieved the matrix (approx. 30 * 30 * 30 cm) at each locality; and 3) created detailed stratigraphic logs. We observe a lower mean density and a greater variance for clasts generated by the explosive eruption. Our results highlight the different origin of the 2005 deposits on Colima. Ergo, the physical properties of eruptive products allow the constraining of eruptive scenarios and may help to better interpret volcanic deposits that have not been eye-witnessed.

Phase Diagram of Ammonium Nitrate

NASA Astrophysics Data System (ADS)

Dunuwille, Mihindra; Yoo, Choong-Shik

2013-06-01

Ammonium Nitrate (AN) has often been subjected to uses in improvised explosive devices, due to its wide availability as a fertilizer and its capability of becoming explosive with slight additions of organic and inorganic compounds. Yet, the origin of enhanced energetic properties of impure AN (or AN mixtures) is neither chemically unique nor well understood - resulting in rather catastrophic disasters in the past1 and thereby a significant burden on safety, in using ammonium nitrates even today. To remedy this situation, we have carried out an extensive study to investigate the phase stability of AN, in different chemical environments, at high pressure and temperature, using diamond anvil cells and micro-Raman spectroscopy. The present results confirm the recently proposed phase IV-to-IV' transition above 15 GPa2 and provide new constraints for the melting and phase diagram of AN to 40 GPa and 673 K. The present study has been supported by the U.S. DHS under Award Number 2008-ST-061-ED0001.

The awakening of a classical nova from hibernation.

PubMed

Mróz, Przemek; Udalski, Andrzej; Pietrukowicz, Paweł; Szymański, Michał K; Soszyński, Igor; Wyrzykowski, Łukasz; Poleski, Radosław; Kozłowski, Szymon; Skowron, Jan; Ulaczyk, Krzysztof; Skowron, Dorota; Pawlak, Michał

2016-09-29

Cataclysmic variable stars-novae, dwarf novae, and nova-likes-are close binary systems consisting of a white dwarf star (the primary) that is accreting matter from a low-mass companion star (the secondary). From time to time such systems undergo large-amplitude brightenings. The most spectacular eruptions, with a ten-thousandfold increase in brightness, occur in classical novae and are caused by a thermonuclear runaway on the surface of the white dwarf. Such eruptions are thought to recur on timescales of ten thousand to a million years. In between, the system's properties depend primarily on the mass-transfer rate: if it is lower than a billionth of a solar mass per year, the accretion becomes unstable and the matter is dumped onto the white dwarf during quasi-periodic dwarf nova outbursts. The hibernation hypothesis predicts that nova eruptions strongly affect the mass-transfer rate in the binary, keeping it high for centuries after the event. Subsequently, the mass-transfer rate should significantly decrease for a thousand to a million years, starting the hibernation phase. After that the nova awakes again-with accretion returning to the pre-eruption level and leading to a new nova explosion. The hibernation model predicts cyclical evolution of cataclysmic variables through phases of high and low mass-transfer. The theory gained some support from the discovery of ancient nova shells around the dwarf novae Z Camelopardalis and AT Cancri, but direct evidence for considerable mass-transfer changes prior, during and after nova eruptions has not hitherto been found. Here we report long-term observations of the classical nova V1213 Cen (Nova Centauri 2009) covering its pre- and post-eruption phases and precisely documenting its evolution. Within the six years before the explosion, the system revealed dwarf nova outbursts indicative of a low mass-transfer rate. The post-nova is two orders of magnitude brighter than the pre-nova at minimum light with no trace of dwarf nova behaviour, implying that the mass-transfer rate increased considerably as a result of the nova explosion.

Spectroscopic characterization of nitroaromatic landmine signature explosives

NASA Astrophysics Data System (ADS)

Hernandez-Rivera, Samuel P.; Manrique-Bastidas, Cesar A.; Blanco, Alejandro; Primera, Oliva M.; Pacheco, Leonardo C.; Castillo-Chara, Jairo; Castro, Miguel E.; Mina, Nairmen

2004-09-01

TNT and DNT are important explosives used as base charges of landmines and other explosive devices. They are often combined with RDX in specific explosive formulations. Their detection in vapor phase as well as in soil in contact with the explosives is important in landmine detection technology. The spectroscopic signatures of nitroaromatic compounds in neat forms: crystals, droplets, and recrystallized samples were determined by Raman Microspectroscopy (RS), Fourier Transform Infrared Microscopy (FTIR) and Fiber Optics Coupled - Fourier Transform Infrared Spectroscopy (FOC-FTIR) using a grazing angle (GA) probe. TNT exhibits a series of characteristic bands: vibrational signatures, which allow its detection in soil. The spectroscopic signature of neat TNT is dominated by strong bands about 1380 and 2970 cm-1. The intensity and position of these bands were found remarkably different in soil samples spiked with TNT. The 1380 cm-1 band is split into a number of bands in that region. The 2970 cm-1 band is reduced in intensity and new bands are observed about 2880 cm-1. The results are consistent with a different chemical environment of TNT in soil as compared to neat TNT. Interactions were found to be dependent on the physical source of the explosive. In the case of DNT-sand interactions, shifts in vibrational frequencies of the explosives as well as the substrates were found.

Multicale modeling of the detonation of aluminized explosives using SPH-MD-QM method

NASA Astrophysics Data System (ADS)

Peng, Qing; Wang, Guangyu; Liu, Gui-Rong; de, Suvranu

Aluminized explosives have been applied in military industry since decades ago. Compared with ideal explosives, aluminized explosives feature both fast detonation and slow metal combustion chemistry, generating a complex multi-phase reactive flow. Here, we introduce a sequential multiscale model of SPH-MD-QM to simulate the detonation behavior of aluminized explosives. At the bottom level, first-principles quantum mechanics (QM) calculations are employed to obtain the training sets for fitting the ReaxFF potentials, which are used in turn in the reactive molecular dynamics (MD) simulations in the middle level to obtain the chemical reaction rates and equations of states. At the up lever, a smooth particle hydrodynamics (SPH) method incorporated ignition and growth model and afterburning model has been used for the simulation of the detonation and combustion of the aluminized explosive. Simulation is compared with experiment and good agreement is observed. The proposed multiscale method of SPH-MD-QM could be used to optimize the performance of aluminized explosives. The authors would like to acknowledge the generous financial support from the Defense Threat Reduction Agency (DTRA) Grant No. HDTRA1-13-1-0025 and the Office of Naval Research Grants ONR Award No. N00014-08-1-0462 and No. N00014-12-1-0527.

Shock induced shear strength in an HMX based plastic bonded explosive

NASA Astrophysics Data System (ADS)

Millett, J. C. F.; Taylor, P.; Appleby-Thomas, G.

2017-01-01

The shock induced mechanical response of an HMX based plastic bonded explosive (PBX) has been investigated in terms of the shear strength. Results show that shear strength increases with impact stress. However comparison with the calculated elastic response of both the PBX and pure HMX suggests that the overall mechanical response is controlled by the HMX crystals, with the near liquid like nature of the binder phase having a minimal contribution.

Infrasound Observation of the Apparent North Korean Nuclear Test of 25 May 2009

NASA Astrophysics Data System (ADS)

Jeon, J.; Che, I.; Kim, T.; Lee, H.

2009-12-01

On 25 May 2009, a seismic event (mb 4.6) was recorded from a source in northeastern North Korea, close to the location of a previous seismic event on 9 October 2006. Both events have been declared to be nuclear tests. Five seismo-acoustic arrays in South Korea recorded epicentral infrasonic signals for the more recent test following the strong seismic waves from the explosion. This study describes the characteristics of the nuclear test-generated infrasound signals observed at infrasound arrays located from 304 to 528 km from the source. The signals were characterized by stratospheric returns with amplitudes from 0.16 to 0.35 microbar and dominant frequencies between 1.0 and 4.3 Hz. Celerities determined for the arrivals suggest that most of the infrasonic energy travelled as a stratospheric phase. The inferred infrasonic location was offset about 15.7 km from the reference seismic location. On the basis of observed amplitudes of the stratospheric phases and corrections based on prevailing winds, the epicentral infrasonic energy was estimated to be equivalent to that expected from about 2.2 ton surface detonation of conventional explosives. We conclude that this small energy estimate is related to the partitioning of the contained explosive energy resulting from the interaction of strong ground motion at the surface with the atmosphere rather than the direct transfer of explosion energy to the air. This relatively small energy ratio between the infrasonic energy and the seismic energy could be used to distinguish the event from a common surface explosion.

Recognizing explosion sites with a self-organizing network for unsupervised learning

NASA Astrophysics Data System (ADS)

Tarvainen, Matti

1999-06-01

A self-organizing neural network model has been developed for identifying mining explosion locations in different environments in Finland and adjacent areas. The main advantage of the method is its ability to automatically find a suitable network structure and naturally correctly identify explosions as such. The explosion site recognition was done using extracted waveform attributes of various kind event records from the small-aperture array FINESS in Finland. The recognition was done by using P-S phase arrival differences and rough azimuth estimates to provide a first robust epicentre location. This, in turn, leads to correct mining district identification where more detailed tuning was performed using different phase amplitude and signal-to-noise attributes. The explosions studied here originated in mines and quarries located in Finland, coast of Estonia and in the St. Petersburg area, Russia. Although the Helsinki bulletins in 1995 and 1996 listed 1649 events in these areas, analysis was restricted to the 380 (ML≥2) events which, besides, were found in the reviewed event bulletins (REB) of the CTBTO/UN prototype international data centre (pIDC) in Arlington, VA, USA. These 380 events with different attributes were selected for the learning stage. Because no `ground-truth' information was available the corresponding mining, `code' coordinates used earlier to compile Helsinki bulletins were utilized instead. The novel self-organizing method was tested on 18 new event recordings in the mentioned area in January-February 1997, out of which 15 were connected to correct mines. The misconnected three events were those which did not have all matching attributes in the self-organizing maps (SOMs) network.

Carbon solids in oxygen-deficient explosives (LA-UR-13-21151)

NASA Astrophysics Data System (ADS)

Peery, Travis

2013-06-01

The phase behavior of excess carbon in oxygen-deficient explosives has a significant effect on detonation properties and product equations of state. Mixtures of fuel oil in ammonium nitrate (ANFO) above a stoichiometric ratio demonstrate that even small amounts of graphite, on the order of 5% by mole fraction, can substantially alter the Chapman-Jouget (CJ) state properties, a central ingredient in modeling the products equation of state. Similar effects can be seen for Composition B, which borders the carbon phase boundary between graphite and diamond. Nano-diamond formation adds complexity to the product modeling because of surface adsorption effects. I will discuss these carbon phase issues in our equation of state modeling of detonation products, including our statistical mechanics description of carbon clustering and surface chemistry to properly treat solid carbon formation. This work is supported by the Advanced Simulation and Computing Program, under the NNSA.

Using Geo-Data Corporately on the Response Phase of Emergency Management

NASA Astrophysics Data System (ADS)

Demir Ozbek, E.; Ates, S.; Aydinoglu, A. C.

2015-08-01

Response phase of emergency management is the most complex phase in the entire cycle because it requires cooperation between various actors relating to emergency sectors. A variety of geo-data is needed at the emergency response such as; existing data provided by different institutions and dynamic data collected by different sectors at the time of the disaster. Disaster event is managed according to elaborately defined activity-actor-task-geodata cycle. In this concept, every activity of emergency response is determined with Standard Operation Procedure that enables users to understand their tasks and required data in any activity. In this study, a general conceptual approach for disaster and emergency management system is developed based on the regulations to serve applications in Istanbul Governorship Provincial Disaster and Emergency Directorate. The approach is implemented to industrial facility explosion example. In preparation phase, optimum ambulance locations are determined according to general response time of the ambulance to all injury cases in addition to areas that have industrial fire risk. Management of the industrial fire case is organized according to defined actors, activities, and working cycle that describe required geo-data. A response scenario was prepared and performed for an industrial facility explosion event to exercise effective working cycle of actors. This scenario provides using geo-data corporately between different actors while required data for each task is defined to manage the industrial facility explosion event. Following developing web technologies, this scenario based approach can be effective to use geo-data on the web corporately.

A Risk Management Framework to Characterize Black Swan Risks: A Case Study of Lightning Effects on Insensitive High Explosives

NASA Astrophysics Data System (ADS)

Sanders, Gary A.

Effective and efficient risk management processes include the use of high fidelity modeling and simulation during the concept exploration phase as part of the technology and risk assessment activities, with testing and evaluation tasks occurring in later design development phases. However, some safety requirements and design architectures may be dominated by the low probability/high consequence "Black Swan" vulnerabilities that require very early testing to characterize and efficiently mitigate. Failure to address these unique risks has led to catastrophic systems failures including the space shuttle Challenger, Deepwater Horizon, Fukushima nuclear reactor, and Katrina dike failures. Discovering and addressing these risks later in the design and development process can be very costly or even lead to project cancellation. This paper examines the need for risk management process adoption of early hazard phenomenology testing to inform the technical risk assessment, requirements definition and conceptual design. A case study of the lightning design vulnerability of the insensitive high explosives being used in construction, mining, demolition, and defense industries will be presented to examine the impact of this vulnerability testing during the concept exploration phase of the design effort. While these insensitive high explosives are far less sensitive to accidental initiation by fire, impact, friction or even electrical stimuli, their full range of sensitivities have not been characterized and ensuring safe engineering design and operations during events such as lightning storms requires vulnerability testing during the risk assessment phase.

Design and fabrication of optical chemical sensor for detection of nitroaromatic explosives based on fluorescence quenching of phenol red immobilized poly(vinyl alcohol) membrane.

PubMed

Zarei, Ali Reza; Ghazanchayi, Behnam

2016-04-01

The present study developed a new optical chemical sensor for detection of nitroaromatic explosives in liquid phase. The method is based on the fluorescence quenching of phenol red as fluorophore in a poly(vinyl alcohol) (PVA) membrane in the presence of nitroaromatic explosives as quenchers, e.g., 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), 4-nitrotoluene (4-NT), 2,4,6-trinitrobenzene (TNB), and nitrobenzene (NB). For chemical immobilization of phenol red in PVA, phenol red reacted with formaldehyde to produce hydroxymethyl groups and then attached to PVA membrane through the hydroxymethyl groups. The optical sensor showed strong quenching of nitroaromatic explosives. A Stern-Volmer graph for each explosive was constructed and showed that the range of concentration from 5.0 × 10(-6) to 2.5 × 10(-4) mol L(-1) was linear for each explosive and sensitivity varied as TNB >TNT>2,4-DNT>NB>4-NT. The response time of the sensor was within 1 min. The proposed sensor showed good reversibility and reproducibility. Copyright © 2015 Elsevier B.V. All rights reserved.

Small-Scale Thermal Violence Cook Off Test

NASA Astrophysics Data System (ADS)

Cook, Malcolm; Curtis, John; Stennett, Christopher

2015-06-01

The Small-Scale thermal Violence Test (SSVT) is designed to quantify the violence (explosiveness) of test materials by means of observing the velocity history of a metal burst disk that forms one end of a strong thick-walled cylindrical test vehicle. A copper heating block is placed to the rear of, but in contact with, the sample and provides sealing. The difference in thermal conductivity between copper and steel is sufficient that thermal runaway is induced near to the explosive / copper interface in an unlagged test. A series of experiments has been made, in which explosive specimens were confined and heated to explosion. A high-accuracy velocity measurement system was used to record the motion of the bursting disk. These experiments have shown that the early-time motion of the bursting disk corresponds qualitatively to the onset of thermal explosion and growth of reaction within the explosive specimens. However, the velocity history traces are more complex than had been anticipated. In particular, unexplained shoulders were observed in the Phase-Doppler Velocimeter (PDV) data. Some preliminary modelling studies have been carried out in order to shed light on the complex shapes of the projectile velocity histories.

Progressing the analysis of Improvised Explosive Devices: Comparative study for trace detection of explosive residues in handprints by Raman spectroscopy and liquid chromatography.

PubMed

Zapata, Félix; de la Ossa, Mª Ángeles Fernández; Gilchrist, Elizabeth; Barron, Leon; García-Ruiz, Carmen

2016-12-01

Concerning the dreadful global threat of terrorist attacks, the detection of explosive residues in biological traces and marks is a current need in both forensics and homeland security. This study examines the potential of Raman microscopy in comparison to liquid chromatography (ion chromatography (IC) and reversed-phase high performance liquid chromatography (RP-HPLC)) to detect, identify and quantify residues in human handmarks of explosives and energetic salts commonly used to manufacture Improvised Explosive Devices (IEDs) including dynamite, ammonium nitrate, single- and double-smokeless gunpowders and black powder. Dynamite, ammonium nitrate and black powder were detected through the identification of the energetic salts by Raman spectroscopy, their respective anions by IC, and organic components by RP-HPLC. Smokeless gunpowders were not detected, either by Raman spectroscopy or the two liquid chromatography techniques. Several aspects of handprint collection, sample treatment and a critical comparison of the identification of compounds by both techniques are discussed. Raman microscopy and liquid chromatography were shown to be complementary to one another offering more comprehensive information for trace explosives analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

The spatial distribution patterns of condensed phase post-blast explosive residues formed during detonation.

PubMed

Abdul-Karim, Nadia; Blackman, Christopher S; Gill, Philip P; Karu, Kersti

2016-10-05

The continued usage of explosive devices, as well as the ever growing threat of 'dirty' bombs necessitates a comprehensive understanding of particle dispersal during detonation events in order to develop effectual methods for targeting explosive and/or additive remediation efforts. Herein, the distribution of explosive analytes from controlled detonations of aluminised ammonium nitrate and an RDX-based explosive composition were established by systematically sampling sites positioned around each firing. This is the first experimental study to produce evidence that the post-blast residue mass can distribute according to an approximate inverse-square law model, while also demonstrating for the first time that distribution trends can vary depending on individual analytes. Furthermore, by incorporating blast-wave overpressure measurements, high-speed imaging for fireball volume recordings, and monitoring of environmental conditions, it was determined that the principle factor affecting all analyte dispersals was the wind direction, with other factors affecting specific analytes to varying degrees. The dispersal mechanism for explosive residue is primarily the smoke cloud, a finding which in itself has wider impacts on the environment and fundamental detonation theory. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Small explosions interrupt 3-year quiescence at Mount St. Helens, Washington

USGS Publications Warehouse

Myers, B.

1992-01-01

These ash-producing explosions are part of a series of at least 28 explosion-like seismic events that began on August 24, 989. Seismic signals from these events resemble those associated with confirmed ash-producing explosions in April-May 1986. Yet not all of the 1989-1991 events produced ash plumes. Excellent visual observations during four of the events indicated that neither a steam nor ash plume was generated. There is little information about the other events because they occurred when the mountain was not visible, nor was there physical evidence of ashfall or surface changes when scientists visited the crater days to weeks alter. Considerable deformation of the north side of the dome occurred during the series of explosion-like seismic events. Sections of the dome slumped northward and two new vents were formed. However, monitoring the changes associated with individual events was often impossible because several key electronic-distance-meter (EDM) targets and tiltmeters were destroyed by the series of events. 

Response of two-phase droplets to intense electromagnetic radiation

NASA Technical Reports Server (NTRS)

Spann, James F.; Maloney, Daniel J.; Lawson, William F.; Casleton, Kent H.

1993-01-01

The behavior of two-phase droplets subjected to high intensity radiation pulses is studied. Droplets are highly absorbing solids in weakly absorbing liquid medium. The objective of the study was to define heating thresholds required for causing explosive boiling and secondary atomization of the fuel droplet. The results point to mechanisms for energy storage and transport in two-phase systems.

Multi-Sensor Data Fusion Project

DTIC Science & Technology

2000-02-28

seismic network by detecting T phases generated by underground events ( generally earthquakes ) and associating these phases to seismic events. The...between underwater explosions (H), underground sources, mostly earthquake - generated (7), and noise detections (N). The phases classified as H are the only...processing for infrasound sensors is most similar to seismic array processing with the exception that the detections are based on a more sophisticated

49 CFR 176.156 - Defective packages.

Code of Federal Regulations, 2010 CFR

2010-10-01

... packages. (a) No leaking, broken, or otherwise defective package containing Class 1 (explosive) materials.... (b) No Class 1 (explosive) material, which for any reason has deteriorated or undergone a change of...

The hard start phenomena in hypergolic engines. Volume 5: RCS engine deformation and destruct tests

NASA Technical Reports Server (NTRS)

Miron, Y.; Perlee, H. E.

1974-01-01

Tests were conducted to determine the causes of Apollo Reaction Control (RCS) engine failures. Stainless steel engines constructed for use in the destructive tests are described. The tests conducted during the three phase investigation are discussed. It was determined that the explosive reaction that destroys the RCS engines occurs at the time of engine ignition and is apparently due to either the detonation of the heterogeneous constituents of the rocket engine, consisting primarily of unreacted propellant droplets and vapors, and/or the detonation of explosive materials accumulated on the engine walls from previous pulses. Photographs of the effects of explosions on the simulated RCS engines are provided.

Detection of circumstellar material in a normal type Ia supernova.

PubMed

Patat, F; Chandra, P; Chevalier, R; Justham, S; Podsiadlowski, Ph; Wolf, C; Gal-Yam, A; Pasquini, L; Crawford, I A; Mazzali, P A; Pauldrach, A W A; Nomoto, K; Benetti, S; Cappellaro, E; Elias-Rosa, N; Hillebrandt, W; Leonard, D C; Pastorello, A; Renzini, A; Sabbadin, F; Simon, J D; Turatto, M

2007-08-17

Type Ia supernovae are important cosmological distance indicators. Each of these bright supernovae supposedly results from the thermonuclear explosion of a white dwarf star that, after accreting material from a companion star, exceeds some mass limit, but the true nature of the progenitor star system remains controversial. Here we report the spectroscopic detection of circumstellar material in a normal type Ia supernova explosion. The expansion velocities, densities, and dimensions of the circumstellar envelope indicate that this material was ejected from the progenitor system. In particular, the relatively low expansion velocities suggest that the white dwarf was accreting material from a companion star that was in the red-giant phase at the time of the explosion.

Identification of improvised explosives residues using physical-chemical analytical methods under real conditions after an explosion

NASA Astrophysics Data System (ADS)

Kotrlý, Marek; Mareš, Bohumil; Turková, Ivana; Beroun, Ivo

2016-05-01

Within the analysis of cases relating to the use of explosives for crimes, we have experienced a shift from using industrial explosives towards substances made in amateur and illegal way. Availability of industrial explosives is increasingly limited to a narrow sphere of subjects with a relevant permission. Thus, on the part of perpetrators, terrorists, ever greater attention is paid to illegal production of explosives that are easily made from readily available raw materials. Another alarming fact is the availability of information found on the internet. Procedures of preparation are often very simple and do not require even a deeper professional knowledge. Explosive characteristics are not actually accessible for many of these substances (detonation velocity, sensitivity, working capacity, brisance, physical and chemical stability, etc.). Therefore, a project is being implemented, which on grounds of assessment of individual information available in literature and on the internet, aiming at choosing individual areas of potentially abusable substances (e.g. mixtures of nitric acid (98%) with organic substances, mixtures nitromethane and tetranitromethane with organic substances, mixtures of chlorates and perchlorates of alkali metals with organic substances, chemically individual compounds of organic base type of perchloric acid, azides, fulminates, acetylides, picrates, styphnates of heavy metals, etc.). It is directed towards preparation of these explosives also in non-stoichiometric mixtures, conducting test explosives, determination of explosive characteristics (if they are unknown) and analysis of both primary phases and post-blast residues through available analytical techniques, such as gas and liquid chromatography with mass detection, FTIR, micro-Raman spectrometry, electron microscopy with microanalysis and Raman microspectrometry directly in SEM chamber for analysis at the level of individual microparticles. The received characteristics will be used to extend knowledge database for security forces.

Metallic glass formation at the interface of explosively welded Nb and stainless steel

NASA Astrophysics Data System (ADS)

Bataev, I. A.; Hokamoto, K.; Keno, H.; Bataev, A. A.; Balagansky, I. A.; Vinogradov, A. V.

2015-07-01

The interface between explosively welded niobium and stainless steel SUS 304 was studied using scanning electron microscopy, transmission electron microscopy and energy dispersive X-Ray spectroscopy. The wavy interface along which vortex zones were located was observed. The vortex zones formed due to the mixing of materials typically had amorphous structure. Inoue's criteria of glass formation were used to explain this result. The effect of the composition, cooling rate and pressure on the glass formation are discussed. The conditions of deformation, heating, and cooling as well as shockwaves propagation were numerically simulated. We show that the conditions of vortex zone formation resemble the conditions of rapid solidification processes. In contrast to the "classical" methods of rapid solidification of melt, the conditions of metastable phase formation during explosive welding are significantly complicated by the fluctuations of composition and pressure. Possible metastable structures formation at the interface of some common explosively joined materials is predicted.

A verification and validation effort for high explosives at Los Alamos National Lab (u)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scovel, Christina A; Menikoff, Ralph S

2009-01-01

We have started a project to verify and validate ASC codes used to simulate detonation waves in high explosives. Since there are no non-trivial analytic solutions, we are going to compare simulated results with experimental data that cover a wide range of explosive phenomena. The intent is to compare both different codes and different high explosives (HE) models. The first step is to test the products equation of state used for the HE models, For this purpose, the cylinder test, flyer plate and plate-push experiments are being used. These experiments sample different regimes in thermodynamic phase space: the CJ isentropemore » for the cylinder tests, the isentrope behind an overdriven detonation wave for the flyer plate experiment, and expansion following a reflected CJ detonation for the plate-push experiment, which is sensitive to the Gruneisen coefficient. The results of our findings for PBX 9501 are presented here.« less

High pressure-resistant nonincendive emulsion explosive

DOEpatents

Ruhe, Thomas C.; Rao, Pilaka P.

1994-01-01

An improved emulsion explosive composition including hollow microspheres/bulking agents having high density and high strength. The hollow microspheres/bulking agents have true particle densities of about 0.2 grams per cubic centimeter or greater and include glass, siliceous, ceramic and synthetic resin microspheres, expanded minerals, and mixtures thereof. The preferred weight percentage of hollow microspheres/bulking agents in the composition ranges from 3.0 to 10.0 A chlorinated paraffin oil, also present in the improved emulsion explosive composition, imparts a higher film strength to the oil phase in the emulsion. The emulsion is rendered nonincendive by the production of sodium chloride in situ via the decomposition of sodium nitrate, a chlorinated paraffin oil, and sodium perchlorate. The air-gap sensitivity is improved by the in situ formation of monomethylamine perchlorate from dissolved monomethylamine nitrate and sodium perchlorate. The emulsion explosive composition can withstand static pressures to 139 bars and dynamic pressure loads on the order of 567 bars.

Development of explosively driven launcher for meteoroid studies

NASA Technical Reports Server (NTRS)

Baum, D. W.

1973-01-01

The results of a continuing program to develop an explosively driven 2-stage hypervelocity launcher capable of achieving velocities between 15 and 20 km/sec are described. Previous efforts had identified incomplete barrel collapse as a limiting factor in launcher performance. Correlation of experimental and computational results obtained in the present study indicate that boundary-layer gases within the barrel act to prevent complete closure. Simplified calculations suggest that in-contact explosives may have insufficient energy densities to collapse the barrel against a developed boundary layer. Higher energy densities, sufficient to produce complete closure, were obtained with the use of steel flyer plates accelerated by a phased explosive lens. However, when flat flyer plates were impacted on the barrel, the sides of the barrel were observed to rupture and leak gas prior to barrel closure. A promising solution to this problem (untested) is to produce a symmetrical collapse with a cylindrical tube around the barrel.

A Study of Energy Partitioning Using A Set of Related Explosive Formulations

NASA Astrophysics Data System (ADS)

Lieber, Mark; Foster, Joseph C., Jr.; Stewart, D. Scott

2011-06-01

Condensed phase high explosives convert potential energy stored in the electro-magnetic field structure of complex molecules to kinetic energy during the detonation process. This energy is manifest in the internal thermodynamic energy and the translational flow of the products. Historically, the explosive design problem has focused on intramolecular stoichiometry providing prompt reactions based on transport physics at the molecular scale. Modern material design has evolved to approaches that employee intermolecular ingredients to alter the spatial and temporal distribution of energy release. CHEETA has been used to produce data for a set of fictitious explosive formulations based on C-4 to study the partitioning of the available energy between internal and flow energy in the detonation. The equation of state information from CHEETA has been used in ALE3D to develop an understanding of the relationship between variations in the formulation parameters and the internal energy cycle in the products.

Energetic Trend in Explosive Activity of Stromboli

NASA Astrophysics Data System (ADS)

Coltelli, M.; Cristaldi, A.; Mangiagli, S.; Nunnari, G.; Pecora, E.

2003-12-01

The typical activity of Stromboli consists of intermittent mild explosions lasting a few seconds, which take place at different vents and at variable intervals, the most common time interval being 10-20 minutes. However, the routine activity can be interrupted by more violent, paroxysmal explosions, that eject m-sized scoriaceous bombs and lava blocks to a distance of several hundreds of meters from the craters, endangering the numerous tourists that watch the spectacular activity from the volcano's summit located about two hundreds meters from the active vents. On average, 1-2 paroxysmal explosions occurred per year over the past century, but this statistic may be underestimated in absence of continuous monitoring. For this reason from summer 1996 a remote surveillance camera works on Stromboli recording continuously the volcanic activity. It is located on Pizzo Sopra la Fossa, 100 metres above the crater terrace where are the active vents. Using image analysis we seeks to identify any change of the explosive activity trend that could precede a particular eruptive event, like paroxysmal explosions, fire fountains, lava flows. The analysis include the counting of the explosions occurred at the different craters and the parameterization in classes of intensity for each explosion on the base of tephra dispersion and kinetics energy. Associating at each class a corresponding Index of energy in order to compute an heuristic value of the Average Daily Energy Released (ADER) of the explosive activity at Stromboli and plotting this value for each crater versus time, the diagram shows a cyclic behavior with max and min of explosive activity ranging from a few days to a month. Often the craters show opposite trends so when the activity decreases in a crater, increases in the other. Before every paroxysmal explosions recorded, the crater that produced the event decreased and then stopped its activity from a few days to weeks before. The other crater tried to compensate increasing its activity and when it declined the paroxysmal explosion occurred suddenly at the former site. From September 2001 an on-line image analyzer called VAMOS (Volcanic Activity MOnitoring System) operates detection and classification of explosive events in real-time. The system has automatically recorded and analyzed the change in the energetic trend that preceded the 20 October 2001 paroxysmal explosion that killed a woman and the strong explosive activity that preceded the onset of 28 December 2002 lava flow eruption.

Supernova simulations from a 3D progenitor model - Impact of perturbations and evolution of explosion properties

NASA Astrophysics Data System (ADS)

Müller, Bernhard; Melson, Tobias; Heger, Alexander; Janka, Hans-Thomas

2017-11-01

We study the impact of large-scale perturbations from convective shell burning on the core-collapse supernova explosion mechanism using 3D multigroup neutrino hydrodynamics simulations of an 18M⊙ progenitor. Seed asphericities in the O shell, obtained from a recent 3D model of O shell burning, help trigger a neutrino-driven explosion 330 ms after bounce whereas the shock is not revived in a model based on a spherically symmetric progenitor for at least another 300 ms. We tentatively infer a reduction of the critical luminosity for shock revival by ˜ 20 {per cent} due to pre-collapse perturbations. This indicates that convective seed perturbations play an important role in the explosion mechanism in some progenitors. We follow the evolution of the 18M⊙ model into the explosion phase for more than 2 s and find that the cycle of accretion and mass ejection is still ongoing at this stage. With a preliminary value of 7.7 × 1050 erg for the diagnostic explosion energy, a baryonic neutron star mass of 1.85M⊙, a neutron star kick of ˜ 600 km s^{-1} and a neutron star spin period of ˜ 20 ms at the end of the simulation, the explosion and remnant properties are slightly atypical, but still lie comfortably within the observed distribution. Although more refined simulations and a larger survey of progenitors are still called for, this suggests that a solution to the problem of shock revival and explosion energies in the ballpark of observations is within reach for neutrino-driven explosions in 3D.

Volcaniclastic dykes tell on fracturing, explosive eruption and lateral collapse at Stromboli volcano (Italy)

NASA Astrophysics Data System (ADS)

Vezzoli, Luigina; Corazzato, Claudia

2016-05-01

In the upper part of the Stromboli volcano, in the Le Croci and Bastimento areas, two dyke-like bodies of volcanic breccia up to two-metre thick crosscut and intrude the products of Vancori and Neostromboli volcanoes. We describe the lithofacies association of these unusual volcaniclastic dykes, interpret the setting of dyke-forming fractures and the emplacement mechanism of internal deposits, and discuss their probable relationships with the explosive eruption and major lateral collapse events that occurred at the end of the Neostromboli period. The dyke volcaniclastic deposits contain juvenile magmatic fragments (pyroclasts) suggesting a primary volcanic origin. Their petrographic characteristics are coincident with the Neostromboli products. The architecture of the infilling deposits comprises symmetrically-nested volcaniclastic units, separated by sub-vertical boundaries, which are parallel to the dyke margins. The volcanic units are composed of distinctive lithofacies. The more external facies is composed of fine and coarse ash showing sub-vertical laminations, parallel to the contact wall. The central facies comprises stratified, lithic-rich breccia and lapilli-tuff, whose stratification is sub-horizontal and convolute, discordant to the dyke margins. Only at Le Croci dyke, the final unit shows a massive tuff-breccia facies. The volcaniclastic dykes experienced a polyphasic geological evolution comprising three stages. The first phase consisted in fracturing, explosive intrusion related to magma rising and upward injection of magmatic fluids and pyroclasts. The second phase recorded the dilation of fractures and their role as pyroclastic conduits in an explosive eruption possibly coeval with the lateral collapse of the Neostromboli lava cone. Finally, in the third phase, the immediately post-eruption mass-flow remobilization of pyroclastic deposits took place on the volcano slopes.

Magma extrusion during the Ubinas 2013–2014 eruptive crisis based on satellite thermal imaging (MIROVA) and ground-based monitoring

USGS Publications Warehouse

Coppola, Diego; Macedo, Orlando; Ramos, Domingo; Finizola, Anthony; Delle Donne, Dario; del Carpio, Jose; White, Randall A.; McCausland, Wendy; Centeno, Riky; Rivera, Marco; Apaza, Fredy; Ccallata, Beto; Chilo, Wilmer; Cigolini, Corrado; Laiolo, Marco; Lazarte, Ivonne; Machaca, Roger; Masias, Pablo; Ortega, Mayra; Puma, Nino; Taipe, Edú

2015-01-01

After 3 years of mild gases emissions, the Ubinas volcano entered in a new eruptive phase on September 2nd, 2013. The MIROVA system (a space-based volcanic hot-spot detection system), allowed us to detect in near real time the thermal emissions associated with the eruption and provided early evidence of magma extrusion within the deep summit crater. By combining IR data with plume height, sulfur emissions, hot spring temperatures and seismic activity, we interpret the thermal output detected over Ubinas in terms of extrusion rates associated to the eruption. We suggest that the 2013–2014 eruptive crisis can be subdivided into three main phases: (i) shallow magma intrusion inside the edifice, (ii) extrusion and growing of a lava plug at the bottom of the summit crater coupled with increasing explosive activity and finally, (iii) disruption of the lava plug and gradual decline of the explosive activity. The occurrence of the 8.2 Mw Iquique (Chile) earthquake (365 km away from Ubinas) on April 1st, 2014, may have perturbed most of the analyzed parameters, suggesting a prompt interaction with the ongoing volcanic activity. In particular, the analysis of thermal and seismic datasets shows that the earthquake may have promoted the most intense thermal and explosive phase that culminated in a major explosion on April 19th, 2014.These results reveal the efficiency of space-based thermal observations in detecting the extrusion of hot magma within deep volcanic craters and in tracking its evolution. We emphasize that, in combination with other geophysical and geochemical datasets, MIROVA is an essential tool for monitoring remote volcanoes with rather difficult accessibility, like those of the Andes that reach remarkably high altitudes.

30 CFR 75.815 - Disconnect devices.

Code of Federal Regulations, 2011 CFR

2011-07-01

... phase-to-phase voltage of the circuit in which they are installed, and for the full-load current of the... explosion-proof enclosures, must be capable of interrupting the full-load current of the circuit or designed and installed to cause the current to be interrupted automatically prior to the opening of the...

30 CFR 75.815 - Disconnect devices.

Code of Federal Regulations, 2010 CFR

2010-07-01

... phase-to-phase voltage of the circuit in which they are installed, and for the full-load current of the... explosion-proof enclosures, must be capable of interrupting the full-load current of the circuit or designed and installed to cause the current to be interrupted automatically prior to the opening of the...

Plasma parameters of the cathode spot explosive electron emission cell obtained from the model of liquid-metal jet tearing and electrical explosion

NASA Astrophysics Data System (ADS)

Tsventoukh, M. M.

2018-05-01

A model has been developed for the explosive electron emission cell pulse of a vacuum discharge cathode spot that describes the ignition and extinction of the explosive pulse. The pulse is initiated due to hydrodynamic tearing of a liquid-metal jet which propagates from the preceding cell crater boundary and draws the ion current from the plasma produced by the preceding explosion. Once the jet neck has been resistively heated to a critical temperature (˜1 eV), the plasma starts expanding and decreasing in density, which corresponds to the extinction phase. Numerical and analytical solutions have been obtained that describe both the time behavior of the pulse plasma parameters and their average values. For the cell plasma, the momentum per transferred charge has been estimated to be some tens of g cm/(s C), which is consistent with the known measurements of ion velocity, ion erosion rate, and specific recoil force. This supports the model of the pressure-gradient-driven plasma acceleration mechanism for the explosive cathode spot cells. The ohmic electric field within the explosive current-carrying plasma has been estimated to be some tens of kV/cm, which is consistent with the known experimental data on cathode potential fall and explosive cell plasma size. This supports the model that assumes the ohmic nature of the cathode potential fall in a vacuum discharge.

Theory, Solution Methods, and Implementation of the HERMES Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reaugh, John E.; White, Bradley W.; Curtis, John P.

The HERMES (high explosive response to mechanical stimulus) model was developed over the past decade to enable computer simulation of the mechanical and subsequent energetic response of explosives and propellants to mechanical insults such as impacts, perforations, drops, and falls. The model is embedded in computer simulation programs that solve the non-linear, large deformation equations of compressible solid and fluid flow in space and time. It is implemented as a user-defined model, which returns the updated stress tensor and composition that result from the simulation supplied strain tensor change. Although it is multi-phase, in that gas and solid species aremore » present, it is single-velocity, in that the gas does not flow through the porous solid. More than 70 time-dependent variables are made available for additional analyses and plotting. The model encompasses a broad range of possible responses: mechanical damage with no energetic response, and a continuous spectrum of degrees of violence including delayed and prompt detonation. This paper describes the basic workings of the model.« less

Simulation of Deformation, Momentum and Energy Coupling Particles Deformed by Intense Shocks

NASA Astrophysics Data System (ADS)

Lieberthal, B.; Stewart, D. S.; Bdzil, J. B.; Najjar, F. M.; Balachandar, S.; Ling, Y.

2011-11-01

Modern energetic materials have embedded solids and inerts in an explosive matrix. A detonation in condensed phase materials, generates intense shocks that deform particles as the incident shock diffracts around them. The post-shock flow generates a wake behind the particle that is influenced by the shape changes of the particle. The gasdynamic flow in the explosive products and its interaction with the deformation of the particle must be treated simultaneously. Direct numerical simulations are carried out that vary the particle-to-surrounding density and impedance ratios to consider heavier and lighter particle. The vorticity deposited on the interface due to shock interaction with the particle, the resulting particle deformation and the net momentum and energy transferred to the particle, on the acoustic and longer viscous time scale are considered. The LLNL multi-physics hydrodynamic code ALE3D is used to carry out the simulations. BL, DSS and JBB supported by AFRL/RW AF FA8651-10-1-0004 & DTRA, HDTRA1-10-1-0020 Off Campus. FMN's work supported by the U.S. DOE/ LLNL, Contract DE-AC52-07NA27344. LLNL-ABS-491794.

Proceedings of the 11th Annual DARPA/AFGL Seismic Research symposium

NASA Astrophysics Data System (ADS)

Lewkowicz, James F.; McPhetres, Jeanne M.

1990-11-01

The following subjects are covered: near source observations of quarry explosions; small explosion discrimination and yield estimation; Rg as a depth discriminant for earthquakes and explosions: a case study in New England; a comparative study of high frequency seismic noise at selected sites in the USSR and USA; chemical explosions and the discrimination problem; application of simulated annealing to joint hypocenter determination; frequency dependence of Q(sub Lg) and Q in the continental crust; statistical approaches to testing for compliance with a threshold test ban treaty; broad-band studies of seismic sources at regional and teleseismic distances using advanced time series analysis methods; effects of depth of burial and tectonic release on regional and teleseismic explosion waveforms; finite difference simulations of seismic wave excitation at Soviet test sites with deterministic structures; stochastic geologic effects on near-field ground motions; the damage mechanics of porous rock; nonlinear attenuation mechanism in salt at moderate strain; compressional- and shear-wave polarizations at the Anza seismic array; and a generalized beamforming approach to real time network detection and phase association.

Equations of state for detonation products of high energy PBX explosives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, E. L.; Helm, F. H.; Finger, M.

1977-08-01

It has become apparent that the accumulated changes in the analysis of cylinder test data, in the material specifications, and in the hydrodynamic code simulation of the cylinder test necessitated an update of the detonation product EOS description for explosives in common use at LLL. The explosives reviewed are PBX-9404-3, LX-04-1, LX-10-1, LX-14-0 and LX-09-1. In order to maintain the proper relation of predicted performance of these standard explosives, they have been revised as a single set.

High methane natural gas/air explosion characteristics in confined vessel.

PubMed

Tang, Chenglong; Zhang, Shuang; Si, Zhanbo; Huang, Zuohua; Zhang, Kongming; Jin, Zebing

2014-08-15

The explosion characteristics of high methane fraction natural gas were investigated in a constant volume combustion vessel at different initial conditions. Results show that with the increase of initial pressure, the peak explosion pressure, the maximum rate of pressure rise increase due to a higher amount (mass) of flammable mixture, which delivers an increased amount of heat. The increased total flame duration and flame development time result as a consequence of the higher amount of flammable mixture. With the increase of the initial temperature, the peak explosion pressures decrease, but the pressure increase during combustion is accelerated, which indicates a faster flame speed and heat release rate. The maximum value of the explosion pressure, the maximum rate of pressure rise, the minimum total combustion duration and the minimum flame development time is observed when the equivalence ratio of the mixture is 1.1. Additionally, for higher methane fraction natural gas, the explosion pressure and the maximum rate of pressure rise are slightly decreased, while the combustion duration is postponed. The combustion phasing is empirically correlated with the experimental parameters with good fitting performance. Furthermore, the addition of dilute gas significantly reduces the explosion pressure, the maximum rate of pressure rise and postpones the flame development and this flame retarding effect of carbon dioxide is stronger than that of nitrogen. Copyright © 2014 Elsevier B.V. All rights reserved.

Tephra architecture, pyroclast texture and magma rheology of mafic, ash-dominated eruptions: the Violent Strombolian phase of the Pleistocene Croscat (NE Spain) eruption.

NASA Astrophysics Data System (ADS)

Cimarelli, C.; Di Traglia, F.; Vona, A.,; Taddeucci, J.

2012-04-01

A broad range of low- to mid-intensity explosive activity is dominated by the emission of ash-sized pyroclasts. Among this activity, Violent Strombolian phases characterize the climax of many mafic explosive eruptions. Such phases last months to years, and produce ash-charged plumes several kilometers in height, posing severe threats to inhabited areas. To tackle the dominant processes leading to ash formation during Violent Strombolian eruptions, we investigated the magma rheology and the field and textural features of products from the 11 ka Croscat basaltic complex scoria cone in the Quaternary Garrotxa Volcanic Field (GVF). Field, grain-size, chemical (XRF, FE-SEM and electron microprobe) and textural analyses of the Croscat pyroclastic succession outlined the following eruption evolution: activity at Croscat began with fissural, Hawaiian-type fountaining that rapidly shifted towards Strombolian style from a central vent. Later, a Violent Strombolian explosion included several stages, with different emitted volumes and deposit features indicative of differences within the same eruptive style: at first, quasi-sustained fire-fountaining with ash jet and plume produced a massive, reverse to normal graded, scoria deposit; later, a long lasting series of ash-explosions produced a laminated scoria deposit. The eruption ended with a lava flow breaching the western-side of the volcano. Scoria clasts from the Croscat succession ubiquitously show micrometer- to centimeter-sized, microlite-rich domains (MRD) intermingled with volumetrically dominant, microlite-poor domains (MPD). MRD magmas resided longer in a relatively cooler, degassed zone lining the conduit walls, while MPD ones travelled faster along the central, hotter streamline, the two interminging along the interface between the two velocity zones. The preservation of two distinct domains in the short time-scale of the eruption was favoured by their rheological contrast related to the different microlite abundances. The proportion of MPD and MRD, in agreement with bubble-number density (BND), in different tephra layers reflects the extent of the fast- and slow-flowing zones, thus reflecting the ascent velocity profile of magma during the different phases. Recent works (Kueppers et al. 2006, "Explosive energy" during volcanic eruptions from fractal analysis of pyroclasts) indicate that fractal fragmentation theory may allow for quantifying fragmentation processes during explosive volcanic eruptions by calculating the fractal dimension (D) of the size distribution of pyroclasts. At Croscat, BND and MPD/MRD volume ratio decreased during the violent Strombolian activity while D increased, suggesting that the decrease in the magma flow rate was accompanied by the increase in fragmentation efficiency, i.e. by the increase in the ash production capability. This trend may be tentatively attributed to an increased rheological stiffness of the magma progressively enhancing its brittle, more efficient fragmentation.

Effects of Ramadan on physical capacities of North African boys fasting for the first time

PubMed Central

Fenneni, Mohamed A.; Latiri, Imed; Aloui, Asma; Rouatbi, Sonia; Saafi, Mohamed A.; Bougmiza, Iheb; Chamari, Karim; Saad, Helmi Ben

2014-01-01

Introduction Most of the literature related to the effects of Ramadan fasting on physical performance has focused on adults, and only three studies have examined its impact on children’s physical performance. Aims To examine the effects of Ramadan fasting on first-time fasting boys’ performance in short-term explosive exercises [vertical and horizontal jump tests (VJT and HJT), 20-m and 30-m sprints and medicine-ball throw (MBT)], as well as in sub-maximal endurance [6-min walking distance (6MWD) measured during the 6-min walk test (6MWT)]. Methods Eighteen Tunisian boys [mean±standard deviation (SD) of age and body mass (BM): 11.9±0.8 y and 55.4±18.2 kg, respectively] were included. The experimental design comprised four testing phases: 2-weeks before Ramadan (BR), the end of the second week (R2) and the fourth week (R4) of Ramadan, and 10–12 days after the end of Ramadan (AR). At each phase, boys performed two test sessions in the afternoon (15:00–17:00 h) interrupted by 48 h of recovery (first test session: BM, VJT, HJT, and 20-m and 30-m sprint tests; second session: MBT and 6MWT). The study was conducted during the summer of 2012 from July 5 to August 29. Results 6MWDs (m) were significantly shorter during R2 (652±101) and R4 (595±123) compared to BR (697±86) and came back to baseline values AR. BM (kg) mean±SD did not significantly change during R2 (52±15) and during R4 (53±15) compared to BR (55±17), and short-term explosive performances were unchanged throughout the study. Conclusion In non-athletic children, first-ever Ramadan fasting impairs sub-maximal aerobic capacity but has no effect on BM or short-term explosive performance. PMID:25261691

Effects of Ramadan on physical capacities of North African boys fasting for the first time.

PubMed

Fenneni, Mohamed A; Latiri, Imed; Aloui, Asma; Rouatbi, Sonia; Saafi, Mohamed A; Bougmiza, Iheb; Chamari, Karim; Ben Saad, Helmi

2014-01-01

Most of the literature related to the effects of Ramadan fasting on physical performance has focused on adults, and only three studies have examined its impact on children's physical performance. To examine the effects of Ramadan fasting on first-time fasting boys' performance in short-term explosive exercises [vertical and horizontal jump tests (VJT and HJT), 20-m and 30-m sprints and medicine-ball throw (MBT)], as well as in sub-maximal endurance [6-min walking distance (6MWD) measured during the 6-min walk test (6MWT)]. Eighteen Tunisian boys [mean±standard deviation (SD) of age and body mass (BM): 11.9±0.8 y and 55.4±18.2 kg, respectively] were included. The experimental design comprised four testing phases: 2-weeks before Ramadan (BR), the end of the second week (R2) and the fourth week (R4) of Ramadan, and 10-12 days after the end of Ramadan (AR). At each phase, boys performed two test sessions in the afternoon (15:00-17:00 h) interrupted by 48 h of recovery (first test session: BM, VJT, HJT, and 20-m and 30-m sprint tests; second session: MBT and 6MWT). The study was conducted during the summer of 2012 from July 5 to August 29. 6MWDs (m) were significantly shorter during R2 (652±101) and R4 (595±123) compared to BR (697±86) and came back to baseline values AR. BM (kg) mean±SD did not significantly change during R2 (52±15) and during R4 (53±15) compared to BR (55±17), and short-term explosive performances were unchanged throughout the study. In non-athletic children, first-ever Ramadan fasting impairs sub-maximal aerobic capacity but has no effect on BM or short-term explosive performance.

Luminescent detection of hydrazine and hydrazine derivatives

DOEpatents

Swager, Timothy M [Newton, MA; Thomas, III, Samuel W.

2012-04-17

The present invention generally relates to methods for modulating the optical properties of a luminescent polymer via interaction with a species (e.g., an analyte). In some cases, the present invention provides methods for determination of an analyte by monitoring a change in an optical signal of a luminescent polymer upon exposure to an analyte. Methods of the present invention may be useful for the vapor phase detection of analytes such as explosives and toxins. The present invention also provides methods for increasing the luminescence intensity of a polymer, such as a polymer that has been photobleached, by exposing the luminescent polymer to a species such as a reducing agent.

Source Region Modeling of Explosions 2 and 3 from the Source Physics Experiment Using the Rayleigh Integral Method

NASA Astrophysics Data System (ADS)

Jones, K. R.; Arrowsmith, S.; Whitaker, R. W.

2012-12-01

The overall mission of the National Center for Nuclear Security (NCNS) Source Physics Experiment at the National Nuclear Security Site (SPE-N) near Las Vegas, Nevada is to improve upon and develop new physics based models for underground nuclear explosions using scaled, underground chemical explosions as proxies. To this end, we use the Rayleigh integral as an approximation to the Helmholz-Kirchoff integral, [Whitaker, 2007 and Arrowsmith et al., 2011], to model infrasound generation in the far-field. Infrasound generated by single-point explosive sources above ground can typically be treated as monopole point-sources. While the source is relatively simple, the research needed to model above ground point-sources is complicated by path effects related to the propagation of the acoustic signal and out of the scope of this study. In contrast, for explosions that occur below ground, including the SPE explosions, the source region is more complicated but the observation distances are much closer (< 5 km), thus greatly reducing the complication of path effects. In this case, elastic energy from the explosions radiates upward and spreads out, depending on depth, to a more distributed region at the surface. Due to this broad surface perturbation of the atmosphere we cannot model the source as a simple monopole point-source. Instead, we use the analogy of a piston mounted in a rigid, infinite baffle, where the surface area that moves as a result of the explosion is the piston and the surrounding region is the baffle. The area of the "piston" is determined by the depth and explosive yield of the event. In this study we look at data from SPE-N-2 and SPE-N-3. Both shots had an explosive yield of 1 ton at a depth of 45 m. We collected infrasound data with up to eight stations and 32 sensors within a 5 km radius of ground zero. To determine the area of the surface acceleration, we used data from twelve surface accelerometers installed within 100 m radially about ground zero. With the accelerometer data defining the vertical motion of the surface, we use the Rayleigh Integral Method, [Whitaker, 2007 and Arrowsmith et al., 2011], to generate a synthetic infrasound pulse to compare to the observed data. Because the phase across the "piston" is not necessarily uniform, constructive and destructive interference will change the shape of the acoustic pulse if observed directly above the source (on-axis) or perpendicular to the source (off-axis). Comparing the observed data to the synthetic data we note that the overall structure of the pulse agrees well and that the differences can be attributed to a number of possibilities, including the sensors used, topography, meteorological conditions, etc. One other potential source of error between the observed and calculated data is that we use a flat, symmetric source region for the "piston" where in reality the source region is not flat and not perfectly symmetric. A primary goal of this work is to better understand and model the relationships between surface area, depth, and yield of underground explosions.

SN 2013ej IN M74: A LUMINOUS AND FAST-DECLINING TYPE II-P SUPERNOVA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Fang; Wang, Xiaofeng; Chen, Juncheng

2015-07-01

We present extensive ultraviolet, optical, and near-infrared observations of the Type IIP supernova (SN IIP) 2013ej in the nearby spiral galaxy M74. The multicolor light curves, spanning from ∼8–185 days after explosion, show that it has a higher peak luminosity (i.e., M{sub V} ∼ −17.83 mag at maximum light), a faster post-peak decline, and a shorter plateau phase (i.e., ∼50 days) compared to the normal Type IIP SN 1999em. The mass of {sup 56}Ni is estimated as 0.02 ± 0.01 M{sub ⊙} from the radioactive tail of the bolometric light curve. The spectral evolution of SN 2013ej is similar tomore » that of SN 2004et and SN 2007od, but shows a larger expansion velocity (i.e., v{sub Fe} {sub ii} ∼ 4600 km s{sup −1} at t ∼ 50 days) and broader line profiles. In the nebular phase, the emission of the Hα line displays a double-peak structure, perhaps due to the asymmetric distribution of {sup 56}Ni produced in the explosion. With the constraints from the main observables such as bolometric light curve, expansion velocity, and photospheric temperature of SN 2013ej, we performed hydrodynamical simulations of the explosion parameters, yielding the total explosion energy as ∼0.7× 10{sup 51} erg, the radius of the progenitor as ∼600 R{sub ⊙}, and the ejected mass as ∼10.6 M{sub ⊙}. These results suggest that SN 2013ej likely arose from a red supergiant with a mass of 12–13 M{sub ⊙} immediately before the explosion.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Müller, Bernhard; Janka, Hans-Thomas, E-mail: bernhard.mueller@monash.edu, E-mail: bjmuellr@mpa-garching.mpg.de, E-mail: thj@mpa-garching.mpg.de

Considering six general relativistic, two-dimensional (2D) supernova (SN) explosion models of progenitor stars between 8.1 and 27 M {sub ☉}, we systematically analyze the properties of the neutrino emission from core collapse and bounce to the post-explosion phase. The models were computed with the VERTEX-COCONUT code, using three-flavor, energy-dependent neutrino transport in the ray-by-ray-plus approximation. Our results confirm the close similarity of the mean energies, (E), of ν-bar {sub e} and heavy-lepton neutrinos and even their crossing during the accretion phase for stars with M ≳ 10 M {sub ☉} as observed in previous 1D and 2D simulations with state-of-the-artmore » neutrino transport. We establish a roughly linear scaling of 〈E{sub ν-bar{sub e}}〉 with the proto-neutron star (PNS) mass, which holds in time as well as for different progenitors. Convection inside the PNS affects the neutrino emission on the 10%-20% level, and accretion continuing beyond the onset of the explosion prevents the abrupt drop of the neutrino luminosities seen in artificially exploded 1D models. We demonstrate that a wavelet-based time-frequency analysis of SN neutrino signals in IceCube will offer sensitive diagnostics for the SN core dynamics up to at least ∼10 kpc distance. Strong, narrow-band signal modulations indicate quasi-periodic shock sloshing motions due to the standing accretion shock instability (SASI), and the frequency evolution of such 'SASI neutrino chirps' reveals shock expansion or contraction. The onset of the explosion is accompanied by a shift of the modulation frequency below 40-50 Hz, and post-explosion, episodic accretion downflows will be signaled by activity intervals stretching over an extended frequency range in the wavelet spectrogram.« less

Spike-adding in parabolic bursters: The role of folded-saddle canards

NASA Astrophysics Data System (ADS)

Desroches, Mathieu; Krupa, Martin; Rodrigues, Serafim

2016-09-01

The present work develops a new approach to studying parabolic bursting, and also proposes a novel four-dimensional canonical and polynomial-based parabolic burster. In addition to this new polynomial system, we also consider the conductance-based model of the Aplysia R15 neuron known as the Plant model, and a reduction of this prototypical biophysical parabolic burster to three variables, including one phase variable, namely the Baer-Rinzel-Carillo (BRC) phase model. Revisiting these models from the perspective of slow-fast dynamics reveals that the number of spikes per burst may vary upon parameter changes, however the spike-adding process occurs in an explosive fashion that involves special solutions called canards. This spike-adding canard explosion phenomenon is analysed by using tools from geometric singular perturbation theory in tandem with numerical bifurcation techniques. We find that the bifurcation structure persists across all considered systems, that is, spikes within the burst are incremented via the crossing of an excitability threshold given by a particular type of canard orbit, namely the true canard of a folded-saddle singularity. However there can be a difference in the spike-adding transitions in parameter space from one case to another, according to whether the process is continuous or discontinuous, which depends upon the geometry of the folded-saddle canard. Using these findings, we construct a new polynomial approximation of the Plant model, which retains all the key elements for parabolic bursting, including the spike-adding transitions mediated by folded-saddle canards. Finally, we briefly investigate the presence of spike-adding via canards in planar phase models of parabolic bursting, namely the theta model by Ermentrout and Kopell.

Looking for a correlation between infrasound and volcanic gas in strombolian explosions by using high resolution UV spectroscopy and thermal imagery

NASA Astrophysics Data System (ADS)

Delle Donne, Dario; Tamburello, Giancarlo; Ripepe, Maurizio; Aiuppa, Alessandro

2014-05-01

According to the linear theory of sound, acoustic pressure propagating in a homogeneous atmosphere can be modelled in terms of the rate of change of a volumetric source. At open-vent volcanoes, this acoustic source process is commonly related to the explosive dynamics triggered by the rise, expansion and bursting of a gas slug at the magma free surface with the conduit. Just before an explosion, the magma surface will undergo deformation by the expanding gas slug. The deformation of the magma surface will then produce an equivalent displacement of the atmosphere, inducing a volumetric compression and generating an excess pressure that scales to the rate of volumetric change of the atmosphere displaced. Linear theory of sound thus predicts that pressure amplitude of infrasonic waves associated to volcanic explosions should be generated by the first time-derivative of the gas mass flux during the burst. In some cases a correlation between the first time-derivative and the SO2 mass flux has been found. However no clear correlation has yet been established between infrasonic amplitude and total ejected gas mass; therefore, the origin of infrasound in volcanic systems remains matter of debate. In the framework of the FP7-ERC BRIDGE Project, we tested different possible hypotheses on the acoustic source model, by correlating infrasound with the total gas mass retrieved from high-resolution UV spectroscopy techniques (UV camera). Experiments were conducted at Stromboli volcano (Italy), where we also employed a thermal camera to measure the total fragments/gas mass. Both techniques allowed independent estimation of total mass flux of gas and fragments within the volcanic plume. During the experiments, explosions detected by the UV camera emitted between 2 and 55 kg SO2, corresponding to SO2 peak fluxes of 0.1-0.8 kg/s. SO2 mass was converted into a total (maximum) erupted gas of 1310 kg, which is generating a peak pressure of ~8 Pa recorded at ~450 m from the source vent. Mass fluxes derived by infrasound using different methods show weak correlation with the SO2 mass measured by UV camera, and the total volume measured by thermal imagery. This correlation increases when acoustic energy is considered, supporting thus the idea that total mass is not the only parameter controlling infrasound amplitude and waveform. However, more experiments need to be done in order to better understand how infrasound is related to mass of the erupted gas and/or fragments. These include a synchronized acquisition of infrasound and gas flux using high frame rate UV and thermal imaging, allowing us to better investigate the first phase of volcanic explosions.

Compressible Heating in the Condense Phase due to Pore Collapse in HMX

NASA Astrophysics Data System (ADS)

Zhang, Ju; Jackson, Thomas

Axisymmetric pore collapse in HMX is studied numerically by solving multi-phase reactive Euler equations. The generation of hot spots in the condense phase due to compressible heating is examined. The motivation is to improve the understanding of the role of embedded cavities in the initiation of reaction in explosives, and to investigate the effect of hot spots in the condense phase due to compressible heating alone, complementing previous study on hot spots due to the reaction in the gas phase and at the interface. It is found that the shock-cavity interaction results in pressures and thus temperatures that are substantially higher than the post-shock values in the condense phase. However, these hot spots in the condense phase due to compressible heating alone do not seem to be sufficiently hot to lead to ignition at shock pressures of 1-3 GPa. Thus, compressible heating in the condense phase may be excluded as a mechanism for initiation of explosives. It should be pointed out that the ignition threshold for the temperature, the so-called ``switch-on'' temperature, of hot spots depend on chemistry kinetics parameters. Switch-on temperature is lower for faster reaction rate. The current chemistry kinetics parameters are based on previous experimental work. This work was supported in part by the Defense Threat Reduction Agency and by the U.S. Department of Energy.

Innovative Navigation Systems to Support Digital Geophysical Mapping, ESTCP #200129, Phase II Demonstrations

DTIC Science & Technology

2004-09-25

7 Figure 2-3 Blackhawk/ Applanix GPS/INS System...electro-mechanical system ms millisecond NP navigation processor OE ordnance and explosive POSLV Applanix Positioning and Orientation...demonstration GPS/INS positioning system. In Phase II, a man-portable modified version called the POSLV 310 UXO of the Applanix Positioning and

Digitization of Nuclear Explosion Seismograms from the Former Soviet Union

DTIC Science & Technology

2015-03-30

others in terms of frequency-amplitude-phase ( fap ) response files. Approved for public release; distribution is unlimited. T ab le 1 . I ns tr um en...responses are given in terms of poles and zeros, or fap (frequency-amplitude-phase) in CSS 3.0 relational database tables, specifically via .sensor and

Surface modification of Ti alloy by electro-explosive alloying and electron-beam treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gromov, Victor, E-mail: gromov@physics.sibsiu.ru; Kobzareva, Tatiana, E-mail: kobzarevatanya@mail.ru; Budovskikh, Evgeniy, E-mail: budovskih-ea@physics.sibsiu.ru

2016-01-15

By methods of modern physical metallurgy the analysis of structure phase states of titanium alloy VT6 is carried out after electric explosion alloying with boron carbide and subsequent irradiation by pulsed electron beam. The formation of an electro-explosive alloying zone of a thickness up to 50 µm, having a gradient structure, characterized by decrease in the concentration of carbon and boron with increasing distance to the treatable surface has been revealed. Subsequent electron-beam treatment of alloying zone leads to smoothing of the alloying area surface and is accompanied by the multilayer structure formation at the depth of 30 µm withmore » alternating layers with different alloying degrees having the structure of submicro - and nanoscale level.« less

Power and energy of exploding wires

DOE PAGES

Valancius, Cole J.; Garasi, Christopher J.; O?Malley, Patrick D.

2017-01-01

Exploding wires are used in many high-energy applications, such as initiating explosives. Previous work analyzing gold wire burst in detonator applications has shown burst current and action metrics to be inconsistent with burst phenomenon across multiple firing-sets. Energy density better captures the correlation between different wire geometries, different electrical inputs, and explosive initiation. This idea has been expanded upon, to analyze the burst properties in power-energy space. Further inconsistencies in the understanding of wire burst and its relation to peak voltage have been found. An argument will be made for redefining the definition of burst. The result is a moremore » broad understanding of rapid metal phase transition and the initiation of explosives in EBW applications.« less

Ultrasensitive detection of explosives and chemical warfare agents by low-pressure photoionization mass spectrometry.

PubMed

Sun, Wanqi; Liang, Miao; Li, Zhen; Shu, Jinian; Yang, Bo; Xu, Ce; Zou, Yao

2016-08-15

On-spot monitoring of threat agents needs high sensitive instrument. In this study, a low-pressure photoionization mass spectrometer (LPPI-MS) was employed to detect trace amounts of vapor-phase explosives and chemical warfare agent mimetics under ambient conditions. Under 10-s detection time, the limits of detection of 2,4-dinitrotoluene, nitrotoluene, nitrobenzene, and dimethyl methyl phosphonate were 30, 0.5, 4, and 1 parts per trillion by volume, respectively. As compared to those obtained previously with PI mass spectrometric techniques, an improvement of 3-4 orders of magnitude was achieved. This study indicates that LPPI-MS will open new opportunities for the sensitive detection of explosives and chemical warfare agents. Copyright © 2016 Elsevier B.V. All rights reserved.

Power and energy of exploding wires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valancius, Cole J.; Garasi, Christopher J.; O?Malley, Patrick D.

Exploding wires are used in many high-energy applications, such as initiating explosives. Previous work analyzing gold wire burst in detonator applications has shown burst current and action metrics to be inconsistent with burst phenomenon across multiple firing-sets. Energy density better captures the correlation between different wire geometries, different electrical inputs, and explosive initiation. This idea has been expanded upon, to analyze the burst properties in power-energy space. Further inconsistencies in the understanding of wire burst and its relation to peak voltage have been found. An argument will be made for redefining the definition of burst. The result is a moremore » broad understanding of rapid metal phase transition and the initiation of explosives in EBW applications.« less

Microstructure and Properties of 5083 Al/1060 Al/AZ31 Composite Plate Fabricated by Explosive Welding

NASA Astrophysics Data System (ADS)

Yang, Suyuan; Bao, Jiawei

2018-03-01

A 5083 Al/1060 Al/AZ31 composite plate was fabricated by explosive welding. The microstructure and properties of the composite plate were investigated after explosive welding. The results showed that all bonding interfaces were wavy interfaces. With an increasing distance from the detonation point, the wavelength and the amplitude also increased. The EDS results indicated that a 5-μm diffusion layer was observed at the 1060 Al/AZ31 layer, including the Mg2Al3 phase. Adiabatic shear bands and twin structures were observed in AZ31. The shear bond strength of the 5083 Al/1060 Al interface was 60 MPa, and the shear bond strength of the 1060 Al/AZ31 interface was 84 MPa.

DOE Office of Scientific and Technical Information (OSTI.GOV)

K., S C; M., T C

Plastic bonded explosives (PBX) generally consist of 85 - 95 % by weight energetic material, such as HMX, and 5 - 15 % polymeric binder. Understanding of the structure and morphology at elevated temperatures and pressures is important for predicting of PBX behavior in accident scenarios. The crystallographic behavior of pure HMX has been measured as functions of temperature and grain size. The investigation is extended to the high temperature behavior of PBX 9501 (95% HMX, 2.5 % Estane, 2.5 % BDNPA/F). The results show that the HMX {beta}-phase to {delta}-phase transition in PBX 9501 is similar to that inmore » neat HMX. However, in the presence of the PBX 9501 binder, {delta}-phase HMX readily converts back to {beta}-phase during cooling. Using the same temperature profile, the conversion rate decreases for each subsequent heating and cooling cycle. As observed in earlier experiments, no reverse conversion is observed without the polymer binder. It is proposed that the reversion of {delta}-phase to {beta}-phase is due to changes in the surface molecular potential caused by the influence of the polymer binder on the surface molecules of the {delta}-phase. Upon thermal cycling, the polymer binder segregates from the HMX particles and thus reduces the influence of the binder on the surface molecules. This segregation increases the resistance for the {delta}-phase to {beta}-phase transition, as demonstrated in an aged PBX 9501 material for which the reversion is not observed.« less

Remedial Design/Remedial Action Work Plan for Operable Units 6-05 and 10-04, Phase IV

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. P. Wells

2006-11-14

This Phase IV Remedial Design/Remedial Action Work Plan addresses the remediation of areas with the potential for UXO at the Idaho National Laboratory. These areas include portions of the Naval Proving Ground, the Arco High-Altitude Bombing Range, and the Twin Buttes Bombing Range. Five areas within the Naval Proving Ground that are known to contain UXO include the Naval Ordnance Disposal Area, the Mass Detonation Area, the Experimental Field Station, The Rail Car Explosion Area, and the Land Mine Fuze Burn Area. The Phase IV remedial action will be concentrated in these five areas. For other areas, such as themore » Arco High-Altitude Bombing Range and the Twin Buttes Bombing Range, ordnance has largely consisted of sand-filled practice bombs that do not pose an explosion risk. Ordnance encountered in these areas will be addressed under the Phase I Operations and Maintenance Plan that allows for the recovery and disposal of ordnance that poses an imminent risk to human health or the environment.« less

Dynamic polarizability of tungsten atoms reconstructed from fast electrical explosion of fine wires in vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarkisov, G. S.; Rosenthal, S. E.; Struve, K. W.

For nanosecond electrical explosion of fine metal wires in vacuum generates calibrated, radially expanded gas cylinders of metal atoms are surrounded by low-density fast expanding plasma corona. Here, a novel integrated-phase technique, based on laser interferometry, provides the dynamic dipole polarizability of metal atoms. This data was previously unavailable for tungsten atoms. Furthermore, an extremely high melting temperature and significant pre-melt electronic emission make these measurements particularly complicated for this refractory metal.

Structure of bicomponent particles synthesized from colliding metal clusters

NASA Astrophysics Data System (ADS)

Kryzhevich, D. S.; Zolnikov, K. P.; Korchuganov, A. V.; Psakhie, S. G.

2017-12-01

Here, based on a molecular dynamics simulation with many-body interaction potentials, we consider several scenarios of the formation of bicomponent particles from colliding clusters in an electrical explosion of Cu and Ni wires. The data suggest that the structure of bicomponent particles depends largely on the explosion time of one wire with respect to the other and on the phase state of colliding clusters. Diagrams are presented demonstrating the dynamics of bicomponent particles with block structure synthesized from crystalline Ni and molten Cu clusters.

Dynamic polarizability of tungsten atoms reconstructed from fast electrical explosion of fine wires in vacuum

DOE PAGES

Sarkisov, G. S.; Rosenthal, S. E.; Struve, K. W.

2016-10-12

For nanosecond electrical explosion of fine metal wires in vacuum generates calibrated, radially expanded gas cylinders of metal atoms are surrounded by low-density fast expanding plasma corona. Here, a novel integrated-phase technique, based on laser interferometry, provides the dynamic dipole polarizability of metal atoms. This data was previously unavailable for tungsten atoms. Furthermore, an extremely high melting temperature and significant pre-melt electronic emission make these measurements particularly complicated for this refractory metal.

The Effect of Acid Neutralization on Analytical Results Produced from SW846 Method 8330 after the Alkaline Hydrolysis of Explosives in Soil

DTIC Science & Technology

2012-09-01

basic form of phosphoric acid or sodium phosphate NO2- Nitrite OH- Hydroxide ion ERDC/EL TR-12-14 1 1 Introduction Alkaline hydrolysis has...into amber sample vials and refrigerated until analyzed. TNT analyses were conducted by high performance liquid chromatography (HPLC) with a C-18...The explosives concentrations of the different soils were quantified using a DIONEX HPLC system equipped with a C-18 reverse phase column and a

Evaluation of the Use of Supercritical Fluids for the Extraction of Explosives and Their Degradation Products from Soil

DTIC Science & Technology

1994-04-01

and nontoxic is a major pounds. advantage . The accepted analytical method for explosives, The basic equipment required to conduct SFE is SW846 Method...theoretical advantage of SFE tion (SlE) with 18-hour sonic extraction with ACN. compared to conventional solvent extraction. II T r Figure 1. Phase...diagram of C0 2.Temperature 31"C Shut-off Hewler Figure 2. Design for a basic SFE apparaztus. (After Hawthorne 1993.) The advantages of extraction

The Synthesis of 44Ti and 56Ni in Massive Stars

NASA Astrophysics Data System (ADS)

Chieffi, Alessandro; Limongi, Marco

2017-02-01

We discuss the influence of rotation on the combined synthesis of {}44{Ti} and {}56{Ni} in massive stars. While {}56{Ni} is significantly produced by both complete and incomplete explosive Si burning, {}44{Ti} is mainly produced by complete explosive Si burning, with a minor contribution (in standard non-rotating models) from incomplete explosive Si burning and O burning (both explosive and hydrostatic). We find that, in most cases, the thickness of the region exposed to incomplete explosive Si burning increases in rotating models (initial velocity, v ini = 300 km s-1) and since {}56{Ni} is significantly produced in this zone, the fraction of mass coming from the complete explosive Si burning zone necessary to get the required amount of {}56{Ni} reduces. Therefore the amount of {}44{Ti} ejected for a given fixed amount of {}56{Ni} decreases in rotating models. However, some rotating models at [Fe/H] = -1 develop a very extended O convective shell in which a consistent amount of {}44{Ti} is formed, preserved, and ejected in the interstellar medium. Hence a better modeling of the thermal instabilities (convection) in the advanced burning phases together with a critical analysis of the cross sections of the nuclear reactions operating in O burning are relevant for the understanding of the synthesis of {}44{Ti}.

A Fracture Decoupling Experiment

NASA Astrophysics Data System (ADS)

Stroujkova, A. F.; Bonner, J. L.; Leidig, M.; Ferris, A. N.; Kim, W.; Carnevale, M.; Rath, T.; Lewkowicz, J.

2012-12-01

Multiple observations made at the Semipalatinsk Test Site suggest that conducting nuclear tests in the fracture zones left by previous explosions results in decreased seismic amplitudes for the second nuclear tests (or "repeat shots"). Decreased seismic amplitudes reduce both the probability of detection and the seismically estimated yield of a "repeat shot". In order to define the physical mechanism responsible for the amplitude reduction and to quantify the degree of the amplitude reduction in fractured rocks, Weston Geophysical Corp., in collaboration with Columbia University's Lamont Doherty Earth Observatory, conducted a multi-phase Fracture Decoupling Experiment (FDE) in central New Hampshire. The FDE involved conducting explosions of various yields in the damage/fracture zones of previously detonated explosions. In order to quantify rock damage after the blasts we performed well logging and seismic cross-hole tomography studies of the source region. Significant seismic velocity reduction was observed around the source regions after the initial explosions. Seismic waves produced by the explosions were recorded at near-source and local seismic networks, as well as several regional stations throughout northern New England. Our analysis confirms frequency dependent seismic amplitude reduction for the repeat shots compared to the explosions in un-fractured rocks. The amplitude reduction is caused by pore closing and/or by frictional losses within the fractured media.

Plastic deformation and wave formation on the interface of metals welded by ultrasound-assisted explosive welding

NASA Astrophysics Data System (ADS)

Kuz'min, E. V.; Kuz'min, S. V.; Lysak, V. I.; Lata, A. N.

2017-10-01

This paper presents the influence of the effect of ultrasound on the wave formation and plastic deformation in the metals welded by ultrasound-assisted explosive welding. It has been established that the influence of high-frequency acoustic waves on the metal leads to a reduction of the dynamic yield stress, which in turn leads to changes in the properties of the surface layers of metal and in the conditions of bonding between the collided plates upon explosive welding. It has been shown that the changes in the length and amplitude of waves that arise in the weld joint upon the explosive welding with the simultaneous action of ultrasonic vibrations is connected with a decrease in the magnitude of the deforming pulse and time of action of the compressive stresses that exceed the dynamic yield stress behind the point of contact.

Thin film sensor materials for detection of Nitro-Aromatic explosives

NASA Astrophysics Data System (ADS)

Ramdasi, Dipali; Mudhalwadkar, Rohini

2018-03-01

Many countries have experienced terrorist activities and innocent people have suffered. Timely detection of explosives can avoid this situation. This paper targets the detection of Nitrobenzene and Nitrotoluene, which are nitroaromatic compounds possessing explosive properties. As direct sensors for detecting these compounds are not available, Polyaniline based thin film sensors doped with palladium are developed using the spin coating technique. The response of the developed sensors is observed for varying concentrations of explosives. It is observed that zinc oxide based sensor is more sensitive to Nitrotoluene exhibiting a relative change in resistance of 0.78. The tungsten oxide sensor is more sensitive to Nitrobenzene with a relative change in resistance of 0.48. The sensor performance is assessed by measuring the response and recovery time. The cross sensitivity of the sensors is evaluated for ethanol, acetone and methanol which was observed as very low.

A study comparing centralized CD-ROM and decentralized intranet access to MEDLINE

PubMed Central

Darmoni, Stefan J.; Benichou, Jacques; Thirion, Benoit; Hellot, Marie France; Fuss, Jacques

2000-01-01

Objective: The purpose of this study was to evaluate the efficacy of a decentralized intranet access in each medical department as opposed to centralized unique MEDLINE access in the medical library. Design: A two-phase questionnaire to evaluate MEDLINE use was given to junior and senior physicians at Rouen University Hospital (RUH). Phase I (August–October 1996) corresponded to a time period when centralized access was the only means of access available and phase II (August–October 1997) to a time period following the introduction of decentralized intranet access. Results: A total of 168 physicians filled out at least one phase of the questionnaire, among whom 123 (73%) filled out both phases. Use of MEDLINE significantly increased in 1997 (average of 10.2 ± 1.1 searches in three months) versus 1996 (average of 4.9 ± 0.7 searches in three months, P < 0.0001). The aim of searches changed, becoming significantly more care oriented in phase II (P < 0.0001). The number of searches performed by the physicians alone increased (P < 0.0001) and searches performed by the librarian decreased (P < 0.0001) in phase II. The method of searches also changed, as searches by author (P < 0.0001), by journal (P = 0.0042), and by free word (P = 0.0027) increased in phase II. Knowledge of the following concepts of MEDLINE significantly increased: explosion (P < 0.0001), scope note (P < 0.0001), Abridged Index Medicus (AIM) journals (P < 0.0001), Medical Subject Headings (MeSH) qualifier (P < 0.0001), and focus (P < 0.0001). Conclusion: A decentralized intranet access to MEDLINE increased the number of searches and knowledge of this bibliographic database. MEDLINE intranet access modified the purpose and the methods of searching. PMID:10783970

Influence of stochastic perturbations on the cluster explosive synchronization of second-order Kuramoto oscillators on networks.

PubMed

Cao, Liang; Tian, Changhai; Wang, Zhenhua; Zhang, Xiyun; Liu, Zonghua

2018-02-01

Explosive synchronization in networked second-order Kuramoto oscillators has been well studied recently and it is revealed that the synchronization process is featured by cluster explosive synchronization. However, little attention has been paid to the influence of noise or perturbation. We here study this problem and discuss the influences of noise and perturbation. For the former, we interestingly find that noise has significant influence on the cluster explosive synchronization of those nodes with smaller degrees, i.e., their synchronization will change from the first-order to second-order transition and the critical points for both the forward and backward synchronization depend on the strength of noise. Especially, when the strength of noise is in an optimal range, a synchronization of the nodes with smaller degrees will be induced in the region of coupling strength where they do not display synchronization in the absence of noise. For the latter, we find that the effect of perturbation is similar to that of noise when its duration W is small. However, the perturbation will induce a change from cluster explosive synchronization to explosive synchronization when W is large. Furthermore, a brief theory is provided to explain the influence of perturbations on the critical points.

A critical review of ion mobility spectrometry for the detection of explosives and explosive related compounds.

PubMed

Ewing, R G; Atkinson, D A; Eiceman, G A; Ewing, G J

2001-05-10

Ion mobility spectrometry has become the most successful and widely used technology for the detection of trace levels of nitro-organic explosives on handbags and carry on-luggage in airports throughout the US. The low detection limits are provided by the efficient ionization process, namely, atmospheric pressure chemical ionization (APCI) reactions in negative polarity. An additional level of confidence in a measurement is imparted by characterization of ions for mobilities in weak electric fields of a drift tube at ambient pressure. Findings from over 30 years of investigations into IMS response to these explosives have been collected and assessed to allow a comprehensive view of the APCI reactions characteristic of nitro-organic explosives. Also, the drift tube conditions needed to obtain particular mobility spectra have been summarized. During the past decade, improvements have occurred in IMS on the understanding of reagent gas chemistries, the influence of temperature on ion stability, and sampling methods. In addition, commercial instruments have been refined to provide fast and reliable measurements for on-site detection of explosives. The gas phase ion chemistry of most explosives is mediated by the fragile CONO(2) bonds or the acidity of protons. Thus, M(-) or M.Cl(-) species are found with only a few explosives and loss of NO(2), NO(3) and proton abstraction reactions are common and complicating pathways. However, once ions are formed, they appear to have stabilities on time scales equal to or longer than ion drift times from 5-20 ms. As such, peak shapes in IMS are suitable for high selectivity and sensitivity.

On-line image analysis of the stromboli volcanic activity recorded by the surveillance camera helps the forecasting of the major eruptive events.

NASA Astrophysics Data System (ADS)

Cristaldi, A.; Coltelli, M.; Mangiagli, S.; Pecora, E.

2003-04-01

The typical activity of Stromboli consists of intermittent mild explosions lasting a few seconds, which take place at different vents and at variable intervals, the most common time interval being 10-20 minutes. However, the routine activity can be interrupted by more violent, paroxysmal explosions, that eject m-sized scoriaceous bombs and lava blocks to a distance of several hundreds of meters from the craters, endangering the numerous tourists that watch the spectacular activity from the volcano's summit located about two hundreds meters from the active vents. On average, 1-2 paroxysmal explosions occurred per year over the past century, but this statistic may be underestimated in absence of continuous monitoring. For this reason from summer 1996 a remote surveillance camera works on Stromboli recording continuously the volcanic activity. It is located on Pizzo Sopra la Fossa, 100 metres above the crater terrace where are the active vents. Using image analysis we seeks to identify any change of the explosive activity trend that could precede a particular eruptive event, like paroxysmal explosions, fire fountains, lava flows. From the day of the camera installation up to present 12 paroxysmal events and lava flows occurred. The analysis include the counting of the explosions occurred at the different craters and the parameterization in classes of intensity for each explosion on the base of tephra dispersion and kinetics energy. The plot of dissipated energy by each crater versus time shows a cyclic behavior with max and min of explosive activity ranging from a few days to a month. Often the craters show opposite trends so when the activity decreases in a crater, increases in the other. Before every paroxysmal explosions recorded, the crater that produced the event decreased and then stopped its activity from a few days to weeks before. The other crater tried to compensate increasing its activity and when it declined the paroxysmal explosion occurred suddenly at the former site. From September 2001 an on-line image analyzer called VAMOS (Volcanic Activity MOnitoring System) operates detection and classification of explosive events in quasi real-time. The system has automatically recorded and analyzed the change in the energetic trend that preceded the 20 October 2001 paroxysmal explosion that killed a woman and the strong explosive activity that preceded the onset of 28 December 2002 lava flow eruption.

Photoacoustic spectroscopy for trace vapor detection and standoff detection of explosives

NASA Astrophysics Data System (ADS)

Holthoff, Ellen L.; Marcus, Logan S.; Pellegrino, Paul M.

2016-05-01

The Army is investigating several spectroscopic techniques (e.g., infrared spectroscopy) that could allow for an adaptable sensor platform. Current sensor technologies, although reasonably sized, are geared to more classical chemical threats, and the ability to expand their capabilities to a broader range of emerging threats is uncertain. Recently, photoacoustic spectroscopy (PAS), employed in a sensor format, has shown enormous potential to address these ever-changing threats. PAS is one of the more flexible IR spectroscopy variants, and that flexibility allows for the construction of sensors that are designed for specific tasks. PAS is well suited for trace detection of gaseous and condensed media. Recent research has employed quantum cascade lasers (QCLs) in combination with MEMS-scale photoacoustic cell designs. The continuous tuning capability of QCLs over a broad wavelength range in the mid-infrared spectral region greatly expands the number of compounds that can be identified. We will discuss our continuing evaluation of QCL technology as it matures in relation to our ultimate goal of a universal compact chemical sensor platform. Finally, expanding on our previously reported photoacoustic detection of condensed phase samples, we are investigating standoff photoacoustic chemical detection of these materials. We will discuss the evaluation of a PAS sensor that has been designed around increasing operator safety during detection and identification of explosive materials by performing sensing operations at a standoff distance. We investigate a standoff variant of PAS based upon an interferometric sensor by examining the characteristic absorption spectra of explosive hazards collected at 1 m.

A numerical framework for the direct simulation of dense particulate flow under explosive dispersal

NASA Astrophysics Data System (ADS)

Mo, H.; Lien, F.-S.; Zhang, F.; Cronin, D. S.

2018-05-01

In this paper, we present a Cartesian grid-based numerical framework for the direct simulation of dense particulate flow under explosive dispersal. This numerical framework is established through the integration of the following numerical techniques: (1) operator splitting for partitioned fluid-solid interaction in the time domain, (2) the second-order SSP Runge-Kutta method and third-order WENO scheme for temporal and spatial discretization of governing equations, (3) the front-tracking method for evolving phase interfaces, (4) a field function proposed for low-memory-cost multimaterial mesh generation and fast collision detection, (5) an immersed boundary method developed for treating arbitrarily irregular and changing boundaries, and (6) a deterministic multibody contact and collision model. Employing the developed framework, this paper further studies particle jet formation under explosive dispersal by considering the effects of particle properties, particulate payload morphologies, and burster pressures. By the simulation of the dispersal processes of dense particle systems driven by pressurized gas, in which the driver pressure reaches 1.01325× 10^{10} Pa (10^5 times the ambient pressure) and particles are impulsively accelerated from stationary to a speed that is more than 12000 m/s within 15 μ s, it is demonstrated that the presented framework is able to effectively resolve coupled shock-shock, shock-particle, and particle-particle interactions in complex fluid-solid systems with shocked flow conditions, arbitrarily irregular particle shapes, and realistic multibody collisions.

The numerical methods for the development of the mixture region in the vapor explosion simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Y.; Ohashi, H.; Akiyama, M.

An attempt to numerically simulate the process of the vapor explosion with a general multi-component and multi-dimension code is being challenged. Because of the rapid change of the flow field and extremely nonuniform distribution of the components in the system of the vapor explosion, the numerical divergence and diffusion are subject to occur easily. A dispersed component model and a multiregion scheme, by which these difficulties can be effectively overcome, were proposed. The simulations have been performed for the processes of the premixing and the fragmentation propagation in the vapor explosion.

Testing of Confining Pressure Impacton Explosion Energy of Explosive Materials

NASA Astrophysics Data System (ADS)

Drzewiecki, Jan; Myszkowski, Jacek; Pytlik, Andrzej; Pytlik, Mateusz

2017-06-01

This paper presents the results of testing the explosion effects of two explosive charges placed in an environment with specified values of confining pressure. The aim of this study is to determine the impact of variable environmental conditions on the suitability of particular explosives for their use in the prevention of natural hazards in hard coal mining. The research results will contribute to improving the efficiency of currently adopted technologies of natural hazard prevention and aid in raising the level of occupational safety. To carry out the subject matter measurements, a special test stand was constructed which allows the value of the initial pressure inside the chamber, which constitutes its integral part, to be altered before the detonation of the charge being tested. The obtained characteristics of the pressure changes during the explosion of the analysed charge helped to identify the work (energy) which was produced during the process. The test results are a valuable source of information, opening up new possibilities for the use of explosives, the development of innovative solutions for the construction of explosive charges and their initiation.

Gas and ash emissions associated with the 2010–present activity of Sinabung Volcano, Indonesia

USGS Publications Warehouse

Primulyana, Sofyan; Kern, Christoph; Lerner, Allan; Saing, Ugan; Kunrat, Syegi; Alfianti, Hilma; Marlia, Mitha

2017-01-01

Sinabung Volcano (Sumatra, Indonesia) awoke from over 1200 years of dormancy with multiple phreatic explosions in 2010. After a period of quiescence, Sinabung activity resumed in 2013, producing frequent explosions, lava dome extrusion, and pyroclastic flows from dome collapses, becoming one of the world's most active volcanoes and displacing over 20,000 citizens. This study presents a compilation of the geochemical datasets collected by the Indonesian Center for Volcanology and Geological Hazard Mitigation (CVGHM) from 2010 - current (2016), which provides insights into the evolution of the eruption. Based on observations of SO2 emissions, ash componentry, leachate chemistry, and bulk ash geochemistry, the eruption can be split into five distinct phases. The initial stage of phreatic summit explosions occurred from August - October 2010, during which background SO2 emissions averaged ~550 ± 180 t/d (1 s.d.). An eruptive pause (phase two) starting in October 2010 abruptly ended in September 2013 with a resumption of conduit-clearing eruptions. This third phase had a relatively modest background SO2 emission rate (avg. ~410 ± 275 t/d) and produced ash consisting entirely of accidental ejecta with high S/Cl leachate ratios (up to 30), suggestive of deep-sourced magma and the incorporation of hydrothermal sulfur-bearing phases. The most intense phase of the eruption (phase four) occurred from December 2013 to February 2014, when juvenile magma first reached the surface. This period included dozens of large eruptions per day, high SO2 emission rates (average: 1,120 ± 1,030 t/d, peak: ~3,800 t/d), the onset of lava dome extrusion, and a dramatic drop in S/Cl ash leachates to ratios < 5, all reflecting increased degassing from shallow magma and the clearing out of sulfurous phases from the old hydrothermal system. From late February 2014 through the time of writing (September 2016), Sinabung settled into a relatively steady state of lower activity (phase five). Ash emissions now consist of dominantly juvenile material, and background SO2 emission rates have been progressively decreasing to an average of ~250 - 300 t/d. Starting August 2016, SO2 emissions started being measured in a continuous manner using a network of permanent scanning DOAS instruments. We find that long-term SO2 emission rates have been gradually declining at Sinabung since early 2014, consistent with an apparent decrease in magma supply. Our degassing model suggests that large explosions and pyroclastic flows could continue in the near-term owing to conduit plugging and dome collapses, remaining a major threat until the magma supply rate decreases further and the eruption ends.

Reactive Blast Waves from Composite Charges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhl, A L; Bell, J B; Beckner, V E

2009-10-16

Investigated here is the performance of composite explosives - measured in terms of the blast wave they drive into the surrounding environment. The composite charge configuration studied here was a spherical booster (1/3 charge mass), surrounded by aluminum (Al) powder (2/3 charge mass) at an initial density of {rho}{sub 0} = 0.604 g/cc. The Al powder acts as a fuel but does not detonate - thereby providing an extreme example of a 'non-ideal' explosive (where 2/3 of the charge does not detonate). Detonation of the booster charge creates a blast wave that disperses the Al powder and ignites the ensuingmore » Al-air mixture - thereby forming a two-phase combustion cloud embedded in the explosion. Afterburning of the booster detonation products with air also enhances and promotes the Al-air combustion process. Pressure waves from such reactive blast waves have been measured in bomb calorimeter experiments. Here we describe numerical simulations of those experiments. A Heterogeneous Continuum Model was used to model the dispersion and combustion of the Al particle cloud. It combines the gasdynamic conservation laws for the gas phase with a dilute continuum model for the dispersed phase, as formulated by Nigmatulin. Inter-phase mass, momentum and energy exchange are prescribed by phenomenological models of Khasainov. It incorporates a combustion model based on mass conservation laws for fuel, air and products; source/sink terms are treated in the fast-chemistry limit appropriate for such gasdynamic fields, along with a model for mass transfer from the particle phase to the gas. The model takes into account both the afterburning of the detonation products of the booster with air, and the combustion of the Al particles with air. The model equations were integrated by high-order Godunov schemes for both the gas and particle phases. Adaptive Mesh Refinement (AMR) was used to capture the energy-bearing scales of the turbulent flow on the computational grid, and to track/resolve reaction zones. Numerical simulations of the explosion fields from 1.5-g and 10-kg composite charges were performed. Computed pressure histories (red curve) are compared with measured waveforms (black curves) in Fig. 1. Comparison of these results with a waveform for a non-combustion case in nitrogen (blue curve) demonstrates that a reactive blast wave was formed. Cross-sectional views of the temperature field at various times are presented in Fig. 2, which shows that the flow is turbulent. Initially, combustion occurs at the fuel-air interface, and the energy release rate is controlled by the rate of turbulent mixing. Eventually, oxidizer becomes distributed throughout the cloud via ballistic mixing of the particles with air; energy release then occurs in a distributed combustion mode, and Al particle kinetics controls the energy release rate. Details of the Heterogeneous Continuum Model and results of the numerical simulations of composite charge explosions will be described in the paper.« less

Dynamic reflectance of tin shocked from its beta to BCT phase

NASA Astrophysics Data System (ADS)

Stevens, Gerald; La Lone, Brandon; Veeser, Lynn; Turley, Dale

2015-06-01

Shock-induced phase transitions have historically been inferred by features in loading/unloading velocity wave profiles, which arise due to volume or sound speed differences between phases. In 2010, we used a flash-lamp illuminated multi-band reflectometer to demonstrate that iron, tin, cerium, and gallium have measureable reflectance changes at phase boundaries. We have improved upon our prior technique, utilizing an integrating sphere with an internal xenon flash lamp to illuminate a shocked metal beneath a LiF window. The new reflectance system is insensitive to motion, tilt, or curvature and measures the absolute (not relative) reflectance within five bands centered at 500, 700, 850, 1300, and 1550 nm. We have made dynamic reflectance measurements of tin samples shocked to pressures above and below the beta-bct phase transition using either high explosives or a gas gun. Below the transition, the visible reflectance decreases with pressure. At and above the transition, the visible reflectance increases to values higher than the ambient values. Reflectance can therefore be used to locate the beta-bct phase transition boundary for tin, independent of the velocity wave profile. This work was done by National Security Technologies, LLC, under Contract No. DE-AC52-06NA25946 with the U.S. Department of Energy, and supported by the Site-Directed Research and Development Program.

Phase Structures and Magnetic Properties of Graphite Nanosheets and Ni-Graphite Nanocomposite Synthesized by Electrical Explosion of Wire in Liquid

NASA Astrophysics Data System (ADS)

Nguyen, Minh-Thuyet; Kim, Jin-Hyung; Lee, Jung-Goo; Kim, Jin-Chun

2018-03-01

The present work studied on phases and magnetic properties of graphite nanosheets and Ni-graphite nanocomposite synthesized using the electrical explosion of wire (EEW) in ethanol. X-ray diffraction and field emission scanning electron microscope were used to investigate the phases and the morphology of the nanopowders obtained. It was found that graphite nanosheets were absolutely fabricated by EEW with a thickness of 29 nm and 3 μm diameter. The as-synthesized Ni-graphite composite powders had a Ni-coating on the surfaces of graphite sheets. The hysteresis loop of the as-exploded, the hydrogen-treated composite nanopowders and the sintered samples were examined with a vibrating sample magnetometer at room temperature. The Ni-graphite composite exposed the magnetic behaviors which are attributed to Ni component. The magnetic properties of composite had the improvement from 10.2 emu/g for the as-exploded powders to 15.8 emu/g for heat-treated powders and 49.16 emu/g for sintered samples.

Ground Truth Collections for Explosions in Northern Fennoscandia and Russia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harris, D B; Ringdal, F; Kremenetskaya, E

2003-07-28

This project is providing ground-truth information on explosions conducted at the principal mines within 500 kilometers of the ARCES station, and is assembling a seismic waveform database for these events from local and regional stations. The principal mines of interest are in northwest Russia (Khibiny Massif, Olenogorsk, Zapolyamy, and Kovdor groups) and Sweden (Malmberget, Kiruna). These mines form a natural laboratory for examining the variation of mining explosion observations with source type, since they include colocated surface and underground mines and mines conducting a variety of different shot types. In September 2002 we deployed two lines of temporary stations frommore » the Khibiny Massif through and to the north of the ARCES station. This deployment is producing data that will allow researchers to examine the variation of discriminants caused by varying source-receiver distance and the diversity of explosion types. To date, we have collected ground-truth information on 1,118 explosions in the Kola Peninsula, and have assembled waveform data for approximately 700 of these. The database includes waveforms from instruments temporarily deployed in the Khibiny Massif mines, from the Apatity network just outside of the Massif, from LVZ, KEV and ARCES, and from the stations deployed along the two lines into northern Norway. In this paper we present representative waveforms for several types of shots recorded at various regional distances. We have conducted a preliminary study of the variation of phase ratios as a function of source type. This study shows significant differences in Pd/Sn and Pd/Lg ratios for two types of mining explosions: surface ripple-fired explosions and compact underground explosions. Compact explosions are, typically, underground explosions of a few tons with only one or two short delays, and are the closest approximation to single, well-tamped explosions available in the Khibiny mines. The surface shots typically are much larger (ranging up to hundreds of tons), with many delays. The surface mine that we present results for typically also conducts several distinct shots across the mine nearly simultaneously (with a few seconds or tens of seconds). Measured phase ratios are more consistent for compact underground explosions. This consistency is an expected result given the smaller scope for shot variation in these smaller events. In addition, Pd/Lg ratios appear more stable than Pd/Sn ratios for both types of events. The most interesting result is that the compact underground explosions are richer in shear energy (i.e. having smaller P/S ratios) than their surface ripple-fired counterparts. We continue to work on an approach for identifying the principal mines to be targeted for screening at a particular station. Often, routine industrial blasts constitute a large proportion of events detected by monitoring stations close to major mining districts. Many mines may be present, and it may be a problem to determine which subset of mines is responsible for the majority of the events, and should be prime candidates for the deployment of ground-truth collection resources. Our solution to this problem entails several steps. The first is to find geographic clusters of events that may correspond to major groups of mines. For this step, we use event density maps generated from existing network catalogs. This year we examined some of the tradeoffs in generating event density maps: use of automated bulletins to produce maps vs. analyst-reviewed bulletins, and the amount of time required to produce stables maps which can be used to identify significant mines.« less

Phase shifts, herbivory, and the resilience of coral reefs to climate change.

PubMed

Hughes, Terence P; Rodrigues, Maria J; Bellwood, David R; Ceccarelli, Daniela; Hoegh-Guldberg, Ove; McCook, Laurence; Moltschaniwskyj, Natalie; Pratchett, Morgan S; Steneck, Robert S; Willis, Bette

2007-02-20

Many coral reefs worldwide have undergone phase shifts to alternate, degraded assemblages because of the combined effects of over-fishing, declining water quality, and the direct and indirect impacts of climate change. Here, we experimentally manipulated the density of large herbivorous fishes to test their influence on the resilience of coral assemblages in the aftermath of regional-scale bleaching in 1998, the largest coral mortality event recorded to date. The experiment was undertaken on the Great Barrier Reef, within a no-fishing reserve where coral abundances and diversity had been sharply reduced by bleaching. In control areas, where fishes were abundant, algal abundance remained low, whereas coral cover almost doubled (to 20%) over a 3 year period, primarily because of recruitment of species that had been locally extirpated by bleaching. In contrast, exclusion of large herbivorous fishes caused a dramatic explosion of macroalgae, which suppressed the fecundity, recruitment, and survival of corals. Consequently, management of fish stocks is a key component in preventing phase shifts and managing reef resilience. Importantly, local stewardship of fishing effort is a tractable goal for conservation of reefs, and this local action can also provide some insurance against larger-scale disturbances such as mass bleaching, which are impractical to manage directly.

The role of H2O in controlling the eruptive behavior observed during 2008 Chaitén eruption

NASA Astrophysics Data System (ADS)

Forte, Pablo; Castro, Jonathan

2016-04-01

Although highly explosive and with the capacity of producing impacts in a world-wide scale, the underlying mechanisms driving rhyolitic eruptions are not yet fully understood. The lower frequency of these events in comparison to intermediate composition and mafic magmatic eruptions has hampered observation-based studies of rhyolite activity in last century. But in 2008, the eruption of Chaitén volcano (Southern Chile), gave us the first view of a rhyolitic eruptive cycle, start to finish. After an initial explosive phase that lasted for 10 days, the vigour of the eruption decreased and gave way to an effusive phase that was characterized by the emplacement of a dome complex. Surprisingly, a transitional phase between them was identified, with the simultaneous occurrence of explosive and effusive activity (Pallister et al. 2013). During the eruption, vast amounts of glassy rhyolite bombs with H2O contents ranging from 0.1 to 1.58 wt. % H2O were produced (Castro et al. 2012). It is already well known that H2O is one of the main players involved in the evolution of rhyolitic systems and in the occurrence of explosive volcanic eruptions (eg. Zhang et al. 2007). In this study, we conducted 90 high-temperature, 1 atm experiments in order to constrain degassing systematics and resultant foaming/fragmentation behavior of magma residing in the last hundred meters of Chaitén's volcanic conduit. By using cylindrical cores (4 x 10 mm) drilled from obsidian bombs and lava dome samples, isothermal experiments were performed at temperatures between 740° and 1030°C among the whole range of H2O contents measured in the deposits. Due to the experimental design developed, the complete evolution of the experiments was possible to monitor through a sapphire window with high-speed and conventional video cameras. Post-experiment video analysis has revealed 3 types of behaviors of the samples: a) expansion followed by equilibrium (constant volume), b) expansion followed by shrinking and c) expansion followed by explosive fragmentation. This last behavior was identified exclusively in samples with H2O ≥ 1.2 wt.%, and at temperatures higher than 880°C. For samples with H2O < 1.2 wt.%, no fragmentation was observed, even at higher temperatures (up to 1030°C), well above the estimated pre-eruptive temperature (~825°C) of the 2008 Chaitén rhyolite (see Castro and Dingwell, 2009). In samples that did not experience fragmentation, porosities of up to 85% were measured. Experimental results show that foaming and fragmentation behaviors reflect the efficiency of degassing of the system and this in turn depends on H2O content and temperature. We show that diverse vesiculation and fragmentation behaviors are the result of a complex interplay between H2O exsolution, diffusion rates and consequent changes in viscosity. Ultimately foaming versus fragmentation behavior depends on variations in the Peclet number, which balances viscous and diffusion-controlled bubble-growth regimes.

Remedial Action Report for Operable Units 6-05 and 10-04, Phase III

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. P. Wells

2007-08-15

This Phase III remedial action report addresses the remediation of lead-contaminated soils found at the Security Training Facility STF-02 Gun Range at the Idaho National Laboratory Site. Phase I, consisting of developing and implementing institutional controls at Operble Unit 10-04 sites and developing and implementing Idaho National Laboratory Site-wide plans for both institutional controls and ecological monitoring, was addressed in a previous report. Phase II will remediate sites contaminated with trinitrotoluene and Royal Demolition Explosive. Phase IV will remediate hazards from unexploded ordnance.

Probing royal demolition explosive (1,3,5-trinitro-1,3,5-triazocyclohexane) by low-energy electrons: Strong dissociative electron attachment near 0 eV.

PubMed

Sulzer, P; Mauracher, A; Ferreira da Silva, F; Denifl, S; Märk, T D; Probst, M; Limão-Vieira, P; Scheier, P

2009-10-14

Low energy electron attachment to gas phase royal demolition explosive (RDX) (and RDX-A3) has been performed by means of a crossed electron-molecular beam experiment in an electron energy range from 0 to 14 eV with an energy resolution of approximately 70 meV. The most intense signals are observed at 102 and 46 amu and assigned to C(2)H(4)N(3)O(2) (-) and NO(2) (-), respectively. Anion efficiency curves of 16 anions have been measured. Product ions are observed mainly in the low energy region, near 0 eV arising from surprisingly complex reactions associated with multiple bond cleavages and structural and electronic rearrangement. The remarkable instability of RDX to electron attachment with virtually thermal electrons reflects the highly explosive nature of this compound. The present results are compared to other explosive aromatic nitrocompounds studied in our laboratory recently.

Pair-instability supernovae of fast rotating stars

NASA Astrophysics Data System (ADS)

Chen, Ke-Jung

2015-01-01

We present 2D simulations of pair-instability supernovae considering rapid rotation during their explosion phases. Recent studies of the Population III (Pop III) star formation suggested that these stars could be born with a mass scale about 100 M⊙ and with a strong rotation. Based on stellar evolution models, these massive Pop III stars might have died as highly energetic pair-instability supernovae. We perform 2D calculations to investigate the impact of rotation on pair-instability supernovae. Our results suggest that rotation leads to an aspherical explosion due to an anisotropic collapse. If the first stars have a 50% of keplerian rotational rate of the oxygen core before their pair-instability explosions, the overall 56Ni production can be significantly reduced by about two orders of magnitude. An extreme case of 100% keplerian rotational rate shows an interesting feature of fluid instabilities along the equatorial plane caused by non-synchronized and non-isotropic ignitions of explosions, so that the shocks run into the in-falling gas and generate the Richtmyer-Meshkov instability.

Observation and modeling of deflagration-to-detonation transition (DDT) in low-density HMX

NASA Astrophysics Data System (ADS)

Tringe, Joseph W.; Vandersall, Kevin S.; Reaugh, John E.; Levie, Harold W.; Henson, Bryan F.; Smilowitz, Laura B.; Parker, Gary R.

2017-01-01

We employ simultaneous flash x-ray radiography and streak imaging, together with a multi-phase finite element model, to understand deflagration-to-detonation transition (DDT) phenomena in low-density (˜1.2 gm/cm3) powder of the explosive cyclotetramethylene-tetranitramine (HMX). HMX powder was lightly hand-tamped in a 12.7 mm diameter column, relatively lightly-confined in an optically-transparent polycarbonate cylinder with wall thickness 25.4 mm. We observe apparent compaction of the powder in advance of the detonation transition by the motion of small steel spheres pre-emplaced throughout the length of explosive. High-speed imaging along the explosive cylinder length provides a more temporally continuous record of the transition that is correlated with the high-resolution x-ray image record. Preliminary simulation of these experiments with the HERMES model implemented in the ALE3D code enables improved understanding of the explosive particle burning, compaction and detonation phenomena which are implied by the observed reaction rate and transition location within the cylinder.

Effects of hydrogen bond on the melting point of azole explosives

NASA Astrophysics Data System (ADS)

Wang, Jian-Hua; Shen, Chen; Liu, Yu-Cun; Luo, Jin; Duan, Yingjie

2018-07-01

Melting point is an important index to determine whether an explosive can be a melt cast carrier. In this study, the relationship among the molecular structure, crystal structure, and melting point of explosives was investigated by using nitroazole compounds. Hydrogen bonds influence crystal packing modes in chemically understandable ways. Hydrogen bonds also affect the changes in entropy and enthalpy in balancing melting process. Hence, different types of hydrogen bonds in explosive crystal structures were compared when the relationship between the molecular structure and the melting point of nitroazole explosives were analyzed. The effects of methyl and amino groups on intermolecular hydrogen bonds were also compared. Results revealed that the methyl and amino groups connected on the N(1) of the heterocyclic compound can reduce the melting point of azole explosive. This finding is possible because methyl and amino groups destroy the intermolecular hydrogen bond of the heterocyclic compound.

An overview of the 2009 eruption of Redoubt Volcano, Alaska

NASA Astrophysics Data System (ADS)

Bull, Katharine F.; Buurman, Helena

2013-06-01

In March 2009, Redoubt Volcano, Alaska erupted for the first time since 1990. Explosions ejected plumes that disrupted international and domestic airspace, sent lahars more than 35 km down the Drift River to the coast, and resulted in tephra fall on communities over 100 km away. Geodetic data suggest that magma began to ascend slowly from deep in the crust and reached mid- to shallow-crustal levels as early as May, 2008. Heat flux at the volcano during the precursory phase melted ~ 4% of the Drift glacier atop Redoubt's summit. Petrologic data indicate the deeply sourced magma, low-silica andesite, temporarily arrested at 9-11 km and/or at 4-6 km depth, where it encountered and mixed with segregated stored high-silica andesite bodies. The two magma compositions mixed to form intermediate-silica andesite, and all three magma types erupted during the earliest 2009 events. Only intermediate- and high-silica andesites were produced throughout the explosive and effusive phases of the eruption. The explosive phase began with a phreatic explosion followed by a seismic swarm, which signaled the start of lava effusion on March 22, shortly prior to the first magmatic explosion early on March 23, 2009 (UTC). More than 19 explosions (or “Events”) were produced over 13 days from a single vent immediately south of the 1989-90 lava domes. During that period multiple small pyroclastic density currents flowed primarily to the north and into glacial ravines, three major lahars flooded the Drift River Terminal over 35 km down-river on the coast, tephra fall deposited on all aspects of the edifice and on several communities north and east of the volcano, and at least two, and possibly three lava domes were emplaced. Lightning accompanied almost all the explosions. A shift in the eruptive character took place following Event 9 on March 27 in terms of infrasound signal onsets, the character of repeating earthquakes, and the nature of tephra ejecta. More than nine additional explosions occurred in the next two days, followed by a hiatus in explosive activity between March 29 and April 4. During this hiatus effusion of a lava dome occurred, whose growth slowed on or around April 2. The final explosion pulverized the very poorly vesicular dome on April 4, and was immediately followed by the extrusion of the final dome that ceased growing by July 1, 2009, and reached 72 M m3 in bulk volume. The dome remains as of this writing. Effusion of the final dome in the first month produced blocky intermediate- to high-silica andesite lava, which then expanded by means of lava injection beneath a fracturing and annealing, cooling surface crust. In the first week of May, a seismic swarm accompanied extrusion of an intermediate- to high-silica andesite from the apex of the dome that was highly vesicular and characterized by lower P2O5 content. The dome remained stable throughout its growth period likely due to combined factors that include an emptied conduit system, steady degassing through coalesced vesicles in the effusing lava, and a large crater-pit created by the previous explosions. We estimate the total volume of erupted material from the 2009 eruption to be between ~ 80 M and 120 M m3 dense-rock equivalent (DRE). The aim of this report is to synthesize the results from various datasets gathered both during the eruption and retrospectively, and which are represented by the papers in this publication. We therefore provide an overall view of the 2009 eruption and an introduction to this special issue publication.

Acute sedimentation response to rainfall following the explosive phase of the 2008-2009 eruption of Chaitén volcano, Chile

USGS Publications Warehouse

Pierson, Thomas C.; Major, Jon J.; Amigo, Álvaro; Moreno, Hugo

2013-01-01

The 10-day explosive phase at the start of the 2008–2009 eruption of Chaitén volcano in southern Chile (42.83°S, 72.65°W) blanketed the steep, rain-forest-cloaked, 77-km2 Chaitén River drainage basin with 3 to >100 cm of tephra; predominantly fine to extremely fine rhyolitic ash fell during the latter half of the explosive phase. Rain falling on this ash blanket within days of cessation of major explosive activity generated a hyperconcentrated-flow lahar, followed closely by a complex, multi-day, muddy flood (streamflow bordering on dilute hyperconcentrated flow). Sediment mobilized in this lahar-flood event filled the Chaitén River channel with up to 7 m of sediment, buried the town of Chaitén (10 km downstream of the volcano) in up to 3 m of sediment, and caused the lower 3 km of the channel to avulse through the town. Although neither the nature nor rate of the sedimentation response is unprecedented, they are unusual in several ways: (1) Nearly 70 percent of the aggradation (almost 5 m) in the 50–70-m-wide Chaitén River channel was caused by a lahar, triggered by an estimated 20 mm of rainfall over a span of about 24 h. An additional 2 m of aggradation occurred in the next 24–36 h. (2) Direct damage to the town was accomplished by the sediment-laden water-flood phase of the lahar-flood event, not the lahar phase. (3) The volume of sediment eroded from hillslopes and delivered to the Chaitén River channel was at least 3–8 × 106 m3—roughly 15–40 % of the minimum tephra volume that mantled the Chaitén River drainage basin. (4) The acute sedimentation response to rainfall appears to have been due to the thickness and fineness of the ash blanket (inhibiting infiltration of rain) and the steepness of the basin’s hillslopes. Other possible factors such as the prior formation of an ash crust, development of a hydrophobic surface layer, or large-scale destruction of rain-intercepting vegetation did not play a role.

The 2005 eruption of Kliuchevskoi volcano: Chronology and processes derived from ASTER spaceborne and field-based data

NASA Astrophysics Data System (ADS)

Rose, Shellie; Ramsey, Michael

2009-07-01

Kliuchevskoi volcano, located on the Kamchatka peninsula of eastern Russia, is one of the largest and most active volcanoes in the world. Its location and diversity of eruption styles make satellite-based monitoring and characterization of its eruptive activity essential. In 2005, the Kamchatka Volcano Emergency Response Team (KVERT) first reported that seismic activity of Kliuchevskoi increased above background levels on 12 January (Kamchatka Volcanic Eruption Response Team (KVERT) Report, 2005. Kliuchevskoi Volcano, 14 January through 13 May 2005. ( http://www.avo.alaska.edu/activity/avoreport.php?view=kam info&id=&month=January&year=2005). Cited January 2007). By 15 January Kliuchevskoi entered an explosive-effusive phase, which lasted for five months and produced basaltic lava flows, lahar deposits, and phreatic explosions along its northwestern flank. We present a comparison between field observations and multispectral satellite image data acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument in order to characterize the eruptive behavior. The ASTER instrument was targeted in an automated urgent request mode throughout the eruption timeline in order to collect data at the highest observation frequency possible. Brightness temperatures were calculated in all three ASTER wavelength regions during lava flow emplacement. The maximum lava flow brightness temperatures, calculated from the 15 m/pixel visible near infrared (VNIR) data, were in excess of 800 °C. The shortwave infrared (SWIR) data were radiometrically and geometrically corrected, normalized to the same gain settings, and used to estimate an eruptive volume of 2.35 × 10 - 2 km 3 at the summit. These data were also used to better constrain errors arising in the thermal infrared (TIR) data due to sub-pixel thermal heterogeneities. Based on all the ASTER data, the eruption was separated into three phases: an initial explosive phase (20 January-31 January), an explosive-effusive phase (1 February-8 March), and a subsequent cooling phase. Decorrelation stretch (DCS) images of the TIR data also suggested the presence of silicate ash, SO 2, and water vapor plumes that extended up to 300 km from the summit. The ASTER rapid-response program provided important multispectral, moderate spatial resolution information that was used to detect and monitor the eruptive activity of this remote volcano which can be applied to other eruptions worldwide.

Coal-Face Fracture With A Two-Phase Liquid

NASA Technical Reports Server (NTRS)

Collins, E. R., Jr.

1985-01-01

In new method for mining coal without explosive, two-phase liquid such as CO2 and water, injected at high pressure into deeper ends of holes drilled in coal face. Liquid permeates coal seam through existing microfractures; as liquid seeps back toward face, pressure eventually drops below critical value at which dissolved gas flashvaporizes, breaking up coal.

Sensitized Liquid Hydrazine Detonation Studies

NASA Technical Reports Server (NTRS)

Rathgeber, K. A.; Keddy, C. P.; Bunker, R. L.

1999-01-01

Vapor-phase hydrazine (N2H4) is known to be very sensitive to detonation while liquid hydrazine is very insensitive to detonation, theoretically requiring extremely high pressures to induce initiation. A review of literature on solid and liquid explosives shows that when pure explosive substances are infiltrated with gas cavities, voids, and/or different phase contaminants, the energy or shock pressure necessary to induce detonation can decrease by an order of magnitude. Tests were conducted with liquid hydrazine in a modified card-gap configuration. Sensitization was attempted by bubbling helium gas through and/or suspending ceramic microspheres in the liquid. The hydrazine was subjected to the shock pressure from a 2 lb (0.9 kg) Composition C-4 explosive charge. The hydrazine was contained in a 4 in. (10.2 cm) diameter stainless steel cylinder with a 122 in(sup 3) (2 L) volume and sealed with a polyethylene cap. Blast pressures from the events were recorded by 63 high speed pressure transducers located on three radial legs extending from 4 to 115 ft (1.2 to 35.1 in) from ground zero. Comparison of the neat hydrazine and water baseline tests with the "sensitized" hydrazine tests indicates the liquid hydrazine did not detonate under these conditions.

SN 2015ba: a Type IIP supernova with a long plateau.

NASA Astrophysics Data System (ADS)

Dastidar, Raya; Misra, Kuntal; Hosseinzadeh, G.; Pastorello, A.; Pumo, M. L.; Valenti, S.; McCully, C.; Tomasella, L.; Arcavi, I.; Elias-Rosa, N.; Singh, Mridweeka; Gangopadhyay, Anjasha; Howell, D. A.; Morales-Garoffolo, Antonia; Zampieri, L.; Kumar, Brijesh; Turatto, M.; Benetti, S.; Tartaglia, L.; Ochner, P.; Sahu, D. K.; Anupama, G. C.; Pandey, S. B.

2018-06-01

We present optical photometry and spectroscopy from about a week after explosion to ˜272 d of an atypical Type IIP supernova, SN 2015ba, which exploded in the edge-on galaxy IC 1029. SN 2015ba is a luminous event with an absolute V-band magnitude of -17.1 ± 0.2 mag at 50 d since explosion and has a long plateau lasting for ˜123 d. The distance to the SN is estimated to be 34.8 ± 0.7 Mpc using the expanding photosphere and standard candle methods. High-velocity H Balmer components constant with time are observed in the late-plateau phase spectra of SN 2015ba, which suggests a possible role of circumstellar interaction at these phases. Both hydrodynamical and analytical modelling suggest a massive progenitor of SN 2015ba with a pre-explosion mass of 24-26 M⊙. However, the nebular spectra of SN 2015ba exhibit insignificant levels of oxygen, which is otherwise expected from a massive progenitor. This might be suggestive of the non-monotonical link between O-core masses and the zero-age main-sequence mass of pre-supernova stars and/or uncertainties in the mixing scenario in the ejecta of supernovae.

Coupling crystal plasticity and phase-field damage to simulate β-HMX-based polymer-bonded explosive under shock load

NASA Astrophysics Data System (ADS)

Grilli, Nicolo; Dandekar, Akshay; Koslowski, Marisol

2017-06-01

The development of high explosive materials requires constitutive models that are able to predict the influence of microstructure and loading conditions on shock sensitivity. In this work a model at the continuum-scale for the polymer-bonded explosive constituted of β-HMX particles embedded in a Sylgard matrix is developed. It includes a Murnaghan equation of state, a crystal plasticity model, based on power-law slip rate and hardening, and a phase field damage model based on crack regularization. The temperature increase due to chemical reactions is introduced by a heat source term, which is validated using results from reactive molecular dynamics simulations. An initial damage field representing pre-existing voids and cracks is used in the simulations to understand the effect of these inhomogeneities on the damage propagation and shock sensitivity. We show the predictions of the crystal plasticity model and the effect of the HMX crystal orientation on the shock initiation and on the dissipated plastic work and damage propagation. The simulation results are validated with ultra-fast dynamic transmission electron microscopy experiments and x-ray experiments carried out at Purdue University. Membership Pending.

Improved Overpressure Recording and Modeling for Near-Surface Explosion Forensics

NASA Astrophysics Data System (ADS)

Kim, K.; Schnurr, J.; Garces, M. A.; Rodgers, A. J.

2017-12-01

The accurate recording and analysis of air-blast acoustic waveforms is a key component of the forensic analysis of explosive events. Smartphone apps can enhance traditional technologies by providing scalable, cost-effective ubiquitous sensor solutions for monitoring blasts, undeclared activities, and inaccessible facilities. During a series of near-surface chemical high explosive tests, iPhone 6's running the RedVox infrasound recorder app were co-located with high-fidelity Hyperion overpressure sensors, allowing for direct comparison of the resolution and frequency content of the devices. Data from the traditional sensors is used to characterize blast signatures and to determine relative iPhone microphone amplitude and phase responses. A Wiener filter based source deconvolution method is applied, using a parameterized source function estimated from traditional overpressure sensor data, to estimate system responses. In addition, progress on a new parameterized air-blast model is presented. The model is based on the analysis of a large set of overpressure waveforms from several surface explosion test series. An appropriate functional form with parameters determined empirically from modern air-blast and acoustic data will allow for better parameterization of signals and the improved characterization of explosive sources.

Enhanced Raman spectroscopy of 2,4,6-TNT in anatase and rutile titania nanocrystals

NASA Astrophysics Data System (ADS)

De La Cruz-Montoya, Edwin; Jeréz, Jaqueline I.; Balaguera-Gelves, Marcia; Luna-Pineda, Tatiana; Castro, Miguel E.; Hernández-Rivera, Samuel P.

2006-05-01

The majority of explosives found in antipersonnel and antitank landmines contain 2,4,6-trinitrotoluene (TNT). Chemical sensing of landmines and Improvised Explosive Devices (IED) requires detecting the chemical signatures of the explosive components in these devices. Nanotechnology is ideally suited to needs in microsensors development by providing new materials and methods that can be employed for trace explosive detection. This work is focused on modification of nano-scaled colloids of titanium dioxide (Titania: anatase, rutile and brookite) and thin layer of the oxides as substrates for use in Enhanced Raman Scattering (ERS) spectroscopy. Ultrafine particles have been generated by hydrothermally treating the sol-gel derived hydrous oxides. ERS spectra of nanocrystalline anatase Titania samples prepared with different average sizes: 38 nm (without acid), 24 nm (without acid) and 7 nm (with HCl). Bulk phase (commercial) and KBr were also used to prepare mixtures with TNT to look for Enhanced Raman Effect of the nitroaromatic explosive on the test surfaces. The studies clearly indicated that the anatase crystal size affects the enhancement of the TNT Raman signal. This enhancement was highest for the samples with Titania average crystal size of 7 nm.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shumway, R.H.; McQuarrie, A.D.

Robust statistical approaches to the problem of discriminating between regional earthquakes and explosions are developed. We compare linear discriminant analysis using descriptive features like amplitude and spectral ratios with signal discrimination techniques using the original signal waveforms and spectral approximations to the log likelihood function. Robust information theoretic techniques are proposed and all methods are applied to 8 earthquakes and 8 mining explosions in Scandinavia and to an event from Novaya Zemlya of unknown origin. It is noted that signal discrimination approaches based on discrimination information and Renyi entropy perform better in the test sample than conventional methods based onmore » spectral ratios involving the P and S phases. Two techniques for identifying the ripple-firing pattern for typical mining explosions are proposed and shown to work well on simulated data and on several Scandinavian earthquakes and explosions. We use both cepstral analysis in the frequency domain and a time domain method based on the autocorrelation and partial autocorrelation functions. The proposed approach strips off underlying smooth spectral and seasonal spectral components corresponding to the echo pattern induced by two simple ripple-fired models. For two mining explosions, a pattern is identified whereas for two earthquakes, no pattern is evident.« less

Evaluation of the SSRCT engine with a hydrazine as a fuel, phase 1

NASA Technical Reports Server (NTRS)

Minton, S. J.

1978-01-01

The performance parameters for the space shuttle reaction control thruster (SSRCT) when the fuel is changed from monomethylhydrazine to hydrazine were predicted. Potential problems are higher chamber wall temperature during steady state operation and explosive events during pulse mode operation. Solutions to the problems are suggested. To conduct the analysis, a more realistic film cooling model was devised which considers that hydrazine based fuels are reactive when used as a film coolant on the walls of the combustion chamber. Hydrazine based fuels can decompose exothermally as a monopropellant and also enter into bipropellant reactions with any excess oxidizer in the combustion chamber. It is concluded that the conversion of the thruster from MMH to hydrazine fuel is feasible but that a number of changes would be required to achieve the same safety margins as the monomethylhydrazine-fueled thruster.

Development of graphene nanoplatelet embedded polymer microcantilever for vapour phase explosive detection applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ray, Prasenjit; Pandey, Swapnil; Ramgopal Rao, V.

2014-09-28

In this work, a graphene based strain sensor has been reported for explosive vapour detection applications by exploiting the piezoresistive property of graphene. Instead of silicon based cantilevers, a low cost polymeric micro-cantilever platform has been used to fabricate this strain sensor by embedding the graphene nanoplatelet layer inside the beam. The fabricated devices were characterized for their mechanical and electromechanical behaviour. This device shows a very high gauge factor which is around ~144. Also the resonant frequency of these cantilevers is high enough such that the measurements are not affected by environmental noise. These devices have been used inmore » this work for reliable detection of explosive vapours such as 2,4,6-Trinitrotoluene down to parts-per-billion concentrations in ambient conditions.« less

Detecting Surface Changes from an Underground Explosion in Granite Using Unmanned Aerial System Photogrammetry

DOE PAGES

Schultz-Fellenz, Emily S.; Coppersmith, Ryan T.; Sussman, Aviva J.; ...

2017-08-19

Efficient detection and high-fidelity quantification of surface changes resulting from underground activities are important national and global security efforts. In this investigation, a team performed field-based topographic characterization by gathering high-quality photographs at very low altitudes from an unmanned aerial system (UAS)-borne camera platform. The data collection occurred shortly before and after a controlled underground chemical explosion as part of the United States Department of Energy’s Source Physics Experiments (SPE-5) series. The high-resolution overlapping photographs were used to create 3D photogrammetric models of the site, which then served to map changes in the landscape down to 1-cm-scale. Separate models weremore » created for two areas, herein referred to as the test table grid region and the nearfield grid region. The test table grid includes the region within ~40 m from surface ground zero, with photographs collected at a flight altitude of 8.5 m above ground level (AGL). The near-field grid area covered a broader area, 90–130 m from surface ground zero, and collected at a flight altitude of 22 m AGL. The photographs, processed using Agisoft Photoscan® in conjunction with 125 surveyed ground control point targets, yielded a 6-mm pixel-size digital elevation model (DEM) for the test table grid region. This provided the ≤3 cm resolution in the topographic data to map in fine detail a suite of features related to the underground explosion: uplift, subsidence, surface fractures, and morphological change detection. The near-field grid region data collection resulted in a 2-cm pixel-size DEM, enabling mapping of a broader range of features related to the explosion, including: uplift and subsidence, rock fall, and slope sloughing. This study represents one of the first works to constrain, both temporally and spatially, explosion-related surface damage using a UAS photogrammetric platform; these data will help to advance the science of underground explosion detection.« less

Detecting Surface Changes from an Underground Explosion in Granite Using Unmanned Aerial System Photogrammetry

NASA Astrophysics Data System (ADS)

Schultz-Fellenz, Emily S.; Coppersmith, Ryan T.; Sussman, Aviva J.; Swanson, Erika M.; Cooley, James A.

2017-08-01

Efficient detection and high-fidelity quantification of surface changes resulting from underground activities are important national and global security efforts. In this investigation, a team performed field-based topographic characterization by gathering high-quality photographs at very low altitudes from an unmanned aerial system (UAS)-borne camera platform. The data collection occurred shortly before and after a controlled underground chemical explosion as part of the United States Department of Energy's Source Physics Experiments (SPE-5) series. The high-resolution overlapping photographs were used to create 3D photogrammetric models of the site, which then served to map changes in the landscape down to 1-cm-scale. Separate models were created for two areas, herein referred to as the test table grid region and the nearfield grid region. The test table grid includes the region within 40 m from surface ground zero, with photographs collected at a flight altitude of 8.5 m above ground level (AGL). The near-field grid area covered a broader area, 90-130 m from surface ground zero, and collected at a flight altitude of 22 m AGL. The photographs, processed using Agisoft Photoscan® in conjunction with 125 surveyed ground control point targets, yielded a 6-mm pixel-size digital elevation model (DEM) for the test table grid region. This provided the ≤3 cm resolution in the topographic data to map in fine detail a suite of features related to the underground explosion: uplift, subsidence, surface fractures, and morphological change detection. The near-field grid region data collection resulted in a 2-cm pixel-size DEM, enabling mapping of a broader range of features related to the explosion, including: uplift and subsidence, rock fall, and slope sloughing. This study represents one of the first works to constrain, both temporally and spatially, explosion-related surface damage using a UAS photogrammetric platform; these data will help to advance the science of underground explosion detection.

Detecting Surface Changes from an Underground Explosion in Granite Using Unmanned Aerial System Photogrammetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schultz-Fellenz, Emily S.; Coppersmith, Ryan T.; Sussman, Aviva J.

Efficient detection and high-fidelity quantification of surface changes resulting from underground activities are important national and global security efforts. In this investigation, a team performed field-based topographic characterization by gathering high-quality photographs at very low altitudes from an unmanned aerial system (UAS)-borne camera platform. The data collection occurred shortly before and after a controlled underground chemical explosion as part of the United States Department of Energy’s Source Physics Experiments (SPE-5) series. The high-resolution overlapping photographs were used to create 3D photogrammetric models of the site, which then served to map changes in the landscape down to 1-cm-scale. Separate models weremore » created for two areas, herein referred to as the test table grid region and the nearfield grid region. The test table grid includes the region within ~40 m from surface ground zero, with photographs collected at a flight altitude of 8.5 m above ground level (AGL). The near-field grid area covered a broader area, 90–130 m from surface ground zero, and collected at a flight altitude of 22 m AGL. The photographs, processed using Agisoft Photoscan® in conjunction with 125 surveyed ground control point targets, yielded a 6-mm pixel-size digital elevation model (DEM) for the test table grid region. This provided the ≤3 cm resolution in the topographic data to map in fine detail a suite of features related to the underground explosion: uplift, subsidence, surface fractures, and morphological change detection. The near-field grid region data collection resulted in a 2-cm pixel-size DEM, enabling mapping of a broader range of features related to the explosion, including: uplift and subsidence, rock fall, and slope sloughing. This study represents one of the first works to constrain, both temporally and spatially, explosion-related surface damage using a UAS photogrammetric platform; these data will help to advance the science of underground explosion detection.« less

Los Alamos Explosives Performance Key to Stockpile Stewardship

ScienceCinema

Dattelbaum, Dana

2018-02-14

As the U.S. Nuclear Deterrent ages, one essential factor in making sure that the weapons will continue to perform as designed is understanding the fundamental properties of the high explosives that are part of a nuclear weapons system. As nuclear weapons go through life extension programs, some changes may be advantageous, particularly through the addition of what are known as "insensitive" high explosives that are much less likely to accidentally detonate than the already very safe "conventional" high explosives that are used in most weapons. At Los Alamos National Laboratory explosives research includes a wide variety of both large- and small-scale experiments that include small contained detonations, gas and powder gun firings, larger outdoor detonations, large-scale hydrodynamic tests, and at the Nevada Nuclear Security Site, underground sub-critical experiments.

Particle transport in subaqueous eruptions: An experimental investigation

NASA Astrophysics Data System (ADS)

Verolino, A.; White, J. D. L.; Zimanowski, B.

2018-01-01

Subaqueous volcanic eruptions are natural events common under the world's oceans. Here we report results from bench-scale underwater explosions that entrain and eject particles into a water tank. Our aim was to examine how particles are transferred to the water column and begin to sediment from it, and to visualize and interpret evolution of the 'eruption' cloud. Understanding particle transfer to water is a key requirement for using deposit characteristics to infer behaviour and evolution of an underwater eruption. For the experiments here, we used compressed argon to force different types of particles, under known driving pressures, into water within a container, and recorded the results at 1 MPx/frame and 1000 fps. Three types of runs were completed: (1) particles within water were driven into a water-filled container; (2) dry particles were driven into water; (3) dry particles were driven into air at atmospheric pressure. Across the range of particles used for all subaqueous runs, we observed: a) initial doming, b) a main expansion of decompressing gas, and c) a phase of necking, when a forced plume separated from the driving jet. Phase c did not take place for the subaerial runs. A key observation is that none of the subaqueous explosions produced a single, simple, open cavity; in all cases, multiphase mixtures of gas bubbles, particles and water were formed. Explosions in which the expanding argon ejects particles in air, analogous to delivery of particles created in an explosion, produce jets and forced plumes that release particles into the tank more readily than do those in which particles in water are driven into the tank. The latter runs mimic propulsion of an existing vent slurry by an explosion. Explosions with different particle types also yielded differences in behaviour controlled primarily by particle mass, particle density, and particle-population homogeneity. Particles were quickly delivered into the water column during plume rise following necking, with minor transfer along initial-jet margins, and for breaching explosions additional delivery from splashdown of tephra jets. Plume rise after necking also draws upward and re-entrains some groups of particles. Most delivered particles participate in initiating vertical sediment-gravity flows, some of which reached the tank floor and began lateral flow within the short duration of our experiments. Particles transferred from plume margins locally were sufficiently well-separated to settle independently from suspension.

Modelling and Testing of Blast Effect On the Structures

NASA Astrophysics Data System (ADS)

Figuli, Lucia; Jangl, Štefan; Papán, Daniel

2016-10-01

As a blasting agent in the blasting and mining engineering, has been using one of so called new generation of explosives which offer greater flexibility in their range and application, and such explosive is ANFO. It is type of explosive consists of an oxidiser and a fuel (ammonium nitrate and fuel oil). One of such ANFO explosives which are industrially made in Slovakia is POLONIT. The explosive is a mixture of ammonium nitrate, methyl esters of higher fatty acids, vegetable oil and red dye. The paper deals with the analysis of structure subjected to the blast load created by the explosion of POLONIT charge. First part of paper is describing behaviour and characteristic of blast wave generated from the blast (detonation characteristics, physical characteristics, time-history diagram etc.) and the second part presents the behaviour of such loaded structures, because of the analysis of such dynamical loaded structure is required knowing the parameters of blast wave, its effect on structure and the tools for the solution of dynamic analysis. The real field tests of three different weight of charges and two different structures were done. The explosive POLONIT was used together with 25 g of ignition explosive PLNp10. Analytical and numerical model of blast loaded structure is compared with the results obtained from the field tests (is compared with the corresponding experimental accelerations). For the modelling structures were approximated as a one-degree system of freedom (SDOF), where the blast wave was estimated with linear decay and exponential decay using positive and negative phase of blast wave. Numerical solution of the steel beam dynamic response was performed via FEM (Finite Element Method) using standard software Visual FEA.

Numerical modelling of underwater detonation of non-ideal condensed-phase explosives

NASA Astrophysics Data System (ADS)

Schoch, Stefan; Nikiforakis, Nikolaos

2015-01-01

The interest in underwater detonation tests originated from the military, since the expansion and subsequent collapse of the explosive bubble can cause considerable damage to surrounding structures or vessels. In military applications, the explosive is typically represented as a pre-burned material under high pressure, a reasonable assumption due to the short reaction zone lengths, and complete detonation of the unreacted explosive. Hence, numerical simulations of underwater detonation tests have been primarily concerned with the prediction of target loading and the damage incurred rather than the accurate modelling of the underwater detonation process. The mining industry in contrast has adopted the underwater detonation test as a means to experimentally characterise the energy output of their highly non-ideal explosives depending on explosive type and charge configuration. This characterisation requires a good understanding of how the charge shape, pond topography, charge depth, and additional charge confinement affect the energy release, some of which can be successfully quantified with the support of accurate numerical simulations. In this work, we propose a numerical framework which is able to capture the non-ideal explosive behaviour and in addition is capable of capturing both length scales: the reaction zone and the pond domain. The length scale problem is overcome with adaptive mesh refinement, which, along with the explosive model, is validated against experimental data of various TNT underwater detonations. The variety of detonation and bubble behaviour observed in non-ideal detonations is demonstrated in a parameter study over the reactivity of TNT. A representative underwater mining test containing an ammonium-nitrate fuel-oil ratestick charge is carried out to demonstrate that the presented method can be readily applied alongside experimental underwater detonation tests.

Equations of State and High-Pressure Phases of Explosives

NASA Astrophysics Data System (ADS)

Peiris, Suhithi M.; Gump, Jared C.

Energetic materials, being the collective name for explosives, propellants, pyrotechnics, and other flash-bang materials, span a wide range of composite chemical formulations. Most militarily used energetics are solids composed of particles of the pure energetic material held together by a binder. Commonly used binders include various oils, waxes, and polymers or plasticizers, and the composite is melt cast, cured, or pressed to achieve the necessary mechanical properties (gels, putties, sheets, solid blocks, etc.) of the final energetic material. Mining, demolition, and other industries use liquid energetics that are similarly composed of an actual energetic material or oxidizer together with a fuel, that is to be mixed and poured for detonation. Pure energetic materials that are commonly used are nitroglycerine, ammonium nitrate, ammonium or sodium perchlorate, trinitrotoluene (TNT), HMX, RDX, and TATB. All of them are molecular materials or molecular ions that when initiated or insulted undergoes rapid decomposition with excessive liberation of heat resulting in the formation of stable final products. When the final products are gases, and they are rapidly produced, the sudden pressure increase creates a shock wave. When decomposition is so rapid that the reaction moves through the explosive faster than the speed of sound in the unreacted explosive, the material is said to detonate. Typically, energetic materials that undergo detonation are known as high explosives (HEs) and energetic materials that burn rapidly or deflagrate are known as low explosives and/or propellants.

An Experimental Study of Corner Turning in a Granular Ammonium Nitrate Based Explosive

NASA Astrophysics Data System (ADS)

Sorber, S.; Taylor, P.; Burns, M.

2007-12-01

A novel experimental geometry has been designed to perform controlled studies of corner turning in a "tap density" granular explosive. It enables the study of corner turning and detonation properties with high speed framing camera, piezo probes and ionisation probes. The basic geometry consists of a large diameter PMMA cylinder filled with the granular explosive and is initiated on axis from below by a smaller diameter cylinder of granular explosive or a booster charge. Four experiments were performed on a granular Ammonium Nitrate based non-ideal explosive (NIE). Two experiments were initiated directly with the PE4 booster and two were initiated from a train including a booster charge and a 1″ diameter copper cylinder containing the same NIE. Experimental data from the four experiments was reproducible and the observed detonation and shock waves showed good 2-D symmetry. Detonation phase velocity on the vertical side of the main container was observed and both shock and detonation velocities were observed in the corner turning region along the base of the main container. Analysis of the data shows that the booster-initiated geometries with a higher input shock pressure into the granular explosive gave earlier detonation arrival at the lowest probes on the container side. The corner turning data is compared to a hydrocode calculation using a simple JWL++ reactive burn model.

Effect of W/O Emulsion Fuel Properties on Spray Combustion

NASA Astrophysics Data System (ADS)

Ida, Tamio; Fuchihata, Manabu; Takeda, Shuuco

This study proposes a realizable technology for an emulsion combustion method that can reduce environmental loading. This paper discusses the effect on spray combustion for W/O emulsion fuel properties with an added agent, and the ratio between water and emulsifier added to a liquid fuel. The addition of water or emulsifier to a liquid fuel affected the spray combustion by causing micro-explosions in the flame due to geometric changes in the sprayed flame and changes to the temperature distribution. Experimental results revealed that the flame length shortened by almost 40% upon the addition of the water. Furthermore, it was found that water was effective in enhancing combustion due to its promoting micro-explosions. Results also showed that when the emulsifier was added to the spray flame, the additive burned in the flame's wake, producing a bright red flame. The flame length was observed to be long as a result. The micro-explosion phenomenon, caused by emulsifier dosage differences, was observed using time-dependent images at a generated frequency and an explosion scale with a high-speed photography method. Results indicated that the micro-explosion phenomenon in the W/O emulsion combustion method effectively promoted the combustion reaction and suppressed soot formation.

Fate dynamics of environmentally exposed explosive traces.

PubMed

Kunz, Roderick R; Gregory, Kerin E; Aernecke, Matthew J; Clark, Michelle L; Ostrinskaya, Alla; Fountain, Augustus W

2012-04-12

The chemical and physical fates of trace amounts (<50 μg) of explosives containing 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and pentaerythritol tetranitrate (PETN) were determined for the purpose of informing the capabilities of tactical trace explosive detection systems. From these measurements, it was found that the mass decreases and the chemical composition changes on a time scale of hours, with the loss mechanism due to a combination of sublimation and photodegradation. The rates for these processes were dependent on the explosive composition, as well as on both the ambient temperature and the size distribution of the explosive particulates. From these results, a persistence model was developed and applied to model the time dependence of both the mass and areal coverage of the fingerprints, resulting in a predictive capability for determining fingerprint fate. Chemical analysis confirmed that sublimation rates for TNT were depressed by UV (330-400 nm) exposure due to photochemically driven increases in the molecular weight, whereas the opposite was observed for RDX. No changes were observed for PETN upon exposure to UV radiation, and this was attributed to its low UV absorbance.

SN 2013fs and SN 2013fr: exploring the circumstellar-material diversity in Type II supernovae

NASA Astrophysics Data System (ADS)

Bullivant, Christopher; Smith, Nathan; Williams, G. Grant; Mauerhan, Jon C.; Andrews, Jennifer E.; Fong, Wen-Fai; Bilinski, Christopher; Kilpatrick, Charles D.; Milne, Peter A.; Fox, Ori D.; Cenko, S. Bradley; Filippenko, Alexei V.; Zheng, WeiKang; Kelly, Patrick L.; Clubb, Kelsey I.

2018-05-01

We present photometry and spectroscopy of SN 2013fs and SN 2013fr in the first ˜100 d post-explosion. Both objects showed transient, relatively narrow H α emission lines characteristic of SNe IIn, but later resembled normal SNe II-P or SNe II-L, indicative of fleeting interaction with circumstellar material (CSM). SN 2013fs was discovered within 8 h of explosion; one of the earliest SNe discovered thus far. Its light curve exhibits a plateau, with spectra revealing strong CSM interaction at early times. It is a less luminous version of the transitional SN IIn PTF11iqb, further demonstrating a continuum of CSM interaction intensity between SNe II-P and SNe IIn. It requires dense CSM within 6.5 × 1014 cm of the progenitor, from a phase of advanced pre-SN mass loss beginning shortly before explosion. Spectropolarimetry of SN 2013fs shows little continuum polarization (˜0.5 per cent, consistent with zero), but noticeable line polarization during the plateau phase. SN 2013fr morphed from an SN IIn at early times to an SN II-L. After the first epoch, its narrow lines probably arose from host-galaxy emission, but the bright, narrow H α emission at early times may be intrinsic to the SN. As for SN 2013fs, this would point to a short-lived phase of strong CSM interaction if proven to be intrinsic, suggesting a continuum between SNe IIn and SNe II-L. It is a low-velocity SN II-L like SN 2009kr, but more luminous. SN 2013fr also developed an infrared excess at later times, due to warm CSM dust that requires a more sustained phase of strong pre-SN mass loss.

Carbon Condensation during High Explosive Detonation with Time Resolved Small Angle X-ray Scattering

NASA Astrophysics Data System (ADS)

Hammons, Joshua; Bagge-Hansen, Michael; Nielsen, Michael; Lauderbach, Lisa; Hodgin, Ralph; Bastea, Sorin; Fried, Larry; May, Chadd; Sinclair, Nicholas; Jensen, Brian; Gustavsen, Rick; Dattelbaum, Dana; Watkins, Erik; Firestone, Millicent; Ilavsky, Jan; van Buuren, Tony; Willey, Trevor; Lawrence Livermore National Lab Collaboration; Los Alamos National Laboratory Collaboration; Washington State University/Advanced Photon Source Team

Carbon condensation during high-energy detonations occurs under extreme conditions and on very short time scales. Understanding and manipulating soot formation, particularly detonation nanodiamond, has attracted the attention of military, academic and industrial research. An in-situ characterization of these nanoscale phases, during detonation, is highly sought after and presents a formidable challenge even with today's instruments. Using the high flux available with synchrotron X-rays, pink beam small angle X-ray scattering is able to observe the carbon phases during detonation. This experimental approach, though powerful, requires careful consideration and support from other techniques, such as post-mortem TEM, EELS and USAXS. We present a comparative survey of carbon condensation from different CHNO high explosives. This work was performed under the auspices of the US DOE by LLNL under Contract DE-AC52-07NA27344.

Fe nanoparticles produced by electric explosion of wire for new generation of magneto-rheological fluids

NASA Astrophysics Data System (ADS)

Berasategi, Joanes; Gomez, Ainara; Mounir Bou-Ali, M.; Gutiérrez, Jon; Barandiarán, Jose Manuel; Beketov, Igor V.; Safronov, Aleksander P.; Kurlyandskaya, Galina V.

2018-04-01

Iron magnetic nanoparticles were produced by the technique of the electric explosion of a wire (EEW). The major crystalline phase (95 ± 1%) was α-Fe with lattice parameter a = 0.2863(3) nm. The size of the coherent diffraction domains of this phase was 77 ± 3 nm. The EEW MNPs presented a large saturation magnetization value, reaching about 87% of the saturation magnetization of the bulk iron. EEW NMPs demonstrated an improved magnetic performance when used in magnetorheological (MR) fluids with respect to the commercial carbonyl iron particles (CIPs) micron-sized particles studied for comparison. The MR fluids composed with the EEW nanoparticles showed larger yield stress values than those with CIP micron-sized particles, so proving that the EEW MNPs have a high potential for MR fluids applications.

How Will Climate Change Affect Explosive Cyclones in the Extratropics of the Northern Hemisphere?

NASA Astrophysics Data System (ADS)

Seiler, C.; Zwiers, F. W.

2015-12-01

Explosive cyclones are rapidly intensifying low pressure systems generating severe wind speeds and heavy precipitation primarily in coastal and marine environments, such as the March 2014 nor'easter which developed along the United States coastline, with hurricane force winds in eastern Maine and the Maritimes. This study presents the first analysis on how explosive cyclones respond to climate change in the extratropics of the Northern Hemisphere. An objective-feature tracking algorithm is used to identify and track cyclones from 23 CMIP5 climate models for the recent past (1981-1999) and future (2081-2099). Explosive cyclones are projected to shift northwards by about 2.2° latitude on average in the northern Pacific, with fewer and weaker events south of 45°N, and more frequent and stronger events north of this latitude. This shift is correlated with a poleward shift of the jet stream in the inter-model spread (R = 0.56). In the Atlantic, the total number of explosive cyclones is projected to decrease by about 17% when averaging across models, with the largest changes occurring along North America's East Coast. This reduction is correlated with a decline in the lower-tropospheric Eady growth rate (R = 0.51), and is stronger for models with smaller frequency biases (R = -0.65). The same region is also projected to experience a small intensification of explosive cyclones, with larger vorticity values for models that predict stronger increases in the speed of the jet stream (R = 0.58). This strengthening of the jet stream is correlated with an enhanced sea surface temperature gradient in the North Atlantic (R = -0.63). The inverse relationship between model bias and projection, and the role of model resolution are discussed.

Long-term variations in explosion dynamics at Santiaguito volcano

NASA Astrophysics Data System (ADS)

Lamb, Oliver; De Angelis, Silvio; Lavallée, Yan; Lamur, Anthony; Hornby, Adrian; Von Aulock, Felix; Kendrick, Jackie; Chigna, Gustavo; Rietbrock, Andreas

2017-04-01

Here we present two years of seismic and infrasound observations of ash-and-gas explosions recorded during an ongoing multi-disciplinary experiment at the Santiaguito lava dome complex, Guatemala. Due to the occurrence of regular explosive activity since the early 1970's, the volcano is an ideal laboratory for the study of the eruption dynamics of long-lived silicic eruptions. The instrument network, deployed between 0.5 and 7 km from the active vent, includes 5 broadband and 6 short-period seismometers, as well as 5 infrasound sensors. Seismo-acoustic data are complemented by thermal infrared imagery, visual observations from an unmanned aerial vehicle, and geochemical measurements of eruptive products. In mid-2015, a major shift in activity took place at Santiaguito. Vulcanian explosions became more energetic and less regular, and were often accompanied by pyroclastic density currents. Important morphological changes were observed at the active El Caliente dome, as the lava-filled crater was excavated by a sequence of vigorous explosions to a depth of at least 150 m. Variations in the relative arrival times of seismic and infrasound signals suggest a significant deepening of the explosion initiation point inside the conduit. This shift in behaviour likely represents a change in the eruptive mechanism in the upper conduit beneath El Caliente, possibly triggered by disequilibrium at a greater depth in the volcanic system. Our observations suggest a reactivation of the deep magmatic system at Santiaguito, with little precursory activity. The results of this multi-parameteric monitoring experiment have specific implications for hazard assessment at Santiaguito, and contributes to understanding the processes that control changes in eruptive regime at lava dome volcanoes.

Surface soil characterization of explosives and metals at the Land Force Central Area Training Centre (LFCA TC) Meaford, Ontario (Phase 2) Final report

DTIC Science & Technology

2009-10-01

Environment and Director General Environment © Her Majesty the Queen in Right of Canada, as represented by the Minister of National Defence, 2009 © Sa...Majesté la Reine (en droit du Canada), telle que représentée par le ministre de la Défense nationale , 2009 DRDC Valcartier TR 2009-218 i...evaluation of the soil contamination by explosives and metals. In parallel, the Institut national de la recherche scientifique (INRS) conducted

Quantification of Rock Damage from Small Explosions and its Effect on Shear-Wave Generation: Phase I - Homogeneous Crystalline Rock

DTIC Science & Technology

2008-09-30

We hope to quantify crack nucleation and growth (Ashby and Sammis, 1990) as an S-wave generation mechanism in the far-field (Sammis, 2002) and to map...wave generation mechanism in the far-field (Sammis, 2002) and to map the cone of damage (Patton et al. 2005; Stevens et al. 2003) above a source...Two of the proposed mechanisms for S-wave generation involve secondary processes related to the damage and deformations caused by the explosions. First

Updates to concepts on phreatomagmatic maar-diatremes and their pyroclastic deposits

NASA Astrophysics Data System (ADS)

Valentine, Greg A.; White, James D. L.; Ross, Pierre-Simon; Graettinger, Alison H.; Sonder, Ingo

2017-08-01

Recent work is changing our understanding of phreatomagmatic maar-diatreme eruptions and resulting deposits. In previous models, explosions were often inferred to take place only at the base of a diatreme, with progressive downward migration due to a cone of depression in the host aquifer. However, diatremes themselves contain much water that is heterogeneously distributed, and field evidence supports the existence of explosion sites at many vertical and lateral locations within them. Crater sizes have been used to estimate explosion energies, but this only works for single-explosion craters where the depth of explosion is independently known, and has limited value for multi-explosion maar-diatremes. Deep-seated lithic clasts in tephra ring beds have been taken to indicate the depth of the explosion that produced that bed. However, only relatively shallow explosions actually vent to the surface, and deep-seated lithics are gradually brought to shallow depths through step-wise mixing of multiple subsurface explosions. Grain-size of tephra-ring deposits is often inferred to indicate fragmentation efficiency. However, other factors strongly influence deposit grain size, including the scaled depth of an explosion and the interaction of an erupting jet with topography around a vent (e.g., crater), along with long recognized effects of mechanical properties of host rocks and recycling within the vent/diatreme. These insights provide a foundation for future research into this important volcano type.

Pyrotechnic hazards classification and evaluation program. Electrostatic vulnerability of the E8 and XM15/XM165 clusters, phase 1

NASA Technical Reports Server (NTRS)

1970-01-01

A survey of the electrostatic vulnerability of explosive manufacturing plants and recommendations for reducing the vulnerability are discussed. During the course of the investigations, the XM15/XM165 and the E8 launcher were shown to be susceptible to electrostatic ignition. The pyrotechnic hazard of prime concern associated with electrostatics is that of the spark which can be generated. The heat, shock, and ionization produced by the spark can cause ignition of pyrotechnics. However, as a result of the initial ignition tests (XM15 fuse train), changes have been incorporated to make the fusing system relatively safe from premature electrostatic activation.

Analysis of the Explosive Internal Impact on the Barriers of Building Structures

NASA Astrophysics Data System (ADS)

Siwiński, Jarosław; Stolarski, Adam

2017-10-01

Work issues concern the safety of construction in relation to the hazards arising from explosion of the explosive charge located inside the building. The algorithms proposed in the paper for determining the parameters of the overpressure wave resulting from the detonation of clustered explosive charges, determine the basis for numerical simulation analyzes. Determination of the maximum value of peak pressure on the wave forehead of an internal explosion is presented on the basis of reflected wave analysis. Changeability in time of the internal explosion action describes the overpressure phase only. The analysis of the load caused by the internal explosive charge detonation was carried out under conditions of the undisturbed standard atmosphere. A load determination algorithm has been developed, taking into account the geometrical characteristics of the building barriers and the rooms as well as the parameters of environment in which the detonation occurs. The way of taking into account the influence of venting surfaces, i.e. windows, doors, ventilation ducts, on the overpressure wave parameters, was presented. Discloses a method to take into account the effect of the surface relief, i.e. windows, doors, air ducts, pressure wave parameters. Modification of the method for explosive overpressure determination presented by Cormie, Smith, Mays (2009), was proposed in the paper. This modification was developed on the basis of substitute impulse analysis for multiple overpressure pulses. In order to take into account the pressure distribution of explosive gases on the barrier surface, the method of modification the relationship for determination the changeability over time and space of the pressure of explosive gases, was presented. For this purpose, the changeability of the pressure wave angles of incidence to the barrier and the distance of the explosive charge to any point on the surface of the barrier, was taken into account. Based on the developed procedure, the overpressure changeability over time was determined for selected measurement points of the reference room. A comparative analysis of the determined loadings with experimental results and theoretical results of other authors, taken from the original work of Weerhiejm et al. (2012), was carried out.

Swarms of small volcano-tectonic events preceding paroxysmal explosions of Tungurahua volcano (Ecuador)

NASA Astrophysics Data System (ADS)

Battaglia, J.; Hidalgo, S.; Douchain, J. M.; Pacheco, D. A.; Cordova, J.; Alvarado, A. P.; Parra, R.

2017-12-01

Tungurahua (5023 m a.s.l.) is an andesitic volcano located in Central Ecuador. It has been erupting since September 1999. It's activity transitioned in late 2008 towards the occurrence of distinct eruptive phases separated by periods of quiescence. These phases display a great variability of eruptive patterns. In particular the onsets of these phases are quite variable, ranging from progressive increase of surface activity to violent paroxysmal explosions eventually generating pyroclastic flows and plumes up to 13.000 m elevation. The volcano is monitored by the Instituto Geofisico in Quito whose permanent monitoring network include 6 broadband and 6 short period stations. These instruments record various signals related to eruptive processes as well as Long Period and volcano-tectonique (VT) events. However, most of the VT events are scattered around the volcano at depths up to 5-10 km b.s.l.. Their relationship with eruptive activity and precursory aspect are unclear. Since October 2013, we operate a temporary network of 13 broadband stations located up to 4275 m a.s.l., including on the Eastern flank which is remote. We examined data from a reference station located near the summit (3900 m a.s.l.) with a detection and classification procedure, searching for families of similar events. This processing enlights the presence of several families of small VTs previously poorly identified. We located manually some of these events and proceeded with similarity picking using cross-correlation and waveform similarity for nearly 400 events. Finally we applied precise relocation techniques. These events are located 2-3 km below the summit and define vertically elongated streaks. Their temporal evolution shows that they occur in swarms during the days or hours preceding the paroxysmal vent opening explosions in February and April 2014. These short-term precursors could indicate the rupturing of a barrier prior to the large explosions of Tungurahua.

Atomistic modelling of evaporation and explosive boiling of thin film liquid argon over internally recessed nanostructured surface

NASA Astrophysics Data System (ADS)

Hasan, Mohammad Nasim; Shavik, Sheikh Mohammad; Rabbi, Kazi Fazle; Haque, Mominul

2016-07-01

Molecular dynamics (MD) simulations have been carried out to investigate evaporation and explosive boiling phenomena of thin film liquid argon on nanostructured solid surface with emphasis on the effect of solid-liquid interfacial wettability. The nanostructured surface considered herein consists of trapezoidal internal recesses of the solid platinum wall. The wetting conditions of the solid surface were assumed such that it covers both the hydrophilic and hydrophobic conditions and hence effect of interfacial wettability on resulting evaporation and boiling phenomena was the main focus of this study. The initial configuration of the simulation domain comprised of a three phase system (solid platinum, liquid argon and vapor argon) on which equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. After equilibrium of the three-phase system was established, the wall was set to different temperatures (130 K and 250 K for the case of evaporation and explosive boiling respectively) to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat flux normal to the solid surface was also calculated to illustrate the effectiveness of heat transfer for hydrophilic and hydrophobic surfaces in cases of both nanostructured surface and flat surface. The results obtained show that both the wetting condition of the surface and the presence of internal recesses have significant effect on normal evaporation and explosive boiling of the thin liquid film. The heat transfer from solid to liquid in cases of surface with recesses are higher compared to flat surface without recesses. Also the surface with higher wettability (hydrophilic) provides more favorable conditions for boiling than the low-wetting surface (hydrophobic) and therefore, liquid argon responds quickly and shifts from liquid to vapor phase faster in case of hydrophilic surface. The heat transfer rate is also much higher in case of hydrophilic surface.

Atomistic modelling of evaporation and explosive boiling of thin film liquid argon over internally recessed nanostructured surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hasan, Mohammad Nasim, E-mail: nasim@me.buet.ac.bd.com; Shavik, Sheikh Mohammad, E-mail: shavik@me.buet.ac.bd.com; Rabbi, Kazi Fazle, E-mail: rabbi35.me10@gmail.com

2016-07-12

Molecular dynamics (MD) simulations have been carried out to investigate evaporation and explosive boiling phenomena of thin film liquid argon on nanostructured solid surface with emphasis on the effect of solid-liquid interfacial wettability. The nanostructured surface considered herein consists of trapezoidal internal recesses of the solid platinum wall. The wetting conditions of the solid surface were assumed such that it covers both the hydrophilic and hydrophobic conditions and hence effect of interfacial wettability on resulting evaporation and boiling phenomena was the main focus of this study. The initial configuration of the simulation domain comprised of a three phase system (solidmore » platinum, liquid argon and vapor argon) on which equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. After equilibrium of the three-phase system was established, the wall was set to different temperatures (130 K and 250 K for the case of evaporation and explosive boiling respectively) to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat flux normal to the solid surface was also calculated to illustrate the effectiveness of heat transfer for hydrophilic and hydrophobic surfaces in cases of both nanostructured surface and flat surface. The results obtained show that both the wetting condition of the surface and the presence of internal recesses have significant effect on normal evaporation and explosive boiling of the thin liquid film. The heat transfer from solid to liquid in cases of surface with recesses are higher compared to flat surface without recesses. Also the surface with higher wettability (hydrophilic) provides more favorable conditions for boiling than the low-wetting surface (hydrophobic) and therefore, liquid argon responds quickly and shifts from liquid to vapor phase faster in case of hydrophilic surface. The heat transfer rate is also much higher in case of hydrophilic surface.« less

Constraining magma physical properties and its temporal evolution from InSAR and topographic data only: a physics-based eruption model for the effusive phase of the Cordon Caulle 2011-2012 rhyodacitic eruption

NASA Astrophysics Data System (ADS)

Delgado, F.; Kubanek, J.; Anderson, K. R.; Lundgren, P.; Pritchard, M. E.

2017-12-01

The 2011-2012 eruption of Cordón Caulle volcano in Chile is the best scientifically observed rhyodacitic eruption and is thus a key place to understand the dynamics of these rare but powerful explosive rhyodacitic eruptions. Because the volatile phase controls both the eruption temporal evolution and the eruptive style, either explosive or effusive, it is important to constrain the physical parameters that drive these eruptions. The eruption began explosively and after two weeks evolved into a hybrid explosive - lava flow effusion whose volume-time evolution we constrain with a series of TanDEM-X Digital Elevation Models. Our data shows the intrusion of a large volume laccolith or cryptodome during the first 2.5 months of the eruption and lava flow effusion only afterwards, with a total volume of 1.4 km3. InSAR data from the ENVISAT and TerraSAR-X missions shows more than 2 m of subsidence during the effusive eruption phase produced by deflation of a finite spheroidal source at a depth of 5 km. In order to constrain the magma total H2O content, crystal cargo, and reservoir pressure drop we numerically solve the coupled set of equations of a pressurized magma reservoir, magma conduit flow and time dependent density, volatile exsolution and viscosity that we use to invert the InSAR and topographic data time series. We compare the best-fit model parameters with independent estimates of magma viscosity and total gas content measured from lava samples. Preliminary modeling shows that although it is not possible to model both the InSAR and the topographic data during the onset of the laccolith emplacement, it is possible to constrain the magma H2O and crystal content, to 4% wt and 30% which agree well with published literature values.

Relative surface wave amplitude and phase anomalies from the Democratic People's Republic of Korea announced nuclear tests

DOE PAGES

Ichinose, G. A.; Myers, S. C.; Ford, S. R.; ...

2017-08-29

Here, we performed relative locations of six event pairs based on surface wave (SW) and body wave (BW) differential traveltimes of the 9 September 2016, 6 January 2016, 12 February 2013, and 25 May 2009 announced North Korea nuclear explosions. The SW relative locations for the 25 May 2009 and 12 February 2013 events were inconsistent with the BWs when paired with other events, and only the 6 January 2016/9 September 2016 pair was consistent. Apparent SW phase shift is investigated with respect to the BW relative locations. The pairs formed with the 25 May 2009 and 12 February 2013more » events, beneath the southeast slope of Mount Mant'ap, have the largest phase shifts and amplitude ratio deviations, whereas the least deviation was from the 6 January 2016 and 9 September 2016 event pair beneath the mountain peak. Regional moment tensors (MTs) predict the amplitude ratios but do not resolve the relative phase. We find that MTs with 10% difference in isotropic and rotated +CLVD can fit both relative phase and amplitude ratios. SW relative locations of highly isotropic and correlated explosion clusters can be affected by topography and small differences in MT.« less

Computer simulation of the last support phase of the long jump.

PubMed

Chow, John W; Hay, James G

2005-01-01

The purpose was to examine the interacting roles played by the approach velocity, the explosive strength (represented by vertical ground reaction force [VGRF]), and the change in angular momentum about a transverse axis through the jumper's center of mass (deltaHzz) during the last support phase of the long jump, using a computer simulation technique. A two-dimensional inverted-pendulum-plus-foot segment model was developed to simulate the last support phase. Using a reference jump derived from a jump performance reported in the literature, the effects of varying individual parameters were studied using sensitivity analyses. In each sensitivity analysis, the kinematic characteristics of the longest jumps with the deltaHzz considered and not considered when the parameter of interest was altered were noted. A sensitivity analysis examining the influence of altering both approach velocity and VGRF at the same time was also conducted. The major findings were that 1) the jump distance was more sensitive to changes in approach velocity (e.g., a 10% increase yielded a 10.0% increase in jump distance) than to changes in the VGRF (e.g., a 10% increase yielded a 7.2% increase in jump distance); 2) the relatively large change in jump distance when both the approach velocity and VGRF were altered (e.g., a 10% increase in both parameters yielded a 20.4% increase in jump distance), suggesting that these two parameters are not independent factors in determining the jump distance; and 3) the jump distance was overestimated if the deltaHzz was not considered in the analysis.

27 CFR 555.126 - Explosives transaction record for distribution of explosive materials prior to May 24, 2003 and...

Code of Federal Regulations, 2011 CFR

2011-04-01

.... Where there is a change in proprietorship, or in the individual, firm, corporate name or trade name, the... verify the identity of the of the holder of the limited permit by examining an identification document...

27 CFR 555.126 - Explosives transaction record for distribution of explosive materials prior to May 24, 2003 and...

Code of Federal Regulations, 2012 CFR

2012-04-01

.... Where there is a change in proprietorship, or in the individual, firm, corporate name or trade name, the... verify the identity of the of the holder of the limited permit by examining an identification document...

27 CFR 555.126 - Explosives transaction record for distribution of explosive materials prior to May 24, 2003 and...

Code of Federal Regulations, 2013 CFR

2013-04-01

.... Where there is a change in proprietorship, or in the individual, firm, corporate name or trade name, the... verify the identity of the of the holder of the limited permit by examining an identification document...

27 CFR 555.126 - Explosives transaction record for distribution of explosive materials prior to May 24, 2003 and...

Code of Federal Regulations, 2014 CFR

2014-04-01

.... Where there is a change in proprietorship, or in the individual, firm, corporate name or trade name, the... verify the identity of the of the holder of the limited permit by examining an identification document...

27 CFR 555.126 - Explosives transaction record for distribution of explosive materials prior to May 24, 2003 and...

Code of Federal Regulations, 2010 CFR

2010-04-01

.... Where there is a change in proprietorship, or in the individual, firm, corporate name or trade name, the... verify the identity of the of the holder of the limited permit by examining an identification document...

Explosive genetic evidence for explosive human population growth

PubMed Central

Gao, Feng; Keinan, Alon

2016-01-01

The advent of next-generation sequencing technology has allowed the collection of vast amounts of genetic variation data. A recurring discovery from studying larger and larger samples of individuals had been the extreme, previously unexpected, excess of very rare genetic variants, which has been shown to be mostly due to the recent explosive growth of human populations. Here, we review recent literature that inferred recent changes in population size in different human populations and with different methodologies, with many pointing to recent explosive growth, especially in European populations for which more data has been available. We also review the state-of-the-art methods and software for the inference of historical population size changes that lead to these discoveries. Finally, we discuss the implications of recent population growth on personalized genomics, on purifying selection in the non-equilibrium state it entails and, as a consequence, on the genetic architecture underlying complex disease and the performance of mapping methods in discovering rare variants that contribute to complex disease risk. PMID:27710906

Infrasonic Observations of Explosions and Degassing at Kilauea Summit

NASA Astrophysics Data System (ADS)

Fee, D.; Garces, M.

2008-12-01

After 25 years of quiescence, eruptive activity returned to Kilauea Caldera with an explosion in Halema'uma'u crater on March 19th 2008. The explosion is presumed to be the clearing of a clogged vent. Along with the 3/19 explosion, at least 5 more gas-driven explosions have occurred and were clearly recorded at a 4-element infrasound array 7 km away. Acoustic energy estimates for these explosions yield energies between ~ 0.2-3 × 107 J. Infrasonic VLP energy is present for some of the explosions, but not all. The relatively long explosion durations (>20 seconds) and frequency content are consistent with a transient pressure pulse followed by the reverberation of a shallow gas chamber or conduit. Persistent degassing from Halema'uma'u followed the initial explosion. The harmonic infrasonic tremor produced by the degassing is the most energetic to date at Kilauea, with the cumulative tremor acoustic energy at ~107-108 Joules/hour. The complex tremor spectra show numerous peaks, with the dominant peak between 0.3-0.6 Hz and a smaller amplitude peak around 1-3 Hz. The peak frequency of the harmonic tremor has changed over time, which could be related to a change in the gas-filled chamber dimensions or temperature. Further analysis of the tremor spectra may help constrain dimensions. Consistent with our previous observations at Kilauea from Pu'u 'O'o, Fissure D, and lava skylights, the excitation of a gas within a confined volume appears to be the acoustic (and possibly seismic) source. For the tremor, we propose a mechanism where persistent degassing excites the gas volume into resonance. The explosions signals are consistent with a slug of gas reaching the free surface and exciting the conduit as well. Correlation of the infrasound signals with seismic tremor, LP and VLP signals suggest an open system connecting the atmosphere to the seismic excitation process at depth. Results will also be presented in relation to the recent observation of a visible lava lake within the conduit.

Study of Vapour Cloud Explosion Impact from Pressure Changes in the Liquefied Petroleum Gas Sphere Tank Storage Leakage

NASA Astrophysics Data System (ADS)

Rashid, Z. A.; Suhaimi Yeong, A. F. Mohd; Alias, A. B.; Ahmad, M. A.; AbdulBari Ali, S.

2018-05-01

This research was carried out to determine the risk impact of Liquefied Petroleum Gas (LPG) storage facilities, especially in the event of LPG tank explosion. In order to prevent the LPG tank explosion from occurring, it is important to decide the most suitable operating condition for the LPG tank itself, as the explosion of LPG tank could affect and cause extensive damage to the surrounding. The explosion of LPG tank usually occurs due to the rise of pressure in the tank. Thus, in this research, a method called Planas-Cuchi was applied to determine the Peak Side-On Overpressure (Po) of the LPG tank during the occurrence of explosion. Thermodynamic properties of saturated propane, (C3H8) have been chosen as a reference and basis of calculation to determine the parameters such as Explosion Energy (E), Equivalent Mass of TNT (WTNT), and Scaled Overpressure (PS ). A cylindrical LPG tank in Feyzin Refinery, France was selected as a case study in this research and at the end of this research, the most suitable operating pressure of the LPG tank was determined.

Influences of solution chemical conditions on mobilization of TNT from contaminated soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dante, D.A.; Tiller, C.L.; Pennell, K.D.

1996-12-31

Residual explosives and their byproducts are common contaminants at several US military installations. One of the major explosive contaminants is 2,4,6-Trinitrotoluene (TNT) (a hydrophobic organic compound). Contamination from TNT has resulted from manufacturing and handling processes which occurred at military installations, especially Army Ammunition Plants (AAP), over many decades until environmental regulations were implemented. TNT causes adverse effects to the environment, including growth inhibition to plants, toxicity to aquatic life, and possible mutagenicity, and also is toxic to humans. As a result of the effects of TNT on the environment and current environmental regulations, substantial research effort has been focusedmore » on determining the fate of TNT in natural systems and the development of remediation processes. Many potential remediation processes, such as those involving plants or microorganisms, are in part limited by the transfer of TNT from solid phases (e.g., sorbed to soil or present as TNT granules) to the aqueous phase. The purpose of this research is to assess the release of TNT from a soil phase to a mobile aqueous phase under varying solution chemical conditions. In particular, influences of pH, aquatic natural organic matter, and surfactants are investigated.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ichinose, G. A.; Myers, S. C.; Ford, S. R.

Here, we performed relative locations of six event pairs based on surface wave (SW) and body wave (BW) differential traveltimes of the 9 September 2016, 6 January 2016, 12 February 2013, and 25 May 2009 announced North Korea nuclear explosions. The SW relative locations for the 25 May 2009 and 12 February 2013 events were inconsistent with the BWs when paired with other events, and only the 6 January 2016/9 September 2016 pair was consistent. Apparent SW phase shift is investigated with respect to the BW relative locations. The pairs formed with the 25 May 2009 and 12 February 2013more » events, beneath the southeast slope of Mount Mant'ap, have the largest phase shifts and amplitude ratio deviations, whereas the least deviation was from the 6 January 2016 and 9 September 2016 event pair beneath the mountain peak. Regional moment tensors (MTs) predict the amplitude ratios but do not resolve the relative phase. We find that MTs with 10% difference in isotropic and rotated +CLVD can fit both relative phase and amplitude ratios. SW relative locations of highly isotropic and correlated explosion clusters can be affected by topography and small differences in MT.« less

4D Imaging in Thermally Damaged Polymer-bonded Explosives

NASA Astrophysics Data System (ADS)

Parker, Gary; Bourne, Neil; Eastwood, David; Jacques, Simon; Dickson, Peter; Lopez-Pulliam, Ian; Heatwole, Eric; Holmes, Matt; Smilowitz, Laura; Rau, Christoph

2017-06-01

PBXs are composites in which explosive crystallites are bound by compliant polymers. There are safety benefits derived from compliant binders; e.g. they mitigate some effects of mechanical insult. However, during elevated thermal insult, degradation of binder and HE crystallites can modify the morphology in ways that can reduce safety margins by increasing post-ignition reaction violence. The response of thermally damaged PBXs, before and following self-ignition has safety implications and it is desirable to understand the fundamental physics controlling the rate of pre-ignition thermal runaway and the post-ignition flame propagation in thermal accident scenarios. Coupled with this there is an ongoing effort to make in situ, time-resolved, measurements of the size, nature and extent of micro-porosity in PBX 9501 during thermal decomposition. We report on PBX heating experiments conducted at the Diamond synchrotron with both PBX 9501 and an inert mock. During heating, CT radiography was conducted in order to observe void production and interconnectivity of gas flow pathways, as well as to monitor phase changes within the crystals. We explore the variation of behavior as a function of heating rate, soak temperature, soak time and confinement.

Phreatomagmatic eruptions through unconsolidated coastal plain sequences, Maungataketake, Auckland Volcanic Field (New Zealand)

NASA Astrophysics Data System (ADS)

Agustín-Flores, Javier; Németh, Károly; Cronin, Shane J.; Lindsay, Jan M.; Kereszturi, Gábor; Brand, Brittany D.; Smith, Ian E. M.

2014-04-01

Maungataketake is a monogenetic basaltic volcano formed at ~ 85-89 ka in the southern part of the Auckland Volcanic Field (AVF), New Zealand. It comprises a basal 1100-m diameter tuff ring, with a central scoria/spatter cone and lava flows. The tuff ring was formed under hydrogeological and geographic conditions very similar to the present. The tuff records numerous density stratified, wet base surges that radiated outward up to 1 km, decelerating rapidly and becoming less turbulent with distance. The pyroclastic units dominantly comprise fine-grained expelled grains from various sedimentary deposits beneath the volcano mixed with a minor component of juvenile pyroclasts (~ 35 vol.%). Subtle lateral changes relate to deceleration with distance and vertical transformations are minor, pointing to stable explosion depths and conditions, with gradual transitions between units and no evidence for eruptive pauses. This volcano formed within and on ~ 60 m-thick Plio/Pleistocene, poorly consolidated, highly permeable shelly sands and silts (Kaawa Formation) capped by near-impermeable, water-saturated muds (Tauranga Group). These sediments rest on moderately consolidated Miocene-aged permeable turbiditic sandstones and siltstones (Waitemata Group). Magma-water fuelled thermohydraulic explosions remained in the shallow sedimentary layers, excavating fine-grained sediments without brittle fragmentation required. On the whole, the resulting cool, wet pyroclastic density currents were of low energy. The unconsolidated shallow sediments deformed to accommodate rapidly rising magma, leading to development of complex sill-like bodies and a range of magma-water contact conditions at any time. The weak saturated sediments were also readily liquefied to provide an enduring supply of water and fine sediment to the explosion loci. Changes in magma flux and/or subsequent stabilisation of the conduit area by a lava ring-barrier led to ensuing Strombolian and fire-fountaining eruption phases. Future eruptions in littoral environments around Auckland are likely to be of this type, producing base surges that rapidly decrease in energy over short runout distances (~ 1 km).

Hospital Affiliations with HMOs and PPOs: An Analysis of Organizational and Market Factors Influencing Engagement In Resource Exchange Relationships

DTIC Science & Technology

1994-01-01

hospitals since at least 1965, subsequently changing the rules of economic engagement across the nation beginnin- � with PPS. The explosion of 63...exchange relationships obviously matches the explosive growth in membership in both HMOs and PPOs during the early to mid 1980s, especially for the...of affiliations, while explosive in the early 1980s, reached a plateau by the late 130 1980s. While hospital linkages increased tremendously between

Changes in long-term eruption dynamics at Santiaguito, Guatemala: Observations from seismic data

NASA Astrophysics Data System (ADS)

Lamb, O. D.; Lavallée, Y.; De Angelis, S.; Lamur, A.; Hornby, A. J.; von Aulock, F. W.; Kendrick, J. E.; Chigna, G.; Rietbrock, A.

2016-12-01

Santiaguito (Guatemala) is an ideal laboratory for the study of the eruption dynamics of long-lived silicic eruptions. Here we present seismic observations of ash-and-gas explosions recorded between November 2014 and June 2016 during a multi-disciplinary experiment by the University of Liverpool. The instruments, deployed around the active dome complex between 0.5 to 7 km from the vent, included 5 broadband and 6 short-period seismometers, as well as 5 infrasound sensors. The geophysical data is complemented by thermal images, optical images from a UAV, and geochemical measurements of erupted material. Regular, small-to-moderate sized explosions from the El Caliente dome at Santiaguito have been common since at least the early 1970s. However, in 2015, a shift in character took place in terms of the regularity and magnitude of the explosions. Explosions became larger and less regular, and often accompanied by pyroclastic density currents. The larger explosions have caused a major morphological change at the vent, as a rubble-filled vent was replaced by a crater of 150 m depth. This shift in behaviour likely represents a change in the eruptive mechanism in the upper conduit beneath the Caliente vent, possibly triggered by processes at a greater depth in the volcanic system. This experiment represents a unique opportunity to use multi-disciplinary research to help understand the long-term eruptive dynamics of lava dome eruptions. Our observations may have implications for hazard assessment not only at Santiaguito, but at many other volcanic systems worldwide.

Multispectral Observations of Explosive Gas Emissions from Santiaguito, Guatemala

NASA Astrophysics Data System (ADS)

Carn, S. A.; Watson, M.; Thomas, H.; Rodriguez, L. A.; Campion, R.; Prata, F. J.

2016-12-01

Santiaguito volcano, Guatemala, has been persistently active for decades, producing frequent explosions from its actively growing lava dome. Repeated release of volcanic gases contains information about conduit processes during the cyclical explosions at Santiaguito, but the composition of the gas phase and the amount of volatiles released in each explosion remains poorly constrained. In addition to its persistent activity, Santiaguito offers an exceptional opportunity to investigate lava dome degassing processes since the upper surface of the active lava dome can be viewed from the summit of neighboring Santa Maria. In January 2016 we conducted multi-spectral observations of Santiaguito's explosive eruption plumes and passive degassing from multiple perspectives as part of the first NSF-sponsored `Workshop on Volcanoes' instrument deployment. Gas measurements included open-path Fourier-Transform infrared (OP-FTIR) spectroscopy from the Santa Maria summit, coincident with ultraviolet (UV) and infrared (IR) camera and UV Differential Optical Absorption Spectroscopy (DOAS) from the El Mirador site below Santiaguito's active Caliente lava dome. Using the OP-FTIR in passive mode with the Caliente lava dome as the source of IR radiation, we were able to collect IR spectra at high temporal resolution prior to and during two explosions of Santiaguito on 7-8 January, with volcanic SO2 and H2O emissions detected. UV and IR camera data provide constraints on the total SO2 burden in the emissions (and potentially the volcanic ash burden), which coupled with the FTIR gas ratios provides new constraints on the mass and composition of volatiles driving explosions at Santiaguito. All gas measurements indicate significant volatile release during explosions with limited degassing during repose periods. In this presentation we will present ongoing analysis of the unique Santiaguito gas dataset including estimation of the total volatile mass released in explosions and an intercomparison of SO2 amounts recorded by the UV and IR instruments.

Los Alamos Explosives Performance Key to Stockpile Stewardship

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dattelbaum, Dana

2014-11-03

As the U.S. Nuclear Deterrent ages, one essential factor in making sure that the weapons will continue to perform as designed is understanding the fundamental properties of the high explosives that are part of a nuclear weapons system. As nuclear weapons go through life extension programs, some changes may be advantageous, particularly through the addition of what are known as "insensitive" high explosives that are much less likely to accidentally detonate than the already very safe "conventional" high explosives that are used in most weapons. At Los Alamos National Laboratory explosives research includes a wide variety of both large- andmore » small-scale experiments that include small contained detonations, gas and powder gun firings, larger outdoor detonations, large-scale hydrodynamic tests, and at the Nevada Nuclear Security Site, underground sub-critical experiments.« less

Near-Source Mechanism for Creating Shear Content from Buried Explosions

NASA Astrophysics Data System (ADS)

Steedman, D. W.; Bradley, C. R.

2017-12-01

The Source Physics Experiment (SPE) has the goal of developing a greater understanding of explosion phenomenology at various spatial scales, from near-source to the far-field. SPE Phase I accomplished a series of six chemical explosive tests of varying scaled depth of burial within a borehole in granite. The testbed included an extensive array of triaxial accelerometers. Velocity traces derived from these accelerometers allow for detailed study of the shock environment close in to the explosion. A specific goal of SPE is to identify various mechanisms for generating shear within the propagation environment and how this might be informative on the identification of explosive events that otherwise fail historic compression wave energy/shear wave energy (P/S) event discrimination. One of these sources was hypothesized to derive from slippage along joint sets near to the source. Velocity traces from SPE Phase I events indicate that motion tangential to a theoretically spherical shock wave are initially quiescent after shock arrival. But this period of quiescence is followed by a sudden increase in amplitude that consistently occurs just after the peak of the radial velocity (i.e., onset of shock unloading). The likelihood of occurrence of this response is related to yield-scaled depth-of-burial (SDOB). We describe a mechanism where unloading facilitates dilation of closed joints accompanied by a release of shear energy stored during compression. However, occurrence of this mechanism relies on relative amplitudes between the shock loading caused at a point and the in situ stress: at too large a SDOB the stored energy is insufficient to overcome the combination of the overburden stress and traction on the joint. On the other hand, too small of a SDOB provides that the in situ stress is insufficient to keep joints from storing stress, thus overriding the release mechanism and mitigating rupture-like slippage. We develop a notional relationship between SPE Phase I SDOB and the likelihood of shear release. We then compare this to the six recorded DPRK events in terms of where these events fall in relation to the accepted mb:MS discriminant using estimated SDOB values for those events. To first order SPE SDOBs resulting in shear release appear to map to estimated DPRK SDOBs which display excessive shear magnitude. LA-UR-17-29528.

Thermal reactive hazards of HMX with contaminants.

PubMed

Peng, Deng-Jr; Chang, Cheng-Ming; Chiu, Miin

2004-10-18

In the past, many unexpected runaway accidents occurred in manufacturing processes, involving volatile chemical and explosive storage and transportation. Incompatible product reactions of high explosives must be carefully considered using loss prevention strategies for thermal hazards risk analysis. High explosive reactions vary via environmental changes, contact materials, or process situations, such as onset temperature and shifts in reaction type when high explosives are in contact with contaminants. Therefore, the manufacture and handling of high explosives require the utmost in safety and loss prevention. HMX (cyclotetramethyene tetranitramine) is one kind of high explosive widely used around the world which is stable with high detonation strength properties. In this study, the influences of contaminants on HMX are investigated. The studied contaminants include ferrous chloride tetrahydrate, ferric chloride hexahydrate, acetone solution, acetic acid, and nitric acid. DSC thermal curves and incompatible reaction kinetic evaluations were preformed using iron, chlorine and acid. Organic acetone solution has lesser effects on HMX. Hopefully, this study will lead to improved thermal hazards risk analysis and reduce accidents.

Anatomy of a diffracting detonation in a circular arc of explosive

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bdzil, John Bohdan

Using high-resolution numerical simulation, study diffraction of a detonation as it traverses a 270° finite-thickness condensed-phase explosive arc. This geometry admits a steady solution in a frame rotating with angular speed ω 0, which thereby facilitates a detailed analysis of how the loss of energy from the detonation reaction zone due to the diffraction process slows the propagation of the detonation. There exists a region of subsonic flow, between the detonation shock and the curve of sonic flow (labelled the DDZ), which is responsible for setting ω 0. Although the DDZ spans the entire thickness for thin arcs, it ismore » localized to a region near the inside surface as the arc is thickened. Furthermore the explosive energy release near this inside surface plays a disproportionate role in the diffraction process.« less

A test of the comet hypothesis of the Tunguska Meteor Fall - Nature of the meteor 'thermal' explosion paradox

NASA Technical Reports Server (NTRS)

Liu, V. C.

1978-01-01

The hypothesis that a comet was responsible for the Tunguska Meteor Fall is rejected because the hypothesis does not seem to account for the intense terminal spherical shock. A porous meteoroid model is proposed, and an analysis indicates that an entity of this type might produce an aerodynamic heat flux large enough to account for the terminal meteor explosion. It is suggested that the presence of olivine and of highly irregular macrostructure in meteors might indicate the presence of some porosity. For a highly porous meteoroid, it is postulated that during entry into the atmosphere the aerodynamic heat transfer at its external or pore walls would become so intensified as to cause either complete ablation with popping or a solid-liquid-vapor phase transition accompanied by an explosion.

Probing Dynamic Processes in Explosives and Propellants - Science Issues

NASA Astrophysics Data System (ADS)

Moore, David

2017-06-01

Recent experiments on advanced light sources have started to unravel some of the micromechanical behavior of single crystal energetic materials, including void collapse under shock loading and inter-granular failure. These examples just scratch the surface of many extant explosives science issues, which could be elucidated with advanced XFEL-type resources. These include such diverse questions as: How do powders actually compact and what are the spatially and temporally resolved temperature and flow fields generated (especially two-phase flows)? Are there polymorphic effects (if so, how are they spatially distributed)? What are the strain fields during compaction? What happens near surfaces, especially for composite explosives? How is mechanics coupled to chemistry? What are hot spots really? I will provide some history behind these and other questions and point towards how future experiments might be designed to provide some answers.

On-site comprehensive analysis of explosives using HPLC-UV-PAED

NASA Astrophysics Data System (ADS)

Marple, Ronita L.; LaCourse, William R.

2004-03-01

High-performance liquid chromatography with ultra violet and photo-assisted electrochemical detection (HPLC-UV-PAED) has been developed for the sensitive and selective detection of explosives in ground water and soil extracts. Fractionation and preconcentration of explosives is accomplished with on-line solid phase extraction (SPE), which minimizes sample pretreatment and enables faster and more accurate on-site assessment of a contaminated site. Detection limits are equivalent or superior (i.e., <1 part-per-trillion for HMX) to those achieved using the Environmental Protection Agency (EPA) Method 8330. This approach is more broadly applicable, as it is capable of determining a wider range of organic nitro compounds. Soil samples are extracted using pressurized fluid extraction (PFE), and this technique is automatable, field-compatible, and environmentally friendly, adding to the overall efficiency of the methodology.

Anatomy of a diffracting detonation in a circular arc of explosive

DOE PAGES

Bdzil, John Bohdan

2018-02-08

Using high-resolution numerical simulation, study diffraction of a detonation as it traverses a 270° finite-thickness condensed-phase explosive arc. This geometry admits a steady solution in a frame rotating with angular speed ω 0, which thereby facilitates a detailed analysis of how the loss of energy from the detonation reaction zone due to the diffraction process slows the propagation of the detonation. There exists a region of subsonic flow, between the detonation shock and the curve of sonic flow (labelled the DDZ), which is responsible for setting ω 0. Although the DDZ spans the entire thickness for thin arcs, it ismore » localized to a region near the inside surface as the arc is thickened. Furthermore the explosive energy release near this inside surface plays a disproportionate role in the diffraction process.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cavanaugh, J.E.; McQuarrie, A.D.; Shumway, R.H.

Conventional methods for discriminating between earthquakes and explosions at regional distances have concentrated on extracting specific features such as amplitude and spectral ratios from the waveforms of the P and S phases. We consider here an optimum nonparametric classification procedure derived from the classical approach to discriminating between two Gaussian processes with unequal spectra. Two robust variations based on the minimum discrimination information statistic and Renyi's entropy are also considered. We compare the optimum classification procedure with various amplitude and spectral ratio discriminants and show that its performance is superior when applied to a small population of 8 land-based earthquakesmore » and 8 mining explosions recorded in Scandinavia. Several parametric characterizations of the notion of complexity based on modeling earthquakes and explosions as autoregressive or modulated autoregressive processes are also proposed and their performance compared with the nonparametric and feature extraction approaches.« less

Source and path effects in the wave fields of tremor and explosions at Stromboli Volcano, Italy

USGS Publications Warehouse

Chouet, B.; Saccorotti, G.; Martini, M.; Dawson, P.; De Luca, G.; Milana, G.; Scarpa, R.

1997-01-01

The wave fields generated by Strombolian activity are investigated using data from small-aperture seismic arrays deployed on the north flank of Stromboli and data from seismic and pressure transducers set up near the summit crater. Measurements of slowness and azimuth as a function of time clearly indicate that the sources of tremor and explosions are located beneath the summit crater at depths shallower than 200 m with occasional bursts of energy originating from sources extending to a depth of 3 km. Slowness, azimuth, and particle motion measurements reveal a complex composition of body and surface waves associated with topography, structure, and source properties. Body waves originating at depths shallower than 200 m dominate the wave field at frequencies of 0.5-2.5 Hz, and surface waves generated by the surficial part of the source and by scattering sources distributed around the island dominate at frequencies above 2.5 Hz. The records of tremor and explosions are both dominated by SH motion. Far-field records from explosions start with radial motion, and near-field records from those events show dominantly horizontal motion and often start with a low-frequency (1-2 Hz) precursor characterized by elliptical particle motion, followed within a few seconds by a high-frequency radial phase (1-10 Hz) accompanying the eruption of pyroclastics. The dominant component of the near- and far-field particle motions from explosions, and the timing of air and body wave phases observed in the near field, are consistent with a gaspiston mechanism operating on a shallow (<200 m deep), vertical crack-like conduit. Models of a degassing fluid column suggest that noise emissions originating in the collective oscillations of bubbles ascending in the magma conduit may provide an adequate self-excitation mechanism for sustained tremor generation at Stromboli. Copyright 1997 by the American Geophysical Union.

Large-N Over the Source Physics Experiment (SPE) Phase I and Phase II Test Beds

NASA Astrophysics Data System (ADS)

Snelson, C. M.; Carmichael, J. D.; Mellors, R. J.; Abbott, R. E.

2014-12-01

One of the current challenges in the field of monitoring and verification is source discrimination of low-yield nuclear explosions from background seismicity, both natural and anthropogenic. Work is underway at the Nevada National Security Site to conduct a series of chemical explosion experiments using a multi-institutional, multi-disciplinary approach. The goal of this series of experiments, called the Source Physics Experiments (SPE), is to refine the understanding of the effect of earth structures on source phenomenology and energy partitioning in the source region, the transition of seismic energy from the near field to the far field, and the development of S waves observed in the far field. To fully explore these problems, the SPE series includes tests in both hard and soft rock geologic environments. The project comprises a number of activities, which range from characterizing the shallow subsurface to acquiring new explosion data from both the near field (<100 m) and the far field (>100 m). SPE includes a series of planned explosions (with different yields and depths of burials), which are conducted in the same hole and monitored by a diverse set of sensors recording characteristics of the explosions, ground-shock, seismo-acoustic energy propagation. This presentation focuses on imaging the full 3D wavefield over hard rock and soft rock test beds using a large number of seismic sensors. This overview presents statistical analyses of optimal sensor layout required to estimate wavefield discriminants and the planned deployment for the upcoming experiments. This work was conducted under Contract No. DE-AC52-06NA25946 with the U.S. Department of Energy. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

The Plumbing System of a Highly Explosive Basaltic Volcano: Sunset Crater, AZ

NASA Astrophysics Data System (ADS)

Allison, C. M.; Roggensack, K.; Clarke, A. B.

2015-12-01

We seek to better understand highly explosive basaltic eruptions with specific focus on magmatic volatile solubility in alkali basalts and the magma plumbing system. Sunset Crater, an alkali basalt (~3.7 wt.% alkalis) scoria cone volcano, erupted explosively in 1085 AD. We analyzed 125 primary melt inclusions (MIs) from Sunset Crater tephra deposited by 2 subplinian phases and 1 Strombolian explosion to compare magma volatiles and storage conditions. We picked rapidly quenched free olivine crystals and selected large volume MIs (50-180 μm) located toward crystal cores. MIs are faceted and exhibit little major element composition variability with minor post entrapment crystallization (2-10%). MIs are relatively dry but CO2-rich. Water content varies from 0.4 wt.% to 1.5 wt.% while carbon dioxide abundance ranges between 1,150 ppm and 3,250 ppm. Most MIs contain >1 wt.% H2O and >2,150 ppm CO2. All observed MIs contain a vapor bubble, so we are evaluating MI vapor bubbles with Raman spectroscopy and re-homogenization experiments to determine the full volatile budget. Because knowledge of volatile solubility is critical to accurately interpret results from MI analyses, we measured H2O-CO2 solubility in the Sunset Crater bulk composition. Fluid-saturated experiments at 4 and 6 kbar indicate shallower entrapment pressures for these MIs than values calculated for this composition using existing models. Assuming fluid saturation, MIs record depths from 6 km to 14 km, including groupings suggesting two pauses for longer-term storage at ~6 km and ~10.5 km. We do not observe any significant differences in MIs from phases exhibiting different eruptive styles, suggesting that while a high CO2 content may drive rapid magma ascent and be partly responsible for highly explosive eruptions, shallower processes may govern the final eruptive character. To track shallow processes during magma ascent from depth of MI-entrapment up to the surface, we are examining MI re-entrants.

Volcanic stratigraphy of large-volume silicic pyroclastic eruptions during Oligocene Afro-Arabian flood volcanism in Yemen

NASA Astrophysics Data System (ADS)

Peate, Ingrid Ukstins; Baker, Joel A.; Al-Kadasi, Mohamed; Al-Subbary, Abdulkarim; Knight, Kim B.; Riisager, Peter; Thirlwall, Matthew F.; Peate, David W.; Renne, Paul R.; Menzies, Martin A.

2005-12-01

A new stratigraphy for bimodal Oligocene flood volcanism that forms the volcanic plateau of northern Yemen is presented based on detailed field observations, petrography and geochemical correlations. The >1 km thick volcanic pile is divided into three phases of volcanism: a main basaltic stage (31 to 29.7 Ma), a main silicic stage (29.7 to 29.5 Ma), and a stage of upper bimodal volcanism (29.5 to 27.7 Ma). Eight large-volume silicic pyroclastic eruptive units are traceable throughout northern Yemen, and some units can be correlated with silicic eruptive units in the Ethiopian Traps and to tephra layers in the Indian Ocean. The silicic units comprise pyroclastic density current and fall deposits and a caldera-collapse breccia, and they display textures that unequivocally identify them as primary pyroclastic deposits: basal vitrophyres, eutaxitic fabrics, glass shards, vitroclastic ash matrices and accretionary lapilli. Individual pyroclastic eruptions have preserved on-land volumes of up to ˜850 km3. The largest units have associated co-ignimbrite plume ash fall deposits with dispersal areas >1×107 km2 and estimated maximum total volumes of up to 5,000 km3, which provide accurate and precisely dated marker horizons that can be used to link litho-, bio- and magnetostratigraphy studies. There is a marked change in eruption style of silicic units with time, from initial large-volume explosive pyroclastic eruptions producing ignimbrites and near-globally distributed tuffs, to smaller volume (<50 km3) mixed effusive-explosive eruptions emplacing silicic lavas intercalated with tuffs and ignimbrites. Although eruption volumes decrease by an order of magnitude from the first stage to the last, eruption intervals within each phase remain broadly similar. These changes may reflect the initiation of continental rifting and the transition from pre-break-up thick, stable crust supporting large-volume magma chambers, to syn-rift actively thinning crust hosting small-volume magma chambers.

Finite Element Analysis Of Structural And Magmatic Interactions At Mono Basin (California)

NASA Astrophysics Data System (ADS)

La Marra, D.; Manconi, A.; Battaglia, M.

2010-12-01

Mono Basin is a northward trending graben situated east of the Sierra Nevada and west of Cowtrack Mountains, extending from the northern edge of Long Valley Caldera towards the Bodie Hills. From a hydrographic perspective, the Mono Basin is defined by all streams that drain into Mono Lake. The Mono-Inyo Craters forms a prominent 25-km-long volcanic complex from the NW corner of Long Valley caldera to the southern edge of Mono Lake. The late Quaternary Hartley Springs fault occurs along the Sierran range front between June Lake and the northern border of Long Valley Caldera. Recently it has been proposed that the manifestation of the volcanic and of the tectonic activity in this area is likely interrelated. According to Bursik et al (2003), stratigraphic data suggest that during the North Mono-Inyo eruption sequence of ~1350 A.D., a series of strong earthquakes occurred across the end of the North Mono explosive phase and the beginning of the Inyo explosive phase. Moreover, geological and geomorphic features of the Hartley Springs fault are consistent with rupture of the fault during the eruption sequence. We use the Finite Element Method (FEM) to simulate a three-dimensional model and investigate the feedback mechanism between dike intrusion and slip along the Hartley Springs fault. We first validate our numerical model against the Okada (1985) analytical solution for a homogeneous and elastic flat half-space. Subsequently, we evaluate the distribution of local stress changes to study the influence of the Inyo Dike intrusion in ~1350 A.D. on Hartley Springs fault, and how the fault slip may encourage the propagation of dikes towards the surface. To this end, we considered the standard Coulomb stress change as failure criterion. Finally, we analyze the effects of the topography and of vertical and lateral heterogeneities of the crust on the distribution of local and regional stress changes. In this presentation, we highlight the preliminary results of our analysis and discuss the possible future developments of this study.

Effects of Initial Particle Distribution on an Energetic Dispersal of Particles

NASA Astrophysics Data System (ADS)

Rollin, Bertrand; Ouellet, Frederick; Koneru, Rahul; Garno, Joshua; Durant, Bradford

2017-11-01

Accurate predictions of the late time solid particle cloud distribution ensuing an explosive dispersal of particles is an extremely challenging problem for compressible multiphase flow simulations. The source of this difficulty is twofold: (i) The complex sequence of events taking place. Indeed, as the blast wave crosses the surrounding layer of particles, compaction occurs shortly before particles disperse radially at high speed. Then, during the dispersion phase, complex multiphase interactions occurs between particles and detonation products. (ii) Precise characterization of the explosive and particle distribution is virtually impossible. In this numerical experiment, we focus on the sensitivity of late time particle cloud distributions relative to carefully designed initial distributions, assuming the explosive is well described. Using point particle simulations, we study the case of a bed of glass particles surrounding an explosive. Constraining our simulations to relatively low initial volume fractions to prevent reaching of the close packing limit, we seek to describe qualitatively and quantitatively the late time dependency of a solid particle cloud on its distribution before the energy release of an explosive. This work was supported by the U.S. DoE, NNSA, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

Detection of explosives using negative ion mobility spectrometry in air based on dopant-assisted thermal ionization.

PubMed

Shahraki, Hassan; Tabrizchi, Mahmoud; Farrokhpor, Hossein

2018-05-26

The ionization source is an essential component of most explosive detectors based on negative ion mobility spectrometry. Conventional ion sources suffer from such inherent limitations as special safety regulations on radioactive sources or generating interfering ions (for non-radioactive sources) such as corona discharge operating in the air. In this study, a new negative ion source is introduced for ion mobility spectrometry that is based on thermal ionization and operates in the air, applicable to explosives detection. Our system consists of a heating filament powered by an isolated power supply connected to negative high voltage. The ionization is assisted by doping chlorinated compounds in the gas phase using chlorinated hydrocarbons in contact with the heating element to yield Cl - reactant ions. Several chlorinated hydrocarbons are evaluated as the reagent chemicals for providing Cl- reactant ions, of which CCl 4 is identified as the best ionizing reagent. The ion source is evaluated by recording the ion mobility spectra of common explosives, including TNT, RDX, and PETN in the air. A detection limit of 150 pg is obtained for TNT. Compared to other ionization sources, the new source is found to be low-cost, simple, and long-lived, making it suited to portable explosives detection devices. Copyright © 2018 Elsevier B.V. All rights reserved.

Use of thermal infrared imaging for monitoring renewed dome growth at Mount St. Helens, 2004: Chapter 17 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

USGS Publications Warehouse

Schneider, David J.; Vallance, James W.; Wessels, Rick L.; Logan, Matthew; Ramsey, Michael S.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

2008-01-01

A helicopter-mounted thermal imaging radiometer documented the explosive vent-clearing and effusive phases of the eruption of Mount St. Helens in 2004. A gyrostabilized gimbal controlled by a crew member housed the radiometer and an optical video camera attached to the nose of the helicopter. Since October 1, 2004, the system has provided thermal and video observations of dome growth. Flights conducted as frequently as twice daily during the initial month of the eruption monitored rapid changes in the crater and 1980-86 lava dome. Thermal monitoring decreased to several times per week once dome extrusion began. The thermal imaging system provided unique observations, including timely recognition that the early explosive phase was phreatic, location of structures controlling thermal emissions and active faults, detection of increased heat flow prior to the extrusion of lava, and recognition of new lava extrusion. The first spines, 1 and 2, were hotter when they emerged (maximum temperature 700-730°C) than subsequent spines insulated by as much as several meters of fault gouge. Temperature of gouge-covered spines was about 200°C where they emerged from the vent, and it decreased rapidly with distance from the vent. The hottest parts of these spines were as high as 500-730°C in fractured and broken-up regions. Such temperature variation needs to be accounted for in the retrieval of eruption parameters using satellite-based techniques, as such features are smaller than pixels in satellite images.

Selective Sampling with Direct Ion Mobility Spectrometric Detection for Explosives Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harvey, Scott D; Ewing, Robert G; Waltman, Melanie J

2009-06-29

This study investigates the potential and limitations of a streamlined, field-deployable analytical approach that involves selective capture of explosive materials with direct analysis by ion mobility spectrometry (IMS). Selective capture of explosives was performed on deactivated quartz fiber filters impregnated with metal β-diketonate polymers. These Lewis acidic polymers selectively interact with Lewis base analytes such as explosives. The filter coupons could be directly inserted into an IMS instrument for analysis. The uptake kinetics of 2,4,6-trinitrotoluene (TNT) from a saturated atmosphere were characterized, and based on these studies, passive equilibrium sampling was applied to estimate the TNT concentration within an ammunitionmore » magazine that contained bulk TNT. Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) uptake from a saturated environment also was examined over a one-month period. Each incremental sampling period showed increasing quantities of RDX culminating with collection of approximately 5 ng of RDX on the coupon at the end of one month. This is the first time that gas-phase uptake of RDX has been demonstrated.« less

Study of energy partitioning using a set of related explosive formulations

NASA Astrophysics Data System (ADS)

Lieber, Mark; Foster, Joseph C.; Stewart, D. Scott

2012-03-01

Condensed phase high explosives convert potential energy stored in the electro-magnetic field structure of complex molecules to high power output during the detonation process. Historically, the explosive design problem has focused on intramolecular energy storage. The molecules of interest are derived via molecular synthesis providing near stoichiometric balance on the physical scale of the molecule. This approach provides prompt reactions based on transport physics at the molecular scale. Modern material design has evolved to approaches that employ intermolecular ingredients to alter the spatial and temporal distribution of energy release. State of the art continuum methods have been used to study this approach to the materials design. Cheetah has been used to produce data for a set of fictitious explosive formulations based on C-4 to study the partitioning of the available energy between internal and kinetic energy in the detonation. The equation of state information from Cheetah has been used in ALE3D to develop an understanding of the relationship between variations in the formulation parameters and the internal energy cycle in the products.

The evolution of solid density within a thermal explosion. I. Proton radiography of pre-ignition expansion, material motion, and chemical decomposition

NASA Astrophysics Data System (ADS)

Smilowitz, L.; Henson, B. F.; Romero, J. J.; Asay, B. W.; Saunders, A.; Merrill, F. E.; Morris, C. L.; Kwiatkowski, K.; Grim, G.; Mariam, F.; Schwartz, C. L.; Hogan, G.; Nedrow, P.; Murray, M. M.; Thompson, T. N.; Espinoza, C.; Lewis, D.; Bainbridge, J.; McNeil, W.; Rightley, P.; Marr-Lyon, M.

2012-05-01

We report proton transmission images obtained during direct heating of a sample of PBX 9501 (a plastic bonded formulation of the explosive nitramine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)) prior to the ignition of a thermal explosion. We describe the application of proton radiography using the 800 MeV proton accelerator at Los Alamos National Laboratory to obtain transmission images in these thermal explosion experiments. We have obtained images at two spatial magnifications and viewing both the radial and the transverse axes of a solid cylindrical sample encased in aluminum. During heating we observe the slow evolution of proton transmission through the samples, with particular detail during material flow associated with the HMX β-δ phase transition. We also directly observe the loss of solid density to decomposition associated with elevated temperatures in the volume defining the ignition location in these experiments. We measure a diameter associated with this volume of 1-2 mm, in agreement with previous estimations of the diameter using spatially resolved fast thermocouples.

Explosives signatures and analysis

NASA Astrophysics Data System (ADS)

Fountain, Augustus Way, III; Oyler, Jonathan M.; Ostazeski, Stanley A.

2008-04-01

The challenge of sampling explosive materials for various high threat military and civilian operational scenarios requires the community to identify and exploit other chemical compounds within the mixtures that may be available to support stand-off detection techniques. While limited surface and vapor phase characterization of IEDs exist, they are insufficient to guide the future development and evaluation of field deployable explosives detection (proximity and standoff) capabilities. ECBC has conducted a limited investigation of three artillery ammunition types to determine what chemical vapors, if any, are available for sensing; the relative composition of the vapors which includes the more volatile compounds in munitions, i.e., plastersizers and binders; and the sensitivity needed detect these vapors at stand-off. Also in partnership with MIT-Lincoln Laboratory, we performed a background measurement campaign at the National Training Center to determine the baseline ambient amounts and variability of nitrates and nitro-ester compounds as vapors, particulates, and on surfaces; as well as other chemical compounds related to non-energetic explosive additives. Environmental persistence studies in contexts relevant to counter-IED sensing operations, such as surface residues, are still necessary.

A complete equation of state for non-ideal condensed phase explosives

NASA Astrophysics Data System (ADS)

Wilkinson, S. D.; Braithwaite, M.; Nikiforakis, N.; Michael, L.

2017-12-01

The objective of this work is to improve the robustness and accuracy of numerical simulations of both ideal and non-ideal explosives by introducing temperature dependence in mechanical equations of state for reactants and products. To this end, we modify existing mechanical equations of state to appropriately approximate the temperature in the reaction zone. Mechanical equations of state of the Mie-Grüneisen form are developed with extensions, which allow the temperature to be evaluated appropriately and the temperature equilibrium condition to be applied robustly. Furthermore, the snow plow model is used to capture the effect of porosity on the reactant equation of state. We apply the methodology to predict the velocity of compliantly confined detonation waves. Once reaction rates are calibrated for unconfined detonation velocities, simulations of confined rate sticks and slabs are performed, and the experimental detonation velocities are matched without further parameter alteration, demonstrating the predictive capability of our simulations. We apply the same methodology to both ideal (PBX9502, a high explosive with principal ingredient TATB) and non-ideal (EM120D, an ANE or ammonium nitrate based emulsion) explosives.

Application of Liquid Paraffin in Castable CL-20-Based PBX

NASA Astrophysics Data System (ADS)

Zhang, Pu; Guo, Xue-Yong; Zhang, Jing-Yuan; Jiao, Qing-Jie

2014-10-01

Hydroxy-terminated polybutadiene (HTPB)/CL-20 castable explosives plasticized with liquid paraffin were processed successfully by a cast-curing method. The compatibility of liquid paraffin with CL-20, influence of liquid paraffin on CL-20 phase transition, and viscosity of the cast mixture were tested and analyzed. The thermal decomposition characteristics, thermal stability, mechanical sensitivity, and velocity of detonation (VOD) of the HTPB/CL-20 plastic-bonded explosives (PBXs) were also measured. The experimental results showed that liquid paraffin was well compatible with CL-20, and it did not have a distinct effect on the ɛ- to γ-phase transition of CL-20. In addition, the casting mixture was free-flowing with sufficiently low viscosity. When the content of CL-20 is 90% by weight, the measured VOD reached 8,775 m/s (density of 1.78 g/cm3), and the PBXs exhibited moderate mechanical sensitivity and good thermal stability.

Photonic sensor devices for explosive detection.

PubMed

Willer, Ulrike; Schade, Wolfgang

2009-09-01

For the sensitive online and in situ detection of gaseous species, optical methods are ideally suited. In contrast to chemical analysis, no sample preparation is necessary and therefore spectroscopic methods should be favorable both in respect of a fast signal recovery and economically because no disposal is needed. However, spectroscopic methods are currently not widely used for security applications. We review photonic sensor devices for the detection of explosives in the gas phase as well as the condensed phase and the underlying spectroscopic techniques with respect to their adaptability for security applications, where high sensitivity, high selectivity, and a low false-alarm rate are of importance. The measurements have to be performed under ambient conditions and often remote handling or even operation in standoff configuration is needed. For handheld and portable equipment, special attention is focused on the miniaturization and examples for already-available sensor devices are given.

The Main Sequence of Explosive Solar Active Regions: Comparison of Emerging and Mature Active Regions

NASA Technical Reports Server (NTRS)

Falconer, David; Moore, Ron

2011-01-01

For mature active regions, an active region s magnetic flux content determines the maximum free energy the active region can have. Most Large flares and CMEs occur in active regions that are near their free-energy limit. Active-region flare power radiated in the GOES 1-8 band increases steeply as the free-energy limit is approached. We infer that the free-energy limit is set by the rate of release of an active region s free magnetic energy by flares, CMEs and coronal heating balancing the maximum rate the Sun can put free energy into the active region s magnetic field. This balance of maximum power results in explosive active regions residing in a "mainsequence" in active-region (flux content, free energy content) phase space, which sequence is analogous to the main sequence of hydrogen-burning stars in (mass, luminosity) phase space.

Explosive plasma flows in a solar flare

NASA Technical Reports Server (NTRS)

Zarro, Dominic M.; Canfield, Richard C.; Metcalf, Thomas R.; Strong, Keith T.

1988-01-01

Solar Maximum Mission soft X-ray data and Sacramento Peak Observatory H-alpha observations are combined in a study of the impulsive phase of a solar flare. A blue asymmetry, indicative of upflows, was observed in the coronal Ca XIX line during the soft X-ray rise phase. A red asymmetry, indicative of downflows, was observed simultaneously in chromospheric H-alpha emitted from bright flare kernels during the period of hard X-ray emission. Combining the velocity data with a measurement of coronal electron density, it is shown that the impulsive phase momentum of upflowing soft X-ray-emitting plasma equalled that of the downflowing H-alpha-emitting plasma to within one order of magnitude. In particular, the momentum of the upflowing plasma was 2 x 10 to the 21st g cm/s while that of the downflowing plasma was 7 x 10 to the 21st g cm/s, with a factor of 2 uncertainty on each value. This equality supports the explosive chromospheric evaporation model of solar flares, in which a sudden pressure increase at the footprint of a coronal loop produces oppositely directed flows in the heated plasma.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ritter, Boyd

Insensitive high explosives (IHEs) based on 1,3,5-triamino 2,4,6-trinitro-benzene (TATB) are the IHEs of choice for use in nuclear warheads over conventional high explosives when safety is the only consideration, because they are very insensitive to thermal or mechanical initiation stimuli. It is this inherent insensitivity to high temperatures, shock, and impact, which provides detonation design challenges when designing TATB explosive systems while at the same time providing a significant level of protection against accidental initiation. Although classified as IHE, over the past few years the focus on explosive safety has demonstrated that the shock sensitivity of TATB is influenced withmore » respect to temperature. A number of studies have been performed on TATB and TATB formulations, plastic bonded explosives (PBX) 9502, and LX-17-01 (LX-17), which demonstrates the increase in shock sensitivity of the explosive after it has been preheated or thermally cycled over various temperature ranges. Many studies suggest the change in sensitivity is partly due to the decomposition rates of the temperature elevated TATB. Others point to the coefficient of thermal expansion, the crystalline structures of TATB and/or the combination of all factors, which create voids which can become active hot spots. During thermal cycling, TATB is known to undergo an irreversible increase in specific volume called ratchet growth. This increase in specific volume correlates to a decrease in density. This decrease in density and increase in volume, demonstrate the creations of additional void spaces which could serve as potential new initiation hot spots thus, increasing the overall sensitivity of the HE. This literature review evaluates the published works to understand why the shock sensitivity of TATB-based plastic bonded explosives (PBXs) changes with temperature.« less

The response of the HMX-based material PBXN-9 to thermal insults: thermal decomposition kinetics and morphological changes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glascoe, E A; Hsu, P C; Springer, H K

PBXN-9, an HMX-formulation, is thermally damaged and thermally decomposed in order to determine the morphological changes and decomposition kinetics that occur in the material after mild to moderate heating. The material and its constituents were decomposed using standard thermal analysis techniques (DSC and TGA) and the decomposition kinetics are reported using different kinetic models. Pressed parts and prill were thermally damaged, i.e. heated to temperatures that resulted in material changes but did not result in significant decomposition or explosion, and analyzed. In general, the thermally damaged samples showed a significant increase in porosity and decrease in density and a smallmore » amount of weight loss. These PBXN-9 samples appear to sustain more thermal damage than similar HMX-Viton A formulations and the most likely reasons are the decomposition/evaporation of a volatile plasticizer and a polymorphic transition of the HMX from {beta} to {delta} phase.« less

Defence Capability Plan 2006-2016

DTIC Science & Technology

2006-06-14

and supply chain management ; and • developing strategies focussing on critical industry capabilities and Defence’s ability to manage supply and... managers undertake pre-approval study activity and prepare the necessary departmental documentation. More formal industry solicitation would continue...Defence Management Systems Improvement Less than $10m JP 2085 Phase 1B Explosive Ordnance Warstock $150m to $200m JP 2090 Phase 1B Combined Information

Reaction Mechanisms of Energetic Materials in the Condensed Phase: Long-term Aging, Munition Safety and Condensed-Phase Processes in Propellants and Explosives

DTIC Science & Technology

2009-03-31

Journal of the American Society for Mass Spectrometry, 2002. 13(2): p. 135- 143 . 7. Delcorte, A., P. Bertrand, and B.J. Garrison, Collision cascade and...TNCHP. 49, 50 The presence of the keto group in K6 appears to promote a more direct reaction to the gaseous decomposition products. Decomposition

Surface Wave Detection and Measurement Using a One Degree Global Dispersion Grid

DTIC Science & Technology

2006-05-01

explosions at all major test sites .................................................................... 21 List of Figures (continued) Figure 17 Page...surface - . 7 " wave phase and group velocity dispersion curves from underground nuclear test sites (Stevens, 1986; Stevens and McLaughlin, 19881...calculated from earth models for 270 paths ( test site - station combinations) at 10 frequencies between 0.01 5 and 0.06 Hz; phase and group velocity

Eyjafjallajökull2010 - The activity of the eruption plume during the first 2 weeks

NASA Astrophysics Data System (ADS)

Sigurősson, Árni; Pálmason, Bolli; Hlíőar Jensen, Esther; Petersen, Gudrun Nina; Björnsson, Halldór; Şorsteinsson, Hróbjartur; Arason, Şórőur

2010-05-01

On 14 April 2010 an eruption started in Eyjafjallajökull, in southern Iceland. This was an explosive eruption in the caldera, beneath the glacier. During the first two weeks the eruption went through two phases, an explosive phase with much tephra and ash production and a calmer phase with less productivity and some lava production. During the explosive phase 14-17 April, the plume altititude was about 5-7 km but occasionally increased up to 8 km height, there was lightning activity in the plume and the material produced was mainly ash and tephra. It is estimated that the production was peaked at about 750 tons/s. The local ash fall on 17 April was the worst by far for the local community to the south of the volcano as about a 1 km thick ash cloud flowed almost continuously from the volcano and over the region. During this phase the upper level winds over Iceland were strong, northwesterly 40-50 m/s, and the emitted ash was advected southeastward toward northwestern Europe. This caused major disruption in air traffic. During the second phase 18-29 April there was a reduced net output form the volcano, lava production was estimated as 10-30 tons/s and tephra and ash production of less than 10 tons/s. The height of the plume was estimated as 3-5 km. Local ash fall predictions were made for the areas within a 500 km radius from the eruption site and prediction maps published on the website of the Icelandic Met Office. Information on local ash fall were collected from synoptic weather stations but also from the general public and the media. An internet web registration form was made public and advertised. In 6 days 95 reports of ash fall were made. This information together with other ground observations and remote sense observations are important for validations of ash fall prediction, near field and far field, as well as ensuring that the impact of the volcanic eruption is well understood, in a geological, geophysical and biological sense but also the societal impact on the communities affected.

Acoustic and tephra records of explosive eruptions at West Mata submarine volcano, NE Lau Basin

NASA Astrophysics Data System (ADS)

Dziak, R. P.; Bohnenstiehl, D. R.; Baker, E. T.; Matsumoto, H.; Caplan-Auerbach, J.; Mack, C. J.; Embley, R. W.; Merle, S. G.; Walker, S. L.; Lau, T. A.

2013-12-01

West Mata is a 1200 m deep submarine volcano where explosive boninite eruptions were directly observed in May 2009. Here we present long-term acoustic and tephra records of West Mata explosion activity from three deployments of hydrophone and particle sensor moorings beginning on 8 January 2009. These records provide insights into the character of explosive magma degassing occurring at the volcano's summit vent until the decline and eventual cessation of the eruption during late 2010 and early 2011. The detailed acoustic records show three types of volcanic signals, 1) discrete explosions, 2) diffuse explosions, and 3) volcanic tremor. Discrete explosions are short duration, high amplitude broad-band signals caused by rapid gas bubble release. Diffuse signals are likely a result of 'trap-door' explosions where a quench cap of cooled lava forms over the magmatic vent but gas pressure builds underneath the cap. This pressure eventually causes the cap to breach and gas is explosively released until pressure reduces and the cap once again forms. Volcanic tremor is typified by narrow-band, long-duration signals with overtones, as well as narrow-band tones that vary frequency over time between 60-100 Hz. The harmonic tremor is thought to be caused by modulation of rapid, short duration gas explosion pulses and not a magma resonance phenomenon. The variable frequency tones may be caused by focused degassing or hydrothermal fluid flow from a narrow volcanic vent or conduit. High frequency (>30 Hz) tremor-like bands of energy are a result of interference caused by multipath wide-band signals, including sea-surface reflected acoustic phases, that arrive at the hydrophone with small time delays. Acoustic data suggest that eruption velocities for a single explosion range from 4-50 m s-1, although synchronous arrival of explosion signals has complicated our efforts to estimate long-term gas flux. Single explosions exhibit ~4-40 m3 s-1 of total volume flux (gas and rock) but with durations of only 20-30 ms. Interestingly, explosion activity increased at West Mata for several months, observed at more distant hydrophone stations, following the September 2009 8.1 Mw Samoan earthquake. The tephra and hydrophone data were only synchronously recorded from January to May 2010, but these data indicate a repeated record of summit explosions followed by down flank debris flows, an important process in the construction of the volcanic edifice. Bathymetric differencing between 2010 and 2011 shows two large negative anomalies at the summit and a broad positive anomaly on the east flank, interpreted as a major slump that removed part of the summit during the final magma withdrawal related to formation of the summit pit crater.

Influence of the parameters of a high-frequency acoustic wave on the structure, properties, and plastic flow of metal in the zone of a joint of materials welded by ultrasound-assisted explosive welding

NASA Astrophysics Data System (ADS)

Peev, A. P.; Kuz'min, S. V.; Lysak, V. I.; Kuz'min, E. V.; Dorodnikov, A. N.

2017-05-01

The results of an investigation of the influence of the parameters of high-frequency acoustic wave on the structure and properties of the zone of joint of homogeneous metals bonded by explosive welding under the action of ultrasound have been presented. The influence of the frequency and amplitude of ultrasonic vibrations on the structure and properties of the explosively welded joints compared with the samples welded without the application of ultrasound has been established. The action of high-frequency acoustic waves on the metal leads to a reduction in the dynamic yield stress, which changes the properties of the surface layers of the metal and the conditions of the formation of the joint of the colliding plates upon the explosive welding. It has been shown that the changes in the length and amplitude of waves that arise in the weld joint upon the explosive welding with the simultaneous action of ultrasonic vibrations are connected with a decrease in the magnitude of the deforming pulse and time of action of the compressive stresses that exceed the dynamic yield stress beyond the point of contact.

A kilohertz approach to Strombolian-style eruptions

NASA Astrophysics Data System (ADS)

Taddeucci, Jacopo; Scarlato, Piergiorgio; Del Bello, Elisabetta; Gaudin, Damien

2015-04-01

Accessible volcanoes characterized by persistent, relatively mild Strombolian-style explosive activity have historically hosted multidisciplinary studies of eruptions. These studies, focused on geophysical signals preceding, accompanying, and following the eruptions, have provided key insights on the physical processes driving the eruptions. However, the dynamic development of the single explosions that characterize this style of activity remained somewhat elusive, due to the timescales involved (order of 0.001 seconds). Recent technological advances now allow recording and synchronizing different data sources on time scales relevant to the short timescales involved in the explosions. In the last several years we developed and implemented a field setup that integrates visual and thermal imaging with acoustic and seismic recordings, all synchronized and acquired at timescales of 100-10000 Hz. This setup has been developed at several active volcanoes. On the one hand, the combination of these different techniques provides unique information on the dynamics and energetics of the explosions, including the parameterization of individual ejection pulses within the explosions, the ejection and emplacement of pyroclasts and their coupling-decoupling with the gas phases, the different stages of development of the eruption jets, and their reflection in the associated acoustic and seismic signals. On the other hand, the gained information provides foundation for better understanding and interpreting the signals acquired, at lower sampling rates but routinely, from volcano monitoring networks. Perhaps even more important, our approach allows parameterizing differences and commonalities in the explosions from different volcanoes and settings.

Volcanic tremor and frequency gliding during dike intrusions at Kı¯lauea—A tale of three eruptions

NASA Astrophysics Data System (ADS)

Unglert, K.; Jellinek, A. M.

2015-02-01

To characterize syneruptive/intrusive deviations from background volcanic tremor at Kı¯lauea, Hawai`i, we analyze the spatial and temporal properties of broadband tremor during dike intrusions into the East Rift Zone (ERZ) in 2007 and 2011, as well as during explosive eruptive activity at Kı¯lauea's summit in 2008. Background tremor was similar for each event, and the 2008 explosions did not affect its properties. In contrast, the intrusions were accompanied by departures from this background in the form of two phases of seismicity that were separated in space and time. In both 2007 and 2011, Phase I was characterized by a quick succession of discrete events, which were most intense at the onset of intrusion near the presumed locations of the dikes intruding into the ERZ. Phase II, marked by continuous broadband tremor around the summit, followed 10-14 h later. In 2007, Phase II tremor was accompanied by a monotonic downward shift (glide) of spectral peaks between ˜0.6 and 1.5 Hz over at least 15 h. During Phase II in 2011, a gradual upward and subsequent symmetric downward glide between ˜0.6 and 6.6 Hz occurred over 5-10 h, respectively. The spectra during both phases differed from the background and 2008, as well as from each other, indicating different physical mechanisms. Phase I in 2007 and 2011 is probably related to the mechanics of dike intrusion. Phase II tremor may be characteristic for evolving magma-bubble dynamics related to the geometry of the plumbing system and the style of magma flow.

Long-times series of infrasonic records at open-vents volcanoes (Yasur volcano, Vanuatu, 2003-2014): the remarkable temporal stability of magma viscosity

NASA Astrophysics Data System (ADS)

Vergniolle, S.; Souty, V.; Zielinski, C.; Bani, P.; LE Pichon, A.; Lardy, M.; Millier, P.; Herry, P.; Todman, S.; Garaebiti, E.

2017-12-01

Open-vents volcanoes, often presenting series of Strombolian explosions of various intensity, are responding, although with a delay, to any changes in the degassing pattern, providing a quasi-direct route to processes at depth. Open-vents volcanoes display a persistent volcanic activity, although of variable intensity. Long-times series at open-vents volcanoes could therefore be key measurements to unravel physical processes at the origin of Strombolian explosions and be crucial for monitoring. Continuous infrasonic records can be used to estimate the gas volume expelled at the vent during explosions (bursting of a long slug). The gas volume of each explosion is deduced from a series of two successive integrations of acoustic pressure (monopole). Here we analysed more than 4 years of infrasonic records at Yasur volcano (Vanuatu), spanning between 2003 and 2014 and organised into 8 main quasi-continuous periods. The relationship between the gas volume of each explosion and its associated maximum positive acoustic pressure, a proxy for the inner gas overpressure at bursting, shows a remarkably stable trend over the 8 periods. Two main trends exists, one which covers the full range of acoustic pressures (called « strong explosions ») and the second which represents explosions with a large gas volume and mild acoustic pressure. The class of « strong explosions » clearly follows the model of Del Bello et al. (2012), which shows that the inner gas overpressure at bursting, here empirically measured by the maximum acoustic pressure, is proportional to the gas volume. Constrains on magma viscosity and conduit radius, are deduced from this trend and from the gas volume at the transition passive-active degassing. The remarkable stability of this trend over time suggests that 1) the magma viscosity is stable at the depth where gas overpressure is produced within the slug and 2) any potential changes in magma viscosity occur very close to the top of the magma column.

The 3D Distribution of Magma Bodies that Fed the Paraná Silicic Volcanics, Brazil: A Combination of Field Evidence, Textural Analysis, and Geothermobarometry

NASA Astrophysics Data System (ADS)

Harmon, L.; Gualda, G. A. R.; Gravley, D. M.

2016-12-01

The Paraná Silicic Volcanics include some of the largest eruptive deposits known in the geological record. However, we know very little about the magma bodies that fed these eruptions. Combining physical volcanology, geochemistry, and geothermobarometry techniques, we aim to find the sources of extinct magma bodies to build a 3D view of the magma structure at the time by discovering storage conditions, eruption styles, and post-eruption alteration. The approach elucidates temporal and spatial eruption styles and sequences of the silicic units that make up the Palmas unit of the Serra Geral formation, Brazil. We use field investigations to determine the history of volcanic deposits, domes, and changes in eruptive style; we map and characterize volcanic deposits based on thickness (thicker is proximal to source) and distribution of effusive (proximal to source) and explosive deposits. We focus on several exposed canyons that exhibit either exclusively explosive or effusive, or a clear progression from explosive to effusive deposits. The progression from explosive to effusive indicates a system change from explosively energetic to effusively waning. Additionally, observation of pervasive flow banding in both effusive and explosive deposits indicates rheomorphic flow through many portions of the field area, an indicator of hot emplacement. Geochemical work focuses on the pre-eruptive magma conditions to determine the depth of magma bodies. We utilize glass bearing samples of both the explosively deposited juvenile blob-like structures and obsidian samples to determine crystallization depth. The glass is variably altered, via silicification and devitrification processes, with the blobs more greatly silicified than the obsidian. We use rhyolite-MELTS geothermobarometry when pristine glass can be found. Initial results indicate shallow ( 80 MPa) storage conditions for the explosively erupted blobs. The combination of techniques builds a 3D understanding of extinct super-eruptive systems, and has the potential to unravel both the pre-eruptive and deposition dynamics of the Paraná Silicic Volcanics.

The activity of the Colima volcano and morphological changes in the summit between 2004 and 2013

NASA Astrophysics Data System (ADS)

Suarez-Plascencia, C.; Nunez-Cornu, F. J.; Camarena Garcia, M. A.

2013-05-01

Colima Volcano, located in the West of the Volcanic Mexican Belt (19° 30.696 N, 103° 37.026 W), has shown a new cycle of explosive activity beginning May 30 1999, and reaching its maximum in March-April of 2005 and January 2013. In the 2005 the explosive activity increased gradually, having the largest event on May 23, when a new dome was created. Hours later this dome was destroyed by a strong explosion, forming an ash column 5.6 km high with subsequent pyroclastic flows that reached a distance of 4.2 km flowing along the ravines of the South sector. On May 30 the most intense explosion in 1999 occurred, when the plume reached heights in excess of 4.4 km above the crater, and pyroclastic flows were created. On the same year in July two explosive events occurred of characteristics similar to those in May. These constant explosions caused continuous morphological changes in the summit, the most significant being the collapse of the North and South walls of the crater, in the first week of June of 2005, and the creation of a new crater in July. In 2006 the most significant explosive activity took place during April, May and July, when the eruptive columns reached heights of more than 1500 meters above the crater, occasionally forming small pyroclastic flows. In May of 2007 morphological changes were observed in the summit. Among them a crater explosion on the East side, a dome was formed on the West side, with 20 m in high and 50 m in diameter. Since the end of 2008 to December of 2012 the volcano remained calm, with a dome diameter of 220 m and height of 60 m, in January 2013 three explosions occurred, destroying the dome and throwing a volume of 1.5 million cubic meters. The eruptive column reached a height of 3000 above the crater. It reported light ashfall to the NE to 100 km away from the volcano. The explosive events continue to date, but they have diminished in size and intensity. This activity was similar to the one observed in 1902-1903 and reported by Severo Diaz and J.M. Arreola (1906), but without reaching the maximum levels of activity reported for 1903, where it had levels of three to five maximum explosive events per day. The photographs and the digital mapping have provided detailed information to quantify the dynamic evolution of the volcanic structures that developed on the summit of the volcano in the course of the last for years. The cartographic and database information obtained will be the basis for updating the Operational Plan of the Colima Volcano by the State Civil & Fire Protection Unit of Jalisco, Mexico, and the urban development plans of surrounding municipalities, in order to reduce their vulnerability to the hazards of the volcanic activity.

Statistical analyses and characteristics of volcanic tremor on Stromboli Volcano (Italy)

NASA Astrophysics Data System (ADS)

Falsaperla, S.; Langer, H.; Spampinato, S.

A study of volcanic tremor on Stromboli is carried out on the basis of data recorded daily between 1993 and 1995 by a permanent seismic station (STR) located 1.8km away from the active craters. We also consider the signal of a second station (TF1), which operated for a shorter time span. Changes in the spectral tremor characteristics can be related to modifications in volcanic activity, particularly to lava effusions and explosive sequences. Statistical analyses were carried out on a set of spectra calculated daily from seismic signals where explosion quakes were present or excluded. Principal component analysis and cluster analysis were applied to identify different classes of spectra. Three clusters of spectra are associated with two different states of volcanic activity. One cluster corresponds to a state of low to moderate activity, whereas the two other clusters are present during phases with a high magma column as inferred from the occurrence of lava fountains or effusions. We therefore conclude that variations in volcanic activity at Stromboli are usually linked to changes in the spectral characteristics of volcanic tremor. Site effects are evident when comparing the spectra calculated from signals synchronously recorded at STR and TF1. However, some major spectral peaks at both stations may reflect source properties. Statistical considerations and polarization analysis are in favor of a prevailing presence of P-waves in the tremor signal along with a position of the source northwest of the craters and at shallow depth.

Degassing vs. eruptive styles at Mt. Etna volcano (Sicily, Italy): Volatile stocking, gas fluxing, and the shift from low-energy to highly-explosive basaltic eruptions

NASA Astrophysics Data System (ADS)

Moretti, Roberto; Métrich, Nicole; Di Renzo, Valeria; Aiuppa, Alessandro; Allard, Patrick; Arienzo, Ilenia

2017-04-01

Basaltic magmas can transport and release large amounts of volatiles into the atmosphere, especially in subduction zones, where slab-derived fluids enrich the mantle wedge. Depending on magma volatile content, basaltic volcanoes thus display a wide spectrum of eruptive styles, from common Strombolian-type activity to Plinian events. Mt. Etna in Sicily, is a typical basaltic volcano where the volatile control on such a variable activity can be investigated. Based on a melt inclusion study in products from Strombolian or lava-fountain activity to Plinian eruptions, here we show that for the same initial volatile content, different eruptive styles reflect variable degassing paths throughout the composite Etnean plumbing system. The combined influence of i) crystallization, ii) deep degassing and iii) CO2 gas fluxing can explain the evolution of H2O, CO2, S and Cl in products from such a spectrum of activity. Deep crystallization produces the CO2-rich gas fluxing the upward magma portions, which will become buoyant and easily mobilized in small gas-rich batches stored within the plumbing system. When reaching gas dominated conditions (i.e., a gas/melt mass ratio of 0.3 and CO2,gas/H2Ogas molar ratio 5 ), these will erupt effusively or mildly explosively, whilst in case of the 122 BC Plinian eruption, open-system degassing conditions took place within the plumbing system, such that continuous CO2-fluxing determined gas accumulation on top of the magmatic system. The emission of such a cap in the early eruptive phase triggered the arrival of deep H2O-rich whose fast decompression and bubble nucleation lead to the highly explosive character, enhanced by abundant microlite crystallization and consequent increase of magma effective viscosity. This could explain why open system basaltic systems like Etna may experience highly explosive or even Plinian episodes during eruptions that start with effusive to mildly explosive phases. The proposed mechanism also determines a depression of chlorine contents in CO2-fluxed (and less explosive) magmas with respect to those feeding Plinian events like 122 BC one. The opposite is seen for sulfur: low to mild-explosive fluxed magmas are S-enriched, whereas the 122 BC Plinian products are relatively S-poor, likely because of early sulfide separation accompanying magma crystallization. The proposed mechanism involving CO2 separation and fluxing may suggest a subordinate role for variable mixing of different sources having different degrees of K-enrichment. However, such a mechanism requires further experimental studies about the effects on S and Cl dissolution and does not exclude self-mixing between degassed and undegassed batches within the Etna plumbing system. Finally, our findings may represent a new interpretative tool for the geochemical and petrological monitoring of plume gas discharges and melt inclusions, and allow tracking the switch from mild-explosive to highly explosive or even Plinian events at Etna.

COBE limits on explosive structure formation scenarios

NASA Technical Reports Server (NTRS)

Levin, Janna J.; Freese, Katherine; Spergle, David N.

1992-01-01

The Compton y-distortion that would result from an epoch of explosions at moderate redshifts is estimated and compared to recent measurements of the CBR spectrum made by the COBE satellite. The temperature anisotropy on large angular scales is estimated, and it is found that in general the limits on the overall spectral distortion are more constraining than those on the temperature anisotropy. It is found that most of the y-distortion is produced during the early, noncosmological phase of bubble evolution. An expression is obtained for the y-distortion including the effects of Compton cooling. The implications of the findings are discussed.

A Late Holocene explosive mafic eruption of Villarrica volcano, Southern Andes: The Chaimilla deposit

NASA Astrophysics Data System (ADS)

Costantini, L.; Pioli, L.; Bonadonna, C.; Clavero, J.; Longchamp, C.

2011-03-01

Villarrica (Chile) is one of the most active volcanoes in South America having erupted about 60 times in the last 460 years. Although its historical eruptive activity has been mainly effusive and weakly explosive, it had strong explosive behaviour in postglacial times. Chaimilla (< 3.1 ka) is one of the best exposed and widely dispersed pyroclastic deposits, related to both fall and flow activity. The deposit is dispersed over an area of 250 km 2 and consists of 8 units (A-H) which were grouped into four sequences. Stratigraphic data suggest that the eruption had a relatively short duration and evolved from i) an Opening phase, dispersing ash, lapilli clasts, accretionary lapilli, blocks and bombs, to ii) a Pulsatory phase, originating a series of magmatic explosions, to iii) a Collapsing phase, characterised by unstable plumes which emplaced a series of pyroclastic density currents intercalated with thin fallout layers and finally to iv) a Climactic phase forming a more sustained plume which eventually collapsed generating the final pyroclastic density currents. The deposit (fall and flow) has a minimum cumulative volume of 0.6 km 3, with the main sustained phase being associated with a VEI 4 and the flow units having a minimum estimated total volume of 0.04 km 3. The erupted material has a homogenous chemical composition but displays a remarkable variability in both textural and physical properties. The density distribution of juvenile products shows a clear bimodality characterised by two main populations: P1 and P2. Population P1 consists of highly vesicular clasts (modal density around 1000 kg m - 3 ) with mostly sub-spherical bubbles and moderately crystallised groundmass with large-sized microlites. Clasts from population P2 are poorly vesicular (modal density around 1600 kg m - 3 ) with irregular to collapsed bubbles and numerous smaller microlites. The variability of both vesicularity and microlite characteristics suggests the involvement of two magma batches with distinct pre-eruptive degassing and rising histories. Our eruption conceptual model implies the arrival of new magma (represented in the deposit by P1 clasts) into a small, outgassed magma body which was accumulated at shallow level (mainly represented by P2 clasts). A new Chaimilla-type eruption could significantly affect the communities that have recently developed around Villarrica volcano and subsist mainly on tourism and forestry. As a result, a better understanding of the dynamics and evolution of the Chaimilla eruption is necessary for the identification of potential hazard scenarios at Villarrica volcano and, ultimately, for the risk mitigation of this populated area of Southern Chile.

Evolution of submarine eruptive activity during the 2011-2012 El Hierro event as documented by hydroacoustic images and remotely operated vehicle observations

NASA Astrophysics Data System (ADS)

Somoza, L.; González, F. J.; Barker, S. J.; Madureira, P.; Medialdea, T.; de Ignacio, C.; Lourenço, N.; León, R.; Vázquez, J. T.; Palomino, D.

2017-08-01

Submarine volcanic eruptions are frequent and important events, yet they are rarely observed. Here we relate bathymetric and hydroacoustic images from the 2011 to 2012 El Hierro eruption with surface observations and deposits imaged and sampled by ROV. As a result of the shallow submarine eruption, a new volcano named Tagoro grew from 375 to 89 m depth. The eruption consisted of two main phases of edifice construction intercalated with collapse events. Hydroacoustic images show that the eruptions ranged from explosive to effusive with variable plume types and resulting deposits, even over short time intervals. At the base of the edifice, ROV observations show large accumulations of lava balloons changing in size and type downslope, coinciding with the area where floating lava balloon fallout was observed. Peaks in eruption intensity during explosive phases generated vigorous bubbling at the surface, extensive ash, vesicular lapilli and formed high-density currents, which together with periods of edifice gravitational collapse, produced extensive deep volcaniclastic aprons. Secondary cones developed in the last stages and show evidence for effusive activity with lava ponds and lava flows that cover deposits of stacked lava balloons. Chaotic masses of heterometric boulders around the summit of the principal cone are related to progressive sealing of the vent with decreasing or variable magma supply. Hornitos represent the final eruptive activity with hydrothermal alteration and bacterial mats at the summit. Our study documents the distinct evolution of a submarine volcano and highlights the range of deposit types that may form and be rapidly destroyed in such eruptions.