China 
Africa 
Explore chapters and articles related to this topic
Improvised Explosive Devices' and Suicide Bombers
Published in Robert A. Burke, Counter-Terrorism for Emergency Responders, 2017
Hexamethylene triperoxide diamine, HMTD, is made with hydrogen peroxide; hexamine; and citric acid. Alternative formulation includes formaldehyde solution; hydrogen peroxide; and ammonium sulfate. Despite no longer being used in any military application, and despite its shock sensitivity, HMTD (Figure 7.13) remains a common homemade explosive and has been used in a large number of suicide bombings and other attacks throughout the world. For example, it was one of the components in the explosives intended to bomb Los Angeles International Airport in the 2000 millennium attack plots, it was used in the July 7, 2005 London bombings, and it was the planned explosive in the 2006 transatlantic aircraft plot. It was also used in the 2016 New York and New Jersey bombings (Figure 7.14).
Adaptive multimodal surface patterning on a cylindrical shell panel using piezoelectric actuators
Published in Mechanics of Advanced Materials and Structures, 2022
A characteristic feature of the structure under pure axial compression which exhibits unstable post-buckling response followed by restabilization is its sensitivity to external perturbations or in more general terms “shock sensitivity” [36]. These structures may exhibit dynamic jumps from their trivial configuration to intermediate buckled configurations, if externally disturbed above a characteristic axial compressive load/displacement called Maxwell load/displacement. Thus the Maxwell load/displacement represents the onset of shock sensitivity for a cylindrical shell under axial compression. No stable post-buckled configuration is generated on the cylindrical surface if the structure is subjected to an external disturbance below the Maxwell load. The dynamic jumps which are observed above the Maxwell load are thus bifurcations from the pure axial response. These bifurcations enable the structure to bypass the more energy demanding path “o - p” corresponding to the response under pure axial compression. Several such bifurcation paths exist connecting the trivial and the buckled configurations above Maxwell load. An interesting feature of these bifurcations is that the nature of the resulting patterns can be tailored by appropriately choosing the magnitude of pre-axial compressive displacements.
Enhanced reactivity by energy trapping in shocked materials: reactive metamaterials for controllable output
Published in Combustion Theory and Modelling, 2022
Donald Scott Stewart, Kibaek Lee, Alberto M. Hernández
Through the use of carefully designed numerical experiments on an explosive system that use predictive models for subcomponents, and multi-material simulation technology, we have demonstrated how one can enhance reactivity by energy trapping in regions of the reactive flow that have been previously shocked. Recent new capabilities in additive manufacture has made it possible to consider new designs we referred to as reactive metamaterials. Our simulations of baseline configurations showed that for a fixed energy input, an explosive that normally would not detonate in a fixed length with a fixed amount of energy delivered by a shock impactor, would in fact detonate when particles are embedded in the explosive matrix. This is consistent with older known results that particles can increase shock sensitivity of explosive, dating back to early experimental demonstrations of researchers like Howe et al. [1]. Since then, similar investigations of embedded inerts have been carried out. See Springer et al. [2]. However, our particles and inclusions were placed in designed patterns, of which we simulated a very limited number.