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.

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.

Reduction of 5in./54 Gun Blast Overpressure by Means of an Aqueous Foam- Filled Muzzle Device

DTIC Science & Technology

1981-08-01

aqueous foams have a certain drainage rate that causes the expansion ratio and bubble size to increase progressively. The Rockwood Aquafoam AFFF yields the...NSWC TR 81-128 REDUCTION OF 5"/54 GUN BLAST OVERPRESSURE BY MEANS OF AN AQUEOUS FOAM -FILLED MUZZLE DEVICE by G. STEVENS MILLER RICHARD E. MILLER, JR...128 4. TITLE (ad Subtitle) S. TYPE O r REPORT & PERIOD COVERED REDUCTION OF 5!V54 GUN BLAST OVERPRESSURE Final BY MEANS OF AN AQUEOUS FOAM -FILLED a

[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.

The multipath propagation effect in gunshot acoustics and its impact on the design of sniper positioning systems

NASA Astrophysics Data System (ADS)

Ramos, António L. L.; Holm, Sverre; Gudvangen, Sigmund; Otterlei, Ragnvald

2013-06-01

Counter sniper systems rely on the detection and parameter estimation of the shockwave and the muzzle blast in order to determine the sniper location. In real-world situations, these acoustical signals can be disturbed by natural phenomena like weather and climate conditions, multipath propagation effect, and background noise. While some of these issues have received some attention in recent publications with application to gunshot acoustics, the multipath propagation phenomenon whose effect can not be neglected, specially in urban environments, has not yet been discussed in details in the technical literature in the same context. Propagating sound waves can be reflected at the boundaries in the vicinity of sound sources or receivers, whenever there is a difference in acoustical impedance between the reflective material and the air. Therefore, the received signal can be composed of a direct-path signal plus N scaled delayed copies of that signal. This paper presents a discussion on the multipath propagation effect and its impact on the performance and reliability of sniper positioning systems. In our formulation, propagation models for both the shockwave and the muzzle blast are considered and analyzed. Conclusions following the theoretical analysis of the problem are fully supported by actual gunshots acoustical signatures.

Development of a 3D numerical methodology for fast prediction of gun blast induced loading

NASA Astrophysics Data System (ADS)

Costa, E.; Lagasco, F.

2014-05-01

In this paper, the development of a methodology based on semi-empirical models from the literature to carry out 3D prediction of pressure loading on surfaces adjacent to a weapon system during firing is presented. This loading is consequent to the impact of the blast wave generated by the projectile exiting the muzzle bore. When exceeding a pressure threshold level, loading is potentially capable to induce unwanted damage to nearby hard structures as well as frangible panels or electronic equipment. The implemented model shows the ability to quickly predict the distribution of the blast wave parameters over three-dimensional complex geometry surfaces when the weapon design and emplacement data as well as propellant and projectile characteristics are available. Considering these capabilities, the use of the proposed methodology is envisaged as desirable in the preliminary design phase of the combat system to predict adverse effects and then enable to identify the most appropriate countermeasures. By providing a preliminary but sensitive estimate of the operative environmental loading, this numerical means represents a good alternative to more powerful, but time consuming advanced computational fluid dynamics tools, which use can, thus, be limited to the final phase of the design.

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

Effective direction of arrival estimation of gunshot signals from an in-flight unmanned aerial vehicle

NASA Astrophysics Data System (ADS)

Ribeiro, Juliano G. C.; Serrenho, Felipe G.; Apolinário, José A.; Ramos, António L. L.

2018-04-01

Spotting a shooter from a drone has been the subject of great interest lately due to its many applications in the fields of defense and security and law enforcement. Using a drone can be an effective way to detect potential threats in many real-life scenarios. Nevertheless, acoustic signals recorded from a drone usually exhibit a very low SNR, mainly due to the distance to the source and the proximity of the sensors to the propellers. This is a serious limiting factor and, therefore, the use of signal enhancement techniques is required. This work addresses the problem of determining the Direction-of-Arrival (DoA) of the muzzle blast, captured using a planar microphone array mounted on a commercial DJI PHANTOM 4 drone in flight. This new shooter localization method that relies solely on detecting and estimating the DoA of the muzzle blast. However, the typical low SNR in this scenario requires the use of preprocessing techniques, such as signal clipping and median filtering, to enhance the signal of interest (muzzle blast). In addition, we employ a recently introduced improved data selection DoA estimation method suitable for gunshot signals recorded from a low to medium altitude mobile aerial platform. Positive results achieved indicate that this approach is effective and of practical interest.

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)

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

NASA Astrophysics Data System (ADS)

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

2011-08-01

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

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

PubMed

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

2011-08-01

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

Development and analysis of a leak-based blast attenuator and scaling laws for primary blast peak overpressure for a large caliber muzzleloaded cannon

NASA Astrophysics Data System (ADS)

Carson, Robert Andrew

One of the primary aspects of the research and development work carried out at Benet Laboratories is the Soldier. Maintenance of their health in the field is the first priority while the second priority is the enhancement of their performance. Therefore, a new concept for a weapon system that targets these two priorities is highly desirable. This is the case with a new concept that can reduce the peak overpressure without the use of a muzzle device for a muzzle loaded cannon system. Such a novel concept was developed in this thesis through the application of propellant leak into the precursor region, i.e., when the projectile is still in the bore. A 3D hydrocode (ALE3D) was employed to predict the blast overpressure for the baseline and propellant leak configurations. However, a 3D hydrocode is computationally very expensive to predict peak overpressure in the far-field and an efficient method to predict peak overpressure in the far-field is of significance. Therefore, scaling laws for primary blast peak overpressure were also developed in this thesis. Initially, two propellant leak concepts were examined. A bulge leak method and a channel leak method, which were compared to the baseline configuration. The initial channel leak configuration (referred to as CLM-1) significantly reduced the exit pressure ratio during projectile ejection, and thereby, resulted in a weaker blast. This in-turn substantially attenuated the peak overpressure to the rear of the muzzle without the aid of a muzzle device while having a marginal loss in the projectile exit velocity. For CLM-1, at one monitored location with the largest peak overpressure, a reduction of about 38% in peak overpressure was observed as compared to the baseline case. In order to compare different leak configurations, a performance metric was defined by comparing the ratio of peak overpressure and projectile exit velocity for a leak configuration to that for the baseline configuration. This metric was referred to as the Figure of Merit (FoM) and defined for any probe location. An average FoM was also defined based on the average of local FoM over different locations/probes. The greater the FoM is above zero, the better the configuration. The average FoM for the CLM-1 configuration was 0.221. In addition to FoM, shock structure and strength were also analyzed for the bulge and channel configurations at both the precursor and blast stages. With the success of the CLM-1 configuration, we then performed a parametric study of the channel leak geometry and examined the effect of different geometric parameters on peak overpressure attenuation. The idea was to further improve the performance of the channel leak method. We divided our parametric study into five groups (i.e., A through E), referred to as CLM-A through CLM-E configurations. The focus in these five groups was on geometric parameters that were expected to be the most influential or relevant. Three relevant geometric parameters were considered in this work. In groups A and B, we focused on channel leak volume. Group C analyzed the effect of channel length while groups D and E investigated the effect of aspect ratio. The five groups were ordered in this way because we anticipated the total leak volume to be the most influential parameter, then the channel length which was followed by the aspect ratio. The total leak volume of 7.5% resulted in a relatively high average FoM. On the other hand, the use of channels with a shorter length was found to be detrimental while a lower value of aspect ratio was beneficial. Three leak configurations of CLM-A1, CLM-E1 and CLM-E2 provided excellent peak overpressure attenuation (i.e., above 45% and up to 63%). Each led to an average FoM above 0.5 while CLM-E configurations resulted in lower local FoM for probes near the muzzle and higher FoM for probes farther from the muzzle, and thus, a higher variation of FoM over the probes. The average FoM based on the far-field probes was about 0.575 and 0.560 for CLM-E1 and CLM-E2, respectively, and 0.520 for CLM-A1. Blast structure and strength were also analyzed for these three configurations. In the last part of this thesis, we focused on the baseline and CLM-A1 configurations in order to develop scaling laws for the primary blast peak overpressure. Two different power-law scaling techniques were considered. In the first power-law, scaling parameters were defined from the muzzle center. The second power-law scaling was defined based on the blast center. The muzzle center based power-law has been used in the past while the blast center based power-law is a newly developed scaling law in this thesis. For the baseline configuration, both scaling laws performed well and for many locations absolute difference was below 10%. For the CLM-A1 configuration, blast center based power-law predictions were better than those from the muzzle center based power-law and showed a better overall correlation with the ALE3D predictions.

Airborne DoA estimation of gunshot acoustic signals using drones with application to sniper localization systems

NASA Astrophysics Data System (ADS)

Fernandes, Rigel P.; Ramos, António L. L.; Apolinário, José A.

2017-05-01

Shooter localization systems have been subject of a growing attention lately owing to its wide span of possible applications, e.g., civil protection, law enforcement, and support to soldiers in missions where snipers might pose a serious threat. These devices are based on the processing of electromagnetic or acoustic signatures associated with the firing of a gun. This work is concerned with the latter, where the shooter's position can be obtained based on the estimation of the direction-of-arrival (DoA) of the acoustic components of a gunshot signal (muzzle blast and shock wave). A major limitation of current commercially available acoustic sniper localization systems is the impossibility of finding the shooter's position when one of these acoustic signatures is not detected. This is very likely to occur in real-life situations, especially when the microphones are not in the field of view of the shockwave or when the presence of obstacles like buildings can prevent a direct-path to sensors. This work addresses the problem of DoA estimation of the muzzle blast using a planar array of sensors deployed in a drone. Results supported by actual gunshot data from a realistic setup are very promising and pave the way for the development of enhanced sniper localization systems featuring two main advantages over stationary ones: (1) wider surveillance area; and (2) increased likelihood of a direct-path detection of at least one of the gunshot signals, thereby adding robustness and reliability to the system.

Dynamic pressure measurement of cartridge operated vole captive bolt devices.

PubMed

Frank, M; Philipp, K P; Franke, E; Frank, N; Bockholdt, B; Grossjohann, R; Ekkernkamp, A

2009-01-10

Vole captive bolt devices are powder actuated spring guns that are used as a pest control mean. After having triggered the explosion of the blank cartridge by touching a metal ring around the muzzle, the vole is killed by the massive propulsion of the gas jet. Improper use and recklessness while handling these devices may cause severe injuries with the hand of the operator at particular risk. Currently, there are no experimental investigations on the ballistic background of these devices. An experimental test set-up was designed for measurement of the firing pressure and the dynamic force of the gas jet of a vole captive bolt device. Therefore, a vole captive bolt device was prepared with a pressure take-off channel and a piezoelectric transducer for measurement of the firing pressure. For measurement of the dynamic impact force of the gas jet an annular quartz force sensor was installed on a test bench. Each three simultaneous measurements of the cartridges' firing pressure and the dynamic force of the blast wave were taken at various distances between muzzle and load washer. The maximum gas pressure in the explosion chamber was up to 1100 bar. The shot development over time showed a typical gas pressure curve. Flow velocity of the gas jet was up to 2000 m/s. The maximum impact force of the gas jet at the target showed a strong inverse ratio to the muzzle's distance and was up to 11,500 N for the contact shot distance. Energy density of the gas jet for the close contact shot was far beyond the energy density required for skin penetration. The unique design features (short tube between cartridge mouth and muzzle and narrow diameter of the muzzle) of these gadgets are responsible for the high firing pressure, velocity and force of the gas jet. These findings explain the trauma mechanics of the extensive tissue damage observed in accidental shots of these devices.

Battlefield Acoustic Sensing, Multimodal Sensing, and Networked Sensing for Intelligence, Surveillance, and Reconnaissance (ISR) Applications

DTIC Science & Technology

2015-09-01

seen in Fig. 9, were placed at the rear of the vehicle to minimize the noise and vibration from the engine and its intake and exhaust from the...Specific/unique algorithm approaches attempted and results 4) Observations related to wind noise rejection and/or effects 5) Limitations of technology 6...After a certain time, the muzzle blast is detected, which results from the exit of the munition at the muzzle. Figure 6 shows an example of a single

Method for Determining Artillery Position

NASA Technical Reports Server (NTRS)

Fischer, Johannes; Meuser, Wilfried

1988-01-01

A method is described for determinig artillery positions. Two groups of four closely spaced microphones are placed at known positions, and radio bearings are determined by projectile flight time differences of muzzle blasts. The advantages of the method are discussed.

A multi-band spectral subtraction-based algorithm for real-time noise cancellation applied to gunshot acoustics

NASA Astrophysics Data System (ADS)

Ramos, António L. L.; Holm, Sverre; Gudvangen, Sigmund; Otterlei, Ragnvald

2013-06-01

Acoustical sniper positioning is based on the detection and direction-of-arrival estimation of the shockwave and the muzzle blast acoustical signals. In real-life situations, the detection and direction-of-arrival estimation processes is usually performed under the influence of background noise sources, e.g., vehicles noise, and might result in non-negligible inaccuracies than can affect the system performance and reliability negatively, specially when detecting the muzzle sound under long range distance and absorbing terrains. This paper introduces a multi-band spectral subtraction based algorithm for real-time noise reduction, applied to gunshot acoustical signals. The ballistic shockwave and the muzzle blast signals exhibit distinct frequency contents that are affected differently by additive noise. In most real situations, the noise component is colored and a multi-band spectral subtraction approach for noise reduction contributes to reducing the presence of artifacts in denoised signals. The proposed algorithm is tested using a dataset generated by combining signals from real gunshots and real vehicle noise. The noise component was generated using a steel tracked military tank running on asphalt and includes, therefore, the sound from the vehicle engine, which varies slightly in frequency over time according to the engine's rpm, and the sound from the steel tracks as the vehicle moves.

Use of Foam to Reduce Gun Blast Noise Levels.

DTIC Science & Technology

1981-03-01

conclusively demonstrated that aqueous foam can effect significant (greater than 10 dB) reductions in gun muzzle blast peak sound pressure level...can yield large reductions in airblast noise level. In these experiments, the explosive charge was engulfed in aqueous foam such as that used in fire...within the foam was closely controlled. Coniguration "C" was also quite similar exc, -" !iat ab .. _ 1 gallon of aqueous foam , contained in a 1-mil

Muzzle Blast Amplification

DTIC Science & Technology

1976-11-01

34Acoustic Thermometric Measurements of Propellant Gas Temperatures in Guns," BRL Report 1919, U.S. Army Ballistic Research Laboratory, Aberdeen...M. Schmidt, E. J. Gion, and D. D. Shear, "Acoustic Thermometric Measurements of Propellant Gas Temperatures in Guns," BRL Report 1919, U.S. Army

Method for Determining Artillery Position

NASA Technical Reports Server (NTRS)

Meuser, Wilfried

1988-01-01

A method is described for determining the position of artillery in which a circle of four closely spaced microphones is located at two measurement sites for acoustic radio direction finding of muzzle blasts. A method for determining the position of artillery using this procedure is discussed.

Suppressor for reducing the muzzle blast and flash of a firearm

DOEpatents

Klett, James W

2014-09-30

Disclosed are several examples of apparatuses for suppressing the blast and flash produced as a projectile is expelled by gases from a firearm. In some examples, gases are diverted away from the central chamber to an expansion chamber by baffles. The gases are absorbed by the expansion chamber and desorbed slowly, thus decreasing pressure and increasing residence time of the gases. In other examples, the gases impinge against a plurality of rods before expanding through passages between the rods to decrease the pressure and increase the residence time of the gases.

Laser-Raman Measurements in the Muzzle Blast Region of a 20-mm Cannon

DTIC Science & Technology

1980-08-01

Figs. 5 and 6, the entire spectrometer system was mounted below the laser syste m on the same two-tiered aluminum table which was clamped to the top... Thermometric Measurements of Propellant Gas Temperatures in Guns." AIAA Journal, Vol. 15, No. 2, February 1977, pp. 222-226. 4. Schmidt, E. M., Fansler

Operating Ferret on a patrol boat

NASA Astrophysics Data System (ADS)

Bédard, Jacques

2006-05-01

Ferret is an acoustic system that detects, recognizes and localizes the source and direction of small arms fire. The system comprises a small array of microphones and pressure sensors connected to a standard PC-104 computer that analyzes, displays, reports and logs the parameters of a recognized shot. The system operates by detecting and recognizing the ballistic shock waves created by the supersonic bullet, combined with the muzzle blast wave propagating from the weapon. The system was recently installed and tested on a patrol boat operated by the Royal Canadian Mounted Police (RCMP). An electronic compass with tilt compensation and a GPS was incorporated into the system. This allows the system to correct for the motion of the boat and provide the full coordinates of the shooter. The system also updates the azimuth to the shooter in real time as the boat turns. This paper presents the results of our test and evaluation based on a live firing experiment. Ferret is the result of a collaborative effort by Defence R&D Canada and MacDonald Dettwiler and Associates.

Real-time vehicle noise cancellation techniques for gunshot acoustics

NASA Astrophysics Data System (ADS)

Ramos, Antonio L. L.; Holm, Sverre; Gudvangen, Sigmund; Otterlei, Ragnvald

2012-06-01

Acoustical sniper positioning systems rely on the detection and direction-of-arrival (DOA) estimation of the shockwave and the muzzle blast in order to provide an estimate of a potential snipers location. Field tests have shown that detecting and estimating the DOA of the muzzle blast is a rather difficult task in the presence of background noise sources, e.g., vehicle noise, especially in long range detection and absorbing terrains. In our previous work presented in the 2011 edition of this conference we highlight the importance of improving the SNR of the gunshot signals prior to the detection and recognition stages, aiming at lowering the false alarm and miss-detection rates and, thereby, increasing the reliability of the system. This paper reports on real-time noise cancellation techniques, like Spectral Subtraction and Adaptive Filtering, applied to gunshot signals. Our model assumes the background noise as being short-time stationary and uncorrelated to the impulsive gunshot signals. In practice, relatively long periods without signal occur and can be used to estimate the noise spectrum and its first and second order statistics as required in the spectral subtraction and adaptive filtering techniques, respectively. The results presented in this work are supported with extensive simulations based on real data.

Full-scale high-speed ``Edgerton'' retroreflective shadowgraphy of gunshots

NASA Astrophysics Data System (ADS)

Settles, Gary

2005-11-01

Almost 1/2 century ago, H. E. ``Doc'' Edgerton demonstrated a simple and elegant direct-shadowgraph technique for imaging large-scale events like explosions and gunshots. Only a retroreflective screen, flashlamp illumination, and an ordinary view camera were required. Retroreflective shadowgraphy has seen occasional use since then, but its unique combination of large scale, simplicity and portability has barely been tapped. It functions well in environments hostile to most optical diagnostics, such as full-scale outdoor daylight ballistics and explosives testing. Here, shadowgrams cast upon a 2.4 m square retroreflective screen are imaged by a Photron Fastcam APX-RS digital camera that is capable of megapixel image resolution at 3000 frames/sec up to 250,000 frames/sec at lower resolution. Microsecond frame exposures are used to examine the external ballistics of several firearms, including a high-powered rifle, an AK-47 submachine gun, and several pistols and revolvers. Muzzle blast phenomena and the mechanism of gunpowder residue deposition on the shooter's hands are clearly visualized. In particular, observing the firing of a pistol with and without a silencer (suppressor) suggests that some of the muzzle blast energy is converted by the silencer into supersonic jet noise.

New Diagnostic, Launch and Model Control Techniques in the NASA Ames HFFAF Ballistic Range

NASA Technical Reports Server (NTRS)

Bogdanoff, David W.

2012-01-01

This report presents new diagnostic, launch and model control techniques used in the NASA Ames HFFAF ballistic range. High speed movies were used to view the sabot separation process and the passage of the model through the model splap paper. Cavities in the rear of the sabot, to catch the muzzle blast of the gun, were used to control sabot finger separation angles and distances. Inserts were installed in the powder chamber to greatly reduce the ullage volume (empty space) in the chamber. This resulted in much more complete and repeatable combustion of the powder and hence, in much more repeatable muzzle velocities. Sheets of paper or cardstock, impacting one half of the model, were used to control the amplitudes of the model pitch oscillations.

Wavelet feature extraction for reliable discrimination between high explosive and chemical/biological artillery

NASA Astrophysics Data System (ADS)

Hohil, Myron E.; Desai, Sachi V.; Bass, Henry E.; Chambers, Jim

2005-03-01

Feature extraction methods based on the discrete wavelet transform and multiresolution analysis are used to develop a robust classification algorithm that reliably discriminates between conventional and simulated chemical/biological artillery rounds via acoustic signals produced during detonation. Distinct characteristics arise within the different airburst signatures because high explosive warheads emphasize concussive and shrapnel effects, while chemical/biological warheads are designed to disperse their contents over large areas, therefore employing a slower burning, less intense explosive to mix and spread their contents. The ensuing blast waves are readily characterized by variations in the corresponding peak pressure and rise time of the blast, differences in the ratio of positive pressure amplitude to the negative amplitude, and variations in the overall duration of the resulting waveform. Unique attributes can also be identified that depend upon the properties of the gun tube, projectile speed at the muzzle, and the explosive burn rates of the warhead. In this work, the discrete wavelet transform is used to extract the predominant components of these characteristics from air burst signatures at ranges exceeding 2km. Highly reliable discrimination is achieved with a feedforward neural network classifier trained on a feature space derived from the distribution of wavelet coefficients and higher frequency details found within different levels of the multiresolution decomposition.

Proceedings of the U.S. Army Symposium (Ninth) on Gun Dynamics Held in McLean, Virginia on 17-19 November 1998

DTIC Science & Technology

2000-03-01

Pipe 1 HP Motor Variable Speed Ignition Torch High Density Infrared Heater Sin Bearing Material Feeder Figure 2. Sketch of SHS Centrifugal...the effects of muzzle blast over pressure or how it could be reduced was taken in to account in the formulation of these rules. Since WW2 MB types

Description of FORTRAN Program DAWNA for Analysis of Muzzle Blast Field

DTIC Science & Technology

1976-04-01

meter feet 2/D ! P pressure N/m 2 lb/ft2 00 ’! u velocity m/sec ft/sec u/a» i OO { s entropy m2/sec2 0K ft2/sec2 0R (S...0,KK,i.L/ IPUNCH, IRSTRT, IMOVE , lUNl T, lUNQUT, 18« *** ** HÜUMBHl IFdMOVE. REA0(S,2) READ(5,2

Delay-and-sum beamforming for direction of arrival estimation applied to gunshot acoustics

NASA Astrophysics Data System (ADS)

Ramos, António L. L.; Holm, Sverre; Gudvangen, Sigmund; Otterlei, Ragnvald

2011-06-01

Sniper positioning systems described in the literature use a two-step algorithm to estimate the sniper's location. First, the shockwave and the muzzle blast acoustic signatures must be detected and recognized, followed by an estimation of their respective direction-of-arrival (DOA). Second, the actual sniper's position is calculated based on the estimated DOA via an iterative algorithm that varies from system to system. The overall performance of such a system, however, is highly compromised when the first step is not carried out successfully. Currently available systems rely on a simple calculation of differences of time-of-arrival to estimate angles-of-arrival. This approach, however, lacks robustness by not taking full advantage of the array of sensors. This paper shows how the delay-and-sum beamforming technique can be applied to estimate the DOA for both the shockwave and the muzzle blast. The method has the twofold advantage of 1) adding an array gain of 10 logM, i.e., an increased SNR of 6 dB for a 4-microphone array, which is equivalent to doubling the detection range assuming free-field propagation; and 2) offering improved robustness in handling single- and multi-shots events as well as reflections by taking advantage of the spatial filtering capability.

Shooter position estimation with muzzle blast and shockwave measurements from separate locations

NASA Astrophysics Data System (ADS)

Grasing, David

2016-05-01

There are two acoustical events associated with small arms fire: the muzzle blast (created by bullets being expelled from the barrel of the weapon), and the shockwave (created by bullets which exceed the speed of sound). Assuming the ballistics of a round are known, the times and directions of arrival of the acoustic events furnish sufficient information to determine the origin of the shot. Existing methods tacitly assume that it is a single sensor which makes measurements of the times and direction of arrival. If the sensor is located past the point where the bullet goes transonic or if the sensor is far off the axis of the shot line a single sensor localization become highly inaccurate due to the ill-conditioning of the localization problem. In this paper, a more general approach is taken which allows for localizations from measurements made at separate locations. There are considerable advantages to this approach, the most noteworthy of which is the improvement in localization accuracy due to the improvement in the conditioning of the problem. Additional benefits include: the potential to locate in cases where a single sensor has insufficient information, furnishing high quality initialization to data fusion algorithms, and the potential to identify the round from a set of possible rounds.

Wavenumber-extended high-order oscillation control finite volume schemes for multi-dimensional aeroacoustic computations

NASA Astrophysics Data System (ADS)

Kim, Sungtae; Lee, Soogab; Kim, Kyu Hong

2008-04-01

A new numerical method toward accurate and efficient aeroacoustic computations of multi-dimensional compressible flows has been developed. The core idea of the developed scheme is to unite the advantages of the wavenumber-extended optimized scheme and M-AUSMPW+/MLP schemes by predicting a physical distribution of flow variables more accurately in multi-space dimensions. The wavenumber-extended optimization procedure for the finite volume approach based on the conservative requirement is newly proposed for accuracy enhancement, which is required to capture the acoustic portion of the solution in the smooth region. Furthermore, the new distinguishing mechanism which is based on the Gibbs phenomenon in discontinuity, between continuous and discontinuous regions is introduced to eliminate the excessive numerical dissipation in the continuous region by the restricted application of MLP according to the decision of the distinguishing function. To investigate the effectiveness of the developed method, a sequence of benchmark simulations such as spherical wave propagation, nonlinear wave propagation, shock tube problem and vortex preservation test problem are executed. Also, throughout more realistic shock-vortex interaction and muzzle blast flow problems, the utility of the new method for aeroacoustic applications is verified by comparing with the previous numerical or experimental results.

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.

Uncooled infrared sensors for an integrated sniper location system

NASA Astrophysics Data System (ADS)

Spera, Timothy J.; Figler, Burton D.

1997-02-01

Since July of 1995, Lockheed Martin IR Imaging Systems of Lexington, Massachusetts has been developing an integrated sniper location system for the Advanced Research Projects Agency (ARPA) and for the Department of the Navy's Naval Command Control & Ocean Surveillance Center, RDTE Division in San Diego, California. This system integrates two technologies to provide an affordable and highly effective sniper detection and location capability. The integrated sniper location system is being developed for use by the military and by law enforcement agencies. It will be man portable and can be used by individuals, at fixed ground sites, on ground vehicles, and on low flying aircraft. The integrated sniper location system combines an acoustic warning system with an uncooled infrared warning system. The acoustic warner is being developed by SenTech, Inc. of Lexington, Massachusetts. This acoustic warner provides sniper detection and coarse location information based upon the muzzle blast of the sniper's weapon and/or upon the shock wave produced by the sniper's bullet, if the bullet is supersonic. The uncooled infrared warning system provides sniper detection and fine location information based upon the weapons's muzzle flash. Combining the two technologies improves detection probability and reduces false alarm rate. This paper describes the integrated sniper location system, focusing on the uncooled infrared sensor and its associated signal processing. In addition, preliminary results from Phase I testing of the system are presented. Finally, the paper addresses the plans for implementing Phases II and III, during which the system will be optimized in terms of detection and location performance, size, weight, power, and cost.

On the Propagation and Interaction of Spherical Blast Waves

NASA Technical Reports Server (NTRS)

Kandula, Max; Freeman, Robert

2007-01-01

The characteristics and the scaling laws of isolated spherical blast waves have been briefly reviewed. Both self-similar solutions and numerical solutions of isolated blast waves are discussed. Blast profiles in the near-field (strong shock region) and the far-field (weak shock region) are examined. Particular attention is directed at the blast overpressure and shock propagating speed. Consideration is also given to the interaction of spherical blast waves. Test data for the propagation and interaction of spherical blast waves emanating from explosives placed in the vicinity of a solid propellant stack are presented. These data are discussed with regard to the scaling laws concerning the decay of blast overpressure.

Computer Implementation of a Muzzle Blast Prediction Technique

DTIC Science & Technology

1985-05-01

AVERDEEN PROVING GROUND , MARYLAND • 1y 4 4q* Destroy this report when it is no longer needed. Do not return it to the originator. Additional copies of this...Laboratory AREA & WORK UNIT NUMBERS ATTN: APXBR-LFD Aberdeevi Proving Ground , MD 21005-5066 RDT&E 1LI61102AH43 Ii. CONTROLLING OFFICE NAME AND ADDRESS 12...REPORT DATE !I.S. Army Ballistic Research Laboratory May 1985 ATTN: AMXBR-OD-ST 13. NUMBER OF PAGES Aberdeen Proving Ground , MD. 21005-5066 . 89 14

Muzzle Blast Pressure Loadings upon Aircraft Surfaces

DTIC Science & Technology

1984-02-01

0.02 m Aluminum plate. The plate is instrumented with a linear array of ten piezoelectric pressure transducers, Kistler Model 201B5. The plate is...maintained to insure compatibility of the various sets of 7. E. M. Schmidt, E. J. Gion, and D. D. Shear, "Acoustic Thermometric Measurements of...s -’-’»VA»’ ^I*T^^,*^^T^7.^ MVV-V-VV VV-V-V’-T-^ *7»T REFERENCES 7. E. M. Schmidt, E. J. Gion, and D. D. Shear, "Acoustic Thermometric

The Effect of Propellant Composition on Secondary Muzzle Blast Overpressure

DTIC Science & Technology

1983-04-01

LOVA propellants evaluated included PU/HMX, CTBN /HMX, HTPB/HMX, CAB/RDX, CA/RDX, Kraton/RDX, and EC/NC/RDX. Details of the propellant compositions...RDX tests. Secondary flash was observed for all the firings of all the other candidates, even CTBN /HMX, which had some suppressant. All of these...Propellant Flame Temp (K) Intensity (Mcd) Observations of Flash Kraton/RDX 2283 18.2 ± 1 . 2 11 11 CTBN /HMX 2379 13.8 ± • 72 8 8 HTPB/HMX 2363 10.5

Characterization and Discrimination of Large Caliber Gun Blast and Flash Signatures

DTIC Science & Technology

2011-10-01

from one end of a barrel (the muzzle) by the application of force at the other end. In conventional guns , force is provided by the combustion of a...projectile begins to accelerate down the barrel ; this is known as shot start. As the projectile traverses the gun barrel and additional volume becomes...flash that is used today resulted from this program’s report. Visible and ultraviolet (UV) spectra of 20 mm and .50 caliber machine gun firings were

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.

75 FR 4793 - Availability for Non-Exclusive, Exclusive, or Partially Exclusive Licensing of U.S. Provisional...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-29

... Partially Exclusive Licensing of U.S. Provisional Patent Application Concerning Blast Wave Sensor AGENCY... ``Blast Wave Sensor,'' filed January 4, 2010. The United States Government, as represented by the... wave sensors and their use to detect blast induced pressure changes, and, in particular, a blast wave...

Blast-wave density measurements

NASA Astrophysics Data System (ADS)

Ritzel, D. V.

Applications of a densitometer to obtain time-resolved data on the total density in blast-wave flows are described. A beta-source (promethium-147) is separated by a gap from a scintillator and a photomultiplier tube (PMT). Attenuation of the radiation beam by the passing blast wave is due to the total density in the gap volume during the wave passage. Signal conditioning and filtering methods permit the system to output linearized data. Results are provided from use of the system to monitor blast waves emitted by detonation of a 10.7 m diameter fiberglass sphere containing 609 tons of ammonium nitrate/fuel oil at a 50.6 m height. Blast wave density data are provided for peak overpressure levels of 245, 172 and 70 kPa and distances of 183, 201 and 314 m from ground zero. Data resolution was of high enough quality to encourage efforts to discriminate dust and gasdynamic phenomena within passing blast waves.

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.

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.

Characterization and discrimination of large caliber gun blast and flash signatures

NASA Astrophysics Data System (ADS)

Steward, Bryan J.; Gross, Kevin C.; Perram, Glen P.

2012-06-01

Two hundred and one firings of three 152 mm howitzer munitions were observed to characterize firing signatures of a large caliber gun. Muzzle blast expansion was observed with high-speed (1600 Hz) optical imagery. The trajectory of the blast front was well approximated by a modified point-blast model described by constant rate of energy deposition. Visible and near-infrared (450 - 850 nm) spectra of secondary combustion were acquired at ~0.75 nm spectral resolution and depict strong contaminant emissions including Li, Na, K, Cu, and Ca. The O2 (X-->b) absorption band is evident in the blue wing of the potassium D lines and was used for monocular passive ranging accurate to within 4 - 9%. Timeresolved midwave infrared (1800 - 6000 cm-1) spectra were collected at 100 Hz and 32 cm-1 resolution. A low dimensional radiative transfer model was used to characterize plume emissions in terms of area, temperature, soot emissivity, and species concentrations. Combustion emissions have ~100 ms duration, 1200 - 1600 K temperature, and are dominated by H2O and CO2. Non-combusting plume emissions last ~20 ms, are 850 - 1050 K, and show significant continuum (emissivity ~0.36) and CO structure. Munitions were discriminated with 92 - 96% classification accuracy using only 1 - 3 firing signature features.

Characterization and discrimination of large caliber gun blast and flash signatures

NASA Astrophysics Data System (ADS)

Steward, Bryan J.

Two hundred and one firings of three 152 mm howitzer munitions were observed to characterize firing signatures of a large caliber gun. Muzzle blast expansion was observed with high-speed (1600 Hz) optical imagery. The trajectory of the blast front was well approximated by a modified point-blast model described by constant rate of energy deposition. Visible and near-infrared (450--850 nm) spectra of secondary combustion were acquired at ˜0.75 nm spectral resolution and depict strong contaminant emissions including Li, Na, K, Cu, and Ca. The O2 (X→b) absorption band is evident in the blue wing of the potassium D lines and was used for monocular passive ranging accurate to within 4--9%. Time-resolved midwave infrared (1800--6000 cm-1) spectra were collected at 100 Hz and 32 cm-1 resolution. A low dimensional radiative transfer model was used to characterize plume emissions in terms of area, temperature, soot emissivity, and species concentrations. Combustion emissions have ~100 ms duration, 1200--1600 K temperature, and are dominated by H2O and CO2. Non-combusting plume emissions last ~20 ms, are 850--1050 K, and show significant continuum (emissivity ˜0.36) and CO structure. Munitions were discriminated with 92--96% classification accuracy using only 1--3 firing signature features.

Translational Research for Blast-Induced Traumatic Brain Injury: Injury Mechanism to Development of Medical Instruments

NASA Astrophysics Data System (ADS)

Nakagawa, A.; Ohtani, K.; Arafune, T.; Washio, T.; Iwasaki, M.; Endo, T.; Ogawa, Y.; Kumabe, T.; Takayama, K.; Tominaga, T.

1. Investigation of shock wave-induced phenomenon: blast-induced traumatic brain injury Blast wave (BW) is generated by explosion and is comprised of lead shock wave (SE) followed by subsequent supersonic flow.

Instability of Taylor-Sedov blast waves propagating through a uniform gas

NASA Astrophysics Data System (ADS)

Grun, J.; Stamper, J.; Manka, C.; Resnick, J.; Burris, R.; Crawford, J.; Ripin, B. H.

1991-05-01

An instability in Taylor-Sedov blast waves was measured as the waves propagated through a uniform gas with a low adiabatic index. The first measurements of the instability are given and compared to theoretical predictions. The classical Taylor-Sedov blast waves resulted from the expansion of ablation plasma into an ambient gas from laser-irradiated foils, and photographs were taken using the dark-field imaging method. Visible emission from the blasts were recorded with a four-frame microchannel-plate intensifier camera. Blast waves formed in nitrogen gas are shown to be stable and smooth, whereas the waves propagating through xenon gas are found to be unstable and wrinkled. A power law is fitted to the experimental data, and the adiabatic indices are theorized to cause the different responses in the two gases. The results generally agree with theoretical predictions in spite of some minor discrepancies, and an explanation of the instability mechanism is developed. When the adiabatic index is sufficiently low, the Taylor-Sedov blast waves in a uniform gas will be unstable, and the perturbed amplitudes will grow as a power of time.

The effect of firearm muzzle gases on the backspatter of blood.

PubMed

Taylor, Michael C; Laber, Terry L; Epstein, Barton P; Zamzow, Dan S; Baldwin, David P

2011-09-01

Injuries caused by gunshots can produce what bloodstain pattern analysts know as "backspatter." Observations about the presence or absence of backspatter on an individual may be used in court as evidence of guilt or innocence. The discharge of three firearms (.22 caliber revolver, .38 caliber revolver, and .308 caliber rifle) and the resulting impact of bullets on a blood source were recorded using high-speed digital video imaging. Blood droplets, firearm muzzle gases, and ballistic shock waves were visualized using standard reflected light and shadowgraphy imaging techniques. A significant interaction between air currents, muzzle gases, and particulate material emanating from the firearms upon discharge with backspattered blood was observed. Blood droplets, initially spattered back toward the firearm and the shooter, were observed to change direction under the influence of firearm-induced air currents and were blown forward toward and beyond their original source location. Implications for experts testifying in court and for bloodstain pattern instructors are discussed.

The Effect of Firearm Muzzle Gases on the Backspatter of Blood

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

Taylor, M.C.; Laber, T.L.; Epstein, B.P.

2010-05-12

Injuries caused by gunshots can produce what bloodstain pattern analysts know as 'backspatter.' Observations about the presence or absence of backspatter on an individual may be used in court as evidence of guilt or innocence. The discharge of three firearms (.22 caliber revolver, .38 caliber revolver, and .308 caliber rifle) and the resulting impact of bullets on a blood source were recorded using high-speed digital video imaging. Blood droplets, firearm muzzle gases, and ballistic shock waves were visualized using standard reflected light and shadowgraphy imaging techniques. A significant interaction between air currents, muzzle gases, and particulate material emanating from themore » firearms upon discharge with backspattered blood was observed. Blood droplets, initially spattered back toward the firearm and the shooter, were observed to change direction under the influence of firearm-induced air currents and were blown forward toward and beyond their original source location. Implications for experts testifying in court and for bloodstain pattern instructors are discussed.« less

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.

Characterising the acceleration phase of blast wave formation

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

Fox, T. E., E-mail: tef503@york.ac.uk; Pasley, J.; Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX

2014-10-15

Intensely heated, localised regions in uniform fluids will rapidly expand and generate an outwardly propagating blast wave. The Sedov-Taylor self-similar solution for such blast waves has long been studied and applied to a variety of scenarios. A characteristic time for their formation has also long been identified using dimensional analysis, which by its very nature, can offer several interpretations. We propose that, rather than simply being a characteristic time, it may be interpreted as the definitive time taken for a blast wave resulting from an intense explosion in a uniform media to contain its maximum kinetic energy. A scaling relationmore » for this measure of the acceleration phase, preceding the establishment of the blast wave, is presented and confirmed using a 1D planar hydrodynamic model.« less

Suspended liquid particle disturbance on laser-induced blast wave and low density distribution

NASA Astrophysics Data System (ADS)

Ukai, Takahiro; Zare-Behtash, Hossein; Kontis, Konstantinos

2017-12-01

The impurity effect of suspended liquid particles on the laser-induced gas breakdown was experimentally investigated in quiescent gas. The focus of this study is the investigation of the influence of the impurities on the shock wave structure as well as the low density distribution. A 532 nm Nd:YAG laser beam with an 188 mJ/pulse was focused on the chamber filled with suspended liquid particles 0.9 ± 0.63 μm in diameter. Several shock waves are generated by multiple gas breakdowns along the beam path in the breakdown with particles. Four types of shock wave structures can be observed: (1) the dual blast waves with a similar shock radius, (2) the dual blast waves with a large shock radius at the lower breakdown, (3) the dual blast waves with a large shock radius at the upper breakdown, and (4) the triple blast waves. The independent blast waves interact with each other and enhance the shock strength behind the shock front in the lateral direction. The triple blast waves lead to the strongest shock wave in all cases. The shock wave front that propagates toward the opposite laser focal spot impinges on one another, and thereafter a transmitted shock wave (TSW) appears. The TSW interacts with the low density core called a kernel; the kernel then longitudinally expands quickly due to a Richtmyer-Meshkov-like instability. The laser-particle interaction causes an increase in the kernel volume which is approximately five times as large as that in the gas breakdown without particles. In addition, the laser-particle interaction can improve the laser energy efficiency.

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.

Improved integrated sniper location system

NASA Astrophysics Data System (ADS)

Figler, Burton D.; Spera, Timothy J.

1999-01-01

In July of 1995, Lockheed Martin IR Imaging Systems, of Lexington, Massachusetts began the development of an integrated sniper location system for the Defense Advanced Research Projects Agency and for the Department of the Navy's Naval Command Control & Ocean Surveillance Center, RDTE Division in San Diego, California. The I-SLS integrates acoustic and uncooled infrared sensing technologies to provide an affordable and highly effective sniper detection and location capability. This system, its performance and results from field tests at Camp Pendleton, California, in October 1996 were described in a paper presented at the November 1996 SPIE Photonics East Symposium1 on Enabling Technologies for Law Enforcement and Security. The I-SLS combines an acoustic warning system with an uncooled infrared warning system. The acoustic warning system has been developed by SenTech, Inc., of Lexington, Massachusetts. This acoustic warning system provides sniper detection and coarse location information based upon the muzzle blast of the sniper's weapon and/or upon the shock wave produced by the sniper's bullet, if the bullet is supersonic. The uncooled infrared warning system provides sniper detection and fine location information based upon the weapon's muzzle flash. In addition, the uncooled infrared warning system can provide thermal imagery that can be used to accurately locate and identify the sniper. Combining these two technologies improves detection probability, reduces false alarm rate and increases utility. In the two years since the last report of the integrated sniper location system, improvements have been made and a second field demonstration was planned. In this paper, we describe the integrated sniper location system modifications in preparation for the new field demonstration. In addition, fundamental improvements in the uncooled infrared sensor technology continue to be made. These improvements include higher sensitivity (lower minimum resolvable temperature), higher spatial resolution, and smaller size. This paper will describe the implementation and status of these improvements.

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.

On the Interaction and Coalescence if Spherical Blast Waves

NASA Technical Reports Server (NTRS)

Kandula, Max; Freeman, Robert J.

2005-01-01

The scaling and similarity laws concerning the propagation of isolated spherical blast waves are briefly reviewed. Both point source explosions and high pressure gas explosions are considered. Test data on blast overpressure from the interaction and coalescence of spherical blast waves emanating from explosives in the form of shaped charges of different strength placed in the vicinity of a solid propellant stack are presented. These data are discussed with regard to the scaling laws concerning the decay of blast overpressure. The results point out the possibility of detecting source explosions from far-field pressure measurements.

Dynamics and Afterglow Light Curves of Gamma-Ray Burst Blast Waves Encountering a Density Bump or Void

NASA Astrophysics Data System (ADS)

Uhm, Z. Lucas; Zhang, Bing

2014-07-01

We investigate the dynamics and afterglow light curves of gamma-ray burst blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the characteristic response features that each type of density structure in the medium leaves on the forward shock (FS) and reverse shock (RS) dynamics for blast waves with either a long-lived or short-lived RS. We show that when the ambient medium density drops, the blast waves exhibit in some cases a period of an actual acceleration (even during their deceleration stage) due to adiabatic cooling of blast waves. Comparing numerical examples that have different shapes of bumps or voids, we propose a number of consistency tests that must be satisfied by correct modeling of blast waves. Our model results successfully pass these tests. Employing a Lagrangian description of blast waves, we perform a sophisticated calculation of afterglow emission. We show that as a response to density structures in the ambient medium, the RS light curves produce more significant variations than the FS light curves. Some observed features (such as rebrightenings, dips, or slow wiggles) can be more easily explained within the RS model. We also discuss the origin of these different features imprinted on the FS and RS light curves.

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.

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

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

Taylor, Paul Allen; Ford, Corey C.

U.S. soldiers are surviving blast and impacts due to effective body armor, trauma evacuation and care. Blast injuries are the leading cause of traumatic brain injury (TBI) in military personnel returning from combat. Understanding of Primary Blast Injury may be needed to develop better means of blast mitigation strategies. The objective of this paper is to investigate the effects of blast direction and strength on the resulting mechanical stress and wave energy distributions generated in the brain.

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.

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.

Stepwise shockwave velocity determinator

NASA Technical Reports Server (NTRS)

Roth, Timothy E.; Beeson, Harold

1992-01-01

To provide an uncomplicated and inexpensive method for measuring the far-field velocity of a surface shockwave produced by an explosion, a stepwise shockwave velocity determinator (SSVD) was developed. The velocity determinator is constructed of readily available materials and works on the principle of breaking discrete sensors composed of aluminum foil contacts. The discrete sensors have an average breaking threshold of approximately 7 kPa. An incremental output step of 250 mV is created with each foil contact breakage and is logged by analog-to-digital instrumentation. Velocity data obtained from the SSVD is within approximately 11 percent of the calculated surface shockwave velocity of a muzzle blast from a 30.06 rifle.

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

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

Jackson, Scott L

2011-01-25

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

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.

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

Challenging Some Contemporary Views of Coronal Mass Ejections. I. The Case for Blast Waves

NASA Astrophysics Data System (ADS)

Howard, T. A.; Pizzo, V. J.

2016-06-01

Since the closure of the “solar flare myth” debate in the mid-1990s, a specific narrative of the nature of coronal mass ejections (CMEs) has been widely accepted by the solar physics community. This narrative describes structured magnetic flux ropes at the CME core that drive the surrounding field plasma away from the Sun. This narrative replaced the “traditional” view that CMEs were blast waves driven by solar flares. While the flux rope CME narrative is supported by a vast quantity of measurements made over five decades, it does not adequately describe every observation of what have been termed CME-related phenomena. In this paper we present evidence that some large-scale coronal eruptions, particularly those associated with EIT waves, exhibit characteristics that are more consistent with a blast wave originating from a localized region (such as a flare site) rather than a large-scale structure driven by an intrinsic flux rope. We present detailed examples of CMEs that are suspected blast waves and flux ropes, and show that of our small sample of 22 EIT-wave-related CMEs, 91% involve a blast wave as at least part of the eruption, and 50% are probably blast waves exclusively. We conclude with a description of possible signatures to look for in determining the difference between the two types of CMEs and with a discussion on modeling efforts to explore this possibility.

Study of Perturbations on High Mach Number Blast Waves in Various Gasses

NASA Astrophysics Data System (ADS)

Edens, A.; Adams, R.; Rambo, P.; Shores, J.; Smith, I.; Atherton, B.; Ditmire, T.

2006-10-01

We have performed a series of experiments examining the properties of high Mach number blast waves. Experiments were conducted on the Z-Beamlet^1 laser at Sandia National Laboratories. We created blast waves in the laboratory by using 10 J- 1000 J laser pulses to illuminate millimeter scale solid targets immersed in gas. Our experiments studied the validity of theories forwarded by Vishniac and Ryu^2-4 to explain the dynamics of perturbations on astrophysical blast waves. These experiments consisted of an examination of the evolution of perturbations of known primary mode number induced on the surface of blast waves by means of regularly spaced wire arrays. The temporal evolution of the amplitude of the induced perturbations relative to the mean radius of the blast wave was fit to a power law in time. Measurements were taken for a number of different mode numbers and background gasses and the results show qualitative agreement with previously published theories for the hydrodynamics of thin shell blast wave. The results for perturbations on nitrogen gas have been recently published^5. .^1 P. K. Rambo, I. C. Smith, J. L. Porter, et al., Applied Optics 44, 2421 (2005). ^2 D. Ryu and E. T. Vishniac, Astrophysical Journal 313, 820 (1987). ^3 D. Ryu and E. T. Vishniac, Astrophysical Journal 368, 411 (1991). ^4 E. T. Vishniac, Astrophysical Journal 274, 152 (1983). ^5 A. D. Edens, T. Ditmire, J. F. Hansen, et al., Physical Review Letters 95 (2005).

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.

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.

A Multi-Mode Shock Tube for Investigation of Blast-Induced Traumatic Brain Injury

PubMed Central

Reneer, Dexter V.; Hisel, Richard D.; Hoffman, Joshua M.; Kryscio, Richard J.; Lusk, Braden T.

2011-01-01

Abstract Blast-induced mild traumatic brain injury (bTBI) has become increasingly common in recent military conflicts. The mechanisms by which non-impact blast exposure results in bTBI are incompletely understood. Current small animal bTBI models predominantly utilize compressed air-driven membrane rupture as their blast wave source, while large animal models use chemical explosives. The pressure-time signature of each blast mode is unique, making it difficult to evaluate the contributions of the different components of the blast wave to bTBI when using a single blast source. We utilized a multi-mode shock tube, the McMillan blast device, capable of utilizing compressed air- and compressed helium-driven membrane rupture, and the explosives oxyhydrogen and cyclotrimethylenetrinitramine (RDX, the primary component of C-4 plastic explosives) as the driving source. At similar maximal blast overpressures, the positive pressure phase of compressed air-driven blasts was longer, and the positive impulse was greater, than those observed for shockwaves produced by other driving sources. Helium-driven shockwaves more closely resembled RDX blasts, but by displacing air created a hypoxic environment within the shock tube. Pressure-time traces from oxyhydrogen-driven shockwaves were very similar those produced by RDX, although they resulted in elevated carbon monoxide levels due to combustion of the polyethylene bag used to contain the gases within the shock tube prior to detonation. Rats exposed to compressed air-driven blasts had more pronounced vascular damage than those exposed to oxyhydrogen-driven blasts of the same peak overpressure, indicating that differences in blast wave characteristics other than peak overpressure may influence the extent of bTBI. Use of this multi-mode shock tube in small animal models will enable comparison of the extent of brain injury with the pressure-time signature produced using each blast mode, facilitating evaluation of the blast wave components contributing to bTBI. PMID:21083431

A multi-mode shock tube for investigation of blast-induced traumatic brain injury.

PubMed

Reneer, Dexter V; Hisel, Richard D; Hoffman, Joshua M; Kryscio, Richard J; Lusk, Braden T; Geddes, James W

2011-01-01

Blast-induced mild traumatic brain injury (bTBI) has become increasingly common in recent military conflicts. The mechanisms by which non-impact blast exposure results in bTBI are incompletely understood. Current small animal bTBI models predominantly utilize compressed air-driven membrane rupture as their blast wave source, while large animal models use chemical explosives. The pressure-time signature of each blast mode is unique, making it difficult to evaluate the contributions of the different components of the blast wave to bTBI when using a single blast source. We utilized a multi-mode shock tube, the McMillan blast device, capable of utilizing compressed air- and compressed helium-driven membrane rupture, and the explosives oxyhydrogen and cyclotrimethylenetrinitramine (RDX, the primary component of C-4 plastic explosives) as the driving source. At similar maximal blast overpressures, the positive pressure phase of compressed air-driven blasts was longer, and the positive impulse was greater, than those observed for shockwaves produced by other driving sources. Helium-driven shockwaves more closely resembled RDX blasts, but by displacing air created a hypoxic environment within the shock tube. Pressure-time traces from oxyhydrogen-driven shockwaves were very similar those produced by RDX, although they resulted in elevated carbon monoxide levels due to combustion of the polyethylene bag used to contain the gases within the shock tube prior to detonation. Rats exposed to compressed air-driven blasts had more pronounced vascular damage than those exposed to oxyhydrogen-driven blasts of the same peak overpressure, indicating that differences in blast wave characteristics other than peak overpressure may influence the extent of bTBI. Use of this multi-mode shock tube in small animal models will enable comparison of the extent of brain injury with the pressure-time signature produced using each blast mode, facilitating evaluation of the blast wave components contributing to bTBI.

Fly-ear inspired acoustic sensors for gunshot localization

NASA Astrophysics Data System (ADS)

Liu, Haijun; Currano, Luke; Gee, Danny; Yang, Benjamin; Yu, Miao

2009-05-01

The supersensitive ears of the parasitoid fly Ormia ochracea have inspired researchers to develop bio-inspired directional microphone for sound localization. Although the fly ear is optimized for localizing the narrow-band calling song of crickets at 5 kHz, experiments and simulation have shown that it can amplify directional cues for a wide frequency range. In this article, a theoretical investigation is presented to study the use of fly-ear inspired directional microphones for gunshot localization. Using an equivalent 2-DOF model of the fly ear, the time responses of the fly ear structure to a typical shock wave are obtained and the associated time delay is estimated by using cross-correlation. Both near-field and far-field scenarios are considered. The simulation shows that the fly ear can greatly amplify the time delay by ~20 times, which indicates that with an interaural distance of only 1.2 mm the fly ear is able to generate a time delay comparable to that obtained by a conventional microphone pair with a separation as large as 24 mm. Since the parameters of the fly ear structure can also be tuned for muzzle blast and other impulse stimulus, fly-ear inspired acoustic sensors offers great potential for developing portable gunshot localization systems.

DARPA counter-sniper program: Phase 1 Acoustic Systems Demonstration results

NASA Astrophysics Data System (ADS)

Carapezza, Edward M.; Law, David B.; Csanadi, Christina J.

1997-02-01

During October 1995 through May 1996, the Defense Advanced Research Projects Agency sponsored the development of prototype systems that exploit acoustic muzzle blast and ballistic shock wave signatures to accurately predict the location of gunfire events and associated shooter locations using either single or multiple volumetric arrays. The output of these acoustic systems is an estimate of the shooter location and a classification estimate of the caliber of the shooter's weapon. A portable display and control unit provides both graphical and alphanumeric shooter location related information integrated on a two- dimensional digital map of the defended area. The final Phase I Acoustic Systems Demonstration field tests were completed in May. These these tests were held at USMC Base Camp Pendleton Military Operations Urban Training (MOUT) facility. These tests were structured to provide challenging gunfire related scenarios with significant reverberation and multi-path conditions. Special shot geometries and false alarms were included in these tests to probe potential system vulnerabilities and to determine the performance and robustness of the systems. Five prototypes developed by U.S. companies and one Israeli developed prototype were tested. This analysis quantifies the spatial resolution estimation capability (azimuth, elevation and range) of these prototypes and describes their ability to accurately classify the type of bullet fired in a challenging urban- like setting.

Dynamics and afterglow light curves of gamma-ray burst blast waves encountering a density bump or void

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

Uhm, Z. Lucas; Zhang, Bing, E-mail: uhm@pku.edu.cn, E-mail: zhang@physics.unlv.edu

2014-07-01

We investigate the dynamics and afterglow light curves of gamma-ray burst blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the characteristic response features that each type of density structure in the medium leaves on the forward shock (FS) and reverse shock (RS) dynamics for blast waves with either a long-lived or short-lived RS. We show that when the ambient medium density drops, the blast waves exhibit in some cases a period of an actual acceleration (even during their deceleration stage) due to adiabatic cooling of blastmore » waves. Comparing numerical examples that have different shapes of bumps or voids, we propose a number of consistency tests that must be satisfied by correct modeling of blast waves. Our model results successfully pass these tests. Employing a Lagrangian description of blast waves, we perform a sophisticated calculation of afterglow emission. We show that as a response to density structures in the ambient medium, the RS light curves produce more significant variations than the FS light curves. Some observed features (such as rebrightenings, dips, or slow wiggles) can be more easily explained within the RS model. We also discuss the origin of these different features imprinted on the FS and RS light curves.« less

POLYCYCLIC AROMATIC HYDROCARBON PROCESSING IN THE BLAST WAVE OF THE SUPERNOVA REMNANT N132D

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

Tappe, A.; Rho, J.; Boersma, C.

2012-08-01

We present Spitzer Infrared Spectrograph 14-36 {mu}m mapping observations of the supernova remnant N132D in the Large Magellanic Cloud. This study focuses on the processing of polycyclic aromatic hydrocarbons (PAHs) that we previously identified in the southern blast wave. The mid-infrared spectra show strong continuum emission from shock-heated dust and a unique, nearly featureless plateau in the 15-20 {mu}m region, which we attribute to PAH molecules. The typical PAH emission bands observed in the surrounding interstellar medium ahead of the blast wave disappear, which indicates shock processing of PAH molecules. The PAH plateau appears most strongly at the outer edgemore » of the blast wave and coincides with diffuse X-ray emission that precedes the brightest X-ray and optical filaments. This suggests that PAH molecules in the surrounding medium are swept up and processed in the hot gas of the blast wave shock, where they survive the harsh conditions long enough to be detected. We also observe a broad emission feature at 20 {mu}m appearing with the PAH plateau. We speculate that this feature is either due to FeO dust grains or connected to the processing of PAHs in the supernova blast wave shock.« less

CHALLENGING SOME CONTEMPORARY VIEWS OF CORONAL MASS EJECTIONS. I. THE CASE FOR BLAST WAVES

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

Howard, T. A.; Pizzo, V. J., E-mail: howard@boulder.swri.edu

Since the closure of the “solar flare myth” debate in the mid-1990s, a specific narrative of the nature of coronal mass ejections (CMEs) has been widely accepted by the solar physics community. This narrative describes structured magnetic flux ropes at the CME core that drive the surrounding field plasma away from the Sun. This narrative replaced the “traditional” view that CMEs were blast waves driven by solar flares. While the flux rope CME narrative is supported by a vast quantity of measurements made over five decades, it does not adequately describe every observation of what have been termed CME-related phenomena.more » In this paper we present evidence that some large-scale coronal eruptions, particularly those associated with EIT waves, exhibit characteristics that are more consistent with a blast wave originating from a localized region (such as a flare site) rather than a large-scale structure driven by an intrinsic flux rope. We present detailed examples of CMEs that are suspected blast waves and flux ropes, and show that of our small sample of 22 EIT-wave-related CMEs, 91% involve a blast wave as at least part of the eruption, and 50% are probably blast waves exclusively. We conclude with a description of possible signatures to look for in determining the difference between the two types of CMEs and with a discussion on modeling efforts to explore this possibility.« less

Reliable classification of high explosive and chemical/biological artillery using acoustic sensors

NASA Astrophysics Data System (ADS)

Desai, Sachi V.; Hohil, Myron E.; Bass, Henry E.; Chambers, Jim

2005-05-01

Feature extraction methods based on the discrete wavelet transform and multiresolution analysis are used to develop a robust classification algorithm that reliably discriminates between conventional and simulated chemical/biological artillery rounds via acoustic signals produced during detonation utilizing a generic acoustic sensor. Based on the transient properties of the signature blast distinct characteristics arise within the different acoustic signatures because high explosive warheads emphasize concussive and shrapnel effects, while chemical/biological warheads are designed to disperse their contents over large areas, therefore employing a slower burning, less intense explosive to mix and spread their contents. The ensuing blast waves are readily characterized by variations in the corresponding peak pressure and rise time of the blast, differences in the ratio of positive pressure amplitude to the negative amplitude, and variations in the overall duration of the resulting waveform. Unique attributes can also be identified that depend upon the properties of the gun tube, projectile speed at the muzzle, and the explosive burn rates of the warhead. The algorithm enables robust classification of various airburst signatures using acoustics. It is capable of being integrated within an existing chemical/biological sensor, a stand-alone generic sensor, or a part of a disparate sensor suite. When emplaced in high-threat areas, this added capability would further provide field personal with advanced battlefield knowledge without the aide of so-called "sniffer" sensors that rely upon air particle information based on direct contact with possible contaminated air. In this work, the discrete wavelet transform is used to extract the predominant components of these characteristics from air burst signatures at ranges exceeding 2km while maintaining temporal sequence of the data to keep relevance to the transient differences of the airburst signatures. Highly reliable discrimination is achieved with a feedforward neural network classifier trained on a feature space derived from the distribution of wavelet coefficients and higher frequency details found within different levels of the multiresolution decomposition the neural network then is capable of classifying new airburst signatures as Chemical/Biological or High Explosive.

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.

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.

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.

In silico investigation of intracranial blast mitigation with relevance to military traumatic brain injury.

PubMed

Nyein, Michelle K; Jason, Amanda M; Yu, Li; Pita, Claudio M; Joannopoulos, John D; Moore, David F; Radovitzky, Raul A

2010-11-30

Blast-induced traumatic brain injury is the most prevalent military injury in Iraq and Afghanistan, yet little is known about the mechanical effects of blasts on the human head, and still less is known about how personal protective equipment affects the brain's response to blasts. In this study we investigated the effect of the Advanced Combat Helmet (ACH) and a conceptual face shield on the propagation of stress waves within the brain tissue following blast events. We used a sophisticated computational framework for simulating coupled fluid-solid dynamic interactions and a three-dimensional biofidelic finite element model of the human head and intracranial contents combined with a detailed model of the ACH and a conceptual face shield. Simulations were conducted in which the unhelmeted head, head with helmet, and head with helmet and face shield were exposed to a frontal blast wave with incident overpressure of 10 atm. Direct transmission of stress waves into the intracranial cavity was observed in the unprotected head and head with helmet simulations. Compared to the unhelmeted head, the head with helmet experienced slight mitigation of intracranial stresses. This suggests that the existing ACH does not significantly contribute to mitigating blast effects, but does not worsen them either. By contrast, the helmet and face shield combination impeded direct transmission of stress waves to the face, resulting in a delay in the transmission of stresses to the intracranial cavity and lower intracranial stresses. This suggests a possible strategy for mitigating blast waves often associated with military concussion.

In silico investigation of intracranial blast mitigation with relevance to military traumatic brain injury

PubMed Central

Nyein, Michelle K.; Jason, Amanda M.; Yu, Li; Pita, Claudio M.; Joannopoulos, John D.; Moore, David F.; Radovitzky, Raul A.

2010-01-01

Blast-induced traumatic brain injury is the most prevalent military injury in Iraq and Afghanistan, yet little is known about the mechanical effects of blasts on the human head, and still less is known about how personal protective equipment affects the brain’s response to blasts. In this study we investigated the effect of the Advanced Combat Helmet (ACH) and a conceptual face shield on the propagation of stress waves within the brain tissue following blast events. We used a sophisticated computational framework for simulating coupled fluid–solid dynamic interactions and a three-dimensional biofidelic finite element model of the human head and intracranial contents combined with a detailed model of the ACH and a conceptual face shield. Simulations were conducted in which the unhelmeted head, head with helmet, and head with helmet and face shield were exposed to a frontal blast wave with incident overpressure of 10 atm. Direct transmission of stress waves into the intracranial cavity was observed in the unprotected head and head with helmet simulations. Compared to the unhelmeted head, the head with helmet experienced slight mitigation of intracranial stresses. This suggests that the existing ACH does not significantly contribute to mitigating blast effects, but does not worsen them either. By contrast, the helmet and face shield combination impeded direct transmission of stress waves to the face, resulting in a delay in the transmission of stresses to the intracranial cavity and lower intracranial stresses. This suggests a possible strategy for mitigating blast waves often associated with military concussion. PMID:21098257

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

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

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.

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

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.

An investigation of a reticulated foam - perforated steel sheet combination as a blast mitigation structure

NASA Astrophysics Data System (ADS)

Nguyen, Thuy-Tien N.; Proud, William G.

2017-01-01

Explosions are one of the main causes of injuries during battles and conflicts, with improvised explosive devices (IEDs) becoming increasingly common. Blast waves produced from such explosions can inflict very complex injuries on human and serious damage to structures. Here, the interaction between blast waves and sandwich structures of reticulated foam and perforated sheets is studied using a shock tube. The level of mitigation for primary blast injuries of these structures are discussed in terms of pulse shape, pressure magnitude and impulse. Schlieren photography and other high-speed imaging were used to capture the form of the blast wave. The results show up to 95% mitigation in both pressure and impulse with the structures studied. The behaviors of these mitigating sandwich panels under two loadings, Mach 2.0 and Mach 2.6, are also discussed.

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

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.

Lasting Retinal Injury in a Mouse Model of Blast-Induced Trauma.

PubMed

Mammadova, Najiba; Ghaisas, Shivani; Zenitsky, Gary; Sakaguchi, Donald S; Kanthasamy, Anumantha G; Greenlee, Justin J; West Greenlee, M Heather

2017-07-01

Traumatic brain injury due to blast exposure is currently the most prevalent of war injuries. Although secondary ocular blast injuries due to flying debris are more common, primary ocular blast exposure resulting from blast wave pressure has been reported among survivors of explosions, but with limited understanding of the resulting retinal pathologies. Using a compressed air-driven shock tube system, adult male and female C57BL/6 mice were exposed to blast wave pressure of 300 kPa (43.5 psi) per day for 3 successive days, and euthanized 30 days after injury. We assessed retinal tissues using immunofluorescence for glial fibrillary acidic protein, microglia-specific proteins Iba1 and CD68, and phosphorylated tau (AT-270 pThr181 and AT-180 pThr231). Primary blast wave pressure resulted in activation of Müller glia, loss of photoreceptor cells, and an increase in phosphorylated tau in retinal neurons and glia. We found that 300-kPa blasts yielded no detectable cognitive or motor deficits, and no neurochemical or biochemical evidence of injury in the striatum or prefrontal cortex, respectively. These changes were detected 30 days after blast exposure, suggesting the possibility of long-lasting retinal injury and neuronal inflammation after primary blast exposure. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Estimate of the influence of muzzle smoke on function range of infrared system

NASA Astrophysics Data System (ADS)

Luo, Yan-ling; Wang, Jun; Wu, Jiang-hui; Wu, Jun; Gao, Meng; Gao, Fei; Zhao, Yu-jie; Zhang, Lei

2013-09-01

Muzzle smoke produced by weapons shooting has important influence on infrared (IR) system while detecting targets. Based on the theoretical model of detecting spot targets and surface targets of IR system while there is muzzle smoke, the function range for detecting spot targets and surface targets are deduced separately according to the definition of noise equivalent temperature difference(NETD) and minimum resolution temperature difference(MRTD). Also parameters of muzzle smoke affecting function range of IR system are analyzed. Base on measured data of muzzle smoke for single shot, the function range of an IR system for detecting typical targets are calculated separately while there is muzzle smoke and there is no muzzle smoke at 8-12 micron waveband. For our IR system function range has reduced by over 10% for detecting tank if muzzle smoke exists. The results will provide evidence for evaluating the influence of muzzle smoke on IR system and will help researchers to improve ammo craftwork.

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

Stress Wave Interaction Between Two Adjacent Blast Holes

NASA Astrophysics Data System (ADS)

Yi, Changping; Johansson, Daniel; Nyberg, Ulf; Beyglou, Ali

2016-05-01

Rock fragmentation by blasting is determined by the level and state of stress in the rock mass subjected to blasting. With the application of electronic detonators, some researchers stated that it is possible to achieve improved fragmentation through stress wave superposition with very short delay times. This hypothesis was studied through theoretical analysis in the paper. First, the stress in rock mass induced by a single-hole shot was analyzed with the assumptions of infinite velocity of detonation and infinite charge length. Based on the stress analysis of a single-hole shot, the stress history and tensile stress distribution between two adjacent holes were presented for cases of simultaneous initiation and 1 ms delayed initiation via stress superposition. The results indicated that the stress wave interaction is local around the collision point. Then, the tensile stress distribution at the extended line of two adjacent blast holes was analyzed for a case of 2 ms delay. The analytical results showed that the tensile stress on the extended line increases due to the stress wave superposition under the assumption that the influence of neighboring blast hole on the stress wave propagation can be neglected. However, the numerical results indicated that this assumption is unreasonable and yields contrary results. The feasibility of improving fragmentation via stress wave interaction with precise initiation was also discussed. The analysis in this paper does not support that the interaction of stress waves improves the fragmentation.

Blast wave attenuation in liquid foams: role of gas and evidence of an optimal bubble size.

PubMed

Monloubou, Martin; Bruning, Myrthe A; Saint-Jalmes, Arnaud; Dollet, Benjamin; Cantat, Isabelle

2016-09-28

Liquid foams are excellent systems to mitigate pressure waves such as acoustic or blast waves. The understanding of the underlying dissipation mechanisms however still remains an active matter of debate. In this paper, we investigate the attenuation of a weak blast wave by a liquid foam. The wave is produced with a shock tube and impacts a foam, with a cylindrical geometry. We measure the wave attenuation and velocity in the foam as a function of bubble size, liquid fraction, and the nature of the gas. We show that the attenuation depends on the nature of the gas and we experimentally evidence a maximum of dissipation for a given bubble size. All features are qualitatively captured by a model based on thermal dissipation in the gas.

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

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.

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.

The soft X-ray background as a supernova blast wave viewed from inside - Solar abundance models

NASA Technical Reports Server (NTRS)

Edgar, R. J.

1986-01-01

A model of the soft X-ray background is presented in which the sun is assumed to be inside an active supernova blast wave. The blast wave evolves in a preexisting cavity. The broad band surface brightnesses is explained by such a blast wave with an explosion energy of E sub approximately 5 x 10 to the 50th power ergs and radius 80 to 100 pc, using solar abundances. An approach to treating the problem of large anisotropies in the ambient medium is also explored, accommodating the observed anticorrelation between the soft X-ray surface brightness and the 21 cm column density. It is found that only for post shock temperatures below 10 to the 6 power K a shock propagating into a density enhancement will be dimmer than a similar shock in a lower density region.

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.

Characteristics of laser-induced shock wave injury to the inner ear of rats

NASA Astrophysics Data System (ADS)

Kurioka, Takaomi; Matsunobu, Takeshi; Niwa, Katsuki; Tamura, Atsushi; Kawauchi, Satoko; Satoh, Yasushi; Sato, Shunichi; Shiotani, Akihiro

2014-12-01

Recently, the number of blast injuries of the inner ear has increased in the general population. In blast-induced inner ear injury, a shock wave (SW) component in the blast wave is considered to play an important role in sensorineural hearing loss. However, the mechanisms by which an SW affects inner ear tissue remain largely unknown. We aimed to establish a new animal model for SW-induced inner ear injury by using laser-induced SWs (LISWs) on rats. The LISWs were generated by irradiating an elastic laser target with 694-nm nanosecond pulses of a ruby laser. After LISW application to the cochlea through bone conduction, auditory measurements revealed the presence of inner ear dysfunction, the extent of which depended on LISW overpressure. A significantly lower survival rate of hair cells and spiral ganglion neurons, as well as severe oxidative damage, were observed in the inner ear exposed to an LISW. Although considerable differences in the pressure characteristics exist between LISWs and SWs in real blast waves, the functional and morphological changes shown by the present LISW-based model were similar to those observed in real blast-induced injury. Thus, our animal model is expected to be useful for laboratory-based research of blast-induced inner ear injury.

Characteristics of laser-induced shock wave injury to the inner ear of rats.

PubMed

Kurioka, Takaomi; Matsunobu, Takeshi; Niwa, Katsuki; Tamura, Atsushi; Kawauchi, Satoko; Satoh, Yasushi; Sato, Shunichi; Shiotani, Akihiro

2014-12-01

Recently, the number of blast injuries of the inner ear has increased in the general population. In blast-induced inner ear injury, a shock wave (SW) component in the blast wave is considered to play an important role in sensorineural hearing loss. However, the mechanisms by which an SW affects inner ear tissue remain largely unknown. We aimed to establish a new animal model for SW-induced inner ear injury by using laser-induced SWs (LISWs) on rats. The LISWs were generated by irradiating an elastic laser target with 694-nm nanosecond pulses of a ruby laser. After LISW application to the cochlea through bone conduction, auditory measurements revealed the presence of inner ear dysfunction, the extent of which depended on LISW overpressure. A significantly lower survival rate of hair cells and spiral ganglion neurons, as well as severe oxidative damage, were observed in the inner ear exposed to an LISW. Although considerable differences in the pressure characteristics exist between LISWs and SWs in real blast waves, the functional and morphological changes shown by the present LISW-based model were similar to those observed in real blast-induced injury. Thus, our animal model is expected to be useful for laboratory-based research of blast-induced inner ear injury.

Blast wave mitigation by dry aqueous foams

NASA Astrophysics Data System (ADS)

Del Prete, E.; Chinnayya, A.; Domergue, L.; Hadjadj, A.; Haas, J.-F.

2013-02-01

This paper presents results of experiments and numerical modeling on the mitigation of blast waves using dry aqueous foams. The multiphase formalism is used to model the dry aqueous foam as a dense non-equilibrium two-phase medium as well as its interaction with the high explosion detonation products. New experiments have been performed to study the mass scaling effects. The experimental as well as the numerical results, which are in good agreement, show that more than an order of magnitude reduction in the peak overpressure ratio can be achieved. The positive impulse reduction is less marked than the overpressures. The Hopkinson scaling is also found to hold particularly at larger scales for these two blast parameters. Furthermore, momentum and heat transfers, which have the main dominant role in the mitigation process, are shown to modify significantly the classical blast wave profile and thereafter to disperse the energy from the peak overpressure due to the induced relaxation zone. In addition, the velocity of the fireball, which acts as a piston on its environment, is smaller than in air. Moreover, the greater inertia of the liquid phase tends to project the aqueous foam far from the fireball. The created gap tempers the amplitude of the transmitted shock wave to the aqueous foam. As a consequence, this results in a lowering of blast wave parameters of the two-phase spherical decaying shock wave.

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.

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.

Method for Determination of the Wind Velocity and Direction

NASA Technical Reports Server (NTRS)

Dahlin, Goesta Johan

1988-01-01

Accurate determination of the position of an artillery piece, for example, using sound measurement systems through measurement of the muzzle noise requires access to wind data that is representative of the portion of the air from where the sound wave is propagated up the microphone base of the system. The invention provides a system for determining such representative wind data.

Using Building Seismic Strong-Motion Data to Quantify Urban Blast Pressure Fields

NASA Astrophysics Data System (ADS)

Massari, A.; Kohler, M. D.; Heaton, T. H.; Kanamori, H.; Hauksson, E.; Clayton, R. W.; Guy, R.; Bunn, J.; Chandy, M.

2015-12-01

The use of building vibrations to measure blast wave propagation in a city is examined in this case study. The Exxon Mobil Corp. oil refinery in Torrance, California experienced an explosion on February 18, 2015 causing ground shaking equivalent to a magnitude 1.9 earthquake. The impulse response for the source was computed from Southern California Seismic Network data for a multi-orthogonal force system with a value of 2×105 kN vertically downward. The pressure wave excited by the explosion traveled through the city of Los Angeles, and was detected by a dense accelerometer array in a 52-story building also in downtown Los Angeles 22.8 km from the explosion. The array is part of the Community Seismic Network (CSN) and consists of three-component class-C MEMs sensors located on each floor of the building. The detection was verified by the nearly simultaneous arrival times of acceleration pulses on multiple floors of the building, corresponding to an average wave speed near the speed of sound in air. The pressure wave peak magnitude from the air blast was determined using accelerometer data collected on every floor of the building coupled with the elastic response of the structure as a whole. . Making use of high-fidelity finite element modeling of the building validated by previous low-level seismicity and ambient noise data, a procedure is outlined for pressure wave detection and quantification on well instrumented buildings. This case study for a 52 story building, instrumented by the CSN, acts as a proxy for blast wave quantification in dense urban environments. This type of information can be used to understand the flow of blast waves through a cityscape as well as enhance procedures for estimating blast source magnitude. Better understanding of the propagation of pressure waves in urban environments will lead to the development of improved countermeasures in those environments.

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.

Investigations of primary blast-induced traumatic brain injury

NASA Astrophysics Data System (ADS)

Sawyer, T. W.; Josey, T.; Wang, Y.; Villanueva, M.; Ritzel, D. V.; Nelson, P.; Lee, J. J.

2018-01-01

The development of an advanced blast simulator (ABS) has enabled the reproducible generation of single-pulse shock waves that simulate free-field blast with high fidelity. Studies with rodents in the ABS demonstrated the necessity of head restraint during head-only exposures. When the head was not restrained, violent global head motion was induced by pressures that would not produce similar movement of a target the size and mass of a human head. This scaling artefact produced changes in brain function that were reminiscent of traumatic brain injury (TBI) due to impact-acceleration effects. Restraint of the rodent head eliminated these, but still produced subtle changes in brain biochemistry, showing that blast-induced pressure waves do cause brain deficits. Further experiments were carried out with rat brain cell aggregate cultures that enabled the conduct of studies without the gross movement encountered when using rodents. The suspension nature of this model was also exploited to minimize the boundary effects that complicate the interpretation of primary blast studies using surface cultures. Using this system, brain tissue was found not only to be sensitive to pressure changes, but also able to discriminate between the highly defined single-pulse shock waves produced by underwater blast and the complex pressure history exposures experienced by aggregates encased within a sphere and subjected to simulated air blast. The nature of blast-induced primary TBI requires a multidisciplinary research approach that addresses the fidelity of the blast insult, its accurate measurement and characterization, as well as the limitations of the biological models used.

Single-subject-based whole-brain MEG slow-wave imaging approach for detecting abnormality in patients with mild traumatic brain injury

PubMed Central

Huang, Ming-Xiong; Nichols, Sharon; Baker, Dewleen G.; Robb, Ashley; Angeles, Annemarie; Yurgil, Kate A.; Drake, Angela; Levy, Michael; Song, Tao; McLay, Robert; Theilmann, Rebecca J.; Diwakar, Mithun; Risbrough, Victoria B.; Ji, Zhengwei; Huang, Charles W.; Chang, Douglas G.; Harrington, Deborah L.; Muzzatti, Laura; Canive, Jose M.; Christopher Edgar, J.; Chen, Yu-Han; Lee, Roland R.

2014-01-01

Traumatic brain injury (TBI) is a leading cause of sustained impairment in military and civilian populations. However, mild TBI (mTBI) can be difficult to detect using conventional MRI or CT. Injured brain tissues in mTBI patients generate abnormal slow-waves (1–4 Hz) that can be measured and localized by resting-state magnetoencephalography (MEG). In this study, we develop a voxel-based whole-brain MEG slow-wave imaging approach for detecting abnormality in patients with mTBI on a single-subject basis. A normative database of resting-state MEG source magnitude images (1–4 Hz) from 79 healthy control subjects was established for all brain voxels. The high-resolution MEG source magnitude images were obtained by our recent Fast-VESTAL method. In 84 mTBI patients with persistent post-concussive symptoms (36 from blasts, and 48 from non-blast causes), our method detected abnormalities at the positive detection rates of 84.5%, 86.1%, and 83.3% for the combined (blast-induced plus with non-blast causes), blast, and non-blast mTBI groups, respectively. We found that prefrontal, posterior parietal, inferior temporal, hippocampus, and cerebella areas were particularly vulnerable to head trauma. The result also showed that MEG slow-wave generation in prefrontal areas positively correlated with personality change, trouble concentrating, affective lability, and depression symptoms. Discussion is provided regarding the neuronal mechanisms of MEG slow-wave generation due to deafferentation caused by axonal injury and/or blockages/limitations of cholinergic transmission in TBI. This study provides an effective way for using MEG slow-wave source imaging to localize affected areas and supports MEG as a tool for assisting the diagnosis of mTBI. PMID:25009772

Relationship between changes in the cochlear blood flow and disorder of hearing function induced by blast injury in guinea pigs.

PubMed

Chen, Wei; Wang, Jianmin; Chen, Jing; Chen, Jichuan; Chen, Zhiqiang

2013-01-01

The auditory system is the most susceptible to damages from blast waves. Blast injuries always lead to varying degrees of hearing impairment. Although a disorder of the cochlear blood flow (CoBF) has been considered to be related to many pathological processes of the auditory system and to contribute to various types of hearing loss, changes in the CoBF induced by blast waves and the relationship between such changes and hearing impairment are undefined. To observe the changes in the cochlear microcirculation after exposure to an explosion blast, investigate the relationship between changes in the CoBF and hearing impairment and subsequently explore the mechanism responsible for the changes in the CoBF, we detected the perfusion of the cochlear microcirculation and hearing threshold shift after exposure to an explosion blast. Then, an N-nitro-L-arginine-methyl ester (L-NAME, NO synthase inhibitor) solution and artificial perilymph were applied to the round window (RW) of the cochlea before the blast exposure, followed by an evaluation of the CoBF and hearing function. The results indicated that the changes in the CoBF were correlated to the strength of the blast wave. The cochlear blood flow significantly increased when the peak value of the blast overpressure was greater than approximately 45 kPa, and there was no significant change in the cochlear blood flow when the peak value of the blast overpressure was less than approximately 35 kPa. Following local administration of the NO synthase inhibitor L-NAME, the increase in the CoBF induced by the blast was inhibited, and this reduction was significantly associated with the hearing threshold.

[Werkgartner's muzzle imprint mark--a literature study].

PubMed

Geserick, Gunther; Vendura, Klaus; Wirth, Ingo

2009-01-01

Since Werkgartner described and correctly interpreted the muzzle imprint mark around the gunshot entrance wound in 1922, this finding has been generally accepted as a sign of a contact shot. In further studies, it could finally be clarified that the muzzle imprint mark is caused by the expansive power of the powder gases with pressure on and abrasion of the skin at the muzzle (weapon imprint). Its shape depends on the firearm, the ammunition and the anatomical conditions, but does not require a bullet. Examinations under a magnifying glass microscope and histological investigations can complete the macroscopic findings. Occasionally, the muzzle imprint mark requires a certain "drying period" in order to become clearly visible. In rare cases, muzzle imprint marks also form on textiles perforated by the projectile. Characteristically shaped muzzled imprint marks can provide clues to the type of the firearm and its position at the time of discharge.

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

MCDU-8-A Computer Code for One-Dimensional Blast Wave Problems

DTIC Science & Technology

1975-07-01

medium surrounding the explosion is assuned to be air obeying an ideal gas equation of state with a constant specific heat ratio, y2, of 1.4. The...characteristics Explosive blast Pentolite spheres ■ 20.\\ASSTRACT (Continue on reverie eld* II neceeemry end Identify by block number) he method...INVOLVING THE. SUDDEN RELEASE OF A HIGHLY COMPRESSED AIR SPHERE 11 V. A SAMPLE PROBLEM INVOLVING A BLAST WAVE RESULTING FROM THE DETONATION OF A

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

Method for determining artillery position

NASA Technical Reports Server (NTRS)

Fischer, Johannes; Loges, Werner; Meuser, Wilfried

1988-01-01

A method is disclosed for determining the position of cannon from measurement sites whose distance from each other lies in the same order of magnitude as the distance between the cannons -- that distance being in the kilometer range -- with the help of the travel time evaluation of muzzle blasts received at the measurement sites. There are at least two measurement sites, consisting of a cruciform of four microphones each positioned so that one axis is oriented to an arbitrarily chosen reference direction with the microphones spaced closely together. In this arrangement of diametrically opposed microphones, the respective travel times are determined and placed in a relationship whose arctangent is a radio bearing to the reference direction in which radio bearings are determined with consideration of their position and their opposing distance from the cannon position.

Pathophysiology of the inner ear after blast injury caused by laser-induced shock wave

PubMed Central

Niwa, Katsuki; Mizutari, Kunio; Matsui, Toshiyasu; Kurioka, Takaomi; Matsunobu, Takeshi; Kawauchi, Satoko; Satoh, Yasushi; Sato, Shunichi; Shiotani, Akihiro; Kobayashi, Yasushi

2016-01-01

The ear is the organ that is most sensitive to blast overpressure, and ear damage is most frequently seen after blast exposure. Blast overpressure to the ear results in sensorineural hearing loss, which is untreatable and is often associated with a decline in the quality of life. In this study, we used a rat model to demonstrate the pathophysiological and structural changes in the inner ear that replicate pure sensorineural hearing loss associated with blast injury using laser-induced shock wave (LISW) without any conductive hearing loss. Our results indicate that threshold elevation of the auditory brainstem response (ABR) after blast exposure was primarily caused by outer hair cell dysfunction induced by stereociliary bundle disruption. The bundle disruption pattern was unique; disturbed stereocilia were mostly observed in the outermost row, whereas those in the inner and middle rows stereocilia remained intact. In addition, the ABR examination showed a reduction in wave I amplitude without elevation of the threshold in the lower energy exposure group. This phenomenon was caused by loss of the synaptic ribbon. This type of hearing dysfunction has recently been described as hidden hearing loss caused by cochlear neuropathy, which is associated with tinnitus or hyperacusis. PMID:27531021

Mathematical Models of Blast-Induced TBI: Current Status, Challenges, and Prospects

PubMed Central

Gupta, Raj K.; Przekwas, Andrzej

2013-01-01

Blast-induced traumatic brain injury (TBI) has become a signature wound of recent military activities and is the leading cause of death and long-term disability among U.S. soldiers. The current limited understanding of brain injury mechanisms impedes the development of protection, diagnostic, and treatment strategies. We believe mathematical models of blast wave brain injury biomechanics and neurobiology, complemented with in vitro and in vivo experimental studies, will enable a better understanding of injury mechanisms and accelerate the development of both protective and treatment strategies. The goal of this paper is to review the current state of the art in mathematical and computational modeling of blast-induced TBI, identify research gaps, and recommend future developments. A brief overview of blast wave physics, injury biomechanics, and the neurobiology of brain injury is used as a foundation for a more detailed discussion of multiscale mathematical models of primary biomechanics and secondary injury and repair mechanisms. The paper also presents a discussion of model development strategies, experimental approaches to generate benchmark data for model validation, and potential applications of the model for prevention and protection against blast wave TBI. PMID:23755039

Pathophysiology of the inner ear after blast injury caused by laser-induced shock wave.

PubMed

Niwa, Katsuki; Mizutari, Kunio; Matsui, Toshiyasu; Kurioka, Takaomi; Matsunobu, Takeshi; Kawauchi, Satoko; Satoh, Yasushi; Sato, Shunichi; Shiotani, Akihiro; Kobayashi, Yasushi

2016-08-17

The ear is the organ that is most sensitive to blast overpressure, and ear damage is most frequently seen after blast exposure. Blast overpressure to the ear results in sensorineural hearing loss, which is untreatable and is often associated with a decline in the quality of life. In this study, we used a rat model to demonstrate the pathophysiological and structural changes in the inner ear that replicate pure sensorineural hearing loss associated with blast injury using laser-induced shock wave (LISW) without any conductive hearing loss. Our results indicate that threshold elevation of the auditory brainstem response (ABR) after blast exposure was primarily caused by outer hair cell dysfunction induced by stereociliary bundle disruption. The bundle disruption pattern was unique; disturbed stereocilia were mostly observed in the outermost row, whereas those in the inner and middle rows stereocilia remained intact. In addition, the ABR examination showed a reduction in wave I amplitude without elevation of the threshold in the lower energy exposure group. This phenomenon was caused by loss of the synaptic ribbon. This type of hearing dysfunction has recently been described as hidden hearing loss caused by cochlear neuropathy, which is associated with tinnitus or hyperacusis.

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.

Volcanic Lightning, Pyroclastic Density Currents, Ballistic Fall, Vent Tremor, and One Very Loud Blast: Acoustic Analysis of the 14 July 2013 Vulcanian Eruption at Tungurahua, Ecuador.

NASA Astrophysics Data System (ADS)

Anderson, J.; Johnson, J. B.; Steele, A. L.; Anzieta, J. C.; Ortiz, H. D.; Hall, M. L.; Ruiz, M. C.

2014-12-01

Acoustic recordings reveal a variety of volcanic activities during an exceptionally loud vulcanian eruption at Tungurahua. A period of several months of mild surface activity came to an abrupt end with the emission of a powerful blast wave heard at least 180 km away. Sensors 2080 m from the vent recorded a stepped rise to its maximum overpressure of 1220 Pa (corresponding to a sound pressure level of 156 dB) and its unusually long dominant period of 5.6 s. We discuss source processes that produced the blast wave, considering that wave propagation could be nonlinear near the vent because of high overpressures. More than an hour of acoustic activity was recorded after the blast wave, including sound from falling ballistics, reflections of the blast wave from nearby mountains, pyroclastic density currents, and acoustic tremor at the vent. Glitches in the acoustic records related to plume lightning were also serendipitously observed, although thunder could not be unambiguously identified. We discuss acoustic signatures of falling ballistics and pyroclastic density currents and how array-style deployments and analytic methods can be used to reveal them. Placement of sensors high on the volcano's slopes facilitated resolving these distinct processes. This study demonstrates that near-vent, array-style acoustic installations can be used to monitor various types of volcanic activity.

The characterization and evaluation of accidental explosions

NASA Technical Reports Server (NTRS)

Strehlow, R. A.; Baker, W. E.

1975-01-01

Accidental explosions are discussed from a number of viewpoints. First, all accidental explosions, intentional explosions and natural explosions are characterized by type. Second, the nature of the blast wave produced by an ideal (point source or HE) explosion is discussed to form a basis for describing how other explosion processes yield deviations from ideal blast wave behavior. The current status blast damage mechanism evaluation is also discussed. Third, the current status of our understanding of each different category of accidental explosions is discussed in some detail.

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.

Change in muzzle velocity due to freezing and water immersion of .22, long rifle, K.F. cartridges.

PubMed

Jauhari, M; Chatterjee, S M; Ghosh, P K

1975-01-01

A study of change in muzzle velocity due to freezing and water immersion of .22, long rifle, K. F. cartridges has been presented. A statistical criterion has been formulated to ascertain whether or not a cartridge undergoes a change in muzzle velocity due to a particular treatment. The muzzle velocity data of .22, long rifle, K. F. cartridges, obtained by an electronic timer before and after the various treatments, have been analyzed in the light of this criterion. These cartridges have generally been found to suffer considerable loss in muzzle velocity when immersed in water for three weeks and also when immersed in water for three days and simultaneously cooled to 0 degrees C. The forensic significance of this loss in muzzle velocity has been discussed.

Perfluorocarbon reduces cell damage from blast injury by inhibiting signal paths of NF-κB, MAPK and Bcl-2/Bax signaling pathway in A549 cells

PubMed Central

Li, Huaidong; Li, Chunsun; Yang, Zhen; Li, Yanqin; She, Danyang; Cao, Lu; Wang, Wenjie; Liu, Changlin; Chen, Liangan

2017-01-01

Background and objective Blast lung injury is a common type of blast injury and has very high mortality. Therefore, research to identify medical therapies for blast injury is important. Perfluorocarbon (PFC) is used to improve gas exchange in diseased lungs and has anti-inflammatory functions in vitro and in vivo. The aim of this study was to determine whether PFC reduces damage to A549 cells caused by blast injury and to elucidate its possible mechanisms of action. Study design and methods A549 alveolar epithelial cells exposed to blast waves were treated with and without PFC. Morphological changes and apoptosis of A549 cells were recorded. PCR and enzyme-linked immunosorbent assay (ELISA) were used to measure the mRNA or protein levels of IL-1β, IL-6 and TNF-α. Malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity levels were detected. Western blot was used to quantify the expression of NF-κB, Bax, Bcl-2, cleaved caspase-3 and MAPK cell signaling proteins. Results A549 cells exposed to blast wave shrank, with less cell-cell contact. The morphological change of A549 cells exposed to blast waves were alleviated by PFC. PFC significantly inhibited the apoptosis of A549 cells exposed to blast waves. IL-1β, IL-6 and TNF-α cytokine and mRNA expression levels were significantly inhibited by PFC. PFC significantly increased MDA levels and decreased SOD activity levels. Further studies indicated that NF-κB, Bax, caspase-3, phospho-p38, phosphor-ERK and phosphor-JNK proteins were also suppressed by PFC. The quantity of Bcl-2 protein was increased by PFC. Conclusion Our research showed that PFC reduced A549 cell damage caused by blast injury. The potential mechanism may be associated with the following signaling pathways: 1) the signaling pathways of NF-κB and MAPK, which inhibit inflammation and reactive oxygen species (ROS); and 2) the signaling pathways of Bcl-2/Bax and caspase-3, which inhibit apoptosis. PMID:28323898

Mathematical theory of cylindrical isothermal blast waves in a magnetic field. [with application to supernova remnant evolution

NASA Technical Reports Server (NTRS)

Lerche, I.

1981-01-01

An analysis is conducted regarding the properties of cylindrically symmetric self-similar blast waves propagating away from a line source into a medium whose density and magnetic field (with components in both the phi and z directions) both vary as r to the -(omega) power (with omega less than 1) ahead of the blast wave. The main results of the analysis can be divided into two classes, related to a zero azimuthal field and a zero longitudinal field. In the case of the zero longitudinal field it is found that there are no physically acceptable solutions with continuous postshock variations of flow speed and gas density.

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.

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.

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

Microstructural effects on ignition sensitivity in Ni/Al systems subjected to high strain rate impacts

NASA Astrophysics Data System (ADS)

Reeves, Robert; Mukasyan, Alexander; Son, Steven

2011-06-01

The effect of microstructural refinement on the sensitivity of the Ni/Al (1:1 at%) system to ignition via high strain rate impacts is investigated. The tested microstructures include compacts of irregularly convoluted lamellar structures with nanometric features created through high-energy ball milling (HEBM) of micron size Ni/Al powders and compacts of nanometric Ni and Al powders. The test materials were subjected to high strain rate impacts through Asay shear experiments powered by a light gas gun. Muzzle velocities up to 1.1 km/s were used. It was found that the nanometric powder exhibited a greater sensitivity to ignition via impact than the HEBM material, despite greater thermal sensitivity of the HEBM. A previously unseen fast reaction mode where the reaction front traveled at the speed of the input stress wave was also observed in the nanometric mixtures at high muzzle energies. This fast mode is considered to be a mechanically induced thermal explosion mode dependent on the magnitude of the traveling stress wave, rather than a self-propagating detonation, since its propagation rate decreases rapidly across the sample. A similar mode is not exhibited by HEBM samples, although local, nonpropagating reaction zones occur in shear bands formed during the impact event.

Microstructural effects on ignition sensitivity in Ni/Al systems subjected to high strain rate impacts

NASA Astrophysics Data System (ADS)

Reeves, Robert V.; Mukasyan, Alexander S.; Son, Steven

2012-03-01

The effect of microstructural refinement on the sensitivity of the Ni/Al (1:1 mol%) system to ignition via high strain rate impacts is investigated. The tested microstructures include compacts of irregularly convoluted lamellar structures with nanometric features created through high-energy ball milling (HEBM) of micron size Ni/Al powders and compacts of nanometric Ni and Al powders. The test materials were subjected to high strain rate impacts through Asay shear experiments powered by a light gas gun. Muzzle velocities up to 1.1 km/s were used. It was found that the nanometric powder exhibited a greater sensitivity to ignition via impact than the HEBM material, despite greater thermal sensitivity of the HEBM. A previously unseen fast reaction mode where the reaction front traveled at the speed of the input stress wave was also observed in the nanometric mixtures at high muzzle energies. This fast mode is considered to be a mechanically induced thermal explosion mode dependent on the magnitude of the traveling stress wave, rather than a self-propagating detonation, since its propagation rate decreases rapidly across the sample. A similar mode is not exhibited by HEBM samples, although local, nonpropagating reaction zones shear bands formed during the impact event are observed.

Muzzle flash issues related to the Waco FLIR analysis

NASA Astrophysics Data System (ADS)

Grant, Barbara G.; Hardy, David T.

2001-09-01

The controversy surrounding the origin of flashes on the Mt. Carmel FLIR videotape acquired on April 19, 1993, is introduced. The characteristics of muzzle flash are reviewed. A comparative weapons description is offered. The temporal, spatial, and radiance characteristics of thermal infrared muzzle flash are addressed. Data acquired from a field experiment are presented. The authors conclude that the spatial characteristics of muzzle flash enable its detection by equipment such as the FLIR in use at Mt. Carmel on April 19, 1993; that while flashes obtained in the field appear highly radiant, measurements are necessary to quantify their values; and that the temporal behavior of muzzle flash deserves further study.

The role of stress waves in thoracic visceral injury from blast loading: modification of stress transmission by foams and high-density materials.

PubMed

Cooper, G J; Townend, D J; Cater, S R; Pearce, B P

1991-01-01

Materials have been applied to the thoracic wall of anaesthetised experimental animals exposed to blast overpressure to investigate the coupling of direct stress waves into the thorax and the relative contribution of compressive stress waves and gross thoracic compression to lung injury. The ultimate purpose of the work is to develop effective personal protection from the primary effects of blast overpressure--efficient protection can only be achieved if the injury mechanism is identified and characterized. Foam materials acted as acoustic couplers and resulted in a significant augmentation of the visceral injury; decoupling and elimination of injury were achieved by application of a high acoustic impedance layer on top of the foam. In vitro experiments studying stress wave transmission from air through various layers into an anechoic water chamber showed a significant increase in power transmitted by the foams, principally at high frequencies. Material such as copper or resin bonded Kevlar incorporated as a facing upon the foam achieved substantial decoupling at high frequencies--low frequency transmission was largely unaffected. An acoustic transmission model replicated the coupling of the blast waves into the anechoic water chamber. The studies suggest that direct transmission of stress waves plays a dominant role in lung parenchymal injury from blast loading and that gross thoracic compression is not the primary injury mechanism. Acoustic decoupling principles may therefore be employed to reduce the direct stress coupled into the body and thus reduce the severity of lung injury--the most simple decoupler is a high acoustic impedance material as a facing upon a foam, but decoupling layers may be optimized using acoustic transmission models. Conventional impacts producing high body wall velocities will also lead to stress wave generation and transmission--stress wave effects may dominate the visceral response to the impact with direct compression and shear contributing little to the aetiology of the injury.

Microarray-based analysis of the differential expression of melanin synthesis genes in dark and light-muzzle Korean cattle.

PubMed

Kim, Sang Hwan; Hwang, Sue Yun; Yoon, Jong Taek

2014-01-01

The coat color of mammals is determined by the melanogenesis pathway, which is responsible for maintaining the balance between black-brown eumelanin and yellow-reddish pheomelanin. It is also believed that the color of the bovine muzzle is regulated in a similar manner; however, the molecular mechanism underlying pigment deposition in the dark-muzzle has yet to be elucidated. The aim of the present study was to identify melanogenesis-associated genes that are differentially expressed in the dark vs. light muzzle of native Korean cows. Using microarray clustering and real-time polymerase chain reaction techniques, we observed that the expression of genes involved in the mitogen-activated protein kinase (MAPK) and Wnt signaling pathways is distinctively regulated in the dark and light muzzle tissues. Differential expression of tyrosinase was also noticed, although the difference was not as distinct as those of MAPK and Wnt. We hypothesize that emphasis on the MAPK pathway in the dark-muzzle induces eumelanin synthesis through the activation of cAMP response element-binding protein and tyrosinase, while activation of Wnt signaling counteracts this process and raises the amount of pheomelanin in the light-muzzle. We also found 2 novel genes (GenBank No. NM-001076026 and XM-588439) with increase expression in the black nose, which may provide additional information about the mechanism of nose pigmentation. Regarding the increasing interest in the genetic diversity of cattle stocks, genes we identified for differential expression in the dark vs. light muzzle may serve as novel markers for genetic diversity among cows based on the muzzle color phenotype.

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.

Chemical Initiation of FAE Clouds

DTIC Science & Technology

1980-11-01

iadlded significant FAE blasts when performed in open air, no blasl when performed in an atmosphere of nitrogen, and a very strong blast when per...miniature experiments produced well-measurable blast pressures which were considerably larger when the ambient atmosphere was air instead of nitrogen, and...very much larger when the ambient atmosphere was oxygen. It was thus demonstrated that the blast wave is reinforced by release of combustion energy

Extended adiabatic blast waves and a model of the soft X-ray background. [interstellar matter

NASA Technical Reports Server (NTRS)

Cox, D. P.; Anderson, P. R.

1981-01-01

An analytical approximation is generated which follows the development of an adiabatic spherical blast wave in a homogeneous ambient medium of finite pressure. An analytical approximation is also presented for the electron temperature distribution resulting from coulomb collisional heating. The dynamical, thermal, ionization, and spectral structures are calculated for blast waves of energy E sub 0 = 5 x 10 to the 50th power ergs in a hot low-density interstellar environment. A formula is presented for estimating the luminosity evolution of such explosions. The B and C bands of the soft X-ray background, it is shown, are reproduced by such a model explosion if the ambient density is about .000004 cm, the blast radius is roughly 100 pc, and the solar system is located inside the shocked region. Evolution in a pre-existing cavity with a strong density gradient may, it is suggested, remove both the M band and OVI discrepancies.

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.

Pulmonary microvascular dysfunction and pathological changes induced by blast injury in a rabbit model.

PubMed

Wu, Si Yu; Han, Geng Fen; Kang, Jian Yi; Zhang, Liang Chao; Wang, Ai Min; Wang, Jian Min

2016-09-01

Vascular leakage has been proven to play a critical role in the incidence and development of explosive pulmonary barotrauma. Quantitatively investigated in the present study was the severity of vascular leakage in a gradient blast injury series, as well as ultrastructural evidence relating to pulmonary vascular leakage. One hundred adult male New Zealand white rabbits were randomly divided into 5 groups according to distance from the detonator (10 cm, 15 cm, 20 cm, 30 cm, and sham control). Value of pulmonary vascular leakage was monitored by a radioactive 125I-albumin labeling method. Pathological changes caused by the blast wave were examined under light and electron microscopes. Transcapillary escape rate of 125I-albumin and residual radioactivity in both lungs increased significantly at the distances of 10 cm, 15 cm, and 20 cm, suggesting increased severity of vascular leakage in these groups. Ultrastructural observation showed swelling of pulmonary capillary endothelial cells and widened gap between endothelial cells in the 10-cm and 15-cm groups. Primary blast wave can result in pulmonary capillary blood leakage. Blast wave can cause swelling of pulmonary capillary endothelial cells and widened gap between endothelial cells, which may be responsible for pulmonary vascular leakage.

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.

NIR small arms muzzle flash

NASA Astrophysics Data System (ADS)

Montoya, Joseph; Kennerly, Stephen; Rede, Edward

2010-04-01

Utilization of Near-Infrared (NIR) spectral features in a muzzle flash will allow for small arms detection using low cost silicon (Si)-based imagers. Detection of a small arms muzzle flash in a particular wavelength region is dependent on the intensity of that emission, the efficiency of source emission transmission through the atmosphere, and the relative intensity of the background scene. The NIR muzzle flash signature exists in the relatively large Si spectral response wavelength region of 300 nm-1100 nm, which allows for use of commercial-off-the-shelf (COTS) Si-based detectors. The alkali metal origin of the NIR spectral features in the 7.62 × 39-mm round muzzle flash is discussed, and the basis for the spectral bandwidth is examined, using a calculated Voigt profile. This report will introduce a model of the 7.62 × 39-mm NIR muzzle flash signature based on predicted source characteristics. Atmospheric limitations based on NIR spectral regions are investigated in relation to the NIR muzzle flash signature. A simple signal-to-clutter ratio (SCR) metric is used to predict sensor performance based on a model of radiance for the source and solar background and pixel registered image subtraction.

The Effect of Muzzle Jet Asymmetry on Projectile Motion

DTIC Science & Technology

1975-01-01

fixture was designed to provide invariant mechanical support to the gun tube while allowing control of the symmetry of the muzzle gar flow field...Figure 4. A 2S4mm diameter by 12.7mm thick (non-metric dimensions: 10 in x 1/2 in) aluminum base plate is press fit onto the muzzle of a 6.71mm...indicated by the opaque regions of concentrated powder particles. The muzzle flow at a considerably later time, Figure 1, shows the projectile to be

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.

Relationship between Orientation to a Blast and Pressure Wave Propagation Inside the Rat Brian

DTIC Science & Technology

2011-01-01

8217·’ 2.9 ± 0.4’ ·• 64 M. Chavko ec at. I j ournal of Neuroscience Mecl1ods 195 (20!1 ) 61-66 A 60 ~ c 60 ~ ------> ------> 40 40 ~ 20 20 v :; VI...WA, Prusaczyk WK. McCarron RM. Measurement or blast wave by a miniature fiber optic pressure transducer in the rat brain. J Neurosci Methods...AI. Blast related neuro- trauma: a review or cellular injury. Mol Cell Biomech 2008;3: 155-68. ling G. Bandak F, Armonda R, Grant G, Ecklund J

Microarray-Based Analysis of the Differential Expression of Melanin Synthesis Genes in Dark and Light-Muzzle Korean Cattle

PubMed Central

Kim, Sang Hwan; Hwang, Sue Yun; Yoon, Jong Taek

2014-01-01

The coat color of mammals is determined by the melanogenesis pathway, which is responsible for maintaining the balance between black-brown eumelanin and yellow-reddish pheomelanin. It is also believed that the color of the bovine muzzle is regulated in a similar manner; however, the molecular mechanism underlying pigment deposition in the dark-muzzle has yet to be elucidated. The aim of the present study was to identify melanogenesis-associated genes that are differentially expressed in the dark vs. light muzzle of native Korean cows. Using microarray clustering and real-time polymerase chain reaction techniques, we observed that the expression of genes involved in the mitogen-activated protein kinase (MAPK) and Wnt signaling pathways is distinctively regulated in the dark and light muzzle tissues. Differential expression of tyrosinase was also noticed, although the difference was not as distinct as those of MAPK and Wnt. We hypothesize that emphasis on the MAPK pathway in the dark-muzzle induces eumelanin synthesis through the activation of cAMP response element-binding protein and tyrosinase, while activation of Wnt signaling counteracts this process and raises the amount of pheomelanin in the light-muzzle. We also found 2 novel genes (GenBank No. NM-001076026 and XM-588439) with increase expression in the black nose, which may provide additional information about the mechanism of nose pigmentation. Regarding the increasing interest in the genetic diversity of cattle stocks, genes we identified for differential expression in the dark vs. light muzzle may serve as novel markers for genetic diversity among cows based on the muzzle color phenotype. PMID:24811126

Multispectral signature analysis measurements of selected sniper rifles and small arms

NASA Astrophysics Data System (ADS)

Law, David B.; Carapezza, Edward M.; Csanadi, Christina J.; Edwards, Gerald D.; Hintz, Todd M.; Tong, Ronald M.

1997-02-01

During October 1995 - June 1996, the Naval Command, Control and Ocean Surveillance Center RDT&E Division (NRaD), under sponsorship from Defense Advanced Research Projects Agency (DARPA), conducted an intensive series of multi-spectral signature analyses of typical sniper weapons. Multi-spectral signatures of the muzzle flashes from rifles and pistols and some imagery of the bullets in flight were collected. Multi- spectral signatures of the muzzle flash were collected in the infrared (2.5 - 14.5 microns), visible -- near-IR (400 - 1200 nanometers), and the ultra-violet (185 - 400 nanometers) wavelength regions. These measurements consisted of high spectral resolution (0.0159 micron) measurements of the spectral radiance of the muzzle flash. A time history plot of the muzzle flash as it evolves just forward of the end of the muzzle is provided. These measurements were performed with a CI Systems Model SR5000 IR/Visible spectroradiometer and an Ocean Optics Model PC1000 UV spectroradiometer. Muzzle flash infrared imagery is provided to show the effect that specific muzzle breaks have on the resulting muzzle flash. The following set of sniper weapons were included in this test: AK-47, SKS, M16A2, M-14, FN-FAL, SMLE IIa, 03 Springfield, SVD Dragunov, 50 caliber McMillan, and a 45 caliber ACP pistol. The results of this signature analysis show that important measurable electro-optical differences do exist between all these weapons in terms of spectral radiance of the flash, spectral content of the gun powders, and spectral shapes/geometries of the muzzle flashes. These differences were sufficient such that, after a more complete data base is collected, it will be possible to develop a passive electro-optical weapon and ammunition identifier.

Kinematic Tests of Small Arms

DTIC Science & Technology

2016-03-15

muzzle devices, such as flash suppressors and muzzle compensators, if the items are designed to be operator removable. Use the ammunition that will...muzzle brake or adding a sound suppressor . A kinematics study is also a diagnostic tool to investigate weapon problems such as poor functioning with

Unusual blunt force wound produced by a gun muzzle.

PubMed

Hanzlick, R; Zaki, S A

1986-09-01

Most blunt force injuries produced by guns are associated with gun butts, and patterned, muzzle/sight impressions are usually produced by discharging firearms. An unusual and distinct forehead laceration produced by a blow with the muzzle end of a .32 caliber revolver is presented.

Muzzle imprint mark: a patterned injury which may be constituted of intradermal blood extravasations.

PubMed

Pircher, R; Bielefeld, L; Geisenberger, D; Große Perdekamp, M; Pollak, S; Thierauf-Emberger, A

2014-11-01

The muzzle imprint mark in contact shots is usually regarded as a patterned pressure abrasion depicting the barrel end as well as adjacent constructional components of the weapon. Due to parching after exposure to air, the affected skin assumes a brown color, especially along the contours of the impacting structures. Apart from this well-known type of epidermal damage, the imprint mark may also be formed by intradermal hemorrhages. In some cases, these intracutaneous bleedings manifest themselves as circular, curved or straight reddish lines mirroring the surface relief of the weapon's muzzle end. To estimate the frequency of skin hematomas in muzzle imprints, 35 consecutive contact shots to the head (temple, forehead, submental and occipital region) were evaluated. In 3 cases, the muzzle imprint mark exclusively consisted of intracutaneous bruises surrounding the bullet entrance hole. In 14 cases, the muzzle imprint was composed of both excoriations and intradermal hematomas. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

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

Combined hostile fire and optics detection

NASA Astrophysics Data System (ADS)

Brännlund, Carl; Tidström, Jonas; Henriksson, Markus; Sjöqvist, Lars

2013-10-01

Snipers and other optically guided weapon systems are serious threats in military operations. We have studied a SWIR (Short Wave Infrared) camera-based system with capability to detect and locate snipers both before and after shot over a large field-of-view. The high frame rate SWIR-camera allows resolution of the temporal profile of muzzle flashes which is the infrared signature associated with the ejection of the bullet from the rifle. The capability to detect and discriminate sniper muzzle flashes with this system has been verified by FOI in earlier studies. In this work we have extended the system by adding a laser channel for optics detection. A laser diode with slit-shaped beam profile is scanned over the camera field-of-view to detect retro reflection from optical sights. The optics detection system has been tested at various distances up to 1.15 km showing the feasibility to detect rifle scopes in full daylight. The high speed camera gives the possibility to discriminate false alarms by analyzing the temporal data. The intensity variation, caused by atmospheric turbulence, enables discrimination of small sights from larger reflectors due to aperture averaging, although the targets only cover a single pixel. It is shown that optics detection can be integrated in combination with muzzle flash detection by adding a scanning rectangular laser slit. The overall optics detection capability by continuous surveillance of a relatively large field-of-view looks promising. This type of multifunctional system may become an important tool to detect snipers before and after shot.

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

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.

Muzzle secretion electrolytes as a possible indicator of sodium status in buffalo (Bubalus bubalis) calves: effects of sodium depletion and aldosterone administration.

PubMed

Kumar, S; Singh, S P

1981-01-01

In two separate experiments, the effects of sodium depletion and aldosterone administration on sodium and potassium concentrations in muzzle secretion, saliva and urine were studied in buffalo calves. Sodium deficiency in the animals was experimentally produced by unilateral parotid saliva deprivation for 18 days. During sodium depletion, the sodium levels in saliva and muzzle secretion gradually fell while the potassium level gradually rose. The concentrations of both of these cations in urine gradually fell during the course of sodium depletion. Aldosterone administration in normal (sodium-replete) animals simulated the effects of sodium depletion as far as cationic changes in saliva were concerned. However, aldosterone did not affect sodium and potassium concentration in the urine and in muzzle secretion in a manner similar to that caused by sodium depletion. Though the hormone decreased urinary sodium without affecting urinary potassium, it did not affect the muzzle sodium or potassium. Results suggest that aldosterone affects the composition of saliva and urine in buffaloes as it does in sheep and other ruminants. Similar changes in composition of muzzle secretion and saliva during sodium depletion indicate that the concentration of sodium in muzzle secretion could possibly be used to evaluate the sodium status of animals.

RESONANT AMPLIFICATION OF TURBULENCE BY THE BLAST WAVES

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

Zankovich, A. M.; Kovalenko, I. G., E-mail: ilya.g.kovalenko@gmail.com

2015-02-10

We discuss the idea of whether spherical blast waves can amplify by a nonlocal resonant hydrodynamic mechanism inhomogeneities formed by turbulence or phase segregation in the interstellar medium. We consider the problem of a blast-wave-turbulence interaction in the Linear Interaction Approximation. Mathematically, this is an eigenvalue problem for finding the structure and amplitude of eigenfunctions describing the response of the shock-wave flow to forced oscillations by external perturbations in the ambient interstellar medium. Linear analysis shows that the blast wave can amplify density and vorticity perturbations for a wide range of length scales with amplification coefficients of up to 20,more » with increasing amplification the larger the length. There also exist resonant harmonics for which the gain becomes formally infinite in the linear approximation. Their orbital wavenumbers are within the range of macro- (l ∼ 1), meso- (l ∼ 20), and microscopic (l > 200) scales. Since the resonance width is narrow (typically, Δl < 1), resonance should select and amplify discrete isolated harmonics. We speculate on a possible explanation of an observed regular filamentary structure of regularly shaped round supernova remnants such as SNR 1572, 1006, or 0509-67.5. Resonant mesoscales found (l ≈ 18) are surprisingly close to the observed scales (l ≈ 15) of ripples in the shell's surface of SNR 0509-67.5.« less

Multi-thermal observations of the 2010 October 16 flare:heating of a ribbon via loops, or a blast wave?

NASA Astrophysics Data System (ADS)

Christe, Steven; Inglis, A.; Aschwanden, M.; Dennis, B.

2011-05-01

On 2010 October 16th SDO/AIA observed its first flare using automatic exposure control. Coincidentally, this flare also exhibited a large number of interesting features. Firstly, a large ribbon significantly to the solar west of the flare kernel was ignited and was visible in all AIA wavelengths, posing the question as to how this energy was deposited and how it relates to the main flare site. A faint blast wave also emanates from the flare kernel, visible in AIA and observed traveling to the solar west at an estimated speed of 1000 km/s. This blast wave is associated with a weak white-light CME observed with STEREO B and a Type II radio burst observed from Green Bank Observatory (GBSRBS). One possibility is that this blast wave is responsible for the heating of the ribbon. However, closer scrutiny reveals that the flare site and the ribbon are in fact connected magnetically via coronal loops which are heated during the main energy release. These loops are distinct from the expected hot, post-flare loops present within the main flare kernel. RHESSI spectra indicate that these loops are heated to approximately 10 MK in the immediate flare aftermath. Using the multi-temperature capabilities of AIA in combination with RHESSI, and by employing the cross-correlation mapping technique, we are able to measure the loop temperatures as a function of time over several post-flare hours and hence measure the loop cooling rate. We find that the time delay between the appearance of loops in the hottest channel, 131 A, and the cool 171 A channel, is 70 minutes. Yet the causality of this event remains unclear. Is the ribbon heated via these interconnected loops or via a blast wave?

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.

Gun muzzle flash detection using a CMOS single photon avalanche diode

NASA Astrophysics Data System (ADS)

Merhav, Tomer; Savuskan, Vitali; Nemirovsky, Yael

2013-10-01

Si based sensors, in particular CMOS Image sensors, have revolutionized low cost imaging systems but to date have hardly been considered as possible candidates for gun muzzle flash detection, due to performance limitations, and low SNR in the visible spectrum. In this study, a CMOS Single Photon Avalanche Diode (SPAD) module is used to record and sample muzzle flash events in the visible spectrum, from representative weapons, common on the modern battlefield. SPADs possess two crucial properties for muzzle flash imaging - Namely, very high photon detection sensitivity, coupled with a unique ability to convert the optical signal to a digital signal at the source pixel, thus practically eliminating readout noise. This enables high sampling frequencies in the kilohertz range without SNR degradation, in contrast to regular CMOS image sensors. To date, the SPAD has not been utilized for flash detection in an uncontrolled environment, such as gun muzzle flash detection. Gun propellant manufacturers use alkali salts to suppress secondary flashes ignited during the muzzle flash event. Common alkali salts are compounds based on Potassium or Sodium, with spectral emission lines around 769nm and 589nm, respectively. A narrow band filter around the Potassium emission doublet is used in this study to favor the muzzle flash signal over solar radiation. This research will demonstrate the SPAD's ability to accurately sample and reconstruct the temporal behavior of the muzzle flash in the visible wavelength under the specified imaging conditions. The reconstructed signal is clearly distinguishable from background clutter, through exploitation of flash temporal characteristics.

Assessment of sodium status in large ruminants by measuring the sodium-to-potassium ratio in muzzle secretions.

PubMed

Singh, S P; Rani, D

1999-09-01

To develop a simple diagnostic test to assess sodium status in large ruminants on the basis of the sodium-to-potassium ratio (Na:K) and to determine its relevance. 7 buffalo heifers and 21 lactating, pregnant, and nonpregnant dairy cows and heifers. Buffalo heifers were subjected in 2 experiments to variable dietary sodium intake or sodium depletion and changes in sodium and potassium concentrations; Na:K was simultaneously monitored in various body fluids to study its value for indicating sodium status. Validity of the muzzle secretion test was assessed. Muzzle secretion and urinary Na:K and sodium concentration, but not serum electrolyte concentrations, reflected the sodium status of buffalo heifers in response to the widely variable intake of sodium (0.03 to 0.16% of dry matter [DM]). Progressive sodium depletion during an 11-day period, using saliva deprivation caused reciprocal changes in sodium and potassium concentrations in saliva and muzzle secretion, but not in urine. Decreasing urine sodium concentration was associated with decreasing urine potassium concentration. Saliva, urine, and muzzle secretion Na:K closely reflected the degree of sodium deficit. Buffaloes or dairy cows maintained on optimal sodium intake had muzzle secretion and urine Na:K > 0.30. Muzzle secretion or urine Na:K < 0.20 or < 0.10, respectively, was indicative of sodium deficiency. Analysis of muzzle secretion Na:K, and to a large extent urine Na:K, may be used as a convenient diagnostic tool to assess sodium status in large ruminants. It has accuracy similar to that of saliva Na:K.

Off-center blast in a shocked medium

DOE PAGES

Duncan-Miller, Gabrielle Christiane; Stone, William D.

2017-11-16

When multiple blasts occur at different times, the situation arises in which a blast wave is propagating into a medium that has already been shocked. Determining the evolution in shape of the second shock is not trivial, as it is propagating into air that is not only non-uniform, but also non-stationary. To accomplish this task, we employ the method of Kompaneets to determine the shape of a shock in a non-uniform media. We also draw from the work of Korycansky [1] on an off-center explosion in a medium with radially varying density. Extending this to treat non-stationary flow, and makingmore » use of approximations to the Sedov solution for the point blast problem, we are able to determine an analytic expression for the evolving shape of the second shock. Specifically, we consider the case of a shock in air at standard ambient temperature and pressure, with the second shock occurring shortly after the original blast wave reaches it, as in a sympathetic detonation.« less

Air blast injuries killed the crew of the submarine H.L. Hunley.

PubMed

Lance, Rachel M; Stalcup, Lucas; Wojtylak, Brad; Bass, Cameron R

2017-01-01

The submarine H.L. Hunley was the first submarine to sink an enemy ship during combat; however, the cause of its sinking has been a mystery for over 150 years. The Hunley set off a 61.2 kg (135 lb) black powder torpedo at a distance less than 5 m (16 ft) off its bow. Scaled experiments were performed that measured black powder and shock tube explosions underwater and propagation of blasts through a model ship hull. This propagation data was used in combination with archival experimental data to evaluate the risk to the crew from their own torpedo. The blast produced likely caused flexion of the ship hull to transmit the blast wave; the secondary wave transmitted inside the crew compartment was of sufficient magnitude that the calculated chances of survival were less than 16% for each crew member. The submarine drifted to its resting place after the crew died of air blast trauma within the hull.

Off-center blast in a shocked medium

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

Duncan-Miller, Gabrielle Christiane; Stone, William D.

When multiple blasts occur at different times, the situation arises in which a blast wave is propagating into a medium that has already been shocked. Determining the evolution in shape of the second shock is not trivial, as it is propagating into air that is not only non-uniform, but also non-stationary. To accomplish this task, we employ the method of Kompaneets to determine the shape of a shock in a non-uniform media. We also draw from the work of Korycansky [1] on an off-center explosion in a medium with radially varying density. Extending this to treat non-stationary flow, and makingmore » use of approximations to the Sedov solution for the point blast problem, we are able to determine an analytic expression for the evolving shape of the second shock. Specifically, we consider the case of a shock in air at standard ambient temperature and pressure, with the second shock occurring shortly after the original blast wave reaches it, as in a sympathetic detonation.« less

Air blast injuries killed the crew of the submarine H.L. Hunley

PubMed Central

Stalcup, Lucas; Wojtylak, Brad; Bass, Cameron R.

2017-01-01

The submarine H.L. Hunley was the first submarine to sink an enemy ship during combat; however, the cause of its sinking has been a mystery for over 150 years. The Hunley set off a 61.2 kg (135 lb) black powder torpedo at a distance less than 5 m (16 ft) off its bow. Scaled experiments were performed that measured black powder and shock tube explosions underwater and propagation of blasts through a model ship hull. This propagation data was used in combination with archival experimental data to evaluate the risk to the crew from their own torpedo. The blast produced likely caused flexion of the ship hull to transmit the blast wave; the secondary wave transmitted inside the crew compartment was of sufficient magnitude that the calculated chances of survival were less than 16% for each crew member. The submarine drifted to its resting place after the crew died of air blast trauma within the hull. PMID:28832592

Pressure pulse induced-damage in live biological samples

NASA Astrophysics Data System (ADS)

Bo, C.; Balzer, J.; Godfrey, S.; Francois, M.; Saffell, J. L.; Rankin, S. M.; Proud, W. G.; Brown, K. A.

2012-08-01

Developing a cellular and molecular understanding of the nature of traumatic and post-traumatic effects of blast on live biological samples is critical for improving clinical outcomes. To analyze the effects of blast waves upon the cellular structures and the underlying physiological and biochemical changes, we have constructed an experimental platform capable of delivering compression waves, of amplitudes relevant to blast, to cell suspensions in a contained environment. Initial characterization of the system shows that cell cultures can be subjected to high-intensity compression waves up to 15 MPa in pressure and duration of 80 ± 10μs. Studies of mouse mesenchymal stem cells subjected to two different pressure impulses were analysed by cell counting, cell viability assays and microscopic evaluation: the experiments present evidence suggestive of increased levels of damage and loss of cellular integrity compared to uncompressed cell cultures.

Blast induced mild traumatic brain injury/concussion: A physical analysis

NASA Astrophysics Data System (ADS)

Kucherov, Yan; Hubler, Graham K.; DePalma, Ralph G.

2012-11-01

Currently, a consensus exists that low intensity non-impact blast wave exposure leads to mild traumatic brain injury (mTBI). Considerable interest in this "invisible injury" has developed in the past few years but a disconnect remains between the biomedical outcomes and possible physical mechanisms causing mTBI. Here, we show that a shock wave travelling through the brain excites a phonon continuum that decays into specific acoustic waves with intensity exceeding brain tissue strength. Damage may occur within the period of the phonon wave, measured in tens to hundreds of nanometers, which makes the damage difficult to detect using conventional modalities.

On meteor-generated infrasound. [propagation characteristics during entry into earth atmosphere

NASA Technical Reports Server (NTRS)

Revelle, D. O.

1976-01-01

The characteristics of generation and propagation of infrasonic pressure waves excited during meteor entry into the earth's atmosphere are studied. Existing line source blast wave theory is applied to infrasonic airwave data from four bright fire-balls. It is shown that the strong shock behavior of the blast wave is confined to a cylinderical region with a radius proportional to the product of the meteor Mach number and its diameter. A description of the wave form far from the source is provided. Infrasonic data reported elsewhere are analyzed. All the results should be considered as preliminary, and additional work is under way to refine the estimates obtained.

Supersonic projectile models for asynchronous shooter localization

NASA Astrophysics Data System (ADS)

Kozick, Richard J.; Whipps, Gene T.; Ash, Joshua N.

2011-06-01

In this work we consider the localization of a gunshot using a distributed sensor network measuring time differences of arrival between a firearm's muzzle blast and the shockwave induced by a supersonic bullet. This so-called MB-SW approach is desirable because time synchronization is not required between the sensors, however it suffers from increased computational complexity and requires knowledge of the bullet's velocity at all points along its trajectory. While the actual velocity profile of a particular gunshot is unknown, one may use a parameterized model for the velocity profile and simultaneously fit the model and localize the shooter. In this paper we study efficient solutions for the localization problem and identify deceleration models that trade off localization accuracy and computational complexity. We also develop a statistical analysis that includes bias due to mismatch between the true and actual deceleration models and covariance due to additive noise.

Intracranial pressure increases during exposure to a shock wave.

PubMed

Leonardi, Alessandra Dal Cengio; Bir, Cynthia A; Ritzel, Dave V; VandeVord, Pamela J

2011-01-01

Traumatic brain injuries (TBI) caused by improvised explosive devices (IEDs) affect a significant percentage of surviving soldiers wounded in Iraq and Afghanistan. The extent of a blast TBI, especially initially, is difficult to diagnose, as internal injuries are frequently unrecognized and therefore underestimated, yet problems develop over time. Therefore it is paramount to resolve the physical mechanisms by which critical stresses are inflicted on brain tissue from blast wave encounters with the head. This study recorded direct pressure within the brains of male Sprague-Dawley rats during exposure to blast. The goal was to understand pressure wave dynamics through the brain. In addition, we optimized in vivo methods to ensure accurate measurement of intracranial pressure (ICP). Our results demonstrate that proper sealing techniques lead to a significant increase in ICP values, compared to the outside overpressure generated by the blast. Further, the values seem to have a direct relation to a rat's size and age: heavier, older rats had the highest ICP readings. These findings suggest that a global flexure of the skull by the transient shockwave is an important mechanism of pressure transmission inside the brain.

Survey of seismic conditions of drilling and blasting operations near overhead electricity power lines

NASA Astrophysics Data System (ADS)

Korshunov, G. I.; Afanasev, P. I.; Bulbasheva, I. A.

2017-10-01

The monitoring and survey results of drilling and blasting operations are specified during the development of Afanasyevsky deposit of cement raw materials for a 110 kV electricity power lines structure. Seismic explosion waves and air shock waves were registered in the course of monitoring. The dependency of peak particle velocities on the scaled distance and explosive weight by the delay time was obtained.

Calculation of wing response to gusts and blast waves with vortex lift effect

NASA Technical Reports Server (NTRS)

Chao, D. C.; Lan, C. E.

1983-01-01

A numerical study of the response of aircraft wings to atmospheric gusts and to nuclear explosions when flying at subsonic speeds is presented. The method is based upon unsteady quasi-vortex lattice method, unsteady suction analogy and Pade approximant. The calculated results, showing vortex lag effect, yield reasonable agreement with experimental data for incremental lift on wings in gust penetration and due to nuclear blast waves.

Nonuniform Expansion of the Youngest Galactic Supernova Remnant G1.9+0.3

NASA Technical Reports Server (NTRS)

Borkowski, Kazimierz J.; Reynolds, Stephen P.; Green, David A.; Hwang, Una; Petre, Robert; Krishnamurthy, Kalyani; Willett, Rebecca

2014-01-01

We report measurements of the X-ray expansion of the youngest Galactic supernova remnant, G1.9+0.3, using Chandra observations in 2007, 2009, and 2011. The measured rates strongly deviate from uniform expansion, decreasing radially by about 60 along the X-ray bright SE-NW axis from 0.84 plus or minus 0.06% yr(exp -1) to 0.52% plus or minus 0.03 yr(exp -1). This corresponds to undecelerated ages of 120-190 yr, confirming the young age of G1.9+0.3 and implying a significant deceleration of the blast wave. The synchrotron-dominated X-ray emission brightens at a rate of 1.9% plus or minus 0.4% yr(exp -1). We identify bright outer and inner rims with the blast wave and reverse shock, respectively. Sharp density gradients in either the ejecta or ambient medium are required to produce the sudden deceleration of the reverse shock or the blast wave implied by the large spread in expansion ages. The blast wave could have been decelerated recently by an encounter with a modest density discontinuity in the ambient medium, such as may be found at a wind termination shock, requiring strong mass loss in the progenitor.

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

Blast lung injury.

PubMed

Sasser, Scott M; Sattin, Richard W; Hunt, Richard C; Krohmer, Jon

2006-01-01

Current trends in global terrorism mandate that emergency medical services, emergency medicine and other acute care clinicians have a basic understanding of the physics of explosions, the types of injuries that can result from an explosion, and current management for patients injured by explosions. High-order explosive detonations result in near instantaneous transformation of the explosive material into a highly pressurized gas, releasing energy at supersonic speeds. This results in the formation of a blast wave that travels out from the epicenter of the blast. Primary blast injuries are characterized by anatomical and physiological changes from the force generated by the blast wave impacting the body's surface, and affect primarily gas-containing structures (lungs, gastrointestinal tract, ears). "Blast lung" is a clinical diagnosis and is characterized as respiratory difficulty and hypoxia without obvious external injury to the chest. It may be complicated by pneumothoraces and air emboli and may be associated with multiple other injuries. Patients may present with a variety of symptoms, including dyspnea, chest pain, cough, and hemoptysis. Physical examination may reveal tachypnea, hypoxia, cyanosis, and decreased breath sounds. Chest radiography, computerized tomography, and arterial blood gases may assist with diagnosis and management; however, they should not delay diagnosis and emergency interventions in the patient exposed to a blast. High flow oxygen, airway management, tube thoracostomy in the setting of pneumothoraces, mechanical ventilation (when required) with permissive hypercapnia, and judicious fluid administration are essential components in the management of blast lung injury.

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.

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.

Shock tubes and waves; Proceedings of the Sixteenth International Symposium, Rheinisch-Westfaelische Technische Hochschule, Aachen, Federal Republic of Germany, July 26-31, 1987

NASA Astrophysics Data System (ADS)

Groenig, Hans

Topics discussed in this volume include shock wave structure, propagation, and interaction; shocks in condensed matter, dusty gases, and multiphase media; chemical processes and related combustion and detonation phenomena; shock wave reflection, diffraction, and focusing; computational fluid dynamic code development and shock wave application; blast and detonation waves; advanced shock tube technology and measuring technique; and shock wave applications. Papers are presented on dust explosions, the dynamics of shock waves in certain dense gases, studies of condensation kinetics behind incident shock waves, the autoignition mechanism of n-butane behind a reflected shock wave, and a numerical simulation of the focusing process of reflected shock waves. Attention is also given to the equilibrium shock tube flow of real gases, blast waves generated by planar detonations, modern diagnostic methods for high-speed flows, and interaction between induced waves and electric discharge in a very high repetition rate excimer laser.

Video Measurement of the Muzzle Velocity of a Potato Gun

ERIC Educational Resources Information Center

Jasperson, Christopher; Pollman, Anthony

2011-01-01

Using first principles, a theoretical equation for the maximum and actual muzzle velocities for a pneumatic cannon was recently derived. For a fixed barrel length, this equation suggests that the muzzle velocity can be enhanced by maximizing the product of the initial pressure and the volume of the propellant gas and decreasing the projectile…

27 CFR 53.61 - Imposition and rates of tax.

Code of Federal Regulations, 2013 CFR

2013-04-01

... choke, a flash hider, a muzzle brake, a magazine, a set of sling swivels, and/or an attachable ramrod for muzzle loading firearms when provided by the manufacturer or importer for use with the firearm in... flash hiders/muzzle brakes of a type not provided by the manufacturer or importer of the firearm in the...

27 CFR 53.61 - Imposition and rates of tax.

Code of Federal Regulations, 2012 CFR

2012-04-01

... set of sights (iron or optical), sight mount or set of sight mounts, a choke, a flash hider, a muzzle brake, a magazine, a set of sling swivels, and/or an attachable ramrod for muzzle loading firearms when... sights and mounts, recoil pads, slings, sling swivels, chokes, and flash hiders/muzzle brakes of a type...

27 CFR 53.61 - Imposition and rates of tax.

Code of Federal Regulations, 2011 CFR

2011-04-01

... choke, a flash hider, a muzzle brake, a magazine, a set of sling swivels, and/or an attachable ramrod for muzzle loading firearms when provided by the manufacturer or importer for use with the firearm in... flash hiders/muzzle brakes of a type not provided by the manufacturer or importer of the firearm in the...

27 CFR 53.61 - Imposition and rates of tax.

Code of Federal Regulations, 2014 CFR

2014-04-01

... choke, a flash hider, a muzzle brake, a magazine, a set of sling swivels, and/or an attachable ramrod for muzzle loading firearms when provided by the manufacturer or importer for use with the firearm in... flash hiders/muzzle brakes of a type not provided by the manufacturer or importer of the firearm in the...

Muzzle of South American Pleistocene ground sloths (Xenarthra, Tardigrada).

PubMed

Bargo, M Susana; Toledo, Néstor; Vizcaíno, Sergio F

2006-02-01

Sloths are among the most characteristic elements of the Cainozoic of South America and are represented, during the Pleistocene, by approximately nine genera of gigantic ground sloths (Megatheriidae and Mylodontidae). A few contributions have described their masticatory apparatus, but almost no attention has been paid to the reconstruction of the muzzle, an important feature to consider in relation to food intake, and particularly relevant in sloths because of the edentulous nature of the muzzle and its varied morphology. The relationship between dietary habits and shape and width of the muzzle is well documented in living herbivores and has been considered an important feature for the inference of alimentary styles in fossils, providing an interesting methodological tool that deserves to be considered for xenarthrans. The goal of this study was to examine models of food intake by reconstructing the appearance and shape of the muzzle in five species of Pleistocene ground sloths (Megatherium americanum, Glossotherium robustum, Lestodon armatus, Mylodon darwini, and Scelidotherium leptocephalum) using reconstructions of the nasal cartilages and facial muscles involved in food intake. The preservation of the nasal septum, and the scars for muscular attachment in the rostral part of the skulls, allow making a conservative reconstruction of muzzle anatomy in fossil sloths. Wide-muzzled ground sloths (Glossotherium and Lestodon) had a square, nonprehensile upper lip and were mostly bulk-feeders. The lips, coupled with the tongue, were used to pull out grass and herbaceous plants. Narrow-muzzled sloths (Mylodon, Scelidotherium, and Megatherium) had a cone-shaped and prehensile lip and were mixed or selective feeders. The prehensile lip was used to select particular plants or plant parts. (c) 2005 Wiley-Liss, Inc.

Muzzle size, paranasal swelling size and body mass in Mandrillus leucophaeus.

PubMed

Elton, Sarah; Morgan, Bethan J

2006-04-01

The drill (Mandrillus leucophaeus), a forest-living Old World monkey, is highly sexually dimorphic, with males exhibiting extreme secondary sexual characteristics, including growth of paranasal swellings on the muzzle. In this study, the size of the secondary bone that forms the paranasal swellings on the muzzles of drills was assessed in relation to body mass proxies. The relationship between the overall size of the muzzle and surrogate measures of body mass was also examined. In female drills, muzzle breadth was positively correlated with two proxies of overall body mass, greatest skull length and upper M1 area. However, there was no such correlation in males. Paranasal swellings in males also appeared to have no significant relationship to body mass proxies. This suggests that secondary bone growth on the muzzles of male drills is independent of overall body size. Furthermore, this secondary bone appears to be vermiculate, probably developing rapidly and in an irregular manner, with no correlation in the sizes of paranasal swelling height and breadth. However, various paranasal swelling dimensions were related to the size of the muzzle. It is suggested that the growth of the paranasal swellings and possibly the muzzle could be influenced by androgen production and reflect testes size and sperm motility. The size and appearance of the paranasal swellings may thus be an indicator of reproductive quality both to potential mates and male competitors. Further work is required to investigate the importance of the paranasal swellings as secondary sexual characteristics in Mandrillus and the relationship between body size and secondary sexual characteristics. Attention should also be paid to the mechanisms and trajectories of facial growth in Mandrillus.

Fast uncooled module 32×32 array of polycrystalline PbSe used for muzzle flash detection

NASA Astrophysics Data System (ADS)

Kastek, Mariusz; Dulski, Rafał; Trzaskawka, Piotr; Bieszczad, Grzegorz

2011-06-01

The paper presents some aspects of muzzle flash detection using low resolution polycrystalline PbSe uncooled 32×32 detectors array. This system for muzzle flash detection works in MWIR (3 - 5 microns) region and it is based on VPD (Vapor Phase Deposition) technology. The low density uncooled 32×32 array is suitable for being used in low cost IR imagers sensitive in the MWIR band with frame rates exceeding 1.000 Hz. The FPA detector, read-out electronics and processing electronics (allowing the implementation of some algorithms for muzzle flash detection) has been presented. The system has been tested at field test ground. Results of detection range measurement with two types of optical systems (wide and narrow field of view) have been shown. The initial results of testing of some algorithms for muzzle flash detection have been also presented.

The dynamic development of the muzzle imprint by contact gunshot: high-speed documentation utilizing the "skin-skull-brain model".

PubMed

Thali, M J; Kneubuehl, B P; Dirnhofer, R; Zollinger, U

2002-07-17

Many contact gunshots produce a muzzle imprint in the skin of the victim. Different mechanisms have been discussed in literature as being responsible for the creation of the muzzle imprint. Experimenting upon the synthetic non biological skin-skull-brain model, our goal was to document and study the creation of the muzzle imprint with the aid of high-speed photography. In our experiments, we could document with our high-speed photography (at exposure rates in the range of nanoseconds) the bulging, the pressing against the muzzle, and the splitting of the artificial skin. Furthermore, it was possible to photographically record the back pattern of synthetic tissue particles. And, the soot and gunpowder cavity could be reproduced experimentally. In conclusion the experiments completed with the skin-skull-brain model, using high-speed photography for documentation, show the promising possibilities of experimental ballistics with body models.

Laser High-Speed Photography System Used To Take Pictures Of The Attitudes Of Flying Projectile At The Muzzle Of Heavy Calibre Gun

NASA Astrophysics Data System (ADS)

Yuren, Wang; Fang, Shao; Weiping, Sun; Xioujuan, Li; Suning, Tian; Hongyan, Li

1989-06-01

When a heavy-calibre gun is fired and a projectite is flying near the gun muzzle, velocity of the projectile is very high and firing process is accompanying with strong muzzle flash. So taking the picture of the attitudes of flying projectile at the gun muzzle is very difficult. "YDS speed Photography System" developed by our group can take the framing pictures of the attitudes of the projectile and prevent them from flash confusing at the muzzle. Since framing depends on sequential pulse of the laser and the width of the putse is very narrow, therefore the exposure time is very short and photos of high-velocity flying body taken are very clear. This paper Introduces configuration and operation principle of "YDS laser High-speed Photography System" and the fuctions of the devices in this system In addition, some experimental results are briefly introduced.

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.

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.

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

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.

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.

Noxious mechanical heterotopic stimulation induces inhibition of the spinal dorsal horn neuronal network: analysis of spinal somatosensory-evoked potentials.

PubMed

Meléndez-Gallardo, J; Eblen-Zajjur, A

2016-09-01

Most of the endogenous pain modulation (EPM) involves the spinal dorsal horn (SDH). EPM including diffuse noxious inhibitory controls have been extensively described in oligoneuronal electrophysiological recordings but less attention had been paid to responses of the SDH neuronal population to heterotopic noxious stimulation (HNS). Spinal somatosensory-evoked potentials (SEP) offer the possibility to evaluate the neuronal network behavior, reflecting the incoming afferent volleys along the entry root, SDH interneuron activities and the primary afferent depolarization. SEP from de lumbar cord dorsum were evaluated during mechanical heterotopic noxious stimuli. Sprague-Dawley rats (n = 12) were Laminectomized (T10-L3). The sural nerve of the left hind paw was electrically stimulated (5 mA, 0.5 ms, 0.05 Hz) to induce lumbar SEP. The HNS (mechanic clamp) was applied sequentially to the tail, right hind paw, right forepaw, muzzle and left forepaw during sural stimulation. N wave amplitude decreases (-16.6 %) compared to control conditions when HNS was applied to all areas of stimulation. This effect was more intense for muzzle stimulation (-23.5 %). N wave duration also decreased by -23.6 %. HNS did not change neither the amplitude nor the duration of the P wave but dramatically increases the dispersion of these two parameters. The results of the present study strongly suggest that a HNS applied to different parts of the body is able to reduce the integrated electrical response of the SDH, suggesting that not only wide dynamic range neurons but many others in the SDH are modulated by the EPM.

High-fidelity simulations of blast loadings in urban environments using an overset meshing strategy

NASA Astrophysics Data System (ADS)

Wang, X.; Remotigue, M.; Arnoldus, Q.; Janus, M.; Luke, E.; Thompson, D.; Weed, R.; Bessette, G.

2017-05-01

Detailed blast propagation and evolution through multiple structures representing an urban environment were simulated using the code Loci/BLAST, which employs an overset meshing strategy. The use of overset meshes simplifies mesh generation by allowing meshes for individual component geometries to be generated independently. Detailed blast propagation and evolution through multiple structures, wave reflection and interaction between structures, and blast loadings on structures were simulated and analyzed. Predicted results showed good agreement with experimental data generated by the US Army Engineer Research and Development Center. Loci/BLAST results were also found to compare favorably to simulations obtained using the Second-Order Hydrodynamic Automatic Mesh Refinement Code (SHAMRC). The results obtained demonstrated that blast reflections in an urban setting significantly increased the blast loads on adjacent buildings. Correlations of computational results with experimental data yielded valuable insights into the physics of blast propagation, reflection, and interaction under an urban setting and verified the use of Loci/BLAST as a viable tool for urban blast analysis.

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.

The multi-modal responses of a physical head model subjected to various blast exposure conditions

NASA Astrophysics Data System (ADS)

Ouellet, S.; Philippens, M.

2018-01-01

The local and global biomechanical response of the body to a blast wave is the first step of a sequence that leads to the development of stresses and strains which can exceed the tolerance of brain tissue. These stresses and strains may then lead to neuro-physical changes in the brain and contribute to initiate a cascade of events leading to injury. The specific biomechanical pathways by which the blast energy is transmitted through the head structure are, however, not clearly understood. Multiple transmission mechanisms have been proposed to explain the generation of brain stresses following the impingement of a blast wave on the head. With the use of a physical head model, the work presented here aims at demonstrating that the proposed transmission mechanisms are not mutually exclusive. They are part of a continuum of head responses where, depending on the exposure conditions, a given mechanism may or may not dominate. This article presents the joint analysis of previous blast test results generated with the brain injury protection evaluation device (BIPED) headform under four significantly different exposure conditions. The focus of the analysis is to demonstrate how the nature of the recorded response is highly dependent on the exposure characteristics and consequently, on the method used to reproduce blast exposure in a laboratory environment. The timing and magnitude of the variations in intra-cranial pressures (ICP) were analysed relative to the external pressure field in order to better understand the wave dynamics occurring within the brain structure of the headform. ICP waveforms were also analysed in terms of their energy spectral density to better identify the energy partitioning between the different modes of response. It is shown that the BIPED response is multi-modal and that the energy partitioning between its different modes of response is greatly influenced by exposure characteristics such as external peak overpressure, impulse, blast wave structure, and direction of propagation. Convincing evidence of stresses generated from local skull deformation is presented along with evidence of stress transmission through relative brain-to-skull motion. These findings suggest that research aimed at defining exposure thresholds should not focus on a single stress transmission mechanism or use experimental designs unrepresentative of realistic blast loading conditions that may favour a given mechanism over another.

Integrated experimental platforms to study blast injuries: a bottom-up approach

NASA Astrophysics Data System (ADS)

Bo, C.; Williams, A.; Rankin, S.; Proud, W. G.; Brown, K. A.

2014-05-01

We are developing experimental models of blast injury using data from live biological samples. An integrated research strategy is followed to study material and biological properties of cells, tissues and organs, that are subjected to dynamic and static pressures, relevant to those of battlefield blast. We have developed a confined Split Hopkinson Pressure Bar (SHPB) system, which allows cells, either in suspension or as a monolayer, to be subjected to compression waves with pressures on the order of a few MPa and durations of hundreds of microseconds. The chamber design enables recovery of biological samples for cellular and molecular analysis. The SHPB platform, coupled with Quasi-Static experiments, is used to determine stress-strain curves of soft biological tissues under compression at low, medium and high strain rates. Tissue samples are examined, using histological techniques, to study macro- and microscopic changes induced by compression waves. In addition, a shock tube enables application of single or multiple air blasts with pressures on the order of kPa and a few milliseconds duration; this platform was used for initial studies on mesenchymal stem cells responses to blast pressures.

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

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.

An ultra-fast fiber optic pressure sensor for blast event measurements

NASA Astrophysics Data System (ADS)

Wu, Nan; Zou, Xiaotian; Tian, Ye; Fitek, John; Maffeo, Michael; Niezrecki, Christopher; Chen, Julie; Wang, Xingwei

2012-05-01

Soldiers who are exposed to explosions are at risk of suffering traumatic brain injury (TBI). Since the causal relationship between a blast and TBI is poorly understood, it is critical to have sensors that can accurately quantify the blast dynamics and resulting wave propagation through a helmet and skull that are imparted onto and inside the brain. To help quantify the cause of TBI, it is important to record transient pressure data during a blast event. However, very few sensors feature the capabilities of tracking the dynamic pressure transients due to the rapid change of the pressure during blast events, while not interfering with the physical material layers or wave propagation. In order to measure the pressure transients efficiently, a pressure sensor should have a high resonant frequency and a high spatial resolution. This paper describes an ultra-fast fiber optic pressure sensor based on the Fabry-Perot principle for the application of measuring the rapid pressure changes in a blast event. A shock tube experiment performed in US Army Natick Soldier Research, Development and Engineering Center has demonstrated that the resonant frequency of the sensor is 4.12 MHz, which is relatively close to the designed theoretical value of 4.113 MHz. Moreover, the experiment illustrated that the sensor has a rise time of 120 ns, which demonstrates that the sensor is capable of observing the dynamics of the pressure transient during a blast event.

Surface wave inversion of central Texas quarry blasts

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

Bonner, J.L.; Goforth, T.T.

1993-02-01

Compressional and shear wave models of the upper crust in central Texas were obtained by inverting Rayleigh and Love waves recorded at the new W.M. Keck Foundation Seismological Observatory at Baylor University. The Keck Observatory, which became operational in April 1992, consists of a three-component, broadband Geotech seismometer located at a depth of 130 feet in a borehole 17 miles from the Baylor campus. The field station is solar powered, and the 140-dB dynamic range digital data are transmitted to the Baylor analysis lab via radio, where they are analyzed and archived. Limestone quarries located in all directions from themore » Keck Observatory detonate two to four tons of explosives per blast several times a week. Recordings of these blasts show sharp onsets of P and S waves, as well as dispersed Rayleigh and Love waves in the period band 1 to 3 seconds. Multiple filter analysis and phase matched filtering techniques were used to obtain high quality dispersion curves for the surface waves, and inversion techniques were applied to produce shear velocity models of the upper crust. A rapid increase in shear velocity at a depth of about 1.5 km is associated with the Ouachita Overthrust Belt. Portable seismic recording systems were placed at the quarries to monitor start times and initial wave forms. These data were combined with the Keck recordings to produce attenuation and compressional velocity models.« less

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.

Check Firing of Master and Reference Propellants

DTIC Science & Technology

2014-12-08

estimate amount and color of smoke generated. s. Visually estimate amount and color of muzzle flash generated. TOP 04-2-607A 8 December 2014 10...Stargauge. TOP 04-2-607A 8 December 2014 3 e. Pressure gauge (piezoelectric preferred, and/or crusher). f. Muzzle velocity radar unit...firing: a. Provide electronics personnel with the weapon caliber and type, the weight and model of projectile, and expected muzzle velocities. b

An Investigation of the Mechanism of Traumatic Brain Injury Caused by Blast in the Open Field

NASA Astrophysics Data System (ADS)

Feng, Ke

Blast-induced traumatic brain injury (bTBI) is a signature wound of modern warfare. The current incomplete understanding of its injury mechanism impedes the development of strategies for effective protection of bTBI. Despite a considerable amount of experimental animal studies focused on the evaluation of brain neurotrauma caused by blast exposure, there is very limited knowledge on the biomechanical responses of the gyrenecephalic brain subjected to primary free-field blast waves imposed in vivo, and the correlation analysis between the biomechanical responses and its injury outcomes. Such information is crucial to the development of injury criteria of bTBI. This study aims to evaluate the external and internal mechanical responses of the brain against different levels of blast loading with Yucatan swine in free field, and to conduct correlational studies with brain tissue damage. To better understand primary bTBI, we have implemented an open field experimental model to apply controlled shock waves on swine head. The applied pressure levels of shock waves were predicted by finite element modeling and verified with calibrated testing. Biomechanical responses of primary blasts such as intracranial pressure (ICP), head kinetics, strain rate of skull, were measured in vivo during the blasts. A positive correlation between incident overpressure (IOP) and its corresponding biomechanical responses of the brain was observed. A parallel group of non-instrumented animals were used to collect injury data 72 hours post experiment. Cellular responses governed by primary blasts, such as neuronal degeneration and apoptosis were studied via immunohistochemistry. Representative fluorescent-stained images were examined under microscope. A positive correlation was found between the amount of degenerative neurons and the blast level. Significant elevation of apoptosis was found in the high-level blast. Comparisons between brains with varies ICP readings demonstrate differences of the numbers of neuronal degeneration and apoptosis within the imaged volume. Additionally, comparisons between sections at different locations of the head did not show spatial changes for cellular responses. These metrics provide a pathway for direct connection between the cellular damage and the measured biomechanical responses of the brain within the same experimental model, and could be critical in understanding the mechanisms of bTBI. This experimental data can be used to validate computer models of bTBI.

Technology of uncooled fast polycrystalline PbSe focal plane arrays in systems for muzzle flash detection

NASA Astrophysics Data System (ADS)

Kastek, Mariusz; PiÄ tkowski, Tadeusz; Polakowski, Henryk; Barela, Jaroslaw; Firmanty, Krzysztof; Trzaskawka, Piotr; Vergara, German; Linares, Rodrigo; Gutierrez, Raul; Fernandez, Carlos; Montojo Supervielle, Maria Teresa

2014-05-01

The paper presents some aspects of muzzle flash detection using low resolution polycrystalline PbSe 32×32 and 80×80 detectors FPA operating at room temperature (uncooled performance). These sensors, which detect in MWIR (3 - 5 microns region) and are manufactured using proprietary technology from New Infrared Technologies (VPD PbSe - Vapor Phase Deposition of polycrystalline PbSe), can be applied to muzzle flash detection. The system based in the uncooled 80×80 FPA monolithically integrated with the CMOS readout circuitry has allowed image recording with frame rates over 2000 Hz (true snapshot acquisition), whereas the lower density, uncooled 32×32 FPA is suitable for being used in low cost infrared imagers sensitive in the MWIR band with frame rates above 1000 Hz. The FPA detector, read-out electronics and processing electronics (allows the implementation of some algorithms for muzzle flash detection) of both systems are presented. The systems have been tested at field test ground. Results of detection range measurement with two types of optical systems (wide and narrow field of view) have been shown. The theoretical analysis of possibility detection of muzzle flash and initial results of testing of some algorithms for muzzle flash detection have been presented too.

Characterization and Modeling of Thoraco-Abdominal Response to Blast Waves. Volume 4. Biomechanical Model of Thorax Response to Blast Loading

DTIC Science & Technology

1985-05-01

non- zero Dirichlet boundary conditions and/or general mixed type boundary conditions. Note that Neumann type boundary condi- tion enters the problem by...Background ................................. ................... I 1.3 General Description ..... ............ ........... . ....... ...... 2 2. ANATOMICAL...human and varions loading conditions for the definition of a generalized safety guideline of blast exposure. To model the response of a sheep torso

Infection Casualty Estimation (ICE) Model: Predicting Sepsis in Nuclear Detonation Burn Patient Populations using Procalcitonin as a Biomarker

DTIC Science & Technology

2017-06-06

environments may be injured or killed from the primary blast wave, thermal pulse and ionizing radiation . Burn casualties surviving the initial blast wave are...32]/1.8 degree Celsius (oC) degree Fahrenheit (oF) [T(oF) + 459.67]/1.8 kelvin (K) Radiation activity of radionuclides [curie (Ci)] 3.7 × 1010...develop casualty estimation models for improvised nuclear device (IND) scenarios. The HSRDIPT team has developed health effects models of radiation , burn

Interaction of Supernova Blast Waves with Wind-Driven Shells: Formation of "Jets", "Bullets", "Ears", Etc.

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.

Most of middle-aged supernova remnants (SNRs) have a distorted and complicated appearance which cannot be explained in the framework of the Sedov-Taylor model. We consider three typical examples of such SNRs (Vela SNR, MSH15-52, G309.2-00.6) and show that their structure could be explained as a result of interaction of a supernova (SN) blast wave with the ambient medium preprocessed by the action of the SN progenitor's wind and ionized emission.

Improved 20mm Plastic Rotating Bands

DTIC Science & Technology

1976-12-01

Taper, and 13- Degree Aft Taper, In-Flight at 3, 786 Feet per Second Muzzle Velocity at Ambient Conditions ....... ... 46 I LIST OF ILLUSTRATIONS...at 3, 770 Feet per Second Muzzle Velocity at Ambient Conditions ......... ... 46 14 EG-D69-B-813/15 Series Projectile with 0.813-inch Band Diameter...15-Degree Fore and Aft Tapers, In- Flight at 3, 763 Feet per Second Muzzle Velocity at Ambient Conditions ..... ............... .... 47 15 EG-D69-B-813

Identification of Soldier Behaviors Associated with Search and Target Acquisition (STA)

DTIC Science & Technology

2010-05-01

specifically concentrated on representing Soldier and small unit behavior engaging "non-acquired" targets and "non-standard" entities, such as: muzzle ...Forces Are Targeting (e.g., weapon orientation, bullet impacts) Area Where Fire Coming From (e.g., muzzle Flash) Target Handoff...Surveys Cue Average Sum* Participants Muzzle Flash 7.51 34 Hostile Behaviors 7.35 40 Outgoing Fire 7.22 18 Suspicious Behaviors/Activities 6.91

Video measurement of the muzzle velocity of a potato gun

NASA Astrophysics Data System (ADS)

Jasperson, Christopher; Pollman, Anthony

2011-09-01

Using first principles, a theoretical equation for the maximum and actual muzzle velocities for a pneumatic cannon was recently derived. For a fixed barrel length, this equation suggests that the muzzle velocity can be enhanced by maximizing the product of the initial pressure and the volume of the propellant gas and decreasing the projectile mass. The present paper describes the results of experiments conducted to verify the validity of this theoretical equation. A high-speed video camera was used to quantify muzzle velocity for potatoes of varying mass exiting a pneumatic cannon for gauge pressures ranging from 310 to 830 kPa. The experiments verified that a friction modified version of the theoretical equation is qualitatively and quantitatively accurate for potato masses above 100 g.

Damage Detection of a Concrete Column Subject to Blast Loads Using Embedded Piezoceramic Transducers.

PubMed

Xu, Kai; Deng, Qingshan; Cai, Lujun; Ho, Siuchun; Song, Gangbing

2018-04-28

Some of the most severe structural loadings come in the form of blast loads, which may be caused by severe accidents or even terrorist activities. Most commonly after exposure to explosive forces, a structure will suffer from different degrees of damage, and even progress towards a state of collapse. Therefore, damage detection of a structure subject to explosive loads is of importance. This paper proposes a new approach to damage detection of a concrete column structure subjected to blast loads using embedded piezoceramic smart aggregates (SAs). Since the sensors are embedded in the structure, the proposed active-sensing based approach is more sensitive to internal or through cracks than surface damage. In the active sensing approach, the embedded SAs act as actuators and sensors, that can respectively generate and detect stress waves. If the stress wave propagates across a crack, the energy of the wave attenuates, and the reduction of the energy compared to the healthy baseline is indicative of a damage. With a damage index matrix constructed by signals obtained from an array of SAs, cracks caused by blast loads can be detected throughout the structure. Conventional sensing methods such as the measurement of dynamic strain and acceleration were included in the experiment. Since columns are critical elements needed to prevent structural collapse, knowledge of their integrity and damage conditions is essential for safety after exposure to blast loads. In this research, a concrete column with embedded SAs was chosen as the specimen, and a series of explosive tests were conducted on the column. Experimental results reveal that surface damages, though appear severe, cause minor changes in the damage index, and through cracks result in significant increase of the damage index, demonstrating the effectiveness of the active sensing, enabled by embedded SAs, in damage monitoring of the column under blast loads, and thus providing a reliable indication of structural integrity in the event of blast loads.

Damage Detection of a Concrete Column Subject to Blast Loads Using Embedded Piezoceramic Transducers

PubMed Central

Deng, Qingshan; Cai, Lujun; Ho, Siuchun; Song, Gangbing

2018-01-01

Some of the most severe structural loadings come in the form of blast loads, which may be caused by severe accidents or even terrorist activities. Most commonly after exposure to explosive forces, a structure will suffer from different degrees of damage, and even progress towards a state of collapse. Therefore, damage detection of a structure subject to explosive loads is of importance. This paper proposes a new approach to damage detection of a concrete column structure subjected to blast loads using embedded piezoceramic smart aggregates (SAs). Since the sensors are embedded in the structure, the proposed active-sensing based approach is more sensitive to internal or through cracks than surface damage. In the active sensing approach, the embedded SAs act as actuators and sensors, that can respectively generate and detect stress waves. If the stress wave propagates across a crack, the energy of the wave attenuates, and the reduction of the energy compared to the healthy baseline is indicative of a damage. With a damage index matrix constructed by signals obtained from an array of SAs, cracks caused by blast loads can be detected throughout the structure. Conventional sensing methods such as the measurement of dynamic strain and acceleration were included in the experiment. Since columns are critical elements needed to prevent structural collapse, knowledge of their integrity and damage conditions is essential for safety after exposure to blast loads. In this research, a concrete column with embedded SAs was chosen as the specimen, and a series of explosive tests were conducted on the column. Experimental results reveal that surface damages, though appear severe, cause minor changes in the damage index, and through cracks result in significant increase of the damage index, demonstrating the effectiveness of the active sensing, enabled by embedded SAs, in damage monitoring of the column under blast loads, and thus providing a reliable indication of structural integrity in the event of blast loads. PMID:29710807

The circumstellar ring of SN 1987A

NASA Astrophysics Data System (ADS)

Fransson, Claes; Migotto, Katia; Larsson, Josefin; Pesce, Dominic; Challis, Peter; Chevalier, Roger A.; France, Kevin; Kirshner, Robert P.; Leibundgut, Bruno; Lundqvist, Peter; McCray, Richard; Spyromilio, Jason; Taddia, Francesco; Jerkstrand, Anders; Mattila, Seppo; Smith, Nathan; Sollerman, Jesper; Wheeler, J. Craig; Crotts, Arlin; Garnavich, Peter; Heng, Kevin; Lawrence, Stephen S.; Panagia, Nino; Pun, Chun S. J.; Sonneborn, George; Sugerman, Ben

2016-06-01

The circumstellar ring of supernova 1987A first became visible a few months after the explosion due to photoionisation by the supernova flash. From 1995 hotspots appeared in the ring and their brightness increased nearly exponentially as a result of interaction with the supernova blast wave. Imaging and spectroscopic observations with the Hubble Space Telescope and the Very Large Telescope now show that both the shocked and the unshocked emission components from the ring have been decreasing since ~ 2009. In addition, the most recent images reveal the brightening of new spots outside the ring. These observations indicate that the hotspots are being dissolved by the shocks and that the blast wave is now expanding and interacting with dense clumps beyond the ring. Based on the currently observed decay we predict that the ring will be destroyed by ~ 2025, while the blast wave will reveal the distribution of gas as it expands outside the ring, thus tracing the mass-loss history of the supernova progenitor.

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

Synaptic Mechanisms of Blast-Induced Brain Injury

PubMed Central

Przekwas, Andrzej; Somayaji, Mahadevabharath R.; Gupta, Raj K.

2016-01-01

Blast wave-induced traumatic brain injury (TBI) is one of the most common injuries to military personnel. Brain tissue compression/tension due to blast-induced cranial deformations and shear waves due to head rotation may generate diffuse micro-damage to neuro-axonal structures and trigger a cascade of neurobiological events culminating in cognitive and neurodegenerative disorders. Although diffuse axonal injury is regarded as a signature wound of mild TBI (mTBI), blast loads may also cause synaptic injury wherein neuronal synapses are stretched and sheared. This synaptic injury may result in temporary disconnect of the neural circuitry and transient loss in neuronal communication. We hypothesize that mTBI symptoms such as loss of consciousness or dizziness, which start immediately after the insult, could be attributed to synaptic injury. Although empirical evidence is beginning to emerge; the detailed mechanisms underlying synaptic injury are still elusive. Coordinated in vitro–in vivo experiments and mathematical modeling studies can shed light into the synaptic injury mechanisms and their role in the potentiation of mTBI symptoms. PMID:26834697

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

Underbody Blast Models of TBI Caused by Hyper-Acceleration and Secondary Head Impact

DTIC Science & Technology

2016-02-01

discovery rate (FDR), which controls for the expected proportion of false rejected hypotheses. ANOVA was performed to evaluate the significance in gene...acceleration/deceleration11,27 and blast4,13 have also been designed for the purpose of evaluating coup-contrecoup and blast wave energies potentially... evaluation of different angles/ locations of the projectile impact to the surface of the rat head. Finally, pilot studies were conducted to provide further

Ultrahigh energy neutrino afterglows of nearby long duration gamma-ray bursts

NASA Astrophysics Data System (ADS)

Thomas, Jessymol K.; Moharana, Reetanjali; Razzaque, Soebur

2017-11-01

Detection of ultrahigh energy (UHE, ≳1 PeV ) neutrinos from astrophysical sources will be a major advancement in identifying and understanding the sources of UHE cosmic rays (CRs) in nature. Long duration gamma-ray burst (GRB) blast waves have been considered as potential acceleration sites of UHECRs. These CRs are expected to interact with GRB afterglow photons, which are synchrotron radiation from relativistic electrons coaccelerated with CRs in the blast wave, and naturally produce UHE neutrinos. Fluxes of these neutrinos are uncertain, however, and crucially depend on the observed afterglow modeling. We have selected a sample of 23 long duration GRBs within redshift 0.5 for which adequate electromagnetic afterglow data are available and which could produce high flux of UHE afterglow neutrinos, being nearby. We fit optical, x-ray, and γ -ray afterglow data with an adiabatic blast wave model in a constant density interstellar medium and in a wind environment where the density of the wind decreases as the inverse square of the radius from the center of the GRB. The blast wave model parameters extracted from these fits are then used for calculating UHECR acceleration and p γ interactions to produce UHE neutrino fluxes from these GRBs. We have also explored the detectability of these neutrinos by currently running and upcoming large area neutrino detectors, such as the Pierre Auger Observatory, IceCube Gen-2, and KM3NeT observatories. We find that our realistic flux models from nearby GRBs will be unconstrained in the foreseeable future.

Integrated Experimental Platforms to Study Blast Injuries: a Bottom-Up Approach

NASA Astrophysics Data System (ADS)

Bo, Chiara

2013-06-01

Developing a cellular and molecular understanding of the nature of traumatic and post-traumatic effects of blast events on live biological samples is critical for improving clinical outcomes.1 To investigate the consequences of pressure waves upon cellular structures and the underlying physiological and biochemical changes, we are using an integrated approach to study the material and biological properties of cells, tissues and organs when subjected to extreme conditions. In particular we have developed a confined Split Hopkinson Pressure Bar (SHPB) system, which allows us to subject cells in suspension or in a monolayer to compression waves of the order of few MPa and duration of hundreds of microseconds.2 The chamber design also enables recovery of the biological samples for cellular and molecular analysis. Specifically, cell survivability, viability, proliferation and morphological changes are investigated post compression for different cell populations. The SHPB platform, coupled with Quasi-Static experiments, is also used to determine stress-strain curves of soft biological tissues under compression at low, medium and high strain rates. Samples are also examined using histological techniques to study macro- and microscopical changes induced by compression waves. Finally, a shock tube has been developed to replicate primary blast damage on organs (i.e. mice lungs) and cell monolayers by generating single or multiple air blast of the order of kPa and few milliseconds duration. This platform allows us to visualize post-traumatic morphological changes at the cellular level as a function of the stimulus pressure and duration as well as biomarker signatures of blast injuries. Adapting and integrating a variety of approaches with different experimental platforms allows us to sample a vast pressure-time space in terms of biological and structural damage that mimic blast injuries and also to determine which physical parameters (peak pressure, stimulus duration, impulse) are contributing to the injury process. Moreover, understanding biological damage following blast events is crucial to developing novel clinical approaches to detect and treat traumatic injury pathologies. This work is supported by he Atomic Weapons Establishment, UK and The Royal British Legion Centre for Blast Injury Studies at Imperial College London, UK

Off-center blast in a shocked medium

NASA Astrophysics Data System (ADS)

Duncan-Miller, G. C.; Stone, W. D.

2018-07-01

When multiple blasts occur at different times, the situation arises in which a blast wave is propagating into a medium that has already been shocked. Determining the evolution in the shape of the second shock is not trivial, as it is propagating into air that is not only non-uniform, but also non-stationary. To accomplish this task, we employ the method of Kompaneets to determine the shape of a shock in a non-uniform media. We also draw from the work of Korycansky (Astrophys J 398:184-189. https://doi.org/10.1086/171847 , 1992) on an off-center explosion in a medium with radially varying density. Extending this to treat non-stationary flow, and making use of approximations to the Sedov solution for the point blast problem, we are able to determine an analytic expression for the evolving shape of the second shock. In particular, we consider the case of a shock in air at standard ambient temperature and pressure, with the second shock occurring shortly after the original blast wave reaches it, as in a sympathetic detonation.

Substantial Effect of Melanin Influencing Factors on In vitro Melanogenesis in Muzzle Melanocytes of Differently Colored Hanwoo.

PubMed

Amna, Touseef; Park, Kyoung Mi; Cho, In-Kyung; Choi, Tae Jeong; Lee, Seung Soo; Seo, Kang-Seok; Hwang, Inho

2012-07-01

The present study was designed to investigate the effect of α-melanocyte-stimulating hormone (α-MSH), nitric oxide (NO) and L-cysteine on melanin production and expression of related genes MC1R, Tyr, Tyrp-1 and Tyrp-2 in muzzle melanocytes of differently colored three native Hanwoo cattle. Muzzle samples were taken from black, brindle and brown Hanwoo and purified melanocytes were cultured with α-MSH, nitric oxide and L-cysteine at 100 nM, 50 µM and 0.07 mg/ml of media respectively. The amounts of total melanin, eumelanin and mRNA expression at Tyr, Tyrp-1, Tyrp-2 and MC1R levels were quantified. α-MSH and nitric oxide significantly increased (p<0.05) the amount of total melanin in black and brindle whereas eumelanin production in brown Hanwoo muzzle melanocytes. On the contrary, L-cysteine greatly (p<0.05) depressed the eumelanin production in black color but increased in brown. Simultaneously, up regulation of Tyr by nitric oxide and α-MSH and down regulation of Tyr, Tyrp-2 and MC1R genes by L-cysteine were observed in muzzle melanocytes of all three phenotypes. The results of this study revealed nitric oxide and α-MSH contribute hyper-pigmentation by enhancing eumelanogenesis whereas L-cysteine contributes to pheomelanin production in different colored Hanwoo muzzle melanocytes.

Substantial Effect of Melanin Influencing Factors on In vitro Melanogenesis in Muzzle Melanocytes of Differently Colored Hanwoo

PubMed Central

Amna, Touseef; Park, Kyoung Mi; Cho, In-Kyung; Choi, Tae Jeong; Lee, Seung Soo; Seo, Kang-Seok; Hwang, Inho

2012-01-01

The present study was designed to investigate the effect of α-melanocyte-stimulating hormone (α-MSH), nitric oxide (NO) and L-cysteine on melanin production and expression of related genes MC1R, Tyr, Tyrp-1 and Tyrp-2 in muzzle melanocytes of differently colored three native Hanwoo cattle. Muzzle samples were taken from black, brindle and brown Hanwoo and purified melanocytes were cultured with α-MSH, nitric oxide and L-cysteine at 100 nM, 50 µM and 0.07 mg/ml of media respectively. The amounts of total melanin, eumelanin and mRNA expression at Tyr, Tyrp-1, Tyrp-2 and MC1R levels were quantified. α-MSH and nitric oxide significantly increased (p<0.05) the amount of total melanin in black and brindle whereas eumelanin production in brown Hanwoo muzzle melanocytes. On the contrary, L-cysteine greatly (p<0.05) depressed the eumelanin production in black color but increased in brown. Simultaneously, up regulation of Tyr by nitric oxide and α-MSH and down regulation of Tyr, Tyrp-2 and MC1R genes by L-cysteine were observed in muzzle melanocytes of all three phenotypes. The results of this study revealed nitric oxide and α-MSH contribute hyper-pigmentation by enhancing eumelanogenesis whereas L-cysteine contributes to pheomelanin production in different colored Hanwoo muzzle melanocytes. PMID:25049660

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)

Spectroscopic temperature measurements in interior ballistic environments

NASA Astrophysics Data System (ADS)

Klingenberg, G.; Mach, H.

1984-11-01

Spectroscopic temperature measurements during the interior ballistic cycle of a 20 mm test fixture gun and inside the muzzle flash of a 7.62 mm rifle are described. The investigation yields information on temperature distribution in the burning propellant charge of the 20 mm test fixture and on radial temperature profiles in the 7.62 mm muzzle flash region. A technique to obtain temperature during the ignition and combustion within the 20 mm propellant charge is presented. Additional in-bore measurements by quartz windows mounted into bores along the barrel and emission-absorption measurements inside the muzzle flash of the 20 mm test fixture yield a complete temperature profile for the gun system. Spectroscopic infrared measurements inside the muzzle flash of a 7.62 mm rifle complete the investigation.

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

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

Test Operations Procedure (TOP) 03-2-830A Stability Test of Indirect Fire Artillery Weapons

DTIC Science & Technology

2013-02-20

0.01 degree 0 to 6400 mil; ± 1 mil Powder thermometer -55 to +40 °Celsius (C); ± 1 °C Muzzle velocity radar 42 to 1200 meters/second; ± 4...Gun crew 2 Geodetics personnel 1 Muzzle velocity radar operator 2 HS and regular videographer 2 Wiebel tracking radar operator 1...fire. d. Install the muzzle velocity radar at the test weapon. e. Verify test weapons boresight before and after firing each group. f

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

NASA Technical Reports Server (NTRS)

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

1973-01-01

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

Dynamic Pressure Impulse for Near-Ideal and Non-Ideal Blast Waves -- Height of Burst Charts. Supplement

DTIC Science & Technology

1983-12-31

Law 79-565), 22 April 1967. Other requests shall be referred to Director, Defense Nuclear Agency, Washington, DC 20305- 10101. THIS WORK WAS SPONSORED...JPUMNTNYNOTATIO This work was sponsored by the Defense Nuclear Agency under RDT&E RMSS Code 8344082466 Y99QAXSGO0039 H25900. I?. cosASI comR I& SUISCI TM...displacement which a vehicle exposed to a blast wave sufers can be used as a measure of the dynamic pressure impulse it receives. ,hat is, the vehicle

Astrophysical blast wave data

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

Riley, Nathan; Geissel, Matthias; Lewis, Sean M

2015-03-01

The data described in this document consist of image files of shadowgraphs of astrophysically relevant laser driven blast waves. Supporting files include Mathematica notebooks containing design calculations, tabulated experimental data and notes, and relevant publications from the open research literature. The data was obtained on the Z-Beamlet laser from July to September 2014. Selected images and calculations will be published as part of a PhD dissertation and in associated publications in the open research literature, with Sandia credited as appropriate. The authors are not aware of any restrictions that could affect the release of the data.

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

Blast-wave model description of the Hanbury-Brown-Twiss radii in pp collisions at LHC energies

NASA Astrophysics Data System (ADS)

Bialas, Andrzej; Florkowski, Wojciech; Zalewski, Kacper

2015-04-01

The blast wave model is applied to the recent data on Hanbury-Brown-Twiss radii in pp collisions, measured by the ALICE Collaboration. A reasonable description of data is obtained for a rather low temperature of the kinetic freeze-out, T≃ 100 MeV, and the transverse profile corresponding to the emission from a shell of a fairly small width 2δ ˜ 1.5 fm. The size and the life-time of the produced system are determined for various multiplicities of the produced particles.

Another self-similar blast wave: Early time asymptote with shock heated electrons and high thermal conductivity

NASA Technical Reports Server (NTRS)

Cox, D. P.; Edgar, R. J.

1982-01-01

Accurate approximations are presented for the self-similar structures of nonradiating blast waves with adiabatic ions, isothermal electrons, and equation ion and electron temperatures at the shock. The cases considered evolve in cavities with power law ambient densities (including the uniform density case) and have negligible external pressure. The results provide the early time asymptote for systems with shock heating of electrons and strong thermal conduction. In addition, they provide analytical results against which two fluid numerical hydrodynamic codes can be checked.

Blast Wave Experiments at Z

DTIC Science & Technology

2007-06-01

radiation flows upward, it passes though a 1.7-mm high, tapered, 25-μm thick gold wall cone that is filled 20 ± 3 mg/cm3 silica aerogel (SiO2). Above...this cone is a 20 ± 3 mg/cm3 silica aerogel filled, 1-mm high, 2.4-mm inner diameter, 25-μm thick gold wall cylinder. On the cylinder rests a 4-mm...diameter gold platform that supports a higher density (40-60 mg/cm3) silica aerogel . This aerogel is the region where the blast wave forms after

Numerical modeling of deflagration mode in coaxial plasma guns

NASA Astrophysics Data System (ADS)

Sitaraman, Hariswaran; Raja, Laxminarayan

2012-10-01

Pulsed coaxial plasma guns have been used in several applications in the field of space propulsion, nuclear fusion and materials processing. These devices operate in two modes based on the delay between gas injection and breakdown initiation. Larger delay led to the plasma detonation mode where a compression wave in the form of a luminous front propagates from the breech to the muzzle. Shorter delay led to the more efficient deflagration mode characterized by a relatively diffuse plasma with higher resistivity. The overall physics of the discharge in the two modes of operation and in particular the latter remain relatively unexplored. Here we perform a computational modeling study by solving the non-ideal Magneto-hydrodynamics equations for the quasi-neutral plasma in the coaxial plasma gun. A finite volume formulation on an unstructured mesh framework with an implicit scheme is used to do stable computations. The final work will present details of important species in the plasma, particle energies and Mach number at the muzzle. A comparison of the plasma parameters will be made with the experiments reported in ref. [1]. [4pt] [1] F. R. Poehlmann et al., Phys. Plasmas 17, 123508 (2010)

Internal ballistics of the detonation products of a blast-hole charge

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

Mangush, S.K.; Garbunov, V.A.

1986-07-01

The authors investigate the gasdynamic flow of the detonation products of a blast-hole charge (the expansion of the detonation products in the blast hole and the gas outflow and propagation of shock airwaves into the face space). The problem is solved by means of a numerical program for integration of partial differential equations of one-dimensional gas-dynamics. A numerical model of the internal ballistics of a blast-hole charge is presented. In addition to the variation of the thermodynamic parameters in the blast hole, the formation of the shock wave in the face space is shown, which is the source of gasmore » ignition. Further development of the numerical model of the action of blast-hole charges is planned which will involve an analysis of a number of applied problems.« less

Bomb blast mass casualty incidents: initial triage and management of injuries.

PubMed

Goh, S H

2009-01-01

Bomb blast injuries are no longer confined to battlefields. With the ever present threat of terrorism, we should always be prepared for bomb blasts. Bomb blast injuries tend to affect air-containing organs more, as the blast wave tends to exert a shearing force on air-tissue interfaces. Commonly-injured organs include the tympanic membranes, the sinuses, the lungs and the bowel. Of these, blast lung injury is the most challenging to treat. The clinical picture is a mix of acute respiratory distress syndrome and air embolism, and the institution of positive pressure ventilation in the presence of low venous pressures could cause systemic arterial air embolism. The presence of a tympanic membrane perforation is not a reliable indicator of the presence of a blast injury in the other air-containing organs elsewhere. Radiological imaging of the head, chest and abdomen help with the early identification of blast lung injury, head injury, abdominal injury, eye and sinus injuries, as well as any penetration by foreign bodies. In addition, it must be borne in mind that bomb blasts could also be used to disperse radiological and chemical agents.

The Internal Ballistics of an Air Gun

NASA Astrophysics Data System (ADS)

Denny, Mark

2011-02-01

The internal ballistics of a firearm or artillery piece considers the pellet, bullet, or shell motion while it is still inside the barrel. In general, deriving the muzzle speed of a gunpowder firearm from first principles is difficult because powder combustion is fast and it very rapidly raises the temperature of gas (generated by gunpowder deflagration, or burning), which greatly complicates the analysis. A simple case is provided by air guns, for which we can make reasonable approximations that permit a derivation of muzzle speed. It is perhaps surprising that muzzle speed depends upon barrel length (artillerymen debated this dependence for centuries, until it was established experimentally and, later, theoretically ). Here we see that a simple physical analysis, accessible to high school or freshmen undergraduate physics students, not only derives realistic muzzle speed but also shows how it depends upon barrel length.

Novel approach for low-cost muzzle flash detection system

NASA Astrophysics Data System (ADS)

Voskoboinik, Asher

2008-04-01

A low-cost muzzle flash detection based on CMOS sensor technology is proposed. This low-cost technology makes it possible to detect various transient events with characteristic times between dozens of microseconds up to dozens of milliseconds while sophisticated algorithms successfully separate them from false alarms by utilizing differences in geometrical characteristics and/or temporal signatures. The proposed system consists of off-the-shelf smart CMOS cameras with built-in signal and image processing capabilities for pre-processing together with allocated memory for storing a buffer of images for further post-processing. Such a sensor does not require sending giant amounts of raw data to a real-time processing unit but provides all calculations in-situ where processing results are the output of the sensor. This patented CMOS muzzle flash detection concept exhibits high-performance detection capability with very low false-alarm rates. It was found that most false-alarms due to sun glints are from sources at distances of 500-700 meters from the sensor and can be distinguished by time examination techniques from muzzle flash signals. This will enable to eliminate up to 80% of falsealarms due to sun specular reflections in the battle field. Additional effort to distinguish sun glints from suspected muzzle flash signal is made by optimization of the spectral band in Near-IR region. The proposed system can be used for muzzle detection of small arms, missiles and rockets and other military applications.

Photographic laboratory studies of explosions.

NASA Technical Reports Server (NTRS)

Kamel, M. M.; Oppenheim, A. K.

1973-01-01

Description of a series of cinematographic studies of explosions made with a high-speed rotating-mirror streak camera which uses a high-frequency stroboscopic ruby laser as the light source. The results obtained mainly concern explosions initiated by focused laser irradiation from a pulsed neodymium laser in a detonating gas consisting essentially of an equimolar mixture of acetylene and oxygen at an initial pressure of 100 torr at room temperature. Among the most significant observations were observations of a spherical blast wave preceded by a Chapman-Jouguet detonation which is stabilized immediately after initiation, the merging of a spherical flame with a shock front of the blast wave in which the flame is propagating, the division of a spherical detonation front into a shock wave and flame, and the generation of shock waves by a network of spherical flames.

Molecular Signatures and Diagnostic Biomarkers of Cumulative, Blast-Graded Mild TBI

DTIC Science & Technology

2012-10-01

These results are in agreement with data obtained using non-blast TBI models (Diet- rich et al., 2004; Maegele et al., 2007). Moreover, CX3CL1 chemokine...the shoulder at Figure 1A), substantially contaminating the blast wave in the direction of shock tube axis (Figure 1A). In addition, the exhaust...highly spe- cific for the CNS and is present in platelets and red blood cells (see Svetlov et al., 2009 for review). In previous studies, we reported a

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

The Acceleration of Charged Particles at a Spherical Shock Moving through an Irregular Magnetic Field

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

Giacalone, J.

We investigate the physics of charged-particle acceleration at spherical shocks moving into a uniform plasma containing a turbulent magnetic field with a uniform mean. This has applications to particle acceleration at astrophysical shocks, most notably, to supernovae blast waves. We numerically integrate the equations of motion of a large number of test protons moving under the influence of electric and magnetic fields determined from a kinematically defined plasma flow associated with a radially propagating blast wave. Distribution functions are determined from the positions and velocities of the protons. The unshocked plasma contains a magnetic field with a uniform mean andmore » an irregular component having a Kolmogorov-like power spectrum. The field inside the blast wave is determined from Maxwell’s equations. The angle between the average magnetic field and unit normal to the shock varies with position along its surface. It is quasi-perpendicular to the unit normal near the sphere’s equator, and quasi-parallel to it near the poles. We find that the highest intensities of particles, accelerated by the shock, are at the poles of the blast wave. The particles “collect” at the poles as they approximately adhere to magnetic field lines that move poleward from their initial encounter with the shock at the equator, as the shock expands. The field lines at the poles have been connected to the shock the longest. We also find that the highest-energy protons are initially accelerated near the equator or near the quasi-perpendicular portion of the shock, where the acceleration is more rapid.« less

Collimation and Asymmetry of the Hot Blast Wave from the Recurrent Nova V745 Sco

NASA Astrophysics Data System (ADS)

Drake, Jeremy J.; Delgado, Laura; Laming, J. Martin; Starrfield, Sumner; Kashyap, Vinay; Orlando, Salvatore; Page, Kim L.; Hernanz, M.; Ness, J.-U.; Gehrz, R. D.; van Rossum, Daan; Woodward, Charles E.

2016-07-01

The recurrent symbiotic nova V745 Sco exploded on 2014 February 6 and was observed on February 22 and 23 by the Chandra X-ray Observatory Transmission Grating Spectrometers. By that time the supersoft source phase had already ended, and Chandra spectra are consistent with emission from a hot, shock-heated circumstellar medium with temperatures exceeding 107 K. X-ray line profiles are more sharply peaked than expected for a spherically symmetric blast wave, with a full width at zero intensity of approximately 2400 km s-1, an FWHM of 1200 ± 30 km s-1, and an average net blueshift of 165 ± 10 km s-1. The red wings of lines are increasingly absorbed toward longer wavelengths by material within the remnant. We conclude that the blast wave was sculpted by an aspherical circumstellar medium in which an equatorial density enhancement plays a role, as in earlier symbiotic nova explosions. Expansion of the dominant X-ray-emitting material is aligned close to the plane of the sky and is most consistent with an orbit seen close to face-on. Comparison of an analytical blast wave model with the X-ray spectra, Swift observations, and near-infrared line widths indicates that the explosion energy was approximately 1043 erg and confirms an ejected mass of approximately 10-7 M ⊙. The total mass lost is an order of magnitude lower than the accreted mass required to have initiated the explosion, indicating that the white dwarf is gaining mass and is a Type Ia supernova progenitor candidate.

Gunshot residue patterns on skin in angled contact and near contact gunshot wounds.

PubMed

Plattner, T; Kneubuehl, B; Thali, M; Zollinger, U

2003-12-17

The goal of this study was the reproduction of shape and pattern of gunshot residues in near contact and contact gunshot wounds by a series of experimental gunshots on a skin and soft tissue model. The aim was to investigate the shape and direction of soot deposits with regard to the muzzle according to different muzzle-target angles, firing distances, type of ammunition and weapon and barrel length. Based on a review of the literature and on the results of the experiments the authors could make the following statements of gunshot residues in angled contact and close contact gunshot: (1) gunshot residues on the target surface can be differentiated in a "inner" and "outer powder soot zone"; (2) the outer powder soot zone is much less visible than the inner powder soot zone and may lack on human skin; (3) with increasing muzzle target distance both inner and outer powder soot halo increase in size and decrease in density; (4) in angled shots the inner powder soot halo shows an eccentric, elliptic shape which points towards the muzzle, regardless of ammunition, calibre and barrel length; (5) the outer powder soot points away from the muzzle in angled contact and close contact shots.

Ultrafast Fabry-Perot fiber-optic pressure sensors for multimedia blast event measurements.

PubMed

Zou, Xiaotian; Wu, Nan; Tian, Ye; Zhang, Yang; Fitek, John; Maffeo, Michael; Niezrecki, Christopher; Chen, Julie; Wang, Xingwei

2013-02-20

A shock wave (SW) is characterized as a large pressure fluctuation that typically lasts only a few milliseconds. On the battlefield, SWs pose a serious threat to soldiers who are exposed to explosions, which may lead to blast-induced traumatic brain injuries. SWs can also be used beneficially and have been applied to a variety of medical treatments due to their unique interaction with tissues and cells. Consequently, it is important to have sensors that can quantify SW dynamics in order to better understand the physical interaction between body tissue and the incident acoustic wave. In this paper, the ultrafast fiber-optic sensor based on the Fabry-Perot interferometric principle was designed and four such sensors were fabricated to quantify a blast event within different media, simultaneously. The compact design of the fiber-optic sensor allows for a high degree of spatial resolution when capturing the wavefront of the traveling SW. Several blast event experiments were conducted within different media (e.g., air, rubber membrane, and water) to evaluate the sensor's performance. This research revealed valuable knowledge for further study of SW behavior and SW-related applications.

Spectroscopic measurements of muzzle flash plasma

NASA Astrophysics Data System (ADS)

Uglum, J. R.

1986-11-01

The experimental apparatus and sample data for the muzzle flash plasma of a laboratory-scale railgun are described. Theoretical predictions for the railgun system configuration used indicated that 24 kJ of energy would be dissipated by the muzzle flash. Spectral data were recorded with a spectrograph sensing through a slit and a PIN diode, the latter to obtain temporal resolution in the data. The tests featured a plastic projectile with an Al foil armature. The measurements identified Cu as the dominant flash material, ablated from the rails in the barrel.

A Wireless Intracranial Brain Deformation Sensing System for Blast-Induced Traumatic Brain Injury

PubMed Central

Song, S.; Race, N. S.; Kim, A.; Zhang, T.; Shi, R.; Ziaie, B.

2015-01-01

Blast-induced traumatic brain injury (bTBI) has been linked to a multitude of delayed-onset neurodegenerative and neuropsychiatric disorders, but complete understanding of their pathogenesis remains elusive. To develop mechanistic relationships between bTBI and post-blast neurological sequelae, it is imperative to characterize the initiating traumatic mechanical events leading to eventual alterations of cell, tissue, and organ structure and function. This paper presents a wireless sensing system capable of monitoring the intracranial brain deformation in real-time during the event of a bTBI. The system consists of an implantable soft magnet and an external head-mounted magnetic sensor that is able to measure the field in three dimensions. The change in the relative position of the soft magnet WITH respect to the external sensor as the result of the blast wave induces changes in the magnetic field. The magnetic field data in turn is used to extract the temporal and spatial motion of the brain under the blast wave in real-time. The system has temporal and spatial resolutions of 5 μs and 10 μm. Following the characterization and validation of the sensor system, we measured brain deformations in a live rodent during a bTBI. PMID:26586273

Neurodegeneration and Vision Loss after Mild Blunt Trauma in the C57Bl/6 and DBA/2J Mouse

PubMed Central

Bricker-Anthony, Courtney; Rex, Tonia S.

2015-01-01

Damage to the eye from blast exposure can occur as a result of the overpressure air-wave (primary injury), flying debris (secondary injury), blunt force trauma (tertiary injury), and/or chemical/thermal burns (quaternary injury). In this study, we investigated damage in the contralateral eye after a blast directed at the ipsilateral eye in the C57Bl/6J and DBA/2J mouse. Assessments of ocular health (gross pathology, electroretinogram recordings, optokinetic tracking, optical coherence tomography and histology) were performed at 3, 7, 14 and 28 days post-trauma. Olfactory epithelium and optic nerves were also examined. Anterior pathologies were more common in the DBA/2J than in the C57Bl/6 and could be prevented with non-medicated viscous eye drops. Visual acuity decreased over time in both strains, but was more rapid and severe in the DBA/2J. Retinal cell death was present in approximately 10% of the retina at 7 and 28 days post-blast in both strains. Approximately 60% of the cell death occurred in photoreceptors. Increased oxidative stress and microglial reactivity was detected in both strains, beginning at 3 days post-injury. However, there was no sign of injury to the olfactory epithelium or optic nerve in either strain. Although our model directs an overpressure air-wave at the left eye in a restrained and otherwise protected mouse, retinal damage was detected in the contralateral eye. The lack of damage to the olfactory epithelium and optic nerve, as well as the different timing of cell death as compared to the blast-exposed eye, suggests that the injuries were due to physical contact between the contralateral eye and the housing chamber of the blast device and not propagation of the blast wave through the head. Thus we describe a model of mild blunt eye trauma. PMID:26148200

Blast overpressure after tire explosion: a fatal case.

PubMed

Pomara, Cristoforo; D'Errico, Stefano; Riezzo, Irene; Perilli, Gabriela; Volpe, Umberto; Fineschi, Vittorio

2013-12-01

Fatal blast injuries are generally reported in literature as a consequence of the detonation of explosives in war settings. The pattern of lesion depends on the position of the victim in relation to the explosion, on whether the blast tracks through air or water, and whether it happens in the open air or within an enclosed space and the distance from the explosion. Tire explosion-related injuries are rarely reported in literature. This study presents a fatal case of blast overpressure due to the accidental explosion of a truck tire occurring in a tire repair shop. A multidisciplinary approach to the fatality involving forensic pathologists and engineers revealed that the accidental explosion, which caused a series of primary and tertiary blast wave injuries, was due to tire deterioration.

Stochastic Lanchester Air-To-Air Campaign Model: Methods Used to Generate Model Outputs and a User’s Guide: 2007

DTIC Science & Technology

2007-05-01

only the non-dimensional parameter Kill Rate Ra- tio = KRR = κ = kb/kr: . [Eq. 2-6] 1(0)Pexcept0(0)P Mmb,κPmP Nnr, nPP ;NnrandMmb ,nPκPm)Pnκ(mP NM,nm...varies with explosive yield E. Dy- namic overpressure p is proportional to the square of the air velocity v immedi- ately behind the blast wave ...ρ and the time t required for the blast wave to reach the locations of interest. According to the principles of dimensional analysis, v can be

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

Computation of viscous blast wave flowfields

NASA Technical Reports Server (NTRS)

Atwood, Christopher A.

1991-01-01

A method to determine unsteady solutions of the Navier-Stokes equations was developed and applied. The structural finite-volume, approximately factored implicit scheme uses Newton subiterations to obtain the spatially and temporally second-order accurate time history of the interaction of blast-waves with stationary targets. The inviscid flux is evaluated using MacCormack's modified Steger-Warming flux or Roe flux difference splittings with total variation diminishing limiters, while the viscous flux is computed using central differences. The use of implicit boundary conditions in conjunction with a telescoping in time and space method permitted solutions to this strongly unsteady class of problems. Comparisons of numerical, analytical, and experimental results were made in two and three dimensions. These comparisons revealed accurate wave speed resolution with nonoscillatory discontinuity capturing. The purpose of this effort was to address the three-dimensional, viscous blast-wave problem. Test cases were undertaken to reveal these methods' weaknesses in three regimes: (1) viscous-dominated flow; (2) complex unsteady flow; and (3) three-dimensional flow. Comparisons of these computations to analytic and experimental results provided initial validation of the resultant code. Addition details on the numerical method and on the validation can be found in the appendix. Presently, the code is capable of single zone computations with selection of any permutation of solid wall or flow-through boundaries.

Skull flexure as a contributing factor in the mechanism of injury in the rat when exposed to a shock wave.

PubMed

Bolander, Richard; Mathie, Blake; Bir, Cynthia; Ritzel, David; VandeVord, Pamela

2011-10-01

The manner in which energy from an explosion is transmitted into the brain is currently a highly debated topic within the blast injury community. This study was conducted to investigate the injury biomechanics causing blast-related neurotrauma in the rat. Biomechanical responses of the rat head under shock wave loading were measured using strain gauges on the skull surface and a fiber optic pressure sensor placed within the cortex. MicroCT imaging techniques were applied to quantify skull bone thickness. The strain gauge results indicated that the response of the rat skull is dependent on the intensity of the incident shock wave; greater intensity shock waves cause greater deflections of the skull. The intracranial pressure (ICP) sensors indicated that the peak pressure developed within the brain was greater than the peak side-on external pressure and correlated with surface strain. The bone plates between the lambda, bregma, and midline sutures are probable regions for the greatest flexure to occur. The data provides evidence that skull flexure is a likely candidate for the development of ICP gradients within the rat brain. This dependency of transmitted stress on particular skull dynamics for a given species should be considered by those investigating blast-related neurotrauma using animal models.

Shock waves; Proceedings of the 18th International Symposium, Sendai, Japan, July 21-26, 1991. Vols. 1 & 2

NASA Astrophysics Data System (ADS)

Takayama, Kazuyoshi

Various papers on shock waves are presented. The general topics addressed include: shock wave structure, propagation, and interaction; shock wave reflection, diffraction, refraction, and focusing; shock waves in condensed matter; shock waves in dusty gases and multiphase media; hypersonic flows and shock waves; chemical processes and related combustion phenomena; explosions, blast waves, and laser initiation of shock waves; shock tube technology and instrumentation; CFD of shock wave phenomena; medical applications and biological effects; industrial applications.

Informative breath: olfactory cues sought during social foraging among Old World monkeys (Mandrillus sphinx, M. Leucophaeus, and Papio anubis).

PubMed

Laidre, Mark E

2009-02-01

Sociality provides a unique opportunity for animals to acquire information and learn from others. Especially during foraging, where trial-and-error food selection might be fatal, conspecifics could act as valuable sources of information. During a six-year study across captive, semifree ranging, and wild Old World monkeys, I investigated whether individuals garnered olfactory-based information from their group mates that could guide their feeding decisions. Each of three study species [mandrills (Mandrillus sphinx), drills (M. leucophaeus), and olive baboons (Papio anubis)] performed a prominent muzzle-muzzle behavior, potentially enabling individuals to smell others' mouths and determine via olfaction what foods their conspecifics had chosen. This muzzle-muzzle behavior (1) was preferentially directed by naïve, younger individuals toward more experienced, older individuals, (2) occurred specifically while recipients were chewing and hence emitting the most potent chemical cues, (3) was typically followed by the actor consuming the very same food type the recipient had been eating, (4) was elicited most often in response to experiments involving novel foods, and (5) occurred less frequently as initially novel foods became more familiar. In contrast to this evidence for information acquisition, there was little support for previous proposals suggesting that muzzle-muzzle functions as a social display. Instead, the omnivorous diets and intensely social lifestyles of mandrills, drills, and baboons, may have each favored a convergent form of information acquisition: seeking out the breath of knowledgeable conspecifics to help decide what foods are safe to eat. Copyright 2009 APA, all rights reserved.

21. VAL, DETAIL OF MUZZLE END OF LAUNCHER BRIDGE SHOWING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

21. VAL, DETAIL OF MUZZLE END OF LAUNCHER BRIDGE SHOWING BOTH LAUNCHER TUBES TAKEN FROM RESERVOIR LOOKING NORTH. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

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.

Low-cost rapid miniature optical pressure sensors for blast wave measurements.

PubMed

Wu, Nan; Wang, Wenhui; Tian, Ye; Zou, Xiaotian; Maffeo, Michael; Niezrecki, Christopher; Chen, Julie; Wang, Xingwei

2011-05-23

This paper presents an optical pressure sensor based on a Fabry-Perot (FP) interferometer formed by a 45° angle polished single mode fiber and an external silicon nitride diaphragm. The sensor is comprised of two V-shape grooves with different widths on a silicon chip, a silicon nitride diaphragm released on the surface of the wider V-groove, and a 45° angle polished single mode fiber. The sensor is especially suitable for blast wave measurements: its compact structure ensures a high spatial resolution; its thin diaphragm based design and the optical demodulation scheme allow a fast response to the rapid changing signals experienced during blast events. The sensor shows linearity with the correlation coefficient of 0.9999 as well as a hysteresis of less than 0.3%. The shock tube test demonstrated that the sensor has a rise time of less than 2 µs from 0 kPa to 140 kPa.

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.

Spectral measurements of muzzle flash with multispectral and hyperspectral sensor

NASA Astrophysics Data System (ADS)

Kastek, M.; Dulski, R.; Trzaskawka, P.; Piątkowski, T.; Polakowski, H.

2011-08-01

The paper presents some practical aspects of the measurements of muzzle flash signatures. Selected signatures of sniper shot in typical scenarios has been presented. Signatures registered during all phases of muzzle flash were analyzed. High precision laboratory measurements were made in a special ballistic laboratory and as a result several flash patterns were registered. The field measurements of a muzzle flash were also performed. During the tests several infrared cameras were used, including the measurement class devices with high accuracy and frame rates. The registrations were made in NWIR, SWIR and LWIR spectral bands simultaneously. An ultra fast visual camera was also used for visible spectra registration. Some typical infrared shot signatures were presented. Beside the cameras, the LWIR imaging spectroradiometer HyperCam was also used during the laboratory experiments and the field tests. The signatures collected by the HyperCam device were useful for the determination of spectral characteristics of the muzzle flash, whereas the analysis of thermal images registered during the tests provided the data on temperature distribution in the flash area. As a result of the measurement session the signatures of several types handguns, machine guns and sniper rifles were obtained which will be used in the development of passive infrared systems for sniper detection.

Comparison of methods to determine methane emissions from dairy cows in farm conditions.

PubMed

Huhtanen, P; Cabezas-Garcia, E H; Utsumi, S; Zimmerman, S

2015-05-01

Nutritional and animal-selection strategies to mitigate enteric methane (CH4) depend on accurate, cost-effective methods to determine emissions from a large number of animals. The objective of the present study was to compare 2 spot-sampling methods to determine CH4 emissions from dairy cows, using gas quantification equipment installed in concentrate feeders or automatic milking stalls. In the first method (sniffer method), CH4 and carbon dioxide (CO2) concentrations were measured in close proximity to the muzzle of the animal, and average CH4 concentrations or CH4/CO2 ratio was calculated. In the second method (flux method), measurement of CH4 and CO2 concentration was combined with an active airflow inside the feed troughs for capture of emitted gas and measurements of CH4 and CO2 fluxes. A muzzle sensor was used allowing data to be filtered when the muzzle was not near the sampling inlet. In a laboratory study, a model cow head was built that emitted CO2 at a constant rate. It was found that CO2 concentrations using the sniffer method decreased up to 39% when the distance of the muzzle from the sampling inlet increased to 30cm, but no muzzle-position effects were observed for the flux method. The methods were compared in 2 on-farm studies conducted using 32 (experiment 1) or 59 (experiment 2) cows in a switch-back design of 5 (experiment 1) or 4 (experiment 2) periods for replicated comparisons between methods. Between-cow coefficient of variation (CV) in CH4 was smaller for the flux than the sniffer method (experiment 1, CV=11.0 vs. 17.5%, and experiment 2, 17.6 vs. 28.0%). Repeatability of the measurements from both methods were high (0.72-0.88), but the relationship between the sniffer and flux methods was weak (R(2)=0.09 in both experiments). With the flux method CH4 was found to be correlated to dry matter intake or body weight, but this was not the case with the sniffer method. The CH4/CO2 ratio was more highly correlated between the flux and sniffer methods (R(2)=0.30), and CV was similar (6.4-8.8%). In experiment 2, cow muzzle position was highly repeatable (0.82) and influenced sniffer and flux method results when not filtered for muzzle position. It was concluded that the flux method provides more reliable estimates of CH4 emissions than the sniffer method. The sniffer method appears to be affected by variable air-mixing conditions created by geometry of feed trough, muzzle movement, and muzzle position. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

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.

COLLIMATION AND ASYMMETRY OF THE HOT BLAST WAVE FROM THE RECURRENT NOVA V745 Sco

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

Drake, Jeremy J.; Kashyap, Vinay; Delgado, Laura

The recurrent symbiotic nova V745 Sco exploded on 2014 February 6 and was observed on February 22 and 23 by the Chandra X-ray Observatory Transmission Grating Spectrometers. By that time the supersoft source phase had already ended, and Chandra spectra are consistent with emission from a hot, shock-heated circumstellar medium with temperatures exceeding 10{sup 7} K. X-ray line profiles are more sharply peaked than expected for a spherically symmetric blast wave, with a full width at zero intensity of approximately 2400 km s{sup 1}, an FWHM of 1200 ± 30 km s{sup 1}, and an average net blueshift of 165more » ± 10 km s{sup 1}. The red wings of lines are increasingly absorbed toward longer wavelengths by material within the remnant. We conclude that the blast wave was sculpted by an aspherical circumstellar medium in which an equatorial density enhancement plays a role, as in earlier symbiotic nova explosions. Expansion of the dominant X-ray-emitting material is aligned close to the plane of the sky and is most consistent with an orbit seen close to face-on. Comparison of an analytical blast wave model with the X-ray spectra, Swift observations, and near-infrared line widths indicates that the explosion energy was approximately 10{sup 43} erg and confirms an ejected mass of approximately 10{sup 7} M {sub ⊙}. The total mass lost is an order of magnitude lower than the accreted mass required to have initiated the explosion, indicating that the white dwarf is gaining mass and is a Type Ia supernova progenitor candidate.« less

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.

Chronic Traumatic Encephalopathy in Blast-Exposed Military Veterans and a Blast Neurotrauma Mouse Model

PubMed Central

Goldstein, Lee E.; Fisher, Andrew M.; Tagge, Chad A.; Zhang, Xiao-Lei; Velisek, Libor; Sullivan, John A.; Upreti, Chirag; Kracht, Jonathan M.; Ericsson, Maria; Wojnarowicz, Mark W.; Goletiani, Cezar J.; Maglakelidze, Giorgi M.; Casey, Noel; Moncaster, Juliet A.; Minaeva, Olga; Moir, Robert D.; Nowinski, Christopher J.; Stern, Robert A.; Cantu, Robert C.; Geiling, James; Blusztajn, Jan K.; Wolozin, Benjamin L.; Ikezu, Tsuneya; Stein, Thor D.; Budson, Andrew E.; Kowall, Neil W.; Chargin, David; Sharon, Andre; Saman, Sudad; Hall, Garth F.; Moss, William C.; Cleveland, Robin O.; Tanzi, Rudolph E.; Stanton, Patric K.; McKee, Ann C.

2013-01-01

Blast exposure is associated with traumatic brain injury (TBI), neuropsychiatric symptoms, and long-term cognitive disability. We examined a case series of postmortem brains from U.S. military veterans exposed to blast and/or concussive injury. We found evidence of chronic traumatic encephalopathy (CTE), a tau protein–linked neurodegenerative disease, that was similar to the CTE neuropathology observed in young amateur American football players and a professional wrestler with histories of concussive injuries. We developed a blast neurotrauma mouse model that recapitulated CTE-linked neuropathology in wild-type C57BL/6 mice 2 weeks after exposure to a single blast. Blast-exposed mice demonstrated phosphorylated tauopathy, myelinated axonopathy, microvasculopathy, chronic neuroinflammation, and neurodegeneration in the absence of macroscopic tissue damage or hemorrhage. Blast exposure induced persistent hippocampal-dependent learning and memory deficits that persisted for at least 1 month and correlated with impaired axonal conduction and defective activity-dependent long-term potentiation of synaptic transmission. Intracerebral pressure recordings demonstrated that shock waves traversed the mouse brain with minimal change and without thoracic contributions. Kinematic analysis revealed blast-induced head oscillation at accelerations sufficient to cause brain injury. Head immobilization during blast exposure prevented blast-induced learning and memory deficits. The contribution of blast wind to injurious head acceleration may be a primary injury mechanism leading to blast-related TBI and CTE. These results identify common pathogenic determinants leading to CTE in blast-exposed military veterans and head-injured athletes and additionally provide mechanistic evidence linking blast exposure to persistent impairments in neurophysiological function, learning, and memory. PMID:22593173

Chronic traumatic encephalopathy in blast-exposed military veterans and a blast neurotrauma mouse model.

PubMed

Goldstein, Lee E; Fisher, Andrew M; Tagge, Chad A; Zhang, Xiao-Lei; Velisek, Libor; Sullivan, John A; Upreti, Chirag; Kracht, Jonathan M; Ericsson, Maria; Wojnarowicz, Mark W; Goletiani, Cezar J; Maglakelidze, Giorgi M; Casey, Noel; Moncaster, Juliet A; Minaeva, Olga; Moir, Robert D; Nowinski, Christopher J; Stern, Robert A; Cantu, Robert C; Geiling, James; Blusztajn, Jan K; Wolozin, Benjamin L; Ikezu, Tsuneya; Stein, Thor D; Budson, Andrew E; Kowall, Neil W; Chargin, David; Sharon, Andre; Saman, Sudad; Hall, Garth F; Moss, William C; Cleveland, Robin O; Tanzi, Rudolph E; Stanton, Patric K; McKee, Ann C

2012-05-16

Blast exposure is associated with traumatic brain injury (TBI), neuropsychiatric symptoms, and long-term cognitive disability. We examined a case series of postmortem brains from U.S. military veterans exposed to blast and/or concussive injury. We found evidence of chronic traumatic encephalopathy (CTE), a tau protein-linked neurodegenerative disease, that was similar to the CTE neuropathology observed in young amateur American football players and a professional wrestler with histories of concussive injuries. We developed a blast neurotrauma mouse model that recapitulated CTE-linked neuropathology in wild-type C57BL/6 mice 2 weeks after exposure to a single blast. Blast-exposed mice demonstrated phosphorylated tauopathy, myelinated axonopathy, microvasculopathy, chronic neuroinflammation, and neurodegeneration in the absence of macroscopic tissue damage or hemorrhage. Blast exposure induced persistent hippocampal-dependent learning and memory deficits that persisted for at least 1 month and correlated with impaired axonal conduction and defective activity-dependent long-term potentiation of synaptic transmission. Intracerebral pressure recordings demonstrated that shock waves traversed the mouse brain with minimal change and without thoracic contributions. Kinematic analysis revealed blast-induced head oscillation at accelerations sufficient to cause brain injury. Head immobilization during blast exposure prevented blast-induced learning and memory deficits. The contribution of blast wind to injurious head acceleration may be a primary injury mechanism leading to blast-related TBI and CTE. These results identify common pathogenic determinants leading to CTE in blast-exposed military veterans and head-injured athletes and additionally provide mechanistic evidence linking blast exposure to persistent impairments in neurophysiological function, learning, and memory.

Wounding capacity of muzzle-gas pressure.

PubMed

Schyma, Christian

2012-05-01

Suicidal gunshot wounds that are caused by ammunition fired from a 9-mm Luger pistol, with direct contact between the gun muzzle and the victim's head, present a serious injury pattern even with full metal jacket bullets. Wound ballistic experiments were performed to clarify whether muzzle gases from the firearm have an additional wounding potential. Fifteen head models were prepared as follows: an acryl sphere measuring 14 cm in diameter was completely covered with a layer of silicon that was 3 mm thick. These spheres were filled with 10% gelatine. At 4°C, these models were fired at with a 9-mm Luger pistol, loaded with Quick Defense 1 expanding bullets. Five shots were fired with direct muzzle contact, one shot was fired from a distance of 10 cm, four shots were fired from a distance of 2 m, and five shots were fired from a distance of 4 m. Each projectile penetrated the model; all but one projectile deformed regularly. Each acryl sphere shattered into comminuted pieces but was held together by the silicon cover. The gelatine filling was then cut into slices 1 cm thick, and each slice was optically scanned. An evaluation was performed following both Fackler's Wound Profile method and the polygon procedure method. The pattern of gelatine disruption did not differ in shots from intermediate ranges, but the amount of gelatine destruction was always more extended in the case of muzzle contact shots. Depending on the section of the bullet path, crack lengths were 31% to 133% longer in contact shots. The first centimetre and the second half of the bullet path showed the greatest increase. The experimental findings prove the wounding capacity of muzzle gases.

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

A Bulk Comptonization Model for the Prompt GRB Emission and its Relation to the Fermi GRB Spectra

NASA Technical Reports Server (NTRS)

Kazanas, Demosthenes

2010-01-01

We present a model in which the GRB prompt emission at E E(sub peak) is due to bulk Comptonization by the relativistic blast wave motion of either its own synchrotron photons of ambient photons of the stellar configuration that gave birth to the GRB. The bulk Comptonization process then induces the production of relativistic electrons of Lorentz factor equal to that of the blast wave through interactions with its ambient protons. The inverse compton emission of these electrons produces a power law component that extends to multi GeV energies in good agreement with the LAT GRB observations.

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.

Wireless device for activation of an underground shock wave absorber

NASA Astrophysics Data System (ADS)

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

2011-10-01

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

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).

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.

Use of a hard palate mucoperiosteal flap for rostral muzzle reconstruction in a dog after a traumatic premaxillary degloving injury.

PubMed

Kurach, Lindsey; Plesman, Rhea; Grier-Lowe, Candace; Linn, Kathleen; Anthony, James

2013-02-01

To describe a technique for reconstruction of the rostral aspect of the muzzle of a dog after traumatic amputation. Clinical report. Adult female dog. A 6-year-old, intact, female, mixed-breed dog was admitted for facial reconstructive surgery after traumatic amputation of the rostral aspect of the muzzle. The nasal planum and the rostral portion of the upper lips were missing. A hard palate mucoperiosteal flap and lateral labial advancement flaps were used to reconstruct the nasal philtrum and borders of the nares. This reconstructive technique resulted in adequate nostril function and an acceptable cosmetic outcome. One naris developed partial obstruction with granulation tissue that may have occurred because of a lack of circumferential nasal mucosa to appose the skin on that side. The mucoperiosteum of the hard palate can be used to reconstruct the rostral aspect of the muzzle after traumatic amputation, resulting in an acceptable cosmetic outcome. © Copyright 2012 by The American College of Veterinary Surgeons.

Composite Resection of Tumors of the Rostral Maxilla and Dorsolateral Muzzle Utilizing an Upper Lip-Sparing, Combined Approach in Dogs.

PubMed

Thomson, Amy E; Soukup, Jason W

2018-01-01

Tumors of the rostral maxilla that involve both the oral mucosa and the dermis or subdermis of the dorsolateral muzzle provide unique challenges for the oromaxillofacial surgeon. Traditionally described approaches to such lesions may involve an intraoral incision that extends and involves the upper lip to envelope the involved dermis of the dorsolateral muzzle. However, such an approach unnecessarily resects upper lip tissue resulting in a large defect that likely requires advanced skin flaps or grafts for reconstruction. Such flaps are technically challenging and introduce potential for significance postoperative complications. In this article, we provide a detailed description a combined intra- and extraoral approach that allows for composite resection of tumors of the rostral maxilla that also involve the dorsolateral muzzle. The described technique allows for excellent intraoperative visualization and provides a superior cosmetic outcome that minimizes postoperative complications. In addition, we describe our experience utilizing the technique in three clinical cases.

Composite Resection of Tumors of the Rostral Maxilla and Dorsolateral Muzzle Utilizing an Upper Lip-Sparing, Combined Approach in Dogs

PubMed Central

Thomson, Amy E.; Soukup, Jason W.

2018-01-01

Tumors of the rostral maxilla that involve both the oral mucosa and the dermis or subdermis of the dorsolateral muzzle provide unique challenges for the oromaxillofacial surgeon. Traditionally described approaches to such lesions may involve an intraoral incision that extends and involves the upper lip to envelope the involved dermis of the dorsolateral muzzle. However, such an approach unnecessarily resects upper lip tissue resulting in a large defect that likely requires advanced skin flaps or grafts for reconstruction. Such flaps are technically challenging and introduce potential for significance postoperative complications. In this article, we provide a detailed description a combined intra- and extraoral approach that allows for composite resection of tumors of the rostral maxilla that also involve the dorsolateral muzzle. The described technique allows for excellent intraoperative visualization and provides a superior cosmetic outcome that minimizes postoperative complications. In addition, we describe our experience utilizing the technique in three clinical cases. PMID:29616231

[Severe inflammation of the muzzle caused by a nose ring in a breeding bull].

PubMed

Braun, U; Gautschi, A; Reichle, S; Gerspach, C

2010-09-01

This report describes the findings in a bull with severe inflammation of the muzzle and nose attributable to a nose ring. The most striking finding was that the bull continually licked the right side of the upper lip. The muzzle and right upper lip were swollen, hard, reddened and partially depigmented. Mucopurulent nasal discharge and salivation were also noted, and palpation of the right upper lip was extremely painful. Based on the findings, purulent infection of the right side of the muzzle, right naris and external nasal passage was diagnosed. After removing the nose ring the affected areas were washed daily for four days with a camomile-containing solution after which a chlorhexidine and dexpanthenol salve was applied. The bull also received ceftiofur and ketoprofen. The general condition and appetite of the bull normalised within a few days, and the inflammatory lesions resolved with the exception of the areas of depigmentation. After ten days of treatment, the bull was considered healthy and discharged from the clinic.

Gunshot residue particle velocity and deceleration.

PubMed

De Forest, Peter R; Martir, Kirby; Pizzola, Peter A

2004-11-01

The velocity of over 800 gunshot residue particles from eight different sources was determined using high speed stroboscopic photography (spark gap light source). These particles were found to have an average velocity of 500 to 600 ft per second. Many particles acquired considerably higher velocities. Thus, the particles have sufficient energy to embed themselves within certain nearby targets like skin or fabric. The relatively high velocity that the particles acquire explain the formation of stippling on skin in close proximity to a muzzle discharge. These findings also indicate little influence of air currents on particle behavior near the muzzle. The deceleration of less than 100 particles during a 100-microsecond interval was also calculated. The particles experienced rapid rates of deceleration which would explain why few particles are found in test firings beyond 3 ft from the muzzle of a discharged firearm. Because of their relatively high velocity, normal wind velocity would not be expected to significantly influence their motion near the muzzle.

Use of a Tantalum Liner to Reduce Bore Erosion and Increase Muzzle Velocity in Two-Stage Light Gas Guns

NASA Technical Reports Server (NTRS)

Bogdanoff, David W.

2015-01-01

Muzzle velocities and gun erosion predicted by earlier numerical simulations of two stage light gas guns with steel gun tubes were in good agreement with experimental values. In a subsequent study, simulations of high performance shots were repeated with rhenium (Re) gun tubes. Large increases in muzzle velocity (2 - 4 km/sec) were predicted for Re tubes. In addition, the hydrogen-produced gun tube erosion was, in general, predicted to be zero with Re tubes. Tantalum (Ta) has some mechanical properties superior to those of Re. Tantalum has a lower modulus of elasticity than Re for better force transmission from the refractory metal liner to an underlying thick wall steel tube. Tantalum also has greater ductility than Re for better survivability during severe stress/strain cycles. Also, tantalum has been used as a coating or liner in military powder guns with encouraging results. Tantalum has, however, somewhat inferior thermal properties to those of rhenium, with a lower melting point and lower density and thermal conductivity. The present study was undertaken to see to what degree the muzzle velocity gains of rhenium gun tubes (over steel tubes) could be achieved with tantalum gun tubes. Nine high performance shots were modeled with a new version of our CFD gun code for steel, rhenium and tantalum gun tubes. For all except the highest velocity shot, the results with Ta tubes were nearly identical with those for Re tubes. Even for the highest velocity shot, the muzzle velocity gain over a steel tube using Ta was 82% of the gain obtained using Re. Thus, the somewhat inferior thermal properties of Ta (when compared to those of Re) translate into only very slightly poorer overall muzzle velocity performance. When this fact is combined with the superior mechanical properties of Ta and the encouraging performance of Ta liners/coatings in military powder guns, tantalum is to be preferred over Re as a liner/coating material for two stage light gas guns to increase muzzle velocity and reduce bore erosion.

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.

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.

Some diagnostic interpretations from railgun plasma profile experiments

NASA Astrophysics Data System (ADS)

Stainsby, D. F.; Bedford, A. J.

1984-03-01

Some aspects of a railgun experimental series to investigate plasma profiles are reviewed. Certain diagnostic records clearly show plasma leakage past the projectile, and correspondence between various in-bore events and muzzle voltage. A muzzle flash detector is shown to have a useful role as a plasma diagnostic tool.

Investigation of shock-wave phenomena in composite materials

NASA Astrophysics Data System (ADS)

Afanas'eva, S. A.; Belov, N. N.; Biryukov, Yu. A.; Burkin, V. V.; Zakharov, V. M.; Ishchenko, A. N.; Skosyrskii, A. V.; Tabachenko, A. N.; Khorev, I. E.; Yugov, N. T.

2011-01-01

We propose a complex experimental-theoretical approach to the investigation and development of high-energy and composite materials for the conditions of high-velocity throwing and interaction with the application of nanotechnologies. We have obtained data on the character of the high-velocity interaction of strikers made from tungsten composites by different technologies with a steel obstacle. A nanostructured material based on copper with higher strength characteristics has been developed. The conditions for increasing the muzzle velocity of a barrel throwing installation due to the application of nanocomposite fuels have been investigated and realized. A computing-experimental method for investigating the processes of high-velocity collision of bodies has been elaborated.

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

Fatal contact shot to the chest caused by the gas jet from a muzzle-loading pistol discharging only black powder and no bullet: case study and experimental simulation of the wounding effect.

PubMed

Große Perdekamp, Markus; Glardon, Matthieu; Kneubuehl, Beat P; Bielefeld, Lena; Nadjem, Hadi; Pollak, Stefan; Pircher, Rebecca

2015-01-01

In modern medico-legal literature, only a small number of publications deal with fatal injuries from black powder guns. Most of them focus on the morphological features such as intense soot soiling, blast tattooing and burn effects in close-range shots or describe the wound ballistics of spherical lead bullets. Another kind of "unusual" and potentially lethal weapons are handguns destined for firing only blank cartridges such as starter and alarm pistols. The dangerousness of these guns is restricted to very close and contact range shots and results from the gas jet produced by the deflagration of the propellant. The present paper reports on a suicide committed with a muzzle-loading percussion pistol cal. 45. An unusually large stellate entrance wound was located in the precordial region, accompanied by an imprint mark from the ramrod and a faint greenish discoloration (apparently due to the formation of sulfhemoglobin). Autopsy revealed an oversized powder cavity, multiple fractures of the anterior thoracic wall as well as ruptures of the heart, the aorta, the left hepatic lobe and the diaphragm. In total, the zone of mechanical destruction had a diameter of approx. 15 cm. As there was no exit wound and no bullet lodged in the body, the injury was caused exclusively by the inrushing combustion gases of the propellant (black powder) comparable with the gas jet of a blank cartridge gun. In contact shots to ballistic gelatine using the suicide's pistol loaded with black powder but no projectile, the formation of a nearly spherical cavity could be demonstrated by means of a high-speed camera. The extent of the temporary cavity after firing with 5 g of black powder roughly corresponded to the zone of destruction found in the suicide's body.

Fatigue methodology III; Proceedings of the AHS National Technical Specialists' Meeting on Advanced Rotorcraft Structures, Scottsdale, AZ, Oct. 3-5, 1989

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

Not Available

1989-01-01

Papers on rotorcraft and fatigue methodology are presented, covering topics such as reliability design for rotorcraft, a comparison between theory and fatigue test data on stress concentration factors, the retirement lives of rolling element bearings, hydrogen embrittlement risk analysis for high hardness steel parts, and rotating system load monitoring with minimum fixed system instrumentation. Additional topics include usage data collection to improve structural integrity of operational helicopters, usage monitory of military helicopters, improvements to the fatigue substantiation of the H-60 composite tail rotor blade, helicopter surviellance programs, and potential application of automotive fatigue technology in rotorcraft design. Also, consideration ismore » given to fatigue evaluation of C/MH-53 E main rotor damper threaded joints, SH-2F airframe fatigue test program, a ply termination concept for improving fracture and fatigue strength of composite laminates, the analysis and testing of composite panels subject to muzzle blast effects, the certification plan for an all-composite main rotor flexbeam, and the effects of stacking sequence on the flexural strength of composite beams.« less

Lead exposures and biological responses in military weapons systems: Aerosol characteristics and acute lead effects among US Army artillerymen: Final report

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

Bhattacharyya, M.H.; Stebbings, J.H.; Peterson, D.P.

1993-03-01

This study was to determine the concentration and chemical nature of lead (Pb) aerosols produced during the firing of artillery and to determine the exposures and biological responses of crew members exposed to lead aerosols during such firing. The concentrations of lead-containing aerosols at crew positions depended on wind conditions, with higher concentrations when firing into a head wind. Aerosol concentrations were highest in the muzzle blast zone. Concentrations of lead in the blood of crew members rose during the first 12 days of exposure to elevated airborne lead concentrations and then leveled off. There was no rapid decrease inmore » blood lead concentrations after completion of firing. Small decreases in hematocrit and small increases in free erythrocyte porphyrin were correlated with increasing exposure to airborne lead. These changes were reversed by seven weeks after firing. Changes in nerve conduction velocity had borderline statistical significance to airborne lead exposure. In measuring nerve conduction velocity, differences in skin temperature must be taken into account.« less

Ozone formation behind pulsed-laser-generated blast waves in oxygen

NASA Astrophysics Data System (ADS)

Stricker, J.; Parker, J. G.

1984-12-01

The formation of ozone behind blast waves in oxygen generated by a pulsed laser has been investigated both experimentally and theoretically, over cell pressure range of 0.68-27 atm. Ozone buildup formed by successive pulses was monitored by recording UV absorption at 2540 Å. It was found that, as the number of pulses increase, the rate of ozone formation decreased until finally an equilibrium concentration was reached. This equilibrium magnitude was determined by the condition that the number of ozone molecules produced by the wave equals the number decomposed by the same wave. The decomposition and formation of O3 during a single pulse were monitored by time-resolved UV absorption measurements. In order to provide a fundamental basis for interpretation of the mechanism of ozone formation, a mathematical model was developed. Although qualitatively measurements and theory agree, the data, mainly on the number of O3 molecules produced per pulse, is in significant disagreement. Several possible explanations of this discrepancy are given.

The ratio between corner frequencies of source spectra of P- and S-waves—a new discriminant between earthquakes and quarry blasts

NASA Astrophysics Data System (ADS)

Ataeva, G.; Gitterman, Y.; Shapira, A.

2017-01-01

This study analyzes and compares the P- and S-wave displacement spectra from local earthquakes and explosions of similar magnitudes. We propose a new approach to discrimination between low-magnitude shallow earthquakes and explosions by using ratios of P- to S-wave corner frequencies as a criterion. We have explored 2430 digital records of the Israeli Seismic Network (ISN) from 456 local events (226 earthquakes, 230 quarry blasts, and a few underwater explosions) of magnitudes Md = 1.4-3.4, which occurred at distances up to 250 km during 2001-2013 years. P-wave and S-wave displacement spectra were computed for all events following Brune's source model of earthquakes (1970, 1971) and applying the distance correction coefficients (Shapira and Hofstetter, Teconophysics 217:217-226, 1993; Ataeva G, Shapira A, Hofstetter A, J Seismol 19:389-401, 2015), The corner frequencies and moment magnitudes were determined using multiple stations for each event, and then the comparative analysis was performed.

Concussive brain injury from explosive blast

PubMed Central

de Lanerolle, Nihal C; Hamid, Hamada; Kulas, Joseph; Pan, Jullie W; Czlapinski, Rebecca; Rinaldi, Anthony; Ling, Geoffrey; Bandak, Faris A; Hetherington, Hoby P

2014-01-01

Objective Explosive blast mild traumatic brain injury (mTBI) is associated with a variety of symptoms including memory impairment and posttraumatic stress disorder (PTSD). Explosive shock waves can cause hippocampal injury in a large animal model. We recently reported a method for detecting brain injury in soldiers with explosive blast mTBI using magnetic resonance spectroscopic imaging (MRSI). This method is applied in the study of veterans exposed to blast. Methods The hippocampus of 25 veterans with explosive blast mTBI, 20 controls, and 12 subjects with PTSD but without exposure to explosive blast were studied using MRSI at 7 Tesla. Psychiatric and cognitive assessments were administered to characterize the neuropsychiatric deficits and compare with findings from MRSI. Results Significant reductions in the ratio of N-acetyl aspartate to choline (NAA/Ch) and N-acetyl aspartate to creatine (NAA/Cr) (P < 0.05) were found in the anterior portions of the hippocampus with explosive blast mTBI in comparison to control subjects and were more pronounced in the right hippocampus, which was 15% smaller in volume (P < 0.05). Decreased NAA/Ch and NAA/Cr were not influenced by comorbidities – PTSD, depression, or anxiety. Subjects with PTSD without blast had lesser injury, which tended to be in the posterior hippocampus. Explosive blast mTBI subjects had a reduction in visual memory compared to PTSD without blast. Interpretation The region of the hippocampus injured differentiates explosive blast mTBI from PTSD. MRSI is quite sensitive in detecting and localizing regions of neuronal injury from explosive blast associated with memory impairment. PMID:25493283

83. DETAIL OF THE MUZZLE END OF THE LAUNCHER BRIDGE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

83. DETAIL OF THE MUZZLE END OF THE LAUNCHER BRIDGE ON TEMPORARY SUPPORTS LOOKING NORTHEAST SHOWING TWO LAUNCHING TUBES, Date unknown, circa 1950'S. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

82. DETAIL OF THE MUZZLE END OF THE LAUNCHER BRIDGE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

82. DETAIL OF THE MUZZLE END OF THE LAUNCHER BRIDGE LOOKING NORTH SHOWING THE CONNECTING BRIDGE AND TWO LAUNCHING TUBES, Date unknown, circa 1952. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

Ignition potential of muzzle-loading firearms: An exploratory investigation

Treesearch

David V. Haston; Mark A. Finney; Andy Horcher; Philip A. Yates; Kahlil Detrich

2009-01-01

The National Technology and Development Program of the Forest Service, U.S. Department of Agriculture, was asked to conduct an exploratory study on the ignition potential of muzzle-loading firearms. The five independent variables investigated include projectile type, powder type, powder load, patch thickness, and patch lubricant treatment. Indoor testing was performed...

Temporal characterization of small arms muzzle flash in the broadband visible

NASA Astrophysics Data System (ADS)

Burke, Tom; Bratlie, Duane

2010-04-01

The authors have developed a simple system for characterizing the muzzle flash duration of common military small-arms ammunition as a feeder for system design configurations. This paper is a synopsis of the efforts and results of the effort to characterize the broadband optical signature of modern small arms.

A patterned abrasion caused by the impact of a cartridge case may simulate an atypical muzzle imprint mark.

PubMed

Kramer, Lena; Nadjem, Hadi; Glardon, Matthieu; Kneubuehl, Beat P; Pollak, Stefan; Große Perdekamp, Markus; Pircher, Rebecca

2016-05-01

In contact shots, the muzzle imprint is an informative finding associated with the entrance wound. It typically mirrors the constructional components being in line with the muzzle or just behind. Under special conditions, other patterned skin marks located near a gunshot entrance wound may give the impression to be part of the muzzle imprint. A potential mechanism causing a patterned pressure abrasion in close proximity to the bullet entrance site is demonstrated on the basis of a suicidal shot to the temple. The skin lesion in question appeared as a ring-shaped excoriation with a diameter corresponding to that of the cartridge case. Two hypotheses concerning the causative mechanism were investigated by test shots: - After being ejected, the cartridge case ricocheted inside a confined space (car cabin in the particular case) and secondarily hit the skin near the gunshot entrance wound. - The ejection of the cartridge case failed so that the case became stuck in the ejection port and its mouth contacted the skin when the body collapsed after being hit.

Mechanical Damage of Tympanic Membrane in Relation to Impulse Pressure Waveform – A Study in Chinchillas

PubMed Central

Gan, Rong Z.; Nakmali, Don; Ji, Xiao D.; Leckness, Kegan; Yokell, Zachary

2016-01-01

Mechanical damage to middle ear components in blast exposure directly causes hearing loss, and the rupture of the tympanic membrane (TM) is the most frequent injury of the ear. However, it is unclear how the severity of injury graded by different patterns of TM rupture is related to the overpressure waveforms induced by blast waves. In the present study, the relationship between the TM rupture threshold and the impulse or overpressure waveform has been investigated in chinchillas. Two groups of animals were exposed to blast overpressure simulated in our lab under two conditions: open field and shielded with a stainless steel cup covering the animal head. Auditory brainstem response (ABR) and wideband tympanometry were measured before and after exposure to check the hearing threshold and middle ear function. Results show that waveforms recorded in the shielded case were different from those in the open field and the TM rupture threshold in the shielded case was lower than that in the open field (3.4±0.7 vs. 9.1±1.7 psi or 181±1.6 vs. 190±1.9 dB SPL). The impulse pressure energy spectra analysis of waveforms demonstrates that the shielded waveforms include greater energy at high frequencies than that of the open field waves. Finally, a 3D finite element (FE) model of the chinchilla ear was used to compute the distributions of stress in the TM and the TM displacement with impulse pressure waves. The FE model-derived change of stress in response to pressure loading in the shielded case was substantially faster than that in the open case. This finding provides the biomechanical mechanisms for blast induced TM damage in relation to overpressure waveforms. The TM rupture threshold difference between the open and shielded cases suggests that an acoustic role of helmets may exist, intensifying ear injury during blast exposure. PMID:26807796

Forensic Seismology: constraints on terrorist bombings

NASA Astrophysics Data System (ADS)

Wallace, T. C.; Koper, K. D.

2002-05-01

Seismology has long been used as a tool to monitor and investigate explosions, both accidental and intentional. Seismic records can be used to provide a precise chronology of events, estimate the energy release in explosions and produce constraints to test various scenarios for the explosions. Truck bombs are a popular tool of terrorists, and at least two such attacks have been recorded seismically. On August 7, 1998 a truck bomb was detonated near the US embassy in Nairobi, Kenya. The bomb seriously damaging a dozen buildings, injuring more than 4000 people and causing 220 fatalities. The explosion was recorded on a short-period seismometer located north of the blast site; the blast seismogram contained body waves, Rayleigh waves and vibrations associated with the air blast. Modeling of the body and surfaces wave allowed an estimate of the origin time of the bombing, which it turn could be used as a constraint the timing of the air blasts. The speed of the air waves from an explosion depend on the air temperature and the size, or yield, of the explosion. In an effort to fully utilize the seismic recordings from such attacks, we analyzed the seismic records from a series of controlled truck bomb explosions carried out at White Sand Missile Range in New Mexico. We developed a new set of scaling laws that relate seismic and acoustic observations directly to the explosive mass (yield). These relationships give a yield of approximately 3000 kg of TNT equivalent for the Nairobi bomb. The terrorist bombing of the Murrah Federal Building in Oklahoma City in 1995 was also recorded on seismometers. One of these records showed 2 discrete surface wavetrains separated by approximately 10 seconds. Some groups seized on the seismic recordings as evidence that there were 2 explosions, and that the US government was actually behind the bombing. However, the USGS monitored the demolition of the remainder of the Murrah Building and showed that the collapse also produced 2 surface waves. The interpretation is that one group was the fundamental mode Rayleigh wave while the other was either a higher-mode surface wave or a scattered S-wave (Lg like) packet (Holzer et al, 1996). This example illustrates the utility of forensic seismology for testing various hypothesis for the explosions. As the number of permanent and temporarily installed seismometers increase in the next decade, the number of "exotic" sources recorded and investigated is grow dramatically. These studies can be very useful for investigating terrorist attacks, and developing scenarios for the crimes.

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

U.S. Army RDECOM-ARDEC's results of the TG-53 experiment and field test

NASA Astrophysics Data System (ADS)

Desai, Sachi V.; Morcos, Amir

2009-05-01

Herein is described the U.S. Army RDECOM-ARDEC's purpose and series of activities conducted at the 2008 NATO SET-093 TG-53 experiment and field test. The overall purpose of the field test as stated by SET-093 panel was to provide a baseline test capable of providing relevant scenarios and data regarding a variety of impulsive generated acoustic events. As organized, the field experiment also allowed the room o study sensor interoperability across multiple platforms and multi-national users via the spider communication framework/reporting structure. This multinational network maintained by the host ETBS with a standardized messaging format with specific goals for each participating organization. ARDEC's role and purpose for the test was to provide situational awareness via the Spider and associated messaging format to the ETBS command center while continuing to gather unique acoustic data from various vantage points. ARDEC had several deliverables for the TG-53 field experiment derived from the mission and spirit of the field test. The most relevant deliverable was to demonstrate sensor interoperability via the Spider network and provide situational awareness by describing the said mortar/artillery events. The second purpose revolved around a relevant environment algorithm validation of the muzzle blast discrimination for future UGS transition in particular the UTAMS II. The algorithm validation information remained internal to the specific data acquisition system and not broadcasted out on the Spider network. The TG-53 field experiments provided the added opportunity to further test and refine the algorithm based on the discrete wavelet transform (DWT) and multiresolution analysis. These techniques are used to classify and reliably discriminates between launch and impact artillery and/or mortar events via acoustic signals produced during detonation. Distinct characteristics are found within the acoustic signatures since impact events emphasize concussive and shrapnel effects, while launch events are similar to explosions, designed to expel and propel an artillery round from a gun. The ensuing signatures are readily characterized by variations in the corresponding peak pressure and rise time of the waveform, differences in the ratio of positive pressure amplitude to the negative amplitude, variations in the prominent frequencies associated with the blast events and variations in the overall duration of the resulting waveform. Unique attributes can also be identified that depend upon the properties of the gun tube, projectile speed at the muzzle, and the explosive/concussive properties associated with the events. The event allows the examination of particular extreme battlefield acoustic challenges not normally documented or readily studied. The final portion will focus on the unique acoustic signatures data collected and how it allowed very relevant situations to be tested in a variety of scenarios.

Engine Cycle Analysis of Air Breathing Microwave Rocket with Reed Valves

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

Fukunari, Masafumi; Komatsu, Reiji; Yamaguchi, Toshikazu

The Microwave Rocket is a candidate for a low cost launcher system. Pulsed plasma generated by a high power millimeter wave beam drives a blast wave, and a vehicle acquires impulsive thrust by exhausting the blast wave. The thrust generation process of the Microwave Rocket is similar to a pulse detonation engine. In order to enhance the performance of its air refreshment, the air-breathing mechanism using reed valves is under development. Ambient air is taken to the thruster through reed valves. Reed valves are closed while the inside pressure is high enough. After the time when the shock wave exhaustsmore » at the open end, an expansion wave is driven and propagates to the thrust-wall. The reed valve is opened by the negative gauge pressure induced by the expansion wave and its reflection wave. In these processes, the pressure oscillation is important parameter. In this paper, the pressure oscillation in the thruster was calculated by CFD combined with the flux through from reed valves, which is estimated analytically. As a result, the air-breathing performance is evaluated using Partial Filling Rate (PFR), the ratio of thruster length to diameter L/D, and ratio of opening area of reed valves to superficial area {alpha}. An engine cycle and predicted thrust was explained.« less

Shock Initiated Reactions of Reactive Multiphase Blast Explosives

NASA Astrophysics Data System (ADS)

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

2015-06-01

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

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.

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.

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.

Comprehensive 3D Model of Shock Wave-Brain Interactions in Blast-Induced Traumatic Brain Injuries

DTIC Science & Technology

2009-10-01

waves can cause brain damage by other mechanisms including excess pressure (leading to contusions), excess strain (leading to subdural ... hematomas and/or diffuse axonal injuries), and, in particular, cavitation effects (leading to subcellular damage). This project aims at the development of a

Aluminum Micro-Balloons as Improved Fuel for Warhead Explosives

DTIC Science & Technology

2018-01-29

12-1-0006 Dr. Jerry W. Forbes Prepared by: Energetics Technology Center 10400 O Donnell Place Suite 202 St. Charles, MD 20603...the goal of enhancing blast waves. This 6.2 grant work provides the baseline technology to understand shock wave experiments done and to be done

Examination of a Wear-Reducing Muzzle Device

DTIC Science & Technology

2013-08-01

resistant material attached to the muzzle end of the gun tube. The bore diameter of the device is slightly less than the bore diameter of the gun. The...3  Figure 3. Weapon and universal bearing slide used for firings ...small caliber round of ammunition. ..........21  v List of Tables Table 1. Firing test matrix for phase 1

A Quick Look at Supernova 1987A

NASA Image and Video Library

2017-02-24

On February 24, 1987, astronomers in the southern hemisphere saw a supernova in the Large Magellanic Cloud. This new object was dubbed “Supernova 1987A” and was the brightest stellar explosion seen in over four centuries. Chandra has observed Supernova 1987A many times and the X-ray data reveal important information about this object. X-rays from Chandra have shown the expanding blast wave from the original explosion slamming into a ring of material expelled by the star before it exploded. The latest Chandra data reveal the blast wave has moved beyond the ring into a region that astronomers do not know much about. These observations can help astronomers learn how supernovas impact their environments and affect future generations of stars and planets.

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.

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

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.

Gun muzzle flash detection using a single photon avalanche diode array in 0.18µm CMOS technology

NASA Astrophysics Data System (ADS)

Savuskan, Vitali; Jakobson, Claudio; Merhav, Tomer; Shoham, Avi; Brouk, Igor; Nemirovsky, Yael

2015-05-01

In this study, a CMOS Single Photon Avalanche Diode (SPAD) 2D array is used to record and sample muzzle flash events in the visible spectrum, from representative weapons. SPADs detect the emission peaks of alkali salts, potassium or sodium, with spectral emission lines around 769nm and 589nm, respectively. The alkali salts are included in the gunpowder to suppress secondary flashes ignited during the muzzle flash event. The SPADs possess two crucial properties for muzzle flash imaging: (i) very high photon detection sensitivity, (ii) a unique ability to convert the optical signal to a digital signal at the source pixel, thus practically eliminating readout noise. The sole noise sources are the ones prior to the readout circuitry (optical signal distribution, avalanche initiation distribution and nonphotonic generation). This enables high sampling frequencies in the kilohertz range without significant SNR degradation, in contrast to regular CMOS image sensors. This research will demonstrate the SPAD's ability to accurately sample and reconstruct the temporal behavior of the muzzle flash in the visible wavelength, in the presence of sunlight. The reconstructed signal is clearly distinguishable from background clutter, through exploitation of flash temporal characteristics and signal processing, which will be reported. The frame rate of ~16 KHz was chosen as an optimum between SNR degradation and temporal profile recognition accuracy. In contrast to a single SPAD, the 2D array allows for multiple events to be processed simultaneously. Moreover, a significant field of view is covered, enabling comprehensive surveillance and imaging.

Thulium fiber laser lithotripsy using a muzzle brake fiber tip

NASA Astrophysics Data System (ADS)

Hutchens, Thomas C.; Gonzalez, David A.; Irby, Pierce B.; Fried, Nathaniel M.

2017-02-01

The Thulium fiber laser (TFL) is being explored as an alternative to Holmium:YAG laser for lithotripsy. TFL beam profile allows coupling of higher power into smaller fibers than multimode Holmium laser beam, without proximal fiber tip degradation. A smaller fiber provides more space in ureteroscope working channel for increased saline irrigation and allows maximum ureteroscope flexion. However, distal fiber tip burnback increases as fiber diameter decreases. Previous studies utilizing hollow steel sheaths around recessed distal fiber tips reduced fiber burnback, but increased retropulsion. In this study, a "fiber muzzle brake" was tested for reducing fiber burnback and stone retropulsion. TFL lithotripsy studies were performed at 1908 nm, 35 mJ, 500 μs, and 300 Hz using a 100-μm-core fiber. The optimal stainless steel muzzle brake tip tested consisted of a 1-cm-long, 560-μm-OD, 360-μm-ID tube with 275-μm thru hole located 250-μm from the distal end. The fiber tip was recessed a distance of 500 μm. Stone phantom retropulsion, fiber tip burnback, and calcium oxalate stone ablation studies were performed, ex vivo. Small stones with a mass of 40 +/- 4 mg and 4-mm-diameter were ablated over a 1.5-mm sieve in 25 +/- 4 s (n=10), without distal fiber tip burnback. Reduction in stone phantom retropulsion distance by 50% and 85% was observed when using muzzle brake tips versus 100-μm-core bare fibers and hollow steel tip fibers. The muzzle brake fiber tip provided efficient stone ablation, reduced stone retropulsion, and minimal fiber degradation during TFL lithotripsy.

Dynamic load mitigation using dissipative elastic metamaterials with multiple Maxwell-type oscillators

NASA Astrophysics Data System (ADS)

Alamri, Sagr; Li, Bing; Tan, K. T.

2018-03-01

Dissipative elastic metamaterials have attracted increased attention in recent times. This paper presents the development of a dissipative elastic metamaterial with multiple Maxwell-type resonators for stress wave attenuation. The mechanism of the dissipation effect on the vibration characteristics is systematically investigated by mass-spring-damper models with single and dual resonators. Based on the parameter optimization, it is revealed that a broadband wave attenuation region (stopping band) can be obtained by properly utilizing interactions from resonant motions and viscoelastic effects of the Maxwell-type oscillators. The relevant numerical verifications are conducted for various cases, and excellent agreement between the numerical and theoretical frequency response functions is shown. The design of this dissipative metamaterial system is further applied for dynamic load mitigation and blast wave attenuation. Moreover, the transient response in the continuum model is designed and analyzed for more robust design. By virtue of the bandgap merging effect induced by the Maxwell-type damper, the transient blast wave can be almost completely suppressed in the low frequency range. A significantly improved performance of the proposed dissipative metamaterials for stress wave mitigation is verified in both time and frequency domains.

Assessment of Waco, Texas FLIR videotape

NASA Astrophysics Data System (ADS)

Frankel, Donald S.

2001-09-01

The FLIR video recorded by the FBI on 19 April 1993, records the final assault on the Branch Davidian compound in Waco, Texas, and the fire in which some 80 members of the sect died. Attention has focused on a number of flashes recorded on the videotape. The author has examined the 1993 videotape and the recorded videotapes of the re-enactment conducted at Fort Hood, Texas on 19 March 2000. The following conclusions have been reached: 1) The flashes seen on the tape cannot be weapons muzzle flash. Their duration is far too long and their spatial extent is far too great. They are almost certainly the result of solar energy or heat energy form nearby vehicles reflected toward the FLIR by debris or puddles. 2) The FLIR video technology has a very low probability of detecting small arms muzzle flash. 3) As a consequence of 2) above, the absence of muzzle flash detection on the FLIR tape does not prove that no weapons were actually fired during the final assault. Indeed, there is ample evidence (not presented here) that the Davidians fired at the federal agents, but none of their muzzle flashes are detectable on the videotape.

Comparison of muzzle suppression and ear-level hearing protection in firearm use.

PubMed

Branch, Matthew Parker

2011-06-01

To compare noise reduction of commercially available ear-level hearing protection (muffs/inserts) to that of firearm muzzle suppressors. Experimental sound measurements under consistent environmental conditions. None. Muzzle suppressors for 2 pistol and 2 rifle calibers were tested using the Bruel & Kjaer 2209 sound meter and Bruel & Kjaer 4136 microphone calibrated with the Bruel & Kjaer Pistonphone using Military-Standard 1474D placement protocol. Five shots were recorded unsuppressed and 10 shots suppressed under consistent environmental conditions. Sound reduction was then compared with the real-world noise reduction rate of the best available ear-level protectors. All suppressors offered significantly greater noise reduction than ear-level protection, usually greater than 50% better. Noise reduction of all ear-level protectors is unable to reduce the impulse pressure below 140 dB for certain common firearms, an international standard for prevention of sensorineural hearing loss. Modern muzzle-level suppression is vastly superior to ear-level protection and the only available form of suppression capable of making certain sporting arms safe for hearing. The inadequacy of standard hearing protectors with certain common firearms is not recognized by most hearing professionals or their patients and should affect the way hearing professionals counsel patients and the public.

Integrated development of light armored vehicles based on wargaming simulators

NASA Astrophysics Data System (ADS)

Palmarini, Marc; Rapanotti, John

2004-08-01

Vehicles are evolving into vehicle networks through improved sensors, computers and communications. Unless carefully planned, these complex systems can result in excessive crew workload and difficulty in optimizing the use of the vehicle. To overcome these problems, a war-gaming simulator is being developed as a common platform to integrate contributions from three different groups. The simulator, OneSAF, is used to integrate simplified models of technology and natural phenomena from scientists and engineers with tactics and doctrine from the military and analyzed in detail by operations analysts. This approach ensures the modelling of processes known to be important regardless of the level of information available about the system. Vehicle survivability can be improved as well with better sensors, computers and countermeasures to detect and avoid or destroy threats. To improve threat detection and reliability, Defensive Aids Suite (DAS) designs are based on three complementary sensor technologies including: acoustics, visible and infrared optics and radar. Both active armour and softkill countermeasures are considered. In a typical scenario, a search radar, providing continuous hemispherical coverage, detects and classifies the threat and cues a tracking radar. Data from the tracking radar is processed and an explosive grenade is launched to destroy or deflect the threat. The angle of attack and velocity from the search radar can be used by the soft-kill system to carry out an infrared search and track or an illuminated range-gated scan for the threat platform. Upon detection, obscuration, countermanoeuvres and counterfire can be used against the threat. The sensor suite is completed by acoustic detection of muzzle blast and shock waves. Automation and networking at the platoon level contribute to improved vehicle survivability. Sensor data fusion is essential in avoiding catastrophic failure of the DAS. The modular DAS components can be used with Light Armoured Vehicle (LAV) variants including: armoured personnel carriers and direct-fire support vehicles. OneSAF will be used to assess the performance of these DAS-equipped vehicles on a virtual battlefield.

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

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

PubMed

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

2018-07-16

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

Current topics in shock waves; Proceedings of the International Symposium on Shock Waves and Shock Tubes, 17th, Lehigh University, Bethlehem, PA, July 17-21, 1989

NASA Astrophysics Data System (ADS)

Kim, Yong W.

Various papers on shock waves are presented. The general topics addressed include: shock formation, focusing, and implosion; shock reflection and diffraction; turbulence; laser-produced plasmas and waves; ionization and shock-plasma interaction; chemical kinetics, pyrolysis, and soot formation; experimental facilities, techniques, and applications; ignition of detonation and combustion; particle entrainment and shock propagation through particle suspension; boundary layers and blast simulation; computational methods and numerical simulation.

Radiative precursors driven by converging blast waves in noble gases

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

Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.

2014-03-15

A detailed study of the radiative precursor that develops ahead of converging blast waves in gas-filled cylindrical liner z-pinch experiments is presented. The experiment is capable of magnetically driving 20 km s{sup −1} blast waves through gases of densities of the order 10{sup −5} g cm{sup −3} (see Burdiak et al. [High Energy Density Phys. 9(1), 52–62 (2013)] for a thorough description). Data were collected for Ne, Ar, and Xe gas-fills. The geometry of the setup allows a determination of the plasma parameters both in the precursor and across the shock, along a nominally uniform line of sight that is perpendicularmore » to the propagation of the shock waves. Radiation from the shock was able to excite NeI, ArII, and XeII/XeIII precursor spectral features. It is shown that the combination of interferometry and optical spectroscopy data is inconsistent with upstream plasmas being in LTE. Specifically, electron density gradients do not correspond to any apparent temperature change in the emission spectra. Experimental data are compared to 1D radiation hydrodynamics HELIOS-CR simulations and to PrismSPECT atomic physics calculations to assist in a physical interpretation of the observations. We show that upstream plasma is likely in the process of being radiatively heated and that the emission from a small percentage of ionised atoms within a cool background plasma dominates the emission spectra. Experiments were carried out on the MAGPIE and COBRA pulsed-power facilities at Imperial College London and Cornell University, respectively.« less

Head orientation affects the intracranial pressure response resulting from shock wave loading in the rat.

PubMed

Dal Cengio Leonardi, Alessandra; Keane, Nickolas J; Bir, Cynthia A; Ryan, Anne G; Xu, Liaosa; Vandevord, Pamela J

2012-10-11

Since an increasing number of returning military personnel are presenting with neurological manifestations of traumatic brain injury (TBI), there has been a great focus on the effects resulting from blast exposure. It is paramount to resolve the physical mechanism by which the critical stress is being inflicted on brain tissue from blast wave encounters with the head. This study quantitatively measured the effect of head orientation on intracranial pressure (ICP) of rats exposed to a shock wave. Furthermore, the study examined how skull maturity affects ICP response of animals exposed to shock waves at various orientations. Results showed a significant increase in ICP values in larger rats at any orientation. Furthermore, when side-ICP values were compared to the other orientations, the peak pressures were significantly lower suggesting a relation between ICP and orientation of the head due to geometry of the skull and location of sutures. This finding accentuates the importance of skull dynamics in explaining possible injury mechanisms during blast. Also, the rate of pressure change was measured and indicated that the rate was significantly higher when the top of the head was facing the shock front. The results confirm that the biomechanical response of the superior rat skull is distinctive compared to other areas of the skull, suggesting a skull flexure mechanism. These results not only present insights into the mechanism of brain injury, but also provide information which can be used for designing more effective protective head gear. Copyright © 2012 Elsevier Ltd. All rights reserved.

Protection of the lung from blast overpressure by stress wave decouplers, buffer plates or sandwich panels.

PubMed

Sedman, Andrew; Hepper, A

2018-03-19

This paper outlines aspects of UK Ministry of Defence's research and development of blast overpressure protection technologies appropriate for use in body armour, with the aim of both propagating new knowledge and updating existing information. Two simple models are introduced not only to focus the description of the mechanism by which the lungs can be protected, but also to provide a bridge between fields of research that may hold the key to further advances in protection technology and related body armour. Protection can be provided to the lungs by decoupling the stress wave transmission into the thorax by managing the blast energy imparted through the protection system. It is proposed that the utility of the existing 'simple decoupler' blast overpressure protection is reviewed in light of recent developments in the treatment of those sustaining both overpressure and fragment injuries. It is anticipated that further advances in protection technology may be generated by those working in other fields on the analogous technologies of 'buffer plates' and 'sandwich panels'. © Crown copyright (2018), Dstl. This material is licensed under the terms of the Open Government Licence except where otherwise stated. To view this licence, visit http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3 or write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email: psi@nationalarchives.gsi.gov.uk.

AN EXTERNAL SHOCK ORIGIN OF GRB 141028A

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

Burgess, J. Michael; Bégué, Damien; Ryde, Felix

The prompt emission of the long, smooth, and single-pulsed gamma-ray burst, GRB 141028A, is analyzed under the guise of an external shock model. First, we fit the γ -ray spectrum with a two-component photon model, namely, synchrotron+blackbody, and then fit the recovered evolution of the synchrotron νF{sub ν} peak to an analytic model derived considering the emission of a relativistic blast wave expanding into an external medium. The prediction of the model for the νF{sub ν} peak evolution matches well with the observations. We observe the blast wave transitioning into the deceleration phase. Furthermore, we assume the expansion of themore » blast wave to be nearly adiabatic, motivated by the low magnetic field deduced from the observations. This allows us to recover within an order of magnitude the flux density at the νF{sub ν} peak, which is remarkable considering the simplicity of the analytic model. Under this scenario we argue that the distinction between prompt and afterglow emission is superfluous as both early-time emission and late-time emission emanate from the same source. While the external shock model is clearly not a universal solution, this analysis opens the possibility that at least some fraction of GRBs can be explained with an external shock origin of their prompt phase.« less

Initiation and structures of gaseous detonation

NASA Astrophysics Data System (ADS)

Vasil'ev, A. A.; Vasiliev, V. A.

2018-03-01

The analysis of the initiation of a detonation wave (DW) and the emergence of a multi-front structure of the DW-front are presented. It is shown that the structure of the DW arises spontaneously at the stage of a strong overdriven of the wave. The hypothesis of the gradual enhancement of small perturbations on an initially smooth initiating blast wave, traditionally used in the numerical simulation of multi-front detonation, does not agree with the experimental data. The instability of the DW is due to the chemical energy release of the combustible mixture Q. A technique for determining the Q-value of mixture was proposed, based on reconstruction of the trajectory of the expanding wave from the position of the strong explosion model. The wave trajectory at the critical initiation of a multifront detonation in a combustible mixture is compared with the trajectory of an explosive wave from the same initiator in an inert mixture whose gas-dynamic parameters are equivalent to the parameters of the combustible mixture. The energy release of a mixture is defined as the difference in the joint energy release of the initiator and the fuel mixture during the critical initiation and energy release of the initiator when the blast wave is excited in an inert mixture. Observable deviations of the experimental profile of Q from existing model representations were found.

Comparison of Some Blast Vibration Predictors for Blasting in Underground Drifts and Some Observations

NASA Astrophysics Data System (ADS)

Bhagwat, Vaibhab Pramod; Dey, Kaushik

2016-04-01

Drilling and blasting are the most economical excavation techniques in underground drifts driven through hard rock formation. Burn cut is the most popular drill pattern, used in this case, to achieve longer advance per blast round. The ground vibration generated due to the propagation of blast waves on the detonation of explosive during blasting is the principal cause for structural and rock damage. Thus, ground vibration is a point of concern for the blasting engineers. The ground vibration from a blast is measured using a seismograph placed at the blast monitoring station. The measured vibrations, in terms of peak particle velocity, are related to the maximum charge detonated at one instant and the distance of seismograph from the blast point. The ground vibrations from a number of blast rounds of varying charge/delay and distances are monitored. A number of scaling factors of these dependencies (viz. Distance and maximum charge/delay) have been proposed by different researchers, namely, square root, cube root, CMRI, Langefors and Kihlstrom, Ghosh-Daemon, Indian standard etc. Scaling factors of desired type are computed for all the measured blast rounds. Regression analysis is carried out between the scaling factors and peak particle velocities to establish the coefficients of the vibration predictor equation. Then, the developed predictor equation is used for designing the blast henceforth. Director General of Mine Safety, India, specified that ground vibrations from eight to ten blast rounds of varying charge/delay and distances should be monitored to develop a predictor equation; however, there is no guideline about the type of scaling factor to be used. Further to this, from the statistical point of view, a regression analysis on a small sample population cannot be accepted without the testing of hypothesis. To show the importance of the above, in this paper, seven scaling factors are considered for blast data set of a hard-rock underground drift using burn-cut blast design. The possible step by step approach to establish a vibration predictor equation is also proposed.

Two-material optimization of plate armour for blast mitigation using hybrid cellular automata

NASA Astrophysics Data System (ADS)

Goetz, J.; Tan, H.; Renaud, J.; Tovar, A.

2012-08-01

With the increased use of improvised explosive devices in regions at war, the threat to military and civilian life has risen. Cabin penetration and gross acceleration are the primary threats in an explosive event. Cabin penetration crushes occupants, damaging the lower body. Acceleration causes death at high magnitudes. This investigation develops a process of designing armour that simultaneously mitigates cabin penetration and acceleration. The hybrid cellular automaton (HCA) method of topology optimization has proven efficient and robust in problems involving large, plastic deformations such as crash impact. Here HCA is extended to the design of armour under blast loading. The ability to distribute two metallic phases, as opposed to one material and void, is also added. The blast wave energy transforms on impact into internal energy (IE) inside the solid medium. Maximum attenuation occurs with maximized IE. The resulting structures show HCA's potential for designing blast mitigating armour structures.

Homemade battery-operated multi-barreled muzzle-loading gun.

PubMed

Ramiah, R; Thirunavukkarasu, G

2003-11-01

In a recent shootout by a terrorist group against a law enforcement agency, some unusual firearms were seized. On examination, these firearms were found to be homemade, battery-operated, multi-barreled muzzle-loading guns, analogous to a repeater. Reference to battery-operated firearms is rather scanty in the literature. Hence, the unique design features, electrical circuit, and the operation system of these unusual guns are described.

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

The Sedov Blast Wave as a Radial Piston Verification Test

DOE PAGES

Pederson, Clark; Brown, Bart; Morgan, Nathaniel

2016-06-22

The Sedov blast wave is of great utility as a verification problem for hydrodynamic methods. The typical implementation uses an energized cell of finite dimensions to represent the energy point source. We avoid this approximation by directly finding the effects of the energy source as a boundary condition (BC). Furthermore, the proposed method transforms the Sedov problem into an outward moving radial piston problem with a time-varying velocity. A portion of the mesh adjacent to the origin is removed and the boundaries of this hole are forced with the velocities from the Sedov solution. This verification test is implemented onmore » two types of meshes, and convergence is shown. Our results from the typical initial condition (IC) method and the new BC method are compared.« less

The state of clouds in a violent interstellar medium

NASA Astrophysics Data System (ADS)

Heathcote, S. R.; Brand, P. W. J. L.

1983-04-01

A highly approximate but simple model is developed which describes the interaction of a supernova blast wave with an interstellar cloud. The behavior of a cloud when exposed to conditions prevalent in a violent interstellar medium is examined using this model. Results show that after a cloud has been shocked it is rarely allowed sufficient time to return to pressure equilibrium with its surroundings before encountering a second shock. Thus, significant departures from pressure equilibrium are inevitable. It is determined that the disruption of a cloud by its passage through a blast wave is quite effective and the half life of clouds cannot greatly exceed the mean interval between shocks striking a given cloud. In addition, it is found that composite core-envelope clouds are not viable under typical conditions.

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

Cellular characterization of compression-induceddamage in live biological samples

NASA Astrophysics Data System (ADS)

Bo, Chiara; Balzer, Jens; Hahnel, Mark; Rankin, Sara M.; Brown, Katherine A.; Proud, William

2012-03-01

Understanding the damage that high intensity compression waves induce in human tissues is critical for developing improved therapies for patients suffering from blast injuries. Experimentally based models of blast injury using live biological samples are needed. In this study we have developed a system to directly assess the effects of dynamic loading conditions on live cells. Here, we describe a confinement chamber designed to subject live cell cultures in a liquid environment to high intensity compression waves using a split Hopkinson pressure bar system. Signals from the strain gauges mounted on the bars and the chamber allow the measurement of parameters such as pressure and duration of the stimulus. The chamber itself also allows recovery of cells subjected to compression for assessment of cellular damage. In these studies we present evidence of increased levels of damage and loss of cellular integrity in cultured mouse mesenchymal stem cells subjected to a high-intensity compression wave with a peak pressure of 7.6 ± 0.8 MPa.

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

Modeling of weak blast wave propagation in the lung.

PubMed

D'yachenko, A I; Manyuhina, O V

2006-01-01

Blast injuries of the lung are the most life-threatening after an explosion. The choice of physical parameters responsible for trauma is important to understand its mechanism. We developed a one-dimensional linear model of an elastic wave propagation in foam-like pulmonary parenchyma to identify the possible cause of edema due to the impact load. The model demonstrates different injury localizations for free and rigid boundary conditions. The following parameters were considered: strain, velocity, pressure in the medium and stresses in structural elements, energy dissipation, parameter of viscous criterion. Maximum underpressure is the most suitable wave parameter to be the criterion for edema formation in a rabbit lung. We supposed that observed scattering of experimental data on edema severity is induced by the physiological variety of rabbit lungs. The criterion and the model explain this scattering. The model outlines the demands for experimental data to make an unambiguous choice of physical parameters responsible for lung trauma due to impact load.

Reactive Blast Waves from Composite Charges

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

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

2009-10-16

Investigated here is the performance of composite explosives - measured in terms of the blast wave they drive into the surrounding environment. The composite charge configuration studied here was a spherical booster (1/3 charge mass), surrounded by aluminum (Al) powder (2/3 charge mass) at an initial density of {rho}{sub 0} = 0.604 g/cc. The Al powder acts as a fuel but does not detonate - thereby providing an extreme example of a 'non-ideal' explosive (where 2/3 of the charge does not detonate). Detonation of the booster charge creates a blast wave that disperses the Al powder and ignites the ensuingmore » Al-air mixture - thereby forming a two-phase combustion cloud embedded in the explosion. Afterburning of the booster detonation products with air also enhances and promotes the Al-air combustion process. Pressure waves from such reactive blast waves have been measured in bomb calorimeter experiments. Here we describe numerical simulations of those experiments. A Heterogeneous Continuum Model was used to model the dispersion and combustion of the Al particle cloud. It combines the gasdynamic conservation laws for the gas phase with a dilute continuum model for the dispersed phase, as formulated by Nigmatulin. Inter-phase mass, momentum and energy exchange are prescribed by phenomenological models of Khasainov. It incorporates a combustion model based on mass conservation laws for fuel, air and products; source/sink terms are treated in the fast-chemistry limit appropriate for such gasdynamic fields, along with a model for mass transfer from the particle phase to the gas. The model takes into account both the afterburning of the detonation products of the booster with air, and the combustion of the Al particles with air. The model equations were integrated by high-order Godunov schemes for both the gas and particle phases. Adaptive Mesh Refinement (AMR) was used to capture the energy-bearing scales of the turbulent flow on the computational grid, and to track/resolve reaction zones. Numerical simulations of the explosion fields from 1.5-g and 10-kg composite charges were performed. Computed pressure histories (red curve) are compared with measured waveforms (black curves) in Fig. 1. Comparison of these results with a waveform for a non-combustion case in nitrogen (blue curve) demonstrates that a reactive blast wave was formed. Cross-sectional views of the temperature field at various times are presented in Fig. 2, which shows that the flow is turbulent. Initially, combustion occurs at the fuel-air interface, and the energy release rate is controlled by the rate of turbulent mixing. Eventually, oxidizer becomes distributed throughout the cloud via ballistic mixing of the particles with air; energy release then occurs in a distributed combustion mode, and Al particle kinetics controls the energy release rate. Details of the Heterogeneous Continuum Model and results of the numerical simulations of composite charge explosions will be described in the paper.« less

Mechanical damage of tympanic membrane in relation to impulse pressure waveform - A study in chinchillas.

PubMed

Gan, Rong Z; Nakmali, Don; Ji, Xiao D; Leckness, Kegan; Yokell, Zachary

2016-10-01

Mechanical damage to middle ear components in blast exposure directly causes hearing loss, and the rupture of the tympanic membrane (TM) is the most frequent injury of the ear. However, it is unclear how the severity of injury graded by different patterns of TM rupture is related to the overpressure waveforms induced by blast waves. In the present study, the relationship between the TM rupture threshold and the impulse or overpressure waveform has been investigated in chinchillas. Two groups of animals were exposed to blast overpressure simulated in our lab under two conditions: open field and shielded with a stainless steel cup covering the animal head. Auditory brainstem response (ABR) and wideband tympanometry were measured before and after exposure to check the hearing threshold and middle ear function. Results show that waveforms recorded in the shielded case were different from those in the open field and the TM rupture threshold in the shielded case was lower than that in the open field (3.4 ± 0.7 vs. 9.1 ± 1.7 psi or 181 ± 1.6 vs. 190 ± 1.9 dB SPL). The impulse pressure energy spectra analysis of waveforms demonstrates that the shielded waveforms include greater energy at high frequencies than that of the open field waves. Finally, a 3D finite element (FE) model of the chinchilla ear was used to compute the distributions of stress in the TM and the TM displacement with impulse pressure waves. The FE model-derived change of stress in response to pressure loading in the shielded case was substantially faster than that in the open case. This finding provides the biomechanical mechanisms for blast induced TM damage in relation to overpressure waveforms. The TM rupture threshold difference between the open and shielded cases suggests that an acoustic role of helmets may exist, intensifying ear injury during blast exposure. Copyright © 2016 Elsevier B.V. All rights reserved.

Seismo-acoustic analysis of the near quarry blasts using Plostina small aperture array

NASA Astrophysics Data System (ADS)

Ghica, Daniela; Stancu, Iulian; Ionescu, Constantin

2013-04-01

Seismic and acoustic signals are important to recognize different type of industrial blasting sources in order to discriminate between them and natural earthquakes. We have analyzed the seismic events listed in the Romanian catalogue (Romplus) for the time interval between 2011 and 2012, and occurred in the Dobrogea region, in order to determine detection seismo-acoustic signals of quarry blasts by Plostina array stations. Dobrogea is known as a seismic region characterized by crustal earthquakes with low magnitudes; at the same time, over 40 quarry mines are located in the area, being sources of blasts recorded both with the seismic and infrasound sensors of the Romanian Seismic Network. Plostina seismo-acoustic array, deployed in the central part of Romania, consists of 7 seismic sites (3C broad-band instruments and accelerometers) collocated with 7 infrasound instruments. The array is particularly used for the seismic monitoring of the local and regional events, as well as for the detection of infrasonic signals produced by various sources. Considering the characteristics of the infrasound sensors (frequency range, dynamic, sensibility), the array proved its efficiency in observing the signals produced by explosions, mine explosion and quarry blasts. The quarry mines included for this study cover distances of two hundreds of kilometers from the station and routinely generate explosions that are detected as seismic and infrasonic signals with Plostina array. The combined seismo-acoustic analysis uses two types of detectors for signal identification: one, applied for the seismic signal identification, is based on array processing techniques (beamforming and frequency-wave number analysis), while the other one, which is used for infrasound detection and characterization, is the automatic detector DFX-PMCC (Progressive Multi-Channel Correlation Method). Infrasonic waves generated by quarry blasts have frequencies ranging from 0.05 Hz up to at least 6 Hz and amplitudes below 5 Pa. Seismic data analysis shows that the frequency range of the signals are above 2 Hz. Surface explosions such as quarry blasts are useful sources for checking detection and location efficiency, when seismic measurements are added. The process is crucial for discrimination purposes and for establishing of a set of ground-truth infrasound events. Ground truth information plays a key role in the interpretation of infrasound signals, by including near-field observations from industrial blasts.

Assessment and Treatment of Blast-Induced Auditory and Vestibular Injuries

DTIC Science & Technology

2016-06-01

Year 2: Q 1 – 2. Examine cochlear and vestibular tissue at 1d and 7d after bTBI Q 3 – 4. Examine cochlear and vestibular tissue at 30d and 60d...the key features of blast wave flow conditions, including the negative phase and secondary shock. However the ABS has not been previously utilized to...isoflurane can be easily adjusted by the flow control. However, due to movement artefact and nosecone constraints, it is a sub-optimal anesthetic

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.

AFWL (Air Force Weapons Laboratory) HULL (Hydrodynamics Unlimited) calculations of air blast over a dam slope. Final report

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

Fry, M.A.; Needham, C.E.; Stucker, M.

1976-10-01

This laboratory performed Hydrodynamics Unlimited (HULL) calculations of the air blast over a dam for two yields and two pressure regions. A 5th calculation included a rigid blockhouse at the foot of the dam. Although the shielding effect of the dam reduced the incident blast wave overpressure, reflection of the shock from the valley floor raised the peak overpressure up to at least 40% of the free air value. In almost every case, the overpressure impulses near the foot of the dam were greater than or equal to free air values. The rigid blockhouse experienced the most severe overpressure environments.more » The assumption of a 50-psi hard blockhouse is reasonable. During collapse of the blockhouse, it appears to be rigid to the air flow, since it responds slowly to the rapid air blast. Although there may be other reasons to detonate the weapon on the surface of the reservoir, the best way to destroy the blockhouse and any related structures with air blast, probably would be to detonate the device downstream of the blockhouse.« less

Gangliosides and Ceramides Change in a Mouse Model of Blast Induced Traumatic Brain Injury

PubMed Central

2013-01-01

Explosive detonations generate atmospheric pressure changes that produce nonpenetrating blast induced “mild” traumatic brain injury (bTBI). The structural basis for mild bTBI has been extremely controversial. The present study applies matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging to track the distribution of gangliosides in mouse brain tissue that were exposed to very low level of explosive detonations (2.5–5.5 psi peak overpressure). We observed major increases of the ganglioside GM2 in the hippocampus, thalamus, and hypothalamus after a single blast exposure. Moreover, these changes were accompanied by depletion of ceramides. No neurological or brain structural signs of injury could be inferred using standard light microscopic techniques. The first source of variability is generated by the Latency between blast and tissue sampling (peak intensity of the blast wave). These findings suggest that subtle molecular changes in intracellular membranes and plasmalemma compartments may be biomarkers for biological responses to mild bTBI. This is also the first report of a GM2 increase in the brains of mature mice from a nongenetic etiology. PMID:23590251

Influence of pellet seating on the external ballistic parameters of spring-piston air guns.

PubMed

Werner, Ronald; Schultz, Benno; Frank, Matthias

2016-09-01

In firearm examiners' and forensic specialists' casework as well as in air gun proof testing, reliable measurement of the weapon's muzzle velocity is indispensable. While there are standardized and generally accepted procedures for testing the performance of air guns, the method of seating the diabolo pellets deeper into the breech of break barrel spring-piston air guns has not found its way into standardized test procedures. The influence of pellet seating on the external ballistic parameters was investigated using ten different break barrel spring-piston air guns. Test shots were performed with the diabolo pellets seated 2 mm deeper into the breech using a pellet seater. The results were then compared to reference shots with conventionally loaded diabolo pellets. Projectile velocity was measured with a high-precision redundant ballistic speed measurement system. In eight out of ten weapons, the muzzle energy increased significantly when the pellet seater was used. The average increase in kinetic energy was 31 % (range 9-96 %). To conclude, seating the pellet even slightly deeper into the breech of spring-piston air guns might significantly alter the muzzle energy. Therefore, it is strongly recommended that this effect is taken into account when accurate and reliable measurements of air gun muzzle velocity are necessary.

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.

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

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

Blasting Damage Predictions by Numerical Modeling in Siahbishe Pumped Storage Powerhouse

NASA Astrophysics Data System (ADS)

Eslami, Majid; Goshtasbi, Kamran

2018-04-01

One of the popular methods of underground and surface excavations is the use of blasting. Throughout this method of excavation, the loading resulted from blasting can be affected by different geo-mechanical and structural parameters of rock mass. Several factors affect turbulence in underground structures some of which are explosion, vibration, and stress impulses caused by the neighbouring blasting products. In investigating the blasting mechanism one should address the processes which expand with time and cause seismic events. To protect the adjoining structures against any probable deconstruction or damage, it is very important to model the blasting process prior to any actual operation. Efforts have been taken in the present study to demonstrate the potentiality of numerical methods in predicting the specified parameters in order to prevent any probable destruction. For this purpose the blasting process was modeled, according to its natural implementation, in one of the tunnels of Siahbishe dam by the 3DEC and AUTODYN 3D codes. 3DEC was used for modeling the blasting environment as well as the blast holes and AUTODYN 3D for modeling the explosion process in the blast hole. In this process the output of AUTODYN 3D, which is a result of modeling the blast hole and is in the form of stress waves, is entered into 3DEC. For analyzing the amount of destruction made by the blasting operation, the key parameter of Peak Particle Velocity was used. In the end, the numerical modeling results have been compared with the data recorded by the seismographs planted through the tunnel. As the results indicated 3DEC and AUTODYN 3D proved appropriate for analyzing such an issue. Therefore, by means of these two softwares one can analyze explosion processes prior to their implementation and make close estimation of the damage resulting from these processes.

Energies of GRB blast waves and prompt efficiencies as implied by modelling of X-ray and GeV afterglows

NASA Astrophysics Data System (ADS)

Beniamini, Paz; Nava, Lara; Duran, Rodolfo Barniol; Piran, Tsvi

2015-11-01

We consider a sample of 10 gamma-ray bursts with long-lasting ( ≳ 102 s) emission detected by Fermi/Large Area Telescope and for which X-ray data around 1 d are also available. We assume that both the X-rays and the GeV emission are produced by electrons accelerated at the external forward shock, and show that the X-ray and the GeV fluxes lead to very different estimates of the initial kinetic energy of the blast wave. The energy estimated from GeV is on average ˜50 times larger than the one estimated from X-rays. We model the data (accounting also for optical detections around 1 d, if available) to unveil the reason for this discrepancy and find that good modelling within the forward shock model is always possible and leads to two possibilities: (i) either the X-ray emitting electrons (unlike the GeV emitting electrons) are in the slow-cooling regime or (ii) the X-ray synchrotron flux is strongly suppressed by Compton cooling, whereas, due to the Klein-Nishina suppression, this effect is much smaller at GeV energies. In both cases the X-ray flux is no longer a robust proxy for the blast wave kinetic energy. On average, both cases require weak magnetic fields (10-6 ≲ ɛB ≲ 10-3) and relatively large isotropic kinetic blast wave energies 10^{53} erg<{E}_{0,kin}<10^{55} erg corresponding to large lower limits on the collimated energies, in the range 10^{52} erg<{E}_{θ ,kin}<5× 10^{52} erg for an ISM (interstellar medium) environment with n ˜ 1 cm-3 and 10^{52} erg<{E}_{θ ,kin}<10^{53} erg for a wind environment with A* ˜ 1. These energies are larger than those estimated from the X-ray flux alone, and imply smaller inferred values of the prompt efficiency mechanism, reducing the efficiency requirements on the still uncertain mechanism responsible for prompt emission.

Analysis of the X-ray emission of nine Swift afterglows

NASA Astrophysics Data System (ADS)

Panaitescu, A.; Mészáros, P.; Gehrels, N.; Burrows, D.; Nousek, J.

2006-03-01

The X-ray light curves of nine Swift XRT afterglows (050126, 050128, 050219A, 050315, 050318, 050319, 050401, 050408 and 050505) display a complex behaviour: a steep t-3.0+/-0.3 decay until ~400 s, followed by a significantly slower t-0.65+/-0.20 fall-off, which at 0.2-2 day after the burst evolves into a t-1.7+/-0.5 decay. We consider three possible models for the geometry of relativistic blast-waves (spherical outflows, non-spreading jets and spreading jets), two possible dynamical regimes for the forward shock (adiabatic and fully radiative), and we take into account a possible angular structure of the outflow and delayed energy injection in the blast-wave to identify the models which reconcile the X-ray light-curve decay with the slope of the X-ray continuum for each of the above three afterglow phases. By piecing together the various models for each phase in a way that makes physical sense, we identify possible models for the entire X-ray afterglow. The major conclusion of this work is that a long-lived episode of energy injection in the blast-wave, during which the shock energy increases at t1.0+/-0.5, is required for five afterglows and could be at work in the other four as well. For some afterglows, there may be other mechanisms that can explain the t < 400 s fast falling-off X-ray light curve (e.g. the large-angle gamma-ray burst emission), the 400 s to 5 h slow decay (e.g. a structured outflow), or the steepening at 0.2-2 day (e.g. a jet-break, a collimated outflow transiting from a wind with a r-3 radial density profile to a homogeneous or outward-increasing density region). Optical observations in conjunction with the X-ray can distinguish among these various models. Our simple tests allow the determination of the location of the cooling frequency relative to the X-ray domain and, thus, of the index of the electron power-law distribution with energy in the blast-wave. The resulting indices are clearly inconsistent with a universal value.

X-Ray Emission from Supernova Remnants.

NASA Astrophysics Data System (ADS)

Sackville Hamilton, Andrew James

1984-12-01

This thesis deals with the x-ray spectra of supernova remnants (SNRs), and in particular the x-ray spectra of the two young Type I SNRs SN1006 and Tycho. Firstly an extensive grid of nonequilibrium model spectra of SNRs in the adiabatic blast wave stage of evolution is computed, and numerous diagnostics of the state and composi- tion of the blast wave plasma are plotted over parameter space. It is demonstrated that the spectrum of an adiabatic blast wave is a good approximation to several other model SNR structures in which emission is dominated by gas undergoing quasi steady state ioni- zation near a shock front, including the one-fluid isothermal blast wave similarity solution, and the reverse shock similarity solution advocated by Chevalier for the early evolution of Type I SNe. None of these structures appears able to account for the observed spectra of SN1006 or Tycho. A new similarity solution for the early time evolution of uniform ejecta moving into an external medium is presented. It is argued that the x-ray spectra of SN1006 and Tycho are consistent with emission mainly from a reverse shock into 1.4M(,o) of initially uniform density SN ejecta consisting of pure heavy elements, moving into a uniform medium. Satisfactory fits to the observed spectra are obtained with a two layer structure of ejecta, an outer layer of unprocessed material, and an inner layer of mixed processed heavy elements. The structure of ejecta inferred is similar for both SN1006 and Tycho, the marked difference between the two spectra being attributed largely to the lower density of the ambient medium around SN1006. The results are consistent with the theory of Type I SNe as exploded white dwarfs, and resolve the apparent problems of too little iron, and too much total mass, deduced by other authors from earlier analyses of the x-ray emission of SN1006 and Tycho. Various salient aspects of the physics of a shock-heated pure heavy element plasma are discussed.

Instability of a Planar Expansion Wave

DTIC Science & Technology

2005-10-11

Israel 3E. T. S. I. Industriales , Universidad de Castilla-La Mancha, 13071 Cuidad Real, Spain Received 18 March 2005; published 11 October 2005 An...modulation amplitude m=dx. As first shown in 3, for ideal gases with moderate values of , like 5 3 or 7 5 , m in a rippled rarefaction wave exhibits...radiating gases . The accuracy of such approximation is beyond the scope of the present paper see 17 and refer- ences therein. A blast wave

Rigid polyurethane foam as an efficient material for shock wave attenuation

NASA Astrophysics Data System (ADS)

Komissarov, P. V.; Borisov, A. A.; Sokolov, G. N.; Lavrov, V. V.

2016-09-01

A new method for reducing parameters of blast waves generated by explosions of HE charges on ground is presented. Most of the traditional techniques reduce the wave parameters at a certain distance from the charge, i.e. as a matter of fact the damping device interacts with a completely formed shock wave. The proposed approach is to use rigid polyurethane foam coating immediately the explosive charge. A distributed structure of such a foam block that provides most efficient shock wave attenuation is suggested. Results of experimental shock wave investigations recorded in tests in which HE charges have been exploded with damping devices and without it are compared.

On the propagation of decaying planar shock and blast waves through non-uniform channels

NASA Astrophysics Data System (ADS)

Peace, J. T.; Lu, F. K.

2018-05-01

The propagation of planar decaying shock and blast waves in non-uniform channels is investigated with the use of a two-equation approximation of the generalized CCW theory. The effects of flow non-uniformity for the cases of an arbitrary strength decaying shock and blast wave in the strong shock limit are considered. Unlike the original CCW theory, the two-equation approximation takes into account the effects of initial temporal flow gradients in the flow properties behind the shock as the shock encounters an area change. A generalized order-of-magnitude analysis is carried out to analyze under which conditions the classical area-Mach (A-M) relation and two-equation approximation are valid given a time constant of decay for the flow properties behind the shock. It is shown that the two-equation approximation extends the applicability of the CCW theory to problems where flow non-uniformity behind the shock is orders of magnitude above that for appropriate use of the A-M relation. The behavior of the two-equation solution is presented for converging and diverging channels and compared against the A-M relation. It is shown that the second-order approximation and A-M relation have good agreement for converging geometries, such that the influence of flow non-uniformity behind the shock is negligible compared to the effects of changing area. Alternatively, the two-equation approximation is shown to be strongly dependent on the initial magnitude of flow non-uniformity in diverging geometries. Further, in diverging geometries, the inclusion of flow non-uniformity yields shock solutions that tend toward an acoustic wave faster than that predicted by the A-M relation.

Reactivity and Fragmentation of Aluminum-based Structural Energetic Materials under Explosive Loading

NASA Astrophysics Data System (ADS)

Glumac, Nick; Clemenson, Michael; Guadarrama, Jose; Krier, Herman

2015-06-01

Aluminum-cased warheads have been observed to generate enhanced blast and target damage due to reactivity of the aluminum fragments with ambient air. This effect can more than double the output of a conventional warhead. The mechanism by which the aluminum reacts under these conditions remains poorly understood. We undertake a highly controlled experimental study to investigate the phenomenon of aluminum reaction under explosive loading. Experiments are conducted with Al 6061 casings and PBX-N9 explosive with a fixed charge to case mass ratio of 1:2. Results are compared to inert casings (steel), as well as to tests performed in nitrogen environments to isolate aerobic and anaerobic effects. Padded walls are used in some tests to isolate the effects of impact-induced reactions, which are found to be non-negligible. Finally, blast wave measurements and quasi-static pressure measurements are used to isolate the fraction of case reaction that is fast enough to drive the primary blast wave from the later time reaction that generates temperature and overpressure only in the late-time fireball. Fragment size distributions, including those in the micron-scale range, are collected and quantified.

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.

[The muzzle and biochemical genetic markers as supplementary breed characteristics in cattle].

PubMed

Tarasiuk, S I; Glazko, V I; Trofimenko, A L

1997-01-01

The comparative analysis of characteristics of three different cattle breeds (Brown Carpathian, Pinzgauer, Red Polish) on the 5 molecular-genetic markers and 5 muzzle dermatoglyphic types was carried out. It was indicated, that one characteristic can not be use as a breed-specific one but only their complex. The main aspect of search of this complex is the use of characteristics which mark different structure-functional systems of whole organism.

Unusual planned complex suicide committed with a muzzle-loading pistol in combination with subsequent hanging.

PubMed

Ondruschka, Benjamin; Morgenthal, Sylvia; Dreβler, Jan; Bayer, Ronny

2016-11-01

In Germany, suicides by firearms are not very common in contrast to deaths by hanging and intoxications. The use of historical muzzle-loading firearms in the context of suicides is a rarity. Contact shots from muzzle loaders cause an unusual wound morphology with extensive soot soiling. We report the case of a 59-year-old man, who committed a planned complex suicide by shooting into his mouth with a replica percussion gun in combination with hanging. The gunshot injury showed strong explosive effects in the oral cavity with fractures of the facial bones and the skull associated with cerebral evisceration (so-called Krönlein shot). Due to the special constellation of the case with hanging immediately after the shot, external bleeding from the head injuries was only moderate. Therefore, the head injuries could be assessed and partially reconstructed already at the scene.

Concepts and strategies for clinical management of blast-induced traumatic brain injury and posttraumatic stress disorder.

PubMed

Chen, Yun; Huang, Wei; Constantini, Shlomi

2013-01-01

After exposure of the human body to blast, kinetic energy of the blast shock waves might be transferred into hydraulic energy in the cardiovascular system to cause a rapid physical movement or displacement of blood (a volumetric blood surge). The volumetric blood surge moves through blood vessels from the high-pressure body cavity to the low-pressure cranial cavity, causing damage to tiny cerebral blood vessels and the blood-brain barrier (BBB). Large-scale cerebrovascular insults and BBB damage that occur globally throughout the brain may be the main causes of non-impact, blast-induced brain injuries, including the spectrum of traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD). The volumetric blood surge may be a major contributor not only to blast-induced brain injuries resulting from physical trauma, but may also be the trigger to psychiatric disorders resulting from emotional and psychological trauma. Clinical imaging technologies, which are able to detect tiny cerebrovascular insults, changes in blood flow, and cerebral edema, may help diagnose both TBI and PTSD in the victims exposed to blasts. Potentially, prompt medical treatment aiming at prevention of secondary neuronal damage may slow down or even block the cascade of events that lead to progressive neuronal damage and subsequent long-term neurological and psychiatric impairment.

Simplified modeling of blast waves from metalized heterogeneous explosives

NASA Astrophysics Data System (ADS)

Zarei, Z.; Frost, D. L.

2011-09-01

The detonation of a metalized explosive generates a complex multiphase flow field. Modeling the subsequent propagation of the blast front requires a detailed knowledge of the metal particle dynamics and reaction rate. Given the uncertainties in modeling these phenomena, a much simpler, 1D compressible flow model is used to illustrate the general effects of secondary energy release due to particle reaction on the blast front properties. If the total energy release is held constant, the blast pressure and impulse are primarily dependent on the following parameters: the proportion of secondary energy released due to afterburning, the rate of energy release, the location the secondary energy release begins, and the range over which it occurs. Releasing the total energy over a longer time period in general reduces the peak blast overpressure at a given distance. However, secondary energy release reduces the rate of decay of the shock pressure, increases the local gas temperature and hence increases the velocity of the secondary shock front. As a result, for certain values of the above parameters, the peak blast impulse may be increased by a factor of about two in a region near the charge. The largest augmentation to the near-field peak impulse results when the secondary energy is released immediately behind the shock front rather than uniformly within the combustion products.

The quinary pattern of blast injury.

PubMed

Kluger, Yoram; Nimrod, Adi; Biderman, Philippe; Mayo, Ami; Sorkin, Patric

2007-01-01

Bombing is the primary weapon of global terrorism, and it results in a complicated, multidimensional injury pattern. It induces bodily injuries through the well-documented primary, secondary, tertiary, and quaternary mechanisms of blast. Their effects dictate special medical concern and timely implementation of diagnostic and management strategies. Our objective is to report on clinical observations of patients admitted to the Tel Aviv Medical Center following a terrorist bombing. The explosion injured 27 patients, and three died. Four survivors who had been in close proximity to the explosion, as indicated by their eardrum perforation and additional blast injuries, were exposed to the blast wave. They exhibited a unique and immediate hyperinflammatory state, two upon admission to the intensive care unit and two during surgery. This hyperinflammatory state manifested as hyperpyrexia, sweating, low central venous pressure, and positive fluid balance. This state did not correlate with the complexity of injuries sustained by any of the 67 patients admitted to the intensive care unit after previous bombings. The patients' hyperinflammatory behavior, unrelated to their injury complexity and severity of trauma, indicates a new injury pattern in explosions, termed the "quinary blast injury pattern." Unconventional materials used in the manufacture of the explosive can partly explain the observed early hyperinflammatory state. Medical personnel caring for blast victims should be aware of this new type of bombing injury.

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

A Novel Closed-Head Model of Mild Traumatic Brain Injury Caused by Primary Overpressure Blast to the Cranium Produces Sustained Emotional Deficits in Mice

PubMed Central

Heldt, Scott A.; Elberger, Andrea J.; Deng, Yunping; Guley, Natalie H.; Del Mar, Nobel; Rogers, Joshua; Choi, Gy Won; Ferrell, Jessica; Rex, Tonia S.; Honig, Marcia G.; Reiner, Anton

2014-01-01

Emotional disorders are a common outcome from mild traumatic brain injury (TBI) in humans, but their pathophysiological basis is poorly understood. We have developed a mouse model of closed-head blast injury using an air pressure wave delivered to a small area on one side of the cranium, to create mild TBI. We found that 20-psi blasts in 3-month-old C57BL/6 male mice yielded no obvious behavioral or histological evidence of brain injury, while 25–40 psi blasts produced transient anxiety in an open field arena but little histological evidence of brain damage. By contrast, 50–60 psi blasts resulted in anxiety-like behavior in an open field arena that became more evident with time after blast. In additional behavioral tests conducted 2–8 weeks after blast, 50–60 psi mice also demonstrated increased acoustic startle, perseverance of learned fear, and enhanced contextual fear, as well as depression-like behavior and diminished prepulse inhibition. We found no evident cerebral pathology, but did observe scattered axonal degeneration in brain sections from 50 to 60 psi mice 3–8 weeks after blast. Thus, the TBI caused by single 50–60 psi blasts in mice exhibits the minimal neuronal loss coupled to “diffuse” axonal injury characteristic of human mild TBI. A reduction in the abundance of a subpopulation of excitatory projection neurons in basolateral amygdala enriched in Thy1 was, however, observed. The reported link of this neuronal population to fear suppression suggests their damage by mild TBI may contribute to the heightened anxiety and fearfulness observed after blast in our mice. Our overpressure air blast model of concussion in mice will enable further studies of the mechanisms underlying the diverse emotional deficits seen after mild TBI. PMID:24478749

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

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

Quantifying Coastal Hazard of Airburst-Generated Tsunamis

NASA Astrophysics Data System (ADS)

Titov, V. V.; Boslough, M.

2017-12-01

The effort to prevent or mitigate the effects of an impact on Earth is known as planetary defense. A significant component of planetary defense research involves risk assessment. Much of our understanding of the risk from near-Earth objects comes from the geologic record in the form of impact craters, but not all asteroid impacts are crater-forming events. Small asteroids explode before reaching the surface, generating an airburst, and most impacts into the ocean do not penetrate the water to form a crater in the sea floor. The risk from these non-crater-forming ocean impacts and airbursts is difficult to quantify and represents a significant uncertainty in our assessment of the overall threat. One of the suggested mechanisms for the production of asteroid-generated tsunami is by direct coupling of the pressure wave to the water, analogous to the means by which a moving weather front can generate a meteotsunami. To test this hypothesis, we have run a series of airburst simulations and provided time-resolved pressure and wind profiles for tsunami modelers to use as source functions. We used hydrocodes to model airburst scenarios and provide time dependent boundary conditions as input to shallow-water wave propagation codes. The strongest and most destructive meteotsunami are generated by atmospheric pressure oscillations with amplitudes of only a few hPa, corresponding to changes in sea level of a few cm. The resulting wave is strongest when there is a resonance between the ocean and the atmospheric forcing. The blast wave from an airburst propagates at a speed close to a tsunami speed only in the deepest part of the ocean, and a Proudman resonance cannot be usually achieved even though the overpressures are orders of magnitude greater. However, blast wave profiles are N-waves in which a sharp shock wave leading to overpressure is followed by a more gradual rarefaction to a much longer-duration underpressure phase. Even though the blast outruns the water wave it is forcing, the tsunami should continue to be driven by the out-of-resonance gradient associated with the suction phase, which may depend strongly on the details of the airburst scenario. The open question is whether there are any conditions under which such an airburst can generate tsunami with substantial coastal hazard to contribute to the overall impact risk.

Characterizing the energy output generated by a standard electric detonator using shadowgraph imaging

NASA Astrophysics Data System (ADS)

Petr, V.; Lozano, E.

2017-09-01

This paper overviews a complete method for the characterization of the explosive energy output from a standard detonator. Measurements of the output of explosives are commonly based upon the detonation parameters of the chemical energy content of the explosive. These quantities provide a correct understanding of the energy stored in an explosive, but they do not provide a direct measure of the different modes in which the energy is released. This optically based technique combines high-speed and ultra-high-speed imaging to characterize the casing fragmentation and the detonator-driven shock load. The procedure presented here could be used as an alternative to current indirect methods—such as the Trauzl lead block test—because of its simplicity, high data accuracy, and minimum demand for test repetition. This technique was applied to experimentally measure air shock expansion versus time and calculating the blast wave energy from the detonation of the high explosive charge inside the detonator. Direct measurements of the shock front geometry provide insight into the physics of the initiation buildup. Because of their geometry, standard detonators show an initial ellipsoidal shock expansion that degenerates into a final spherical wave. This non-uniform shape creates variable blast parameters along the primary blast wave. Additionally, optical measurements are validated using piezoelectric pressure transducers. The energy fraction spent in the acceleration of the metal shell is experimentally measured and correlated with the Gurney model, as well as to several empirical formulations for blasts from fragmenting munitions. The fragment area distribution is also studied using digital particle imaging analysis and correlated with the Mott distribution. Understanding the fragmentation distribution plays a critical role when performing hazard evaluation from these types of devices. In general, this technique allows for characterization of the detonator within 6-8% error with no knowledge of the amount or type of explosive contained within the shell, making it also suitable for the study of unknown improvised explosive devices.

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.

Quantification of non-ideal explosion violence with a shock tube

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

Jackson, Scott I; Hill, Larry G

There is significant interest in quantifying the blast violence associated with various nonideal explosions. Such data is essential to evaluate the damage potential of both explosive cookoff and terrorist explosive scenarios. We present a technique designed to measure the source energy associated with a non-ideal, asymmetrical, and three-dimensional explosion. A tube is used to confine and focus energy from a blast event into a one-dimensional, quasi-planar shock front. During propagation along the length of the tube, the wave is allowed to shocksteepen into a more ideal form. Pressure transducers then measure the shock overpressure as a function of the distancemore » from the source. One-dimensional blast scaling theory allows calculation of the source energy from this data. This small-scale test method addresses cost and noise concerns as well as boosting and symmetry issues associated with large-scale, three-dimensional, blast arena tests. Results from both ideal explosives and non-ideal explosives are discussed.« less

Methods to Reduce Sand Ejecta from Projectile Impact - a Scaled Study with the Goal of Application to Depleted Uranium Penetrator Catch Boxes

DTIC Science & Technology

2012-04-01

caliber ammunition that were commercially available were used in this study: (1) lead ball (M33 ball) and (2) armor piercing ( machine hardened steel, M2 ...each test fire. The barrel will be a machined 0.50 caliber, 1 in 15-inch right twist bore, 29-inch length barrel without a muzzle brake; muzzle brake...11 Figure 15. Fired M2 50-caliber round

LOADING MACHINE FOR REACTORS

DOEpatents

Simon, S.L.

1959-07-01

An apparatus is described for loading or charging slugs of fissionable material into a nuclear reactor. The apparatus of the invention is a "muzzle loading" type comprising a delivery tube or muzzle designed to be brought into alignment with any one of a plurality of fuel channels. The delivery tube is located within the pressure shell and it is also disposed within shielding barriers while the fuel cantridges or slugs are forced through the delivery tube by an externally driven flexible ram.

Powder Lot Variations: A Case Study with H4831 - Hodgdon Extreme

DTIC Science & Technology

2012-11-30

7.62x39 mm. Long range applications also require smaller variations in muzzle velocity from shot to shot, with variations in ambient temperature, with... flash hole and case neck with appropriate tools. Cleaning brass in stainless tumbling media is important to consistency. For example, we have...likely pressure variations, consider that QuickLoad V3.6 predicts a muzzle velocity of 3174 ft/s and a peak pressure of 54371 psi for 79 grains of

The U.S. M-16 rifle versus the Russian AK-47 rifle. A comparison of terminal ballistics.

PubMed

Swan, K G; Swan, R C; Levine, M G; Rocko, J M

1983-09-01

The standard U.S. military rifle (M-16) is substantially more destructive than its Russian counterpart (AK-47) when fired at short range into clay blocks, despite the fact that the AK-47 is of larger caliber and fires a much heavier bullet with a kinetic energy (muzzle) 25% greater when compared to the M-16. The decisive factor is the 40% greater muzzle velocity of the M-16.

Consortium Study of the Chelyabinsk Meteorite

NASA Technical Reports Server (NTRS)

Righter, K.; Fries, M. D.; Gibson, E. K.; Harrington, R.; Keller, L. P.; McCoy, T. J.; Morris, R. V.; Nagao, K.; Nakamura-Messenger, K.; Niles, P.;

Case Report: Lightning-Induced Pneumomediastinum.

PubMed

Blumenthal, Ryan; Saayman, Gert

2017-06-01

We present the case of a 41-year-old woman who was fatally injured during a witnessed lightning strike event and in whom autopsy revealed the unusual keraunopathological finding of overt pneumomediastinum. The possible pathophysiological mechanism(s) of causation of this phenomenon are discussed, with specific reference also to the "Macklin" effect and the role of blast overpressures associated with lightning strike. It is suggested that the latter may lead to sudden alveolar rupture, with subsequent rapid tracking of air along bronchovascular sheaths in a centripetal manner toward the hilum of the lung and thus into the mediastinum. A review of the blast literature suggests that this victim would have been exposed to a blast pressure wave of approximately 29-psi (200 kPa) to 72-psi (500 kPa) magnitude.

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

2016-10-01

Righting Reflex of rats following double blast exposure. 0 4 8 12 16 20 R ig ht in g Re fle x (m in ut es ) PLACEBO FISH OIL Total Lived Died...experiments. Funding Support: Geneva Foundation contractor – WRAIR Name: Joseph B. Long, Ph.D. Project Role: Co-Investigator – WRAIR Researcher...Funding Support: Clinical Research Management contractor Name: Andrew B. Batuure Project Role: Technician - WRAIR Researcher Identifier (e.g. ORCID

Role of helmet in the mechanics of shock wave propagation under blast loading conditions.

PubMed

Ganpule, S; Gu, L; Alai, A; Chandra, N

2012-01-01

The effectiveness of helmets in extenuating the primary shock waves generated by the explosions of improvised explosive devices is not clearly understood. In this work, the role of helmet on the overpressurisation and impulse experienced by the head were examined. The shock wave-head interactions were studied under three different cases: (i) unprotected head, (ii) head with helmet but with varying head-helmet gaps and (iii) head covered with helmet and tightly fitting foam pads. The intensification effect was discussed by examining the shock wave flow pattern and verified with experiments. A helmet with a better protection against shock wave is suggested.

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.

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.

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.

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.

CFD Modelling of Bore Erosion in Two-Stage Light Gas Guns

NASA Technical Reports Server (NTRS)

Bogdanoff, D. W.

1998-01-01

A well-validated quasi-one-dimensional computational fluid dynamics (CFD) code for the analysis of the internal ballistics of two-stage light gas guns is modified to explicitly calculate the ablation of steel from the gun bore and the incorporation of the ablated wall material into the hydrogen working cas. The modified code is used to model 45 shots made with the NASA Ames 0.5 inch light gas gun over an extremely wide variety of gun operating conditions. Good agreement is found between the experimental and theoretical piston velocities (maximum errors of +/-2% to +/-6%) and maximum powder pressures (maximum errors of +/-10% with good igniters). Overall, the agreement between the experimental and numerically calculated gun erosion values (within a factor of 2) was judged to be reasonably good, considering the complexity of the processes modelled. Experimental muzzle velocities agree very well (maximum errors of 0.5-0.7 km/sec) with theoretical muzzle velocities calculated with loading of the hydrogen gas with the ablated barrel wall material. Comparison of results for pump tube volumes of 100%, 60% and 40% of an initial benchmark value show that, at the higher muzzle velocities, operation at 40% pump tube volume produces much lower hydrogen loading and gun erosion and substantially lower maximum pressures in the gun. Large muzzle velocity gains (2.4-5.4 km/sec) are predicted upon driving the gun harder (that is, upon using, higher powder loads and/or lower hydrogen fill pressures) when hydrogen loading is neglected; much smaller muzzle velocity gains (1.1-2.2 km/sec) are predicted when hydrogen loading is taken into account. These smaller predicted velocity gains agree well with those achieved in practice. CFD snapshots of the hydrogen mass fraction, density and pressure of the in-bore medium are presented for a very erosive shot.

Design of a Two-Stage Light Gas Gun for Muzzle Velocities of 10 - 11 kms

NASA Technical Reports Server (NTRS)

Bogdanoff, David W.

2016-01-01

Space debris poses a major risk to spacecraft. In low earth orbit, impact velocities can be 10 11 kms and as high as 15 kms. For debris shield design, it would be desirable to be able to launch controlled shape projectiles to these velocities. The design of the proposed 10 11 kmsec gun uses, as a starting point, the Ames 1.280.22 two stage gun, which has achieved muzzle velocities of 10 11.3 kmsec. That gun is scaled up to a 0.3125 launch tube diameter. The gun is then optimized with respect to maximum pressures by varying the pump tube length to diameter ratio (LD), the piston mass and the hydrogen pressure. A pump tube LD of 36.4 is selected giving the best overall performance. Piezometric ratios for the optimized guns are found to be 2.3, much more favorable than for more traditional two stage light gas guns, which range from 4 to 6. The maximum powder chamber pressures are 20 to 30 ksi. To reduce maximum pressures, the desirable range of the included angle of the cone of the high pressure coupling is found to be 7.3 to 14.6 degrees. Lowering the break valve rupture pressure is found to lower the maximum projectile base pressure, but to raise the maximum gun pressure. For the optimized gun with a pump tube LD of 36.4, increasing the muzzle velocity by decreasing the projectile mass and increasing the powder loads is studied. It appears that saboted spheres could be launched to 10.25 and possibly as high as 10.7 10.8 kmsec, and that disc-like plastic models could be launched to 11.05 kms. The use of a tantalum liner to greatly reduce bore erosion and increase muzzle velocity is discussed. With a tantalum liner, CFD code calculations predict muzzle velocities as high as 12 to 13 kms.

Thulium fiber laser induced vapor bubbles using bare, tapered, ball, hollow steel, and muzzle brake fiber optic tips

NASA Astrophysics Data System (ADS)

Gonzalez, David A.; Hardy, Luke A.; Hutchens, Thomas C.; Irby, Pierce B.; Fried, Nathaniel M.

2018-02-01

This study characterizes laser-induced vapor bubbles for five distal fiber optic tip configurations, to provide insight into stone retropulsion experienced during laser ablation of kidney stones. A TFL with 1908-nm wavelength delivered 34 mJ energy per pulse at 500-μs pulse duration through five different fibers: 100-μm-core/170-μm-OD bare fiber tip, 150-μm- to 300-μm-core tapered fiber tip, 100-μm-core/300-μm-OD ball tip fiber, 100-μm-core/340- μm-OD hollow steel tip fiber, and 100-μm-core/560-μm-OD muzzle brake fiber tip. A high speed camera with 10- μm spatial and 9.5-μs temporal resolution imaged vapor bubble dynamics. A needle hydrophone measured pressure transients in forward (0°) and side (90°) directions while placed at a 6.8 +/- 0.4 mm distance from fiber tip. Maximum bubble dimensions (width/length) averaged 0.7/1.5, 1.0/1.6, 0.5/1.1, 0.8/1.9, and 0.7/1.5 mm, for bare, tapered, ball, hollow steel, and muzzle tips, respectively (n=5). The hollow steel tip exhibited the most elongated vapor bubble shape, translating into increased forward pressure in this study and consistent with higher stone retropulsion in previous reports. Relative pressures (a.u.) in (forward/side) directions averaged 1.7/1.6, 2.0/2.0, 1.4/1.2, 6.8/1.1, and 0.3/1.2, for each fiber tip (n=5). For hollow steel tip, forward pressure was 4× higher than for bare fiber. For the muzzle brake fiber tip, forward pressure was 5× lower than for bare fiber. Bubble dimensions and pressure measurements demonstrated that the muzzle tip reduced forward pressure by partially venting vapors through side holes, consistent with lower stone retropulsion observed in previous reports.

Fiber optic muzzle brake tip for reducing fiber burnback and stone retropulsion during thulium fiber laser lithotripsy

NASA Astrophysics Data System (ADS)

Hutchens, Thomas C.; Gonzalez, David A.; Irby, Pierce B.; Fried, Nathaniel M.

2017-01-01

The experimental thulium fiber laser (TFL) is being explored as an alternative to the current clinical gold standard Holmium:YAG laser for lithotripsy. The near single-mode TFL beam allows coupling of higher power into smaller optical fibers than the multimode Holmium laser beam profile, without proximal fiber tip degradation. A smaller fiber is desirable because it provides more space in the ureteroscope working channel for increased saline irrigation rates and allows maximum ureteroscope deflection. However, distal fiber tip burnback increases as fiber diameter decreases. Previous studies utilizing hollow steel sheaths around recessed distal fiber tips reduced fiber burnback but increased stone retropulsion. A "fiber muzzle brake" was tested for reducing both fiber burnback and stone retropulsion by manipulating vapor bubble expansion. TFL lithotripsy studies were performed at 1908 nm, 35 mJ, 500 μs, and 300 Hz using a 100-μm-core fiber. The optimal stainless steel muzzle brake tip tested consisted of a 1-cm-long, 560-μm-outer-diameter, 360-μm-inner-diameter tube with a 275-μm-diameter through hole located 250 μm from the distal end. The fiber tip was recessed a distance of 500 μm. Stone phantom retropulsion, fiber tip burnback, and calcium oxalate stone ablation studies were performed ex vivo. Small stones with a mass of 40±4 mg and 4-mm-diameter were ablated over a 1.5-mm sieve in 25±4 s (n=10) without visible distal fiber tip burnback. Reduction in stone phantom retropulsion distance by 50% and 85% was observed when using muzzle brake tips versus 100-μm-core bare fibers and hollow steel tip fibers, respectively. The muzzle brake fiber tip simultaneously provided efficient stone ablation, reduced stone retropulsion, and minimal fiber degradation during TFL lithotripsy.

Piecewise parabolic method for simulating one-dimensional shear shock wave propagation in tissue-mimicking phantoms

NASA Astrophysics Data System (ADS)

Tripathi, B. B.; Espíndola, D.; Pinton, G. F.

2017-11-01

The recent discovery of shear shock wave generation and propagation in the porcine brain suggests that this new shock phenomenology may be responsible for a broad range of traumatic injuries. Blast-induced head movement can indirectly lead to shear wave generation in the brain, which could be a primary mechanism for injury. Shear shock waves amplify the local acceleration deep in the brain by up to a factor of 8.5, which may tear and damage neurons. Currently, there are numerical methods that can model compressional shock waves, such as comparatively well-studied blast waves, but there are no numerical full-wave solvers that can simulate nonlinear shear shock waves in soft solids. Unlike simplified representations, e.g., retarded time, full-wave representations describe fundamental physical behavior such as reflection and heterogeneities. Here we present a piecewise parabolic method-based solver for one-dimensional linearly polarized nonlinear shear wave in a homogeneous medium and with empirical frequency-dependent attenuation. This method has the advantage of being higher order and more directly extendable to multiple dimensions and heterogeneous media. The proposed numerical scheme is validated analytically and experimentally and compared to other shock capturing methods. A Riemann step-shock problem is used to characterize the numerical dissipation. This dissipation is then tuned to be negligible with respect to the physical attenuation by choosing an appropriate grid spacing. The numerical results are compared to ultrasound-based experiments that measure planar polarized shear shock wave propagation in a tissue-mimicking gelatin phantom. Good agreement is found between numerical results and experiment across a 40 mm propagation distance. We anticipate that the proposed method will be a starting point for the development of a two- and three-dimensional full-wave code for the propagation of nonlinear shear waves in heterogeneous media.

Revisiting the emission from relativistic blast waves in a density-jump medium

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

Geng, J. J.; Huang, Y. F.; Dai, Z. G.

2014-09-01

Re-brightening bumps are frequently observed in gamma-ray burst afterglows. Many scenarios have been proposed to interpret the origin of these bumps, of which a blast wave encountering a density-jump in the circumburst environment has been questioned by recent works. We develop a set of differential equations to calculate the relativistic outflow encountering the density-jump by extending the work of Huang et al. This approach is a semi-analytic method and is very convenient. Our results show that late high-amplitude bumps cannot be produced under common conditions, rather only a short plateau may emerge even when the encounter occurs at an earlymore » time (<10{sup 4} s). In general, our results disfavor the density-jump origin for those observed bumps, which is consistent with the conclusion drawn from full hydrodynamics studies. The bumps thus should be caused by other scenarios.« less

Blast waves from violent explosive activity at Yasur Volcano, Vanuatu

NASA Astrophysics Data System (ADS)

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

2013-11-01

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

The Supercritical Pile Model: Prompt Emission Across the Electromagnetic Spectrum

NASA Technical Reports Server (NTRS)

Kazanas, Demos; Mastichiadis, A.

2008-01-01

The "Supercritical Pile" GRB model is an economical model that provides the dissipation necessary to convert explosively the energy stored in relativistic protons in the blast wave of a GRB into radiation; at the same time it produces spectra whose luminosity peaks at 1 MeV in the lab frame, the result of the kinematics of the proton-photon - pair production reaction that effects the conversion of proton energy to radiation. We outline the fundamental notions behind the "Supercritical Pile" model and discuss the resulting spectra of the prompt emission from optical to gamma-ray energies of order Gamma^2 m_ec^2, (Gamma is the Lorentz factor of the blast wave) present even in the absence of an accelerated particle distribution and compare our results to bursts that cover this entire energy range. Particular emphasis is given on the emission at the GLAST energy range both in the prompt and the afterglow stages of the burst.

Basic Studies on Electro-Energetic Physics (EEP) Weapons Technologies

DTIC Science & Technology

2015-01-15

Po\\\\ered Microwa\\e. High Energ) Laser. Charged Particle Beams. and II) pcrsonic Rail guns . Using these representations. wargame simulations of’ arious...Projectile length = 30 in (76 cm) • Barrel length = 10 m • Muzzle velocity = 2,100 m/s To understand how such an advanced weapon compares with conventional...weaponry, it is illustrating to compare these figures with the M-1 Abrams M256 120mm gun firing a M829A1 kinetic energy round Page 5 • Muzzle

Wounds caused by contact with muzzle-lift relief ports (Mag-Na-Port).

PubMed

Rogers, D R; Shem, R J

1992-12-01

Fan-shaped stippled burns were produced on the skin when a revolver whose barrel had been modified by the Mag-Na-Port process was fired twice with the side of the muzzle in contact. A grazing wound was produced by one bullet, and an oblique entry was produced by the other. The characteristics of Mag-Na-Port wounds and test shots are described, and these are compared with test shots from two other higher power revolvers.

High resolution seismic tomography imaging of Ireland with quarry blast data

NASA Astrophysics Data System (ADS)

Arroucau, P.; Lebedev, S.; Bean, C. J.; Grannell, J.

2017-12-01

Local earthquake tomography is a well established tool to image geological structure at depth. That technique, however, is difficult to apply in slowly deforming regions, where local earthquakes are typically rare and of small magnitude, resulting in sparse data sampling. The natural earthquake seismicity of Ireland is very low. That due to quarry and mining blasts, on the other hand, is high and homogeneously distributed. As a consequence, and thanks to the dense and nearly uniform coverage achieved in the past ten years by temporary and permanent broadband seismological stations, the quarry blasts offer an alternative approach for high resolution seismic imaging of the crust and uppermost mantle beneath Ireland. We detected about 1,500 quarry blasts in Ireland and Northern Ireland between 2011 and 2014, for which we manually picked more than 15,000 P- and 20,000 S-wave first arrival times. The anthropogenic, explosive origin of those events was unambiguously assessed based on location, occurrence time and waveform characteristics. Here, we present a preliminary 3D tomographic model obtained from the inversion of 3,800 P-wave arrival times associated with a subset of 500 events observed in 2011, using FMTOMO tomographic code. Forward modeling is performed with the Fast Marching Method (FMM) and the inverse problem is solved iteratively using a gradient-based subspace inversion scheme after careful selection of damping and smoothing regularization parameters. The results illuminate the geological structure of Ireland from deposit to crustal scale in unprecedented detail, as demonstrated by sensitivity analysis, source relocation with the 3D velocity model and comparisons with surface geology.

Analysis of MINIE2013 Explosion Air-Blast Data

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

Schnurr, Julie M.; Rodgers, Arthur J.; Kim, Keehoon

We report analysis of air-blast overpressure measurements from the MINIE2013 explosive experiments. The MINIE2013 experiment involved a series of nearly 70 near-surface (height-ofburst, HOB, ranging from -1 to +4 m) low-yield (W=2-20 kg TNT equivalent) chemical highexplosives tests that were recorded at local distances (230 m – 28.5 km). Many of the W and HOB combinations were repeated, allowing for quantification of the variability in air-blast features and corresponding yield estimates. We measured canonical signal features (peak overpressure, impulse per unit area, and positive pulse duration) from the air-blast data and compared these to existing air-blast models. Peak overpressure measurementsmore » showed good agreement with the models at close ranges but tended to attenuate more rapidly at longer range (~ 1 km), which is likely caused by upward refraction of acoustic waves due to a negative vertical gradient of sound speed. We estimated yields of the MINIE2013 explosions using the Integrated Yield Determination Tool (IYDT). Errors of the estimated yields were on average within 30% of the reported yields, and there were no significant differences in the accuracy of the IYDT predictions grouped by yield. IYDT estimates tend to be lower than ground truth yields, possibly because of reduced overpressure amplitudes by upward refraction. Finally, we report preliminary results on a development of a new parameterized air-blast waveform.« less

Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen

PubMed Central

Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

2016-01-01

The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent. PMID:27603017

Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen.

PubMed

Kuriakose, Matthew; Skotak, Maciej; Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

2016-01-01

The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent.

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

Uhm, Z. Lucas; Zhang Bing; Hascoeet, Romain

We perform a detailed study on the dynamics of a relativistic blast wave with the presence of a long-lived reverse shock (RS). Although a short-lived RS has been widely considered, the RS is believed to be long-lived as a consequence of a stratification expected on the ejecta Lorentz factors. The existence of a long-lived RS causes the forward shock (FS) dynamics to deviate from a self-similar Blandford-McKee solution. Employing the ''mechanical model'' that correctly incorporates the energy conservation, we present an accurate solution for both the FS and RS dynamics. We conduct a sophisticated calculation of the afterglow emission. Adoptingmore » a Lagrangian description of the blast wave, we keep track of an adiabatic evolution of numerous shells between the FS and RS. An evolution of the electron spectrum is also followed individually for every shell. We then find the FS and RS light curves by integrating over the entire FS and RS shocked regions, respectively. Exploring a total of 20 different ejecta stratifications, we explain in detail how a stratified ejecta affects its blast wave dynamics and afterglow light curves. We show that, while the FS light curves are not sensitive to the ejecta stratifications, the RS light curves exhibit much richer features, including steep declines, plateaus, bumps, re-brightenings, and a variety of temporal decay indices. These distinctive RS features may be observable if the RS has higher values of the microphysics parameters than the FS. We discuss possible applications of our results in understanding the gamma-ray burst afterglow data.« less

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.

PAIR-DOMINATED GeV-OPTICAL FLASH IN GRB 130427A

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

Vurm, Indrek; Hascoët, Romain; Beloborodov, Andrei M., E-mail: indrek.vurm@gmail.com

2014-07-10

We show that the light curve of the double GeV+optical flash in GRB 130427A is consistent with radiation from the blast wave in a wind-type medium with density parameter A = ρr {sup 2} ∼ 5 × 10{sup 10} g cm{sup –1}. The peak of the flash is emitted by copious e {sup ±} pairs created and heated in the blast wave; our first-principle calculation determines the pair-loading factor and temperature of the shocked plasma. Using detailed radiative transfer simulations, we reconstruct the observed double flash. The optical flash is dominated by synchrotron emission from the thermal plasma behind the forward shock, andmore » the GeV flash is produced via inverse Compton (IC) scattering by the same plasma. The seed photons for IC scattering are dominated by the prompt MeV radiation during the first tens of seconds, and by the optical to X-ray afterglow thereafter. IC cooling of the thermal plasma behind the forward shock reproduces all GeV data from a few seconds to ∼1 day. We find that the blast wave Lorentz factor at the peak of the flash is Γ ≈ 200, and the forward shock magnetization is ε{sub B} ∼ 2 × 10{sup –4}. An additional source is required by the data in the optical and X-ray bands at times >10{sup 2} s; we speculate that this additional source may be a long-lived reverse shock in the explosion ejecta.« less

Further Validation of a CFD Code for Calculating the Performance of Two-Stage Light Gas Guns

NASA Technical Reports Server (NTRS)

Bogdanoff, David W.

2017-01-01

Earlier validations of a higher-order Godunov code for modeling the performance of two-stage light gas guns are reviewed. These validation comparisons were made between code predictions and experimental data from the NASA Ames 1.5" and 0.28" guns and covered muzzle velocities of 6.5 to 7.2 km/s. In the present report, five more series of code validation comparisons involving experimental data from the Ames 0.22" (1.28" pump tube diameter), 0.28", 0.50", 1.00" and 1.50" guns are presented. The total muzzle velocity range of the validation data presented herein is 3 to 11.3 km/s. The agreement between the experimental data and CFD results is judged to be very good. Muzzle velocities were predicted within 0.35 km/s for 74% of the cases studied with maximum differences being 0.5 km/s and for 4 out of 50 cases, 0.5 - 0.7 km/s.

Influence of the power supply parameters on the projectile energy in the permanent magnet electrodynamic accelerator

NASA Astrophysics Data System (ADS)

Waindok, Andrzej; Piekielny, Paweł

2017-10-01

The main objective of the research is to investigate, how the power supply parameters influence the kinetic energy of the movable element, called commonly a projectile or bullet. A calculation and measurement results of transient characteristics for an electrodynamic accelerator with permanent magnet support were presented in the paper. The calculations were made with using field-circuit model, which includes the parameters of the power supply, mass of the bullet and friction phenomenon. Characteristics of energy and muzzle velocity verso supply voltage (50 V to 350 V) and capacitance value (60 mF to 340.5 mF) were determined, as well. A measurement verification of selected points of calculation characteristics were carried out for investigated values of muzzle velocity. A good conformity between calculation and measurement results was obtained. Concluding, presented characteristics of the muzzle velocity and energy of the projectile vs. power supply parameters indicate, that accelerators could be used for fatigue testing of materials.

Theoretical Characterizaiton of Visual Signatures (Muzzle Flash)

NASA Astrophysics Data System (ADS)

Kashinski, D. O.; Scales, A. N.; Vanderley, D. L.; Chase, G. M.; di Nallo, O. E.; Byrd, E. F. C.

2014-05-01

We are investigating the accuracy of theoretical models used to predict the visible, ultraviolet and infrared spectra of product materials ejected from the muzzle of currently fielded systems. Recent advances in solid propellants has made the management of muzzle signature (flash) a principle issue in weapons development across the calibers. A priori prediction of the electromagnetic spectra of formulations will allow researchers to tailor blends that yield desired signatures and determine spectrographic detection ranges. We are currently employing quantum chemistry methods at various levels of sophistication to optimize molecular geometries, compute vibrational frequencies, and determine the optical spectra of specific gas-phase molecules and radicals of interest. Electronic excitations are being computed using Time Dependent Density Functional Theory (TD-DFT). A comparison of computational results to experimental values found in the literature is used to assess the affect of basis set and functional choice on calculation accuracy. The current status of this work will be presented at the conference. Work supported by the ARL, and USMA.

Histochemistry of glycoconjugates in the skin of the bovine muzzle, with special reference to glandular structures.

PubMed

Meyer, W; Tsukise, A

1989-01-01

The distribution of glycoconjugates in the muzzle of young adult Holstein cows has been studied by means of selected light-microscopic histochemical methods, including lectin histochemistry. In the skin layers, strong reactions were confined to intercellular substances in between the cells of the vital epidermis, exhibiting neutral glycoconjugates mainly with alpha-D-galactosyl and N-acetyl-D-galactosaminyl residues. In the nasolabial glands, distinctly positive staining for neutral glycoproteins with various saccharide residues (alpha-D-galactose, alpha-N-acetylgalactosamine, D-galactose-beta(1----3)D-N-acetylgalactosamine, beta-D-galactose), and for smaller amounts of acidic glycoconjugates, was found in the secretory cells and the luminal secretion. The cells of the excretory duct system showed weak to moderate reactions (alpha-D-galactose, beta-D-galactose), only the collecting ducts reacted positively for acidic glycoproteins with sialyl residues. The results obtained are discussed in view of muzzle function, with special reference to the salivary nature of the secretion of bovine nasolabial glands.

Optical fiber-based system for continuous measurement of in-bore projectile velocity.

PubMed

Wang, Guohua; Sun, Jinglin; Li, Qiang

2014-08-01

This paper reports the design of an optical fiber-based velocity measurement system and its application in measuring the in-bore projectile velocity. The measurement principle of the implemented system is based on Doppler effect and heterodyne detection technique. The analysis of the velocity measurement principle deduces the relationship between the projectile velocity and the instantaneous frequency (IF) of the optical fiber-based system output signal. To extract the IF of the fast-changing signal carrying the velocity information, an IF extraction algorithm based on the continuous wavelet transforms is detailed. Besides, the performance of the algorithm is analyzed by performing corresponding simulation. At last, an in-bore projectile velocity measurement experiment with a sniper rifle having a 720 m/s muzzle velocity is performed to verify the feasibility of the optical fiber-based velocity measurement system. Experiment results show that the measured muzzle velocity is 718.61 m/s, and the relative uncertainty of the measured muzzle velocity is approximately 0.021%.

In the line of fire--21st-century approach to an ancient war injury.

PubMed

Frank, Matthias; Rademacher, Grit; Schmucker, Uli; David, Stephan; Ekkernkamp, Axel

2009-03-01

Authentic black-powder muzzle-loader weapons or replicas are used today primarily for re-enactments of historic battles. A lay actor playing the role of a Prussian infantryman sustained life-threatening gunshot injuries during a recent re-enactment of a historic battle of the Sixth Coalition. As only blank historic muzzle-loading weaponry was used, the origin of the missile causing the wounding was initially unclear. Further investigation revealed a ramrod that had been propelled out of the barrel of another gunner's smooth-bore gun as cause of injury. The ramrod was hurled on a trajectory of more than 20 m, breaking the victim's shouldered barrel and hitting the victim resulting in severe abdominal, thoracic, and upper limb injuries. The critical incidents while handling muzzle-loading weaponry leading to premature discharge are elucidated. Furthermore, this report demonstrates how actual diagnostics and subsequent surgical treatment enabled this infantryman to survive an injury to which his comrades-in-arms would have succumbed 200 years ago.

Optical fiber-based system for continuous measurement of in-bore projectile velocity

NASA Astrophysics Data System (ADS)

Wang, Guohua; Sun, Jinglin; Li, Qiang

2014-08-01

This paper reports the design of an optical fiber-based velocity measurement system and its application in measuring the in-bore projectile velocity. The measurement principle of the implemented system is based on Doppler effect and heterodyne detection technique. The analysis of the velocity measurement principle deduces the relationship between the projectile velocity and the instantaneous frequency (IF) of the optical fiber-based system output signal. To extract the IF of the fast-changing signal carrying the velocity information, an IF extraction algorithm based on the continuous wavelet transforms is detailed. Besides, the performance of the algorithm is analyzed by performing corresponding simulation. At last, an in-bore projectile velocity measurement experiment with a sniper rifle having a 720 m/s muzzle velocity is performed to verify the feasibility of the optical fiber-based velocity measurement system. Experiment results show that the measured muzzle velocity is 718.61 m/s, and the relative uncertainty of the measured muzzle velocity is approximately 0.021%.

Noise trauma induced by a mousetrap--sound pressure level measurement of vole captive bolt devices.

PubMed

Frank, Matthias; Napp, Matthias; Lange, Joern; Grossjohann, Rico; Ekkernkamp, Axel; Beule, Achim G

2010-05-01

While ballistic parameters of vole captive bolt devices have been reported, there is no investigation on their hazardous potential to cause noise trauma. The aim of this experimental study was to measure the sound pressure levels of vole captive bolt devices. Two different shooting devices were examined with a modular precision sound level meter on an outdoor firing range. Measurements were taken in a semi-circular configuration with measuring points 0 degrees in front of the muzzle, 90 degrees at right angle of the muzzle, and 180 degrees behind the shooting device. Distances between muzzle and microphone were 0.5, 1, 2, 10, and 20 m. Sound pressure levels exceeded 130 dB(C) at any measuring point within the 20-m area. Highest measurements (more than 172 dB[C]) were taken in the 0 degrees direction at the 0.5-m distance for both shooting devices proving the hazardous potential of these gadgets to cause noise trauma.

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.

A Novel Closed-Head Model of Mild Traumatic Brain Injury Using Focal Primary Overpressure Blast to the Cranium in Mice

PubMed Central

Guley, Natalie H.; Rogers, Joshua T.; Del Mar, Nobel A.; Deng, Yunping; Islam, Rafiqul M.; D'Surney, Lauren; Ferrell, Jessica; Deng, Bowei; Hines-Beard, Jessica; Bu, Wei; Ren, Huiling; Elberger, Andrea J.; Marchetta, Jeffrey G.; Rex, Tonia S.; Honig, Marcia G.

2016-01-01

Abstract Mild traumatic brain injury (TBI) from focal head impact is the most common form of TBI in humans. Animal models, however, typically use direct impact to the exposed dura or skull, or blast to the entire head. We present a detailed characterization of a novel overpressure blast system to create focal closed-head mild TBI in mice. A high-pressure air pulse limited to a 7.5 mm diameter area on the left side of the head overlying the forebrain is delivered to anesthetized mice. The mouse eyes and ears are shielded, and its head and body are cushioned to minimize movement. This approach creates mild TBI by a pressure wave that acts on the brain, with minimal accompanying head acceleration-deceleration. A single 20-psi blast yields no functional deficits or brain injury, while a single 25–40 psi blast yields only slight motor deficits and brain damage. By contrast, a single 50–60 psi blast produces significant visual, motor, and neuropsychiatric impairments and axonal damage and microglial activation in major fiber tracts, but no contusive brain injury. This model thus reproduces the widespread axonal injury and functional impairments characteristic of closed-head mild TBI, without the complications of systemic or ocular blast effects or head acceleration that typically occur in other blast or impact models of closed-skull mild TBI. Accordingly, our model provides a simple way to examine the biomechanics, pathophysiology, and functional deficits that result from TBI and can serve as a reliable platform for testing therapies that reduce brain pathology and deficits. PMID:26414413

Prevalence of Cerebral Microhemorrhage following Chronic Blast-Related Mild Traumatic Brain Injury in Military Service Members Using Susceptibility-Weighted MRI.

PubMed

Lotan, E; Morley, C; Newman, J; Qian, M; Abu-Amara, D; Marmar, C; Lui, Y W

2018-05-24

Cerebral microhemorrhages are a known marker of mild traumatic brain injury. Blast-related mild traumatic brain injury relates to a propagating pressure wave, and there is evidence that the mechanism of injury in blast-related mild traumatic brain injury may be different from that in blunt head trauma. Two recent reports in mixed cohorts of blunt and blast-related traumatic brain injury in military personnel suggest that the prevalence of cerebral microhemorrhages is lower than in civilian head injury. In this study, we aimed to characterize the prevalence of cerebral microhemorrhages in military service members specifically with chronic blast-related mild traumatic brain injury. Participants were prospectively recruited and underwent 3T MR imaging. Susceptibility-weighted images were assessed by 2 neuroradiologists independently for the presence of cerebral microhemorrhages. Our cohort included 146 veterans (132 men) who experienced remote blast-related mild traumatic brain injury (mean, 9.4 years; median, 9 years after injury). Twenty-one (14.4%) reported loss of consciousness for <30 minutes. Seventy-seven subjects (52.7%) had 1 episode of blast-related mild traumatic brain injury; 41 (28.1%) had 2 episodes; and 28 (19.2%) had >2 episodes. No cerebral microhemorrhages were identified in any subject, as opposed to the frequency of SWI-detectable cerebral microhemorrhages following blunt-related mild traumatic brain injury in the civilian population, which has been reported to be as high as 28% in the acute and subacute stages. Our results may reflect differences in pathophysiology and the mechanism of injury between blast- and blunt-related mild traumatic brain injury. Additionally, the chronicity of injury may play a role in the detection of cerebral microhemorrhages. © 2018 by American Journal of Neuroradiology.

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

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.

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.

Improving the Performance of Two-Stage Gas Guns By Adding a Diaphragm in the Pump Tube

NASA Technical Reports Server (NTRS)

Bogdanoff, D. W.; Miller, Robert J.

1995-01-01

Herein, we study the technique of improving the gun performance by installing a diaphragm in the pump tube of the gun. A CFD study is carried out for the 0.28 in. gun in the Hypervelocity Free Flight Radiation (HFF RAD) range at the NASA Ames Research Center. The normal, full-length pump tube is studied as well as two pump tubes of reduced length (approximately 75% and approximately 33% of the normal length). Significant improvements in performance are calculated to be gained for the reduced length pump tubes upon the addition of the diaphragm. These improvements are identified as reductions in maximum pressures in the pump tube and at the projectile base of approximately 20%, while maintaining the projectile muzzle velocity or as increases in muzzle velocity of approximately 0.5 km/sec while not increasing the maximum pressures in the gun. Also, it is found that both guns with reduced pump tube length (with diaphragms) could maintain the performance of gun with the full length pump tube without diaphragms, whereas the guns with reduced pump tube lengths without diaphragms could not. A five-shot experimental investigation of the pump tube diaphragm technique is carried out for the gun with a pump tube length of 75% normal. The CFD predictions of increased muzzle velocity are borne out by the experimental data. Modest, but useful muzzle velocity increases (2.5 - 6%) are obtained upon the installation of a diaphragm, compared to a benchmark shot without a diaphragm.

Muzzle flash localization for the dismounted soldier

NASA Astrophysics Data System (ADS)

Kennedy Scott, Will

2015-05-01

The ability to accurately and rapidly know the precise location of enemy fire would be a substantial capability enhancement to the dismounted soldier. Acoustic gun-shot detections systems can provide an approximate bearing but it is desired to precisely know the location (direction and range) of enemy fire; for example to know from `which window' the fire is coming from. Funded by the UK MOD (via Roke Manor Research) QinetiQ is developing an imaging solution built around an InGaAs camera. This paper presents work that QinetiQ has undertaken on the Muzzle Flash Locator system. Key technical challenges that have been overcome are explained and discussed in this paper. They include; the design of the optical sensor and processing hardware to meet low size, weight and power requirements; the algorithm approach required to maintain sensitivity whilst rejecting false alarms from sources such as close passing insects and sun glint from scene objects; and operation on the move. This work shows that such a sensor can provide sufficient sensitivity to detect muzzle flash events to militarily significant ranges and that such a system can be combined with an acoustic gunshot detection system to minimize the false alarm rate. The muzzle flash sensor developed in this work operates in real-time and has a field of view of approximately 29° (horizontal) by 12° (vertical) with a pixel resolution of 0.13°. The work has demonstrated that extension to a sensor with realistic angular rotation rate is feasible.

Localization of the rabies virus antigen in Merkel cells in the follicle-sinus complexes of muzzle skins of rabid dogs.

PubMed

Shimatsu, Taichi; Shinozaki, Harumi; Kimitsuki, Kazunori; Shiwa, Nozomi; Manalo, Daria L; Perez, Rodolfo C; Dilig, Joselito E; Yamada, Kentaro; Boonsriroj, Hassadin; Inoue, Satoshi; Park, Chun-Ho

2016-11-01

The direct fluorescent antibody test (dFAT) on fresh brain tissues is the gold standard for rabies virus antigen detection in dogs. However, this method is laborious and holds a high risk of virus exposure for the experimenter. Skin biopsies are useful for the diagnosis of humans and animals. In mammals, the tactile hair, known as the follicle-sinus complex (FSC), is a specialized touch organ that is abundant in the muzzle skin. Each tactile hair is equipped with more than 2,000 sensory nerve endings. Therefore, this organ is expected to serve as an alternative postmortem diagnostic material. However, the target cells and localization of rabies virus antigen in the FSCs remain to be defined. In the present study, muzzle skins were obtained from 60 rabid dogs diagnosed with rabies by dFAT at the Research Institute of Tropical Medicine in the Philippines. In all dogs, virus antigen was clearly detected in a part of the outer root sheath at the level of the ring sinus of the FSCs, and the majority of cells were positive for the Merkel cell (MC) markers cytokeratin 20 and CAM5.2. Our results suggest that MCs in the FSCs of the muzzle skin are a target for virus replication and could serve as a useful alternative specimen source for diagnosis of rabies. Copyright © 2016 Elsevier B.V. All rights reserved.

Morphometric variation in the papionin muzzle and the biochronology of the South African Plio-Pleistocene karst cave deposits.

PubMed

Gilbert, Christopher C; Grine, Frederick E

2010-03-01

Papionin monkeys are widespread, relatively common members of Plio-Pleistocene faunal assemblages across Africa. For these reasons, papionin taxa have been used as biochronological indicators by which to infer the ages of the South African karst cave deposits. A recent morphometric study of South African fossil papionin muzzle shape concluded that its variation attests to a substantial and greater time depth for these sites than is generally estimated. This inference is significant, because accurate dating of the South African cave sites is critical to our knowledge of hominin evolution and mammalian biogeographic history. We here report the results of a comparative analysis of extant papionin monkeys by which variability of the South African fossil papionins may be assessed. The muzzles of 106 specimens representing six extant papionin genera were digitized and interlandmark distances were calculated. Results demonstrate that the overall amount of morphological variation present within the fossil assemblage fits comfortably within the range exhibited by the extant sample. We also performed a statistical experiment to assess the limitations imposed by small sample sizes, such as typically encountered in the fossil record. Results suggest that 15 specimens are sufficient to accurately represent the population mean for a given phenotype, but small sample sizes are insufficient to permit the accurate estimation of the population standard deviation, variance, and range. The suggestion that the muzzle morphology of fossil papionins attests to a considerable and previously unrecognized temporal depth of the South African karst cave sites is unwarranted.

Optical bullet-tracking algorithms for weapon localization in urban environments

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

Roberts, R S; Breitfeller, E F

2006-03-31

Localization of the sources of small-arms fire, mortars, and rocket propelled grenades is an important problem in urban combat. Weapons of this type produce characteristic signatures, such as muzzle flashes, that are visible in the infrared. Indeed, several systems have been developed that exploit the infrared signature of muzzle flash to locate the positions of shooters. However, systems based on muzzle flash alone can have difficulty localizing weapons if the muzzle flash is obscured or suppressed. Moreover, optical clutter can be problematic to systems that rely on muzzle flash alone. Lawrence Livermore National Laboratory (LLNL) has developed a projectile trackingmore » system that detects and localizes sources of small-arms fire, mortars and similar weapons using the thermal signature of the projectile rather than a muzzle flash. The thermal signature of a projectile, caused by friction as the projectile travels along its trajectory, cannot be concealed and is easily discriminated from optical clutter. The LLNL system was recently demonstrated at the MOUT facility of the Aberdeen Test Center [1]. In the live-fire demonstration, shooters armed with a variety of small-arms, including M-16s, AK-47s, handguns, mortars and rockets, were arranged at several positions in around the facility. Experiments ranged from a single-weapon firing a single-shot to simultaneous fire of all weapons on full automatic. The LLNL projectile tracking system was demonstrated to localize multiple shooters at ranges up to 400m, far greater than previous demonstrations. Furthermore, the system was shown to be immune to optical clutter that is typical in urban combat. This paper describes the image processing and localization algorithms designed to exploit the thermal signature of projectiles for shooter localization. The paper begins with a description of the image processing that extracts projectile information from a sequence of infrared images. Key to the processing is an adaptive spatio-temporal filter developed to suppress scene clutter. The filtered image sequence is further processed to produce a set of parameterized regions, which are classified using several discriminate functions. Regions that are classified as projectiles are passed to a data association algorithm that matches features from these regions with existing tracks, or initializes new tracks as needed. A Kalman filter is used to smooth and extrapolate existing tracks. Shooter locations are determined by solving a combinatorial least-squares solution for all bullet tracks. It also provides an error ellipse for each shooter, quantifying the uncertainty of shooter location. The paper concludes with examples from the live-fire exercise at the Aberdeen Test Center.« less

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

Shock initiated reactions of reactive multi-phase blast explosives

NASA Astrophysics Data System (ADS)

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

2017-01-01

This paper describes a new class of non-ideal explosive compositions made of perfluoropolyether (PFPE), nanoaluminum, and a micron-size, high mass density, reactive metal. Unlike high explosives, these compositions release energy via a fast self-oxidized combustion wave rather than a true self-sustaining detonation. Their reaction rates are shock dependent and they can be overdriven to change their energy release rate. These compositions are fuel rich and have an extended aerobic energy release phase. The term "reactive multiphase blast" refers to the post-dispersion blast behavior: multiphase in that there are a gas phase that imparts pressure and a solid (particulate) phase that imparts energy and momentum [1]; and reactive in that the hot metal particles react with atmospheric oxygen and the explosive gas products to give an extended pressure pulse. Tantalum-based RMBX formulations were tested in two spherical core-shell configurations - an RMBX shell exploded by a high explosive core, and an RMBX core imploded by a high explosive shell. The fireball and blast characteristics were compared to a C-4 baseline charge.

Numerical study of blast characteristics from detonation of homogeneous explosives

NASA Astrophysics Data System (ADS)

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

2010-04-01

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

Air pressure waves from Mount St. Helens eruptions

NASA Astrophysics Data System (ADS)

Reed, Jack W.

1987-10-01

Infrasonic recordings of the pressure wave from the Mount St. Helens (MSH) eruption on May 18, 1980, together with the weather station barograph records were used to estimate an equivalent explosion airblast yield for this eruption. Pressure wave amplitudes versus distance patterns were found to be comparable with patterns found for a small-scale nuclear explosion, the Krakatoa eruption, and the Tunguska comet impact, indicating that the MSH wave came from an explosion equivalent of about 5 megatons of TNT. The peculiar audibility pattern reported, with the blast being heard only at ranges beyond about 100 km, is explained by consideration of finite-amplitude shock propagation developments.

Proceedings of the US Army Symposium on Gun Dynamics (2nd), Held at the Institute on Man and Science, Rensselaerville, N.Y. 19-22 September 1978

DTIC Science & Technology

1978-09-01

Alamo Avenue, S.E. Albuquerque, New Mexico 87106 ABSTRACT: A system for measuring the angular motion of the muzzle of artil- lery weapons during firing...0051, while the author was at EG&G, Inc., Albuquerque Operations, Albuquerque, New Mexico . 01 1-33 COX AND HOKANSON TITLE: Muzzle Motions of the M68...1978. DEGREES HELD: B.A. Chemical Engineer, New Mexico State University, University Park, New Mexico . 1 II1-34 COUNTER RECOIL SYSTEM EFFECTS ON

Muzzle Flash Onset: An Algebraic Criterion and Further Validation of the Muzzle Exhaust Flow Field Model

DTIC Science & Technology

1983-03-01

Tic, equals to (NI/ Nic ) where Nic , defined as the net chemical production rate of i-th species, is in general the algebraic sum of terms which are...detailed analysis has shown that in preignition regions the chemical rates which make a significant contribution to any of the Nic are such that at least...Elkton Division Lab., Inc. ATTN. R. Biddle ATTN: M. Summeitield Tech Lib. 1041 US Hlighway One North P. 0. Box 241 Princeton, NJ 08540 Elkton, MD

Antimony content of inorganic gunshot residue (IGSR) produced by 0.22 caliber rimfire ammunition having free-antimony primer.

PubMed

Zeichner, Arie

2017-01-01

In a recent paper published in Forensic Science International (FSI), Lucas et al. (2016) claimed that muzzle discharge of 0.22 caliber rimfire ammunition is more likely to incorporate particles from the bullet surface than those retained on the firearm and that characteristic particles containing Pb, Ba and Sb formed from known Sb-free primers are likely to be more prevalent in muzzle discharge. It seems that this claim is not based on sufficient experimental results. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Atypical Post Kala Azar Dermal Leishmaniasis with “Muzzle Area” Swelling

PubMed Central

Arora, Sandeep; Bal, Arvinder Singh; Baveja, Sukriti; Sood, Aradhana; Rathi, Khushi Ram; Patil, Pradeep

2015-01-01

A 50-year-old male presented with recurrent swelling of the muzzle area of the face with history of low-grade intermittent fever of 3 year duration managed variously with antibiotics, systemic steroids, and antituberculous therapy. Skin biopsy revealed a granulomatous infiltration negative for acid-fast bacilli and leishmania donovan bodies. Immunochromatography test for rK 39 antigen and polymerase chain reaction for leishmania was positive. He was diagnosed as a case of post kala azar dermal leishmaniasis, managed with injection sodium stibogluconate and followed-up thereafter. PMID:25657406

Atypical post kala azar dermal leishmaniasis with "muzzle area" swelling.

PubMed

Arora, Sandeep; Bal, Arvinder Singh; Baveja, Sukriti; Sood, Aradhana; Rathi, Khushi Ram; Patil, Pradeep

2015-01-01

A 50-year-old male presented with recurrent swelling of the muzzle area of the face with history of low-grade intermittent fever of 3 year duration managed variously with antibiotics, systemic steroids, and antituberculous therapy. Skin biopsy revealed a granulomatous infiltration negative for acid-fast bacilli and leishmania donovan bodies. Immunochromatography test for rK 39 antigen and polymerase chain reaction for leishmania was positive. He was diagnosed as a case of post kala azar dermal leishmaniasis, managed with injection sodium stibogluconate and followed-up thereafter.

Proceedings of the Workshop on the Chemical Suppression of Rocket Afterburning and of Gun Muzzle Flash

DTIC Science & Technology

1987-03-01

We report here the first results of this gun simulator used in the study of muzzle flash. The test setup used is shown in Figure 18. Pressure ports...experiments. For the first tests , the exploding wires mentioned above ignited the gas mixture. Later, "soft" ignition by means of a single tungsten...wire, placed axially in the chamber, was also tested . The voltage pulse applied across this hot wire is shown in Figure 19. This "soft" ignition

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.

Consequences of impacts of small asteroids and comets with Earth

NASA Technical Reports Server (NTRS)

Hills, J. G.

1994-01-01

The fragmentation of a small asteroid in the atmosphere greatly increases its cross sections for aerodynamic braking and energy dissipation. At a typical impact velocity of 22 km/s, the atmosphere absorbs more than half the kinetic energy of stony meteoroids with diameters, D(sub m), less than 220 m and iron meteoroids with D(sub m) less than 80 m. The corresponding diameter for comets with impact velocity 50 km/s is D(sub m) less than 1600 m. Most of the atmospheric energy dissipation occurs in a fraction of a scale height, so large meteors appear to 'explode' or 'flare' at the end of their visible paths. This dissipation of energy in the atmosphere protects the earth from direct impact damage (e.g., craters), but it produces a blast wave that can do considerable damage. The area of destruction around the impact point in which the over-pressure in the blast wave exceeds 4 lb/sq in = 2.8 x 10(exp 5) dynes/cu cm, which is enough to knock over trees and destroy buildings, increases rapidly from zero for chondritic meteoroids less than 56 m in diameter (15 megatons) to about 200 sq km for those 80 m in diameter (48 megatons); the probable diameter of the tunguska impactor of 1908 is about 80 m. Crater formation and earthquakes are not significant in land impacts by stony asteroids less than about 200 m in diameter because of the air protection. A tsunami is probably the most devastating type of damage for asteroids 200 m to 1 km in diameter. An impact by an asteroid this size anywhere in the Atlantic would devastate coastal areas on both sides of the ocean. An asteroid a few kilometers across would produce a tsunami that would reach the foothills of the Appalachian Mountains in the upper half of the East Coast of the United States. Most of Florida is protected from a tsunami by the gradual slope of the ocean off its coast, which causes most of the tsunami energy to be reflected back into the Atlantic. The atmosphere plume produced by asteroids with diameters exceeding about 120 m cannot be contained by the atmosphere, so this bubble of high-temperature gas forms a new layer on top of the atmosphere. The dust entrapped in this hot gas is likely to have optical depths exceeding tau = 10 for asteroids with diameters exceeding about 0.5 to 1 km. The optical flux from asteroids 60 m or more in diameter is enough to ignite pine forests. However, the blast wave from an impacting asteroid goes beyond the radius in which the fire starts. The blast wave tends to blow out the fire, so it is likely that the impact will char the forest, as at Tunguska, but the impact will not produce a sustained fire. Because comets dissipate their energy much higher in the atmosphere than asteroids, they illuminate a much larger region and their blast wave is weaker. So they are much more effective in producing large fires. This suggests that the KT impactor was a comet rather than an asteroid.

Minimisation of the explosion shock wave load onto the occupants inside the vehicle during trinitrotoluene charge blast.

PubMed

Krzystała, Edyta; Mężyk, Arkadiusz; Kciuk, Sławomir

2016-01-01

The aim of this study was to elaborate identification method of crew overload as a result of trinitrotoluene charge explosion under the military wheeled vehicle. During the study, an experimental military ground research was carried out. The aim of this research was to verify the mine blast resistance of the prototype wheeled vehicle according to STANG 4569 as well as the anti-explosive seat. Within the work, the original methodology was elaborated along with a prototype research statement. This article presents some results of the experimental research, thanks to which there is a possibility to estimate the crew's lives being endangered in an explosion through the measurement of acceleration as well as the pressure on the chest, head and internal organs. On the basis of our acceleration results, both effectiveness and infallibility of crew protective elements along with a blast mitigation seat were verified.

Thulium fiber laser-induced vapor bubble dynamics using bare, tapered, ball, hollow steel, and muzzle brake fiber optic tips

NASA Astrophysics Data System (ADS)

Gonzalez, David A.; Hardy, Luke A.; Hutchens, Thomas C.; Irby, Pierce B.; Fried, Nathaniel M.

2018-03-01

This study characterizes laser-induced vapor bubble dynamics for five different distal fiber optic tip configurations, to provide insight into stone retropulsion commonly experienced during laser ablation of kidney stones. A thulium fiber laser with 1908-nm wavelength delivered 34-mJ energy per pulse at 500-μs pulse duration through five different fibers such as 100-μm-core / 170-μm-OD bare fiber tip, 150- to 300-μm-core tapered fiber tip, 100-μm-core / 300-μm-OD ball tip fiber, 100-μm-core / 340-μm-OD hollow steel tip fiber, and 100-μm-core / 560-μm-OD muzzle brake fiber tip. A high-speed camera with 10-μm-spatial and 9.5-μs-temporal resolution was used to image the vapor bubble dynamics. A needle hydrophone measured pressure transients in the forward (0 deg) and side (90 deg) directions while placed at a 6.8 ± 0.4 mm distance from the distal fiber tip. Maximum bubble dimensions (width/length) averaged 0.7/1.5, 1.0/1.6, 0.5/1.1, 0.8/1.9, and 0.7 / 1.5 mm, for bare, tapered, ball, hollow steel, and muzzle brake fiber tips, respectively (n = 5). The hollow steel tip exhibited the most elongated vapor bubble shape, translating into increased forward pressure in this study and consistent with higher stone retropulsion in previous reports. Relative pressures (a.u.) in (forward/side) directions averaged 1.7/1.6, 2.0/2.0, 1.4/1.2, 6.8/1.1, and 0.3/1.2, for each fiber tip (n = 5). For the hollow steel tip, forward pressure was 4 × higher than for the bare fiber. For the muzzle brake fiber tip, forward pressure was 5 × lower than the bare fiber. Bubble dimensions and pressure measurements demonstrated that the muzzle brake fiber tip reduced forward pressure by partially venting vapors through the portholes, which is consistent with the observation of lower stone retropulsion in previous reports.

An Investigation of the Interstellar Environment of Supernova Remnant CTB87

NASA Astrophysics Data System (ADS)

Liu, Qian-Cheng; Chen, Yang; Chen, Bing-Qiu; Zhou, Ping; Wang, Xiao-Tao; Su, Yang

2018-06-01

We present a new millimeter CO-line observation toward supernova remnant (SNR) CTB 87, which was regarded purely as a pulsar wind nebula (PWN), and an optical investigation of a coincident surrounding superbubble. The CO observation shows that the SNR delineated by the radio emission is projectively covered by a molecular cloud (MC) complex at {V}LSR}=-60 to -54 {km} {{{s}}}-1. Both the symmetric axis of the radio emission and the trailing X-ray PWN appear projectively to be along a gap between two molecular gas patches at ‑58 to -57 {km} {{{s}}}-1. Asymmetric broad profiles of 12CO lines peaked at -58 {km} {{{s}}}-1 are found at the eastern and southwestern edges of the radio emission. This represents a kinematic signature consistent with an SNR–MC interaction. We also find that a superbubble, ∼37‧ in radius, appears to surround the SNR from H I 21 cm ({V}LSR}∼ -61 to -68 {km} {{{s}}}-1), WISE mid-IR, and optical extinction data. We build a multi-band photometric stellar sample of stars within the superbubble region and find 82 OB star candidates. The likely peak distance in the stars’ distribution seems consistent with the distance previously suggested for CTB 87. We suggest the arc-like radio emission is mainly a relic of the part of the blast wave that propagates into the MC complex and is now in a radiative stage while the other part of the blast wave has been expanding into the low-density region in the superbubble. This scenario naturally explains the lack of X-ray emission related to the ejecta and blast wave. The SNR–MC interaction also favors a hadronic contribution to the γ-ray emission from the CTB 87 region.

Infrared and X-Ray Evidence for Circumstellar Grain Destruction by the Blast Wave of Supernova 1987A

NASA Technical Reports Server (NTRS)

Dwek, Eliahu; Arendt, Richard G.; Bouchet, Patrice; Burrows, David N.; Challis, Peter; Danziger, John; DeBuizer James M.; Gehrz, Robert D.; Kirshner, Robert P.; McCray, Richard;

Shear wave propagation in anisotropic soft tissues and gels

PubMed Central

Namani, Ravi; Bayly, Philip V.

2013-01-01

The propagation of shear waves in soft tissue can be visualized by magnetic resonance elastography (MRE) [1] to characterize tissue mechanical properties. Dynamic deformation of brain tissue arising from shear wave propagation may underlie the pathology of blast-induced traumatic brain injury. White matter in the brain, like other biological materials, exhibits a transversely isotropic structure, due to the arrangement of parallel fibers. Appropriate mathematical models and well-characterized experimental systems are needed to understand wave propagation in these structures. In this paper we review the theory behind waves in anisotropic, soft materials, including small-amplitude waves superimposed on finite deformation of a nonlinear hyperelastic material. Some predictions of this theory are confirmed in experimental studies of a soft material with controlled anisotropy: magnetically-aligned fibrin gel. PMID:19963987

Pseudoxanthoma elasticum is a metabolic disease.

PubMed

Jiang, Qiujie; Endo, Masayuki; Dibra, Florian; Wang, Krystle; Uitto, Jouni

2009-02-01

Pseudoxanthoma elasticum (PXE) is a pleiotropic multisystem disorder affecting skin, eyes, and the cardiovascular system with progressive pathological mineralization. It is caused by mutations in the ABCC6 gene expressed primarily in the liver and kidneys, and at very low levels, if at all, in tissues affected by PXE. A question has arisen regarding the pathomechanism of PXE, particularly the "metabolic" versus the "PXE cell" hypotheses. We examined a murine PXE model (Abcc6(-/-)) by transplanting muzzle skin from knockout (KO) and wild-type (WT) mice onto the back of WT and KO mice using mineralization of the connective tissue capsule surrounding the vibrissae as an early phenotypic biomarker. Grafting of WT mouse muzzle skin onto the back of KO mice resulted in mineralization of vibrissae, whereas grafting KO mouse muzzle skin onto WT mice did not. Thus, these findings implicate circulatory factors as a critical component of the mineralization process. This mouse grafting model supports the notion that PXE is a systemic metabolic disorder with secondary mineralization of connective tissues and that the mineralization process can be countered or even reversed by changes in the homeostatic milieu.

Pattern injuries from blows with the muzzle end of a handgun.

PubMed

Geisenberger, D; Vogt, S; Pircher, R; Kramer, L; Pollak, S; Große Perdekamp, M

2015-12-01

Pistols, revolvers and blank guns are not only used to discharge cartridges, but also for hits to the victim. In such cases, the blows preferably affect the head and/or the interposed hands protecting the body. The impact is mostly exerted either by the grip of a pistol or the butt of a revolver. In vigorous thrusts inflicted with the muzzle end of the weapon, the edge of the barrel may produce circular punch lesions with central skin flaps roughly corresponding to the bore. As in other kinds of pistol-whipping, the scalp wounds may be associated with fractures of the skull and even with brain contusions. Using the example of a homicide committed by pistol-whipping, the morphological features of blunt injuries from a handgun's muzzle are presented. The characteristic wound pattern found on the victim's head could be reproduced experimentally by forceful blows to the forehead of a slaughtered pig. In the case presented, the dominant hand of the perpetrator showed friction blisters due to prolonged striking with an unhandy tool in the form of a pistol. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

A computational study of laser-supported detonation waves propagating up an oblique incident beam

NASA Astrophysics Data System (ADS)

Bohn, C. L.; Crawford, M. L.

1987-01-01

A series of numerical experiments was conducted to study the propagation of laser-supported detonation waves (LSDWs) in the case that a CO2 laser beam strikes an aluminum surface obliquely in air. A reflected shock formed at the aluminum surface was more prominent at higher angles of incidence theta of the beam, but otherwise the hydrodynamics of the plasma and the LSDW were insensitive to theta. Furthermore, the total impulse delivered to the aluminum varied approximately as 1/cos theta, a result that can be modeled with elementary blast-wave theory.

Vane Flow Direction Sensor for Blast Waves

DTIC Science & Technology

1987-02-07

APPLICATIONS INTL CORP IIT RESEARCH INSTITUTE ATTN: K SITES ATTN: DOCUMENTS LIBRARY SCIENCE APPLICATIONS INTL CORP KAMAN SCIENCES CORP ATTN: TECHNICAL...UBRARY ATTN: L MENTE ATTN: W PLOWS ATTN: LIBRARY SCIENCE APPLICATIONS INTL CORP KAMAN SCIENCE§ CORP ATTN: J MCRARY ATTN: B KINSLOW SCIENCE APPLICATIONS

Excitation and Disruption of a Giant Molecular Cloud by the Sepurnova Remnant 3C 391

NASA Technical Reports Server (NTRS)

Reach, W. T.; Rho, J.

1998-01-01

The ambient molecular gas at the distance of the remnant comprises a giant molecular cloud whose edge is closely parallel to a ridge of bright non-thermal radio continuum, which evidently delineates the blast-wave into the cloud.

Shock tubes and waves; Proceedings of the Fourteenth International Symposium on Shock Tubes and Shock Waves, University of Sydney, Sydney, Australia, August 19-22, 1983

NASA Astrophysics Data System (ADS)

Archer, R. D.; Milton, B. E.

Techniques and facilities are examined, taking into account compressor cascades research using a helium-driven shock tube, the suppression of shocks on transonic airfoils, methods of isentropically achieving superpressures, optimized performance of arc heated shock tubes, pressure losses in free piston driven shock tubes, large shock tubes designed for nuclear survivability testing, and power-series solutions of the gasdynamic equations for Mach reflection of a planar shock by a wedge. Other subjects considered are related to aerodynamics in shock tubes, shocks in dusty gases, chemical kinetics, and lasers, plasmas, and optical methods. Attention is given to vapor explosions and the blast at Mt. St. Helens, combustion reaction mechanisms from ignition delay times, the development and use of free piston wind tunnels, models for nonequilibrium flows in real shock tubes, air blast measuring techniques, finite difference computations of flow about supersonic lifting bodies, and the investigation of ionization relaxation in shock tubes.

SUPERNOVAE AND THEIR EXPANDING BLAST WAVES DURING THE EARLY EVOLUTION OF GALACTIC GLOBULAR CLUSTERS

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

Tenorio-Tagle, Guillermo; Silich, Sergiy; Muñoz-Tuñón, Casiana

2015-11-20

Our arguments deal with the early evolution of Galactic globular clusters and show why only a few of the supernovae (SNe) products were retained within globular clusters and only in the most massive cases (M ≥ 10{sup 6} M{sub ⊙}), while less massive clusters were not contaminated at all by SNe. Here, we show that SN blast waves evolving in a steep density gradient undergo blowout and end up discharging their energy and metals into the medium surrounding the clusters. This inhibits the dispersal and the contamination of the gas left over from a first stellar generation. Only the ejecta from well-centeredmore » SNe that evolve into a high-density medium available for a second stellar generation (2SG) in the most massive clusters would be retained. These are likely to mix their products with the remaining gas, eventually leading in these cases to an Fe-contaminated 2SG.« less

Dynamic loads on human and animal surrogates at different test locations in compressed-gas-driven shock tubes

NASA Astrophysics Data System (ADS)

Alay, E.; Skotak, M.; Misistia, A.; Chandra, N.

2018-01-01

Dynamic loads on specimens in live-fire conditions as well as at different locations within and outside compressed-gas-driven shock tubes are determined by both static and total blast overpressure-time pressure pulses. The biomechanical loading on the specimen is determined by surface pressures that combine the effects of static, dynamic, and reflected pressures and specimen geometry. Surface pressure is both space and time dependent; it varies as a function of size, shape, and external contour of the specimens. In this work, we used two sets of specimens: (1) anthropometric dummy head and (2) a surrogate rodent headform instrumented with pressure sensors and subjected them to blast waves in the interior and at the exit of the shock tube. We demonstrate in this work that while inside the shock tube the biomechanical loading as determined by various pressure measures closely aligns with live-fire data and shock wave theory, significant deviations are found when tests are performed outside.

The X-Ray Evolution of the Symbiotic Star V 407 Cygni During Its 2010 Outburst

NASA Technical Reports Server (NTRS)

Mukai, K.; Nelson, T.; Chomiuk, L.; Donato, D.; Sokoloski, J.

2011-01-01

We present a summary of Swift and Suzaku X-ray observations of the 2010 nova outburst of the symbiotic star, V 407 Cyg. The Suzaku spectrum obtained on day 30 indicates the presence of the supersoft component from the white dwarf surface, as well as optically thin component from the shock between the nova ejecta and the Mira wind. The Swift observations then allow us to track the evolution of both components from day 4 to day 150. Most notable is the sudden brightening of the optically think component around day 20. We identify this as the time when the blast wave reached the immediate vicinity of the photosphere of the Mira. We have developed a simplified model of the blast wave-wind interaction that can reproduce the gross features of the X-ray evolution of V407 Cyg. If the model is correct, the binary separation is likely to be large and the mass loss rate of the Mira is likely to be relatively low.

The X-Ray Evolution of the Symbiotic Star V407 Cygni During Its 2010 Outburst

NASA Technical Reports Server (NTRS)

Mukai, K.; Nelson, T.; Chomiuk, L.; Donato, D.; Sokoloski, J.

2011-01-01

We present a summary of Swift and Suzaku X-ray observations of the 2010 nova outburst of the symbiotic star, V407 Cyg. The Suzaku spectrum obtained on day 30 indicates the presence of the supersoft component from the white dwarf surface, as well as optically thin component from the shock between the nova ejecta and the Mira wind. The Swift observations then allow us to track the evolution of both components from day 4 to day 150. Most notable is the sudden brightening of the optically think component around day 20. We identify this as the time when the blast wave reached the immediate vicinity of the photosphere of the Mira. We have developed a simplified model of the blast wave-wind interaction that can reproduce the gross features of the X-ray evolution of V407 Cyg. If the model is correct, the binary separation is likely to be large and the mass loss rate of the Mira is likely to be relatively low.

A cosmic-ray-mediated shock in the solar system

NASA Technical Reports Server (NTRS)

Eichler, D.

1981-01-01

It is pointed out that the flare-induced blast wave of Aug. 4, 1972, the most violent disturbance in the solar wind on record, produced cosmic rays with an efficiency of about 50%. Such a high efficiency is predicted by the self-regulating production model of cosmic-ray origin in shocks. Most interplanetary shocks, according to simple theoretical analysis, are not strong enough to produce cosmic rays efficiently. However, if shock strength is the key parameter governing efficiency, as present interplanetary data suggest, then shocks from supernova blasts, quasar outbursts, and other violent astrophysical phenomena should be extremely efficient sources of cosmic rays.

Basic Research Investigations into Multimode Laser and EM Launchers for Affordable Rapid Access to Space (Volumes 1 and 2)

DTIC Science & Technology

2010-08-31

not defined. Figure 5.9: Run 10-Schlieren image with only the laser-induced air-breakdown glow visible. (M=8.77, T∞=68.7 K , P∞=0.15 kPa...Run #13-Laser induced blast wave interaction with oblique shock. (M-5.95, T∞=263.7 K , P∞=5.62 kPa, Ep=196±20 J) ................ Error! Bookmark not...the air-breakdown geometry. (M-5.95, T∞=262.3 K , P∞=5.16 kPa, Ep=176±18 J)Error! Bookmark not defined. Figure 5.13: Run#16 - Laser induced blast

Bose--Einstein Correlations and Thermal Cluster Formation in High-energy Collisions

NASA Astrophysics Data System (ADS)

Bialas, A.; Florkowski, W.; Zalewski, K.

The blast wave model is generalized to include the production of thermal clusters, as suggested by the apparent success of the statistical model of particle production at high energies. The formulae for the HBT correlation functions and the corresponding HBT radii are derived.

A miniature pressure sensor for blast event evaluation

NASA Astrophysics Data System (ADS)

Wu, Nan; Wang, Wenhui; Tian, Ye; Niezrecki, Christopher; Wang, Xingwei

2011-06-01

Traumatic brain injury (TBI) is a great potential threat to people who deal with explosive devices. Protection from TBI has attracted more and more interest. Great efforts have been taken to the studies on the understanding of the propagation of the blast events and its effect on TBI. However, one of the biggest challenges is that the current available pressure sensors are not fast enough to capture the blast wave especially the transient period. This paper reports an ultrafast pressure sensor that could be very useful for analysis of the fast changing blast signal. The sensor is based on Fabry-Perot (FP) principle. It uses a 45º angle polished fiber sitting in a V-groove on a silicon chip. The endface of the angle polished fiber and the diaphragm which is lifted off on the side wall of the V-groove form the FP cavity. The sensor is very small and can be mounted on different locations of a helmet to measure blast pressure simultaneously. The tests were conducted at Natick Soldier Research, Development, and Engineering Center (NSRDEC) in Natick, MA. The sensors were mounted in a shock tube, side by side with the reference sensors, to measure a rapidly increased pressure. The results demonstrated that our sensors' responses agreed well with those from the electrical reference sensors and their response time is comparable.

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.

Five Years of Mid-Infrared Evolution of the Remnant of SN 1987A: The Encounter Between the Blast Wave and the Dusty Equatorial Ring

NASA Technical Reports Server (NTRS)

Dwek, Eli; Arendt, Richard G.; Bouchet, Patrice; Burrows, David N.; Challis, Peter; Danziger, I. John; De Buizer, James M.; Gehrz, Robert D.; Park, Sangwook; Polomski, Elisha F.;

Mild neurotrauma indicates a range-specific pressure response to low level shock wave exposure.

PubMed

Vandevord, Pamela J; Bolander, Richard; Sajja, Venkata Siva Sai Sujith; Hay, Kathryn; Bir, Cynthia A

2012-01-01

Identifying the level of overpressure required to create physiological deficits is vital to advance prevention, diagnostic, and treatment strategies for individuals exposed to blasts. In this study, a rodent model of primary blast neurotrauma was employed to determine the pressure at which acute neurological alterations occurred. Rats were exposed to a single low intensity shock wave at a pressure of 0, 97, 117, or 153 kPa. Following exposure, rats were assessed for acute cognitive alterations using the Morris water maze and motor dysfunction using the horizontal ladder test. Subsequently, histological analyses of three brain regions (primary motor cortex, the hippocampal dentate gyrus region, and the posteromedial cortical amygdala) were conducted. Histological parameters included measuring the levels of glial fibrillary acidic protein (GFAP) to identify astrocyte activation, cleaved caspase-3 for early apoptosis identification and Fluoro-Jade B (FJB) which labels degenerating neurons within the brain tissue. The results demonstrated that an exposure to a single 117 kPa shock wave revealed a significant change in overall neurological deficits when compared to controls and the other pressures. The animals showed significant alterations in water maze parameters and a histological increase in the number of GFAP, caspase-3, and FJB-positive cells. It is suggested that when exposed to a low level shock wave, there may be a biomechanical response elicited by a specific pressure range which can cause low level neurological deficits within the rat. These data indicate that neurotrauma induced from a shock wave may lead to cognitive deficits in short-term learning and memory of rats. Additional histological evidence supports significant and diffuse glial activation and cellular damage. Further investigation into the biomechanical aspects of shock wave exposure is required to elucidate this pressure range-specific phenomenon.

Operation Greenhouse. Scientific Director's report of atomic weapon tests at Eniwetok, 1951. Annex 1. 6, blast measurements. Part 3. Pressure near ground level. Section 4. Blast asymmetry from aerial photographs. Section 5. Ball-crusher-gauge measurements of peak pressure

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

Not Available

1985-04-01

Aerial motion pictures from manned aircraft were taken of the Dog, Easy, and George Shots and from a drone aircraft on Dog Shot to determine whether asymmetries in the blast waves could be detected and measured. Only one film, that taken of Dog Shot from a drone, was considered good enough to warrant detailed analysis, but this failed to yield any positive information on asymmetries. The analysis showed that failure to obtain good arrival-time data arose from a number of cases, but primarily from uncertainities in magnification and timing. Results could only be matched with reliable data from blast-velocity switchesmore » by use of large corrections. Asymnetries, if present, were judged to have been too small or to have occurred too early to be detected with the slow-frame speed used. Recommendations for better results include locating the aircraft directly overhead at the time of burst and using a camera having greater frame speed and provided with timing marks.« less

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

Histopathologic criteria to confirm white-nose syndrome in bats

USGS Publications Warehouse

Meteyer, Carol U.; Buckles, Elizabeth L.; Blehert, David S.; Hicks, Alan C.; Green, David E.; Shearn-Bochsler, Valerie I.; Thomas, Nancy J.; Gargas, Andrea; Behr, Melissa

2009-01-01

White-nose syndrome (WNS) is a cutaneous fungal disease of hibernating bats associated with a novel Geomyces sp. fungus. Currently, confirmation of WNS requires histopathologic examination. Invasion of living tissue distinguishes this fungal infection from those caused by conventional transmissible dermatophytes. Although fungal hyphae penetrate the connective tissue of glabrous skin and muzzle, there is typically no cellular inflammatory response in hibernating bats. Preferred tissue samples to diagnose this fungal infection are rostral muzzle with nose and wing membrane fixed in 10% neutral buffered formalin. To optimize detection, the muzzle is trimmed longitudinally, the wing membrane is rolled, and multiple cross-sections are embedded to increase the surface area examined. Periodic acid-Schiff stain is essential to discriminate the nonpigmented fungal hyphae and conidia. Fungal hyphae form cup-like epidermal erosions and ulcers in the wing membrane and pinna with involvement of underlying connective tissue. In addition, fungal hyphae are present in hair follicles and in sebaceous and apocrine glands of the muzzle with invasion of tissue surrounding adnexa. Fungal hyphae in tissues are branching and septate, but the diameter and shape of the hyphae may vary from parallel walls measuring 2 ??m in diameter to irregular walls measuring 3-5 ??m in diameter. When present on short aerial hyphae, curved conidia are approximately 2.5 ??m wide and 7.5 ??m in curved length. Conidia have a more deeply basophilic center, and one or both ends are usually blunt. Although WNS is a disease of hibernating bats, severe wing damage due to fungal hyphae may be seen in bats that have recently emerged from hibernation. These recently emerged bats also have a robust suppurative inflammatory response.

Histopathologic criteria to confirm white-nose syndrome in bats.

PubMed

Meteyer, Carol Uphoff; Buckles, Elizabeth L; Blehert, David S; Hicks, Alan C; Green, D Earl; Shearn-Bochsler, Valerie; Thomas, Nancy J; Gargas, Andrea; Behr, Melissa J

2009-07-01

White-nose syndrome (WNS) is a cutaneous fungal disease of hibernating bats associated with a novel Geomyces sp. fungus. Currently, confirmation of WNS requires histopathologic examination. Invasion of living tissue distinguishes this fungal infection from those caused by conventional transmissible dermatophytes. Although fungal hyphae penetrate the connective tissue of glabrous skin and muzzle, there is typically no cellular inflammatory response in hibernating bats. Preferred tissue samples to diagnose this fungal infection are rostral muzzle with nose and wing membrane fixed in 10% neutral buffered formalin. To optimize detection, the muzzle is trimmed longitudinally, the wing membrane is rolled, and multiple cross-sections are embedded to increase the surface area examined. Periodic acid-Schiff stain is essential to discriminate the nonpigmented fungal hyphae and conidia. Fungal hyphae form cup-like epidermal erosions and ulcers in the wing membrane and pinna with involvement of underlying connective tissue. In addition, fungal hyphae are present in hair follicles and in sebaceous and apocrine glands of the muzzle with invasion of tissue surrounding adnexa. Fungal hyphae in tissues are branching and septate, but the diameter and shape of the hyphae may vary from parallel walls measuring 2 microm in diameter to irregular walls measuring 3-5 microm in diameter. When present on short aerial hyphae, curved conidia are approximately 2.5 microm wide and 7.5 microm in curved length. Conidia have a more deeply basophilic center, and one or both ends are usually blunt. Although WNS is a disease of hibernating bats, severe wing damage due to fungal hyphae may be seen in bats that have recently emerged from hibernation. These recently emerged bats also have a robust suppurative inflammatory response.

An Evaluation of the Compressive Properties of Helmet Pads Pre- and Post-Shock Wave Overpressure Exposure

DTIC Science & Technology

2015-08-14

by ANSI Std. Z39.18 BLAST DROP TESTS BRAIN DAMAGE VISCOELASTICITY BRAIN CONCUSSION ...Cambridge, UK: Cambridge University Press, 1997. [5] W. C. Moss and M. J. King, "Impact response of US Army and National Football League helmet pad

An external shock origin of GRB 141028A

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

Burgess, J. Michael; Bégué, Damien; Ryde, Felix

The prompt emission of the long, smooth, and single-pulsed gamma-ray burst, GRB 141028A, is analyzed under the guise of an external shock model. First, we fit the γ-ray spectrum with a two-component photon model, namely, synchrotron+blackbody, and then fit the recovered evolution of the synchrotron νF ν peak to an analytic model derived considering the emission of a relativistic blast wave expanding into an external medium. The prediction of the model for the νF ν peak evolution matches well with the observations. We observe the blast wave transitioning into the deceleration phase. Furthermore, we assume the expansion of the blastmore » wave to be nearly adiabatic, motivated by the low magnetic field deduced from the observations. This allows us to recover within an order of magnitude the flux density at the νF ν peak, which is remarkable considering the simplicity of the analytic model. Under this scenario we argue that the distinction between prompt and afterglow emission is superfluous as both early-time emission and late-time emission emanate from the same source. In conclusion, while the external shock model is clearly not a universal solution, this analysis opens the possibility that at least some fraction of GRBs can be explained with an external shock origin of their prompt phase.« less

An external shock origin of GRB 141028A

DOE PAGES

Burgess, J. Michael; Bégué, Damien; Ryde, Felix; ...

2016-05-05

The prompt emission of the long, smooth, and single-pulsed gamma-ray burst, GRB 141028A, is analyzed under the guise of an external shock model. First, we fit the γ-ray spectrum with a two-component photon model, namely, synchrotron+blackbody, and then fit the recovered evolution of the synchrotron νF ν peak to an analytic model derived considering the emission of a relativistic blast wave expanding into an external medium. The prediction of the model for the νF ν peak evolution matches well with the observations. We observe the blast wave transitioning into the deceleration phase. Furthermore, we assume the expansion of the blastmore » wave to be nearly adiabatic, motivated by the low magnetic field deduced from the observations. This allows us to recover within an order of magnitude the flux density at the νF ν peak, which is remarkable considering the simplicity of the analytic model. Under this scenario we argue that the distinction between prompt and afterglow emission is superfluous as both early-time emission and late-time emission emanate from the same source. In conclusion, while the external shock model is clearly not a universal solution, this analysis opens the possibility that at least some fraction of GRBs can be explained with an external shock origin of their prompt phase.« less

External front instabilities induced by a shocked particle ring.

PubMed

Rodriguez, V; Saurel, R; Jourdan, G; Houas, L

2014-10-01

The dispersion of a cylindrical particle ring by a blast or shock wave induces the formation of coherent structures which take the form of particle jets. A blast wave, issuing from the discharge of a planar shock wave at the exit of a conventional shock tube, is generated in the center of a granular medium ring initially confined inside a Hele-Shaw cell. With the present experimental setup, under impulsive acceleration, a solid particle-jet formation is observed in a quasi-two-dimensional configuration. The aim of the present investigation is to observe in detail the formation of very thin perturbations created around the external surface of the dispersed particle layer. By means of fast flow visualization with an appropriate recording window, we focus solely on the first instants during which the external particle ring becomes unstable. We find that the critical area of the destabilization of the external ring surface is constant regardless of the acceleration of the initial layer. Moreover, we observe in detail the external front perturbation wavelength, rendered dimensionless by the initial ring perimeter, and follow its evolution with the initial particle layer acceleration. We report this quantity to be constant regardless of the evolution of the initial particle layer acceleration. Finally, we can reasonably assert that external front perturbations depend solely on the material of the particles.

Uniform high order spectral methods for one and two dimensional Euler equations

NASA Technical Reports Server (NTRS)

Cai, Wei; Shu, Chi-Wang

1991-01-01

Uniform high order spectral methods to solve multi-dimensional Euler equations for gas dynamics are discussed. Uniform high order spectral approximations with spectral accuracy in smooth regions of solutions are constructed by introducing the idea of the Essentially Non-Oscillatory (ENO) polynomial interpolations into the spectral methods. The authors present numerical results for the inviscid Burgers' equation, and for the one dimensional Euler equations including the interactions between a shock wave and density disturbance, Sod's and Lax's shock tube problems, and the blast wave problem. The interaction between a Mach 3 two dimensional shock wave and a rotating vortex is simulated.

Curvilinear trajectory estimation of a supersonic bullet using ballistic shock wave arrivals at asynchronous acoustic sensor nodes.

PubMed

Lo, Kam W

2017-06-01

The trajectory of a supersonic bullet, which is subjected to drag and gravity, is curvilinear and the supersonic flight of the bullet generates a ballistic shock wave (SW). A model for the differential time of arrival (DTOA) of the SW at a pair of acoustic sensors is derived for a given bullet trajectory, which is fully described by seven parameters including the drag coefficient exponent and ballistic constant of the bullet. Assuming that the drag coefficient exponent is 0.5, the DTOA model is used to develop a nonlinear least-squares (NLS) method to estimate the other six trajectory parameters using DTOA of SW measurements from each node (which comprises a small acoustic sensor array) of an asynchronous sensor network. The position of the shooter and the muzzle speed of the bullet are then determined by tracing the estimated bullet trajectory back to topographic or man-made obstructions on a digital map. The effectiveness of the NLS method is verified using simulated data for different types of real bullets, and the error standard deviations in the parameter estimates are close to the Cramer-Rao lower bounds.

Cultured embryonic non-innervated mouse muzzle is capable of generating a whisker pattern.

PubMed

Andrés, F L; Van Der Loos, H

1983-01-01

The whisker pattern on the muzzle of the mouse is mapped in the contralateral parietal neocortex, each whisker follicle projecting to its own multineuronal unit ('barrel'). To determine the role, if any, of the peripheral innervation in the establishment of the vibrissal array, we cultured non-innervated prospective whiskerpads from 9- and 10-day-old embryos, mostly on chorioallantoic membrane. The results show that skin, alone, is capable of generating the whisker pattern, thus adducing a strong argument for the hypothesis that the central brain maps have their origin in the periphery. Copyright © 1983. Published by Elsevier Ltd.

Pseudoxanthoma Elasticum is a Metabolic Disease

PubMed Central

Jiang, Qiujie; Endoh, Masayuki; Dibra, Florian; Wang, Krystle; Uitto, Jouni

2011-01-01

Pseudoxanthoma elasticum (PXE) is a pleiotropic multisystem disorder affecting skin, eyes, and the cardiovascular system with progressive pathological mineralization. It is caused by mutations in the ABCC6 gene expressed primarily in the liver and kidneys, and at very low levels, if at all, in tissues affected by PXE. A question has arisen regarding the pathomechanism of PXE, particularly the “metabolic” versus the “PXE cell” hypotheses. We examined a murine PXE model (Abcc6−/−) by transplanting muzzle skin from knock-out (KO) and wild-type (WT) mice onto the back of WT and KO mice using mineralization of the connective tissue capsule surrounding the vibrissae as an early phenotypic biomarker. Grafting of WT mouse muzzle skin onto the back of KO mice resulted in mineralization of vibrissae, while grafting KO mouse muzzle skin onto the WT mice did not. Thus, these findings implicate circulatory factors as a critical component of the mineralization process. This mouse grafting model supports the notion that PXE is a systemic metabolic disorder with secondary mineralization of connective tissues and that the mineralization process can be countered or even reversed by changes in the homeostatic milieu. PMID:18685618

A Crime Scene Fabricated as Suicide.

PubMed

Amararatne, Rrg Sriyantha; Vidanapathirana, Muditha

2017-02-01

When ascertaining the manner of death, the forensic pathologist should be careful, because in some instances, attempts are made by the criminals to conceal homicides as suicides. The case under discussion highlights the contribution of the forensic pathologist in the ascertainment of the manner in firearm deaths. The deceased was a poacher and his dead body was found in a cashew land with his shotgun lying over him. The shirt had a roughly circular defect with muzzle mark, and burnt and blackened margin. Beneath that, on front of the left upper chest a 2cm diameter circular, perforated laceration, with muzzle imprint and, burnt and blackened margin was found. Shelving was found at the upper margin. Chest X-ray showed the downward pellet distribution. Cause of death was chest injuries due to pellets discharged from a smooth bore weapon. Length of the upper arm reach was 65cm (25 inches) and the length from the muzzle to the trigger was 79cm (31 inches). In conclusion, it was found to be a fabricated suicide scene and the manner of death was ascertained as homicide. This reiterates that the postmortem investigation of firearm deaths should be performed or conducted under direct supervision of forensic specialist to deliver justice.

A Crime Scene Fabricated as Suicide

PubMed Central

Amararatne, RRG Sriyantha

2017-01-01

When ascertaining the manner of death, the forensic pathologist should be careful, because in some instances, attempts are made by the criminals to conceal homicides as suicides. The case under discussion highlights the contribution of the forensic pathologist in the ascertainment of the manner in firearm deaths. The deceased was a poacher and his dead body was found in a cashew land with his shotgun lying over him. The shirt had a roughly circular defect with muzzle mark, and burnt and blackened margin. Beneath that, on front of the left upper chest a 2cm diameter circular, perforated laceration, with muzzle imprint and, burnt and blackened margin was found. Shelving was found at the upper margin. Chest X-ray showed the downward pellet distribution. Cause of death was chest injuries due to pellets discharged from a smooth bore weapon. Length of the upper arm reach was 65cm (25 inches) and the length from the muzzle to the trigger was 79cm (31 inches). In conclusion, it was found to be a fabricated suicide scene and the manner of death was ascertained as homicide. This reiterates that the postmortem investigation of firearm deaths should be performed or conducted under direct supervision of forensic specialist to deliver justice. PMID:28384886

Signal-to-solar clutter calculations of AK-47 muzzle flash at various spectral bandpasses near the potassium D1/D2 doublet

NASA Astrophysics Data System (ADS)

Klett, Karl K., Jr.

2010-04-01

An analysis was performed, using MODTRAN, to determine the best filters to use for detecting the muzzle flash of an AK-47 in daylight conditions in the desert. Filters with bandwidths of 0.05, 0.1, 0.5, 1.0, 3.0, and 5.0 nanometers (nm) were analyzed to understand how the optical bandwidth affects the signal-to-solar clutter ratio. These filters were evaluated near the potassium D1 and D2 doublet emission lines that occur at 769.89 and 766.49 nm respectively that are observed where projectile propellants are used. The maximum spectral radiance, from the AK-47 muzzle flash, is 1.88 x 10-2 W/cm2 str micron, and is approximately equal to the daytime atmospheric spectral radiance. The increased emission, due to the potassium doublet lines, and decreased atmospheric transmission, due to oxygen absorption, combine to create a condition where the signal-to-solar clutter ratio is greater than 1. The 3 nm filter, has a signal-to-solar clutter ratio of 2.09 when centered at 765.37 nm and provides the best combination of both cost and signal sensitivity.

A Review of Research on Impulsive Loading of Marine Composites

NASA Astrophysics Data System (ADS)

Porfiri, Maurizio; Gupta, Nikhil

Impulsive loading conditions, such as those produced by blast waves, are being increasingly recognized as relevant in marine applications. Significant research efforts are directed towards understanding the impulsive loading response of traditional naval materials, such as aluminum and steel, and advanced composites, such as laminates and sandwich structures. Several analytical studies are directed towards establishing predictive models for structural response and failure of marine structures under blast loading. In addition, experimental research efforts are focused on characterizing structural response to blast loading. The aim of this review is to provide a general overview of the state of the art on analytical and experimental studies in this field that can serve as a guideline for future research directions. Reported studies cover the Office of Naval Research-Solid Mechanics Program sponsored research along with other worldwide research efforts of relevance to marine applications. These studies have contributed to developing a fundamental knowledge of the mechanics of advanced materials subjected to impulsive loading, which is of interest to all Department of Defense branches.

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.