Underwater Shock Response Analysis of a Floating Vessel

Directory of Open Access Journals (Sweden)

J.E. van Aanhold

1998-01-01

Full Text Available The response of a surface vessel to underwater shock has been calculated using an explicit finite element analysis. The analysis model is two-dimensional and contains the floating steel structure, a large surrounding water volume and the free surface. The underwater shock is applied in the form of a plane shock wave and cavitation is considered in the analysis. Advanced computer graphics, in particular video animations, provide a powerful and indispensable means for the presentation and evaluation of the analysis results.

Underwater explosive compaction-sintering of tungsten-copper coating on a copper surface

Science.gov (United States)

Chen, Xiang; Li, Xiaojie; Yan, Honghao; Wang, Xiaohong; Chen, Saiwei

2018-01-01

This study investigated underwater explosive compaction-sintering for coating a high-density tungsten-copper composite on a copper surface. First, 50% W-50% Cu tungsten-copper composite powder was prepared by mechanical alloying. The composite powder was pre-compacted and sintered by hydrogen. Underwater explosive compaction was carried out. Finally, a high-density tungsten-copper coating was obtained by diffusion sintering of the specimen after explosive compaction. A simulation of the underwater explosive compaction process showed that the peak value of the pressure in the coating was between 3.0 and 4.8 GPa. The hardness values of the tungsten-copper layer and the copper substrate were in the range of 87-133 and 49 HV, respectively. The bonding strength between the coating and the substrate was approximately 100-105 MPa.

Aluminum-Enhanced Underwater Electrical Discharges for Steam Explosion Triggering

International Nuclear Information System (INIS)

HOGELAND, STEVE R.; NELSON, LLOYD S.; ROTH, THOMAS CHRISTOPHER

1999-01-01

For a number of years, we have been initiating steam explosions of single drops of molten materials with pressure and flow (bubble growth) transients generated by discharging a capacitor bank through gold bridgewires placed underwater. Recent experimental and theoretical advances in the field of steam explosions, however, have made it important to substantially increase these relatively mild transients in water without using high explosives, if possible. To do this with the same capacitor bank, we have discharged similar energies through tiny strips of aluminum foil submerged in water. By replacing the gold wires with the aluminum strips, we were able to add the energy of the aluminum-water combustion to that normally deposited electrically by the bridgewire explosion in water. The chemical enhancement of the explosive characteristics of the discharges was substantial: when the same electrical energies were discharged through the aluminum strips, peak pressures increased as much as 12-fold and maximum bubble volumes as much as 5-fold above those generated with the gold wires. For given weights of aluminum, the magnitudes of both parameters appeared to exceed those produced by the underwater explosion of equivalent weights of high explosives

Experimental and numerical study on penetration of micro/nano diamond particle into metal by underwater shock wave

Directory of Open Access Journals (Sweden)

S Tanaka

2016-09-01

Full Text Available In order to develop composite materials, new attempting was conducted. When an explosive is exploded in water, underwater shock wave is generated. Metal plate is accelerated by the underwater shock wave and collided with diamond particles at high velocity. In this paper, pure aluminum and magnesium alloy plates are used as matrix. Micro and nano sized diamond particles were used as reinforcement. Micro diamond particles were closely coated on metal surface. Some of micro diamond particles were penetrated into aluminum. Improvement of base metal property (wearing resistance was verified by wear test for recovering metal plate. In order to confirm the deformation of the aluminum plate during the collision with diamond particles, simplified numerical simulation was conducted by using LS-DYNA software. From the result of numerical simulation, large deformation of aluminum and process of particle penetration were verified.

The Basic Research for Pulverization of Rice Using Underwater Shock Wave by Electric Discharge

Directory of Open Access Journals (Sweden)

M Ide

2016-09-01

Full Text Available In recent years, the food self-support rate of Japan is 40%, and this value is the lowest level in major developed countries. This reason includes decreasing of diverting rice consumption in Japan and increasing abandonment of cultivation. Therefore, these problems are solved by using rice powder instead of expensive flour, and we manage to increase the food selfsupport rate. Previously, the rice powder is manufactured by two methods. One is dry type, and the other is wet type. The former is the method getting rice powder by running dried rice to rotating metal, and has a problem which that starch is damaged by heat when processing was performed. The latter is performed same method against wet rice, and has a problem which a large quantity of water is used. As a method to solve these problems, an underwater shock wave is used. Shock wave is the pressure wave which is over speed of sound by discharging high energy in short time. Propagating shock wave in water is underwater shock wave. The characters of underwater shock wave are long duration of shock wave because water density is uniform, water is low price and easy to get and not heat processing. Thinking of industrialization, the electric discharge is used as the generating source of underwater shock wave in the experiment. As the results, the efficiency of obtaining enough grain size, 100ìm, of rice powder was too bad only using the simple processing using underwater shock wave. Therefore, in Okinawa National College of Technology collaborating with us, obtaining rice powder with higher efficiency by using converged underwater shock wave is the goal of this research. In this research, the underwater shock wave with equal energy of the experimental device of underwater shock wave is measured by the optical observation. In addition, the appearance converging underwater shock wave is simulated by numerical analysis, and the pressure appreciation rate between the first wave and converged

Experimental studies on the deformation and rupture of thin metal plates subject to underwater shock wave loading

Directory of Open Access Journals (Sweden)

Chen Pengwan

2015-01-01

Full Text Available In this paper, the dynamic deformation and rupture of thin metal plates subject to underwater shock wave loading are studied by using high-speed 3D digital image correlation (3D-DIC. An equivalent device consist of a gas gun and a water anvil tube was used to supplying an exponentially decaying pressure in lieu of explosive detonation which acted on the panel specimen. The thin metal plate is clamped on the end of the shock tube by a flange. The deformation and rupture process of the metal plates subject to underwater shock waves are recorded by two high-speed cameras. The shape, displacement fields and strain fields of the metal plates under dynamic loading are obtained by using VIC-3D digital image correlation software. The strain gauges also were used to monitor the structural response on the selected position for comparison. The DIC data and the strain gauges results show a high level of correlation, and 3D-DIC is proven to be an effective method to measure 3D full-field dynamic response of structures under underwater impact loading. The effects of pre-notches on the failure modes of thin circular plate were also discussed.

Experimental and Numerical Investigations on Deformation of Cylindrical Shell Panels to Underwater Explosion

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K. Ramajeyathilagam

2001-01-01

Full Text Available Experimental and numerical investigations on cylindrical shell panels subjected to underwater explosion loading are presented. Experiments were conducted on panels of size 0.8 × 0.6 × 0.00314 m and shell rise-to-span ratios h/l = 0.0, 0.05, 0.1 , using a box model set-up under air backed conditions in a shock tank. Small charges of PEK I explosive were employed. The plastic deformation of the panels was measured for three loading conditions. Finite element analysis was carried out using the CSA/GENSA [DYNA3D] software to predict the plastic deformation for various loading conditions. The analysis included material and geometric non-linearities, with strain rate effects incorporated based on the Cowper-Symonds relation. The numerical results for plastic deformation are compared with those from experiments.

Hydrodynamics of Explosion Experiments and Models

CERN Document Server

Kedrinskii, Valery K

2005-01-01

Hydronamics of Explosion presents the research results for the problems of underwater explosions and contains a detailed analysis of the structure and the parameters of the wave fields generated by explosions of cord and spiral charges, a description of the formation mechanisms for a wide range of cumulative flows at underwater explosions near the free surface, and the relevant mathematical models. Shock-wave transformation in bubbly liquids, shock-wave amplification due to collision and focusing, and the formation of bubble detonation waves in reactive bubbly liquids are studied in detail. Particular emphasis is placed on the investigation of wave processes in cavitating liquids, which incorporates the concepts of the strength of real liquids containing natural microinhomogeneities, the relaxation of tensile stress, and the cavitation fracture of a liquid as the inversion of its two-phase state under impulsive (explosive) loading. The problems are classed among essentially nonlinear processes that occur unde...

Transient Interaction of a Spherical Shell with an Underwater Explosion Shock Wave and Subsequent Pulsating Bubble

Directory of Open Access Journals (Sweden)

H. Huang

1995-01-01

Full Text Available The nonlinear interaction problem is analyzed by simultaneously solving the mass, momentum, and energy conservation equations together .with appropriate material constitutive equations governing the fluid dynamics of the explosion gaseous product and the water and the structural dynamics of the compliant shell. A finite difference technique in a coupled Eulerian–Lagrangian scheme is used. The computer program PISCES 2DELK is employed to carry out the numerical computations. The results demonstrate that to rigorously analyze the response of a submerged structure to a nearby explosion, the interactions among the explosion shock wave, the structure, its surrounding media, and the explosion bubble need to be considered.

Surface Ship Shock Modeling and Simulation: Two-Dimensional Analysis

Directory of Open Access Journals (Sweden)

Young S. Shin

1998-01-01

Full Text Available The modeling and simulation of the response of a surface ship system to underwater explosion requires an understanding of many different subject areas. These include the process of underwater explosion events, shock wave propagation, explosion gas bubble behavior and bubble-pulse loading, bulk and local cavitation, free surface effect, fluid-structure interaction, and structural dynamics. This paper investigates the effects of fluid-structure interaction and cavitation on the response of a surface ship using USA-NASTRAN-CFA code. First, the one-dimensional Bleich-Sandler model is used to validate the approach, and second, the underwater shock response of a two-dimensional mid-section model of a surface ship is predicted with a surrounding fluid model using a constitutive equation of a bilinear fluid which does not allow transmission of negative pressures.

Influence of water conductivity on shock waves generated by underwater electrical wire explosion

Science.gov (United States)

Liu, Ben; Wang, Deguo; Guo, Yanbao

2018-01-01

The new application of electrical explosion of wire (EEW) used in petroleum industry is to enhance oil recovery (EOR). Because of the complex environment underground, the effect of underground water conductivity on EEW should be considered. This work describes the effect of water conductivities on discharge current, voltage and shock waves. It was found that the effect of water conductivity contains two parts. One is the shunt effect of saline water, which can be considered as a parallel load with the copper wire between the electrodes connected to the discharge circuit. The peak pressure of shock waves are gradually decrease with the increase of water conductivity. The other is the current loss through saline water directly to the ground ends without flowing through the electrodes. The shunt effect is the main factor affecting the wire discharge process. As the charging voltage increased, the energy loss caused by these two parts are all reduced. These indicate that increasing the charging voltage to a certain value will increase the energy efficiency to generate a more powerful shock waves in conductive water.

Quasi-isentropic compression using compressed water flow generated by underwater electrical explosion of a wire array

Science.gov (United States)

Gurovich, V.; Virozub, A.; Rososhek, A.; Bland, S.; Spielman, R. B.; Krasik, Ya. E.

2018-05-01

A major experimental research area in material equation-of-state today involves the use of off-Hugoniot measurements rather than shock experiments that give only Hugoniot data. There is a wide range of applications using quasi-isentropic compression of matter including the direct measurement of the complete isentrope of materials in a single experiment and minimizing the heating of flyer plates for high-velocity shock measurements. We propose a novel approach to generating quasi-isentropic compression of matter. Using analytical modeling and hydrodynamic simulations, we show that a working fluid composed of compressed water, generated by an underwater electrical explosion of a planar wire array, might be used to efficiently drive the quasi-isentropic compression of a copper target to pressures ˜2 × 1011 Pa without any complex target designs.

Experimental Study on Peak Pressure of Shock Waves in Quasi-Shallow Water

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Zhenxiong Wang

2015-01-01

Full Text Available Based on the similarity laws of the explosion, this research develops similarity requirements of the small-scale experiments of underwater explosions and establishes a regression model for peak pressure of underwater shock waves under experimental condition. Small-scale experiments are carried out with two types of media at the bottom of the water and for different water depths. The peak pressure of underwater shock waves at different measuring points is acquired. A formula consistent with the similarity law of explosions is obtained and an analysis of the regression precision of the formula confirms its accuracy. Significance experiment indicates that the influence of distance between measuring points and charge on peak pressure of underwater shock wave is the greatest and that of water depth is the least within the range of geometric parameters. An analysis of data from experiments with different media at the bottom of the water reveals an influence on the peak pressure, as the peak pressure of a shock wave in a body of water with a bottom soft mud and rocks is about 1.33 times that of the case where the bottom material is only soft mud.

Shock Initiation of Damaged Explosives

Energy Technology Data Exchange (ETDEWEB)

Chidester, S K; Vandersall, K S; Tarver, C M

2009-10-22

Explosive and propellant charges are subjected to various mechanical and thermal insults that can increase their sensitivity over the course of their lifetimes. To quantify this effect, shock initiation experiments were performed on mechanically and thermally damaged LX-04 (85% HMX, 15% Viton by weight) and PBX 9502 (95% TATB, 5% Kel-F by weight) to obtain in-situ manganin pressure gauge data and run distances to detonation at various shock pressures. We report the behavior of the HMX-based explosive LX-04 that was damaged mechanically by applying a compressive load of 600 psi for 20,000 cycles, thus creating many small narrow cracks, or by cutting wedge shaped parts that were then loosely reassembled, thus creating a few large cracks. The thermally damaged LX-04 charges were heated to 190 C for long enough for the beta to delta solid - solid phase transition to occur, and then cooled to ambient temperature. Mechanically damaged LX-04 exhibited only slightly increased shock sensitivity, while thermally damaged LX-04 was much more shock sensitive. Similarly, the insensitive explosive PBX 9502 was mechanically damaged using the same two techniques. Since PBX 9502 does not undergo a solid - solid phase transition but does undergo irreversible or 'rachet' growth when thermally cycled, thermal damage to PBX 9502 was induced by this procedure. As for LX-04, the thermally damaged PBX 9502 demonstrated a greater shock sensitivity than mechanically damaged PBX 9502. The Ignition and Growth reactive flow model calculated the increased sensitivities by igniting more damaged LX-04 and PBX 9502 near the shock front based on the measured densities (porosities) of the damaged charges.

Limiting Performance Analysis of Underwater Shock Isolation of a System with Biodynamic Response Using Genetic Algorithm

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Z. Zong

2000-01-01

Full Text Available Biodynamic response of shipboard crew to underwater shock is of a major concern to navies. An underwater shock can produce very high accelerations, resulting in severe human injuries aboard a battleship. Protection of human bodies from underwater shock is implemented by installing onboard isolators. In this paper, the optimal underwater shock isolation to protect human bodies is studied. A simple shock-structure-isolator-human interaction model is first constructed. The model incorporates the effect of fluid-structure interaction, biodynamic response of human body, isolator influence. Based on this model, the optimum shock isolation is then formulated. The performance index and restriction are defined. Thirdly, GA (genetic algorithm is employed to solve the formulated optimization problem. GA is a powerful evolutionary optimization scheme suitable for large-scale and multi-variable optimization problems that are otherwise hard to be solved by conventional methods. A brief introduction to GA is given in the paper. Finally, the method is applied to an example problem and the limiting performance characteristic is obtained.

Multi-layer protective armour for underwater shock wave mitigation

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Ahmed Hawass

2015-12-01

The strain gauge data and displacement sensors results showed that the multi-layer plates have higher level of underwater shock wave mitigation than the triple aluminum plates with strain and deflection of nearly 50%.

Shock waves & explosions

CERN Document Server

Sachdev, PL

2004-01-01

Understanding the causes and effects of explosions is important to experts in a broad range of disciplines, including the military, industrial and environmental research, aeronautic engineering, and applied mathematics. Offering an introductory review of historic research, Shock Waves and Explosions brings analytic and computational methods to a wide audience in a clear and thorough way. Beginning with an overview of the research on combustion and gas dynamics in the 1970s and 1980s, the author brings you up to date by covering modeling techniques and asymptotic and perturbative methods and ending with a chapter on computational methods.Most of the book deals with the mathematical analysis of explosions, but computational results are also included wherever they are available. Historical perspectives are provided on the advent of nonlinear science, as well as on the mathematical study of the blast wave phenomenon, both when visualized as a point explosion and when simulated as the expansion of a high-pressure ...

Spatiotemporal dynamics of underwater conical shock wave focusing

Czech Academy of Sciences Publication Activity Database

Hoffer, Petr; Lukeš, Petr; Akiyama, H.; Hosseini, H.

2017-01-01

Roč. 27, č. 4 (2017), s. 685-690 ISSN 0938-1287 Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100431203 Program:M Institutional support: RVO:61389021 Keywords : Underwater shock wave focusing * multichannel * electrohydraulic discharge * conical shock wave reflection * medical application Subject RIV: BI - Acoustics OBOR OECD: Applied mechanics Impact factor: 1.107, year: 2016 https://link.springer.com/article/10.1007/s00193-016-0703-7

Effects of explosion-generated shock waves in ducts

International Nuclear Information System (INIS)

Busby, M.R.; Kahn, J.E.; Belk, J.P.

1976-01-01

An explosion in a space causes an increase in temperature and pressure. To quantify the challenge that will be presented to essential components in a ventilation system, it is necessary to analyze the dynamics of a shock wave generated by an explosion, with attention directed to the propagation of such a wave in a duct. Using the equations of unsteady flow and shock tube theory, a theoretical model has been formulated to provide flow properties behind moving shock waves that have interacted with various changes in duct geometry. Empirical equations have been derived to calculate air pressure, temperature, Mach number, and velocity in a duct following an explosion

Fluid-Structure Interaction Mechanisms for Close-In Explosions

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Andrew B. Wardlaw Jr.

2000-01-01

Full Text Available This paper examines fluid-structure interaction for close-in internal and external underwater explosions. The resulting flow field is impacted by the interaction between the reflected explosion shock and the explosion bubble. This shock reflects off the bubble as an expansion that reduces the pressure level between the bubble and the target, inducing cavitation and its subsequent collapse that reloads the target. Computational examples of several close-in interaction cases are presented to document the occurrence of these mechanisms. By comparing deformable and rigid body simulations, it is shown that cavitation collapse can occur solely from the shock-bubble interaction without the benefit of target deformation. Addition of a deforming target lowers the flow field pressure, facilitates cavitation and cavitation collapse, as well as reducing the impulse of the initial shock loading.

''Water bath'' effect during the electrical underwater wire explosion

International Nuclear Information System (INIS)

Oreshkin, V. I.; Chaikovsky, S. A.; Ratakhin, N. A.; Grinenko, A.; Krasik, Ya. E.

2007-01-01

The results of a simulation of underwater electrical wire explosion at a current density >10 9 A/cm 2 , total discharge current of ∼3 MA, and rise time of the current of ∼100 ns are presented. The electrical wire explosion was simulated using a one-dimensional radiation-magnetohydrodynamic model. It is shown that the radiation of the exploded wire produces a thin conducting plasma shell in the water in the vicinity of the exploding wire surface. It was found that this plasma shell catches up to 30% of the discharge current. Nevertheless, it was shown that the pressure and temperature of the wire material remain unchanged as compared with the idealized case of the electrical wire explosion in vacuum. This result is explained by a 'water bath' effect

The Effectof Underwater Explosion on the Kinetics of Alkaline Leaching of Roasted Tungsten Carbide Scraps for Recycling

OpenAIRE

BAIK, Seung Woo; SHIBAYAMA, Atsushi; MURATA, Kenji; FUJITA, Toyohisa

2004-01-01

Wasted tungsten scraps are important resources for recycling, however, the mechanical recycle process of tungsten has a difficulty for recycling due to its mechanical strength. Underwater explosion fracturing technique was designed for solving this problem. The kinetics for alkaline leaching of roasted tungsten alloy scraps with different size distribution prepared by two ways of crushing technique has been investigated to evaluate the effect of the underwater explosion-crushing. The merit of...

Explosive volcanism, shock metamorphism and the K-T boundary

International Nuclear Information System (INIS)

Desilva, S.L.; Sharpton, V.L.

1988-01-01

The issue of whether shocked quartz can be produced by explosive volcanic events is important in understanding the origin of the K-T boundary constituents. Proponents of a volcanic origin for the shocked quartz at the K-T boundary cite the suggestion of Rice, that peak overpressures of 1000 kbars can be generated during explosive volcanic eruptions, and may have occurred during the May, 1980 eruption of Mt. St. Helens. Attention was previously drawn to the fact that peak overpressures during explosive eruptions are limited by the strength of the rock confining the magma chamber to less than 8 kbars even under ideal conditions. The proposed volcanic mechanisms for generating pressures sufficient to shock quartz are further examined. Theoretical arguments, field evidence and petrographic data are presented showing that explosive volcanic eruptions cannot generate shock metamorphic features of the kind seen in minerals at the K-T boundary

Research on Initiation Sensitivity of Solid Explosive and Planer Initiation System

OpenAIRE

N Matsuo; M Otuka; H Hamasima; K Hokamoto; S Itoh

2016-01-01

Firstly, recently, there are a lot of techniques being demanded for complex process, various explosive initiation method and highly accurate control of detonation are needed. In this research, the metal foil explosion using high current is focused attention on the method to obtain linear or planate initiation easily, and the main evaluation of metal foil explosion to initiate explosive was conducted. The explosion power was evaluated by observing optically the underwater shock wave generated ...

Phase velocity enhancement of linear explosive shock tubes

Science.gov (United States)

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.

Algorithm describing pressure distribution of non-contact TNT explosion

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Radosław Kiciński

2014-12-01

Full Text Available [b]Abstract[/b]. The aim of this study is to develop a computational algorithm, describing the shock wave pressure distribution in the space induced by non-contact TNT explosion. The procedure describes pressure distribution on a damp surface of the hull. Simulations have been carried out using Abaqus/CAE. The study also shows the pressure waveform descriptions provided by various authors and presents them in charts. The formulated conclusions convince efficiency of the algorithm application.[b]Keywords:[/b] Underwater explosion, shock wave, CAE, TNT, Kobben class submarine

Application of holographic interferometric studies of underwater shock-wave focusing to medicine

Science.gov (United States)

Takayama, Kazuyoshi; Nagoya, H.; Obara, Tetsuro; Kuwahara, M.

1993-01-01

Holographic interferometric flow visualization was successfully applied to underwater shock wave focusing and its application to extracorporeal shock wave lithotripsy (ESWL). Real time diffuse holograms revealed the shock wave focusing process in an ellipsoidal reflector made from PMMA and double exposure holographic interferometry also clarified quantitatively the shock focusing process. Disintegration of urinary tract stones and gallbladder stones was observed by high speed photogrammetry. Tissue damage associated with the ESWL treatment is discussed in some detail.

Hydroelastic behaviour of a structure exposed to an underwater explosion.

Science.gov (United States)

Colicchio, G; Greco, M; Brocchini, M; Faltinsen, O M

2015-01-28

The hydroelastic interaction between an underwater explosion and an elastic plate is investigated num- erically through a domain-decomposition strategy. The three-dimensional features of the problem require a large computational effort, which is reduced through a weak coupling between a one-dimensional radial blast solver, which resolves the blast evolution far from the boundaries, and a three-dimensional compressible flow solver used where the interactions between the compression wave and the boundaries take place and the flow becomes three-dimensional. The three-dimensional flow solver at the boundaries is directly coupled with a modal structural solver that models the response of the solid boundaries like elastic plates. This enables one to simulate the fluid-structure interaction as a strong coupling, in order to capture hydroelastic effects. The method has been applied to the experimental case of Hung et al. (2005 Int. J. Impact Eng. 31, 151-168 (doi:10.1016/j.ijimpeng.2003.10.039)) with explosion and structure sufficiently far from other boundaries and successfully validated in terms of the evolution of the acceleration induced on the plate. It was also used to investigate the interaction of an underwater explosion with the bottom of a close-by ship modelled as an orthotropic plate. In the application, the acoustic phase of the fluid-structure interaction is examined, highlighting the need of the fluid-structure coupling to capture correctly the possible inception of cavitation. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Spectral analysis of underwater explosions in the Dead Sea

Science.gov (United States)

Gitterman, Y.; Ben-Avraham, Z.; Ginzburg, A.

1998-08-01

The present study utilizes the Israel Seismic Network (ISN) as a spatially distributed multichannel system for the discrimination of low-magnitude events (ML UWEs) and 16 earthquakes in the magnitude range ML = 1.6-2.8, within distances of 10-150 km, recorded by the ISN, were selected for the analysis. The analysis is based on a smoothed (0.5 Hz window) Fourier spectrum of the whole signal (defined by the signal-to-noise criterion), without picking separate wave phases. It was found that the classical discriminant of the seismic energy ratio between the relatively low-frequency (1-6 Hz) and high-frequency (6-11 Hz) bands, averaged over an ISN subnetwork, showed an overlap between UWEs and earthquakes and cannot itself provide reliable identification. We developed and tested a new multistation discriminant based on the low- frequency spectral modulation (LFSM) method. In our case the LFSM is associated with the bubbling effect in underwater explosions. The method demonstrates a distinct azimuth-invariant coherency of spectral shapes in the low-frequency range (1-12 Hz) of short-period seismometer systems. The coherency of the modulated spectra for different ISN stations was measured by semblance statistics commonly used in seismic prospecting for phase correlation in the time domain. The modified statistics provided an almost complete separation between earthquakes and underwater explosions.

The fracture of concrete under explosive shock loading

International Nuclear Information System (INIS)

Watson, A.J.; Sanderson, A.J.

1982-01-01

Concrete fracture close to the point of application of high explosive shock pressures has been studied experimentally by placing an explosive charge on the edge of a concrete slab. The extent of the crushing and cracking produced by a semi cylindrical diverging plane compressive stress pulse has been measured and complementary experiments gave the pressure transmitted at an explosive to concrete interface and the stress-strain relation for concrete at explosive strain rates. (orig.) [de

Experimental Research on the Dynamic Response of Floating Structures with Coatings Subjected to Underwater Explosion

Directory of Open Access Journals (Sweden)

Feng Xiao

2014-01-01

Full Text Available This paper presents an experimental investigation into the dynamic response of three free floating stiffened metal boxes with protective coatings subjected to underwater explosion (UNDEX. One box was kept intact while the other two were, respectively, covered with monolithic coatings and chiral honeycomb coatings. Three groups of live fire tests with different attack angles and stand-off distances were conducted. The acceleration on the stiffener and strain peak on the bottom hull were selected as the major comparative criterions. Test results show that the impulse transmitted to the structure at the initial stage can be reduced, owing to the coating flexibility and fluid-structure interaction mechanism. Consequently, the acceleration peaks induced by both shock wave and bubble pulse were reduced. The shock environment can be more effectively improved by honeycomb coating when compared with monolithic coating. Most of the strain peaks decreased to a certain extent, but some of them were notably manifested, especially for honeycomb coating. The test affirms the fact that soft coating can cause stress concentration on the shell that is in direct contact with the coating due to the impedance mismatch between the interfaces of materials. A softer rubber coating induces a greater magnitude of strain.

Review of potential impacts to sea turtles from underwater explosive removal of offshore structures

International Nuclear Information System (INIS)

Viada, Stephen T.; Hammer, Richard M.; Racca, Roberto; Hannay, David; Thompson, M. John; Balcom, Brian J.; Phillips, Neal W.

2008-01-01

The purpose of this study was to collect and synthesize existing information relevant to the explosive removal of offshore structures (EROS) in aquatic environments. Data sources were organized and summarized by topic - explosive removal methods, physics of underwater explosions, sea turtle resources, documented impacts to sea turtles, and mitigation of effects. Information was gathered via electronic database searches and literature source review. Bulk explosive charges are the most commonly used technique in EROS. While the physical principles of underwater detonations and the propagation of pressure and acoustic waves are well understood, there are significant gaps in the application of this knowledge. Impacts to sea turtles from explosive removal operations may range from non-injurious effects (e.g. acoustic annoyance; mild tactile detection or physical discomfort) to varying levels of injury (i.e. non-lethal and lethal injuries). Very little information exists regarding the impacts of underwater explosions on sea turtles. Effects of explosions on turtles often must be inferred from documented effects to other vertebrates with lungs or other gas-containing organs, such as mammals and most fishes. However, a cautious approach should be used when determining impacts to sea turtles based on extrapolations from other vertebrates. The discovery of beached sea turtles and bottlenose dolphins following an explosive platform removal event in 1986 prompted the initiation of formal consultation between the U.S. Department of the Interior, Minerals Management Service (MMS) and the National Marine Fisheries Service (NMFS), authorized through the Endangered Species Act Section 7, to determine a mechanism to minimize potential impacts to listed species. The initial consultation resulted in a requirement for oil and gas companies to obtain a permit (through separate consultations on a case-by-case basis) prior to using explosives in Federal waters. Because many offshore

Explicit Modeling of Solid Ocean Floor in Shallow Underwater Explosions

Directory of Open Access Journals (Sweden)

A.P. Walters

2013-01-01

Full Text Available Current practices for modeling the ocean floor in underwater explosion simulations call for application of an inviscid fluid with soil properties. A method for modeling the ocean floor as a Lagrangian solid, vice an Eulerian fluid, was developed in order to determine its effects on underwater explosions in shallow water using the DYSMAS solver. The Lagrangian solid bottom model utilized transmitting boundary segments, exterior nodal forces acting as constraints, and the application of prestress to minimize any distortions into the fluid domain. For simplicity, elastic materials were used in this current effort, though multiple constitutive soil models can be applied to improve the overall accuracy of the model. Even though this method is unable to account for soil cratering effects, it does however provide the distinct advantage of modeling contoured ocean floors such as dredged channels and sloped bottoms absent in Eulerian formulations. The study conducted here showed significant differences among the initial bottom reflections for the different solid bottom contours that were modeled. The most important bottom contour effect was the distortion to the gas bubble and its associated first pulse timing. In addition to its utility in bottom modeling, implementation of the non-reflecting boundary along with realistic material models can be used to drastically reduce the size of current fluid domains.

Shock Initiation of Wedge-shaped Explosive Measured with Smear Camera and Photon Doppler Velocimetry

Science.gov (United States)

Gu, Yan

2017-06-01

Triaminotrinitrobenzene (TATB) is an important insensitive high explosive in conventional weapons due to its safety and high energy. In order to have an insight into the shock initiation performance of a TATB-based insensitive high explosive (IHE), experimental measurements of the particle velocity histories of the TATB-based Explosive using Photon Doppler Velocimetry and shock wave profile of the TATB-based explosive using High Speed Rotating Mirror Smear Camera had been performed. In this paper, we would describe the shock initiation performance of the TATB-based explosive by run-to-detonation distance and the particle velocity history at an initialization shock of about 7.9 GPa. The parameters of hugoniot of unreacted the TATB-based explosive and Pop relationship could be derived with the particle velocity history obtained in this paper.

Ground Shock Effects from Accidental Explosions

Science.gov (United States)

1976-11-01

1,200 P0 A = V P cp 8 Horizontal Dh = Dv tannin " 1 (cp/U)] Vh = Vv tan [sin" 1 (cp/U)] \\ - \\ tanfainŕ (cp/U)] For tan sin (c /U...explosive are not included in the present analysis . This effect will limit the credibility of the direct- induced ground shock predictions, but if the... analysis . Dr. D. R. Richmond of Lovelace Foundation provided data on human shock tolerances. 26 REFERENCES 1. "Structures to Resist the Effects of

Evaluation of XHVRB for Capturing Explosive Shock Desensitization

Science.gov (United States)

Tuttle, Leah; Schmitt, Robert; Kittell, Dave; Harstad, Eric

2017-06-01

Explosive shock desensitization phenomena have been recognized for some time. It has been demonstrated that pressure-based reactive flow models do not adequately capture the basic nature of the explosive behavior. Historically, replacing the local pressure with a shock captured pressure has dramatically improved the numerical modeling approaches. Models based upon shock pressure or functions of entropy have recently been developed. A pseudo-entropy based formulation using the History Variable Reactive Burn model, as proposed by Starkenberg, was implemented into the Eulerian shock physics code CTH. Improvements in the shock capturing algorithm were made. The model is demonstrated to reproduce single shock behavior consistent with published pop plot data. It is also demonstrated to capture a desensitization effect based on available literature data, and to qualitatively capture dead zones from desensitization in 2D corner turning experiments. This models shows promise for use in modeling and simulation problems that are relevant to the desensitization phenomena. Issues are identified with the current implementation and future work is proposed for improving and expanding model capabilities. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Evaluation of Accelerometer Mechanical Filters on Submerged Cylinders Near an Underwater Explosion

Directory of Open Access Journals (Sweden)

G. Yiannakopoulos

1998-01-01

Full Text Available An accelerometer, mounted to a structure near an explosion to measure elasto-plastic deformation, can be excited at its resonant frequency by impulsive stresses transmitted within the structure. This results in spurious high peak acceleration levels that can be much higher than acceleration levels from the explosion itself. The spurious signals also have higher frequencies than the underlying signal from the explosion and can be removed by a low pass filter. This report assesses the performance of four accelerometer and filter assemblies. The assessment involves measurements of the response of a mild steel cylinder to an underwater explosion, in which each assembly is mounted onto the interior surface of the cylinder. Three assemblies utilise a piezoresistive accelerometer in which isolation is provided mechanically. In the fourth assembly, a piezoelectric accelerometer, with a built-in filter, incorporates both mechanical and electronic filtering. This assembly is found to be more suitable because of its secure mounting arrangement, ease of use, robustness and noise free results.

Research on Initiation Sensitivity of Solid Explosive and Planer Initiation System

Directory of Open Access Journals (Sweden)

N Matsuo

2016-09-01

Full Text Available Firstly, recently, there are a lot of techniques being demanded for complex process, various explosive initiation method and highly accurate control of detonation are needed. In this research, the metal foil explosion using high current is focused attention on the method to obtain linear or planate initiation easily, and the main evaluation of metal foil explosion to initiate explosive was conducted. The explosion power was evaluated by observing optically the underwater shock wave generated from the metal foil explosion. Secondly, in high energy explosive processing, there are several applications, such as shock compaction, explosive welding, food processing and explosive forming. In these explosive applications, a high sensitive explosive has been mainly used. The high sensitive explosive is so dangerous, since it can lead to explosion suddenly. So, for developing explosives, the safety is the most important thing as well as low manufacturing cost and explosive characteristics. In this work, we have focused on the initiation sensitivity of a solid explosive and performed numerical analysis of sympathetic detonation. The numerical analysis is calculated by LS-DYNA 3D (commercial code. To understand the initiation reaction of an explosive, Lee-Tarver equation was used and impact detonation process was analyzed by ALE code. Configuration of simulation model is a quarter of circular cylinder. The donor type of explosive (SEP was used as initiation explosive. When the donor explosive is exploded, a shock wave is generated and it propagates into PMMA, air and metallic layers in order. During passing through the layers, the shock wave is attenuated and finally, it has influence on the acceptor explosive, Comp. B. Here, we evaluate the initiation of acceptor explosive and discuss about detonation pressure, reactive rate of acceptor explosive and attenuation of impact pressure.

Development of fiber optic sensors at TNO for explosion and shock wave measurements

NARCIS (Netherlands)

Cheng, L.K.; Smorenburg, C.; Bree, J.L.M.J. van; Bouma, R.H.B.; Meer, B.J. van der; Prinse, W.C.; Scholtes, J.H.G.

2000-01-01

Fiber Optic sensors are found to be very suitable for explosion and shock wave measurements because they are immune to Electromagnetic Interference (EMI). In the past few years, TNO has developed a number of sensor systems for explosion and shock wave measurements in which the optical fiber is a

Spherical shock due to point explosion with varying energy

Science.gov (United States)

Singh, J. B.; Srivastava, S. K.

1983-05-01

The motion of a perfect gas behind a weak or strong spherical point-explosion shock wave in a nonuniform rest atmosphere is investigated analytically for the case of variable flow energy. The self-similar solutions derived are also adaptable to a uniform expanding piston. The solution is applied to the isothermal case, and the results of numerical integration are presented in graphs showing the density, velocity, and pressure distributions for different values of delta. The findings are considered significant for investigations of sonic booms, laser production of plasmas, high-altitude nuclear detonations, supernova explosions, and the sudden expansion of the solar corona, and for the laboratory production of high temperatures using shock waves.

Bioeffects on an In Vitro Model by Small-Scale Explosives and Shock Wave Overpressure Impacts

Science.gov (United States)

2017-11-01

Many TBIs are associated with blast from improvised explosive devices.2–4 Explosions are physical, chemical , or nuclear reactions involving a rapid...ARL-TR-8210 ● NOV 2017 US Army Research Laboratory Bioeffects on an In Vitro Model by Small-Scale Explosives and Shock Wave...Research Laboratory Bioeffects on an In Vitro Model by Small-Scale Explosives and Shock Wave Overpressure Impacts by Nicole E Zander, Thuvan

Modeling Hot-Spot Contributions in Shocked High Explosives at the Mesoscale

Energy Technology Data Exchange (ETDEWEB)

Harrier, Danielle [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-08-12

When looking at performance of high explosives, the defects within the explosive become very important. Plastic bonded explosives, or PBXs, contain voids of air and bonder between the particles of explosive material that aid in the ignition of the explosive. These voids collapse in high pressure shock conditions, which leads to the formation of hot spots. Hot spots are localized high temperature and high pressure regions that cause significant changes in the way the explosive material detonates. Previously hot spots have been overlooked with modeling, but now scientists are realizing their importance and new modeling systems that can accurately model hot spots are underway.

Underwater hydraulic shock shovel control system

Science.gov (United States)

Liu, He-Ping; Luo, A.-Ni; Xiao, Hai-Yan

2008-06-01

The control system determines the effectiveness of an underwater hydraulic shock shovel. This paper begins by analyzing the working principles of these shovels and explains the importance of their control systems. A new type of control system’s mathematical model was built and analyzed according to those principles. Since the initial control system’s response time could not fulfill the design requirements, a PID controller was added to the control system. System response time was still slower than required, so a neural network was added to nonlinearly regulate the proportional element, integral element and derivative element coefficients of the PID controller. After these improvements to the control system, system parameters fulfilled the design requirements. The working performance of electrically-controlled parts such as the rapidly moving high speed switch valve is largely determined by the control system. Normal control methods generally can’t satisfy a shovel’s requirements, so advanced and normal control methods were combined to improve the control system, bringing good results.

Shock-induced explosive chemistry in a deterministic sample configuration.

Energy Technology Data Exchange (ETDEWEB)

Stuecker, John Nicholas; Castaneda, Jaime N.; Cesarano, Joseph, III (,; ); Trott, Wayne Merle; Baer, Melvin R.; Tappan, Alexander Smith

2005-10-01

Explosive initiation and energy release have been studied in two sample geometries designed to minimize stochastic behavior in shock-loading experiments. These sample concepts include a design with explosive material occupying the hole locations of a close-packed bed of inert spheres and a design that utilizes infiltration of a liquid explosive into a well-defined inert matrix. Wave profiles transmitted by these samples in gas-gun impact experiments have been characterized by both velocity interferometry diagnostics and three-dimensional numerical simulations. Highly organized wave structures associated with the characteristic length scales of the deterministic samples have been observed. Initiation and reaction growth in an inert matrix filled with sensitized nitromethane (a homogeneous explosive material) result in wave profiles similar to those observed with heterogeneous explosives. Comparison of experimental and numerical results indicates that energetic material studies in deterministic sample geometries can provide an important new tool for validation of models of energy release in numerical simulations of explosive initiation and performance.

Basic study on promotion of thawing frozen soil by shock loading

Directory of Open Access Journals (Sweden)

Toshiaki WATANABE

2008-06-01

Full Text Available The aim of study is to confirm a new technique that can crush the frozen soil and/or ice block using underwater shock wave generated by the underwater explosion of explosive. This technique can lead to the earlier sowing, which can have the larger harvest because the duration of sunshine increases. Especially, in Hokkaido prefecture, Japan, if the sowing is carried out in April, we can expect to have 150% of harvest in the ordinary season. In the case of small processing area such as road repairing, frozen soil is thawed by using the heat of gas burner and/or the electric heater. It is not a suitable plan to apply these heating methods to agriculture, from the point of view enormous amount of processing area. Thawing technique for frozen soil is effective against the cold regions, for example, Russia, Norway, and Sweden, etc. At first, we carried out experiments using a detonating fuse and ice block. The propagation process of shock wave into the ice block was observed by means of a high-speed camera. In order to check about that influence we tried to give an actual frozen soil a shock wave. We could get a result that existence of water layer serves an important role in promotion of thawing by the shock loading to the frozen soil.

Convergence of shock waves between conical and parabolic boundaries

Energy Technology Data Exchange (ETDEWEB)

Yanuka, D.; Zinowits, H. E.; Antonov, O.; Efimov, S.; Virozub, A.; Krasik, Ya. E. [Physics Department, Technion, Haifa 32000 (Israel)

2016-07-15

Convergence of shock waves, generated by underwater electrical explosions of cylindrical wire arrays, between either parabolic or conical bounding walls is investigated. A high-current pulse with a peak of ∼550 kA and rise time of ∼300 ns was applied for the wire array explosion. Strong self-emission from an optical fiber placed at the origin of the implosion was used for estimating the time of flight of the shock wave. 2D hydrodynamic simulations coupled with the equations of state of water and copper showed that the pressure obtained in the vicinity of the implosion is ∼7 times higher in the case of parabolic walls. However, comparison with a spherical wire array explosion showed that the pressure in the implosion vicinity in that case is higher than the pressure in the current experiment with parabolic bounding walls because of strong shock wave reflections from the walls. It is shown that this drawback of the bounding walls can be significantly minimized by optimization of the wire array geometry.

Understanding the shock and detonation response of high explosives at the continuum and meso scales

Science.gov (United States)

Handley, C. A.; Lambourn, B. D.; Whitworth, N. J.; James, H. R.; Belfield, W. J.

2018-03-01

The shock and detonation response of high explosives has been an active research topic for more than a century. In recent years, high quality data from experiments using embedded gauges and other diagnostic techniques have inspired the development of a range of new high-fidelity computer models for explosives. The experiments and models have led to new insights, both at the continuum scale applicable to most shock and detonation experiments, and at the mesoscale relevant to hotspots and burning within explosive microstructures. This article reviews the continuum and mesoscale models, and their application to explosive phenomena, gaining insights to aid future model development and improved understanding of the physics of shock initiation and detonation propagation. In particular, it is argued that "desensitization" and the effect of porosity on high explosives can both be explained by the combined effect of thermodynamics and hydrodynamics, rather than the traditional hotspot-based explanations linked to pressure-dependent reaction rates.

The simplified interaction tool for efficient and accurate underwater shock analysis of naval ships

NARCIS (Netherlands)

Aanhold, J.E. van; Trouwborst, W.; Vaders, J.A.A.

2014-01-01

In order to satisfy the need for good quality UNDEX response estimates of naval ships, TNO developed the Simplified Interaction Tool (SIT) for underwater shock analysis. The SIT is a module of user routines linked to LS-DYNA, which generates the UNDEX loading on the wet hull of a 3D finite element

Experimental response of an optical sensor used to determine the moment of blast by sensing the flash of the explosion

CSIR Research Space (South Africa)

Roux, A

2009-09-01

Full Text Available of an optical sensor constructed to measure the light flash of an underwater blast to determine the moment of explosion. By measurement of the time taken between this moment and the time when the shock wave reaches the pressure sensors, accurate measurements...

Relating pressure measurements to phenomena observed in high speed video recordings during tests of explosive charges in a semi-confined blast chamber

CSIR Research Space (South Africa)

Mostert, FJ

2012-09-01

Full Text Available initiation of the charge. It was observed in the video recordings that the detonation product cloud exhibited pulsating behaviour due to the reflected shocks in the chamber analogous to the behaviour of the gas bubble in underwater explosions. This behaviour...

Applications of Arbitrary Lagrangian Eulerian (ALE) Analysis Approach to Underwater and Air Explosion Problems

National Research Council Canada - National Science Library

Trevino, Theodore

2000-01-01

...) numerical technique. The investigation primarily examined the explosive-fluid, fluid-structure, and fluid-air interaction effects, and the shock wave pressure propagation through a subjected medium, with the intent...

Thermal chemical-mechanical reactive flow model of shock initiation in solid explosives

International Nuclear Information System (INIS)

Nicholls, A.L. III; Tarver, C.M.

1998-01-01

The three dimensional Arbitrary Lagrange Eulerian hydrodynamic computer code ALE3D with fully coupled thermal-chemical-mechanical material models provides the framework for the development of a physically realistic model of shock initiation and detonation of solid explosives. The processes of hot spot formation during shock compression, subsequent ignition of reaction or failure to react, growth of reaction in individual hot spots, and coalescence of reacting hot spots during the transition to detonation can now be modeled using Arrhenius chemical kinetic rate laws and heat transfer to propagate the reactive flow. This paper discusses the growth rates of reacting hot spots in HMX and TATB and their coalescence during shock to detonation transition. Hot spot deflagration rates are found to be fast enough to consume explosive particles less than 10 mm in diameter during typical shock duration times, but larger particles must fragment and create more reactive surface area in order to be rapidly consumed

Compaction shock dissipation in low density granular explosive

Energy Technology Data Exchange (ETDEWEB)

Rao, Pratap T.; Gonthier, Keith A., E-mail: gonthier@me.lsu.edu; Chakravarthy, Sunada [Mechanical and Industrial Engineering Department, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)

2016-06-14

The microstructure of granular explosives can affect dissipative heating within compaction shocks that can trigger combustion and initiate detonation. Because initiation occurs over distances that are much larger than the mean particle size, homogenized (macroscale) theories are often used to describe local thermodynamic states within and behind shocks that are regarded as the average manifestation of thermodynamic fields at the particle scale. In this paper, mesoscale modeling and simulation are used to examine how the initial packing density of granular HMX (C{sub 4}H{sub 8}N{sub 8}O{sub 8}) C{sub 4}H{sub 8}N{sub 8}O{sub 8} having a narrow particle size distribution influences dissipation within resolved, planar compaction shocks. The model tracks the evolution of thermomechanical fields within large ensembles of particles due to pore collapse. Effective shock profiles, obtained by averaging mesoscale fields over space and time, are compared with those given by an independent macroscale compaction theory that predicts the variation in effective thermomechanical fields within shocks due to an imbalance between the solid pressure and a configurational stress. Reducing packing density is shown to reduce the dissipation rate within shocks but increase the integrated dissipated work over shock rise times, which is indicative of enhanced sensitivity. In all cases, dissipated work is related to shock pressure by a density-dependent power law, and shock rise time is related to pressure by a power law having an exponent of negative one.

A mesoscopic reaction rate model for shock initiation of multi-component PBX explosives.

Science.gov (United States)

Liu, Y R; Duan, Z P; Zhang, Z Y; Ou, Z C; Huang, F L

2016-11-05

The primary goal of this research is to develop a three-term mesoscopic reaction rate model that consists of a hot-spot ignition, a low-pressure slow burning and a high-pressure fast reaction terms for shock initiation of multi-component Plastic Bonded Explosives (PBX). Thereinto, based on the DZK hot-spot model for a single-component PBX explosive, the hot-spot ignition term as well as its reaction rate is obtained through a "mixing rule" of the explosive components; new expressions for both the low-pressure slow burning term and the high-pressure fast reaction term are also obtained by establishing the relationships between the reaction rate of the multi-component PBX explosive and that of its explosive components, based on the low-pressure slow burning term and the high-pressure fast reaction term of a mesoscopic reaction rate model. Furthermore, for verification, the new reaction rate model is incorporated into the DYNA2D code to simulate numerically the shock initiation process of the PBXC03 and the PBXC10 multi-component PBX explosives, and the numerical results of the pressure histories at different Lagrange locations in explosive are found to be in good agreements with previous experimental data. Copyright © 2016 Elsevier B.V. All rights reserved.

Spallation reactions in shock waves at supernova explosions and related problems

Energy Technology Data Exchange (ETDEWEB)

Ustinova, G. K., E-mail: ustinova@dubna.net.ru [RAS, V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry (Russian Federation)

2013-05-15

The isotopic anomalies of some extinct radionuclides testify to the outburst of a nearby supernova just before the collapse of the protosolar nebula, and to the fact that the supernova was Sn Ia, i.e. the carbon-detonation supernova. A key role of spallation reactions in the formation of isotopic anomalies in the primordial matter of the Solar System is revealed. It is conditioned by the diffusive acceleration of particles in the explosive shock waves, which leads to the amplification of rigidity of the energy spectrum of particles and its enrichment with heavier ions. The quantitative calculations of such isotopic anomalies of many elements are presented. It is well-grounded that the anomalous Xe-HL in meteoritic nanodiamonds was formed simultaneously with nanodiamonds themselves during the shock wave propagation at the Sn Ia explosion. The possible effects of shock wave fractionation of noble gases in the atmosphere of planets are considered. The origin of light elements Li, Be and B in spallation reactions, predicted by Fowler in the middle of the last century, is argued. All the investigated isotopic anomalies give the evidence for the extremely high magnetohydrodynamics (MHD) conditions at the initial stage of free expansion of the explosive shock wave from Sn Ia, which can be essential in solution of the problem of origin of cosmic rays. The specific iron-enriched matter of Sn Ia and its MHD-separation in turbulent processes must be taking into account in the models of origin of the Solar System.

Shock wave convergence in water with parabolic wall boundaries

International Nuclear Information System (INIS)

Yanuka, D.; Shafer, D.; Krasik, Ya.

2015-01-01

The convergence of shock waves in water, where the cross section of the boundaries between which the shock wave propagates is either straight or parabolic, was studied. The shock wave was generated by underwater electrical explosions of planar Cu wire arrays using a high-current generator with a peak output current of ∼45 kA and rise time of ∼80 ns. The boundaries of the walls between which the shock wave propagates were symmetric along the z axis, which is defined by the direction of the exploding wires. It was shown that with walls having a parabolic cross section, the shock waves converge faster and the pressure in the vicinity of the line of convergence, calculated by two-dimensional hydrodynamic simulations coupled with the equations of state of water and copper, is also larger

In-situ Raman spectroscopy and high-speed photography of a shocked triaminotrinitrobenzene based explosive

Energy Technology Data Exchange (ETDEWEB)

Saint-Amans, C.; Hébert, P., E-mail: philippe.hebert@cea.fr; Doucet, M. [CEA, DAM, Le RIPAULT, F-37620 Monts (France); Resseguier, T. de [Institut P' , UPR CNRS 3346, ENSMA, Université de Poitiers, F-86961 Futuroscope, Chasseneuil (France)

2015-01-14

We have developed a single-shot Raman spectroscopy experiment to study at the molecular level the initiation mechanisms that can lead to sustained detonation of a triaminotrinitrobenzene-based explosive. Shocks up to 30 GPa were generated using a two-stage laser-driven flyer plate generator. The samples were confined by an optical window and shock pressure was maintained for at least 30 ns. Photon Doppler Velocimetry measurements were performed at the explosive/window interface to determine the shock pressure profile. Raman spectra were recorded as a function of shock pressure and the shifts of the principal modes were compared to static high-pressure measurements performed in a diamond anvil cell. Our shock data indicate the role of temperature effects. Our Raman spectra also show a progressive extinction of the signal which disappears around 9 GPa. High-speed photography images reveal a simultaneous progressive darkening of the sample surface up to total opacity at 9 GPa. Reflectivity measurements under shock compression show that this opacity is due to a broadening of the absorption spectrum over the entire visible region.

Shock temperature dependent rate law for plastic bonded explosives

Science.gov (United States)

Aslam, Tariq D.

2018-04-01

A reactive flow model for the tri-amino-tri-nitro-benzene (TATB) based plastic bonded explosive PBX 9502 (95% TATB, 5% polymeric binder Kel-F 800) is presented. This newly devised model is based primarily on the shock temperature of the material, along with local pressure, and accurately models a broader range of detonation and initiation scenarios. Specifically, sensitivity changes to the initial explosive temperature are accounted for naturally and with a single set of parameters. The equation of state forms for the reactants and products, as well as the thermodynamic closure of pressure and temperature equilibration, are carried over from the Wescott-Stewart-Davis (WSD) model [Wescott et al., J. Appl. Phys. 98, 053514 (2005) and "Modeling detonation diffraction and dead zones in PBX-9502," in Proceedings of the Thirteenth International Detonation Symposium (2006)]. This newly devised model, with Arrhenius state dependence on the shock temperature, based on the WSD equation of states, is denoted by AWSD. Modifying an existing implementation of the WSD model to the AWSD model in a hydrocode is a rather straightforward procedure.

Shock Hugoniot and equations of states of water, castor oil, and aqueous solutions of sodium chloride, sucrose and gelatin

Science.gov (United States)

Gojani, A. B.; Ohtani, K.; Takayama, K.; Hosseini, S. H. R.

2016-01-01

This paper reports a result of experiments for the determination of reliable shock Hugoniot curves of liquids, in particular, at relatively low pressure region, which are needed to perform precise numerical simulations of shock wave/tissue interaction prior to the development of shock wave related therapeutic devices. Underwater shock waves were generated by explosions of laser ignited 10 mg silver azide pellets, which were temporally and spatially well controlled. Measuring temporal variation of shock velocities and over-pressures in caster oil, aqueous solutions of sodium chloride, sucrose and gelatin with various concentrations, we succeeded to determine shock Hugoniot curves of these liquids and hence parameters describing Tait type equations of state.

Holographic interferometric observation of shock wave focusing to extracorporeal shock wave lithotripsy

Science.gov (United States)

Takayama, Kazuyoshi; Obara, Tetsuro; Onodera, Osamu

1991-04-01

Underwater shock wave focusing is successfully applied to disintegrate and remove kidney stones or gallbladder stones without using surgical operations. This treatment is one of the most peaceful applications ofshock waves and is named as the Extracorporeal Shock Wave Lithotripsy. Ajoint research project is going on between the Institute ofFluid Science, Tohoku University and the School ofMedicine, Tohoku University. The paper describes a result of the fundamental research on the underwater shock wave focusing applied to the ESWL. Quantitatively to visualize the underwater shock waves, various optical flow visualization techniques were successfully used such as holographic interferometry, and shadowgraphs combined with Ima-Con high speed camera. Double exposure holographic interferometric observation revealed the mechanism of generation, propagation and focusing of underwater shock waves. The result of the present research was already used to manufacture a prototype machine and it has already been applied successfully to ESWL crinical treatments. However, despite of success in the clinical treatments, important fundamental questions still remain unsolved, i.e., effects of underwater shock wave focusing on tissue damage during the treatment. Model experiments were conducted to clarify mechanism of the tissue damage associated with the ESWL. Shock-bubble interactions were found responsible to the tissue damage during the ESWL treatment. In order to interprete experimental findings and to predict shock wave behavior and high pressures, a numerical simulation was carried. The numerical results agreed with the experiments.

Impulsive shock induced single drop steam explosion visualized by high-speed x-ray radiography and photography - metallic melt

International Nuclear Information System (INIS)

Park, H. S.; Hansson, R. C.; Sehgal, B. R.

2003-01-01

Experimental investigation of fine fragmentation process during vapor explosion was conducted in a small-scale single drop system employing continuous high-speed X-ray radiography and photography. A molten tin drop of about 0.7 g at approximately 1000 .deg. C was dropped into a water pool, at temperatures ranging from 20 to 90 .deg. C, and the explosion was triggered by an external shock pulse of about 1 MPa. X-ray radiographs show that finely fragmented melt particles accelerates to the vapor bubble boundary and forms a particle shell during the period of vapor bubble expansion due to vapor explosions. From the photographs, it was possible to observe a number of counter-jets on the vapor boundary. For tests with highly subcooled coolant, local explosion due to external impulsive shock trigger initiates the stratified mode of explosion along the entire melt surface. For tests with lower subcooled coolant local explosions were initiated by an external impulsive shock trigger and by collapse of vapor/gas pocket attached on the top of the melt drop. Transient spatial distribution map of melt fragments during vapor explosion was obtained by a series of image processing and calibration tests

On the low pressure shock initiation of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine based plastic bonded explosives

Science.gov (United States)

Vandersall, Kevin S.; Tarver, Craig M.; Garcia, Frank; Chidester, Steven K.

2010-05-01

In large explosive and propellant charges, relatively low shock pressures on the order of 1-2 GPa impacting large volumes and lasting tens of microseconds can cause shock initiation of detonation. The pressure buildup process requires several centimeters of shock propagation before shock to detonation transition occurs. In this paper, experimentally measured run distances to detonation for lower input shock pressures are shown to be much longer than predicted by extrapolation of high shock pressure data. Run distance to detonation and embedded manganin gauge pressure histories are measured using large diameter charges of six octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) based plastic bonded explosives (PBX's): PBX 9404; LX-04; LX-07; LX-10; PBX 9501; and EDC37. The embedded gauge records show that the lower shock pressures create fewer and less energetic "hot spot" reaction sites, which consume the surrounding explosive particles at reduced reaction rates and cause longer distances to detonation. The experimental data is analyzed using the ignition and growth reactive flow model of shock initiation in solid explosives. Using minimum values of the degrees of compression required to ignite hot spot reactions, the previously determined high shock pressure ignition and growth model parameters for the six explosives accurately simulate the much longer run distances to detonation and much slower growths of pressure behind the shock fronts measured during the shock initiation of HMX PBX's at several low shock pressures.

AN INVESTIGATION INTO THE CHARACTER OF PRE-EXPLOSION CORE-COLLAPSE SUPERNOVA SHOCK MOTION

International Nuclear Information System (INIS)

Burrows, Adam; Dolence, Joshua C.; Murphy, Jeremiah W.

2012-01-01

We investigate the structure of the stalled supernova shock in both two and three dimensions (2D and 3D, respectively) and explore the differences in the effects of neutrino heating and the standing accretion shock instability (SASI). We find that early on the amplitude of the dipolar mode of the shock is factors of ∼2-3 smaller in 3D than in 2D. However, later in both 3D and 2D, the monopole and dipole modes start to grow until explosion. Whereas in 2D, the (l, m) = (1, 0) mode changes sign quasi-periodically, producing the 'up-and-down' motion always seen in modern 2D simulations, in 3D this almost never happens. Rather, in 3D when the dipolar mode starts to grow, it grows in magnitude and wanders stochastically in direction until settling before explosion to a particular patch of solid angle. Furthermore, in 2D, we find that the amplitude of the dipolar shock deformation separates into two classes. For the first, identified with the SASI and for a wide range of 'low' neutrino luminosities, this amplitude remains small and roughly constant. For the other, identified with higher luminosities and neutrino-driven convection, the dipolar amplitude grows sharply. Importantly, it is only for this higher luminosity class that we see neutrino-driven explosions within ∼1 s of bounce. Moreover, for the 'low' luminosity runs (including zero), the power spectra of these dipolar oscillations peak in the 30-50 Hz range associated with advection timescales, while for the high-luminosity runs the power spectra at lower frequencies are significantly more prominent. We associate this enhanced power at lower frequencies with slower convective effects and the secular growth of the dipolar shock amplitude. Though our study involves a simplified, parameterized approach, on the basis of it we hypothesize that neutrino-driven buoyant convection should almost always dominate the SASI when the supernova explosion is neutrino-driven.

Development of laser-induced grating spectroscopy for underwater temperature measurement in shock wave focusing regions

Science.gov (United States)

Gojani, Ardian B.; Danehy, Paul M.; Alderfer, David W.; Saito, Tsutomu; Takayama, Kazuyoshi

2004-02-01

In Extracorporeal Shock Wave Lithotripsy (ESWL) underwater shock wave focusing generates high pressures at very short duration of time inside human body. However, it is not yet clear how high temperatures are enhanced at the spot where a shock wave is focused. The estimation of such dynamic temperature enhancements is critical for the evaluation of tissue damages upon shock loading. For this purpose in the Interdisciplinary Shock Wave Research Center a technique is developed which employs laser induced thermal acoustics or Laser Induced Grating Spectroscopy. Unlike most of gas-dynamic methods of measuring physical quantities this provides a non-invasive one having spatial and temporal resolutions of the order of magnitude of 1.0 mm 3 and 400 ns, respectively. Preliminary experiments in still water demonstrated that this method detected sound speed and hence temperature in water ranging 283 K to 333 K with errors of 0.5%. These results are used to empirically establish the equation of states of water, gelatin or agar cell which will work as alternatives of human tissues.

Analysis of microstructure-dependent shock dissipation and hot-spot formation in granular metalized explosive

Science.gov (United States)

Chakravarthy, Sunada; Gonthier, Keith A.

2016-07-01

Variations in the microstructure of granular explosives (i.e., particle packing density, size, shape, and composition) can affect their shock sensitivity by altering thermomechanical fields at the particle-scale during pore collapse within shocks. If the deformation rate is fast, hot-spots can form, ignite, and interact, resulting in burn at the macro-scale. In this study, a two-dimensional finite and discrete element technique is used to simulate and examine shock-induced dissipation and hot-spot formation within low density explosives (68%-84% theoretical maximum density (TMD)) consisting of large ensembles of HMX (C4H8N8O8) and aluminum (Al) particles (size ˜ 60 -360 μm). Emphasis is placed on identifying how the inclusion of Al influences effective shock dissipation and hot-spot fields relative to equivalent ensembles of neat/pure HMX for shocks that are sufficiently strong to eliminate porosity. Spatially distributed hot-spot fields are characterized by their number density and area fraction enabling their dynamics to be described in terms of nucleation, growth, and agglomeration-dominated phases with increasing shock strength. For fixed shock particle speed, predictions indicate that decreasing packing density enhances shock dissipation and hot-spot formation, and that the inclusion of Al increases dissipation relative to neat HMX by pressure enhanced compaction resulting in fewer but larger HMX hot-spots. Ensembles having bimodal particle sizes are shown to significantly affect hot-spot dynamics by altering the spatial distribution of hot-spots behind shocks.

Relationship between energy deposition and shock wave phenomenon in an underwater electrical wire explosion

Science.gov (United States)

Han, Ruoyu; Zhou, Haibin; Wu, Jiawei; Qiu, Aici; Ding, Weidong; Zhang, Yongmin

2017-09-01

An experimental study of pressure waves generated by an exploding copper wire in a water medium is performed. We examined the effects of energy deposited at different stages on the characteristics of the resulting shock waves. In the experiments, a microsecond time-scale pulsed current source was used to explode a 300-μm-diameter, 4-cm-long copper wire with initial stored energies ranging from 500 to 2700 J. Our experimental results indicated that the peak pressure (4.5-8.1 MPa) and energy (49-287 J) of the shock waves did not follow a simple relationship with any electrical parameters, such as peak voltage or deposited energy. Conversely, the impulse had a quasi-linear relationship with the parameter Π. We also found that the peak pressure was mainly influenced by the energy deposited before separation of the shock wave front and the discharge plasma channel (DPC). The decay time constant of the pressure waveform was affected by the energy injection after the separation. These phenomena clearly demonstrated that the deposited energy influenced the expansion of the DPC and affected the shock wave characteristics.

The Numerical Simulation of the Shock Wave of Coal Gas Explosions in Gas Pipe*

Science.gov (United States)

Chen, Zhenxing; Hou, Kepeng; Chen, Longwei

2018-03-01

For the problem of large deformation and vortex, the method of Euler and Lagrange has both advantage and disadvantage. In this paper we adopt special fuzzy interface method(volume of fluid). Gas satisfies the conditions of conservation equations of mass, momentum, and energy. Based on explosion and three-dimension fluid dynamics theory, using unsteady, compressible, inviscid hydrodynamic equations and state equations, this paper considers pressure gradient’s effects to velocity, mass and energy in Lagrange steps by the finite difference method. To minimize transport errors of material, energy and volume in Finite Difference mesh, it also considers material transport in Euler steps. Programmed with Fortran PowerStation 4.0 and visualized with the software designed independently, we design the numerical simulation of gas explosion with specific pipeline structure, check the key points of the pressure change in the flow field, reproduce the gas explosion in pipeline of shock wave propagation, from the initial development, flame and accelerate the process of shock wave. This offers beneficial reference and experience to coal gas explosion accidents or safety precautions.

Nitrogen-rich heterocycles as reactivity retardants in shocked insensitive explosives.

Science.gov (United States)

Manaa, M Riad; Reed, Evan J; Fried, Laurence E; Goldman, Nir

2009-04-22

We report the first quantum-based multiscale simulations to study the reactivity of shocked perfect crystals of the insensitive energetic material triaminotrinitrobenzene (TATB). Tracking chemical transformations of TATB experiencing overdriven shock speeds of 9 km/s for up to 0.43 ns and 10 km/s for up to 0.2 ns reveal high concentrations of nitrogen-rich heterocyclic clusters. Further reactivity of TATB toward the final decomposition products of fluid N(2) and solid carbon is inhibited due to the formation of these heterocycles. Our results thus suggest a new mechanism for carbon-rich explosive materials that precedes the slow diffusion-limited process of forming the bulk solid from carbon clusters and provide fundamental insight at the atomistic level into the long reaction zone of shocked TATB.

Nanotwin Formation in High-Manganese Austenitic Steels Under Explosive Shock Loading

Science.gov (United States)

Canadinc, D.; Uzer, B.; Elmadagli, M.; Guner, F.

2018-04-01

The micro-deformation mechanisms active in a high-manganese austenitic steel were investigated upon explosive shock loading. Single system of nanotwins forming within primary twins were shown to govern the deformation despite the elevated temperatures attained during testing. The benefits of nanotwin formation for potential armor materials were demonstrated.

Non-destructive visualization of linear explosive-induced Pyroshock using phase arrayed laser-induced shock in a space launcher composite

International Nuclear Information System (INIS)

Jang, Jae Kyeong; Lee, Jung Ryul

2015-01-01

Separation mechanism of Space launch vehicles are used in various separation systems and pyrotechnic devices. The operation of these pyrotechnic devices generates Pyroshock that can cause failures in electronic components. The prediction of high frequency structural response, especially the shock response spectrum (SRS), is important. This paper presents a non-destructive visualization and simulation of linear explosive-induced Pyroshock using phase arrayed Laser-induced shock. The proposed method includes a laser shock test based on laser beam and filtering zone conditioning to predict the SRS of Pyroshock. A ballistic test based on linear explosive and non-contact Laser Doppler Vibrometers and a nondestructive Laser shock measurement using laser excitation and several PZT sensors, are performed using a carbon composite sandwich panel. The similarity of the SRS of the conditioned laser shock to that of the real explosive Pyroshock is evaluated with the Mean Acceleration Difference. The average of MADs over the two training points was 33.64%. And, MAD at verification point was improved to 31.99%. After that, experimentally found optimal conditions are applied to any arbitrary points in laser scanning area. Finally, it is shown that linear explosive-induced real Pyroshock wave propagation can be visualized with high similarity based on the proposed laser technology. (paper)

Influence of Test Section Geometry on the Blast Environment in an Explosively Driven Conical Shock Tube

Science.gov (United States)

2018-03-30

ARL-TR-8335•MAR 2018 US Army Research Laboratory Influence of Test Section Geometry on theBlast Environment in an Explosively DrivenConical Shock...ARL-TR-8335•MAR 2018 US Army Research Laboratory Influence of Test Section Geometry on theBlast Environment in an Explosively DrivenConical Shock...TITLE AND SUBTITLE    5a. CONTRACT NUMBER  5b. GRANT NUMBER  5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S)    5d.  PROJECT  NUMBER  5e. TASK NUMBER  5f

Generation of ultra-fast cumulative water jets by sub-microsecond underwater electrical explosion of conical wire arrays

Energy Technology Data Exchange (ETDEWEB)

Shafer, D.; Gurovich, V. Tz.; Gleizer, S.; Gruzinsky, K.; Krasik, Ya. E. [Physics Department, Technion, Haifa 32000 (Israel)

2015-12-15

The results of experiments with underwater electrical explosion of modified conical arrays of copper and aluminum wires are presented. A pulsed generator producing a 550 kA-amplitude current with a 400 ns rise time was used in the explosion of the arrays. The array explosion generates water flows converging at the axis of the cone. This flow generates a fast-moving water jet with a velocity exceeding 1.8 × 10{sup 5 }cm/s, which was observed being ejected from the surface of the water covering the array. The positions of the water jet were measured by multiple-exposure fast framing imaging. In experiments, the apex angle of the array, the thickness of the water layer above the arrays, or the material of the wires was altered, which changed the resulting velocities and shapes of the emitted jets. A model that considers the converging stationary flow of a slightly compressible fluid is suggested. The velocities and shapes of the jets obtained by this model agree well with the experimentally measured jet velocities.

Polarimetry and Schlieren diagnostics of underwater exploding wires

Science.gov (United States)

Fedotov-Gefen, A. V.; Krasik, Ya. E.

2009-11-01

Nondisturbing laser-probing polarimetry (based on the Faraday and Kerr effects) and Schlieren diagnostics were used in the investigation of underwater electrical wire explosion. Measuring the polarization plane rotation angle of a probing laser beam due to the Faraday effect allows one to determine an axially resolved current flowing through the exploding wire, unlike commonly used current probes. This optical method of measuring current yields results that match those obtained using a current viewing resistor within an accuracy of 10%. The same optical setup allows simultaneous space-resolved measurement of the electric field using the Kerr effect. It was shown that the maximal amplitude of the electric field in the vicinity of the high-voltage electrode is ˜80 kV/cm and that the radial electric field is <1 MV/cm during the wire explosion. Finally, it was shown that the use of Schlieren diagnostics allows one to obtain qualitatively the density distribution behind the shock wave front, which is important for the determination of the energy transfer from the discharge channel to the generated water flow.

Polarimetry and Schlieren diagnostics of underwater exploding wires

International Nuclear Information System (INIS)

Fedotov-Gefen, A. V.; Krasik, Ya. E.

2009-01-01

Nondisturbing laser-probing polarimetry (based on the Faraday and Kerr effects) and Schlieren diagnostics were used in the investigation of underwater electrical wire explosion. Measuring the polarization plane rotation angle of a probing laser beam due to the Faraday effect allows one to determine an axially resolved current flowing through the exploding wire, unlike commonly used current probes. This optical method of measuring current yields results that match those obtained using a current viewing resistor within an accuracy of 10%. The same optical setup allows simultaneous space-resolved measurement of the electric field using the Kerr effect. It was shown that the maximal amplitude of the electric field in the vicinity of the high-voltage electrode is ∼80 kV/cm and that the radial electric field is <1 MV/cm during the wire explosion. Finally, it was shown that the use of Schlieren diagnostics allows one to obtain qualitatively the density distribution behind the shock wave front, which is important for the determination of the energy transfer from the discharge channel to the generated water flow.

Augmentation of DAA Staggered – Solution Equations in Underwater Shock Problems for Singular Structural Mass Matrices

OpenAIRE

DeRuntz Jr., John A.

2005-01-01

The numerical solution of underwater shock fluid – structure interaction problems using boundary element/finite element techniques became tractable through the development of the family of Doubly Asymptotic Approximations (DAA). Practical implementation of the method has relied on the so-called augmentation of the DAA equations. The fluid and structural systems are respectively coupled by the structural acceleration vector in the surface normal direction on the right hand side of the DAA equa...

Shock initiation of explosives: Temperature spikes and growth spurts

Science.gov (United States)

Bassett, Will P.; Dlott, Dana D.

2016-08-01

When energetic materials are subjected to high-velocity impacts, the first steps in the shock-to-detonation transition are the creation, ignition, and growth of hot spots. We used 1-3.2 km s-1 laser-launched flyer plates to impact powdered octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, a powerful explosive, and monitored hundreds of emission bursts with an apparatus that determined temperature and emissivity at all times. The time-dependent volume fraction of hot spots was determined by measuring the time-dependent emissivity. After the shock, most hot spots extinguished, but the survivors smoldered for hundreds of nanoseconds until their temperatures spiked, causing a hot spot growth spurt. Depending on the impact duration, the growth spurts could be as fast as 300 ns and as slow as 13 μs.

High-order shock-fitted detonation propagation in high explosives

Science.gov (United States)

Romick, Christopher M.; Aslam, Tariq D.

2017-03-01

A highly accurate numerical shock and material interface fitting scheme composed of fifth-order spatial and third- or fifth-order temporal discretizations is applied to the two-dimensional reactive Euler equations in both slab and axisymmetric geometries. High rates of convergence are not typically possible with shock-capturing methods as the Taylor series analysis breaks down in the vicinity of discontinuities. Furthermore, for typical high explosive (HE) simulations, the effects of material interfaces at the charge boundary can also cause significant computational errors. Fitting a computational boundary to both the shock front and material interface (i.e. streamline) alleviates the computational errors associated with captured shocks and thus opens up the possibility of high rates of convergence for multi-dimensional shock and detonation flows. Several verification tests, including a Sedov blast wave, a Zel'dovich-von Neumann-Döring (ZND) detonation wave, and Taylor-Maccoll supersonic flow over a cone, are utilized to demonstrate high rates of convergence to nontrivial shock and reaction flows. Comparisons to previously published shock-capturing multi-dimensional detonations in a polytropic fluid with a constant adiabatic exponent (PF-CAE) are made, demonstrating significantly lower computational error for the present shock and material interface fitting method. For an error on the order of 10 m /s, which is similar to that observed in experiments, shock-fitting offers a computational savings on the order of 1000. In addition, the behavior of the detonation phase speed is examined for several slab widths to evaluate the detonation performance of PBX 9501 while utilizing the Wescott-Stewart-Davis (WSD) model, which is commonly used in HE modeling. It is found that the thickness effect curve resulting from this equation of state and reaction model using published values is dramatically more steep than observed in recent experiments. Utilizing the present fitting

Numerical modelling of the effect of using multi-explosives on the explosive forming of steel cones

OpenAIRE

De Vuyst, T; Kong, K; Djordjevic, N; Vignjevic, R; Campbell, JC; Hughes, K

2016-01-01

Modelling and analysis of underwater explosive forming process by using FEM and SPH formulation is presented in this work. The explosive forming of a steel cone is studied. The model setup includes a low carbon steel plate, plate holder, forming die as well as water and C4 explosive. The effect of multiple explosives on rate of targets deformation has been studied. Four different multi-explosives models have been developed and compared to the single explosive model. The formability of the ste...

Impact of surface energy on the shock properties of granular explosives

Science.gov (United States)

Bidault, X.; Pineau, N.

2018-01-01

This paper presents the first part of a two-fold molecular dynamics study of the impact of the granularity on the shock properties of high explosives. Recent experimental studies show that the granularity can have a substantial impact on the properties of detonation products {i.e., variations in the size distributions of detonation nanodiamonds [V. Pichot et al., Sci. Rep. 3, 2159 (2013)]}. These variations can have two origins: the surface energy, which is a priori enhanced from micro- to nano-scale, and the porosity induced by the granular structure. In this first report, we study the impact of the surface-energy contribution on the inert shock compression of TATB, TNT, α-RDX, and β-HMX nano-grains (triaminotrinitrobenzene, trinitrotoluene, hexogen and octogen, respectively). We compute the radius-dependent surface energy and combine it with an ab initio-based equation of state in order to obtain the resulting shock properties through the Rankine-Hugoniot relations. We find that the enhancement of the surface energy results in a moderate overheating under shock compression. This contribution is minor with respect to porosity, when compared to a simple macroscopic model. This result motivates further atomistic studies on the impact of nanoporosity networks on the shock properties.

Extension and Validation of UNDEX Analysis Methods

National Research Council Canada - National Science Library

Donahue, L

2004-01-01

.... Adaptive grid schemes for underwater shock and bubble analysis, hydrostatic pressure and airwater/seafloor boundaries, underwater explosion profiles, and fluid-backed shapes were also implemented...

Time-resolved dynamics of nanosecond laser-induced phase explosion

International Nuclear Information System (INIS)

Porneala, Cristian; Willis, David A

2009-01-01

Visualization of Nd : YAG laser ablation of aluminium targets was performed by a shadowgraph apparatus capable of imaging the dynamics of ablation with nanosecond time resolution. Direct observations of vaporization, explosive phase change and shock waves were obtained. The influence of vaporization and phase explosion on shock wave velocity was directly measured. A significant increase in the shock wave velocity was observed at the onset of phase explosion. However, the shock wave behaviour followed the form of a Taylor-Sedov spherical shock below and above the explosive phase change threshold. The jump in the shock wave velocity above phase explosion threshold is attributed to the release of stored enthalpy in the superheated liquid surface. The energy released during phase explosion was estimated by fitting the transient shock wave position to the Taylor scaling rules. Results of temperature calculations indicate that the vapour temperature at the phase explosion threshold is slightly higher than the critical temperature at the early stages of the shock wave formation. The shock wave pressure nearly doubled when transitioning from normal vaporization to phase explosion.

Pressure Measurements on a Deforming Surface in Response to an Underwater Explosion in a Water-Filled Aluminum Tube

Directory of Open Access Journals (Sweden)

G. Chambers

2001-01-01

Full Text Available Experiments have been conducted to benchmark DYSMAS computer code calculations for the dynamic interaction of water with cylindrical structures. Small explosive charges were suspended using hypodermic needle tubing inside Al tubes filled with distilled water. Pressures were measured during shock loading by tourmaline crystal, carbon resistor and ytterbium foil gages bonded to the tube using a variety of adhesives. Comparable calculated and measured pressures were obtained for the explosive charges used, with some gages surviving long enough to record results after cavitation with the tube wall.

Efficient transformation of Mycosphaerella fijiensis by underwater shock waves.

Science.gov (United States)

Escobar-Tovar, Lina; Magaña-Ortíz, Denis; Fernández, Francisco; Guzmán-Quesada, Mauricio; Sandoval-Fernández, Jorge A; Ortíz-Vázquez, Elizabeth; Loske, Achim M; Gómez-Lim, Miguel A

2015-12-01

Black leaf streak disease, also known as black Sigatoka, causes dramatic losses in production of banana and plantains fruits. The disease is caused by the pathogenic fungus Mycosphaerella fijiensis (anamorph Pseudocercospora fijiensis; Mycosphaerellaceae). Genetic transformation of M. fijiensis would allow a better understanding of molecular basis of pathogenicity and design novel approaches to control the infection caused by this pathogen. However, transformation of this fungus has not been easy. We report here a protocol for genetic transformation of M. fijiensis employing underwater shock waves and intact conidia. The recombinant strains recovered showed genetic stability over >10 generations. The frequency of transformation obtained was between 75 and 150 times higher than the efficiency reported in the only article published on transformation of M. fijiensis using spheroplasts. This improvement allowed the use of a thousand times less cells than the amount employed before, avoiding the need for cumbersome successive batch cultures. Our protocol is simple, highly efficient, fast and reproducible and together with the available genomes of M. fijiensis and Musa acuminata, it offers new possibilities to study the diverse mechanisms of pathogenesis of the fungus. Copyright © 2015. Published by Elsevier B.V.

Calculation of the shock-wave in the region close to an underground nuclear explosion (method Cades); Calcul de l'onde de choc en zone proche d'une explosion nucleaire souterraine (methode cades)

Energy Technology Data Exchange (ETDEWEB)

Supiot, F; Brugies, J [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

1969-07-01

The outline of a method is presented for calculating the characteristics of a shock wave produced by an underground nuclear explosion (pressure, wave velocity, velocity of the medium, energy left in the medium by the shock, etc.). By means of an application to a granitic medium and of a comparison with results obtained during French nuclear explosions, it has been possible to show the good agreement existing between the calculations and the experimental results. The advantages of such a method for studying the industrial applications of underground nuclear explosions are stressed. (authors) [French] On expose les grandes lignes d'une methode de calcul des caracteristiques de l'onde de choc issue d'une explosion nucleaire souterraine (pression, vitesse de l'onde, vitesse du milieu, energie deposee par le choc dans le milieu...). Une application a un milieu granitique et une comparaison aux resultats obtenus au cours d'explosions nucleaires francaises permet de montrer la bonne concordance entre le calcul et les resultats experimentaux. On souligne l'interet d'une telle, methode pour l'etude d'applications industrielles des explosions nucleaires souterraines. (auteurs)

Predictive Model for the Analysis of the Effects of Underwater Impulsive Sources on Marine Life

National Research Council Canada - National Science Library

Lazauski, Colin J

2007-01-01

A method is provided to predict the biological consequences to marine animals from exposure to multiple underwater impulsive sources by simulating underwater explosions over a defined period of time...

Applied pressure-dependent anisotropic grain connectivity in shock consolidated MgB{sub 2} samples

Energy Technology Data Exchange (ETDEWEB)

Ohashi, Wataru [Graduate School of Engineering, University of Yamanashi, Takeda 4-3-11, Kofu 400-8511 (Japan); Takenaka, Kenta [Graduate School of Engineering, University of Yamanashi, Takeda 4-3-11, Kofu 400-8511 (Japan); Kondo, Tadashi [Graduate School of Engineering, University of Yamanashi, Takeda 4-3-11, Kofu 400-8511 (Japan); Tamaki, Hideyuki [Graduate School of Engineering, University of Yamanashi, Takeda 4-3-11, Kofu 400-8511 (Japan); Matsuzawa, Hidenori [Graduate School of Engineering, University of Yamanashi, Takeda 4-3-11, Kofu 400-8511 (Japan)]. E-mail: matuzawa@mx3.nns.ne.jp; Kai, Shoichiro [Advanced Materials and Process Development Group, Explosive Division, Asahi Kasei Chemicals Corporation, Oita 870-0392 (Japan); Kakimoto, Etsuji [Advanced Materials and Process Development Group, Explosive Division, Asahi Kasei Chemicals Corporation, Oita 870-0392 (Japan); Takano, Yoshihiko [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Minehara, Eisuke [FEL Laboratory, Tokai Site, Japan Atomic Energy Research Institute, Shirakata-shirane 2-4, Tokai, Ibaraki 319-1195 (Japan)

2006-09-15

Three different cylindrical MgB{sub 2} bulk samples were prepared by the underwater shock consolidation method in which shock waves of several GPa, generated by detonation of explosives, were applied to a metallic cylinder containing commercially available MgB{sub 2} powders with no additives. Resistivity anisotropy of the samples increased with shock pressure. The highest- and medium-pressure applied samples had finite resistivities in the radial direction for the whole temperature range down to 12 K, whereas their axial and azimuthal resistivities dropped to zero at 32-35 K. By contrast, the lowest-pressure applied sample was approximately isotropic with a normal-state resistivity of {approx}40 {mu}{omega} cm, an onset temperature of {approx}38.5 K, and a transition width of {approx}4.5 K. These extremely anisotropic properties would have resulted from the distortion of grain boundaries and grain cores, caused by the shock pressures and their repeated bouncing.

Effect of shock pressure on the structure and superconducting properties of Y-Ba-Cu-O in explosively fabricated bulk metal-matrix composites

Science.gov (United States)

Murr, L. E.; Niou, C. S.; Pradhan-Advani, M.

1991-01-01

While it is now well established that copper-oxide-based power, or virtually any other ceramic superconductor powder, can be consolidated and encapsulated within a metal matrix by explosive consolidation, the erratic superconductivity following fabrication has posed a major problem for bulk applications. The nature of this behavior was found to arise from microstructural damage created in the shock wave front, and the residual degradation in superconductivity was demonstrated to be directly related to the peak shock pressure. The explosively fabricated or shock loaded YBa2Cu3Ox examples exhibit drastically altered rho (or R) - T curves. The deterioration in superconductivity is even more noticeable in the measurement of ac magnetic susceptibility and flux exclusion or shielding fraction which is also reduced in proportion to increasing peak shock pressure. The high frequency surface resistance (in the GHz range) is also correspondingly compromised in explosively fabricated, bulk metal-matrix composites based on YBa2Cu3O7. Transmission electron microscopy (including lattice imaging techniques) is being applied in an effort to elucidate the fundamental (microstructural) nature of the shock-induced degradation of superconductivity and normal state conductivity. One focus of TEM observations has assumed that oxygen displaced from b-chains rather than oxygen-vacancy disorder in the basal plane of oxygen deficient YBa2Cu3Ox may be a prime mechanism. Shock-wave displaced oxygen may also be locked into new positions or interstitial clusters or chemically bound to displaced metal (possibly copper) atoms to form precipitates, or such displacements may cause the equivalent of local lattice cell changes as a result of stoichiometric changes. While the shock-induced suppression of T(sub c) is not desirable in the explosive fabrication of bulk metal-matrix superconductors, it may be turned into an advantage if the atomic-scale distortion can be understood and controlled as local

Shock-to-detonation transition of RDX, HMX and NTO based composite high explosives: experiments and modelling

International Nuclear Information System (INIS)

Baudin, G; Roudot, M; Genetier, M; Mateille, P; Lefrançois, A

2014-01-01

HMX, RDX and NTO based cast-cured plastic bounded explosive (PBX) are widely used in insensitive ammunitions. Designing modern warheads needs robust and reliable models to compute shock ignition and detonation propagation inside PBX. Comparing to a pressed PBX, a cast-cured PBX is not porous and the hot-spots are mainly located at the grain-binder interface leading to a different burning behavior during shock-to-detonation transition. Here, we review the shock-to-detonation transition (SDT) and its modeling for cast-cured PBX containing HMX, RDX and NTO. Future direction is given in conclusion.

Shock-to-detonation transition of RDX, HMX and NTO based composite high explosives: experiments and modelling

Science.gov (United States)

Baudin, G.; Roudot, M.; Genetier, M.; Mateille, P.; Lefrançois, A.

2014-05-01

HMX, RDX and NTO based cast-cured plastic bounded explosive (PBX) are widely used in insensitive ammunitions. Designing modern warheads needs robust and reliable models to compute shock ignition and detonation propagation inside PBX. Comparing to a pressed PBX, a cast-cured PBX is not porous and the hot-spots are mainly located at the grain-binder interface leading to a different burning behavior during shock-to-detonation transition. Here, we review the shock-to-detonation transition (SDT) and its modeling for cast-cured PBX containing HMX, RDX and NTO. Future direction is given in conclusion.

An approach to incorporate the detonation shock dynamics into the calculation of explosive acceleration of metals

International Nuclear Information System (INIS)

Li Qingzhong; Sun Chengwei; Zhao Feng; Gao Wen; Wen Shanggang; Liu Wenhan

1999-11-01

The generalized geometrical optics model for the detonation shock dynamics (DSD) has been incorporated into the two dimensional hydro-code WSU to form a combination code ADW for numerical simulation of explosive acceleration of metals. An analytical treatment of the coupling conditions at the nodes just behind the detonation front is proposed. The experiments on two kinds of explosive-flyer assemblies with different length/diameter ratio were carried out to verify the ADW calculations, where the tested explosive was HMX or TATB based. It is found that the combination of DSD and hydro-code can improve the calculation precision, and has advantages in larger meshes and less CPU time

Investigation of shock waves in explosive blasts using fibre optic pressure sensors

Energy Technology Data Exchange (ETDEWEB)

Watson, S [School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); MacPherson, W N [School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Barton, J S [School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Jones, J D C [School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Tyas, A [Department of Civil and Structural Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Pichugin, A V [Department of Civil and Structural Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Hindle, A [Department of Civil and Structural Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Parkes, W [Scottish Microelectronics Centre, Kings Buildings, West Mains Road, Edinburgh EH9 3JF (United Kingdom); Dunare, C [Scottish Microelectronics Centre, Kings Buildings, West Mains Road, Edinburgh EH9 3JF (United Kingdom); Stevenson, T [Scottish Microelectronics Centre, Kings Buildings, West Mains Road, Edinburgh EH9 3JF (United Kingdom)

2005-01-01

We describe miniature all-optical pressure sensors, fabricated by wafer etching techniques, less than 1mm{sup 2} in overall cross-section with rise times in the {mu}s regime and pressure ranges typically 600 kPa. Their performance is suitable for experimental studies of the pressure-time history for test models exposed to shocks initiated by an explosive charge. The small size and fast response of the sensors promises higher quality data than has been previously available from conventional electrical sensors, with potential improvements to numerical models of blast effects. Provisional results from blast tests will be presented in which up to 6 sensors were multiplexed, embedded within test models in a range of orientations relative to the shock front.

Investigation of shock waves in explosive blasts using fibre optic pressure sensors

International Nuclear Information System (INIS)

Watson, S; MacPherson, W N; Barton, J S; Jones, J D C; Tyas, A; Pichugin, A V; Hindle, A; Parkes, W; Dunare, C; Stevenson, T

2005-01-01

We describe miniature all-optical pressure sensors, fabricated by wafer etching techniques, less than 1mm 2 in overall cross-section with rise times in the μs regime and pressure ranges typically 600 kPa. Their performance is suitable for experimental studies of the pressure-time history for test models exposed to shocks initiated by an explosive charge. The small size and fast response of the sensors promises higher quality data than has been previously available from conventional electrical sensors, with potential improvements to numerical models of blast effects. Provisional results from blast tests will be presented in which up to 6 sensors were multiplexed, embedded within test models in a range of orientations relative to the shock front

STOCHASTIC NATURE OF GRAVITATIONAL WAVES FROM SUPERNOVA EXPLOSIONS WITH STANDING ACCRETION SHOCK INSTABILITY

International Nuclear Information System (INIS)

Kotake, Kei; Iwakami, Wakana; Ohnishi, Naofumi; Yamada, Shoichi

2009-01-01

We study the properties of gravitational waves (GWs) based on three-dimensional (3D) simulations, which demonstrate neutrino-driven explosions aided by standing accretion shock instability (SASI). Pushed by evidence supporting slow rotation prior to core collapse, we focus on the asphericities in neutrino emissions and matter motions outside the protoneutron star. By performing a ray-tracing calculation in 3D, we estimate accurately the gravitational waveforms from anisotropic neutrino emissions. In contrast to the previous work assuming axisymmetry, we find that the gravitational waveforms vary much more stochastically because the explosion anisotropies depend sensitively on the growth of SASI which develops chaotically in all directions. Our results show that the GW spectrum has its peak near ∼100 Hz, reflecting SASI-induced matter overturns of ∼O(10) ms. We point out that the detection of such signals, possibly visible to the LIGO-class detectors for a Galactic supernova, could be an important probe into the long-veiled explosion mechanism.

CHARGED PARTICLE MOTION IN AN EXPLOSIVELY GENERATED IONIZING SHOCK

International Nuclear Information System (INIS)

Boswell, Christopher J.; O'Connor, Patrick D.

2009-01-01

Different aspects of the plasma generated in a gas contained in a tube due to detonation of a small explosive charge located at one end of the tube are presented. The motion of the charged particles within the plasma is monitored using Rogowski coils. Using time-resolved emission spectroscopy the temperature and species in the detonation products and compressed gas behind the shock wave are recorded. From the spectral lines of the emission profiles the temperatures and electron density were evaluated to be in the vicinity of 7,000 K and 5x10 22 m -3 . An ultra fast wave traveling down the guide tube ahead of the hydrodynamic shock and causing any charged particles there to move fast enough to be detected by the Rogowski coils was recorded. From the measurements the phase velocity of the wave was calculated at 525 km/s when krypton filled the tube, and 1300 km/s in the case of argon. The temperature and density measurements are consistent with the data reported in the literature for similar tests. The electrostatic pulse measurements are a new phenomena not previously observed.

Expansion shock waves in the implosion process from a time-reversible molecular-dynamics simulation of a dual explosion process

International Nuclear Information System (INIS)

Komatsu, Nobuyoshi; Abe, Takashi

2007-01-01

Why does not an expansion shock wave exist in a gaseous medium in nature? The reason has been widely believed to be the irreversibility in nature, while an obvious demonstration for this belief has not been accomplished yet. In order to resolve the question from a microscopic viewpoint, an implosion process dual to an explosion process was investigated by means of the molecular-dynamics method (MD). To this aim, we employed a ''bit-reversible algorithm (Bit MD)'' that was completely time-reversible in a microscopic viewpoint and was free from any round-off error. Here we show that, through a dual implosion simulation (i.e., a time-reversible simulation of the explosion), a kind of expansion shock wave is successfully formed in the Bit MD simulation. Furthermore, we show that when the controlled noise is intentionally added to the Bit MD, the expansion shock wave disappears dramatically and turns into an isentropic expansion wave, even if the noise is extremely small. Since the controlled noise gives rise to the irreversibility in the Bit MD simulation, it can be concluded that the irreversibility in the system prohibits the expansion shock wave from appearing in the system

Spherical Solutions of an Underwater Explosion Bubble

Directory of Open Access Journals (Sweden)

Andrew B. Wardlaw

1998-01-01

Full Text Available The evolution of the 1D explosion bubble flow field out to the first bubble minimum is examined in detail using four different models. The most detailed is based on the Euler equations and accounts for the internal bubble fluid motion, while the simplest links a potential water solution to a stationary, Isentropic bubble model. Comparison of the different models with experimental data provides insight into the influence of compressibility and internal bubble dynamics on the behavior of the explosion bubble.

Human Injury Criteria for Underwater Blasts

Science.gov (United States)

2014-09-08

further underscored the need for this new guideline based on injury data. Conference Name: Personal Armour Systems Symposium Conference Date...29.  Cole, R., Underwater Explosion. (Dover Publications, Inc ., New York, N.Y., 1948) 30.  Nakahara, M., Nagayama, K, Mori, Y, Japanese Journal...Abstract of the Undersea and Hyperbaric Medical Society, Inc . Annual Scientific Meeting, (1976).

Shock Isolation Elements Testing for High Input Loadings. Volume II. Foam Shock Isolation Elements.

Science.gov (United States)

SHOCK ABSORBERS ), (*GUIDED MISSILE SILOS, SHOCK ABSORBERS ), (*EXPANDED PLASTICS, (*SHOCK(MECHANICS), REDUCTION), TEST METHODS, SHOCK WAVES, STRAIN(MECHANICS), LOADS(FORCES), MATHEMATICAL MODELS, NUCLEAR EXPLOSIONS, HARDENING.

General phenomenology of underground nuclear explosions

International Nuclear Information System (INIS)

Derlich, S.; Supiot, F.

1969-01-01

An essentially qualitatively description is given of the phenomena related to underground nuclear explosions (explosion of a single unit, of several units in line, and simultaneous explosions). In the first chapter are described the phenomena which are common to contained explosions and to explosions forming craters (formation and propagation of a shock-wave causing the vaporization, the fusion and the fracturing of the medium). The second chapter describes the phenomena related to contained explosions (formation of a cavity with a chimney). The third chapter is devoted to the phenomenology of test explosions which form a crater; it describes in particular the mechanism of formation and the different types of craters as a function of the depth of the explosion and of the nature of the ground. The aerial phenomena connected with explosions which form a crater: shock wave in the air and focussing at a large distance, and dust clouds, are also dealt with. (authors) [fr

Donor free radical explosive composition

Science.gov (United States)

Walker, Franklin E. [15 Way Points Rd., Danville, CA 94526; Wasley, Richard J. [4290 Colgate Way, Livermore, CA 94550

1980-04-01

An improved explosive composition is disclosed and comprises a major portion of an explosive having a detonation velocity between about 1500 and 10,000 meters per second and a minor amount of a donor additive comprising an organic compound or mixture of organic compounds capable of releasing low molecular weight free radicals or ions under mechanical or electrical shock conditions and which is not an explosive, or an inorganic compound or mixture of inorganic compounds capable of releasing low molecular weight free radicals or ions under mechanical or electrical shock conditions and selected from ammonium or alkali metal persulfates.

Shock Isolation Elements Testing for High Input Loadings. Volume III. Mechanical Shock Isolation Elements.

Science.gov (United States)

SHOCK ABSORBERS ), (*GUIDED MISSILE SILOS, SHOCK ABSORBERS ), (*SPRINGS, (*SHOCK(MECHANICS), REDUCTION), TORSION BARS, ELASTOMERS, DAMPING, EQUATIONS OF MOTION, MODEL TESTS, TEST METHODS, NUCLEAR EXPLOSIONS, HARDENING.

2D RADIATION-HYDRODYNAMIC SIMULATIONS OF SUPERNOVA SHOCK BREAKOUT IN BIPOLAR EXPLOSIONS OF A BLUE SUPERGIANT PROGENITOR

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Akihiro; Maeda, Keiichi [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto, 606-8502 (Japan); Shigeyama, Toshikazu [Research Center for the Early Universe, School of Science, University of Tokyo, Bunkyo-ku, Tokyo, 113-0033 (Japan)

2016-07-10

A two-dimensional special relativistic radiation-hydrodynamics code is developed and applied to numerical simulations of supernova shock breakout in bipolar explosions of a blue supergiant. Our calculations successfully simulate the dynamical evolution of a blast wave in the star and its emergence from the surface. Results of the model with spherical energy deposition show a good agreement with previous simulations. Furthermore, we calculate several models with bipolar energy deposition and compare their results with the spherically symmetric model. The bolometric light curves of the shock breakout emission are calculated by a ray-tracing method. Our radiation-hydrodynamic models indicate that the early part of the shock breakout emission can be used to probe the geometry of the blast wave produced as a result of the gravitational collapse of the iron core.

Study on possible explosive reactions of sodium nitrate-bitumen mixtures initiated by a shock wave

International Nuclear Information System (INIS)

Savornin, J.; Vasseur, C.

1986-01-01

Potential hazards of the mixture sodium nitrate-bitumen obtained by embedding in bitumen liquid radioactive effluents concentrated by evaporation are studied in case of accidental shock wave. A theoretical evaluation based on thermodynamical data show a low probability, nevertheless different from zero. No explosion occurred in tests realized in severe conditions. In conclusion there is no risk of detonation of large quantity of bitumen-nitrates stored in 200-liter drum in radioactive waste storage [fr

Performance properties of commercial explosives

Energy Technology Data Exchange (ETDEWEB)

Johnson, J.N.; Mader, C.L.; Goldstein, S.

1983-01-01

The aquarium test is a proven means of obtaining nonidial performance property data for commercial blasting agents. Optical data on the detonation velocity, shock wave in water, and expansion rate of the pipe enclosing the detonation products (in combination with the equilibrium thermodynamic chemistry code BKW) give the C-J state and degree of chemical reaction at the detonation front, as well as information on additional chemical reaction that occurs as the detonation products expand. Specific explosive systems that are studied are ammonium nitrate-fuel oil mixture (ANFO), aluminized ANFO, flaked trinitrotoluene (TNT), and several other commercial products in 10-cm diam and 20-cm-diam pipes of Plexiglas and clay. Experimental shock-pressure data are obtained with lithium niobate transducers placed in the water surrounding the explosive charge. These data show that the addition of approx.100-..mu..m aluminum particles to ANFO significantly increases the initial peak shock pressure delivered to the surrounding medium. Peak shock pressures in the water, calculated from the shock-wave orientation, are also useful in comparing performance properties of various commercial explosives. 20 references, 17 figures, 2 tables.

Mesoscale modeling of metal-loaded high explosives

Energy Technology Data Exchange (ETDEWEB)

Bdzil, John Bohdan [Los Alamos National Laboratory; Lieberthal, Brandon [UNIV OF ILLINOIS; Srewart, Donald S [UNIV OF ILLINOIS

2010-01-01

We describe a 3D approach to modeling multi-phase blast explosive, which is primarily condensed explosive by volume with inert embedded particles. These embedded particles are uniform in size and placed on the array of a regular lattice. The asymptotic theory of detonation shock dynamics governs the detonation shock propagation in the explosive. Mesoscale hydrodynamic simulations are used to show how the particles are compressed, deformed, and accelerated by the high-speed detonation products flow.

Inhomogeneous wire explosion in water

International Nuclear Information System (INIS)

Hwangbo, C.K.; Kong, H.J.; Lee, S.S.

1980-01-01

Inhomogeneous processes are observed in underwater copper wire explosion induced by a condensed capacitor discharge. The wire used is 0.1 mm in diameter and 10 mm long, and the capacitor of 2 μF is charged to 5 KV. A N 2 laser is used for the diagnostic of spatial extension of exploding copper vapour. The photographs obtained in this experiment show unambiguously the inhomogeneous explosion along the exploding wire. The quenching of plasma by the surrounding water inhibits the expansion of the vapour. It is believed the observed inhomogeneous explosion along the wire is located and localized around Goronkin's striae, which was first reported by Goronkin and discussed by Froengel as a pre-breakdown phenomenon. (author)

General phenomenology of underground nuclear explosions; Phenomenologie generale des explosions nucleaires souterraines

Energy Technology Data Exchange (ETDEWEB)

Derlich, S; Supiot, F [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

1969-07-01

An essentially qualitatively description is given of the phenomena related to underground nuclear explosions (explosion of a single unit, of several units in line, and simultaneous explosions). In the first chapter are described the phenomena which are common to contained explosions and to explosions forming craters (formation and propagation of a shock-wave causing the vaporization, the fusion and the fracturing of the medium). The second chapter describes the phenomena related to contained explosions (formation of a cavity with a chimney). The third chapter is devoted to the phenomenology of test explosions which form a crater; it describes in particular the mechanism of formation and the different types of craters as a function of the depth of the explosion and of the nature of the ground. The aerial phenomena connected with explosions which form a crater: shock wave in the air and focussing at a large distance, and dust clouds, are also dealt with. (authors) [French] On donne une description essentiellement qualitative des phenomenes lies aux explosions nucleaires souterraines (explosion d'un seul engin, d'engins en ligne et explosions simultanees). Dans un premier chapitre sont decrits les phenomenes communs aux explosions contenues et aux explosions formant un cratere (formation et propagation d'une onde de choc provoquant la vaporisation, la fusion et la fracturation du milieu). Le deuxieme chapitre decrit les phenomenes lies aux tirs contenus (formation d'une cavite et d'une cheminee). Le troisieme chapitre est consacre a la phenomenologie des tirs formant un cratere et decrit notamment le mecanisme de formation et les differents types de crateres en fonction de la profondeur d'explosion et de la nature du terrain. Les phenomenes aeriens lies aux explosions formant un cratere: onde de pression aerienne et focalisation a grande distance, nuages de poussieres, sont egalement abordes. (auteurs)

Shock-to-detonation transition of RDX and NTO based composite high explosives: experiments and modeling

Science.gov (United States)

Baudin, Gerard; Roudot, Marie; Genetier, Marc

2013-06-01

Composite HMX and NTO based high explosives (HE) are widely used in ammunitions. Designing modern warheads needs robust and reliable models to compute shock ignition and detonation propagation inside HE. Comparing to a pressed HE, a composite HE is not porous and the hot-spots are mainly located at the grain - binder interface leading to a different behavior during shock-to-detonation transition. An investigation of how shock-to-detonation transition occurs inside composite HE containing RDX and NTO is proposed in this lecture. Two composite HE have been studied. The first one is HMX - HTPB 82:18. The second one is HMX - NTO - HTPB 12:72:16. These HE have been submitted to plane sustained shock waves at different pressure levels using a laboratory powder gun. Pressure signals are measured using manganin gauges inserted at several distances inside HE. The corresponding run-distances to detonation are determined using wedge test experiments where the plate impact is performed using a powder gun. Both HE exhibit a single detonation buildup curve in the distance - time diagram of shock-to-detonation transition. This feature seems a common shock-to-detonation behavior for composite HE without porosity. This behavior is also confirmed for a RDX - HTPB 85:15 based composite HE. Such a behavior is exploited to determine the heterogeneous reaction rate versus the shock pressure using a method based on the Cauchy-Riemann problem inversion. The reaction rate laws obtained allow to compute both run-distance to detonation and pressure signals.

Shock-to-detonation transition in solid heterogeneous explosives; La transition choc-detonation dans les explosifs solides heterogenes

Energy Technology Data Exchange (ETDEWEB)

Belmas, R.

2003-07-01

This paper is an overview of the studies performed during the last decades on the shock-to-detonation transition process in heterogeneous explosives. We present the experimental and theoretical approaches mentioned in the literature and/or developed at CEA/DAM. The aim is to identify which main mechanisms govern this transition process and to evaluate the relevance of the available modeling tools. (author)

Inspecting the inside of underwater hull

Science.gov (United States)

Valkovic, Vladivoj; Sudac, Davorin

2009-05-01

In order to demonstrate the possibility of identifying the material within ship's underwater hull, sunken ships and other objects on the sea floor tests with the 14 MeV sealed tube neutron generator incorporated inside a small submarine submerged in the test basin filled with sea water have been performed. Results obtained for inspection of diesel fuel and explosive presence behind single and double hull constructions are presented.

Approximating a free-field blast environment in the test section of an explosively driven conical shock tube

Science.gov (United States)

Stewart, J. B.

2018-02-01

This paper presents experimental data on incident overpressures and the corresponding impulses obtained in the test section of an explosively driven 10° (full angle) conical shock tube. Due to the shock tube's steel walls approximating the boundary conditions seen by a spherical sector cut out of a detonating sphere of energetic material, a 5.3-g pentolite shock tube driver charge produces peak overpressures corresponding to a free-field detonation from an 816-g sphere of pentolite. The four test section geometries investigated in this paper (open air, cylindrical, 10° inscribed square frustum, and 10° circumscribed square frustum) provide a variety of different time histories for the incident overpressures and impulses, with a circumscribed square frustum yielding the best approximation of the estimated blast environment that would have been produced by a free-field detonation.

Development of a Novel Shock Wave Catheter Ablation System

Science.gov (United States)

Yamamoto, H.; Hasebe, Yuhi; Kondo, Masateru; Fukuda, Koji; Takayama, Kazuyoshi; Shimokawa, Hiroaki

Although radio-frequency catheter ablation (RFCA) is quite effective for the treatment tachyarrhythmias, it possesses two fundamental limitations, including limited efficacy for the treatment of ventricular tachyarrhythmias of epicardial origin and the risk of thromboembolism. Consequently, new method is required, which can eradicate arrhythmia source in deep part of cardiac muscle without heating. On the other hand, for a medical application of shock waves, extracorporeal shock wave lithotripter (ESWL) has been established [1]. It was demonstrated that the underwater shock focusing is one of most efficient method to generate a controlled high pressure in a small region [2]. In order to overcome limitations of existing methods, we aimed to develop a new catheter ablation system with underwater shock waves that can treat myocardium at arbitrary depth without causing heat.

Cavitation phenomena in extracorporeal microexplosion lithotripsy

Science.gov (United States)

Tomita, Y.; Obara, T.; Takayama, K.; Kuwahara, M.

1994-09-01

An experimental investigation was made of cavitation phenomena induced by underwater shock wave focusing applied to the extracorporeal microexplosion lithotripsy (microexplosion ESWL). Firstly an underwater microexplosion generated by detonation of a 10 mg silver azide pellet was studied and secondly underwater shock focusing and its induced cavitation phenomena were investgated. Underwater shock wave was focused by using a semi-ellipsoidal reflector in which a shock wave generated at the first focal point of the reflector was reflected and focused at the second focal point. It is found that an explosion product gas bubble did not produce any distinct rebound shocks. Meantime cavitation appeared after shock focusing at the second focal point where expansion waves originated at the exit of the reflector were simultaneously collected. A shock/bubble interaction is found to contribute not only to urinary tract stone disintegration but also tissue damage. The cavitation effect associated with the microexplosion ESWL was weaker in comparison with a spark discharge ESWL. The microexplosion ESWL is an effective method which can minimize the number of shock exposures hence decreasing tissue damage by conducting precise positioning of urinary tract stones.

Study on explosives and their quality performance

Energy Technology Data Exchange (ETDEWEB)

Nabiullah, M.; Pingua, B.M.P.; Jagdish Khan, M.; Emranuzzaman [Central Mining Research Institute, Dhanbad (India)

2005-07-01

There are about forty suppliers of explosive and blasting accessories in India manufacturing site mixed emulsion, site mixed slurry, ANFO, HANFO, packed products, and blasting accessories of use in surface and underground mines. A field laboratory was set up to measure explosive properties of explosive samples, cast booster, detonating fuse, detonators, cord relay, MS connector, and shock tubes. Density, velocity of detonation, water percentage, water resistance, and energy output were considered as the important properties of explosives. A rating system was designed for selection of good explosive products. The delay interval and delay scattering in cord relay and shock tube was studied to improve blast performance. This paper describes in detail the method of measurement and vender rating system for explosive products as per marking system accepted by Coal India. 12 refs., 4 figs., 22 tabs.

Free radical explosive composition

Science.gov (United States)

Walker, Franklin E.; Wasley, Richard J.

1979-01-01

An improved explosive composition is disclosed and comprises a major portion of an explosive having a detonation velocity between about 1500 and 10,000 meters per second and a minor amount of a getter additive comprising a compound or mixture of compounds capable of capturing or deactivating free radicals or ions under mechanical or electrical shock conditions and which is not an explosive. Exemplary getter additives are isocyanates, olefins and iodine.

Shock-induced modification of inorganic powders

International Nuclear Information System (INIS)

Graham, R.A.; Morosin, B.; Venturini, E.L.; Beauchamp, E.K.; Hammetter, W.F.

1984-01-01

The results of studies performed to quantify the characteristics of TiO2, ZrO2 and Si3N4 powders exposed to explosive loading and post-shock analysis are reported. The shocks were produced with plane wave generators and explosive pads impinging on steel disks, a copper recovery fixture, and then the samples. Peak pressures of 13 and 17 GPa were attained, along with 40 GPz at the center of the powder cavity. Data are provided on the changes occurring during the explosive densification and X-ray and paramagnetic studies of the products. Only fractured disks were obtained in the trials. The shock-treated materials were more free flowing than the original powders, which were fluffy. Post-shock annealing was a significant feature of the treated powders

Electromagnetic field effects in explosives

Science.gov (United States)

Tasker, Douglas

2009-06-01

Present and previous research on the effects of electromagnetic fields on the initiation and detonation of explosives and the electromagnetic properties of explosives are reviewed. Among the topics related to detonating explosives are: measurements of conductivity; enhancement of performance; and control of initiation and growth of reaction. Hayes...()^1 showed a strong correlation of peak electrical conductivity with carbon content of the detonation products. Ershov.......^2 linked detailed electrical conductivity measurements with reaction kinetics and this work was extended to enhance detonation performance electrically;...^3 for this, electrical power densities of the order of 100 TW/m^2 of explosive surface normal to the detonation front were required. However, small electrical powers are required to affect the initiation and growth of reaction.......^4,5 A continuation of this work will be reported. LA-UR 09-00873 .^1 B. Hayes, Procs. of 4th Symposium (International) on Detonation (1965), p. 595. ^2 A. Ershov, P. Zubkov, and L. Luk'yanchikov, Combustion, Explosion, and Shock Waves 10, 776-782 (1974). ^3 M. Cowperthwaite, Procs. 9th Detonation Symposium (1989), p. 388-395. ^4 M. A. Cook and T. Z. Gwyther, ``Influence of Electric Fields on Shock to Detonation Transition,'' (1965). ^5 D. Salisbury, R. Winter, and L. Biddle, Procs. of the APS Topical Conference on Shock Compression of Condensed Matter (2005) p. 1010-1013.

R-22 vapor explosions

International Nuclear Information System (INIS)

Anderson, R.P.; Armstrong, D.R.

1977-01-01

Previous experimental and theoretical studies of R-22 vapor explosions are reviewed. Results from two experimental investigations of vapor explosions in a medium scale R-22/water system are reported. Measurements following the drop of an unrestrained mass of R-22 into a water tank demonstrated the existence of two types of interaction behavior. Release of a constrained mass of R-22 beneath the surface of a water tank improved the visual resolution of the system thus allowing identification of two interaction mechansims: at low water temperatures, R-22/water contact would produce immediate violent boiling; at high water temperatures a vapor film formed around its R-22 as it was released, explosions were generated by a surface wave which initiated at a single location and propagated along the vapor film as a shock wave. A new vapor explosion model is proposed, it suggests explosions are the result of a sequence of three independent steps: an initial mixing phase, a trigger and growth phase, and a mature phase where a propagating shock wave accelerates the two liquids into a collapsing vapor layer causing a high velocity impact which finely fragments and intermixes the two liquids

Apparatus for reducing shock and overpressure

Science.gov (United States)

Walter, C.E.

1975-01-28

An apparatus for reducing shock and overpressure is particularly useful in connection with the sequential detonation of a series of nuclear explosives under ground. A coupling and decoupling arrangement between adjacent nuclear explosives in the tubing string utilized to emplace the explosives is able to support lower elements on the string but yields in a manner which absorbs energy when subjected to the shock wave produced upon detonation of one of the explosives. Overpressure is accomodated by an arrangement in the string which provides an additional space into which the pressurized material can expand at a predetermined overpressure. (10 claims)

Safety engineering experiments of explosives

Energy Technology Data Exchange (ETDEWEB)

Ishikawa, Noboru

1987-07-24

The outline of large scale experiments carried out every year since 1969 to obtain fundamental data and then establish the safety engineering standards concerning the manufacturing, storage and transportation, etc. of all explosives was described. Because it becomes recently difficult to ensure the safety distance in powder magazines and powder plants, the sandwich structure with sand is thought to be suitable as the neighboring barrier walls. The special vertical structure for embankments to provide against a emergency explosion is effective to absorb the blast. Explosion behaviors such as initiating sensitivity, detonation, sympathetic detonation, and shock occurence of the ANFO explosives in place of dynamite and the slurry explosives were studied. The safety engineering standards for the manufacturing and application of explosives were studied to establish because accidents by tabacco fire are not still distinguished. Much data concerning early stage fire fighting, a large quantity of flooding and shock occurence from a assumption of ignition during machining in the propellants manufacturing plant, could be obtained. Basic studies were made to prevent pollution in blasting sites. Collected data are utilized for the safety administration after sufficient discussion. (4 figs, 2 tabs, 3 photos, 17 refs)

Augmentation of DAA Staggered – Solution Equations in Underwater Shock Problems for Singular Structural Mass Matrices

Directory of Open Access Journals (Sweden)

John A. DeRuntz Jr.

2005-01-01

Full Text Available The numerical solution of underwater shock fluid – structure interaction problems using boundary element/finite element techniques became tractable through the development of the family of Doubly Asymptotic Approximations (DAA. Practical implementation of the method has relied on the so-called augmentation of the DAA equations. The fluid and structural systems are respectively coupled by the structural acceleration vector in the surface normal direction on the right hand side of the DAA equations, and the total pressure applied to the structural equations on its right hand side. By formally solving for the acceleration vector from the structural system and substituting it into its place in the DAA equations, the augmentation introduces a term involving the inverse of the structural mass matrix. However there exist at least two important classes of problems in which the structural mass matrix is singular. This paper develops a method to carry out the augmentation for such problems using a generalized inverse technique.

Kaliski's explosive driven fusion experiments

International Nuclear Information System (INIS)

Marshall, J.

1979-01-01

An experiment performed by a group in Poland on the production of DD fusion neutrons by purely explosive means is discussed. A method for multiplying shock velocities ordinarily available from high explosives by a factor of ten is described, and its application to DD fusion experiments is discussed

Penetration Evaluation of Explosively Formed Projectiles Through Air and Water Using Insensitive Munition: Simulative and Experimental Studies

Directory of Open Access Journals (Sweden)

M. Ahmed

2016-02-01

Full Text Available The process of formation, flying, penetration of explosively-formed projectiles (EFP and the effect of water on performance of the charge for underwater applications is simulated by Ansysis Autodyn 2D-Hydro code. The main objective of an explosively formed projectile designed for underwater applications is to disintegrate the target at longer standoff distances. In this paper we have simulated the explosively formed projectile from OFHC-Copper liner for 1200 conical angle. The Affect of water on the penetration of EFP is determined by simulations from Ansysis Autodyn 2-D Hydrocode and by varying depth of water from 1CD-5CD. The depth of penetration against steel target is measured experimentally. Flash X-Ray Radiography (FXR is used to capture EFP jet formation and its penetration against target is measured by depth of penetration experiments. Simulation results are compared with experimental results. The difference in simulated and experimental results for depth of penetration is about 7 mm, which lies within favorable range of error. The jet formation captured from FXR is quite clear and jet velocity determined from Flash X-ray radiography is the same as the ones obtained by using other high explosives. Therefore, it is indicated that Insensitive Munition (8701 can be utilized instead of Polymer Bonded Explosives (PBX for air and underwater environments with great reliability and without any hazard.

Experimental and Theoretical Investigation of Shock-Induced Reactions in Energetic Materials

Energy Technology Data Exchange (ETDEWEB)

Kay, Jeffrey J. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Park, Samuel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kohl, Ian Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knepper, Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Farrow, Darcie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tappan, Alexander S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-09-01

In this work, shock-induced reactions in high explosives and their chemical mechanisms were investigated using state-of-the-art experimental and theoretical techniques. Experimentally, ultrafast shock interrogation (USI, an ultrafast interferometry technique) and ultrafast absorption spectroscopy were used to interrogate shock compression and initiation of reaction on the picosecond timescale. The experiments yielded important new data that appear to indicate reaction of high explosives on the timescale of tens of picoseconds in response to shock compression, potentially setting new upper limits on the timescale of reaction. Theoretically, chemical mechanisms of shock-induced reactions were investigated using density functional theory. The calculations generated important insights regarding the ability of several hypothesized mechanisms to account for shock-induced reactions in explosive materials. The results of this work constitute significant advances in our understanding of the fundamental chemical reaction mechanisms that control explosive sensitivity and initiation of detonation.

Off-center point explosion in a spheroid

International Nuclear Information System (INIS)

Morita, Kazuhiko; Sakashita, Shiro

1978-01-01

An off-center point explosion in a spheroid with exponential or Gaussian density distribution is investigated by applying the generalized Laumbach and Probstein method. For a typical example, we calculate the explosion in a spheroid with the eccentricity e = 0.7. If the separation distance between the center of the spheroid and the explosion point is larger than three times of the density scale height, the shock wave may almost propagate toward the direction of the minor axis of symmetry, within the polar angle of 30 0 . The shock envelope elongates toward the same direction and may form a polar jet and/or a tilted jet. But, in the case of an explosion in the equatorial plane (perpendicular to the minor axis of symmetry), two plasmas with the same form may be ejected into two different directions with the angle smaller than 180 0 . Explosion models of double radio sources and related objects are suggested. (author)

Close-in airblast from underground explosions

Energy Technology Data Exchange (ETDEWEB)

Vortman, L J [Sandia Laboratories, Albuquerque, NM (United States)

1970-05-15

Air overpressures as a function of time have been measured from surface zero to about 170 ft/lb{sup 1/3} along the ground from nuclear and chemical explosions. Charge depths varied from the surface to depths below which explosion gases are contained. A ground-shock-induced air pressure pulse is clearly distinguishable from the pulse caused by venting gases. Measured peak overpressures show reasonable agreement with the theoretical treatment by Monta. In a given medium the suppression of blast with explosion burial depth is a function of the relative distance at which the blast is observed. Rates of suppression of peak overpressure with charge burial are different for the two pulses. Rates are determined for each pulse over the range of distances at which measurements have been made of air overpressure from chemical explosions in several media. Nuclear data are available from too few shots for similar dependence on burial depth and distance to be developed, but it is clear that the gas venting peak overpressure from nuclear explosions is much more dependent on medium than that from chemical explosions. For above-ground explosions, experiment has shown that airblast from a I-kiloton nuclear explosion is equal to that from a 0.5-kiloton TNT explosion. Data on ground-shock-induced airblast is now sufficient to show that a similar relationship may exist for buried explosions. Because of medium dependence of the gas venting pulse from nuclear explosions, data from additional nuclear events will be required before a chemical/nuclear airblast equivalence can be determined for the gas-venting pulse. (author)

Procalcitonin as a diagnostic biomarker for septic shock and bloodstream infection in burn patients from the Formosa Fun Coast dust explosion

Directory of Open Access Journals (Sweden)

Rui-Xin Wu

2017-12-01

Full Text Available Background/Purpose: Infection is the most common cause of death following burn injury. The study was conducted to compare the diagnostic value of serum procalcitonin (PCT with the other current benchmarks as early predictors of septic shock and bloodstream infection in burn patients. Methods: We included 24 patients admitted to the Burn Unit of a medical center from June 2015 to December 2015 from the Formosa Fun Coast dust explosion. We categorized all patients at initial admission into either sepsis or septic shock groups. Laboratory tests including the worst PCT and C-reactive protein (CRP levels, platelet (PLT, and white blood cell (WBC count were performed at <48 h after admission. Patients were also classified in two groups with subsequent bacteremia and non-bacteremia groups during hospitalization. Results: Significantly higher PCT levels were observed among participants with septic shock compared to those with sepsis (47.19 vs. 1.18 ng/mL, respectively; p < 0.001. Patients with bacteremia had significantly elevated PCT levels compared to patients without bacteremia (29.54 versus 1.81 ng/mL, respectively, p < 0.05. No significant differences were found in CRP levels, PLT, and WBC count between the two groups. PCT levels showed reasonable discriminative power (cut-off: 5.12 ng/mL; p = 0.01 in predicting of bloodstream infection in burn patients and the area under receiver operating curves was 0.92. Conclusions: PCT levels can be helpful in determining the septic shock and bloodstream infection in burn patients but CRP levels, PLT, and WBC count were of little diagnostic value. Keywords: Procalcitonin, Septic shock, Bloodstream infection, Burn patient, Formosa fun coast dust explosion

The CREST reactive-burn model for explosives

Directory of Open Access Journals (Sweden)

Maheswaran M-A.

2011-01-01

Full Text Available CREST is an innovative reactive-burn model that has been developed at AWE for simulating shock initiation and detonation propagation behaviour in explosives. The model has a different basis from other reactive-burn models in that its reaction rate is independent of local flow variables behind the shock wave e.g. pressure and temperature. The foundation for CREST, based on a detailed analysis of data from particle-velocity gauge experiments, is that the reaction rate depends only on the local shock strength and the time since the shock passed. Since a measure of shock strength is the entropy of the non-reacted explosive, which remains constant behind a shock, CREST uses an entropy-dependent reaction rate. This paper will provide an overview of the CREST model and its predictive capability. In particular, it will be shown that the model can predict a wide range of experimental phenomena for both shock initiation (e.g. the effects of porosity and initial temperature on sustained-shock and thin-flyer initiation and detonation propagation (e.g. the diameter effect curve and detonation failure cones using a single set of coefficients.

Spall strength and ejecta production of gold under explosively driven shock wave compression

International Nuclear Information System (INIS)

La Lone, B. M.; Stevens, G. D.; Turley, W. D.; Veeser, L. R.; Holtkamp, D. B.

2013-01-01

Explosively driven shock wave experiments were conducted to characterize the spall strength and ejecta production of high-purity cast gold samples. The samples were from 0.75 to 1.84 mm thick and 30 mm in diameter. Peak stresses up to 44 GPa in gold were generated using PBX-9501 high explosive. Sample free surface and ejecta velocities were recorded using photonic Doppler velocimetry techniques. Lithium niobate pins were used to quantify the time dependence of the ejecta density and the total ejected mass. An optical framing camera for time-resolved imaging and a single-image x-ray radiograph were used for additional characterization. Free surface velocities exhibited a range of spall strengths from 1.7 to 2.4 GPa (mean: 2.0 ±0.3 GPa). The pullback signals were faint, minimal ringing was observed in the velocity records, and the spall layer continued to decelerate after first pull back. These results suggest finite tensile strength was present for some time after the initial void formation. Ejecta were observed for every sample with a roughened free surface, and the ejecta density increased with increased surface roughness, which was different in every experiment. The total ejected mass is consistent with the missing mass model.

Pyroshock Prediction of Ridge-Cut Explosive Bolts Using Hydrocodes

Directory of Open Access Journals (Sweden)

Juho Lee

2016-01-01

Full Text Available Pyrotechnic release devices such as explosive bolts are prevalent for many applications due to their merits: high reliability, high power-to-weight ratio, reasonable cost, and more. However, pyroshock generated by an explosive event can cause failures in electric components. Although pyroshock propagations are relatively well understood through many numerical and experimental studies, the prediction of pyroshock generation is still a very difficult problem. This study proposes a numerical method for predicting the pyroshock of a ridge-cut explosive bolt using a commercial hydrocode (ANSYS AUTODYN. A numerical model is established by integrating fluid-structure interaction and complex material models for high explosives and metals, including high explosive detonation, shock wave transmission and propagation, and stress wave propagation. To verify the proposed numerical scheme, pyroshock measurement experiments of the ridge-cut explosive bolts with two types of surrounding structures are performed using laser Doppler vibrometers (LDVs. The numerical analysis results provide accurate prediction in both the time (acceleration and frequency domains (maximax shock response spectra. In maximax shock response spectra, the peaks due to vibration modes of the structures are observed in both the experimental and numerical results. The numerical analysis also helps to identify the pyroshock generation source and the propagation routes.

Premixing and steam explosion phenomena in the tests with stratified melt-coolant configuration and binary oxidic melt simulant materials

Energy Technology Data Exchange (ETDEWEB)

Kudinov, Pavel, E-mail: pavel@safety.sci.kth.se; Grishchenko, Dmitry, E-mail: dmitry@safety.sci.kth.se; Konovalenko, Alexander, E-mail: kono@kth.se; Karbojian, Aram, E-mail: karbojan@kth.se

2017-04-01

Highlights: • Steam explosion in stratified melt-coolant configuration is studied experimentally. • Different binary oxidic melt simulant materials were used. • Five spontaneous steam explosions were observed. • Instability of melt-coolant interface and formation of premixing layer was observed. • Explosion strength is influenced by melt superheat and water subcooling. - Abstract: Steam explosion phenomena in stratified melt-coolant configuration are considered in this paper. Liquid corium layer covered by water on top can be formed in severe accident scenarios with (i) vessel failure and release of corium melt into a relatively shallow water pool; (ii) with top flooding of corium melt layer. In previous assessments of potential energetics in stratified melt-coolant configuration, it was assumed that melt and coolant are separated by a stable vapor film and there is no premixing prior to the shock wave propagation. This assumption was instrumental for concluding that the amount of energy that can be released in such configuration is not of safety importance. However, several recent experiments carried out in Pouring and Under-water Liquid Melt Spreading (PULiMS) facility with up to 78 kg of binary oxidic corium simulants mixtures have resulted in spontaneous explosions with relatively high conversion ratios (order of one percent). The instability of the melt-coolant interface, melt splashes and formation of premixing layer were observed in the tests. In this work, we present results of experiments carried out more recently in steam explosion in stratified melt-coolant configuration (SES) facility in order to shed some light on the premixing phenomena and assess the influence of the test conditions on the steam explosion energetics.

Dynamic testing of adhesive joints using a shock testing machine

NARCIS (Netherlands)

Aanhold, J.E. van; Weersink, A.F.J.; Ludolphy, J.W.L.

1998-01-01

A light-weight shock testing machine, designed for type approval testing of naval equipment up to 300 kg mass, has been modified into a dynamic tensile test rig. This enables to test structural details for high rate dynamic tensile loadings such as occur during underwater shock. The maximum capacity

HERMES: A Model to Describe Deformation, Burning, Explosion, and Detonation

Energy Technology Data Exchange (ETDEWEB)

Reaugh, J E

2011-11-22

HERMES (High Explosive Response to MEchanical Stimulus) was developed to fill the need for a model to describe an explosive response of the type described as BVR (Burn to Violent Response) or HEVR (High Explosive Violent Response). Characteristically this response leaves a substantial amount of explosive unconsumed, the time to reaction is long, and the peak pressure developed is low. In contrast, detonations characteristically consume all explosive present, the time to reaction is short, and peak pressures are high. However, most of the previous models to describe explosive response were models for detonation. The earliest models to describe the response of explosives to mechanical stimulus in computer simulations were applied to intentional detonation (performance) of nearly ideal explosives. In this case, an ideal explosive is one with a vanishingly small reaction zone. A detonation is supersonic with respect to the undetonated explosive (reactant). The reactant cannot respond to the pressure of the detonation before the detonation front arrives, so the precise compressibility of the reactant does not matter. Further, the mesh sizes that were practical for the computer resources then available were large with respect to the reaction zone. As a result, methods then used to model detonations, known as {beta}-burn or program burn, were not intended to resolve the structure of the reaction zone. Instead, these methods spread the detonation front over a few finite-difference zones, in the same spirit that artificial viscosity is used to spread the shock front in inert materials over a few finite-difference zones. These methods are still widely used when the structure of the reaction zone and the build-up to detonation are unimportant. Later detonation models resolved the reaction zone. These models were applied both to performance, particularly as it is affected by the size of the charge, and to situations in which the stimulus was less than that needed for reliable

Vapor explosion studies for nuclear and non-nuclear industries

Energy Technology Data Exchange (ETDEWEB)

Taleyarkhan, Rusi P. [Arden L. Bement, Jr. Professor Nuclear Engineering, School of Nuclear Engineering, 1290 Nuclear Engineering Building, Room 108C, Purdue University, West Lafayette, IN 47905 (United States)]. E-mail: rusi@purdue.edu

2005-05-01

Energetic melt-water explosions are a well-established contributor to risk for nuclear reactors, and even more so for the metal casting industry. In-depth studies were undertaken in an industry-national laboratory collaborative effort to understand the root causes of explosion triggering and to evaluate methods for prevention. The steam explosion triggering studies (SETS) facility was devised and implemented for deriving key insights into explosion prevention. Data obtained indicated that onset of base surface-entrapment induced explosive boiling-caused trigger shocks is a result of complex combination of surface wettability, type of coating (organic versus inorganic), degree of coating wearoff, existence of bypass pathways for pressure relief, charring and non-condensable gas (NCG) release potential. Of these parameters NCGs were found to play a preeminent role on explosion prevention by stabilizing the melt-water steam interface and acting as a shock absorber. The role of NCGs was experimentally confirmed using SETS for their effect on stable film boiling using a downward facing heated body through which gases were injected. The presence of NCGs in the steam film layer caused a significant delay in the transitioning of film-to-nucleate boiling. The role of NCGs on explosion prevention was thereafter demonstrated more directly by introducing molten metal drops into water pools with and without NCG bubbling. Whereas spontaneous and energetic explosions took place without NCG injection, only benign quenching occurred in the presence of NCGs. Gravimetric analyses of organic coatings which are known to prevent explosion onset were also found to release significant NCGs during thermal attack by melt in the presence of water. These findings offer a novel, simple, cost-effective technique for deriving fundamental insights into melt-water explosions as well as for explosion prevention under most conditions of interest to metal casting, and possibly for nuclear reactor

Three-dimensional simulations of core-collapse supernovae: from shock revival to shock breakout

Science.gov (United States)

Wongwathanarat, A.; Müller, E.; Janka, H.-Th.

2015-05-01

We present three-dimensional hydrodynamic simulations of the evolution of core-collapse supernovae (SN) from blast-wave initiation by the neutrino-driven mechanism to shock breakout from the stellar surface, using an axis-free Yin-Yang grid and considering two 15 M⊙ red supergiants (RSG) and two blue supergiants (BSG) of 15 M⊙ and 20 M⊙. We demonstrate that the metal-rich ejecta in homologous expansion still carry fingerprints of asymmetries at the beginning of the explosion, but the final metal distribution is massively affected by the detailed progenitor structure. The most extended and fastest metal fingers and clumps are correlated with the biggest and fastest-rising plumes of neutrino-heated matter, because these plumes most effectively seed the growth of Rayleigh-Taylor (RT) instabilities at the C+O/He and He/H composition-shell interfaces after the passage of the SN shock. The extent of radial mixing, global asymmetry of the metal-rich ejecta, RT-induced fragmentation of initial plumes to smaller-scale fingers, and maximum Ni and minimum H velocities depend not only on the initial asphericity and explosion energy (which determine the shock and initial Ni velocities), but also on the density profiles and widths of C+O core and He shell and on the density gradient at the He/H transition, which leads to unsteady shock propagation and the formation of reverse shocks. Both RSG explosions retain a large global metal asymmetry with pronounced clumpiness and substructure, deep penetration of Ni fingers into the H-envelope (with maximum velocities of 4000-5000 km s-1 for an explosion energy around 1.5 bethe) and efficient inward H-mixing. While the 15 M⊙ BSG shares these properties (maximum Ni speeds up to ~3500 km s-1), the 20 M⊙ BSG develops a much more roundish geometry without pronounced metal fingers (maximum Ni velocities only ~2200 km s-1) because of reverse-shock deceleration and insufficient time for strong RT growth and fragmentation at the He

An integral condition for core-collapse supernova explosions

International Nuclear Information System (INIS)

Murphy, Jeremiah W.; Dolence, Joshua C.

2017-01-01

Here, we derive an integral condition for core-collapse supernova (CCSN) explosions and use it to construct a new diagnostic of explodability. The fundamental challenge in CCSN theory is to explain how a stalled accretion shock revives to explode a star. In this manuscript, we assume that the shock revival is initiated by the delayed-neutrino mechanism and derive an integral condition for spherically symmetric shock expansion, v_s > 0. One of the most useful one-dimensional explosion conditions is the neutrino luminosity and mass-accretion rate (L_ν-- M-dot ) critical curve. Below this curve, steady-state stalled solutions exist, but above this curve, there are no stalled solutions. Burrows & Goshy suggested that the solutions above this curve are dynamic and explosive. In this manuscript, we take one step closer to proving this supposition; we show that all steady solutions above this curve have v_s > 0. Assuming that these steady v_s > 0 solutions correspond to explosion, we present a new dimensionless integral condition for explosion, Ψ > 0. Ψ roughly describes the balance between pressure and gravity, and we show that this parameter is equivalent to the τ condition used to infer the L_ν-- M-dot critical curve. The illuminating difference is that there is a direct relationship between Ψ and v_s. Below the critical curve, Ψ may be negative, positive, and zero, which corresponds to receding, expanding, and stalled-shock solutions. At the critical curve, the minimum Ψ solution is zero; above the critical curve, Ψ_m_i_n > 0, and all steady solutions have v_s > 0. Using one-dimensional simulations, we confirm our primary assumptions and verify that Ψ_m_i_n > 0 is a reliable and accurate explosion diagnostic.

Explosions on a gas-vacuum interface

International Nuclear Information System (INIS)

Nutt, G.; Klein, L.; Ratcliffe, A.E.

1981-01-01

A finite-difference computer code is used to calculate the time development of an explosion on a gas-vacuum interface. An analytic theory of the shape of the shock wave produced in the explosion is compared with the results of the computer simulation. The assumptions used in obtaining this analytic solution are verified, and the degree to which the variables describing the explosion are self-similar is examined. Finally, certain consistency relations among the similarity exponents are tested

Shock Dynamics in Stellar Outbursts. I. Shock Formation

Energy Technology Data Exchange (ETDEWEB)

Ro, Stephen; Matzner, Christopher D., E-mail: ro@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada)

2017-05-20

Wave-driven outflows and non-disruptive explosions have been implicated in pre-supernova outbursts, supernova impostors, luminous blue variable eruptions, and some narrow-line and superluminous supernovae. To model these events, we investigate the dynamics of stars set in motion by strong acoustic pulses and wave trains, focusing on nonlinear wave propagation, shock formation, and an early phase of the development of a weak shock. We identify the shock formation radius, showing that a heuristic estimate based on crossing characteristics matches an exact expansion around the wave front and verifying both with numerical experiments. Our general analytical condition for shock formation applies to one-dimensional motions within any static environment, including both eruptions and implosions. We also consider the early phase of shock energy dissipation. We find that waves of super-Eddington acoustic luminosity always create shocks, rather than damping by radiative diffusion. Therefore, shock formation is integral to super-Eddington outbursts.

The Air Blast Wave from a Nuclear Explosion

Science.gov (United States)

Reines, Frederick

The sudden, large scale release of energy in the explosion of a nuclear bomb in air gives rise, in addition to nuclear emanations such as neutrons and gamma rays, to an extremely hot, rapidly expanding mass of air.** The rapidly expanding air mass has an initial temperature in the vicinity of a few hundred thousand degrees and for this reason it glows in its early stages with an intensity of many suns. It is important that the energy density in this initial "ball of fire" is of the order of 3 × 103 times that found in a detonating piece of TNT and hence that the initial stages of the large scale air motion produced by a nuclear explosion has no counterpart in an ordinary. H. E. explosion. Further, the relatively low temperatures ˜2,000°C associated with the initial stages of an H. E. detonation implies that the thermal radiation which it emits is a relatively insignificant fraction of the total energy involves. This point is made more striking when it is remembered that the thermal energy emitted by a hot object varies directly with the temperature in the Rayleigh Jeans region appropriate to the present discussion. The expansion of the air mass heated by the nuclear reaction produces, in qualitatively the same manner as in an H.E. explosion or the bursting of a high pressure balloon, an intense sharp pressure pulse, a shock wave, in the atmosphere. As the pressure pulse spreads outward it weakens due to the combined effects of divergence and the thermodynamically irreversible nature of the shock wave. The air comprising such a pressure pulse or blast wave moves first radially outward and then back towards the center as the blast wave passes. Since a permanent outward displacement of an infinite mass of air would require unlimited energy, the net outward displacement of the air distant from an explosion must approach zero with increasing distance. As the distance from the explosion is diminished the net outward displacement due to irreversible shock heating of

Glass produced by underground nuclear explosions

International Nuclear Information System (INIS)

Schwartz, L.; Piwinskii, A.; Ryerson, F.; Tewes, H.; Beiriger, W.

1983-01-01

Detonation of an underground nuclear explosive produces a strong shock wave which propagates spherically outward, vaporizing the explosive and nearby rock and melting, the surrounding rock. The vaporized material expands adiabatically, forming a cavity. As the energy is dissipated during the cavity formation process, the explosive and rock debris condense and mix with the melted rock. The melt flows to the bottom of the cavity where it is quenched by fractured rock fragments falling from above as the cavity collapses. Measurements indicate that about 740 tonnes of rock and/or soil are melted for every kiloton (10 12 calories) of explosive energy, or about 25% of the explosive energy goes to melting rock. The resulting glass composition reflects the composition of the unaltered rock with explosive debris. The appearance ranges from white pumice to dense, dark lava. The bulk composition and color vary with the amount of explosive iron incorporated into the glass. The refractory explosion products are mixed with the solidified melt, although the degree of mixing is variable. Electron microprobe studies of glasses produced by Rainier in welded tuff have produced the following results: glasses are dehydrated relative to the host media, glasses are extremely heterogeneous on a 20 μm scale, a ubiquitous feature is the presence of dark marble-cake regions in the glass, which were locally enriched in iron and may be related to the debris, optically amorphous regions provide evidence of shock melting, only limited major element redistribution and homogenization occur within the cavity

Contribution to the study of detonation initiation by shock in solid explosives (1961); Contribution a l'etude de l'initiation de la detonation par choc dans les explosifs solides (1961)

Energy Technology Data Exchange (ETDEWEB)

Fauquignon, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-05-15

When a shock wave is induced in an explosive, it can initiate chemical reactions which lead more or less rapidly to a stable detonation state. In this study more particular attention was paid to the transition phase, in which has been evaluated the increases in the wave velocity, the pressure, and the electrical conductivity. The influence of the nature of the medium in front of the wave and in contact with the explosive has also been the subject of an experimental study designed to determine the extent to which its nature can be ignored and, subsequently, to characterise the initiation conditions using only the shock intensity induced in the explosive. Finally, the results were generalized for various explosive compositions and led to the development of a possible mechanism for shock initiation. (author) [French] Lorsqu'une onde de choc est induite dans un explosif, elle peut y amorcer des reactions chimiques qui conduisent plus ou moins rapidement a un regime de detonation stable. Dans cette etude, on s'est interesse plus particulierement a la phase transitoire dans laquelle on a evalue l'accroissement de la vitesse d'onde, de la pression et de la conductibilite electrique. L'influence du milieu amont, au contact de l'explosif, a egalement fait l'objet de recherches experimentales de facon a determiner dans quelle mesure on pouvait s'affranchir de sa nature et, par suite, caracteriser les conditions d'initiation par la seule intensite du choc induit dans l'explosif. Enfin, les resultats ont ete generalises a diverses compositions explosives et ont conduit a l'elaboration d'un schema possible du mecanisme de l'initiation par choc. (auteur)

History of Shock Waves, Explosions and Impact A Chronological and Biographical Reference

CERN Document Server

Krehl, Peter O. K

2009-01-01

This unique and encyclopedic reference work charts the evolution of the physics of shock waves and detonations from the earliest investigations into percussion and impact phenomena right up to the most recent groundbreaking research in the field. The history of this long and complex process is first reviewed in a general survey that encompasses everything from the earliest observations and interpretations of puzzling high-rate dynamic phenomena associated with natural and man-made explosions to a discussion of the merits of modern numerical computer simulations. The subject is then treated in more detail and in chronological order in the central section of the book, while also being richly illustrated in form of a picture gallery. The bibliographic index provides 122 short biographies of eminent researchers who have contributed to the field. Further references for biographical sources are given, and both name and subject indices (with over 4500 and 2700 entries, respectively) are provided. "This book is of tr...

Diver Operated Tools and Applications for Underwater Construction

Science.gov (United States)

1987-01-01

Performing underwater tasks can distract the diver from observing mandatory safety precautions and therefore he must be hlert and knowledgeable about...Insulating layer when heat loss, their blood flow is reduced to protect the core. Entry into cold water is itself a shock that can distract Once in the...torahhesfc. fotadpossibly a minor case of hemorrhage into the If the maxillary sinus is involved, the blood supply to skin from pinching, the inf

Shocks near Jamming

Science.gov (United States)

Gómez, Leopoldo R.; Turner, Ari M.; van Hecke, Martin; Vitelli, Vincenzo

2012-02-01

Nonlinear sound is an extreme phenomenon typically observed in solids after violent explosions. But granular media are different. Right when they jam, these fragile and disordered solids exhibit a vanishing rigidity and sound speed, so that even tiny mechanical perturbations form supersonic shocks. Here, we perform simulations in which two-dimensional jammed granular packings are dynamically compressed and demonstrate that the elementary excitations are strongly nonlinear shocks, rather than ordinary phonons. We capture the full dependence of the shock speed on pressure and impact intensity by a surprisingly simple analytical model.

Explosive nucleosynthesis in a neutrino-driven core collapse supernova

International Nuclear Information System (INIS)

Fujimoto, Shin-ichiro; Kotake, Kei; Hashimoto, Masa-aki; Ono, Masaomi; Ohnishi, Naofumi

2010-01-01

We investigate explosive nucleosynthesis in a delayed neutrino-driven, supernova explosion aided by standing accretion shock instability (SASI), based on two-dimensional hydrodynamic simulations of the explosion of a 15 M · star. We take into accounts neutrino heating and cooling as well as change in electron fraction due to weak interactions appropriately, in the two-dimensional simulations. We assume the isotropic emission of neutrinos from the neutrino spheres with given luminosities. and the Fermi-Dirac distribution of given temperatures. We find that the stalled shock revives due to the neutrino heating aided by SASI for cases with L νe ≥3.9x10 52 ergss -1 and the as-pherical shock passes through the outer layers of the star (≥10,000 km), with the explosion energies of ∼10 51 ergs.Next we examine abundances and masses of the supernova ejecta. We find that masses of the ejecta and 56 Ni correlate with the neutrino luminosity, and 56 Ni mass is comparable to that observed in SN 1987A. We also find that abundance pattern of the supernova ejecta is similar to that of the solar system, for cases with high explosion energies of >10 51 ergs. We emphasize that 64 Zn, which is underproduced in the spherical case, is abundantly produced in slightly neutron-rich ejecta.

Explosive composition with group VIII metal nitroso halide getter

Science.gov (United States)

Walker, F.E.; Wasley, R.J.

1982-06-22

An improved explosive composition is disclosed and comprises a major portion of an explosive having a detonation velocity between about 1,500 and 10,000 meters per second and a minor amount of a getter additive comprising a non-explosive compound or mixture of non-explosive compounds capable of chemically reacting with free radicals or ions under shock initiation conditions of 2,000 calories/cm[sup 2] or less of energy fluence.

Explosive compaction of aluminum oxide modified by multiwall carbon nanotubes

Science.gov (United States)

Buzyurkin, A. E.; Kraus, E. I.; Lukyanov, Ya L.

2018-04-01

This paper presents experiments and numerical research on explosive compaction of aluminum oxide powder modified by multiwall carbon nanotubes (MWCNT) and modeling of the stress state behind the shock front at shock loading. The aim of this study was to obtain a durable low-porosity compact sample. The explosive compaction technology is used in this problem because the aluminum oxide is an extremely hard and refractory material. Therefore, its compaction by traditional methods requires special equipment and considerable expenses.

Design Level Ship Shock Simulation of USS WINSTON S. CHURCHILL (DDG-81)

National Research Council Canada - National Science Library

Fensterer, William

2004-01-01

.... The Navy selected the Arleigh Burke class destroyer, USS WINSTON S. CHURCHILL (DDG-81), as the most recent platform and subjected it to an underwater explosion two-thirds the magnitude of the design level shot...

EXPLOSION OF ANNULAR CHARGE ON DUSTY SURFASE

Directory of Open Access Journals (Sweden)

A. Levin Vladimir

2017-01-01

Full Text Available This problem is related to the safety problem in the area of forest fires. It is well known that is possible to extinguish a fire, for example, by means of a powerful air stream. Such flow arises from the explosive shock wave. To enhance the im- pact of the blast wave can be used an explosive charge of annular shape. The shock wave, produced by the explosion, in- creased during moves to the center and can serve as a means of transportation dust in the seat of the fire. In addition, emerging after the collapse of a converging shock wave strong updraft can raise dust on a greater height and facilitate fire extinguishing, precipitating dust over a large area. This updraft can be dangerous for aircraft that are in the sky above the fire. To determine the width and height of the danger zone performed the numerical simulation of the ring of the explosion and the subsequent movement of dust and gas mixtures. The gas is considered ideal and perfect. The explosion is modeled as an instantaneous increase in the specific internal energy in an annular zone on the value of the specific heat of explosives. The flow is consid- ered as two-dimensional, and axisymmetric. The axis of symmetry perpendicular to the Earth surface. This surface is considered to be absolutely rigid and is considered as the boundary of the computational domain. On this surface is exhibited the condition of no motion. For the numerical method S. K. Godunov is used a movable grid. One system of lines of this grid is moved in accordance with movement of the shock wave. Others lines of this grid are stationary. The calculations were per- formed for different values of the radii of the annular field and for different sizes of rectangular cross-sectional of the annular field. Numerical results show that a very strong flow is occurring near the axis of symmetry and the particles rise high above the surface. These calculations allow us to estimate the sizes of the zone of danger in specific

Liquid-liquid contact in vapor explosion

International Nuclear Information System (INIS)

Segev, A.

1978-08-01

The contact of two liquid materials, one of which is at a temperature substantially above the boiling point of the other, can lead to fast energy conversion and a subsequent shock wave. This phenomenon is called a vapor explosion. One method of producing intimate, liquid-liquid contact (which is known to be a necessary condition for vapor explosion) is a shock tube configuration. Such experiments in which water was impacted upon molten aluminum showed that very high pressures, even larger than the thermodynamic critical pressure, could occur. The mechanism by which such sharp pressure pulses are generated is not yet clear. The report describes experiments in which cold liquids (Freon-11, Freon-22, water, or butanol) were impacted upon various hot materials

Experimental study on scale removal from special-shaped conduits through underwater electrical discharge

International Nuclear Information System (INIS)

Cao, Y; Wang, Z Q; Li, G F; Wu, Y; Zhou, J J

2013-01-01

Underwater electrical discharge technology is an innovative technique that can be used to enhance the stress intensity of water and improve the load addition. The technique enlarges the section area and compresses the surrounding water using a high-powered shock wave, which is induced by an underwater electrical discharge. This paper investigates the effectiveness of scale removal for special-shaped conduits employing underwater electrical discharge. Experimental results show that the pressure wave generated by underwater electrical discharge is capable of eliminating scale in special-shaped conduits. The data indicates that when the capacitance of the parallel-pulsed capacitors was 4 μF, the high pulsed power voltage was 33 kV and the primary discharge gap was 48 mm, the result of scale removal was remarkable. In laboratory tests, the scale of special equipment was removed to a great extent by this method. Because of its effectiveness and low cost, this method improves the practice and extends the lifetime of such equipment, and thus has potential application and economic value.

Transmission characteristics of the kinematics of the laser-plasma shock wave in air in compton scattering

International Nuclear Information System (INIS)

Hao Dongshan; Xie Hongjun

2006-01-01

By comparing the kinematical equation of a shock wave in free air, the study of transmission characteristics of the laser plasma shock wave in Compton scattering is presented. The results show that the attenuation course of the kinematics of he laser plasma shock wave is related not only with the explosion fountainhead and the characteristics of the explosion course, total energy release, air elastic, but also with multi-photon nonlinear Compton scattering. Because of the scattering the initial radius of the shock wave increases, the attenuation course shortens, the energy metastasis efficiency rises. The results of the numerical analysis and the actual values of the shock waves in air by a way intense explosion are very tallying. (authors)

Electromagnetically driven radiative shocks and their measurements

International Nuclear Information System (INIS)

Kondo, K.; Watanabe, M.; Nakajima, M.; Kawamura, T.; Horioka, K.

2005-01-01

Experimental results on a generation of strong shocks in a compact pulse power device are reported. The characteristics of strong shocks are different from hydrodynamical shocks' because they depend on not only collisions but radiation processes. Radiative shocks are relevant to high energy density phenomena such as the explosions of supernovae. When initial pressure is lower than about 50 mtorr, an interesting structure is confirmed at the shock front, which might indicate a phenomenon proceeded by the radiative process. (author)

Contribution to the study of detonation initiation by shock in solid explosives (1961); Contribution a l'etude de l'initiation de la detonation par choc dans les explosifs solides (1961)

Energy Technology Data Exchange (ETDEWEB)

Fauquignon, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-05-15

When a shock wave is induced in an explosive, it can initiate chemical reactions which lead more or less rapidly to a stable detonation state. In this study more particular attention was paid to the transition phase, in which has been evaluated the increases in the wave velocity, the pressure, and the electrical conductivity. The influence of the nature of the medium in front of the wave and in contact with the explosive has also been the subject of an experimental study designed to determine the extent to which its nature can be ignored and, subsequently, to characterise the initiation conditions using only the shock intensity induced in the explosive. Finally, the results were generalized for various explosive compositions and led to the development of a possible mechanism for shock initiation. (author) [French] Lorsqu'une onde de choc est induite dans un explosif, elle peut y amorcer des reactions chimiques qui conduisent plus ou moins rapidement a un regime de detonation stable. Dans cette etude, on s'est interesse plus particulierement a la phase transitoire dans laquelle on a evalue l'accroissement de la vitesse d'onde, de la pression et de la conductibilite electrique. L'influence du milieu amont, au contact de l'explosif, a egalement fait l'objet de recherches experimentales de facon a determiner dans quelle mesure on pouvait s'affranchir de sa nature et, par suite, caracteriser les conditions d'initiation par la seule intensite du choc induit dans l'explosif. Enfin, les resultats ont ete generalises a diverses compositions explosives et ont conduit a l'elaboration d'un schema possible du mecanisme de l'initiation par choc. (auteur)

Underwater robots

CERN Document Server

Antonelli, Gianluca

2014-01-01

This book, now at the third edition, addresses the main control aspects in underwater manipulation tasks. The mathematical model with significant impact on the control strategy is discussed. The problem of controlling a 6-degrees-of-freedoms autonomous underwater vehicle is deeply investigated and a survey of fault detection/tolerant strategies for unmanned underwater vehicles is provided. Inverse kinematics, dynamic and interaction control for underwater vehicle-manipulator systems are then discussed. The code used to generate most of the numerical simulations is made available and briefly discussed.       

Neutrino oscillations in magnetically driven supernova explosions

Energy Technology Data Exchange (ETDEWEB)

Kawagoe, Shio; Kotake, Kei [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo, 181-8588 (Japan); Takiwaki, Tomoya, E-mail: shio.k@nao.ac.jp, E-mail: takiwaki.tomoya@nao.ac.jp, E-mail: kkotake@th.nao.ac.jp [Center for Computational Astrophysics, National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo, 181-8588 (Japan)

2009-09-01

We investigate neutrino oscillations from core-collapse supernovae that produce magnetohydrodynamic (MHD) explosions. By calculating numerically the flavor conversion of neutrinos in the highly non-spherical envelope, we study how the explosion anisotropy has impacts on the emergent neutrino spectra through the Mikheyev-Smirnov-Wolfenstein effect. In the case of the inverted mass hierarchy with a relatively large θ{sub 13} (sin{sup 2} 2θ{sub 13} ∼> 10{sup −3}), we show that survival probabilities of ν-bar {sub e} and ν{sub e} seen from the rotational axis of the MHD supernovae (i.e., polar direction), can be significantly different from those along the equatorial direction. The event numbers of ν-bar {sub e} observed from the polar direction are predicted to show steepest decrease, reflecting the passage of the magneto-driven shock to the so-called high-resonance regions. Furthermore we point out that such a shock effect, depending on the original neutrino spectra, appears also for the low-resonance regions, which could lead to a noticeable decrease in the ν{sub e} signals. This reflects a unique nature of the magnetic explosion featuring a very early shock-arrival to the resonance regions, which is in sharp contrast to the neutrino-driven delayed supernova models. Our results suggest that the two features in the ν-bar {sub e} and ν{sub e} signals, if visible to the Super-Kamiokande for a Galactic supernova, could mark an observational signature of the magnetically driven explosions, presumably linked to the formation of magnetars and/or long-duration gamma-ray bursts.

Neutrino oscillations in magnetically driven supernova explosions

Science.gov (United States)

Kawagoe, Shio; Takiwaki, Tomoya; Kotake, Kei

2009-09-01

We investigate neutrino oscillations from core-collapse supernovae that produce magnetohydrodynamic (MHD) explosions. By calculating numerically the flavor conversion of neutrinos in the highly non-spherical envelope, we study how the explosion anisotropy has impacts on the emergent neutrino spectra through the Mikheyev-Smirnov-Wolfenstein effect. In the case of the inverted mass hierarchy with a relatively large θ13 (sin2 2θ13 gtrsim 10-3), we show that survival probabilities of bar nue and νe seen from the rotational axis of the MHD supernovae (i.e., polar direction), can be significantly different from those along the equatorial direction. The event numbers of bar nue observed from the polar direction are predicted to show steepest decrease, reflecting the passage of the magneto-driven shock to the so-called high-resonance regions. Furthermore we point out that such a shock effect, depending on the original neutrino spectra, appears also for the low-resonance regions, which could lead to a noticeable decrease in the νe signals. This reflects a unique nature of the magnetic explosion featuring a very early shock-arrival to the resonance regions, which is in sharp contrast to the neutrino-driven delayed supernova models. Our results suggest that the two features in the bar nue and νe signals, if visible to the Super-Kamiokande for a Galactic supernova, could mark an observational signature of the magnetically driven explosions, presumably linked to the formation of magnetars and/or long-duration gamma-ray bursts.

Diagnostics of underwater electrical wire explosion through a time- and space-resolved hard x-ray source.

Science.gov (United States)

Sheftman, D; Shafer, D; Efimov, S; Gruzinsky, K; Gleizer, S; Krasik, Ya E

2012-10-01

A time- and space-resolved hard x-ray source was developed as a diagnostic tool for imaging underwater exploding wires. A ~4 ns width pulse of hard x-rays with energies of up to 100 keV was obtained from the discharge in a vacuum diode consisting of point-shaped tungsten electrodes. To improve contrast and image quality, an external pulsed magnetic field produced by Helmholtz coils was used. High resolution x-ray images of an underwater exploding wire were obtained using a sensitive x-ray CCD detector, and were compared to optical fast framing images. Future developments and application of this diagnostic technique are discussed.

Validation of Passive Sampling Devices for Monitoring of Munitions Constituents in Underwater Environments

Science.gov (United States)

2017-09-01

and explosives of concern (MEC) corroding, breaching, and leaking MC into the water column (Darrach, Chutjian, and Plett, 1998; GMI, 2007; Lewis et...underwater UWMM have the potential to corrode, breach, and leak munitions constituents (MCs) such as 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5...Wang et al., 2013), a number of challenges prevent accurate assessment of environmental exposure using traditional water , sediment, and tissue

Modelling cavitating flow around underwater missiles

Directory of Open Access Journals (Sweden)

Fabien Petitpas

2011-12-01

Full Text Available The diffuse interface model of Saurel et al. (2008 is used for the computation of compressible cavitating flows around underwater missiles. Such systems use gas injection and natural cavitation to reduce drag effects. Consequently material interfaces appear separating liquid and gas. These interfaces may have a really complex dynamics such that only a few formulations are able to predict their evolution. Contrarily to front tracking or interface reconstruction method the interfaces are computed as diffused numerical zones, that are captured in a routinely manner, as is done usually with gas dynamics solvers for shocks and contact discontinuity. With the present approach, a single set of partial differential equations is solved everywhere, with a single numerical scheme. This leads to very efficient solvers. The algorithm derived in Saurel et al. (2009 is used to compute cavitation pockets around solid bodies. It is first validated against experiments done in cavitation tunnel at CNU. Then it is used to compute flows around high speed underwater systems (Shkval-like missile. Performance data are then computed showing method ability to predict forces acting on the system.

Initiation of a boiling liquid expanding vapour explosion

Energy Technology Data Exchange (ETDEWEB)

McDevitt, C.A.; Chan, C.K.; Steward, F.R.; Tennankore, K.N.; Venart, J.E.S.

1991-06-01

Boiling liquid expanding vapour explosions (BLEVEs) occur when a pressure liquefied gas tank is burst and the fluid is ejected to the atmosphere. As the liquid is exposed to a lower pressure it boils violently, causing an explosion which destroys the container. One litre tanks were filled with propane or R12, heated, and caused to rupture at specific test conditions to determine the parameters required for a BLEVE. Results showed that the energy stored in the liquid under pressure relative to the liquid at atmospheric conditions was a quantity which can be used to predict a BLEVE for the particular apparatus and conditions used. The possible importance of the development of a shock wave within the container during a BLEVE was noted. A shock tube was used to study the shock waves generated during a BLEVE. Temperature, liquid volume, rupture location, rupture area, and the fluid involved were varied. The pressure was measured vs time for periods immediately after the rupture. Photographs of the formation of pressure waves were obtained using spark Schlieren photography and showed that the BLEVE phenomenon is definitely a shock-related event. Pressure information was also gathered during BLEVEs of one litre cylinders, and this information is compared to that from the shock tube. Shock tube data showed that transverse waves formed from the initial pressure wave could be amplified. 37 refs., 54 figs., 11 tabs.

Seismic verification of underground explosions

International Nuclear Information System (INIS)

Glenn, L.A.

1985-06-01

The first nuclear test agreement, the test moratorium, was made in 1958 and lasted until the Soviet Union unilaterally resumed testing in the atmosphere in 1961. It was followed by the Limited Test Ban Treaty of 1963, which prohibited nuclear tests in the atmosphere, in outer space, and underwater. In 1974 the Threshold Test Ban Treaty (TTBT) was signed, limiting underground tests after March 1976 to a maximum yield of 250 kt. The TTBT was followed by a treaty limiting peaceful nuclear explosions and both the United States and the Soviet Union claim to be abiding by the 150-kt yield limit. A comprehensive test ban treaty (CTBT), prohibiting all testing of nuclear weapons, has also been discussed. However, a verifiable CTBT is a contradiction in terms. No monitoring technology can offer absolute assurance that very-low-yield illicit explosions have not occurred. The verification process, evasion opportunities, and cavity decoupling are discussed in this paper

Shock and Detonation Physics at Los Alamos National Laboratory

Energy Technology Data Exchange (ETDEWEB)

Robbins, David L [Los Alamos National Laboratory; Dattelbaum, Dana M [Los Alamos National Laboratory; Sheffield, Steve A [Los Alamos National Laboratory

2012-08-22

WX-9 serves the Laboratory and the Nation by delivering quality technical results, serving customers that include the Nuclear Weapons Program (DOE/NNSA), the Department of Defense, the Department of Homeland Security and other government agencies. The scientific expertise of the group encompasses equations-of-state, shock compression science, phase transformations, detonation physics including explosives initiation, detonation propagation, and reaction rates, spectroscopic methods and velocimetry, and detonation and equation-of-state theory. We are also internationally-recognized in ultra-fast laser shock methods and associated diagnostics, and are active in the area of ultra-sensitive explosives detection. The facility capital enabling the group to fulfill its missions include a number of laser systems, both for laser-driven shocks, and spectroscopic analysis, high pressure gas-driven guns and powder guns for high velocity plate impact experiments, explosively-driven techniques, static high pressure devices including diamond anvil cells and dilatometers coupled with spectroscopic probes, and machine shops and target fabrication facilities.

Focused tandem shock waves in water and their potential application in cancer treatment

Czech Academy of Sciences Publication Activity Database

Lukeš, Petr; Šunka, Pavel; Hoffer, Petr; Stelmashuk, Vitaliy; Poučková, P.; Zadinová, M.; Zeman, J.; Dibdiak, L.; Kolářová, H.; Tománková, K.; Binder, S.; Beneš, J.

2014-01-01

Roč. 24, č. 1 (2014), s. 51-57 ISSN 0938-1287. [International Symposium on Shock Waves/28./. Manchester, 17.07.2011-22.07.2011] R&D Projects: GA ČR GA202/09/1151 Institutional support: RVO:61389021 Keywords : focused shock waves * underwater discharge * cancer treatment Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.885, year: 2014

Explosion-Induced Implosions of Cylindrical Shell Structures

Science.gov (United States)

Ikeda, C. M.; Duncan, J. H.

2010-11-01

An experimental study of the explosion-induced implosion of cylindrical shell structures in a high-pressure water environment was performed. The shell structures are filled with air at atmospheric pressure and are placed in a large water-filled pressure vessel. The vessel is then pressurized to various levels P∞=αPc, where Pc is the natural implosion pressure of the model and α is a factor that ranges from 0.1 to 0.9. An explosive is then set off at various standoff distances, d, from the model center line, where d varies from R to 10R and R is the maximum radius of the explosion bubble. High-speed photography (27,000 fps) was used to observe the explosion and resulting shell structure implosion. High-frequency underwater blast sensors recorded dynamic pressure waves at 6 positions. The cylindrical models were made from aluminum (diameter D = 39.1 mm, wall thickness t = 0.89 mm, length L = 240 mm) and brass (D = 16.7 mm, t = 0.36 mm, L=152 mm) tubes. The pressure records are interpreted in light of the high-speed movies. It is found that the implosion is induced by two mechanisms: the shockwave generated by the explosion and the jet formed during the explosion-bubble collapse. Whether an implosion is caused by the shockwave or the jet depends on the maximum bubble diameter and the standoff distance.

Shock-induced chemistry in organic materials

Energy Technology Data Exchange (ETDEWEB)

Dattelbaum, Dana M [Los Alamos National Laboratory; Sheffield, Steve [Los Alamos National Laboratory; Engelke, Ray [Los Alamos National Laboratory; Manner, Virginia [Los Alamos National Laboratory; Chellappa, Raja [Los Alamos National Laboratory; Yoo, Choong - Shik [WASHINGTON STATE UNIV

2011-01-20

The combined 'extreme' environments of high pressure, temperature, and strain rates, encountered under shock loading, offer enormous potential for the discovery of new paradigms in chemical reactivity not possible under more benign conditions. All organic materials are expected to react under these conditions, yet we currently understand very little about the first bond-breaking steps behind the shock front, such as in the shock initiation of explosives, or shock-induced reactivity of other relevant materials. Here, I will present recent experimental results of shock-induced chemistry in a variety of organic materials under sustained shock conditions. A comparison between the reactivity of different structures is given, and a perspective on the kinetics of reaction completion under shock drives.

Liquid-liquid contact in vapor explosion. [LMFBR

Energy Technology Data Exchange (ETDEWEB)

Segev, A.

1978-08-01

The contact of two liquid materials, one of which is at a temperature substantially above the boiling point of the other, can lead to fast energy conversion and a subsequent shock wave. This phenomenon is called a vapor explosion. One method of producing intimate, liquid-liquid contact (which is known to be a necessary condition for vapor explosion) is a shock tube configuration. Such experiments in which water was impacted upon molten aluminum showed that very high pressures, even larger than the thermodynamic critical pressure, could occur. The mechanism by which such sharp pressure pulses are generated is not yet clear. The report describes experiments in which cold liquids (Freon-11, Freon-22, water, or butanol) were impacted upon various hot materials (mineral oil, silicone oil, water, mercury, molten Wood's metal or molten salt mixture).

Shot H3837: Darht's First Dual-Axis Explosive Experiment

Science.gov (United States)

Mendez, Jacob; McNeil, Wendy Vogan; Harsh, James; Hull, Lawrence

2011-06-01

Test H3837 was the first explosive shot performed in front of both flash x-ray axes at the Los Alamos Dual Axis Radiographic HydroTest (DARHT) facility. Executed in November 2009, the shot was an explosively-driven metal flyer plate in a series of experiments designed to explore equation-of-state properties of shocked materials. Imaging the initial shock wave traveling through the flyer plate, DARHT Axis II captured the range of motion from the shock front emergence in the flyer to breakout at the free surface; the Axis I pulse provided a perpendicular perspective of the shot at a time coinciding with the third pulse of Axis II. Since the days of the Manhattan Project, penetrating radiography with multiple frames from different viewing angles has remained a high-profile goal at the Laboratory. H3837 is merely the beginning of a bright future for two-axis penetrating radiography.

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

Science.gov (United States)

Yamamoto, Yu

2016-06-01

-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

An assessment of structural response of condensation pool columns in a BWR/MARK II containment to loads resulting from steam explosions

International Nuclear Information System (INIS)

Frid, W.

1989-01-01

The objective is to estimate the amount of molten core debris participating in a postulated propagating large-scale steam explosion that could threaten the integrity of the condensation pool columns in a BWR/MARK II containment. This objective was achieved by examination of the structural response of the columns to shock wave loadings and comparison, on the shock wave energy basis, of a propagating steam explosion to a detonation of TNT. In this connection the fraction of the steam explosion energy which appears in the form of a pressure shock wave was estimated. (orig.)

Shape of shock wave produced by a concentrated impact on a surface

International Nuclear Information System (INIS)

Nutt, G.; Klein, L.

1981-01-01

An approximate similarity solution, derived by Raizer, of a concentrated impact (or intense explosion) at the boundary of a semi-infinite volume of a perfect gas is used to determine the propagation velocity of the shock front as a function of its position. This velocity function is then used to obtain the shape of the propagating shock wave. It is shown that dish-shaped shock fronts are formed when the movement of the gas at the surface is into the gas region and that cup-shaped shock fronts are formed when the movement is out of the gas region. Comparison of these results with the shapes of explosions and meteorite craters are discussed

Warfare Ecology on an Underwater Demolition Range: Acoustic Observations of Marine Life and Shallow Water Detonations in Hawai`i

Science.gov (United States)

Shannon, Lee H.

Most studies investigating the effects of military-associated anthropogenic noise concentrate on deep sea or open ocean propagation of sonar and its effect on marine mammals. In littoral waters, U.S. military special operations units regularly conduct shallow water explosives training, yet relatively little attention has been given to the potential impact on nearshore marine ecosystems from these underwater detonations. This dissertation research focused on the Pu'uloa Underwater Detonation Range off the coast of O`ahu, and examined multiple aspects of the surrounding marine ecosystem and the effects of detonations using acoustic monitoring techniques. The soundscape of a nearshore reef ecosystem adjacent to the UNDET range was characterized through analysis of passive acoustic recordings collected over the span of 6 years. Snapping shrimp were the predominant source of noise, and a diel pattern was present, with increased sound energy during the night hours. Results revealed a difference of up to 7dB between two Ecological Acoustic Recorder locations 2.5km apart along the 60ft isobath. Passive acoustic recording files were searched visually and aurally for odontocete whistles. Whistles were detected in only 0.6% of files analyzed, indicating this area is not frequently transited by coastal odontocete emitting social sounds. The study also opportunistically captured a humpback whale singing during a detonation event, during which the animal showed no obvious alteration of its singing behavior. Four separate underwater detonation events were recorded using a surface deployed F-42C transducer, and the resulting analysis showed no measurable drop in the biologically produced acoustic energy in reaction to the explosive events. Coral reef fishes were recorded visually and acoustically during detonation events at a known distance and bearing from a known explosive sound source. Individual fish behavioral responses to the explosion varied, and a sharp uptick in fish

Study of nano-nitramine explosives: preparation, sensitivity and application

Directory of Open Access Journals (Sweden)

Jie Liu

2014-06-01

Full Text Available Nano-nitramine explosives (RDX, HMX, CL-20 are produced on a bi-directional grinding mill. The scanning electron microscope (SEM observations show that the prepared particles are semi-spherical, and the narrow size distributions are characterized using the laser particle size analyzer. Compared with the micron-sized samples, the nano-products show obvious decrease in friction and impact sensitivities. In the case of shock sensitivities, nano-products have lower values by 59.9% (RDX, 56.4% (HMX, and 58.1% (CL-20, respectively. When nano-RDX and nano-HMX are used in plastic bonded explosives (PBX as alternative materials of micron-sized particles, their shock sensitivities are significantly decreased by 24.5% (RDX and 22.9% (HMX, and their detonation velocities are increased by about 1.7%. Therefore, it is expected to promote the application of nano-nitramine explosives in PBXs and composite modified double-based propellants (CMDBs so that some of their properties would be improved.

Dynamics of explosively imploded pressurized tubes

Science.gov (United States)

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

2011-04-01

The detonation of an explosive layer surrounding a pressurized thin-walled tube causes the formation of a virtual piston that drives a precursor shock wave ahead of the detonation, generating very high temperatures and pressures in the gas contained within the tube. Such a device can be used as the driver for a high energy density shock tube or hypervelocity gas gun. The dynamics of the precursor shock wave were investigated for different tube sizes and initial fill pressures. Shock velocity and standoff distance were found to decrease with increasing fill pressure, mainly due to radial expansion of the tube. Adding a tamper can reduce this effect, but may increase jetting. A simple analytical model based on acoustic wave interactions was developed to calculate pump tube expansion and the resulting effect on the shock velocity and standoff distance. Results from this model agree quite well with experimental data.

Initiation of a boiling liquid expanding vapour explosion

Energy Technology Data Exchange (ETDEWEB)

McDevitt, C.A.

1990-01-01

Boiling liquid expanding vapour explosions (BLEVEs) occur when a pressure liquefied gas tank is burst and the fluid is ejected to the atmosphere. As the liquid is exposed to a lower pressure it boils violently, causing an explosion which destroys the container. One litre tanks were filled with propane or R12, heated, and caused to rupture at specific test conditions to determine the parameters required for a BLEVE. Results showed that the energy stored in the liquid under pressure relative to the liquid at atmospheric conditions was a quantity which can be used to predict a BLEVE for the particular apparatus and conditions used. The possible importance of the development of a shock wave within the container during a BLEVE was noted. A shock tube was used to study the shock waves generated during a BLEVE. Temperature, liquid volume, rupture location, rupture area, and the fluid involved were varied. The pressure was measured vs time for periods immediately after the rupture. Photographs of the formation of pressure waves were obtained using spark Schlieren photography. Similarities to waves measured during detonations in ducts were noted. Pressure information was also gathered during BLEVEs of one litre cylinders, and this data is compared to that from the shock tube. Shock tube data showed that transverse waves formed from the initial pressure wave could be amplified. 37 refs., 54 figs., 11 tabs.

Investigation of pressure transients in nuclear filtration systems: construction details of a large shock tube

International Nuclear Information System (INIS)

Smith, P.R.; Gregory, W.S.

1980-04-01

This report documents the construction of a 0.914-m (36-in.)-dia. shock tube on the New Mexico State University caompus. Highly variable low-grade explosions can be simulated with the shock tube. We plan to investigate the response of nuclear facility ventilation system components to low-grade explosions. Components of particular interest are high-capacity, high efficiency paticulate air (HEPA) filters. Shock tube construction details, operating principles, firing sequence, and preliminary results are reported

MODELING SNR CASSIOPEIA A FROM THE SUPERNOVA EXPLOSION TO ITS CURRENT AGE: THE ROLE OF POST-EXPLOSION ANISOTROPIES OF EJECTA

Energy Technology Data Exchange (ETDEWEB)

Orlando, S.; Miceli, M.; Pumo, M. L.; Bocchino, F., E-mail: orlando@astropa.inaf.it [INAF—Osservatorio Astronomico di Palermo “G.S. Vaiana,” Piazza del Parlamento 1, I-90134 Palermo (Italy)

2016-05-01

The remnants of core-collapse supernovae (SNe) have complex morphologies that may reflect asymmetries and structures developed during the progenitor SN explosion. Here we investigate how the morphology of the supernova remnant Cassiopeia A (Cas A) reflects the characteristics of the progenitor SN with the aim of deriving the energies and masses of the post-explosion anisotropies responsible for the observed spatial distribution of Fe and Si/S. We model the evolution of Cas A from the immediate aftermath of the progenitor SN to the three-dimensional interaction of the remnant with the surrounding medium. The post-explosion structure of the ejecta is described by small-scale clumping of material and larger-scale anisotropies. The hydrodynamic multi-species simulations consider an appropriate post-explosion isotopic composition of the ejecta. The observed average expansion rate and shock velocities can be well reproduced by models with ejecta mass M {sub ej} ≈ 4 M {sub ⊙} and explosion energy E {sub SN} ≈ 2.3 × 10{sup 51} erg. The post-explosion anisotropies (pistons) reproduce the observed distributions of Fe and Si/S if they had a total mass of ≈0.25 M {sub ⊙} and a total kinetic energy of ≈1.5 × 10{sup 50} erg. The pistons produce a spatial inversion of ejecta layers at the epoch of Cas A, leading to the Si/S-rich ejecta physically interior to the Fe-rich ejecta. The pistons are also responsible for the development of the bright rings of Si/S-rich material which form at the intersection between the reverse shock and the material accumulated around the pistons during their propagation. Our result supports the idea that the bulk of asymmetries observed in Cas A are intrinsic to the explosion.

Explosions and light curves of supernovae

International Nuclear Information System (INIS)

Gaffet, B.

1975-01-01

The models developed to explain supernovae explosions are reviewed. The first one is thermonuclear explosion (simple or preceded by an implosion phase); the neutrino emission which results of such an explosion can have an important dynamical effect, according as the star is opaque or transparent to them; another theory involves the radiation pressure of the pulsar which is formed in the center of the star. The origin of the supernovae brightness is also uncertain: the initial heat due to the explosion does not seem to be sufficient; the brightness can result from the diffusion of the heat through the ejected matter or can be transported more rapidly by a shock wave. A model in which the heat is produced by the pulsar seems compatible with most observations (shapes of the brightness curves and the continuum spectra, expansion velocities, temperature and luminosity at the peak, total kinetic energy) [fr

Experimental study on the influence of chemical sensitizer on pressure resistance in deep water of emulsion explosives

Science.gov (United States)

Liu, Lei; zhang, Zhihua; Wang, Ya; Qin, hao

2018-03-01

The study on the pressure resistance performance of emulsion explosives in deep water can provide theoretical basis for underwater blasting, deep-hole blasting and emulsion explosives development. The sensitizer is an important component of emulsion explosives. By using reusable experimental devices to simulate the charge environment in deep water, the influence of the content of chemical sensitizer on the deep-water pressure resistance performance of emulsion explosives was studied. The experimental results show that with the increasing of the content of chemical sensitizer, the deep-water pressure resistance performance of emulsion explosives gradually improves, and when the pressure is fairly large, the effect is particularly pronounced; in a certain range, with the increase of the content of chemical sensitizer, that emulsion explosives’ explosion performance also gradually improve, but when the content reaches a certain value, the explosion properties declined instead; under the same emulsion matrix condition, when the content of NANO2 is 0.2%, that the emulsion explosives has good resistance to water pressure and good explosion properties. The correctness of the results above was testified in model blasting.

Shock wave science and technology reference library

CERN Document Server

2009-01-01

This book is the second of several volumes on solids in the Shock Wave Science and Technology Reference Library. These volumes are primarily concerned with high-pressure shock waves in solid media, including detonation and high-velocity impact and penetration events. Of the four extensive chapters in this volume, the first two describe the reactive behavior of condensed phase explosives, - Condensed-Phase Explosives: Shock Initiation and Detonation Phenomena (SA Sheffield and R Engelke) - First Principles Molecular Simulations of Energetic Materials at High-Pressures (F Zhang, S Alavi, and TK Woo), and the remaining two discuss the inert, mechanical response of solid materials. - Combined Compression and Shear Plane Waves (ZP Tang and JB Aidun), and - Dynamic Fragmentation of Solids (D Grady). All chapters are each self-contained, and can be read independently of each other. They offer a timely reference, for beginners as well as professional scientists and engineers, on the foundations of detonation phenomen...

Shock wave physics group (M-6)

International Nuclear Information System (INIS)

Morris, C.E.

1981-01-01

Experimental facilities and activities of the shock wave physics group at LASL are described. The facilities include a compressed gas gun, two-stage gas gun, high explosive facilities, and a pulsed megagauss field facility

Asymmetric explosion of core-collapse supernovae

International Nuclear Information System (INIS)

Kazeroni, Remi

2016-01-01

A core-collapse supernova represents the ultimate stage of the evolution of massive stars.The iron core contraction may be followed by a gigantic explosion which gives birth to a neutron star.The multidimensional dynamics of the innermost region, during the first hundreds milliseconds, plays a decisive role on the explosion success because hydrodynamical instabilities are able to break the spherical symmetry of the collapse. Large scale transverse motions generated by two instabilities, the neutrino-driven convection and the Standing Accretion Shock Instability (SASI),increase the heating efficiency up to the point of launching an asymmetric explosion and influencing the birth properties of the neutron star. In this thesis, hydrodynamical instabilities are studied using numerical simulations of simplified models. These models enable a wide exploration of the parameter space and a better physical understanding of the instabilities, generally inaccessible to realistic models.The non-linear regime of SASI is analysed to characterize the conditions under which a spiral mode prevails and to assess its ability to redistribute angular momentum radially.The influence of rotation on the shock dynamics is also addressed. For fast enough rotation rates, a corotation instability overlaps with SASI and greatly impacts the dynamics. The simulations enable to better constrain the effect of non-axisymmetric modes on the angular momentum budget of the iron core collapsing into a neutron star. SASI may under specific conditions spin up or down the pulsar born during the explosion. Finally, an idealised model of the heating region is studied to characterize the non-linear onset of convection by perturbations such as those produced by SASI or pre-collapse combustion inhomogeneities. The dimensionality issue is examined to stress the beneficial consequences of the three-dimensional dynamics on the onset of the explosion. (author) [fr

A Literature Review of Shock Sensitivity Changes of TATB Due to Thermal Cycling

Energy Technology Data Exchange (ETDEWEB)

Ritter, Boyd [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); New Mexico Inst. of Mining and Technology, Socorro, NM (United States). Dept. of Mechanical Engineering

2016-07-15

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 with 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.

Predictive Capability of the Compressible MRG Equation for an Explosively Driven Particle with Validation

Science.gov (United States)

Garno, Joshua; Ouellet, Frederick; Koneru, Rahul; Balachandar, Sivaramakrishnan; Rollin, Bertrand

2017-11-01

An analytic model to describe the hydrodynamic forces on an explosively driven particle is not currently available. The Maxey-Riley-Gatignol (MRG) particle force equation generalized for compressible flows is well-studied in shock-tube applications, and captures the evolution of particle force extracted from controlled shock-tube experiments. In these experiments only the shock-particle interaction was examined, and the effects of the contact line were not investigated. In the present work, the predictive capability of this model is considered for the case where a particle is explosively ejected from a rigid barrel into ambient air. Particle trajectory information extracted from simulations is compared with experimental data. This configuration ensures that both the shock and contact produced by the detonation will influence the motion of the particle. The simulations are carried out using a finite volume, Euler-Lagrange code using the JWL equation of state to handle the explosive products. This work was supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program,under Contract No. DE-NA0002378.

Evolution of Shock Waves in Silicon Carbide Rods

International Nuclear Information System (INIS)

Balagansky, I. A.; Balagansky, A. I.; Razorenov, S. V.; Utkin, A. V.

2006-01-01

Evolution of shock waves in self-bonded silicon carbide bars in the shape of 20 mm x 20 mm square prisms of varying lengths (20 mm, 40 mm, and 77.5 mm) is investigated. The density and porosity of the test specimens were 3.08 g/cm3 and 2%, respectively. Shock waves were generated by detonating a cylindrical shaped (d=40 mm and 1=40 mm) stabilized RDX high explosive charge of density 1.60 g/cm3. Embedded manganin gauges at various distances from the impact face were used to monitor the amplitude of shock pressure profiles. Propagation velocity of the stress pulse was observed to be equal to the elastic bar wave velocity of 11 km/s and was independent of the amplitude of the impact pulse. Strong fuzziness of the stress wave front is observed. This observation conforms to the theory on the instability of the shock formation in a finite size elastic body. This phenomenon of wave front fuzziness may be useful for desensitization of heterogeneous high explosives

Shocks in fragile matter

Science.gov (United States)

Vitelli, Vincenzo

2012-02-01

Non-linear sound is an extreme phenomenon typically observed in solids after violent explosions. But granular media are different. Right when they unjam, these fragile and disordered solids exhibit vanishing elastic moduli and sound speed, so that even tiny mechanical perturbations form supersonic shocks. Here, we perform simulations in which two-dimensional jammed granular packings are continuously compressed, and demonstrate that the resulting excitations are strongly nonlinear shocks, rather than linear waves. We capture the full dependence of the shock speed on pressure and compression speed by a surprisingly simple analytical model. We also treat shear shocks within a simplified viscoelastic model of nearly-isostatic random networks comprised of harmonic springs. In this case, anharmonicity does not originate locally from nonlinear interactions between particles, as in granular media; instead, it emerges from the global architecture of the network. As a result, the diverging width of the shear shocks bears a nonlinear signature of the diverging isostatic length associated with the loss of rigidity in these floppy networks.

PROGENITOR-DEPENDENT EXPLOSION DYNAMICS IN SELF-CONSISTENT, AXISYMMETRIC SIMULATIONS OF NEUTRINO-DRIVEN CORE-COLLAPSE SUPERNOVAE

Energy Technology Data Exchange (ETDEWEB)

Summa, Alexander; Hanke, Florian; Janka, Hans-Thomas; Melson, Tobias [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany); Marek, Andreas [Max Planck Computing and Data Facility (MPCDF), Gießenbachstr. 2, D-85748 Garching (Germany); Müller, Bernhard, E-mail: asumma@mpa-garching.mpg.de, E-mail: thj@mpa-garching.mpg.de [Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast, BT7 1NN (United Kingdom)

2016-07-01

We present self-consistent, axisymmetric core-collapse supernova simulations performed with the Prometheus-Vertex code for 18 pre-supernova models in the range of 11–28 M {sub ⊙}, including progenitors recently investigated by other groups. All models develop explosions, but depending on the progenitor structure, they can be divided into two classes. With a steep density decline at the Si/Si–O interface, the arrival of this interface at the shock front leads to a sudden drop of the mass-accretion rate, triggering a rapid approach to explosion. With a more gradually decreasing accretion rate, it takes longer for the neutrino heating to overcome the accretion ram pressure and explosions set in later. Early explosions are facilitated by high mass-accretion rates after bounce and correspondingly high neutrino luminosities combined with a pronounced drop of the accretion rate and ram pressure at the Si/Si–O interface. Because of rapidly shrinking neutron star radii and receding shock fronts after the passage through their maxima, our models exhibit short advection timescales, which favor the efficient growth of the standing accretion-shock instability. The latter plays a supportive role at least for the initiation of the re-expansion of the stalled shock before runaway. Taking into account the effects of turbulent pressure in the gain layer, we derive a generalized condition for the critical neutrino luminosity that captures the explosion behavior of all models very well. We validate the robustness of our findings by testing the influence of stochasticity, numerical resolution, and approximations in some aspects of the microphysics.

Effect of Pressure Gradients on the Initiation of PBX-9502 via Irregular (Mach) Reflection of Low Pressure Curved Shock Waves

Energy Technology Data Exchange (ETDEWEB)

Hull, Lawrence Mark [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Miller, Phillip Isaac [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moro, Erik Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-11-28

In the instance of multiple fragment impact on cased explosive, isolated curved shocks are generated in the explosive. These curved shocks propagate and may interact and form irregular or Mach reflections along the interaction loci, thereby producing a single shock that may be sufficient to initiate PBX-9501. However, the incident shocks are divergent and their intensity generally decreases as they expand, and the regions behind the Mach stem interaction loci are generally unsupported and allow release waves to rapidly affect the flow. The effects of release waves and divergent shocks may be considered theoretically through a “Shock Change Equation”.

Ground Shock Resistant of Buried Nuclear Power Plant Facility

International Nuclear Information System (INIS)

Ornai, D.; Adar, A.; Gal, E.

2014-01-01

Nuclear Power Plant (NPP) might be subjected to hostile attacks such as Earth Penetrating Weapons (EPW) that carry explosive charges. Explosions of these weapons near buried NPP facility might cause collapse, breaching, spalling, deflection, shear, rigid body motion (depending upon the foundations), and in-structure shock. The occupants and the equipment in the buried facilities are exposed to the in-structure motions, and if they are greater than their fragility values than occupants might be wounded or killed and the equipment might be damaged, unless protective measures will be applied. NPP critical equipment such as pumps are vital for the normal safe operation since it requires constant water circulation between the nuclear reactor and the cooling system, including in case of an immediate shut down. This paper presents analytical- semi empirical formulation and analysis of the explosion of a penetrating weapon with a warhead of 100kgs TNT (Trinitrotoluene) that creates ground shock effect on underground NPP structure containing equipment, such as a typical pump. If the in-structure spectral shock is greater than the pump fragility values than protective measures are required, otherwise a real danger to the NPP safety might occur

Tandem shock wave cavitation enhancement for extracorporeal lithotripsy

Science.gov (United States)

Loske, Achim M.; Prieto, Fernando E.; Fernández, Francisco; van Cauwelaert, Javier

2002-11-01

Extracorporeal shock wave lithotripsy (ESWL) has been successful for more than twenty years in treating patients with kidney stones. Hundreds of underwater shock waves are generated outside the patient's body and focused on the kidney stone. Stones fracture mainly due to spalling, cavitation and layer separation. Cavitation bubbles are produced in the vicinity of the stone by the tensile phase of each shock wave. Bubbles expand, stabilize and finally collapse violently, creating stone-damaging secondary shock waves and microjets. Bubble collapse can be intensified by sending a second shock wave a few hundred microseconds after the first. A novel method of generating two piezoelectrically generated shock waves with an adjustable time delay between 50 and 950 µs is described and tested. The objective is to enhance cavitation-induced damage to kidney stones during ESWL in order to reduce treatment time. In vitro kidney stone model fragmentation efficiency and pressure measurements were compared with those for a standard ESWL system. Results indicate that fragmentation efficiency was significantly enhanced at a shock wave delay of about 400 and 250 µs using rectangular and spherical stone phantoms, respectively. The system presented here could be installed in clinical devices at relatively low cost, without the need for a second shock wave generator.

Hydrodynamic modeling and explosive compaction of ceramics

International Nuclear Information System (INIS)

Hoenig, C.; Holt, A.; Finger, M.; Kuhl, W.

1977-01-01

High-density ceramics with high-strength microstructure were achieved by explosive compaction. Well-characterized Al 2 O 3 , AlN, and boron powders were explosively compacted in both cylindrical and flat plate geometries. In cylindrical geometries compacted densities between 91 and 98 percent of theoretical were achieved. Microhardness measurements indicated that the strength and integrity of the microstructure were comparable to conventionally fabricated ceramics, even though all samples with densities greater than 90 percent theoretical contained macrocracks. Fractured surfaces evaluated by SEM showed evidence of boundary melting. Equation of state data for porous Al 2 O 3 were used to calculate the irreversible work done on the sample as a function of pressure. This was expressed as a percentage of the total sample which could be melted. Calculations show that very little melting can be expected in samples shocked to less than 3 GPa. Significant melting and grain boundary fusion can be expected in samples shocked to pressures greater than 8 GPa. Hydrodynamic modeling of right cylinder compaction with detonation at one end was attempted by using a two-dimensional computer code. The complications of this analysis led to experiments using plane shock waves. Flat-plate compaction assemblies were designed and analyzed by 2-D hydrodynamic codes. The use of porous shock attenuators was evaluated. Experiments were performed on aluminum oxide powders in plane wave geometry. Microstructure evaluations were made as a function of location in the flat plate samples. 11 figures, 1 table

Steam explosion simulation code JASMINE v.3 user's guide

International Nuclear Information System (INIS)

Moriyama, Kiyofumi; Maruyama, Yu; Nakamura, Hideo

2008-07-01

A steam explosion occurs when hot liquid contacts with cold volatile liquid. In this phenomenon, fine fragmentation of the hot liquid causes extremely rapid heat transfer from the hot liquid to the cold volatile liquid, and explosive vaporization, bringing shock waves and destructive forces. The steam explosion due to the contact of the molten core material and coolant water during severe accidents of light water reactors has been regarded as a potential threat to the integrity of the containment vessel. We developed a mechanistic steam explosion simulation code, JASMINE, that is applicable to plant scale assessment of the steam explosion loads. This document, as a manual for users of JASMINE code, describes the models, numerical solution methods, and also some verification and example calculations, as well as practical instructions for input preparation and usage of the code. (author)

The imitator of nuclear explosion signals for field operations

International Nuclear Information System (INIS)

Wang Lusong; Xie Yujun; Tan Youjin; Wang Liping

1999-01-01

According to the present system of the nuclear explosion monitoring equipment (NEME), the imitator of nuclear explosion signals for field operation is urgently needed by NEME, which has been fitted out to the army and some new types that will be finalized soon. The authors have made the imitator for the equipment, and as the cause of this research, it can be used not only in training and maintenance for army but also in research and production for scientific research institutions and industrial enterprise. Function of this imitator is to imitate the NEMP, the light and shock wave signals of nuclear explosion in proper order. The time difference of the process accords with the true location of nuclear explosion. This research is of great military importance

Hybrid Underwater Vehicle: ARV Design and Development

Directory of Open Access Journals (Sweden)

Zhigang DENG

2014-02-01

Full Text Available The development of SMU-I, a new autonomous & remotely-operated vehicle (ARV is described. Since it has both the characteristics of autonomous underwater vehicle (AUV and remote operated underwater vehicle (ROV, it is able to achieve precision fix station operation and manual timely intervention. In the paper the initial design of basic components, such as vehicle, propulsion, batteries etc. and the control design of motion are introduced and analyzed. ROV’s conventional cable is replaced by a fiber optic cable, which makes it available for high-bandwidth real-time video, data telemetry and high-quality teleoperation. Furthermore, with the aid of the manual real-time remote operation and ranging sonar, it also resolves the AUV’s conflicting issue, which can absolutely adapt the actual complex sea environment and satisfy the unknown mission need. The whole battery system is designed as two-battery banks, whose voltages and temperatures are monitored through CAN (controller area network bus to avoid battery fire and explosion. A fuzzy-PID controller is designed for its motion control, including depth control and direction control. The controller synthesizes the advantage of fuzzy control and PID control, utilizes the fuzzy rules to on-line tune the parameters of PID controller, and achieves a better control effect. Experiment results demonstrate to show the effectiveness of the test-bed.

Planar compaction of ceramic powders with mining explosives

International Nuclear Information System (INIS)

Stuivinga, M.; Verbeek, H.J.; Carton, E.P.

2000-01-01

Shock compaction experiments of B 4 C powders have been performed using a planar configuration. The powders were contained between metal plates. On top of the upper plate, having a thickness of about 10 mm, was a layer of mining explosives. For this configuration, computer simulations have been performed with use of the hydrocode Autodyn. In comparison with the cylindrical compaction process the planar compaction process appears to be quite different. The reason is the very low detonation velocity of the used mining explosives (2-4 km/s), which is much lower than the sound and shock speeds of the steel plate, in combination with the relatively large thickness of the metal layer. As a result, the nature of the compaction process of the powder initially more resembles a quasi-static compaction process than a shock compaction process. Due to the quasi-static nature of the compaction, the pressure release in the powder after compression is very gradual. Therefore, no strong rarefaction waves leading to high tensile stresses in the compact arise. Flat plates (10x10 cm, 0.6-0.8 cm thick) of Al (20-30 vol %) infiltrated B 4 C have been fabricated using this configuration

P. W. Bridgman's contributions to the foundations of shock compression of condensed matter

Energy Technology Data Exchange (ETDEWEB)

Nellis, W J, E-mail: nellis@physics.harvard.ed [Department of Physics, Harvard University, Cambridge MA 02138 (United States)

2010-03-01

Based on his 50-year career in static high-pressure research, P. W. Bridgman (PWB) is the father of modern high-pressure physics. What is not generally recognized is that Bridgman was also intimately connected with establishing shock compression as a scientific tool and he predicted major events in shock research that occurred up to 40 years after his death. In 1956 the first phase transition under shock compression was reported in Fe at 13 GPa (130 kbar). PWB said a phase transition could not occur in a {approx}microsec, thus setting off a controversy. The scientific legitimacy of shock compression resulted 5 years later when static high-pressure researchers confirmed with x-ray diffraction the existence of epsilon-Fe. Once PWB accepted the fact that shock waves generated with chemical explosives were a valid scientific tool, he immediately realized that substantially higher pressures would be achieved with nuclear explosives. He included his ideas for achieving higher pressures in articles published a few years after his death. L. V. Altshuler eventually read Bridgman's articles and pursued the idea of using nuclear explosives to generate super high pressures, which subsequently morphed today into giant lasers. PWB also anticipated combining static and shock methods, which today is done with pre-compression of a soft sample in a diamond anvil cell followed by laser-driven shock compression. One variation of that method is the reverberating-shock technique, in which the first shock pre-compresses a soft sample and subsequent reverberations isentropically compress the first-shocked state.

Design of underwater work systems

International Nuclear Information System (INIS)

Lovelace, R.B.

1980-01-01

In the near future, underwater vehicles will replace divers as the principal means for inspection and maintenance work. These vehicles will provide a maneuverable work platform for an underwater viewing system and manipulator/tool package. Some of the problems faced by the underwater designer, and some areas to consider in the design of an integrated underwater work system, are considered

Variation of Pressure Waveforms in Measurements of Extracorporeal Shock Wave Lithotripter

Science.gov (United States)

Inose, Naoto; Ide, Masao

1993-05-01

In this paper, we describe measurement of variation in pressure waveforms of the acoustic field of an extra-corporeal shock-wave lithotripter (ESWL). Variations in the measured acoustic fields and pressure waveform of an underwater spark-gap-type ESWL with an exhausted spark plug electrode have been reported by researchers using crystal sensors. If the ESWL spark plugs become exhausted, patients feel pain during kidney, biliary stone disintegration. We studied the relationship between exhaustion of electrodes and the variation of pressure waveforms and shock-wave fields of the ESWL using a newly developed hydrophone.

Physics of IED blast shock tube simulations for mTBI research

NARCIS (Netherlands)

Mediavilla Varas, J.; Philippens, M.M.G.M.; Meijer, S.R.; Berg, A.C. van den; Sibma, P.C.; Bree, J.L.M.J. van; Vries, D.V.W.M. de

2011-01-01

Shock tube experiments and simulations are conducted with a spherical gelatin filled skull- brain surrogate, in order to study the mechanisms leading to blast induced mild traumatic brain injury. A shock tube including sensor system is optimized to simulate realistic impro-vised explosive device

Collisionless shock waves

International Nuclear Information System (INIS)

Sagdeev, R.Z.; Kennel, C.F.

1991-01-01

Collisionless shocks cannot occur naturally on the earth, because nearly all matter here consists of electrically neutral atoms and molecules. In space, however, high temperatures and ultraviolet radiation from hot stars decompose atoms into their constituent nuclei and electrons, producing a soup of electrically charged particles known as a plasma. Plasma physicists proposed that the collective electrical and magnetic properties of plasmas could produce interactions that take the place of collisions and permit shocks to form. In 1964 the theoretical work found its first experimental confirmation. Norman F. Ness and his colleagues at the Goddard Space Flight Center, using data collected from the iMP-1 spacecraft, detected clear signs that a collisionless shock exists where the solar wind encounters the earth's magnetic field. More recent research has demonstrated that collisionless shocks appear in a dazzling array of astronomical settings. For example, shocks have been found in the solar wind upstream (sunward) of all the planet and comets that have been visited by spacecraft. Violent flares on the sun generate shocks that propagate to the far reaches of the solar system; tremendous galactic outbursts create disruptions in the intergalactic medium that are trillions of times larger. In addition, many astrophysicists think that shocks from supernova explosions in our galaxy accelerate cosmic rays, a class of extraordinarily energetic elementary particles and atomic nuclei that rain down on the earth from all directions

Nucleosynthesis in neutrino-driven, aspherical supernova explosion of a massive star

International Nuclear Information System (INIS)

Fujimoto, S.; Hashimoto, M.; Ono, M.; Kotake, K.; Ohnishi, N.

2011-01-01

We examine explosive nucleosynthesis of p-nuclei during a delayed neutrino-driven, aspherical supernova explosion aided by standing accretion shock instability, based on two-dimensional hydrodynamic simulations of the explosion of a 15M · star. We find that p-nuclei are mainly produced through γ-processes, and that the nuclei lighter than 92 Mo are abundantly synthesized in slightly neutron-rich bubbles with electron fractions of Y e ≤0.48. 94 Mo, 96 Ru, and 98 Ru, are underproduced compared with the solar system, as in the spherical model.

Numerical simulation of the structure of collisionless supercritical shocks

International Nuclear Information System (INIS)

Lipatov, A.S.

1990-01-01

Research on the structure of a collisionless shock wave and on acceleration of charged particles is important for analyzing the processes accompanying solar flares, and also for studying the shock waves which are excited in the interaction of the solar wind with planets, comets and interstellar gas, the mechanisms for the acceleration of cosmic rays, the processes accompanying magnetic field reconnection, explosion of Supernova. The study of the shock is also important for studying the processes in the active experiments in space. In the present report only supercritical shocks are considered, when partial ion reflection plays a controlling roll in shock formation. One- and two-dimensional simulations of the perpendicular shocks are presented. (R.P.) 33 refs.; 4 figs

Taiwan's underwater cultural heritage documentation management

Science.gov (United States)

Tung, Y.-Y.

2015-09-01

Taiwan is an important trading and maritime channels for many countries since ancient time. Numerous relics lie underwater due to weather, wars, and other factors. In the year of 2006, Bureau of Cultural Heritage (BOCH) entrusted the Underwater Archaeological Team of Academia Sinica to execute the underwater archaeological investigation projects. Currently, we verified 78 underwater targets, with 78 site of those had been recognized as shipwrecks sites. Up to date, there is a collection of 638 underwater objects from different underwater archaeological sites. Those artefacts are distributed to different institutions and museums. As very diverse management methods/systems are applied for every individual institution, underwater cultural heritage data such as survey, excavation report, research, etc. are poorly organized and disseminated for use. For better communication regarding to Taiwan's underwater cultural heritage in every level, a universal format of documentation should be established. By comparing the existing checklist used in Taiwan with guidelines that are followed in other countries, a more intact and appropriate underwater cultural heritage condition documentation system can be established and adapted in Taiwan.

Development of underwater laser cutting technology

International Nuclear Information System (INIS)

Sato, Seiichi; Inaba, Takanori; Inose, Koutarou; Matsumoto, Naoyuki; Sakakibara, Yuji

2015-01-01

In is desirable to use remote underwater device for the decommissioning work of highly radioactive components such as the nuclear internals from a view point of reducing the ranitidine exposure to the worker. Underwater laser cutting technology has advantages. First advantage in underwater laser cutting technology is that low reaction force during cutting, namely, remote operability is superior. Second point is that underwater laser cutting generates a little amount of secondary waste, because cutting kerf size is very small. Third point is that underwater laser cutting has low risk of the process delay, because device trouble is hard to happen. While underwater laser cutting has many advantages, the careful consideration in the safe treatment of the offgas which underwater laser cutting generates is necessary. This paper describes outline of underwater laser cutting technology developed by IHI Corporation (IHI) and that this technology is effective in various dismantling works in water. (author)

Blind equalization for underwater communications

NARCIS (Netherlands)

Blom, K.C.H.

2014-01-01

Underwater wireless (sensor) networks would vastly improve man's ability to explore and exploit remote aquatic environments. Despite underwater sensor and vehicle technology being relatively mature, underwater communications is still a major challenge. The most challenging characteristics of the

Procalcitonin as a diagnostic biomarker for septic shock and bloodstream infection in burn patients from the Formosa Fun Coast dust explosion.

Science.gov (United States)

Wu, Rui-Xin; Chiu, Chih-Chien; Lin, Tzu-Chao; Yang, Ya-Sung; Lee, Yi; Lin, Jung-Chung; Chang, Feng-Yee

2017-12-01

Infection is the most common cause of death following burn injury. The study was conducted to compare the diagnostic value of serum procalcitonin (PCT) with the other current benchmarks as early predictors of septic shock and bloodstream infection in burn patients. We included 24 patients admitted to the Burn Unit of a medical center from June 2015 to December 2015 from the Formosa Fun Coast dust explosion. We categorized all patients at initial admission into either sepsis or septic shock groups. Laboratory tests including the worst PCT and C-reactive protein (CRP) levels, platelet (PLT), and white blood cell (WBC) count were performed at <48 h after admission. Patients were also classified in two groups with subsequent bacteremia and non-bacteremia groups during hospitalization. Significantly higher PCT levels were observed among participants with septic shock compared to those with sepsis (47.19 vs. 1.18 ng/mL, respectively; p < 0.001). Patients with bacteremia had significantly elevated PCT levels compared to patients without bacteremia (29.54 versus 1.81 ng/mL, respectively, p < 0.05). No significant differences were found in CRP levels, PLT, and WBC count between the two groups. PCT levels showed reasonable discriminative power (cut-off: 5.12 ng/mL; p = 0.01) in predicting of bloodstream infection in burn patients and the area under receiver operating curves was 0.92. PCT levels can be helpful in determining the septic shock and bloodstream infection in burn patients but CRP levels, PLT, and WBC count were of little diagnostic value. Copyright © 2017. Published by Elsevier B.V.

Uniformity of cylindrical imploding underwater shockwaves at very small radii

Science.gov (United States)

Yanuka, D.; Rososhek, A.; Bland, S. N.; Krasik, Ya. E.

2017-11-01

We compare the convergent shockwaves generated from underwater, cylindrical arrays of copper wire exploded by multiple kilo-ampere current pulses on nanosecond and microsecond scales. In both cases, the pulsed power devices used for the experiments had the same stored energy (˜500 J) and the wire mass was adjusted to optimize energy transfer to the shockwave. Laser backlit framing images of the shock front were achieved down to the radius of 30 μm. It was found that even in the case of initial azimuthal non-symmetry, the shock wave self-repairs in the final stages of its motion, leading to a highly uniform implosion. In both these and previous experiments, interference fringes have been observed in streak and framing images as the shockwave approached the axis. We have been able to accurately model the origin of the fringes, which is due to the propagation of the laser beam diffracting off the uniform converging shock front. The dynamics of the shockwave and its uniformity at small radii indicate that even with only 500 J stored energies, this technique should produce pressures above 1010 Pa on the axis, with temperatures and densities ideal for warm dense matter research.

Physics of phenomena in the zone close to an underground nuclear explosion; Physique des phenomenes en zone proche des explosions nucleaires souterraines

Energy Technology Data Exchange (ETDEWEB)

Maury, J; Levret, C [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

1969-07-01

After a description of the phenomenology of underground explosions, the basic laws governing the propagation in the ground of the energy produced by the explosion are given. The reports considers hydrodynamics, the mechanics of solids, the equations of state for solids and gases in the case of very high and medium pressures, and the dynamical strength of solids. These various elements make it possible to draw up a system of equations which define completely the changes with time of the shock-wave produced in the ground by the explosion. (authors) [French] Apres une description de la phenomenologie des explosions souterraines, on expose les lois fondamentales regissant la propagation dans le sol de l'energie degagee par l'explosion. L'expose comprend des developpements sur l'hydrodynamique, la mecanique des solides, les equations d'etat des solides et des gaz, aux tres fortes et moyennes pressions, et sur la resistance dynamique des solides. Ces differents elements permettent d'ecrire un systeme d'equations qui definissent completement l'evolution dans le temps de l'onde de choc emise dans le sol par l'explosion. (auteurs)

Magnetorotational Explosions of Core-Collapse Supernovae

Directory of Open Access Journals (Sweden)

Gennady S. Bisnovatyi-Kogan

2014-12-01

Full Text Available Core-collapse supernovae are accompanied by formation of neutron stars. The gravitation energy is transformed into the energy of the explosion, observed as SN II, SN Ib,c type supernovae. We present results of 2-D MHD simulations, where the source of energy is rotation, and magnetic eld serves as a "transition belt" for the transformation of the rotation energy into the energy of the explosion. The toroidal part of the magnetic energy initially grows linearly with time due to dierential rotation. When the twisted toroidal component strongly exceeds the poloidal eld, magneto-rotational instability develops, leading to a drastic acceleration in the growth of magnetic energy. Finally, a fast MHD shock is formed, producing a supernova explosion. Mildly collimated jet is produced for dipole-like type of the initial field. At very high initial magnetic field no MRI development was found.

Fast neutron sensor for detection of explosives and chemical warfare agents

International Nuclear Information System (INIS)

Valkovic, Vladivoj; Sudac, Davorin; Matika, Dario

2010-01-01

Once the presence of the anomaly on the bottom of the shallow coastal sea water has been confirmed it is necessary to establish if it contains explosive or chemical warfare charge. We propose that this be performed by using neutron sensor installed within an underwater vessel. When positioned above the object, or to its side, the system can inspect the object for the presence of the threat materials by using alpha particle tagged neutrons from the sealed tube d+t neutron generator.

Fast neutron sensor for detection of explosives and chemical warfare agents

Energy Technology Data Exchange (ETDEWEB)

Valkovic, Vladivoj [A.C.T.d.o.o., Prilesje 4, 10000 Zagreb (Croatia)], E-mail: valkovic@irb.hr; Sudac, Davorin [Institute Ruder Boskovic, Bijenicka c.54, 10000 Zagreb (Croatia); Matika, Dario [Institute for Researches and Development of Defense Systems, Ilica 256b, 10000 Zagreb (Croatia)

2010-04-15

Once the presence of the anomaly on the bottom of the shallow coastal sea water has been confirmed it is necessary to establish if it contains explosive or chemical warfare charge. We propose that this be performed by using neutron sensor installed within an underwater vessel. When positioned above the object, or to its side, the system can inspect the object for the presence of the threat materials by using alpha particle tagged neutrons from the sealed tube d+t neutron generator.

Underwater Noise Pollution at the Strait of Istanbul (Bosphorus

Directory of Open Access Journals (Sweden)

Cem Gazioğlu

2016-12-01

Full Text Available Underwater noise pollution (UNP has become a major concern in marine habitats, which is intense anthropogenic noise in the marine (aquatic environment. It is caused by ship traffic, oceanographic experiments, and use of explosives in geophysical research, underwater construction, active sonars and seismic survey techniques. Oceans are much nosier than 1960s. Narrow and shallow channel noisy aquatic environments where noise levels reach the highest value is not surprising. The Strait of Istanbul (SoI; Bosphorus is one of the most important maritime passages (app. 50 000 vessel/year or 140 vessel/day which is situated between the Black Sea and the Aegean Sea are also biologically extremely important gateway not only it provides access to a channel. Many of the varieties of fish migration hunting value are realized through the TSS. Local maritime traffic is another important acoustic sources which are more than 3 000 elements (Kesgin and Vardar, 2001 of everyday local traffic in SoI, which are causing noise in the 2 and 10 kHz range. Large vessels create signals both in bands below 1 kHz (main engine, electrical instruments cavitation noise creates higher frequency bands. Almost all elements of marine traffic in SoI located therefore encountered UND in all bands.

Oblique interactions of detonation waves with explosive/metal interfaces

International Nuclear Information System (INIS)

Walsh, J.M.

1982-12-01

The interaction of a detonation wave with an explosive/metal interface is considered. Theoretical models are discussed, and calculated results are given for PBX 9501 onto uranium, tantalum, copper, 304 stainless steel, aluminum, and nickel. For PBX 9501 onto aluminum and copper, regular shock reflection (in the PBX 9501) at small angles changes to regular rarefaction reflection (Prandtl-Meyer flow) at large angles, and the curve of metal-shock pressure vs incidence angle is smooth. For the other metals, there is a discontinuity in shock pressure where low-angle, regular reflection transists to Mach reflection, and a smaller discontinuity where the Mach reflection changes back to high-angle regular reflection

Cutting of CO2 primary circuit pipes of G 2/G 3 using explosive charges

International Nuclear Information System (INIS)

Imbard, G.; Le Goaller, C.; Ravera, J.P.; Bonnier, Y.; Guilbert, J.P.; Puntous, R.

1994-01-01

The objective of this work is to cut large diameter contaminated pipes from the CO 2 cooling system of the gas-cooled reactors by means of explosive charges and to use the resulting shock wave to remove part of the contamination fixed inside the pipe. Two types of tests have been conducted using different explosives in different forms (the decontamination and the cutting tests) and are described. After testing the cutting modules and decontamination fuses, the effects of the detonations on the environment have been measured and were greater than expected. A metal containment device was therefore designed to absorb part of the energy dissipated by the shock wave and retain the debris from the explosions. A description of the tests conducted for this purpose is given. (O.L.). 7 figs., 3 tabs

Summary of efficiency testing of standard and high-capacity high-efficiency particulate air filters subjected to simulated tornado depressurization and explosive shock waves

International Nuclear Information System (INIS)

Smith, P.R.; Gregory, W.S.

1985-04-01

Pressure transients in nuclear facility air cleaning systems can originate from natural phenomena such as tornadoes or from accident-induced explosive blast waves. This study was concerned with the effective efficiency of high-efficiency particulate air (HEPA) filters during pressure surges resulting from simulated tornado and explosion transients. The primary objective of the study was to examine filter efficiencies at pressure levels below the point of structural failure. Both standard and high-capacity 0.61-m by 0.61-m HEPA filters were evaluated, as were several 0.2-m by 0.2-m HEPA filters. For a particular manufacturer, the material release when subjected to tornado transients is the same (per unit area) for both the 0.2-m by 0.2-m and the 0.61-m by 0.61-m filters. For tornado transients, the material release was on the order of micrograms per square meter. When subjecting clean HEPA filters to simulated tornado transients with aerosol entrained in the pressure pulse, all filters tested showed a degradation of filter efficiency. For explosive transients, the material release from preloaded high-capacity filters was as much as 340 g. When preloaded high-capacity filters were subjected to shock waves approximately 50% of the structural limit level, 1 to 2 mg of particulate was released

Similarities and differences in vapor explosion criteria

International Nuclear Information System (INIS)

Cronenberg, A.W.

1978-01-01

An overview of recent ideas pertaining to vapor explosion criteria indicates that in general sense, a consensus of opinion is emerging on the conditions applicable to explosive vaporization. Experimental and theoretical work has lead a number of investigators to the formulation of such conditions which are quite similar in many respects, although the quantitative details of the model formulation of such conditions are somewhat different. All model concepts are consistent in that an initial period of stable film boiling, separating molten fuel from coolant, is considered necessary (at least for large-scale interactions and efficient intermixing), with subsequent breakdown of film boiling due to pressure and/or thermal effects, followed by intimate fuel-coolant contact and a rapid vaporization process which is sufficient to cause shock pressurization. Although differences arise as to the conditions for and the energetics associated with film boiling destabilization and the mode and energetics of fragmentation and intermixing. However, the principal area of difference seems to be the question of what constitutes the requisite condition(s) for rapid vapor production to cause shock pressurization

Shocked plate metal atom oxidation laser

International Nuclear Information System (INIS)

De Koker, J.G.; Rice, W.W. Jr.; Jensen, R.J.

1975-01-01

A method and apparatus for producing metal atom oxidation lasing wherein an explosively shocked grooved metal plate produces metal vapor jets directed through an appropriate gaseous oxidizer are described. Reaction of the metal vapor with the oxidizer produces molecular species having a population inversion therein. (U.S.)

Explosion-produced ground motion: technical summary with respect to seismic hazards

Energy Technology Data Exchange (ETDEWEB)

Rodean, Howard C [Lawrence Radiation Laboratory, University of California, Livermore, CA (United States)

1970-05-15

This paper summarizes the present technical knowledge, experimental and theoretical, of how underground nuclear explosions produce seismic motion that may be a hazard at distances measured in tens of kilometers. The effects of explosion yield and rock properties (at the explosion, along the signal propagation path, and at the site where a hazard may exist) on the ground motion are described in detail, and some consideration is given to the relation between ground motion and damage criteria. The energy released in a nuclear explosion is sufficient to vaporize the explosive and to generate an intense shock wave that is propagated outward into the surrounding rock. Part of the energy transported by the shock wave is dissipated in the shocked material. The shock wave strength decreases with distance from the center of the explosion as a consequence of this energy loss and because of geometric (approximately spherical) divergence. The dissipated energy fraction ranges from over 95% (for competent rocks like granite) to over 99% (for crushable, porous rocks like alluvium) of the explosion yield. Therefore, the energy fraction that is radiated in the form of seismic waves ranges from a few percent down to a few tenths of a percent. This is consistent with the observation that explosions in granite produce more severe ground motion than corresponding explosions in alluvium. The effects of explosion yield and rock properties on the frequency spectrum of the seismic source function are demonstrated by both experimental measurements and theoretical analysis. The characteristics of an ideal elastic medium are such that its frequency response is that of a low-pass filter, with its cutoff frequency being a function of the elastic properties of the material and the radius at which the explosion-produced stress wave becomes elastic. There is further frequency- and distance-dependent attenuation (especially of the higher frequencies) of the seismic waves, because rocks are not

Explosion-produced ground motion: technical summary with respect to seismic hazards

International Nuclear Information System (INIS)

Rodean, Howard C.

1970-01-01

This paper summarizes the present technical knowledge, experimental and theoretical, of how underground nuclear explosions produce seismic motion that may be a hazard at distances measured in tens of kilometers. The effects of explosion yield and rock properties (at the explosion, along the signal propagation path, and at the site where a hazard may exist) on the ground motion are described in detail, and some consideration is given to the relation between ground motion and damage criteria. The energy released in a nuclear explosion is sufficient to vaporize the explosive and to generate an intense shock wave that is propagated outward into the surrounding rock. Part of the energy transported by the shock wave is dissipated in the shocked material. The shock wave strength decreases with distance from the center of the explosion as a consequence of this energy loss and because of geometric (approximately spherical) divergence. The dissipated energy fraction ranges from over 95% (for competent rocks like granite) to over 99% (for crushable, porous rocks like alluvium) of the explosion yield. Therefore, the energy fraction that is radiated in the form of seismic waves ranges from a few percent down to a few tenths of a percent. This is consistent with the observation that explosions in granite produce more severe ground motion than corresponding explosions in alluvium. The effects of explosion yield and rock properties on the frequency spectrum of the seismic source function are demonstrated by both experimental measurements and theoretical analysis. The characteristics of an ideal elastic medium are such that its frequency response is that of a low-pass filter, with its cutoff frequency being a function of the elastic properties of the material and the radius at which the explosion-produced stress wave becomes elastic. There is further frequency- and distance-dependent attenuation (especially of the higher frequencies) of the seismic waves, because rocks are not

Shock compression and flash-heating of molecular adsorbates on the picosecond time scale

Science.gov (United States)

Berg, Christopher Michael

An ultrafast nonlinear coherent laser spectroscopy termed broadband multiplex vibrational sum-frequency generation (SFG) with nonresonant suppression was employed to monitor vibrational transitions of molecular adsorbates on metallic substrates during laser-driven shock compression and flash-heating. Adsorbates were in the form of well-ordered self-assembled monolayers (SAMs) and included molecular explosive simulants, such as nitroaromatics, and long chain-length alkanethiols. Based on reflectance measurements of the metallic substrates, femtosecond flash-heating pulses were capable of producing large-amplitude temperature jumps with DeltaT = 500 K. Laser-driven shock compression of SAMs produced pressures up to 2 GPa, where 1 GPa ≈ 1 x 104 atm. Shock pressures were estimated via comparison with frequency shifts observed in the monolayer vibrational transitions during hydrostatic pressure measurements in a SiC anvil cell. Molecular dynamics during flash-heating and shock loading were probed with vibrational SFG spectroscopy with picosecond temporal resolution and sub-nanometer spatial resolution. Flash-heating studies of 4-nitrobenzenethiolate (NBT) on Au provided insight into effects from hot-electron excitation of the molecular adsorbates at early pump-probe delay times. At longer delay times, effects from the excitation of SAM lattice modes and lower-energy NBT vibrations were shown. In addition, flash-heating studies of alkanethiolates demonstrated chain disordering behaviors as well as interface thermal conductances across the Au-SAM junction, which was of specific interest within the context of molecular electronics. Shock compression studies of molecular explosive simulants, such as 4-nitrobenzoate (NBA), demonstrated the proficiency of this technique to observe shock-induced molecular dynamics, in this case orientational dynamics, on the picosecond time scale. Results validated the utilization of these refined shock loading techniques to probe the shock

SN 2016X: a type II-P supernova with a signature of shock breakout from explosion of a massive red supergiant

Science.gov (United States)

Huang, F.; Wang, X.-F.; Hosseinzadeh, G.; Brown, P. J.; Mo, J.; Zhang, J.-J.; Zhang, K.-C.; Zhang, T.-M.; Howell, D.-A.; Arcavi, I.; McCully, C.; Valenti, S.; Rui, L.-M.; Song, H.; Xiang, D.-F.; Li, W.-X.; Lin, H.; Wang, L.-F.

2018-04-01

We present extensive ultraviolet (UV) and optical photometry, as well as dense optical spectroscopy, for type II Plateau (IIP) supernova SN 2016X that exploded in the nearby (˜15 Mpc) spiral galaxy UGC 08041. The observations span the period from 2 to 180 d after the explosion; in particular, the Swift UV data probably captured the signature of shock breakout associated with the explosion of SN 2016X. It shows very strong UV emission during the first week after explosion, with a contribution of ˜20-30 per cent to the bolometric luminosity (versus ≲15 per cent for normal SNe IIP). Moreover, we found that this supernova has an unusually long rise time of about 12.6 ± 0.5 d in the R band (versus ˜7.0 d for typical SNe IIP). The optical light curves and spectral evolution are quite similar to the fast-declining type IIP object SN 2013ej, except that SN 2016X has a relatively brighter tail. Based on the evolution of photospheric temperature as inferred from the Swift data in the early phase, we derive that the progenitor of SN 2016X has a radius of about 930 ± 70 R⊙. This large-size star is expected to be a red supergiant star with an initial mass of ≳19-20 M⊙ based on the mass-radius relation of the Galactic red supergiants, and it represents one of the most largest and massive progenitors found for SNe IIP.

Underwater wireless communication system

International Nuclear Information System (INIS)

Goh, J H; Shaw, A; Al-Shamma'a, A I

2009-01-01

Underwater communication has a range of applications including remotely operated vehicle (ROV) and autonomous underwater vehicle (AUV) communication and docking in the offshore industry. Current underwater transmission techniques is primarily utilise sound waves for large distance at lower frequencies and the velocity of sound in water is approximately 1500m/s the resultant communications have problems with multi-path propagation and low bandwidth problems. The use of electromagnetic (EM) techniques underwater has largely been overlooked because of the attenuation due to the conductivity of seawater. However, for short range applications, the higher frequencies and much higher velocity can prove advantageous. This paper will outline a project which will utilise recent investigations that demonstrate EM wave propagation up to the MHz frequency range is possible in seawater.

Underwater Scene Composition

Science.gov (United States)

Kim, Nanyoung

2009-01-01

In this article, the author describes an underwater scene composition for elementary-education majors. This project deals with watercolor with crayon or oil-pastel resist (medium); the beauty of nature represented by fish in the underwater scene (theme); texture and pattern (design elements); drawing simple forms (drawing skill); and composition…

Near-Source Mechanism for Creating Shear Content from Buried Explosions

Science.gov (United States)

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

Resources for Underwater Robotics Education

Science.gov (United States)

Wallace, Michael L.; Freitas, William M.

2016-01-01

4-H clubs can build and program underwater robots from raw materials. An annotated resource list for engaging youth in building underwater remotely operated vehicles (ROVs) is provided. This article is a companion piece to the Research in Brief article "Building Teen Futures with Underwater Robotics" in this issue of the "Journal of…

A new technique for robot vision in autonomous underwater vehicles using the color shift in underwater imaging

Science.gov (United States)

2017-06-01

FOR ROBOT VISION IN AUTONOMOUS UNDERWATER VEHICLES USING THE COLOR SHIFT IN UNDERWATER IMAGING by Jake A. Jones June 2017 Thesis Advisor...techniques to determine the distances from each pixel to the camera. 14. SUBJECT TERMS unmanned undersea vehicles (UUVs), autonomous ... AUTONOMOUS UNDERWATER VEHICLES USING THE COLOR SHIFT IN UNDERWATER IMAGING Jake A. Jones Lieutenant Commander, United States Navy B.S

Residual stress improvement mechanism on metal material by underwater laser irradiation

International Nuclear Information System (INIS)

Sano, Yuji; Yoda, Masaki; Mukai, Naruhiko; Obata, Minoru; Kanno, Masanori

2000-01-01

Residual stress improvement technology for component surface by underwater pulsed laser irradiation has been developed as a method of preventing stress corrosion cracking (SCC) of core components in nuclear reactors. In order to optimize the laser irradiation conditions based on a complete understanding of the mechanism, the propagation of a shock wave induced by the impulse of laser irradiation and the dynamic response of the irradiated material were analyzed through time-dependent elasto-plastic calculations with a finite element program. The calculated results are compared with the measured results obtained by experiments in which laser pulses with an energy of 200 mJ are focused to a diameter of 0.8 mm on a water-immersed test piece of 20% cold-worked Type 304 austenitic stainless steel to simulate neutron irradiation hardening. A residual compressive stress, which is nearly equivalent to the yield stress of the processed material, remains on the material surface after passage of the shock wave with enough amplitude to induce a permanent strain. Multiple irradiation of laser pulses extends the stress-improved depth to about 1 mm, which would be the limit corresponding to the three-dimensional dispersion effect of the shock wave. (author)

Experimental Study on Reaction Characteristics of PTFE/Ti/W Energetic Materials under Explosive Loading

Directory of Open Access Journals (Sweden)

Yan Li

2016-11-01

Full Text Available Metal/fluoropolymer composites represent a new category of energetic structural materials that release energy through exothermic chemical reactions initiated under shock loading conditions. This paper describes an experiment designed to study the reaction characteristics of energetic materials with low porosity under explosive loading. Three PTFE (polytetrafluoroethylene/Ti/W mixtures with different W contents are processed through pressing and sintering. An inert PTFE/W mixture without reactive Ti particles is also prepared to serve as a reference. Shock-induced chemical reactions are recorded by high-speed video through a narrow observation window. Related shock parameters are calculated based on experimental data, and differences in energy release are discussed. The results show that the reaction propagation of PTFE/Ti/W energetic materials with low porosity under explosive loading is not self-sustained. As propagation distance increases, the energy release gradually decreases. In addition, reaction failure distance in PTFE/Ti/W composites is inversely proportional to the W content. Porosity increased the failure distance due to higher shock temperature.

Improved Reactive Flow Modeling of the LX-17 Double Shock Experiments

Science.gov (United States)

Rehagen, Thomas J.; Vitello, Peter

2017-06-01

Over driven double shock experiments provide a measurement of the properties of the reaction product states of the insensitive high explosive LX-17 (92.5% TATB and 7.5% Kel-F by weight). These experiments used two flyer materials mounted on the end of a projectile to send an initial shock through the LX-17, followed by a second shock of a higher magnitude into the detonation products. In the experiments, the explosive was initially driven by the flyer plate to pressures above the Chapman-Jouguet state. The particle velocity history was recorded by Photonic Doppler Velocimetry (PDV) probes pointing at an aluminum foil coated LiF window. The PDV data shows a sharp initial shock and decay, followed by a rounded second shock. Here, the experimental results are compared to 2D and 3D Cheetah reactive flow modeling. Our default Cheetah reactive flow model fails to accurately reproduce the decay of the first shock or the curvature or strength of the second shock. A new model is proposed in which the carbon condensate produced in the reaction zone is controlled by a kinetic rate. This allows the carbon condensate to be initially out of chemical equilibrium with the product gas. This new model reproduces the initial detonation peak and decay, and matches the curvature of the second shock, however, it still over-predicts the strength of the second shock. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

The effect of moisture content on the explosively driven fragmentation of wet sand

International Nuclear Information System (INIS)

Xue, K

2014-01-01

A comprehensive model is established to account for the instability onset of rapidly expanding granular shells subject to the explosion loadings generated by the detonation of the central explosives. The moisture content strongly influences the shock interactions in the wet particle beds and the ensuing evolvement of the granular compacts. A material model for granular materials which can account for the degree of saturation was incorporated into a nonlinear dynamic simulation program to investigate the moisture effect on the shock responses of wet granular materials. In conjunction with our instability model, the predicted instability diameters of the expanding dry/wet granular shells are in a good agreement with the experimental results. Particularly the postponed instability onset of the wet granular shell found both experimentally and analytically can largely be attributed to the significantly greater kinetic energy obtained by wet particles thanks to less energy of shock wave consumed in compacting the granular material.

THE BIGGEST EXPLOSIONS IN THE UNIVERSE

International Nuclear Information System (INIS)

Johnson, Jarrett L.; Whalen, Daniel J.; Smidt, Joseph; Even, Wesley; Fryer, Chris L.; Heger, Alex; Chen, Ke-Jung

2013-01-01

Supermassive primordial stars are expected to form in a small fraction of massive protogalaxies in the early universe, and are generally conceived of as the progenitors of the seeds of supermassive black holes (BHs). Supermassive stars with masses of ∼55, 000 M ☉ , however, have been found to explode and completely disrupt in a supernova (SN) with an energy of up to ∼10 55 erg instead of collapsing to a BH. Such events, ∼10, 000 times more energetic than typical SNe today, would be among the biggest explosions in the history of the universe. Here we present a simulation of such a SN in two stages. Using the RAGE radiation hydrodynamics code, we first evolve the explosion from an early stage through the breakout of the shock from the surface of the star until the blast wave has propagated out to several parsecs from the explosion site, which lies deep within an atomic cooling dark matter (DM) halo at z ≅ 15. Then, using the GADGET cosmological hydrodynamics code, we evolve the explosion out to several kiloparsecs from the explosion site, far into the low-density intergalactic medium. The host DM halo, with a total mass of 4 × 10 7 M ☉ , much more massive than typical primordial star-forming halos, is completely evacuated of high-density gas after ∼ ☉ after ∼> 70 Myr. The chemical signature of supermassive star explosions may be found in such long-lived second-generation stars today

Physics of phenomena in the zone close to an underground nuclear explosion; Physique des phenomenes en zone proche des explosions nucleaires souterraines

Energy Technology Data Exchange (ETDEWEB)

Maury, J.; Levret, C. [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

1969-07-01

After a description of the phenomenology of underground explosions, the basic laws governing the propagation in the ground of the energy produced by the explosion are given. The reports considers hydrodynamics, the mechanics of solids, the equations of state for solids and gases in the case of very high and medium pressures, and the dynamical strength of solids. These various elements make it possible to draw up a system of equations which define completely the changes with time of the shock-wave produced in the ground by the explosion. (authors) [French] Apres une description de la phenomenologie des explosions souterraines, on expose les lois fondamentales regissant la propagation dans le sol de l'energie degagee par l'explosion. L'expose comprend des developpements sur l'hydrodynamique, la mecanique des solides, les equations d'etat des solides et des gaz, aux tres fortes et moyennes pressions, et sur la resistance dynamique des solides. Ces differents elements permettent d'ecrire un systeme d'equations qui definissent completement l'evolution dans le temps de l'onde de choc emise dans le sol par l'explosion. (auteurs)

Shock initiation experiments on ratchet grown PBX 9502

Energy Technology Data Exchange (ETDEWEB)

Gustavsen, Richard L [Los Alamos National Laboratory; Thompson, Darla G [Los Alamos National Laboratory; Olinger, Barton W [Los Alamos National Laboratory; Deluca, Racci [Los Alamos National Laboratory; Bartram, Brian D [Los Alamos National Laboratory; Pierce, Timothy H [Los Alamos National Laboratory; Sanchez, Nathaniel J [Los Alamos National Laboratory

2010-01-01

This study compares the shock initiation behavior of PBX 9502 pressed to less than nominal density (nominal density is 1.890 {+-} 0.005 g/cm{sup 3}) with PBX 9502 pressed to nominal density and then ''ratchet grown'' to low density. PBX 9502 is an insensitive plastic bonded explosive consisting of 95 weight % dry-aminated tri-amino-tri-nitro-benzene (TATB) and 5 weight % Kel-F 800 plastic binder. ''Ratchet growth'' - an irreversible increase in specific volume - occurs when an explosive based on TATB is temperature cycled. The design of our study is as follows: PBX 9502, all from the same lot, received the following four treatments. Samples in the first group were pressed to less than nominal density. These were not ratchet grown and used as a baseline. Samples in the second group were pressed to nominal density and then ratchet grown by temperature cycling 30 times between -54 C and +80 C. Samples in the final group were pressed to nominal density and cut into 100 mm by 25.4 mm diameter cylinders. During thermal cycling the cylinders were axially constrained by a 100 psi load. Samples for shock initiation experiments were cut perpendicular (disks) and parallel (slabs) to the axial load. The four sample groups can be summarized with the terms pressed low, ratchet grown/no load, axial load/disks, and axial load/slabs. All samples were shock initiated with nearly identical inputs in plate impact experiments carried out on a gas gun. Wave profiles were measured after propagation through 3, 4, 5, and 6 mm of explosive. Side by side comparison of wave profiles from different samples is used as a measure of relative sensitivity. All reduced density samples were more shock sensitive than nominal density PBX 9502. Differences in shock sensitivity between ratchet grown and pressed to low density PBX 9502 were small, but the low density pressings are slightly more sensitive than the ratchet grown samples.

Stability analysis of hybrid-driven underwater glider

Science.gov (United States)

Niu, Wen-dong; Wang, Shu-xin; Wang, Yan-hui; Song, Yang; Zhu, Ya-qiang

2017-10-01

Hybrid-driven underwater glider is a new type of unmanned underwater vehicle, which combines the advantages of autonomous underwater vehicles and traditional underwater gliders. The autonomous underwater vehicles have good maneuverability and can travel with a high speed, while the traditional underwater gliders are highlighted by low power consumption, long voyage, long endurance and good stealth characteristics. The hybrid-driven underwater gliders can realize variable motion profiles by their own buoyancy-driven and propeller propulsion systems. Stability of the mechanical system determines the performance of the system. In this paper, the Petrel-II hybrid-driven underwater glider developed by Tianjin University is selected as the research object and the stability of hybrid-driven underwater glider unitedly controlled by buoyancy and propeller has been targeted and evidenced. The dimensionless equations of the hybrid-driven underwater glider are obtained when the propeller is working. Then, the steady speed and steady glide path angle under steady-state motion have also been achieved. The steady-state operating conditions can be calculated when the hybrid-driven underwater glider reaches the desired steady-state motion. And the steadystate operating conditions are relatively conservative at the lower bound of the velocity range compared with the range of the velocity derived from the method of the composite Lyapunov function. By calculating the hydrodynamic coefficients of the Petrel-II hybrid-driven underwater glider, the simulation analysis has been conducted. In addition, the results of the field trials conducted in the South China Sea and the Danjiangkou Reservoir of China have been presented to illustrate the validity of the analysis and simulation, and to show the feasibility of the method of the composite Lyapunov function which verifies the stability of the Petrel-II hybrid-driven underwater glider.

Liquid--liquid contact in vapor explosion

International Nuclear Information System (INIS)

Segev, A.

1978-08-01

The contact of two liquid materials, one of which is at a temperature substantially above the boiling point of the other, can lead to fast energy conversion and a subsequent shock wave. This well-known phenomenon is called a ''vapor explosion.'' One method of producing intimate, liquid--liquid contact (which is known to be a necessary condition for vapor explosion) is a shock tube configuration. Such experiments in which water was impacted upon molten aluminum showed that very high pressures, even larger than the thermodynamic critical pressure, could occur. The mechanism by which such sharp pressure pulses are generated is not yet clear. In this experiment cold liquids (Freon-11, Freon-22, water, or butanol) were impacted upon various hot materials (mineral oil, silicone oil, water, mercury, molten Wood's metal or molten salt mixture). The main conclusion from the experimental study is that hydrodynamic effects may be very significant in any shock tube analyses, especially when multiple interactions are observed. A theoretical study was performed to check the possibility of vapor film squeezing (between a drop in film boiling and a surface) as a controlling mechanism for making liquid--liquid contact. Using experimental data, the film thickness was calculated and it was found to be too thick for any conceivable film rupture mechanism. It was suggested that the coalescence is a two-stage process, in which the controlling stage depends mainly on temperature and surface properties and can be described as the ability of cold liquid to spread on a hot surface

Investigation of shock compressed plasma parameters by interaction with magnetic field

International Nuclear Information System (INIS)

Dudin, S. V.; Fortov, V. E.; Gryaznov, V. K.; Mintsev, V. B.; Shilkin, N. S.; Ushnurtsev, A. E.

1998-01-01

The Hall effect parameters in shock compressed air, helium and xenon have been estimated and results of experiments with air and helium plasma are presented. Explosively driven shock tubes were used for the generation of strong shock waves. To obtain magnetic field a solenoid was winded over the shock tube. Calculations of dense shock compressed plasma parameters were carried out to plan the experiments. In the experiments with the magnetic field of ∼5 T it was found, that air plasma slug was significantly heated by the whirlwind electrical field. The reflected shock waves technique was used in the experiments with helium. Results on measurements of electrical conductivity and electron concentration of helium are presented

Seismic characterization of the Chelyabinsk meteor's terminal explosion

Science.gov (United States)

González, Álvaro; Heimann, Sebastian; Wang, Rongjiang; Cesca, Simone; Dahm, Torsten

2014-05-01

On February 15th, 2013, an exceptionally large meteor in the region of Chelyabinsk, Russia, produced a powerful shock wave which caused unprecedented damage to people and property, the strongest atmospheric infrasound signal ever recorded, and remarkable ground motion. Here we describe and model the resulting Rayleigh waves, recorded at broadband seismic stations at distances from ~230 to ~4,100 km. Our full-waveform modeling uses a seismogram simulation code specifically tailored to consider wave propagation in the atmosphere and solid Earth, and the coupling at the interface between them. An isotropic point-like airburst reproduces very well the available seismic observations, without requiring a more complex explanation, such as a moving source. The measured seismic shaking was generated by direct coupling of the atmospheric shock wave to the ground, and then it propagated outwards faster than the atmospheric shock wave itself, at up to 3.9 km/s. The best-fitting airburst location (61.22° E, 54.88° N) is SW of Chelyabinsk city, exactly at the terminal part of the meteor's trajectory, just after it experienced a dramatic flare, with apparent brightness larger than the Sun's. We estimated the meteor's ground path from published trajectory data, eyewitness observations, and detailed satellite imagery of the exact location where a major meteorite fragment landed, in the frozen Lake Chebarkul (60.32074° E, 54.95966° N). Fixing the source origin time allowed us calculating that the explosion took place in the stratosphere, at an altitude of 22.5 ± 1.5 km. This value is lower than the reported altitude of peak brightness (about 29.5 km), but more consistent with the observations of shock wave travel times. Such results highlight the importance of terminal energy release down to lower altitude. We analyzed a surveillance video recorded inside a factory (61.347° E, 54.902° N) at Korkino, a locality close to the airburst. It shows a time delay of 87.5 seconds

Shock compression of nitrobenzene; Nitoro benzen no shogeki asshoku

Energy Technology Data Exchange (ETDEWEB)

Kozu, Naoshi; Arai, Mitsuru; Tamura, Masamitsu [The University of Tokyo, Tokyo (Japan). Department of Chemical System Engineering; Yoshida, Masatake [National Institute of Materials and Chemical Research, Tsukuba (Japan)

1999-08-31

The Hugoniot (4 - 30 x 10{sup 9}Pa) of nitrobenzene has been obtained by shock compression experiments. Explosive plane-wae generators were used for plane shock wave generation. The obtained Hugoniot consists of two linear lines (U{sub s} (x 10{sup 3}m/s) = 2.52 + 1.23U{sub p} (x 10{sup 3}m/s)(0.8explosives and V.V.Yakyshev's experiments of shock compression of nitrobenzene. (author)

Experimental Study of the Effect of Water Mist Location On Blast Overpressure Attenuation in A Shock Tube

Science.gov (United States)

Mataradze, Edgar; Chikhradze, Nikoloz; Bochorishvili, Nika; Akhvlediani, Irakli; Tatishvili, Dimitri

2017-12-01

Explosion protection technologies are based on the formation of a shock wave mitigation barrier between the protection site and the explosion site. Contemporary protective systems use water mist as an extinguishing barrier. To achieve high effectiveness of the protective system, proper selection of water mist characteristics is important. The main factors defining shock wave attenuation in water mist include droplet size distribution, water concentration in the mist, droplet velocity and geometric properties of mist. This paper examines the process of attenuation of shock waves in mist with droplets ranging from 25 to 400 microns under different conditions of water mist location. Experiments were conducted at the Mining Institute with the use of a shock tube to study the processes of explosion suppression by a water mist barrier. The shock tube consists of a blast chamber, a tube, a system for the dosed supply of water, sensors, data recording equipment, and a process control module. Shock wave overpressure reduction coefficient was studied in the shock tube under two different locations of water mist: a) when water mist is created in direct contact with blast chamber and b) the blast chamber and the mist are separated by air space. It is established that in conditions when the air space distance between the blast chamber and the mist is 1 meter, overpressure reduction coefficient is 1.5-1.6 times higher than in conditions when water mist is created in direct contact with blast chamber.

ROV Based Underwater Blurred Image Restoration

Institute of Scientific and Technical Information of China (English)

LIU Zhishen; DING Tianfu; WANG Gang

2003-01-01

In this paper, we present a method of ROV based image processing to restore underwater blurry images from the theory of light and image transmission in the sea. Computer is used to simulate the maximum detection range of the ROV under different water body conditions. The receiving irradiance of the video camera at different detection ranges is also calculated. The ROV's detection performance under different water body conditions is given by simulation. We restore the underwater blurry images using the Wiener filter based on the simulation. The Wiener filter is shown to be a simple useful method for underwater image restoration in the ROV underwater experiments. We also present examples of restored images of an underwater standard target taken by the video camera in these experiments.

Mechanical vibration and shock analysis, sinusoidal vibration

CERN Document Server

Lalanne, Christian

2014-01-01

Everything engineers need to know about mechanical vibration and shock...in one authoritative reference work! This fully updated and revised 3rd edition addresses the entire field of mechanical vibration and shock as one of the most important types of load and stress applied to structures, machines and components in the real world. Examples include everything from the regular and predictable loads applied to turbines, motors or helicopters by the spinning of their constituent parts to the ability of buildings to withstand damage from wind loads or explosions, and the need for cars to m

Wireless device for activation of an underground shock wave absorber

Science.gov (United States)

Chikhradze, M.; Akhvlediani, I.; Bochorishvili, N.; Mataradze, E.

2011-10-01

The paper describes the mechanism and design of the wireless device for activation of energy absorber for localization of blast energy in underground openings. The statistics shows that the greatest share of accidents with fatal results associate with explosions in coal mines due to aero-methane and/or air-coal media explosion. The other significant problem is terrorist or accidental explosions in underground structures. At present there are different protective systems to reduce the blast energy. One of the main parts of protective Systems is blast Identification and Registration Module. The works conducted at G. Tsulukidze Mining Institute of Georgia enabled to construct the wireless system of explosion detection and mitigation of shock waves. The system is based on the constant control on overpressure. The experimental research continues to fulfill the system based on both threats, on the constant control on overpressure and flame parameters, especially in underground structures and coal mines. Reaching the threshold value of any of those parameters, the system immediately starts the activation. The absorber contains a pyrotechnic device ensuring the discharge of dispersed water. The operational parameters of wireless device and activation mechanisms of pyrotechnic element of shock wave absorber are discussed in the paper.

Underwater 3D filming

Directory of Open Access Journals (Sweden)

Roberto Rinaldi

2014-12-01

Full Text Available After an experimental phase of many years, 3D filming is now effective and successful. Improvements are still possible, but the film industry achieved memorable success on 3D movie’s box offices due to the overall quality of its products. Special environments such as space (“Gravity” and the underwater realm look perfect to be reproduced in 3D. “Filming in space” was possible in “Gravity” using special effects and computer graphic. The underwater realm is still difficult to be handled. Underwater filming in 3D was not that easy and effective as filming in 2D, since not long ago. After almost 3 years of research, a French, Austrian and Italian team realized a perfect tool to film underwater, in 3D, without any constrains. This allows filmmakers to bring the audience deep inside an environment where they most probably will never have the chance to be.

Self-similar dynamic converging shocks - I. An isothermal gas sphere with self-gravity

Science.gov (United States)

Lou, Yu-Qing; Shi, Chun-Hui

2014-07-01

We explore novel self-similar dynamic evolution of converging spherical shocks in a self-gravitating isothermal gas under conceivable astrophysical situations. The construction of such converging shocks involves a time-reversal operation on feasible flow profiles in self-similar expansion with a proper care for the increasing direction of the specific entropy. Pioneered by Guderley since 1942 but without self-gravity so far, self-similar converging shocks are important for implosion processes in aerodynamics, combustion, and inertial fusion. Self-gravity necessarily plays a key role for grossly spherical structures in very broad contexts of astrophysics and cosmology, such as planets, stars, molecular clouds (cores), compact objects, planetary nebulae, supernovae, gamma-ray bursts, supernova remnants, globular clusters, galactic bulges, elliptical galaxies, clusters of galaxies as well as relatively hollow cavity or bubble structures on diverse spatial and temporal scales. Large-scale dynamic flows associated with such quasi-spherical systems (including collapses, accretions, fall-backs, winds and outflows, explosions, etc.) in their initiation, formation, and evolution are likely encounter converging spherical shocks at times. Our formalism lays an important theoretical basis for pertinent astrophysical and cosmological applications of various converging shock solutions and for developing and calibrating numerical codes. As examples, we describe converging shock triggered star formation, supernova explosions, and void collapses.

Underwater welding of steel

International Nuclear Information System (INIS)

Ibarra, S.; Olson, D.L.

1992-01-01

A fundamental basis to understand the behavior of wet underwater welding of steel is introduced. Both the pyrometallurgical and physical metallurgy concepts are discussed. Modifications of welding consumables and practice are suggested. This chapter promotes further contributions of meatllurgical research to improve and promote wet underwater welding. (orig.)

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

Science.gov (United States)

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

Microprocessor-controlled time domain reflectometer for dynamic shock position measurements

International Nuclear Information System (INIS)

Virchow, C.F.; Conrad, G.E.; Holt, D.M.; Hodson, E.K.

1980-01-01

Time-domain reflectometry is used in a novel way to measure dynamically shock propagation in various media. The primary component in this measurement system is a digital time domain reflectometer, which uses local intelligence, a Motorola 6800 microprocessor, to make the unit adaptable and versatile. The recorder, its operating theory and its method of implementation are described and typical data are reviewed. Applications include nuclear explosion yield estimates and explosive energy flow measurements

Colour reconstruction of underwater images

OpenAIRE

Hoth, Julian; Kowalczyk, Wojciech

2017-01-01

Objects look very different in the underwater environment compared to their appearance in sunlight. Images with correct colouring simplify the detection of underwater objects and may allow the use of visual SLAM algorithms developed for land-based robots underwater. Hence, image processing is required. Current algorithms focus on the colour reconstruction of scenery at diving depth where different colours can still be distinguished. At greater depth this is not the case. In this study it is i...

Quantum imaging for underwater arctic navigation

Science.gov (United States)

Lanzagorta, Marco

2017-05-01

The precise navigation of underwater vehicles is a difficult task due to the challenges imposed by the variable oceanic environment. It is particularly difficult if the underwater vehicle is trying to navigate under the Arctic ice shelf. Indeed, in this scenario traditional navigation devices such as GPS, compasses and gyrocompasses are unavailable or unreliable. In addition, the shape and thickness of the ice shelf is variable throughout the year. Current Arctic underwater navigation systems include sonar arrays to detect the proximity to the ice. However, these systems are undesirable in a wartime environment, as the sound gives away the position of the underwater vehicle. In this paper we briefly describe the theoretical design of a quantum imaging system that could allow the safe and stealthy navigation of underwater Arctic vehicles.

Shock tube Multiphase Experiments

Science.gov (United States)

Middlebrooks, John; Allen, Roy; Paudel, Manoj; Young, Calvin; Musick, Ben; McFarland, Jacob

2017-11-01

Shock driven multiphase instabilities (SDMI) are unique physical phenomena that have far-reaching practical applications in engineering and science. The instability is present in high energy explosions, scramjet combustors, and supernovae events. The SDMI arises when a multiphase interface is impulsively accelerated by the passage of a shockwave. It is similar in development to the Richtmyer-Meshkov (RM) instability however, particle-to-gas coupling is the driving mechanism of the SDMI. As particle effects such as lag and phase change become more prominent, the SDMI's development begins to significantly deviate from the RM instability. We have developed an experiment for studying the SDMI in our shock tube facility. In our experiments, a multiphase interface is created using a laminar jet and flowed into the shock tube where it is accelerated by the passage of a planar shockwave. The interface development is captured using CCD cameras synchronized with planar laser illumination. This talk will give an overview of new experiments conducted to examine the development of a shocked cylindrical multiphase interface. The effects of Atwood number, particle size, and a second acceleration (reshock) of the interface will be discussed.

Autonomous Underwater Gliders

OpenAIRE

Wood,; Stephen,

2009-01-01

Autonomous Underwater Vehicles are only now being marketed as robust commercial vehicles for many industries, and of these vehicles underwater gliders are becoming the new tool for oceanographers. Satellites have provided scientists and marine specialists with measurements of the sea surface such as temperature since the late 1970s, and data via subsurface oceanographic moorings since the 1950's. As stated by David Smeed of the National Oceanography Centre, Southampton, England, that "gliders...

An integral view of fast shocks around supernova 1006

NARCIS (Netherlands)

Nikolic, S.; Heng, K.; Kupko, D.; Husemann, B.; Raymond, J.C.; Hughes, J.P.; Falcon-Barroso, J.; Ven, G. van de

2013-01-01

Supernova remnants are among the most spectacular examples of astrophysical pistons in our cosmic neighborhood. The gas expelled by the supernova explosion is launched with velocities ~1000 kilometers per second into the ambient, tenuous interstellar medium, producing shocks that excite hydrogen

Underwater welding using remote controlled robots. Development of remote underwater welding technology with a high power YAG laser

International Nuclear Information System (INIS)

Miwa, Yasuhiro; Sato, Syuuichi; Kojima, Toshio; Owaki, Katsura; Hirose, Naoya

2002-01-01

As components in nuclear power plant have been periodically carried out their inspection and repair to keep their integrity, on radioactive liquid wastes storage facility, because of difficulty on their inspection by human beings, some are remained without inspection, and even when capable of inspection, conversion from human works to remote operations is desired from a viewpoint of their operation efficiency upgrading. For response to these needs, some developments on a technology capable of carrying out inspection of their inside at underwater environment and repairing welding with YAG laser by means of remote operation, have been performed. Remote underwater inspection and repair technology is a combination technology of already applied underwater mobile technique (underwater inspection robot) with underwater YAG laser welding technique which is recently at actual using level. Therefore, this technology is composed of an inspection robot and a repair welding robot. And, testing results using the underwater inspection robot and welding test results using the underwater repair welding robot, were enough preferable to obtain forecasting applicable to actual apparatuses. This technology is especially effective for inspection and repair of inside of nuclear fuel cycle apparatuses and relatively high dose apparatuses, and can be thought to be applicable also to large capacity tanks, tanks dealing with harmful matters, underwater structures, and so on, in general industries. (G.K.)

Observations of Tin/Water Thermal Explosions in a Long-Tube Geometry. Their Interpretation and Consequences for the Detonation Model

International Nuclear Information System (INIS)

Hall, R.W.; Board, S.J.; Baines, M.

1979-01-01

This paper presents details of experiments designed to test the detonation model of thermal explosions (Board et al, 1975); on this theory large-scale explosions should propagate steadily at supersonic velocities through a fuel coolant mixture, giving a yield which has been shown to depend on details of the fragmentation and heat transfer behind the shock front. Observations of propagating explosions have been reported previously. In the present work, a long-tube geometry is used since in 1D, propagation measurements are particularly easy to interpret. Also, in 2D and 3D geometries radial flow can tend to extinguish shock waves and if a single-phase region of coolant is present, pressure pulses can propagate ahead of the two-phase shock in the intermixed region. This paper describes the six experiments that all use molten tin and water mixtures. In the first four, detailed pressure measurement was the main objective; the last two are attempts at flow visualization to aid the interpretation of these. The results obtained and the implications for the detonation model are discussed. A detailed interpretation in terms of fragmentation and heat transfer processes behind the shock is attempted. The implications of the work for reactor materials are then briefly outlined

Methane Explosion Mitigation in Coal Mines by Water Mist

Science.gov (United States)

Chikhradze, Nikoloz; Mataradze, Edgar; Chikhradze, Mikheil; Krauthammer, Ted; Mansurov, Zulkhair; Alyiev, Erhan

2017-12-01

Statistics shows that the majority of accidents with fatal outcome are caused by methane and/or coal dust explosion. This leads to assume that contemporary counter-explosion systems of various designs cannot be considered effective. Considering the growing threat of methane explosion in the coming years along with the development of deeper levels, the improvement of a system for protecting people in underground opening appears urgent. This paper focuses on technical solutions to be used in designing a protective system for minimizing the consequences of methane explosions in coalmines. The new protective system consists of three main modules: i) a high-speed shock wave suppression section; ii) a suppression section with a long-term action and iii) a system activating device. The shock wave suppressor contains a 200 litre volume water tank with a built-in gas generator and nozzles. It is activated after 12ms from the blast moment, the duration of discharge is 40 s. The suppression section with a long-term action contains a 2000 litre volume water tank, a high-pressure pump, a hydraulic accumulator, solenoid valves, and a system of pipes with built-in nozzles. It is activated after 4 s from the blast moment, the duration of discharge is 8 min. The activation device includes a detection block containing sensors, an emergency signal generation module, a signal transmission module, a signal receiving module and a power supply module. The system operates in a waiting mode and activates immediately upon the receipt of the start signal generated by the detector. The paper also addresses the preliminary results of the system prototype testing in the tunnel.

Shock wave interactions with detonable clouds

International Nuclear Information System (INIS)

Ripley, R.C.; Josey, T.; Donahue, L.; Whitehouse, D.R.

2004-01-01

This paper presents results from the numerical simulation of compressible multi-species gases in an unstructured mesh CFD code called Chinook. Multiple species gases are significant to a wide range of CFD applications that involve chemical reactions, in particular detonation. The purpose of this paper is to investigate the interaction of shock waves with localized regions of reactive and non-reactive gas species. Test cases are chosen to highlight shock reflection and acceleration through combustion products resulting from the detonation of an explosive charge, and detonation wave propagation through a fuel-air cloud. Computations are performed in a 2D axi-symmetric framework. (author)

Underwater Acoustic Networking Techniques

CERN Document Server

Otnes, Roald; Casari, Paolo; Goetz, Michael; Husøy, Thor; Nissen, Ivor; Rimstad, Knut; van Walree, Paul; Zorzi, Michele

2012-01-01

This literature study presents an overview of underwater acoustic networking. It provides a background and describes the state of the art of all networking facets that are relevant for underwater applications. This report serves both as an introduction to the subject and as a summary of existing protocols, providing support and inspiration for the development of network architectures.

EEC-sponsored theoretical studies of gas cloud explosion pressure loadings

International Nuclear Information System (INIS)

Briscoe, F.; Curtress, N.; Farmer, C.L.; Fogg, G.J.; Vaughan, G.J.

1979-01-01

Estimates of the pressure loadings produced by unconfined gas cloud explosions on the surface of structures are required to assist the design of strong secondary containments in countries where the protection of nuclear installations against these events is considered to be necessary. At the present time, one difficulty in the specification of occurate pressure loadings arises from our lack of knowledge concerning the interaction between the incident pressure waves produced by unconfined gas cloud explosions and large structures. Preliminary theoretical studies include (i) general theoretical considerations, especially with regard to scaling (ii) investigations of the deflagration wave interaction with a wall based on an analytic solution for situations with planar symmetry and the application of an SRD gas cloud explosion code (GASEX 1) for situations with planar and spherical symmetry, and (iii) investigations of the interaction between shock waves and structures for situations with two-dimensional symmetry based on the application of another SRD gas cloud explosion code (GASEX 2)

Monte Carlo study of neutrino acceleration in supernova shocks

International Nuclear Information System (INIS)

Kazanas, Demosthenes; Ellison, D.C.; National Aeronautics and Space Administration, Greenbelt, MD

1981-01-01

The first order Fermi acceleration mechanism of cosmic rays in shocks may be at work for neutrinos in supernova shocks when the latter are at densities rho>10 13 g cm -3 at which the core material is opaque to neutrinos. A Monte Carlo approach to study this effect is employed and the emerging neutrino power law spectra are presented. The increased energy acquired by the neutrinos may facilitate their detection in supernova explosions and provide information about the physics of collapse

Materials and structures under shock and impact

CERN Document Server

Bailly, Patrice

2013-01-01

In risk studies, engineers often have to consider the consequences of an accident leading to a shock on a construction. This can concern the impact of a ground vehicle or aircraft, or the effects of an explosion on an industrial site.This book presents a didactic approach starting with the theoretical elements of the mechanics of materials and structures, in order to develop their applications in the cases of shocks and impacts. The latter are studied on a local scale at first. They lead to stresses and strains in the form of waves propagating through the material, this movement then extending

OFDM for underwater acoustic communications

CERN Document Server

Zhou, Shengli

2014-01-01

A blend of introductory material and advanced signal processing and communication techniques, of critical importance to underwater system and network development This book, which is the first to describe the processing techniques central to underwater OFDM, is arranged into four distinct sections: First, it describes the characteristics of underwater acoustic channels, and stresses the difference from wireless radio channels. Then it goes over the basics of OFDM and channel coding. The second part starts with an overview of the OFDM receiver, and develops various modules for the receiver des

ALPHA visual data collection. STX005-025: melt drop steam explosion experiments

International Nuclear Information System (INIS)

Moriyama, Kiyofumi; Yamano, Norihiro; Maruyama, Yu; Kudo, Tamotsu; Sugimoto, Jun

1999-03-01

Steam explosion is a phenomenon in which a high temperature liquid gives its internal energy to a low temperature volatile liquid extremely quickly causing rapid evaporation and shock wave generation. In the field of nuclear reactor safety research regarding severe accidents in LWRs, steam explosions involving molten fuel and coolant has been recognized as a potential threat to the integrity of the reactor containment vessel. In the ALPHA (Assessment of Loads and Performance of Containment in Hypothetical Accident) program, experiments were performed to investigate the phenomenology of vapor explosions using iron-alumina thermite melt as a simulant of molten core. This report collects the experimental results especially emphasizing the visual observations by high speed photography. (author)

Underwater Acoustic Tracer System

Science.gov (United States)

2009-03-13

for controlling and utilizing supercavitating projectile dynamics to produce a distinctive radiated noise signal. (2) Description of the Prior Art...metallic objects which travel relatively closely to a magnetic pickup. For larger, high speed, underwater projectiles, supercavitating underwater vehicles...have been proposed for use. The conditions for supercavitation are known in the art. Supercavitation allows for higher speeds to be sustainable

SHOCK BREAKOUT IN TYPE II PLATEAU SUPERNOVAE: PROSPECTS FOR HIGH-REDSHIFT SUPERNOVA SURVEYS

International Nuclear Information System (INIS)

Tominaga, N.; Morokuma, T.; Blinnikov, S. I.; Nomoto, K.; Baklanov, P.; Sorokina, E. I.

2011-01-01

Shock breakout is the brightest radiative phenomenon in a supernova (SN) but is difficult to be observed owing to the short duration and X-ray/ultraviolet (UV)-peaked spectra. After the first observation from the rising phase reported in 2008, its observability at high redshift is attracting enormous attention. We perform multigroup radiation hydrodynamics calculations of explosions for evolutionary presupernova models with various main-sequence masses M MS , metallicities Z, and explosion energies E. We present multicolor light curves of shock breakouts in Type II plateau SNe, being the most frequent core-collapse SNe, and predict apparent multicolor light curves of shock breakout at various redshifts z. We derive the observable SN rate and reachable redshift as functions of filter x and limiting magnitude m x,lim by taking into account an initial mass function, cosmic star formation history, intergalactic absorption, and host galaxy extinction. We propose a realistic survey strategy optimized for shock breakout. For example, the g'-band observable SN rate for m g',lim = 27.5 mag is 3.3 SNe deg -2 day -1 and half of them are located at z ≥ 1.2. It is clear that the shock breakout is a beneficial clue for probing high-z core-collapse SNe. We also establish ways to identify shock breakout and constrain SN properties from the observations of shock breakout, brightness, timescale, and color. We emphasize that the multicolor observations in blue optical bands with ∼hour intervals, preferably over ≥2 continuous nights, are essential to efficiently detect, identify, and interpret shock breakout.

Shock-induced modification of the structure of yttria stabilised zirconia powder

International Nuclear Information System (INIS)

Frazer, B.G.; Killen, P.D.; Page, N.W.; Charleson, S.W.

1999-01-01

Full text: Powder samples of 3 mol% yttria stabilised zirconia were shock compacted in Russia using the explosive flyer plate compaction technique in which a flyer plate is driven by an explosive charge to impact on the surface of a target fixture containing the powder. In these experiments the impact velocity of the flyer plate was approximately 2130 m.s -1 . Initial precompaction densities of 30% and 60% of solid phase densities were used in the shock compaction process. The precompaction densities were responsible for the different values of the shock strength transmitted to the sample. These pressures were 5 GPa and 16 GPa (for the 30% and 60% dense samples respectively). Fragments of all shock compacted samples were obtained for analysis with the only exception being one of the 5 GPa samples which remained intact and was encased in a resin. X-Ray diffraction scans of the recovered samples were analysed using the Rietveld refinement program GSAS. Results show significant changes in crystallite size and strain and an alteration to the shape of the monoclinic lattice as well as the pressure induced phase change from cubic to tetragonal described in another paper. Copyright (1999) Australian X-ray Analytical Association Inc

'Surveyor': An Underwater System for Threat Material Detection

International Nuclear Information System (INIS)

Valkovic, Vladivoj; Sudac, Davorin; Nad, Karlo; Obhodas, Jasmina; Matika, Dario; Kollar, Robert

2010-01-01

The bottoms of the coastal seas, and oceans as well, are contaminated by many man-made objects including a variety of ammunition. This contamination is world wide spread with some areas being highly polluted presenting a serious threat to local population and to visitors as well. All littoral nations are investing lots of effort into the remediation of their coastal areas. Once the presence of the anomaly on the bottom of the shallow coastal sea water is confirmed (by visual identification and by using one or several sensors, namely magnetometer, sonar and optical cameras) it is necessary to establish if it contains explosive/chemical warfare charge. In our work we propose this to be performed by using neutron sensor installed within an underwater vessel - 'Surveyor'. When positioned above the object, or to its side, the system inspects the object for the presence of the threat material by using alpha particle tagged neutrons from the sealed tube d+t neutron generator. (author)

Human Factors Issues When Operating Underwater Remotely Operated Vehicles and Autonomous Underwater Vehicles

Science.gov (United States)

2011-03-01

etiquette (Parasuraman & Miller, 2004). Through natural and intuitive communication, Johnson et al., (2007) hope that this interface will instill greater...and etiquette in high criticality automated systems. Communications of the ACM, 47(4), 51-55. Parasuraman, R., & Riley, V. (1997). Humans and... protocols for underwater wireless communications. IEEE Communications Magazine, pp. 97-102. Quazi, A. H., & Konrad, W. L. (1982, March 1982). Underwater

EXPLOSIVE NUCLEOSYNTHESIS IN THE NEUTRINO-DRIVEN ASPHERICAL SUPERNOVA EXPLOSION OF A NON-ROTATING 15 Msun STAR WITH SOLAR METALLICITY

International Nuclear Information System (INIS)

Fujimoto, Shin-ichiro; Kotake, Kei; Hashimoto, Masa-aki; Ono, Masaomi; Ohnishi, Naofumi

2011-01-01

We investigate explosive nucleosynthesis in a non-rotating 15 M sun star with solar metallicity that explodes by a neutrino-heating supernova (SN) mechanism aided by both standing accretion shock instability (SASI) and convection. To trigger explosions in our two-dimensional hydrodynamic simulations, we approximate the neutrino transport with a simple light-bulb scheme and systematically change the neutrino fluxes emitted from the protoneutron star. By a post-processing calculation, we evaluate abundances and masses of the SN ejecta for nuclei with a mass number ≤70, employing a large nuclear reaction network. Aspherical abundance distributions, which are observed in nearby core-collapse SN remnants, are obtained for the non-rotating spherically symmetric progenitor, due to the growth of a low-mode SASI. The abundance pattern of the SN ejecta is similar to that of the solar system for models whose masses range between (0.4-0.5) M sun of the ejecta from the inner region (≤10, 000 km) of the precollapse core. For the models, the explosion energies and the 56 Ni masses are ≅ 10 51 erg and (0.05-0.06) M sun , respectively; their estimated baryonic masses of the neutron star are comparable to the ones observed in neutron-star binaries. These findings may have little uncertainty because most of the ejecta is composed of matter that is heated via the shock wave and has relatively definite abundances. The abundance ratios for Ne, Mg, Si, and Fe observed in the Cygnus loop are reproduced well with the SN ejecta from an inner region of the 15 M sun progenitor.

Shock wave science and technology reference library

CERN Document Server

2009-01-01

This book, as a volume of the Shock Wave Science and Technology Reference Library, is primarily concerned with detonation waves or compression shock waves in reactive heterogeneous media, including mixtures of solid, liquid and gas phases. The topics involve a variety of energy release and control processes in such media - a contemporary research field that has found wide applications in propulsion and power, hazard prevention as well as military engineering. The six extensive chapters contained in this volume are: - Spray Detonation (SB Murray and PA Thibault) - Detonation of Gas-Particle Flow (F Zhang) - Slurry Detonation (DL Frost and F Zhang) - Detonation of Metalized Composite Explosives (MF Gogulya and MA Brazhnikov) - Shock-Induced Solid-Solid Reactions and Detonations (YA Gordopolov, SS Batsanov, and VS Trofimov) - Shock Ignition of Particles (SM Frolov and AV Fedorov) Each chapter is self-contained and can be read independently of the others, though, they are thematically interrelated. They offer a t...

Energetic materials: crystallization, characterization and insensitive plastic bonded explosives

Energy Technology Data Exchange (ETDEWEB)

Heijden, Antoine E.D.M. van der; Creyghton, Yves L.M.; Marino, Emanuela; Bouma, Richard H.B.; Scholtes, Gert J.H.G.; Duvalois, Willem [TNO Defence, Security and Safety, P. O. Box 45, 2280 AA Rijswijk (Netherlands); Roelands, Marc C.P.M. [TNO Science and Industry, P. O. Box 342, 7300 AH Apeldoorn (Netherlands)

2008-02-15

The product quality of energetic materials is predominantly determined by the crystallization process applied to produce these materials. It has been demonstrated in the past that the higher the product quality of the solid energetic ingredients, the less sensitive a plastic bonded explosive containing these energetic materials becomes. The application of submicron or nanometric energetic materials is generally considered to further decrease the sensitiveness of explosives. In order to assess the product quality of energetic materials, a range of analytical techniques is available. Recent attempts within the Reduced-sensitivity RDX Round Robin (R4) have provided the EM community a better insight into these analytical techniques and in some cases a correlation between product quality and shock initiation of plastic bonded explosives containing (RS-)RDX was identified, which would provide a possibility to discriminate between conventional and reduced sensitivity grades. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

Spatial distribution of cavitation-shock-pressure around a jet-flow gate-valve

International Nuclear Information System (INIS)

Oba, Risaburo; Takayama, Kazuyoshi; Ito, Yukio; Miyakura, Hideto; Nozaki, Satoru; Ishige, Tadashi; Sonoda, Shuji; Sakamoto, Kenji.

1987-01-01

To make clear the mechanism of cavitation erosion, the spatial distribution of cavitation shock pressures were quantitatively measured by a pressure sensitive sheet in the 1/10 scale model of a jet-flow gate-valve, for various valve-openings and cavitation numbers. The dynamic pressure response of the sheet was corrected by the shock wave generated from detonation explosives. It is made clear that the erosive shock pressures are distributed in a limited part of the whole cavitation region, and the safety region without the fatal cavitation erosion is defined. (author)

Determining spherical lens correction for astronaut training underwater.

Science.gov (United States)

Porter, Jason; Gibson, C Robert; Strauss, Samuel

2011-09-01

To develop a model that will accurately predict the distance spherical lens correction needed to be worn by National Aeronautics and Space Administration astronauts while training underwater. The replica space suit's helmet contains curved visors that induce refractive power when submersed in water. Anterior surface powers and thicknesses were measured for the helmet's protective and inside visors. The impact of each visor on the helmet's refractive power in water was analyzed using thick lens calculations and Zemax optical design software. Using geometrical optics approximations, a model was developed to determine the optimal distance spherical power needed to be worn underwater based on the helmet's total induced spherical power underwater and the astronaut's manifest spectacle plane correction in air. The validity of the model was tested using data from both eyes of 10 astronauts who trained underwater. The helmet's visors induced a total power of -2.737 D when placed underwater. The required underwater spherical correction (FW) was linearly related to the spectacle plane spherical correction in air (FAir): FW = FAir + 2.356 D. The mean magnitude of the difference between the actual correction worn underwater and the calculated underwater correction was 0.20 ± 0.11 D. The actual and calculated values were highly correlated (r = 0.971) with 70% of eyes having a difference in magnitude of astronauts. The model accurately predicts the actual values worn underwater and can be applied (more generally) to determine a suitable spectacle lens correction to be worn behind other types of masks when submerged underwater.

Dynamics and Control of Underwater Gliders I: Steady Motions

OpenAIRE

Mahmoudian, N.; Geisbert, J.; Woolsey, C.

2007-01-01

This paper describes analysis of steady motions for underwater gliders, a type of highly efficient underwater vehicle which uses gravity for propulsion. Underwater gliders are winged underwater vehicles which locomote by modulating their buoyancy and their attitude. Several such vehicles have been developed and have proven their worth as efficient long-distance, long-duration ocean sampling platforms. To date, the primary emphasis in underwater glider development has been on locomotive effici...

Laser Induced Shock Waves and Vaporization in Biological System and Material Science

National Research Council Canada - National Science Library

Gerstman, Bernard S

2008-01-01

.... We have developed a computational model that allows the calculation of damage resulting from a laser pulse of any duration or energy due to temperature rise, explosive bubble formation, and shock wave production...

Underwater welding and repair technologies applied in PWR environment

International Nuclear Information System (INIS)

Scandella, Fabrice; Carpreau, Jean-Michel

2012-01-01

The authors describe several welding processes and technologies which have been used for underwater applications and which can be applied when repairing components of a PWR type reactor. They address, describe and discuss wet arc welding processes, the peculiarities of underwater welding, and the use of various processes such as 111, 114 and 135 processes, underwater welding with the hybrid plasma MIG-MAG process, underwater welding with the laser wire process, underwater welding with the FSW, FSP or UWFSW processes, underwater welding with variants of the friction welding process (friction surfacing, taper stitch welding, hydro-pillar processing

Cardiogenic shock following blunt chest trauma

Directory of Open Access Journals (Sweden)

Rodríguez-González Fayna

2010-01-01

Full Text Available Cardiac contusion, usually caused by blunt chest trauma, has been recognized with increased frequency over the past decades. Traffic accidents are the most frequent cause of cardiac contusions resulting from a direct blow to the chest. Other causes of blunt cardiac injury are numerous and include violent fall impacts, interpersonal aggression, explosions, and various types of high-risk sports. Myocardial contusion is difficult to diagnose; clinical presentation varies greatly, ranging from lack of symptoms to cardiogenic shock and arrhythmia. Although death is rare, cardiac contusion can be fatal. We present a case of cardiac contusion due to blunt chest trauma secondary to a fall impact, which manifested as cardiogenic shock.

Advanced Computational Modeling Approaches for Shock Response Prediction

Science.gov (United States)

Derkevorkian, Armen; Kolaini, Ali R.; Peterson, Lee

2015-01-01

Motivation: (1) The activation of pyroshock devices such as explosives, separation nuts, pin-pullers, etc. produces high frequency transient structural response, typically from few tens of Hz to several hundreds of kHz. (2) Lack of reliable analytical tools makes the prediction of appropriate design and qualification test levels a challenge. (3) In the past few decades, several attempts have been made to develop methodologies that predict the structural responses to shock environments. (4) Currently, there is no validated approach that is viable to predict shock environments overt the full frequency range (i.e., 100 Hz to 10 kHz). Scope: (1) Model, analyze, and interpret space structural systems with complex interfaces and discontinuities, subjected to shock loads. (2) Assess the viability of a suite of numerical tools to simulate transient, non-linear solid mechanics and structural dynamics problems, such as shock wave propagation.

Cavities produced by underground nuclear explosions

International Nuclear Information System (INIS)

Butkovich, T.R.

1976-01-01

This investigation studied the displacement of rock that formerly occupied cavities produced by underground nuclear explosions. There are three possible explanations for this displacement: the volume could be displaced to the free surface; it could occupy previously air-filled pores removed from the surrounding rock through compaction; or it could be accounted for by persisting compressive stresses induced by the outgoing shock wave. The analysis shows it unlikely that stored residual elastic stresses account for large fractions of cavity volumes. There is limited experimental evidence that free surface displacement accounts for a significant portion of this volume. Whenever the explosion mediums contain air-filled pores, the compaction of these pores most likely accounts for all the volume. Calculations show that 4 percent air-filled porosity can account for all the cavity volume within about 4 cavity radii and that even 1 percent can account for a significant fraction of the volume

Performance of electrical contact pins near a nuclear explosion

International Nuclear Information System (INIS)

Ragan, C.E.; Silbert, M.G.; Ellis, A.N.; Robinson, E.E.; Daddario, M.J.

1977-09-01

The pressures attainable in equation-of-state studies using nuclear-explosion-driven shock waves greatly exceed those that can be reached in normal laboratory conditions. However, the diagnostic instrumentation must survive in the high-radiation environment present near such an explosion. Therefore, a set of experiments were fielded on the Redmud event to test the feasibility of using electrical contact pins in this environment. In these experiments a 60-cm-high shield of boron-lead was placed on the rack lid approximately 1 m from the device. A sample consisting of slabs of molybdenum and 238 U was placed on top of the shield, and twelve electrical contact pins were embedded to five different depths in the materials. Five different multiplexing-charging circuits were used for the pins, and a piezoelectric quartz gauge was placed on top of the uranium to obtain an estimate of the fission-energy deposition. All of the charged pins survived the radiation and produced signals indicating shock arrival. The uncertainty in determining the pin-closure time was approximately 3 ns. The signal from the quartz gauge corresponded to a pressure that was consistent with the calculated neutron fluence

Human Injury Criteria for Underwater Blasts.

Directory of Open Access Journals (Sweden)

Rachel M Lance

Full Text Available Underwater blasts propagate further and injure more readily than equivalent air blasts. Development of effective personal protection and countermeasures, however, requires knowledge of the currently unknown human tolerance to underwater blast. Current guidelines for prevention of underwater blast injury are not based on any organized injury risk assessment, human data or experimental data. The goal of this study was to derive injury risk assessments for underwater blast using well-characterized human underwater blast exposures in the open literature. The human injury dataset was compiled using 34 case reports on underwater blast exposure to 475 personnel, dating as early as 1916. Using severity ratings, computational reconstructions of the blasts, and survival information from a final set of 262 human exposures, injury risk models were developed for both injury severity and risk of fatality as functions of blast impulse and blast peak overpressure. Based on these human data, we found that the 50% risk of fatality from underwater blast occurred at 302±16 kPa-ms impulse. Conservatively, there is a 20% risk of pulmonary injury at a kilometer from a 20 kg charge. From a clinical point of view, this new injury risk model emphasizes the large distances possible for potential pulmonary and gut injuries in water compared with air. This risk value is the first impulse-based fatality risk calculated from human data. The large-scale inconsistency between the blast exposures in the case reports and the guidelines available in the literature prior to this study further underscored the need for this new guideline derived from the unique dataset of actual injuries in this study.

Material Evidence for Ocean Impact from Shock-Metamorphic Experiments

Science.gov (United States)

Miura, Y.; Takayama, K.; Iancu, O. G.

1993-07-01

Continental impact reveals an excavated crater that has few fresh fine ejecta showing major high shock metamorphism due to weathering [1]. A giant ocean impact rarely remains as an excavated crater mainly due to crushing by dynamic plate-tectonic movements on the crust [2]. However, all impact materials, including fine-grained ejecta, can be obtained with artificial impact experiments [3]. The purpose of this study is to discuss material evidence for ocean impact based on shock-metamorphic experiments. Artificial impact experiments indicate that fine shocked quartz (SQ) aggregates can be formed on several target rocks (Table 1) [1]. It is found in Table 1 that (1) the largest-density deviation of SQ grain is found not at the wall-rock or the impact crater but at fine-grained ejecta, and (2) silica-poor rocks of basalt, gabbro, and anorthosite can also make fine SQ aggregates by impact. Table 1, which appears here in the hard copy, shows formations of fine shocked quartz aggregates from ocean-floor rocks of basalt, gabbroic anorthosite, and granite [3]. An asteroid (about 10 km across) hits the Earth ~65 m.y. ago [4] to result in global catastrophe by titanic explosion and climate change. But shocked quartz grains found in the K/T boundary layer were considered to come from crystalline continental rocks [5]. The present result as listed in Table 1 indicates that fine SQ aggregates can also be formed at sea-floor basaltic and gabbroic rocks [3]. The present result of formation of the SQ grains from sea- floor target rocks is nearly consistent with the finding of a sea-impact crater at the K/T boundary near the Caribbean [6]. Impact-induced volcanism at the K/T boundary can explained by the penetration from thin ocean crust to upper mantle reservoirs, if giant impact of a 10-km- diameter asteroid hit the ocean [2,7]. The present result can explain "phreatomagmatic (magmatic vapor) explosion," which is created by abrupt boiling between high-temperature magma and cold

An underwater shear compactor

International Nuclear Information System (INIS)

Biver, E.; Sims, J.

1997-01-01

This paper, originally presented at the WM'96 Conference in Tucson Arizona, describes a concept of a specialised decommissioning tool designed to operate underwater and to reduce the volume of radioactive components by shearing and compacting. The shear compactor was originally conceived to manage the size reduction of a variety of decommissioned stainless steel tubes stored within a reactor fuel cooling pond and which were consuming a substantial volume of the pond. The main objective of this tool was to cut the long tubes into shorter lengths and to compact them into a flat rectangular form which could be stacked on the pond floor, thus saving valuable space. The development programme, undertaken on this project, investigated a wide range of factors which could contribute to an extended cutting blade performance, ie: materials of construction, cutting blade shape and cutting loads required, shock effects, etc. The second phase was to review other aspects of the design, such as radiological protection, cutting blade replacement, maintenance, pond installation and resultant wall loads, water hydraulics, collection of products of shearing/compacting operations, corrosion of the equipment, control system, operational safety and the ability of the equipment to operate in dry environments. The paper summarises the extended work programme involved with this shear compactor tool. (author)

Underwater Gliders by Dr. Kevin Smith [video

OpenAIRE

Naval Postgraduate School Physics

2015-01-01

NPS Physics NPS Physics Research Projects Underwater glider research is currently underway in the physics department at the naval postgraduate in Monterey Ca. Dr. Kevin Smith is a specialist in underwater acoustics and sonar systems. He and his team are currently focused on autonomous underwater gliders and developing systems capable of detecting parameters in the ocean and listening for various sources of sound.

Three Dimensional Analysis of Induced Detonation of Cased Explosive

Science.gov (United States)

2014-10-16

hardness and ductility . RHA steel is largely used in military applications to manufacture armoured vehicles. The Johnson Cook (JC) constitutive...armour (RHA) steel were investigated through the LS-DYNA. The investigation focused on shock to detonation simulations of Composition B, with the... hot spots caused by the compression of the explosive from the initial shockwave. Detonation was also caused by pressure waves reflecting against the

Air blast effects on nuclear power plants from vapor cloud explosions

International Nuclear Information System (INIS)

Wiedermann, A.H.; Eichler, T.V.; Kot, C.A.

1981-01-01

To assess the hazards arising from the explosion of a large flammable vapor cloud a method was developed for estimating the air blast field assuming a detonation wave is established. The actual 'pancake' like geometry typical for negatively buoyant vapor clouds is taken into account. The cloud height and other characteristics are generated by a global cloud dynamics model for negatively buoyant clouds. This model provides the cloud height as a function of fuel vapor concentration and other pertinent variables. A two-dimensional Eulerian shock hydrodynamic computer code is utilized to compute the blast environment in the neighborhood of the end of the cloud. The initial field is taken to be a quasi-steady explosion field calculated by the method of characteristics for a thin Prandtl-Meyer expansion wave, and the upward driven air shock representing the combustion and pressure relief processes inherent in the pancake geometry. This initial fields is established in the 2-D hydrocode at a time corresponding to the arrival of the detonation front at the cloud edge. It is to be noted that the local blast environment scales with respect to the cloud height. The computational results indicate that it is essential to include the influence of cloud geometry for the realistic prediction of the air blast hazard arising from the explosion of a negatively buoyant vapor cloud. (orig./HP)

On beyond the standard model for high explosives: challenges & obstacles to surmount

Energy Technology Data Exchange (ETDEWEB)

Menikoff, Ralph Ds [Los Alamos National Laboratory

2009-01-01

Plastic-bonded explosives (PBX) are heterogeneous materials. Nevertheless, current explosive models treat them as homogeneous materials. To compensate, an empirically determined effective burn rate is used in place of a chemical reaction rate. A significant limitation of these models is that different burn parameters are needed for applications in different regimes; for example, shock initiation of a PBX at different initial temperatures or different initial densities. This is due to temperature fluctuations generated when a heterogeneous material is shock compressed. Localized regions of high temperatures are called hot spots. They dominate the reaction for shock initiation. The understanding of hot spot generation and their subsequent evolution has been limited by the inability to measure transients on small spatial ({approx} 1 {micro}m) and small temporal ({approx} 1 ns) scales in the harsh environment of a detonation. With the advances in computing power, it is natural to try and gain an understanding of hot-spot initiation with numerical experiments based on meso-scale simulations that resolve material heterogeneities and utilize realistic chemical reaction rates. However, to capture the underlying physics correctly, such high resolution simulations will require more than fast computers with a large amount of memory. Here we discuss some of the issues that need to be addressed. These include dissipative mechanisms that generate hot spots, accurate thermal propceties for the equations of state of the reactants and products, and controlling numerical entropy error from shock impedance mismatches at material interfaces. The later can generate artificial hot spots and lead to premature reaction. Eliminating numerical hot spots is critical for shock initiation simulations due to the positive feedback between the energy release from reaction and the hydrodynamic flow.

The Interplay of Opacities and Rotation in Promoting the Explosion of Core-Collapse Supernovae

Science.gov (United States)

Vartanyan, David; Burrows, Adam; Radice, David

2018-01-01

For over five decades, the mechanism of explosion in core-collapse supernovae has been a central unsolved problem in astrophysics, challenging both our computational capabilities and our understanding of relevant physics. Current simulations often produce explosions, but they are at times underenergetic. The neutrino mechanism, wherein a fraction of emitted neutrinos is absorbed in the mantle of the star to reignite the stalled shock, remains the dominant model for reviving explosions in massive stars undergoing core collapse. We present here a diverse suite of 2D axisymmetric simulations produced by FORNAX, a highly parallelizable multidimensional supernova simulation code. We explore the effects of various corrections, including the many-body correction, to neutrino-matter opacities and the possible role of rotation in promoting explosion amongst various core-collapse progenitors.

Containment analysis for the simultaneous detonation of two nuclear explosives

International Nuclear Information System (INIS)

Terhune, R.W.; Glenn, H.D.; Burton, D.E.; Rambo, J.T.

1977-01-01

The explosive phenomenology associated with the simultaneous detonation of two 2.2-kt nuclear explosives is examined. A comprehensive spatial-time pictorial of the resultant shock-wave phenomenology is given. The explosives were buried at depths of 200 m and 280 m, corresponding to a separation of approximately 4 final cavity radii. Constitutive relations for the surrounding medium were derived from the geophysical logs and core samples taken from an actual emplacement configuration at the Nevada Test Site. Past calculational studies indicate that successful containment may depend upon the development of a strong tangential-stress field (or ''containment cage'') surrounding the cavity at late times. A series of conditions that must be met to insure formation of this cage are presented. Calculational results, based on one- and two-dimensional finite-difference codes of continuum mechanics, describe how each condition has been fulfilled and illustrate the dynamic sequence of events important to the formation of the containment cage. They also indicate, at least for the geological site chosen, that two nuclear explosives do not combine to threaten containment

Towards gravitational-wave astronomy of core-collapse supernova explosion

International Nuclear Information System (INIS)

Kotake, Kei

2010-01-01

We study properties of gravitational waves based on the three-dimensional (3D) simulations, which demonstrate the neutrino-driven explosions aided by the standing accretion shock instability (SASI). Pushed by evidence supporting slow rotation prior to core-collapse, we focus on the asphericities in neutrino emissions and matter motions outside the protoneutron star. By performing a ray-tracing calculation in 3D, we estimate accurately the gravitational waveforms from anisotropic neutrino emissions. In contrast to the previous work assuming axisymmetry, we find that the gravitational waveforms vary much more stochastically because the explosion anisotropies depend sensitively on the growth of the SASI which develops chaotically in all directions. Our results show that the gravitational-wave spectrum has its peak near ∼ 100 Hz, reflecting the SASI-induced matter overturns of ∼ O(10) ms. We point out that the detection of such signals, possibly visible to the LIGO-class detectors for a Galactic supernova, could be an important probe into the long-veiled explosion mechanism.

Underwater Ranging

OpenAIRE

S. P. Gaba

1984-01-01

The paper deals with underwater laser ranging system, its principle of operation and maximum depth capability. The sources of external noise and methods to improve signal-to-noise ratio are also discussed.

UNDERWATER COATINGS FOR CONTAMINATION CONTROL

International Nuclear Information System (INIS)

Julia L. Tripp; Kip Archibald; Ann Marie Phillips; Joseph Campbell

2004-01-01

The Idaho National Laboratory (INL) deactivated several aging nuclear fuel storage basins. Planners for this effort were greatly concerned that radioactive contamination present on the basin walls could become airborne as the sides of the basins became exposed during deactivation and allowed to dry after water removal. One way to control this airborne contamination was to fix the contamination in place while the pool walls were still submerged. There are many underwater coatings available on the market for marine, naval and other applications. A series of tests were run to determine whether the candidate underwater fixatives were easily applied and adhered well to the substrates (pool wall materials) found in INL fuel pools. Lab-scale experiments were conducted by applying fourteen different commercial underwater coatings to four substrate materials representative of the storage basin construction materials, and evaluating their performance. The coupons included bare concrete, epoxy painted concrete, epoxy painted carbon steel, and stainless steel. The evaluation criteria included ease of application, adherence to the four surfaces of interest, no change on water clarity or chemistry, non-hazardous in final applied form and be proven in underwater applications. A proprietary two-part, underwater epoxy owned by S. G. Pinney and Associates was selected from the underwater coatings tested for application to all four pools. Divers scrubbed loose contamination off the basin walls and floors using a ship hull scrubber and vacuumed up the sludge. The divers then applied the coating using a special powered roller with two separate heated hoses that allowed the epoxy to mix at the roller surface was used to eliminate pot time concerns. The walls were successfully coated and water was removed from the pools with no detectable airborne contamination releases

Shock-induced synthesis of high temperature superconducting materials

Science.gov (United States)

Ginley, D.S.; Graham, R.A.; Morosin, B.; Venturini, E.L.

1987-06-18

It has now been determined that the unique features of the high pressure shock method, especially the shock-induced chemical synthesis technique, are fully applicable to high temperature superconducting materials. Extraordinarily high yields are achievable in accordance with this invention, e.g., generally in the range from about 20% to about 99%, often in the range from about 50% to about 90%, lower and higher yields, of course, also being possible. The method of this invention involves the application of a controlled high pressure shock compression pulse which can be produced in any conventional manner, e.g., by detonation of a high explosive material, the impact of a high speed projectile or the effect of intense pulsed radiation sources such as lasers or electron beams. Examples and a discussion are presented.

Conductivity Histories Measured in Shock-Dispersed-Fuel Explosion Clouds

Energy Technology Data Exchange (ETDEWEB)

Kuhl, A L

2010-04-01

The notion of high ion and electron concentrations in the detonation of aluminized explosive mixtures has aroused some interest in electro-magnetic effects that the SDF charges might generate when detonated. Beside the scientific aspects at least two questions appear to be of practical interest: (1) Does the detonation of an SDF charge create electro-magnetic disturbances strong enough to affect the operation of electrical infrastructure in for example a tunnel system? (2) Does the detonation of an SDF charge in a tunnel system create an electromagnetic signature that relays information of the charge performance to the outside environment?

Shock Revival in Core-collapse Supernovae: A Phase-diagram Analysis

Science.gov (United States)

Gabay, Daniel; Balberg, Shmuel; Keshet, Uri

2015-12-01

We examine the conditions for the revival of the stalled accretion shock in core-collapse supernovae, in the context of the neutrino heating mechanism. We combine one-dimensional simulations of the shock revival process with a derivation of a quasi-stationary approximation, which is both accurate and efficient in predicting the flow. In particular, this approach is used to explore how the evolution of the accretion shock depends on the shock radius, RS, and velocity, VS (in addition to other global properties of the system). We do so through a phase-space analysis of the shock acceleration, aS, in the {R}S{--}{V}S plane, shown to provide quantitative insights into the initiation and nature of runaway expansion. In the particular case of an initially stationary ({V}S=0, {a}S=0) profile, the prospects for an explosion can be assessed by the initial signs of the partial derivatives of the shock acceleration, in analogy to a linear damped/anti-damped oscillator. If \\partial {a}S/\\partial {R}S\\lt 0 and \\partial {a}S/\\partial {V}S\\gt 0, runaway will likely occur after several oscillations, while if \\partial {a}S/\\partial {R}S\\gt 0, runaway expansion will commence in a non-oscillatory fashion. These two modes of runaway correspond to low and high mass accretion rates, respectively. We also use the quasi-stationary approximation to assess the advection-to-heating timescale ratio in the gain region, often used as an explosion proxy. Indeed, this ratio does tend to ∼1 in conjunction with runaway conditions, but neither this unit value nor the specific choice of the gain region as a point of reference appear to be unique in this regard.

Steam explosions of single drops of pure and alloyed molten aluminum

International Nuclear Information System (INIS)

Nelson, L.S.

1995-01-01

Studies of steam explosion phenomena have been performed related to the hypothetical meltdown of the core and other components of aluminum alloy-fueled production reactors. Our objectives were to characterise the triggers, if any, required to initiate these explosions and to determine the energetics and chemical processes associated with these events. Three basic studies have been carried out with 1-10 g single drops of molten aluminum or aluminum-based alloys: untriggered experiments in which drops of melt were released into water; triggered experiments in which thermal-type steam explosions occurred; and one triggered experiment in which an ignition-type steam explosion occurred. In untriggered experiments, spontaneous steam explosions never occurred during the free fall through water of single drops of pure Al or of the alloys studied here. Moreover, spontaneous explosions never occurred upon or during contact of the globules with several underwater surfaces. When Li was present in the alloy, H 2 was generated as a stream of bubbles as the globules fell through the water, and also as they froze on the bottom surface of the chamber. The triggered experiments were performed with pure Al and the 6061 alloy. Bare bridgewire discharges and those focused with cylindrical reflectors produced a small first bubble that collapsed and was followed by a larger second bubble. When the bridgewire was discharged at one focus of an ellipsoidal reflector, a melt drop at the other focus triggered only very mildly in spite of a 30-fold increase in peak pressure above that of the bridgewire discharge without the reflector. Experiments were also performed with globules of high purity Al in which the melt release temperature was progressively increased. Moderate thermal-type explosions were produced over the temperature range 1273-1673 K. At about 1773 K, however, one experiment produced a brilliant flash of light and bubble growth about an order of magnitude faster than normal; it

Underwater Gliders: A Review

OpenAIRE

Javaid Muhammad Yasar; Ovinis Mark; Nagarajan T; Hashim Fakhruldin B M

2014-01-01

Underwater gliders are a type of underwater vehicle that transverse the oceans by shifting its buoyancy, during which its wings develop a component of the downward motion in the horizontal plane, thus producing a forward force. They are primarily used in oceanography sensing and data collection and play an important role in ocean research and development. Although there have been considerable developments in these gliders since the development of the first glider concept in 1989, to date, no ...

Analysis of ex-vessel steam explosion with MC3D

International Nuclear Information System (INIS)

Leskovar, M.; Mavko, B.

2007-01-01

An ex-vessel steam explosion may occur when, during a severe reactor accident, the reactor vessel fails and the molten core pours into the water in the reactor cavity. A steam explosion is a fuel coolant interaction process where the heat transfer from the melt to water is so intense and rapid that the timescale for heat transfer is shorter than the timescale for pressure relief. This can lead to the formation of shock waves and production of missiles that may endanger surrounding structures. A strong enough steam explosion in a nuclear power plant could jeopardize the containment integrity and so lead to a direct release of radioactive material to the environment. In the paper, different scenarios of ex-vessel steam explosions in a typical pressurized water reactor cavity are analyzed with the code MC3D, which was developed for the simulation of fuel-coolant interactions. A comprehensive parametric study was performed varying the location of the melt release (central, left and right side melt pour), the cavity water subcooling, the primary system overpressure at vessel failure and the triggering time for explosion calculations. The main purpose of the study was to determine the most challenging ex-vessel steam explosion cases in a typical pressurized water reactor and to estimate the expected pressure loadings on the cavity walls. The performed analysis shows that for some ex-vessel steam explosion scenarios significantly higher pressure loads are predicted than obtained in the OECD programme SERENA Phase 1. (author)

The use of underwater high-voltage discharges to improve the efficiency of Jatropha curcas L. biodiesel production.

Science.gov (United States)

Maroušek, Josef; Itoh, Shigeru; Higa, Osamu; Kondo, Yoshikazu; Ueno, Masami; Suwa, Ryuichi; Komiya, Yasuaki; Tominaga, Jun; Kawamitsu, Yoshinobu

2012-01-01

Underwater high-voltage discharges (3.5 kV) resulting in 4.9 kJ shock waves (50-60 MPa) were studied at the laboratory scale as a Jatropha curcas L. seed disintegration method. Grinding and macerating in an excess of methanol (3.5:1) was advantageous because methanol acts both as a liquid carrier for the pressure shock waves and as a solvent that increases the efficiency of oil extraction while remaining usable for esterification. The influence of the number of shock waves and the intensity of methanol maceration on the heat values of the pressed cake are stated in detail. Soxhlet extraction demonstrated that a greater than 94% oil extraction was achieved. The increased disintegration of vacuoles rich in oil was documented by surface area analysis, mineralization kinetics analysis, and electron microscopy. The working volumes were small, and the proportion of energy inadequate compared to the yields released; however, much can be improved by upgrading the process. © 2012 International Union of Biochemistry and Molecular Biology, Inc.

Temperature-dependent shock initiation of LX-17 explosive

Energy Technology Data Exchange (ETDEWEB)

Lee, R.S.; Chau, H.H.; Druce, R.L.; Moua, K.

1995-02-01

LX-17 samples, heated to temperatures up to 250 C, were impacted by 3 to 10-mm-wide, 50.8-mm-long strips of 0.13-mm-thick Kapton polyimide film at velocities up to 7.7 km/s. The Kapton strips were laminated onto a thin aluminum bridge foil and were launched to the desired velocity by discharging a capacitor bank through the foil, causing the foil to explode. The LX-17 samples were confined in a steel holder and heated in an oven to the desired temperature. After the capacitor bank was charged, the LX-17 sample in its steel holder was remotely drawn out of the oven on rails and positioned over the bridge-foil/Kapton-strip laminate. When the sample was in position, the bank was discharged, launching the Kapton strip against the LX-17 surface. The shock initiation threshold was measured for 3, 7, and 10-mm-wide strips at room temperature, 200 C and 250 C. The authors found a significant reduction in the velocity threshold and in the critical area for initiation when the samples were heated. The authors compare the results with the earlier data of Bloom, who measured the initiation threshold of LX-17 over the density range 1.8--1.91 g/cm{sup 3} at room temperature and {minus}54 C. LX-17 has a large coefficient of thermal expansion, as reported by Urtiew, et al., which reduces its density significantly t elevated temperatures. They find that the change of shock initiation threshold with temperature is consistent with the change in sample density, using the relation between threshold and density reported by Bloom.

Underwater Calibration of Dome Port Pressure Housings

Science.gov (United States)

Nocerino, E.; Menna, F.; Fassi, F.; Remondino, F.

2016-03-01

Underwater photogrammetry using consumer grade photographic equipment can be feasible for different applications, e.g. archaeology, biology, industrial inspections, etc. The use of a camera underwater can be very different from its terrestrial use due to the optical phenomena involved. The presence of the water and camera pressure housing in front of the camera act as additional optical elements. Spherical dome ports are difficult to manufacture and consequently expensive but at the same time they are the most useful for underwater photogrammetry as they keep the main geometric characteristics of the lens unchanged. Nevertheless, the manufacturing and alignment of dome port pressure housing components can be the source of unexpected changes of radial and decentring distortion, source of systematic errors that can influence the final 3D measurements. The paper provides a brief introduction of underwater optical phenomena involved in underwater photography, then presents the main differences between flat and dome ports to finally discuss the effect of manufacturing on 3D measurements in two case studies.

Laser shocks: A tool for experimental simulation of damage into materials

Energy Technology Data Exchange (ETDEWEB)

Boustie, M.; Cuq Lelandais, J. P.; Berthe, L.; Ecault, R. [Institut PPRIME, Departement Physique et Mecanique des Materiaux, CNRS-ENSMA-Universite de Poitiers, 1 av Clement Ader, 86961 FUTUROSCOPE Cedex (France); CEA-DAM Valduc, 21120 Is-sur-Tille (France); Laboratoire Procedes et Ingenierie en Mecanique et Materiaux (CNRS), Arts et Metiers ParisTech, 151 bd de l' Hopital, 75013 PARIS (France); Institut PPRIME, Departement Physique et Mecanique des Materiaux, CNRS-ENSMA-Universite de Poitiers, 1 av Clement Ader, 86961 FUTUROSCOPE Cedex (France)

2012-07-30

High power laser irradiation of solids results in a strong shock wave propagation, driving very high amplitude pressure loadings with very short durations. These particular characteristics offer the possibility to study the behaviour of matter under extreme dynamic conditions in continuity with what is possible with the conventional generators of shock (launchers of projectiles, explosives). An advantage of laser shocks is a possible recovery of the shocked samples presenting the metallurgical effects of the shock in most cases. We introduce the principle of the laser shock generation, the characterization of these shocks, the principal mechanisms and effects associated with their propagation in the solids. We show how laser shocks can be a laboratory tool for simulating shock effects at ultra high strain rate, providing a high in information experimental layout for validation of damage modelling on an extended strain rate range compared to conventional shock generators. New data have been obtained with ultra short femtosecond range irradiation. Experimental data gathered through post mortem observation, time resolved velocity measurement are shown along with numerical associated simulations, showing the possibility to predict the damage behaviour of metallic targets under extreme strain rate up to 10{sup 8} s{sup -1}.

Study of the conditions of fracture at explosive compaction of powders

Directory of Open Access Journals (Sweden)

Andrey E. Buzyurkin

2013-04-01

Full Text Available Joint theoretical and experimental investigations have allowed to realize an approach with use of mathematical and physical modeling of processes of a shock wave loading of powder materials.In order to gain a better insight into the effect of loading conditions and, in particular, to study the effect of detonation velocity, explosive thickness, and explosion pressure on the properties of the final sample, we numerically solved the problem about powder compaction in the axisymmetric case.The performed analysis shows that an increase in the decay time of the pressure applied to the sample due to an increase of the explosive thickness or the external loading causes no shrinkage of the destructed region at a fixed propagation velocity of the detonation wave. Simultaneously, a decrease in the propagation velocity of the detonation wave results in an appreciable shrinkage of this region.

Characterization of shocked beryllium

Directory of Open Access Journals (Sweden)

Papin P.A.

2012-08-01

Full Text Available While numerous studies have investigated the low-strain-rate constitutive response of beryllium, the combined influence of high strain rate and temperature on the mechanical behavior and microstructure of beryllium has received limited attention over the last 40 years. In the current work, high strain rate tests were conducted using both explosive drive and a gas gun to accelerate the material. Prior studies have focused on tensile loading behavior, or limited conditions of dynamic strain rate and/or temperature. Two constitutive strength (plasticity models, the Preston-Tonks-Wallace (PTW and Mechanical Threshold Stress (MTS models, were calibrated using common quasi-static and Hopkinson bar data. However, simulations with the two models give noticeably different results when compared with the measured experimental wave profiles. The experimental results indicate that, even if fractured by the initial shock loading, the Be remains sufficiently intact to support a shear stress following partial release and subsequent shock re-loading. Additional “arrested” drive shots were designed and tested to minimize the reflected tensile pulse in the sample. These tests were done to both validate the model and to put large shock induced compressive loads into the beryllium sample.

Features of the incorporation of single and double based powders within emulsion explosives

Science.gov (United States)

Ribeiro, J. B.; Mendes, R.; Tavares, B.; Louro, C.

2014-05-01

In this work, features of the thermal and detonation behaviour of compositions resulting from the mixture of single and double based powders within ammonium nitrate based emulsion explosives are shown. Those features are portrayed through results of thermodynamic-equilibrium calculations of the detonation velocity, the chemical compatibility assessment through differential thermal analysis [DTA] and thermo gravimetric analysis [TGA], the experimental determination of the detonation velocity and a comparative evaluation of the shock sensitivity using a modified version of the "gap-test". DTA/TGA results for the compositions and for the individual components overlap until the beginning of the thermal decomposition which is an indication of the absence of formation of any new chemical species and so of the compatibility of the components of the compositions. After the beginning of the thermal decomposition it can be seen that the rate of mass loss is much higher for the compositions with powder than for the one with sole emulsion explosive. Both, theoretical and experimental, values of the detonation velocity have been shown to be higher for the powdered compositions than for the sole emulsion explosive. Shock sensitivity assessments have ended-up with a slightly bigger sensitivity for the compositions with double based powder when compared to the single based compositions or to the sole emulsion.

Features of the incorporation of single and double based powders within emulsion explosives

International Nuclear Information System (INIS)

Ribeiro, J B; Mendes, R; Tavares, B; Louro, C

2014-01-01

In this work, features of the thermal and detonation behaviour of compositions resulting from the mixture of single and double based powders within ammonium nitrate based emulsion explosives are shown. Those features are portrayed through results of thermodynamic-equilibrium calculations of the detonation velocity, the chemical compatibility assessment through differential thermal analysis [DTA] and thermo gravimetric analysis [TGA], the experimental determination of the detonation velocity and a comparative evaluation of the shock sensitivity using a modified version of the g ap-test . DTA/TGA results for the compositions and for the individual components overlap until the beginning of the thermal decomposition which is an indication of the absence of formation of any new chemical species and so of the compatibility of the components of the compositions. After the beginning of the thermal decomposition it can be seen that the rate of mass loss is much higher for the compositions with powder than for the one with sole emulsion explosive. Both, theoretical and experimental, values of the detonation velocity have been shown to be higher for the powdered compositions than for the sole emulsion explosive. Shock sensitivity assessments have ended-up with a slightly bigger sensitivity for the compositions with double based powder when compared to the single based compositions or to the sole emulsion.

First all-union symposium on shock pressures, October 24-26, 1973, Moscow. Volume 2

International Nuclear Information System (INIS)

Batsanov, S.S.

Twenty-two papers on the chemistry of impulsive pressures are contained in this volume. The papers deal primarily with shock wave propagation in various materials (particularly oxides) and explosive forming and sintering

Analysis of recordings from underwater controlled sources in the Pacific Ocean received by the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO)

Science.gov (United States)

Yamada, Tomoaki; Zampolli, Mario; Haralabus, Georgios; Heaney, Kevin; Prior, Mark; Isse, Takeshi

2016-04-01

Controlled impulsive scientific underwater sound sources in the Northwestern Pacific were observed at two IMS hydroacoustic stations in the Pacific Ocean. Although these experiments were conducted with the aim of studying the physical properties of the plate boundaries inside the Earth, they are also suitable for the investigation of long range underwater acoustic detections. In spite of the fact that the energy of these controlled impulsive scientific sources is significantly smaller than that of nuclear explosions, the signals were obtained by IMS hydrophone stations thousands of kilometres away and also by distant ocean bottom instruments operated by various Institutes, such as the Earthquake Research Institute, University of Tokyo. These experiments provide calibrated (yield, time, location) long-range acoustic transmissions, which enable one to examine the physics of long-range acoustic propagation and to verify the capabilities of the CTBTO IMS network to detect even small explosions.The two IMS stations used are H03 (Juan Fernandez Island, Chile) off the coast of Chile in the Southeastern Pacific and H11 (Wake Island, USA) in the Western Pacific. Both stations consist of two triplets of hydrophones in the SOFAR channel, which monitor the oceans for signs of nuclear explosions. H03 detected low-yield explosions above flat terrain at distances of 15,000 km across the Pacific as well as explosions above the landward slope off the coast of Japan at distances above 16,000 km across the Pacific. These records showed that source signatures, such as short duration and bubble pulses, were preserved over the long propagation distances. It was found that the observed maximum amplitudes from each source exhibit order of magnitude variations even when the yield and detonation depth are the same. The experimental data and transmission loss simulations suggest that bathymetric features around the sources and between the sources and the receivers are the main causes for

Measurement of the pressure pulse from a detonating explosive

International Nuclear Information System (INIS)

Bourne, N K; Milne, A M; Biers, R A

2005-01-01

A series of experiments has been carried out to determine the pressure pulse exiting from a polymethylmethacrylate (PMMA) plate, of varying thickness, subject to the shock pulse exerted by a detonating charge of fixed mass. This calibration will define a new donor explosive and inert gap material for use in one of the qualification tests for energetic materials, the large scale gap test. The peak pressure was recorded on the central axis of the attenuator using calibrated piezoresistive manganin gauges as a function of the quantity of PMMA applied to the output of the donor charge. The stress history within the PMMA was measured as a function of run distance and the peak pressure plotted against thickness as a calibration. The shock front was known to have curvature and a measurement of this was attempted. The behaviour of the transmitted shock at small gap thicknesses was shown to be anomalous since the front was partially in a reactive and partially within an inert medium

SUB-PHOTOSPHERIC EMISSION FROM RELATIVISTIC RADIATION MEDIATED SHOCKS IN GRBs

International Nuclear Information System (INIS)

Bromberg, Omer; Mikolitzky, Ziv; Levinson, Amir

2011-01-01

It is proposed that the prompt emission observed in bursts that exhibit a thermal component originates from relativistic radiation mediated shocks (RRMS) that form below the photosphere of the gamma-ray burst (GRB) outflow. It is argued that such shocks are expected to form in luminous bursts via collisions of shells that propagate with moderate Lorentz factors Γ ∼< 500. Faster shells will collide above the photosphere to form collisionless shocks. We demonstrate that in events like GRB 090902B a substantial fraction of the explosion energy is dissipated below the photosphere, in a region of moderate optical depth τ ∼< 300, whereas in GRB 080916C the major fraction of the energy dissipates above the photosphere. We show that under conditions anticipated in many GRBs, such RRMS convect enough radiation upstream to render photon production in the shock transition negligible, unlike the case of shock breakout in supernovae. The resulting spectrum, as measured in the shock frame, has a relatively low thermal peak, followed by a broad, nonthermal component extending up to the Klein-Nishina limit.

Underwater 3D filming

OpenAIRE

Rinaldi, Roberto

2014-01-01

After an experimental phase of many years, 3D filming is now effective and successful. Improvements are still possible, but the film industry achieved memorable success on 3D movie’s box offices due to the overall quality of its products. Special environments such as space (“Gravity” ) and the underwater realm look perfect to be reproduced in 3D. “Filming in space” was possible in “Gravity” using special effects and computer graphic. The underwater realm is still difficult to be handled. Unde...

Explosive Performance Modification by Cosolidification of Ammonium Nitrate with Fuels

Science.gov (United States)

1976-10-01

explosives, by calibrated codes and formulas (Rif 1-4). It has been recognized that departure from the instantan- eity approximation may be significant...velocity nor density changed much. No other explanation of the synergism se.-. as tenable as intermolecular reaction behind the shock front yielding...delivery problems with UDMH ). Among potentially interesting materials which were deferred or to receive less attention were nitro- guanidine nitrate

IVO develops a new repair technique for underwater sites. Viscous doughlike substance underwater cracks

Energy Technology Data Exchange (ETDEWEB)

Klingstedt, G.; Leisio, C. [ed.

1998-07-01

A viscous sealant is revolutionizing repair of the stone and concrete masonry of underwater dams, bridges and canals. There is now no need for expensive and time-consuming cofferdams, since a diver can extrude quick-setting mortar into underwater structures needing repair. This technique has worked well in recent years in various parts of Finland even in strongly flowing water. IVO experts are now starting to look more beyond the borders of Finland

A man-made object detection for underwater TV

Science.gov (United States)

Cheng, Binbin; Wang, Wenwu; Chen, Yao

2018-03-01

It is a great challenging task to complete an automatic search of objects underwater. Usually the forward looking sonar is used to find the target, and then the initial identification of the target is completed by the side-scan sonar, and finally the confirmation of the target is accomplished by underwater TV. This paper presents an efficient method for automatic extraction of man-made sensitive targets in underwater TV. Firstly, the image of underwater TV is simplified with taking full advantage of the prior knowledge of the target and the background; then template matching technology is used for target detection; finally the target is confirmed by extracting parallel lines on the target contour. The algorithm is formulated for real-time execution on limited-memory commercial-of-the-shelf platforms and is capable of detection objects in underwater TV.

Embedded Fiber Optic Sensors for Measuring Transient Detonation/Shock Behavior;Time-of-Arrival Detection and Waveform Determination.

Energy Technology Data Exchange (ETDEWEB)

Chavez, Marcus Alexander; Willis, Michael David; Covert, Timothy Todd

2014-09-01

The miniaturization of explosive components has driven the need for a corresponding miniaturization of the current diagnostic techniques available to measure the explosive phenomena. Laser interferometry and the use of spectrally coated optical windows have proven to be an essential interrogation technique to acquire particle velocity time history data in one- dimensional gas gun and relatively large-scale explosive experiments. A new diagnostic technique described herein allows for experimental measurement of apparent particle velocity time histories in microscale explosive configurations and can be applied to shocks/non-shocks in inert materials. The diagnostic, Embedded Fiber Optic Sensors (EFOS), has been tested in challenging microscopic experimental configurations that give confidence in the technique's ability to measure the apparent particle velocity time histories of an explosive with pressure outputs in the tenths of kilobars to several kilobars. Embedded Fiber Optic Sensors also allow for several measurements to be acquired in a single experiment because they are microscopic, thus reducing the number of experiments necessary. The future of EFOS technology will focus on further miniaturization, material selection appropriate for the operating pressure regime, and extensive hydrocode and optical analysis to transform apparent particle velocity time histories into true particle velocity time histories as well as the more meaningful pressure time histories.

Design of Autonomous Underwater Vehicle

Directory of Open Access Journals (Sweden)

Tadahiro Hyakudome

2011-03-01

Full Text Available There are concerns about the impact that global warming will have on our environment, and which will inevitably result in expanding deserts and rising water levels. While a lot of underwater vehicles are utilized, AUVs (Autonomous Underwater Vehicle were considered and chosen, as the most suitable tool for conduction survey concerning these global environmental problems. AUVs can comprehensive survey because the vehicle does not have to be connected to the support vessel by tether cable. When such underwater vehicles are made, it is necessary to consider about the following things. 1 Seawater and Water Pressure Environment, 2 Sink, 3 There are no Gas or Battery Charge Stations, 4 Global Positioning System cannot use, 5 Radio waves cannot use. In the paper, outline of above and how deal about it are explained.

SN 1987 A: A Unique Laboratory for Shock Physics

Science.gov (United States)

Sonneborn, George

2012-01-01

Supernova 1987 A has given us an unprecedented view of the evolution of the explosion debris and its interaction with circumstellar matter. The outer supernova debris, now expanding with velocities approx.8000 km/s, encountered the relatively dense circumstellar ring formed by presupernova mass loss in the early 1990s. The shock interaction is manifested by UV-optical "hotspots", an expanding X-ray ring, an expanding ring of knotty non-thermal radio emission, and a ring of thermal IR emission from silicate dust Recent ultraviolet observations of the emissions from the reverse shock and the ring with the HST/COS reveal new details about the shock interaction. Lyman alpha emission from the reverse shock is much stronger than H alpha and they have different emission morphologies, pointing to different emission mechanisms. The reverse shock was detected for the first time in C IV 1550. The N V to C IV brightness ratio indicates the N/C abundance ratio in the expanding debris is about 100X solar, about 3X N/C in the inner ring.

Experimental simulation of lightning, interacting explosions and astrophysical jets with pulsed lasers

International Nuclear Information System (INIS)

Villagran-Muniz, M; Sobral, H; Navarro-Gonzalez, R; Velazquez, P F; Raga, A C

2003-01-01

Tabletop laboratory experiments have been used to simulate natural lightning, interacting explosions and astrophysical jets. When a high-energy laser pulse is focused in air, a laser-induced plasma (LIP) is produced, that generates a shock wave and an adiabatic expansion of the gas. In our work we have used LIPs in order to simulate lightning, for the study of chemical reactions relevant to atmospheric science. Several diagnostics have been applied to our LIPs, such as deflectometry, shadowgraphy and interferometry, which yield full spatial information of the process (electron density and temperature, the position of the shock wave fronts and the expansion of the hot gas), with a time resolution that ranges from nanoseconds to milliseconds. A new diagnostic alternative was implemented for shadowgraphy, which uses either continuous lasers or conventional light sources. The experimental results have been reproduced by hydrodynamic codes that we have developed. With astrophysical applications in mind, we have simulated and diagnosed the interaction of two explosions, with the aforementioned techniques. For this purpose, two LIPs are synchronized and diagnosed spatially and temporarily. Also, by producing the LIP in a glass sphere with a nozzle that ejects a shock wave and hot gas, we are able to simulate astrophysical jets. With such experiments, astrophysical models developed by us have been validated, showing excellent agreement between experiments and numerical simulations

Elaboration of the Charge Constructions of Explosives for the Structure of Facing Stone

Science.gov (United States)

Khomeriki, Sergo; Mataradze, Edgar; Chikhradze, Nikoloz; Losaberidze, Marine; Khomeriki, Davit; Shatberashvili, Grigol

2017-12-01

Increased demand for high-strength facing material caused the enhancement of the volume of explosives use in modern technologies of blocks production. The volume of broken rocks and crushing quality depends on the rock characteristics and on the properties of the explosive, in particular on its brisance and serviceability. Therefore, the correct selection of the explosive for the specific massif is of a considerable practical importance. For efficient mining of facing materials by explosion method the solving of such problems as determination of the method of blasthole drilling as well as of the regime and charge values, selection of the explosive, blastholes distribution in the face and their order is necessary. This paper focuses on technical solutions for conservation of rock natural structure in the blocks of facing material, mined by the use of the explosives. It has been established that the efficient solving of mentioned problem is attained by reducing of shock pulse duration. In such conditions the rigidity of crystalline lattice increases in high pressure area. As a result, the hazard if crack formation in structural unites and the increases of natural cracks are excluded. Short-time action of explosion pulse is possible only by linear charges of the explosives, characterized by high detonation velocity which detonate by the velocity of 7-7.5 km/sec and are characterized by very small critical diameter.

Remote Underwater Characterization System - Innovative Technology Summary Report

International Nuclear Information System (INIS)

Willis, Walter David

1999-01-01

Characterization and inspection of water-cooled and moderated nuclear reactors and fuel storage pools requires equipment capable of operating underwater. Similarly, the deactivation and decommissioning of older nuclear facilities often requires the facility owner to accurately characterize underwater structures and equipment which may have been sitting idle for years. The underwater characterization equipment is often required to operate at depths exceeding 20 ft (6.1 m) and in relatively confined or congested spaces. The typical baseline approach has been the use of radiation detectors and underwater cameras mounted on long poles, or stationary cameras with pan and tilt features mounted on the sides of the underwater facility. There is a perceived need for an inexpensive, more mobile method of performing close-up inspection and radiation measurements in confined spaces underwater. The Remote Underwater Characterization System (RUCS) is a small, remotely operated submersible vehicle intended to serve multiple purposes in underwater nuclear operations. It is based on the commercially-available ''Scallop'' vehicle, but has been modified by Department of Energy's Robotics Technology Development Program to add auto-depth control, and vehicle orientation and depth monitoring at the operator control panel. The RUCS is designed to provide visual and gamma radiation characterization, even in confined or limited access areas. It was demonstrated in August 1998 at Idaho National Engineering and environmental Laboratory (INEEL) as part of the INEEL Large Scale Demonstration and Deployment Project. During the demonstration it was compared in a ''head-to-head'' fashion with the baseline characterization technology. This paper summarizes the results of the demonstration and lessons learned; comparing and contrasting both technologies in the areas of cost, visual characterization, radiological characterization, and overall operations

Shock interactions with heterogeneous energetic materials

Science.gov (United States)

Yarrington, Cole D.; Wixom, Ryan R.; Damm, David L.

2018-03-01

The complex physical phenomenon of shock wave interaction with material heterogeneities has significant importance and nevertheless remains little understood. In many materials, the observed macroscale response to shock loading is governed by characteristics of the microstructure. Yet, the majority of computational studies aimed at predicting phenomena affected by these processes, such as the initiation and propagation of detonation waves in explosives or shock propagation in geological materials, employ continuum material and reactive burn model treatment. In an effort to highlight the grain-scale processes that underlie the observable effects in an energetic system, a grain-scale model for hexanitrostilbene (HNS) has been developed. The measured microstructures were used to produce synthetic computational representations of the pore structure, and a density functional theory molecular dynamics derived equation of state (EOS) was used for the fully dense HNS matrix. The explicit inclusion of the microstructure along with a fully dense EOS resulted in close agreement with historical shock compression experiments. More recent experiments on the dynamic reaction threshold were also reproduced by inclusion of a global kinetics model. The complete model was shown to reproduce accurately the expected response of this heterogeneous material to shock loading. Mesoscale simulations were shown to provide a clear insight into the nature of threshold behavior and are a way to understand complex physical phenomena.

An Underwater Image Enhancement Algorithm for Environment Recognition and Robot Navigation

Directory of Open Access Journals (Sweden)

Kun Xie

2018-03-01

Full Text Available There are many tasks that require clear and easily recognizable images in the field of underwater robotics and marine science, such as underwater target detection and identification of robot navigation and obstacle avoidance. However, water turbidity makes the underwater image quality too low to recognize. This paper proposes the use of the dark channel prior model for underwater environment recognition, in which underwater reflection models are used to obtain enhanced images. The proposed approach achieves very good performance and multi-scene robustness by combining the dark channel prior model with the underwater diffuse model. The experimental results are given to show the effectiveness of the dark channel prior model in underwater scenarios.

Underwater fiber-wireless communication with a passive front end

Science.gov (United States)

Xu, Jing; Sun, Bin; Lyu, Weichao; Kong, Meiwei; Sarwar, Rohail; Han, Jun; Zhang, Wei; Deng, Ning

2017-11-01

We propose and experimentally demonstrate a novel concept on underwater fiber-wireless (Fi-Wi) communication system with a fully passive wireless front end. A low-cost step-index (SI) plastic optical fiber (POF) together with a passive collimating lens at the front end composes the underwater Fi-Wi architecture. We have achieved a 1.71-Gb/s transmission at a mean BER of 4.97 × 10-3 (1.30 × 10-3 when using power loading) over a 50-m SI-POF and 2-m underwater wireless channel using orthogonal frequency division multiplexing (OFDM). Although the wireless part is very short, it actually plays a crucial role in practical underwater implementation, especially in deep sea. Compared with the wired solution (e.g. using a 52-m POF cable without the UWOC part), the proposed underwater Fi-Wi scheme can save optical wet-mate connectors that are sophisticated, very expensive and difficult to install in deep ocean. By combining high-capacity robust POF with the mobility and ubiquity of underwater wireless optical communication (UWOC), the proposed underwater Fi-Wi technology will find wide application in ocean exploration.

75 FR 3160 - Commerce in Explosives-Storage of Shock Tube With Detonators (2005R-3P)

Science.gov (United States)

2010-01-20

..., Firearms, and Explosives, U.S. Department of Justice, 99 New York Avenue, NE., Washington, DC 20226... separate magazines for each explosive product. ATF estimates the average cost for a new type 4 magazine (4... Reading Room, Room 1E-063, 99 New York Avenue, NE., Washington, DC 20226; telephone: (202) 648-7080...

Delay Tolerance in Underwater Wireless Communications: A Routing Perspective

Directory of Open Access Journals (Sweden)

Safdar Hussain Bouk

2016-01-01

Full Text Available Similar to terrestrial networks, underwater wireless networks (UWNs also aid several critical tasks including coastal surveillance, underwater pollution detection, and other maritime applications. Currently, once underwater sensor nodes are deployed at different levels of the sea, it is nearly impossible or very expensive to reconfigure the hardware, for example, battery. Taking this issue into account, considerable amount of research has been carried out to ensure minimum energy costs and reliable communication between underwater nodes and base stations. As a result, several different network protocols were proposed for UWN, including MAC, PHY, transport, and routing. Recently, a new paradigm was introduced claiming that the intermittent nature of acoustic channel and signal resulted in designing delay tolerant routing schemes for the UWN, known as an underwater delay tolerant network. In this paper, we provide a comprehensive survey of underwater routing protocols with emphasis on the limitations, challenges, and future open issues in the context of delay tolerant network routing.

Source mechanisms of volcanic tsunamis.

Science.gov (United States)

Paris, Raphaël

2015-10-28

Volcanic tsunamis are generated by a variety of mechanisms, including volcano-tectonic earthquakes, slope instabilities, pyroclastic flows, underwater explosions, shock waves and caldera collapse. In this review, we focus on the lessons that can be learnt from past events and address the influence of parameters such as volume flux of mass flows, explosion energy or duration of caldera collapse on tsunami generation. The diversity of waves in terms of amplitude, period, form, dispersion, etc. poses difficulties for integration and harmonization of sources to be used for numerical models and probabilistic tsunami hazard maps. In many cases, monitoring and warning of volcanic tsunamis remain challenging (further technical and scientific developments being necessary) and must be coupled with policies of population preparedness. © 2015 The Author(s).

3D Laser Scanner for Underwater Manipulation.

Science.gov (United States)

Palomer, Albert; Ridao, Pere; Youakim, Dina; Ribas, David; Forest, Josep; Petillot, Yvan

2018-04-04

Nowadays, research in autonomous underwater manipulation has demonstrated simple applications like picking an object from the sea floor, turning a valve or plugging and unplugging a connector. These are fairly simple tasks compared with those already demonstrated by the mobile robotics community, which include, among others, safe arm motion within areas populated with a priori unknown obstacles or the recognition and location of objects based on their 3D model to grasp them. Kinect-like 3D sensors have contributed significantly to the advance of mobile manipulation providing 3D sensing capabilities in real-time at low cost. Unfortunately, the underwater robotics community is lacking a 3D sensor with similar capabilities to provide rich 3D information of the work space. In this paper, we present a new underwater 3D laser scanner and demonstrate its capabilities for underwater manipulation. In order to use this sensor in conjunction with manipulators, a calibration method to find the relative position between the manipulator and the 3D laser scanner is presented. Then, two different advanced underwater manipulation tasks beyond the state of the art are demonstrated using two different manipulation systems. First, an eight Degrees of Freedom (DoF) fixed-base manipulator system is used to demonstrate arm motion within a work space populated with a priori unknown fixed obstacles. Next, an eight DoF free floating Underwater Vehicle-Manipulator System (UVMS) is used to autonomously grasp an object from the bottom of a water tank.

Time-resolved processes in a pulsed electrical discharge in water generated with shock wave assistance in a plate-to-plate configuration

Czech Academy of Sciences Publication Activity Database

Stelmashuk, Vitaliy

2014-01-01

Roč. 47, č. 49 (2014), s. 495204-495204 ISSN 0022-3727 Institutional support: RVO:61389021 Keywords : underwater discharge * streamers * spark * cavitation bubble * shock wave Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.721, year: 2014 http://iopscience.iop.org/0022-3727/47/49/495204/pdf/0022-3727_47_49_495204.pdf

Shock interaction with a two-gas interface in a novel dual-driver shock tube

Science.gov (United States)

Labenski, John R.

Fluid instabilities exist at the interface between two fluids having different densities if the flow velocity and density gradient are anti-parallel or if a shock wave crosses the boundary. The former case is called the Rayleigh-Taylor (R-T) instability and the latter, the Richtmyer-Meshkov (R-M) instability. Small initial perturbations on the interface destabilize and grow into larger amplitude structures leading to turbulent mixing. Instabilities of this type are seen in inertial confinement fusion (ICF) experiments, laser produced plasmas, supernova explosions, and detonations. A novel dual-driver shock tube was used to investigate the growth rate of the R-M instability. One driver is used to create an argon-refrigerant interface, and the other at the opposite end of the driven section generates a shock to force the interface with compressible flows behind the shock. The refrigerant gas in the first driver is seeded with sub-micron oil droplets for visualization of the interface. The interface travels down the driven section past the test section for a fixed amount of time. A stronger shock of Mach 1.1 to 1.3 drives the interface back past the test section where flow diagnostics are positioned. Two schlieren systems record the density fluctuations while light scattering detectors record the density of the refrigerant as a function of position over the interface. A pair of digital cameras take stereo images of the interface, as mapped out by the tracer particles under illumination by a Q-switched ruby laser. The amount of time that the interface is allowed to travel up the driven section determines the interaction time as a control. Comparisons made between the schlieren signals, light scattering detector outputs, and the images quantify the fingered characteristics of the interface and its growth due to shock forcing. The results show that the interface has a distribution of thickness and that the interaction with a shock further broadens the interface. The

Particle acceleration in explosive relativistic reconnection events and Crab Nebula gamma-ray flares

Science.gov (United States)

Lyutikov, Maxim; Komissarov, Serguei; Sironi, Lorenzo

2018-04-01

We develop a model of gamma-ray flares of the Crab Nebula resulting from the magnetic reconnection events in a highly magnetised relativistic plasma. We first discuss physical parameters of the Crab Nebula and review the theory of pulsar winds and termination shocks. We also review the principle points of particle acceleration in explosive reconnection events [Lyutikov et al., J. Plasma Phys., vol. 83(6), p. 635830601 (2017a); J. Plasma Phys., vol. 83(6), p. 635830602 (2017b)]. It is required that particles producing flares are accelerated in highly magnetised regions of the nebula. Flares originate from the poleward regions at the base of the Crab's polar outflow, where both the magnetisation and the magnetic field strength are sufficiently high. The post-termination shock flow develops macroscopic (not related to the plasma properties on the skin-depth scale) kink-type instabilities. The resulting large-scale magnetic stresses drive explosive reconnection events on the light-crossing time of the reconnection region. Flares are produced at the initial stage of the current sheet development, during the X-point collapse. The model has all the ingredients needed for Crab flares: natural formation of highly magnetised regions, explosive dynamics on the light travel time, development of high electric fields on macroscopic scales and acceleration of particles to energies well exceeding the average magnetic energy per particle.

Surface instabilities in shock loaded granular media

Science.gov (United States)

Kandan, K.; Khaderi, S. N.; Wadley, H. N. G.; Deshpande, V. S.

2017-12-01

The initiation and growth of instabilities in granular materials loaded by air shock waves are investigated via shock-tube experiments and numerical calculations. Three types of granular media, dry sand, water-saturated sand and a granular solid comprising PTFE spheres were experimentally investigated by air shock loading slugs of these materials in a transparent shock tube. Under all shock pressures considered here, the free-standing dry sand slugs remained stable while the shock loaded surface of the water-saturated sand slug became unstable resulting in mixing of the shocked air and the granular material. By contrast, the PTFE slugs were stable at low pressures but displayed instabilities similar to the water-saturated sand slugs at higher shock pressures. The distal surfaces of the slugs remained stable under all conditions considered here. Eulerian fluid/solid interaction calculations, with the granular material modelled as a Drucker-Prager solid, reproduced the onset of the instabilities as seen in the experiments to a high level of accuracy. These calculations showed that the shock pressures to initiate instabilities increased with increasing material friction and decreasing yield strain. Moreover, the high Atwood number for this problem implied that fluid/solid interaction effects were small, and the initiation of the instability is adequately captured by directly applying a pressure on the slug surface. Lagrangian calculations with the directly applied pressures demonstrated that the instability was caused by spatial pressure gradients created by initial surface perturbations. Surface instabilities are also shown to exist in shock loaded rear-supported granular slugs: these experiments and calculations are used to infer the velocity that free-standing slugs need to acquire to initiate instabilities on their front surfaces. The results presented here, while in an idealised one-dimensional setting, provide physical understanding of the conditions required to

Underwater hearing in the great cormorant (Phalacrocorax carbo sinensis)

DEFF Research Database (Denmark)

Hansen, Kirstin Anderson; Larsen, Ole Næsbye; Wahlberg, Magnus

2016-01-01

The underwater hearing threshold of a great cormorant (Phalacrocroax carbo sinensis) was measured at 2 kHz using psychophysical methods. Previous in-air and underwater testing suggests that cormorants have rather poor in-air hearing compared to other birds of similar size (Johansen, 2016). Prelim......The underwater hearing threshold of a great cormorant (Phalacrocroax carbo sinensis) was measured at 2 kHz using psychophysical methods. Previous in-air and underwater testing suggests that cormorants have rather poor in-air hearing compared to other birds of similar size (Johansen, 2016...

Intelligent Navigation for a Solar Powered Unmanned Underwater Vehicle

Directory of Open Access Journals (Sweden)

Francisco García-Córdova

2013-04-01

Full Text Available In this paper, an intelligent navigation system for an unmanned underwater vehicle powered by renewable energy and designed for shadow water inspection in missions of a long duration is proposed. The system is composed of an underwater vehicle, which tows a surface vehicle. The surface vehicle is a small boat with photovoltaic panels, a methanol fuel cell and communication equipment, which provides energy and communication to the underwater vehicle. The underwater vehicle has sensors to monitor the underwater environment such as sidescan sonar and a video camera in a flexible configuration and sensors to measure the physical and chemical parameters of water quality on predefined paths for long distances. The underwater vehicle implements a biologically inspired neural architecture for autonomous intelligent navigation. Navigation is carried out by integrating a kinematic adaptive neuro-controller for trajectory tracking and an obstacle avoidance adaptive neuro- controller. The autonomous underwater vehicle is capable of operating during long periods of observation and monitoring. This autonomous vehicle is a good tool for observing large areas of sea, since it operates for long periods of time due to the contribution of renewable energy. It correlates all sensor data for time and geodetic position. This vehicle has been used for monitoring the Mar Menor lagoon.

Optimal Node Placement in Underwater Acoustic Sensor Network

KAUST Repository

Felemban, Muhamad

2011-10-01

Almost 70% of planet Earth is covered by water. A large percentage of underwater environment is unexplored. In the past two decades, there has been an increase in the interest of exploring and monitoring underwater life among scientists and in industry. Underwater operations are extremely difficult due to the lack of cheap and efficient means. Recently, Wireless Sensor Networks have been introduced in underwater environment applications. However, underwater communication via acoustic waves is subject to several performance limitations, which makes the relevant research issues very different from those on land. In this thesis, we investigate node placement for building an initial Underwater Wireless Sensor Network infrastructure. Firstly, we formulated the problem into a nonlinear mathematic program with objectives of minimizing the total transmission loss under a given number of sensor nodes and targeted volume. We conducted experiments to verify the proposed formulation, which is solved using Matlab optimization tool. We represented each node with a truncated octahedron to fill out the 3D space. The truncated octahedrons are tiled in the 3D space with each node in the center where locations of the nodes are given using 3D coordinates. Results are supported using ns-3 simulator. Results from simulation are consistent with the obtained results from mathematical model with less than 10% error.

The Influence of Shock-Induced Air Bubble Collapse Resulting from Underwater Explosive Events

Science.gov (United States)

2012-06-01

Pressure-Time History Results When comparing the pressure-time history in Figure 26, it is important to note the general shape of the curve . The...Indian Head, MD, Final Rep. IHTR 2589, May 28, 2004. [10] V. K. Kedrinskii, “ Rarefaction Waves and Bubbly Cavitation in Real Liquid,” presented at the

Significance of special blasting modes for anti shock struggle at hydrothermal Pribram uranium ore deposit

International Nuclear Information System (INIS)

Stenczel, J.

1988-01-01

Situations are presented which occur in connection with blasting jobs. Special blasting operations are described. In the Pribram uranium deposit two types of special blasting operations were tested. Conditions are described under which softening blasting was carried out. This type of work did not prove satisfactory in operation and is therefore not performed at the Pribram deposit. A theoretical analysis is made of shock distrubance blasting and the procedure of designing such projects, the placement of explosives and the determination of their size. Such blasting jobs have been tested in shock zones of vein node. The total weight of the explosive was 100 to 200 kg of Px V 19. In most cases a mine shock was initiated (in some cases with a delay of up to several dozen hours). The said method increases the technical safety of operation. At the Pribram deposit it is only used in cases of utmost necessity because its use increases costs and delays the procedure of mining work. (E.S.). 9 figs., 1 tab., 6 refs

Features of the Valorization of Single and Double Based Powders for Codetonation in Emulsion Explosives

Science.gov (United States)

Ribeiro, Jose; Mendes, Ricardo; Tavares, Bruno; Louro, Cristina

2013-06-01

In this work, features of the thermal and detonation behavior of compositions resulting from the mixture of single and double based gun powder within ammonium nitrate (AN) based emulsion explosives are shown. That includes results of thermodynamic-equilibrium calculations of the detonation velocity, the chemical compatibility assessment through differential scanning calorimetry [DSC] and thermo gravimetric analysis [TGA], the experimental determination of the detonation velocity and a comparative evaluation of the shock sensitivity using a modified version of the ``gap-test''. DSC/TGA results for the compositions and for the individual components overlap until the beginning of the thermal decomposition which is an indication of the absence of formation of any new chemical specimens and so of the capability of the composition components. After the beginning of the thermal decomposition it can be seen that the rate of mass loss is much higher for the compositions with gun powder than for the sole emulsion explosive. Both, theoretical and experimental, values of the detonation velocity have shown to be higher for the powdered compositions than for the pure emulsion explosive. Shock sensitivity assessment have ended-up with a slightly bigger sensitivity for the compositions with double based gun powder when compared to the single based compositions or to the pure emulsion.

Study on Dynamic Response of Downhole Tools under Perforation Impact Load

Directory of Open Access Journals (Sweden)

Liu Jun

2017-01-01

Full Text Available A model of a multibody system is established to investigate the dynamic response of an oil tube-shock absorber-perforating gun system in downhole perforation-test joint operation. In the model, the oil tube and perforating gun are modeled as elastic rods and the shock absorber is modeled as single particle system with damping and a spring. Two force continuity conditions are used to simulate the interactions among the three components. The perforation impact load is determined by an experiment of underwater explosion of perforating bullets. Using the model, the effects of charge quantity of perforating bullet, the number of shock absorbers, and the length of oil tube on the dynamic response of oil tube and packer are investigated. On this basis, a basic principle of the combination design of shock absorber and oil tube is proposed to improve the mechanical state of downhole tools. The study results can provide theoretical support for the design of downhole perforation-test joint operation.

Underwater television camera for monitoring inner side of pressure vessel

International Nuclear Information System (INIS)

Takayama, Kazuhiko.

1997-01-01

An underwater television support device equipped with a rotatable and vertically movable underwater television camera and an underwater television camera controlling device for monitoring images of the inside of the reactor core photographed by the underwater television camera to control the position of the underwater television camera and the underwater light are disposed on an upper lattice plate of a reactor pressure vessel. Both of them are electrically connected with each other by way of a cable to rapidly observe the inside of the reactor core by the underwater television camera. The reproducibility is extremely satisfactory by efficiently concentrating the position of the camera and image information upon inspection and observation. As a result, the steps for periodical inspection can be reduced to shorten the days for the periodical inspection. Since there is no requirement to withdraw fuel assemblies over a wide reactor core region, and the device can be used with the fuel assemblies being left as they are in the reactor, it is suitable for inspection of detectors for nuclear instrumentation. (N.H.)

3D Laser Scanner for Underwater Manipulation

Directory of Open Access Journals (Sweden)

Albert Palomer

2018-04-01

Full Text Available Nowadays, research in autonomous underwater manipulation has demonstrated simple applications like picking an object from the sea floor, turning a valve or plugging and unplugging a connector. These are fairly simple tasks compared with those already demonstrated by the mobile robotics community, which include, among others, safe arm motion within areas populated with a priori unknown obstacles or the recognition and location of objects based on their 3D model to grasp them. Kinect-like 3D sensors have contributed significantly to the advance of mobile manipulation providing 3D sensing capabilities in real-time at low cost. Unfortunately, the underwater robotics community is lacking a 3D sensor with similar capabilities to provide rich 3D information of the work space. In this paper, we present a new underwater 3D laser scanner and demonstrate its capabilities for underwater manipulation. In order to use this sensor in conjunction with manipulators, a calibration method to find the relative position between the manipulator and the 3D laser scanner is presented. Then, two different advanced underwater manipulation tasks beyond the state of the art are demonstrated using two different manipulation systems. First, an eight Degrees of Freedom (DoF fixed-base manipulator system is used to demonstrate arm motion within a work space populated with a priori unknown fixed obstacles. Next, an eight DoF free floating Underwater Vehicle-Manipulator System (UVMS is used to autonomously grasp an object from the bottom of a water tank.

Explosive simulants for testing explosive detection systems

Science.gov (United States)

Kury, John W.; Anderson, Brian L.

1999-09-28

Explosives simulants that include non-explosive components are disclosed that facilitate testing of equipment designed to remotely detect explosives. The simulants are non-explosive, non-hazardous materials that can be safely handled without any significant precautions. The simulants imitate real explosives in terms of mass density, effective atomic number, x-ray transmission properties, and physical form, including moldable plastics and emulsions/gels.

Centralised versus Decentralised Control Reconfiguration for Collaborating Underwater Robots

DEFF Research Database (Denmark)

Furno, Lidia; Nielsen, Mikkel Cornelius; Blanke, Mogens

2015-01-01

The present paper introduces an approach to fault-tolerant reconfiguration for collaborating underwater robots. Fault-tolerant reconfiguration is obtained using the virtual actuator approach, Steen (2005). The paper investigates properties of a centralised versus a decentralised implementation an...... an underwater drill needs to be transported and positioned by three collaborating robots as part of an underwater autonomous operation....

Dynamics of ionizing shock waves on adiabatic motions of gases

International Nuclear Information System (INIS)

Zorev, N.N.; Sklizkov, G.V.; Shikanov, A.S.

1982-01-01

Results are presented of an experimental investigation of free (adiabatic) motion of a spherical ionizing wave in deuterium produced by an expanding laser plasma. It is shown that the discrepancy between the free movement of shock waves (which lead to total ionization of the gas) and the Sedov-Taylor model of a spontaneous point explosion is not related to variations in the adiabat exponent γ and the motion occurs for a constant γ=5/3. The effect is ascribed to the influence of the shock wave front structure on the dynamics of its propagation. An analytic expression for the motion of symmetric ionizing shock waves is found which has an accuracy of better than 1%. As a result the adiabat exponent was determined experimentally. A method for determining the energy of a shock wave on the basis of its dynamics of motion is developed which has an accuracy of approximately 5% [ru

Equipment and appliances for underwater operations. Pt. 2

International Nuclear Information System (INIS)

Krueger, P.

1976-01-01

The 6/75 edition of 'mt' reported on the 'ARGE underwater appliances' and the study on 'design development of appliances and equipment for underwater use' in a brief summary. One of these designs, the 'unmanned DSWS underwater appliance' was described in detail. The present article describes three further design developments mentioned in the above study and which are based on unmanned appliances connected to the mother-ship. These designs were developed by Preussag-Meerestechnik. (orig.) [de

Simulations of Shock Wave Interaction with a Particle Cloud

Science.gov (United States)

Koneru, Rahul; Rollin, Bertrand; Ouellet, Frederick; Annamalai, Subramanian; Balachandar, S.'Bala'

2016-11-01

Simulations of a shock wave interacting with a cloud of particles are performed in an attempt to understand similar phenomena observed in dispersal of solid particles under such extreme environment as an explosion. We conduct numerical experiments in which a particle curtain fills only 87% of the shock tube from bottom to top. As such, the particle curtain upon interaction with the shock wave is expected to experience Kelvin-Helmholtz (KH) and Richtmyer-Meshkov (RM) instabilities. In this study, the initial volume fraction profile matches with that of Sandia Multiphase Shock Tube experiments, and the shock Mach number is limited to M =1.66. In these simulations we use a Eulerian-Lagrangian approach along with state-of-the-art point-particle force and heat transfer models. Measurements of particle dispersion are made at different initial volume fractions of the particle cloud. A detailed analysis of the evolution of the particle curtain with respect to the initial conditions is presented. This work was supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, Contract No. DE-NA0002378.

Underwater cladding with laser beam and plasma arc welding

International Nuclear Information System (INIS)

White, R.A.; Fusaro, R.; Jones, M.G.; Solomon, H.D.; Milian-Rodriguez, R.R.

1997-01-01

Two welding processes, plasma arc (transferred arc) (PTA) and laser beam, were investigated to apply cladding to austenitic stainless steels and Inconel 600. These processes have long been used to apply cladding layers , but the novel feature being reported here is that these cladding layers were applied underwater, with a water pressure equivalent to 24 m (80 ft). Being able to apply the cladding underwater is very important for many applications, including the construction of off-shore oil platforms and the repair of nuclear reactors. In the latter case, being able to weld underwater eliminates the need for draining the reactor and removing the fuel. Welding underwater in reactors presents numerous challenges, but the ability to weld without having to drain the reactor and remove the fuel provides a huge cost savings. Welding underwater in reactors must be done remotely, but because of the radioactive corrosion products and neutron activation of the steels, remote welding would also be required even if the reactor is drained and the fuel removed. In fact, without the shielding of the water, the remote welding required if the reactor is drained might be even more difficult than that required with underwater welds. Furthermore, as shall be shown, the underwater welds that the authors have made were of high quality and exhibit compressive rather than tensile residual stresses

Underwater image mosaicking and visual odometry

Science.gov (United States)

Sadjadi, Firooz; Tangirala, Sekhar; Sorber, Scott

2017-05-01

This paper summarizes the results of studies in underwater odometery using a video camera for estimating the velocity of an unmanned underwater vehicle (UUV). Underwater vehicles are usually equipped with sonar and Inertial Measurement Unit (IMU) - an integrated sensor package that combines multiple accelerometers and gyros to produce a three dimensional measurement of both specific force and angular rate with respect to an inertial reference frame for navigation. In this study, we investigate the use of odometry information obtainable from a video camera mounted on a UUV to extract vehicle velocity relative to the ocean floor. A key challenge with this process is the seemingly bland (i.e. featureless) nature of video data obtained underwater which could make conventional approaches to image-based motion estimation difficult. To address this problem, we perform image enhancement, followed by frame to frame image transformation, registration and mosaicking/stitching. With this approach the velocity components associated with the moving sensor (vehicle) are readily obtained from (i) the components of the transform matrix at each frame; (ii) information about the height of the vehicle above the seabed; and (iii) the sensor resolution. Preliminary results are presented.

Underwater Gliders: A Review

Directory of Open Access Journals (Sweden)

Javaid Muhammad Yasar

2014-07-01

Full Text Available Underwater gliders are a type of underwater vehicle that transverse the oceans by shifting its buoyancy, during which its wings develop a component of the downward motion in the horizontal plane, thus producing a forward force. They are primarily used in oceanography sensing and data collection and play an important role in ocean research and development. Although there have been considerable developments in these gliders since the development of the first glider concept in 1989, to date, no review of these gliders have been done. This paper reviews existing underwater gliders, with emphasis on their respective working principles, range and payload capacity. All information on gliders available in the public domain or published in literature from the year 2000-2013 was reviewed. The majority of these gliders have an operational depth of 1000 m and a payload of less than 25 kg. The exception is a blend-body shape glider, which has a payload of approximately 800 kg and an operational depth around about 300 m. However, the commercialization of these gliders has been limited with only three know examples that have been successfully commercialized.

Underwater Object Segmentation Based on Optical Features

Directory of Open Access Journals (Sweden)

Zhe Chen

2018-01-01

Full Text Available Underwater optical environments are seriously affected by various optical inputs, such as artificial light, sky light, and ambient scattered light. The latter two can block underwater object segmentation tasks, since they inhibit the emergence of objects of interest and distort image information, while artificial light can contribute to segmentation. Artificial light often focuses on the object of interest, and, therefore, we can initially identify the region of target objects if the collimation of artificial light is recognized. Based on this concept, we propose an optical feature extraction, calculation, and decision method to identify the collimated region of artificial light as a candidate object region. Then, the second phase employs a level set method to segment the objects of interest within the candidate region. This two-phase structure largely removes background noise and highlights the outline of underwater objects. We test the performance of the method with diverse underwater datasets, demonstrating that it outperforms previous methods.

Shocked molecular gas and the origin of cosmic rays

Science.gov (United States)

Reach, William; Gusdorf, Antoine; Richter, Matthew

2018-06-01

When massive stars reach the end of their ability to remain stable with core nuclear fusion, they explode in supernovae that drive powerful shocks into their surroundings. Because massive stars form in and remain close to molecular clouds they often drive shocks into dense gas, which is now believed to be the origin of a significant fraction of galactic cosmic rays. The nature of the supernova-molecular cloud interaction is not well understood, though observations are gradually elucidating their nature. The range of interstellar densities, and the inclusion of circumstellar matter from the late-phase mass-loss of the stars before their explosions, leads to a wide range of possible appearances and outcomes. In particular, it is not even clear what speed or physical type of shocks are present: are they dense, magnetically-mediated shocks where H2 is not dissociated, or are they faster shocks that dissociate molecules and destroy some of the grains? SOFIA is observing some of the most significant (in terms of cosmic ray production potential and infrared energy output) supernova-molecular cloud interactions for measurement of the line widths of key molecular shocks tracers: H2, [OI], and CO. The presence of gas at speeds 100 km/s or greater would indicate dissociative shocks, while speeds 30 km/s and slower retain most molecules. The shock velocity is a key ingredient in modeling the interaction between supernovae and molecular clouds including the potential for formation of cosmic rays.

MEASUREMENTS OF SHOCK WAVE FORCE IN SHOCK TUBE WITH INDIRECT METHODS

Directory of Open Access Journals (Sweden)

Mario Dobrilović

2005-12-01

Full Text Available Tests have been conducted at the “Laboratory for testing of civil explosives, detonators, electrical detonators and pyrotechnical materials”, Department for mining and geotechnics of the Faculty of mining, geology and petroleum engineering, University of Zagreb with the purpose of designing a detonator that would unite advantages of a non-electric system and the precision in regulation of time delay in electronic initiation system. Sum of energy released by the wave force in shock tube is a pre-condition for operation of the new detonator, and measurement of wave force is the first step in determining the sum of energy. The sum of energy is measured indirectly, based on two principles: movement sensors and strain.

Rotation-supported Neutrino-driven Supernova Explosions in Three Dimensions and the Critical Luminosity Condition

Science.gov (United States)

Summa, Alexander; Janka, Hans-Thomas; Melson, Tobias; Marek, Andreas

2018-01-01

We present the first self-consistent, 3D core-collapse supernova simulations performed with the PROMETHEUS-VERTEX code for a rotating progenitor star. Besides using the angular momentum of the 15 M ⊙ model as obtained in the stellar evolution calculation with an angular frequency of ∼10‑3 rad s‑1 (spin period of more than 6000 s) at the Si/Si–O interface, we also computed 2D and 3D cases with no rotation and with a ∼300 times shorter rotation period and different angular resolutions. In 2D, only the nonrotating and slowly rotating models explode, while rapid rotation prevents an explosion within 500 ms after bounce because of lower radiated neutrino luminosities and mean energies and thus reduced neutrino heating. In contrast, only the fast-rotating model develops an explosion in 3D when the Si/Si–O interface collapses through the shock. The explosion becomes possible by the support of a powerful standing accretion shock instability spiral mode, which compensates for the reduced neutrino heating and pushes strong shock expansion in the equatorial plane. Fast rotation in 3D leads to a “two-dimensionalization” of the turbulent energy spectrum (yielding roughly a ‑3 instead of a ‑5/3 power-law slope at intermediate wavelengths) with enhanced kinetic energy on the largest spatial scales. We also introduce a generalization of the “universal critical luminosity condition” of Summa et al. to account for the effects of rotation, and we demonstrate its viability for a set of more than 40 core-collapse simulations, including 9 and 20 M ⊙ progenitors, as well as black-hole-forming cases of 40 and 75 M ⊙ stars to be discussed in forthcoming papers.

Hydrodynamic Coefficients Identification and Experimental Investigation for an Underwater Vehicle

Directory of Open Access Journals (Sweden)

Shaorong XIE

2014-02-01

Full Text Available Hydrodynamic coefficients are the foundation of unmanned underwater vehicles modeling and controller design. In order to reduce identification complexity and acquire necessary hydrodynamic coefficients for controllers design, the motion of the unmanned underwater vehicle was separated into vertical motion and horizontal motion models. Hydrodynamic coefficients were regarded as mapping parameters from input forces and moments to output velocities and acceleration of the unmanned underwater vehicle. The motion models of the unmanned underwater vehicle were nonlinear and Genetic Algorithm was adopted to identify those hydrodynamic coefficients. To verify the identification quality, velocities and acceleration of the unmanned underwater vehicle was measured using inertial sensor under the same conditions as Genetic Algorithm identification. Curves similarity between measured velocities and acceleration and those identified by Genetic Algorithm were used as optimizing standard. It is found that the curves similarity were high and identified hydrodynamic coefficients of the unmanned underwater vehicle satisfied the measured motion states well.

4th Pacific Rim Underwater Acoustics Conference

CERN Document Server

Xu, Wen; Cheng, Qianliu; Zhao, Hangfang

2016-01-01

These proceedings are a collection of 16 selected scientific papers and reviews by distinguished international experts that were presented at the 4th Pacific Rim Underwater Acoustics Conference (PRUAC), held in Hangzhou, China in October 2013. The topics discussed at the conference include internal wave observation and prediction; environmental uncertainty and coupling to sound propagation; environmental noise and ocean dynamics; dynamic modeling in acoustic fields; acoustic tomography and ocean parameter estimation; time reversal and matched field processing; underwater acoustic localization and communication as well as measurement instrumentations and platforms. These proceedings provide insights into the latest developments in underwater acoustics, promoting the exchange of ideas for the benefit of future research.

Research topics in explosives - a look at explosives behaviors

International Nuclear Information System (INIS)

Maienschein, J L

2014-01-01

The behaviors of explosives under many conditions - e.g., sensitivity to inadvertent reactions, explosion, detonation - are controlled by the chemical and physical properties of the explosive materials. Several properties are considered for a range of improvised and conventional explosives. Here I compare these properties across a wide range of explosives to develop an understanding of explosive behaviors. For improvised explosives, which are generally heterogeneous mixtures of ingredients, a range of studies is identified as needed to more fully understand their behavior and properties. For conventional explosives, which are generally comprised of crystalline explosive molecules held together with a binder, I identify key material properties that determine overall sensitivity, including the extremely safe behavior of Insensitive High Explosives, and discuss an approach to predicting the sensitivity or insensitivity of an explosive.

Theoretical and experimental investigation of shock wave stressing of metal powders by an explosion

Directory of Open Access Journals (Sweden)

Lukyanov Ya.L.

2011-01-01

Full Text Available Joint theoretical and experimental investigations have allowed to realize an approach with use of mathematical and physical modeling of processes of a shock wave loading of powder materials. Hugoniot adiabats of the investigated powder have been measured with a noncontact electromagnetic method. The mathematical model of elastic-plastic deformation of the powder media used in the investigation has been validated. Numerical simulation of shock wave propagation and experimental assembly deformation has been performed.

Characteristics and measurement of supersonic projectile shock waves by a 32-microphone ring array

Science.gov (United States)

Chang, Ho; Wu, Yan-Chyuan; Tsung, Tsing-Tshih

2011-08-01

This paper discusses about the characteristics of supersonic projectile shock wave in muzzle region during firing of high explosive anti-tank (HEAT) and high explosive (HE) projectiles. HEAT projectiles are fired horizontally at a muzzle velocity of Mach 3.5 from a medium caliber tank gun equipped with a newly designed multi-perforated muzzle brake, whereas HE projectiles are fired at elevation angles at a muzzle velocity of Mach 2 from a large caliber howitzer equipped with a newly designed double-baffle muzzle brake. In the near field, pressure signatures of the N-wave generated from projectiles are measured by 32-microphone ring array wrapped by cotton sheath. Records measured by the microphone array are used to demonstrate several key characteristics of the shock wave of supersonic projectile. All measurements made in this study can be a significant reference for developing guns, tanks, or the chassis of fighting vehicles.

The influence of underwater turbulence on optical phase measurements

Science.gov (United States)

Redding, Brandon; Davis, Allen; Kirkendall, Clay; Dandridge, Anthony

2016-05-01

Emerging underwater optical imaging and sensing applications rely on phase-sensitive detection to provide added functionality and improved sensitivity. However, underwater turbulence introduces spatio-temporal variations in the refractive index of water which can degrade the performance of these systems. Although the influence of turbulence on traditional, non-interferometric imaging has been investigated, its influence on the optical phase remains poorly understood. Nonetheless, a thorough understanding of the spatio-temporal dynamics of the optical phase of light passing through underwater turbulence are crucial to the design of phase-sensitive imaging and sensing systems. To address this concern, we combined underwater imaging with high speed holography to provide a calibrated characterization of the effects of turbulence on the optical phase. By measuring the modulation transfer function of an underwater imaging system, we were able to calibrate varying levels of optical turbulence intensity using the Simple Underwater Imaging Model (SUIM). We then used high speed holography to measure the temporal dynamics of the optical phase of light passing through varying levels of turbulence. Using this method, we measured the variance in the amplitude and phase of the beam, the temporal correlation of the optical phase, and recorded the turbulence induced phase noise as a function of frequency. By bench marking the effects of varying levels of turbulence on the optical phase, this work provides a basis to evaluate the real-world potential of emerging underwater interferometric sensing modalities.

Optimal Node Placement in Underwater Wireless Sensor Networks

KAUST Repository

Felamban, M.; Shihada, Basem; Jamshaid, K.

2013-01-01

Wireless Sensor Networks (WSN) are expected to play a vital role in the exploration and monitoring of underwater areas which are not easily reachable by humans. However, underwater communication via acoustic waves is subject to several performance

Operational experience in underwater photogrammetry

Science.gov (United States)

Leatherdale, John D.; John Turner, D.

Underwater photogrammetry has become established as a cost-effective technique for inspection and maintenance of platforms and pipelines for the offshore oil industry. A commercial service based in Scotland operates in the North Sea, USA, Brazil, West Africa and Australia. 70 mm cameras and flash units are built for the purpose and analytical plotters and computer graphics systems are used for photogrammetric measurement and analysis of damage, corrosion, weld failures and redesign of underwater structures. Users are seeking simple, low-cost systems for photogrammetric analysis which their engineers can use themselves.

Evaluating the SCC resistance of underwater welds in sodium tetrathionate

International Nuclear Information System (INIS)

White, R.A.; Angeliu, T.M.

1997-01-01

The susceptibility of welds to stress corrosion cracking (SCC) is enhanced by the surface residual tensile stresses generated by the typical welding process. However, underwater plasma transferred arc (PTA) welding has been shown to produce compressive surface residual stresses, an encouraging result if repairs of cracked boiling water reactor (BWR) components are to be made without further endangering them to SCC. This program was designed to verify that underwater PTA welds are resistant to SCC and to determine if underwater PTA welding could mitigate SCC in potentially susceptible welds. This was achieved by exposing various welds on solution annealed (SA) and SA + thermally sensitized 304 stainless steel at 25 C in a solution of 1.5 gm/liter of sodium sulfide added to 0.05M sodium tetrathionate, titrated to a pH of 1.25 with H 2 SO 4 . The autogeneous welds were produced using gas tungsten arc (GTA) and plasma transferred arc (PTA) welding under atmospheric conditions, and PTA welding underwater. After 1 hour of sodium tetrathionate exposure, GTA and air PTA welds exhibited SCC while the underwater PTA weld heat affected zones were more resistant. Underwater PTA welds bisecting a GTA weld eliminated the cracking in the GTA weld heat affected zone under certain conditions. The lack of IG cracking in the region influenced by the underwater PTA weld is consistent with the measurement of compressive surface residual stresses inherent to the underwater welding process

Trade-off Analysis of Underwater Acoustic Sensor Networks

Science.gov (United States)

Tuna, G.; Das, R.

2017-09-01

In the last couple of decades, Underwater Acoustic Sensor Networks (UASNs) were started to be used for various commercial and non-commercial purposes. However, in underwater environments, there are some specific inherent constraints, such as high bit error rate, variable and large propagation delay, limited bandwidth capacity, and short-range communications, which severely degrade the performance of UASNs and limit the lifetime of underwater sensor nodes as well. Therefore, proving reliability of UASN applications poses a challenge. In this study, we try to balance energy consumption of underwater acoustic sensor networks and minimize end-to-end delay using an efficient node placement strategy. Our simulation results reveal that if the number of hops is reduced, energy consumption can be reduced. However, this increases end-to-end delay. Hence, application-specific requirements must be taken into consideration when determining a strategy for node deployment.

Magnetogasdynamic spherical shock wave in a non-ideal gas under gravitational field with conductive and radiative heat fluxes

Science.gov (United States)

Nath, G.; Vishwakarma, J. P.

2016-11-01

Similarity solutions are obtained for the flow behind a spherical shock wave in a non-ideal gas under gravitational field with conductive and radiative heat fluxes, in the presence of a spatially decreasing azimuthal magnetic field. The shock wave is driven by a piston moving with time according to power law. The radiation is considered to be of the diffusion type for an optically thick grey gas model and the heat conduction is expressed in terms of Fourier's law for heat conduction. Similarity solutions exist only when the surrounding medium is of constant density. The gas is assumed to have infinite electrical conductivity and to obey a simplified van der Waals equation of state. It is shown that an increase of the gravitational parameter or the Alfven-Mach number or the parameter of the non-idealness of the gas decreases the compressibility of the gas in the flow-field behind the shock, and hence there is a decrease in the shock strength. The pressure and density vanish at the inner surface (piston) and hence a vacuum is formed at the center of symmetry. The shock waves in conducting non-ideal gas under gravitational field with conductive and radiative heat fluxes can be important for description of shocks in supernova explosions, in the study of a flare produced shock in the solar wind, central part of star burst galaxies, nuclear explosion etc. The solutions obtained can be used to interpret measurements carried out by space craft in the solar wind and in neighborhood of the Earth's magnetosphere.

Nanosecond formation of diamond and lonsdaleite by shock compression of graphite.

Science.gov (United States)

Kraus, D; Ravasio, A; Gauthier, M; Gericke, D O; Vorberger, J; Frydrych, S; Helfrich, J; Fletcher, L B; Schaumann, G; Nagler, B; Barbrel, B; Bachmann, B; Gamboa, E J; Göde, S; Granados, E; Gregori, G; Lee, H J; Neumayer, P; Schumaker, W; Döppner, T; Falcone, R W; Glenzer, S H; Roth, M

2016-03-14

The shock-induced transition from graphite to diamond has been of great scientific and technological interest since the discovery of microscopic diamonds in remnants of explosively driven graphite. Furthermore, shock synthesis of diamond and lonsdaleite, a speculative hexagonal carbon polymorph with unique hardness, is expected to happen during violent meteor impacts. Here, we show unprecedented in situ X-ray diffraction measurements of diamond formation on nanosecond timescales by shock compression of pyrolytic as well as polycrystalline graphite to pressures from 19 GPa up to 228 GPa. While we observe the transition to diamond starting at 50 GPa for both pyrolytic and polycrystalline graphite, we also record the direct formation of lonsdaleite above 170 GPa for pyrolytic samples only. Our experiment provides new insights into the processes of the shock-induced transition from graphite to diamond and uniquely resolves the dynamics that explain the main natural occurrence of the lonsdaleite crystal structure being close to meteor impact sites.

Terminal velocity of liquids and granular materials dispersed by a high explosive

Science.gov (United States)

Loiseau, J.; Pontalier, Q.; Milne, A. M.; Goroshin, S.; Frost, D. L.

2018-04-01

The explosive dispersal of a layer of solid particles or a layer of liquid surrounding a spherical high-explosive charge generates a turbulent, multiphase flow. Shock compression of the material layer during the initial acceleration may partially consolidate the material, leading to the formation of jet-like structures when the layer fragments and sheds particles upon release. Similarly, release of a shock-compressed liquid shell causes the nucleation of cavitation sites, leading to the radial breakup of the shell and the formation of jets upon expansion. In the current study, a wide variety of granular materials and liquids were explosively dispersed. The maximum terminal jet tip or shell velocity was measured using high-speed videography. Charges were constructed using thin-walled glass bulbs of various diameters and contained a central C-4 charge surrounded by the material to be dispersed. This permitted variation of the ratio of material mass to charge mass (M/C) from 4 to 300. Results indicated that material velocity broadly correlates with predictions of the Gurney model. For liquids, the terminal velocity was accurately predicted by the Gurney model. For granular materials, Gurney over-predicted the terminal velocity by 25-60%, depending on the M/C ratio, with larger M/C values exhibiting larger deficits. These deficits are explained by energy dissipation during the collapse of voids in the granular material bed. Velocity deficits were insensitive to the degree of jetting and granular material properties. Empirical corrections to the Gurney model are presented with improved agreement with the dry powder experimental velocities.

Terminal velocity of liquids and granular materials dispersed by a high explosive

Science.gov (United States)

Loiseau, J.; Pontalier, Q.; Milne, A. M.; Goroshin, S.; Frost, D. L.

2018-05-01

The explosive dispersal of a layer of solid particles or a layer of liquid surrounding a spherical high-explosive charge generates a turbulent, multiphase flow. Shock compression of the material layer during the initial acceleration may partially consolidate the material, leading to the formation of jet-like structures when the layer fragments and sheds particles upon release. Similarly, release of a shock-compressed liquid shell causes the nucleation of cavitation sites, leading to the radial breakup of the shell and the formation of jets upon expansion. In the current study, a wide variety of granular materials and liquids were explosively dispersed. The maximum terminal jet tip or shell velocity was measured using high-speed videography. Charges were constructed using thin-walled glass bulbs of various diameters and contained a central C-4 charge surrounded by the material to be dispersed. This permitted variation of the ratio of material mass to charge mass ( M/ C) from 4 to 300. Results indicated that material velocity broadly correlates with predictions of the Gurney model. For liquids, the terminal velocity was accurately predicted by the Gurney model. For granular materials, Gurney over-predicted the terminal velocity by 25-60%, depending on the M/ C ratio, with larger M/ C values exhibiting larger deficits. These deficits are explained by energy dissipation during the collapse of voids in the granular material bed. Velocity deficits were insensitive to the degree of jetting and granular material properties. Empirical corrections to the Gurney model are presented with improved agreement with the dry powder experimental velocities.

Single High Fidelity Geometric Data Sets for LCM - Model Requirements

Science.gov (United States)

2006-11-01

designed specifically to withstand severe underwater explosion (UNDEX) loading caused by the detonation of weapons such as bombs, missiles, mines and... Explosions ( BLEVEs ): The energy from a BLEVE is from a sudden change of phase of stored material. Tanks of liquids immersed in pool fires BLEVE when the...2.10.3 Summary of Data Requirements ....................................................... 46 2.11 Underwater Explosion

Data derived from constitutive laws for description of shock wave propagation in concrete. Final report

International Nuclear Information System (INIS)

Eibl, J.; Ockert, J.

1994-01-01

Especially the need to design safe reactor containments, but also the necessity to protect facilities and human beings against impacts induced secondarily by explosions and detonations, demand simulations and design calculations of concrete under shock wave loading. The necessary computer codes are available, but the relevant constitutive laws for concrete with volumetric pressures up to more than 10000 MPa are lacking. Therefore shock wave tests have been carried out to develop such constitutive laws by loading concrete slabs with contact explosions. By the use of hot-molded carbon composition resistors shock waves propagating through the slab were measured. Pressures up to 13900 MPa were registered. Additionally shock wave velocities were determined from the different arrival times of the wave at the gages. By these two measured values and the conservation equations of mass and momentum the needed p-V relationship, the so called Hugoniot-Curve, was established up to 13900 MPa. Using the theory of Mie-Grueneisen and the so called P-α model the Hugoniot-Curve was extended to the equation of state for concrete. In a first step the deviatoric part of the constitutive law was attached from own static experiments considering the existing knowledge of strain rate effects since relevant dynamic tests under extreme loads are not available. With this constitutive law the analysis of the experiments then was backward verified in detail. (orig.) [de

Youngest Stellar Explosion in Our Galaxy Discovered

Science.gov (United States)

2008-05-01

Astronomers have found the remains of the youngest supernova, or exploded star, in our Galaxy. The supernova remnant, hidden behind a thick veil of gas and dust, was revealed by the National Science Foundation's Very Large Array (VLA) and NASA's Chandra X-Ray Observatory, which could see through the murk. The object is the first example of a "missing population" of young supernova remnants. 1985 and 2008 VLA Images Move cursor over image to blink. VLA Images of G1.9+0.3 in 1985 and 2008: Circle for size comparison. CREDIT: Green, et al., NRAO/AUI/NSF From observing supernovae in other galaxies, astronomers have estimated that about three such stellar explosions should occur in our Milky Way every century. However, the most recent one known until now occurred around 1680, creating the remnant called Cassiopeia A. The newly-discovered object is the remnant of an explosion only about 140 years ago. "If the supernova rate estimates are correct, there should be the remnants of about 10 supernova explosions in the Milky Way that are younger than Cassiopeia A," said David Green of the University of Cambridge in the UK, who led the VLA study. "It's great to finally track one of them down." Supernova explosions, which mark the violent death of a star, release tremendous amounts of energy and spew heavy elements such as calcium and iron into interstellar space. They thus seed the clouds of gas and dust from which new stars and planets are formed and, through their blast shocks, can even trigger such formation. The lack of evidence for young supernova remnants in the Milky Way had caused astronomers to wonder if our Galaxy, which appears otherwise normal, differed in some unknown way from others. Alternatively, scientists thought that the "missing" Milky Way supernovae perhaps indicated that their understanding of the relationship between supernovae and other galactic processes was in error. The astronomers made their discovery by measuring the expansion of the debris from

Filming Underwater in 3d Respecting Stereographic Rules

Science.gov (United States)

Rinaldi, R.; Hordosch, H.

2015-04-01

After an experimental phase of many years, 3D filming is now effective and successful. Improvements are still possible, but the film industry achieved memorable success on 3D movie's box offices due to the overall quality of its products. Special environments such as space ("Gravity") and the underwater realm look perfect to be reproduced in 3D. "Filming in space" was possible in "Gravity" using special effects and computer graphic. The underwater realm is still difficult to be handled. Underwater filming in 3D was not that easy and effective as filming in 2D, since not long ago. After almost 3 years of research, a French, Austrian and Italian team realized a perfect tool to film underwater, in 3D, without any constrains. This allows filmmakers to bring the audience deep inside an environment where they most probably will never have the chance to be.

FILMING UNDERWATER IN 3D RESPECTING STEREOGRAPHIC RULES

Directory of Open Access Journals (Sweden)

R. Rinaldi

2015-04-01

Full Text Available After an experimental phase of many years, 3D filming is now effective and successful. Improvements are still possible, but the film industry achieved memorable success on 3D movie’s box offices due to the overall quality of its products. Special environments such as space ("Gravity" and the underwater realm look perfect to be reproduced in 3D. "Filming in space" was possible in "Gravity" using special effects and computer graphic. The underwater realm is still difficult to be handled. Underwater filming in 3D was not that easy and effective as filming in 2D, since not long ago. After almost 3 years of research, a French, Austrian and Italian team realized a perfect tool to film underwater, in 3D, without any constrains. This allows filmmakers to bring the audience deep inside an environment where they most probably will never have the chance to be.

Wireless Underwater Monitoring Systems Based on Energy Harvestings

Directory of Open Access Journals (Sweden)

Sea-Hee HWANGBO

2013-01-01

Full Text Available One of the important research fields for aquatic exploitation and conservation is underwater wireless sensor network. Since limited energy source for underwater nodes and devices is a main open problem, in this paper, we propose wireless underwater monitoring systems powered by energy harvester which resolves the energy constraint. The target system generates renewable energy from energy harvester and shares the energy with underwater sensor nodes. For the realization of the system, key components to be investigated are discriminated as follows: acoustic modem, actuator, smart battery charge controller, energy harvester and wireless power transfer module. By developing acoustic modem, actuator and smart battery charge controller and utilizing off-the-shelf energy harvester and wireless power transfer module, we design and implement a prototype of the system. Also, we verify the feasibility of concept of target system by conducting indoor and outdoor experiments.

Low-contrast underwater living fish recognition using PCANet

Science.gov (United States)

Sun, Xin; Yang, Jianping; Wang, Changgang; Dong, Junyu; Wang, Xinhua

2018-04-01

Quantitative and statistical analysis of ocean creatures is critical to ecological and environmental studies. And living fish recognition is one of the most essential requirements for fishery industry. However, light attenuation and scattering phenomenon are present in the underwater environment, which makes underwater images low-contrast and blurry. This paper tries to design a robust framework for accurate fish recognition. The framework introduces a two stage PCA Network to extract abstract features from fish images. On a real-world fish recognition dataset, we use a linear SVM classifier and set penalty coefficients to conquer data unbalanced issue. Feature visualization results show that our method can avoid the feature distortion in boundary regions of underwater image. Experiments results show that the PCA Network can extract discriminate features and achieve promising recognition accuracy. The framework improves the recognition accuracy of underwater living fishes and can be easily applied to marine fishery industry.

Laser driven single shock compression of fluid deuterium from 45 to 220 GPa

Energy Technology Data Exchange (ETDEWEB)

Hicks, D; Boehly, T; Celliers, P; Eggert, J; Moon, S; Meyerhofer, D; Collins, G

2008-03-23

The compression {eta} of liquid deuterium between 45 and 220 GPa under laser-driven shock loading has been measured using impedance matching to an aluminum (Al) standard. An Al impedance match model derived from a best fit to absolute Hugoniot data has been used to quantify and minimize the systematic errors caused by uncertainties in the high-pressure Al equation of state. In deuterium below 100 GPa results show that {eta} {approx_equal} 4.2, in agreement with previous impedance match data from magnetically-driven flyer and convergent-explosive shock wave experiments; between 100 and 220 GPa {eta} reaches a maximum of {approx}5.0, less than the 6-fold compression observed on the earliest laser-shock experiments but greater than expected from simple extrapolations of lower pressure data. Previous laser-driven double-shock results are found to be in good agreement with these single-shock measurements over the entire range under study. Both sets of laser-shock data indicate that deuterium undergoes an abrupt increase in compression at around 110 GPa.

Automatic stabilization of underwater robots in the time manipulation operations

International Nuclear Information System (INIS)

Filaretov, V.F.; Koval, E.V.

1994-01-01

When carrying out underwater technical works by means of an underwater vehicles having a manipulator it is desirable to perform manipulation operations in the regime of the underwater vehicle hovering above the object without durable and complicated operations up its rigid fixation. Underwater vehicle stabilization is achieved by compensation all the effects on the vehicle caused by the operating manipulator in water medium. This automatic stabilization is formed due to input of the required control signals into corresponding vehicle propellers proportional to calculated components of the generalized forces and moments. The propellers should form stops reacting against effects

Development of axial tomography technique for the study of steam explosion

Energy Technology Data Exchange (ETDEWEB)

Lee, Jae Young; Seo, S. W.; You, S. [Handong Golbal Univ., Pohang (Korea, Republic of)

2006-05-15

In this report, axial tomography applying to steam explosion is implemented. When steam explosion experiment is performed, we have seen the difficulty with physical modeling due to the complex phenomena of generated steam, propagation of shock wave and bubble breakup and coalescence. Hence, the uncertainty due to these phenomena is occurred. The fast and global measurement of the steam distribution is imperative to understand the complex phenomena performed during the steam explosion, KAERI have developed the fast and global measuring instrument to monitor such phenomena of axial steam distribution. Generally, X-ray is used as measuring method, but this method is very expensive and has limited measurement area. So we need new method that can substitute X-ray method and in this research, ECT method is replaced. The research is performed dividing within two parts: Software and Hardware. In the software part, the electric field analysis code and algorithm for inverse projection were developed. And, in the hardware part, capacitance measurement circuit is developed to measure up to fF level. Operable axial tomography was analyzed with concept design of axial tomography appropriate to steam explosion accident and analysis code for axial electric field analysis and inverse algorithm were developed, moreover, designing signal analysis system for axial tomography was performed.

WODA technical guidance on underwater sound from dredging

NARCIS (Netherlands)

Thomsen, F.; Borsani, F.; Clarke, D.; Jong, C. de; Wit, P. de; Goethals, F.; Holtkamp, M.; Martin, E.S.; Spadaro, P.; Raalte, G. van; Victor, G.Y.V.; Jensen, A.

2016-01-01

The World Organization of Dredging Associations (WODA) has identified underwater sound as an environmental issue that needs further consideration. A WODA Expert Group on Underwater Sound (WEGUS) prepared a guidance paper in 2013 on dredging sound, including a summary of potential impacts on aquatic

A NEW MULTI-DIMENSIONAL GENERAL RELATIVISTIC NEUTRINO HYDRODYNAMICS CODE OF CORE-COLLAPSE SUPERNOVAE. III. GRAVITATIONAL WAVE SIGNALS FROM SUPERNOVA EXPLOSION MODELS

International Nuclear Information System (INIS)

Müller, Bernhard; Janka, Hans-Thomas; Marek, Andreas

2013-01-01

We present a detailed theoretical analysis of the gravitational wave (GW) signal of the post-bounce evolution of core-collapse supernovae (SNe), employing for the first time relativistic, two-dimensional explosion models with multi-group, three-flavor neutrino transport based on the ray-by-ray-plus approximation. The waveforms reflect the accelerated mass motions associated with the characteristic evolutionary stages that were also identified in previous works: a quasi-periodic modulation by prompt post-shock convection is followed by a phase of relative quiescence before growing amplitudes signal violent hydrodynamical activity due to convection and the standing accretion shock instability during the accretion period of the stalled shock. Finally, a high-frequency, low-amplitude variation from proto-neutron star (PNS) convection below the neutrinosphere appears superimposed on the low-frequency trend associated with the aspherical expansion of the SN shock after the onset of the explosion. Relativistic effects in combination with detailed neutrino transport are shown to be essential for quantitative predictions of the GW frequency evolution and energy spectrum, because they determine the structure of the PNS surface layer and its characteristic g-mode frequency. Burst-like high-frequency activity phases, correlated with sudden luminosity increase and spectral hardening of electron (anti-)neutrino emission for some 10 ms, are discovered as new features after the onset of the explosion. They correspond to intermittent episodes of anisotropic accretion by the PNS in the case of fallback SNe. We find stronger signals for more massive progenitors with large accretion rates. The typical frequencies are higher for massive PNSs, though the time-integrated spectrum also strongly depends on the model dynamics.

Underwater laser imaging system (UWLIS)

Energy Technology Data Exchange (ETDEWEB)

DeLong, M. [Lawrence Livermore National Lab., CA (United States)

1994-11-15

Practical limitations with underwater imaging systems area reached when the noise in the back scattered radiation generated in the water between the imaging system and the target obscures the spatial contrast and resolution necessary for target discovery and identification. The advent of high power lasers operating in the blue-green portion of the visible spectrum (oceanic transmission window) has led to improved experimental illumination systems for underwater imaging. Range-gated and synchronously scanned devices take advantage of the unique temporal and spatial coherence properties of laser radiation, respectively, to overcome the deleterious effects of common volume back scatter.

Design and Evaluation Methods for Underwater Control Systems

Energy Technology Data Exchange (ETDEWEB)

Chi, Lin

1996-12-31

This thesis on underwater control systems is written with the designer in mind, assuming that the reader has some knowledge of control theory. It can be used as a text for undergraduate students and engineers. To help readers better understand the system they will be working with, the thesis is organised in a stepwise way. The reader will gain basic knowledge about underwater operations, equipment and control systems. Then the reader will be able to follow the steps to develop a required control system for an underwater equipment by first understanding the characteristics of the design problem, customer requirement, functional requirement, and possible solution, and then to present a mathematical model of the control problem. Having developed the concept, the thesis guides the reader to develop evaluation criteria and different ways to make the decision. The thesis gives an overview of how to achieve a successful design rather than giving the techniques for detailed control system design. Chapter 1 describes underwater operations and systems. Chapter 2 discusses issues of underwater control systems and control methods. Chapter 3 deals with design method and control systems theory, focusing on human-centered control. Chapter 4 discusses methods used to evaluate and rank products, and chapter 5 applies the methods to an example. 113 refs., 115 figs., 80 tabs.

Design and Evaluation Methods for Underwater Control Systems

Energy Technology Data Exchange (ETDEWEB)

Chi, Lin

1997-12-31

This thesis on underwater control systems is written with the designer in mind, assuming that the reader has some knowledge of control theory. It can be used as a text for undergraduate students and engineers. To help readers better understand the system they will be working with, the thesis is organised in a stepwise way. The reader will gain basic knowledge about underwater operations, equipment and control systems. Then the reader will be able to follow the steps to develop a required control system for an underwater equipment by first understanding the characteristics of the design problem, customer requirement, functional requirement, and possible solution, and then to present a mathematical model of the control problem. Having developed the concept, the thesis guides the reader to develop evaluation criteria and different ways to make the decision. The thesis gives an overview of how to achieve a successful design rather than giving the techniques for detailed control system design. Chapter 1 describes underwater operations and systems. Chapter 2 discusses issues of underwater control systems and control methods. Chapter 3 deals with design method and control systems theory, focusing on human-centered control. Chapter 4 discusses methods used to evaluate and rank products, and chapter 5 applies the methods to an example. 113 refs., 115 figs., 80 tabs.

Construction Method of the Topographical Features Model for Underwater Terrain Navigation

Directory of Open Access Journals (Sweden)

Wang Lihui

2015-09-01

Full Text Available Terrain database is the reference basic for autonomous underwater vehicle (AUV to implement underwater terrain navigation (UTN functions, and is the important part of building topographical features model for UTN. To investigate the feasibility and correlation of a variety of terrain parameters as terrain navigation information metrics, this paper described and analyzed the underwater terrain features and topography parameters calculation method. Proposing a comprehensive evaluation method for terrain navigation information, and constructing an underwater navigation information analysis model, which is associated with topographic features. Simulation results show that the underwater terrain features, are associated with UTN information directly or indirectly, also affect the terrain matching capture probability and the positioning accuracy directly.

New Mix Explosives for Explosive Welding

Science.gov (United States)

Andreevskikh, Leonid

2011-06-01

Suggested and tested were some mix explosives--powder mixtures of a brisant high explosive (HE = RDX, PETN) and an inert diluent (baking soda)--for use in explosive welding. RDX and PETN were selected in view of their high throwing ability and low critical diameter. Since the decomposition of baking soda yields a huge amount of gaseous products, its presence ensures (even at a low HE percentage) a throwing speed that is sufficient for realization of explosive welding, at a reduced brisant action of charge. Mix chargers containing 30-70 wt % HE (the rest baking soda) have been tested experimentally and optimized. For study of possibility to reduce critical diameter of HE mixture, the mixture was prepared where HE crystal sizes did not exceed 10 μm. The tests, which were performed with this HE, revealed that the mixture detonated stably with the velocity D ~ 2 km/s, if the layer thickness was d = 2 mm. The above explosives afford to markedly diminish deformations within the oblique impact zone and thus to carry out explosive welding of hollow items and thin metallic foils.

A PROPOSAL FOR A SUSTAINABLE MODEL BASED UPON UNDERWATER TOURISM RESEARCH IN AYVALIK

Directory of Open Access Journals (Sweden)

A. GÖKDENİZ

2013-03-01

Full Text Available Underwater sports are the activities being done with the aims of witnessing the beauties, hunting, taking photos, the ecology and the archaeology of underwater analysing or finding out the human being’s boundaries by improving the physical and psychological skills of men. The initial aim of this project is to increase the underwater flora and the fauna heritage of Ayvalık and to bring them in tourism. Ayvalık is on the west coast of Turkey. It is getting more and more famous with its underwater richness. Also, to form a new underwater sports centre in order to contribute to the improvement of the region. By providing visual attractiveness, the tourists related to underwater sports will pay attention to Ayvalık and underwater tourism will contribute much to the economy of the region. The aim of this project is to improve the underwater sports which is now a hobby than a sport. In Ayvalık Underwater World study, we dealt with 247 divers and 4 underwater sports club. In this study, we analysed the expectation, satisfaction, demographic and economic level of 247 divers about the services in the region. Interview technique has been used in the study on the 4 underwater sports clubs which are hosting divers. As a conclusion, a report has been prepared in which detailed information and proposals are presented by developing a sustainable marketing model concerned with the underwater sports for those who want to possess information, shareholders of the sector and make analyse about tourism.

Attenuation of shock waves in copper and stainless steel

International Nuclear Information System (INIS)

Harvey, W.B.

1986-06-01

By using shock pins, data were gathered on the trajectories of shock waves in stainless steel (SS-304L) and oxygen-free-high-conductivity copper (OFHC-Cu). Shock pressures were generated in these materials by impacting the appropriate target with thin (approx.1.5 mm) flying plates. The flying plates in these experiments were accelerated to high velocities (approx.4 km/s) by high explosives. Six experiments were conducted, three using SS-304L as the target material and three experiments using OFHC-Cu as the target material. Peak shock pressures generated in the steel experiments were approximately 109, 130, and 147 GPa and in the copper experiments, the peak shock pressures were approximately 111, 132, and 143 GPa. In each experiment, an attenuation of the shock wave by a following release wave was clearly observed. An extensive effort using two characteristic codes (described in this work) to theoretically calculate the attenuation of the shock waves was made. The efficacy of several different constitutive equations to successfully model the experiments was studied by comparing the calculated shock trajectories to the experimental data. Based on such comparisons, the conclusion can be drawn that OFHC-Cu enters a melt phase at about 130 GPa on the principal Hugoniot. There was no sign of phase changes in the stainless-steel experiments. In order to match the observed attenuation of the shock waves in the SS-304L experiments, it was necessary to include strength effects in the calculations. It was found that the values for the parameters in the strength equations were dependent on the equation of state used in the modeling of the experiments. 66 refs., 194 figs., 77 tabs

Attenuation of shock waves in copper and stainless steel

Energy Technology Data Exchange (ETDEWEB)

Harvey, W.B.

1986-06-01

By using shock pins, data were gathered on the trajectories of shock waves in stainless steel (SS-304L) and oxygen-free-high-conductivity copper (OFHC-Cu). Shock pressures were generated in these materials by impacting the appropriate target with thin (approx.1.5 mm) flying plates. The flying plates in these experiments were accelerated to high velocities (approx.4 km/s) by high explosives. Six experiments were conducted, three using SS-304L as the target material and three experiments using OFHC-Cu as the target material. Peak shock pressures generated in the steel experiments were approximately 109, 130, and 147 GPa and in the copper experiments, the peak shock pressures were approximately 111, 132, and 143 GPa. In each experiment, an attenuation of the shock wave by a following release wave was clearly observed. An extensive effort using two characteristic codes (described in this work) to theoretically calculate the attenuation of the shock waves was made. The efficacy of several different constitutive equations to successfully model the experiments was studied by comparing the calculated shock trajectories to the experimental data. Based on such comparisons, the conclusion can be drawn that OFHC-Cu enters a melt phase at about 130 GPa on the principal Hugoniot. There was no sign of phase changes in the stainless-steel experiments. In order to match the observed attenuation of the shock waves in the SS-304L experiments, it was necessary to include strength effects in the calculations. It was found that the values for the parameters in the strength equations were dependent on the equation of state used in the modeling of the experiments. 66 refs., 194 figs., 77 tabs.

Applications of Shock Wave Research to Developments of Therapeutic Devices.

Science.gov (United States)

Takayama, Kazuyoshi

2007-06-01

Underwater shock wave research applied to medicine started in 1980 by exploding micro lead azide pellets in water. Collaboration with urologists in the School of Medicine, Tohoku University at the same time was directed to disintegration of kidney stones by controlling shock waves. We initially proposed a miniature truncated ellipsoidal cavity for generating high-pressures enough to disintegrate the stone but gave up the idea, when encountering the Dornie Systems' invention of an extracorporeal shock wave lithotripter (ESWL). Then we confirmed its effectiveness by using 10 mg silver azide pellets and constructed our own lithotripter, which was officially approved for a clinical use in 1987. Tissue damage during ESWL was attributable to bubble collapse and we convinced it could be done in a controlled fashion. In 1996, we used 160 mJ pulsed Ho:YAG laser beam focusing inside a catheter for shock generation and applied it to the revascularization of cerebral embolism, which is recently expanded to the treatment of pulmonary infarction. Micro water jets discharged in air were so effective to dissect soft tissues preserving small blood vessels. Animal experiments are successfully performed with high frequency water jets driven by an actuator-assisted micro-pump. A metal foil is deformed at high speed by a Q-switched Nd:YAG laser beam loading. We used this technique to project micro-particles or dry drugs attached on its reverse side and extended it to a laser ablation assisted dry drug delivery or DNA introductory system.

Blue-light digital communication in underwater environments utilizing orbital angular momentum

Science.gov (United States)

Baghdady, Joshua; Miller, Keith; Osler, Sean; Morgan, Kaitlyn; Li, Wenzhe; Johnson, Eric; Cochenour, Brandon

2016-05-01

Underwater optical communication has recently become the topic of much investigation as the demands for underwater data transmission have rapidly grown in recent years. The need for reliable, high-speed, secure underwater communication has turned increasingly to blue-light optical solutions. The blue-green visible wavelength window provides an attractive solution to the problem of underwater data transmission thanks to its low attenuation, where traditional RF solutions used in free-space communications collapse. Beginning with GaN laser diodes as the optical source, this work explores the encoding and transmission of digital data across underwater environments of varying turbidities. Given the challenges present in an underwater environment, such as the mechanical and optical turbulences that make proper alignment difficult to maintain, it is desirable to achieve extremely high data rates in order to allow the time window of alignment between the transmitter and receiver to be as small as possible. In this paper, work is done to increase underwater data rates through the use of orbital angular momentum. Results are shown for a range of data rates across a variety of channel types ranging in turbidity from that of a clear ocean to a dirty harbor.

Underwater 3D Surface Measurement Using Fringe Projection Based Scanning Devices.

Science.gov (United States)

Bräuer-Burchardt, Christian; Heinze, Matthias; Schmidt, Ingo; Kühmstedt, Peter; Notni, Gunther

2015-12-23

In this work we show the principle of optical 3D surface measurements based on the fringe projection technique for underwater applications. The challenges of underwater use of this technique are shown and discussed in comparison with the classical application. We describe an extended camera model which takes refraction effects into account as well as a proposal of an effective, low-effort calibration procedure for underwater optical stereo scanners. This calibration technique combines a classical air calibration based on the pinhole model with ray-based modeling and requires only a few underwater recordings of an object of known length and a planar surface. We demonstrate a new underwater 3D scanning device based on the fringe projection technique. It has a weight of about 10 kg and the maximal water depth for application of the scanner is 40 m. It covers an underwater measurement volume of 250 mm × 200 mm × 120 mm. The surface of the measurement objects is captured with a lateral resolution of 150 μm in a third of a second. Calibration evaluation results are presented and examples of first underwater measurements are given.

78 FR 64246 - Commerce in Explosives; List of Explosives Materials

Science.gov (United States)

2013-10-28

..., including non-cap sensitive slurry and water gel explosives. Blasting caps. Blasting gelatin. Blasting.... Explosive conitrates. Explosive gelatins. Explosive liquids. Explosive mixtures containing oxygen-releasing... powder. [[Page 64247

Single underwater image enhancement based on color cast removal and visibility restoration

Science.gov (United States)

Li, Chongyi; Guo, Jichang; Wang, Bo; Cong, Runmin; Zhang, Yan; Wang, Jian

2016-05-01

Images taken under underwater condition usually have color cast and serious loss of contrast and visibility. Degraded underwater images are inconvenient for observation and analysis. In order to address these problems, an underwater image-enhancement method is proposed. A simple yet effective underwater image color cast removal algorithm is first presented based on the optimization theory. Then, based on the minimum information loss principle and inherent relationship of medium transmission maps of three color channels in an underwater image, an effective visibility restoration algorithm is proposed to recover visibility, contrast, and natural appearance of degraded underwater images. To evaluate the performance of the proposed method, qualitative comparison, quantitative comparison, and color accuracy test are conducted. Experimental results demonstrate that the proposed method can effectively remove color cast, improve contrast and visibility, and recover natural appearance of degraded underwater images. Additionally, the proposed method is comparable to and even better than several state-of-the-art methods.

Effects of neutrino trapping on supernova explosions

International Nuclear Information System (INIS)

Takahara, Mariko; Sato, Katsuhiko

1982-01-01

Effects of neutrino trapping on the mass ejection from the stellar cores are investigated with the aid of a simplified equation of state under the assumption of adiabatic collapse. It is found that mass ejection becomes violent only if the ratio of the trapped leptons to baryons, Y sub(L), lies in an appropriate range. If the value of Y sub(L) lies out of this range, mass ejection is difficult. It is also shown that as the thermal stiffness of the shocked matter increases, the range necessary for the violent mass ejection becomes wider. Possibilities of supernova explosion are discussed on the basis of these results. (author)

Study of archaeological underwater finds: deterioration and conservation

Science.gov (United States)

Crisci, G. M.; La Russa, M. F.; Macchione, M.; Malagodi, M.; Palermo, A. M.; Ruffolo, S. A.

2010-09-01

This study is aimed at an assessment of the methodologies, instruments and new applications for underwater archaeology. Research focused on study of the various kinds of degradation affecting underwater finds and stone materials aged in underwater environment, efficiency evaluation of various surface cleaning methods and study and mixing of protective products with consolidating resins and antimicrobial biocides to be applied to restored underwater finds. Transmitted light optical microscopy and scanning electron microscopy (SEM) were used to study surface biofilms and the interactions with samples of different stone materials such as brick, marble and granite immersed in the submarine archaeological area of Crotone (South of Italy). Surface cleaning tests were performed with application of ion exchange resins, EDTA, hydrogen peroxide and ultrasound techniques. Capillary water absorption, simulated solar ageing and colourimetric measurements were carried out to evaluate hydrophobic and consolidant properties; to assess biocidal efficacy, heterotrophic micro-organisms ( Aspergillus niger) were inoculated on agar plates and growth inhibition was measured.

Efficient Weibull channel model for salinity induced turbulent underwater wireless optical communications

KAUST Repository

Oubei, Hassan M.; Zedini, Emna; Elafandy, Rami T.; Kammoun, Abla; Ng, Tien Khee; Alouini, Mohamed-Slim; Ooi, Boon S.

2017-01-01

Recent advances in underwater wireless optical communications necessitate a better understanding of the underwater channel. We propose the Weibull model to characterize the fading of salinity induced turbulent underwater wireless optical channels

Underwater laser cutting of metallic structures

International Nuclear Information System (INIS)

Alfille, J.P.; Schildknecht, J.; Ramaswami, V.S.

1993-01-01

In the frame of an european contract, the feasibility of the underwater cutting with a CO 2 laser power is studied. The aim of this work is the dismantling metallic structures of reactors pools. The paper analyzes the general concept of the experimental device, the underwater cutting head, the experimenting vessel, examples of cuttings in dismantling situation with a 500 W CO 2 laser, and examples of cuttings with a 5 kW CO 2 laser. (author). 2 refs., 9 figs., 2 tabs

Digital sonar design in underwater acoustics principles and applications

CERN Document Server

Li, Qihu

2012-01-01

"Digital Sonar Design in Underwater Acoustics Principles and Applications" provides comprehensive and up-to-date coverage of research on sonar design, including the basic theory and techniques of digital signal processing, basic concept of information theory, ocean acoustics, underwater acoustic signal propagation theory, and underwater signal processing theory. This book discusses the general design procedure and approaches to implementation, the design method, system simulation theory and techniques, sonar tests in the laboratory, lake and sea, and practical validation criteria and methods for digital sonar design. It is intended for researchers in the fields of underwater signal processing and sonar design, and also for navy officers and ocean explorers. Qihu Li is a professor at the Institute of Acoustics, Chinese Academy of Sciences, and an academician of the Chinese Academy of Sciences.

Underwater wireless optical communications: From system-level demonstrations to channel modelling

KAUST Repository

Oubei, Hassan M.

2018-01-09

In this paper, we discuss about recent experimental advances in underwater wireless optical communications (UWOC) over various underwater channel water types using different modulation schemes as well as modelling and describing the statistical properties of turbulence-induced fading in underwater wireless optical channels using laser beam intensity fluctuations measurements.

Development of a non-explosive release actuator using shape memory alloy wire.

Science.gov (United States)

Yoo, Young Ik; Jeong, Ju Won; Lim, Jae Hyuk; Kim, Kyung-Won; Hwang, Do-Soon; Lee, Jung Ju

2013-01-01

We have developed a newly designed non-explosive release actuator that can replace currently used release devices. The release mechanism is based on a separation mechanism, which relies on segmented nuts and a shape memory alloy (SMA) wire trigger. A quite fast and simple trigger operation is made possible through the use of SMA wire. This actuator is designed to allow a high preload with low levels of shock for the solar arrays of medium-size satellites. After actuation, the proposed device can be easily and instantly reset. Neither replacement, nor refurbishment of any components is necessary. According to the results of a performance test, the release time, preload capacity, and maximum shock level are 50 ms, 15 kN, and 350 G, respectively. In order to increase the reliability of the actuator, more than ten sets of performance tests are conducted. In addition, the proposed release actuator is tested under thermal vacuum and extreme vibration environments. No degradation or damage was observed during the two environment tests, and the release actuator was able to operate successfully. Considering the test results as a whole, we conclude that the proposed non-explosive release actuator can be applied reliably to intermediate-size satellites to replace existing release systems.

Electric gun: a new method for generating shock pressures in excess of 1 TPa

International Nuclear Information System (INIS)

Steinberg, D.; Chau, H.; Dittbenner, G.; Weingart, R.

1978-01-01

By combining the electrically-driven, flying-plate, high-explosive initiator with well-known gas-gun technology, a novel method of generating and measuring shock pressures greater than 1 TPa has been developed. Called the electric gun, this system is competitive with laser or nuclear-driven, shock-wave, equation-of-state experiments in the 1 to 5 TPa range. Compared to those other methods, it has the advantage of simplicity, high precision, and low cost. In addition, its small size and low total energy allow it to be easily contained for experiments with toxic materials

WODA Technical Guidance on Underwater Sound from Dredging.

Science.gov (United States)

Thomsen, Frank; Borsani, Fabrizio; Clarke, Douglas; de Jong, Christ; de Wit, Pim; Goethals, Fredrik; Holtkamp, Martine; Martin, Elena San; Spadaro, Philip; van Raalte, Gerard; Victor, George Yesu Vedha; Jensen, Anders

2016-01-01

The World Organization of Dredging Associations (WODA) has identified underwater sound as an environmental issue that needs further consideration. A WODA Expert Group on Underwater Sound (WEGUS) prepared a guidance paper in 2013 on dredging sound, including a summary of potential impacts on aquatic biota and advice on underwater sound monitoring procedures. The paper follows a risk-based approach and provides guidance for standardization of acoustic terminology and methods for data collection and analysis. Furthermore, the literature on dredging-related sounds and the effects of dredging sounds on marine life is surveyed and guidance on the management of dredging-related sound risks is provided.

Communication and cooperation in underwater acoustic networks

Science.gov (United States)

Yerramalli, Srinivas

In this thesis, we present a study of several problems related to underwater point to point communications and network formation. We explore techniques to improve the achievable data rate on a point to point link using better physical layer techniques and then study sensor cooperation which improves the throughput and reliability in an underwater network. Robust point-to-point communications in underwater networks has become increasingly critical in several military and civilian applications related to underwater communications. We present several physical layer signaling and detection techniques tailored to the underwater channel model to improve the reliability of data detection. First, a simplified underwater channel model in which the time scale distortion on each path is assumed to be the same (single scale channel model in contrast to a more general multi scale model). A novel technique, which exploits the nature of OFDM signaling and the time scale distortion, called Partial FFT Demodulation is derived. It is observed that this new technique has some unique interference suppression properties and performs better than traditional equalizers in several scenarios of interest. Next, we consider the multi scale model for the underwater channel and assume that single scale processing is performed at the receiver. We then derive optimized front end pre-processing techniques to reduce the interference caused during single scale processing of signals transmitted on a multi-scale channel. We then propose an improvised channel estimation technique using dictionary optimization methods for compressive sensing and show that significant performance gains can be obtained using this technique. In the next part of this thesis, we consider the problem of sensor node cooperation among rational nodes whose objective is to improve their individual data rates. We first consider the problem of transmitter cooperation in a multiple access channel and investigate the stability of

Survivability design for a hybrid underwater vehicle

Energy Technology Data Exchange (ETDEWEB)

Wang, Biao; Wu, Chao; Li, Xiang; Zhao, Qingkai; Ge, Tong [State Key Lab of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

2015-03-10

A novel hybrid underwater robotic vehicle (HROV) capable of working to the full ocean depth has been developed. The battery powered vehicle operates in two modes: operate as an untethered autonomous vehicle in autonomous underwater vehicle (AUV) mode and operate under remote control connected to the surface vessel by a lightweight, fiber optic tether in remotely operated vehicle (ROV) mode. Considering the hazardous underwater environment at the limiting depth and the hybrid operating modes, survivability has been placed on an equal level with the other design attributes of the HROV since the beginning of the project. This paper reports the survivability design elements for the HROV including basic vehicle design of integrated navigation and integrated communication, emergency recovery strategy, distributed architecture, redundant bus, dual battery package, emergency jettison system and self-repairing control system.

Survivability design for a hybrid underwater vehicle

International Nuclear Information System (INIS)

Wang, Biao; Wu, Chao; Li, Xiang; Zhao, Qingkai; Ge, Tong

2015-01-01

A novel hybrid underwater robotic vehicle (HROV) capable of working to the full ocean depth has been developed. The battery powered vehicle operates in two modes: operate as an untethered autonomous vehicle in autonomous underwater vehicle (AUV) mode and operate under remote control connected to the surface vessel by a lightweight, fiber optic tether in remotely operated vehicle (ROV) mode. Considering the hazardous underwater environment at the limiting depth and the hybrid operating modes, survivability has been placed on an equal level with the other design attributes of the HROV since the beginning of the project. This paper reports the survivability design elements for the HROV including basic vehicle design of integrated navigation and integrated communication, emergency recovery strategy, distributed architecture, redundant bus, dual battery package, emergency jettison system and self-repairing control system

Feasibility of in situ beta ray measurements in underwater environment.

Science.gov (United States)

Park, Hye Min; Park, Ki Hyun; Kang, Sung Won; Joo, Koan Sik

2017-09-01

We describe an attempt at the development of an in situ detector for beta ray measurements in underwater environment. The prototype of the in situ detector is based on a CaF2: Eu scintillator using crystal light guide and Si photomultiplier. Tests were conducted using various reference sources for evaluating the linearity and stability of the detector in underwater environment. The system is simple and stable for long-term monitoring, and consumes low power. We show here an effective detection distance of 7 mm and a 2.273 MeV end-point energy spectrum of 90 Sr/ 90 Y when using the system underwater. The results demonstrate the feasibility of in situ beta ray measurements in underwater environment and can be applied for designing an in situ detector for radioactivity measurement in underwater environment. The in situ detector can also have other applications such as installation on the marine monitoring platform and quantitative analysis of radionuclides. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optimization of an Intelligent Controller for an Unmanned Underwater Vehicle

Directory of Open Access Journals (Sweden)

M. Fauzi Nor Shah

2011-08-01

Full Text Available Underwater environment poses a difficult challenge for autonomous underwater navigation. A standard problem of underwater vehicles is to maintain it position at a certain depth in order to perform desired operations. An effective controller is required for this purpose and hence the design of a depth controller for an unmanned underwater vehicle is described in this paper. The control algorithm is simulated by using the marine guidance navigation and control simulator. The project shows a radial basis function metamodel can be used to tune the scaling factors of a fuzzy logic controller. By using offline optimization approach, a comparison between genetic algorithm and metamodeling has been done to minimize the integral square error between the set point and the measured depth of the underwater vehicle. The results showed that it is possible to obtain a reasonably good error using metamodeling approach in much a shorter time compared to the genetic algorithm approach.

Comparative study of the expansion dynamics of laser-driven plasma and shock wave in in-air and underwater ablation regimes

Science.gov (United States)

Nguyen, Thao T. P.; Tanabe, Rie; Ito, Yoshiro

2018-03-01

We compared the expansion characteristics of the plasma plumes and shock waves generated in laser-induced shock process between the two ablation regimes: in air and under water. The observation was made from the initial moment when the laser pulse hit the target until 1.5 μs. The shock processes were driven by focusing a single laser pulse (1064 nm, FWHM = 13 ns) onto the surface of epoxy-resin blocks using a 40-mm focal length lens. The estimated laser intensity at the target plane is approximate to 9 ×109Wcm-2 . We used the fast-imaging technique to observe the expansion of the plasma plume and a custom-designed time-resolved photoelasticity imaging technique to observe the propagation of shock waves with the time resolution of nanoseconds. We found that at the same intensity of the laser beam, the plasma expansion during the laser pulse follows different mechanisms: the plasma plume that grows in air follows a radiation-wave model while a detonation-wave model can explain the expansion of the plasma plume induced in water. The ideal blast wave theory can be used to predict the decay of the shock wave in air but is not appropriate to describe the decay of the shock wave induced under water.

A bio-inspired electrocommunication system for small underwater robots.

Science.gov (United States)

Wang, Wei; Liu, Jindong; Xie, Guangming; Wen, Li; Zhang, Jianwei

2017-03-29

Weakly electric fishes (Gymnotid and Mormyrid) use an electric field to communicate efficiently (termed electrocommunication) in the turbid waters of confined spaces where other communication modalities fail. Inspired by this biological phenomenon, we design an artificial electrocommunication system for small underwater robots and explore the capabilities of such an underwater robotic communication system. An analytical model for electrocommunication is derived to predict the effect of the key parameters such as electrode distance and emitter current of the system on the communication performance. According to this model, a low-dissipation, and small-sized electrocommunication system is proposed and integrated into a small robotic fish. We characterize the communication performance of the robot in still water, flowing water, water with obstacles and natural water conditions. The results show that underwater robots are able to communicate electrically at a speed of around 1 k baud within about 3 m with a low power consumption (less than 1 W). In addition, we demonstrate that two leader-follower robots successfully achieve motion synchronization through electrocommunication in the three-dimensional underwater space, indicating that this bio-inspired electrocommunication system is a promising setup for the interaction of small underwater robots.

UTOFIA: an underwater time-of-flight image acquisition system

Science.gov (United States)

Driewer, Adrian; Abrosimov, Igor; Alexander, Jonathan; Benger, Marc; O'Farrell, Marion; Haugholt, Karl Henrik; Softley, Chris; Thielemann, Jens T.; Thorstensen, Jostein; Yates, Chris

2017-10-01

In this article the development of a newly designed Time-of-Flight (ToF) image sensor for underwater applications is described. The sensor is developed as part of the project UTOFIA (underwater time-of-flight image acquisition) funded by the EU within the Horizon 2020 framework. This project aims to develop a camera based on range gating that extends the visible range compared to conventional cameras by a factor of 2 to 3 and delivers real-time range information by means of a 3D video stream. The principle of underwater range gating as well as the concept of the image sensor are presented. Based on measurements on a test image sensor a pixel structure that suits best to the requirements has been selected. Within an extensive characterization underwater the capability of distance measurements in turbid environments is demonstrated.

SN 2008D: A WOLF-RAYET EXPLOSION THROUGH A THICK WIND

International Nuclear Information System (INIS)

Svirski, Gilad; Nakar, Ehud

2014-01-01

Supernova (SN) 2008D/XRT 080109 is considered to be the only direct detection of a shock breakout from a regular SN to date. While a breakout interpretation was favored by several papers, inconsistencies remain between the observations and current SN shock breakout theory. Most notably, the duration of the luminous X-ray pulse is considerably longer than expected for a spherical breakout through the surface of a type Ibc SN progenitor, and the X-ray radiation features, mainly its flat spectrum and its luminosity evolution, are enigmatic. We apply a recently developed theoretical model for the observed radiation from a Wolf-Rayet SN exploding through a thick wind and show that it naturally explains all of the observed features of SN 2008D X-ray emission, including the energetics, the spectrum, and the detailed luminosity evolution. We find that the inferred progenitor and SN parameters are typical for an exploding Wolf-Rayet. A comparison of the wind density found at the breakout radius and the density at much larger radii, as inferred by late radio observations, suggests an enhanced mass-loss rate taking effect about 10 days prior to the SN explosion. This finding joins accumulating evidence for a possible late phase in the stellar evolution of massive stars, involving vigorous mass loss a short time before the SN explosion

SN 2008D: A WOLF-RAYET EXPLOSION THROUGH A THICK WIND

Energy Technology Data Exchange (ETDEWEB)

Svirski, Gilad; Nakar, Ehud [Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel)

2014-06-10

Supernova (SN) 2008D/XRT 080109 is considered to be the only direct detection of a shock breakout from a regular SN to date. While a breakout interpretation was favored by several papers, inconsistencies remain between the observations and current SN shock breakout theory. Most notably, the duration of the luminous X-ray pulse is considerably longer than expected for a spherical breakout through the surface of a type Ibc SN progenitor, and the X-ray radiation features, mainly its flat spectrum and its luminosity evolution, are enigmatic. We apply a recently developed theoretical model for the observed radiation from a Wolf-Rayet SN exploding through a thick wind and show that it naturally explains all of the observed features of SN 2008D X-ray emission, including the energetics, the spectrum, and the detailed luminosity evolution. We find that the inferred progenitor and SN parameters are typical for an exploding Wolf-Rayet. A comparison of the wind density found at the breakout radius and the density at much larger radii, as inferred by late radio observations, suggests an enhanced mass-loss rate taking effect about 10 days prior to the SN explosion. This finding joins accumulating evidence for a possible late phase in the stellar evolution of massive stars, involving vigorous mass loss a short time before the SN explosion.

Underwater photogrammetry successful in Spain and France

International Nuclear Information System (INIS)

Anon.

1988-01-01

Underwater photogrammetry has been used to measure distortions in fuel assembly alignment pins in the upper internals of the Almarez and Dampierre PWRs. Photogrammetry is a three-dimensional precision measurement method using photographic techniques for the on-site measurement phase. On the strength of the operations at the two PWRs, underwater photogrammetry is now considered as a practical and effective technique for dimensional inspection at nuclear plants. (U.K.)

OPTICAL correlation identification technology applied in underwater laser imaging target identification

Science.gov (United States)

Yao, Guang-tao; Zhang, Xiao-hui; Ge, Wei-long

2012-01-01

The underwater laser imaging detection is an effective method of detecting short distance target underwater as an important complement of sonar detection. With the development of underwater laser imaging technology and underwater vehicle technology, the underwater automatic target identification has gotten more and more attention, and is a research difficulty in the area of underwater optical imaging information processing. Today, underwater automatic target identification based on optical imaging is usually realized with the method of digital circuit software programming. The algorithm realization and control of this method is very flexible. However, the optical imaging information is 2D image even 3D image, the amount of imaging processing information is abundant, so the electronic hardware with pure digital algorithm will need long identification time and is hard to meet the demands of real-time identification. If adopt computer parallel processing, the identification speed can be improved, but it will increase complexity, size and power consumption. This paper attempts to apply optical correlation identification technology to realize underwater automatic target identification. The optics correlation identification technology utilizes the Fourier transform characteristic of Fourier lens which can accomplish Fourier transform of image information in the level of nanosecond, and optical space interconnection calculation has the features of parallel, high speed, large capacity and high resolution, combines the flexibility of calculation and control of digital circuit method to realize optoelectronic hybrid identification mode. We reduce theoretical formulation of correlation identification and analyze the principle of optical correlation identification, and write MATLAB simulation program. We adopt single frame image obtained in underwater range gating laser imaging to identify, and through identifying and locating the different positions of target, we can improve

The Universal Role of Tubulence in the Propagation of Strong Shocks and Detonation Waves

Science.gov (United States)

Lee, John H.

2001-06-01

The passage of a strong shock wave usually results in irreversible physical and chemical changes in the medium. If the chemical reactions are sufficiently exothermic, the shock wave can be self-propagating, i.e., sustained by the chemical energy release via the expansion work of the reaction products. Although shocks and detonations can be globally stable and propagate at constant velocities (in the direction of motion), their structure may be highly unstable and exhibit large hydrodynamic fluctuations, i.e., turbulence. Recent investigations on plastic deformation of polycrystalline material behind shock waves have revealed particle velocity dispersion at the mesoscopic level, a result of vortical rotational motion similar to that of turbulent fluid flows at high Reynolds number.1 Strong ionizing shocks in noble gases2, as well as dissociating shock waves in carbon dioxide,3 also demonstrate a turbulent density fluctuation in the non-equilibrium shock transition zone. Perhaps the most thoroughly investigated unstable structure is that of detonation waves in gaseous explosives.4 Detonation waves in liquid explosives such as nitromethane also take on similar unstable structure as gaseous detonations.5 There are also indications that detonations in solid explosives have a similar unsteady structure under certain conditions. Thus, it appears that it is more of a rule than an exception that the structure of strong shocks and detonations are unstable and exhibit turbulent-like fluctuations as improved diagnostics now permit us to look more closely at the meso- and micro-levels. Increasing attention is now devoted to the understanding of the shock waves at the micro-scale level in recent years. This is motivated by the need to formulate physical and chemical models that contain the correct physics capable of describing quantitatively the shock transition process. It should be noted that, in spite of its unstable 3-D structure, the steady 1-D conservation laws (in the

Deep Learning Methods for Underwater Target Feature Extraction and Recognition

Directory of Open Access Journals (Sweden)

Gang Hu

2018-01-01

Full Text Available The classification and recognition technology of underwater acoustic signal were always an important research content in the field of underwater acoustic signal processing. Currently, wavelet transform, Hilbert-Huang transform, and Mel frequency cepstral coefficients are used as a method of underwater acoustic signal feature extraction. In this paper, a method for feature extraction and identification of underwater noise data based on CNN and ELM is proposed. An automatic feature extraction method of underwater acoustic signals is proposed using depth convolution network. An underwater target recognition classifier is based on extreme learning machine. Although convolution neural networks can execute both feature extraction and classification, their function mainly relies on a full connection layer, which is trained by gradient descent-based; the generalization ability is limited and suboptimal, so an extreme learning machine (ELM was used in classification stage. Firstly, CNN learns deep and robust features, followed by the removing of the fully connected layers. Then ELM fed with the CNN features is used as the classifier to conduct an excellent classification. Experiments on the actual data set of civil ships obtained 93.04% recognition rate; compared to the traditional Mel frequency cepstral coefficients and Hilbert-Huang feature, recognition rate greatly improved.

A hybrid formulation for the numerical simulation of condensed phase explosives

Science.gov (United States)

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.

Detonation of high explosives in Lagrangian hydrodynamic codes using the programmed burn technique

International Nuclear Information System (INIS)

Berger, M.E.

1975-09-01

Two initiation methods were developed for improving the programmed burn technique for detonation of high explosives in smeared-shock Lagrangian hydrodynamic codes. The methods are verified by comparing the improved programmed burn with existing solutions in one-dimensional plane, converging, and diverging geometries. Deficiencies in the standard programmed burn are described. One of the initiation methods has been determined to be better for inclusion in production hydrodynamic codes

Set-up for steam generator tube bundle washing after explosion expanding the tubes

International Nuclear Information System (INIS)

Osipov, S.I.; Kal'nin, A.Ya.; Mazanenko, M.F.

1985-01-01

Set-up for steam generator tube bundle washing after the explosion expanding of tubes is described. Washing is accomplished by distillate. Steam is added to distillate for heating, and compersed air for preventing hydraulic shock. The set-up is equiped by control equipment. Set-up performances are presented. Time for one steam generator washing constitutes 8-12 h. High economic efficiency is realized due to the set-up introduction

Primary explosives

Energy Technology Data Exchange (ETDEWEB)

Matyas, Robert; Pachman, Jiri [Pardubice Univ. (Czech Republic). Faculty of Chemical Technology

2013-06-01

The first chapter provides background such as the basics of initiation and differences between requirements on primary explosives used in detonators and igniters. The authors then clarify the influence of physical characteristics on explosive properties, focusing on those properties required for primary explosives. Furthermore, the issue of sensitivity is discussed. All the chapters on particular groups of primary explosives are structured in the same way, including introduction, physical and chemical properties, explosive properties, preparation and documented use.

Shock wave science and technology reference library. Vol. 4. Heterogeneous detonation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Fan (ed.) [Defence Research and Development Canada, Suffield, AB (Canada)

2009-07-01

This book, as a volume of the Shock Wave Science and Technology Reference Library, is primarily concerned with detonation waves or compression shock waves in reactive heterogeneous media, including mixtures of solid, liquid and gas phases. The topics involve a variety of energy release and control processes in such media - a contemporary research field that has found wide applications in propulsion and power, hazard prevention as well as military engineering. The six extensive chapters contained in this volume are: - Spray Detonation (SB Murray and PA Thibault) - Detonation of Gas-Particle Flow (F Zhang) - Slurry Detonation (DL Frost and F Zhang) - Detonation of Metalized Composite Explosives (MF Gogulya and MA Brazhnikov) - Shock-Induced Solid-Solid Reactions and Detonations (YA Gordopolov, SS Batsanov, and VS Trofimov) - Shock Ignition of Particles (SM Frolov and AV Fedorov). Each chapter is self-contained and can be read independently of the others, though, they are thematically interrelated. They offer a timely reference, for graduate students as well as professional scientists and engineers, by laying out the foundations and discussing the latest developments including yet unresolved challenging problems. (orig.)

Underwater video enhancement using multi-camera super-resolution

Science.gov (United States)

Quevedo, E.; Delory, E.; Callicó, G. M.; Tobajas, F.; Sarmiento, R.

2017-12-01

Image spatial resolution is critical in several fields such as medicine, communications or satellite, and underwater applications. While a large variety of techniques for image restoration and enhancement has been proposed in the literature, this paper focuses on a novel Super-Resolution fusion algorithm based on a Multi-Camera environment that permits to enhance the quality of underwater video sequences without significantly increasing computation. In order to compare the quality enhancement, two objective quality metrics have been used: PSNR (Peak Signal-to-Noise Ratio) and the SSIM (Structural SIMilarity) index. Results have shown that the proposed method enhances the objective quality of several underwater sequences, avoiding the appearance of undesirable artifacts, with respect to basic fusion Super-Resolution algorithms.

Restoration and Enhancement of Underwater Images Based on Bright Channel Prior

Directory of Open Access Journals (Sweden)

Yakun Gao

2016-01-01

Full Text Available This paper proposed a new method of underwater images restoration and enhancement which was inspired by the dark channel prior in image dehazing field. Firstly, we proposed the bright channel prior of underwater environment. By estimating and rectifying the bright channel image, estimating the atmospheric light, and estimating and refining the transmittance image, eventually underwater images were restored. Secondly, in order to rectify the color distortion, the restoration images were equalized by using the deduced histogram equalization. The experiment results showed that the proposed method could enhance the quality of underwater images effectively.