Simulation of jet blast effect on landing aircraft

DOT National Transportation Integrated Search

2001-01-01

Presents a model to measure the effects of various kinds and sizes of jet blast from an airplane that is taking off on a path at right angle to and traveling away from a jet that is landing. With increasingly powerful engines and growing capacity and...

Modelling the combustion of charcoal in a model blast furnace

NASA Astrophysics Data System (ADS)

Shen, Yansong; Shiozawa, Tomo; Yu, Aibing; Austin, Peter

2013-07-01

The pulverized charcoal (PCH) combustion in ironmaking blast furnaces is abstracting remarkable attention due to various benefits such as lowering CO2 emission. In this study, a three-dimensional CFD model is used to simulate the flow and thermo-chemical behaviours in this process. The model is validated against the experimental results from a pilot-scale combustion test rig for a range of conditions. The typical flow and thermo-chemical phenomena is simulated. The effect of charcoal type, i.e. VM content is examined, showing that the burnout increases with VM content in a linear relationship. This model provides an effective way for designing and optimizing PCH operation in blast furnace practice.

Numerical Simulations of Near-Field Blast Effects using Kinetic Plates

NASA Astrophysics Data System (ADS)

Neuscamman, Stephanie; Manner, Virginia; Brown, Geoffrey; Glascoe, Lee

2013-06-01

Numerical simulations using two hydrocodes were compared to near-field measurements of blast impulse associated with ideal and non-ideal explosives to gain insight into testing results and predict untested configurations. The recently developed kinetic plate test was designed to measure blast impulse in the near-field by firing spherical charges in close range from steel plates and probing plate acceleration using laser velocimetry. Plate velocities for ideal, non-ideal and aluminized explosives tests were modeled using a three dimensional hydrocode. The effects of inert additives in the explosive formulation were modeled using a 1-D hydrocode with multiphase flow capability using Lagrangian particles. The relative effect of particle impact on the plate compared to the blast wave impulse is determined and modeling is compared to free field pressure results. This work is performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This is abstract LLNL-ABS-622152.

Large blast and thermal simulator advanced concept driver design by computational fluid dynamics. Final report, 1987-1989

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

Opalka, K.O.

1989-08-01

The construction of a large test facility has been proposed for simulating the blast and thermal environment resulting from nuclear explosions. This facility would be used to test the survivability and vulnerability of military equipment such as trucks, tanks, and helicopters in a simulated thermal and blast environment, and to perform research into nuclear blast phenomenology. The proposed advanced design concepts, heating of driver gas and fast-acting throat valves for wave shaping, are described and the results of CFD studies to advance these new technical concepts fro simulating decaying blast waves are reported.

Modelling the Source of Blasting for the Numerical Simulation of Blast-Induced Ground Vibrations: A Review

NASA Astrophysics Data System (ADS)

Ainalis, Daniel; Kaufmann, Olivier; Tshibangu, Jean-Pierre; Verlinden, Olivier; Kouroussis, Georges

2017-01-01

The mining and construction industries have long been faced with considerable attention and criticism in regard to the effects of blasting. The generation of ground vibrations is one of the most significant factors associated with blasting and is becoming increasingly important as mining sites are now regularly located near urban areas. This is of concern to not only the operators of the mine but also residents. Mining sites are subjected to an inevitable compromise: a production blast is designed to fragment the utmost amount of rock possible; however, any increase in the blast can generate ground vibrations which can propagate great distances and cause structural damage or discomfort to residents in surrounding urban areas. To accurately predict the propagation of ground vibrations near these sensitive areas, the blasting process and surrounding environment must be characterised and understood. As an initial step, an accurate model of the source of blast-induced vibrations is required. This paper presents a comprehensive review of the approaches to model the blasting source in order to critically evaluate developments in the field. An overview of the blasting process and description of the various factors which influence the blast performance and subsequent ground vibrations are also presented. Several approaches to analytically model explosives are discussed. Ground vibration prediction methods focused on seed waveform and charge weight scaling techniques are presented. Finally, numerical simulations of the blasting source are discussed, including methods to estimate blasthole wall pressure time-history, and hydrodynamic codes.

Low-cost blast wave generator for studies of hearing loss and brain injury: blast wave effects in closed spaces.

PubMed

Newman, Andrew J; Hayes, Sarah H; Rao, Abhiram S; Allman, Brian L; Manohar, Senthilvelan; Ding, Dalian; Stolzberg, Daniel; Lobarinas, Edward; Mollendorf, Joseph C; Salvi, Richard

2015-03-15

Military personnel and civilians living in areas of armed conflict have increased risk of exposure to blast overpressures that can cause significant hearing loss and/or brain injury. The equipment used to simulate comparable blast overpressures in animal models within laboratory settings is typically very large and prohibitively expensive. To overcome the fiscal and space limitations introduced by previously reported blast wave generators, we developed a compact, low-cost blast wave generator to investigate the effects of blast exposures on the auditory system and brain. The blast wave generator was constructed largely from off the shelf components, and reliably produced blasts with peak sound pressures of up to 198dB SPL (159.3kPa) that were qualitatively similar to those produced from muzzle blasts or explosions. Exposure of adult rats to 3 blasts of 188dB peak SPL (50.4kPa) resulted in significant loss of cochlear hair cells, reduced outer hair cell function and a decrease in neurogenesis in the hippocampus. Existing blast wave generators are typically large, expensive, and are not commercially available. The blast wave generator reported here provides a low-cost method of generating blast waves in a typical laboratory setting. This compact blast wave generator provides scientists with a low cost device for investigating the biological mechanisms involved in blast wave injury to the rodent cochlea and brain that may model many of the damaging effects sustained by military personnel and civilians exposed to intense blasts. Copyright © 2015 Elsevier B.V. All rights reserved.

Low-Cost Blast Wave Generator for Studies of Hearing Loss and Brain Injury: Blast Wave Effects in Closed Spaces

PubMed Central

Newman, Andrew J.; Hayes, Sarah H.; Rao, Abhiram S.; Allman, Brian L.; Manohar, Senthilvelan; Ding, Dalian; Stolzberg, Daniel; Lobarinas, Edward; Mollendorf, Joseph C.; Salvi, Richard

2015-01-01

Background Military personnel and civilians living in areas of armed conflict have increased risk of exposure to blast overpressures that can cause significant hearing loss and/or brain injury. The equipment used to simulate comparable blast overpressures in animal models within laboratory settings is typically very large and prohibitively expensive. New Method To overcome the fiscal and space limitations introduced by previously reported blast wave generators, we developed a compact, low-cost blast wave generator to investigate the effects of blast exposures on the auditory system and brain. Results The blast wave generator was constructed largely from off the shelf components, and reliably produced blasts with peak sound pressures of up to 198 dB SPL (159.3 kPa) that were qualitatively similar to those produced from muzzle blasts or explosions. Exposure of adult rats to 3 blasts of 188 dB peak SPL (50.4 kPa) resulted in significant loss of cochlear hair cells, reduced outer hair cell function and a decrease in neurogenesis in the hippocampus. Comparison to existing methods Existing blast wave generators are typically large, expensive, and are not commercially available. The blast wave generator reported here provides a low-cost method of generating blast waves in a typical laboratory setting. Conclusions This compact blast wave generator provides scientists with a low cost device for investigating the biological mechanisms involved in blast wave injury to the rodent cochlea and brain that may model many of the damaging effects sustained by military personnel and civilians exposed to intense blasts. PMID:25597910

Full-scale testing and numerical modeling of a multistory masonry structure subjected to internal blast loading

NASA Astrophysics Data System (ADS)

Zapata, Brian Jarvis

As military and diplomatic representatives of the United States are deployed throughout the world, they must frequently make use of local, existing facilities; it is inevitable that some of these will be load bearing unreinforced masonry (URM) structures. Although generally suitable for conventional design loads, load bearing URM presents a unique hazard, with respect to collapse, when exposed to blast loading. There is therefore a need to study the blast resistance of load bearing URM construction in order to better protect US citizens assigned to dangerous locales. To address this, the Department of Civil and Environmental Engineering at the University of North Carolina at Charlotte conducted three blast tests inside a decommissioned, coal-fired, power plant prior to its scheduled demolition. The power plant's walls were constructed of URM and provided an excellent opportunity to study the response of URM walls in-situ. Post-test analytical studies investigated the ability of existing blast load prediction methodologies to model the case of a cylindrical charge with a low height of burst. It was found that even for the relatively simple blast chamber geometries of these tests, simplified analysis methods predicted blast impulses with an average net error of 22%. The study suggested that existing simplified analysis methods would benefit from additional development to better predict blast loads from cylinders detonated near the ground's surface. A hydrocode, CTH, was also used to perform two and three-dimensional simulations of the blast events. In order to use the hydrocode, Jones Wilkins Lee (JWL) equation of state (EOS) coefficients were developed for the experiment's Unimax dynamite charges; a novel energy-scaling technique was developed which permits the derivation of new JWL coefficients from an existing coefficient set. The hydrocode simulations were able to simulate blast impulses with an average absolute error of 34.5%. Moreover, the hydrocode simulations provided highly resolved spatio-temporal blast loading data for subsequent structural simulations. Equivalent single-degree-of-freedom (ESDOF) structural response models were then used to predict the out-of-plane deflections of blast chamber walls. A new resistance function was developed which permits a URM wall to crack at any height; numerical methodologies were also developed to compute transformation factors required for use in the ESDOF method. When combined with the CTH derived blast loading predictions, the ESDOF models were able to predict out-of-plane deflections with reasonable accuracy. Further investigations were performed using finite element models constructed in LS-DYNA; the models used elastic elements combined with contacts possessing a tension/shear cutoff and the ability to simulate fracture energy release. Using the CTH predicted blast loads and carefully selected constitutive parameters, the LS-DYNA models were able to both qualitatively and quantitatively predict blast chamber wall deflections and damage patterns. Moreover, the finite element models suggested several modes of response which cannot be modeled by current ESDOF methods; the effect of these response modes on the accuracy of ESDOF predictions warrants further study.

Simulation of primary-slag melting behavior in the cohesive zone of a blast furnace, considering the effect of Al{sub 2}O{sub 3}, Fe{sub t}O, and basicity in the sinter ore

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

Hino, Mitsutaka; Nagasaka, Tetsuya; Katsumata, Akitoshi

1999-08-01

The alumina content in the iron ore imported to Japan is increasing year by year, and some problems in blast furnace operation, due to the use of the high-alumina-containing sinter, have already been reported. In order to clarify the mechanism of the harmful effect of alumina on the blast furnace operation, the behavior of the primary melt, which is formed in the sinter at the cohesive zone of the blast furnace, has been simulated by dripping slag through an iron or oxide funnel. The effects of basicity, Al{sub 2}O{sub 3}, and Fe{sub t}O contents in the five slag systems onmore » the dripping temperature and weight of slag remaining on the funnel have been discussed. It was found that the eutectic melt formed in the sinter would play an important role in the dripping behavior of the slag in the blast furnace through the fine porosity of the reduced iron and ore particles. Al{sub 2}O{sub 3} increased the weight of the slag remaining on the funnel, and its effect became very significant in the acidic and low-Fe{sub t}O-containing slag. It was estimated that the increase of the weight of the slag remaining on the funnel by Al{sub 2}O{sub 3} in the ore could result in a harmful effect on the permeability resistance and an indirect reduction rate of the sinter in the blast furnace.« less

Numerical simulations of the occupant head response in an infantry vehicle under blunt impact and blast loading conditions.

PubMed

Sevagan, Gopinath; Zhu, Feng; Jiang, Binhui; Yang, King H

2013-07-01

This article presents the results of a finite element simulation on the occupant head response in an infantry vehicle under two separated loading conditions: (1) blunt impact and (2) blast loading conditions. A Hybrid-III dummy body integrated with a previously validated human head model was used as the surrogate. The biomechanical response of the head was studied in terms of head acceleration due to the impact by a projectile on the vehicle and intracranial pressure caused by blast wave. A series of parametric studies were conducted on the numerical model to analyze the effect of some key parameters, such as seat configuration, impact velocity, and boundary conditions. The simulation results indicate that a properly designed seat and internal surface of the infantry vehicle can play a vital role in reducing the risk of head injury in the current scenarios. Comparison of the kinematic responses under the blunt impact and blast loading conditions reveals that under the current loading conditions, the acceleration pulse in the blast scenario has much higher peak values and frequency than blunt impact case, which may reflect different head response characteristics.

An Empirical Model for Mine-Blast Loading

DTIC Science & Technology

2014-10-17

fledged experimental program. The numerical approach however suffers from several drawbacks in the mine blast simulations. First, it is a very...Suffield consisted in a pendulum type device to measure global impulse of buried mine [15]. One of the main purposes of the ONAGER pendulum was to study...TP-1 Terminal effects, KTA 1-34 report, 2004. [15] Bues, R., Hlady, S.L. and Bergeron, D.M., Pendulum Measurement of Land Mine Blast Output, Volume

Minimization of Blast furnace Fuel Rate by Optimizing Burden and Gas Distribution

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

Dr. Chenn Zhou

2012-08-15

The goal of the research is to improve the competitive edge of steel mills by using the advanced CFD technology to optimize the gas and burden distributions inside a blast furnace for achieving the best gas utilization. A state-of-the-art 3-D CFD model has been developed for simulating the gas distribution inside a blast furnace at given burden conditions, burden distribution and blast parameters. The comprehensive 3-D CFD model has been validated by plant measurement data from an actual blast furnace. Validation of the sub-models is also achieved. The user friendly software package named Blast Furnace Shaft Simulator (BFSS) has beenmore » developed to simulate the blast furnace shaft process. The research has significant benefits to the steel industry with high productivity, low energy consumption, and improved environment.« less

Mine Blast Loading: Experiments and Simulations

DTIC Science & Technology

2010-04-01

plates by approximately 50%. We investigated the root cause for this discrepancy. The simulations calculate a turbulent-like flow field characterized...Toussaint [19] evaluated two numerical methods, Smooth Particle Hydrodynamics ( SPH ) and Arbitrary Lagrangian Eulerian (ALE), to simulate a mine blast on...That is, the mine blast products were not flowing along the solid plate boundary in the simulations as freely as they should. 6 In particular, the V

Investigation of blast-induced traumatic brain injury.

PubMed

Taylor, Paul A; Ludwigsen, John S; Ford, Corey C

2014-01-01

Many troops deployed in Iraq and Afghanistan have sustained blast-related, closed-head injuries from being within non-lethal distance of detonated explosive devices. Little is known, however, about the mechanisms associated with blast exposure that give rise to traumatic brain injury (TBI). This study attempts to identify the precise conditions of focused stress wave energy within the brain, resulting from blast exposure, which will correlate with a threshold for persistent brain injury. This study developed and validated a set of modelling tools to simulate blast loading to the human head. Using these tools, the blast-induced, early-time intracranial wave motions that lead to focal brain damage were simulated. The simulations predict the deposition of three distinct wave energy components, two of which can be related to injury-inducing mechanisms, namely cavitation and shear. Furthermore, the results suggest that the spatial distributions of these damaging energy components are independent of blast direction. The predictions reported herein will simplify efforts to correlate simulation predictions with clinical measures of TBI and aid in the development of protective headwear.

Investigation of blast-induced traumatic brain injury

PubMed Central

Ludwigsen, John S.; Ford, Corey C.

2014-01-01

Objective Many troops deployed in Iraq and Afghanistan have sustained blast-related, closed-head injuries from being within non-lethal distance of detonated explosive devices. Little is known, however, about the mechanisms associated with blast exposure that give rise to traumatic brain injury (TBI). This study attempts to identify the precise conditions of focused stress wave energy within the brain, resulting from blast exposure, which will correlate with a threshold for persistent brain injury. Methods This study developed and validated a set of modelling tools to simulate blast loading to the human head. Using these tools, the blast-induced, early-time intracranial wave motions that lead to focal brain damage were simulated. Results The simulations predict the deposition of three distinct wave energy components, two of which can be related to injury-inducing mechanisms, namely cavitation and shear. Furthermore, the results suggest that the spatial distributions of these damaging energy components are independent of blast direction. Conclusions The predictions reported herein will simplify efforts to correlate simulation predictions with clinical measures of TBI and aid in the development of protective headwear. PMID:24766453

NUMERICAL ANALYSIS TECHNIQUE USING THE STATISTICAL ENERGY ANALYSIS METHOD CONCERNING THE BLASTING NOISE REDUCTION BY THE SOUND INSULATION DOOR USED IN TUNNEL CONSTRUCTIONS

NASA Astrophysics Data System (ADS)

Ishida, Shigeki; Mori, Atsuo; Shinji, Masato

The main method to reduce the blasting charge noise which occurs in a tunnel under construction is to install the sound insulation door in the tunnel. However, the numerical analysis technique to predict the accurate effect of the transmission loss in the sound insulation door is not established. In this study, we measured the blasting charge noise and the vibration of the sound insulation door in the tunnel with the blasting charge, and performed analysis and modified acoustic feature. In addition, we reproduced the noise reduction effect of the sound insulation door by statistical energy analysis method and confirmed that numerical simulation is possible by this procedure.

Simulation and Measurements of Small Arms Blast Wave Overpressure in the Process of Designing a Silencer

NASA Astrophysics Data System (ADS)

Hristov, Nebojša; Kari, Aleksandar; Jerković, Damir; Savić, Slobodan; Sirovatka, Radoslav

2015-02-01

Simulation and measurements of muzzle blast overpressure and its physical manifestations are studied in this paper. The use of a silencer can have a great influence on the overpressure intensity. A silencer is regarded as an acoustic transducer and a waveguide. Wave equations for an acoustic dotted source of directed effect are used for physical interpretation of overpressure as an acoustic phenomenon. Decomposition approach has proven to be suitable to describe the formation of the output wave of the wave transducer. Electroacoustic analogies are used for simulations. A measurement chain was used to compare the simulation results with the experimental ones.

Simulation of adaptive semi-active magnetorheological seat damper for vehicle occupant blast protection

NASA Astrophysics Data System (ADS)

Yoo, Jin-Hyeong; Murugan, Muthuvel; Wereley, Norman M.

2013-04-01

This study investigates a lumped-parameter human body model which includes lower leg in seated posture within a quarter-car model for blast injury assessment simulation. To simulate the shock acceleration of the vehicle, mine blast analysis was conducted on a generic land vehicle crew compartment (sand box) structure. For the purpose of simulating human body dynamics with non-linear parameters, a physical model of a lumped-parameter human body within a quarter car model was implemented using multi-body dynamic simulation software. For implementing the control scheme, a skyhook algorithm was made to work with the multi-body dynamic model by running a co-simulation with the control scheme software plug-in. The injury criteria and tolerance levels for the biomechanical effects are discussed for each of the identified vulnerable body regions, such as the relative head displacement and the neck bending moment. The desired objective of this analytical model development is to study the performance of adaptive semi-active magnetorheological damper that can be used for vehicle-occupant protection technology enhancements to the seat design in a mine-resistant military vehicle.

Blast and the Consequences on Traumatic Brain Injury-Multiscale Mechanical Modeling of Brain

DTIC Science & Technology

2011-02-17

blast simulation. LS-DYNA as an explicit FE code has been employed to simulate this multi- material fluid –structure interaction problem. The 3-D head...formulation is implemented to model the air-blast simulation. LS-DYNA as an explicit FE code has been employed to simulate this multi-material fluid ...Biomechanics Study of Influencing Parameters for brain under Impact ............................... 12 5.1 The Impact of Cerebrospinal Fluid

Enhancements and Analysis of CTH Software for Underbody Blast

DTIC Science & Technology

2013-02-01

authors expressed herein do not necessarily state or reflect those of the United States Government or the DoD, and shall not be used for advertising or...Trembelay, J., “Validation of a Loading Model for Simulating Blast Mine Effects on Armoured Vehicles,” 7th International LS-DYNA Users Conference

Development of a multimodal blast sensor for measurement of head impact and over-pressurization exposure.

PubMed

Chu, Jeffrey J; Beckwith, Jonathan G; Leonard, Daniel S; Paye, Corey M; Greenwald, Richard M

2012-01-01

It is estimated that 10-20% of United States soldiers returning from Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF) have suffered at least one instance of blast-induced traumatic brain injury (bTBI) with many reporting persistent symptomology and long-term effects. This variation in blast response may be related to the complexity of blast waves and the many mechanisms of injury, including over-pressurization due to the shock wave and potential for blunt impacts to the head from shrapnel or from other indirect impacts (e.g., building, ground, and vehicle). To help differentiate the effects of primary, secondary, and tertiary effects of blast, a custom sensor was developed to simultaneously measure over-pressurization and blunt impact. Moreover, a custom, complementary filter was designed to differentiate the measurements of blunt (low-frequency bandwidth) from over-pressurization (high-frequency bandwidth). The custom sensor was evaluated in the laboratory using a shock tube to simulate shock waves and a drop fixture to simulate head impacts. Both bare sensors and sensor embedded within an ACH helmet coupon were compared to laboratory reference transducers under multiple loading conditions (n = 5) and trials at each condition (n = 3). For all comparative measures, peak magnitude, peak impulse, and cross-correlation measures, R (2) values, were greater than 0.900 indicating excellent agreement of peak measurements and time-series comparisons with laboratory measures.

Blast Load Simulator Experiments for Computational Model Validation Report 3

DTIC Science & Technology

2017-07-01

establish confidence in the results produced by the simulations. This report describes a set of replicate experiments in which a small, non - responding steel...designed to simulate blast waveforms for explosive yields up to 20,000 lb of TNT equivalent at a peak reflected pressure up to 80 psi and a peak...the pressure loading on a non - responding box-type structure at varying obliquities located in the flow of the BLS simulated blast environment for

Simulation Engine for Fluid Solid Interaction Problems and its Application to the Modelling of Air Blast Hazards in Block Cave Mining.

NASA Astrophysics Data System (ADS)

Galindo Torres, S. A.; Scheuermann, A.; Ruest, M.

2016-12-01

Air blasts that may occur in a block caving mining operation represent a significant hazard for personnel as well as to mining infrastructure. Uncontrolled caving of a large volume of broken rock into a mine void causes compression of the air within, forcing it to flow at high velocities into connecting tunnels such as extraction points beneath the cave or observation points intersecting the cave. This high velocity flow of air can cause injury to personnel and significant damage to equipment. In this presentation, we introduce a simulation engine for the air blast problem. The solid material is modelled using the Discrete Element Method (DEM) and the fluid (air) is modelled using the Lattice Boltzmann Method (LBM). The combined DEM-LBM approach has been introduced by our group at the University of Queensland[1]. LBM allows us to introduce an appropriate equation of state for the air that simulates compressibility as a function of the speed of sound. Validation examples are presented to justify the use of this tool for an air blasting situation. A section view of one simulation is provided in Fig 1. An investigation into the risk of developing air pockets as a function of fragment size distribution is also conducted and described. The fragment size distribution can be assessed during mining and the risk of air pockets forming (and consequently of air blast occurring) can be deduced and mitigation measures put in place. The effect of other key variables that can be determined from geotechnical investigations, such as fracture frequency, are also systematically explored. It is expected that the results of this study can elucidate key features of the air blasting phenomenon in order to formulate safer mining protocols. references 1. Galindo-Torres, S.A., A coupled Discrete Element Lattice Boltzmann Method for the simulation of fluid-solid interaction with particles of general shapes. Computer Methods in Applied Mechanics and Engineering, 2013. 265(0): p. 107-119.

Comparison of Building Loads Analysis and System Thermodynamics (BLAST) Computer Program Simulations and Measured Energy Use for Army Buildings.

DTIC Science & Technology

1980-05-01

engineering ,ZteNo D R RPTE16 research w 9 laboratory COMPARISON OF BUILDING LOADS ANALYSIS AND SYSTEM THERMODYNAMICS (BLAST) AD 0 5 5,0 3COMPUTER PROGRAM...Building Loads Analysis and System Thermodynamics (BLAST) computer program. A dental clinic and a battalion headquarters and classroom building were...Building and HVAC System Data Computer Simulation Comparison of Actual and Simulated Results ANALYSIS AND FINDINGS

Blast Load Simulator Experiments for Computational Model Validation: Report 1

DTIC Science & Technology

2016-08-01

involving the inclusion of non-responding box-type structures in a BLS simulated blast environment. The BLS is a highly tunable com- pressed-gas-driven...Blast Load Simulator (BLS) to evaluate its suitability for a future effort involving the inclusion of non-responding box-type structures located in...Recommendations Preliminary testing indicated that inclusion of the grill and diaphragm striker resulted in a decrease in peak pressure of about 12

Dynamics and stability of relativistic gamma-ray-bursts blast waves

NASA Astrophysics Data System (ADS)

Meliani, Z.; Keppens, R.

2010-09-01

Aims: In gamma-ray-bursts (GRBs), ultra-relativistic blast waves are ejected into the circumburst medium. We analyse in unprecedented detail the deceleration of a self-similar Blandford-McKee blast wave from a Lorentz factor 25 to the nonrelativistic Sedov phase. Our goal is to determine the stability properties of its frontal shock. Methods: We carried out a grid-adaptive relativistic 2D hydro-simulation at extreme resolving power, following the GRB jet during the entire afterglow phase. We investigate the effect of the finite initial jet opening angle on the deceleration of the blast wave, and identify the growth of various instabilities throughout the coasting shock front. Results: We find that during the relativistic phase, the blast wave is subject to pressure-ram pressure instabilities that ripple and fragment the frontal shock. These instabilities manifest themselves in the ultra-relativistic phase alone, remain in full agreement with causality arguments, and decay slowly to finally disappear in the near-Newtonian phase as the shell Lorentz factor drops below 3. From then on, the compression rate decreases to levels predicted to be stable by a linear analysis of the Sedov phase. Our simulations confirm previous findings that the shell also spreads laterally because a rarefaction wave slowly propagates to the jet axis, inducing a clear shell deformation from its initial spherical shape. The blast front becomes meridionally stratified, with decreasing speed from axis to jet edge. In the wings of the jetted flow, Kelvin-Helmholtz instabilities occur, which are of negligible importance from the energetic viewpoint. Conclusions: Relativistic blast waves are subject to hydrodynamical instabilities that can significantly affect their deceleration properties. Future work will quantify their effect on the afterglow light curves.

Simulation and scaling analysis of a spherical particle-laden blast wave

NASA Astrophysics Data System (ADS)

Ling, Y.; Balachandar, S.

2018-02-01

A spherical particle-laden blast wave, generated by a sudden release of a sphere of compressed gas-particle mixture, is investigated by numerical simulation. The present problem is a multiphase extension of the classic finite-source spherical blast-wave problem. The gas-particle flow can be fully determined by the initial radius of the spherical mixture and the properties of gas and particles. In many applications, the key dimensionless parameters, such as the initial pressure and density ratios between the compressed gas and the ambient air, can vary over a wide range. Parametric studies are thus performed to investigate the effects of these parameters on the characteristic time and spatial scales of the particle-laden blast wave, such as the maximum radius the contact discontinuity can reach and the time when the particle front crosses the contact discontinuity. A scaling analysis is conducted to establish a scaling relation between the characteristic scales and the controlling parameters. A length scale that incorporates the initial pressure ratio is proposed, which is able to approximately collapse the simulation results for the gas flow for a wide range of initial pressure ratios. This indicates that an approximate similarity solution for a spherical blast wave exists, which is independent of the initial pressure ratio. The approximate scaling is also valid for the particle front if the particles are small and closely follow the surrounding gas.

Simulation and scaling analysis of a spherical particle-laden blast wave

NASA Astrophysics Data System (ADS)

Ling, Y.; Balachandar, S.

2018-05-01

A spherical particle-laden blast wave, generated by a sudden release of a sphere of compressed gas-particle mixture, is investigated by numerical simulation. The present problem is a multiphase extension of the classic finite-source spherical blast-wave problem. The gas-particle flow can be fully determined by the initial radius of the spherical mixture and the properties of gas and particles. In many applications, the key dimensionless parameters, such as the initial pressure and density ratios between the compressed gas and the ambient air, can vary over a wide range. Parametric studies are thus performed to investigate the effects of these parameters on the characteristic time and spatial scales of the particle-laden blast wave, such as the maximum radius the contact discontinuity can reach and the time when the particle front crosses the contact discontinuity. A scaling analysis is conducted to establish a scaling relation between the characteristic scales and the controlling parameters. A length scale that incorporates the initial pressure ratio is proposed, which is able to approximately collapse the simulation results for the gas flow for a wide range of initial pressure ratios. This indicates that an approximate similarity solution for a spherical blast wave exists, which is independent of the initial pressure ratio. The approximate scaling is also valid for the particle front if the particles are small and closely follow the surrounding gas.

Skull Flexure from Blast Waves: A Mechanism for Brain Injury with Implications for Helmet Design

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

Moss, W C; King, M J; Blackman, E G

2009-04-30

Traumatic brain injury [TBI] has become a signature injury of current military conflicts, with debilitating, costly, and long-lasting effects. Although mechanisms by which head impacts cause TBI have been well-researched, the mechanisms by which blasts cause TBI are not understood. From numerical hydrodynamic simulations, we have discovered that non-lethal blasts can induce sufficient skull flexure to generate potentially damaging loads in the brain, even without a head impact. The possibility that this mechanism may contribute to TBI has implications for injury diagnosis and armor design.

BLAST BIOLOGY. Technical Progress Report

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

White, C.S.; Richmond, D.R.

1959-09-18

Experimental data regarding the biologic consequences of exposure to several environmental variations associated with actual and simulated explosive detonations were reviewed. Blast biology is discussed relative to primary, secondary, tentiary, and miscellaneous blast effects as those attributable, respectively, to variations in environmental pressure, trauma from blast-produced missiles (both penetrating and nonpenetrating), the consequences of physical displacement of biological targets by blast-produced winds, and hazards due to ground shock, dust, and thermal phenomena not caused by thermal radiation per se. Primary blast effects were considered, noting physical-biophysical factors contributing to the observed pathophysiology. A simple hydrostatic model was utilized diagrammatically inmore » pointing out possible etiologic mechanisms. The gross biologic response to single. "fast"-rising overpressures were described as was the tolerance of mice, rats, guinea pigs. and rabbits to "long"-duration pressure pulses rising "rapidly" in single and double steps. Data regarding biological response to "slowly" rising over-pressures of "long" duration are discussed. Attention was called to the similarities under certain circumstances between thoracic trauma from nonpenetrating missiles and that noted from air blast. The association between air emboli, increase in lung weight (hemorrhage and edema), and mortality was discussed. Data relevant to the clinical symptoms and therapy of blast injury are presented. The relation of blast hazards to nuclear explosions was assessed and one approach to predicting the maximal potential casualties from blast phenomena is presented making use of arbitrary and tentative criteria. (auth)« less

Computational modeling of blast wave interaction with a human body and assessment of traumatic brain injury

NASA Astrophysics Data System (ADS)

Tan, X. G.; Przekwas, A. J.; Gupta, R. K.

2017-11-01

The modeling of human body biomechanics resulting from blast exposure poses great challenges because of the complex geometry and the substantial material heterogeneity. We developed a detailed human body finite element model representing both the geometry and the materials realistically. The model includes the detailed head (face, skull, brain and spinal cord), the neck, the skeleton, air cavities (lungs) and the tissues. Hence, it can be used to properly model the stress wave propagation in the human body subjected to blast loading. The blast loading on the human was generated from a simulated C4 explosion. We used the highly scalable solvers in the multi-physics code CoBi for both the blast simulation and the human body biomechanics. The meshes generated for these simulations are of good quality so that relatively large time-step sizes can be used without resorting to artificial time scaling treatments. The coupled gas dynamics and biomechanics solutions were validated against the shock tube test data. The human body models were used to conduct parametric simulations to find the biomechanical response and the brain injury mechanism due to blasts impacting the human body. Under the same blast loading condition, we showed the importance of inclusion of the whole body.

Improvements to the Sandia CTH Hydro-Code to Support Blast Analysis and Protective Design of Military Vehicles

DTIC Science & Technology

2014-04-15

used for advertising or product endorsement purposes. 6.0 REFERENCES [1] McGlaun, J., Thompson, S. and Elrick, M. “CTH: A Three-Dimensional Shock-Wave...Validation of a Loading Model for Simulating Blast Mine Effects on Armoured Vehicles,” 7 th International LS-DYNA Users Conference, Detroit, MI 2002. [14

An animal-to-human scaling law for blast-induced traumatic brain injury risk assessment.

PubMed

Jean, Aurélie; Nyein, Michelle K; Zheng, James Q; Moore, David F; Joannopoulos, John D; Radovitzky, Raúl

2014-10-28

Despite recent efforts to understand blast effects on the human brain, there are still no widely accepted injury criteria for humans. Recent animal studies have resulted in important advances in the understanding of brain injury due to intense dynamic loads. However, the applicability of animal brain injury results to humans remains uncertain. Here, we use advanced computational models to derive a scaling law relating blast wave intensity to the mechanical response of brain tissue across species. Detailed simulations of blast effects on the brain are conducted for different mammals using image-based biofidelic models. The intensity of the stress waves computed for different external blast conditions is compared across species. It is found that mass scaling, which successfully estimates blast tolerance of the thorax, fails to capture the brain mechanical response to blast across mammals. Instead, we show that an appropriate scaling variable must account for the mass of protective tissues relative to the brain, as well as their acoustic impedance. Peak stresses transmitted to the brain tissue by the blast are then shown to be a power function of the scaling parameter for a range of blast conditions relevant to TBI. In particular, it is found that human brain vulnerability to blast is higher than for any other mammalian species, which is in distinct contrast to previously proposed scaling laws based on body or brain mass. An application of the scaling law to recent experiments on rabbits furnishes the first physics-based injury estimate for blast-induced TBI in humans.

[An experimental study of blast injury].

PubMed

Wang, Z G

1989-01-01

This paper presents some aspects of the authors' experimental research on blast injury in the past two years. The main results are as follows: (1) A new designed 39 meter-long shock tube for biological test has been built in the laboratory. Its maximal overpressure values are 215 kPa (in open condition) and 505 kPa (in closed condition). It may meet the need for inflicting blast injuries with various degree of severity. (2) A study of the effect of simulating gun muzzle blast wave on sheep indicated that in the single explosion, the threshold overpressure values inflicting the injury of internal organs were: Lung-37.27 kPa, G-I tract-41.0 kPa; the upper respiratory tract-negative until 73 kPa, while in the multiple (20 times) explosions, they were 23.7, 23.7 and 41.4 kPa, respectively. (3) Using TEM, SEM and some other special techniques, such as morphometry, freeze-fracture technique, labelled lanthanum nitrate technique, etc, it was demonstrated that in the lung with blast injury there were significant pathological changes in pulmonary capillary endothelium, alveolar epithelium and their intercellular junctions with apparent increase of permeability. (4) It has been shown that parallel superficial stripelike hemorrhage typical for lung blast injury is "Intercostal marking" instead of "Rib marking". (5) A new type of material (foamy nickel) for protection against blast wave is presented. It was proved that the material can effectively weaken or eliminate the effect of blast wave on human body.

Blast-induced phenotypic switching in cerebral vasospasm

PubMed Central

Alford, Patrick W.; Dabiri, Borna E.; Goss, Josue A.; Hemphill, Matthew A.; Brigham, Mark D.; Parker, Kevin Kit

2011-01-01

Vasospasm of the cerebrovasculature is a common manifestation of blast-induced traumatic brain injury (bTBI) reported among combat casualties in the conflicts in Afghanistan and Iraq. Cerebral vasospasm occurs more frequently, and with earlier onset, in bTBI patients than in patients with other TBI injury modes, such as blunt force trauma. Though vasospasm is usually associated with the presence of subarachnoid hemorrhage (SAH), SAH is not required for vasospasm in bTBI, which suggests that the unique mechanics of blast injury could potentiate vasospasm onset, accounting for the increased incidence. Here, using theoretical and in vitro models, we show that a single rapid mechanical insult can induce vascular hypercontractility and remodeling, indicative of vasospasm initiation. We employed high-velocity stretching of engineered arterial lamellae to simulate the mechanical forces of a blast pulse on the vasculature. An hour after a simulated blast, injured tissues displayed altered intracellular calcium dynamics leading to hypersensitivity to contractile stimulus with endothelin-1. One day after simulated blast, tissues exhibited blast force dependent prolonged hypercontraction and vascular smooth muscle phenotype switching, indicative of remodeling. These results suggest that an acute, blast-like injury is sufficient to induce a hypercontraction-induced genetic switch that potentiates vascular remodeling, and cerebral vasospasm, in bTBI patients. PMID:21765001

Shock tubes and blast injury modeling.

PubMed

Ning, Ya-Lei; Zhou, Yuan-Guo

2015-01-01

Explosive blast injury has become the most prevalent injury in recent military conflicts and terrorist attacks. The magnitude of this kind of polytrauma is complex due to the basic physics of blast and the surrounding environments. Therefore, development of stable, reproducible and controllable animal model using an ideal blast simulation device is the key of blast injury research. The present review addresses the modeling of blast injury and applications of shock tubes.

Static Holdup of Liquid Slag in Simulated Packed Coke Bed Under Oxygen Blast Furnace Ironmaking Conditions

NASA Astrophysics Data System (ADS)

Wang, Guang; Liu, Yingli; Zhou, Zhenfeng; Wang, Jingsong; Xue, Qingguo

2018-01-01

The liquid-phase flow behavior of slag in the lower zone of a blast furnace affects the furnace permeability, performance, and productivity. The effects of pulverized coal injection (PCI) on the behavior of simulated primary slag flow were investigated by quantifying the effect of key variables including Al/Si ratio [Al2O3 (wt.%) to SiO2 (wt.%)] and the amount of unburnt pulverized coal (UPC) at 1500°C. Viscosity analysis demonstrated that the slag fluidity decreased as the Al/Si ratio was increased (from 0.35 to 0.50), resulting in gradual increase of the static holdup. Increasing the amount of UPC resulted in a significant increase of the static holdup. Flooding analysis was applied to determine the maximum static holdup, which was found to be 11.5%. It was inferred that the burnout rates of pulverized coal should exceed 78.6% and 83.9% in traditional and oxygen blast furnaces, respectively.

Effects of Packed Structure and Operation Conditions on Liquid Flow Behavior in Blast Furnace Hearth

NASA Astrophysics Data System (ADS)

Zuo, Haibin; Hong, Jun; Zhang, Jianliang; Zheng, Jin

The circulating flow of molten iron is an important reason that results in the erosion of blast furnace hearth. In order to prolong the campaign life of blast furnace, it is necessary to analysis the flow state of molten iron. The three-dimensional mathematical model at steady state which takes the standard k-e and porous zone model into consideration is applied to simulate the flow field under different conditions. The results showed that floating of the deadman did strengthen molten iron circulating flow. Increasing the deadman diameter will increase the erosion of hearth and bottom. Deepen the depth of the taphole and reduce the taphole diameter can reduce the circulating flow. Effect of the taphole angle from 10° to 15° is not significant. The results can be used to provide guidance for protecting the blast furnace hearth.

Physics-Based Simulation and Experiment on Blast Protection of Infill Walls and Sandwich Composites Using New Generation of Nano Particle Reinforced Materials

NASA Astrophysics Data System (ADS)

Irshidat, Mohammad

A critical issue for the development of nanotechnology is our ability to understand, model, and simulate the behavior of small structures and to make the connection between nano structure properties and their macroscopic functions. Material modeling and simulation helps to understand the process, to set the objectives that could guide laboratory efforts, and to control material structures, properties, and processes at physical implementation. These capabilities are vital to engineering design at the component and systems level. In this research, experimental-computational-analytical program was employed to investigate the performance of the new generation of polymeric nano-composite materials, like nano-particle reinforced elastomeric materials (NPREM), for the protection of masonry structures against blast loads. New design tools for using these kinds of materials to protect Infill Walls (e.g. masonry walls) against blast loading were established. These tools were also extended to cover other type of panels like sandwich composites. This investigation revealed that polymeric nano composite materials are strain rate sensitive and have large amount of voids distributed randomly inside the materials. Results from blast experiments showed increase in ultimate flexural resistance achieved by both unreinforced and nano reinforced polyurea retrofit systems applied to infill masonry walls. It was also observed that a thin elastomeric coating on the interior face of the walls could be effective at minimizing the fragmentation resulting from blast. More conclusions are provided with recommended future research.

Fluid dynamics of the 1997 Boxing Day volcanic blast on Montserrat, West Indies

NASA Astrophysics Data System (ADS)

Esposti Ongaro, T.; Clarke, A. B.; Neri, A.; Voight, B.; Widiwijayanti, C.

2008-03-01

Directed volcanic blasts are powerful explosions with a significant laterally directed component, which can generate devastating, high-energy pyroclastic density currents (PDCs). Such blasts are an important class of eruptive phenomena, but quantified understanding of their dynamics and effects is still incomplete. Here we use 2-D and 3-D multiparticle thermofluid dynamic flow codes to examine a powerful volcanic blast that occurred on Montserrat in December 1997. On the basis of the simulations, we divide the blast into three phases: an initial burst phase that lasts roughly 5 s and involves rapid expansion of the gas-pyroclast mixture, a gravitational collapse phase that occurs when the erupted material fails to mix with sufficient air to form a buoyant column and thus collapses asymmetrically, and a PDC phase that is dominated by motion parallel to the ground surface and is influenced by topography. We vary key input parameters such as total gas energy and total solid mass to understand their influence on simulations, and we compare the simulations with independent field observations of damage and deposits, demonstrating that the models generally capture important large-scale features of the natural phenomenon. We also examine the 2-D and 3-D model results to estimate the flow Mach number and conclude that the range of damage sustained at villages on Montserrat can be reasonably explained by the spatial and temporal distribution of the dynamic pressure associated with subsonic PDCs.

Optimization for blast furnace slag dry cooling granulation device

NASA Astrophysics Data System (ADS)

Dazhan, Sheng; Yali, Wang; Ruiyun, Wang; Suping, Cui; Xiaoyu, Ma

2017-03-01

Since the large accumulation amount of blast furnace slag (BFS) with recycling value, it has become a hot topic for recovery utilization. Compared with the existing various BFS granulation process, the dry granulation process can promote the use of blast furnace granulated slag as cement substitute and concrete admixtures. Our research group developed a novel dry cooling granulation experiment device to treat BFS. However, there are still some problems to be solved. The purpose of this research is to improve the cooling and granulation efficiency of the existing dry type cooling equipment. This topic uses the FLUENT simulation software to study the impact of the number of air inlet on the cooling effect of the device. The simulation result is that the device possessing eight air inlets can increase the number of hot and cold gas exchanged, resulting in a better cooling effect. According to the power consumption, LCA analysis was carried out on the cooling granulation process. The results show that the device equipped eight air inlets not only improved the original equipment cooling granulation effect, but also increased resource utilization ratio, realized energy-saving and emission reduction.

Novel method to dynamically load cells in 3D-hydrogels culture for blast injury studies

NASA Astrophysics Data System (ADS)

Sory, David R.; Areias, Anabela C.; Overby, Darryl R.; Proud, William G.

2017-01-01

For at least a century explosive devices have been one of the most important causes of injuries in military conflicts as well as in terrorist attacks. Although significant experimental and modelling efforts have been focussed on blast injuries at the organ or tissue level, few studies have investigated the mechanisms of blast injuries at the cellular level. This paper introduces an in vitro method compatible with living cells to examine the effects of high stress and short-duration pulses relevant to blast loadings and blunt trauma. The experimental phase involves high strain-rate axial compression of cylindrical specimens within an hermetically sealed chamber made of biocompatible polymer. Numerical simulations were performed in order to verify the experimental loading conditions and to characterize the loading path within the sample. A proof of concept is presented so as to establish a new window to address fundamental questions regarding blast injury at the cellular level.

Comparison between a typical and a simplified model for blast load-induced structural response

NASA Astrophysics Data System (ADS)

Abd-Elhamed, A.; Mahmoud, S.

2017-02-01

As explosive blasts continue to cause severe damage as well as victims in both civil and military environments. There is a bad need for understanding the behavior of structural elements to such extremely short duration dynamic loads where it is of great concern nowadays. Due to the complexity of the typical blast pressure profile model and in order to reduce the modelling and computational efforts, the simplified triangle model for blast loads profile is used to analyze structural response. This simplified model considers only the positive phase and ignores the suction phase which characterizes the typical one in simulating blast loads. The closed from solution for the equation of motion under blast load as a forcing term modelled either typical or simplified models has been derived. The considered herein two approaches have been compared using the obtained results from simulation response analysis of a building structure under an applied blast load. The computed error in simulating response using the simplified model with respect to the typical one has been computed. In general, both simplified and typical models can perform the dynamic blast-load induced response of building structures. However, the simplified one shows a remarkably different response behavior as compared to the typical one despite its simplicity and the use of only positive phase for simulating the explosive loads. The prediction of the dynamic system responses using the simplified model is not satisfactory due to the obtained larger errors as compared to the system responses obtained using the typical one.

Numerical modeling anti-personnel blast mines coupled to a deformable leg structure

NASA Astrophysics Data System (ADS)

Cronin, Duane; Worswick, Mike; Williams, Kevin; Bourget, Daniel; Pageau, Gilles

2001-06-01

The development of improved landmine protective footwear requires an understanding of the physics and damage mechanisms associated with a close proximity blast event. Numerical models have been developed to model surrogate mines buried in soil using the Arbitrary Lagrangian Eulerian (ALE) technique to model the explosive and surrounding air, while the soil is modeled as a deformable Lagrangian solid. The advantage of the ALE model is the ability to model large deformations, such as the expanding gases of a high explosive. This model has been validated using the available experimental data [1]. The effect of varying depth of burial and soil conditions has been investigated with these numerical models and compares favorably to data in the literature. The surrogate landmine model has been coupled to a numerical model of a Simplified Lower Leg (SLL), which is designed to mimic the response and failure mechanisms of a human leg. The SLL consists of a bone and tissue simulant arranged as concentric cylinders. A new strain-rate dependant hyperelastic material model for the tissue simulant, ballistic gelatin, has been developed to model the tissue simulant response. The polymeric bone simulant material has been characterized and implemented as a strain-rate dependent material in the numerical model. The numerical model results agree with the measured response of the SLL during experimental blast tests [2]. The numerical model results are used to explain the experimental data. These models predict that, for a surface or sub-surface buried anti-personnel mine, the coupling between the mine and SLL is an important effect. In addition, the soil properties have a significant effect on the load transmitted to the leg. [1] Bergeron, D., Walker, R. and Coffey, C., 1998, “Detonation of 100-Gram Anti-Personnel Mine Surrogate Charges in Sand”, Report number SR 668, Defence Research Establishment Suffield, Canada. [2] Bourget, D., Williams, K., Pageau, G., and Cronin, D., “AP Mine Blast Effects on Surrogate Lower Leg”, Military Aspects of Ballistics and Shock, MABS 16, 2000.

Computational modeling of human head under blast in confined and open spaces: primary blast injury.

PubMed

Rezaei, A; Salimi Jazi, M; Karami, G

2014-01-01

In this paper, a computational modeling for biomechanical analysis of primary blast injuries is presented. The responses of the brain in terms of mechanical parameters under different blast spaces including open, semi-confined, and confined environments are studied. In the study, the effect of direct and indirect blast waves from the neighboring walls in the confined environments will be taken into consideration. A 50th percentile finite element head model is exposed to blast waves of different intensities. In the open space, the head experiences a sudden intracranial pressure (ICP) change, which vanishes in a matter of a few milliseconds. The situation is similar in semi-confined space, but in the confined space, the reflections from the walls will create a number of subsequent peaks in ICP with a longer duration. The analysis procedure is based on a simultaneous interaction simulation of the deformable head and its components with the blast wave propagations. It is concluded that compared with the open and semi-confined space settings, the walls in the confined space scenario enhance the risk of primary blast injuries considerably because of indirect blast waves transferring a larger amount of damaging energy to the head. Copyright © 2013 John Wiley & Sons, Ltd.

DendroBLAST: approximate phylogenetic trees in the absence of multiple sequence alignments.

PubMed

Kelly, Steven; Maini, Philip K

2013-01-01

The rapidly growing availability of genome information has created considerable demand for both fast and accurate phylogenetic inference algorithms. We present a novel method called DendroBLAST for reconstructing phylogenetic dendrograms/trees from protein sequences using BLAST. This method differs from other methods by incorporating a simple model of sequence evolution to test the effect of introducing sequence changes on the reliability of the bipartitions in the inferred tree. Using realistic simulated sequence data we demonstrate that this method produces phylogenetic trees that are more accurate than other commonly-used distance based methods though not as accurate as maximum likelihood methods from good quality multiple sequence alignments. In addition to tests on simulated data, we use DendroBLAST to generate input trees for a supertree reconstruction of the phylogeny of the Archaea. This independent analysis produces an approximate phylogeny of the Archaea that has both high precision and recall when compared to previously published analysis of the same dataset using conventional methods. Taken together these results demonstrate that approximate phylogenetic trees can be produced in the absence of multiple sequence alignments, and we propose that these trees will provide a platform for improving and informing downstream bioinformatic analysis. A web implementation of the DendroBLAST method is freely available for use at http://www.dendroblast.com/.

Additive Manufacturing of Cranial Simulants for Blast Induced Traumatic Brain Injury

DTIC Science & Technology

2017-08-28

REPORT TYPE 08/28/2017 Poster 4. TITLE AND SUBTITLE Additive Manufacturing of Cranial Sin1ulants for Blast Induced Traumatic Brain Injut’y 6... manufacturing techniques: Fused deposition modeling: ca sling molds Casting: white and gray matter Polymerization of injected solution...Sandia National Laboratories Conclusion MICHIGAN STAT[ l- I’ll I \\ I R <, I r \\ Additive manufacturrng provrdes a cost effective fabrration

Numerical modeling of an experimental shock tube for traumatic brain injury studies

NASA Astrophysics Data System (ADS)

Phillips, Michael; Regele, Jonathan D.

2015-11-01

Unfortunately, Improvised Explosive Devices (IEDs) are encountered commonly by both civilians and military soldiers throughout the world. Over a decade of medical history suggests that traumatic brain injury (TBI) may result from exposure to the blast waves created by these explosions, even if the person does not experience any immediate injury or lose consciousness. Medical researchers study the exposure of mice and rats to blast waves created in specially designed shock tubes to understand the effect on brain tissue. A newly developed table-top shock tube with a short driver section has been developed for mice experiments to reduce the time necessary to administer the blast radiation and increase the amount of statistical information available. In this study, numerical simulations of this shock tube are performed to assess how the blast wave takes its shape. The pressure profiles obtained from the numerical results are compared with the pressure histories from the experimental pressure transducers. The results show differences in behavior from what was expected, but the blast wave may still be an effective means of studying TBI.

Simulation of the Reflected Blast Wave froma C-4 Charge

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

Howard, W M; Kuhl, A L; Tringe, J W

2011-08-01

The reflection of a blast wave from a C4 charge detonated above a planar surface is simulated with our ALE3D code. We used a finely-resolved, fixed Eulerian 2-D mesh (167 {micro}m per cell) to capture the detonation of the charge, the blast wave propagation in nitrogen, and its reflection from the surface. The thermodynamic properties of the detonation products and nitrogen were specified by the Cheetah code. A programmed-burn model was used to detonate the charge at a rate based on measured detonation velocities. Computed pressure histories are compared with pressures measured by Kistler 603B piezoelectric gauges at 8 rangesmore » (GR = 0, 2, 4, 8, 10, and 12 inches) along the reflecting surface. Computed and measured waveforms and positive-phase impulses were similar, except at close-in ranges (GR < 2 inches), which were dominated by jetting effects.« less

Simulation of the reflected blast wave from a C-4 charge

NASA Astrophysics Data System (ADS)

Howard, W. Michael; Kuhl, Allen L.; Tringe, Joseph

2012-03-01

The reflection of a blast wave from a C4 charge detonated above a planar surface is simulated with our ALE3D code. We used a finely-resolved, fixed Eulerian 2-D mesh (167 μm per cell) to capture the detonation of the charge, the blast wave propagation in nitrogen, and its reflection from the surface. The thermodynamic properties of the detonation products and nitrogen were specified by the Cheetah code. A programmed-burn model was used to detonate the charge at a rate based on measured detonation velocities. Computed pressure histories are compared with pressures measured by Kistler 603B piezoelectric gauges at 7 ranges (GR = 0, 5.08, 10.16, 15.24, 20.32, 25.4, and 30.48 cm) along the reflecting surface. Computed and measured waveforms and positive-phase impulses were similar, except at close-in ranges (GR < 5 cm), which were dominated by jetting effects.

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

Preece, D.S.; Knudsen, S.D.

The spherical element computer code DMC (Distinct Motion Code) used to model rock motion resulting from blasting has been enhanced to allow routine computer simulations of bench blasting. The enhancements required for bench blast simulation include: (1) modifying the gas flow portion of DMC, (2) adding a new explosive gas equation of state capability, (3) modifying the porosity calculation, and (4) accounting for blastwell spacing parallel to the face. A parametric study performed with DMC shows logical variation of the face velocity as burden, spacing, blastwell diameter and explosive type are varied. These additions represent a significant advance in themore » capability of DMC which will not only aid in understanding the physics involved in blasting but will also become a blast design tool. 8 refs., 7 figs., 1 tab.« less

Tsunami Generation from Asteroid Airburst and Ocean Impact and Van Dorn Effect

NASA Technical Reports Server (NTRS)

Robertson, Darrel

2016-01-01

Airburst - In the simulations explored energy from the airburst couples very weakly with the water making tsunami dangerous over a shorter distance than the blast for asteroid sizes up to the maximum expected size that will still airburst (approx.250MT). Future areas of investigation: - Low entry angle airbursts create more cylindrical blasts and might couple more efficiently - Bursts very close to the ground will increase coupling - Inclusion of thermosphere (>80km altitude) may show some plume collapse effects over a large area although with much less pressure center dot Ocean Impact - Asteroid creates large cavity in ocean. Cavity backfills creating central jet. Oscillation between the cavity and jet sends out tsunami wave packet. - For deep ocean impact waves are deep water waves (Phase speed = 2x Group speed) - If the tsunami propagation and inundation calculations are correct for the small (<250MT) asteroids in these simulations where they impact deep ocean basins, the resulting tsunami is not a significant hazard unless particularly close to vulnerable communities. Future work: - Shallow ocean impact. - Effect of continental shelf and beach profiles - Tsunami vs. blast damage radii for impacts close to populated areas - Larger asteroids below presumed threshold of global effects (Ø200 - 800m).

Risk Assessment and Prediction of Flyrock Distance by Combined Multiple Regression Analysis and Monte Carlo Simulation of Quarry Blasting

NASA Astrophysics Data System (ADS)

Armaghani, Danial Jahed; Mahdiyar, Amir; Hasanipanah, Mahdi; Faradonbeh, Roohollah Shirani; Khandelwal, Manoj; Amnieh, Hassan Bakhshandeh

2016-09-01

Flyrock is considered as one of the main causes of human injury, fatalities, and structural damage among all undesirable environmental impacts of blasting. Therefore, it seems that the proper prediction/simulation of flyrock is essential, especially in order to determine blast safety area. If proper control measures are taken, then the flyrock distance can be controlled, and, in return, the risk of damage can be reduced or eliminated. The first objective of this study was to develop a predictive model for flyrock estimation based on multiple regression (MR) analyses, and after that, using the developed MR model, flyrock phenomenon was simulated by the Monte Carlo (MC) approach. In order to achieve objectives of this study, 62 blasting operations were investigated in Ulu Tiram quarry, Malaysia, and some controllable and uncontrollable factors were carefully recorded/calculated. The obtained results of MC modeling indicated that this approach is capable of simulating flyrock ranges with a good level of accuracy. The mean of simulated flyrock by MC was obtained as 236.3 m, while this value was achieved as 238.6 m for the measured one. Furthermore, a sensitivity analysis was also conducted to investigate the effects of model inputs on the output of the system. The analysis demonstrated that powder factor is the most influential parameter on fly rock among all model inputs. It is noticeable that the proposed MR and MC models should be utilized only in the studied area and the direct use of them in the other conditions is not recommended.

Neurological Effects of Blast Injury

PubMed Central

Hicks, Ramona R.; Fertig, Stephanie J.; Desrocher, Rebecca E.; Koroshetz, Walter J.; Pancrazio, Joseph J.

2010-01-01

Over the last few years, thousands of soldiers and an even greater number of civilians have suffered traumatic injuries due to blast exposure, largely attributed to improvised explosive devices in terrorist and insurgent activities. The use of body armor is allowing soldiers to survive blasts that would otherwise be fatal due to systemic damage. Emerging evidence suggests that exposure to a blast can produce neurological consequences in the brain, but much remains unknown. To elucidate the current scientific basis for understanding blast-induced traumatic brain injury (bTBI), the NIH convened a workshop in April, 2008. A multidisciplinary group of neuroscientists, engineers, and clinicians were invited to share insights on bTBI, specifically pertaining to: physics of blast explosions, acute clinical observations and treatments, preclinical and computational models, and lessons from the international community on civilian exposures. This report provides an overview of the state of scientific knowledge of bTBI, drawing from the published literature, as well as presentations, discussions, and recommendations from the workshop. One of the major recommendations from the workshop was the need to characterize the effects of blast exposure on clinical neuropathology. Clearer understanding of the human neuropathology would enable validation of preclinical and computational models, which are attempting to simulate blast wave interactions with the central nervous system. Furthermore, the civilian experience with bTBI suggests that polytrauma models incorporating both brain and lung injuries may be more relevant to the study of civilian countermeasures than considering models with a neurological focus alone. PMID:20453776

Simulating Afterburn with LLNL Hydrocodes

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

Daily, L D

2004-06-11

Presented here is a working methodology for adapting a Lawrence Livermore National Laboratory (LLNL) developed hydrocode, ALE3D, to simulate weapon damage effects when afterburn is a consideration in the blast propagation. Experiments have shown that afterburn is of great consequence in enclosed environments (i.e. bomb in tunnel scenario, penetrating conventional munition in a bunker, or satchel charge placed in a deep underground facility). This empirical energy deposition methodology simulates the anticipated addition of kinetic energy that has been demonstrated by experiment (Kuhl, et. al. 1998), without explicitly solving the chemistry, or resolving the mesh to capture small-scale vorticity. This effortmore » is intended to complement the existing capability of either coupling ALE3D blast simulations with DYNA3D or performing fully coupled ALE3D simulations to predict building or component failure, for applications in National Security offensive strike planning as well as Homeland Defense infrastructure protection.« less

Numerical Simulation of Bolide Entry with Ground Footprint Prediction

NASA Technical Reports Server (NTRS)

Aftosmis, Michael J.; Nemec, Marian; Mathias, Donovan L.; Berger, Marsha J.

2016-01-01

As they decelerate through the atmosphere, meteors deposit mass, momentum and energy into the surrounding air at tremendous rates. Trauma from the entry of such bolides produces strong blast waves that can propagate hundreds of kilometers and cause substantial terrestrial damage even when no ground impact occurs. We present a new simulation technique for airburst blast prediction using a fully-conservative, Cartesian mesh, finite-volume solver and investigate the ability of this method to model far- field propagation over hundreds of kilometers. The work develops mathematical models for the deposition of mass, momentum and energy into the atmosphere and presents verification and validation through canonical problems and the comparison of surface overpressures, and blast arrival times with actual results in the literature for known bolides. The discussion also examines the effects of various approximations to the physics of bolide entry that can substantially decrease the computational expense of these simulations. We present parametric studies to quantify the influence of entry-angle, burst-height and other parameters on the ground footprint of the airburst, and these values are related to predictions from analytic and handbook-methods.

Coal Combustion Behavior in New Ironmaking Process of Top Gas Recycling Oxygen Blast Furnace

NASA Astrophysics Data System (ADS)

Zhou, Zhenfeng; Xue, Qingguo; Tang, Huiqing; Wang, Guang; Wang, Jingsong

2017-10-01

The top gas recycling oxygen blast furnace (TGR-OBF) is a new ironmaking process which can significantly reduce the coke ratio and emissions of carbon dioxide. To better understand the coal combustion characteristics in the TGR-OBF, a three dimensional model was developed to simulate the lance-blowpipe-tuyere-raceway of a TGR-OBF. The combustion characteristics of pulverized coal in TGR-OBF were investigated. Furthermore, the effects of oxygen concentration and temperature were also analyzed. The simulation results show that the coal burnout increased by 16.23% compared to that of the TBF. The oxygen content has an obvious effect on the burnout. At 70% oxygen content, the coal burnout is only 21.64%, with a decrease of 50.14% compared to that of TBF. Moreover, the effect of oxygen temperature is also very obvious.

Computer assisted blast design and assessment tools

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

Cameron, A.R.; Kleine, T.H.; Forsyth, W.W.

1995-12-31

In general the software required by a blast designer includes tools that graphically present blast designs (surface and underground), can analyze a design or predict its result, and can assess blasting results. As computers develop and computer literacy continues to rise the development of and use of such tools will spread. An example of the tools that are becoming available includes: Automatic blast pattern generation and underground ring design; blast design evaluation in terms of explosive distribution and detonation simulation; fragmentation prediction; blast vibration prediction and minimization; blast monitoring for assessment of dynamic performance; vibration measurement, display and signal processing;more » evaluation of blast results in terms of fragmentation; and risk and reliability based blast assessment. The authors have identified a set of criteria that are essential in choosing appropriate software blasting tools.« less

Study on Collapse Mechanism of Steel Frame Structure under High Temperature and Blast Loading

NASA Astrophysics Data System (ADS)

Baoxin, Qi; Yan, Shi; Bi, Jialiang

2018-03-01

Numerical simulation analysis for collapsing process and mechanism of steel frame structures under the combined effects of fire and explosion is performed in this paper. First of all, a new steel constitutive model considering fire (high temperature softening effect) and blast (strain rate effect) is established. On the basis of the traditional Johnson-Cook model and the Perzyna model, the relationship between strain and scaled distance as well as the EOUROCODE3 standard heating curve taking into account the temperature effect parameters is introduced, and a modified Johnson-Cook constitutive model is established. Then, the influence of considering the scaled distance is introduced in order to more effectively describe the destruction and collapse phenomena of steel frame structures. Some conclusions are obtained based on the numerical analysis that the destruction will be serious and even progressively collapse with decreasing of the temperature of the steel column for the same scaled distance under the combined effects of fire and blast; the damage will be serious with decreasing of the scaled distance of the steel column under the same temperature under the combined effects of fire and blast; in the case of the combined effects of fire and blast happening in the side-spans, the partial progressive collapse occurs as the scaled distance is less than or equal to 1.28; six kinds of damages which are no damage, minor damage, moderate damage, severe damage, critical collapse, and progressive collapse.

System Engineering Approach to Assessing Integrated Survivability

DTIC Science & Technology

2009-08-01

based response for the above engagements using LS- Dyna for blast modelling, MADYMO for safety and human response, CFD software (Fluent) is used to...Simulation JFAS Joint Force Analysis Simulation JANUS Joint Army Navy Uniform Simulation LS- DYNA Livermore Software-Dynamics MADYMO...management technologies. The “don’t be killed” layer of survivability protection accounts for many of the mitigation technologies (i.e. blast

The Foulness Multiton Air Blast Simulator. Part 3. Blast Wave Formation and Methods Used to Drive the Simulator,

DTIC Science & Technology

1980-03-01

the total energy release of the explosive driver using expanded polystyrene and at the same time, controlling the rate of release. The part played by aqueous foam in minimising irregularities in waveform also is described. (Author)

Air blasts generated by rockfall impacts: Analysis of the 1996 Happy Isles event in Yosemite National Park

USGS Publications Warehouse

Morrissey, M.M.; Savage, W.Z.; Wieczorek, G.F.

1999-01-01

The July 10, 1996, Happy Isles rockfall in Yosemite National Park, California, released 23,000 to 38,000 m3 of granite in four separate events. The impacts of the first two events which involved a 550-m free fall, generated seismic waves and atmospheric pressure waves (air blasts). We focus on the dynamic behavior of the second air blast that downed over 1000 trees, destroyed a bridge, demolished a snack bar, and caused one fatality and several injuries. Calculated velocities for the air blast from a two-phase, finite difference model are compared to velocities estimated from tree damage. From tornadic studies of tree damage, the air blast is estimated to have traveled <108-120 m/s within 50 m from the impact and decreased to <10-20 m/s within 500 m from the impact. The numerical model simulates the two-dimensional propagation of an air blast through a dusty atmosphere with initial conditions defined by the impact velocity and pressure. The impact velocity (105-107 m/s) is estimated from the Colorado Rockfall Simulation Program that simulates rockfall trajectories. The impact pressure (0.5 MPa) is constrained by the kinetic energy of the impact (1010-1012 J) estimated from the seismic energy generated by the impact. Results from the air blast simulations indicate that the second Happy Isles air blast (weak shock wave) traveled with an initial velocity above the local sound speed. The size and location of the first impact are thought to have injected <50 wt % dust into the atmosphere. This amount of dust lowered the local atmospheric sound speed to ???220 m/s. The discrepancy between calculated velocity data and field estimated velocity data (???220 m/s versus ???110 m/s) is attributed to energy dissipated by the downing of trees and additional entrainment of debris into the atmosphere not included in the calculations. Copyright 1999 by the American Geophysical Union.

Air blasts generated by rockfall impacts: Analysis of the 1996 Happy Isles event in Yosemite National Park

NASA Astrophysics Data System (ADS)

Morrissey, M. M.; Savage, W. Z.; Wieczorek, G. F.

1999-10-01

The July 10, 1996, Happy Isles rockfall in Yosemite National Park, California, released 23,000 to 38,000 m3 of granite in four separate events. The impacts of the first two events which involved a 550-m free fall, generated seismic waves and atmospheric pressure waves (air blasts). We focus on the dynamic behavior of the second air blast that downed over 1000 trees, destroyed a bridge, demolished a snack bar, and caused one fatality and several injuries. Calculated velocities for the air blast from a two-phase, finite difference model are compared to velocities estimated from tree damage. From tornadic studies of tree damage, the air blast is estimated to have traveled <108-120 m/s within 50 m from the impact and decreased to <10-20 m/s within 500 m from the impact. The numerical model simulates the two-dimensional propagation of an air blast through a dusty atmosphere with initial conditions defined by the impact velocity and pressure. The impact velocity (105-107 m/s) is estimated from the Colorado Rockfall Simulation Program that simulates rockfall trajectories. The impact pressure (0.5 MPa) is constrained by the kinetic energy of the impact (1010-1012 J) estimated from the seismic energy generated by the impact. Results from the air blast simulations indicate that the second Happy Isles air blast (weak shock wave) traveled with an initial velocity above the local sound speed. The size and location of the first impact are thought to have injected <50 wt% dust into the atmosphere. This amount of dust lowered the local atmospheric sound speed to ˜220 m/s. The discrepancy between calculated velocity data and field estimated velocity data (˜220 m/s versus ˜110 m/s) is attributed to energy dissipated by the downing of trees and additional entrainment of debris into the atmosphere not included in the calculations.

Dynamic Modelling of Fault Slip Induced by Stress Waves due to Stope Production Blasts

NASA Astrophysics Data System (ADS)

Sainoki, Atsushi; Mitri, Hani S.

2016-01-01

Seismic events can take place due to the interaction of stress waves induced by stope production blasts with faults located in close proximity to stopes. The occurrence of such seismic events needs to be controlled to ensure the safety of the mine operators and the underground mine workings. This paper presents the results of a dynamic numerical modelling study of fault slip induced by stress waves resulting from stope production blasts. First, the calibration of a numerical model having a single blast hole is performed using a charge weight scaling law to determine blast pressure and damping coefficient of the rockmass. Subsequently, a numerical model of a typical Canadian metal mine encompassing a fault parallel to a tabular ore deposit is constructed, and the simulation of stope extraction sequence is carried out with static analyses until the fault exhibits slip burst conditions. At that point, the dynamic analysis begins by applying the calibrated blast pressure to the stope wall in the form of velocities generated by the blast holes. It is shown from the results obtained from the dynamic analysis that the stress waves reflected on the fault create a drop of normal stresses acting on the fault, which produces a reduction in shear stresses while resulting in fault slip. The influence of blast sequences on the behaviour of the fault is also examined assuming several types of blast sequences. Comparison of the blast sequence simulation results indicates that performing simultaneous blasts symmetrically induces the same level of seismic events as separate blasts, although seismic energy is more rapidly released when blasts are performed symmetrically. On the other hand when nine blast holes are blasted simultaneously, a large seismic event is induced, compared to the other two blasts. It is concluded that the separate blasts might be employed under the adopted geological conditions. The developed methodology and procedure to arrive at an ideal blast sequence can be applied to other mines where faults are found in the vicinity of stopes.

Airblast Simulator Studies.

DTIC Science & Technology

1984-02-01

RAREFACTION WAVE ELIMINATOR CONSIDERATIONS 110 5.1 FLIP CALCULATIONS 110 5.2 A PASSIVE/ACTIVE RWE 118 6 DISTRIBUTED FUEL AIR EXPLOSIVES 120 REFERENCES 123 TA...conventional and distributed-charge fuel- air explosive charges used in a study of the utility of distributed charge FAE systems for blast simulation. The...limited investigation of distributed charge fuel air explosive configurations for blast simulator applications. During the course of this study

Explosively driven air blast in a conical shock tube

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

Stewart, Joel B., E-mail: joel.b.stewart2.civ@mail.mil; Pecora, Collin, E-mail: collin.r.pecora.civ@mail.mil

2015-03-15

Explosively driven shock tubes present challenges in terms of safety concerns and expensive upkeep of test facilities but provide more realistic approximations to the air blast resulting from free-field detonations than those provided by gas-driven shock tubes. Likewise, the geometry of conical shock tubes can naturally approximate a sector cut from a spherically symmetric blast, leading to a better agreement with the blast profiles of free-field detonations when compared to those provided by shock tubes employing constant cross sections. The work presented in this article documents the design, fabrication, and testing of an explosively driven conical shock tube whose goalmore » was to closely replicate the blast profile seen from a larger, free-field detonation. By constraining the blast through a finite area, large blasts (which can add significant damage and safety constraints) can be simulated using smaller explosive charges. The experimental data presented herein show that a close approximation to the free-field air blast profile due to a 1.5 lb charge of C4 at 76 in. can be achieved by using a 0.032 lb charge in a 76-in.-long conical shock tube (which translates to an amplification factor of nearly 50). Modeling and simulation tools were used extensively in designing this shock tube to minimize expensive fabrication costs.« less

Model of Draining of the Blast Furnace Hearth with an Impermeable Zone

NASA Astrophysics Data System (ADS)

Saxén, Henrik

2015-02-01

Due to demands of lower costs and higher productivity in the steel industry, the volume of operating blast furnaces has grown during the last decades. As the height is limited by the allowable pressure drop, the hearth diameter has grown considerably and, along with this, also draining-related problems. In this paper a mathematical model is developed for simulating the drainage in the case where an impermeable region exists in the blast furnace hearth. The model describes the quasi-stationary drainage process of a hearth with two operating tapholes, where the communication between the two pools of molten slag and iron can be controlled by parameterized expressions. The model also considers the case where the buoyancy of the liquids is sufficient for lifting the coke bed. The implications of different size of the liquid pools, communication between the pools, bed porosity, etc. are studied by simulation, and conclusions concerning their effect on the drainage behavior and evolution of the liquid levels in the hearth are drawn. The simulated liquid levels are finally demonstrated to give rise to a pressure profile acting on the hearth which agrees qualitatively with signals from strain gauges mounted in the hearth wall of an industrial ironmaking process.

Simulation of blast-induced early-time intracranial wave physics leading to traumatic brain injury.

PubMed

Taylor, Paul A; Ford, Corey C

2009-06-01

The objective of this modeling and simulation study was to establish the role of stress wave interactions in the genesis of traumatic brain injury (TBI) from exposure to explosive blast. A high resolution (1 mm3 voxels) five material model of the human head was created by segmentation of color cryosections from the Visible Human Female data set. Tissue material properties were assigned from literature values. The model was inserted into the shock physics wave code, CTH, and subjected to a simulated blast wave of 1.3 MPa (13 bars) peak pressure from anterior, posterior, and lateral directions. Three-dimensional plots of maximum pressure, volumetric tension, and deviatoric (shear) stress demonstrated significant differences related to the incident blast geometry. In particular, the calculations revealed focal brain regions of elevated pressure and deviatoric stress within the first 2 ms of blast exposure. Calculated maximum levels of 15 KPa deviatoric, 3.3 MPa pressure, and 0.8 MPa volumetric tension were observed before the onset of significant head accelerations. Over a 2 ms time course, the head model moved only 1 mm in response to the blast loading. Doubling the blast strength changed the resulting intracranial stress magnitudes but not their distribution. We conclude that stress localization, due to early-time wave interactions, may contribute to the development of multifocal axonal injury underlying TBI. We propose that a contribution to traumatic brain injury from blast exposure, and most likely blunt impact, can occur on a time scale shorter than previous model predictions and before the onset of linear or rotational accelerations traditionally associated with the development of TBI.

Modeling and simulation of blast-induced, early-time intracranial wave physics leading to traumatic brain injury.

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

Ford, Corey C.; Taylor, Paul Allen

The objective of this modeling and simulation study was to establish the role of stress wave interactions in the genesis of traumatic brain injury (TBI) from exposure to explosive blast. A high resolution (1 mm{sup 3} voxels), 5 material model of the human head was created by segmentation of color cryosections from the Visible Human Female dataset. Tissue material properties were assigned from literature values. The model was inserted into the shock physics wave code, CTH, and subjected to a simulated blast wave of 1.3 MPa (13 bars) peak pressure from anterior, posterior and lateral directions. Three dimensional plots ofmore » maximum pressure, volumetric tension, and deviatoric (shear) stress demonstrated significant differences related to the incident blast geometry. In particular, the calculations revealed focal brain regions of elevated pressure and deviatoric (shear) stress within the first 2 milliseconds of blast exposure. Calculated maximum levels of 15 KPa deviatoric, 3.3 MPa pressure, and 0.8 MPa volumetric tension were observed before the onset of significant head accelerations. Over a 2 msec time course, the head model moved only 1 mm in response to the blast loading. Doubling the blast strength changed the resulting intracranial stress magnitudes but not their distribution. We conclude that stress localization, due to early time wave interactions, may contribute to the development of multifocal axonal injury underlying TBI. We propose that a contribution to traumatic brain injury from blast exposure, and most likely blunt impact, can occur on a time scale shorter than previous model predictions and before the onset of linear or rotational accelerations traditionally associated with the development of TBI.« less

Modeling and simulation of explosion effectiveness as a function of blast and crowd characteristics

NASA Astrophysics Data System (ADS)

Usmani, Zeeshan-Ul-Hassan

Suicide bombing has become one of the most lethal and favorite modus operandi of terrorist organizations around the world. On average, there is a suicide bombing attack every six days somewhere in the world. While various attempts have been made to assess the impact of explosions on structures and military personnel, little has been done on modeling the impact of a blast wave on a crowd in civilian settings. The assessment of an explosion's effect on a crowd can lead to better management of disasters, triage of patients, locating blast victims under the debris, development of protective gear, and safe distance recommendations to reduce the casualties. The overall goal of this work is to predict the magnitude of injuries and lethality on humans from a blast-wave with various explosive and crowd characteristics, and to compare, contrast, and analyze the performance of explosive and injury models against the real-life data of suicide bombing incidents. This thesis introduces BlastSim---a physics based stationary multi-agent simulation platform to model and simulate a suicide bombing event. The agents are constrained by the physical characteristics and mechanics of the blast wave. The BlastSim is programmed to test, analyze, and validate the results of different model combinations under various conditions with different sets of parameters, such as the crowd and explosive characteristics, blockage and human shields, fragmentation and the bomber's position, in 2-dimensional and 3-dimensional environments. The suicide bombing event can be re-created for forensic analysis. The proposed model combinations show a significant performance---the Harold Brode explosive model with Catherine Lee injury model using the blockage stands out consistently to be the best with an overall cumulative accuracy of 87.6%. When comparing against actual data, overall, prediction accuracy can be increased by 71% using this model combination. The J. Clutter with Reflection explosive model using Charles Stewart injury model with blockage works best for confined-space incidents with an accuracy of 80%. Blockage in a crowd can increase the accuracy by 17% for all models. Line-of-sight with an attacker, rushing towards an exit, announcing the threat of a suicide bombing, sitting inside a vehicle or building, and standing closer to a wall or a rigid surface were found to be the most lethal choices both during and after an attack. The findings can have implications for emergency response and counter terrorism.

A Monte Carlo Approach to Modeling the Breakup of the Space Launch System EM-1 Core Stage with an Integrated Blast and Fragment Catalogue

NASA Technical Reports Server (NTRS)

Richardson, Erin; Hays, M. J.; Blackwood, J. M.; Skinner, T.

2014-01-01

The Liquid Propellant Fragment Overpressure Acceleration Model (L-FOAM) is a tool developed by Bangham Engineering Incorporated (BEi) that produces a representative debris cloud from an exploding liquid-propellant launch vehicle. Here it is applied to the Core Stage (CS) of the National Aeronautics and Space Administration (NASA) Space Launch System (SLS launch vehicle). A combination of Probability Density Functions (PDF) based on empirical data from rocket accidents and applicable tests, as well as SLS specific geometry are combined in a MATLAB script to create unique fragment catalogues each time L-FOAM is run-tailored for a Monte Carlo approach for risk analysis. By accelerating the debris catalogue with the BEi blast model for liquid hydrogen / liquid oxygen explosions, the result is a fully integrated code that models the destruction of the CS at a given point in its trajectory and generates hundreds of individual fragment catalogues with initial imparted velocities. The BEi blast model provides the blast size (radius) and strength (overpressure) as probabilities based on empirical data and anchored with analytical work. The coupling of the L-FOAM catalogue with the BEi blast model is validated with a simulation of the Project PYRO S-IV destruct test. When running a Monte Carlo simulation, L-FOAM can accelerate all catalogues with the same blast (mean blast, 2 s blast, etc.), or vary the blast size and strength based on their respective probabilities. L-FOAM then propagates these fragments until impact with the earth. Results from L-FOAM include a description of each fragment (dimensions, weight, ballistic coefficient, type and initial location on the rocket), imparted velocity from the blast, and impact data depending on user desired application. LFOAM application is for both near-field (fragment impact to escaping crew capsule) and far-field (fragment ground impact footprint) safety considerations. The user is thus able to use statistics from a Monte Carlo set of L-FOAM catalogues to quantify risk for a multitude of potential CS destruct scenarios. Examples include the effect of warning time on the survivability of an escaping crew capsule or the maximum fragment velocities generated by the ignition of leaking propellants in internal cavities.

Transcriptional profiling in rat hair follicles following simulated Blast insult: a new diagnostic tool for traumatic brain injury.

PubMed

Zhang, Jing; Carnduff, Lisa; Norman, Grant; Josey, Tyson; Wang, Yushan; Sawyer, Thomas W; Martyniuk, Christopher J; Langlois, Valerie S

2014-01-01

With wide adoption of explosive-dependent weaponry during military activities, Blast-induced neurotrauma (BINT)-induced traumatic brain injury (TBI) has become a significant medical issue. Therefore, a robust and accessible biomarker system is in demand for effective and efficient TBI diagnosis. Such systems will also be beneficial to studies of TBI pathology. Here we propose the mammalian hair follicles as a potential candidate. An Advanced Blast Simulator (ABS) was developed to generate shock waves simulating traumatic conditions on brains of rat model. Microarray analysis was performed in hair follicles to identify the gene expression profiles that are associated with shock waves. Gene set enrichment analysis (GSEA) and sub-network enrichment analysis (SNEA) were used to identify cell processes and molecular signaling cascades affected by simulated bomb blasts. Enrichment analyses indicated that genes with altered expression levels were involved in central nervous system (CNS)/peripheral nervous system (PNS) responses as well as signal transduction including Ca2+, K+-transportation-dependent signaling, Toll-Like Receptor (TLR) signaling and Mitogen Activated Protein Kinase (MAPK) signaling cascades. Many of the pathways identified as affected by shock waves in the hair follicles have been previously reported to be TBI responsive in other organs such as brain and blood. The results suggest that the hair follicle has some common TBI responsive molecular signatures to other tissues. Moreover, various TBI-associated diseases were identified as preferentially affected using a gene network approach, indicating that the hair follicle may be capable of reflecting comprehensive responses to TBI conditions. Accordingly, the present study demonstrates that the hair follicle is a potentially viable system for rapid and non-invasive TBI diagnosis.

Transcriptional Profiling in Rat Hair Follicles following Simulated Blast Insult: A New Diagnostic Tool for Traumatic Brain Injury

PubMed Central

Zhang, Jing; Carnduff, Lisa; Norman, Grant; Josey, Tyson; Wang, Yushan; Sawyer, Thomas W.; Martyniuk, Christopher J.; Langlois, Valerie S.

2014-01-01

With wide adoption of explosive-dependent weaponry during military activities, Blast-induced neurotrauma (BINT)-induced traumatic brain injury (TBI) has become a significant medical issue. Therefore, a robust and accessible biomarker system is in demand for effective and efficient TBI diagnosis. Such systems will also be beneficial to studies of TBI pathology. Here we propose the mammalian hair follicles as a potential candidate. An Advanced Blast Simulator (ABS) was developed to generate shock waves simulating traumatic conditions on brains of rat model. Microarray analysis was performed in hair follicles to identify the gene expression profiles that are associated with shock waves. Gene set enrichment analysis (GSEA) and sub-network enrichment analysis (SNEA) were used to identify cell processes and molecular signaling cascades affected by simulated bomb blasts. Enrichment analyses indicated that genes with altered expression levels were involved in central nervous system (CNS)/peripheral nervous system (PNS) responses as well as signal transduction including Ca2+, K+-transportation-dependent signaling, Toll-Like Receptor (TLR) signaling and Mitogen Activated Protein Kinase (MAPK) signaling cascades. Many of the pathways identified as affected by shock waves in the hair follicles have been previously reported to be TBI responsive in other organs such as brain and blood. The results suggest that the hair follicle has some common TBI responsive molecular signatures to other tissues. Moreover, various TBI-associated diseases were identified as preferentially affected using a gene network approach, indicating that the hair follicle may be capable of reflecting comprehensive responses to TBI conditions. Accordingly, the present study demonstrates that the hair follicle is a potentially viable system for rapid and non-invasive TBI diagnosis. PMID:25136963

Blast optimization for improved dragline productivity

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

Humphreys, M.; Baldwin, G.

1994-12-31

A project aimed at blast optimization for large open pit coal mines is utilizing blast monitoring and analysis techniques, advanced dragline monitoring equipment, and blast simulation software, to assess the major controlling factors affecting both blast performance and subsequent dragline productivity. This has involved collaborative work between the explosives supplier, mine operator, monitoring equipment manufacturer, and a mining research organization. The results from trial blasts and subsequently monitored dragline production have yielded promising results and continuing studies are being conducted as part of a blast optimization program. It should be stressed that the optimization of blasting practices for improved draglinemore » productivity is a site specific task, achieved through controlled and closely monitored procedures. The benefits achieved at one location can not be simply transferred to another minesite unless similar improvement strategies are first implemented.« less

International Symposium on Military Applications of Blast Simulation (5th)

DTIC Science & Technology

1977-06-22

Centre d’Etudes de Grainat, Gramat , France, de- scribed their work in designing a blast simulator with a test section of 12—rn width and 7—rn height...de Gramat , Gramat , France) on the dynamic behavior of limestone. Through a series of high—pressure experiments of the type developed in the recent

Logistics Complete Round Charts: Grenades, Mines, Pyrotechnics, Rockets, Rocket Motors, Demolition Material

DTIC Science & Technology

1986-06-01

Flash 3. (342 g) Electrically Comp Actuated By Blasting Machine or Battery 5/ 8 STD 37524 Simulator, Projectile M1lSA2 0.30 7549246 MIL-S-10058 Hand...8799710 Blastin Comp (0.07 oz) Blasting (Whistle) Fuze Fuze 8-14 Frictio Friction (Burst) ’ l3AI M3A1 721 Igniter 8833721 Igniter last 5-10 8799714...8799715 iBlasti Blasting Sec FuzeN Fuze M3A1 •721 Igniter 8833721 Igniter Inst 6-10 8799714 879971 Blast Blasting See Fuze Puze N13A1 587 FrictLi 8848587

Evolution of Occupant Survivability Simulation Framework Using FEM-SPH Coupling

DTIC Science & Technology

2011-08-10

Conference (Oral only). • [5] K. Williams, et. al, “Validation of a Loading Model for Simulating Blast Mine Effects on Armoured Vehicles”, 7th...necessarily state or reflect those of the United States Government or the Department of the Army (DoA), and shall not be used for advertising or product endorsement purposes. 24

Quantifying the Effect of Fast Charger Deployments on Electric Vehicle Utility and Travel Patterns via Advanced Simulation: Preprint

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

Wood, E.; Neubauer, J.; Burton, E.

The disparate characteristics between conventional (CVs) and battery electric vehicles (BEVs) in terms of driving range, refill/recharge time, and availability of refuel/recharge infrastructure inherently limit the relative utility of BEVs when benchmarked against traditional driver travel patterns. However, given a high penetration of high-power public charging combined with driver tolerance for rerouting travel to facilitate charging on long-distance trips, the difference in utility between CVs and BEVs could be marginalized. We quantify the relationships between BEV utility, the deployment of fast chargers, and driver tolerance for rerouting travel and extending travel durations by simulating BEVs operated over real-world travel patternsmore » using the National Renewable Energy Laboratory's Battery Lifetime Analysis and Simulation Tool for Vehicles (BLAST-V). With support from the U.S. Department of Energy's Vehicle Technologies Office, BLAST-V has been developed to include algorithms for estimating the available range of BEVs prior to the start of trips, for rerouting baseline travel to utilize public charging infrastructure when necessary, and for making driver travel decisions for those trips in the presence of available public charging infrastructure, all while conducting advanced vehicle simulations that account for battery electrical, thermal, and degradation response. Results from BLAST-V simulations on vehicle utility, frequency of inserted stops, duration of charging events, and additional time and distance necessary for rerouting travel are presented to illustrate how BEV utility and travel patterns can be affected by various fast charge deployments.« less

Dispersal and fallout simulations for urban consequences management (u)

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

Grinstein, Fernando F; Wachtor, Adam J; Nelson, Matt

2010-01-01

Hazardous chemical, biological, or radioactive releases from leaks, spills, fires, or blasts, may occur (intentionally or accidentally) in urban environments during warfare or as part of terrorist attacks on military bases or other facilities. The associated contaminant dispersion is complex and semi-chaotic. Urban predictive simulation capabilities can have direct impact in many threat-reduction areas of interest, including, urban sensor placement and threat analysis, contaminant transport (CT) effects on surrounding civilian population (dosages, evacuation, shelter-in-place), education and training of rescue teams and services. Detailed simulations for the various processes involved are in principle possible, but generally not fast. Predicting urban airflowmore » accompanied by CT presents extremely challenging requirements. Crucial technical issues include, simulating turbulent fluid and particulate transport, initial and boundary condition modeling incorporating a consistent stratified urban boundary layer with realistic wind fluctuations, and post-processing of the simulation results for practical consequences management. Relevant fluid dynamic processes to be simulated include, detailed energetic and contaminant sources, complex building vortex shedding and flows in recirculation zones, and modeling of particle distributions, including particulate fallout, as well as deposition, re-suspension and evaporation. Other issues include, modeling building damage effects due to eventual blasts, addressing appropriate regional and atmospheric data reduction.« less

Blast waves and how they interact with structures.

PubMed

Cullis, I G

2001-02-01

The paper defines and describes blast waves, their interaction with a structure and its subsequent response. Explosions generate blast waves, which need not be due to explosives. A blast wave consists of two parts: a shock wave and a blast wind. The paper explains how shock waves are formed and their basic properties. The physics of blast waves is non-linear and therefore non-intuitive. To understand how an explosion generates a blast wave a numerical modelling computer code, called a hydrocode has to be employed. This is briefly explained and the cAst Eulerian hydrocode is used to illustrate the formation and propagation of the blast wave generated by a 1 kg sphere of TNT explosive detonated 1 m above the ground. The paper concludes with a discussion of the response of a structure to a blast wave and shows that this response is governed by the structures natural frequency of vibration compared to the duration of the blast wave. The basic concepts introduced are illustrated in a second simulation that introduces two structures into the blast field of the TNT charge.

Probabilistic Based Modeling and Simulation Assessment

DTIC Science & Technology

2010-06-01

different crash and blast scenarios. With the integration of the high fidelity neck and head model, a methodology to calculate the probability of injury...variability, correlation, and multiple (often competing) failure metrics. Important scenarios include vehicular collisions, blast /fragment impact, and...first area of focus is to develop a methodology to integrate probabilistic analysis into finite element analysis of vehicle collisions and blast . The

Probabilistic-Based Modeling and Simulation Assessment

DTIC Science & Technology

2010-06-01

developed to determine the relative importance of structural components of the vehicle under differnet crash and blast scenarios. With the integration of...the vehicle under different crash and blast scenarios. With the integration of the high fidelity neck and head model, a methodology to calculate the...parameter variability, correlation, and multiple (often competing) failure metrics. Important scenarios include vehicular collisions, blast /fragment

In silico investigation of blast-induced intracranial fluid cavitation as it potentially leads to traumatic brain injury

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

Haniff, S.; Taylor, P. A.

In this paper, we conducted computational macroscale simulations predicting blast-induced intracranial fluid cavitation possibly leading to brain injury. To further understanding of this problem, we developed microscale models investigating the effects of blast-induced cavitation bubble collapse within white matter axonal fiber bundles of the brain. We model fiber tracks of myelinated axons whose diameters are statistically representative of white matter. Nodes of Ranvier are modeled as unmyelinated sections of axon. Extracellular matrix envelops the axon fiber bundle, and gray matter is placed adjacent to the bundle. Cavitation bubbles are initially placed assuming an intracranial wave has already produced them. Pressuremore » pulses, of varied strengths, are applied to the upper boundary of the gray matter and propagate through the model, inducing bubble collapse. Simulations, conducted using the shock wave physics code CTH, predict an increase in pressure and von Mises stress in axons downstream of the bubbles after collapse. This appears to be the result of hydrodynamic jetting produced during bubble collapse. Interestingly, results predict axon cores suffer significantly lower shear stresses from proximal bubble collapse than does their myelin sheathing. Finally, simulations also predict damage to myelin sheathing, which, if true, degrades axonal electrical transmissibility and general health of the white matter structures in the brain.« less

In silico investigation of blast-induced intracranial fluid cavitation as it potentially leads to traumatic brain injury

DOE PAGES

Haniff, S.; Taylor, P. A.

2017-10-17

In this paper, we conducted computational macroscale simulations predicting blast-induced intracranial fluid cavitation possibly leading to brain injury. To further understanding of this problem, we developed microscale models investigating the effects of blast-induced cavitation bubble collapse within white matter axonal fiber bundles of the brain. We model fiber tracks of myelinated axons whose diameters are statistically representative of white matter. Nodes of Ranvier are modeled as unmyelinated sections of axon. Extracellular matrix envelops the axon fiber bundle, and gray matter is placed adjacent to the bundle. Cavitation bubbles are initially placed assuming an intracranial wave has already produced them. Pressuremore » pulses, of varied strengths, are applied to the upper boundary of the gray matter and propagate through the model, inducing bubble collapse. Simulations, conducted using the shock wave physics code CTH, predict an increase in pressure and von Mises stress in axons downstream of the bubbles after collapse. This appears to be the result of hydrodynamic jetting produced during bubble collapse. Interestingly, results predict axon cores suffer significantly lower shear stresses from proximal bubble collapse than does their myelin sheathing. Finally, simulations also predict damage to myelin sheathing, which, if true, degrades axonal electrical transmissibility and general health of the white matter structures in the brain.« less

In silico investigation of blast-induced intracranial fluid cavitation as it potentially leads to traumatic brain injury

NASA Astrophysics Data System (ADS)

Haniff, S.; Taylor, P. A.

2017-11-01

We conducted computational macroscale simulations predicting blast-induced intracranial fluid cavitation possibly leading to brain injury. To further understanding of this problem, we developed microscale models investigating the effects of blast-induced cavitation bubble collapse within white matter axonal fiber bundles of the brain. We model fiber tracks of myelinated axons whose diameters are statistically representative of white matter. Nodes of Ranvier are modeled as unmyelinated sections of axon. Extracellular matrix envelops the axon fiber bundle, and gray matter is placed adjacent to the bundle. Cavitation bubbles are initially placed assuming an intracranial wave has already produced them. Pressure pulses, of varied strengths, are applied to the upper boundary of the gray matter and propagate through the model, inducing bubble collapse. Simulations, conducted using the shock wave physics code CTH, predict an increase in pressure and von Mises stress in axons downstream of the bubbles after collapse. This appears to be the result of hydrodynamic jetting produced during bubble collapse. Interestingly, results predict axon cores suffer significantly lower shear stresses from proximal bubble collapse than does their myelin sheathing. Simulations also predict damage to myelin sheathing, which, if true, degrades axonal electrical transmissibility and general health of the white matter structures in the brain.

The effect of suppressors and muzzle brakes on shock wave strength

NASA Astrophysics Data System (ADS)

Phan, K. C.; Stollery, J. L.

Experimental simulations of a gun blast were performed in the course of an optimization study of shock-wave suppressor and muzzle-brake geometry. A single-spark schlieren system was used to photograph the shock waves emerging from a 32-mm shock tube. The suppressor systems tested with respect to the overpressure level included a perforated tube enclosed in an expansion chamber, a cup-and-box suppressor, and noise-absorbent materials inside a suppressor; high suppression efficiency was observed for the first two. Recoil simulation tests, performed with plain and pyramidal baffles, disk, and cylinder, show that the blast level is generally higher for a more efective muzzle brake. An optimum distance from the muzzle to the brake is suggested to be in the region of one caliber.

Mechanical assessment of grit blasting surface treatments of dental implants.

PubMed

Shemtov-Yona, K; Rittel, D; Dorogoy, A

2014-11-01

This paper investigates the influence of surface preparation treatments of dental implants on their potential (mechanical) fatigue failure, with emphasis on grit-blasting. The investigation includes limited fatigue testing of implants, showing the relationship between fatigue life and surface damage condition. Those observations are corroborated by a detailed failure analysis of retrieved fracture dental implants. In both cases, the negative effect of embedded alumina particles related to the grit-blasting process is identified. The study also comprises a numerical simulation part of the grit blasting process that reveals, for a given implant material and particle size, the existence of a velocity threshold, below which the rough surface is obtained without damage, and beyond which the creation of significant surface damage will severely reduce the fatigue life, thus increasing fracture probability. The main outcome of this work is that the overall performance of dental implants comprises, in addition to the biological considerations, mechanical reliability aspects. Fatigue fracture is a central issue, and this study shows that uncontrolled surface roughening grit-blasting treatments can induce significant surface damage which accelerate fatigue fracture under certain conditions, even if those treatments are beneficial to the osseointegration process. Copyright © 2014 Elsevier Ltd. All rights reserved.

Computational Modeling of Blast Wave Transmission Through Human Ear.

PubMed

Leckness, Kegan; Nakmali, Don; Gan, Rong Z

2018-03-01

Hearing loss has become the most common disability among veterans. Understanding how blast waves propagate through the human ear is a necessary step in the development of effective hearing protection devices (HPDs). This article presents the first 3D finite element (FE) model of the human ear to simulate blast wave transmission through the ear. The 3D FE model of the human ear consisting of the ear canal, tympanic membrane, ossicular chain, and middle ear cavity was imported into ANSYS Workbench for coupled fluid-structure interaction analysis in the time domain. Blast pressure waveforms recorded external to the ear in human cadaver temporal bone tests were applied at the entrance of the ear canal in the model. The pressure waveforms near the tympanic membrane (TM) in the canal (P1) and behind the TM in the middle ear cavity (P2) were calculated. The model-predicted results were then compared with measured P1 and P2 waveforms recorded in human cadaver ears during blast tests. Results show that the model-derived P1 waveforms were in an agreement with the experimentally recorded waveforms with statistic Kurtosis analysis. The FE model will be used for the evaluation of HPDs in future studies.

Reduced Order Modeling for Rapid Simulation of Blast Events of a Military Ground Vehicle and Its Occupants

DTIC Science & Technology

2014-08-12

deformation of the hull due to blast . An LS- Dyna model which included the ConWep function [6] was run, with a charge mass corresponding to a STANAG...different models and blast loadings are shown in Table 3. These responses are based on generic seat properties and assumed dummy position, which can be...Comparison between MADYMO and LS- Dyna models An LS- Dyna model with ConWep blast force applied to all segments of the hull floor and a MADYMO model with

Simulation of detonation cell kinematics using two-dimensional reactive blast waves

NASA Astrophysics Data System (ADS)

Thomas, G. O.; Edwards, D. H.

1983-10-01

A method of generating a cylindrical blast wave is developed which overcomes the disadvantages inherent in the converging-diverging nozzle technique used by Edwards et al., 1981. It is demonstrated than an exploding wire placed at the apex of a two-dimensional sector provides a satisfactory source of the generation of blast waves in reactive systems. The velocity profiles of the blast waves are found to simulate those in freely propagating detonations very well, and this method does not suffer from the disadvantage of having the mass flow at the throat as in the nozzle method. The density decay parameter is determined to have a constant value of 4 in the systems investigated, and it is suggested that this may be a universal value. It is proposed that suitable wedges could be used to create artificial Mach stems in the same manner as Strehlow and Barthel (1971) without the attendant disadvantages of the nozzle method.

Untangling the Effect of Head Acceleration on Brain Responses to Blast Waves

PubMed Central

Mao, Haojie; Unnikrishnan, Ginu; Rakesh, Vineet; Reifman, Jaques

2015-01-01

Multiple injury-causing mechanisms, such as wave propagation, skull flexure, cavitation, and head acceleration, have been proposed to explain blast-induced traumatic brain injury (bTBI). An accurate, quantitative description of the individual contribution of each of these mechanisms may be necessary to develop preventive strategies against bTBI. However, to date, despite numerous experimental and computational studies of bTBI, this question remains elusive. In this study, using a two-dimensional (2D) rat head model, we quantified the contribution of head acceleration to the biomechanical response of brain tissues when exposed to blast waves in a shock tube. We compared brain pressure at the coup, middle, and contre-coup regions between a 2D rat head model capable of simulating all mechanisms (i.e., the all-effects model) and an acceleration-only model. From our simulations, we determined that head acceleration contributed 36–45% of the maximum brain pressure at the coup region, had a negligible effect on the pressure at the middle region, and was responsible for the low pressure at the contre-coup region. Our findings also demonstrate that the current practice of measuring rat brain pressures close to the center of the brain would record only two-thirds of the maximum pressure observed at the coup region. Therefore, to accurately capture the effects of acceleration in experiments, we recommend placing a pressure sensor near the coup region, especially when investigating the acceleration mechanism using different experimental setups. PMID:26458125

Numerical modeling and characterization of blast waves for application in blast-induced mild traumatic brain injury research

NASA Astrophysics Data System (ADS)

Phillips, Michael G.

Human exposure to blast waves, including blast-induced traumatic brain injury, is a developing field in medical research. Experiments with explosives have many disadvantages including safety, cost, and required area for trials. Shock tubes provide an alternative method to produce free field blast wave profiles. A compressed nitrogen shock tube experiment instrumented with static and reflective pressure taps is modeled using a numerical simulation. The geometry of the numerical model is simplified and blast wave characteristics are derived based upon static and pressure profiles. The pressure profiles are analyzed along the shock tube centerline and radially away from the tube axis. The blast wave parameters found from the pressure profiles provide guidelines for spatial location of a specimen. The location could be based on multiple parameters and provides a distribution of anticipated pressure profiles experience by the specimen.

Combining Advanced Turbulent Mixing and Combustion Models with Advanced Multi-Phase CFD Code to Simulate Detonation and Post-Detonation Bio-Agent Mixing and Destruction

DTIC Science & Technology

2017-10-01

perturbations in the energetic material to study their effects on the blast wave formation. The last case also makes use of the same PBX, however, the...configuration, Case A: Spore cloud located on the top of the charge at an angle 45 degree, Case B: Spore cloud located at an angle 45 degree from the charge...theoretical validation. The first is the Sedov case where the pressure decay and blast wave front are validated based on analytical solutions. In this test

The High-Strain Rate Loading of Structural Biological Materials

NASA Astrophysics Data System (ADS)

Proud, W. G.; Nguyen, T.-T. N.; Bo, C.; Butler, B. J.; Boddy, R. L.; Williams, A.; Masouros, S.; Brown, K. A.

2015-10-01

The human body can be subjected to violent acceleration as a result of explosion caused by military ordinance or accident. Blast waves cause injury and blunt trauma can be produced by violent impact of objects against the human body. The long-term clinical manifestations of blast injury can be significantly different in nature and extent to those suffering less aggressive insult. Similarly, the damage seen in lower limbs from those injured in explosion incidents is in general more severe than those falling from height. These phenomena increase the need for knowledge of the short- and long-term effect of transient mechanical loading to the biological structures of the human body. This paper gives an overview of some of the results of collaborative investigation into blast injury. The requirement for time-resolved data, appropriate mechanical modeling, materials characterization and biological effects is presented. The use of a range of loading platforms, universal testing machines, drop weights, Hopkinson bars, and bespoke traumatic injury simulators are given.

On firework blasts and qualitative parameter dependency.

PubMed

Zohdi, T I

2016-01-01

In this paper, a mathematical model is developed to qualitatively simulate the progressive time-evolution of a blast from a simple firework. Estimates are made for the blast radius that one can expect for a given amount of detonation energy and pyrotechnic display material. The model balances the released energy from the initial blast pulse with the subsequent kinetic energy and then computes the trajectory of the material under the influence of the drag from the surrounding air, gravity and possible buoyancy. Under certain simplifying assumptions, the model can be solved for analytically. The solution serves as a guide to identifying key parameters that control the evolving blast envelope. Three-dimensional examples are given.

On firework blasts and qualitative parameter dependency

PubMed Central

Zohdi, T. I.

2016-01-01

In this paper, a mathematical model is developed to qualitatively simulate the progressive time-evolution of a blast from a simple firework. Estimates are made for the blast radius that one can expect for a given amount of detonation energy and pyrotechnic display material. The model balances the released energy from the initial blast pulse with the subsequent kinetic energy and then computes the trajectory of the material under the influence of the drag from the surrounding air, gravity and possible buoyancy. Under certain simplifying assumptions, the model can be solved for analytically. The solution serves as a guide to identifying key parameters that control the evolving blast envelope. Three-dimensional examples are given. PMID:26997903

A geophysical shock and air blast simulator at the National Ignition Facility

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

Fournier, K. B.; Brown, C. G.; May, M. J.

2014-09-15

The energy partitioning energy coupling experiments at the National Ignition Facility (NIF) have been designed to measure simultaneously the coupling of energy from a laser-driven target into both ground shock and air blast overpressure to nearby media. The source target for the experiment is positioned at a known height above the ground-surface simulant and is heated by four beams from the NIF. The resulting target energy density and specific energy are equal to those of a low-yield nuclear device. The ground-shock stress waves and atmospheric overpressure waveforms that result in our test system are hydrodynamically scaled analogs of full-scale seismicmore » and air blast phenomena. This report summarizes the development of the platform, the simulations, and calculations that underpin the physics measurements that are being made, and finally the data that were measured. Agreement between the data and simulation of the order of a factor of two to three is seen for air blast quantities such as peak overpressure. Historical underground test data for seismic phenomena measured sensor displacements; we measure the stresses generated in our ground-surrogate medium. We find factors-of-a-few agreement between our measured peak stresses and predictions with modern geophysical computer codes.« less

A geophysical shock and air blast simulator at the National Ignition Facility

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

Fournier, K. B.; Brown, C. G.; May, M. J.

2014-09-01

The energy partitioning energy coupling experiments at the National Ignition Facility (NIF) have been designed to measure simultaneously the coupling of energy from a laser-driven target into both ground shock and air blast overpressure to nearby media. The source target for the experiment is positioned at a known height above the ground-surface simulant and is heated by four beams from the NIF. The resulting target energy density and specific energy are equal to those of a low-yield nuclear device. The ground-shock stress waves and atmospheric overpressure waveforms that result in our test system are hydrodynamically scaled analogs of full-scale seismicmore » and air blast phenomena. This report summarizes the development of the platform, the simulations, and calculations that underpin the physics measurements that are being made, and finally the data that were measured. Agreement between the data and simulation of the order of a factor of two to three is seen for air blast quantities such as peak overpressure. Historical underground test data for seismic phenomena measured sensor displacements; we measure the stresses generated in our ground-surrogate medium. We find factors-of-a-few agreement between our measured peak stresses and predictions with modern geophysical computer codes.« less

Waste plastics as supplemental fuel in the blast furnace process: improving combustion efficiencies.

PubMed

Kim, Dongsu; Shin, Sunghye; Sohn, Seungman; Choi, Jinshik; Ban, Bongchan

2002-10-14

The possibility of using waste plastics as a source of secondary fuel in a blast furnace has been of recent interest. The success of this process, however, will be critically dependent upon the optimization of operating systems. For instance, the supply of waste plastics must be reliable as well as economically attractive compared with conventional secondary fuels such as heavy oil, natural gas and pulverized coal. In this work, we put special importance on the improvement of the combustibility of waste plastics as a way to enhance energy efficiency in a blast furnace. As experimental variables to approach this target, the effects of plastic particle size, blast temperature, and the level of oxygen enrichment were investigated using a custom-made blast model designed to simulate a real furnace. Lastly, the combustion efficiency of the mixture of waste plastics and pulverized coal was tested. The observations made from these experiments led us to the conclusion that with the increase of both blast temperature and the level of oxygen enrichment, and with a decrease in particle size, the combustibility of waste polyethylene could be improved at a given distance from the tuyere. Also it was found that the efficiency of coal combustion decreased with the addition of plastics; however, the combustion efficiency of mixture could be comparable at a longer distance from the tuyere.

Primary blast-induced traumatic brain injury: lessons from lithotripsy

NASA Astrophysics Data System (ADS)

Nakagawa, A.; Ohtani, K.; Armonda, R.; Tomita, H.; Sakuma, A.; Mugikura, S.; Takayama, K.; Kushimoto, S.; Tominaga, T.

2017-11-01

Traumatic injury caused by explosive or blast events is traditionally divided into four mechanisms: primary, secondary, tertiary, and quaternary blast injury. The mechanisms of blast-induced traumatic brain injury (bTBI) are biomechanically distinct and can be modeled in both in vivo and in vitro systems. The primary bTBI injury mechanism is associated with the response of brain tissue to the initial blast wave. Among the four mechanisms of bTBI, there is a remarkable lack of information regarding the mechanism of primary bTBI. On the other hand, 30 years of research on the medical application of shock waves (SWs) has given us insight into the mechanisms of tissue and cellular damage in bTBI, including both air-mediated and underwater SW sources. From a basic physics perspective, the typical blast wave consists of a lead SW followed by shock-accelerated flow. The resultant tissue injury includes several features observed in primary bTBI, such as hemorrhage, edema, pseudo-aneurysm formation, vasoconstriction, and induction of apoptosis. These are well-described pathological findings within the SW literature. Acoustic impedance mismatch, penetration of tissue by shock/bubble interaction, geometry of the skull, shear stress, tensile stress, and subsequent cavitation formation are all important factors in determining the extent of SW-induced tissue and cellular injury. In addition, neuropsychiatric aspects of blast events need to be taken into account, as evidenced by reports of comorbidity and of some similar symptoms between physical injury resulting in bTBI and the psychiatric sequelae of post-traumatic stress. Research into blast injury biophysics is important to elucidate specific pathophysiologic mechanisms of blast injury, which enable accurate differential diagnosis, as well as development of effective treatments. Herein we describe the requirements for an adequate experimental setup when investigating blast-induced tissue and cellular injury; review SW physics, research, and the importance of engineering validation (visualization/pressure measurement/numerical simulation); and, based upon our findings of SW-induced injury, discuss the potential underlying mechanisms of primary bTBI.

Brain Response to Primary Blast Wave Using Validated Finite Element Models of Human Head and Advanced Combat Helmet

PubMed Central

Zhang, Liying; Makwana, Rahul; Sharma, Sumit

2013-01-01

Blast-induced traumatic brain injury has emerged as a “signature injury” in combat casualty care. Present combat helmets are designed primarily to protect against ballistic and blunt impacts, but the current issue with helmets is protection concerning blasts. In order to delineate the blast wave attenuating capability of the Advanced Combat Helmet (ACH), a finite element (FE) study was undertaken to evaluate the head response against blast loadings with and without helmet using a partially validated FE model of the human head and ACH. Four levels of overpressures (0.27–0.66 MPa) from the Bowen’s lung iso-damage threshold curves were used to simulate blast insults. Effectiveness of the helmet with respect to head orientation was also investigated. The resulting biomechanical responses of the brain to blast threats were compared for human head with and without the helmet. For all Bowen’s cases, the peak intracranial pressures (ICP) in the head ranged from 0.68 to 1.8 MPa in the coup cortical region. ACH was found to mitigate ICP in the head by 10–35%. Helmeted head resulted in 30% lower average peak brain strains and product of strain and strain rate. Among three blast loading directions with ACH, highest reduction in peak ICP (44%) was due to backward blasts whereas the lowest reduction in peak ICP and brain strains was due to forward blast (27%). The biomechanical responses of a human head to primary blast insult exhibited directional sensitivity owing to the different geometry contours and coverage of the helmet construction and asymmetric anatomy of the head. Thus, direction-specific tolerances are needed in helmet design in order to offer omni-directional protection for the human head. The blasts of varying peak overpressures and durations that are believed to produce the same level of lung injury produce different levels of mechanical responses in the brain, and hence “iso-damage” curves for brain injury are likely different than the Bowen curves for lung injury. PMID:23935591

Design and analysis of a personnel blast shield for different explosives applications

NASA Astrophysics Data System (ADS)

Lozano, Eduardo

The use of explosives brings countless benefits to our everyday lives in areas such as mining, oil and gas exploration, demolition, and avalanche control. However, because of the potential destructive power of explosives, strict safety procedures must be an integral part of any explosives operation. The goal of this work is to provide a solution to protect against the hazards that accompany the general use of explosives, specifically in avalanche control. For this reason, a blast shield was designed and tested to protect the Colorado Department of Transportation personnel against these unpredictable effects. This document will develop a complete analysis to answer the following questions: what are the potential hazards from the detonation of high explosives, what are their effects, and how can we protect ourselves against them. To answer these questions theoretical, analytical, and numerical calculations were performed. Finally, a full blast shield prototype was tested under different simulated operational environments proving its effectiveness as safety device. The Colorado Department of Transportation currently owns more than fifteen shields that are used during every operation involving explosive materials.

Range Systems Simulation for the NASA Shuttle: Emphasis on Disaster and Prevention Management During Lift-Off

NASA Technical Reports Server (NTRS)

Rabelo, Lisa; Sepulveda, Jose; Moraga, Reinaldo; Compton, Jeppie; Turner, Robert

2005-01-01

This article describes a decision-making system composed of a number of safety and environmental models for the launch phase of a NASA Space Shuttle mission. The components of this distributed simulation environment represent the different systems that must collaborate to establish the Expectation of Casualties (E(sub c)) caused by a failed Space Shuttle launch and subsequent explosion (accidental or instructed) of the spacecraft shortly after liftoff. This decision-making tool employs Space Shuttle reliability models, trajectory models, a blast model, weather dissemination systems, population models, amount and type of toxicants, gas dispersion models, human response functions to toxicants, and a geographical information system. Since one of the important features of this proposed simulation environment is to measure blast, toxic, and debris effects, the clear benefits is that it can help safety managers not only estimate the population at risk, but also to help plan evacuations, make sheltering decisions, establish the resources required to provide aid and comfort, and mitigate damages in case of a disaster.

Computational fluid dynamics study of pulverized coal combustion in blast furnace raceway

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

Shen, Y.S.; Maldonado, D.; Guo, B.Y.

In this work, a numerical model is used to study the flow and coal combustion along the coal plume in a large-scale setting simulating the lance-blowpipe-tuyere-raceway region of a blast furnace. The model formulation is validated against the measurements in terms of burnout for both low and high volatile coals. The typical phenomena related to coal combustion along the coal plume are simulated and analyzed. The effects of some operational parameters on combustion behavior are also investigated. The results indicate that oxygen as a cooling gas gives a higher coal burnout than methane and air. The underlying mechanism of coalmore » combustion is explored. It is shown that under the conditions examined, coal burnout strongly depends on the availability of oxygen and residence time. Moreover, the influences of two related issues, i.e. the treatment of volatile matter (VM) and geometric setting in modeling, are investigated. The results show that the predictions of final burnouts using three different VM treatments are just slightly different, but all comparable to the measurements. However, the influence of the geometric setting is not negligible when numerically examining the combustion of pulverized coal under blast furnace conditions.« less

Parametric analysis of the biomechanical response of head subjected to the primary blast loading--a data mining approach.

PubMed

Zhu, Feng; Kalra, Anil; Saif, Tal; Yang, Zaihan; Yang, King H; King, Albert I

2016-01-01

Traumatic brain injury due to primary blast loading has become a signature injury in recent military conflicts and terrorist activities. Extensive experimental and computational investigations have been conducted to study the interrelationships between intracranial pressure response and intrinsic or 'input' parameters such as the head geometry and loading conditions. However, these relationships are very complicated and are usually implicit and 'hidden' in a large amount of simulation/test data. In this study, a data mining method is proposed to explore such underlying information from the numerical simulation results. The heads of different species are described as a highly simplified two-part (skull and brain) finite element model with varying geometric parameters. The parameters considered include peak incident pressure, skull thickness, brain radius and snout length. Their interrelationship and coupling effect are discovered by developing a decision tree based on the large simulation data-set. The results show that the proposed data-driven method is superior to the conventional linear regression method and is comparable to the nonlinear regression method. Considering its capability of exploring implicit information and the relatively simple relationships between response and input variables, the data mining method is considered to be a good tool for an in-depth understanding of the mechanisms of blast-induced brain injury. As a general method, this approach can also be applied to other nonlinear complex biomechanical systems.

Analysis of concrete targets with different kinds of reinforcements subjected to blast loading

NASA Astrophysics Data System (ADS)

Oña, M.; Morales-Alonso, G.; Gálvez, F.; Sánchez-Gálvez, V.; Cendón, D.

2016-05-01

In this paper we describe an experimental campaign carried out to study and analyse the behaviour of concrete slabs when subjected to blast loading. Four different types of concrete have been tested: normal strength concrete with steel rebar, normal strength concrete with steel rebar retrofitted with Kevlar coating, steel fibre reinforced concrete (SFRC) and polypropylene fibre reinforced concrete (PFRC). The major asset of the experimental setup used is that it allows to subject up to four specimens to the same blast load what, besides being cost effective, makes possible to have a measure of the experimental scatter. The results of SFRC and PFRC concretes have been analysed by using a previously developed material model for the numerical simulation of concrete elements subjected to blast. The experimental campaign and preliminary results of this numerical analysis show how the high strain rates, in spite of improving the mechanical properties of these kinds of fibre reinforced concretes, lead to an embrittlement of the material, which may be dangerous from the point of view of the structural behaviour.

Experimental Animal Models for Studies on the Mechanisms of Blast-Induced Neurotrauma

PubMed Central

Risling, Mårten; Davidsson, Johan

2012-01-01

A blast injury is a complex type of physical trauma resulting from the detonation of explosive compounds and has become an important issue due to the use of improvised explosive devices (IED) in current military conflicts. Blast-induced neurotrauma (BINT) is a major concern in contemporary military medicine and includes a variety of injuries that range from mild to lethal. Extreme forces and their complex propagation characterize BINT. Modern body protection and the development of armored military vehicles can be assumed to have changed the outcome of BINT. Primary blast injuries are caused by overpressure waves whereas secondary, tertiary, and quaternary blast injuries can have more varied origins such as the impact of fragments, abnormal movements, or heat. The characteristics of the blast wave can be assumed to be significantly different in open field detonations compared to explosions in a confined space, such an armored vehicle. Important parameters include peak pressure, duration, and shape of the pulse. Reflections from walls and armor can make the prediction of effects in individual cases very complex. Epidemiological data do not contain information of the comparative importance of the different blast mechanisms. It is therefore important to generate data in carefully designed animal models. Such models can be selective reproductions of a primary blast, penetrating injuries from fragments, acceleration movements, or combinations of such mechanisms. It is of crucial importance that the physical parameters of the employed models are well characterized so that the experiments can be reproduced in different laboratory settings. Ideally, pressure recordings should be calibrated by using the same equipment in several laboratories. With carefully designed models and thoroughly evaluated animal data it should be possible to achieve a translation of data between animal and clinical data. Imaging and computer simulation represent a possible link between experiments and studies of human cases. However, in order for mathematical simulations to be completely useful, the predictions will most likely have to be validated by detailed data from animal experiments. Some aspects of BINT can conceivably be studied in vitro. However, factors such as systemic response, brain edema, inflammation, vasospasm, or changes in synaptic transmission and behavior must be evaluated in experimental animals. Against this background, it is necessary that such animal experiments are carefully developed imitations of actual components in the blast injury. This paper describes and discusses examples of different designs of experimental models relevant to BINT. PMID:22485104

Continuum modeling of neuronal cell under blast loading

PubMed Central

Jérusalem, Antoine; Dao, Ming

2012-01-01

Traumatic brain injuries have recently been put under the spotlight as one of the most important causes of accidental brain dysfunctions. Significant experimental and modeling efforts are thus ongoing to study the associated biological, mechanical and physical mechanisms. In the field of cell mechanics, progresses are also being made at the experimental and modeling levels to better characterize many of the cell functions such as differentiation, growth, migration and death, among others. The work presented here aims at bridging both efforts by proposing a continuum model of neuronal cell submitted to blast loading. In this approach, cytoplasm, nucleus and membrane (plus cortex) are differentiated in a representative cell geometry, and different material constitutive models are adequately chosen for each one. The material parameters are calibrated against published experimental work of cell nanoindentation at multiple rates. The final cell model is ultimately subjected to blast loading within a complete fluid-structure interaction computational framework. The results are compared to the nanoindentation simulation and the specific effects of the blast wave on the pressure and shear levels at the interfaces are identified. As a conclusion, the presented model successfully captures some of the intrinsic intracellular phenomena occurring during its deformation under blast loading and potentially leading to cell damage. It suggests more particularly the localization of damage at the nucleus membrane similarly to what has already been observed at the overall cell membrane. This degree of damage is additionally predicted to be worsened by a longer blast positive phase duration. As a conclusion, the proposed model ultimately provides a new three dimensional computational tool to evaluate intracellular damage during blast loading. PMID:22562014

Multiphase-flow numerical modeling of the 18 May 1980 lateral blast at Mount St. Helens, USA

USGS Publications Warehouse

Ongaro, T.E.; Widiwijayanti, C.; Clarke, A.B.; Voight, B.; Neri, A.

2011-01-01

Volcanic lateral blasts are among the most spectacular and devastating of natural phenomena, but their dynamics are still poorly understood. Here we investigate the best documented and most controversial blast at Mount St. Helens (Washington State, United States), on 18 May 1980. By means of three-dimensional multiphase numerical simulations we demonstrate that the blast front propagation, fi nal runout, and damage can be explained by the emplacement of an unsteady, stratifi ed pyroclastic density current, controlled by gravity and terrain morphology. Such an interpretation is quantitatively supported by large-scale observations at Mount St. Helens and will infl uence the defi nition and predictive mapping of hazards on blast-dangerous volcanoes worldwide. ?? 2011 Geological Society of America.

Brain Vulnerability to Repeated Blast Overpressure and Polytrauma

DTIC Science & Technology

2015-10-01

characterization of the mouse model of repeated blast also found no cumula- tive effect of repeated blast on cortical levels of reactive oxygen species [39]. C...overpressure in rats to investigate the cumulative effects of multiple blast exposures on neurologic status, neurobehavioral function, and brain...preclinical model of blast overpressure in rats to investigate the cumulative effects of multiple blast exposures using neurological, neurochemical

A new high-performance 3D multiphase flow code to simulate volcanic blasts and pyroclastic density currents: example from the Boxing Day event, Montserrat

NASA Astrophysics Data System (ADS)

Ongaro, T. E.; Clarke, A.; Neri, A.; Voight, B.; Widiwijayanti, C.

2005-12-01

For the first time the dynamics of directed blasts from explosive lava-dome decompression have been investigated by means of transient, multiphase flow simulations in 2D and 3D. Multiphase flow models developed for the analysis of pyroclastic dispersal from explosive eruptions have been so far limited to 2D axisymmetric or Cartesian formulations which cannot properly account for important 3D features of the volcanic system such as complex morphology and fluid turbulence. Here we use a new parallel multiphase flow code, named PDAC (Pyroclastic Dispersal Analysis Code) (Esposti Ongaro et al., 2005), able to simulate the transient and 3D thermofluid-dynamics of pyroclastic dispersal produced by collapsing columns and volcanic blasts. The code solves the equations of the multiparticle flow model of Neri et al. (2003) on 3D domains extending up to several kilometres in 3D and includes a new description of the boundary conditions over topography which is automatically acquired from a DEM. The initial conditions are represented by a compact volume of gas and pyroclasts, with clasts of different sizes and densities, at high temperature and pressure. Different dome porosities and pressurization models were tested in 2D to assess the sensitivity of the results to the distribution of initial gas pressure, and to the total mass and energy stored in the dome, prior to 3D modeling. The simulations have used topographies appropriate for the 1997 Boxing Day directed blast on Montserrat, which eradicated the village of St. Patricks. Some simulations tested the runout of pyroclastic density currents over the ocean surface, corresponding to observations of over-water surges to several km distances at both locations. The PDAC code was used to perform 3D simulations of the explosive event on the actual volcano topography. The results highlight the strong topographic control on the propagation of the dense pyroclastic flows, the triggering of thermal instabilities, and the elutriation of finest particles, and demonstrated the formation of dense pyroclastic flows by drainage of clasts sedimented from dilute flows. Fundamental and accurate hazard information can be obtained from the simulations, and the 3D displays are readily comprehended by officials and the public, making them very effective tools for risk mitigation.

Methodology and evaluation of intracranial pressure response in rats exposed to complex shock waves.

PubMed

Dal Cengio Leonardi, Alessandra; Keane, Nickolas J; Hay, Kathryn; Ryan, Anne G; Bir, Cynthia A; VandeVord, Pamela J

2013-12-01

Studies on blast neurotrauma have focused on investigating the effects of exposure to free-field blast representing the simplest form of blast threat scenario without considering any reflecting surfaces. However, in reality personnel are often located within enclosures or nearby reflecting walls causing a complex blast environment, that is, involving shock reflections and/or compound waves from different directions. The purpose of this study was to design a complex wave testing system and perform a preliminary investigation of the intracranial pressure (ICP) response of rats exposed to a complex blast wave environment (CBWE). The effects of head orientation in the same environment were also explored. Furthermore, since it is hypothesized that exposure to a CBWE would be more injurious as compared to a free-field blast wave environment (FFBWE), a histological comparison of hippocampal injury (cleaved caspase-3 and glial fibrillary acidic protein (GFAP)) was conducted in both environments. Results demonstrated that, regardless of orientation, peak ICP values were significantly elevated over the peak static air overpressure. Qualitative differences could be noticed compared to the ICP response in rats exposed to simulated FFBWE. In the CBWE scenario, after the initial loading the skull/brain system was not allowed to return to rest and was loaded again reaching high ICP values. Furthermore, results indicated consistent and distinct ICP-time profiles according to orientation, as well as distinctive values of impulse associated with each orientation. Histologically, cleaved caspase-3 positive cells were significantly increased in the CBWE as compared to the FFBWE. Overall, these findings suggest that the geometry of the skull and the way sutures are distributed in the rats are responsible for the difference in the stresses observed. Moreover, this increase stress contributes to correlation of increased injury in the CBWE.

Experimental study and simulation of phosphorus purification effects of bioretention systems on urban surface runoff

PubMed Central

Liang, Zheng; Li, Yajiao; Li, Peng; Jiang, Chunbo

2018-01-01

Excessive phosphorus (P) contributes to eutrophication by degrading water quality and limiting human use of water resources. Identifying economic and convenient methods to control soluble reactive phosphorus (SRP) pollution in urban runoff is the key point of rainwater management strategies. Through three series of different tests involving influencing factors, continuous operation and intermittent operation, this study explored the purification effects of bioretention tanks under different experimental conditions, it included nine intermittent tests, single field continuous test with three groups of different fillers (Fly ash mixed with sand, Blast furnace slag, and Soil), and eight intermittent tests with single filler (Blast furnace slag mixed with sand). Among the three filler combinations studied, the filler with fly ash mixed with sand achieved the best pollution reduction efficiency. The setting of the submerged zone exerted minimal influence on the P removal of the three filler combinations. An extension of the dry period slightly promoted the P purification effect. The combination of fly ash mixed with sand demonstrated a positive purification effect on SRP during short- or long-term simulated rainfall duration. Blast furnace slag also presented a positive purification effect in the short term, although its continuous purification effect on SRP was poor in the long term. The purification abilities of soil in the short and long terms were weak. Under intermittent operations across different seasons, SRP removal was unstable, and effluent concentration processes were different. The purification effect of the bioretention system on SRP was predicted through partial least squares regression (PLS) modeling analysis. The event mean concentration removal of SRP was positively related to the adsorption capacity of filler and rainfall interval time and negatively related to submerged zones, influent concentration and volume. PMID:29742120

Fragment Size Distribution of Blasted Rock Mass

NASA Astrophysics Data System (ADS)

Jug, Jasmin; Strelec, Stjepan; Gazdek, Mario; Kavur, Boris

2017-12-01

Rock mass is a heterogeneous material, and the heterogeneity of rock causes sizes distribution of fragmented rocks in blasting. Prediction of blasted rock mass fragmentation has a significant role in the overall economics of opencast mines. Blasting as primary fragmentation can significantly decrease the cost of loading, transport, crushing and milling operations. Blast fragmentation chiefly depends on the specific blast design (geometry of blast holes drilling, the quantity and class of explosive, the blasting form, the timing and partition, etc.) and on the properties of the rock mass (including the uniaxial compressive strength, the rock mass elastic Young modulus, the rock discontinuity characteristics and the rock density). Prediction and processing of blasting results researchers can accomplish by a variety of existing software’s and models, one of them is the Kuz-Ram model, which is possibly the most widely used approach to estimating fragmentation from blasting. This paper shows the estimation of fragmentation using the "SB" program, which was created by the authors. Mentioned program includes the Kuz-Ram model. Models of fragmentation are confirmed and calibrated by comparing the estimated fragmentation with actual post-blast fragmentation from image processing techniques. In this study, the Kuz-Ram fragmentation model has been used for an open-pit limestone quarry in Dalmatia, southern Croatia. The resulting calibrated value of the rock factor enables the quality prognosis of fragmentation in further blasting works, with changed drilling geometry and blast design parameters. It also facilitates simulation in the program to optimize blasting works and get the desired fragmentations of the blasted rock mass.

Numerical Simulation of Quarry Blast Sources

DTIC Science & Technology

1993-01-01

Phillips Laboratory (PL/PKVA) AGENCY REPORT NUMBER 3701 N. Fairfax Dr. #717 3651 Lowry Avenue, SE Arlington, VA 2203-1714 Kirtland, AFB, NM 87117...Freeman and Company, San Francisco. Smith, A. T. (1992), "Discrimination of Explosions from Simultaneous Mining Blasts," Lawrence Livermore Report UCRL

Sensitivity of Particle Size in Discrete Element Method to Particle Gas Method (DEM_PGM) Coupling in Underbody Blast Simulations

DTIC Science & Technology

2016-06-12

Particle Size in Discrete Element Method to Particle Gas Method (DEM_PGM) Coupling in Underbody Blast Simulations Venkatesh Babu, Kumar Kulkarni, Sanjay...buried in soil viz., (1) coupled discrete element & particle gas methods (DEM-PGM) and (2) Arbitrary Lagrangian-Eulerian (ALE), are investigated. The...DEM_PGM and identify the limitations/strengths compared to the ALE method. Discrete Element Method (DEM) can model individual particle directly, and

Explosion/Blast Dynamics for Constellation Launch Vehicles Assessment

NASA Technical Reports Server (NTRS)

Baer, Mel; Crawford, Dave; Hickox, Charles; Kipp, Marlin; Hertel, Gene; Morgan, Hal; Ratzel, Arthur; Cragg, Clinton H.

2009-01-01

An assessment methodology is developed to guide quantitative predictions of adverse physical environments and the subsequent effects on the Ares-1 crew launch vehicle associated with the loss of containment of cryogenic liquid propellants from the upper stage during ascent. Development of the methodology is led by a team at Sandia National Laboratories (SNL) with guidance and support from a number of National Aeronautics and Space Administration (NASA) personnel. The methodology is based on the current Ares-1 design and feasible accident scenarios. These scenarios address containment failure from debris impact or structural response to pressure or blast loading from an external source. Once containment is breached, the envisioned assessment methodology includes predictions for the sequence of physical processes stemming from cryogenic tank failure. The investigative techniques, analysis paths, and numerical simulations that comprise the proposed methodology are summarized and appropriate simulation software is identified in this report.

Rapid Simulation of Blast Wave Propagation in Built Environments Using Coarse-Grain Based Intelligent Modeling Methods

DTIC Science & Technology

2011-04-01

experiments was performed using an artificial neural network to try to capture the nonlinearities. The radial Gaussian artificial neural network system...Modeling Blast-Wave Propagation using Artificial Neural Network Methods‖, in International Journal of Advanced Engineering Informatics, Elsevier

Numerical Study of the Reduction Process in an Oxygen Blast Furnace

NASA Astrophysics Data System (ADS)

Zhang, Zongliang; Meng, Jiale; Guo, Lei; Guo, Zhancheng

2016-02-01

Based on computational fluid dynamics, chemical reaction kinetics, principles of transfer in metallurgy, and other principles, a multi-fluid model for a traditional blast furnace was established. The furnace conditions were simulated with this multi-fluid mathematical model, and the model was verified with the comparison of calculation and measurement. Then a multi-fluid model for an oxygen blast furnace in the gasifier-full oxygen blast furnace process was established based on this traditional blast furnace model. With the established multi-fluid model for an oxygen blast furnace, the basic characteristics of iron ore reduction process in the oxygen blast furnace were summarized, including the changing process of the iron ore reduction degree and the compositions of the burden, etc. The study found that compared to the traditional blast furnace, the magnetite reserve zone in the furnace shaft under oxygen blast furnace condition was significantly reduced, which is conducive to the efficient operation of blast furnace. In order to optimize the oxygen blast furnace design and operating parameters, the iron ore reduction process in the oxygen blast furnace was researched under different shaft tuyere positions, different recycling gas temperatures, and different allocation ratios of recycling gas between the hearth tuyere and the shaft tuyere. The results indicate that these three factors all have a substantial impact on the ore reduction process in the oxygen blast furnace. Moderate shaft tuyere position, high recycling gas temperature, and high recycling gas allocation ratio between hearth and shaft could significantly promote the reduction of iron ore, reduce the scope of the magnetite reserve zone, and improve the performance of oxygen blast furnace. Based on the above findings, the recommendations for improvement of the oxygen blast furnace design and operation were proposed.

Modular Simulation of HEI Fragments and Blast Pressure.

DTIC Science & Technology

1992-03-01

TEU04D MODULAR SIMULATION OF Accesion For HEI FRAGMENTS AND BLAST PRESSURE NTIS CRAMI DTIC TAB 1] THESIS U.a:’ ouIced Jusification Gordon Galloway C... sustained by a component due to disturbances cre- ated in the medium surrounding the component when no fragment im- pacts are possible. In general, a...component will sustain a maximum kill if located within a minimum range from the burst point [RB(MAX)], and will sustain no damage if it is located beyond a

Blast effect on the lower extremities and its mitigation: a computational study.

PubMed

Dong, Liqiang; Zhu, Feng; Jin, Xin; Suresh, Mahi; Jiang, Binhui; Sevagan, Gopinath; Cai, Yun; Li, Guangyao; Yang, King H

2013-12-01

A series of computational studies were performed to investigate the response of the lower extremities of mounted soldiers under landmine detonation. A numerical human body model newly developed at Wayne State University was used to simulate two types of experimental studies and the model predictions were validated against test data in terms of the tibia axial force as well as bone fracture pattern. Based on the validated model, the minimum axial force causing tibia facture was found. Then a series of parametric studies was conducted to determine the critical velocity (peak velocity of the floor plate) causing tibia fracture at different upper/lower leg angles. In addition, to limit the load transmission through the vehicular floor, two types of energy absorbing materials, namely IMPAXX(®) foam and aluminum alloy honeycomb, were selected for floor matting. Their performances in terms of blast effect mitigation were compared using the validated numerical model, and it has been found that honeycomb is a more efficient material for blast injury prevention under the loading conditions studied. © 2013 Elsevier Ltd. All rights reserved.

A Direct Numerical Simulation of a Temporally Evolving Liquid-Gas Turbulent Mixing Layer

NASA Astrophysics Data System (ADS)

Vu, Lam Xuan; Chiodi, Robert; Desjardins, Olivier

2017-11-01

Air-blast atomization occurs when streams of co-flowing high speed gas and low speed liquid shear to form drops. Air-blast atomization has numerous industrial applications from combustion engines in jets to sprays used for medical coatings. The high Reynolds number and dynamic pressure ratio of a realistic air-blast atomization case requires large eddy simulation and the use of multiphase sub-grid scale (SGS) models. A direct numerical simulations (DNS) of a temporally evolving mixing layer is presented to be used as a base case from which future multiphase SGS models can be developed. To construct the liquid-gas mixing layer, half of a channel flow from Kim et al. (JFM, 1987) is placed on top of a static liquid layer that then evolves over time. The DNS is performed using a conservative finite volume incompressible multiphase flow solver where phase tracking is handled with a discretely conservative volume of fluid method. This study presents statistics on velocity and volume fraction at different Reynolds and Weber numbers.

Simulating maar-diatreme volcanic systems in bench-scale experiments

NASA Astrophysics Data System (ADS)

Andrews, R. G.; White, J. D. L.; Dürig, T.; Zimanowski, B.

2015-12-01

Maar-diatreme eruptions are incompletely understood, and explanations for the processes involved in them have been debated for decades. This study extends bench-scale analogue experiments previously conducted on maar-diatreme systems and attempts to scale the results up to both field-scale experimentation and natural volcanic systems in order to produce a reconstructive toolkit for maar volcanoes. These experimental runs produced via multiple mechanisms complex deposits that match many features seen in natural maar-diatreme deposits. The runs include deeper single blasts, series of descending discrete blasts, and series of ascending blasts. Debris-jet inception and diatreme formation are indicated by this study to involve multiple types of granular fountains within diatreme deposits produced under varying initial conditions. The individual energies of blasts in multiple-blast series are not possible to infer from the final deposits. The depositional record of blast sequences can be ascertained from the proportion of fallback sedimentation versus maar ejecta rim material, the final crater size and the degree of overturning or slumping of accessory strata. Quantitatively, deeper blasts involve a roughly equal partitioning of energy into crater excavation energy versus mass movement of juvenile material, whereas shallower blasts expend a much greater proportion of energy in crater excavation.

Rapid condition assessment of structural condition after a blast using state-space identification

NASA Astrophysics Data System (ADS)

Eskew, Edward; Jang, Shinae

2015-04-01

After a blast event, it is important to quickly quantify the structural damage for emergency operations. In order improve the speed, accuracy, and efficiency of condition assessments after a blast, the authors have previously performed work to develop a methodology for rapid assessment of the structural condition of a building after a blast. The method involved determining a post-event equivalent stiffness matrix using vibration measurements and a finite element (FE) model. A structural model was built for the damaged structure based on the equivalent stiffness, and inter-story drifts from the blast are determined using numerical simulations, with forces determined from the blast parameters. The inter-story drifts are then compared to blast design conditions to assess the structures damage. This method still involved engineering judgment in terms of determining significant frequencies, which can lead to error, especially with noisy measurements. In an effort to improve accuracy and automate the process, this paper will look into a similar method of rapid condition assessment using subspace state-space identification. The accuracy of the method will be tested using a benchmark structural model, as well as experimental testing. The blast damage assessments will be validated using pressure-impulse (P-I) diagrams, which present the condition limits across blast parameters. Comparisons between P-I diagrams generated using the true system parameters and equivalent parameters will show the accuracy of the rapid condition based blast assessments.

Blast overpressure in rats: recreating a battlefield injury in the laboratory.

PubMed

Long, Joseph B; Bentley, Timothy L; Wessner, Keith A; Cerone, Carolyn; Sweeney, Sheena; Bauman, Richard A

2009-06-01

Blast injury to the brain is the predominant cause of neurotrauma in current military conflicts, and its etiology is largely undefined. Using a compression-driven shock tube to simulate blast effects, we assessed the physiological, neuropathological, and neurobehavioral consequences of airblast exposure, and also evaluated the effect of a Kevlar protective vest on acute mortality in rats and on the occurrence of traumatic brain injury (TBI) in those that survived. This approach provides survivable blast conditions under which TBI can be studied. Striking neuropathological changes were caused by both 126- and 147-kPa airblast exposures. The Kevlar vest, which encased the thorax and part of the abdomen, greatly reduced airblast mortality, and also ameliorated the widespread fiber degeneration that was prominent in brains of rats not protected by a vest during exposure to a 126-kPa airblast. This finding points to a significant contribution of the systemic effects of airblast to its brain injury pathophysiology. Airblast of this intensity also disrupted neurologic and neurobehavioral performance (e.g., beam walking and spatial navigation acquisition in the Morris water maze). When immediately followed by hemorrhagic hypotension, with MAP maintained at 30 mm Hg, airblast disrupted cardiocompensatory resilience, as reflected by reduced peak shed blood volume, time to peak shed blood volume, and time to death. These findings demonstrate that shock tube-generated airblast can cause TBI in rats, in part through systemic mediation, and that the resulting brain injury significantly impacts acute cardiovascular homeostatic mechanisms as well as neurobehavioral function.

The comparative behaviour of two combat boots under impact.

PubMed

Newell, Nicolas; Masouros, Spyros D; Pullen, Andy D; Bull, Anthony M J

2012-04-01

Improvised explosive devices have become the characteristic weapon of conflicts in Iraq and Afghanistan. While little can be done to mitigate against the effects of blast in free-field explosions, scaled blast simulations have shown that the combat boot can attenuate the effects on the vehicle occupants of anti-vehicular mine blasts. Although the combat boot offers some protection to the lower limb, its behaviour at the energies seen in anti-vehicular mine blast has not been documented previously. The sole of eight same-size combat boots from two brands currently used by UK troops deployed to Iraq and Afghanistan were impacted at energies of up to 518 J, using a spring-assisted drop rig. The results showed that the Meindl Desert Fox combat boot consistently experienced a lower peak force at lower impact energies and a longer time-to-peak force at higher impact energies when compared with the Lowa Desert Fox combat boot. This reduction in the peak force and extended rise time, resulting in a lower energy transfer rate, is a potentially positive mitigating effect in terms of the trauma experienced by the lower limb. Currently, combat boots are tested under impact at the energies seen during heel strike in running. Through the identification of significantly different behaviours at high loading, this study has shown that there is rationale in adding the performance of combat boots under impact at energies above those set out in international standards to the list of criteria for the selection of a combat boot.

Premature detonation of an NH₄NO₃ emulsion in reactive ground.

PubMed

Priyananda, Pramith; Djerdjev, Alex M; Gore, Jeff; Neto, Chiara; Beattie, James K; Hawkett, Brian S

2015-01-01

When NH4NO3 emulsions are used in blast holes containing pyrite, they can exothermally react with pyrite, causing the emulsion to intensively heat and detonate prematurely. Such premature detonations can inflict fatal and very costly damages. The mechanism of heating of the emulsions is not well understood though such an understanding is essential for designing safe blasting. In this study the heating of an emulsion in model blast holes was simulated by solving the heat equation. The physical factors contributing to the heating phenomenon were studied using microscopic and calorimetric methods. Microscopic studies revealed the continuous formation of a large number of gas bubbles as the reaction progressed at the emulsion-pyrite interface, which made the reacting emulsion porous. Calculations show that the increase in porosity causes the thermal conductivity of a reacting region of an emulsion column in a blast hole to decrease exponentially. This large reduction in the thermal conductivity retards heat dissipation from the reacting region causing its temperature to rise. The rise in temperature accelerates the exothermic reaction producing more heat. Simulations predict a migration of the hottest spot of the emulsion column, which could dangerously heat the primers and boosters located in the blast hole. Copyright © 2014 Elsevier B.V. All rights reserved.

Blast-Wave Generation and Propagation in Rapidly Heated Laser-Irradiated Targets

NASA Astrophysics Data System (ADS)

Ivancic, S. T.; Stillman, C. R.; Nilson, P. M.; Solodov, A. A.; Froula, D. H.

2017-10-01

Time-resolved extreme ultraviolet (XUV) spectroscopy was used to study the creation and propagation of a >100-Mbar blast wave in a target irradiated by an intense (>1018WWcm2 cm2) laser pulse. Blast waves provide a platform to generate immense pressures in the laboratory. A temporal double flash of XUV radiation was observed when viewing the rear side of the target, which is attributed to the emergence of a blast wave following rapid heating by a fast-electron beam generated from the laser pulse. The time-history of XUV emission in the photon energy range of 50 to 200 eV was recorded with an x-ray streak camera with 7-ps temporal resolution. The heating and expansion of the target was simulated with an electron transport code coupled to 1-D radiation-hydrodynamics simulations. The temporal delay between the two flashes measured in a systematic study of target thickness and composition was found to evolve in good agreement with a Sedov-Taylor blast-wave solution. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and Department of Energy Office of Science Award Number DE-SC-0012317.

Self-similar relativistic blast waves with energy injection

NASA Astrophysics Data System (ADS)

van Eerten, Hendrik

2014-08-01

A sufficiently powerful astrophysical source with power-law luminosity in time will give rise to a self-similar relativistic blast wave with a reverse shock travelling into the ejecta and a forward shock moving into the surrounding medium. Once energy injection ceases and the last energy is delivered to the shock front, the blast wave will transit into another self-similar stage depending only on the total amount of energy injected. I describe the effect of limited duration energy injection into environments with density depending on radius as a power law, emphasizing optical/X-ray Gamma-ray Burst afterglows as applications. The blast wave during injection is treated analytically, the transition following last energy injection with one-dimensional simulations. Flux equations for synchrotron emission from the forward and reverse shock regions are provided. The reverse shock emission can easily dominate, especially with different magnetizations for both regions. Reverse shock emission is shown to support both the reported X-ray and optical correlations between afterglow plateau duration and end time flux, independently of the luminosity power-law slope. The model is demonstrated by application to bursts 120521A and 090515, and can accommodate their steep post-plateau light-curve slopes.

No Flares from Gamma-Ray Burst Afterglow Blast Waves Encountering Sudden Circumburst Density Change

NASA Astrophysics Data System (ADS)

Gat, Ilana; van Eerten, Hendrik; MacFadyen, Andrew

2013-08-01

Afterglows of gamma-ray bursts are observed to produce light curves with the flux following power-law evolution in time. However, recent observations reveal bright flares at times on the order of minutes to days. One proposed explanation for these flares is the interaction of a relativistic blast wave with a circumburst density transition. In this paper, we model this type of interaction computationally in one and two dimensions, using a relativistic hydrodynamics code with adaptive mesh refinement called RAM, and analytically in one dimension. We simulate a blast wave traveling in a stellar wind environment that encounters a sudden change in density, followed by a homogeneous medium, and compute the observed radiation using a synchrotron model. We show that flares are not observable for an encounter with a sudden density increase, such as a wind termination shock, nor for an encounter with a sudden density decrease. Furthermore, by extending our analysis to two dimensions, we are able to resolve the spreading, collimation, and edge effects of the blast wave as it encounters the change in circumburst medium. In all cases considered in this paper, we find that a flare will not be observed for any of the density changes studied.

Acceleration from short-duration blast

NASA Astrophysics Data System (ADS)

Ritzel, D. V.; Van Albert, S.; Sajja, V.; Long, J.

2018-01-01

The blast-induced motion of spheres has been studied experimentally where the shock wave is rapidly decaying during the period that quasi-steady acceleration would be developed in the case of a step-function shock wave as considered in most shock-tube studies. The motion of sphere models ranging from 39 to 251 mm in diameter and having a range of densities was assessed using the "free-flight" method in a simulator specially designed to replicate the decaying shock wave profile of spherical blast including negative phase and positive entropy gradient. A standardized blast-wave simulation of 125 kPa and 6-ms positive-phase duration was applied for all experiments. In all cases, there are three phases to the motion: a relatively low "kickoff" velocity from the shock diffraction, acceleration or deceleration during the positive duration, then deceleration through the negative phase and subsequent quiescent air. The unexpected deceleration of larger spheres after their kickoff velocity during the decaying yet high-speed flow of the blast wave seems associated with the persistence of a ring vortex on the downstream side of the sphere. The flow is entirely unsteady with initial forces dominated by the shock diffraction; therefore, the early motion of spheres under such conditions is not governed by quasi-steady drag as in classical aerodynamics. The work will help establish scaling rules for model studies of blast-induced motion relevant to improvised explosive devices, and preliminary results are shown for motion imparted to a human skull surrogate.

Mabs monograph, air blast instrumentation, 1943-1993 measurement techniques and instrumentation. Volume 1. The nuclear era. 1945-1963. Technical report, 17 September 1992-31 May 1994

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

Reisler, R.E.; Keefer, J.H.; Ethridge, N.H.

1995-03-01

Blast wave measurement techniques and instrumentation developed by Military Applications of Blast Simulators (MABS) participating countries to study blast phenomena during the nuclear era are summarized. Passive and active gages both mechanical self-recording and electronic systems deployed on kiloton and megaton explosive tests during the period 1945-1963 are presented. The country and the year the gage was introduced are included with the description. References are also provided. Volume 2 covers measurement techniques and instrumentation for the period 1959-1993 and Volume 3 covers structural target and gage calibration from 1943 to 1993.

The effect of cosmic-ray acceleration on supernova blast wave dynamics

NASA Astrophysics Data System (ADS)

Pais, M.; Pfrommer, C.; Ehlert, K.; Pakmor, R.

2018-05-01

Non-relativistic shocks accelerate ions to highly relativistic energies provided that the orientation of the magnetic field is closely aligned with the shock normal (quasi-parallel shock configuration). In contrast, quasi-perpendicular shocks do not efficiently accelerate ions. We model this obliquity-dependent acceleration process in a spherically expanding blast wave setup with the moving-mesh code AREPO for different magnetic field morphologies, ranging from homogeneous to turbulent configurations. A Sedov-Taylor explosion in a homogeneous magnetic field generates an oblate ellipsoidal shock surface due to the slower propagating blast wave in the direction of the magnetic field. This is because of the efficient cosmic ray (CR) production in the quasi-parallel polar cap regions, which softens the equation of state and increases the compressibility of the post-shock gas. We find that the solution remains self-similar because the ellipticity of the propagating blast wave stays constant in time. This enables us to derive an effective ratio of specific heats for a composite of thermal gas and CRs as a function of the maximum acceleration efficiency. We finally discuss the behavior of supernova remnants expanding into a turbulent magnetic field with varying coherence lengths. For a maximum CR acceleration efficiency of about 15 per cent at quasi-parallel shocks (as suggested by kinetic plasma simulations), we find an average efficiency of about 5 per cent, independent of the assumed magnetic coherence length.

Effects of Low-Level Blast Exposure on the Nervous System: Is There Really a Controversy?

PubMed Central

Elder, Gregory A.; Stone, James R.; Ahlers, Stephen T.

2014-01-01

High-pressure blast waves can cause extensive CNS injury in human beings. However, in combat settings, such as Iraq and Afghanistan, lower level exposures associated with mild traumatic brain injury (mTBI) or subclinical exposure have been much more common. Yet controversy exists concerning what traits can be attributed to low-level blast, in large part due to the difficulty of distinguishing blast-related mTBI from post-traumatic stress disorder (PTSD). We describe how TBI is defined in human beings and the problems posed in using current definitions to recognize blast-related mTBI. We next consider the problem of applying definitions of human mTBI to animal models, in particular that TBI severity in human beings is defined in relation to alteration of consciousness at the time of injury, which typically cannot be assessed in animals. However, based on outcome assessments, a condition of “low-level” blast exposure can be defined in animals that likely approximates human mTBI or subclinical exposure. We review blast injury modeling in animals noting that inconsistencies in experimental approach have contributed to uncertainty over the effects of low-level blast. Yet, animal studies show that low-level blast pressure waves are transmitted to the brain. In brain, low-level blast exposures cause behavioral, biochemical, pathological, and physiological effects on the nervous system including the induction of PTSD-related behavioral traits in the absence of a psychological stressor. We review the relationship of blast exposure to chronic neurodegenerative diseases noting the paradoxical lowering of Abeta by blast, which along with other observations suggest that blast-related TBI is pathophysiologically distinct from non-blast TBI. Human neuroimaging studies show that blast-related mTBI is associated with a variety of chronic effects that are unlikely to be explained by co-morbid PTSD. We conclude that abundant evidence supports low-level blast as having long-term effects on the nervous system. PMID:25566175

Mabs monograph air blast instrumentation, 1943 - 1993. Measurement techniques and instrumentation. Volume 3. Air blast structural target and gage calibration. Technical report, 17 September 1993-31 May 1994, FLD04

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

Reisler, R.E.; Keefer, J.H.; Ethridge, N.H.

1995-08-01

Structural response measurement techniques and instrumentation developed by Military Applications of Blast Simulators (MABS) participating countries for field tests over the period 1943 through 1993 are summarized. Electronic and non-electronic devices deployed on multi-ton nuclear and high-explosive events are presented with calibration techniques. The country and the year the gage was introduced are included with the description. References for each are also provided.

Low-Level Blast Exposure Increases Transient Receptor Potential Vanilloid 1 (TRPV1) Expression in the Rat Cornea

PubMed Central

Por, Elaine D.; Choi, Jae-Hyek; Lund, Brian J.

2016-01-01

ABSTRACT Background: Blast-related ocular injuries sustained by military personnel have led to rigorous efforts to elucidate the effects of blast exposure on neurosensory function. Recent studies have provided some insight into cognitive and visual deficits sustained following blast exposure; however, limited data are available on the effects of blast on pain and inflammatory processes. Investigation of these secondary effects of blast exposure is necessary to fully comprehend the complex pathophysiology of blast-related injuries. The overall purpose of this study is to determine the effects of single and repeated blast exposure on pain and inflammatory mediators in ocular tissues. Methods: A compressed air shock tube was used to deliver a single or repeated blast (68.0 ± 2.7 kPa) to anesthetized rats daily for 5 days. Immunohistochemistry was performed on ocular tissues to determine the expression of the transient receptor potential vanilloid 1 (TRPV1) channel, calcitonin gene-related peptide (CGRP), substance P (SP), and endothelin-1 (ET-1) following single and repeated blast exposure. Neutrophil infiltration and myeloperoxidase (MPO) expression were also assessed in blast tissues via immunohistochemistry and enzyme-linked immunosorbent assay (ELISA) analysis, respectively. Results: TRPV1 expression was increased in rat corneas exposed to both single and repeated blast. Increased secretion of CGRP, SP, and ET-1 was also detected in rat corneas as compared to control. Moreover, repeated blast exposure resulted in neutrophil infiltration in the cornea and stromal layer as compared to control animals. Conclusion: Single and repeated blast exposure resulted in increased expression of TRPV1, CGRP, SP, and ET-1 as well as neutrophil infiltration. Collectively, these findings provide novel insight into the activation of pain and inflammation signaling mediators following blast exposure. PMID:27049881

Structural Changes in Lipid Vesicles Generated by the Shock Blast Waves: Coarse-Grained Molecular Dynamics Simulation

DTIC Science & Technology

2013-11-01

duration, or shock-pulse shape. Used in this computational study is a coarse-grained model of the lipid vesicle as a simplified model of a cell...Figures iv List of Tables iv 1. Introduction 1 2. Model and Methods 3 3. Results and Discussion 6 3.1 Simulation of the Blast Waves with Low Peak...realistic detail but to focus on a simple model of the major constituent of a cell membrane, the phospholipid bilayer. In this work, we studied the

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

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

Chipman, V D

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

Xenon Protects against Blast-Induced Traumatic Brain Injury in an In Vitro Model.

PubMed

Campos-Pires, Rita; Koziakova, Mariia; Yonis, Amina; Pau, Ashni; Macdonald, Warren; Harris, Katie; Edge, Christopher J; Franks, Nicholas P; Mahoney, Peter F; Dickinson, Robert

2018-04-15

The aim of this study was to evaluate the neuroprotective efficacy of the inert gas xenon as a treatment for patients with blast-induced traumatic brain injury in an in vitro laboratory model. We developed a novel blast traumatic brain injury model using C57BL/6N mouse organotypic hippocampal brain-slice cultures exposed to a single shockwave, with the resulting injury quantified using propidium iodide fluorescence. A shock tube blast generator was used to simulate open field explosive blast shockwaves, modeled by the Friedlander waveform. Exposure to blast shockwave resulted in significant (p < 0.01) injury that increased with peak-overpressure and impulse of the shockwave, and which exhibited a secondary injury development up to 72 h after trauma. Blast-induced propidium iodide fluorescence overlapped with cleaved caspase-3 immunofluorescence, indicating that shock-wave-induced cell death involves apoptosis. Xenon (50% atm) applied 1 h after blast exposure reduced injury 24 h (p < 0.01), 48 h (p < 0.05), and 72 h (p < 0.001) later, compared with untreated control injury. Xenon-treated injured slices were not significantly different from uninjured sham slices at 24 h and 72 h. We demonstrate for the first time that xenon treatment after blast traumatic brain injury reduces initial injury and prevents subsequent injury development in vitro. Our findings support the idea that xenon may be a potential first-line treatment for those with blast-induced traumatic brain injury.

Distinguishing the Unique Neuropathological Profile of Blast Polytrauma

PubMed Central

Greenberg, Shaylen; Eck, Joseph; Lavik, Erin

2017-01-01

Traumatic brain injury sustained after blast exposure (blast-induced TBI) has recently been documented as a growing issue for military personnel. Incidence of injury to organs such as the lungs has decreased, though current epidemiology still causes a great public health burden. In addition, unprotected civilians sustain primary blast lung injury (PBLI) at alarming rates. Often, mild-to-moderate cases of PBLI are survivable with medical intervention, which creates a growing population of survivors of blast-induced polytrauma (BPT) with symptoms from blast-induced mild TBI (mTBI). Currently, there is a lack of preclinical models simulating BPT, which is crucial to identifying unique injury mechanisms of BPT and its management. To meet this need, our group characterized a rodent model of BPT and compared results to a blast-induced mTBI model. Open field (OF) performance trials were performed on rodents at 7 days after injury. Immunohistochemistry was performed to evaluate cellular outcome at day seven following BPT. Levels of reactive astrocytes (GFAP), apoptosis (cleaved caspase-3 expression), and vascular damage (SMI-71) were significantly elevated in BPT compared to blast-induced mTBI. Downstream markers of hypoxia (HIF-1α and VEGF) were higher only after BPT. This study highlights the need for unique therapeutics and prehospital management when handling BPT. PMID:28424745

Blast Fragmentation Modeling and Analysis

DTIC Science & Technology

2010-10-31

weapons device containing a multiphase blast explosive (MBX). 1. INTRODUCTION The ARL Survivability Lethality and Analysis Directorate (SLAD) is...velocity. In order to simulate the highly complex phenomenon, the exploding cylinder is modeled with the hydrodynamics code ALE3D , an arbitrary...Lagrangian-Eulerian multiphysics code, developed at Lawrence Livermore National Laboratory. ALE3D includes physical properties, constitutive models for

Bioceramic inlays do not improve mechanical incorporation of grit-blasted titanium stems in the proximal sheep femur.

PubMed

Keränen, Pauli; Koort, Jyri; Itälä, Ari; Ylänen, Heimo; Dalstra, Michel; Hupa, Mikko; Kommonen, Bertel; Aro, Hannu T

2010-03-15

The aim of the present study was to determine, if bioactive glass (BG) surface inlays improve osseointegration of titanium implants in the proximal femur of adult sheep. In simulation of uncemented primary stems (nine animals), only the proximal part of the implants was grit-blasted and three surface slots of the grit-blasted region were filled with sintered BG microspheres. Primary stems were implanted using press-fit technique. In revision stem simulation (eight animals), grit-blasting was extended over the whole implant and seven perforating holes of the stem were filled by sintered BG granules. Revision stems were implanted with a mixture of autogenous bone graft and BG granules. Comparison with solid partially or fully grit-blasted control stems implanted in the contralateral femurs was performed in the primary and revision stem experiments at 12 and 25 weeks, respectively. Implant incorporation was evaluated by torsional failure testing and histomorphometry. Only one-third of the primary stems anchored mechanically to bone. The revision stems incorporated better and the BG inlays of the revision stems showed ingrowth of new bone. However, there were no significant differences in the torsional failure loads between the stems with BG inlays and the control stems. In conclusion, surface BG inlays gave no measurable advantage in mechanical incorporation of grit-blasted titanium implants. Overall, the proximal sheep femur, characterized by minimal amount of cancellous bone and the presence of adipocytic bone marrow, seemed to present compromised bone healing conditions. (c) 2009 Wiley Periodicals, Inc.

Effect of Stemming to Burden Ratio and Powder Factor on Blast Induced Rock Fragmentation- A Case Study

NASA Astrophysics Data System (ADS)

Prasad, Sandeep; Choudhary, B. S.; Mishra, A. K.

2017-08-01

Rock fragmentation size is very important parameters for economical point of view in any surface mining. Rock fragment size direct effects on the costs of drilling, blasting, loading, secondary blasting and crushing. The main purpose of this study is to investigate effect of blast design parameters such as burden, blast hole length, stemming length, and powder factor on rock fragmentation. The fragment sizes (MFS, K50, m), and maximum fragment size (K95, m) of rock were determined by using the computer software. For every blast, after blasting operation, the images of whole muck pile are captured and there images were used for fragmentation analysis by using the Fragalyst software. It was observed that the optimal fragment size (MFS, K50, m and maximum fragment size, K95, m) of rock depends strongly on the blast design parameters and explosive parameters.

Large Blast and Thermal Simulator Reflected Wave Eliminator Study

DTIC Science & Technology

1990-03-01

it delays the passage of this wave through the test section until after the test is complete. The required length of extra duct depends on the strength...tube axis, which acts like an additional contraction effect since Se = Sj/[Cqsin(aj)]. Tii extra area is illustrated best by plotting (Se-Ae)/Ac versus...34Simulation de Choc et de Soaffie. Comimpensateur d’Ondes de Detente de Bouche pour tube a Choc de 2400 mm de diametre de Veine. Description, Compte- Renda

Computational Fluid Dynamics (CFD) Modeling for High Rate Pulverized Coal Injection (PCI) into the Blast Furnace

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

Dr. Chenn Zhou

2008-10-15

Pulverized coal injection (PCI) into the blast furnace (BF) has been recognized as an effective way to decrease the coke and total energy consumption along with minimization of environmental impacts. However, increasing the amount of coal injected into the BF is currently limited by the lack of knowledge of some issues related to the process. It is therefore important to understand the complex physical and chemical phenomena in the PCI process. Due to the difficulty in attaining trus BF measurements, Computational fluid dynamics (CFD) modeling has been identified as a useful technology to provide such knowledge. CFD simulation is powerfulmore » for providing detailed information on flow properties and performing parametric studies for process design and optimization. In this project, comprehensive 3-D CFD models have been developed to simulate the PCI process under actual furnace conditions. These models provide raceway size and flow property distributions. The results have provided guidance for optimizing the PCI process.« less

Computational Hydrocode Study of Target Damage due to Fragment-Blast Impact

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

Hatch-Aguilar, T; Najjar, F; Szymanski, E

2011-03-24

A target's terminal ballistic effects involving explosively generated fragments, along with the original blast, are of critical importance for many different security and safety related applications. Personnel safety and protective building design are but a few of the practical disciplines that can gain from improved understanding combined loading effects. Traditionally, any engineering level analysis or design effort involving explosions would divide the target damage analysis into two correspondingly critical areas: blast wave and fragment related impact effects. The hypothesis of this paper lies in the supposition that a linear combination of a blast-fragment loading, coupled with an accurate target responsemore » description, can lead to a non-linear target damage effect. This non-linear target response could then stand as the basis of defining what a synergistic or combined frag-blast loading might actually look like. The table below, taken from Walters, et. al. categorizes some of the critical parameters driving any combined target damage effect and drives the evaluation of results. Based on table 1 it becomes clear that any combined frag-blast analysis would need to account for the target response matching similar ranges for the mechanics described above. Of interest are the critical times upon which a blast event or fragment impact loading occurs relative to the target's modal response. A blast, for the purposes of this paper is defined as the sudden release of chemical energy from a given material (henceforth referred to as an energetic material) onto its surrounding medium. During the coupling mechanism a discrete or discontinuous shockwave is generated. This shockwave travels outward from the source transferring energy and momentum to any surrounding objects including personnel and engineering structures. From an engineering perspective blast effects are typically characterized by way of physical characteristics such as Peak Pressure (PP), Time of Arrival (TOA), Pressure-Impulse (PI) and Time of Duration (TD). Other peculiarities include the radial decrease in pressure from the source, any fireball size measurement, and subsequent increase in temperature from the passing of the shockwave through the surrounding medium. In light of all of these metrics, the loading any object receives from a blast event becomes intricately connected to the distance between itself and the source. Because of this, a clear distinction is made between close-in effects and those from a source far away from the object of interest. Explosively generated fragments on the other hand are characterized by means of their localized damage potential. Metrics such as whether the fragment penetrates or perforates a given object is quantified as well as other variables including fragment's residual velocity, % kinetic energy decrease, residual fragment mass and other exit criteria. A fragment launched under such violent conditions could easily be traveling at speeds in excess of 2500 ft/s. Given these speeds it is conceivable to imagine how any given fragment could deliver a concentrated load to a target and penetrates through walls, vehicles or even the protection systems of nearby personnel. This study will focus on the individual fragment-target impact event with the hopes of expanding it to eventually include statistical procedures. Since this is a modeling excursion into the combined frag-blast target damage effects the numerical methods used to frame this problem become important in-so-far as the simulations are done in a consistent manner. For this study a Finite-Element based Hydrocode solution called ALE3D (ALE=Arbitrary Lagrangian-Eulerian) was utilized. ALE3D is developed by Lawrence Livermore National Laboratory (Livermore, CA), and as this paper will show, successfully implemented a converged ALE formulation including as many of the different aspects needed to query the synergistic damage on a given target. Further information on the modeling setup is included.« less

Canine human scent identifications with post-blast debris collected from improvised explosive devices.

PubMed

Curran, Allison M; Prada, Paola A; Furton, Kenneth G

2010-06-15

In this study it is demonstrated that human odor collected from items recovered at a post-blast scene can be evaluated using human scent specific canine teams to locate and identify individuals who have been in contact with the improvised explosive device (IED) components and/or the delivery vehicle. The purpose of the experiments presented here was to document human scent survivability in both peroxide-based explosions as well as simulated roadside IEDs utilizing double-blind field trials. Human odor was collected from post-blast device and vehicle components. Human scent specific canine teams were then deployed at the blast scene and in locations removed from the blast scene to validate that human odor remains in sufficient quantities for reliable canine detection and identification. Human scent specific canines have shown the ability to identify individuals who have been in contact with IEDs using post-blast debris with an average success from site response of 82.2% verifying that this technology has great potential in criminal, investigative, and military applications. (c) 2010 Elsevier Ireland Ltd. All rights reserved.

Development of a rat model for studying blast-induced traumatic brain injury.

PubMed

Cheng, Jingmin; Gu, Jianwen; Ma, Yuan; Yang, Tao; Kuang, Yongqin; Li, Bingcang; Kang, Jianyi

2010-07-15

Blast-induced traumatic brain injury (TBI) has been the predominant cause of neurotrauma in current military conflicts, and it is also emerging as a potential threat in civilian terrorism. The etiology of TBI, however, is poorly understood. Further study on the mechanisms and treatment of blast injury is urgently needed. We developed a unique rat model to simulate blast effects that commonly occur on the battlefield. An electric detonator with the equivalent of 400 mg TNT was developed as the explosive source. The detonator's peak overpressure and impulse of explosion shock determined the explosion intensity in a distance-dependent manner. Ninety-six male adult Sprague-Dawley rats were randomly divided into four groups: 5-cm, 7.5-cm, 10-cm, and control groups. The rat was fixed in a specially designed cabin with an adjustable aperture showing the frontal, parietal, and occipital parts of the head exposed to explosion; the eyes, ears, mouth, and nose were protected by the cabin. After each explosion, we assessed the physiologic, neuropathologic, and neurobehavioral consequences of blast injury. Changes of brain tissue water content and neuron-specific enolase (NSE) expression were detected. The results in the 7.5-cm group show that 87% rats developed apnea, limb seizure, poor appetite, and limpness. Diffuse subarachnoid hemorrhage and edema could be seen within the brain parenchyma, which showed a loss of integrity. Capillary damage and enlarged intercellular and vascular space in the cortex, along with a tattered nerve fiber were observed. These findings demonstrate that we have provided a reliable and reproducible blast-induced TBI model in rats. Copyright 2010 Elsevier B.V. All rights reserved.

Vascular and Inflammatory Factors in the Pathophysiology of Blast-Induced Brain Injury

PubMed Central

Elder, Gregory A.; Gama Sosa, Miguel A.; De Gasperi, Rita; Stone, James Radford; Dickstein, Dara L.; Haghighi, Fatemeh; Hof, Patrick R.; Ahlers, Stephen T.

2015-01-01

Blast-related traumatic brain injury (TBI) has received much recent attention because of its frequency in the conflicts in Iraq and Afghanistan. This renewed interest has led to a rapid expansion of clinical and animal studies related to blast. In humans, high-level blast exposure is associated with a prominent hemorrhagic component. In animal models, blast exerts a variety of effects on the nervous system including vascular and inflammatory effects that can be seen with even low-level blast exposures which produce minimal or no neuronal pathology. Acutely, blast exposure in animals causes prominent vasospasm and decreased cerebral blood flow along with blood-brain barrier breakdown and increased vascular permeability. Besides direct effects on the central nervous system, evidence supports a role for a thoracically mediated effect of blast; whereby, pressure waves transmitted through the systemic circulation damage the brain. Chronically, a vascular pathology has been observed that is associated with alterations of the vascular extracellular matrix. Sustained microglial and astroglial reactions occur after blast exposure. Markers of a central and peripheral inflammatory response are found for sustained periods after blast injury and include elevation of inflammatory cytokines and other inflammatory mediators. At low levels of blast exposure, a microvascular pathology has been observed in the presence of an otherwise normal brain parenchyma, suggesting that the vasculature may be selectively vulnerable to blast injury. Chronic immune activation in brain following vascular injury may lead to neurobehavioral changes in the absence of direct neuronal pathology. Strategies aimed at preventing or reversing vascular damage or modulating the immune response may improve the chronic neuropsychiatric symptoms associated with blast-related TBI. PMID:25852632

NO FLARES FROM GAMMA-RAY BURST AFTERGLOW BLAST WAVES ENCOUNTERING SUDDEN CIRCUMBURST DENSITY CHANGE

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

Gat, Ilana; Van Eerten, Hendrik; MacFadyen, Andrew

2013-08-10

Afterglows of gamma-ray bursts are observed to produce light curves with the flux following power-law evolution in time. However, recent observations reveal bright flares at times on the order of minutes to days. One proposed explanation for these flares is the interaction of a relativistic blast wave with a circumburst density transition. In this paper, we model this type of interaction computationally in one and two dimensions, using a relativistic hydrodynamics code with adaptive mesh refinement called RAM, and analytically in one dimension. We simulate a blast wave traveling in a stellar wind environment that encounters a sudden change inmore » density, followed by a homogeneous medium, and compute the observed radiation using a synchrotron model. We show that flares are not observable for an encounter with a sudden density increase, such as a wind termination shock, nor for an encounter with a sudden density decrease. Furthermore, by extending our analysis to two dimensions, we are able to resolve the spreading, collimation, and edge effects of the blast wave as it encounters the change in circumburst medium. In all cases considered in this paper, we find that a flare will not be observed for any of the density changes studied.« less

Distinguishing Realistic Military Blasts from Firecrackers in Mitigation Studies of Blast Induced Traumatic Brain Injury

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

Moss, W C; King, M J; Blackman, E G

In their Contributed Article, Nyein et al. (1,2) present numerical simulations of blast waves interacting with a helmeted head and conclude that a face shield may significantly mitigate blast induced traumatic brain injury (TBI). A face shield may indeed be important for future military helmets, but the authors derive their conclusions from a much smaller explosion than typically experienced on the battlefield. The blast from the 3.16 gm TNT charge of (1) has the following approximate peak overpressures, positive phase durations, and incident impulses (3): 10 atm, 0.25 ms, and 3.9 psi-ms at the front of the head (14 cmmore » from charge), and 1.4 atm, 0.32 ms, and 1.7 psi-ms at the back of a typical 20 cm head (34 cm from charge). The peak pressure of the wave decreases by a factor of 7 as it traverses the head. The blast conditions are at the threshold for injury at the front of the head, but well below threshold at the back of the head (4). The blast traverses the head in 0.3 ms, roughly equal to the positive phase duration of the blast. Therefore, when the blast reaches the back of the head, near ambient conditions exist at the front. Because the headform is so close to the charge, it experiences a wave with significant curvature. By contrast, a realistic blast from a 2.2 kg TNT charge ({approx} an uncased 105 mm artillery round) is fatal at an overpressure of 10 atm (4). For an injury level (4) similar to (1), a 2.2 kg charge has the following approximate peak overpressures, positive phase durations, and incident impulses (3): 2.1 atm, 2.3 ms, and 18 psi-ms at the front of the head (250 cm from charge), and 1.8 atm, 2.5 ms, and 16.8 psi-ms at the back of the head (270 cm from charge). The peak pressure decreases by only a factor of 1.2 as it traverses the head. Because the 0.36 ms traversal time is much smaller than the positive phase duration, pressures on the head become relatively uniform when the blast reaches the back of the head. The larger standoff implies that the headform locally experiences a nearly planar blast wave. Also, the positive phase durations and blast impulses are much larger than those of (1). Consequently, the blast model used in (1) is spatially and temporally very different from a military blast. It would be useful to repeat the calculations using military blast parameters. Finally, (1) overlooks a significant part of (5). On page 1 and on page 3, (1) states that (5) did not consider helmet pads. But pages pages 3 and 4 of (5) present simulations of blast wave propagation across an ACH helmeted head form with and without pads. (5) states that when the pads are present, the 'underwash' of air under the helmet is blocked when compared to the case without. (1) reaches this same conclusion, but reports it as a new result rather than a confirmation of that already found in (5).« less

Assessment of the Effect of Blast Hole Diameter on the Number of Oversize Boulders Using ANN Model

NASA Astrophysics Data System (ADS)

Dhekne, Prakash; Pradhan, Manoj; Jade, Ravi Krishnarao

2016-04-01

Now-a-days, blasts are planned using large diameter blast holes. The loading density (kg/m) and subsequently the energy available for the breakage of the rockmass increase with the diameter. The in-hole velocity of detonation (VoD) of non-ideal explosive also boosts up with the increase in diameter till the optimum diameter is reached. The increase in the energy content and in-hole VoD cause a sizable effect on the rock fragmentation. The effect can be assessed by counting the number of oversize boulders. This paper explains as to how the technique of artificial neural network modeling was used to predict the number of oversize boulders resulting from ANFO and SME blasts with blast holes of different diameters. The results from ANFO blasts indicated that there was no significant variation in the number of oversize boulders with the diameter whereas a perceptible variation was noticed in case of SME blasts with the change in the diameter. The change in the number of oversize boulders in ANFO blasts was negligible because mean energy factor remained almost same even when the diameter of the blast holes was altered. The decrease in the number of oversize boulders in SME blasts was on account of increase in mean energy factor when the blast hole diameter was increased. The increase in the in-hole VoD due to increase in the diameter of the hole was not found to have an effect on the generation of oversize boulders as this increase was not substantial both in SME and ANFO blasts.

The Centrifugal Simulation of Blast Parameters.

DTIC Science & Technology

1983-12-01

a is to be experimentally evaluated. The terms that remain in Equation (1) are not nondimensional; that is, they are not true i-terms. This does not...If necessary and identify by block number This study is concerned with the use oT a centrifuge as an experimental device on which free-field blast...5 SIMILITUDE. .. .. ..... ...... ...... ... 9 Ill. EXPERIMENTAL PROCEDURES .. .. ... ...... ........13 INTRODUCTION

Xenon Protects against Blast-Induced Traumatic Brain Injury in an In Vitro Model

PubMed Central

Campos-Pires, Rita; Koziakova, Mariia; Yonis, Amina; Pau, Ashni; Macdonald, Warren; Harris, Katie; Edge, Christopher J.; Franks, Nicholas P.; Mahoney, Peter F.

2018-01-01

Abstract The aim of this study was to evaluate the neuroprotective efficacy of the inert gas xenon as a treatment for patients with blast-induced traumatic brain injury in an in vitro laboratory model. We developed a novel blast traumatic brain injury model using C57BL/6N mouse organotypic hippocampal brain-slice cultures exposed to a single shockwave, with the resulting injury quantified using propidium iodide fluorescence. A shock tube blast generator was used to simulate open field explosive blast shockwaves, modeled by the Friedlander waveform. Exposure to blast shockwave resulted in significant (p < 0.01) injury that increased with peak-overpressure and impulse of the shockwave, and which exhibited a secondary injury development up to 72 h after trauma. Blast-induced propidium iodide fluorescence overlapped with cleaved caspase-3 immunofluorescence, indicating that shock-wave–induced cell death involves apoptosis. Xenon (50% atm) applied 1 h after blast exposure reduced injury 24 h (p < 0.01), 48 h (p < 0.05), and 72 h (p < 0.001) later, compared with untreated control injury. Xenon-treated injured slices were not significantly different from uninjured sham slices at 24 h and 72 h. We demonstrate for the first time that xenon treatment after blast traumatic brain injury reduces initial injury and prevents subsequent injury development in vitro. Our findings support the idea that xenon may be a potential first-line treatment for those with blast-induced traumatic brain injury. PMID:29285980

Effect of Plate Curvature on Blast Response of Structural Steel Plates

NASA Astrophysics Data System (ADS)

Veeredhi, Lakshmi Shireen Banu; Ramana Rao, N. V.; Veeredhi, Vasudeva Rao

2018-04-01

In the present work an attempt is made, through simulation studies, to determine the effect of plate curvature on the blast response of a door structure made of ASTM A515 grade 50 steel plates. A door structure with dimensions of 5.142 m × 2.56 m × 10 mm having six different radii of curvatures is analyzed which is subjected to blast load. The radii of curvature investigated are infinity (flat plate), 16.63, 10.81, 8.26, 6.61 and 5.56 m. In the present study, a stand-off distance of 11 m is considered for all the cases. Results showed that the door structure with smallest radius of curvature experienced least plastic deformation and yielding when compared to a door with larger radius of curvature with same projected area. From the present Investigation, it is observed that, as the radius of curvature of the plate increases, the deformation mode gradually shifts from indentation mode to flexural mode. The plates with infinity and 16.63 m radius of curvature have undergone flexural mode of deformation and plates with 6.61 and 5.56 m radius of curvature undergo indentation mode of deformation. Whereas, mixed mode of deformation that consists of both flexural and indentation mode of deformations are seen in the plates with radius of curvature 10.81 and 8.26 m. As the radius of curvature of the plate decreases the ability of the plate to mitigate the effect the blast loads increased. It is observed that the plate with smaller radius of curvature deflects most of the blast energy and results in least indentation mode of deformation. The most significant observation made in the present investigation is that the strain energy absorbed by the steel plate gets reduced to 1/3 rd when the radius of curvature is approximately equal to the stand-off distance which could be the critical radius of curvature.

Simulation Assisted Risk Assessment: Blast Overpressure Modeling

NASA Technical Reports Server (NTRS)

Lawrence, Scott L.; Gee, Ken; Mathias, Donovan; Olsen, Michael

2006-01-01

A probabilistic risk assessment (PRA) approach has been developed and applied to the risk analysis of capsule abort during ascent. The PRA is used to assist in the identification of modeling and simulation applications that can significantly impact the understanding of crew risk during this potentially dangerous maneuver. The PRA approach is also being used to identify the appropriate level of fidelity for the modeling of those critical failure modes. The Apollo launch escape system (LES) was chosen as a test problem for application of this approach. Failure modes that have been modeled and/or simulated to date include explosive overpressure-based failure, explosive fragment-based failure, land landing failures (range limits exceeded either near launch or Mode III trajectories ending on the African continent), capsule-booster re-contact during separation, and failure due to plume-induced instability. These failure modes have been investigated using analysis tools in a variety of technical disciplines at various levels of fidelity. The current paper focuses on the development and application of a blast overpressure model for the prediction of structural failure due to overpressure, including the application of high-fidelity analysis to predict near-field and headwinds effects.

76 FR 52569 - Regulated Navigation Area; Arthur Kill, NY and NJ

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-23

... simulator assessments of the drilling and blasting areas. These simulations studied the possibility of... all times for vessel transits. The results of the simulation allowed the USACE to determine that... 2011 to discuss the results of the navigation simulations. In June the USACE and the contractor...

Modeling and simulations of radiative blast wave driven Rayleigh-Taylor instability experiments

NASA Astrophysics Data System (ADS)

Shimony, Assaf; Huntington, Channing M.; Trantham, Matthew; Malamud, Guy; Elbaz, Yonatan; Kuranz, Carolyn C.; Drake, R. Paul; Shvarts, Dov

2017-10-01

Recent experiments at the National Ignition Facility measured the growth of Rayleigh-Taylor RT instabilities driven by radiative blast waves, relevant to astrophysics and other HEDP systems. We constructed a new Buoyancy-Drag (BD) model, which accounts for the ablation effect on both bubble and spike. This ablation effect is accounted for by using the potential flow model ]Oron et al PoP 1998], adding another term to the classical BD formalism: βDuA / u , where β the Takabe constant, D the drag term, uA the ablation velocity and uthe instability growth velocity. The model results are compared with the results of experiments and 2D simulations using the CRASH code, with nominal radiation or reduced foam opacity (by a factor of 1000). The ablation constant of the model, βb / s, for the bubble and for the spike fronts, are calibrated using the results of the radiative shock experiments. This work is funded by the Lawrence Livermore National Laboratory under subcontract B614207, and was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Mechanical Properties of Polymers Used for Anatomical Components in the Warrior Injury Assessment Manikin (WIAMan) Technology Demonstrator

DTIC Science & Technology

2016-07-01

14. ABSTRACT The Warrior Injury Assessment Manikin was developed to provide an instrumented anthropomorphic test device (ATD) specifically...underbody blasts . To achieve that goal, the ATD used numerous polymeric materials for component parts that simulate human tissue and enable compliance in...strain rate, underbody blast , mechanical testing, tension, compression 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT

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

NASA Astrophysics Data System (ADS)

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.

Determination of Destress Blasting Effectiveness Using Seismic Source Parameters

NASA Astrophysics Data System (ADS)

Wojtecki, Łukasz; Mendecki, Maciej J.; Zuberek, Wacaław M.

2017-12-01

Underground mining of coal seams in the Upper Silesian Coal Basin is currently performed under difficult geological and mining conditions. The mining depth, dislocations (faults and folds) and mining remnants are responsible for rockburst hazard in the highest degree. This hazard can be minimized by using active rockburst prevention, where destress blastings play an important role. Destress blastings in coal seams aim to destress the local stress concentrations. These blastings are usually performed from the longwall face to decrease the stress level ahead of the longwall. An accurate estimation of active rockburst prevention effectiveness is important during mining under disadvantageous geological and mining conditions, which affect the risk of rockburst. Seismic source parameters characterize the focus of tremor, which may be useful in estimating the destress blasting effects. Investigated destress blastings were performed in coal seam no. 507 during its longwall mining in one of the coal mines in the Upper Silesian Coal Basin under difficult geological and mining conditions. The seismic source parameters of the provoked tremors were calculated. The presented preliminary investigations enable a rapid estimation of the destress blasting effectiveness using seismic source parameters, but further analysis in other geological and mining conditions with other blasting parameters is required.

Effects of Filtering on Experimental Blast Overpressure Measurements.

PubMed

Alphonse, Vanessa D; Kemper, Andrew R; Duma, Stefan M

2015-01-01

When access to live-fire test facilities is limited, experimental studies of blast-related injuries necessitate the use of a shock tube or Advanced Blast Simulator (ABS) to mimic free-field blast overpressure. However, modeling blast overpressure in a laboratory setting potentially introduces experimental artifacts in measured responses. Due to the high sampling rates required to capture a blast overpressure event, proximity to alternating current (AC-powered electronics) and poorly strain-relieved or unshielded wires can result in artifacts in the recorded overpressure trace. Data in this study were collected for tests conducted on an empty ABS (“Empty Tube”) using high frequency pressure sensors specifically designed for blast loading rates (n=5). Additionally, intraocular overpressure data (“IOP”) were collected for porcine eyes potted inside synthetic orbits located inside the ABS using an unshielded miniature pressure sensor (n=3). All tests were conducted at a 30 psi static overpressure level. A 4th order phaseless low pass Butterworth software filter was applied to the data. Various cutoff frequencies were examined to determine if the raw shock wave parameters values could be preserved while eliminating noise and artifacts. A Fast Fourier Transform (FFT) was applied to each test to examine the frequency spectra of the raw and filtered signals. Shock wave parameters (time of arrival, peak overpressure, positive duration, and positive impulse) were quantified using a custom MATLAB® script. Lower cutoff frequencies attenuated the raw signal, effectively decreasing the peak overpressure and increasing the positive duration. Rise time was not preserved the filtered data. A CFC 6000 filter preserved the remaining shock wave parameters within ±2.5% of the average raw values for the Empty Tube test data. A CFC 7000 filter removed experimental high-frequency artifacts and preserved the remaining shock wave parameters within ±2.5% of the average raw values for test IOP test data. Though the region of interest of the signals examined in the current study did not contain extremely high frequency content, it is possible that live-fire testing may produce shock waves with higher frequency content. While post-processing filtering can remove experimental artifacts, special care should be taken to minimize or eliminate the possibility of recording these artifacts in the first place.

Correlative analysis of head kinematics and brain's tissue response: a computational approach toward understanding the mechanisms of blast TBI

NASA Astrophysics Data System (ADS)

Sarvghad-Moghaddam, H.; Rezaei, A.; Ziejewski, M.; Karami, G.

2017-11-01

Upon impingement of blast waves on the head, stress waves generated at the interface of the skull are transferred into the cranium and the brain tissue and may cause mild to severe blast traumatic brain injury. The intensity of the shock front, defined by the blast overpressure (BoP), that is, the blast-induced peak static overpressure, significantly affects head kinematics as well as the tissue responses of the brain. While evaluation of global linear and rotational accelerations may be feasible, an experimental determination of dynamic responses of the brain in terms of intracranial pressure (ICP), maximum shear stress (MSS), and maximum principal strain (MPS) is almost impossible. The main objective of this study is to investigate possible correlations between head accelerations and the brain's ICP, MSS, and MPS. To this end, three different blasts were simulated by modeling the detonation of 70, 200, and 500 g of TNT at a fixed distance from the head, corresponding to peak BoPs of 0.52, 1.2, and 2 MPa, respectively. A nonlinear multi-material finite element algorithm was implemented in the LS-DYNA explicit solver. Fluid-solid interaction between the blast waves and head was modeled using a penalty-based method. Strong correlations were found between the brain's dynamic responses and both global linear and rotational accelerations at different blast intensities (R^{2 }≥98%), implying that global kinematic parameters of the head might be strong predictors of brain tissue biomechanical parameters.

High-speed imaging and small-scale explosive characterization techniques to understand effects of primary blast-induced injury on nerve cell structure and function

NASA Astrophysics Data System (ADS)

Piehler, T.; Banton, R.; Zander, N.; Duckworth, J.; Benjamin, R.; Sparks, R.

2018-01-01

Traumatic brain injury (TBI) is often associated with blast exposure. Even in the absence of penetrating injury or evidence of tissue injury on imaging, blast TBI may trigger a series of neural/glial cellular and functional changes. Unfortunately, the diagnosis and proper treatment of mild traumatic brain injury (mTBI) caused by explosive blast is challenging, as it is not easy to clinically distinguish blast from non-blast TBI on the basis of patient symptoms. Damage to brain tissue, cell, and subcellular structures continues to occur slowly and in a manner undetectable by conventional imaging techniques. The threshold shock impulse levels required to induce damage and the cumulative effects upon multiple exposures are not well characterized. Understanding how functional and structural damage from realistic blast impact at cellular and tissue levels at variable timescales after mTBI events may be vital for understanding this injury phenomenon and for linking mechanically induced structural changes with measurable effects on the nervous system. Our working hypothesis is that there is some transient physiological dysfunction occurring at cellular and subcellular levels within the central nervous system due to primary blast exposure. We have developed a novel in vitro indoor experimental system that uses real military explosive charges to more accurately represent military blast exposure and to probe the effects of primary explosive blast on dissociated neurons. We believe this system offers a controlled experimental method to analyze and characterize primary explosive blast-induced cellular injury and to understand threshold injury phenomenon. This paper will also focus on the modeling aspect of our work and how it relates to the experimental work.

The building loads analysis system thermodynamics (BLAST) program, Version 2. 0: input booklet. Final report

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

Sowell, E.

1979-06-01

The Building Loads Analysis and System Thermodynamics (BLAST) program is a comprehensive set of subprograms for predicting energy consumption in buildings. There are three major subprograms: (1) the space load predicting subprogram, which computes hourly space loads in a building or zone based on user input and hourly weather data; (2) the air distribution system simulation subprogram, which uses the computed space load and user inputs describing the building air-handling system to calculate hot water or steam, chilled water, and electric energy demands; and (3) the central plant simulation program, which simulates boilers, chillers, onsite power generating equipment and solarmore » energy systems and computes monthly and annual fuel and electrical power consumption and plant life cycle cost.« less

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

Suzuki, Akihiro; Maeda, Keiichi; Shigeyama, Toshikazu

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 partmore » 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.« less

Numerical Simulation of Quarry Blast Sources

DTIC Science & Technology

1994-01-01

REPORT NUMBER 3701 N. Fairfax Dr. #717 3651 Lowry Avenue, SE Arlington, VA 22203-1714 Kirtland, AFB, NM 87117-5777 11. SUPPLEMENTARY NOTES 12a...Blasts, LLNL Report UCRL -JC- 109245. Wuster, J. (1993). Discrimination of Chemical Explosions and Earthquakes in Central Europe - A Case Study, Bull. Seism...NMRO Building 77 3701 N. Fairfax Drive, Suite 717 University of Arizona Arlington, VA 22203-1714 Tucson, AZ 85721 ARPAIOASB/Librarian Dr. William

Hydrocortisone in culture protects the blast cells in acute myeloblastic leukemia from the lethal effects of cytosine arabinoside

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

Yang, G.S.; Wang, C.; Minkin, S.

The blast cells in acute myeloblastic leukemia (AML) respond to many of the same regulatory mechanisms that control normal hemopoiesis. These include the growth factors that bind to membrane receptors and steroid hormones or vitamins that have intracellular receptors. The authors report the effects in culture of the steroid glucocorticoid hydrocortisone on freshly explanted AML blasts from patients and on two continuous AML cell lines. Only small changes in clonogenic cell numbers in suspension cultures were seen in the presence of hydrocortisone. The most striking effect of the hormone was on the sensitivity of blasts cells to cytosine arabinoside (ara-C).more » In contrast to the response of AML blast cells to retinoic acid, a ligand for intracellular steroid receptors that sensitizes some blast populations to ara-C, hydrocortisone reduced the toxic effects of the drug. The protective action of hydrocortisone was not mediated through the cell cycle since exposure of blasts to hydrocortisone did not affect the percentage of cells in DNA synthesis as measured with the tritiated thymidine (3HTdR) suicide technique. The hydrocortisone effect could be demonstrated using a pulse (20 min) exposure protocol. Blasts pulsed with increasing specific activities of 3HTdR showed the usual response pattern with an initial loss in plating efficiency to about 50% of control, followed by a plateau, regardless of whether the cells had been exposed to hydrocortisone. Control blasts exposed to increasing ara-C concentrations gave very similar dose-response curves; in striking contrast, blast cells cultured in hydrocortisone, then pulsed with ara-C did not lose colony-forming ability even though the same population was sensitive to 3HTdR.« less

Nuclear Air Blast Effects.

DTIC Science & Technology

1982-06-01

AD-All? 43 SCIENCE APPLICATZOhu INC NCLAA VA F/6 19/4I NUICLEAR AIR BLAST IFPCTS(U) JUR " PRY UNCLASSIFID SAI-63-636-VA NLOOI I-C lit? I. 1174~ 132...SiCuftIt, CLASSFICA?1lOw OF fl.IS PAQ-C( fhbl Dal. Lnt.,.d, REPORT DOCUMENTATION4 PAGE apoI ct~ NUCLEAR AIR BLAST EFFECTS FINAL REPORT SAI-83-836-WA...TUCSON a WASHINGTON NUCLEAR AIR BLAST EFFECTS FINAL REPORT SAI-83-836-WA Submitted to: Laboratory for Computational Physics Naval Research Laboratory

Nuclear Power System Architecture and Safety Study- Feasibility of Launch Pad Explosion Simulation using Radios

NASA Astrophysics Data System (ADS)

Destefanis, Stefano; Tracino, Emanuele; Giraudo, Martina

2014-06-01

During a mission involving a spacecraft using nuclear power sources (NPS), the consequences to the population induced by an accident has to be taken into account carefully.Part of the study (led by AREVA, with TAS-I as one of the involved parties) was devoted to "Worst Case Scenario Consolidation". In particular, one of the activities carried out by TAS-I had the aim of characterizing the accidental environment (explosion on launch pad or during launch) and consolidate the requirements given as input in the study. The resulting requirements became inputs for Nuclear Power Source container design.To do so, TAS-I did first an overview of the available technical literature (mostly developed in the frame of NASA Mercury / Apollo program), to identify the key parameters to be used for analytical assessment (blast pressure wave, fragments size, speed and distribution, TNT equivalent of liquid propellant).Then, a simplified Radioss model was setup, to verify both the cards needed for blast / fragment impact analysis and the consistency between preliminary results and available technical literature (Radioss is commonly used to design mine - resistant vehicles, by simulating the effect of blasts onto structural elements, and it is used in TAS-I for several types of analysis, including land impact, water impact and fluid - structure interaction).The obtained results (albeit produced by a very simplified model) are encouraging, showing that the analytical tool and the selected key parameters represent a step in the right direction.

Dynamic response analysis of surrounding rock under the continuous blasting seismic wave

NASA Astrophysics Data System (ADS)

Gao, P. F.; Zong, Q.; Xu, Y.; Fu, J.

2017-10-01

The blasting vibration that is caused by blasting excavation will generate a certain degree of negative effect on the stability of surrounding rock in underground engineering. A dynamic response analysis of surrounding rock under the continuous blasting seismic wave is carried out to optimize blasting parameters and guide underground engineering construction. Based on the theory of wavelet analysis, the reconstructed signals of each layer of different frequency bands are obtained by db8 wavelet decomposition. The difference of dynamic response of the continuous blasting seismic wave at a certain point caused by different blasting sources is discussed. The signal in the frequency band of natural frequency of the surrounding rock shows a certain degree of amplification effect deduced from the dynamic response characteristics of the surrounding rock under the influence of continuous blasting seismic wave. Continuous blasting operations in a fixed space will lead to the change of internal structure of the surrounding rock. It may result in the decline of natural frequency of the whole surrounding rock and it is also harmful for the stability of the surrounding rock.

Close-in Blast Waves from Spherical Charges*

NASA Astrophysics Data System (ADS)

Howard, William; Kuhl, Allen

2011-06-01

We study the close-in blast waves created by the detonation of spherical high explosives (HE) charges, via numerical simulations with our Arbitrary-Lagrange-Eulerian (ALE3D) code. We used a finely-resolved, fixed Eulerian 2-D mesh (200 μm per cell) to capture the detonation of the charge, the blast wave propagation in air, and the reflection of the blast wave from an ideal surface. The thermodynamic properties of the detonation products and air were specified by the Cheetah code. A programmed-burn model was used to detonate the charge at a rate based on measured detonation velocities. The results were analyzed to evaluate the: (i) free air pressure-range curves: Δps (R) , (ii) free air impulse curves, (iii) reflected pressure-range curves, and (iv) reflected impulse-range curves. A variety of explosives were studied. Conclusions are: (i) close-in (R < 10 cm /g 1 / 3) , each explosive had its own (unique) blast wave (e.g., Δps (R , HE) ~ a /Rn , where n is different for each explosive); (ii) these close-in blast waves do not scale with the ``Heat of Detonation'' of the explosive (because close-in, there is not enough time to fully couple the chemical energy to the air via piston work); (iii) instead they are related to the detonation conditions inside the charge. Scaling laws will be proposed for such close-in blast waves.

Blasting, graphical interfaces and Unix

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

Knudsen, S.; Preece, D.S.

1993-11-01

A discrete element computer program, DMC (Distinct Motion Code) was developed to simulate blast-induced rock motion. To simplify the complex task of entering material and explosive design parameters as well as bench configuration, a full-featured graphical interface has been developed. DMC is currently executed on both Sun SPARCstation 2 and Sun SPARCstation 10 platforms and routinely used to model bench and crater blasting problems. This paper will document the design and development of the full-featured interface to DMC. The development of the interface will be tracked through the various stages, highlighting the adjustments made to allow the necessary parameters tomore » be entered in terms and units that field blasters understand. The paper also discusses a novel way of entering non-integer numbers and the techniques necessary to display blasting parameters in an understandable visual manner. A video presentation will demonstrate the graphics interface and explains its use.« less

Blasting, graphical interfaces and Unix

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

Knudsen, S.; Preece, D.S.

1994-12-31

A discrete element computer program, DMC (Distinct Motion Code) was developed to simulate blast-induced rock motion. To simplify the complex task of entering material and explosive design parameters as well as bench configuration, a full-featured graphical interface has been developed. DMC is currently executed on both Sun SPARCstation 2 and Sun SPARCstation 10 platforms and routinely used to model bench and crater blasting problems. This paper will document the design and development of the full-featured interface to DMC. The development of the interface will be tracked through the various stages, highlighting the adjustments made to allow the necessary parameters tomore » be entered in terms and units that field blasters understand. The paper also discusses a novel way of entering non-integer numbers and the techniques necessary to display blasting parameters in an understandable visual manner. A video presentation will demonstrate the graphics interface and explains its use.« less

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

Taylor, Paul A.; Cooper, Candice Frances; Burnett, Damon J.

Light body armor development for the warfighter is based on trial-and-error testing of prototype designs against ballistic projectiles. Torso armor testing against blast is virtually nonexistent but necessary to ensure adequate protection against injury to the heart and lungs. In this report, we discuss the development of a high-fidelity human torso model, it's merging with the existing Sandia Human Head-Neck Model, and development of the modeling & simulation (M&S) capabilities necessary to simulate wound injury scenarios. Using the new Sandia Human Torso Model, we demonstrate the advantage of virtual simulation in the investigation of wound injury as it relates tomore » the warfighter experience. We present the results of virtual simulations of blast loading and ballistic projectile impact to the tors o with and without notional protective armor. In this manner, we demonstrate the ad vantages of applying a modeling and simulation approach to the investigation of wound injury and relative merit assessments of protective body armor without the need for trial-and-error testing.« less

Simulating the Initial Dynamics of the 18 May 1980 Mount St.Helens Blast

NASA Astrophysics Data System (ADS)

Esposti Ongaro, T.; Widiwijayanti, C.; Voight, B.; Clarke, A. B.; Neri, A.

2008-12-01

The initial stage of the 18 May 1980 blast at Mount St. Helens (MSH) has been simulated numerically by the 2D/3D multiphase multiparticle flow model PDAC (Neri et al., J. Geophys. Res. 108 (B4), 2003; Esposti Ongaro et al., Parallel Computing 33, 2007), to provide further insight into the fluid dynamics of this phenomenon. Initial source conditions, including the gas content, the total mass of juvenile and entrained rocks, the temperature, grain size distribution and pre-eruption pressure distribution in the lava dome have been parameterized accordingly to field evidence, available geological constraints and simple theoretical models. Simulation results suggest that the MSH blast can be characterized as an expansion phase (burst), lasting about ten seconds, followed by collapse and pyroclastic density current (PDC) phases. In the burst phase the pressure forces dominate and the flow can locally reach supersonic velocities and generate pressure waves that can be tracked by the numerical model. In the collapse and PDC phases the flow is dominantly gravity-driven and the dynamics are strongly controlled by the source geometry, vertical stratification within the flow and by the 3D topography. The simulations suggest that the severe damage observed at MSH can be explained by high dynamic pressures in gravity currents, and the rapid decrease of dynamic pressure from proximal to distal areas (and related parameters of PDC velocity and density) was largely related to rugged topography beyond the North Fork Toutle River valley. Although the source models investigated thus far represent a simplification of the actual geometry and complex sequence of initial events, we show that the explosion mechanisms are significantly robust over a wide range of initial conditions. Simulation results for MSH are also consistent with those obtained in a previous application of a similar model to the 1997 Boxing Day blast pulses at Soufriere Hills volcano (Montserrat, West Indies) (Esposti Ongaro et al., J. Geophys. Res. 113 (B03211), 2008), which were at least ten times smaller, thus suggesting that the simulated mechanisms are largely independent of eruption scale.

Blast from pressurized carbon dioxide released into a vented atmospheric chamber

NASA Astrophysics Data System (ADS)

Hansen, P. M.; Gaathaug, A. V.; Bjerketvedt, D.; Vaagsaether, K.

2018-03-01

This study describes the blast from pressurized carbon dioxide (CO2) released from a high-pressure reservoir into an openly vented atmospheric chamber. Small-scale experiments with pure vapor and liquid/vapor mixtures were conducted and compared with simulations. A motivation was to investigate the effects of vent size and liquid content on the peak overpressure and impulse response in the atmospheric chamber. The comparison of vapor-phase CO2 test results with simulations showed good agreement. This numerical code described single-phase gas dynamics inside a closed chamber, but did not model any phase transitions. Hence, the simulations described a vapor-only test into an unvented chamber. Nevertheless, the simulations reproduced the incident shock wave, the shock reflections, and the jet release inside the atmospheric chamber. The rapid phase transition did not contribute to the initial shock strength in the current test geometry. The evaporation rate was too low to contribute to the measured peak overpressure that was in the range of 15-20 kPa. The simulation results produced a calculated peak overpressure of 12 kPa. The liquid tests showed a significantly higher impulse compared to tests with pure vapor. Reducing the vent opening from 0.1 to 0.01 m2 resulted in a slightly higher impulse calculated at 100 ms. The influence of the vent area on the calculated impulse was significant in the vapor-phase tests, but not so clear in the liquid/vapor mixture tests.

Effective channel estimation and efficient symbol detection for multi-input multi-output underwater acoustic communications

NASA Astrophysics Data System (ADS)

Ling, Jun

Achieving reliable underwater acoustic communications (UAC) has long been recognized as a challenging problem owing to the scarce bandwidth available and the reverberant spread in both time and frequency domains. To pursue high data rates, we consider a multi-input multi-output (MIMO) UAC system, and our focus is placed on two main issues regarding a MIMO UAC system: (1) channel estimation, which involves the design of the training sequences and the development of a reliable channel estimation algorithm, and (2) symbol detection, which requires interference cancelation schemes due to simultaneous transmission from multiple transducers. To enhance channel estimation performance, we present a cyclic approach for designing training sequences with good auto- and cross-correlation properties, and a channel estimation algorithm called the iterative adaptive approach (IAA). Sparse channel estimates can be obtained by combining IAA with the Bayesian information criterion (BIC). Moreover, we present sparse learning via iterative minimization (SLIM) and demonstrate that SLIM gives similar performance to IAA but at a much lower computational cost. Furthermore, an extension of the SLIM algorithm is introduced to estimate the sparse and frequency modulated acoustic channels. The extended algorithm is referred to as generalization of SLIM (GoSLIM). Regarding symbol detection, a linear minimum mean-squared error based detection scheme, called RELAX-BLAST, which is a combination of vertical Bell Labs layered space-time (V-BLAST) algorithm and the cyclic principle of the RELAX algorithm, is presented and it is shown that RELAX-BLAST outperforms V-BLAST. We show that RELAX-BLAST can be implemented efficiently by making use of the conjugate gradient method and diagonalization properties of circulant matrices. This fast implementation approach requires only simple fast Fourier transform operations and facilitates parallel implementations. The effectiveness of the proposed MIMO schemes is verified by both computer simulations and experimental results obtained by analyzing the measurements acquired in multiple in-water experiments.

Treatment outcomes of chronic post-traumatic headaches after mild head trauma in US soldiers: an observational study.

PubMed

Erickson, Jay C

2011-06-01

he effectiveness of medical therapies for chronic post-traumatic headaches (PTHs) attributable to mild head trauma in military troops has not been established. To determine the treatment outcomes of acute and prophylactic medical therapies prescribed for chronic PTHs after mild head trauma in US Army soldiers. A retrospective cohort study was conducted with 100 soldiers undergoing treatment for chronic PTH at a single US Army neurology clinic. Headache frequency and Migraine Disability Assessment (MIDAS) scores were determined at the initial clinic visit and then again by phone 3 months after starting headache prophylactic medication. Response rates of headache abortive medications were also determined. Treatment outcomes were compared between subjects with blast-related PTH and non-blast PTH. Ninety-nine of 100 subjects were male. Seventy-seven of 100 subjects had blast PTH and 23/100 subjects had non-blast PTH. Headache characteristics were similar for blast PTH and non-blast PTH with 96% and 95%, respectively, resembling migraine. Headache frequency among all PTH subjects decreased from 17.1 days/month at baseline to 14.5 days/month at follow-up (P = .009). Headache frequency decreased by 41% among non-blast PTH compared to 9% among blast PTH. Fifty-seven percent of non-blast PTH subjects had a 50% or greater decline in headache frequency compared to 29% of blast PTH subjects (P =.023). A significant decline in headache frequency occurred in subjects treated with topiramate (n = 29, -23%, P = .02) but not among those treated with a low-dose tricyclic antidepressant (n = 48, -12%, P = .23). Seventy percent of PTH subjects who used a triptan class medication experienced reliable headache relief within 2 hours compared to 42% of subjects using other headache abortive medications (P = .01). Triptan medications were effective for both blast PTH and non-blast PTH (66% response rate vs 86% response rate, respectively; P = .20). Headache-related disability, as measured by mean MIDAS scores, declined by 57% among all PTH subjects with no significant difference between blast PTH (-56%) and non-blast PTH (-61%). Triptan class medications are usually effective for aborting headaches in military troops with chronic PTH attributed to a concussion from a blast injury or non-blast injury. Topiramate appears to be an effective headache prophylactic therapy in military troops with chronic PTH, whereas low doses of tricyclic antidepressants appear to have little efficacy. Chronic PTH triggered by a blast injury may be less responsive to commonly prescribed headache prophylactic medications compared to non-blast PTH. These conclusions require validation by prospective, controlled clinical trials. © 2011 American Headache Society.

Effect of Human and Sheep Lung Orientation on Primary Blast Injury Induced by Single Blast

DTIC Science & Technology

2010-09-01

may be injured by m ore than one of these mechanisms in any given event. Primary blast in juries ( PBI ) are exclusively caused by the blast...overpressure. A PBI usually affects air-containing organs such as t he lung, ears and gastrointestinal tract. Secon dary blast injuries are caused by...orientation on blast injuries predicted in human and sheep models. From th is study, it is predicted that the greatest reduction in lung PBI may be

Evaluation of the Effectiveness of Wet Blast Cleaning Methods of Surface Preparation

DTIC Science & Technology

1985-06-01

for Air Abrasive Wet Blast: Complete System Water Abrasive Mixing Chamber in Slurry Blast Unit Schematic of unit Control Unit Slurry Blast — Air/Water...this discussion we present some general. user guidelines regarding what to look for in con- sidering the use or purchase of wet blasting equipment...These units use compressed air as the medium to propel the eroding material. They differ from air abrasive wet blast units in that the abrasive is mixed

Portable convertible blast effects shield

DOEpatents

Pastrnak, John W.; Hollaway, Rocky; Henning, Carl D.; Deteresa, Steve; Grundler, Walter; Hagler,; Lisle B.; Kokko, Edwin; Switzer, Vernon A

2010-10-26

A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

Portable convertible blast effects shield

DOEpatents

Pastrnak, John W [Livermore, CA; Hollaway, Rocky [Modesto, CA; Henning, Carl D [Livermore, CA; Deteresa, Steve [Livermore, CA; Grundler, Walter [Hayward, CA; Hagler, Lisle B [Berkeley, CA; Kokko, Edwin [Dublin, CA; Switzer, Vernon A [Livermore, CA

2007-05-22

A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

Primary Blast-Induced Traumatic Brain Injury in Rats Leads to Increased Prion Protein in Plasma: A Potential Biomarker for Blast-Induced Traumatic Brain Injury

PubMed Central

Pham, Nam; Sawyer, Thomas W.; Wang, Yushan; Jazii, Ferdous Rastgar; Vair, Cory

2015-01-01

Abstract Traumatic brain injury (TBI) is deemed the “signature injury” of recent military conflicts in Afghanistan and Iraq, largely because of increased blast exposure. Injuries to the brain can often be misdiagnosed, leading to further complications in the future. Therefore, the use of protein biomarkers for the screening and diagnosis of TBI is urgently needed. In the present study, we have investigated the plasma levels of soluble cellular prion protein (PrPC) as a novel biomarker for the diagnosis of primary blast-induced TBI (bTBI). We hypothesize that the primary blast wave can disrupt the brain and dislodge extracellular localized PrPC, leading to a rise in concentration within the systemic circulation. Adult male Sprague–Dawley rats were exposed to single pulse shockwave overpressures of varying intensities (15-30 psi or 103.4–206.8 kPa] using an advanced blast simulator. Blood plasma was collected 24 h after insult, and PrPC concentration was determined with a modified commercial enzyme-linked immunosorbent assay (ELISA) specific for PrPC. We provide the first report that mean PrPC concentration in primary blast exposed rats (3.97 ng/mL±0.13 SE) is significantly increased compared with controls (2.46 ng/mL±0.14 SE; two tailed test p<0.0001). Furthermore, we report a mild positive rank correlation between PrPC concentration and increasing blast intensity (psi) reflecting a plateaued response at higher pressure magnitudes, which may have implications for all military service members exposed to blast events. In conclusion, it appears that plasma levels of PrPC may be a novel biomarker for the detection of primary bTBI. PMID:25058115

Influence of Basalt Mesh Induced Increase of Heterogeneity of Cement Composites with Dispersed Fibers on Its Resistance under Near-Field Blast

NASA Astrophysics Data System (ADS)

Zíma, J.; Foglar, M.

2017-09-01

This paper describes the influence of multiple basalt meshes in the cement composite specimens on the damage induced by near-field blast. Experimental measurements performed in the Boletice military area in 2014 and 2015 are evaluated by numerical simulations. The evaluation of the results is mainly focused on the stress propagation in the cement composite with dispersed fibers, the propagation of the overpressure caused by the blast and velocity of the ejected parts from the specimen. The influence of the presence and position of the basalt meshes in the specimen on its damage induced by delamination is also examined.

Novel Approach to Conducting Blast Load Analyses Using Abaqus/Explicit-CEL

DTIC Science & Technology

2010-05-01

versus uncased, effects of afterburning , angle of incidence with respect to incoming shock, nearby geometry/barriers interacting with the shock...2. Blast parameters as a function of scaled distance – from TNT air blast data (DOE/TIC-11268, 1981). Due to inertial effects, the volume of air...positive phase duration) can be determined for a particular scaled distance. Figure 2 was generated from TNT air blast data for bare, spherical charges

Military blast exposure, ageing and white matter integrity

PubMed Central

Trotter, Benjamin B.; Robinson, Meghan E.; Milberg, William P.; McGlinchey, Regina E.

2015-01-01

Mild traumatic brain injury, or concussion, is associated with a range of neural changes including altered white matter structure. There is emerging evidence that blast exposure—one of the most pervasive causes of casualties in the recent overseas conflicts in Iraq and Afghanistan—is accompanied by a range of neurobiological events that may result in pathological changes to brain structure and function that occur independently of overt concussion symptoms. The potential effects of brain injury due to blast exposure are of great concern as a history of mild traumatic brain injury has been identified as a risk factor for age-associated neurodegenerative disease. The present study used diffusion tensor imaging to investigate whether military-associated blast exposure influences the association between age and white matter tissue structure integrity in a large sample of veterans of the recent conflicts (n = 190 blast-exposed; 59 without exposure) between the ages of 19 and 62 years. Tract-based spatial statistics revealed a significant blast exposure × age interaction on diffusion parameters with blast-exposed individuals exhibiting a more rapid cross-sectional age trajectory towards reduced tissue integrity. Both distinct and overlapping voxel clusters demonstrating the interaction were observed among the examined diffusion contrast measures (e.g. fractional anisotropy and radial diffusivity). The regions showing the effect on fractional anisotropy included voxels both within and beyond the boundaries of the regions exhibiting a significant negative association between fractional anisotropy and age in the entire cohort. The regional effect was sensitive to the degree of blast exposure, suggesting a ‘dose-response’ relationship between the number of blast exposures and white matter integrity. Additionally, there was an age-independent negative association between fractional anisotropy and years since most severe blast exposure in a subset of the blast-exposed group, suggesting a specific influence of time since exposure on tissue structure, and this effect was also independent of post-traumatic stress symptoms. Overall, these data suggest that blast exposure may negatively affect brain-ageing trajectories at the microstructural tissue level. Additional work examining longitudinal changes in brain tissue integrity in individuals exposed to military blast forces will be an important future direction to the initial findings presented here. PMID:26033970

Distributed Mobile Device Based Shooter Detection Simulation

DTIC Science & Technology

2013-09-01

three signatures of a gunshot ( muzzle flash [optical], muzzle blast [auditory], and shock wave [auditory]), we focus only on information from the...bullet, while this proximity is important when using information from the shock wave. Detecting and using the muzzle flash would require accurate...Additionally, the mobile device would need to be aimed towards the blast to even have a chance detect the muzzle flash . 2.1 Single Microphone When a sound is

Non-Impact, Blast-Induced Mild TBI and PTSD: Concepts and Caveats

DTIC Science & Technology

2011-07-01

has been verified by wound ballistics experiments in animals and finite element simulation of blast loads on the torso. Blood surge caused by...ballistic pressure waves in animals An experimental study of wound ballistics demon- strates that a ballistic pressure wave can cause a remote injury to...surge. This hypothesis has been supported by some experimental data. A volumetric surge of blood moved through the thorax and abdomen has been observed

Numerical simulation of blast wave propagation in vicinity of standalone prism on flat plate

NASA Astrophysics Data System (ADS)

Valger, Svetlana; Fedorova, Natalya; Fedorov, Alexander

2018-03-01

In the paper, numerical simulation of shock wave propagation in the vicinity of a standalone prism and a prism with a cavity in front of it was carried out. The modeling was based on the solution of 3D Euler equations and Fluent software was used as a main computational tool. The algorithm for local dynamic mesh adaptation to high gradients of pressure was applied. The initial stage of the explosion of condensed explosive was described with the help of "Compressed balloon method". The research allowed describing the characteristic stages of the blast in a semi-closed space, the structure of secondary shock waves and their interaction with obstacles. The numerical approach in Fluent based on combining inviscid gas dynamics methods and "Compressed balloon method" was compared with the method which had been used by the authors earlier with the help of AUTODYN and which is based on the use of the hydrodynamic model of a material to describe state of detonation products. For the problem of shock wave propagation in the vicinity of standalone prism the comparison of the simulation results obtained using both the methods with the experimental data was performed on the dependence of static pressure and effective momentum on time for the characteristic points located on prism walls.

Cerebellar White Matter Abnormalities following Primary Blast Injury in US Military Personnel

PubMed Central

Mac Donald, Christine; Johnson, Ann; Cooper, Dana; Malone, Thomas; Sorrell, James; Shimony, Joshua; Parsons, Matthew; Snyder, Abraham; Raichle, Marcus; Fang, Raymond; Flaherty, Stephen; Russell, Michael; Brody, David L.

2013-01-01

Little is known about the effects of blast exposure on the human brain in the absence of head impact. Clinical reports, experimental animal studies, and computational modeling of blast exposure have suggested effects on the cerebellum and brainstem. In US military personnel with isolated, primary blast-related ‘mild’ traumatic brain injury and no other known insult, we found diffusion tensor MRI abnormalities consistent with cerebellar white matter injury in 3 of 4 subjects. No abnormalities in other brain regions were detected. These findings add to the evidence supporting the hypothesis that primary blast exposure contributes to brain injury in the absence of head impact and that the cerebellum may be particularly vulnerable. However, the clinical effects of these abnormalities cannot be determined with certainty; none of the subjects had ataxia or other detected evidence of cerebellar dysfunction. The details of the blast events themselves cannot be disclosed at this time, thus additional animal and computational modeling will be required to dissect the mechanisms underlying primary blast-related traumatic brain injury. Furthermore, the effects of possible subconcussive impacts and other military-related exposures cannot be determined from the data presented. Thus many aspects of topic will require further investigation. PMID:23409052

Navier-Stokes simulations of unsteady transonic flow phenomena

NASA Technical Reports Server (NTRS)

Atwood, C. A.

1992-01-01

Numerical simulations of two classes of unsteady flows are obtained via the Navier-Stokes equations: a blast-wave/target interaction problem class and a transonic cavity flow problem class. The method developed for the viscous blast-wave/target interaction problem assumes a laminar, perfect gas implemented in a structured finite-volume framework. The approximately factored implicit scheme uses Newton subiterations to obtain the spatially and temporally second-order accurate time history of the blast-waves with stationary targets. The inviscid flux is evaluated using either of two upwind techniques, while the full viscous terms are computed by central differencing. Comparisons of unsteady numerical, analytical, and experimental results are made in two- and three-dimensions for Couette flows, a starting shock-tunnel, and a shock-tube blockage study. The results show accurate wave speed resolution and nonoscillatory discontinuity capturing of the predominantly inviscid flows. Viscous effects were increasingly significant at large post-interaction times. While the blast-wave/target interaction problem benefits from high-resolution methods applied to the Euler terms, the transonic cavity flow problem requires the use of an efficient scheme implemented in a geometrically flexible overset mesh environment. Hence, the Reynolds averaged Navier-Stokes equations implemented in a diagonal form are applied to the cavity flow class of problems. Comparisons between numerical and experimental results are made in two-dimensions for free shear layers and both rectangular and quieted cavities, and in three-dimensions for Stratospheric Observatory For Infrared Astronomy (SOFIA) geometries. The acoustic behavior of the rectangular and three-dimensional cavity flows compare well with experiment in terms of frequency, magnitude, and quieting trends. However, there is a more rapid decrease in computed acoustic energy with frequency than observed experimentally owing to numerical dissipation. In addition, optical phase distortion due to the time-varying density field is modelled using geometrical constructs. The computed optical distortion trends compare with the experimentally inferred result, but underpredicts the fluctuating phase difference magnitude.

Micro-blast waves using detonation transmission tubing

NASA Astrophysics Data System (ADS)

Samuelraj, I. Obed; Jagadeesh, G.; Kontis, K.

2013-07-01

Micro-blast waves emerging from the open end of a detonation transmission tube were experimentally visualized in this study. A commercially available detonation transmission tube was used (Nonel tube, M/s Dyno Nobel, Sweden), which is a small diameter tube coated with a thin layer of explosive mixture (HMX + traces of Al) on its inner side. The typical explosive loading for this tube is of the order of 18 mg/m of tube length. The blast wave was visualized using a high speed digital camera (frame rate 1 MHz) to acquire time-resolved schlieren images of the resulting flow field. The visualization studies were complemented by computational fluid dynamic simulations. An analysis of the schlieren images showed that although the blast wave appears to be spherical, it propagates faster along the tube axis than along a direction perpendicular to the tube axis. Additionally, CFD analysis revealed the presence of a barrel shock and Mach disc, showing structures that are typical of an underexpanded jet. A theory in use for centered large-scale explosions of intermediate strength (10 < Δ {p}/{p}_0 ≲ 0.02) gave good agreement with the blast trajectory along the tube axis. The energy of these micro-blast waves was found to be 1.25 ± 0.94 J and the average TNT equivalent was found to be 0.3. The repeatability in generating these micro-blast waves using the Nonel tube was very good (± 2 %) and this opens up the possibility of using this device for studying some of the phenomena associated with muzzle blasts in the near future.

Simulation of fundamental atomization mechanisms in fuel sprays

NASA Technical Reports Server (NTRS)

Childs, Robert, E.; Mansour, Nagi N.

1988-01-01

Growth of instabilities on the liquid/gas interface in the initial region of fuel sprays is studied by means of numerical simulations. The simulations are based on solutions of the variable-density incompressible Navier-Stokes equations, which are obtained with a new numerical algorithm. The simulations give good agreement with analytical results for the instabilities on a liquid cylinder induced by surface tension and wind-induced instabilities. The effects of boundary layers on the wind-induced instabilities are investigated. It is found that a boundary layer reduces the growth rate for a single interface, and a comparison with inviscid theory suggests that boundary layer effects may be significantly more important than surface tension effects. The results yield a better estimate than inviscid theory for the drop sizes as reported for diesel sprays. Results for the planar jet show that boundary layer effects hasten the growth of Squire's 'symmetric' mode, which is responsible for jet disintegration. This result helps explain the rapid atomization which occurs in swirl and air-blast atomizers.

A Conformal, Fully-Conservative Approach for Predicting Blast Effects on Ground Vehicles

DTIC Science & Technology

2014-04-01

time integration  Approximate Riemann Fluxes (HLLE, HLLC) ◦ Robust mixture model for multi-material flows  Multiple Equations of State ◦ Perfect Gas...Loci/CHEM: Chemically reacting compressible flow solver . ◦ Currently in production use by NASA for the simulation of rocket motors, plumes, and...vehicles  Loci/DROPLET: Eulerian and Lagrangian multiphase solvers  Loci/STREAM: pressure-based solver ◦ Developed by Streamline Numerics and

Grit blasting and the marginal accuracy of two ceramic veneer systems--a pilot study.

PubMed

Lim, C; Ironside, J G

1997-04-01

Margins of ceramic restorations can be damaged during removal of investment materials with grit blasting and result in relatively large marginal discrepancies and excessive marginal discrepancies with greater exposure of cement to the oral environment. Subsequent dissolution of cement can encourage plaque retention, dental caries, and periodontal problems. This study compared marginal adaptation of ceramic veneers created by the refractory die technique (R), Dicor glass ceramic technique (D), and effects of grit blasting on their margins. Two groups of ceramic veneers were constructed for each system, one without grit blasting (R g and D g) and one with grit blasting (R+g and D+g). Statistical analyses revealed that grit blasting had a greater effect in reducing marginal accuracy for Dicor ceramic veneers compared with refractory die ceramic veneers.

Simulation of crack propagation in rock in plasma blasting technology

NASA Astrophysics Data System (ADS)

Ikkurthi, V. R.; Tahiliani, K.; Chaturvedi, S.

Plasma Blasting Technology (PBT) involves the production of a pulsed electrical discharge by inserting a blasting probe in a water-filled cavity drilled in a rock, which produces shocks or pressure waves in the water. These pulses then propagate into the rock, leading to fracture. In this paper, we present the results of two-dimensional hydrodynamic simulations using the SHALE code to study crack propagation in rock. Three separate issues have been examined. Firstly, assuming that a constant pressure P is maintained in the cavity for a time τ , we have determined the P- τ curve that just cracks a given rock into at least two large-sized parts. This study shows that there exists an optimal pressure level for cracking a given rock-type and geometry. Secondly, we have varied the volume of water in which the initial energy E is deposited, which corresponds to different initial peak pressures Ppeak. We have determined the E- Ppeak curve that just breaks the rock into four large-sized parts. It is found that there must be an optimal Ppeak that lowers the energy consumption, but with acceptable probe damage. Thirdly, we have attempted to identify the dominant mechanism of rock fracture. We also highlight some numerical errors that must be kept in mind in such simulations.

Discrete element simulation of charging and mixed layer formation in the ironmaking blast furnace

NASA Astrophysics Data System (ADS)

Mitra, Tamoghna; Saxén, Henrik

2016-11-01

The burden distribution in the ironmaking blast furnace plays an important role for the operation as it affects the gas flow distribution, heat and mass transfer, and chemical reactions in the shaft. This work studies certain aspects of burden distribution by small-scale experiments and numerical simulation by the discrete element method (DEM). Particular attention is focused on the complex layer-formation process and the problems associated with estimating the burden layer distribution by burden profile measurements. The formation of mixed layers is studied, and a computational method for estimating the extent of the mixed layer, as well as its voidage, is proposed and applied on the results of the DEM simulations. In studying a charging program and its resulting burden distribution, the mixed layers of coke and pellets were found to show lower voidage than the individual burden layers. The dynamic evolution of the mixed layer during the charging process is also analyzed. The results of the study can be used to gain deeper insight into the complex charging process of the blast furnace, which is useful in the design of new charging programs and for mathematical models that do not consider the full behavior of the particles in the burden layers.

Numerical simulation of the effect of regular and sub-caliber projectiles on military bunkers

NASA Astrophysics Data System (ADS)

Jiricek, Pavel; Foglar, Marek

2015-09-01

One of the most demanding topics in blast and impact engineering is the modelling of projectile impact. To introduce this topic, a set of numerical simulations was undertaken. The simulations study the impact of regular and sub-calibre projectile on Czech pre-WW2 military bunkers. The penetrations of the military objects are well documented and can be used for comparison. The numerical model composes of a part from a wall of a military object. The concrete block is subjected to an impact of a regular and sub-calibre projectile. The model is divided into layers to simplify the evaluation of the results. The simulations are processed within ANSYS AUTODYN software. A nonlinear material model of with damage and incorporated strain-rate effect was used. The results of the numerical simulations are evaluated in means of the damage of the concrete block. Progress of the damage is described versus time. The numerical simulation provides good agreement with the documented penetrations.

Characterization of molecular identity and pathogenicity of rice blast fungus in Hunan province of China

USDA-ARS?s Scientific Manuscript database

Characterization of molecular identity and pathogenicity of the rice blast fungus benefits the deployment of effective blast resistance (R) genes. In order to identify blast resistance genes in rice producing areas where most of the hybrid rice is grown in Hunan province, 182 M. oryzae strains were ...

A Simulation Environment for the Dynamic Evaluation of Disaster Preparedness Policies and Interventions

PubMed Central

Lewis, Bryan; Swarup, Samarth; Bisset, Keith; Eubank, Stephen; Marathe, Madhav; Barrett, Chris

2013-01-01

Disasters affect a society at many levels. Simulation based studies often evaluate the effectiveness of one or two response policies in isolation and are unable to represent impact of the policies to coevolve with others. Similarly, most in-depth analyses are based on a static assessment of the “aftermath” rather than capturing dynamics. We have developed a data-centric simulation environment for applying a systems approach to a dynamic analysis of complex combinations of disaster responses. We analyze an improvised nuclear detonation in Washington DC with this environment. The simulated blast affects the transportation system, communications infrastructure, electrical power system, behaviors and motivations of population, and health status of survivors. The effectiveness of partially restoring wireless communications capacity is analyzed in concert with a range of other disaster response policies. Despite providing a limited increase in cell phone communication, overall health was improved. PMID:23903394

Elucidation of Inflammation Processes Exacerbating Neuronal Cell Damage to the Retina and Brain Visual Centers as Quest for Therapeutic Drug Targets in Rat Model of Blast Overpressure Wave Exposure

DTIC Science & Technology

tissues, as carried out by immune cells; and thus is a promising target. Scope and timing, however, of this process must be better understood. Our study...uses an adult rat model of eye and brain injuries, as produced by exposure to simulated blast waves in a shock tube. Rats were kept on an omega-3

Effects of Blast Overpressure on Neurons and Glial Cells in Rat Organotypic Hippocampal Slice Cultures

PubMed Central

Miller, Anna P.; Shah, Alok S.; Aperi, Brandy V.; Budde, Matthew D.; Pintar, Frank A.; Tarima, Sergey; Kurpad, Shekar N.; Stemper, Brian D.; Glavaski-Joksimovic, Aleksandra

2015-01-01

Due to recent involvement in military conflicts, and an increase in the use of explosives, there has been an escalation in the incidence of blast-induced traumatic brain injury (bTBI) among US military personnel. Having a better understanding of the cellular and molecular cascade of events in bTBI is prerequisite for the development of an effective therapy that currently is unavailable. The present study utilized organotypic hippocampal slice cultures (OHCs) exposed to blast overpressures of 150 kPa (low) and 280 kPa (high) as an in vitro bTBI model. Using this model, we further characterized the cellular effects of the blast injury. Blast-evoked cell death was visualized by a propidium iodide (PI) uptake assay as early as 2 h post-injury. Quantification of PI staining in the cornu Ammonis 1 and 3 (CA1 and CA3) and the dentate gyrus regions of the hippocampus at 2, 24, 48, and 72 h following blast exposure revealed significant time dependent effects. OHCs exposed to 150 kPa demonstrated a slow increase in cell death plateauing between 24 and 48 h, while OHCs from the high-blast group exhibited a rapid increase in cell death already at 2 h, peaking at ~24 h post-injury. Measurements of lactate dehydrogenase release into the culture medium also revealed a significant increase in cell lysis in both low- and high-blast groups compared to sham controls. OHCs were fixed at 72 h post-injury and immunostained for markers against neurons, astrocytes, and microglia. Labeling OHCs with PI, neuronal, and glial markers revealed that the blast-evoked extensive neuronal death and to a lesser extent loss of glial cells. Furthermore, our data demonstrated activation of astrocytes and microglial cells in low- and high-blasted OHCs, which reached a statistically significant difference in the high-blast group. These data confirmed that our in vitro bTBI model is a useful tool for studying cellular and molecular changes after blast exposure. PMID:25729377

Nuclear Fusion Blast and Electrode Lifetimes in a PJMIF Reactor

NASA Astrophysics Data System (ADS)

Thio, Y. C. Francis; Witherspoon, F. D.; Case, A.; Brockington, S.; Cruz, E.; Luna, M.; Hsu, S. C.

2017-10-01

We present an analysis and numerical simulation of the nuclear blast from the micro-explosion following the completion of the fusion burn for a baseline design of a PJMIF fusion reactor with a fusion gain of 20. The stagnation pressure from the blast against the chamber wall defines the engineering requirement for the structural design of the first wall and the plasma guns. We also present an analysis of the lifetimes of the electrodes of the plasma guns which are exposed to (1) the high current, and (2) the neutron produced by the fusion reactions. We anticipate that the gun electrodes are made of tungsten alloys as plasma facing components reinforced structurally by appropriate steel alloys. Making reasonable assumptions about the electrode erosion rate (100 ng/C transfer), the electrode lifetime limited by the erosion rate is estimated to be between 19 and 24 million pulses before replacement. Based on known neutron radiation effects on structural materials such as steel alloys and plasma facing component materials such as tungsten alloys, the plasma guns are expected to survive some 22 million shots. At 1 Hz, this equal to about 6 months of continuous operation before they need to be replaced. Work supported by Strong Atomics, LLC.

Reconstruction of Axial Energy Deposition in Magnetic Liner Inertial Fusion Based on PECOS Shadowgraph Unfolds Using the AMR Code FLASH

NASA Astrophysics Data System (ADS)

Adams, Marissa; Jennings, Christopher; Slutz, Stephen; Peterson, Kyle; Gourdain, Pierre; U. Rochester-Sandia Collaboration

2017-10-01

Magnetic Liner Inertial Fusion (MagLIF) experiments incorporate a laser to preheat a deuterium filled capsule before compression via a magnetically imploding liner. In this work, we focus on the blast wave formed in the fuel during the laser preheat component of MagLIF, where approximately 1kJ of energy is deposited in 3ns into the capsule axially before implosion. To model blast waves directly relevant to experiments such as MagLIF, we inferred deposited energy from shadowgraphy of laser-only experiments preformed at the PECOS target chamber using the Z-Beamlet laser. These energy profiles were used to initialize 2-dimensional simulations using by the adaptive mesh refinement code FLASH. Gradients or asymmetries in the energy deposition may seed instabilities that alter the fuel's distribution, or promote mix, as the blast wave interacts with the liner wall. The AMR capabilities of FLASH allow us to study the development and dynamics of these instabilities within the fuel and their effect on the liner before implosion. Sandia Natl Labs is managed by NTES of Sandia, LLC., a subsidiary of Honeywell International, Inc, for the U.S. DOEs NNSA under contract DE-NA0003525.

Hydrodynamic Simulations of Kepler's Supernova Remnant

NASA Astrophysics Data System (ADS)

Sullivan, Jessica; Blondin, John; Borkowski, Kazik; Reynolds, Stephen

2018-01-01

Kepler’s supernova remnant contains unusual features that strongly suggest an origin in a single-degenerate Type Ia explosion, including anisotropic circumstellar medium (CSM), a strong brightness gradient, and spatially varying expansion proper motions. We present 3Dhydrodynamic simulations to test a picture in which Kepler's progenitor binary emitted a strong asymmetric wind, densest in the orbital plane, while the system moved at high velocity through the ISM. We simulate the creation of the presupernova environment as well as the supernova blast wave, using the VH-1 grid-based hydrodynamics code. We first modeled an anisotropic wind to create an asymmetric bowshock around the progenitor, then the blast wave from thesupernova. The final simulation places both previous model pieces onto a single grid and allows the blast wave to expand into the bowshock. Models were completed on a Yin-Yang grids with matching angular resolutions. By manipulating parameters that control the asymmetry of the system, we attempted to find conditions that recreated the current state of Kepler. We analyzed these models by comparing images of Kepler from the Chandra X-ray Observatory to line-of-sight projections from the model results. We also present comparisons of simulated expansion velocities with recent observations of X-ray proper motions from Chandra images. We were able to produce models that contained similar features to those seen in Kepler. We find the greatest resemblance to Kepler images with a presupernova wind with an equator-to-pole density contrast of 3 and a moderately disk-like CSM at a 5° angle between equatorial plane and system motion.

An RES-Based Model for Risk Assessment and Prediction of Backbreak in Bench Blasting

NASA Astrophysics Data System (ADS)

Faramarzi, F.; Ebrahimi Farsangi, M. A.; Mansouri, H.

2013-07-01

Most blasting operations are associated with various forms of energy loss, emerging as environmental side effects of rock blasting, such as flyrock, vibration, airblast, and backbreak. Backbreak is an adverse phenomenon in rock blasting operations, which imposes risk and increases operation expenses because of safety reduction due to the instability of walls, poor fragmentation, and uneven burden in subsequent blasts. In this paper, based on the basic concepts of a rock engineering systems (RES) approach, a new model for the prediction of backbreak and the risk associated with a blast is presented. The newly suggested model involves 16 effective parameters on backbreak due to blasting, while retaining simplicity as well. The data for 30 blasts, carried out at Sungun copper mine, western Iran, were used to predict backbreak and the level of risk corresponding to each blast by the RES-based model. The results obtained were compared with the backbreak measured for each blast, which showed that the level of risk achieved is in consistence with the backbreak measured. The maximum level of risk [vulnerability index (VI) = 60] was associated with blast No. 2, for which the corresponding average backbreak was the highest achieved (9.25 m). Also, for blasts with levels of risk under 40, the minimum average backbreaks (<4 m) were observed. Furthermore, to evaluate the model performance for backbreak prediction, the coefficient of correlation ( R 2) and root mean square error (RMSE) of the model were calculated ( R 2 = 0.8; RMSE = 1.07), indicating the good performance of the model.

Optimization and application of blasting parameters based on the "pushing-wall" mechanism

NASA Astrophysics Data System (ADS)

Ren, Feng-yu; Sow, Thierno Amadou Mouctar; He, Rong-xing; Liu, Xin-rui

2012-10-01

The large structure parameter of a sublevel caving method was used in Beiminghe iron mine. The ores were generally lower than the medium hardness and easy to be drilled and blasted. However, the questions of boulder yield, "pushing-wall" accident rate, and brow damage rate were not effectively controlled in practical blasting. The model test of a similar material shows that the charge concentration of bottom blastholes in the sector is too high; the pushing wall is the fundamental reason for the poor blasting effect. One of the main methods to adjust the explosive distribution is to increase the length of charged blastholes. Therefore, the field tests with respect to increasing the length of uncharged blastholes were made in 12# stope of -95 subsection and 6# stope of Beiminghe iron mine. This paper took the test result of 12# stope as an example to analyze the impact of charge structure on blasting effect and design an appropriate blasting parameter that is to similar to No.12 stope.

Paint removal activities in Canada

NASA Astrophysics Data System (ADS)

Foster, Terry

1993-03-01

Paint removal activities currently under way in Canada include: research and development of laser paint stripping; development and commercialization of a new blasting medium based on wheat starch; commercialization of a new blasting medium and process using crystalline ice blasting for paint removal and surface cleaning; and the development of automated and robotic systems for paint stripping applications. A specification for plastic media blasting (PMB) of aircraft and aircraft components is currently being drafted by NDHQ for use by the Canadian Armed Forces (CAF) and contractors involved in coating removal for the CAF. Defense Research Establishment Pacific (DREP) is studying the effects of various blast media on coating removal rates, and minimizing the possibility of damage to substrates other than aluminum such as graphite epoxy composite and Kevlar. The effects of plastic media blasting on liquid penetrant detection of fatigue cracks is also under investigation.

Effects of granulocyte-macrophage colony-stimulating factor and interleukin 6 on the growth of leukemic blasts in suspension culture.

PubMed

Tsao, C J; Cheng, T Y; Chang, S L; Su, W J; Tseng, J Y

1992-05-01

We examined the stimulatory effects of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 6 (IL)-6 on the in vitro proliferation of leukemic blast cells from patients with acute leukemia. Bone marrow or peripheral blood leukemic blast cells were obtained from 21 patients, including 14 cases of acute myeloblastic leukemia (AML), four cases of acute lymphoblastic leukemia (ALL), two cases of acute undifferentiated leukemia, and one case of acute mixed-lineage leukemia. The proliferation of leukemic blast cells was evaluated by measuring the incorporation of 3H-thymidine into cells incubated with various concentrations of cytokines for 3 days. GM-CSF stimulated the DNA synthesis (with greater than 2.0 stimulation index) of blast cells in 9 of 14 (64%) AML cases, two cases of acute undifferentiated leukemia and one case of acute mixed-lineage leukemia. Only two cases of AML blasts responded to IL-6 to grow in the short-term suspension cultures. GM-CSF and IL-6 did not display a synergistic effect on the growth of leukemic cells. Moreover, GM-CSF and IL-6 did not stimulate the proliferation of ALL blast cells. Binding study also revealed the specific binding of GM-CSF on the blast cells of acute undifferentiated leukemia and acute mixed-lineage leukemia. Our results indicated that leukemic blast cells of acute undifferentiated leukemia and acute mixed-lineage leukemia possessed functional GM-CSF receptors.

Two-dimensional explosion experiments examining the interaction between a blast wave and a sand hill

NASA Astrophysics Data System (ADS)

Sugiyama, Y.; Izumo, M.; Ando, H.; Matsuo, A.

2018-05-01

Two-dimensional explosion experiments were conducted to discuss the interaction between a blast wave and sand and show the mitigation effect of the sand on the blast wave. The explosive used was a detonating cord 1.0 m in length, which was initiated in a sand hill shaped like a triangular prism and whose cross section was an isosceles triangle with base angles of 30°. Sand-hill heights of 30 and 60 mm were used as parameters to discuss the effect of sand mass upon blast-wave strength. The interaction of the blast wave with the sand/air interface causes multiple peaks in the blast wave, which are induced by successive transmissions at the interface. The increase in the sand mass further mitigates the blast parameters of peak overpressure and positive impulse. The results of this experiment can be utilized to validate the numerical method of solving the problem of interaction between a compressible fluid and a particle layer.

Two-dimensional explosion experiments examining the interaction between a blast wave and a sand hill

NASA Astrophysics Data System (ADS)

Sugiyama, Y.; Izumo, M.; Ando, H.; Matsuo, A.

2018-02-01

Two-dimensional explosion experiments were conducted to discuss the interaction between a blast wave and sand and show the mitigation effect of the sand on the blast wave. The explosive used was a detonating cord 1.0 m in length, which was initiated in a sand hill shaped like a triangular prism and whose cross section was an isosceles triangle with base angles of 30°. Sand-hill heights of 30 and 60 mm were used as parameters to discuss the effect of sand mass upon blast-wave strength. The interaction of the blast wave with the sand/air interface causes multiple peaks in the blast wave, which are induced by successive transmissions at the interface. The increase in the sand mass further mitigates the blast parameters of peak overpressure and positive impulse. The results of this experiment can be utilized to validate the numerical method of solving the problem of interaction between a compressible fluid and a particle layer.

Portable convertible blast effects shield

DOEpatents

Pastrnak, John W [Livermore, CA; Hollaway, Rocky [Modesto, CA; Henning, Carl D [Livermore, CA; Deteresa, Steve [Livermore, CA; Grundler, Walter [Hayward, CA; Hagler, Lisle B [Berkeley, CA; Kokko, Edwin [Dublin, CA; Switzer, Vernon A [Livermore, CA

2011-03-15

A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more frusto-conically-tapered telescoping rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration by the friction fit of adjacent pairs of frusto-conically-tapered rings to each other.

The Effects of Repeated Low-Level Blast Exposure on Hearing in Marines

PubMed Central

Kubli, Lina R.; Pinto, Robin L.; Burrows, Holly L.; Littlefield, Philip D.; Brungart, Douglas S.

2017-01-01

Background: The study evaluates a group of Military Service Members specialized in blast explosive training called “Breachers” who are routinely exposed to multiple low-level blasts while teaching breaching at the U.S. Marine Corps in Quantico Virginia. The objective of this study was to determine if there are any acute or long-term auditory changes due to repeated low-level blast exposures used in training. The performance of the instructor group “Breachers” was compared to a control group, “Engineers”. Methods: A total of 11 Breachers and four engineers were evaluated in the study. The participants received comprehensive auditory tests, including pure-tone testing, speech-in-noise (SIN) measures, and central auditory behavioral and objective tests using early and late (P300) auditory evoked potentials over a period of 17 months. They also received shorter assessments immediately following the blast-exposure onsite at Quantico. Results: No acute or longitudinal effects were identified. However, there were some interesting baseline effects found in both groups. Contrary to the expected, the onsite hearing thresholds and distortion product otoacoustic emissions were slightly better at a few frequencies immediately after blast-exposure than measurements obtained with the same equipment weeks to months after each blast-exposure. Conclusions: To date, the current study is the most comprehensive study that evaluates the long-term effects of blast-exposure on hearing. Despite extensive testing to assess changes, the findings of this study suggest that the levels of current exposures used in this military training environment do not seem to have an obvious deleterious effect on hearing. PMID:28937017

Modelling and Experimental Verification of Pressure Wave Following Gaseous Helium Storage Tank Rupture

NASA Astrophysics Data System (ADS)

Chorowski, M.; Grabowski, M.; Jędrusyna, A.; Wach, J.

Helium inventory in high energy accelerators, tokamaks and free electron lasers may exceed tens of tons. The gaseous helium is stored in steel tanks under a pressure of about 20 bar and at environment temperature. Accidental rupture of any of the tanks filled with the gaseous helium will create a rapid energy release in form of physical blast. An estimation of pressure wave distribution following the tank rupture and potential consequences to the adjacent research infrastructure and buildings is a very important task, critical in the safety aspect of the whole cryogenic system. According to the present regulations the TNT equivalent approach is to be applied to evaluate the pressure wave following a potential gas storage tank rupture. A special test stand was designed and built in order to verify experimentally the blast effects in controlled conditions. In order to obtain such a shock wave a pressurized plastic tank was used. The tank was ruptured and the resulting pressure wave was recorded using a spatially-distributed array of pressure sensors connected to a high-speed data acquisition device. The results of the experiments and the comparison with theoretical values obtained from thermodynamic model of the blast are presented. A good agreement between the simulated and measured data was obtained. Recommendations regarding the applicability of thermodynamic model of physical blast versus TNT approach, to estimate consequences of gas storage tank rupture are formulated. The laboratory scale experimental results have been scaled to ITER pressurized helium storage tanks.

Perspectives on repeated low-level blast and the measurement of neurotrauma in humans as an occupational exposure risk

NASA Astrophysics Data System (ADS)

Carr, W.; Dell, K. C.; Yanagi, M. A.; Hassan, D. M.; LoPresti, M. L.

2017-11-01

A pressing question in military medical research is the nature and degree of effects on the human brain from occupational repeated exposure to low-level explosive blast, but reliable and effective means to objectively measure such effects remain elusive. In survey results, headache, difficulty sleeping, irritability, cognitive impairment, and a variety of other symptoms consistent with post-concussive syndrome have been reported by those exposed to blast and there was positive correlation between degree of blast exposure and degree of symptomology, but an important goal is to obtain more objective evidence of an effect than self-report alone. This review reflects recent efforts to measure and evaluate such hypothesized effects and current recommendations for ongoing study. Optimal measures are likely those with sensitivity and specificity to systemic effects in mild neurotrauma, that have minimal to no volitional component, and that can be sampled relatively quickly with minimal intrusion in prospective, observational field studies during routine training with explosives. An understanding of an association between parameters of exposure to repeated low-level blast and negative neurologic effects would support the evaluation of clinical implications and development of protective equipment and surveillance protocols where warranted. At present, low-level blast exposure surveillance measurements do not exist as a systematic record for any professional community.

Welding-Induced Microstructure Evolution of a Cu-Bearing High-Strength Blast-Resistant Steel

NASA Astrophysics Data System (ADS)

Caron, Jeremy L.; Babu, Sudarsanam Suresh; Lippold, John C.

2011-12-01

A new high strength, high toughness steel containing Cu for precipitation strengthening was recently developed for naval, blast-resistant structural applications. This steel, known as BlastAlloy160 (BA-160), is of nominal composition Fe-0.05C-3.65Cu-6.5Ni-1.84Cr-0.6Mo-0.1V (wt pct). The evident solidification substructure of an autogenous gas tungsten arc (GTA) weld suggested fcc austenite as the primary solidification phase. The heat-affected zone (HAZ) hardness ranged from a minimum of 353 HV in the coarse-grained HAZ (CGHAZ) to a maximum of 448 HV in the intercritical HAZ (ICHAZ). After postweld heat treatment (PWHT) of the spot weld, hardness increases were observed in the fusion zone (FZ), CGHAZ, and fine-grained HAZ (FGHAZ) regions. Phase transformation and metallographic analyses of simulated single-pass HAZ regions revealed lath martensite to be the only austenitic transformation product in the HAZ. Single-pass HAZ simulations revealed a similar hardness profile for low heat-input (LHI) and high heat-input (HHI) conditions, with higher hardness values being measured for the LHI samples. The measured hardness values were in good agreement with those from the GTA weld. Single-pass HAZ regions exhibited higher Charpy V-notch impact toughness than the BM at both test temperatures of 293 K and 223 K (20 °C and -50 °C). Hardness increases were observed for multipass HAZ simulations employing an initial CGHAZ simulation.

Blast-Induced Tinnitus and Elevated Central Auditory and Limbic Activity in Rats: A Manganese-Enhanced MRI and Behavioral Study.

PubMed

Ouyang, Jessica; Pace, Edward; Lepczyk, Laura; Kaufman, Michael; Zhang, Jessica; Perrine, Shane A; Zhang, Jinsheng

2017-07-07

Blast-induced tinitus is the number one service-connected disability that currently affects military personnel and veterans. To elucidate its underlying mechanisms, we subjected 13 Sprague Dawley adult rats to unilateral 14 psi blast exposure to induce tinnitus and measured auditory and limbic brain activity using manganese-enhanced MRI (MEMRI). Tinnitus was evaluated with a gap detection acoustic startle reflex paradigm, while hearing status was assessed with prepulse inhibition (PPI) and auditory brainstem responses (ABRs). Both anxiety and cognitive functioning were assessed using elevated plus maze and Morris water maze, respectively. Five weeks after blast exposure, 8 of the 13 blasted rats exhibited chronic tinnitus. While acoustic PPI remained intact and ABR thresholds recovered, the ABR wave P1-N1 amplitude reduction persisted in all blast-exposed rats. No differences in spatial cognition were observed, but blasted rats as a whole exhibited increased anxiety. MEMRI data revealed a bilateral increase in activity along the auditory pathway and in certain limbic regions of rats with tinnitus compared to age-matched controls. Taken together, our data suggest that while blast-induced tinnitus may play a role in auditory and limbic hyperactivity, the non-auditory effects of blast and potential traumatic brain injury may also exert an effect.

Effect of the Cold-Sprayed Aluminum Coating-Substrate Interface Morphology on Bond Strength for Aircraft Repair Application

NASA Astrophysics Data System (ADS)

Blochet, Quentin; Delloro, Francesco; N'Guyen, Franck; Jeulin, Dominique; Borit, François; Jeandin, Michel

2017-04-01

This article is dealing with the effects of surface preparation of the substrate on aluminum cold-sprayed coating bond strength. Different sets of AA2024-T3 specimens have been coated with pure Al 1050 feedstock powder, using a conventional cold spray coating technique. The sets were grit-blasted (GB) before coating. The study focuses on substrate surface topography evolution before coating and coating-substrate interface morphology after coating. To study coating adhesion by LASAT® technique for each set, specimens with and without preceding GB treatment were tested in load-controlled conditions. Then, several techniques were used to evaluate the effects of substrate surface treatment on the final coating mechanical properties. Irregularities induced by the GB treatment modify significantly the interface morphology. Results showed that particle anchoring was improved dramatically by the presence of craters. The substrate surface was characterized by numerous anchors. Numerical simulation results exhibited the increasing deformation of particle onto the grit-blasted surface. In addition, results showed a strong relationship between the coating-substrate bond strength on the deposited material and surface preparation.

A computational fluid dynamics simulation of high- and low-current arcs in self-blast circuit breakers

NASA Astrophysics Data System (ADS)

Claessens, M.; Möller, K.; Thiel, H. G.

1997-07-01

Computational fluid dynamics calculations for high- and low-current arcs in an interrupter of the self-blast type have been performed. The mixing process of the hot PTFE cloud with the cold 0022-3727/30/13/011/img6 in the pressure chamber is strongly inhomogeneous. The existence of two different species has been taken into account by interpolation of the material functions according to their mass fraction in each grid cell. Depending on the arcing time, fault current and interrupter geometry, blow temperatures of up to 2000 K have been found. The simulation results for a decaying arc immediately before current zero yield a significantly reduced arc cooling at the stagnation point for high blow temperatures.

Experimental Investigation of Cavitation as a Possible Damage Mechanism in Blast-Induced Traumatic Brain Injury in Post-Mortem Human Subject Heads.

PubMed

Salzar, Robert S; Treichler, Derrick; Wardlaw, Andrew; Weiss, Greg; Goeller, Jacques

2017-04-15

The potential of blast-induced traumatic brain injury from the mechanism of localized cavitation of the cerebrospinal fluid (CSF) is investigated. While the mechanism and criteria for non-impact blast-induced traumatic brain injury is still unknown, this study demonstrates that local cavitation in the CSF layer of the cranial volume could contribute to these injuries. The cranial contents of three post-mortem human subject (PMHS) heads were replaced with both a normal saline solution and a ballistic gel mixture with a simulated CSF layer. Each were instrumented with multiple pressure transducers and placed inside identical shock tubes at two different research facilities. Sensor data indicates that cavitation may have occurred in the PMHS models at pressure levels below those for a 50% risk of blast lung injury. This study points to skull flexion, the result of the shock wave on the front of the skull leading to a negative pressure in the contrecoup, as a possible mechanism that contributes to the onset of cavitation. Based on observation of intracranial pressure transducer data from the PMHS model, cavitation onset is thought to occur from approximately a 140 kPa head-on incident blast.

Analysis of In-Flight Collision Process During V-Type Firing Pattern in Surface Blasting Using Simple Physics

NASA Astrophysics Data System (ADS)

Chouhan, Lalit Singh; Raina, Avtar K.

2015-10-01

Blasting is a unit operation in Mine-Mill Fragmentation System (MMFS) and plays a vital role in mining cost. One of the goals of MMFS is to achieve optimum fragment size at minimal cost. Blast fragmentation optimization is known to result in better explosive energy utilization. Fragmentation depends on the rock, explosive and blast design variables. If burden, spacing and type of explosive used in a mine are kept constant, the firing sequence of blast-holes plays a vital role in rock fragmentation. To obtain smaller fragmentation size, mining professionals and relevant publications recommend V- or extended V-pattern of firing sequence. In doing so, it is assumed that the in-flight air collision breaks larger rock fragments into smaller ones, thus aiding further fragmentation. There is very little support to the phenomenon of breakage during in-flight collision of fragments during blasting in published literature. In order to assess the breakage of in-flight fragments due to collision, a mathematical simulation was carried over using basic principles of physics. The calculations revealed that the collision breakage is dependent on velocity of fragments, mass of fragments, the strength of the rock and the area of fragments over which collision takes place. For higher strength rocks, the in-flight collision breakage is very difficult to achieve. This leads to the conclusion that the concept demands an in-depth investigation and validation.

Full-scale testing of leakage of blast waves inside a partially vented room exposed to external air blast loading

NASA Astrophysics Data System (ADS)

Codina, R.; Ambrosini, D.

2018-03-01

For the last few decades, the effects of blast loading on structures have been studied by many researchers around the world. Explosions can be caused by events such as industrial accidents, military conflicts or terrorist attacks. Urban centers have been prone to various threats including car bombs, suicide attacks, and improvised explosive devices. Partially vented constructions subjected to external blast loading represent an important topic in protective engineering. The assessment of blast survivability inside structures and the development of design provisions with respect to internal elements require the study of the propagation and leakage of blast waves inside buildings. In this paper, full-scale tests are performed to study the effects of the leakage of blast waves inside a partially vented room that is subjected to different external blast loadings. The results obtained may be useful for proving the validity of different methods of calculation, both empirical and numerical. Moreover, the experimental results are compared with those computed using the empirical curves of the US Defense report/manual UFC 3-340. Finally, results of the dynamic response of the front masonry wall are presented in terms of accelerations and an iso-damage diagram.

Dry ice blasting

NASA Astrophysics Data System (ADS)

Lonergan, Jeffrey M.

1992-04-01

As legal and societal pressures against the use of hazardous waste generating materials has increased, so has the motivation to find safe, effective, and permanent replacements. Dry ice blasting is a technology which uses CO2 pellets as a blasting medium. The use of CO2 for cleaning and stripping operations offers potential for significant environmental, safety, and productivity improvements over grit blasting, plastic media blasting, and chemical solvent cleaning. Because CO2 pellets break up and sublime upon impact, there is no expended media to dispose of. Unlike grit or plastic media blasting which produce large quantities of expended media, the only waste produced by CO2 blasting is the material removed. The quantity of hazardous waste produced, and thus the cost of hazardous waste disposal is significantly reduced.

Thermal oxidation of medical Ti6Al4V blasted with ceramic particles: Effects on the microstructure, residual stresses and mechanical properties.

PubMed

Lieblich, M; Barriuso, S; Multigner, M; González-Doncel, G; González-Carrasco, J L

2016-02-01

Roughening of Ti6Al4V by blasting with alumina or zirconia particles improves the mechanical fixation of implants by increasing the surface area available for bone/implant apposition. Additional thermal oxidation treatments of the blasted alloy have already shown to be a complementary low-cost solution to enhancing the in vitro biocompatibility and corrosion resistance of the alloy. In this work, the effects of oxidation treatment on a grit blasted Ti6Al4V biomedical alloy have been analysed in order to understand the net effect of the combined treatments on the alloy fatigue properties. Synchrotron radiation diffraction experiments have been performed to measure residual stresses before and after the treatments and microstructural and hardness changes have been determined. Although blasting of Ti6Al4V with small spherical zirconia particles increases the alloy fatigue resistance with respect to unblasted specimens, fatigue strength after oxidation decreases below the unblasted value, irrespective of the type of particle used for blasting. Moreover, at 700°C the as-blasted compressive residual stresses (700MPa) are not only fully relaxed but even moderate tensile residual stresses, of about 120MPa, are found beneath the blasted surfaces. Contrary to expectations, a moderate increase in hardness occurs towards the blasted surface after oxidation treatments. This can be attributed to the fact that grit blasting modifies the crystallographic texture of the Ti6Al4V shifting it to a random texture, which affects the hardness values as shown by additional experiments on cold rolled samples. The results indicate that the oxidation treatment performed to improve biocompatibility and corrosion resistance of grit blasted Ti6Al4V should be carried out with caution since the alloy fatigue strength can be critically diminished below the value required for high load-bearing components. Copyright © 2015 Elsevier Ltd. All rights reserved.

Transient Interaction Between Reduction and Slagging Reactions of Wustite in Simulated Cohesive Zone of Blast Furnace

NASA Astrophysics Data System (ADS)

Ma, Kaihui; Xu, Jian; Deng, Junyi; Wang, Dongdong; Xu, Yang; Liao, Zhehan; Sun, Chengfeng; Zhang, Shengfu; Wen, Liangying

2018-06-01

The blast furnace cohesive zone plays an important role in the gas flow distribution and heat-transfer efficiency. Previous work mainly employed temperature-based indices to evaluate and predict the shape and thickness of the cohesive zone, whereas the internal reactions and related effects on the softening and melting properties of a complex burden are ignored. In this study, an innovative index, namely, shrinkage rate (SR), is first proposed to directly estimate the shrinkage behavior of wustite (FeO)-packed bed inside a simulated cohesive zone. The index is applied as the temperature increases to elucidate the transient interaction between reduction and slagging reactions. Results show that the thermally induced slagging reaction causes the packed bed to shrink at lower temperature, and the SR doubles when compounds with low melting temperature are generated by adding a reasonable concentration of CaO or SiO2. The reduction reaction becomes the driving force during the shrinkage of the packed bed between 1173 K and 1273 K when CO is introduced in the mixture gas. Then, the dominating factors for further shrinkage include slagging, reduction, or both factors. These factors vary with respect to the added compounds or temperature.

Blast injury from explosive munitions.

PubMed

Cernak, I; Savic, J; Ignjatovic, D; Jevtic, M

1999-07-01

To evaluate the effect of blast in common war injuries. One thousand three hundred and three patients injured by explosive munitions and demonstrating extremity wounds without other penetrating injuries were admitted to the Military Medical Academy in Belgrade between 1991 and 1994. Of these, 665 patients (51%) had symptoms and physical signs that were compatible with the clinical diagnosis of primary blast injury, whereas the remaining 658 patients did not. Random sampling of 65 patients in the blast group during the early posttraumatic period showed statistically significant elevations in blood thromboxane A2 (TxA2), prostacyclin (PGI2), and sulfidopeptide leukotrienes compared with the random sample of 62 patients in the nonblast group. This difference could not be accounted for by differing injury severity between the groups, because the severity of wounds as measured by both the Injury Severity Score and the Red Cross Wound Classification was similar in both groups. Amongst blast patients, 200 patients (30%) had long-term (1 year) symptoms and signs reflecting central nervous system disorders. These symptoms and signs were only sporadically found in 4% of the nonblast patients. These findings indicate that primary blast injury is more common in war injuries than previously thought and that of those affected by blast, a surprisingly high proportion retain long-term neurologic disability. The elevation in eicosanoids could be used to confirm and monitor blast injury. In relation to the immediate management of patients injured by explosive weapons, it follows that particular attention should be paid to the presence and/or development of blast injury. Our findings indicate that blast is more common in war injuries than previously thought. Eicosanoid changes after blast injury suggest that blast injury causes a major physiologic stress. A variety of effects on the central nervous system suggest that blast injury could be responsible for some aspects of what is now considered to be the posttraumatic stress disorder.

Double shock front formation in cylindrical radiative blast waves produced by laser irradiation of krypton gas

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

Kim, I.; Quevedo, H. J.; Feldman, S.

2013-12-15

Radiative blast waves were created by irradiating a krypton cluster source from a supersonic jet with a high intensity femtosecond laser pulse. It was found that the radiation from the shock surface is absorbed in the optically thick upstream medium creating a radiative heat wave that travels supersonically ahead of the main shock. As the blast wave propagates into the heated medium, it slows and loses energy, and the radiative heat wave also slows down. When the radiative heat wave slows down to the transonic regime, a secondary shock in the ionization precursor is produced. This paper presents experimental datamore » characterizing both the initial and secondary shocks and numerical simulations to analyze the double-shock dynamics.« less

Numerical Simulation of Blast Action on Civil Structures in Urban Environment

NASA Astrophysics Data System (ADS)

Valger, Svetlana A.; Fedorova, Natalya N.; Fedorov, Alexander V.

2017-10-01

Nowadays, a lot of industrial accidents accompanied by explosions are happening throughout the world. Also, increase in the number of terrorist acts committed by means of explosions is observed. For improving safety of buildings and structures it is necessary to raise their resistance to explosive effects, as well as to be able to predict degree of potential damage upon explosive loads of various intensities. One of the principal goals in designing the structure resistant to explosive effects is to determine the dynamic response of structures to the impact of the blast wave. To this end, the transient pressure loads on the walls of the civil engineering structures are to be determined. The simulation of explosion is highly complicated, involving an explosion causing the shock wave propagation in air and then interaction with a structure. The engineering-level techniques permit one to estimate an explosive shock impact only for isolated buildings. The complexity of the building, the presence of nearby structures and the surrounding environment cannot be taken into account. Advanced computer aid engineering (CAE) software techniques combined with the latest methods of discrete three-dimensional city modelling permits one to simulate and analyse the effects of explosions in urban areas with a precision which previously was not possible. In the paper, the simulation results are presented of shock wave forming due to a spherical explosive charge and its propagation in the vicinity of geometrical configuration imitating an urban environment. The numerical simulation of a flow in the vicinity of prisms of different cross-sections and heights located on a flat plate was performed. The calculations are carried out in a three-dimensional non-viscous formulation using ANSYS software. On a basis of simulation results, a complex wave structures were analysed, and all the peculiarities of flows and pressure history records on building walls were described and explained. The possibility of a correct description of the non-stationary wave flow in the vicinity of the complex of obstacles is demonstrated. The results are compared with the experimental data on the pressure distribution in gauges located on the prism walls. The estimation of shock wave exposure intensity was performed to different objects.

Dynamic Analysis of Tunnel in Weathered Rock Subjected to Internal Blast Loading

NASA Astrophysics Data System (ADS)

Tiwari, Rohit; Chakraborty, Tanusree; Matsagar, Vasant

2016-11-01

The present study deals with three-dimensional nonlinear finite element (FE) analyses of a tunnel in rock with reinforced concrete (RC) lining subjected to internal blast loading. The analyses have been performed using the coupled Eulerian-Lagrangian analysis tool available in FE software Abaqus/Explicit. Rock and RC lining are modeled using three-dimensional Lagrangian elements. Beam elements have been used to model reinforcement in RC lining. Three different rock types with different weathering conditions have been used to understand the response of rock when subjected to blast load. The trinitrotoluene (TNT) explosive and surrounding air have been modeled using the Eulerian elements. The Drucker-Prager plasticity model with strain rate-dependent material properties has been used to simulate the stress-strain response of rock. The concrete damaged plasticity model and Johnson-Cook plasticity model have been used for the simulation of stress-strain response of concrete and steel, respectively. The explosive (TNT) has been modeled using Jones-Wilkins-Lee (JWL) equation of state. The analysis results have been studied for stresses, deformation and damage of RC lining and the surrounding rock. It is observed that damage in RC lining results in higher stress in rock. Rocks with low modulus and high weathering conditions show higher attenuation of shock wave. Higher amount of ground shock wave propagation is observed in case of less weathered rock. Ground heave is observed under blast loading for tunnel close to ground surface.

Relationship between orientation to a blast and pressure wave propagation inside the rat brain.

PubMed

Chavko, Mikulas; Watanabe, Tomas; Adeeb, Saleena; Lankasky, Jason; Ahlers, Stephen T; McCarron, Richard M

2011-01-30

Exposure to a blast wave generated during an explosion may result in brain damage and related neurological impairments. Several mechanisms by which the primary blast wave can damage the brain have been proposed, including: (1) a direct effect of the shock wave on the brain causing tissue damage by skull flexure and propagation of stress and shear forces; and (2) an indirect transfer of kinetic energy from the blast, through large blood vessels and cerebrospinal fluid (CSF), to the central nervous system. To address a basic question related to the mechanisms of blast brain injury, pressure was measured inside the brains of rats exposed to a low level of blast (~35kPa), while positioned in three different orientations with respect to the primary blast wave; head facing blast, right side exposed to blast and head facing away from blast. Data show different patterns and durations of the pressure traces inside the brain, depending on the rat orientation to blast. Frontal exposures (head facing blast) resulted in pressure traces of higher amplitude and longer duration, suggesting direct transmission and reflection of the pressure inside the brain (dynamic pressure transfer). The pattern of the pressure wave inside the brain in the head facing away from blast exposures assumes contribution of the static pressure, similar to hydrodynamic pressure to the pressure wave inside the brain. Published by Elsevier B.V.

Effect of blast furnace slag on self-healing of microcracks in cementitious materials

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

Huang, Haoliang, E-mail: haoliang.huang@tudelft.nl; Ye, Guang; Magnel Laboratory for Concrete Research, Department of Structural Engineering, Ghent University

The physico-chemical process of self-healing in blast furnace slag cement paste was investigated in this paper. With a high slag content i.e., 66% in cement paste and saturated Ca(OH)₂ solution as activator, it was found that the reaction products formed in cracks are composed of C-S-H, ettringite, hydrogarnet and OH–hydrotalcite. The fraction of C-S-H in the reaction products is much larger than the other minerals. Large amount of ettringite formed in cracks indicates the leaching of SO₄⁻² ions from the bulk paste and consequently the recrystallization. Self-healing proceeds fast within 50 h and then slows down. According to thermodynamic modeling,more » when the newly formed reaction products are carbonated, the filling fraction of crack increases first and then decreases. Low soluble minerals such as silica gel, gibbsite and calcite are formed. Compared to Portland cement paste, the potential of self-healing in slag cement paste is higher when the percentage of slag is high. Highlights: • Self-healing reaction products in slag cement paste were characterized. • Self-healing reaction products formed in time were quantified with image analysis. • Self-healing in slag cement paste was simulated with a reactive transport model. • Effect of carbonation on self-healing was investigated by thermodynamic modeling. • Effect of slag on self-healing was discussed based on experiments and simulation.« less

Army Blast Claims Evaluation Procedures

DTIC Science & Technology

1994-03-01

ARMY RESEARCH LABORATORY ARL-MR-131 Army Blast Claims Evaluation Procedures William P. Wright APPROVED FOR PUBUC RELEASE; DISTRIBtmON IS...NUMBERS Anny Blast Claims Evaluation Procedures 4G061-304-U2 6. AUTHOR(S) William P. Wrisht 1. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8...of the technical review process which bas been instituted to develop an opinion as to Army responsibility. 14. SUBJECT TERMS blast effects. muzzle

Wound Ballistics Modeling for Blast Loading Blunt Force Impact and Projectile Penetration.

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

Taylor, Paul A.

Light body armor development for the warfighter is based on trial-and-error testing of prototype designs against ballistic projectiles. Torso armor testing against blast is nonexistent but necessary to protect the heart and lungs. In tests against ballistic projectiles, protective apparel is placed over ballistic clay and the projectiles are fired into the armor/clay target. The clay represents the human torso and its behind-armor, permanent deflection is the principal metric used to assess armor protection. Although this approach provides relative merit assessment of protection, it does not examine the behind-armor blunt trauma to crucial torso organs. We propose a modeling andmore » simulation (M&S) capability for wound injury scenarios to the head, neck, and torso of the warfighter. We will use this toolset to investigate the consequences of, and mitigation against, blast exposure, blunt force impact, and ballistic projectile penetration leading to damage of critical organs comprising the central nervous, cardiovascular, and respiratory systems. We will leverage Sandia codes and our M&S expertise on traumatic brain injury to develop virtual anatomical models of the head, neck, and torso and the simulation methodology to capture the physics of wound mechanics. Specifically, we will investigate virtual wound injuries to the head, neck, and torso without and with protective armor to demonstrate the advantages of performing injury simulations for the development of body armor. The proposed toolset constitutes a significant advance over current methods by providing a virtual simulation capability to investigate wound injury and optimize armor design without the need for extensive field testing.« less

Blast shock wave mitigation using the hydraulic energy redirection and release technology.

PubMed

Chen, Yun; Huang, Wei; Constantini, Shlomi

2012-01-01

A hydraulic energy redirection and release technology has been developed for mitigating the effects of blast shock waves on protected objects. The technology employs a liquid-filled plastic tubing as a blast overpressure transformer to transfer kinetic energy of blast shock waves into hydraulic energy in the plastic tubings. The hydraulic energy is redirected through the plastic tubings to the openings at the lower ends, and then is quickly released with the liquid flowing out through the openings. The samples of the specifically designed body armor in which the liquid-filled plastic tubings were installed vertically as the outer layer of the body armor were tested. The blast test results demonstrated that blast overpressure behind the body armor samples was remarkably reduced by 97% in 0.2 msec after the liquid flowed out of its appropriate volume through the openings. The results also suggested that a volumetric liquid surge might be created when kinetic energy of blast shock wave was transferred into hydraulic energy to cause a rapid physical movement or displacement of the liquid. The volumetric liquid surge has a strong destructive power, and can cause a noncontact, remote injury in humans (such as blast-induced traumatic brain injury and post-traumatic stress disorder) if it is created in cardiovascular system. The hydraulic energy redirection and release technology can successfully mitigate blast shock waves from the outer surface of the body armor. It should be further explored as an innovative approach to effectively protect against blast threats to civilian and military personnel.

Blast Shock Wave Mitigation Using the Hydraulic Energy Redirection and Release Technology

PubMed Central

Chen, Yun; Huang, Wei; Constantini, Shlomi

2012-01-01

A hydraulic energy redirection and release technology has been developed for mitigating the effects of blast shock waves on protected objects. The technology employs a liquid-filled plastic tubing as a blast overpressure transformer to transfer kinetic energy of blast shock waves into hydraulic energy in the plastic tubings. The hydraulic energy is redirected through the plastic tubings to the openings at the lower ends, and then is quickly released with the liquid flowing out through the openings. The samples of the specifically designed body armor in which the liquid-filled plastic tubings were installed vertically as the outer layer of the body armor were tested. The blast test results demonstrated that blast overpressure behind the body armor samples was remarkably reduced by 97% in 0.2 msec after the liquid flowed out of its appropriate volume through the openings. The results also suggested that a volumetric liquid surge might be created when kinetic energy of blast shock wave was transferred into hydraulic energy to cause a rapid physical movement or displacement of the liquid. The volumetric liquid surge has a strong destructive power, and can cause a noncontact, remote injury in humans (such as blast-induced traumatic brain injury and post-traumatic stress disorder) if it is created in cardiovascular system. The hydraulic energy redirection and release technology can successfully mitigate blast shock waves from the outer surface of the body armor. It should be further explored as an innovative approach to effectively protect against blast threats to civilian and military personnel. PMID:22745740

CFD Applications in Support of the Space Shuttle Risk Assessment

NASA Technical Reports Server (NTRS)

Baum, Joseph D.; Mestreau, Eric; Luo, Hong; Sharov, Dmitri; Fragola, Joseph; Loehner, Rainald; Cook, Steve (Technical Monitor)

2000-01-01

The paper describes a numerical study of a potential accident scenario of the space shuttle, operating at the same flight conditions as flight 51L, the Challenger accident. The interest in performing this simulation is derived by evidence that indicates that the event itself did not exert large enough blast loading on the shuttle to break it apart. Rather, the quasi-steady aerodynamic loading on the damaged, unbalance vehicle caused the break-up. Despite the enormous explosive potential of the shuttle total fuel load (both liquid and solid), the post accident explosives working group estimated the maximum energy involvement to be equivalent to about five hundreds of pounds of TNT. This understanding motivated the simulation described here. To err on the conservative side, we modeled the event as an explosion, and used the maximum energy estimate. We modeled the transient detonation of a 500 lbs spherical charge of TNT, placed at the main engine, and the resulting blast wave propagation about the complete stack. Tracking of peak pressures and impulses at hundreds of locations on the vehicle surface indicate that the blast load was insufficient to break the vehicle, hence demonstrating likely crew survivability through such an event.

A Model to Simulate Titanium Behavior in the Iron Blast Furnace Hearth

NASA Astrophysics Data System (ADS)

Guo, Bao-Yu; Zulli, Paul; Maldonado, Daniel; Yu, Ai-Bing

2010-08-01

The erosion of hearth refractory is a major limitation to the campaign life of a blast furnace. Titanium from titania addition in the burden or tuyere injection can react with carbon and nitrogen in molten pig iron to form titanium carbonitride, giving the so-called titanium-rich scaffold or buildup on the hearth surface, to protect the hearth from subsequent erosion. In the current article, a mathematical model based on computational fluid dynamics is proposed to simulate the behavior of solid particles in the liquid iron. The model considers the fluid/solid particle flow through a packed bed, conjugated heat transfer, species transport, and thermodynamic of key chemical reactions. A region of high solid concentration is predicted at the hearth bottom surface. Regions of solid formation and dissolution can be identified, which depend on the local temperature and chemical equilibrium. The sensitivity to the key model parameters for the solid phase is analyzed. The model provides an insight into the fundamental mechanism of solid particle formation, and it may form a basic model for subsequent development to study the formation of titanium scaffold in the blast furnace hearth.

Investigating ground vibration to calculate the permissible charge weight for blasting operations of Gotvand-Olya dam underground structures / Badania drgań gruntu w celu określenia dopuszczalnego ciężaru ładunku wybuchowego przy pracach strzałowych w podziemnych elementach tamy w Gotvand-Olya

NASA Astrophysics Data System (ADS)

Soltani-Mohammadi, Saeed; Bakhshandeh Amnieh, Hassan; Bahadori, Moein

2012-12-01

Ground vibration, air vibration, fly rock, undesirable displacement and fragmentation are some inevitable side effects of blasting operations that can cause serious damage to the surrounding environment. Peak Particle Velocity (PPV) is the main criterion in the assessment of the amount of damage caused by ground vibration. There are different standards for the determination of the safe level of the PPV. To calculate the permissible amount of the explosive to control the damage to the underground structures of Gotvand Olya dam, use was made of sixteen 3-component (totally 48) records generated from 4 blasts. These operations were recorded in 3 directions (radial, transverse and vertical) by four PG-2002 seismographs having GS-11D 3-component seismometers and the records were analyzed with the help of the DADISP software. To predict the PPV, use was made of the scaled distance and the Simulated Annealing (SA) hybrid methods. Using the scaled distance resulted in a relation for the prediction of the PPV; the precision of the relation was then increased to 0.94 with the help of the SA hybrid method. Relying on the high correlation of this relation and considering a minimum distance of 56.2 m to the center of the blast site and a permissible PPV of 178 mm/s (for a 2-day old concrete), the maximum charge weight per delay came out to be 212 Kg.

The influence of clothing on human intrathoracic pressure during airblast.

PubMed

Young, A J; Jaeger, J J; Phillips, Y Y; Yelverton, J T; Richmond, D R

1985-01-01

Exposure to airblast can result in injury to the lungs and other gas-containing organs. The mechanism of lung injury is not clearly understood, but may be related to the rapid increase in intrathoracic pressure (ITP) which is produced when the blast wave strikes the chest wall. The purpose of this study was to determine if ITP during airblast would be influenced by several different types of protective clothing. Ten healthy young male volunteers were exposed to airblast while standing face-on and wearing 1) military fatigues (control condition); 2) fatigues with field jacket; 3) fatigues with ballistic armor vest; 4) fatigues with ceramic vest; 5) fatigues with ceramic vest over the ballistic vest. The incident blast waves simulated artillery muzzle blast. In each subject, an esophageal strain-gauge pressure transducer measured ITP during the blast. The pressure signal was analyzed for ITPmax, and maximum rate of rise of ITP (dP X dt max-1). In addition, the power density spectra of each ITP wave was computed and the peak frequency (fp) and centroid frequency (fc) were calculated. When the subjects wore the ballistic vest, the mean ITPmax was higher (p less than 0.05) than when they were exposed to airblast in fatigues alone. ITPmax was not influenced by the other clothing ensembles. The mean dP X dtmax-1 was not significantly different with any protective clothing ensemble. Clothing had no significant effect of fp, but with the ballistic vest, the mean calculated fc was higher (p less than 0.05) than that for the fatigues alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Current advances on genetic resistance to rice blast disease

USDA-ARS?s Scientific Manuscript database

Rice blast disease caused by the fungal pathogen Magnaporthe oryzae is one of the most threatening fungal diseases resulting in significant annual crop losses worldwide. Blast disease has been effectively managed by a combination of resistant (R) gene deployment, application of fungicides, and suita...

Implementation of Smoothed Particle Hydrodynamics for Detonation of Explosive with Application to Rock Fragmentation

NASA Astrophysics Data System (ADS)

Pramanik, R.; Deb, D.

2015-07-01

The paper presents a methodology in the SPH framework to analyze physical phenomena those occur in detonation process of an explosive. It mainly investigates the dynamic failure mechanism in surrounding brittle rock media under blast-induced stress wave and expansion of high pressure product gases. A program burn model is implemented along with JWL equation of state to simulate the reaction zone in between unreacted explosive and product gas. Numerical examples of detonation of one- and two-dimensional explosive slab have been carried out to investigate the effect of reaction zone in detonation process and outward dispersion of gaseous product. The results are compared with those obtained from existing solutions. A procedure is also developed in SPH framework to apply continuity conditions between gas and rock interface boundaries. The modified Grady-Kipp damage model for the onset of tensile yielding and Drucker-Prager model for shear failure are implemented for elasto-plastic analysis of rock medium. The results show that high compressive stress causes high crack density in the vicinity of blast hole. The major principal stress (tensile) is responsible for forming radial cracks from the blast hole. Spalling zones are also developed due to stress waves reflected from the free surfaces.

Military Blast Injury and Chronic Neurodegeneration: Research Presentations from the 2015 International State-of-the-Science Meeting.

PubMed

Agoston, Denes; Arun, Peethambaran; Bellgowan, Patrick; Broglio, Steven; Cantu, Robert; Cook, David; da Silva, Uade Olaghere; Dickstein, Dara; Elder, Gregory; Fudge, Elizabeth; Gandy, Sam; Gill, Jessica; Glenn, John F; Gupta, Raj K; Hinds, Sidney; Hoffman, Stuart; Lattimore, Theresa; Lin, Alexander; Lu, Kun Ping; Maroon, Joseph; Okonkwo, David; Perl, Daniel; Robinson, Meghan; Rosen, Charles; Smith, Douglas

2017-09-01

Blast-related traumatic brain injury (TBI) is a signature injury of recent military conflicts, leading to increased Department of Defense (DoD) interest in its potential long-term effects, such as chronic traumatic encephalopathy (CTE). The DoD Blast Injury Research Program Coordinating Office convened the 2015 International State-of-the-Science Meeting to discuss the existing evidence regarding a causal relationship between TBI and CTE. Over the course of the meeting, experts across government, academia, and the sports community presented cutting edge research on the unique pathological characteristics of blast-related TBI, blast-related neurodegenerative mechanisms, risk factors for CTE, potential biomarkers for CTE, and treatment strategies for chronic neurodegeneration. The current paper summarizes these presentations. Although many advances have been made to address these topics, more research is needed to establish the existence of links between the long-term effects of single or multiple blast-related TBI and CTE.

Controlled Low-Pressure Blast-Wave Exposure Causes Distinct Behavioral and Morphological Responses Modelling Mild Traumatic Brain Injury, Post-Traumatic Stress Disorder, and Comorbid Mild Traumatic Brain Injury-Post-Traumatic Stress Disorder.

PubMed

Zuckerman, Amitai; Ram, Omri; Ifergane, Gal; Matar, Michael A; Sagi, Ram; Ostfeld, Ishay; Hoffman, Jay R; Kaplan, Zeev; Sadot, Oren; Cohen, Hagit

2017-01-01

The intense focus in the clinical literature on the mental and neurocognitive sequelae of explosive blast-wave exposure, especially when comorbid with post-traumatic stress-related disorders (PTSD) is justified, and warrants the design of translationally valid animal studies to provide valid complementary basic data. We employed a controlled experimental blast-wave paradigm in which unanesthetized animals were exposed to visual, auditory, olfactory, and tactile effects of an explosive blast-wave produced by exploding a thin copper wire. By combining cognitive-behavioral paradigms and ex vivo brain MRI to assess mild traumatic brain injury (mTBI) phenotype with a validated behavioral model for PTSD, complemented by morphological assessments, this study sought to examine our ability to evaluate the biobehavioral effects of low-intensity blast overpressure on rats, in a translationally valid manner. There were no significant differences between blast- and sham-exposed rats on motor coordination and strength, or sensory function. Whereas most male rats exposed to the blast-wave displayed normal behavioral and cognitive responses, 23.6% of the rats displayed a significant retardation of spatial learning acquisition, fulfilling criteria for mTBI-like responses. In addition, 5.4% of the blast-exposed animals displayed an extreme response in the behavioral tasks used to define PTSD-like criteria, whereas 10.9% of the rats developed both long-lasting and progressively worsening behavioral and cognitive "symptoms," suggesting comorbid PTSD-mTBI-like behavioral and cognitive response patterns. Neither group displayed changes on MRI. Exposure to experimental blast-wave elicited distinct behavioral and morphological responses modelling mTBI-like, PTSD-like, and comorbid mTBI-PTSD-like responses. This experimental animal model can be a useful tool for elucidating neurobiological mechanisms underlying the effects of blast-wave-induced mTBI and PTSD and comorbid mTBI-PTSD.

Prediction of air blast mitigation in an array of rigid obstacles using smoothed particle hydrodynamics

NASA Astrophysics Data System (ADS)

Prasanna Kumar, S. S.; Patnaik, B. S. V.; Ramamurthi, K.

2018-04-01

The mitigation of blast waves propagating in air and interacting with rigid barriers and obstacles is numerically investigated using the mesh-free smoothed particle hydrodynamics method. A novel virtual boundary particle procedure with a skewed gradient wall boundary treatment is applied at the interfaces between air and rigid bodies. This procedure is validated with closed-form solutions for strong and weak shock reflection from rigid surfaces, supersonic flows over a wedge, formation of reflected, transverse, and Mach stem shocks, and also earlier experiments on interaction of a blast wave with concrete blocks. The mitigation of the overpressure and impulse transmitted to the protected structure due to an array of rigid obstacles of different shapes placed in the path of the blast wave is thereafter determined and discussed in the context of the existing experimental and numerical studies. It is shown that blockages having the shape of a right facing triangle or square placed in tandem or staggered provide better mitigation. The influence of the distance between the blockage array and protected structure is assessed, and the incorporation of a gap in the blockages is shown to improve the mitigation. The mechanisms responsible for the attenuation of air blast are identified through the simulations.

Subacute Oxidative Stress and Glial Reactivity in the Amygdala are Associated with Increased Anxiety Following Blast Neurotrauma.

PubMed

Sajja, Venkata Siva Sai Sujith; Hubbard, William B; VandeVord, Pamela J

2015-08-01

Behavioral symptoms, such as anxiety, are widely reported after blast overpressure (BOP) exposure. Amygdalar vulnerability to increasing magnitudes of BOP has not been investigated, and single exposures to blast have been limited to acute (<72 h) assessment. Rats were exposed to a single low, moderate, or high BOP (10, 14, or 24 psi) with an advanced blast simulator to test the susceptibility of the amygdala. Anxiety-like behavior was observed in the low- and moderate-pressure groups when subjected to the light/dark box assessment 7 days after the blast but not in high-pressure group. Immunohistochemistry was performed to measure apoptosis (cleaved caspase-3), neuronal loss (NeuN), reactive astrocytes (glial fibrillary acidic protein), microglia (Iba-1), and oxidative stress (CuZn superoxide dismutase). Slower progression of injury cascades was associated with a significant increase in anxiety, apoptosis, and astrogliosis in the low pressure group compared with others. A significant increase of CuZn superoxide dismutase in the low pressure group could be associated with neuroprotection from cell death caused by oxidative stress because neuronal loss was significant in the moderate- and high- but not the low-pressure group. Overall, this study demonstrated that overpressure as low as 10 psi can induce subacute anxiety, in addition to neuropathologic changes in the amygdala.

The Shock and Vibration Bulletin. Part 1: Invited Papers, Vibrations and Acoustics, Blast and Shock

NASA Technical Reports Server (NTRS)

1979-01-01

Development in the modeling and simulation of shock and vibration phenomena are considered. Predicting the noise exposure of payloads in the space shuttle, prediction for step-stress fatigue, pyrotechnique shock simulation using metal-to-metal impact, and prediction of fragment velocities and trajectories are among the topics covered.

A Combined Finite-Element/Discrete-Particle Analysis of a Side-Vent-Channel-Based Concept for Improved Blast-Survivability of Light Tactical Vehicles

DTIC Science & Technology

2013-01-01

design of side- vent-channels. The results obtained confirmed the beneficial effects of the side-vent-channels in reducing the blast momentum , although...confirmed the beneficial effects of the side-vent-channels in reducing the blast momentum , although the extent of these effects is relatively small (3...products against the surrounding medium is associated with exchange of linear momentum and various energy components (e.g. potential, thermal

Studies of the Effects of Perfluorocarbon Emulsions on Platelet Number and Function in Models of Critical Battlefield Injury

DTIC Science & Technology

2015-01-01

Year three: Using the ovine polytrauma model of combined hemorrhagic shock and blast TBI to test the effect of PFC intravenous infusion on platelet...could not be reassembled until late October. The schedule for testing and developing a sheep polytrauma model which combines blast injury with...This research project going forward is to assess PFC’s effect on platelet number and function in sheep 9 10 polytrauma model which combined blast

Combined Effects of Primary and Tertiary Blast on Rat Brain: Characterization of a Model of Blast-induced Mild Traumatic Brain Injury

DTIC Science & Technology

2012-03-01

blast injury mechanisms in rat TBI - Roles of polyunsaturated fatty acids in traumatic brain injury vulnerabilities and resilience: evaluation of...salutary effects of DHA supplementation using neurolipidomics and functional outcome assessments - Diagnostic and Therapeutic Targeting of...immunohistochemical assessments reveal greater glial fibrillary acidic protein (GFAP) and IBa1 immunoreactivity in rats subjected to combined injuries than are

Diffusion Tensor Imaging Reveals White Matter Injury in a Rat Model of Repetitive Blast-Induced Traumatic Brain Injury

PubMed Central

Calabrese, Evan; Du, Fu; Garman, Robert H.; Johnson, G. Allan; Riccio, Cory; Tong, Lawrence C.

2014-01-01

Abstract Blast-induced traumatic brain injury (bTBI) is one of the most common combat-related injuries seen in U.S. military personnel, yet relatively little is known about the underlying mechanisms of injury. In particular, the effects of the primary blast pressure wave are poorly understood. Animal models have proven invaluable for the study of primary bTBI, because it rarely occurs in isolation in human subjects. Even less is known about the effects of repeated primary blast wave exposure, but existing data suggest cumulative increases in brain damage with a second blast. MRI and, in particular, diffusion tensor imaging (DTI), have become important tools for assessing bTBI in both clinical and preclinical settings. Computational statistical methods such as voxelwise analysis have shown promise in localizing and quantifying bTBI throughout the brain. In this study, we use voxelwise analysis of DTI to quantify white matter injury in a rat model of repetitive primary blast exposure. Our results show a significant increase in microstructural damage with a second blast exposure, suggesting that primary bTBI may sensitize the brain to subsequent injury. PMID:24392843

Protective Effect of N-Acetylcysteine Amide on Blast-Induced Increase in Intracranial Pressure in Rats

PubMed Central

Kawoos, Usmah; McCarron, Richard M.; Chavko, Mikulas

2017-01-01

Blast-induced traumatic brain injury is associated with acute and possibly chronic elevation of intracranial pressure (ICP). The outcome after TBI is dependent on the progression of complex processes which are mediated by oxidative stress. So far, no effective pharmacological protection against TBI exists. In this study, rats were exposed to a single or repetitive blast overpressure (BOP) at moderate intensities of 72 or 110 kPa in a compressed air-driven shock tube. The degree and duration of the increase in ICP were proportional to the intensity and frequency of the blast exposure(s). In most cases, a single dose of antioxidant N-acetylcysteine amide (NACA) (500 mg/kg) administered intravenously 2 h after exposure to BOP significantly attenuated blast-induced increase in ICP. A single dose of NACA was not effective in improving the outcome in the group of animals that were subjected to repetitive blast exposures at 110 kPa on the same day. In this group, two treatments with NACA at 2 and 4 h post-BOP exposure resulted in significant attenuation of elevated ICP. Treatment with NACA prior to BOP exposure completely prevented the elevation of ICP. The findings indicate that oxidative stress plays an important role in blast-induced elevated ICP as treatment with NACA-ameliorated ICP increase, which is frequently related to poor functional recovery after TBI. PMID:28634463

Impact of blast induced transitory vibration and air-overpressure/noise on human brain--an experimental study.

PubMed

Raina, A K; Baheti, M; Haldar, A; Ramulu, M; Chakraborty, A K; Sahu, P B; Bandopadhayay, C

2004-04-01

Human response to blast induced ground vibration and air-overpressure/noise is a major concern of current mining activity. This is because the fact that mines are fast transgressing the habitats and people are getting educated. Consequently the response of humans is changing and expectedly will increase in days to come with no viable and economic alternative to blasting--an essential component of mining. The response of humans can be purely physiological or psychological in nature or combination of both depending upon the situation and conditions of mining. Where physiological response is documented in terms of effects on ears and lungs there is a meager amount or no literature available regarding effects of blasting on the brain. Moreover, the studies on transitory phenomenon like the effects of blasting on humans are rare in comparison to the whole body vibration studies. This study was designed to address the issues as a precursor to a major initiative. The preliminary investigations conducted with the monitoring of EEG responses of humans to vibration and air-overpressure/noise due to blasting revealed that there is no major response of the brain to transitory vibrations and noise.

On the formation of Friedlander waves in a compressed-gas-driven shock tube

PubMed Central

Tasissa, Abiy F.; Hautefeuille, Martin; Fitek, John H.; Radovitzky, Raúl A.

2016-01-01

Compressed-gas-driven shock tubes have become popular as a laboratory-scale replacement for field blast tests. The well-known initial structure of the Riemann problem eventually evolves into a shock structure thought to resemble a Friedlander wave, although this remains to be demonstrated theoretically. In this paper, we develop a semi-analytical model to predict the key characteristics of pseudo blast waves forming in a shock tube: location where the wave first forms, peak over-pressure, decay time and impulse. The approach is based on combining the solutions of the two different types of wave interactions that arise in the shock tube after the family of rarefaction waves in the Riemann solution interacts with the closed end of the tube. The results of the analytical model are verified against numerical simulations obtained with a finite volume method. The model furnishes a rational approach to relate shock tube parameters to desired blast wave characteristics, and thus constitutes a useful tool for the design of shock tubes for blast testing. PMID:27118888

Modelling and Testing of Blast Effect On the Structures

NASA Astrophysics Data System (ADS)

Figuli, Lucia; Jangl, Štefan; Papán, Daniel

2016-10-01

As a blasting agent in the blasting and mining engineering, has been using one of so called new generation of explosives which offer greater flexibility in their range and application, and such explosive is ANFO. It is type of explosive consists of an oxidiser and a fuel (ammonium nitrate and fuel oil). One of such ANFO explosives which are industrially made in Slovakia is POLONIT. The explosive is a mixture of ammonium nitrate, methyl esters of higher fatty acids, vegetable oil and red dye. The paper deals with the analysis of structure subjected to the blast load created by the explosion of POLONIT charge. First part of paper is describing behaviour and characteristic of blast wave generated from the blast (detonation characteristics, physical characteristics, time-history diagram etc.) and the second part presents the behaviour of such loaded structures, because of the analysis of such dynamical loaded structure is required knowing the parameters of blast wave, its effect on structure and the tools for the solution of dynamic analysis. The real field tests of three different weight of charges and two different structures were done. The explosive POLONIT was used together with 25 g of ignition explosive PLNp10. Analytical and numerical model of blast loaded structure is compared with the results obtained from the field tests (is compared with the corresponding experimental accelerations). For the modelling structures were approximated as a one-degree system of freedom (SDOF), where the blast wave was estimated with linear decay and exponential decay using positive and negative phase of blast wave. Numerical solution of the steel beam dynamic response was performed via FEM (Finite Element Method) using standard software Visual FEA.

Control technology for crystalline silica exposures in construction: wet abrasive blasting.

PubMed

Golla, Vijay; Heitbrink, William

2004-03-01

This study was designed to document the effect that wet abrasive blasting has on reducing worker exposure to crystalline silica, which has been associated with silicosis and premature death. In this study, worker exposure to respirable crystalline silica was monitored during wet abrasive blasting on the exterior walls of a parking garage to remove surface concrete and expose the underlying aggregate. In this process a wet sand mix comprised of 80% dry sand and 20% water was used. Sampling and analysis revealed that the geometric mean respirable quartz concentration was 0.2 mg/m(3) for workers conducting abrasive blasting and 0.06 mg/m(3) for helpers. When abrasive blasting was conducted in areas that apparently had reduced natural ventilation, dust exposures appeared to increase. When compared with other published data, this case study suggests that wet abrasive blasting causes less exposure to crystalline silica than dry abrasive blasting.

Application of Carbon Composite Bricks for Blast Furnace Hearth

NASA Astrophysics Data System (ADS)

Zuo, Haibin; Wang, Cong; Zhang, Jianliang; Zhao, Yongan; Jiao, Kexin

Traditional refractory materials for blast furnace hearth lining are mainly composed of carbon bricks and the ceramic cup. However, these materials can't meet the demands for long service life design of blast furnaces. In this paper, a new refractory called carbon composite brick (CCB) was introduced, which combined the advantages of carbon bricks and the ceramic cup. In this case, the resistance of the CCB against corrosion was equal to the ceramic cup and the thermal conductivity of the CCB was equal to carbon bricks. From the results of more than 20 blast furnaces, the CCB could be well used in small blast furnaces and large blast furnaces. In the bad condition of low grade burden and high smelting intensity, the CCB gave full play to the role of cooling system, and effectively resisted the erosion of hot metal to improve the service life of blast furnaces.

Understanding the Effects of Blast Wave on the Intracranial Pressure and Traumatic Brain Injury in Rodents and Humans Using Experimental Shock Tube and Numerical Simulations

DTIC Science & Technology

2014-07-01

common mechanism of injury responsible for 52% TBI cases overall [24]. The analysis also showed that intracranial injuries, particularly concussions ...about the same time Ommaya and his collegues developed scaling relations (based on Holbourn’s theory) to scale experimental concussion data on sub-human...primates to concussion threshold in man [86]. The primates were subjected to head impact and whiplash in order to produce concussions in them [87

Blast-Induced Acceleration in a Shock Tube: Distinguishing Primary and Tertiary Blast Injury

DTIC Science & Technology

2016-10-01

objects of varied areal densities to define relations of blast flow conditions to acceleration and displacement , we have begun examination of the effects... displacement from other biomechanical components and effects of the shockwave. 15. SUBJECT TERMS Key words or phrases identifying major concepts in the...and total pressure, positive phase duration, and impulse) and acceleration and displacement of a wide range of inanimate objects, we have continued

Flow of supersonic jets across flat plates: Implications for ground-level flow from volcanic blasts

NASA Astrophysics Data System (ADS)

Orescanin, Mara M.; Prisco, David; Austin, Joanna M.; Kieffer, Susan W.

2014-04-01

We report on laboratory experiments examining the interaction of a jet from an overpressurized reservoir with a canonical ground surface to simulate lateral blasts at volcanoes such as the 1980 blast at Mount St. Helens. These benchmark experiments test the application of supersonic jet models to simulate the flow of volcanic jets over a lateral topography. The internal shock structure of the free jet is modified such that the Mach disk shock is elevated above the surface. In elevation view, the width of the shock is reduced in comparison with a free jet, while in map view the dimensions are comparable. The distance of the Mach disk shock from the vent is in good agreement with free jet data and can be predicted with existing theory. The internal shock structures can interact with and penetrate the boundary layer. In the shock-boundary layer interaction, an oblique shock foot is present in the schlieren images and a distinctive ground signature is evident in surface measurements. The location of the oblique shock foot and the surface demarcation are closely correlated with the Mach disk shock location during reservoir depletion, and therefore, estimates of a ground signature in a zone devastated by a blast can be based on the calculated shock location from free jet theory. These experiments, combined with scaling arguments, suggest that the imprint of the Mach disk shock on the ground should be within the range of 4-9 km at Mount St. Helens depending on assumed reservoir pressure and vent dimensions.

Human Injury Criteria for Underwater Blasts

PubMed Central

Lance, Rachel M.; Capehart, Bruce; Kadro, Omar; Bass, Cameron R.

2015-01-01

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. PMID:26606655

Repeat low-level blast exposure increases transient receptor potential vanilloid 1 (TRPV1) and endothelin-1 (ET-1) expression in the trigeminal ganglion

PubMed Central

Burke, Teresa A.; Doyle Brackley, Allison; Jeske, Nathaniel A.; Cleland, Jeffery M.; Lund, Brian J.

2017-01-01

Blast-associated sensory and cognitive trauma sustained by military service members is an area of extensively studied research. Recent studies in our laboratory have revealed that low-level blast exposure increased expression of transient receptor potential vanilloid 1 (TRPV1) and endothelin-1 (ET-1), proteins well characterized for their role in mediating pain transmission, in the cornea. Determining the functional consequences of these alterations in protein expression is critical to understanding blast-related sensory trauma. Thus, the purpose of this study was to examine TRPV1 and ET-1 expression in ocular associated sensory tissues following primary and tertiary blast. A rodent model of blast injury was used in which anesthetized animals, unrestrained or restrained, received a single or repeat blast (73.8 ± 5.5 kPa) from a compressed air shock tube once or daily for five consecutive days, respectively. Behavioral and functional analyses were conducted to assess blast effects on nocifensive behavior and TRPV1 activity. Immunohistochemistry and Western Blot were also performed with trigeminal ganglia (TG) to determine TRPV1, ET-1 and glial fibrillary associated protein (GFAP) expression following blast. Increased TRPV1, ET-1 and GFAP were detected in the TG of animals exposed to repeat blast. Increased nocifensive responses were also observed in animals exposed to repeat, tertiary blast as compared to single blast and control. Moreover, decreased TRPV1 desensitization was observed in TG neurons exposed to repeat blast. Repeat, tertiary blast resulted in increased TRPV1, ET-1 and GFAP expression in the TG, enhanced nociception and decreased TRPV1 desensitization. PMID:28797041

Isochoric heating and strong blast wave formation driven by fast electrons in solid-density targets

NASA Astrophysics Data System (ADS)

Santos, J. J.; Vauzour, B.; Touati, M.; Gremillet, L.; Feugeas, J.-L.; Ceccotti, T.; Bouillaud, R.; Deneuville, F.; Floquet, V.; Fourment, C.; Hadj-Bachir, M.; Hulin, S.; Morace, A.; Nicolaï, Ph; d'Oliveira, P.; Reau, F.; Samaké, A.; Tcherbakoff, O.; Tikhonchuk, V. T.; Veltcheva, M.; Batani, D.

2017-10-01

We experimentally investigate the fast (< 1 {ps}) isochoric heating of multi-layer metallic foils and subsequent high-pressure hydrodynamics induced by energetic electrons driven by high-intensity, high-contrast laser pulses. The early-time temperature profile inside the target is measured from the streaked optical pyrometry of the target rear side. This is further characterized from benchmarked simulations of the laser-target interaction and the fast electron transport. Despite a modest laser energy (< 1 {{J}}), the early-time high pressures and associated gradients launch inwards a strong compression wave developing over ≳ 10 ps into a ≈ 140 {Mbar} blast wave, according to hydrodynamic simulations, consistent with our measurements. These experimental and numerical findings pave the way to a short-pulse-laser-based platform dedicated to high-energy-density physics studies.

A Parametric Approach to Shape Field-Relevant Blast Wave Profiles in Compressed-Gas-Driven Shock Tube

PubMed Central

Sundaramurthy, Aravind; Chandra, Namas

2014-01-01

Detonation of a high-explosive produces shock-blast wave, shrapnel, and gaseous products. While direct exposure to blast is a concern near the epicenter, shock-blast can affect subjects, even at farther distances. When a pure shock-blast wave encounters the subject, in the absence of shrapnels, fall, or gaseous products the loading is termed as primary blast loading and is the subject of this paper. The wave profile is characterized by blast overpressure, positive time duration, and impulse and called herein as shock-blast wave parameters (SWPs). These parameters in turn are uniquely determined by the strength of high explosive and the distance of the human subjects from the epicenter. The shape and magnitude of the profile determine the severity of injury to the subjects. As shown in some of our recent works (1–3), the profile not only determines the survival of the subjects (e.g., animals) but also the acute and chronic biomechanical injuries along with the following bio-chemical sequelae. It is extremely important to carefully design and operate the shock tube to produce field-relevant SWPs. Furthermore, it is vital to identify and eliminate the artifacts that are inadvertently introduced in the shock-blast profile that may affect the results. In this work, we examine the relationship between shock tube adjustable parameters (SAPs) and SWPs that can be used to control the blast profile; the results can be easily applied to many of the laboratory shock tubes. Further, replication of shock profile (magnitude and shape) can be related to field explosions and can be a standard in comparing results across different laboratories. Forty experiments are carried out by judiciously varying SAPs such as membrane thickness, breech length (66.68–1209.68 mm), measurement location, and type of driver gas (nitrogen, helium). The effects SAPs have on the resulting shock-blast profiles are shown. Also, the shock-blast profiles of a TNT explosion from ConWep software is compared with the profiles obtained from the shock tube. To conclude, our experimental results demonstrate that a compressed-gas shock tube when designed and operated carefully can replicate the blast time profiles of field explosions accurately. Such a faithful replication is an essential first step when studying the effects of blast induced neurotrauma using animal models. PMID:25520701

Fragmentation, Cost and Environmental Effects of Plaster Stemming Method for Blasting at A Basalt Quarry

NASA Astrophysics Data System (ADS)

Cevizci, Halim

2014-10-01

In this study, the plaster stemming application for blasting at a basalt quarry is studied. Drill cuttings are generally used in open pits and quarries as the most common stemming material since these are most readily available at blast sites. However, dry drill cuttings eject very easily from blastholes without offering much resistance to blast energy. The plaster stemming method has been found to be better than the drill cuttings stemming method due to increased confinement inside the hole and better utilization of blast explosive energy in the rock. The main advantage of the new stemming method is the reduction in the cost of blasting. At a basalt quarry, blasting costs per unit volume of rock were reduced to 15% by increasing burden and spacing distances. In addition, better fragmentation was obtained by using the plaster stemming method. Blast trials showed that plaster stemming produced finer material. In the same blast tests, +30 cm size fragments were reduced to 47.3% of the total, compared to 32.6% in the conventional method of drill cuttings stemming. With this method of stemming, vibration and air shock values increased slightly due to more blast energy being available for rock breakage but generally these increased values were small and stayed under the permitted limit for blast damage criteria unless measuring distance is too close.

Application of directional blasting in mining and civil engineering, 1986

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

Chernigovskii, A.A.

1986-01-01

The author describes the mechanism of breaking mineral rocks through blasting and offers recommendations on the application of directional blasting in mining and civil engineering. He also introduces criteria for cost-effectiveness of transporting rock mass from stope to pile by means of energy of explosion. And, the book presents ballistic tables to be used in constructing the trajectory of movement of a rock fragment during blasting operations while taking into account the topography of the land. In this edition, the author presents a more detailed theoretical treatment on the mechanism of fragmentation of a monolithic or fissured rock mass throughmore » blasting.« less

Progress on Protection of Titanium-Bearing Materials in Chinese Blast Furnace

NASA Astrophysics Data System (ADS)

Cai, Qiuye; Zhang, Jianliang; Jiao, Kexin; Wang, Cui

Prolonging the campaign life of the blast furnace has been an important task for iron makers, and it has been studied for decades. Adding titanium-bearing materials is a generally agreed and effective technique to protect the blast furnace hearth. Titanium from titania additions in the burden or tuyere injection react with carbon and nitrogen and form scaffolds on the hearth surface to protect the hearth from subsequent erosion. In this article, the progress on blast furnace hearth protection of titania additions in Chinese steel companies and research institutions is investigated, and the difficulties in the operation and production, such as little effect after adding titanium- bearing materials and the property deterioration of liquid iron and slags, are analyzed. The future research for protection in Chinese blast furnace is proposed, and a comprehensive process which combines protection of titanium bearing materials with reasonable thermal balance and slag- making regimes should be established.

Seismic safety in conducting large-scale blasts

NASA Astrophysics Data System (ADS)

Mashukov, I. V.; Chaplygin, V. V.; Domanov, V. P.; Semin, A. A.; Klimkin, M. A.

2017-09-01

In mining enterprises to prepare hard rocks for excavation a drilling and blasting method is used. With the approach of mining operations to settlements the negative effect of large-scale blasts increases. To assess the level of seismic impact of large-scale blasts the scientific staff of Siberian State Industrial University carried out expertise for coal mines and iron ore enterprises. Determination of the magnitude of surface seismic vibrations caused by mass explosions was performed using seismic receivers, an analog-digital converter with recording on a laptop. The registration results of surface seismic vibrations during production of more than 280 large-scale blasts at 17 mining enterprises in 22 settlements are presented. The maximum velocity values of the Earth’s surface vibrations are determined. The safety evaluation of seismic effect was carried out according to the permissible value of vibration velocity. For cases with exceedance of permissible values recommendations were developed to reduce the level of seismic impact.

Structures to Resist the Effects of Accidental Explosions. Volume 2. Blast, Fragment, and Shock Loads

DTIC Science & Technology

1986-12-01

IS. SUPPLEMENTARY NOTfS This report is Volume II of six volumes which will eventually be published as a tri-service design manual and was sponsored by...CLASSIFICAT ION OF THIS PAGE(When Date Entered) TABLE OF CONTENTS PAGE INTRODUCTION 2-I Purpose 1 2-2 Objective 1 2 3 Background 1 2-4 Scope of Manual ...2 2-5 Format of Manual 3 VOLUME CONTENTS 2-6 General EXPLOSION EFFECTS 2-7 Effects of Explosive Output 4 BLAST LOADS 2-8 Blast Phenomena 5 2-8.1

Blasting and Blast Effects in Cold Regions. Part 3. Explosions in Ground Materials

DTIC Science & Technology

1989-05-01

121- York, Ontario: Technical Marketing Services- 123. Explosives, Canadian Industries, 6th edition. Gaffney, E.S. (1984b) Hugoniot of water ice. In...Mines, blasting. U.S. Bureau of Nlines , Report of Insesti- Report of lnsestigations RI 7751. gations 8507. Piekutoiski. A.J. (1974) I.aborator,, scale

30 CFR 816.68 - Use of explosives: Records of blasting operations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... § 816.67(e). (e) Weather conditions, including those which may cause possible adverse blasting effects..., spacing, decks, and delay pattern. (h) Diameter and depth of holes. (i) Types of explosives used. (j... airblast level recorded. (p) Reasons and conditions for each unscheduled blast. [48 FR 9809, Mar. 8, 1983...

30 CFR 816.68 - Use of explosives: Records of blasting operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... § 816.67(e). (e) Weather conditions, including those which may cause possible adverse blasting effects..., spacing, decks, and delay pattern. (h) Diameter and depth of holes. (i) Types of explosives used. (j... airblast level recorded. (p) Reasons and conditions for each unscheduled blast. [48 FR 9809, Mar. 8, 1983...

30 CFR 816.68 - Use of explosives: Records of blasting operations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... § 816.67(e). (e) Weather conditions, including those which may cause possible adverse blasting effects..., spacing, decks, and delay pattern. (h) Diameter and depth of holes. (i) Types of explosives used. (j... airblast level recorded. (p) Reasons and conditions for each unscheduled blast. [48 FR 9809, Mar. 8, 1983...

30 CFR 817.68 - Use of explosives: Records of blasting operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... § 817.67 (e). (e) Weather conditions, including those which may cause possible adverse blasting effects..., spacing, decks, and delay pattern. (h) Diameter and depth of holes. (i) Types of explosives used. (j... airblast level recorded. (p) Reasons and conditions for each unscheduled blast. [48 FR 9811, Mar. 8, 1983] ...

30 CFR 817.68 - Use of explosives: Records of blasting operations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... § 817.67 (e). (e) Weather conditions, including those which may cause possible adverse blasting effects..., spacing, decks, and delay pattern. (h) Diameter and depth of holes. (i) Types of explosives used. (j... airblast level recorded. (p) Reasons and conditions for each unscheduled blast. [48 FR 9811, Mar. 8, 1983] ...

30 CFR 817.68 - Use of explosives: Records of blasting operations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... § 817.67 (e). (e) Weather conditions, including those which may cause possible adverse blasting effects..., spacing, decks, and delay pattern. (h) Diameter and depth of holes. (i) Types of explosives used. (j... airblast level recorded. (p) Reasons and conditions for each unscheduled blast. [48 FR 9811, Mar. 8, 1983] ...

User News. Volume 17, Number 1 -- Spring 1996

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

NONE

This is a newsletter for users of the DOE-2, PowerDOE, SPARK, and BLAST building energy simulation programs. The topics for the Spring 1996 issue include the SPARK simulation environment, DOE-2 validation, listing of free fenestration software from LBNL, Web sites for building energy efficiency, the heat balance method of calculating building heating and cooling loads.

MSTV Mini-Symposium Preview

DTIC Science & Technology

2009-08-12

Man-In- The-Loop Simulation Integration & Demonstrators FTTS JLTV Future Force MRAP Thermal / CFD Crew Safety Structures/Durability Blast Dynamics ...Scott Stilson – General Dynamics Land Systems Chief Engineer, Stryker Modernization (S-Mod) Program The Application of Modeling and Simulation to the S...Military Ground Vehicles Nammalwar Purushothaman, Paramsothy Jayakumar & James Critchley – BAE Systems Sandip Datta & Venkat Pisipati – TAC World Wide

Laboratory impulsivity and depression in blast-exposed military personnel with post-concussion syndrome.

PubMed

Bjork, James M; Burroughs, Thomas K; Franke, Laura M; Pickett, Treven C; Johns, Sade E; Moeller, F Gerard; Walker, William C

2016-12-30

In military populations, traumatic brain injury (TBI) also holds potential to increase impulsivity and impair mood regulation due to blast injury effects on ventral frontal cortex - to put military personnel at risk for suicide or substance abuse. We assessed a linkage between depression and impaired behavioral inhibition in 117 blast-exposed service members (SM) and veterans with post-concussion syndrome (PCS), where PCS was defined using a Rivermead Postconcussive Symptom Questionnaire (RPQ) modified to clarify whether each symptom worsened compared to pre-blast. Center for Epidemiological Studies-Depression Scale (CES-D) scores, PTSD Checklist 5 (PCL-5) scores, and RPQ raw subscale scores correlated positively with commission and perseverative errors on the continuous performance test II (CPT-II). In contrast, the number of RPQ symptoms ostensibly worsened post-blast did not correlate with impulsive errors on the CPT-II. These data replicate earlier findings that link increased affective symptomatology to impaired behavior inhibition in military TBI populations, but where additional effects on impulsivity from the blast itself remain equivocal. Published by Elsevier Ireland Ltd.

Primary blast injuries.

PubMed

Phillips, Y Y

1986-12-01

Injury from explosion may be due to the direct cussive effect of the blast wave (primary), being struck by material propelled by the blast (secondary), to whole-body displacement and impact (tertiary), or to miscellaneous effects from burns, toxic acids, and so on. Severe primary blast injury is most likely to be seen in military operations but can occur in civilian industrial accidents or terrorist actions. Damage is seen almost exclusively in air-containing organs--the lungs, the gastrointestinal tract, and the auditory system. Pulmonary injury is characterized by pneumothorax, parenchymal hemorrhage, and alveolar rupture. The last is responsible for the arterial air embolism that is the principle cause of early mortality. Treatment for blast injury is similar to that for blunt trauma. The sequalae of air embolization to the cerebral or coronary circulation may be altered by immediate hyperbaric therapy. Use of positive pressure ventilatory systems should be closely monitored as they may increase the risk of air embolism in pneumothorax. Morbidity and mortality may be increased by strenuous exertion after injury and by the wearing of a cloth ballistic vest at the time of the blast.

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

James Schondel; Henry S. Chu

Lightweight panels have been designed to protect buildings and vehicles from blast pressures by activating energy dissipation mechanisms under the influence of blast loading. Panels were fabricated which featured a variety of granular materials and hydraulic dissipative deformation mechanisms and the test articles were subjected to full-scale blast loading. The force time-histories transmitted by each technology were measured by a novel method that utilized inexpensive custom-designed force sensors. The array of tests revealed that granular materials can effectively dissipate blast energy if they are employed in a way that they easily crush and rearrange. Similarly, hydraulic dissipation can effectively dissipatemore » energy if the panel features a high fraction of porosity and the panel encasement features low compressive stiffness.« less

A Conformal, Fully-Conservative Approach for Predicting Blast Effects on Ground Vehicles

DTIC Science & Technology

2014-02-09

hydrocode. Again, a very detailed model of the pick-up truck was used. The results demonstrated that the soil type and moisture content affect both...dynamics code with the capability to model soil and blast using a multi- species formulation with advanced equations of state. The two-way coupling...of the blast, the effects of soil , which could have a high water content, must also be included. An attractive strategy, which is much less costly

Ubiquitin Carboxy-Terminal Hydrolase-L1 as a Serum Neurotrauma Biomarker for Exposure to Occupational Low-Level Blast

PubMed Central

Carr, Walter; Yarnell, Angela M.; Ong, Ricardo; Walilko, Timothy; Kamimori, Gary H.; da Silva, Uade; McCarron, Richard M.; LoPresti, Matthew L.

2015-01-01

Repeated exposure to low-level blast is a characteristic of a few select occupations and there is concern that such occupational exposures present risk for traumatic brain injury. These occupations include specialized military and law enforcement units that employ controlled detonation of explosive charges for the purpose of tactical entry into secured structures. The concern for negative effects from blast exposure is based on rates of operator self-reported headache, sleep disturbance, working memory impairment, and other concussion-like symptoms. A challenge in research on this topic has been the need for improved assessment tools to empirically evaluate the risk associated with repeated exposure to blast overpressure levels commonly considered to be too low in magnitude to cause acute injury. Evaluation of serum-based neurotrauma biomarkers provides an objective measure that is logistically feasible for use in field training environments. Among candidate biomarkers, ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1) has some empirical support and was evaluated in this study. We used daily blood draws to examine acute change in UCH-L1 among 108 healthy military personnel who were exposed to repeated low-level blast across a 2-week period. These research volunteers also wore pressure sensors to record blast exposures, wrist actigraphs to monitor sleep patterns, and completed daily behavioral assessments of symptomology, postural stability, and neurocognitive function. UCH-L1 levels were elevated as a function of participating in the 2-week training with explosives, but the correlation of UCH-L1 elevation and blast magnitude was weak and inconsistent. Also, UCH-L1 elevations did not correlate with deficits in behavioral measures. These results provide some support for including UCH-L1 as a measure of central nervous system effects from exposure to low-level blast. However, the weak relation observed suggests that additional indicators of blast effect are needed. PMID:25852633

Eigenvalue Detonation of Combined Effects Aluminized Explosives

NASA Astrophysics Data System (ADS)

Capellos, Christos; Baker, Ernest; Balas, Wendy; Nicolich, Steven; Stiel, Leonard

2007-06-01

This paper reports on the development of theory and performance for recently developed combined effects aluminized explosives. Traditional high energy explosives used for metal pushing incorporate high loading percentages of HMX or RDX, whereas blast explosives incorporate some percentage of aluminum. However, the high blast explosives produce increased blast energies, with reduced metal pushing capability due to late time aluminum reaction. Metal pushing capability refers to the early volume expansion work produced during the first few volume expansions associated with cylinder wall velocities and Gurney energies. Our Recently developed combined effects aluminized explosives (PAX-29C, PAX-30, PAX-42) are capable of achieving excellent metal pushing and high blast energies. Traditional Chapman-Jouguet detonation theory does not explain the observed detonation states achieved by these combined effects explosives. This work demonstrates, with the use of cylinder expansion data and thermochemical code calculations (JAGUAR and CHEETAH), that eigenvalue detonation theory explains the observed behavior.

Dietary Zinc Modulates Matrix Metalloproteinases in Traumatic Brain Injury.

PubMed

Scrimgeour, Angus; Carrigan, Christopher; Condlin, Michelle Lynn; Urso, Maria L; van den Berg, Roland M; van Helden, Herman P M; Montain, Scott J; Joosen, Marloes J A

2018-05-18

Animal models of mild traumatic brain injury (mTBI) provide opportunity to examine the extent to which dietary interventions can be used to improve recovery after injury. Animal studies also suggest that matrix metalloproteinases (MMPs) play a role in tissue remodeling post-TBI. Because dietary zinc (Zn) improved recovery in non-blast mTBI models, and the MMPs are Zn-requiring enzymes, we evaluated the effects of low- and adequate Zn diets on MMP expression and behavioral responses, following exposure to a single blast. MMP mRNA expression in soleus muscle and frontal cortex tissues were quantified at 48h and 14d post-blast. In muscle, blast resulted in significant upregulation of MT-MMP, MMP-2, TIMP-1 and TIMP-2 at 48h post-injury in rats consuming adequate Zn diets (AdZn). At 14d post-blast, there were no blast- or dietary-effects observed on MMP levels in muscle, supporting the existence of a Zn-responsive, functional repair and remodeling mechanism. In contrast, blast resulted in a significant down-regulation of MT-MMP, TIMP-1 and TIMP-2, and a significant up-regulation of MMP-3 levels at 48h post-injury in cortex tissue; while at 14d post-blast, MT-MMP, MMP-2 and TIMP-2 were all down-regulated in response to blast, independent of diet, and TIMP-1 were significantly increased in rats fed AdZn diets despite the absence of elevated MMPs. Because the blast injuries occurred while animals were under general anesthesia, the increased immobility observed post-injury in rats consuming LoZn diets, suggest that blast mTBI can, in the absence of any psychological stressor, induce PTSD-related traits that are chronic, but responsive to diet. Taken together, our results support a relationship between marginally Zn-deficient status and a compromised regenerative response post-injury in muscle, likely through the MMP pathway. However, in neuronal tissue changes in MMP/TIMP levels following blast indicate a variable response to marginally Zn-deficient diets that may help explain compromised repair mechanism(s) previously associated with the systemic hypozincemia that develops in patients with TBI.

Dynamic Response and Optimal Design of Curved Metallic Sandwich Panels under Blast Loading

PubMed Central

Yang, Shu; Han, Shou-Hong; Lu, Zhen-Hua

2014-01-01

It is important to understand the effect of curvature on the blast response of curved structures so as to seek the optimal configurations of such structures with improved blast resistance. In this study, the dynamic response and protective performance of a type of curved metallic sandwich panel subjected to air blast loading were examined using LS-DYNA. The numerical methods were validated using experimental data in the literature. The curved panel consisted of an aluminum alloy outer face and a rolled homogeneous armour (RHA) steel inner face in addition to a closed-cell aluminum foam core. The results showed that the configuration of a “soft” outer face and a “hard” inner face worked well for the curved sandwich panel against air blast loading in terms of maximum deflection (MaxD) and energy absorption. The panel curvature was found to have a monotonic effect on the specific energy absorption (SEA) and a nonmonotonic effect on the MaxD of the panel. Based on artificial neural network (ANN) metamodels, multiobjective optimization designs of the panel were carried out. The optimization results revealed the trade-off relationships between the blast-resistant and the lightweight objectives and showed the great use of Pareto front in such design circumstances. PMID:25126606

Dynamic response and optimal design of curved metallic sandwich panels under blast loading.

PubMed

Qi, Chang; Yang, Shu; Yang, Li-Jun; Han, Shou-Hong; Lu, Zhen-Hua

2014-01-01

It is important to understand the effect of curvature on the blast response of curved structures so as to seek the optimal configurations of such structures with improved blast resistance. In this study, the dynamic response and protective performance of a type of curved metallic sandwich panel subjected to air blast loading were examined using LS-DYNA. The numerical methods were validated using experimental data in the literature. The curved panel consisted of an aluminum alloy outer face and a rolled homogeneous armour (RHA) steel inner face in addition to a closed-cell aluminum foam core. The results showed that the configuration of a "soft" outer face and a "hard" inner face worked well for the curved sandwich panel against air blast loading in terms of maximum deflection (MaxD) and energy absorption. The panel curvature was found to have a monotonic effect on the specific energy absorption (SEA) and a nonmonotonic effect on the MaxD of the panel. Based on artificial neural network (ANN) metamodels, multiobjective optimization designs of the panel were carried out. The optimization results revealed the trade-off relationships between the blast-resistant and the lightweight objectives and showed the great use of Pareto front in such design circumstances.

Mechanism Research on Melting Loss of Coppery Tuyere Small Sleeve in Blast Furnace

NASA Astrophysics Data System (ADS)

Chai, Yi-Fan; Zhang, Jian-Liang; Ning, Xiao-Jun; Wei, Guang-Yun; Chen, Yu-Ting

2016-01-01

The tuyere small sleeve in blast furnace works under poor conditions. The abnormal damage of it will severely affect the performance of the blast furnace, thus it should be replaced during the damping down period. So it is of great significance that we study and reduce the burnout of tuyere small sleeve. Melting loss is one case of its burnout. This paper studied the reasons of tuyere small sleeve's melting loss, through computational simulation and microscopic analysis of the melting section. The research shows that the temperature of coppery tuyere small sleeve is well distributed when there is no limescale in the lumen, and the temperature increases with the thickness of limescale. In addition, the interruption of circulating water does great harm to the tuyere small sleeve. The melting loss of tuyere small sleeve is caused by iron-slag erosion, with the occurrence of the melt metallurgical bonding and diffusion metallurgical combination.

Improved mine blast algorithm for optimal cost design of water distribution systems

NASA Astrophysics Data System (ADS)

Sadollah, Ali; Guen Yoo, Do; Kim, Joong Hoon

2015-12-01

The design of water distribution systems is a large class of combinatorial, nonlinear optimization problems with complex constraints such as conservation of mass and energy equations. Since feasible solutions are often extremely complex, traditional optimization techniques are insufficient. Recently, metaheuristic algorithms have been applied to this class of problems because they are highly efficient. In this article, a recently developed optimizer called the mine blast algorithm (MBA) is considered. The MBA is improved and coupled with the hydraulic simulator EPANET to find the optimal cost design for water distribution systems. The performance of the improved mine blast algorithm (IMBA) is demonstrated using the well-known Hanoi, New York tunnels and Balerma benchmark networks. Optimization results obtained using IMBA are compared to those using MBA and other optimizers in terms of their minimum construction costs and convergence rates. For the complex Balerma network, IMBA offers the cheapest network design compared to other optimization algorithms.

A Differential Scanning Calorimetry Method for Construction of Continuous Cooling Transformation Diagram of Blast Furnace Slag

NASA Astrophysics Data System (ADS)

Gan, Lei; Zhang, Chunxia; Shangguan, Fangqin; Li, Xiuping

2012-06-01

The continuous cooling crystallization of a blast furnace slag was studied by the application of the differential scanning calorimetry (DSC) method. A kinetic model describing the correlation between the evolution of the degree of crystallization with time was obtained. Bulk cooling experiments of the molten slag coupled with numerical simulation of heat transfer were conducted to validate the results of the DSC methods. The degrees of crystallization of the samples from the bulk cooling experiments were estimated by means of the X-ray diffraction (XRD) and the DSC method. It was found that the results from the DSC cooling and bulk cooling experiments are in good agreement. The continuous cooling transformation (CCT) diagram of the blast furnace slag was constructed according to crystallization kinetic model and experimental data. The obtained CCT diagram characterizes with two crystallization noses at different temperature ranges.

Mathematical modeling of the burden distribution in the blast furnace shaft

NASA Astrophysics Data System (ADS)

Park, Jong-In; Jung, Hun-Je; Jo, Min-Kyu; Oh, Han-Sang; Han, Jeong-Whan

2011-06-01

Process efficiency in the blast furnace is influenced by the gas flow pattern, which is dictated by the burden profile. Therefore, it is important to control the burden distribution so as to achieve reasonable gas flow in the blast furnace operation. Additionally, the charging pattern selection is important as it affects the burden trajectory and stock profile. For analysis of the burden distribution, a new analysis model was developed by use of the spreadsheet program, Microsoft® Office Excel, based on visual basic. This model is composed of the falling burden trajectory and a stock model. The burden trajectory is determined by the burden type, batch weight, rotating velocity of the chute, tilting angle, and friction coefficient. After falling, stock lines are formed by the angle of repose, which is affected by the burden trajectory and the falling velocity. The mathematical formulas for developing this model were modified by a scaled model experiment and DEM simulation.

Waveform inversion of acoustic waves for explosion yield estimation

DOE PAGES

Kim, K.; Rodgers, A. J.

2016-07-08

We present a new waveform inversion technique to estimate the energy of near-surface explosions using atmospheric acoustic waves. Conventional methods often employ air blast models based on a homogeneous atmosphere, where the acoustic wave propagation effects (e.g., refraction and diffraction) are not taken into account, and therefore, their accuracy decreases with increasing source-receiver distance. In this study, three-dimensional acoustic simulations are performed with a finite difference method in realistic atmospheres and topography, and the modeled acoustic Green's functions are incorporated into the waveform inversion for the acoustic source time functions. The strength of the acoustic source is related to explosionmore » yield based on a standard air blast model. The technique was applied to local explosions (<10 km) and provided reasonable yield estimates (<~30% error) in the presence of realistic topography and atmospheric structure. In conclusion, the presented method can be extended to explosions recorded at far distance provided proper meteorological specifications.« less

Waveform inversion of acoustic waves for explosion yield estimation

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

Kim, K.; Rodgers, A. J.

We present a new waveform inversion technique to estimate the energy of near-surface explosions using atmospheric acoustic waves. Conventional methods often employ air blast models based on a homogeneous atmosphere, where the acoustic wave propagation effects (e.g., refraction and diffraction) are not taken into account, and therefore, their accuracy decreases with increasing source-receiver distance. In this study, three-dimensional acoustic simulations are performed with a finite difference method in realistic atmospheres and topography, and the modeled acoustic Green's functions are incorporated into the waveform inversion for the acoustic source time functions. The strength of the acoustic source is related to explosionmore » yield based on a standard air blast model. The technique was applied to local explosions (<10 km) and provided reasonable yield estimates (<~30% error) in the presence of realistic topography and atmospheric structure. In conclusion, the presented method can be extended to explosions recorded at far distance provided proper meteorological specifications.« less

A new formulation for air-blast fluid-structure interaction using an immersed approach. Part I: basic methodology and FEM-based simulations

NASA Astrophysics Data System (ADS)

Bazilevs, Y.; Kamran, K.; Moutsanidis, G.; Benson, D. J.; Oñate, E.

2017-07-01

In this two-part paper we begin the development of a new class of methods for modeling fluid-structure interaction (FSI) phenomena for air blast. We aim to develop accurate, robust, and practical computational methodology, which is capable of modeling the dynamics of air blast coupled with the structure response, where the latter involves large, inelastic deformations and disintegration into fragments. An immersed approach is adopted, which leads to an a-priori monolithic FSI formulation with intrinsic contact detection between solid objects, and without formal restrictions on the solid motions. In Part I of this paper, the core air-blast FSI methodology suitable for a variety of discretizations is presented and tested using standard finite elements. Part II of this paper focuses on a particular instantiation of the proposed framework, which couples isogeometric analysis (IGA) based on non-uniform rational B-splines and a reproducing-kernel particle method (RKPM), which is a Meshfree technique. The combination of IGA and RKPM is felt to be particularly attractive for the problem class of interest due to the higher-order accuracy and smoothness of both discretizations, and relative simplicity of RKPM in handling fragmentation scenarios. A collection of mostly 2D numerical examples is presented in each of the parts to illustrate the good performance of the proposed air-blast FSI framework.

Traumatic brain injury produced by exposure to blasts, a critical problem in current wars: biomarkers, clinical studies, and animal models

NASA Astrophysics Data System (ADS)

Dixon, C. Edward

2011-06-01

Traumatic brain injury (TBI) resulting from exposure to blast energy released by Improvised Explosive Devices (IEDs) has been recognized as the "signature injury" of Operation Iraqi Freedom and Operation Enduring Freedom. Repeated exposure to mild blasts may produce subtle deficits that are difficult to detect and quantify. Several techniques have been used to detect subtle brain dysfunction including neuropsychological assessments, computerized function testing and neuroimaging. Another approach is based on measurement of biologic substances (e.g. proteins) that are released into the body after a TBI. Recent studies measuring biomarkers in CSF and serum from patients with severe TBI have demonstrated the diagnostic, prognostic, and monitoring potential. Advancement of the field will require 1) biochemical mining for new biomarker candidates, 2) clinical validation of utility, 3) technical advances for more sensitive, portable detectors, 4) novel statistical approach to evaluate multiple biomarkers, and 5) commercialization. Animal models have been developed to simulate elements of blast-relevant TBI including gas-driven shock tubes to generate pressure waves similar to those produced by explosives. These models can reproduce hallmark clinical neuropathological responses such as neuronal degeneration and inflammation, as well as behavioral impairments. An important application of these models is to screen novel therapies and conduct proteomic, genomic, and lipodomic studies to mine for new biomarker candidates specific to blast relevant TBI.

Blast Testing Issues and TBI: Experimental Models That Lead to Wrong Conclusions.

PubMed

Needham, Charles E; Ritzel, David; Rule, Gregory T; Wiri, Suthee; Young, Leanne

2015-01-01

Over the past several years, we have noticed an increase in the number of blast injury studies published in peer-reviewed biomedical journals that have utilized improperly conceived experiments. Data from these studies will lead to false conclusions and more confusion than advancement in the understanding of blast injury, particularly blast neurotrauma. Computational methods to properly characterize the blast environment have been available for decades. These methods, combined with a basic understanding of blast wave phenomena, enable researchers to extract useful information from well-documented experiments. This basic understanding must include the differences and interrelationships of static pressure, dynamic pressure, reflected pressure, and total or stagnation pressure in transient shockwave flows, how they relate to loading of objects, and how they are properly measured. However, it is critical that the research community effectively overcomes the confusion that has been compounded by a misunderstanding of the differences between the loading produced by a free field explosive blast and loading produced by a conventional shock tube. The principles of blast scaling have been well established for decades and when properly applied will do much to repair these problems. This paper provides guidance regarding proper experimental methods and offers insights into the implications of improperly designed and executed tests. Through application of computational methods, useful data can be extracted from well-documented historical tests, and future work can be conducted in a way to maximize the effectiveness and use of valuable biological test data.

Rodent model of direct cranial blast injury.

PubMed

Kuehn, Reed; Simard, Philippe F; Driscoll, Ian; Keledjian, Kaspar; Ivanova, Svetlana; Tosun, Cigdem; Williams, Alicia; Bochicchio, Grant; Gerzanich, Volodymyr; Simard, J Marc

2011-10-01

Traumatic brain injury resulting from an explosive blast is one of the most serious wounds suffered by warfighters, yet the effects of explosive blast overpressure directly impacting the head are poorly understood. We developed a rodent model of direct cranial blast injury (dcBI), in which a blast overpressure could be delivered exclusively to the head, precluding indirect brain injury via thoracic transmission of the blast wave. We constructed and validated a Cranium Only Blast Injury Apparatus (COBIA) to deliver blast overpressures generated by detonating .22 caliber cartridges of smokeless powder. Blast waveforms generated by COBIA replicated those recorded within armored vehicles penetrated by munitions. Lethal dcBI (LD(50) ∼ 515 kPa) was associated with: (1) apparent brainstem failure, characterized by immediate opisthotonus and apnea leading to cardiac arrest that could not be overcome by cardiopulmonary resuscitation; (2) widespread subarachnoid hemorrhages without cortical contusions or intracerebral or intraventricular hemorrhages; and (3) no pulmonary abnormalities. Sub-lethal dcBI was associated with: (1) apnea lasting up to 15 sec, with transient abnormalities in oxygen saturation; (2) very few delayed deaths; (3) subarachnoid hemorrhages, especially in the path of the blast wave; (4) abnormal immunolabeling for IgG, cleaved caspase-3, and β-amyloid precursor protein (β-APP), and staining for Fluoro-Jade C, all in deep brain regions away from the subarachnoid hemorrhages, but in the path of the blast wave; and (5) abnormalities on the accelerating Rotarod that persisted for the 1 week period of observation. We conclude that exposure of the head alone to severe explosive blast predisposes to significant neurological dysfunction.

Computational Model of the Eye for Primary and Secondary Blast Trauma

DTIC Science & Technology

2015-10-01

inflicted closed eye injuries with features similar to those seen in patients with ocular blast trauma. Alphonse et al. [16] studied the effect of low...Kemper, V. Alphonse , C. McNally, I. Herring, P. Brown, J. Stitzel, and S. Duma. Response of Porcine Eyes to Blast Overpressure: Effects of Overpressure...that induces closed globe anterior and posterior pole damage. Experimental eye research, 99:63–70, 2012. [16] V. D. Alphonse , A. R. Kemper, B. T. Strom

In Silico Investigation of Intracranial Blast Mitigation with Relevance to Military Traumatic Brain Injury

DTIC Science & Technology

2010-09-01

how personal protective equipment affects the brain’s response to blasts. In this study we investigated the effect of the Advanced Combat...analyzing stress wave propagation, which is the main dynamic effect loading the brain tissue during a blast event. We consider two key metrics of stress ...Cauchy stress tensor, and sij ¼ σij − 13σkkδij are the compo- nents of the deviatoric stress tensor (24). Fig. 1 shows snapshots of the pressure

Note: A table-top blast driven shock tube

NASA Astrophysics Data System (ADS)

Courtney, Michael W.; Courtney, Amy C.

2010-12-01

The prevalence of blast-induced traumatic brain injury in conflicts in Iraq and Afghanistan has motivated laboratory scale experiments on biomedical effects of blast waves and studies of blast wave transmission properties of various materials in hopes of improving armor design to mitigate these injuries. This paper describes the design and performance of a table-top shock tube that is more convenient and widely accessible than traditional compression driven and blast driven shock tubes. The design is simple: it is an explosive driven shock tube employing a rifle primer that explodes when impacted by the firing pin. The firearm barrel acts as the shock tube, and the shock wave emerges from the muzzle. The small size of this shock tube can facilitate localized application of a blast wave to a subject, tissue, or material under test.

Note: A table-top blast driven shock tube.

PubMed

Courtney, Michael W; Courtney, Amy C

2010-12-01

The prevalence of blast-induced traumatic brain injury in conflicts in Iraq and Afghanistan has motivated laboratory scale experiments on biomedical effects of blast waves and studies of blast wave transmission properties of various materials in hopes of improving armor design to mitigate these injuries. This paper describes the design and performance of a table-top shock tube that is more convenient and widely accessible than traditional compression driven and blast driven shock tubes. The design is simple: it is an explosive driven shock tube employing a rifle primer that explodes when impacted by the firing pin. The firearm barrel acts as the shock tube, and the shock wave emerges from the muzzle. The small size of this shock tube can facilitate localized application of a blast wave to a subject, tissue, or material under test.

Genetic analysis of rice blast disease resistance genes using USDA rice mini-core and a mapping population

USDA-ARS?s Scientific Manuscript database

Rice blast disease caused by the fungal pathogen Magnaporthe oryzae (M. oryzae) is one of the most destructive diseases of cultivated rice, resulting in significant yield loss each year all over the world. Developing and utilizing blast resistant rice varieties is the most economical and effective m...

Study of blasting seismic effects of underground powerhouse of pumped storage project in granite condition

NASA Astrophysics Data System (ADS)

Wan, Sheng; Li, Hui

2018-03-01

Though the test of blasting vibration, the blasting seismic wave propagation laws in southern granite pumped storage power project are studied. Attenuation coefficient of seismic wave and factors coefficient are acquired by the method of least squares regression analysis according to Sadaovsky empirical formula, and the empirical formula of seismic wave is obtained. This paper mainly discusses on the test of blasting vibration and the procedure of calculation. Our practice might as well serve as a reference for similar projects to come.

Development of a Finite Element Model for Blast Brain Injury and the Effects of CSF Cavitation

DTIC Science & Technology

2012-02-02

FIGURE 1. Brain geometry from photo ( left ; Visible Human Project) and plane-strain model ( right ). Development of a Finite Element Model method in LS-Dyna...between the non-cavitating ( left ) and cavitating ( right ) models for the 500 kPa/4 ms blast condition. FIGURE 6. (a) Comparing the time-history and (b...between the non-cavitating ( left ) and cavitating ( right ) models for the 500 kPa/4 ms blast condition. PANZER et al. Brain Response to Blast Over the wide

Analysis of dynamical response of air blast loaded safety device

NASA Astrophysics Data System (ADS)

Tropkin, S. N.; Tlyasheva, R. R.; Bayazitov, M. I.; Kuzeev, I. R.

2018-03-01

Equipment of many oil and gas processing plants in the Russian Federation is considerably worn-out. This causes the decrease of reliability and durability of equipment and rises the accident rate. An air explosion is the one of the most dangerous cases for plants in oil and gas industry, usually caused by uncontrolled emission and inflammation of oil products. Air explosion can lead to significant danger for life and health of plant staff, so it necessitates safety device usage. A new type of a safety device is designed. Numerical simulation is necessary to analyse design parameters and performance of the safety device, subjected to air blast loading. Coupled fluid-structure interaction analysis is performed to determine strength of the protective device and its performance. The coupled Euler-Lagrange method, allowable in Abaqus by SIMULIA, is selected as the most appropriate analysis tool to study blast wave interaction with the safety device. Absorption factors of blast wave are evaluated for the safety device. This factors allow one to assess efficiency of the safety device, and its main structural component – dampener. Usage of CEL allowed one to model fast and accurately the dampener behaviour, and to develop the parametric model to determine safety device sizes.

Sequence variation at the rice blast resistance gene Pi-km locus: Implications for the development of allele specific markers

USDA-ARS?s Scientific Manuscript database

The recently cloned blast resistance (R) gene Pi-km protects rice crops against specific races of the fungal pathogen Magnaporthe oryzae in a gene-for-gene manner. The use of blast R genes remains the most cost-effective method for an integrated disease management strategy. To facilitate rice breed...

Atmospheric particulate emissions from dry abrasive blasting using coal slag.

PubMed

Kura, Bhaskar; Kambham, Kalpalatha; Sangameswaran, Sivaramakrishnan; Potana, Sandhya

2006-08-01

Coal slag is one of the widely used abrasives in dry abrasive blasting. Atmospheric emissions from this process include particulate matter (PM) and heavy metals, such as chromium, lead, manganese, nickel. Quantities and characteristics of PM emissions depend on abrasive characteristics and process parameters. Emission factors are key inputs to estimate emissions. Experiments were conducted to study the effect of blast pressure, abrasive feed rate, and initial surface contamination on total PM (TPM) emission factors for coal slag. Rusted and painted mild steel surfaces were used as base plates. Blasting was carried out in an enclosed chamber, and PM was collected from an exhaust duct using U.S. Environment Protection Agency source sampling methods for stationary sources. Results showed that there is significant effect of blast pressure, feed rate, and surface contamination on TPM emissions. Mathematical equations were developed to estimate emission factors in terms of mass of emissions per unit mass of abrasive used, as well as mass of emissions per unit of surface area cleaned. These equations will help industries in estimating PM emissions based on blast pressure and abrasive feed rate. In addition, emissions can be reduced by choosing optimum operating conditions.

Analysis of Abrasive Blasting of DOP-26 Iridium Alloy

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

Ohriner, Evan Keith; Zhang, Wei; Ulrich, George B

2012-01-01

The effects of abrasive blasting on the surface geometry and microstructure of DOP-26 iridium alloy (Ir-0.3% W-0.006% Th 0.005% Al) have been investigated. Abrasive blasting has been used to control emissivity of components operating at elevated temperature. The effects of abrasive blasting conditions on surface morphology were investigated both experimentally and by numerical modeling. The simplified model, based on finite element analysis of a single angular particle impacting on Ir alloy disk, calculates the surface deformation and residual strain distribution. The experimental results and modeling results both indicate that the surface geometry is not sensitive to the abrasive blast processmore » conditions of nozzle pressure and standoff distance considered in this study. On the other hand, the modeling results suggest that the angularity of the abrasive particle has an important role in determining surface geometry, which in turn, affects the emissivity. Abrasive blasting causes localized surface strains and localized recrystallization, but it does not affect grain size following extended exposure at elevated temperature. The dependence of emissivity of the DOP-26 alloy on mean surface slope follows a similar trend to that reported for pure iridium.« less

Impact and Blast Resistance of Sandwich Plates

NASA Astrophysics Data System (ADS)

Dvorak, George J.; Bahei-El-Din, Yehia A.; Suvorov, Alexander P.

Response of conventional and modified sandwich plate designs is examined under static load, impact by a rigid cylindrical or flat indenter, and during and after an exponential pressure impulse lasting for 0.05 ms, at peak pressure of 100 MPa, simulating a nearby explosion. The conventional sandwich design consists of thin outer (loaded side) and inner facesheets made of carbon/epoxy fibrous laminates, separated by a thick layer of structural foam core. In the three modified designs, one or two thin ductile interlayers are inserted between the outer facesheet and the foam core. Materials selected for the interlayers are a hyperelas-tic rate-independent polyurethane;a compression strain and strain rate dependent, elastic-plastic polyurea;and an elastomeric foam. ABAQUS and LS-Dyna software were used in various response simulations. Performance comparisons between the enhanced and conventional designs show that the modified designs provide much better protection against different damage modes under both load regimes. After impact, local facesheet deflection, core compression, and energy release rate of delamination cracks, which may extend on hidden interfaces between facesheet and core, are all reduced. Under blast or impulse loads, reductions have been observed in the extent of core crushing, facesheet delaminations and vibration amplitudes, and in overall deflections. Similar reductions were found in the kinetic energy and in the stored and dissipated strain energy. Although strain rates as high as 10-4/s1 are produced by the blast pressure, peak strains in the interlayers were too low to raise the flow stress in the polyurea to that in the polyurethane, where a possible rate-dependent response was neglected. Therefore, stiff polyurethane or hard rubber interlayers materials should be used for protection of sandwich plate foam cores against both impact and blast-induced damage.

Origin of asymmetries in X-ray emission lines from the blast wave of the 2014 outburst of nova V745 Sco

NASA Astrophysics Data System (ADS)

Orlando, Salvatore; Drake, Jeremy J.; Miceli, Marco

2017-02-01

The symbiotic nova V745 Sco was observed in outburst on 2014 February 6. Its observations by the Chandra X-ray Observatory at days 16 and 17 have revealed a spectrum characterized by asymmetric and blueshifted emission lines. Here we investigate the origin of these asymmetries through 3D hydrodynamic simulations describing the outburst during the first 20 d of evolution. The model takes into account thermal conduction and radiative cooling, and assumes that a blast wave propagates through an equatorial density enhancement (EDE). From these simulations, we synthesize the X-ray emission and derive the spectra as they would be observed with Chandra. We find that both the blast wave and the ejecta distribution are efficiently collimated in polar directions due to the presence of the EDE. The majority of the X-ray emission originates from the interaction of the blast with the EDE and is concentrated on the equatorial plane as a ring-like structure. Our `best-fitting' model requires a mass of ejecta in the outburst Mej ≈ 3 × 10-7 M⊙ and an explosion energy Eb ≈ 3 × 1043 erg, and reproduces the distribution of emission measure versus temperature and the evolution of shock velocity and temperature inferred from the observations. The model predicts asymmetric and blueshifted line profiles similar to those observed and explains their origin as due to substantial X-ray absorption of redshifted emission by ejecta material. The comparison of predicted and observed Ne and O spectral line ratios reveals no signs of strong Ne enhancement and suggests that the progenitor is a CO white dwarf.

Is Blast Injury a Modern Phenomenon?: Early Historical Descriptions of Mining and Volcanic Traumatic Brain Injury With Relevance to Modern Terrorist Attacks and Military Warfare.

PubMed

Bowen, Lauren N; Moore, David F; Okun, Michael S

2016-03-01

Given the recent interest in blast injury spurred by returning soldiers from overseas conflicts, we sought to research the early historical descriptions of blast injuries and their treatments. Consideration was given to specific descriptions of survivors of closed head injury and their treatment. A review of the medical and nonmedical literature was undertaken, with particular emphasis on pre-1800 descriptions of volcanic eruptions and mining accidents. Compilations of accounts of the Etna eruptions dating from 126 BC were translated into English, and early mining texts from the 1600s and 1700s were reviewed. Accumulations of flammable gases were recorded in many medieval sources and this knowledge of toxic gas which could lead to blast injury was known in the mining community by 1316. No direct attribution of injuries to blast forces was present in the historical record examined before the 1300s, although mining accounts in the 1600s detail deaths due to blast. No specific descriptions of survivors of a closed head injury were found in the mining and volcanic eruption literature. Descriptions and warnings of blast forces were commonly written about in the medieval and Renaissance mining communities. Personal narratives as early as 1316 recognize the traumatic effects of blast injury. No mining or volcanic blast descriptions before 1800 detailed severe closed head injury survivors, suggesting greater mortality than morbidity from blast injury in the premodern era. This review also uncovered that there was no historical treatment or remedy recommended to survivors of blast injury. Blast explosions resulting in injury or death were frequently described, although in simplistic terminology.

Development of GP and GEP models to estimate an environmental issue induced by blasting operation.

PubMed

Faradonbeh, Roohollah Shirani; Hasanipanah, Mahdi; Amnieh, Hassan Bakhshandeh; Armaghani, Danial Jahed; Monjezi, Masoud

2018-05-21

Air overpressure (AOp) is one of the most adverse effects induced by blasting in the surface mines and civil projects. So, proper evaluation and estimation of the AOp is important for minimizing the environmental problems resulting from blasting. The main aim of this study is to estimate AOp produced by blasting operation in Miduk copper mine, Iran, developing two artificial intelligence models, i.e., genetic programming (GP) and gene expression programming (GEP). Then, the accuracy of the GP and GEP models has been compared to multiple linear regression (MLR) and three empirical models. For this purpose, 92 blasting events were investigated, and subsequently, the AOp values were carefully measured. Moreover, in each operation, the values of maximum charge per delay and distance from blast points, as two effective parameters on the AOp, were measured. After predicting by the predictive models, their performance prediction was checked in terms of variance account for (VAF), coefficient of determination (CoD), and root mean square error (RMSE). Finally, it was found that the GEP with VAF of 94.12%, CoD of 0.941, and RMSE of 0.06 is a more precise model than other predictive models for the AOp prediction in the Miduk copper mine, and it can be introduced as a new powerful tool for estimating the AOp resulting from blasting.

Global efforts in managing rice blast disease

USDA-ARS?s Scientific Manuscript database

Rice blast disease caused by the fungus Magnaporthe oryzae is a major destructive disease threatening global food security. Resistance (R) genes to M. oryzae are effective in preventing infections by strains of M. oryzae carry the corresponding avirulence (AVR) genes. Effectiveness of genetic resist...

Neck blast disease influences grain yield and quality traits of aromatic rice.

PubMed

Khan, Mohammad Ashik Iqbal; Bhuiyan, Md Rejwan; Hossain, Md Shahadat; Sen, Partha Pratim; Ara, Anjuman; Siddique, Md Abubakar; Ali, Md Ansar

2014-11-01

A critical investigation was conducted to find out the effect of neck blast disease on yield-contributing characters, and seed quality traits of aromatic rice in Bangladesh. Both healthy and neck-blast-infected panicles of three aromatic rice cultivars (high-yielding and local) were collected and investigated at Plant Pathology Division, Bangladesh Rice Research Institute (BRRI), Gazipur, Bangladesh. All of the tested varieties were highly susceptible to neck blast disease under natural conditions, though no leaf blast symptoms appear on leaves. Neck blast disease increased grain sterility percentages, reduced grain size, yield and quality traits of seeds. The degrees of yield and seed quality reduction depended on disease severity and variety's genetic make-up. Unfilled grains were the main source of seed-borne pathogen, especially for blast in the seed lot. Transmission of blast pathogen from neck (panicle base) to seed was very poor. These findings are important, especially concerning the seed certification programme in which seed lots are certified on the basis of field inspection. Finally, controlled experiments are needed to draw more critical conclusions. Copyright © 2014 Académie des sciences. Published by Elsevier SAS. All rights reserved.

In vitro and in vivo effects of deferoxamine in neonatal acute leukemia.

PubMed

Estrov, Z; Tawa, A; Wang, X H; Dubé, I D; Sulh, H; Cohen, A; Gelfand, E W; Freedman, M H

1987-03-01

A six week old infant with acute leukemia failed to attain remission with chemotherapy. Because we previously demonstrated that the iron chelator deferoxamine (DFO) has antiproliferative properties and modulatory effects on cell differentiation, a protocol was designed for in vitro study and for clinical use in the patient. At diagnosis, blast cells were morphologically undifferentiated, had nondiagnostic cytochemistry, showed an abnormal karyotype (t[4;11]), expressed markers of B cell lineage, and demonstrated C mu gene rearrangement. Tissue culture of marrow or blood cells yielded colonies of leukemic blasts. Increasing concentrations of DFO produced a dose-dependent suppression of patient's blast colony growth in vitro, and blasts within colonies showed a marked change in surface antigen expression from lymphoid to myelomonocytic markers, became monocytic in appearance, and developed intense staining for nonspecific esterase. When DFO was given intravenously to the patient as a single agent for 48 hours, blasts no longer expressed lymphoid antigens and became strongly positive for myelomonocytic markers, identical to the in vitro findings. Intravenous DFO halted rising peripheral blood blast cell numbers and allowed a several-fold increase in normal hematopoietic progenitor colony growth. When combined with low-dose cytosine arabinoside in the treatment protocol, DFO caused striking leukemic cytoreduction. Our findings indicate that DFO has antileukemic properties by virtue of its effects on proliferation and differentiation, and they prompt further experimental and clinical studies with this agent.

Attenuation of blast pressure behind ballistic protective vests.

PubMed

Wood, Garrett W; Panzer, Matthew B; Shridharani, Jay K; Matthews, Kyle A; Capehart, Bruce P; Myers, Barry S; Bass, Cameron R

2013-02-01

Clinical studies increasingly report brain injury and not pulmonary injury following blast exposures, despite the increased frequency of exposure to explosive devices. The goal of this study was to determine the effect of personal body armour use on the potential for primary blast injury and to determine the risk of brain and pulmonary injury following a blast and its impact on the clinical care of patients with a history of blast exposure. A shock tube was used to generate blast overpressures on soft ballistic protective vests (NIJ Level-2) and hard protective vests (NIJ Level-4) while overpressure was recorded behind the vest. Both types of vest were found to significantly decrease pulmonary injury risk following a blast for a wide range of conditions. At the highest tested blast overpressure, the soft vest decreased the behind armour overpressure by a factor of 14.2, and the hard vest decreased behind armour overpressure by a factor of 56.8. Addition of body armour increased the 50th percentile pulmonary death tolerance of both vests to higher levels than the 50th percentile for brain injury. These results suggest that ballistic protective body armour vests, especially hard body armour plates, provide substantial chest protection in primary blasts and explain the increased frequency of head injuries, without the presence of pulmonary injuries, in protected subjects reporting a history of blast exposure. These results suggest increased clinical suspicion for mild to severe brain injury is warranted in persons wearing body armour exposed to a blast with or without pulmonary injury.

The effects of combat-related mild traumatic brain injury (mTBI): Does blast mTBI history matter?

PubMed

Kontos, Anthony P; Elbin, R J; Kotwal, Russ S; Lutz, Robert H; Kane, Shawn; Benson, Peter J; Forsten, Robert D; Collins, Michael W

2015-10-01

The effects of mild traumatic brain injury (mTBI) have received significant attention since the beginning of the conflicts in Afghanistan and Iraq. Surprisingly, little is known about the temporal nature of neurocognitive impairment, mTBI, and posttraumatic stress (PTS) symptoms following combat-related mTBI. It is also unclear as to the role that blast exposure history has on mTBI and PTS impairments and symptoms. The purposes of this study were to examine prospectively the effects of mTBI on neurocognitive performance as well as mTBI and PTS symptoms among US Army Special Operations Command personnel and to study the influence of history of blast mTBI on these effects. Eighty US Army Special Operations Command personnel with (n = 19) and without (n = 61) a history of blast-related mTBI completed the military version of the Immediate Post-concussion Assessment Cognitive Test (ImPACT), Post Concussion Symptom Scale (PCSS), and the PTSD Checklist (PCL) at baseline as well as 1 day to 7 days and 8 days to 20 days following a combat-related mTBI. Results indicated that verbal memory (p = 0.002) and processing speed (p = 0.003) scores were significantly lower and mTBI symptoms (p = 0.001) were significantly higher at 1 day to 7 days after injury compared with both baseline and 8 days to 20 days after injury. PTS remained stable across the three periods. Participants with a history of blast mTBI demonstrated lower verbal memory at 1 day to 7 days after mTBI compared with participants without a history of blast mTBI (p = 0.02). Decreases in neurocognitive performance and increased mTBI symptoms are evident in the first 1 day to 7 days following combat-related mTBI, and a history of blast-related mTBI may influence these effects. Epidemiologic/prognostic study, level II.

Performance Tests of a Fast-Acting Valve for the Driver Tubes of a Large Blast/Thermal Simulator

DTIC Science & Technology

1992-05-01

ETVE. The lag time of the valve varied from 36 to 120 milliseconds from the time the fire signal was initiated to the time the first movement of the...ETVE Fire 2 ETVE Hall Effect 3 Pressure transducer in expansion tunnel at loft 4 Pressure transducer in expansion tunnel at 18ft 5 Pressure...be noted that the LED’s which were used during Phase I testing to indicate if the ETVE was ready to fire were disconnected by Eaton during Phase II

Retinal ganglion cell damage in an experimental rodent model of blast-mediated traumatic brain injury.

PubMed

Mohan, Kabhilan; Kecova, Helga; Hernandez-Merino, Elena; Kardon, Randy H; Harper, Matthew M

2013-05-15

To evaluate retina and optic nerve damage following experimental blast injury. Healthy adult mice were exposed to an overpressure blast wave using a custom-built blast chamber. The effects of blast exposure on retina and optic nerve function and structure were evaluated using the pattern electroretinogram (pERG), spectral domain optical coherence tomography (OCT), and the chromatic pupil light reflex. Assessment of the pupil response to light demonstrated decreased maximum pupil constriction diameter in blast-injured mice using red light or blue light stimuli 24 hours after injury compared with baseline in the eye exposed to direct blast injury. A decrease in the pupil light reflex was not observed chronically following blast exposure. We observed a biphasic pERG decrease with the acute injury recovering by 24 hours postblast and the chronic injury appearing at 4 months postblast injury. Furthermore, at 3 months following injury, a significant decrease in the retinal nerve fiber layer was observed using OCT compared with controls. Histologic analysis of the retina and optic nerve revealed punctate regions of reduced cellularity in the ganglion cell layer and damage to optic nerves. Additionally, a significant upregulation of proteins associated with oxidative stress was observed acutely following blast exposure compared with control mice. Our study demonstrates that decrements in retinal ganglion cell responses can be detected after blast injury using noninvasive functional and structural tests. These objective responses may serve as surrogate tests for higher CNS functions following traumatic brain injury that are difficult to quantify.

BLAST: Building energy simulation in Hong Kong

NASA Astrophysics Data System (ADS)

Fong, Sai-Keung

1999-11-01

The characteristics of energy use in buildings under local weather conditions were studied and evaluated using the energy simulation program BLAST-3.0. The parameters used in the energy simulation for the study and evaluation include the architectural features, different internal building heat load settings and weather data. In this study, mathematical equations and the associated coefficients useful to the industry were established. A technology for estimating energy use in buildings under local weather conditions was developed by using the results of this study. A weather data file of Typical Meteorological Years (TMY) has been compiled for building energy studies by analyzing and evaluating the weather of Hong Kong from the year 1979 to 1988. The weather data file TMY and the example weather years 1980 and 1988 were used by BLAST-3.0 to evaluate and study the energy use in different buildings. BLAST-3.0 was compared with other building energy simulation and approximation methods: Bin method and Degree Days method. Energy use in rectangular compartments of different volumes varying from 4,000 m3 to 40,000 m3 with different aspect ratios were analyzed. The use of energy in buildings with concrete roofs was compared with those with glass roofs at indoor temperature 21°C, 23°C and 25°C. Correlation relationships among building energy, space volume, monthly mean temperature and solar radiation were derived and investigated. The effects of space volume, monthly mean temperature and solar radiation on building energy were evaluated. The coefficients of the mathematical relationships between space volume and energy use in a building were computed and found satisfactory. The calculated coefficients can be used for quick estimation of energy use in buildings under similar situations. To study energy use in buildings, the cooling load per floor area against room volume was investigated. The case of an air-conditioned single compartment with 5 m ceiling height was evaluated. It was found that the supply of cool air to the lower portion of the compartment provided significant performance of space cooling. The mathematical relationships between different shading patterns and different glass window to wall ratios of single compartments were established to provide a guide for easy approximation of energy use under similar conditions. In addition, the Overall Thermal Transfer Values (OTTV) for the compartments were studied. The monthly and annual energy use of three realistic buildings were investigated. They were a commercial building, an industrial building and a dual-purpose building. The cooling loads per floor area for the buildings were studied and the OTTV were evaluated by two different methods. Sensitivity analysis was carried out to investigate the impact of the parameters of internal heat gains on the energy use of an academic building. It was found that there was major influence of indoor temperature setting on building energy use The performances of using the local weather data file of TMY and example weather years 1980 and 1989 were evaluated. TMY was found to be the most suitable for energy simulation while the weather years 1980 and 1989 yielded good results.

Glyburide-Novel Prophylaxis and Effective Treatment for Traumatic Brain Injury

DTIC Science & Technology

2011-08-01

between apnea and various neurological abnormalities measured at 24 hours and at later times. Indeed, our analysis showed a high degree of correlation...7 and 14 after blast-TBI. Conventional Analysis . After blast-TBI, we observed significant deficits in un- coerced (spontaneous Rearing) and in...intensity-response” relationship between blast intensity and outcome. Detailed analysis of the outcomes at 24 hours in individual animals showed

A Multisite Study of the Relationships between Blast Exposures and Symptom Reporting in a Post-Deployment Active Duty Military Population with Mild Traumatic Brain Injury

PubMed Central

Miller, Kelly J.; Lange, Rael T.; Cooper, Douglas B.; Tate, David F.; Bailie, Jason; Brickell, Tracey A.; French, Louis M.; Asmussen, Sarah; Kennedy, Jan E.

2014-01-01

Abstract Explosive devices have been the most frequent cause of traumatic brain injury (TBI) among deployed contemporary U.S. service members. The purpose of this study was to examine the influence of previous cumulative blast exposures (that did or did not result in TBI) on later post-concussion and post-traumatic symptom reporting after sustaining a mild TBI (MTBI). Participants were 573 service members who sustained MTBI divided into four groups by number of blast exposures (1, 2, 3, and 4–10) and a nonblast control group. Post-concussion symptoms were measured using the Neurobehavioral Symptom Inventory (NSI) and post-traumatic stress disorder (PTSD) symptoms using the Post-traumatic Checklist-Civilian version (PCL-C). Results show groups significantly differed on total NSI scores (p<0.001), where symptom endorsement increased as number of reported blast exposures increased. Total NSI scores were significantly higher for the 3– and 4–10 blast groups compared with the 1- and 2-blast groups with effect sizes ranging from small to moderate (d=0.31 to 0.63). After controlling for PTSD symptoms using the PCL-C total score, NSI total score differences remained between the 4–10-blast group and the 1- and 2-blast groups, but were less pronounced (d=0.35 and d=0.24, respectively). Analyses of NSI subscale scores using PCL-C scores as a covariate revealed significant between-blast group differences on cognitive, sensory, and somatic, but not affective symptoms. Regression analyses revealed that cumulative blast exposures accounted for a small but significant amount of the variance in total NSI scores (4.8%; p=0.009) and total PCL-C scores (2.3%; p<0.001). Among service members exposed to blast, post-concussion symptom reporting increased as a function of cumulative blast exposures. Future research will need to determine the relationship between cumulative blast exposures, symptom reporting, and neuropathological changes. PMID:25036531

Overexpression of the wasabi defensin gene confers enhanced resistance to blast fungus ( Magnaporthe grisea) in transgenic rice.

PubMed

Kanzaki, H.; Nirasawa, S.; Saitoh, H.; Ito, M.; Nishihara, M.; Terauchi, R.; Nakamura, I.

2002-11-01

Transgenic rice ( Oryza sativa cv. Sasanishiki) overexpressing the wasabi defensin gene, a plant defensin effective against the rice blast fungus, was generated by Agrobacterium tumefaciens-mediated transformation. Twenty-two T2 homozygous lines harboring the wasabi defensin gene were challenged by the blast fungus. Transformants exhibited resistance to rice blast at various levels. The inheritance of the resistance over generations was investigated. T3 plants derived from two highly blast-resistant T2 lines (WT14-5 and WT43-5) were challenged with the blast fungus using the press-injured spots method. The average size of disease lesions of the transgenic line WT43-5 was reduced to about half of that of non-transgenic plants. The 5-kDa peptide, corresponding to the processed form of the wasabi defensin, was detected in the total protein fraction extracted from the T3 progeny. Transgenic rice plants overproducing wasabi defensin are expected to possess a durable and wide-spectrum resistance (i.e. field resistance) against various rice blast races.

Matrerials Characterization of Craninal Simulants for Blast Induced Traumatic Brain Injury

DTIC Science & Technology

2017-08-28

34.....,,. Witt.. Cranial Simulants Under Tensile, Compressive, and Shear Stresses Tensile Testing i 2 !’u ~ t . .. · Bovine Skin Derived Gel• tin 0𔄀...1 : • •• ..... 50 100 l,50 ~VM/1) ""’ 2°" tone Gel• tin Stress Comparhon u 14 l2 7 10 6. •• I .. , ... " .... -2 0 so 100 uo r

DRoplet and hAdron generator for nuclear collisions: An update

NASA Astrophysics Data System (ADS)

Tomášik, Boris

2016-10-01

The Monte Carlo generator DRAGON simulates hadron production in ultrarelativistic nuclear collisions. The underlying theoretical description is provided by the blast-wave model. DRAGON includes second-order angular anisotropy in transverse shape and the amplitude of the transverse expansion velocity. It also allows to simulate hadron production from a fragmented fireball, e.g. as resulting from spinodal decomposition happening at the first-order phase transition.

Fiber release from impacted graphite reinforced epoxy composites

NASA Technical Reports Server (NTRS)

Babinsky, T. C.

1980-01-01

Carbon fibers released from composites by aircraft fires and crashes can cause electrical shorts and consequent equipment damage. This report investigates less vigorous release mechanisms than that previously simulated by explosive burn/blast tests. When AS/3501-6 composites are impacted by various head and weight configurations of a pendulum impactor, less than 0.2 percent by weight of the original sample is released as single fibers. Other fiber release mechanisms studied were air blasts, constant airflow, torsion, flexural, and vibration of composite samples. The full significance of the low single fiber release rates found here is to be evaluated by NASA in their aircraft vulnerability studies.

[Confined blasting in microexplosion cystolithotripsy].

PubMed

Uchida, M

1989-03-01

This paper is the 12th report in a series of studies on the application of microexplosion to medicine and biology. Microexplosion lithotripsy is a newly developed technique in our clinic to crush urinary stones with small quantities of explosives. A systematic research project has been performed since the first report of microexplosion lithotripsy in 1977. As a result, microexplosion was successfully applied to the destruction of bladder stones in 130 cases from 1981 to 1988. In blasting to crush rocks in industrial works, two kinds of blasting are available: external charge blasting and confined blasting. The detonation power of the latter is 10 to 50 times larger than that of the former. A detruction test using several kinds of spherical form model calculus and lead azide explosive was performed. The formula to calculate the suitable explosive dose was determined experimentally as shown below. (formula; see text) Thus the theory in general industrial blasting with massive explosives was proved to be effective also in microexplosion with small explosives. An original electric drill system was developed to make a hole in stones for confined blasting. 60 cases, including 2 cases of giant bladder stones over 100 g in weight, were successfully treated by confined blasting using this system without any complication. We consider that any bladder stones, however big or however many, can be treated by microexplosion lithotripsy with confined blasting.

Model for small arms fire muzzle blast wave propagation in air

NASA Astrophysics Data System (ADS)

Aguilar, Juan R.; Desai, Sachi V.

2011-11-01

Accurate modeling of small firearms muzzle blast wave propagation in the far field is critical to predict sound pressure levels, impulse durations and rise times, as functions of propagation distance. Such a task being relevant to a number of military applications including the determination of human response to blast noise, gunfire detection and localization, and gun suppressor design. Herein, a time domain model to predict small arms fire muzzle blast wave propagation is introduced. The model implements a Friedlander wave with finite rise time which diverges spherically from the gun muzzle. Additionally, the effects in blast wave form of thermoviscous and molecular relaxational processes, which are associated with atmospheric absorption of sound were also incorporated in the model. Atmospheric absorption of blast waves is implemented using a time domain recursive formula obtained from numerical integration of corresponding differential equations using a Crank-Nicholson finite difference scheme. Theoretical predictions from our model were compared to previously recorded real world data of muzzle blast wave signatures obtained by shooting a set different sniper weapons of varying calibers. Recordings containing gunfire acoustical signatures were taken at distances between 100 and 600 meters from the gun muzzle. Results shows that predicted blast wave slope and exponential decay agrees well with measured data. Analysis also reveals the persistency of an oscillatory phenomenon after blast overpressure in the recorded wave forms.

14 CFR 417.229 - Far-field overpressure blast effects analysis.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Far-field overpressure blast effects analysis. 417.229 Section 417.229 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION... explosions resulting from debris impacts, including the potential for mixing of liquid propellants; (4...

14 CFR 417.229 - Far-field overpressure blast effects analysis.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Far-field overpressure blast effects analysis. 417.229 Section 417.229 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION... explosions resulting from debris impacts, including the potential for mixing of liquid propellants; (4...

14 CFR 417.229 - Far-field overpressure blast effects analysis.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Far-field overpressure blast effects analysis. 417.229 Section 417.229 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION... explosions resulting from debris impacts, including the potential for mixing of liquid propellants; (4...

14 CFR 417.229 - Far-field overpressure blast effects analysis.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Far-field overpressure blast effects analysis. 417.229 Section 417.229 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION... explosions resulting from debris impacts, including the potential for mixing of liquid propellants; (4...

Fatigue behavior of Ti6Al4V and 316 LVM blasted with ceramic particles of interest for medical devices.

PubMed

Barriuso, S; Chao, J; Jiménez, J A; García, S; González-Carrasco, J L

2014-02-01

Grit blasting is used as a cost-effective method to increase the surface roughness of metallic biomaterials, as Ti6Al4V and 316 LVM, to enhance the osteointegration, fixation and stability of implants. Samples of these two alloys were blasted by using alumina and zirconia particles, yielding rough (up to Ra~8μm) and nearly smooth (up to Ra~1μm) surfaces, respectively. In this work, we investigate the sub-surface induced microstructural effects and its correlation with the mechanical properties, with special emphasis in the fatigue behavior. Blasting with zirconia particles increases the fatigue resistance whereas the opposite effect is observed using alumina ones. As in a conventional shot penning process, the use of rounded zirconia particles for blasting led to the development of residual compressive stresses at the surface layer, without zones of stress concentrators. Alumina particles are harder and have an angular shape, which confers a higher capability to abrade the surface, but also a high rate of breaking down on impact. The higher roughness and the presence of a high amount of embedded alumina particles make the blasted alloy prone to crack nucleation. Interestingly, the beneficial or detrimental role of blasting is more intense for the Ti6Al4V alloy than for the 316 steel. It is proposed that this behavior is related to their different strain hardening exponents and the higher mass fraction of particles contaminating the surface. The low value of this exponent for the Ti6Al4V alloy justifies the expected low sub-surface hardening during the severe plastic deformation, enhancing its capability to soft during cyclic loading. © 2013 Published by Elsevier Ltd.

Economic and Environmental Impact of Rice Blast Pathogen (Magnaporthe oryzae) Alleviation in the United States.

PubMed

Nalley, Lawton; Tsiboe, Francis; Durand-Morat, Alvaro; Shew, Aaron; Thoma, Greg

2016-01-01

Rice blast (Magnaporthe oryzae) is a key concern in combating global food insecurity given the disease is responsible for approximately 30% of rice production losses globally-the equivalent of feeding 60 million people. These losses increase the global rice price and reduce consumer welfare and food security. Rice is the staple crop for more than half the world's population so any reduction in rice blast would have substantial beneficial effects on consumer livelihoods. In 2012, researchers in the US began analyzing the feasibility of creating blast-resistant rice through cisgenic breeding. Correspondingly, our study evaluates the changes in producer, consumer, and environmental welfare, if all the rice produced in the Mid-South of the US were blast resistant through a process like cisgenics, using both international trade and environmental assessment modeling. Our results show that US rice producers would gain 69.34 million dollars annually and increase the rice supply to feed an additional one million consumers globally by eliminating blast from production in the Mid-South. These results suggest that blast alleviation could be even more significant in increasing global food security given that the US is a small rice producer by global standards and likely experiences lower losses from blast than other rice-producing countries because of its ongoing investment in production technology and management. Furthermore, results from our detailed life cycle assessment (LCA) show that producing blast-resistant rice has lower environmental (fossil fuel depletion, ecotoxicity, carcinogenics, eutrophication, acidification, global warming potential, and ozone depletion) impacts per unit of rice than non-blast resistant rice production. Our findings suggest that any reduction in blast via breeding will have significantly positive impacts on reducing global food insecurity through increased supply, as well as decreased price and environmental impacts in production.

Economic and Environmental Impact of Rice Blast Pathogen (Magnaporthe oryzae) Alleviation in the United States

PubMed Central

2016-01-01

Rice blast (Magnaporthe oryzae) is a key concern in combating global food insecurity given the disease is responsible for approximately 30% of rice production losses globally—the equivalent of feeding 60 million people. These losses increase the global rice price and reduce consumer welfare and food security. Rice is the staple crop for more than half the world’s population so any reduction in rice blast would have substantial beneficial effects on consumer livelihoods. In 2012, researchers in the US began analyzing the feasibility of creating blast-resistant rice through cisgenic breeding. Correspondingly, our study evaluates the changes in producer, consumer, and environmental welfare, if all the rice produced in the Mid-South of the US were blast resistant through a process like cisgenics, using both international trade and environmental assessment modeling. Our results show that US rice producers would gain 69.34 million dollars annually and increase the rice supply to feed an additional one million consumers globally by eliminating blast from production in the Mid-South. These results suggest that blast alleviation could be even more significant in increasing global food security given that the US is a small rice producer by global standards and likely experiences lower losses from blast than other rice-producing countries because of its ongoing investment in production technology and management. Furthermore, results from our detailed life cycle assessment (LCA) show that producing blast-resistant rice has lower environmental (fossil fuel depletion, ecotoxicity, carcinogenics, eutrophication, acidification, global warming potential, and ozone depletion) impacts per unit of rice than non-blast resistant rice production. Our findings suggest that any reduction in blast via breeding will have significantly positive impacts on reducing global food insecurity through increased supply, as well as decreased price and environmental impacts in production. PMID:27907101

Experimental investigation of blast mitigation and particle-blast interaction during the explosive dispersal of particles and liquids

NASA Astrophysics Data System (ADS)

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

2018-04-01

The attenuation of a blast wave from a high-explosive charge surrounded by a layer of inert material is investigated experimentally in a spherical geometry for a wide range of materials. The blast wave pressure is inferred from extracting the blast wave velocity with high-speed video as well as direct measurements with pressure transducers. The mitigant consists of either a packed bed of particles, a particle bed saturated with water, or a homogeneous liquid. The reduction in peak blast wave overpressure is primarily dependent on the mitigant to explosive mass ratio, M/C, with the mitigant material properties playing a secondary role. Relative peak pressure mitigation reduces with distance and for low values of M/C (< 10) can return to unmitigated pressure levels in the mid-to-far field. Solid particles are more effective at mitigating the blast overpressure than liquids, particularly in the near field and at low values of M/C, suggesting that the energy dissipation during compaction, deformation, and fracture of the powders plays an important role. The difference in scaled arrival time of the blast and material fronts increases with M/C and scaled distance, with solid particles giving the largest separation between the blast wave and cloud of particles. Surrounding a high-explosive charge with a layer of particles reduces the positive-phase blast impulse, whereas a liquid layer has no influence on the impulse in the far field. Taking the total impulse due to the blast wave and material impact into account implies that the damage to a nearby structure may actually be augmented for a range of distances. These results should be taken into consideration in the design of explosive mitigant systems.

Experimental investigation of blast mitigation and particle-blast interaction during the explosive dispersal of particles and liquids

NASA Astrophysics Data System (ADS)

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

2018-05-01

The attenuation of a blast wave from a high-explosive charge surrounded by a layer of inert material is investigated experimentally in a spherical geometry for a wide range of materials. The blast wave pressure is inferred from extracting the blast wave velocity with high-speed video as well as direct measurements with pressure transducers. The mitigant consists of either a packed bed of particles, a particle bed saturated with water, or a homogeneous liquid. The reduction in peak blast wave overpressure is primarily dependent on the mitigant to explosive mass ratio, M/ C, with the mitigant material properties playing a secondary role. Relative peak pressure mitigation reduces with distance and for low values of M/ C (< 10) can return to unmitigated pressure levels in the mid-to-far field. Solid particles are more effective at mitigating the blast overpressure than liquids, particularly in the near field and at low values of M/ C, suggesting that the energy dissipation during compaction, deformation, and fracture of the powders plays an important role. The difference in scaled arrival time of the blast and material fronts increases with M/ C and scaled distance, with solid particles giving the largest separation between the blast wave and cloud of particles. Surrounding a high-explosive charge with a layer of particles reduces the positive-phase blast impulse, whereas a liquid layer has no influence on the impulse in the far field. Taking the total impulse due to the blast wave and material impact into account implies that the damage to a nearby structure may actually be augmented for a range of distances. These results should be taken into consideration in the design of explosive mitigant systems.

Study of blast event propagation in different media using a novel ultrafast miniature optical pressure sensor

NASA Astrophysics Data System (ADS)

Zou, Xiaotian; Wu, Nan; Tian, Ye; Zhang, Hongtao; Niezrecki, Christopher; Wang, Xingwei

2011-06-01

Traumatic brain injury (TBI, also called intracranial injury) is a high potential threat to our soldiers. A helmet structural health monitoring system can be effectively used to study the effects of ballistic/blast events on the helmet and human skull to prevent soldiers from TBI. However, one of the biggest challenges lies in that the pressure sensor installed inside the helmet system must be fast enough to capture the blast wave during the transient period. In this paper, an ultrafast optical fiber sensor is presented to measure the blast signal. The sensor is based on a Fabry-Pérot (FP) interferometeric principle. An FP cavity is built between the endface of an etched optical fiber tip and the silica thin diaphragm attached on the end of a multimode optical fiber. The sensor is small enough to be installed in different locations of a helmet to measure blast pressure simultaneously. Several groups of tests regarding multi-layer blast events were conducted to evaluate the sensors' performance. The sensors were mounted in different segments of a shock tube side by side with the reference sensors, to measure a rapidly increasing pressure. The segments of the shock tube were filled with different media. The results demonstrated that our sensors' responses agreed well with those from the electrical reference sensors. In addition, the home-made shock tube could provide a good resource to study the propagation of blast event in different media.

Quarry blasts assessment and their environmental impacts on the nearby oil pipelines, southeast of Helwan City, Egypt

NASA Astrophysics Data System (ADS)

Mohamed, Adel M. E.; Mohamed, Abuo El-Ela A.

2013-06-01

Ground vibrations induced by blasting in the cement quarries are one of the fundamental problems in the quarrying industry and may cause severe damage to the nearby utilities and pipelines. Therefore, a vibration control study plays an important role in the minimization of environmental effects of blasting in quarries. The current paper presents the influence of the quarry blasts at the National Cement Company (NCC) on the two oil pipelines of SUMED Company southeast of Helwan City, by measuring the ground vibrations in terms of Peak Particle Velocity (PPV). The seismic refraction for compressional waves deduced from the shallow seismic survey and the shear wave velocity obtained from the Multi channel Analysis of Surface Waves (MASW) technique are used to evaluate the closest site of the two pipelines to the quarry blasts. The results demonstrate that, the closest site of the two pipelines is of class B, according to the National Earthquake Hazard Reduction Program (NEHRP) classification and the safe distance to avoid any environmental effects is 650 m, following the deduced Peak Particle Velocity (PPV) and scaled distance (SD) relationship (PPV = 700.08 × SD-1.225) in mm/s and the Air over Pressure (air blast) formula (air blast = 170.23 × SD-0.071) in dB. In the light of prediction analysis, the maximum allowable charge weight per delay was found to be 591 kg with damage criterion of 12.5 mm/s at the closest site of the SUMED pipelines.

Glyburide - Novel Prophylaxis and Effective Treatment for Traumatic Brain Injury

DTIC Science & Technology

2009-08-06

objective – the development, construction and implementation of a cranial- only blast injury app aratus ( COBIA ) for produ ction of reliable, re peatable...dose-dependent” blast-TBI, i ndependent o f t ransthoracic mechanisms of injury to the brain. Using COBIA , we began characterizing the...Cranium-only blast injury apparatus ( COBIA ) During the first year of this proj ect, we implemented several succes sive modifications to the

A Stealth Intervention: The GLAMA (Girls! Lead! Achieve! Mentor! Activate!) and BLAST (Boys! Lead! Activate! Succeed Together!) School Connectedness, Peer Leadership and Physical Activity Transition Program

ERIC Educational Resources Information Center

Jenkinson, Kate A.; Naughton, Geraldine; Benson, Amanda C.

2018-01-01

This study investigated the effects of the GLAMA (Girls! Lead! Achieve! Mentor! Activate!) and BLAST (Boys! Lead! Activate! Succeed Together!) controlled 8-week peer-led stealth intervention on school connectedness and physical activity self-efficacy (PASE). The GLAMA and BLAST sessions were conducted during curriculum time in an Australian state…

Surface modification with alumina blasting and H2SO4-HCl etching for bonding two resin-composite veneers to titanium.

PubMed

Taira, Yohsuke; Egoshi, Takafumi; Kamada, Kohji; Sawase, Takashi

2014-02-01

The purpose of this study was to investigate the effect of an experimental surface treatment with alumina blasting and acid etching on the bond strengths between each of two resin composites and commercially pure titanium. The titanium surface was blasted with alumina and then etched with 45wt% H2SO4 and 15wt% HCl (H2SO4-HCl). A light- and heat-curing resin composite (Estenia) and a light-curing resin composite (Ceramage) were used with adjunctive metal primers. Veneered specimens were subjected to thermal cycling between 4 and 60°C for 50,000 cycles, and the shear bond strengths were determined. The highest bond strengths were obtained for Blasting/H2SO4-HCl/Estenia (30.2 ± 4.5 MPa) and Blasting/Etching/Ceramage (26.0 ± 4.5 MPa), the values of which were not statistically different, followed by Blasting/No etching/Estenia (20.4 ± 2.4 MPa) and Blasting/No etching/Ceramage (0.8 ± 0.3 MPa). Scanning electron microscopy observations revealed that alumina blasting and H2SO4-HCl etching creates a number of micro- and nanoscale cavities on the titanium surface, which contribute to adhesive bonding. © 2013 Eur J Oral Sci.

Viscoelastic Materials Study for the Mitigation of Blast-Related Brain Injury

NASA Astrophysics Data System (ADS)

Bartyczak, Susan; Mock, Willis, Jr.

2011-06-01

Recent preliminary research into the causes of blast-related brain injury indicates that exposure to blast pressures, such as from IED detonation or multiple firings of a weapon, causes damage to brain tissue resulting in Traumatic Brain Injury (TBI) and Post Traumatic Stress Disorder (PTSD). Current combat helmets are not sufficient to protect the warfighter from this danger and the effects are debilitating, costly, and long-lasting. Commercially available viscoelastic materials, designed to dampen vibration caused by shock waves, might be useful as helmet liners to dampen blast waves. The objective of this research is to develop an experimental technique to test these commercially available materials when subject to blast waves and evaluate their blast mitigating behavior. A 40-mm-bore gas gun is being used as a shock tube to generate blast waves (ranging from 1 to 500 psi) in a test fixture at the gun muzzle. A fast opening valve is used to release nitrogen gas from the breech to impact instrumented targets. The targets consist of aluminum/ viscoelastic polymer/ aluminum materials. Blast attenuation is determined through the measurement of pressure and accelerometer data in front of and behind the target. The experimental technique, calibration and checkout procedures, and results will be presented.

Experimental Investigation on the Basic Law of the Fracture Spatial Morphology for Water Pressure Blasting in a Drillhole Under True Triaxial Stress

NASA Astrophysics Data System (ADS)

Huang, Bingxiang; Li, Pengfeng

2015-07-01

The present literature on the morphology of water pressure blasting fractures in drillholes is not sufficient and does not take triaxial confining stress into account. Because the spatial morphology of water pressure blasting fractures in drillholes is not clear, the operations lack an exact basis. Using a large true triaxial water pressure blasting experimental system and an acoustic emission 3-D positioning system, water pressure blasting experiments on cement mortar test blocks (300 mm × 300 mm × 300 mm) were conducted to study the associated basic law of the fracture spatial morphology. The experimental results show that water pressure blasting does not always generate bubble pulsation. After water pressure blasting under true triaxial stress, a crushed compressive zone and a blasting fracture zone are formed from the inside, with the blasting section of the naked drillhole as the center, to the outside. The shape of the outer edges of the two zones is ellipsoidal. The range of the blasting fracture is large in the radial direction of the drillhole, where the surrounding pressure is large, i.e., the range of the blasting fracture in the drillhole radial cross-section is approximately ellipsoidal. The rock near the drillhole wall is affected by a tensile stress wave caused by the test block boundary reflection, resulting in more flake fractures appearing in the fracturing crack surface in the drillhole axial direction and parallel to the boundary surface. The flake fracture is thin, presenting a small-range flake fracture. The spatial morphology of the water pressure blasting fracture in the drillhole along the axial direction is similar to a wide-mouth Chinese bottle: the crack extent is large near the drillhole orifice, gradually narrows inward along the drillhole axial direction, and then increases into an approximate ellipsoid in the internal naked blasting section. Based on the causes of the crack generation, the blasting cracks are divided into three zones: the blasting shock zone, the axial extension zone, and the orifice influence zone. The explosion shock zone is the range that is directly impacted by the explosive shock waves. The axial extension zone is the axial crack area with uniform width, which is formed when the blasting fracture in the edge of the explosion shock zone extends along the drillhole wall. The extension of the orifice influence zone is very large because the explosion stress waves reflect at the free face and generate tensile stress waves. In the water pressure blasting of the drillhole, the sealing section should be lengthened to allow the drillhole blasting cracks to extend sufficiently under the long-time effect of the blasting stress field of quasi-hydrostatic pressure.

Optimizing taxonomic classification of marker-gene amplicon sequences with QIIME 2's q2-feature-classifier plugin.

PubMed

Bokulich, Nicholas A; Kaehler, Benjamin D; Rideout, Jai Ram; Dillon, Matthew; Bolyen, Evan; Knight, Rob; Huttley, Gavin A; Gregory Caporaso, J

2018-05-17

Taxonomic classification of marker-gene sequences is an important step in microbiome analysis. We present q2-feature-classifier ( https://github.com/qiime2/q2-feature-classifier ), a QIIME 2 plugin containing several novel machine-learning and alignment-based methods for taxonomy classification. We evaluated and optimized several commonly used classification methods implemented in QIIME 1 (RDP, BLAST, UCLUST, and SortMeRNA) and several new methods implemented in QIIME 2 (a scikit-learn naive Bayes machine-learning classifier, and alignment-based taxonomy consensus methods based on VSEARCH, and BLAST+) for classification of bacterial 16S rRNA and fungal ITS marker-gene amplicon sequence data. The naive-Bayes, BLAST+-based, and VSEARCH-based classifiers implemented in QIIME 2 meet or exceed the species-level accuracy of other commonly used methods designed for classification of marker gene sequences that were evaluated in this work. These evaluations, based on 19 mock communities and error-free sequence simulations, including classification of simulated "novel" marker-gene sequences, are available in our extensible benchmarking framework, tax-credit ( https://github.com/caporaso-lab/tax-credit-data ). Our results illustrate the importance of parameter tuning for optimizing classifier performance, and we make recommendations regarding parameter choices for these classifiers under a range of standard operating conditions. q2-feature-classifier and tax-credit are both free, open-source, BSD-licensed packages available on GitHub.

Numerical Analyses of the Influence of Blast-Induced Damaged Rock Around Shallow Tunnels in Brittle Rock

NASA Astrophysics Data System (ADS)

Saiang, David; Nordlund, Erling

2009-06-01

Most of the railway tunnels in Sweden are shallow-seated (<20 m of rock cover) and are located in hard brittle rock masses. The majority of these tunnels are excavated by drilling and blasting, which, consequently, result in the development of a blast-induced damaged zone around the tunnel boundary. Theoretically, the presence of this zone, with its reduced strength and stiffness, will affect the overall performance of the tunnel, as well as its construction and maintenance. The Swedish Railroad Administration, therefore, uses a set of guidelines based on peak particle velocity models and perimeter blasting to regulate the extent of damage due to blasting. However, the real effects of the damage caused by blasting around a shallow tunnel and their criticality to the overall performance of the tunnel are yet to be quantified and, therefore, remain the subject of research and investigation. This paper presents a numerical parametric study of blast-induced damage in rock. By varying the strength and stiffness of the blast-induced damaged zone and other relevant parameters, the near-field rock mass response was evaluated in terms of the effects on induced boundary stresses and ground deformation. The continuum method of numerical analysis was used. The input parameters, particularly those relating to strength and stiffness, were estimated using a systematic approach related to the fact that, at shallow depths, the stress and geologic conditions may be highly anisotropic. Due to the lack of data on the post-failure characteristics of the rock mass, the traditional Mohr-Coulomb yield criterion was assumed and used. The results clearly indicate that, as expected, the presence of the blast-induced damage zone does affect the behaviour of the boundary stresses and ground deformation. Potential failure types occurring around the tunnel boundary and their mechanisms have also been identified.

Retinal Ganglion Cell Damage in an Experimental Rodent Model of Blast-Mediated Traumatic Brain Injury

PubMed Central

Mohan, Kabhilan; Kecova, Helga; Hernandez-Merino, Elena; Kardon, Randy H.; Harper, Matthew M.

2013-01-01

Purpose. To evaluate retina and optic nerve damage following experimental blast injury. Methods. Healthy adult mice were exposed to an overpressure blast wave using a custom-built blast chamber. The effects of blast exposure on retina and optic nerve function and structure were evaluated using the pattern electroretinogram (pERG), spectral domain optical coherence tomography (OCT), and the chromatic pupil light reflex. Results. Assessment of the pupil response to light demonstrated decreased maximum pupil constriction diameter in blast-injured mice using red light or blue light stimuli 24 hours after injury compared with baseline in the eye exposed to direct blast injury. A decrease in the pupil light reflex was not observed chronically following blast exposure. We observed a biphasic pERG decrease with the acute injury recovering by 24 hours postblast and the chronic injury appearing at 4 months postblast injury. Furthermore, at 3 months following injury, a significant decrease in the retinal nerve fiber layer was observed using OCT compared with controls. Histologic analysis of the retina and optic nerve revealed punctate regions of reduced cellularity in the ganglion cell layer and damage to optic nerves. Additionally, a significant upregulation of proteins associated with oxidative stress was observed acutely following blast exposure compared with control mice. Conclusions. Our study demonstrates that decrements in retinal ganglion cell responses can be detected after blast injury using noninvasive functional and structural tests. These objective responses may serve as surrogate tests for higher CNS functions following traumatic brain injury that are difficult to quantify. PMID:23620426

Isolated primary blast alters neuronal function with minimal cell death in organotypic hippocampal slice cultures.

PubMed

Effgen, Gwen B; Vogel, Edward W; Lynch, Kimberly A; Lobel, Ayelet; Hue, Christopher D; Meaney, David F; Bass, Cameron R Dale; Morrison, Barclay

2014-07-01

An increasing number of U.S. soldiers are diagnosed with traumatic brain injury (TBI) subsequent to exposure to blast. In the field, blast injury biomechanics are highly complex and multi-phasic. The pathobiology caused by exposure to some of these phases in isolation, such as penetrating or inertially driven injuries, has been investigated extensively. However, it is unclear whether the primary component of blast, a shock wave, is capable of causing pathology on its own. Previous in vivo studies in the rodent and pig have demonstrated that it is difficult to deliver a primary blast (i.e., shock wave only) without rapid head accelerations and potentially confounding effects of inertially driven TBI. We have previously developed a well-characterized shock tube and custom in vitro receiver for exposing organotypic hippocampal slice cultures to pure primary blast. In this study, isolated primary blast induced minimal hippocampal cell death (on average, below 14% in any region of interest), even for the most severe blasts tested (424 kPa peak pressure, 2.3 ms overpressure duration, and 248 kPa*ms impulse). In contrast, measures of neuronal function were significantly altered at much lower exposures (336 kPa, 0.84 ms, and 86.5 kPa*ms), indicating that functional changes occur at exposures below the threshold for cell death. This is the first study to investigate a tolerance for primary blast-induced brain cell death in response to a range of blast parameters and demonstrate functional deficits at subthreshold exposures for cell death.

Optical shaping of gas targets for laser–plasma ion sources

DOE PAGES

Dover, N. P.; Cook, N.; Tresca, O.; ...

2016-02-09

In this paper, we report on the experimental demonstration of a technique to generate steep density gradients in gas-jet targets of interest to laser–plasma ion acceleration. By using an intentional low-energy prepulse, we generated a hydrodynamic blast wave in the gas to shape the target prior to the arrival of an intense COmore » $$_{2}$$($${\\it\\lambda}\\approx 10~{\\rm\\mu}\\text{m}$$) drive pulse. This technique has been recently shown to facilitate the generation of ion beams by shockwave acceleration (Trescaet al.,Phys. Rev. Lett., vol. 115 (9), 2015, 094802). Here, we discuss and introduce a model to understand the generation of these blast waves and discuss in depth the experimental realisation of the technique, supported by hydrodynamics simulations. With appropriate prepulse energy and timing, this blast wave can generate steepened density gradients as short as$$l\\approx 20~{\\rm\\mu}\\text{m}$$($1/e$), opening up new possibilities for laser–plasma studies with near-critical gaseous targets.« less

Expansion of a radially symmetric blast shell into a uniformly magnetized plasma

NASA Astrophysics Data System (ADS)

Dieckmann, M. E.; Moreno, Q.; Doria, D.; Romagnani, L.; Sarri, G.; Folini, D.; Walder, R.; Bret, A.; d'Humières, E.; Borghesi, M.

2018-05-01

The expansion of a thermal pressure-driven radial blast shell into a dilute ambient plasma is examined with two-dimensional PIC simulations. The purpose is to determine if laminar shocks form in a collisionless plasma which resemble their magnetohydrodynamic counterparts. The ambient plasma is composed of electrons with the temperature of 2 keV and cool fully ionized nitrogen ions. It is permeated by a spatially uniform magnetic field. A forward shock forms between the shocked ambient medium and the pristine ambient medium, which changes from an ion acoustic one through a slow magnetosonic one to a fast magnetosonic shock with increasing shock propagation angles relative to the magnetic field. The slow magnetosonic shock that propagates obliquely to the magnetic field changes into a tangential discontinuity for a perpendicular propagation direction, which is in line with the magnetohydrodynamic model. The expulsion of the magnetic field by the expanding blast shell triggers an electron-cyclotron drift instability.

Immobilization of Cr (VI) in stainless steel slag and Cd, As, and Pb in wastewater using blast furnace slag via a hydrothermal treatment

NASA Astrophysics Data System (ADS)

Tae, Soon-Jae; Morita, Kazuki

2017-05-01

The immobilization of hexavalent chromium in stainless steel slag using blast furnace slag as the immobilizing agent and by performing a hydrothermal treatment was investigated. The results showed that there was no immobilization in the absence of the blast furnace slag. On the other hand, the hexavalent chromium in stainless steel slag could be immobilized through the hydrothermal reaction when blast furnace slag was used at 250 °C for 24 h. A leaching test was performed to evaluate the degree of immobilization of hexavalent chromium in the products formed by the hydrothermal reaction. It was found that the degree of immobilization was very high. Based on the results obtained, the immobilization mechanism of hexavalent chromium in stainless steel slag, resulting from the hydrothermal treatment of blast furnace slag, could be elucidated. Finally, the immobilization of cadmium, lead, and arsenic using blast furnace slag as the immobilization agent was also studied while focusing on the effects of the hydrothermal treatment.

Chloroplast-expressed MSI-99 in tobacco improves disease resistance and displays inhibitory effect against rice blast fungus.

PubMed

Wang, Yun-Peng; Wei, Zheng-Yi; Zhang, Yu-Ying; Lin, Chun-Jing; Zhong, Xiao-Fang; Wang, Yue-Lin; Ma, Jing-Yong; Ma, Jian; Xing, Shao-Chen

2015-03-02

Rice blast is a major destructive fungal disease that poses a serious threat to rice production and the improvement of blast resistance is critical to rice breeding. The antimicrobial peptide MSI-99 has been suggested as an antimicrobial peptide conferring resistance to bacterial and fungal diseases. Here, a vector harboring the MSI-99 gene was constructed and introduced into the tobacco chloroplast genome via particle bombardment. Transformed plants were obtained and verified to be homoplastomic by PCR and Southern hybridization. In planta assays demonstrated that the transgenic tobacco plants displayed an enhanced resistance to the fungal disease. The evaluation of the antimicrobial activity revealed that the crude protein extracts from the transgenic plants manifested an antimicrobial activity against E. coli, even after incubation at 120 °C for 20 min, indicating significant heat stability of MSI-99. More importantly, the MSI-99-containing protein extracts were firstly proved in vitro and in vivo to display significant suppressive effects on two rice blast isolates. These findings provide a strong basis for the development of new biopesticides to combat rice blast.

Corrosion mechanism of carbon brick in the blast furnace hearth by potassium

NASA Astrophysics Data System (ADS)

Jiao, Ke-xin; Zhang, Jian-liang; Liu, Zheng-jian; Liu, Zhuang-zhuang; Deng, Yong; Fan, Xiaoyue

2017-11-01

Alkali plays a significant role in the formation of brittle layer of carbon brick in the blast furnace hearth. The brittle layer in a commercial blast furnace hearth was investigated. Large amounts of potassium compounds were found in the brittle layer. Subsequently, the carbon bricks which reacted with potassium in the simulation of blast furnace hearth under different contents of potassium in the brick (0.25, 0.5, 1.0 and 2.0 wt.%) during various reaction times (0.5, 1, 2 and 4 h) were experimentally studied. Finally, the formation mechanism of the brittle layer in carbon brick was clarified. The investigation results show that a large number of cracks are present in the brittle layer. The average potassium content in the brittle layer is 1 wt.%. According to the experimental results, cracks in the carbon brick can be formed by the attack of potassium. The reason for the formation of the brittle layer in the carbon brick is that the liquid potassium permeates into the carbon brick through the pores and cracks, and then reacts with SiO2 and Al2O3 in CO atmosphere. The generated potassium compounds nepheline and leucite lead to the volume expansion and the damage of the carbon brick.

Field Evaluation of Fracture Control in Tunnel Blasting

DOT National Transportation Integrated Search

1979-12-01

The objective of this research was to implement fracture control procedures in a tunnel project and to assess the practicality, advantages, disadvantages, performance and cost effectiveness of fracture control methods against smooth blasting procedur...

[Effect of soil preparation and fertilization on foliage and shoot growth of Ginkgo biloba and its medicine content].

PubMed

He, Binghui; Zhong, Zhangcheng

2004-06-01

The study showed that the efficiency of various treatments in improving the height growth of Ginkgo biloba was organic fertilizer plus intercropping > soil preparation by blasting plus intercropping > organic fertilizer > soil preparation by blasting > intercropping, and the height growth increased by 14.5%, 8.6%, 5.7%, 3.2% and 0, respectively. The efficiency of the treatments in improving new shoot growth was organic fertilizer plus intercropping > soil preparation by blasting plus intercropping > intercropping > organic fertilizer > soil preparation by blasting, and the new shoot growth increased by 58.1%, 36.6%, 33.1%, 30.2% and 14.0%, respectively. Soil preparation, organic fertilization and intercropping had no different effect on the number of long shoots, but their effect on the numbers of short shoots and leaves was significantly different. The most efficient treatment in improving the medicine content was organic fertilization plus intercropping. Compared with control, the content of quercetin and rutin in Ginkgo biloba leaves increased by 420% and 220%, respectively.

Reliability Analysis of Retaining Walls Subjected to Blast Loading by Finite Element Approach

NASA Astrophysics Data System (ADS)

GuhaRay, Anasua; Mondal, Stuti; Mohiuddin, Hisham Hasan

2018-02-01

Conventional design methods adopt factor of safety as per practice and experience, which are deterministic in nature. The limit state method, though not completely deterministic, does not take into account effect of design parameters, which are inherently variable such as cohesion, angle of internal friction, etc. for soil. Reliability analysis provides a measure to consider these variations into analysis and hence results in a more realistic design. Several studies have been carried out on reliability of reinforced concrete walls and masonry walls under explosions. Also, reliability analysis of retaining structures against various kinds of failure has been done. However, very few research works are available on reliability analysis of retaining walls subjected to blast loading. Thus, the present paper considers the effect of variation of geotechnical parameters when a retaining wall is subjected to blast loading. However, it is found that the variation of geotechnical random variables does not have a significant effect on the stability of retaining walls subjected to blast loading.

Blackjack

DTIC Science & Technology

2012-05-01

astar (C++) path finding algorithms.  bwaves (Fortran) simulation of blast waves in 3D transonic transient laminar viscous flow.  bzip2 (C) in...search based on Profile Hidden Markov Models.  lbm (C) implementation of Lattice Boltzman Method for simulation of incompressible fluids in 3D...to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE

Simplified Methods for Improving the Blast Resistance of Cold-Formed Steel Walls

DTIC Science & Technology

2011-01-01

sheathing products such as oriented strand board ( OSB ) offer a level of blast resistance that may be effective in mitigating lower-level blast...considered in order to keep designs to a minimum cost. Standard sheathing materials such as OSB , gypsum and plywood— as well as specially selected sheathing...commercially available clip connectors. Sheathing materials such as gypsum and OSB are brittle and have significantly lower capacity than sheet steel

Updates to Blast Injury Criteria Models for Nuclear Casualty Estimation

DTIC Science & Technology

2015-12-01

the likelihood of blast-related injury use a two-step process. First, the maximum velocity obtained by the human body or secondary missile is determined...the human body . Secondary injuries are caused by missiles that are accelerated by the blast wave. Tertiary injuries are caused by the acceleration of...the human body and the ensuing deceleration. In this work, we focus on secondary and tertiary injuries. Because of the dramatic effects experienced

Experimental and Numerical Investigations into Polymeric Coatings for Blast Protection

DTIC Science & Technology

2011-09-01

the effect of applying polyurea coatings made by Defence Science and Technology Organisation (DSTO) to the back face of D36 and X80 steel plates under...blast loading. It was found that the plates coated with polyurea deformed less than uncoated plates when subjected to the same blast loading...three commercially available products that are currently on the market in Australia. Two of the coatings were polyurea /polyurethane blends and the

Retractor-Based Stroking Seat System and Energy-Absorbing Floor to Mitigate High Shock and Vertical Acceleration

DTIC Science & Technology

2014-04-15

Seat stroke, Lumbar loads, Accelerative load, M&S analysis, Blast , UBB, LS- DYNA , ATD 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT...typical blast input load to the seat . Resulting crew injuries are monitored for various vertical accelerative loading scenarios. The retractor load...an enforced blast pulse, this hull structural thickness does not have any effect on the results. 2.2 Seatbelt model Automotive seat belts with

Localized coating removal using plastic media blasting

NASA Technical Reports Server (NTRS)

Novak, Howard L.; Wyckoff, Michael G.; Zook, Lee M.

1988-01-01

Steps taken to qualify the use of plastic media blasting for safely and effectively removing paint and other coatings from solid rocket booster aluminum structures are described. As a result of the effort, an improvement was made in the design of surface finishing equipment for processing flight hardware, in addition to a potentially patentable idea on improved plastic media composition. The general arrangement of the blast equipment and the nozzle configuration are presented.

Epidemiological Study of Mild Traumatic Brain Injury Sequelae Caused by Blast Exposure During Operations Iraqi Freedom and Enduring Freedom

DTIC Science & Technology

2013-10-01

1991), pain using both the McGill Pain Questionnaire short form (MPQ-SF) (Melzak, 1987) and the 11 point Numerical Scale (Jensen MP et al, 1989...subject above, complete standardized current state questionnaires for qualitative and quantitative measurement of: Post-concussion syndrome (PCS) using...consciousness, stress, pain , helmet wearing, shrapnel injury, tympanic membrane rupture, hearing loss, type of blast, immediate blast effects, number of

Blasting methods for heterogeneous rocks in hillside open-pit mines with high and steep slopes

NASA Astrophysics Data System (ADS)

Chen, Y. J.; Chang, Z. G.; Chao, X. H.; Zhao, J. F.

2017-06-01

In the arid desert areas in Xinjiang, most limestone quarries are hillside open-pit mines (OPMs) where the limestone is hard, heterogeneous, and fractured, and can be easily broken into large blocks by blasting. This study tried to find effective technical methods for blasting heterogeneous rocks in such quarries based on an investigation into existing problems encountered in actual mining at Hongshun Limestone Quarry in Xinjiang. This study provided blasting schemes for hillside OPMs with different heights and slopes. These schemes involve the use of vertical deep holes, oblique shallow holes, and downslope hole-by-hole sublevel or simultaneous detonation techniques. In each bench, the detonations of holes in a detonation unit occur at intervals of 25-50 milliseconds. The research findings can offer technical guidance on how to blast heterogeneous rocks in hillside limestone quarries.

Osteogenic differentiation of periosteum-derived stromal cells in blast-associated traumatic loading

NASA Astrophysics Data System (ADS)

Sory, David R.; Amin, Harsh D.; Rankin, Sara M.; Proud, William G.

2017-06-01

One of the most recurrent medical complications resulting from blast trauma includes blast-induced heterotopic ossification. Heterotopic ossification refers to the pathologic formation of extraskeletal bone in non-osseous tissue. Although a number of studies have established the interaction between mechanics and biology in bone formation following shock trauma, the exact nature of the mechanical stimuli associated to blast-loading and their influence on the activation of osteogenic differentiation of cells remain unanswered. Here we present the design and calibration of a loading platform compatible with living cells to examine the effects of mechanical stress pulses of blast-associated varying strain rates on the activation of osteogenic differentiation of periosteum (PO) cells. Multiaxial compression loadings of PO cells are performed at different magnitudes of stress and ranges of strain rate. A proof of concept is presented so as to establish a new window to address fundamental questions regarding blast injuries at the cellular level. This work was conducted under the auspices of the Royal British Legion Centre for Blast Injury Studies at Imperial College London. The authors would like to acknowledge the financial support of the Royal British Legion.

Use of simulated data sets to evaluate the fidelity of metagenomic processing methods

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

Mavromatis, K; Ivanova, N; Barry, Kerrie

2007-01-01

Metagenomics is a rapidly emerging field of research for studying microbial communities. To evaluate methods presently used to process metagenomic sequences, we constructed three simulated data sets of varying complexity by combining sequencing reads randomly selected from 113 isolate genomes. These data sets were designed to model real metagenomes in terms of complexity and phylogenetic composition. We assembled sampled reads using three commonly used genome assemblers (Phrap, Arachne and JAZZ), and predicted genes using two popular gene-finding pipelines (fgenesb and CRITICA/GLIMMER). The phylogenetic origins of the assembled contigs were predicted using one sequence similarity-based ( blast hit distribution) and twomore » sequence composition-based (PhyloPythia, oligonucleotide frequencies) binning methods. We explored the effects of the simulated community structure and method combinations on the fidelity of each processing step by comparison to the corresponding isolate genomes. The simulated data sets are available online to facilitate standardized benchmarking of tools for metagenomic analysis.« less

Use of simulated data sets to evaluate the fidelity of Metagenomicprocessing methods

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

Mavromatis, Konstantinos; Ivanova, Natalia; Barry, Kerri

2006-12-01

Metagenomics is a rapidly emerging field of research for studying microbial communities. To evaluate methods presently used to process metagenomic sequences, we constructed three simulated data sets of varying complexity by combining sequencing reads randomly selected from 113 isolate genomes. These data sets were designed to model real metagenomes in terms of complexity and phylogenetic composition. We assembled sampled reads using three commonly used genome assemblers (Phrap, Arachne and JAZZ), and predicted genes using two popular gene finding pipelines (fgenesb and CRITICA/GLIMMER). The phylogenetic origins of the assembled contigs were predicted using one sequence similarity--based (blast hit distribution) and twomore » sequence composition--based (PhyloPythia, oligonucleotide frequencies) binning methods. We explored the effects of the simulated community structure and method combinations on the fidelity of each processing step by comparison to the corresponding isolate genomes. The simulated data sets are available online to facilitate standardized benchmarking of tools for metagenomic analysis.« less

Modelling of Coke Layer Collapse during Ore Charging in Ironmaking Blast Furnace by DEM

NASA Astrophysics Data System (ADS)

Narita, Yoichi; Mio, Hiroshi; Orimoto, Takashi; Nomura, Seiji

2017-06-01

A technical issue in an ironmaking blast furnace operation is to realize the optimum layer thickness and the radial distribution of burden (ore and coke) to enhance its efficiency and productivity. When ore particles are charged onto the already-embedded coke layer, the coke layer-collapse phenomenon occurs. The coke layer-collapse phenomenon has a significant effect on the distribution of ore and coke layer thickness in the radial direction. In this paper, the mechanical properties of coke packed bed under ore charging were investigated by the impact-loading test and the large-scale direct shear test. Experimental results show that the coke particle is broken by the impact force of ore charging, and the particle breakage leads to weaken of coke-layer strength. The expression of contact force for coke in Discrete Element Method (DEM) was modified based on the measured data, and it followed by the 1/3-scaled experiment on coke's collapse phenomena. Comparing a simulation by modified model to the 1/3-scaled experiment, they agreed well in the burden distribution.

Comparative Genomics and Association Mapping Approaches for Blast Resistant Genes in Finger Millet Using SSRs

PubMed Central

Babu, B. Kalyana; Dinesh, Pandey; Agrawal, Pawan K.; Sood, S.; Chandrashekara, C.; Bhatt, Jagadish C.; Kumar, Anil

2014-01-01

The major limiting factor for production and productivity of finger millet crop is blast disease caused by Magnaporthe grisea. Since, the genome sequence information available in finger millet crop is scarce, comparative genomics plays a very important role in identification of genes/QTLs linked to the blast resistance genes using SSR markers. In the present study, a total of 58 genic SSRs were developed for use in genetic analysis of a global collection of 190 finger millet genotypes. The 58 SSRs yielded ninety five scorable alleles and the polymorphism information content varied from 0.186 to 0.677 at an average of 0.385. The gene diversity was in the range of 0.208 to 0.726 with an average of 0.487. Association mapping for blast resistance was done using 104 SSR markers which identified four QTLs for finger blast and one QTL for neck blast resistance. The genomic marker RM262 and genic marker FMBLEST32 were linked to finger blast disease at a P value of 0.007 and explained phenotypic variance (R2) of 10% and 8% respectively. The genomic marker UGEP81 was associated to finger blast at a P value of 0.009 and explained 7.5% of R2. The QTLs for neck blast was associated with the genomic SSR marker UGEP18 at a P value of 0.01, which explained 11% of R2. Three QTLs for blast resistance were found common by using both GLM and MLM approaches. The resistant alleles were found to be present mostly in the exotic genotypes. Among the genotypes of NW Himalayan region of India, VHC3997, VHC3996 and VHC3930 were found highly resistant, which may be effectively used as parents for developing blast resistant cultivars in the NW Himalayan region of India. The markers linked to the QTLs for blast resistance in the present study can be further used for cloning of the full length gene, fine mapping and their further use in the marker assisted breeding programmes for introgression of blast resistant alleles into locally adapted cultivars. PMID:24915067

Comparative genomics and association mapping approaches for blast resistant genes in finger millet using SSRs.

PubMed

Babu, B Kalyana; Dinesh, Pandey; Agrawal, Pawan K; Sood, S; Chandrashekara, C; Bhatt, Jagadish C; Kumar, Anil

2014-01-01

The major limiting factor for production and productivity of finger millet crop is blast disease caused by Magnaporthe grisea. Since, the genome sequence information available in finger millet crop is scarce, comparative genomics plays a very important role in identification of genes/QTLs linked to the blast resistance genes using SSR markers. In the present study, a total of 58 genic SSRs were developed for use in genetic analysis of a global collection of 190 finger millet genotypes. The 58 SSRs yielded ninety five scorable alleles and the polymorphism information content varied from 0.186 to 0.677 at an average of 0.385. The gene diversity was in the range of 0.208 to 0.726 with an average of 0.487. Association mapping for blast resistance was done using 104 SSR markers which identified four QTLs for finger blast and one QTL for neck blast resistance. The genomic marker RM262 and genic marker FMBLEST32 were linked to finger blast disease at a P value of 0.007 and explained phenotypic variance (R²) of 10% and 8% respectively. The genomic marker UGEP81 was associated to finger blast at a P value of 0.009 and explained 7.5% of R². The QTLs for neck blast was associated with the genomic SSR marker UGEP18 at a P value of 0.01, which explained 11% of R². Three QTLs for blast resistance were found common by using both GLM and MLM approaches. The resistant alleles were found to be present mostly in the exotic genotypes. Among the genotypes of NW Himalayan region of India, VHC3997, VHC3996 and VHC3930 were found highly resistant, which may be effectively used as parents for developing blast resistant cultivars in the NW Himalayan region of India. The markers linked to the QTLs for blast resistance in the present study can be further used for cloning of the full length gene, fine mapping and their further use in the marker assisted breeding programmes for introgression of blast resistant alleles into locally adapted cultivars.

Low Level Primary Blast Injury in Rodent Brain

PubMed Central

Pun, Pamela B. L.; Kan, Enci Mary; Salim, Agus; Li, Zhaohui; Ng, Kian Chye; Moochhala, Shabbir M.; Ling, Eng-Ang; Tan, Mui Hong; Lu, Jia

2011-01-01

The incidence of blast attacks and resulting traumatic brain injuries has been on the rise in recent years. Primary blast is one of the mechanisms in which the blast wave can cause injury to the brain. The aim of this study was to investigate the effects of a single sub-lethal blast over pressure (BOP) exposure of either 48.9 kPa (7.1 psi) or 77.3 kPa (11.3 psi) to rodents in an open-field setting. Brain tissue from these rats was harvested for microarray and histopathological analyses. Gross histopathology of the brains showed that cortical neurons were “darkened” and shrunken with narrowed vasculature in the cerebral cortex day 1 after blast with signs of recovery at day 4 and day 7 after blast. TUNEL-positive cells were predominant in the white matter of the brain at day 1 after blast and double-labeling of brain tissue showed that these DNA-damaged cells were both oligodendrocytes and astrocytes but were mainly not apoptotic due to the low caspase-3 immunopositivity. There was also an increase in amyloid precursor protein immunoreactive cells in the white matter which suggests acute axonal damage. In contrast, Iba-1 staining for macrophages or microglia was not different from control post-blast. Blast exposure altered the expression of over 5786 genes in the brain which occurred mostly at day 1 and day 4 post-blast. These genes were narrowed down to 10 overlapping genes after time-course evaluation and functional analyses. These genes pointed toward signs of repair at day 4 and day 7 post-blast. Our findings suggest that the BOP levels in the study resulted in mild cellular injury to the brain as evidenced by acute neuronal, cerebrovascular, and white matter perturbations that showed signs of resolution. It is unclear whether these perturbations exist at a milder level or normalize completely and will need more investigation. Specific changes in gene expression may be further evaluated to understand the mechanism of blast-induced neurotrauma. PMID:21541261

Effect of casing yield stress on bomb blast impulse

NASA Astrophysics Data System (ADS)

Hutchinson, M. D.

2012-08-01

An equation to predict blast effects from cased charges was first proposed by U. Fano in 1944 and revised by E.M. Fisher in 1953 [1]. Fisher's revision provides much better matches to available blast impulse data, but still requires empirical parameter adjustments. A new derivation [2], based on the work of R.W. Gurney [3] and G.I. Taylor [4], has resulted in an equation which nearly matches experimental data. This new analytical model is also capable of being extended, through the incorporation of additional physics, such as the effects of early case fracture, finite casing thickness, casing metal strain energy dissipation, explosive gas escape through casing fractures and the comparative dynamics of blast wave and metal fragment impacts. This paper will focus on the choice of relevant case fracture strain criterion, as it will be shown that this allows the explicit inclusion of the dynamic properties of the explosive and casing metal. It will include a review and critique of the most significant earlier work on this topic, contained in a paper by Hoggatt and Recht [5]. Using this extended analytical model, good matches can readily be made to available free-field blast impulse data, without any empirical adjustments being needed. Further work will be required to apply this model to aluminised and other highly oxygen-deficient explosives.

Brain Vulnerability to Repeated Blast Overpressure and Polytrauma

DTIC Science & Technology

2012-05-01

shock tube: distinguishing primary and tertiary blast injury mechanisms in rat TBI - Roles of polyunsaturated fatty acids in traumatic brain injury...vulnerabilities and resilience: evaluation of salutary effects of DHA supplementation using neurolipidomics and functional outcome assessments

Large scale germplasm screening for identification of novel rice blast resistance sources

PubMed Central

Vasudevan, Kumar; Vera Cruz, Casiana M.; Gruissem, Wilhelm; Bhullar, Navreet K.

2014-01-01

Rice is a major cereal crop that contributes significantly to global food security. Biotic stresses, including the rice blast fungus, cause severe yield losses that significantly impair rice production worldwide. The rapid genetic evolution of the fungus often overcomes the resistance conferred by major genes after a few years of intensive agricultural use. Therefore, resistance breeding requires continuous efforts of enriching the reservoir of resistance genes/alleles to effectively tackle the disease. Seed banks represent a rich stock of genetic diversity, however, they are still under-explored for identifying novel genes and/or their functional alleles. We conducted a large-scale screen for new rice blast resistance sources in 4246 geographically diverse rice accessions originating from 13 major rice-growing countries. The accessions were selected from a total collection of over 120,000 accessions based on their annotated rice blast resistance information in the International Rice Genebank. A two-step resistance screening protocol was used involving natural infection in a rice uniform blast nursery and subsequent artificial infections with five single rice blast isolates. The nursery-resistant accessions showed varied disease responses when infected with single isolates, suggesting the presence of diverse resistance genes/alleles in this accession collection. In addition, 289 accessions showed broad-spectrum resistance against all five single rice blast isolates. The selected resistant accessions were genotyped for the presence of the Pi2 resistance gene, thereby identifying potential accessions for isolation of allelic variants of this blast resistance gene. Together, the accession collection with broad spectrum and isolate specific blast resistance represent the core material for isolation of previously unknown blast resistance genes and/or their allelic variants that can be deployed in rice breeding programs. PMID:25324853

A Mouse Model of Blast-Induced mild Traumatic Brain Injury

PubMed Central

Rubovitch, Vardit; Ten-Bosch, Meital; Zohar, Ofer; Harrison, Catherine R.; Tempel-Brami, Catherine; Stein, Elliot; Hoffer, Barry J.; Balaban, Carey D.; Schreiber, Shaul; Chiu, Wen-Ta; Pick, Chaim G.

2011-01-01

Improvised explosive devices (IEDs) are one of the main causes for casualties among civilians and military personnel in the present war against terror. Mild traumatic brain injury from IEDs induces various degrees of cognitive, emotional and behavioral disturbances but knowledge of the exact brain pathophysiology following exposure to blast is poorly understood. The study was aimed at establishing a murine model for a mild BI-TBI that isolates low-level blast pressure effects to the brain without systemic injuries. An open-field explosives detonation was used to replicate, as closely as possible, low-level blast trauma in the battlefield or at a terror-attack site. No alterations in basic neurological assessment or brain gross pathology were found acutely in the blast-exposed mice. At 7 days post blast, cognitive and behavioral tests revealed significantly decreased performance at both 4 and 7 meters distance from the blast (5.5 and 2.5 PSI, respectively). At 30 days post-blast, clear differences were found in animals at both distances in the object recognition test, and in the 7 m group in the Y maze test. Using MRI, T1 weighted images showed an increased BBB permeability one month post-blast. DTI analysis showed an increase in fractional anisotropy (FA) and a decrease in radial diffusivity. These changes correlated with sites of up-regulation of manganese superoxide dismutase 2 in neurons and CXC-motif chemokine receptor 3 around blood vessels in fiber tracts. These results may represent brain axonal and myelin abnormalities. Cellular and biochemical studies are underway in order to further correlate the blast-induced cognitive and behavioral changes and to identify possible underlying mechanisms that may help develop treatment- and neuroprotective modalities. PMID:21946269

Modelling the blast environment and relating this to clinical injury: experience from the 7/7 inquest.

PubMed

Hepper, Alan E; Pope, D J; Bishop, M; Kirkman, E; Sedman, A; Russell, R; Mahoney, P F; Clasper, J

2014-06-01

This paper addresses the computational modelling of a series of specific blast-related incidents and the relationships of clinical and engineering interpretations. The Royal Centre for Defence Medicine and the Defence Science and Technology Laboratory were tasked in 2010 by the UK Ministry of Defence to assist the Coroner's inquests into the 7 July 2005 London bombings. A three phase approach was taken. The first phase included an engineering expert in blast effects on structures reviewing photographs of the damaged carriages and bus to give a view on the likely physical effects on people close to the explosions. The second phase was a clinical review of the evidence by military clinicians to assess blast injury in the casualties. The third phase was to model the blast environment by structural dynamics experts to assess likely blast loading on victims to evaluate the potential blast loading on individuals. This loading information was then assessed by physiology experts. Once all teams (engineering, clinical and modelling/physiological) had separately arrived at their conclusions, the information streams were integrated to arrive at a consensus. The aim of this paper is to describe the methodology used as a potential model for others to consider if faced with a similar investigation, and to show the benefit of the transition of military knowledge to a civilian environment. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Blast-related mild traumatic brain injury: a Bayesian random-effects meta-analysis on the cognitive outcomes of concussion among military personnel.

PubMed

Karr, Justin E; Areshenkoff, Corson N; Duggan, Emily C; Garcia-Barrera, Mauricio A

2014-12-01

Throughout their careers, many soldiers experience repeated blasts exposures from improvised explosive devices, which often involve head injury. Consequentially, blast-related mild Traumatic Brain Injury (mTBI) has become prevalent in modern conflicts, often occuring co-morbidly with psychiatric illness (e.g., post-traumatic stress disorder [PTSD]). In turn, a growing body of research has begun to explore the cognitive and psychiatric sequelae of blast-related mTBI. The current meta-analysis aimed to evaluate the chronic effects of blast-related mTBI on cognitive performance. A systematic review identified 9 studies reporting 12 samples meeting eligibility criteria. A Bayesian random-effects meta-analysis was conducted with cognitive construct and PTSD symptoms explored as moderators. The overall posterior mean effect size and Highest Density Interval (HDI) came to d = -0.12 [-0.21, -0.04], with executive function (-0.16 [-0.31, 0.00]), verbal delayed memory (-0.19 [-0.44, 0.06]) and processing speed (-0.11 [-0.26, 0.01]) presenting as the most sensitive cognitive domains to blast-related mTBI. When dividing executive function into diverse sub-constructs (i.e., working memory, inhibition, set-shifting), set-shifting presented the largest effect size (-0.33 [-0.55, -0.05]). PTSD symptoms did not predict cognitive effects sizes, β PTSD  = -0.02 [-0.23, 0.20]. The results indicate a subtle, but chronic cognitive impairment following mTBI, especially in set-shifting, a relevant aspect of executive attention. These findings are consistent with past meta-analyses on multiple mTBI and correspond with past neuroimaging research on the cognitive correlates of white matter damage common in mTBI. However, all studies had cross-sectional designs, which resulted in universally low quality ratings and limited the conclusions inferable from this meta-analysis.

ARC Collaborative Research Seminar Series

Science.gov Websites

been used to formulate design rules for hydration-based TES systems. Don Siegel is an Associate structural-acoustics, design of complex systems, and blast event simulations. Technology that he developed interests includes advanced fatigue and fracture assessment methodologies, computational methods for

Simulations of heterogeneous detonations and post-detonation turbulent mixing and afterburning

NASA Astrophysics Data System (ADS)

Gottiparthi, Kalyana Chakravarthi; Menon, Suresh

2012-03-01

We conduct three-dimensional numerical simulations of the propagation of blast waves resulting from detonation of a nitromethane charge of radius 5.9 cm loaded with aluminum particles and analyze the afterburn process as well as the generation of multiple scales ofmixing in the post detonation flow field. In the current study, the particle combustion is observed to be dependent on particle dispersal and mixing of gases in the flow where particle dispersal spreads aluminum within the flow and mixing provides the necessary oxidizer. Thus, 5 μm aluminum particles are burnt more effectively in comparison to 10 μm particles for a fixed initial mass of particles. Also, for a fixed initial particle size, increase in the initial mass of aluminum particles resulted in greater mixing.

Design of air blast pressure sensors based on miniature silicon membrane and piezoresistive gauges

NASA Astrophysics Data System (ADS)

Riondet, J.; Coustou, A.; Aubert, H.; Pons, P.; Lavayssière, M.; Luc, J.; Lefrançois, A.

2017-11-01

Available commercial piezoelectric pressure sensors are not able to accurately reproduce the ultra-fast transient pressure occurring during an air blast experiment. In this communication a new pressure sensor prototype based on a miniature silicon membrane and piezoresistive gauges is reported for significantly improving the performances in terms of time response. Simulation results demonstrate the feasibility of a pressure transducer having a fundamental resonant frequency almost ten times greater than the commercial piezoelectric sensors one. The sensor uses a 5μm-thick SOI membrane and four P-type silicon gauges (doping level ≅ 1019 at/cm3) in Wheatstone bridge configuration. To obtain a good trade-off between the fundamental mechanical resonant frequency and pressure sensitivity values, the typical dimension of the rectangular membrane is fixed to 30μm x 90μm with gauge dimension of 1μm x 5μm. The achieved simulated mechanical resonant frequency of these configuration is greater than 40MHz with a sensitivity of 0.04% per bar.

Influence of the post-weld surface treatment on the corrosion resistance of the duplex stainless steel 1.4062

NASA Astrophysics Data System (ADS)

Rosemann, P.; Müller, C.; Baumann, O.; Modersohn, W.; Halle, T.

2017-03-01

The duplex stainless steel 1.4062 (X2CrNiN22-2) is used as alternative material to austenitic stainless steels in the construction industry. The corrosion resistance of welded seams is influenced by the base material, the weld filler material, the welding process and also by the final surface treatment. The scale layer next to the weld seam can be removed by grinding, pickling, electro-polished or blasting depending on the application and the requested corrosion resistance. Blasted surfaces are often used in industrial practice due to the easier and cheaper manufacturing process compared to pickled or electro-polished surfaces. Furthermore blasting with corundum-grain is more effective than blasting with glass-beads which also lower the process costs. In recent years, stainless steel surfaces showed an unusually high susceptibility to pitting corrosion after grinding with corundum. For this reason, it is now also questioned critically whether the corrosion resistance is influenced by the applied blasting agent. This question was specifically investigated by comparing grinded, pickled, corundum-grain- and glass-bead-blasted welding seams. Results of the SEM analyses of the blasting agents and the blasted surfaces will be presented and correlated with the different performed corrosion tests (potential measurement, KorroPad-test and pitting potential) on welding seams with different surface treatments.

Development of a Comprehensive Blast-Related Auditory Injury Database (BRAID)

DTIC Science & Technology

2016-05-01

these, may result in temporary or persistent noise-induced hear- ing loss (NIHL) and tinnitus . NIHL and tinnitus present a problematic public...uals deployed to battle zones are increasingly at risk for NIHL, tinnitus , and other otologic injuries [4]. The effects of blast exposure on the...primary interest because it may be permanent and cause persistent symptoms of tinnitus [18–20] and hear- ing loss [6,17,21–23]. Blast-related middle

Glyburide - Novel Prophylaxis and Effective Treatment for Blast-Traumatic Brain Injury

DTIC Science & Technology

2013-10-01

determine the safety of the SUR1 blocker , glyburide (glibenclamide), as it might be used as prophylaxis against blast-TBI. During the 4th year of...We completed evaluation of the prophylaxis treatment with SUR1 blocker , glyburide in the neurobehavioral outcome after blast-TBI (Obj. 1d, c...APP ( Beta -amyloid precursor protein) 64 qPCR Casp 3 (caspase 3) 28 Tissue hemoglobin detection SP1 (ischemic, hypoxic marker) 7 ED1

Role of neutrophil elastase in lung injury induced by burn-blast combined injury in rats.

PubMed

Chai, Jia-ke; Cai, Jian-hua; Deng, Hu-ping; Zou, Xiao-fang; Liu, Wei; Hu, Qing-gang; Shen, Chuan-an; Yin, Hui-nan; Zhang, Xi-bo; Chi, Yun-fei; Ma, Li; Feng, Rui

2013-06-01

Neutrophil elastase (NE) takes part in the pathogenesis of acute lung injury. However, its role in lung injury of burn-blast combined injury is unclear. Our objective was to assess the role of NE, and effect of sivelestat, a specific NE inhibitor, in lung injury induced by burn-blast combined injury in rats. One hundred and sixty male Sprague-Dawley rats were randomly subjected to burn-blast combined injury (BB) group, burn-blast combined injury plus sivelestat treatment (S) group or control (C) group. Blood gas, protein concentration and NE activity in bronchoalveolar lavage fluid (BALF), pulmonary myeloperoxidase (MPO) activity, serum concentrations of TNF-α and IL-8, etc. were investigated from 0 h to 7 d post-injury. In BB group, PaO2 decreased, while NE activity in BALF, total protein concentration in BALF, pulmonary MPO activity and W/D ratio, serum concentrations of TNF-α and IL-8 increased with neutrophil infiltration, progressive bleeding and pulmonary oedema. Compared with BB group, sivelestat treatment decreased the NE activity and ameliorated the above indexes. Sivelestat, exerts a protective effect in lung injury after burn-blast combined injury through inhibiting NE activity to decrease pulmonary vascular permeability, neutrophil sequestration, and production of TNF-α and IL-8. Copyright © 2012 Elsevier Ltd and ISBI. All rights reserved.

Blast-Induced Tinnitus and Hearing Loss in Rats: Behavioral and Imaging Assays

PubMed Central

Mao, Johnny C.; Pace, Edward; Pierozynski, Paige; Kou, Zhifeng; Shen, Yimin; VandeVord, Pamela; Haacke, E. Mark; Zhang, Xueguo

2012-01-01

Abstract The current study used a rat model to investigate the underlying mechanisms of blast-induced tinnitus, hearing loss, and associated traumatic brain injury (TBI). Seven rats were used to evaluate behavioral evidence of tinnitus and hearing loss, and TBI using magnetic resonance imaging following a single 10-msec blast at 14 psi or 194 dB sound pressure level (SPL). The results demonstrated that the blast exposure induced early onset of tinnitus and central hearing impairment at a broad frequency range. The induced tinnitus and central hearing impairment tended to shift towards high frequencies over time. Hearing threshold measured with auditory brainstem responses also showed an immediate elevation followed by recovery on day 14, coinciding with behaviorally-measured results. Diffusion tensor magnetic resonance imaging results demonstrated significant damage and compensatory plastic changes to certain auditory brain regions, with the majority of changes occurring in the inferior colliculus and medial geniculate body. No significant microstructural changes found in the corpus callosum indicates that the currently adopted blast exposure mainly exerts effects through the auditory pathways rather than through direct impact onto the brain parenchyma. The results showed that this animal model is appropriate for investigation of the mechanisms underlying blast-induced tinnitus, hearing loss, and related TBI. Continued investigation along these lines will help identify pathology with injury/recovery patterns, aiding development of effective treatment strategies. PMID:21933015

The use of vibration monitoring to record the blasting works impact on buildings surrounding open-pit mines

NASA Astrophysics Data System (ADS)

Sołtys, Anna; Pyra, Józef; Winzer, Jan

2018-04-01

Environmental protection law and geological and mining law require the mineral mining plant to protect its surroundings from the effects of mining operations. This also applies to the negative impact of vibrations induced by blasting works on people and construction facilities. Effective protection is only possible if the level of this impact is known, therefore it is necessary to record it. The thesis formulated in this way has been and continues to be the guiding principle of the research works carried out in the AGH Laboratory of Blasting Work and Environmental Protection. As a result of these works are procedures for conducting preventive activities by open-pit mines in order to minimize the impact of blasting on facilities in the surrounding area. An important element of this activity is the monitoring of vibrations in constructions, which is a source of knowledge for excavation supervisors and engineers performing blasting works, thus contributing to raising the awareness of the responsible operation of the mining plant. Developed in the Laboratory of the Mine's Vibration Monitoring Station (KSMD), after several modernizations, it became a fully automated system for monitoring and recording the impact of blasting works on the surrounding environment. Currently, there are 30 measuring devices in 10 open-pit mines, and additional 8 devices are used to provide periodic measurement and recording services for the mines concerned.

What Dominates a Craters Size, the Largest Single Explosion of the Formation Process or the Cumulative Energy of Many? Results of Multiblast Crater Evolution Experiments

NASA Astrophysics Data System (ADS)

Sonder, I.; Graettinger, A. H.; Valentine, G. A.

2015-12-01

Craters of explosive volcanic eruptions are products of many explosions. Such craters are different than products of single events such as meteorite impacts or those produced by military testing because they typically result from multiple, rather than single, explosions. We analyzed the evolution of experimental craters that were created by several detonations of chemical explosives in layered aggregates. A method to calculate an effective explosion depth for non-flat topography (e.g. for explosions below existing craters) is derived, showing how multi-blast crater sizes differ from the single blast case. It is shown that sizes of natural caters (radii, volumes) are not characteristic of the number of explosions, and therefore not characteristic for the total acting energy, that formed a crater. Also the crater size is not simply related to the largest explosion in a sequence, but depends upon that explosion and the energy of that single blast and on the cumulative energy of all blasts that formed the crater. The two energies can be combined to form an effective number of explosions that is characteristic for the crater evolution. The multi-blast crater size evolution implies that it is not correct to estimate explosion energy of volcanic events from crater size using previously published relationships that were derived for single blast cases.

A helium burst biolistic device adapted to penetrate fragile insect tissues

PubMed Central

Thomas, Jean-Luc; Bardou, Jérôme; L'hoste, Sebastien; Mauchamp, Bernard; Chavancy, Gérard

2001-01-01

To compensate for the extremely low penetration efficiency of the original PDS/1000-He Bio Rad biolistic® device and the deleterious blast effect, design modifications have been made to the launching module. These modifications were evaluated on Bombyx mori embryos and fragile tissues, such as oocytes and imaginal wing disks. The original floppy macrocarrier was replaced by a rigid macrocarrier to avoid the effects of the helium blast. The efficiency of the gene gun bombardment was reinforced by the addition of a focusing nozzle. The reduced blast effect allowed us to carry out high-pressure shootings to small organs with improved penetration. This system allowed potentially all the internal embryonic tissues to be transfected with optimal survival rates. The new module was effective on tissues that are difficult to transfect, such as the epithelial wing disk that is covered by a peripodial membrane, and the ovarian follicle cells that lie under the ovariole cell membrane. The new macrocarrier allowed both an aqueous delivery of particles and an ethanolic dry delivery. No significant differences were noted between these two modes of delivery. The major improvement is the possibility of high pressure shooting correlated with appreciable penetration and a weak blast effect. PMID:15455069

Evaluation of observed blast loading effects on NIF x-ray diagnostic collimators.

PubMed

Masters, N D; Fisher, A; Kalantar, D; Prasad, R; Stölken, J S; Wlodarczyk, C

2014-11-01

We present the "debris wind" models used to estimate the impulsive load to which x-ray diagnostics and other structures are subject during National Ignition Facility experiments. These models are used as part of the engineering design process. Isotropic models, based on simulations or simplified "expanding shell" models, are augmented by debris wind multipliers to account for directional anisotropy. We present improvements to these multipliers based on measurements of the permanent deflections of diagnostic components: 4× for the polar direction and 2× within the equatorial plane-the latter relaxing the previous heuristic debris wind multiplier.

Evaluation of Grade 120 Granulated Ground blast Furnace Slag.

DOT National Transportation Integrated Search

1999-06-01

This study evaluates Grade 120 Granulated Ground Blast Furnace Slag (GGBFS) and its effect on the properties of hydraulic cement concretes used in structural and pavement construction. Several mix designs, structural and pavement, were used for this ...

A Multiscale Approach to Blast Neurotrauma Modeling: Part I – Development of Novel Test Devices for in vivo and in vitro Blast Injury Models

PubMed Central

Panzer, Matthew B.; Matthews, Kyle A.; Yu, Allen W.; Morrison, Barclay; Meaney, David F.; Bass, Cameron R.

2012-01-01

The loading conditions used in some current in vivo and in vitro blast-induced neurotrauma models may not be representative of real-world blast conditions. To address these limitations, we developed a compressed-gas driven shock tube with different driven lengths that can generate Friedlander-type blasts. The shock tube can generate overpressures up to 650 kPa with durations between 0.3 and 1.1 ms using compressed helium driver gas, and peak overpressures up to 450 kPa with durations between 0.6 and 3 ms using compressed nitrogen. This device is used for short-duration blast overpressure loading for small animal in vivo injury models, and contrasts the more frequently used long duration/high impulse blast overpressures in the literature. We also developed a new apparatus that is used with the shock tube to recreate the in vivo intracranial overpressure response for loading in vitro culture preparations. The receiver device surrounds the culture with materials of similar impedance to facilitate the propagation of a single overpressure pulse through the tissue. This method prevents pressure waves reflecting off the tissue that can cause unrealistic deformation and injury. The receiver performance was characterized using the longest helium-driven shock tube, and produced in-fluid overpressures up to 1500 kPa at the location where a culture would be placed. This response was well correlated with the overpressure conditions from the shock tube (R2 = 0.97). Finite element models of the shock tube and receiver were developed and validated to better elucidate the mechanics of this methodology. A demonstration exposing a culture to the loading conditions created by this system suggest tissue strains less than 5% for all pressure levels simulated, which was well below functional deficit thresholds for strain rates less than 50 s−1. This novel system is not limited to a specific type of culture model and can be modified to reproduce more complex pressure pulses. PMID:22470367

Blast biology: a study of the primary and tertiary effects of blast in open underground protective shelters. Project 33. 1 of Operation Plumbbob

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

Ricmond, D.R.; Taborelli, R.V.; Bowen, I.G.

1959-02-01

Dogs, pigs, rabbits, guinea pigs, and mice were exposed to nuclear detonations in two open underground partitioned shelters. The shelters were of similar construction, and each was exposed to separate detonations. Each inner chamber filled through its own orifice; thus four separate pressure environments were obtained. An aerodynamic mound was placed over the escape hatch of each structure to determine its effect on the pressure-curve shape inside the chamber. In one test a sieve plate bolted across the top of the mound was evaluated. Wind protective baffles of solid plate and of heavy wire screen were installed in the sheltersmore » to compare primary and tertiary blast effects on dogs. The shelters also contained static and dynamic pressure gages, radiation detectors, telemetering devices, and, in one test, air-temperature measuring instruments, dust-collecting trays, and eight pigs for the biological assessment of thermal effects. One dog was severely injured from tertiary blast effects associated with a maximal dynamic pressure (Q) of 10.5 psi, and one was undamaged with a maximal Q of 2 psi. Primary blast effects resulting from peak overpressures of 30.3, 25.5, 9.5, and 4.1 psi were minimal. The mortality was 19% of the mice exposed to a peak pressure of 30.3 psi and 5 and 3% of the guinea pigs and mice exposed to a peak pressure of 25.5 psi. Many of the rabbits, guinea pigs, and mice sustained slight lung hemorrhages at maximum pressues of 25.5 and 30.3 psi. Eardrum perforation data for all species, except mice, were recorded. Following shot 2, thermal effects were noted. Animals of the groups saved for observation have died from ionizing-radiation effects.« less

BLAST BIOLOGY--A STUDY OF THE PRIMARY AND TERTIARY EFFECTS OF BLAST IN OPEN UNDERGROUND PROTECTIVE SHELTERS

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

Ricmond, D.R.; Taborelli, R.V.; Bowen, I.G.

1959-02-01

Dogs, pigs, rabbits, guinea pigs, and mice were exposed to nuclear detonatiors in two open underground pantitioned shelters. The shelters were of similar constructions and each was exposed to separate detonations. Each inner chamber filled through its own orifice; thus four separate pressure enviromments were obtained. An aerodynamic mound was placed over the escape hatch of each structure to determine its effect on the pressurecurve shape inside the chamber. In one test a sieve plate bolted across the top of the mound was evaluated. Wind protective baffles of solid plate and of heavy wire screen were installed in the sheltersmore » to compare primary and tertiary blast effects on dogs. The shelters also contained static and dynamic pressure gages, radiation detectors, telemetering devices, and, in one test, air-temperature measuring instruments, dustcollecting trays, and eight pigs for the biological assessment of thermal effects. One dog was severely injured from tertiary blast effects associated with a maximal dynamic pressure (Q) of 10.5 psi, and one was undamaged with a maximal Q of 2 psi. Primary blast effects resulting from peak overpressures of 30.3, 25.5, 9.5. and 4.1 psi were minimal. The mortality was 19 per cent of the mice exposed to a peak pressure of 30.3 psi and 5 and 3 per cent of the guinea pigs and mice exposed to a peak pressure of 25.5 psi. Many of the rabbits, guinea pigs, and mice sustained slight lung hemorrhages at maximum pressures of 25.5 and 30.3 psi. Eardrum perforation data for all species, except mice, were recorded. Following shot 2, thermal effects were noted. Animals of the groups saved for observation have died from ionizing-radiation effects. (auth)« less

Investigation of Ballistic Penetration through Tibia Soft Tissue Simulant

NASA Astrophysics Data System (ADS)

Nguyen, Thuy-Tien N.; Masouros, Spyros D.; Tear, Gareth R.; Proud, William G.; Institute of Shock Physics; CentreBlast Injury Studies, Imperial College London, UK Team

2017-06-01

High energy trauma events such as from explosions and ballistic weapons can cause severe damage to the human body. The resulting injuries are very complex and their mechanism is not fully understood. Secondary blast injuries, effectively ballistic traumas, to the extremities are commonly reported, especially to the tibia. The aim of this study is to quantify the effect of parameters such as projectile mass and velocity, and impact location on injury thresholds in the leg. The bones of the leg were set in biofidelic gelatin tissue simulant. A 32-mm-bore gas gun was used to launch a sabot carrying a carbon steel projectile 0.5 to 1.1 g in mass at the sample with speeds of 50 to 300 m/s. Penetration depth and impact velocity were recorded. The effect of different postures - such as standing and non-weight bearing -- on injury were considered. The resulting injuries were scored clinically and their correlation with the various impact parameters was calculated. The project is funded by the Royal British Legion, United Kingdom.

Modification of surface morphology of Ti6Al4V alloy manufactured by Laser Sintering

NASA Astrophysics Data System (ADS)

Draganovská, Dagmar; Ižariková, Gabriela; Guzanová, Anna; Brezinová, Janette; Koncz, Juraj

2016-06-01

The paper deals with the evaluation of relation between roughness parameters of Ti6Al4V alloy produced by DMLS and modified by abrasive blasting. There were two types of blasting abrasives that were used - white corundum and Zirblast at three levels of air pressure. The effect of pressure on the value of individual roughness parameters and an influence of blasting media on the parameters for samples blasted by white corundum and Zirblast were evaluated by ANOVA. Based on the measured values, the correlation matrix was set and the standard of correlation statistic importance between the monitored parameters was determined from it. The correlation coefficient was also set.

Intrathoracic pressure variations in an anthropomorphic dummy exposed to air blast, blunt impact, and missiles.

PubMed

Jönsson, A; Arvebo, E; Schantz, B

1988-01-01

Experiments with an anthropomorphic dummy for blast research demonstrated that pressures recorded in the lung model of the dummy could be correlated to primary air blast effects on the lungs of experimental animals. The results presented here were obtained with a dummy of the type mentioned above, but with the lung model modified to improve geometric similarity to man. Blast experiments were performed in a shock tube, and impact experiments in a special impact machine. Experiments with nonpenetrating missiles were performed with small-caliber firearms and the dummy protected by body armor. Severity indices derived from the blast experiments were related to established criteria for primary lung injury in man. Impacts delivered in the impact machine and by nonpenetrating missiles are compared. Relationships between severity of impact based on experiments with animals and primary lung injury in man are discussed.

Post-blasting seismicity in Rudna copper mine, Poland - source parameters analysis.

NASA Astrophysics Data System (ADS)

Caputa, Alicja; Rudziński, Łukasz; Talaga, Adam

2017-04-01

The really important hazard in Polish copper mines is high seismicity and corresponding rockbursts. Many methods are used to reduce the seismic hazard. Among others the most effective is preventing blasting in potentially hazardous mining panels. The method is expected to provoke small moderate tremors (up to M2.0) and reduce in this way a stress accumulation in the rockmass. This work presents an analysis, which deals with post-blasting events in Rudna copper mine, Poland. Using the Full Moment Tensor (MT) inversion and seismic spectra analysis, we try to find some characteristic features of post blasting seismic sources. Source parameters estimated for post-blasting events are compared with the parameters of not-provoked mining events that occurred in the vicinity of the provoked sources. Our studies show that focal mechanisms of events which occurred after blasts have similar MT decompositions, namely are characterized by a quite strong isotropic component as compared with the isotropic component of not-provoked events. Also source parameters obtained from spectral analysis show that provoked seismicity has a specific source physics. Among others, it is visible from S to P wave energy ratio, which is higher for not-provoked events. The comparison of all our results reveals a three possible groups of sources: a) occurred just after blasts, b) occurred from 5min to 24h after blasts and c) not-provoked seismicity (more than 24h after blasting). Acknowledgements: This work was supported within statutory activities No3841/E-41/S/2016 of Ministry of Science and Higher Education of Poland.

Optical Property Enhancement and Durability Evaluation of Heat Receiver Aperture Shield Materials

NASA Technical Reports Server (NTRS)

deGroh, Kim K.; Jaworske, Donald A.; Smith, Daniela C.

1998-01-01

Under the Solar Dynamic Flight Demonstration (SDFD) program, NASA Lewis Research Center worked with AlliedSignal Aerospace, the heat receiver contractor, on the development, characterization and durability testing of refractory metals to obtain appropriate optical and thermal properties for the SDFD heat receiver aperture shield. Molybdenum and tungsten foils were grit-blasted using silicon carbide or alumina grit under various grit-blasting conditions for optical property enhancement. Black rhenium coated tungsten foil was also evaluated. Tungsten, black rhenium-coated tungsten, and grit-blasted tungsten screens of various mesh sizes were placed over the pristine and grit-blasted foils for optical property characterization. Grit-blasting was found to be effective in decreasing the specular reflectance and the absorptance/emittance ratio of the refractory foils. The placement of a screen further enhanced these optical properties, with a grit-blasted screen over a grit-blasted foil producing the best results. Based on the optical property enhancement results, samples were tested for atomic oxygen and vacuum heat treatment durability. Grit-blasted (Al2O3 grit) 2 mil tungsten foil was chosen for the exterior layer of the SDFD heat receiver aperture shield. A 0.007 in. wire diameter, 20 x 20 mesh tungsten screen was chosen to cover the tungsten foil. Based on these test results, a heat receiver aperture shield test unit has been built with the screen covered grit-blast tungsten foil exterior layers. The aperture shield was tested and verified the thermal and structural durability of the outer foil layers during an off-pointing period.

Can 10% hydrofluoric acid be used for reconditioning of orthodontic brackets?

PubMed

Pompeo, Daniela D; Rosário, Henrique D; Lopes, Beatriz Mv; Cesar, Paulo F; Paranhos, Luiz Renato

2016-01-01

Bracket debonding is a common problem during orthodontic treatment. This type of failure is associated to masticatory forces, poor adhesion, and the need for repositioning the piece. The objective of this work was to compare the shear bond strength of debonded brackets that were reconditioned using different protocols (alumina blasting versus hydrofluoric etching). This was an in vitro experimental study with 45 stainless steel orthodontic brackets. They were randomly divided into three groups: (1) New brackets (n = 15), (2) brackets reconditioned using 10% hydrofluoric acid for 60 s (n = 15), and (3) brackets reconditioned by aluminum oxide blasting until complete removal of the remaining resin (n = 15). In Groups 2 and 3, the insertion of composite resin proceeded in two stages to simulate a type of bracket failure in which the bonding resin was left at the bracket base. For the shear test, the assembly composed by the metallic support, and specimen was taken to the Instron universal testing machine in which the specimens were loaded using a semicircle-shaped active tip in the region of the bonding interface parallel to the surface of the bracket at a speed of 0.5 mm/min. The data were subjected to D'Agostino's normality test to have their distribution checked. Analysis of variance and Tukey's test (P < 0.01) were used to compare the findings between groups. The results indicated that Group 1 (new brackets) showed higher bond strength than that obtained for the group treated with hydrofluoric acid (Group 2, P < 0.01). The bond strength value obtained for the group treated with alumina blasting (Group 3) was statistically similar to those obtained for Groups 1 and 2. The aluminum oxide blasting technique was effective for the reconditioning of orthodontic brackets. Nevertheless, the reconditioning technique using 10% fluoridric acid for 60 s was not efficient for clinical use.

LAD Early Career Prize Talk:Laboratory astrophysics experiments investigating the effects of high energy fluxes on Rayleigh-Taylor instability growth relevant to young supernova remnants

NASA Astrophysics Data System (ADS)

Kuranz, Carolyn C.; Drake, R. Paul; Park, Hye Sook; Huntington, Channing; Miles, Aaron R.; Remington, Bruce A.; Plewa, Tomek; Trantham, Matt; Shvarts, Dov; Raman, Kumar; MacLaren, Steven; Wan, Wesley; Doss, Forrest; Kline, John; Flippos, Kirk; Malamud, Guy; Handy, Timothy; Prisbey, Shon; Grosskopf, Michael; Krauland, Christine; Klein, Sallee; Harding, Eric; Wallace, Russell; Marion, Donna; Kalantar, Dan

2017-06-01

Energy-transport effects can alter the structure that develops as a supernova evolves into a supernova remnant. The Rayleigh Taylor (RT) instability is thought to produce structure at the interface between the stellar ejecta and the circumstellar matter (CSM), based on simple models and hydrodynamic simulations. When a blast wave emerges from an exploding star, it drives a forward shock into the CSM and a reverse shock forms in the expanding stellar ejecta, creating a young supernova remnant (SNR). As mass accumulates in the shocked layers, the interface between these two shocks decelerates, becoming unstable to the RT instability. Simulations predict that RT produces structures at this interface, having a range of spatial scales. When the CSM is dense enough, as in the case of SN 1993J, the hot shocked matter can produce significant radiative fluxes that affect the emission from the SNR. Here we report experimental results from the National Ignition Facility (NIF) to explore how large energy fluxes, which are present in supernovae such as SN 1993J, might affect this structure. The experiment used NIF to create a RT unstable interface subject to a high energy flux by the emergence of a blast wave into lower-density matter, in analogy to the SNR. We also preformed and with a low energy flux to compare the affect of the energy flux on the instability growth. We found that the RT growth was reduced in the experiments with a high energy flux. In analyzing the comparison with SN 1993J, we discovered that the energy fluxes produced by heat conduction appear to be larger than the radiative energy fluxes, and large enough to have dramatic consequences. No reported astrophysical simulations have included radiation and heat conduction self-consistently in modeling SNRs.

Quick reproduction of blast-wave flow-field properties of nuclear, TNT, and ANFO explosions

NASA Astrophysics Data System (ADS)

Groth, C. P. T.

1986-04-01

In many instances, extensive blast-wave flow-field properties are required in gasdynamics research studies of blast-wave loading and structure response, and in evaluating the effects of explosions on their environment. This report provides a very useful computer code, which can be used in conjunction with the DNA Nuclear Blast Standard subroutines and code, to quickly reconstruct complete and fairly accurate blast-wave data for almost any free-air (spherical) and surface-burst (hemispherical) nuclear, trinitrotoluene (TNT), or ammonium nitrate-fuel oil (ANFO) explosion. This code is capable of computing all of the main flow properties as functions of radius and time, as well as providing additional information regarding air viscosity, reflected shock-wave properties, and the initial decay of the flow properties just behind the shock front. Both spatial and temporal distributions of the major blast-wave flow properties are also made readily available. Finally, provisions are also included in the code to provide additional information regarding the peak or shock-front flow properties over a range of radii, for a specific explosion of interest.

Investigations of Tissue-Level Mechanisms of Primary Blast Injury Through Modeling, Simulation, Neuroimaging and Neuropathological Studies

DTIC Science & Technology

2012-07-10

materials used, the complexity of the human anatomy , manufacturing limitations, and analysis capability prohibits exactly matching surrogate material...upper and lower bounds for possible loading behaviour. Although it is impossible to exactly match the human anatomy according to mechanical

Simulation of blast action on civil structures using ANSYS Autodyn

NASA Astrophysics Data System (ADS)

Fedorova, N. N.; Valger, S. A.; Fedorov, A. V.

2016-10-01

The paper presents the results of 3D numerical simulations of shock wave spreading in cityscape area. ANSYS Autodyne software is used for the computations. Different test cases are investigated numerically. On the basis of the computations, the complex transient flowfield structure formed in the vicinity of prismatic bodies was obtained and analyzed. The simulation results have been compared to the experimental data. The ability of two numerical schemes is studied to correctly predict the pressure history in several gauges placed on walls of the obstacles.

Mitigation of explosions of hydrogen-air mixtures using bulk materials and aqueous foam

NASA Astrophysics Data System (ADS)

Medvedev, S. P.; Khomik, S. V.; Mikhalkin, V. N.; Ivantsov, A. N.; Agafonov, G. L.; Cherepanov, A. A.; Cherepanova, T. T.; Betev, A. S.

2018-01-01

The objective of this work is to determine experimentally the effectiveness of protective barriers under conditions when blast waves are generated during premixed hydrogen- air combustion in various regimes. Experiments are conducted in a vertical tube having a diameter of 54 mm and a length of up to 2 m. Blast loads are produced by acceleration of premixed hydrogen-air flames in the tube with ring obstacles. Comparative tests are performed between protection barriers made of bulk materials with different densities and aqueous foams with different expansion ratios. It is demonstrated that the degree of blast load attenuation by an aqueous foam barrier increases with decreasing molecular weight of the filling gas and increasing density (decreasing expansion ratio) of the foam. An Aerosil barrier three times thicker than a titanium-dioxide one is found to have a similar attenuating effect on blast action. However, the mass per unit area of an Aerosil barrier is lower than titanium dioxide by a factor of 6 and is comparable to foam. The observed dependence of blast load attenuation on parameters of bulk materials and aqueous foams must be taken into account in systems designed to mitigate the consequences of accidental hydrogen release and combustion.

Modeling of damage, permeability changes and pressure responses during excavation of the TSX tunnel in granitic rock at URL, Canada

NASA Astrophysics Data System (ADS)

Rutqvist, Jonny; Börgesson, Lennart; Chijimatsu, Masakazu; Hernelind, Jan; Jing, Lanru; Kobayashi, Akira; Nguyen, Son

2009-05-01

This paper presents numerical modeling of excavation-induced damage, permeability changes, and fluid-pressure responses during excavation of a test tunnel associated with the tunnel sealing experiment (TSX) at the Underground Research Laboratory (URL) in Canada. Four different numerical models were applied using a wide range of approaches to model damage and permeability changes in the excavation disturbed zone (EDZ) around the tunnel. Using in situ calibration of model parameters, the modeling could reproduce observed spatial distribution of damage and permeability changes around the tunnel as a combination of disturbance induced by stress redistribution around the tunnel and by the drill-and-blast operation. The modeling showed that stress-induced permeability increase above the tunnel is a result of micro and macrofracturing under high deviatoric (shear) stress, whereas permeability increase alongside the tunnel is a result of opening of existing microfractures under decreased mean stress. The remaining observed fracturing and permeability changes around the periphery of the tunnel were attributed to damage from the drill-and-blast operation. Moreover, a reasonably good agreement was achieved between simulated and observed excavation-induced pressure responses around the TSX tunnel for 1 year following its excavation. The simulations showed that these pressure responses are caused by poroelastic effects as a result of increasing or decreasing mean stress, with corresponding contraction or expansion of the pore volume. The simulation results for pressure evolution were consistent with previous studies, indicating that the observed pressure responses could be captured in a Biot model using a relatively low Biot-Willis’ coefficient, α ≈ 0.2, a porosity of n ≈ 0.007, and a relatively low permeability of k ≈ 2 × 10-22 m2, which is consistent with the very tight, unfractured granite at the site.

A Set of Blast Marks in Color, Right Side

NASA Image and Video Library

2012-08-09

This cut-out from a color panorama image taken by NASA Curiosity rover shows the effects of the descent stage rocket engines blasting the ground. It comes from the right side of the thumbnail panorama obtained the Mast Camera.

A Set of Blast Marks in Color, Left Side

NASA Image and Video Library

2012-08-09

This cut-out from a color panorama image taken by NASA Curiosity rover shows the effects of the descent stage rocket engines blasting the ground. It comes from the left side of the thumbnail panorama obtained by Curiosity Mast Camera.

Numerical investigation of particle-blast interaction during explosive dispersal of liquids and granular materials

NASA Astrophysics Data System (ADS)

Pontalier, Q.; Lhoumeau, M.; Milne, A. M.; Longbottom, A. W.; Frost, D. L.

2018-05-01

Experiments show that when a high-explosive charge with embedded particles or a charge surrounded by a layer of liquid or granular material is detonated, the flow generated is perturbed by the motion of the particles and the blast wave profile differs from that of an ideal Friedlander form. Initially, the blast wave overpressure is reduced due to the energy dissipation resulting from compaction, fragmentation, and heating of the particle bed, and acceleration of the material. However, as the blast wave propagates, particle-flow interactions collectively serve to reduce the rate of decay of the peak blast wave overpressure. Computations carried out with a multiphase hydrocode reproduce the general trends observed experimentally and highlight the transition between the particle acceleration/deceleration phases, which is not accessible experimentally, since the particles are obscured by the detonation products. The dependence of the particle-blast interaction and the blast mitigation effectiveness on the mitigant to explosive mass ratio, the particle size, and the initial solid volume fraction is investigated systematically. The reduction in peak blast overpressure is, as in experiments, primarily dependent on the mass ratio of material to explosive, with the particle size, density, and initial porosity of the particle bed playing secondary roles. In the near field, the blast overpressure decreases sharply with distance as the particles are accelerated by the flow. When the particles decelerate due to drag, energy is returned to the flow and the peak blast overpressure recovers and reaches values similar to that of a bare explosive charge for low mass ratios. Time-distance trajectory plots of the particle and blast wave motion with the pressure field superimposed, illustrate the weak pressure waves generated by the motion of the particle layer which travel upstream and perturb the blast wave motion. Computation of the particle and gas momentum flux in the multiphase flow generated during explosive particle dispersal indicates that the particle momentum flux is the dominant term in the near field. Both the gas and particle loading must be taken into account when determining the damage to nearby structures following the detonation of a high-explosive charge surrounded by a material layer.

Blast waves from detonated military explosive reduce GluR1 and synaptophysin levels in hippocampal slice cultures✩

PubMed Central

Smith, Marquitta; Piehler, Thuvan; Benjamin, Richard; Farizatto, Karen L.; Pait, Morgan C.; Almeida, Michael F.; Ghukasyan, Vladimir V.; Bahr, Ben A.

2017-01-01

Explosives create shockwaves that cause blast-induced neurotrauma, one of the most common types of traumatic brain injury (TBI) linked to military service. Blast-induced TBIs are often associated with reduced cognitive and behavioral functions due to a variety of factors. To study the direct effects of military explosive blasts on brain tissue, we removed systemic factors by utilizing rat hippocampal slice cultures. The long-term slice cultures were briefly sealed air-tight in serum-free medium, lowered into a 37 °C water-filled tank, and small 1.7-gram assemblies of cyclotrimethylene trinitramine (RDX) were detonated 15 cm outside the tank, creating a distinct shockwave recorded at the culture plate position. Compared to control mock-treated groups of slices that received equal submerge time, 1–3 blast impacts caused a dose-dependent reduction in the AMPA receptor subunit GluR1. While only a small reduction was found in hippocampal slices exposed to a single RDX blast and harvested 1–2 days later, slices that received two consecutive RDX blasts 4 min apart exhibited a 26–40% reduction in GluR1, and the receptor subunit was further reduced by 64–72% after three consecutive blasts. Such loss correlated with increased levels of HDAC2, a histone deacetylase implicated in stress-induced reduction of glutamatergic transmission. No evidence of synaptic marker recovery was found at 72 h post-blast. The presynaptic marker synaptophysin was found to have similar susceptibility as GluR1 to the multiple explosive detonations. In contrast to the synaptic protein reductions, actin levels were unchanged, spectrin breakdown was not detected, and Fluoro-Jade B staining found no indication of degenerating neurons in slices exposed to three RDX blasts, suggesting that small, sub-lethal explosives are capable of producing selective alterations to synaptic integrity. Together, these results indicate that blast waves from military explosive cause signs of synaptic compromise without producing severe neurodegeneration, perhaps explaining the cognitive and behavioral changes in those blast-induced TBI sufferers that have no detectable neuropathology. PMID:27720798

Numerical investigation of particle-blast interaction during explosive dispersal of liquids and granular materials

NASA Astrophysics Data System (ADS)

Pontalier, Q.; Lhoumeau, M.; Milne, A. M.; Longbottom, A. W.; Frost, D. L.

2018-04-01

Experiments show that when a high-explosive charge with embedded particles or a charge surrounded by a layer of liquid or granular material is detonated, the flow generated is perturbed by the motion of the particles and the blast wave profile differs from that of an ideal Friedlander form. Initially, the blast wave overpressure is reduced due to the energy dissipation resulting from compaction, fragmentation, and heating of the particle bed, and acceleration of the material. However, as the blast wave propagates, particle-flow interactions collectively serve to reduce the rate of decay of the peak blast wave overpressure. Computations carried out with a multiphase hydrocode reproduce the general trends observed experimentally and highlight the transition between the particle acceleration/deceleration phases, which is not accessible experimentally, since the particles are obscured by the detonation products. The dependence of the particle-blast interaction and the blast mitigation effectiveness on the mitigant to explosive mass ratio, the particle size, and the initial solid volume fraction is investigated systematically. The reduction in peak blast overpressure is, as in experiments, primarily dependent on the mass ratio of material to explosive, with the particle size, density, and initial porosity of the particle bed playing secondary roles. In the near field, the blast overpressure decreases sharply with distance as the particles are accelerated by the flow. When the particles decelerate due to drag, energy is returned to the flow and the peak blast overpressure recovers and reaches values similar to that of a bare explosive charge for low mass ratios. Time-distance trajectory plots of the particle and blast wave motion with the pressure field superimposed, illustrate the weak pressure waves generated by the motion of the particle layer which travel upstream and perturb the blast wave motion. Computation of the particle and gas momentum flux in the multiphase flow generated during explosive particle dispersal indicates that the particle momentum flux is the dominant term in the near field. Both the gas and particle loading must be taken into account when determining the damage to nearby structures following the detonation of a high-explosive charge surrounded by a material layer.

Combined Effects of Primary and Tertiary Blast on Rat Brain: Characterization of a Model of Blast-induced Mild Traumatic Brain Injury

DTIC Science & Technology

2014-03-01

military environments, affected in- dividuals (e.g. football players) often sustain additional mild injuries. mTBI symptoms are typically mild and... concussion andmild traumatic brain injury. PM R 3, S354–358; DOI:10.1016/j.pmrj.2011.07.017 (2011). 2. Hendricks, A. M. et al. Screening for mild traumatic...Mendez, M. F. et al. Mild traumatic brain injury from primary blast vs. blunt forces: post- concussion consequences and functional neuroimaging

Evaluating the Effectiveness of Various Blast Loading Descriptors as Occupant Injury Predictors for Underbody Blast Events

DTIC Science & Technology

2014-01-09

of Hybrid III ATD LSDYNA model with FTSS v7.1.6 finite element dummy 6 Unclassified: Distribution Statement A. Approved for public release...descriptors as occupant injury predictors for underbody blast events Recording injury metrics Response from the dummy especially pelvic acceleration and...Ciip(H&ad CG,2) "’"’ "-......--------, I Max : 122.669 @59.81 7!; Time, ms Pelvic Z acceleration, g I I Clip: -4.75737 Ts:97.4138 Te: 104.414

A Finite Difference Numerical Model for the Propagation of Finite Amplitude Acoustical Blast Waves Outdoors Over Hard and Porous Surfaces

DTIC Science & Technology

1991-09-01

Difference Numerical Model for the Propagation of Finite Amplitude Acoustical Blast Waves Outdoors Over Hard and Porous Surfaces by Victor W. Sparrow...The nonlinear acoustic propagation effects require a numerical solution in the time domain. To model a porous ground surface, which in the frequency...incident on the hard and porous surfaces were produced. The model predicted that near grazing finite amplitude acoustic blast waves decay with distance

Cloning of novel rice blast resistance genes from two rapidly evolving NBS-LRR gene families in rice.

PubMed

Guo, Changjiang; Sun, Xiaoguang; Chen, Xiao; Yang, Sihai; Li, Jing; Wang, Long; Zhang, Xiaohui

2016-01-01

Most rice blast resistance genes (R-genes) encode proteins with nucleotide-binding site (NBS) and leucine-rich repeat (LRR) domains. Our previous study has shown that more rice blast R-genes can be cloned in rapidly evolving NBS-LRR gene families. In the present study, two rapidly evolving R-gene families in rice were selected for cloning a subset of genes from their paralogs in three resistant rice lines. A total of eight functional blast R-genes were identified among nine NBS-LRR genes, and some of these showed resistance to three or more blast strains. Evolutionary analysis indicated that high nucleotide diversity of coding regions served as important parameters in the determination of gene resistance. We also observed that amino-acid variants (nonsynonymous mutations, insertions, or deletions) in essential motifs of the NBS domain contribute to the blast resistance capacity of NBS-LRR genes. These results suggested that the NBS regions might also play an important role in resistance specificity determination. On the other hand, different splicing patterns of introns were commonly observed in R-genes. The results of the present study contribute to improving the effectiveness of R-gene identification by using evolutionary analysis method and acquisition of novel blast resistance genes.

Characterization of Viscoelastic Materials for Low-Magnitude Blast Mitigation

NASA Astrophysics Data System (ADS)

Bartyczak, Susan; Mock, Willis

2013-06-01

Recent preliminary research indicates that exposure to low amplitude blast waves, such as from IED detonation or multiple firings of a weapon, causes damage to brain tissue resulting in Traumatic Brain Injury (TBI) and Post Traumatic Stress Disorder (PTSD). Current combat helmets are not sufficiently protecting warfighters from this danger and the effects are debilitating, costly, and long-lasting. The objective of this research is to evaluate the blast mitigating behavior of current helmet materials and new materials designed for blast mitigation using a test fixture recently developed at the Naval Surface Warfare Center Dahlgren Division for use with an existing gas gun. A 40-mm-bore gas gun is used as a shock tube to generate blast waves (ranging from 5 to 30 psi) in a test fixture mounted at the gun muzzle. A fast opening valve is used to release helium gas from a breech which forms into a blast wave and impacts instrumented targets in the test fixture. Blast attenuation of selected materials is determined through the measurement of pressure and accelerometer data in front of and behind the target. Materials evaluated in this research include 6061-T6 aluminum, polyurea 1000, Styrofoam, and Sorbothane (durometer 50, shore 00). The experimental technique, calibration and checkout procedures, and results will be presented.

From painkiller to empathy killer: acetaminophen (paracetamol) reduces empathy for pain

PubMed Central

Crocker, Jennifer; Way, Baldwin M.

2016-01-01

Simulation theories of empathy hypothesize that empathizing with others’ pain shares some common psychological computations with the processing of one’s own pain. Support for this perspective has largely relied on functional neuroimaging evidence of an overlap between activations during the experience of physical pain and empathy for other people’s pain. Here, we extend the functional overlap perspective to the neurochemical level and test whether a common physical painkiller, acetaminophen (paracetamol), can reduce empathy for another’s pain. In two double-blind placebo-controlled experiments, participants rated perceived pain, personal distress and empathic concern in response to reading scenarios about another's physical or social pain, witnessing ostracism in the lab, or visualizing another study participant receiving painful noise blasts. As hypothesized, acetaminophen reduced empathy in response to others’ pain. Acetaminophen also reduced the unpleasantness of noise blasts delivered to the participant, which mediated acetaminophen's effects on empathy. Together, these findings suggest that the physical painkiller acetaminophen reduces empathy for pain and provide a new perspective on the neurochemical bases of empathy. Because empathy regulates prosocial and antisocial behavior, these drug-induced reductions in empathy raise concerns about the broader social side effects of acetaminophen, which is taken by almost a quarter of adults in the United States each week. PMID:27217114

On the neutralization of bacterial spores in post-detonation flows

NASA Astrophysics Data System (ADS)

Gottiparthi, K. C.; Schulz, J. C.; Menon, S.

2014-09-01

In multiple operational scenarios, explosive charges are used to neutralize confined or unconfined stores of bacterial spores. The spore destruction is achieved by post-detonation combustion and mixing of hot detonation product gases with the ambient flow and spore clouds. In this work, blast wave interaction with bacterial spore clouds and the effect of post-detonation combustion on spore neutralization are investigated using numerical simulations. Spherical explosive charges (radius, = 5.9 cm) comprising of nitromethane are modeled in the vicinity of a spore cloud, and the spore kill in the post-detonation flow is quantified. The effect of the mass of the spores and the initial distance, , of the spore cloud from the explosive charge on the percentage of spores neutralized is investigated. When the spores are initially placed within a distance of 3.0, within 0.1 ms after detonation of the charge, all the spores are neutralized by the blast wave and the hot detonation product gases. In contrast, almost all the spores survived the explosion when is greater than 8.0. The percentage of intact spores varied from 0 to 100 for 3.0 8.0 with spore neutralization dependent on time spent by the spores in the post-detonation mixing/combustion zone.

Numerical simulation of the fluid-structure interaction between air blast waves and soil structure

NASA Astrophysics Data System (ADS)

Umar, S.; Risby, M. S.; Albert, A. Luthfi; Norazman, M.; Ariffin, I.; Alias, Y. Muhamad

2014-03-01

Normally, an explosion threat on free field especially from high explosives is very dangerous due to the ground shocks generated that have high impulsive load. Nowadays, explosion threats do not only occur in the battlefield, but also in industries and urban areas. In industries such as oil and gas, explosion threats may occur on logistic transportation, maintenance, production, and distribution pipeline that are located underground to supply crude oil. Therefore, the appropriate blast resistances are a priority requirement that can be obtained through an assessment on the structural response, material strength and impact pattern of material due to ground shock. A highly impulsive load from ground shocks is a dynamic load due to its loading time which is faster than ground response time. Of late, almost all blast studies consider and analyze the ground shock in the fluid-structure interaction (FSI) because of its influence on the propagation and interaction of ground shock. Furthermore, analysis in the FSI integrates action of ground shock and reaction of ground on calculations of velocity, pressure and force. Therefore, this integration of the FSI has the capability to deliver the ground shock analysis on simulation to be closer to experimental investigation results. In this study, the FSI was implemented on AUTODYN computer code by using Euler-Godunov and the arbitrary Lagrangian-Eulerian (ALE). Euler-Godunov has the capability to deliver a structural computation on a 3D analysis, while ALE delivers an arbitrary calculation that is appropriate for a FSI analysis. In addition, ALE scheme delivers fine approach on little deformation analysis with an arbitrary motion, while the Euler-Godunov scheme delivers fine approach on a large deformation analysis. An integrated scheme based on Euler-Godunov and the arbitrary Lagrangian-Eulerian allows us to analyze the blast propagation waves and structural interaction simultaneously.

Micro-scale pollution mechanism of dust diffusion in a blasting driving face based on CFD-DEM coupled model.

PubMed

Yu, Haiming; Cheng, Weimin; Xie, Yao; Peng, Huitian

2018-05-23

In order to investigate the diffuse pollution mechanisms of high-concentration dusts in the blasting driving face, the airflow-dust coupled model was constructed based on CFD-DEM coupled model; the diffusion rules of the dusts with different diameters at microscopic scale were analyzed in combination with the field measured results. The simulation results demonstrate that single-exhaust ventilation exhibited more favorable dust suppression performance than single-forced ventilation. Under single-exhaust ventilation condition, the motion trajectories of the dusts with the diameter smaller than 20 μm were close to the airflow streamline and these dusts were mainly distributed near the footway walls; by contrast, under single-forced ventilation condition, the motion trajectories of the dust particles with a diameter range of 20~40 μm were close to the airflow streamlines, and a large number of dusts with the diameter smaller than 20 μm accumulated in the regions 5 m and 17~25 m away from the head-on section. Moreover, under the single-exhaust ventilation, the relationship between dust diameter D and negative-pressured-induced dust emission ratio P can be expressed as P = - 25.03ln(D) + 110.39, and the dust emission ratio was up to 74.36% for 7-μm dusts, and the path-dependent settling behaviors of the dusts mainly occurred around the head-on section; under single-forced ventilation condition, the z value of the dusts with the diameter over 20 μm decreased and the dusts with a diameter smaller than 7 μm are particularly harmful to human health, but their settling ratios were below 22.36%. Graphical abstract The airflow-dust CFD-DEM coupling model was established. The numerical simulation results were verified. The migration laws of airflow field were obtained in a blasting driving face. The diffusion laws of dusts were obtained after blasting.

A Numerical Study on the Screening of Blast-Induced Waves for Reducing Ground Vibration

NASA Astrophysics Data System (ADS)

Park, Dohyun; Jeon, Byungkyu; Jeon, Seokwon

2009-06-01

Blasting is often a necessary part of mining and construction operations, and is the most cost-effective way to break rock, but blasting generates both noise and ground vibration. In urban areas, noise and vibration have an environmental impact, and cause structural damage to nearby structures. Various wave-screening methods have been used for many years to reduce blast-induced ground vibration. However, these methods have not been quantitatively studied for their reduction effect of ground vibration. The present study focused on the quantitative assessment of the effectiveness in vibration reduction of line-drilling as a screening method using a numerical method. Two numerical methods were used to analyze the reduction effect toward ground vibration, namely, the “distinct element method” and the “non-linear hydrocode.” The distinct element method, by particle flow code in two dimensions (PFC 2D), was used for two-dimensional parametric analyses, and some cases of two-dimensional analyses were analyzed three-dimensionally using AUTODYN 3D, the program of the non-linear hydrocode. To analyze the screening effectiveness of line-drilling, parametric analyses were carried out under various conditions, with the spacing, diameter of drill holes, distance between the blasthole and line-drilling, and the number of rows of drill holes, including their arrangement, used as parameters. The screening effectiveness was assessed via a comparison of the vibration amplitude between cases both with and without screening. Also, the frequency distribution of ground motion of the two cases was investigated through fast Fourier transform (FFT), with the differences also examined. From our study, it was concluded that line-drilling as a screening method of blast-induced waves was considerably effective under certain design conditions. The design details for field application have also been proposed.

Nondestructive Evaluation and Underwater Repair of Composite Structures

DTIC Science & Technology

2008-06-01

virtually required with coatings in excess of 200 mm because of magnetic field losses [31]. This method has been effectively used in the underwater...Environmental Effects 42 flexural and fatigue degradation under saturated conditions, 0.6% weight [53]. Figure 14, shows the difference between saturated and...blasting and grit blasting plus chemical etching have the most pronounced effects , achieving nearly 60% relative to the highest achieved value [30, 71

Emergency War Surgery: Third United States Revision

DTIC Science & Technology

2004-01-01

FOREWORD xxi PREFACE xxiii PROLOGUE xxvii Chapter 1 : Weapons Effects and Parachute Injuries Epidemiology 1.1 Mechanism of Injury 1.2 Antipersonnel...Ed. Lounsbury, MD Colonel, Medical Corps October, 2004 Washington, DC Approved for Public Release 1.1 Weapons Effects and Parachute Injuries Chapter 1 ...ft/s (600 m/s). Unlike small arms, explosive munitions cause multiple wounds. Blast (see Fig. 1 -2). ο The blast effects take place relatively close

Development of Rock Engineering Systems-Based Models for Flyrock Risk Analysis and Prediction of Flyrock Distance in Surface Blasting

NASA Astrophysics Data System (ADS)

Faramarzi, Farhad; Mansouri, Hamid; Farsangi, Mohammad Ali Ebrahimi

2014-07-01

The environmental effects of blasting must be controlled in order to comply with regulatory limits. Because of safety concerns and risk of damage to infrastructures, equipment, and property, and also having a good fragmentation, flyrock control is crucial in blasting operations. If measures to decrease flyrock are taken, then the flyrock distance would be limited, and, in return, the risk of damage can be reduced or eliminated. This paper deals with modeling the level of risk associated with flyrock and, also, flyrock distance prediction based on the rock engineering systems (RES) methodology. In the proposed models, 13 effective parameters on flyrock due to blasting are considered as inputs, and the flyrock distance and associated level of risks as outputs. In selecting input data, the simplicity of measuring input data was taken into account as well. The data for 47 blasts, carried out at the Sungun copper mine, western Iran, were used to predict the level of risk and flyrock distance corresponding to each blast. The obtained results showed that, for the 47 blasts carried out at the Sungun copper mine, the level of estimated risks are mostly in accordance with the measured flyrock distances. Furthermore, a comparison was made between the results of the flyrock distance predictive RES-based model, the multivariate regression analysis model (MVRM), and, also, the dimensional analysis model. For the RES-based model, R 2 and root mean square error (RMSE) are equal to 0.86 and 10.01, respectively, whereas for the MVRM and dimensional analysis, R 2 and RMSE are equal to (0.84 and 12.20) and (0.76 and 13.75), respectively. These achievements confirm the better performance of the RES-based model over the other proposed models.

Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects

NASA Astrophysics Data System (ADS)

Courtney, Amy C.; Andrusiv, Lubov P.; Courtney, Michael W.

2012-04-01

This paper describes the development and characterization of modular, oxy-acetylene driven laboratory scale shock tubes. Such tools are needed to produce realistic blast waves in a laboratory setting. The pressure-time profiles measured at 1 MHz using high-speed piezoelectric pressure sensors have relevant durations and show a true shock front and exponential decay characteristic of free-field blast waves. Descriptions are included for shock tube diameters of 27-79 mm. A range of peak pressures from 204 kPa to 1187 kPa (with 0.5-5.6% standard error of the mean) were produced by selection of the driver section diameter and distance from the shock tube opening. The peak pressures varied predictably with distance from the shock tube opening while maintaining both a true blast wave profile and relevant pulse duration for distances up to about one diameter from the shock tube opening. This shock tube design provides a more realistic blast profile than current compression-driven shock tubes, and it does not have a large jet effect. In addition, operation does not require specialized personnel or facilities like most blast-driven shock tubes, which reduces operating costs and effort and permits greater throughput and accessibility. It is expected to be useful in assessing the response of various sensors to shock wave loading; assessing the reflection, transmission, and absorption properties of candidate armor materials; assessing material properties at high rates of loading; assessing the response of biological materials to shock wave exposure; and providing a means to validate numerical models of the interaction of shock waves with structures. All of these activities have been difficult to pursue in a laboratory setting due in part to lack of appropriate means to produce a realistic blast loading profile.

High interindividual variability in dose-dependent reduction in speed of movement after exposing C. elegans to shock waves

PubMed Central

Angstman, Nicholas B.; Kiessling, Maren C.; Frank, Hans-Georg; Schmitz, Christoph

2015-01-01

In blast-related mild traumatic brain injury (br-mTBI) little is known about the connections between initial trauma and expression of individual clinical symptoms. Partly due to limitations of current in vitro and in vivo models of br-mTBI, reliable prediction of individual short- and long-term symptoms based on known blast input has not yet been possible. Here we demonstrate a dose-dependent effect of shock wave exposure on C. elegans using shock waves that share physical characteristics with those hypothesized to induce br-mTBI in humans. Increased exposure to shock waves resulted in decreased mean speed of movement while increasing the proportion of worms rendered paralyzed. Recovery of these two behavioral symptoms was observed during increasing post-traumatic waiting periods. Although effects were observed on a population-wide basis, large interindividual variability was present between organisms exposed to the same highly controlled conditions. Reduction of cavitation by exposing worms to shock waves in polyvinyl alcohol resulted in reduced effect, implicating primary blast effects as damaging components in shock wave induced trauma. Growing worms on NGM agar plates led to the same general results in initial shock wave effect in a standard medium, namely dose-dependence and high interindividual variability, as raising worms in liquid cultures. Taken together, these data indicate that reliable prediction of individual clinical symptoms based on known blast input as well as drawing conclusions on blast input from individual clinical symptoms is not feasible in br-mTBI. PMID:25705183

Empirical Scaling Laws of Rocket Exhaust Cratering

NASA Technical Reports Server (NTRS)

Donahue, Carly M.; Metzger, Philip T.; Immer, Christopher D.

2005-01-01

When launching or landing a space craft on the regolith of a terrestrial surface, special attention needs to be paid to the rocket exhaust cratering effects. If the effects are not controlled, the rocket cratering could damage the spacecraft or other surrounding hardware. The cratering effects of a rocket landing on a planet's surface are not understood well, especially for the lunar case with the plume expanding in vacuum. As a result, the blast effects cannot be estimated sufficiently using analytical theories. It is necessary to develop physics-based simulation tools in order to calculate mission-essential parameters. In this work we test out the scaling laws of the physics in regard to growth rate of the crater depth. This will provide the physical insight necessary to begin the physics-based modeling.

The 2NS Translocation from Aegilops ventricosa Confers Resistance to the Triticum Pathotype of Magnaporthe oryzae

PubMed Central

Cruz, C.D.; Peterson, G.L.; Bockus, W.W.; Kankanala, P.; Dubcovsky, J.; Jordan, K.W.; Akhunov, E.; Chumley, F.; Baldelomar, F.D.; Valent, B.

2016-01-01

Wheat blast is a serious disease caused by the fungus Magnaporthe oryzae (Triticum pathotype) (MoT). The objective of this study was to determine the effect of the 2NS translocation from Aegilops ventricosa (Zhuk.) Chennav on wheat head and leaf blast resistance. Disease phenotyping experiments were conducted in growth chamber, greenhouse, and field environments. Among 418 cultivars of wheat (Triticum aestivum L.), those with 2NS had 50.4 to 72.3% less head blast than those without 2NS when inoculated with an older MoT isolate under growth chamber conditions. When inoculated with recently collected isolates, cultivars with 2NS had 64.0 to 80.5% less head blast. Under greenhouse conditions when lines were inoculated with an older MoT isolate, those with 2NS had a significant head blast reduction. With newer isolates, not all lines with 2NS showed a significant reduction in head blast, suggesting that the genetic background and/or environment may influence the expression of any resistance conferred by 2NS. However, when near-isogenic lines (NILs) with and without 2NS were planted in the field, there was strong evidence that 2NS conferred resistance to head blast. Results from foliar inoculations suggest that the resistance to head infection that is imparted by the 2NS translocation does not confer resistance to foliar disease. In conclusion, the 2NS translocation was associated with significant reductions in head blast in both spring and winter wheat. PMID:27814405

Experimental investigation of the noise reduction of supersonic exhaust jets with fluidic inserts

NASA Astrophysics Data System (ADS)

Powers, Russell William Walter

The noise produced by the supersonic, high temperature jets that exhaust from military aircraft is becoming a hazard to naval personnel and a disturbance to communities near military bases. Methods to reduce the noise produced from these jets in a practical full-scale environment are difficult. The development and analysis of distributed nozzle blowing for the reduction of radiated noise from supersonic jets is described. Model scale experiments of jets that simulate the exhaust jets from typical low-bypass ratio military jet aircraft engines during takeoff are performed. Fluidic inserts are created that use distributed blowing in the divergent section of the nozzle to simulate mechanical, hardwall corrugations, while having the advantage of being an active control method. This research focuses on model scale experiments to better understand the fluidic insert noise reduction method. Distributed blowing within the divergent section of the military-style convergent divergent nozzle alters the shock structure of the jet in addition to creating streamwise vorticity for the reduction of mixing noise. Enhancements to the fluidic insert design have been performed along with experiments over a large number of injection parameters and core jet conditions. Primarily military-style round nozzles have been used, with preliminary measurements of hardwall corrugations and fluidic inserts in rectangular nozzle geometries also performed. It has been shown that the noise reduction of the fluidic inserts is most heavily dependent upon the momentum flux ratio between the injector and core jet. Maximum reductions of approximately 5.5 dB OASPL have been observed with practical mass flow rates and injection pressures. The first measurements with fluidic inserts in the presence of a forward flight stream have been performed. Optimal noise reduction occurs at similar injector parameters in the presence of forward flight. Fluidic inserts in the presence of a forward flight stream were observed to reduce the peak mixing noise below the already reduced levels by nearly 4 dB OASP and the broadband shock-associated noise by nearly 3 dB OASP. Unsteady velocity measurements are used to complement acoustic results of jets with fluidic inserts. Measured axial turbulence intensities and mean axial velocity are examined to illuminate the differences in the flow field from jets with fluidic inserts. Comparisons of laser Doppler measurements with RANS CFD simulations are shown with good agreement. Analysis of the effect of spatial turbulence on the measured quantities is performed. Experimental model scale measurements of jets with and without fluidic inserts over a simulated carrier deck are presented. The model carrier environment consists of a ground plane of adjustable distance below the jet, and a simulated jet blast deflector similar to those found in practice. Measurements are performed with far-field microphones, near-field microphones, and unsteady pressure sensors. The constructive and destructive interference that results from the interaction of the direct and reflected sound waves is observed and compared with results from free jets. The noise reduction of fluidic inserts in a realistic carrier deck environment with steering of the "quiet planes" is examined. The overall sound pressure level in heat-simulated jets is reduced by 3-5 dB depending on the specific angle and ground plane height. Jets impinging upon a modeled jet blast deflector are tested in addition to jets solely in the presence of the carrier deck. Observed modifications to the acoustic field from the presence of the jet blast deflector include downstream acoustic shielding and low frequency augmentation. The region of maximum noise radiation for heat-simulated jets from nozzles with fluidic inserts impinging on the jet blast deflector is reduced in overall sound pressure level by 4-7 dB. This region includes areas where aircraft carrier personnel are located. iv.

Evaluation of ground granulated iron blast-furnace slag : grade-100.

DOT National Transportation Integrated Search

2002-09-01

Currently, the use of grade-120 Granulated Ground Blast Furnace Slag (GGBFS) is incorporated into the specifications of LA DOTD concrete mixes. This study evaluates grade-100 GGBFS and its effect on the properties of hydraulic cement concretes used i...

PERFORMANCE OF RC AND FRC WALL PANELS REINFORCED WITH MILD STEEL AND GFRP COMPOSITES IN BLAST EVENTS

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

Timothy Garfield; William D. Richins; Thomas K. Larson

The structural integrity of reinforced concrete structures in blast events is important for critical facilities. This paper presents experimental data generated for calibrating detailed finite element models that predict the performance of reinforced concrete wall panels with a wide range of construction details under blast loading. The test specimens were 1.2 m square wall panels constructed using Normal Weight Concrete (NWC) or Fiber Reinforced Concrete (FRC). FRC consists of macro-synthetic fibers dispersed in NWC. Five types of panels were tested: NWC panels with steel bar reinforcement (Type A); FRC panels without additional reinforcement (Type B); FRC panels with steel barmore » reinforcement (Type C); NWC panels with glass fiber reinforced polymer (GFRP) bar reinforcement (Type D); and NWC panels reinforced with steel bar reinforcement and external bidirectional GFRP overlays on both faces (Type E). An additional three Type C panels were used as control specimens (CON). Each panel type was constructed with three thicknesses: 152 mm, 254 mm, and 356 mm. The panels were instrumented with strain gauges, and accelerometers; in addition, pressure sensors and high speed videos were employed during the blast events. Panel types C and E had the best performance, whereas panel type B did not perform well. Preliminary dynamic simulations show crack patterns similar to the experimental results.« less

Modeling Sound as a Non-Lethal Weapon in the COMBAT(XXI) Simulation Model

DTIC Science & Technology

2005-06-01

Kilgore in ‘ Apocalypse Now !’ [Ref 4] blasting Wagner from his Cavalry helicopters. Moving from film to recent history, consider how General Noriega...Military Operations Research Society, 71 4. Coppola, F. F. (Producer). (1979). Apocalypse now . [Motion Picture] Hollywood, California: United Artists

Fracture and fatigue behavior of shot-blasted titanium dental implants.

PubMed

Gil, F J; Planell, J A; Padrós, A

2002-01-01

This investigation studies the effect of the shot-blasting treatment on the cyclic deformation behavior of a commercially pure titanium, with two microstructures: equiaxed and acicular. The fatigue tests were carried out in artificial saliva medium at 37 degrees C. Cyclic deformation tests have been carried out up to fracture, and the fatigue crack nucleation and propagation have been analyzed. The results show that the shot-blasting treatment improves the fatigue life in the microstructures studied, and that the equiaxed was better in mechanical properties than the acicular. The cause of this improvement in the mechanical properties is due to the compressive stress on the material surface for the shot-blasted specimens. Hardness tests were carried out to determine the value of these internal stresses.

Detecting blast-induced infrasound in wind noise.

PubMed

Howard, Wheeler B; Dillion, Kevin L; Shields, F Douglas

2010-03-01

Current efforts seek to monitor and investigate such naturally occurring events as volcanic eruptions, hurricanes, bolides entering the atmosphere, earthquakes, and tsunamis by the infrasound they generate. Often, detection of the infrasound signal is limited by the masking effect of wind noise. This paper describes the use of a distributed array to detect infrasound signals from four atmospheric detonations at White Sands Missile Range in New Mexico, USA in 2006. Three of the blasts occurred during times of low wind noise and were easily observed with array processing techniques. One blast was obscured by high wind conditions. The results of signal processing are presented that allowed localization of the blast-induced signals in the presence of wind noise in the array response.

The Potential of Streptomyces as Biocontrol Agents against the Rice Blast Fungus, Magnaporthe oryzae (Pyricularia oryzae).

PubMed

Law, Jodi Woan-Fei; Ser, Hooi-Leng; Khan, Tahir M; Chuah, Lay-Hong; Pusparajah, Priyia; Chan, Kok-Gan; Goh, Bey-Hing; Lee, Learn-Han

2017-01-01

Rice is a staple food source for more than three billion people worldwide. However, rice is vulnerable to diseases, the most destructive among them being rice blast, which is caused by the fungus Magnaporthe oryzae (anamorph Pyricularia oryzae ). This fungus attacks rice plants at all stages of development, causing annual losses of approximately 10-30% in various rice producing regions. Synthetic fungicides are often able to effectively control plant diseases, but some fungicides result in serious environmental and health problems. Therefore, there is growing interest in discovering and developing new, improved fungicides based on natural products as well as introducing alternative measures such as biocontrol agents to manage plant diseases. Streptomyce s bacteria appear to be promising biocontrol agents against a wide range of phytopathogenic fungi, which is not surprising given their ability to produce various bioactive compounds. This review provides insight into the biocontrol potential of Streptomyces against the rice blast fungus, M. oryzae . The ability of various S treptomyces spp. to act as biocontrol agents of rice blast disease has been studied by researchers under both laboratory and greenhouse/growth chamber conditions. Laboratory studies have shown that Streptomyces exhibit inhibitory activity against M. oryzae . In greenhouse studies, infected rice seedlings treated with Streptomyces resulted in up to 88.3% disease reduction of rice blast. Studies clearly show that Streptomyces spp. have the potential to be used as highly effective biocontrol agents against rice blast disease; however, the efficacy of any biocontrol agent may be affected by several factors including environmental conditions and methods of application. In order to fully exploit their potential, further studies on the isolation, formulation and application methods of Streptomyces along with field experiments are required to establish them as effective biocontrol agents.

The Potential of Streptomyces as Biocontrol Agents against the Rice Blast Fungus, Magnaporthe oryzae (Pyricularia oryzae)

PubMed Central

Law, Jodi Woan-Fei; Ser, Hooi-Leng; Khan, Tahir M.; Chuah, Lay-Hong; Pusparajah, Priyia; Chan, Kok-Gan; Goh, Bey-Hing; Lee, Learn-Han

2017-01-01

Rice is a staple food source for more than three billion people worldwide. However, rice is vulnerable to diseases, the most destructive among them being rice blast, which is caused by the fungus Magnaporthe oryzae (anamorph Pyricularia oryzae). This fungus attacks rice plants at all stages of development, causing annual losses of approximately 10–30% in various rice producing regions. Synthetic fungicides are often able to effectively control plant diseases, but some fungicides result in serious environmental and health problems. Therefore, there is growing interest in discovering and developing new, improved fungicides based on natural products as well as introducing alternative measures such as biocontrol agents to manage plant diseases. Streptomyces bacteria appear to be promising biocontrol agents against a wide range of phytopathogenic fungi, which is not surprising given their ability to produce various bioactive compounds. This review provides insight into the biocontrol potential of Streptomyces against the rice blast fungus, M. oryzae. The ability of various Streptomyces spp. to act as biocontrol agents of rice blast disease has been studied by researchers under both laboratory and greenhouse/growth chamber conditions. Laboratory studies have shown that Streptomyces exhibit inhibitory activity against M. oryzae. In greenhouse studies, infected rice seedlings treated with Streptomyces resulted in up to 88.3% disease reduction of rice blast. Studies clearly show that Streptomyces spp. have the potential to be used as highly effective biocontrol agents against rice blast disease; however, the efficacy of any biocontrol agent may be affected by several factors including environmental conditions and methods of application. In order to fully exploit their potential, further studies on the isolation, formulation and application methods of Streptomyces along with field experiments are required to establish them as effective biocontrol agents. PMID:28144236

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

NASA Astrophysics Data System (ADS)

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.

BLAST and FASTA similarity searching for multiple sequence alignment.

PubMed

Pearson, William R

2014-01-01

BLAST, FASTA, and other similarity searching programs seek to identify homologous proteins and DNA sequences based on excess sequence similarity. If two sequences share much more similarity than expected by chance, the simplest explanation for the excess similarity is common ancestry-homology. The most effective similarity searches compare protein sequences, rather than DNA sequences, for sequences that encode proteins, and use expectation values, rather than percent identity, to infer homology. The BLAST and FASTA packages of sequence comparison programs provide programs for comparing protein and DNA sequences to protein databases (the most sensitive searches). Protein and translated-DNA comparisons to protein databases routinely allow evolutionary look back times from 1 to 2 billion years; DNA:DNA searches are 5-10-fold less sensitive. BLAST and FASTA can be run on popular web sites, but can also be downloaded and installed on local computers. With local installation, target databases can be customized for the sequence data being characterized. With today's very large protein databases, search sensitivity can also be improved by searching smaller comprehensive databases, for example, a complete protein set from an evolutionarily neighboring model organism. By default, BLAST and FASTA use scoring strategies target for distant evolutionary relationships; for comparisons involving short domains or queries, or searches that seek relatively close homologs (e.g. mouse-human), shallower scoring matrices will be more effective. Both BLAST and FASTA provide very accurate statistical estimates, which can be used to reliably identify protein sequences that diverged more than 2 billion years ago.

Electrical Currents and Adhesion of Edge-Delete Regions of EVA-to-Glass Module Packaging: Preprint

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

McMahon, T. J.; Jorgensen, G. J.

2001-10-01

Presented at the 2001 NCPV Program Review Meeting: Electrical conductivity pathways from the grounded frame to the cell area in a PV module are reviewed here. Electrical conductivity pathways from the grounded frame to the cell area in a PV module are reviewed here. Measurements are made on 4 inch x 8 inch soda lime (SL) glass substrates with contact patterns defined using 3-mil and 10-mil diameter bead-blast removal of the SnO{sub 2} coating to study the dominant path, which is the EVA/glass interface. The remaining SnO{sub 2} contact strips are separated by what would simulate the module edge deletemore » regions. EVA encapsulated bead-blast surface resistances are 8 x 10{sup 15} ohm/sq compared to 8 x 10{sup 12} ohm/sq for native SL glass surfaces. Adhesion strengths to bead-blast surfaces are 25 to 30 lbs/in. Stress test results on these interfaces after removal from damp heat suggest corrosion of the glass at the glass-EVA interface.« less

Process for Design Optimization of Honeycomb Core Sandwich Panels for Blast Load Mitigation

DTIC Science & Technology

2012-12-01

experiments. Numerical simulation using a single ‘Y’ cross-sectional unit cell model predicted the crush behavior quite well compared to experiments with...of foil glued together by an adhesive. LS-DYNA is used to carry out the virtual simulation . The foil is modeled by quadrilateral Belytschko-Tsay...aluminum alloy with bilinear isotropic-hardening elastoplastic material model is used for the foil. Since the yield and ultimate strength of the AL5052

Manufacture and Preparation of Test Specimens for Johnson-Cook Material Characterization

DTIC Science & Technology

2013-01-01

modeling and simulation, and will be included in the Elastic Plastic Impact Code (EPIC) library. This report describes the welding and machining...used by the government for ballistic, blast and other types of modeling and simulation, and will be included in the Elastic Plastic Impact Code (EPIC...made of H13 tool steel with a scrolled pin and shoulder (See Figure 2-3) was used however the different heat requirements of the materials required

Characteristics and mechanisms of cardiopulmonary injury caused by mine blasts in shoals: a randomized controlled study in a rabbit model.

PubMed

Han, Gengfen; Wang, Ziming; Wang, Jianmin; Yang, Weixiao; Chen, Jing; Kang, Jianyi; Zhang, Sen; Wang, Aimin; Lai, Xinan

2013-01-01

Because the characteristics of blast waves in water are different from those in air and because kinetic energy is liberated by a pressure wave at the water-air interface, thoracic injuries from mine blasts in shoals may be serious. The aim of the present study was to investigate the characteristics and mechanisms of cardiopulmonary injury caused by mine blasts in shoals. To study the characteristics of cardiopulmonary injury, 56 animals were divided randomly into three experimental groups (12 animals in the sham group, 22 animals in the land group and 22 animals in the shoal group). To examine the biomechanics of injury, 20 animals were divided randomly into the land group and the shoal group. In the experimental model, the water surface was at the level of the rabbit's xiphoid process, and paper electric detonators (600 mg RDX) were used to simulate mines. Electrocardiography and echocardiography were conducted, and arterial blood gases, serum levels of cardiac troponin I and creatine kinase-MB and other physiologic parameters were measured over a 12-hour period after detonation. Pressures in the thorax and abdomen and the acceleration of the thorax were measured. The results indicate that severe cardiopulmonary injury and dysfunction occur following exposure to mine blasts in shoals. Therefore, the mechanisms of cardiopulmonary injury may result from shear waves that produce strain at the water-air interface. Another mechanism of injury includes the propagation of the shock wave from the planta to the thorax, which causes a much higher peak overpressure in the abdomen than in the thorax; as a result, the abdominal organs and diaphragm are thrust into the thorax, damaging the lungs and heart.

Design and Verification of Blast Densification for Highway Embankments of Liquefiable Sands

DOT National Transportation Integrated Search

2012-10-26

As part of a larger effort to investigate the effects of blast densification on the properties and : behavior of compacted sand deposits, this study presents a procedure for replicating in the : laboratory the occluded gas bubbles believed to exist i...

Characterization of Psychological and Biological Factors in an Animal Model of Warrior Stress

DTIC Science & Technology

2013-07-26

blast/stress (257; 259), and presentation of effects of blast/stress on central monoamine activity ( 22 ). In each of these cases, the dependent...secreted by the pituitary gland. Prolactin is known to physiologically increase the stimulatory effect of ACTH-induced corticosterone secretion in...the stress field. J. Human Stress: 22 -36 165. McAllister TW, Stein MB. 2010. Effects of psychological and biomechanical trauma on brain and behavior

Manganese-Enhanced Magnetic Resonance Imaging as a Diagnostic and Dispositional Tool after Mild-Moderate Blast Traumatic Brain Injury

PubMed Central

Schaefer, Michele L.; Wester, Brock; Lee, Yi-Chien; Boggs, Nathan; Conner, Howard A.; Merkle, Andrew C.; Fricke, Stanley T.; Albanese, Chris; Koliatsos, Vassilis E.

2016-01-01

Abstract Traumatic brain injury (TBI) caused by explosive munitions, known as blast TBI, is the signature injury in recent military conflicts in Iraq and Afghanistan. Diagnostic evaluation of TBI, including blast TBI, is based on clinical history, symptoms, and neuropsychological testing, all of which can result in misdiagnosis or underdiagnosis of this condition, particularly in the case of TBI of mild-to-moderate severity. Prognosis is currently determined by TBI severity, recurrence, and type of pathology, and also may be influenced by promptness of clinical intervention when more effective treatments become available. An important task is prevention of repetitive TBI, particularly when the patient is still symptomatic. For these reasons, the establishment of quantitative biological markers can serve to improve diagnosis and preventative or therapeutic management. In this study, we used a shock-tube model of blast TBI to determine whether manganese-enhanced magnetic resonance imaging (MEMRI) can serve as a tool to accurately and quantitatively diagnose mild-to-moderate blast TBI. Mice were subjected to a 30 psig blast and administered a single dose of MnCl2 intraperitoneally. Longitudinal T1-magnetic resonance imaging (MRI) performed at 6, 24, 48, and 72 h and at 14 and 28 days revealed a marked signal enhancement in the brain of mice exposed to blast, compared with sham controls, at nearly all time-points. Interestingly, when mice were protected with a polycarbonate body shield during blast exposure, the marked increase in contrast was prevented. We conclude that manganese uptake can serve as a quantitative biomarker for TBI and that MEMRI is a minimally-invasive quantitative approach that can aid in the accurate diagnosis and management of blast TBI. In addition, the prevention of the increased uptake of manganese by body protection strongly suggests that the exposure of an individual to blast risk could benefit from the design of improved body armor. PMID:26414591

Manganese-Enhanced Magnetic Resonance Imaging as a Diagnostic and Dispositional Tool after Mild-Moderate Blast Traumatic Brain Injury.

PubMed

Rodriguez, Olga; Schaefer, Michele L; Wester, Brock; Lee, Yi-Chien; Boggs, Nathan; Conner, Howard A; Merkle, Andrew C; Fricke, Stanley T; Albanese, Chris; Koliatsos, Vassilis E

2016-04-01

Traumatic brain injury (TBI) caused by explosive munitions, known as blast TBI, is the signature injury in recent military conflicts in Iraq and Afghanistan. Diagnostic evaluation of TBI, including blast TBI, is based on clinical history, symptoms, and neuropsychological testing, all of which can result in misdiagnosis or underdiagnosis of this condition, particularly in the case of TBI of mild-to-moderate severity. Prognosis is currently determined by TBI severity, recurrence, and type of pathology, and also may be influenced by promptness of clinical intervention when more effective treatments become available. An important task is prevention of repetitive TBI, particularly when the patient is still symptomatic. For these reasons, the establishment of quantitative biological markers can serve to improve diagnosis and preventative or therapeutic management. In this study, we used a shock-tube model of blast TBI to determine whether manganese-enhanced magnetic resonance imaging (MEMRI) can serve as a tool to accurately and quantitatively diagnose mild-to-moderate blast TBI. Mice were subjected to a 30 psig blast and administered a single dose of MnCl2 intraperitoneally. Longitudinal T1-magnetic resonance imaging (MRI) performed at 6, 24, 48, and 72 h and at 14 and 28 days revealed a marked signal enhancement in the brain of mice exposed to blast, compared with sham controls, at nearly all time-points. Interestingly, when mice were protected with a polycarbonate body shield during blast exposure, the marked increase in contrast was prevented. We conclude that manganese uptake can serve as a quantitative biomarker for TBI and that MEMRI is a minimally-invasive quantitative approach that can aid in the accurate diagnosis and management of blast TBI. In addition, the prevention of the increased uptake of manganese by body protection strongly suggests that the exposure of an individual to blast risk could benefit from the design of improved body armor.

29 CFR 1926.909 - Firing the blast.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Firing the blast. (a) A code of blasting signals equivalent to Table U-1, shall be posted on one or more... blasts 5 minutes prior to blast signal. Blast Signal—A series of short blasts 1 minute prior to the shot...

29 CFR 1926.909 - Firing the blast.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Firing the blast. (a) A code of blasting signals equivalent to Table U-1, shall be posted on one or more... blasts 5 minutes prior to blast signal. Blast Signal—A series of short blasts 1 minute prior to the shot...

29 CFR 1926.909 - Firing the blast.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Firing the blast. (a) A code of blasting signals equivalent to Table U-1, shall be posted on one or more... blasts 5 minutes prior to blast signal. Blast Signal—A series of short blasts 1 minute prior to the shot...

29 CFR 1926.909 - Firing the blast.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Firing the blast. (a) A code of blasting signals equivalent to Table U-1, shall be posted on one or more... blasts 5 minutes prior to blast signal. Blast Signal—A series of short blasts 1 minute prior to the shot...

29 CFR 1926.909 - Firing the blast.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Firing the blast. (a) A code of blasting signals equivalent to Table U-1, shall be posted on one or more... blasts 5 minutes prior to blast signal. Blast Signal—A series of short blasts 1 minute prior to the shot...

Bomb blast, mild traumatic brain injury and psychiatric morbidity: a review.

PubMed

Rosenfeld, Jeffrey V; Ford, Nick L

2010-05-01

Traumatic brain injury (TBI) arising from blast exposure during war is common, and frequently complicated by psychiatric morbidity. There is controversy as to whether mild TBI from blast is different from other causes of mild TBI. Anxiety and affective disorders such as Post-traumatic Stress Disorder (PTSD) and depression are common accompaniments of blast injury with a significant overlap in the diagnostic features of PTSD with post-concussive syndrome (PCS). This review focuses on this overlap and the effects of mild TBI due to bomb blast. Mild TBI may have been over diagnosed by late retrospective review of returned servicemen and women using imprecise criteria. There is therefore a requirement for clear and careful documentation by health professionals of a TBI due to bomb blast shortly after the event so that the diagnosis of TBI can be made with confidence. There is a need for the early recognition of symptoms of PCS, PTSD and depression and early multi-disciplinary interventions focussed on expected return to duties. There also needs to be a continued emphasis on the de-stigmatization of psychological conditions in military personnel returning from deployment. (c) 2009 Elsevier Ltd. All rights reserved.

25. "GAFFTC 19 OCT 60, BLAST EFFECTS ON AIRFOILS, STATIC ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

25. "G-AFFTC 19 OCT 60, BLAST EFFECTS ON AIRFOILS, STATIC RUN 5." View of track rail mounting and the water brake trough at 20,000-foot track. Looking northeast. File no. 12,358-60. - Edwards Air Force Base, South Base Sled Track, Edwards Air Force Base, North of Avenue B, between 100th & 140th Streets East, Lancaster, Los Angeles County, CA

THEORETICAL BACKGROUND AND DERIVATION OF SELECTED EQUATIONS FROM THE REPORT STUDY OF BLAST EFFECTS IN SOIL

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

Ehlers, O.K.; Grum, A.F.

1959-03-27

An amplification and clarification of the report Study of Blast Effects in Soil by M. A. Chaszeyka and F. B. Porzel of the Armour Research Foundation is presented. The basic thermodynamic relationships that are essential to the understanding of the Armour Report are given, and the more complex equations of the Armour Report are derived. (auth)

Change in surface properties of zirconia and initial attachment of osteoblastlike cells with hydrophilic treatment.

PubMed

Watanabe, Hiroaki; Saito, Kensuke; Kokubun, Katsutoshi; Sasaki, Hodaka; Yoshinari, Masao

2012-01-01

The objectives of this study were to characterize change in surface properties of tetragonal zirconia polycrystals (TZP) after hydrophilic treatment, and to determine the effect of such changes on initial attachment of osteoblast-like cells. Roughened surfaces were produced by alumina-blasting and acid-etching. Hydrophilic treatment comprised application of immediately after blasting and acid-etching (Blast/Etch), oxygen plasma (O2-Plasma), ultraviolet light (UV). Specimens stored in air were used as a control. The water contact angle was determined and surface analysis was performed using an X-ray photoelectron spectroscopy. Blast/Etch, O2-Plasma and UV specimens showed superhydrophilicity, and these hydrophilic treatments to TZP elicited a marked decrease in carbon content and an increase in hydroxyl groups. Hydrophilic treatments enhanced initial attachment of osteoblast-like cells and a change in cell morphologies. These results indicate that Blast/Etch, O2-Plasma, or UV treatment has potential in the creation and maintenance of superhydrophilic surfaces and enhancing initial attachment of osteoblast-like cells.

Improvement in the properties of plasma-sprayed metallic, alloy and ceramic coatings using dry-ice blasting

NASA Astrophysics Data System (ADS)

Dong, Shujuan; Song, Bo; Hansz, Bernard; Liao, Hanlin; Coddet, Christian

2011-10-01

Dry-ice blasting, as an environmental-friendly method, was introduced into atmospheric plasma spraying for improving properties of metallic, alloy and ceramic coatings. The deposited coatings were then compared with coatings plasma-sprayed using conventional air cooling in terms of microstructure, temperature, oxidation, porosity, residual stress and adhesion. It was found that a denser steel or CoNiCrAlY alloy coating with a lower content of oxide can be achieved with the application of dry-ice blasting during the plasma spraying. In addition, the adhesive strength of Al 2O 3 coating deposited with dry-ice blasting exceeded 60 MPa, which was nearly increased by 30% compared with that of the coating deposited with conventional air cooling. The improvement in properties of plasma-sprayed metallic, alloy and ceramic coatings caused by dry-ice blasting was attributed to the decrease of annulus-ringed disk like splats, the better cooling efficiency of dry-ice pellets and even the mechanical effect of dry-ice impact.

Characterization of viscoelastic materials for low-magnitude blast mitigation

NASA Astrophysics Data System (ADS)

Bartyczak, S.; Mock, W.

2014-05-01

Recent research indicates that exposure to low amplitude blast waves, such as IED detonation or multiple firings of a weapon, causes damage to brain tissue resulting in Traumatic Brain Injury (TBI) and Post Traumatic Stress Disorder (PTSD). Current combat helmets are not sufficiently protecting warfighters from this danger and the effects are debilitating, costly, and long-lasting. The objective of the present work is to evaluate the blast mitigating behavior of current helmet materials and new materials designed for blast mitigation using a test fixture recently developed at the Naval Surface Warfare Center Dahlgren Division for use with an existing gas gun. The 40-mm-bore gas gun was used as a shock tube to generate blast waves (ranging from 0.5 to 2 bar) in the test fixture mounted on the gun muzzle. A fast opening valve was used to release helium gas from the breech which formed into a blast wave and impacted instrumented targets in the test fixture. Blast attenuation of selected materials was determined through the measurement of stress data in front of and behind the target. Materials evaluated in this research include polyurethane foam from currently fielded US Army and Marine Corps helmets, polyurea 1000, and three hardnesses of Sorbothane (48, 58, and 70 durometer, Shore 00). Polyurea 1000 and 6061-T6 aluminum were used to calibrate the stress gauges.

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

PubMed

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

2009-06-01

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

Modelling Public Security Operations: Analysis of the Effect of Key Social, Cognitive, and Informational Factors with Security System Relationship Configurations for Goal Achievement

DTIC Science & Technology

2012-12-01

of MARSEC 2 13 Causing a fire or explosion, conducting blasting or setting off fireworks , including setting a flare or other signalling device...or explosion, conducting blasting or setting off fireworks , including setting a flare or other signalling device without port approval X X X X X X...explosion, conducting blasting or setting off fireworks , including setting a flare or other signalling device without port approval X X X X X X X Non

CrocoBLAST: Running BLAST efficiently in the age of next-generation sequencing.

PubMed

Tristão Ramos, Ravi José; de Azevedo Martins, Allan Cézar; da Silva Delgado, Gabrielle; Ionescu, Crina-Maria; Ürményi, Turán Peter; Silva, Rosane; Koca, Jaroslav

2017-11-15

CrocoBLAST is a tool for dramatically speeding up BLAST+ execution on any computer. Alignments that would take days or weeks with NCBI BLAST+ can be run overnight with CrocoBLAST. Additionally, CrocoBLAST provides features critical for NGS data analysis, including: results identical to those of BLAST+; compatibility with any BLAST+ version; real-time information regarding calculation progress and remaining run time; access to partial alignment results; queueing, pausing, and resuming BLAST+ calculations without information loss. CrocoBLAST is freely available online, with ample documentation (webchem.ncbr.muni.cz/Platform/App/CrocoBLAST). No installation or user registration is required. CrocoBLAST is implemented in C, while the graphical user interface is implemented in Java. CrocoBLAST is supported under Linux and Windows, and can be run under Mac OS X in a Linux virtual machine. jkoca@ceitec.cz. Supplementary data are available at Bioinformatics online. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

Effects of Mild Blast Traumatic Brain Injury on Cerebral Vascular, Histopathological, and Behavioral Outcomes in Rats

PubMed Central

Zeng, Yaping; Deyo, Donald; Parsley, Margaret A.; Hawkins, Bridget E.; Prough, Donald S.; DeWitt, Douglas S.

2018-01-01

Abstract To determine the effects of mild blast-induced traumatic brain injury (bTBI), several groups of rats were subjected to blast injury or sham injury in a compressed air-driven shock tube. The effects of bTBI on relative cerebral perfusion (laser Doppler flowmetry [LDF]), and mean arterial blood pressure (MAP) cerebral vascular resistance were measured for 2 h post-bTBI. Dilator responses to reduced intravascular pressure were measured in isolated middle cerebral arterial (MCA) segments, ex vivo, 30 and 60 min post-bTBI. Neuronal injury was assessed (Fluoro-Jade C [FJC]) 24 and 48 h post-bTBI. Neurological outcomes (beam balance and walking tests) and working memory (Morris water maze [MWM]) were assessed 2 weeks post-bTBI. Because impact TBI (i.e., non-blast TBI) is often associated with reduced cerebral perfusion and impaired cerebrovascular function in part because of the generation of reactive oxygen and nitrogen species such as peroxynitrite (ONOO−), the effects of the administration of the ONOO− scavenger, penicillamine methyl ester (PenME), on cerebral perfusion and cerebral vascular resistance were measured for 2 h post-bTBI. Mild bTBI resulted in reduced relative cerebral perfusion and MCA dilator responses to reduced intravascular pressure, increases in cerebral vascular resistance and in the numbers of FJC-positive cells in the brain, and significantly impaired working memory. PenME administration resulted in significant reductions in cerebral vascular resistance and a trend toward increased cerebral perfusion, suggesting that ONOO− may contribute to blast-induced cerebral vascular dysfunction. PMID:29160141

Genetic analysis and identification of SSR markers associated with rice blast disease in a BC2F1 backcross population.

PubMed

Hasan, N; Rafii, M Y; Abdul Rahim, H; Nusaibah, S A; Mazlan, N; Abdullah, S

2017-01-23

Rice (Oryza sativa L.) blast disease is one of the most destructive rice diseases in the world. The fungal pathogen, Magnaporthe oryzae, is the causal agent of rice blast disease. Development of resistant cultivars is the most preferred method to achieve sustainable rice production. However, the effectiveness of resistant cultivars is hindered by the genetic plasticity of the pathogen genome. Therefore, information on genetic resistance and virulence stability are vital to increase our understanding of the molecular basis of blast disease resistance. The present study set out to elucidate the resistance pattern and identify potential simple sequence repeat markers linked with rice blast disease. A backcross population (BC 2 F 1 ), derived from crossing MR264 and Pongsu Seribu 2 (PS2), was developed using marker-assisted backcross breeding. Twelve microsatellite markers carrying the blast resistance gene clearly demonstrated a polymorphic pattern between both parental lines. Among these, two markers, RM206 and RM5961, located on chromosome 11 exhibited the expected 1:1 testcross ratio in the BC 2 F 1 population. The 195 BC 2 F 1 plants inoculated against M. oryzae pathotype P7.2 showed a significantly different distribution in the backcrossed generation and followed Mendelian segregation based on a single-gene model. This indicates that blast resistance in PS2 is governed by a single dominant gene, which is linked to RM206 and RM5961 on chromosome 11. The findings presented in this study could be useful for future blast resistance studies in rice breeding programs.

Influence of implant surface topography on bone-regenerative potential and mechanical retention in the human maxilla and mandible.

PubMed

Wei, Niu; Bin, Shi; Jing, Zhou; Wei, Sun; Yingqiong, Zhao

2014-06-01

To evaluate the short- and mid-term effects of commercial pure (cp) titanium implant surface topography on osseointegration, bone-regenerative potential and mechanical retention in the human maxilla and mandible. 32 micro-implants with the same geometry but with four different surface treatments were implanted in the maxilla and mandible of eight patients. Each patient received four micro-implants, one of each type. Percentage of bone-to-implant contact analysis and histological evaluation was carried 3, 6 and 12 weeks after implantation. Furthermore, reverse removal torque tests were conducted 3 and 6 weeks after implantation to analyze functional bone attachment. Implant surfaces tested were: machined, grit-blasted, acid-etched, and grit-blasted with acid-etch. One-way ANOVA was performed using the multiple comparison Fisher's test to determine significance of observed differences among test groups. The level of significance was established at 5% (P < 0.05). Mean and standard deviations of the test groups were calculated. Surface roughness had a significant correlation with the evolution of bone regeneration. The surfaces with roughness Ra approximately 4 microim (grit-blasted and grit-blasted with acid-etch), showed rapid tissue colonization compared to machine and acid-etched surfaces. The results of reverse removal torque tests confirmed a significant correlation between surface roughness and functional bone attachment. Grit-blasted and grit-blasted with acid etched surfaces showed higher retention values compared to machine and acid-etched implants. This finding was supported by higher bone-to-implant contact observed for rougher surfaces (grit-blasted and grit-blasted with acid etching).

Paint removal using wheat starch blast media

NASA Astrophysics Data System (ADS)

Foster, Terry; Oestreich, John

1993-03-01

A review of the Wheat Starch Blasting technology is presented. Laboratory evaluations covering Almen Arc testing on bare 2024-T3 aluminum and magnesium, as well as crack detection on 7075-T6 bare aluminum, are discussed. Comparisons with Type V plastic media show lower residual stresses are achieved on aluminum and magnesium with wheat starch media. Dry blasting effects on the detection of cracks confirms better crack visibility with wheat starch media versus Type V or Type II plastic media. Testing of wheat starch media in several composite test programs, including fiberglass, Kevlar, and graphite-epoxy composites, showed no fiber damage. Process developments and production experience at the first U.S. aircraft stripping facility are also reviewed. Corporate and regional aircraft are being stripped in this three nozzle dry blast hanger.

Effect of Admixtures on the Yield Stresses of Cement Pastes under High Hydrostatic Pressures

PubMed Central

Yim, Hong Jae; Kim, Jae Hong; Kwon, Seung Hee

2016-01-01

When cement-based materials are transported at a construction site, they undergo high pressures during the pumping process. The rheological properties of the materials under such high pressures are unknown, and estimating the workability of the materials after pumping is a complex problem. Among various influential factors on the rheology of concrete, this study investigated the effect of mineral and chemical admixtures on the high-pressure rheology. A rheometer was fabricated that could measure the rheological properties while maintaining a high pressure to simulate the pumping process. The effects of superplasticizer, silica fume, nanoclay, fly ash, or ground granulated blast furnace slag were investigated when mixed with two control cement pastes. The water-to-cement ratios were 0.35 and 0.50. PMID:28773273

Detonation Propagation through Nitromethane Embedded Metal Foam

NASA Astrophysics Data System (ADS)

Lieberthal, Brandon; Maines, Warren R.; Stewart, D. Scott

2015-11-01

There is considerable interest in developing a better understanding of dynamic behaviors of multicomponent systems. We report results of Eulerian hydrodynamic simulations of shock waves propagating through metal foam at approximately 20% relative density and various porosities using a reactive flow model in the ALE3D software package. We investigate the applied pressure and energy of the shock wave and its effects on the fluid and the inert material interface. By varying pore sizes, as well as metal impedance, we predict the overall effects of heterogeneous material systems at the mesoscale. In addition, we observe a radially expanding blast front in these heterogeneous models and apply the theory of Detonation Shock Dynamics to the convergence behavior of the lead shock.

FIELD DEMONSTRATION OF LEAD-BASED PAINT REMOVAL AND INORGANIC STABILIZATION TECHNOLOGIES

EPA Science Inventory

A study was conducted to demonstrate the effectiveness of a wet abrasive blasting technology to remove lead-based paint from exterior wood siding and brock substrates and to stabilize the resultant blasting media (coal slag and mineral sand) paint debris to reduce the leachable l...

Understanding the molecular mechanisms of rice blast resistance using rice mutants

USDA-ARS?s Scientific Manuscript database

Induced mutation can be useful for studying resistance gene controlled plant immunity. Resulting knowledge should benefit the development of strategies for crop protection. The Pi-ta gene in rice has been effectively deployed for preventing rice blast disease-the most devastating disease of rice wo...

Blast Effects on Fires

DTIC Science & Technology

1980-12-01

Film Records..........................33 Discussion and Interpretation..................34 CRIB FIRE EXTINGUISHMENT BY BLAST ................... 36...48 Phototransistor Records ................... 53 Film Records and Visual Observation. ............ 54 v Discussion and Interpretation...deflection by the barrier and a region of reverse flow behind the barrier; film coverage (with fires) indicates that fuel reignition occurs in the large

Combinations of pozzolans and ground, granulated blast-furnace slag for durable hydraulic cement concrete

DOT National Transportation Integrated Search

1999-08-01

Hydraulic cement concretes were produced using pozzolans and ground, granulated, blast-furnace slag to investigate the effect of these materials on durability. The pozzolans used were an ASTM C 618 Class F fly ash with a low lime content and a dry, d...

30 CFR 816.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2013 CFR

2013-07-01

... established in accordance with either the maximum peak-particle-velocity limits of paragraph (d)(2), the... in the blasting plan and approved by the regulatory authority. (2) Maximum peak particle velocity. (i... (D), from the blasting site, in feet Maximum allowable peak particle velocity (V max) for ground...

30 CFR 816.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2014 CFR

2014-07-01

... established in accordance with either the maximum peak-particle-velocity limits of paragraph (d)(2), the... in the blasting plan and approved by the regulatory authority. (2) Maximum peak particle velocity. (i... (D), from the blasting site, in feet Maximum allowable peak particle velocity (V max) for ground...

30 CFR 816.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2010 CFR

2010-07-01

... established in accordance with either the maximum peak-particle-velocity limits of paragraph (d)(2), the... in the blasting plan and approved by the regulatory authority. (2) Maximum peak particle velocity. (i... (D), from the blasting site, in feet Maximum allowable peak particle velocity (V max) for ground...

30 CFR 816.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2012 CFR

2012-07-01

... established in accordance with either the maximum peak-particle-velocity limits of paragraph (d)(2), the... in the blasting plan and approved by the regulatory authority. (2) Maximum peak particle velocity. (i... (D), from the blasting site, in feet Maximum allowable peak particle velocity (V max) for ground...

30 CFR 816.67 - Use of explosives: Control of adverse effects.

Code of Federal Regulations, 2011 CFR

2011-07-01

... established in accordance with either the maximum peak-particle-velocity limits of paragraph (d)(2), the... in the blasting plan and approved by the regulatory authority. (2) Maximum peak particle velocity. (i... (D), from the blasting site, in feet Maximum allowable peak particle velocity (V max) for ground...

POLLUTION EFFECTS OF ABNORMAL OPERATIONS IN IRON AND STEEL MAKING. VOLUME III. BLAST FURNACE IRONMAKING, MANUAL OF PRACTICE

EPA Science Inventory

The report is one in a six-volume series considering abnormal operating conditions (AOCs) in the primary section (sintering, blast furnace ironmaking, open hearth, electric furnace, and basic oxygen steelmaking) of an integrated iron and steel plant. Pollution standards, generall...

Lateral blasts at Mount St. Helens and hazard zonation

USGS Publications Warehouse

Crandell, D.R.; Hoblitt, R.P.

1986-01-01

Lateral blasts at andesitic and dacitic volcanoes can produce a variety of direct hazards, including ballistic projectiles which can be thrown to distances of at least 10 km and pyroclastic density flows which can travel at high speed to distances of more than 30 km. Indirect effect that may accompany such explosions include wind-borne ash, pyroclastic flows formed by the remobilization of rock debris thrown onto sloping ground, and lahars. Two lateral blasts occurred at a lava dome on the north flank of Mount St. Helens about 1200 years ago; the more energetic of these threw rock debris northeastward across a sector of about 30?? to a distance of at least 10 km. The ballistic debris fell onto an area estimated to be 50 km2, and wind-transported ash and lapilli derived from the lateral-blast cloud fell on an additional lobate area of at least 200 km2. In contrast, the vastly larger lateral blast of May 18, 1980, created a devastating pyroclastic density flow that covered a sector of as much as 180??, reached a maximum distance of 28 km, and within a few minutes directly affected an area of about 550 km2. The May 18 lateral blast resulted from the sudden, landslide-induced depressurization of a dacite cryptodome and the hydrothermal system that surrounded it within the volcano. We propose that lateral-blast hazard assessments for lava domes include an adjoining hazard zone with a radius of at least 10 km. Although a lateral blast can occur on any side of a dome, the sector directly affected by any one blast probably will be less than 180??. Nevertheless, a circular hazard zone centered on the dome is suggested because of the difficulty of predicting the direction of a lateral blast. For the purpose of long-term land-use planning, a hazard assessment for lateral blasts caused by explosions of magma bodies or pressurized hydrothermal systems within a symmetrical volcano could designate a circular potential hazard area with a radius of 35 km centered on the volcano. For short-term hazard assessments, if seismicity and deformation indicate that magma is moving toward the flank of a volcano, it should be recognized that a landslide could lead to the sudden unloading of a magmatic or hydrothermal system and thereby cause a catastrophic lateral blast. A hazard assessment should assume that a lateral blast could directly affect an area at least 180?? wide to a distance of 35 km from the site of the explosion, irrespective of topography. ?? 1986 Springer-Verlag.

Simulation of Blast Loading on an Ultrastructurally-based Computational Model of the Ocular Lens

DTIC Science & Technology

2013-10-01

gradient components in the axial ( F22 ) and radial (F11) directions. One can observe the very large deformation (approaching 800%) and 5 Figure 5...and (bottom left) show deformation gradient in axial ( F22 ) and radial (F11) directions. (bottom right) normalized force versus displacement curve for

Applying Modeling and Simulation to Predict Human Injury due to a Blast Attack on a Shipboard Environment

DTIC Science & Technology

2012-10-01

score is also used to assess inca - pacitation using the Military Functional Incapacity Score (MFIS), which characterizes the degree of impairment in...firefighting), are com- pared to any injury impairments (Champion & Lawnick, 2012). Thus, an individual with a sprained ankle will be inca - pacitated if his

Rarefaction Wave Eliminator Concepts For A Large Blast/Thermal Simulator.

DTIC Science & Technology

1985-02-01

hard copies of the pressure-time records. Final data process- ing was completed with the computer, printer , and plotter. Plots of pressure- time records...F ATTN: Prof 0. Zinke Fayetteville, AR 72701 Cdr, CRDC, AMCCOM ATTI: 4O-SPS-IL University of California PM=-J Lawrence Livermore Lab SOM-RSP-A ATTN

International Instrumentation Symposium, 38th, Las Vegas, NV, Apr. 26-30, 1992, Proceedings

NASA Astrophysics Data System (ADS)

The present volume on aerospace instrumentation discusses computer applications, blast and shock, implementation of the Clean Air Act amendments, and thermal systems. Attention is given to measurement uncertainty/flow measurement, data acquisition and processing, force/acceleration/motion measurements, and hypersonics/reentry vehicle systems. Topics addressed include wind tunnels, real time systems, and pressure effects. Also discussed are a distributed data and control system for space simulation and thermal testing a stepwise shockwave velocity determinator, computer tracking and decision making, the use of silicon diodes for detecting the liquid-vapor interface in hydrogen, and practical methods for analysis of uncertainty propagation.