Nearby Explosions Research Articles

A big bang theory of big brain trauma.

One of the biggest neurophysiological science news headlines of the 2024 summer reported a critical link between post-traumatic stress disorder (PTSD), suicide, and brain injury from blast events in members of the elite US fighting force, Navy SEALS. Researchers from the Department of Defense/Uniformed Services University Brain Tissue Repository (DOD/USU BTR) had discovered a border of neural damage between the layers of white and gray matter comprising the cortical folds of service members' brains. Described as a distinctive anatomical line of astroglial scarring along the shared junctions of gray and white cellular zones of the brain, this tissue injury was unlike that observed for concussive brain trauma. Rather, it was consistent with blast biophysics of mammalian tissues. In this new study, the damage appears to be correlated with long-term, repeated exposure to blast waves from nearby explosions or firing weapons. A cascade of progressive unexplained behaviors, cognitive decline, and severe depression in the trained fighters ensued. This analysis suggested that repetitive, impulsive pressure waves traveling through the service members' heads and brains with each blast had compromised their cognitive centers, setting a downward trajectory in their mental and physical health.

Blast injury risks to humans within a military trench

In land warfare, trenches serve as vital defensive fortifications, offering protection to soldiers while engaging in combat. However, despite their protective function, soldiers often sustain injuries within these trenches. The lack of corresponding blast data alongside empirical injury reports presents a significant knowledge gap, particularly concerning the blast pressures propagating within trench spaces following nearby explosions. This absence hinders the correlation between blast parameters, trench geometry, and reported injury cases, limiting our understanding of blast-related risks within trenches.This paper addresses the critical aspect of blast propagation within trench systems, essential for evaluating potential blast injury risks to individuals within these structures. Through advanced computational fluid dynamics (CFD) simulations, the study comprehensively investigates blast injury risks resulting from explosions near military trenches. Employing a sophisticated computational model, the research analyzes the dynamic blast effects within trenches, considering both geometrical parameters and blast characteristics influenced by explosive weight and scaled distance.The numerical simulations yield valuable insights into the impact of these parameters on blast injury risks, particularly focusing on eardrum rupture, lung injury, and traumatic brain injury levels within the trench. The findings elucidate distinct patterns of high-risk zones, highlighting unique characteristics of internal explosions due to confinement and venting dynamics along the trench. This study underscores the significance of detailed numerical modeling in assessing blast injury risks and provides a novel knowledge base for understanding risks associated with explosives detonating near military trenches. The insights gained contribute to enhancing safety measures in both military and civilian contexts exposed to blast events near trench structures.

Rotation, Strain, and Translation Sensors Performance Tests with Active Seismic Sources.

Interest in measuring displacement gradients, such as rotation and strain, is growing in many areas of geophysical research. This results in an urgent demand for reliable and field-deployable instruments measuring these quantities. In order to further establish a high-quality standard for rotation and strain measurements in seismology, we organized a comparative sensor test experiment that took place in November 2019 at the Geophysical Observatory of the Ludwig-Maximilians University Munich in Fürstenfeldbruck, Germany. More than 24 different sensors, including three-component and single-component broadband rotational seismometers, six-component strong-motion sensors and Rotaphone systems, as well as the large ring laser gyroscopes ROMY and a Distributed Acoustic Sensing system, were involved in addition to 14 classical broadband seismometers and a 160 channel, 4.5 Hz geophone chain. The experiment consisted of two parts: during the first part, the sensors were co-located in a huddle test recording self-noise and signals from small, nearby explosions. In a second part, the sensors were distributed into the field in various array configurations recording seismic signals that were generated by small amounts of explosive and a Vibroseis truck. This paper presents details on the experimental setup and a first sensor performance comparison focusing on sensor self-noise, signal-to-noise ratios, and waveform similarities for the rotation rate sensors. Most of the sensors show a high level of coherency and waveform similarity within a narrow frequency range between 10 Hz and 20 Hz for recordings from a nearby explosion signal. Sensor as well as experiment design are critically accessed revealing the great need for reliable reference sensors.

Coupled vs uncoupled analysis of one-way RC-slabs under nearby air explosions

The numerical techniques used for blast analysis of structures are categorized in “coupled” and “uncoupled” analysis methods. In a coupled analysis, the fluid–structure interaction is taken into account. Such analysis, although more accurate, is often complex and time consuming. In an “uncoupled” analysis, the blast loads are estimated by empirical equations and then applied to the structure in a separate analysis. Such an analysis is more cost effective, and of more interest for most practical design applications. The main objective of this study is to assess the efficiency of the empirical graphs prescribed by the UFC Code for uncoupled analysis of structures under the nearby air explosions of scaled distances between 0.4 and 0.7 kg/m1/3. The main characteristic of such explosions is the highly nonuniform distribution of blast-reflected pressure on the surface of structure. A method has been developed by the authors to address this nonuniform distribution in the uncoupled analysis. To examine the accuracy of analysis, the response values and the pattern of damages introduced on several reinforced concrete slabs under blast loads are compared with the results of a corresponding coupled analysis, and experimental observations. The uncoupled analysis described in this paper can be reasonably employed in the blast analysis and design of many structures.

Research on Escape Pathfinding Algorithm in Virtual Simulation of Fire

Research the authenticity of the virtual simulation of the fire and the problems of the pathfinding to escape. In a real fire, the phenomenon of explosion caused the nearby combustible materials fire with randomness. In order to meet the objective fire situation, the concept of probability of the trigger ignition was proposed to simulate the randomness of fire caused by nearby explosions. Because of the random factors caused by the explosion phenomenon in fire, taking into account the safety and efficiency of the pathfinding to escape, the navigation grid routing algorithm is further improved, a safety escaping algorithm is proposed, which divides the safe area and the dangerous area according to the probability of the trigger ignition and let the characters find the route to escape in the safety area according to the navigation algorithm. Finally, the simulation experiment is carried out. The simulation results show that the fire simulation scenes can be more realistic by combining the probability of the trigger of fire, and the safe escape pathfinding algorithm can provide a safety escaping route for the character.

Iron isotope reveals Earth’s close encounters with supernovae

Three new studies associate iron-60 deposits with nearby stellar explosions that occurred as recently as 1.5 million years ago.

Quantifying the Transport of Energetic Materials in Unsaturated Sediments from Cracked Unexploded Ordnance

Dissolved explosive species have been found in the groundwater under military training areas. These explosives are thought to originate from munitions although the mechanism of transport to the groundwater is poorly understood. This study was conducted to determine whether ruptured unexploded ordnance may be a viable source term for these explosives. The rupturing effect of one 81 mm-mortar exploding in close proximity to another 81-mm mortar was observed and the resulting contaminants were collected. These contaminants were then subjected to leaching experiments on repacked, jack drill compacted unsaturated sediment columns in a climate controlled laboratory. The mortars which were exposed to nearby explosions were shown to be susceptible to rupturing rather than sympathetically detonating under certain conditions. The ruptured mortars released up to 166+/-2 g of pulverized explosive residues (largely Composition B) and the results from the subsequent leaching tests showed that this explosive residue is highly mobile in unsaturated sandy soil. Up to 4.45+/-1.00 g of dissolved explosive contamination was transported through the unsaturated soil columns during the first year of infiltration. The results indicate the mass of transported explosive residue dissolved in the leachate was primarily caused by the preferential dissolution of explosive contaminants having a grain size under 0.125 mm. Surface or near-surface unexploded ordnance (UXO) on live fire ranges may therefore be significant sources of explosive environmental contamination after they have been exposed to other rounds which explode nearby.

Performance of metallic honeycomb-core sandwich beams under shock loading

Stainless steel square honeycomb core sandwich and solid monolithic beams have been subjected to high-pressure, short-duration impulses using a shock simulation technique involving high-speed impact of Al foam projectiles. The experiments have been designed to achieve two objectives: (i) to demonstrate the benefits of sandwich construction, and (ii) to assess the fidelity of dynamic finite element calculations in simulating the structural response. The results affirm that, when subjected to impulse levels representative of those associated with nearby explosions, the sandwich beams exhibit smaller displacements than the solid beams at equivalent weight. The benefit is especially large at lower impulses where the effective dynamic strength of the honeycomb core prevents crushing. The measurements and finite element simulations having greatest relevance to the shock resistance are found to correspond closely, particularly the displacements and the core crushing strains. One implication is that the dynamic finite element model has the requisite fidelity at impulse levels of interest.

Seismic wave-field observations at a dense, small-aperture array located on a landslide in the Santa Cruz Mountains, California

Abstract A rectangular (4 by 5) array of short-period three-component seismometers with 15-m spacing was deployed to record several U.S. Geological Survey calibration explosions detonated around the Santa Cruz Mountains. The array was located at a site where an earlier station had recorded frequency-dependent polarized site resonances for aftershocks of the 1989 Loma Prieta earthquake. The site is on a hillside believed to be a landslide structure, with the near surface consisting of poorly sorted sediments and weathered rocks with dipping subsurface layers. The primary objective was to explore the site effects in this complex three-dimensional soft-rock environment, characteristic of much of the Loma Prieta source region. The direct P waves from four nearby (15 to 20 km) explosions at easterly azimuths from the array show counterclockwise arrival azimuth anomalies of 30° to 50°. These deflections are attributed to the presence of more than one dipping velocity contrast beneath the array, with dips of from 10° to 50° and dip directions generally toward the south. One such boundary may correspond to the landslide slip surface, and the presence of dipping velocity contrasts underlying the site is probably responsible for some of the observed directional site resonance. A slowness vector analysis demonstrates that arrivals early in the P coda have similar azimuthal anomalies, while later scattered arrivals come from many azimuths. Particle motions indicate that the more coherent arrivals in the coda are comprised of scattered P waves and Rayleigh waves, probably associated with scattering from the rough topography in the region. The coda displays greater spatial coherency along the hill strike than down the slope, consistent with a wedge-shaped landslide. The overall wave-field spatial coherence, CCC(f, Δx), decreases with increasing frequency, f, and spatial offset, Δx, and on average can be well represented by CCC(f, Δx) = e−cfΔx, with c = 0.6 km−1 Hz−1 for the vertical P wave in the first 1-sec window. This behavior is comparable to that found for previously studied hard-rock locations.

Empirical Analysis of Digital Seismograms From A Cluster of Explosions At Regional Distances For Characterizing Multiple Explosions

SUMMARY Digital seismograms from a cluster of explosions at regional distances are analysed to investigate the similarity of seismograms with the aim of identifying possible multiple explosions. It is observed that the P wave trains from nearby explosions have considerable similarities, and the digital record of single explosions can thus be used in an empirical sense to characterize multiple explosions. By inversion and forward modelling of waveforms using the seismograms of nearby ‘single’ explosions as the pseudo-empirical Green’s function, multiple explosions where the subevents occurred at nearly the same time can be clearly recognized. The resultant ‘event time functions’ correspond to a low-resolution picture of the multiplicity, which relies on both the true ground information about the nature of the pseudo-empirical Green’s function and the resolution provided by the digital seismograms.

An extension of underwater explosive models to include the high frequency transients following pulse maxima

Direct arrival of signals produced from underwater explosions (having no reflective paths contributing to the first arrivals) exhibited high frequency pressure oscillations following the pulse maxima. Appearance is similar to the familiar ringing response of an underdamped linear system to an impulse, i.e., a decaying exponential multiplied by a sinusoid. Correlation equations for description of the main features of the pressure response to an underwater explosion are extensive in the literature. By combining these correlations with the concept of ringing, a simulation method of the pressure response of underwater explosions which includes these high frequency components has been developed for nearby explosions. An interesting method of estimating the ringing frequency from the quarter wave coincidence at the first bubble pulse maximum and a novel means of extending the number of bubble pulse oscillations into the noise level are also presented.

Practical Methods For Increasing The BlastResistance Of Existing Buildings

This paper includes the description of the recent Israeli R&D efforts (1991-1993) in researching, developing, testing and building practical strengthening measures for existing buildings, to increase their resistance against explosive effects. The strengthening measures refer to all types of building elements, sensitive to blast loadings, such as windows, doors, light roofs and weak ceilings, as constructed in normal unhardened buildings. The strengthening measures comprise additional means for improving the blast resistance of existing elements, as well as new blast-resistant elements, replacing the existing ones. The strengthening measures cost-effectiveness as well as their implementation are also discussed, in the frame of the Israeli practical experience. INTRODUCTION It was repeatedly found that normal buildings are severely damaged by blast loadings from nearby explosions. At larger distances, the most sensitive building components are the normal glass windows, which fail under low blast overpressures. At closer ranges, the doors in the building start failing, followed by light roofs and ceilings. As the blast level increases, normal brick and masonry walls fail and at close ranges the structural elements: columms, beams, etc. begin to feel the blast loadings. Following the lessons learned from observing the damages to many normal buildings in Tel Aviv, during the Iraqui Scud missiles attacks in 1991, the Israeli Home Front Command has embarked on a five-year research and development program (1991-1995) to test, develop and define strengthening measures for existing building components, to increase their blast resistance. THE TEST PROGRAM In 1991-1993 the test program included four full-scale tests series, performed in October 1991, April 1992, May 1992 and May 1993. The next full-scale tests are scheduled for June 1994. In the tests performed in 1991-1993, a total of 151 building elements were tested, as described in table no. 1. Transactions on the Built Environment vol 8, © 1994 WIT Press, www.witpress.com, ISSN 1743-3509 30 Structures under Shock and Impact TESTS DATE OCTOBER 1991 APRIL 1992 MAY 1992 MAY 1993 NUMBER OF EXPLOSIVE CHARGES

Biologic Effects of Supernovae

Estimates of the probability that nearby explosions of supernovae have occurred during the earth's history and the biologic effects of the radiation therefrom are presented. They suggest that cosmic radiation from supernovae could have caused the extinction of many exposed animals without the simultaneous extinction of plant life. This suggests that supernovae should be considered as one possible mechanism by which fauna become extinct.

CEREBRAL INJURIES DUE TO EXPLOSION WAVES— "CEREBRAL BLAST CONCUSSION"

THE CONDITION known generically in World War II as "blast concussion,"¹and discussed under synonymous titles by Fulton,²Pollock,³Fabing,⁴Aita and Kerman⁵and others, is presented here from the point of view of the organic basis of the syndrome. The first case to be described, which is one of the few of its type in which autopsy observations are on record, exemplifies the cardinal factors in this syndrome. These factors can be simplified as follows: One or more nearby explosions, causing no overt or external harm to the skull, nevertheless render the subject unconscious. After this, he has a retrograde amnesia for all but the flash of the explosion, and thereafter anterograde amnesia for a variable period. During this time he may have great motor unrest and normal or exaggerated responses to stimuli. On regaining consciousness, he has intense and intractable headache, which later