Search

A simple finite element implementation of the Mott model for fragmentation of a thin walled ring has been implemented and used to explore the effect of local variations in fracture strain around the ring. The model has successfully reproduced the fragment size distributions previously reported, which follow a characteristic "Mott distribution" form, providing sufficient (1000) simulations are run. It has been shown that this form is retained even when there are large differences in the random distribution of fracture strains or a different choice of function used to describe the fracture strain scatter. In these cases, the strain rate has a much stronger effect than fracture strain distribution the on the average fragment size and fragment distribution. However, for cases where there are a small number of local defects that strongly reduce the fracture strain at certain locations around the ring, the predicted fragment size distribution develops a bimodal character. This is also the case for large but gradual variations in fracture strain with position around the ring. The results have implications for cases where a small number of large pre-existing defects exist, or processing has led to macrozones in the microstructure. The utility of a simple fast running model to study these cases is discussed. [ABSTRACT FROM AUTHOR]

On the basis of three selected pieces from a 1991 acquisition documented by both the collector and the museum, it is shown that many of the approximately 60 puppets from Mali within the collection KOLK 17 in Lübeck are presumably set pieces from movable animal puppet stages, a special form of costume puppets that only exists in Mali. It is demonstrated that the terms ascribed to the puppets often do not do justice to the performing objects, since they only describe individual elements and do not take the actual performative action into account. Particularly in the case of those puppets that are animated by the physical movement of the puppet player--as is the case with costume puppets--a fragmentary view of the performing objects leads to an enormous loss of meaning. The complexity of moving animal puppet stages is demonstrated by a presentation of their versatile performance techniques and stage contexts. How the puppets from Mali within the collection KOLK 17 were actually played could not be conclusively clarified. Nevertheless, the objects could be extended to include possible contexts of use and meaning: these contexts are essential for further research. [ABSTRACT FROM AUTHOR]

The scientific evaluation of landscape fragmentation and connectivity is important for habitat conservation. It is strongly influenced by the spatial resolution of source maps, particularly in urban environments. However, there is limited comprehensive investigation of the spatial grain effect on urban habitat and few in-depth analysis across different urban gradients. In this paper, we scrutinize the spatial grain effects of urban green space (UGS) cover maps (derived from remote sensing imagery and survey data) with respect to evaluating habitat fragmentation and connectivity, comparing among different urban gradient scenarios (downtown, urban periphery, and suburban area) in Hangzhou, a megacity in China. The fragmentation was detected from three indices, including Entropy, Contagion, and Hypsometry. Then morphological spatial pattern analysis (MSPA) was applied for the landscape element identification. The possibility of connectivity (PC) and patch importance (dPC) were proposed for measuring the landscape connectivity based on Cores and Bridges from MSPA results. The results indicate that the farther the location is from downtown, the less sensitive the landscape element proportion to the spatial resolution. Among the three fragmentation indices, the overall hypsometry index has the lowest sensitivity to the spatial resolution, which implies this index’s broader application value. Considering connectivity, high spatial resolution maps are appropriate for analyzing highly heterogeneous urban areas, while medium spatial resolution maps are more applicable to urban periphery and suburban area with larger UGS patches and less fragmentation. This study suggests that the spatial resolution of UGS maps substantially influence habitat fragmentation and connectivity, which is critical for decision making in urban planning and management. [ABSTRACT FROM AUTHOR]

For study the energy output law of cylindrical charge with shell induced by different input energies, four different black powder masses were selected to ignite the main charge. Fragmentation degree of the shell was qualitatively analyzed by the area of holes on the witness plate and the recovered fragments mass. Through theoretical analysis, established the functional relationship between the average mass of fragments and the relative energy output of warhead, obtained how the relative energy output of charge changed with different initial energy input. The results showed that the change of input energy could lead to obvious variation in fragment characteristics, and could also control the output of charge. When the igniter mass increases from 1.55 g to 5.00 g, the relative energy output of the charge increases by 26.28%. Excessive initial input energy will destroy the shell confine in advance, resulting in a decrease in the relative energy output of charge. [ABSTRACT FROM AUTHOR]

Costa and Shrapnel ([ 2016 ]) have recently proposed an interventionist theory of quantum causation. The formalism generalizes the classical methods of Pearl ([ 2000 ]) and allows for the discovery of quantum causal structure via localized interventions. Classical causal structure is presented as a special case of this more general framework. I introduce the account and consider whether this formalism provides a causal explanation for the Bell correlations. 1   Introduction 2   Classical Causal Models 3   What's the (Quantum) Problem? 4   Quantum Causal Models: Why Bother? 5   Markov Quantum Causal Models 6   The Bell Experiment 7   Bell's Objections [ABSTRACT FROM AUTHOR]

Highlight • Non-uniform simplified model for the fragments from different axial positions of a metal shell is proposed. • New experiment method conducts the quantitative measurements shape feature and size distribution of fragments from the fragmentation of metal shells undergoing the high explosive loading. • The similarity between the fragment perforation contour and the projected contour of fragments was applied. Abstract The investigation of the fragmentation properties along the axis of a metal shell under explosive loading is valuable for understanding the fragment formation principles of a warhead. To investigate the axial fragmentation distribution of a metal shell, herein the fragmentation from different axial positions of a metal shell under single-end detonation conditions was analyzed based on the microelement method. Moreover, a corresponding simplified model for the average fragment mass was established. The fragment distribution characteristics at different axial positions and the internal features from the metal shell fragmentation was analyzed by designing an experiment for fragment segmented recovery and fragment perforation occurring in the fragmentation of a 1045 metal steel cylinder shell filled internally with 8701 high explosives. The similarity between the fragment perforation contour and the projected contour of fragments was applied to verify the accuracy of the simplified model of the fragmentation along the axial direction, which can provide an important reference for the design of warheads and the performance of protective architecture. [ABSTRACT FROM AUTHOR]

This paper presents scaling relations of the fragments mass distribution for fragmenting shell with variable thickness subjected to internal explosive loading. Available formulas usually predict the fragmentation law of shell with constant thickness, and there are few sources that describe the fragment mass distribution of shells with variable thickness, which are usually used in the Earth Penetration Warhead (EPW). In the study, shells with variable thickness fragmentation were investigated experimentally, and the fragment mass distribution was obtained by statistical analysis. Furthermore, the semi-empirical scaling relations between the fragments’ mass statistical characteristic value of shells with variable thickness and the physical parameters based on the Mott statistical distribution and Grady formula is proposed by the theoretical analysis and data analysis. The position of the initiation end and the taper of the variable thickness shell are considered in the scaling relations which has wider applicability in the study of the fragments mass distribution of shells with variable thickness subjected to internal explosive loading. [ABSTRACT FROM AUTHOR]

The article deals with the quantification of frangibility of the frangible bullets, which has high practical significance in evaluating the capability of a bullet to fragment upon impact on the target or obstacle and which allows comparison between the different types of the frangible bullets. In this article new original evaluation method of frangibility of frangible pistol bullets when hitting to the defined target is presented. [ABSTRACT FROM AUTHOR]

Possible loads on a multiple rocket launcher have been systemized and analyzed. Based on the analysis of loads, a mathematical-mechanical model has been made to describe the stability of a MLR hit by a high explosive-fragmentation projectile (HE-FRAG) in a close range. The results give the dependency of the launcher stability on explosion proximity, its typeand the explosive charge mass. The stability limit is determined by the force that can turn over the laucher and compromise the stability of projectiles inside. To simplify the given model, the kinetic energy is calculated for a projectile fragment that hits the launcher. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations of the ballistic Taylor test are used to explore correlation between the largest fragment mass and the impact energy of a projectile as well as a set of selected state variables. Flat-ended, monocrystalline, nanoscale bars collide with a rigid wall with striking velocities ranging from 0.27 km/s to 60 km/s. The investigation emphasis is on two border regions of the emerging nonlinear phenomenological model identified with two transitions: the damage-fragmentation transition and the shattering transition. In between these two nonlinear regions, the maximum fragment mass is largely inversely proportional to the impact energy, and the maximum values of the pressure, temperature, and the square of the effective strain. A reverse-sigmoid phenomenological model is proposed to capture the unifying features of this nonlinear and saturable dependence. A crystallographic orientation dependence of the damage-fragmentation transition parameters is investigated. [ABSTRACT FROM AUTHOR]

In this paper, the impact-induced fragmentation of a commercially available hot-pressed boron carbide is explored. Fragmentation has been noted previously by many authors to be important in the impact performance of advanced ceramics, and so this paper seeks to provide some of the first near-complete and detailed measurements of individual fragment size and shape distributions available in the literature. Fragment size and shapes are quantified using methods developed in previous papers by the authors, and results reveal that two distinct fragmentation mechanisms exist as a consequence of the impact failure of boron carbide: one mechanism that creates small fragments that is associated with the coalescence of fractures originating from carbonaceous defects in the material, and one that creates larger fragments that is associated with structural failure (e.g., radial and circumferential cracking). While these mechanisms are similar to those noted for uniaxial compressive failure, results presented here highlight the importance of fragment shape as a consequence of impact failure. Namely, results indicate that both blocky and shard fragments are formed during impact into a boron carbide plate. Blocky and shard fragment types span across both the small and large fragmentation mechanisms. Using Scanning Electron Microscopy, blocky fragments were found to be associated with the predominant growth of cracks parallel to the impact direction, while shard fragments contain fracture surfaces that are associated with crack growth and coalescence in a direction perpendicular to the impact direction. The shards are, thus, believed to be a consequence of structural bending. No amorphous features were found on any blocky or shard fragments observed in this study (determined using Raman Spectroscopy), suggesting brittle fracture may be the dominant mechanisms that creates the shard fragments. Altogether, the implications of these results is that one can control fragment size and shape by controlling the carbonaceous defects population in boron carbide. This should help in the design of next-generation advanced ceramics for personal protection. [ABSTRACT FROM AUTHOR]

Blasting is one of the most important operations in mining projects involving production. Inappropriate blasting pattern may lead to unwanted events such as poor fragmentation, back break, fly rock, etc., as well as strong effects on the production rate. In fact, the selection of the most suitable pattern among the previously performed patterns can be considered as a Multi Attribute Decision Making problem. In this paper, first, from various performed patterns, the efficient and inefficient ones were determined using Data Envelopment Analysis. In the second step, linear assignment was used to evaluate the efficient patterns and recognize the most suitable pattern for providing high production rate. According to the obtained results, blasting pattern with the burden of 3.5 m, the spacing of 4.5 m, the stemming of 3.8 m and the hole length of 12.1 m was selected as the most appropriate blasting pattern and suggested for the future blasting operations. [ABSTRACT FROM AUTHOR]

Opencast mining accounts for about 86% of the produced coal in India. Most of the opencast mines in the country use bulk emulsion explosives. The total consumption of explosives in India is around 550,000 tonnes annually. It has been shown that detonation velocities vary with the density of the emulsion explosive. Here we describe experiments that have been conducted to understand the influence of velocity of detonation of emulsion explosives on fragmentation of blasted muckpile over a range of densities. The density of explosives was varied from 0.6 to 1.1 g/cc which resulted in the variation of detonation velocity from 3262 to 4624 m/s. [ABSTRACT FROM AUTHOR]

Electric Arc Furnace (EAF) slags are steel slags that derive from the steel manufacturing process and are produced in large volumes (∼10% of the steel produced) worldwide, which pose an environmental threat when disposed in landfills. Their physicochemical characteristics (high density, roughness and resistance to fragmentation) favor their use in concrete products for special applications, especially where high resistance to abrasion is required and the increase concrete density is not a problem. The special concrete applications considered in this paper were industrial pavements, heavyweight concrete and pervious concrete paving blocks and all proposed products were designed in order to perform in a similar way as reference products with ordinary concrete. Then, in order to quantify the benefits arising from the utilization of an –otherwise useless– industrial by-product, a Life Cycle Assessment was carried out for each of the concrete products. One m 3 or one m 2 of concrete was selected as functional unit and a cradle-to-gate approach was followed for the LCA, including material extraction, transport and production and placement, stating the limitations and system boundaries used. Cost estimation for each of the products was also performed in order to assess their commercial viability. The results show that for industrial pavement construction, concrete with EAF slag aggregates has similar environmental load and cost with the reference concrete, while in the case of pervious paving blocks the use of EAF slag aggregates reduces the environmental load by 14% at a reduced cost, and for heavyweight concrete the environmental load is reduced by 44% at a significantly lower cost. [ABSTRACT FROM AUTHOR]

Recent research in the social sciences has explicitly addressed the challenge of bringing violence back into the center of attention. This has generated substantive progress in terms of both theoretical debate and methodological approaches. However, there is a significant lack of research applying non-reductionist methodological approaches that can, at the same time, be grounded in a theoretical approach to violence as a research subject in its own right. This focus section seeks to address this research gap by strengthening the dialogue between different bodies of literature that pursue disparate strategies of delineating "violence" as the subject of an emerging field of sociology. By synthesizing these literatures, the focus section aims to draw upon insights from social theory and recent developments in the sociology of violence on the one hand, and combine methodological approaches that transcend both micro- and macro-reductionist accounts on the other. In doing so, it offers analytical perspectives for coming to terms with one of the most conspicuous shortcomings in social scientific appraisals of violence: the tendency to treat it as a primarily moral or political problem, instead of conceiving violence as a social fact. [ABSTRACT FROM AUTHOR]

For the first time, a new series of compounds, O,O -dialkyl(diaryl) methylphosphonoselenoates, listed in Schedule 2.B.04 of the Chemical Weapons Convention was synthesized and investigated by the electron-impact (EI) and electrospray ionization (ESI) mass spectrometry. General EI and ESI fragmentation pathways were proposed and confirmed by analyzing fragment ions of deuterated analogs and by the use of density functional theory (DFT) calculations. Several novel fragmentations and rearrangements, involving an intramolecular selenono-selenolo rearrangement have been observed. The study also suggests that a previously unknown nucleophilic aromatic substitution reaction takes place during the fragmentation process. [ABSTRACT FROM AUTHOR]

The IMPACT fragmentation model has been used by The Aerospace Corporation for more than 25 years to analyze orbital altitude explosions and hypervelocity collisions. The model is semi-empirical, combining mass, energy and momentum conservation laws with empirically derived relationships for fragment characteristics such as number, mass, area-to-mass ratio, and spreading velocity as well as event energy distribution. Model results are used for several types of analysis including assessment of short-term risks to satellites from orbital altitude fragmentations, prediction of the long-term evolution of the orbital debris environment and forensic assessments of breakup events. A new version of IMPACT, version 6, has been completed and incorporates a number of advancements enabled by a multi-year long effort to characterize more than 11,000 debris fragments from more than three dozen historical on-orbit breakup events. These events involved a wide range of causes, energies, and fragmenting objects. Special focus was placed on the explosion model, as the majority of events examined were explosions. Revisions were made to the mass distribution used for explosion events, increasing the number of smaller fragments generated. The algorithm for modeling upper stage large fragment generation was updated. A momentum conserving asymmetric spreading velocity distribution algorithm was implemented to better represent sub-catastrophic events. An approach was developed for modeling sub-catastrophic explosions, those where the majority of the parent object remains intact, based on estimated event energy. Finally, significant modifications were made to the area-to-mass ratio distribution to incorporate the tendencies of different materials to fragment into different shapes. This ability enabled better matches between the observed area-to-mass ratios and those generated by the model. It also opened up additional possibilities for post-event analysis of breakups. The paper will discuss a number of the modifications that have been made to improve IMPACT and why these modifications were made. Comparisons between observational data and the IMPACT predictions will be discussed in the context of these model revisions and the overall behavior of model results. A number of future areas of investigation that were uncovered in the process of the analysis efforts will also be reviewed. [ABSTRACT FROM AUTHOR]

A robust blast inhibiting bin is the most often used device for damage blast effects suppression. In particular, a top open cylindrical bin significantly reduces a fragmentation effect resulted from a detonation of an explosive device placed inside the bin. However, reduction of blast wave overpressure and impulse by such cylindrical bins is not sufficient [1] . A reasonable alternative to endless increase of height and thickness of robust blast inhibiting bins is a development of destructible inhibitors having no solid elements in their structure and, therefore, excluding secondary fragmentation. So, the family of “Fountain” inhibitors [2,3] localizes and suppresses damaging blast effects due to multiphase working system. The present study is analyzing data obtained in testing of prototypes of new combined inhibitors. Their structure combines robust elements (bottoms, side surfaces) with elements responsible for blast loads reduction due to multi-phase working system (top and low transverse embeddings) and fairings impeding wave propagation in undesirable directions. [ABSTRACT FROM AUTHOR]

Blasting is the process of use of explosives to excavate or remove the rock mass. The main objective of blasting operation is to provide proper rock fragmentation and to avoid undesirable environmental impacts such as ground vibration, flyrock and back-break. Therefore, proper predicting and subsequently optimizing these impacts may reduce damage on facilities and equipment. In this study, an artificial neural network (ANN) was developed to predict flyrock and back-break resulting from blasting. To do this, 97 blasting works in Delkan iron mine, Iran, were investigated and required blasting parameters were collected. The most influential parameters on flyrock and back-break, i.e. burden, spacing, hole length, stemming, and powder factor were considered as model inputs. Results of absolute error (Ea) and root mean square error (RMSE) (0.0137 and 0.063 for Ea and RMSE, respectively) reveal that ANN as a powerful tool can predict flyrock and back-break with high degree of accuracy. In addition, this paper presents a new metaheuristic approximation approach based on the ant colony optimization (ACO) for solving the problem of flyrock and back-break in Delkan iron mine. Considering changeable parameters of the ACO algorithm, blasting pattern parameters were optimized to minimize results of flyrock and back-break. Eventually, implementing ACO algorithm, reductions of 61 and 58 % were observed in flyrock and back-break results, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Universitas Médica is the property of Pontificia Universidad Javeriana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As an important parameter in blasting design, charging structure directly influences blasting effect. Due to complex conditions of this blasting and excavating engineering in Jiangsu, China, the authors carried out comparative researches with coupling structure, air-decoupling structure, and water-decoupling structure. After collecting, comparing, and analyzing produced signals on blasting vibration, the authors summarized that when proportional distances are the same, water-decoupling structure can reduce instantaneous energy of blasting vibration more effectively with more average rock fragmentation and less harm of dust. From the perspective of impedance matching, the present paper analyzed influence of charging structure on blasting vibration energy, demonstrating that impedance matching relationship between explosive and rock changes because of different charging structures. Through deducing relationship equation that meets the impedance matching of explosive and rock under different charging structures, the research concludes that when blasting rocks with high impedance, explosive with high impedance can better transmits blasting energy. Besides, when employing decoupling charging, there exists a reasonable decoupling coefficient helping realize impedance matching of explosive and rock. [ABSTRACT FROM AUTHOR]

Low intensity warfare had many impact on reducing logistic costs during field operations. It influenced the development of new large caliber HE projectiles. Concerning increasing lethal efficiency at target, the focus is at development of modern projectiles with natural, embossed and preformed fragmentation. Modern natural fragmentation projectiles characterize excellent aerodynamic properties, use of high strength steel with high fragmentation characteristics and denser high energy materials. Artillery projectiles with preformed fragments are usually equipped with large amount of preformed spherical or cubical fragments made of steel or tungsten. Modern unguided rocket warheads are based on embossed fragmentation or preformed warheads concept. There are limited data about real lethal effects of these projectiles. This paper presents available data and research results of embossed fragmentation warhead 122 mm and prefragmented warhead 128 mm, which are conducted in Bosnia and Herzegovina. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Irish Studies is the property of Canadian Association for Irish Studies and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)