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At least 145 records · Page 8Linked to original sources
PubMed2005

A simple approach for determining detonation velocity of high explosive at any loading density.

A simple empirical relationship is introduced between detonation velocity at any loading density and chemical composition of high explosive as well as its gas phase heat of formation, which is calculated by group additivity rules. The present work may be applied to any explosive that contains the elements of carbon, hydrogen, nitrogen and oxygen with no difficulties. The new correlation can easily be applied for determining detonation velocity of explosives with loading densities less than 1g/cm3 as well as greater than 1g/cm3. Calculated detonation velocities by this procedure for both pure and explosive formulations show good agreement with respect to measured detonation velocity over a wide range of loading density.

Carbon↗
PubMed2006

Determination of performance of non-ideal aluminized explosives.

Non-ideal explosives can have Chapman-Jouguet (C-J) detonation pressure significantly different from those expected from existing thermodynamic computer codes, which usually allows finding the parameters of ideal detonation of individual high explosives with good accuracy. A simple method is introduced by which detonation pressure of non-ideal aluminized explosives with general formula C(a)H(b)N(c)O(d)Al(e) can be predicted only from a, b, c, d and e at any loading density without using any assumed detonation products and experimental data. Calculated detonation pressures show good agreement with experimental values with respect to computed results obtained by complicated computer code. It is shown here how loading density and atomic composition can be integrated into an empirical formula for predicting detonation pressure of proposed aluminized explosives.

Explosions↗
PubMed2006

An investigation of the consequences of primary dust explosions in interconnected vessels.

In this article Eulerian-Lagrangian 2D computer simulations of consequences of primary dust explosions in two vessels connected by a duct are described. After an explosion in the primary vessel a propagation of hot pressurised gases to the secondary vessel, initially uniformly filled with dust particles, is simulated. The gas phase is described by the standard equations and it is coupled with the particulate phase through the drag force and the convective heat transfer. No chemical reaction is considered in the model since the objective was to model the system up to the time of ignition. The computation was performed for different lengths and diameters (heights) of the linking duct. Having analysed the results, it was concluded that the simulations agree with experimental observations in that the probability of transmission of an explosion from the primary to the secondary vessel decreases with decreasing diameter (height) and increasing length of the connecting pipeline. Snapshots of particle positions for different times are presented. The work illustrates the behaviour of the mixture in the secondary vessel: the particles tend to concentrate in clouds, and domains with no particles are observed. This may influence the explosion characteristics of the system.

Computer Simulation↗
PubMed2006

Using liquid superheating energy for a quick estimation of overpressure in BLEVEs and similar explosions.

A method is proposed for the quick estimation of the peak overpressure caused by a Boiling Liquid Expanding Vapor Explosion (BLEVE) or a similar explosion. The method is based on the use of the "superheating energy" (SE), which is the difference between the specific enthalpy of the liquid at the temperature just before the explosion and the specific enthalpy of the liquid at its saturation temperature, at atmospheric pressure. The analysis performed with a set of reference substances showed that in a BLEVE or in similar explosions, the energy converted into overpressure will range between 3.5 and 14% of SE. The comparison of the values thus obtained with experimental data from the literature shows a fairly good agreement.

Energy Transfer↗
PubMed2006

Method for preparation of fine TATB (2-5 microm) and its evaluation in plastic bonded explosive (PBX) formulations.

There is a need of fine 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) (2-5 microm) for various high explosive formulations to achieve desired mechanical strength, ease in processing and finally, provide better performance of end product. The reprecipitation method for TATB has been developed using concentrated sulfuric acid as a solvent. The reprecipitation parameters of TATB were optimized to achieve required fine TATB of particle size approximately 2-5 microm. The characteristic properties of fine TATB thus obtained have been confirmed by FTIR, DSC and TG-FTIR. The spectroscopic and thermal data obtained for fine TATB were compared with standard coarse TATB and found chemically unchanged during particle size reduction. In the present study, the preparation of fine TATB was also attempted using ultrasonication method. The fine (2-5 microm) TATB has been introduced to study in the bimodal high explosive formulations. High explosive formulations based on coarse (55 microm) and fine TATB ( approximately 2-5 microm) with 10% polyurethane were studied. It was observed that properties like bulk density (1.70 g/cm(3)), mechanical strength/compressed strength (115.9 mg/cm(2)), %elongation (6.36) were improved for fine TATB in comparison with coarse TATB ( approximately 55 microm) alone in high explosive formulations.

Calorimetry, Differential Scanning↗
PubMed2006

The rate of pressure rise of gaseous propylene-air explosions in spherical and cylindrical enclosures.

The maximum rates of pressure rise of propylene-air explosions at various initial pressures and various fuel/oxygen ratios in three closed vessels (a spherical vessel with central ignition and two cylindrical vessels with central or with top ignition) are reported. It was found that in explosions of quiescent mixtures the maximum rates of pressure rise are linear functions on total initial pressure, at constant initial temperature and fuel/oxygen ratio. The slope and intercept of found correlations are greatly influenced by vessel's volume and shape and by the position of the ignition source--factors which determine the amount of heat losses from the burned gas in a closed vessel explosion. Similar data on propylene-air inert mixtures are discussed in comparison with those referring to propylene-air, revealing the influence of nature and amount of inert additive. The deflagration index KG of centrally ignited explosions was also calculated from maximum rates of pressure rise.

Air↗
PubMed2006

Weapons of mass destruction: Overview of the CBRNEs (Chemical, Biological, Radiological, Nuclear, and Explosives).

The events of September 11, 2001, made citizens of the world acutely aware of disasters consequent to present-day terrorism. This is a war being waged for reasons obscure to many of its potential victims. The term "NBCs" was coined in reference to terrorist weapons of mass destruction, i.e., nuclear, biological and chemical. The currently accepted acronym is "CBRNE" which includes Chemical, Biological, Radiological, Nuclear, and Explosive weapons. Non-nuclear explosives are the most common terrorist weapon now in use. Nuclear and radiological weapons are beyond the scope of this publication, which focuses on the "CBEs", i.e. chemical, biological and explosive weapons. Although neurologists will not be the first responders to CBEs, they must know about the neurological effects in order to provide diagnosis and treatment to survivors. Neurological complications of chemical, biological and explosive weapons which have or may be used by terrorists are reviewed by international experts in this publication. Management and treatment profiles are outlined.

Biological Warfare↗
PubMed2004

Trauma from tire and rim explosions: A retrospective analysis.

PURPOSE: The purpose of this study is to review injuries occurring as a result of tire and rim explosions treated at a level I trauma center. MATERIALS AND METHODS: The retrospective audit evaluated the university hospital trauma database based on ICD-9 code to isolate patients sustaining tire and rim explosion injuries. A total of 12 complete patient records were derived from this search to allow determination of injuries and outcome assessments. RESULTS: Injury patterns from tire and rim explosions were categorized in terms of anatomic region, treatment and hospitalization, disposition, and outcome assessment. Maxillofacial injuries were further subdivided into specific injuries involving a total of 7 patients from this case series. CONCLUSIONS: Significant blast injuries can result from tire and rim explosions, which can often involve the maxillofacial region due to proximity to the source. Reductions in injuries have been seen since the implementation of physical safety measures by the Occupational Safety and Health Administration and the National Highway Transportation Safety Board.

Accidents, Occupational↗
PubMed2003

An exploratory approach to modeling explosive compound persistence and flux using dissolution kinetics.

Recent advances in the description of aqueous dissolution rates for explosive compounds enhance the ability to describe these compounds as a contaminant source term and to model the behavior of these compounds in a field environment. The objective of this study is to make predictions concerning the persistence of 2,4,6-trinitrotoluene (TNT) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in solid form both as individual explosive compounds and components of octol, and the resultant concentrations of explosives in water as a result of dissolution using three exploratory modeling approaches. The selection of dissolution model and rate greatly affect not only the predicted persistence of explosive compound sources but also their resulting concentrations in solution. This study identifies the wide range in possible predictions using existing information and these modeling approaches to highlight the need for further research to ensure that risk assessment, remediation and predicted fate and transport are appropriately presented and interpreted.

Azocines↗
PubMed2000

Airblast TNT equivalence for a range of commercial blasting explosives.

Results are reported from a programme of work undertaken by the UK Health and Safety Executive to investigate the airblast produced by commercial sector explosives having velocities of detonation (VoD) in the range 2000-8200 m s(-1). The data produced will be useful in evaluating the blast hazards of such explosives in industrial circumstances and also as a means of assessing post-accident damage. All of the solid explosive materials studied produced blast waves which ramped up into shock-wave form close to the point of initiation. The dependence of peak overpressure and positive phase impulse on scaled distance is presented and compared to that of TNT. The TNT equivalence (TNT(e)) technique is shown to be applicable to solid phase explosives with a wide range of VoD, although the precise values of TNT(e) vary with distance.

Air Movements↗
PubMed2000

Flixborough revisited - an explosion simulation approach.

A literature study of explosion estimation reports from the Flixborough accident was performed and commented. The results from this survey were compared to the results obtained from explosion simulations. The simulations were done with a computer model of the Flixborough plant using the EXSIM software simulation tool. The comparison showed that explosion magnitude estimates in the literature based on visual inspection are much lower than the simulated results, while the estimates based on calculations to a large degree conform with the simulations. The simulations also showed that the exact location of the ignition source does not seem to be significant for the magnitude of the explosion.

Accidents, Occupational↗
PubMed2002

Theoretical and experimental investigation into the explosive boiling potential of thermally stratified liquid-liquid systems.

The occurrence of a rapid phase transition, or so-called explosive boiling, when a cold volatile liquid comes into contact with a hot liquid or hot surface is a potential hazard in industry. This study was focused on the explosive boiling potential of thermally stratified liquid-liquid systems that result from a runaway reaction. The experimental runs were performed on both a non-reacting and a reacting system. The experimental results showed that under the analysed conditions, the cold phase was superheated but did not evaporate explosively, as the limits of superheat of the phase were not achieved. The response of the cold phase appeared to be completely controlled by the interface temperature between the hot and the cold phase. In general, based on the order of magnitude of temperature differences that result from a runaway reaction in a multi-phasic system and the fact that the system is pressurised by its own vapour pressure, the occurrence of explosive boiling under runaway conditions appears unlikely for these type of systems.

Accidents↗
PubMed2002

Passive explosion suppression by blast-induced atomisation from water containers.

The experimental findings of a combined wind tunnel and field-scale explosion study of blast-induced water release and its effect on blast suppression are reported. The release of water, and its subsequent atomisation, from containers both with open and partly enclosed surfaces, was first studied in a wind tunnel. An array of water containers were then placed at differing positions from the ignition point, together with flame acceleration obstacle arrays at fixed positions, inside a 5.1 m long by 0.3 m(2) cross-section explosion duct. The droplet size and the minimum flame speed necessary for the container array to suppress the explosion were found to depend upon the number of containers in the array and on their shape and size. One particular container array extinguished the flame when placed at any position beyond 1.7 m from the ignition point. When extinction was observed the internal over-pressure was substantially reduced and the external over-pressure completely eliminated. This study suggests a new approach toward passive explosion suppression.

Explosions↗
PubMed2003

Thermal hazard assessment of AN and AN-based explosives.

Ammonium nitrate (AN) is an essential ingredient in most fertilizers. It is also widely used in the commercial explosives industry. In this latter application, it is mostly mixed with fuel oil to form the most popular commercial explosive: ANFO. In both the fertilizer and the explosive industry, aqueous AN solutions (ANS) of various concentrations are processed. These solutions also form the basis of ammonium nitrate emulsion explosives (also called ammonium nitrate emulsions or ANE), which are produced either in bulk or in packaged form. For all these AN-based products, quantities of the order of 20,000kg are being manufactured, transported, stored, and processed at elevated temperatures and/or elevated pressures. Correspondingly, major accidents involving overheating of large quantities of these products have happened in several of these operations. In comparison, convenient laboratory quantities to investigate thermal decomposition properties are generally less than 1kg. As a result, in order to provide information applicable to real-life situations, any laboratory study must use techniques that minimize heat losses from the samples to their environment. In the present study, two laboratory-scale calorimeters providing an adiabatic environment were used: an accelerating rate calorimeter (ARC) and an adiabatic Dewar calorimeter (ADC). Experiments were performed on pure AN, ANFO, various ANS systems, and typical bulk and packaged ANE systems. The effects of sample mass, atmosphere, and formulation on the resulting onset temperatures were studied. A comparison of the results from the two techniques is provided and a proposed method to extrapolate these results to large-scale inventories is examined.

Atmosphere↗
PubMed2002

Explosives detection using prompt-gamma neutron activation and neural networks.

This work describes a study of the application of a neural network to determine the presence of explosives using the neutron capture prompt gamma-ray spectra of the substances as patterns which were simulated via Monte Carlo N-particle transport code, version 4B. After the training of the neural networks, it was possible to determine the presence of the C-4 explosive, even when they were occluded by several materials. The neural network was a powerful tool, able to recognize prompt gamma-ray explosive patterns in spite of the presence of occluding materials. Besides that, the network was able to generalize, identify the presence of explosive in cases in which it had not been trained. In that way, it was revealed as a potential tool for in situ inspection systems.

Explosions↗
PubMed2005

Evaluation of late functional results of patients treated with free muscle flaps for heel defects caused by land-mine explosions.

BACKGROUND: High-energy land-mine explosions cause extensive soft-tissue and bone defects in the heel area, which mostly require free flap coverage. In this article, the authors present the long-term functional outcomes of 72 patients who had free muscle flap reconstructions for composite heel defects caused by land-mine explosions. METHODS: The composite heel defects of 72 male patients caused by land-mine explosions were reconstructed by means of free muscle flaps. The mean follow-up was 6.5 years (range, 1 to 12 years). Each patient completed a questionnaire rating his level of satisfaction. Dynamic foot pressure distribution testing, three-dimensional motion analysis, and dynamic electromyography were performed for all patients. The data were compared with the control group of 20 volunteers. Statistical analysis was performed by Kruskal-Wallis, Mann-Whitney U, and Wilcoxon tests. RESULTS: Dynamic pressure distribution tests revealed significantly higher pressure and load in the injured feet of the patients (p < 0.05). Three-dimensional motion analysis showed restricted range of motion at the ankle joints of the injured extremity (p < 0.05). Seventeen patients were able to stand as long as the control group; the mean standing time for the others was 2.85 hours per day (range, 36 minutes to 5.32 hours). Many of the patients (71 percent) declared their satisfaction of having their own feet instead of prostheses. CONCLUSIONS: This is the longest series documenting the long-term functional results of patients injured by land mines who were treated with free muscle flaps. Reconstructive options should be preferred to amputation procedures in extensive tissue loss caused by land-mine explosion where possible.

Adult↗
PubMed2004

A photoluminescence-based field method for detection of traces of explosives.

We report a photoluminescence-based field method for detecting traces of explosives. In its standard version, the method utilizes a commercially available color spot test kit for treating explosive traces on filter paper after swabbing. The colored products are fluorescent under illumination with a laser that operates on three C-size flashlight batteries and delivers light at 532 nm. In the fluorescence detection mode, by visual inspection, the typical sensitivity gain is a factor of 100. The method is applicable to a wide variety of explosives. In its time-resolved version, intended for in situ work, explosives are tagged with europium complexes. Instrumentation-wise, the time-resolved detection, again visual, can be accomplished in facile fashion. The europium luminescence excitation utilizes a laser operating at 355 nm. We demonstrate the feasibility of CdSe quantum dot sensitization of europium luminescence for time-resolved purposes. This would allow the use of the above 532 nm laser.

Azocines↗
PubMed2001

Homicide by improvised explosive device made out of firecrackers.

Explosion is a phenomenon resulting from a sudden release of energy dissipated by: (1) blast wave; (2) translocation of objects; and (3) generation of heat. There are different types of explosive devices varying from sophisticated military bombs to simple firecrackers. These are made from various kinds of explosive materials. Sophisticated bombs are used in war and military operations to kill one's enemies, while simple firecrackers are meant for expressing joy and celebration. Here, the author reports an unusual case of homicide by the manufacture of an improvised explosive device from simple firecrackers. In India, these firecrackers are widely and freely available all over the country. The case highlights the fatal hazard resulting from easy access to these potentially dangerous devices, apart from the environmental pollution produced by their large scale use at the time of festivals in this country.

Adult↗