Penetration of a shaped charge

A shaped charge is an explosive device used to penetrate thick targets using a high velocity jet. A typical shaped charge contains explosive material behind a conical hollow. The hollow is lined with a compliant material, such as copper. Extremely high stresses caused by the detonation of the explosive have a focusing effect on the liner, turning it into a long, slender, stretching jet with a tip speed of up to 12km/s.\ud \ud A mathematical model for the penetration of this jet into a solid target is developed with the goal of accurately predicting the resulting crater depth and diameter. The model initially couples fluid dynamics in the jet with elastic-plastic solid mechanics in the target. Far away from the tip, the high aspect ratio is exploited to reduce the dimensionality of the problem by using slender body theory. In doing so, a novel system of partial differential equations for the free-boundaries between fluid, plastic and elastic regions and for the velocity potential of the jet is obtained.\ud \ud In order to gain intuition, the paradigm expansion-contraction of a circular cavity under applied pressure is considered. This yields the interesting possibility of residual stresses and displacements. Using these ideas, a more realistic penetration model is developed. Plastic flow of the target near the tip of the jet is considered, using a squeeze-film analogy. Models for the flow of the jet in the tip are then proposed, based on simple geometric arguments in the slender region. One particular scaling in the tip leads to the consideration of a two-dimensional paradigm model of a ``filling-flow'' impacting on an obstacle, such as a membrane or beam.\ud \ud Finally, metallurgical analysis and hydrocode runs are presented. Unresolved issues are discussed and suggestions for further work are presented

The Recovery of Human Remains in Weapon-Contaminated Settings: Towards Guidance for the Mine Action Community

Mine action and forensic services are critical elements in the response to humanitarian needs during and after armed conflict. Mine action operators will work to identify, mark, and eventually clear areas contaminated with landmines and explosive remnants of war (ERW). Forensic specialists and other related experts will be operational in the search for missing persons and the management of the dead by locating, recovering, and helping to identify human remains, while ensuring maximum protection, dignity of the deceased, and attention to their families.[1] These professions can often intersect in situations where human remains and explosive hazards are both present

Tetraethylene Gycol-Based Electrolytes for High Temperature Electrodeposition of Compound Semiconductors

We report an investigation of tetraethylene glycol (TEG) solutions of chloride salts (CdCl2 ,TeCl4 ,and HgCl2 ) for electrodeposition of films of CdTe and Hg1.xCdxTe, leading II-VI semiconductors. The high boiling point (314°C), below-room temperature (T) (-6°C) melting point, adequate metal chloride solubilities, and low toxicity of TEG make it a good candidate for electrodeposition at T \u3e 200°C. Such temperatures tend to activate growth of larger crystallites than with aqueous electrolytes at T\u3c 100 °C, as are advantageous in optoelectronic applications. Initial results do, indeed, indicate a dramatic increase in crystallinity with deposition temperature, especially for the CdTe films which are nearly amorphous when grown at room temperature. Hg1.xCdxTe films (x\u3c 0.5) are marginally polycrystalline when grown at room temperature but also improve in crystallinity at higher growth temperatures. There appears to be a strong decrease in film adherence and uniformity as growth temperature increases for both materials probably because the greatly increased carrier concentrations at higher temperatures increase film conductivity which, in turn, supports easy electroplating of protruding loose dendritic and/or columnar crystallites, instead of the monolayer-by monolayer growth of lower conductivity material as occurs at lower temperatures, especially in the higher bandgap/lower conductivity CdTe. The same increase in film conductivity with temperature is responsible for the decrease in the relative photosensitivity of both the CdTe and Hg1.x CdxTe with temperature. At all temperatures, the inferior adherence, uniformity, and photosensitivity as well as the superior crystallinity of Hg1.xCd xTe over that of the CdTe are also explained by its lower bandgap and higher conductivity. On balance, however, the initial results prove the utility of high temperature TEG electrolytes for electrodepositing CdTe and Hg1.xCdxTe films with much better crystallinity than for those grown at lower temperatures, notably in aqueous baths

Membrane Ballooning in Aggregated Platelets is Synchronised and Mediates a Surge in Microvesiculation:Synchronised ballooning and microvesiculation

AbstractHuman platelet transformation into balloons is part of the haemostatic response and thrombus architecture. Here we reveal that in aggregates of platelets in plasma, ballooning in multiple platelets occurs in a synchronised manner. This suggests a mechanism of coordination between cells, previously unrecognised. We aimed to understand this mechanism, and how it may contribute to thrombus development. Using spinning-disc confocal microscopy we visualised membrane ballooning in human platelet aggregates adherent to collagen-coated surfaces. Within an aggregate, multiple platelets undergo ballooning in a synchronised fashion, dependent upon extracellular calcium, in a manner that followed peak cytosolic calcium levels in the aggregate. Synchrony was observed in platelets within but not between aggregates, suggesting a level of intra-thrombus communication. Blocking phosphatidylserine, inhibiting thrombin or blocking PAR1 receptor, largely prevented synchrony without blocking ballooning itself. In contrast, inhibition of connexins, P2Y12, P2Y1 or thromboxane formation had no effect on synchrony or ballooning. Importantly, synchronised ballooning was closely followed by a surge in microvesicle formation, which was absent when synchrony was blocked. Our data demonstrate that the mechanism underlying synchronised membrane ballooning requires thrombin generation acting effectively in a positive feedback loop, mediating a subsequent surge in procoagulant activity and microvesicle release.</jats:p

How does our choice of observable influence our estimation of the centre of a galaxy cluster? Insights from cosmological simulations

Galaxy clusters are an established and powerful test-bed for theories of both galaxy evolution and cosmology. Accurate interpretation of cluster observations often requires robust identification of the location of the centre. Using a statistical sample of clusters drawn from a suite of cosmological simulations in which we have explored a range of galaxy formation models, we investigate how the location of this centre is affected by the choice of observable - stars, hot gas, or the full mass distribution as can be probed by the gravitational potential. We explore several measures of cluster centre: the minimum of the gravitational potential, which would expect to define the centre if the cluster is in dynamical equilibrium; the peak of the density; the centre of BCG; and the peak and centroid of X-ray luminosity. We find that the centre of BCG correlates more strongly with the minimum of the gravitational potential than the X-ray defined centres, while AGN feedback acts to significantly enhance the offset between the peak X-ray luminosity and minimum gravitational potential. These results highlight the importance of centre identification when interpreting clusters observations, in particular when comparing theoretical predictions and observational data.Comment: 11 pages, 6 figures, MNRAS accepte

Comparison of Aerobic Training Methods on V02 Max, Body Composition and Anaerobic Power.

Recent research has utilized intensity as a primary means to define training methods for improving aerobic capacity (VO2 max). Alternative ways of classifying training techniques must be examined to elucidate optimal practices for aerobic capacity enhancement. PURPOSE: To investigate the potential impact of various aerobic training methods on V02, body composition and anaerobic power. METHODS: Thirty-four healthy male & female subjects (18-30yrs) participated in an equated volume supervised running workout for six weeks utilizing two alternate training methods. Group one (N = 17, 21 ± 3 yr) participated in Interval Training Distance (ITD) and group two (N = 17, 21 ± 3 yr) participated in Long Slow Distance (LSD). All subjects participated in a familiarity session (FAM), a Pre-Test (T1) and a Post-Test (T2) . Each testing session consisted of a V02 Max, a 30 second Wingate and body composition assessment. Data were analyzed by a two-way ANOVA with repeated measures. Significance was set at p \u3c 0.05 and adopted throughout. RESULTS: The ITD and LSD groups experienced significant increases (p \u3c 0 .001) in VO2 max, with 9.05% (4.19 ± 4.15 ml/kg/min) and 3.18% (1.39 ± 3.67 ml/kg/min) increases respectively. A significant interaction (p \u3c 0.05) in VO2 max occurred between groups, as the ITD group displayed a 302% greater increase when compared to the LSD group. Body fat percentage significantly decreased (p \u3c 0.01) in the ITD (1.08 ± 1.90%) and LSD (1.55 ± 3.21%) groups, while a significant reduction (p \u3c 0.05) in total body weight was also observed. CONCLUSION: The findings of this study suggest that the ITD training method has a greater impact on aerobic capacity than LSD training method. However, both ITD and LSD training methods had a significant impact on aerobic capacity, body weight, and body composition

Evaluation of the incremental cost to the National Health Service of prescribing analogue insulin

Introduction Insulin analogues have become increasingly popular despite their greater cost compared with human insulin. The aim of this study was to calculate the incremental cost to the National Health Service (NHS) of prescribing analogue insulin preparations instead of their human insulin alternatives. Methods Open-source data from the four UK prescription pricing agencies from 2000 to 2009 were analysed. Cost was adjusted for inflation and reported in UK pounds at 2010 prices. Results Over the 10-year period, the NHS spent a total of £2732 million on insulin. The total annual cost increased from £156 million to £359 million, an increase of 130%. The annual cost of analogue insulin increased from £18.2 million (12% of total insulin cost) to £305 million (85% of total insulin cost), whereas the cost of human insulin decreased from £131 million (84% of total insulin cost) to £51 million (14% of total insulin cost). If it is assumed that all patients using insulin analogues could have received human insulin instead, the overall incremental cost of analogue insulin was £625 million. Conclusion Given the high marginal cost of analogue insulin, adherence to prescribing guidelines recommending the preferential use of human insulin would have resulted in considerable financial savings over the period