DSDS 17
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This collection showcases outputs from the third Defence and Security Doctoral Symposium, hosted at STEAM: Museum of the Great Western Railway, Swindon by Cranfield University in association with DSTL.
It is the only UK conference to provide research students and early career researchers in defence and security with an opportunity to present their work to a sector-wide audience.
Covering both technology and social sciences research, contributions include technical papers, a 3MT (three minute thesis) competition, digital images, posters and an installation competition. In addition, there are plenary talks from thought-leaders, as well as exhibition space for industry and other employers of defence and security researchers.Citation Cranfield University. (2017). 2017 Defence and Security Doctoral Symposium (DSDS17) in conjunction with DSTL and AWE: Symposium outputs (Version 13). CERES https://doi.org/10.17862/cranfield.rd.c.3924511.v13
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Browsing DSDS 17 by Type "Technical report"
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Item Open Access A Novel Fast Readout, Gamma Detector System for Nuclear Fingerprinting(Cranfield University, 2017-11-15 12:01) Giroletti, Alessia; Velthuis, J.J.; Scott, T.Technical paper presented at the 2017 Defence and Security Doctoral Symposium. In order to be effective, decommissioning of nuclear facilities as well as recovery procedures following a nuclear accident require a precise estimation of the amount, type, and topological distribution of nuclear material present at the scene. In this work we present a novel, fast readout, spectroscopy system suitable for high radiation level environment which we estimate to be 10 times faster than current deployed systems.The proposed device is based on semiconductor materials: when hit by a photon they generate electron-hole pairs, which in turn give rise to a current pulse that is proportional to the incident photon energy. This mechanism allows recognizing the incident radiation source. The proposed apparatus is composed of five semiconductor materials (Silicon, Gallium Arsenide, Uranium Dioxide, Cadmium Zinc Telluride and Diamond), which allow the cover the detection of a wide range of energies. This multi-material platform enables the precise identification of 27 isotopes which can be found after a nuclear accident or when a nuclear plant is in decommissioning. The amplifier stage uses the Amptek A250 charge sensitive preamplifier which shows low-noise (<100 electrons rms) and fast (rise time 2.5 ns) response behaviours. The readout chain consists of a MAROC3 chip and an FPGA (field programmable gate array). To prove the validity of the system, several Monte Carlo simulations, using Geant4, were performed. Simulation results have shown that gamma spectroscopy and material abundance study are possible. The system is under test at the present.Item Open Access Characterization and Micromechanical Modelling of a Temperature Dependent Hyper-viscoelastic Polymer Bonded Explosive(Cranfield University, 2017-11-15 12:01) Li-Mayer, Joanna; Williamson, D.; Lewis, D.; Connors, S.; Iqbal, M.; Charalambides, M. N.Technical paper presented at the 2017 Defence and Security Doctoral Symposium. Polymer bonded explosives (PBXs) are highly filled binary particulate composites, typically >90% volume fraction. The composites consist of a compliant matrix binder and rigid filler crystals. In order to predict the bulk composite behaviour, the polymer matrix material properties and a suitable constitutive model was determined for use in a multi-scale micromechanical finite element model.The matrix material was characterized using monotonic tensile tests at room temperature as well as small strain and large strain shear rheometric tests at different temperatures. A temperature-dependent visco-hyperelastic constitutive model combining the use of the Prony series and the Van der Waals potential was used to describe the matrix material behaviour. Material parameters at room temperature were first optimized by minimisation of the error function between the experimental and predicted behaviour (MATLAB, MathWorks). Temperature dependence for higher temperatures was then determined using time-temperature superposition. A 3D micromechanical finite element model, reconstructed from X-Ray tomographic data, was used for prediction of the composite fracture behaviour. Due to the loss of the smaller filler particles during image processing, a multi-scale hierarchical model was developed to incorporate the missing volume fraction.Item Open Access Imaging and Discrimination of High-Z Materials with Muon Scattering Tomography(Cranfield University, 2017-11-15 12:03) Frazao, Leonor; Maddrell-Mander, S.; Thomay, C.; Velthuis, J.; Steer, C.Technical paper presented at the 2017 Defence and Security Doctoral Symposium.We have developed methods to define the edges of uranium blocks embedded in concrete, and to discriminate them from different high-Z materials, using muon scattering tomography. There is a need to characterise containers of nuclear waste without having to open them. This is particularly important for legacy waste, which includes large containers with unknown materials. Muon scattering tomography uses as probes the natural occurring cosmic muons, which are highly penetrating particles. Muons undergo multiple Coulomb scattering in matter, and the amount of scattering depends on the atomic number Z of the material, so it is possible to perform imaging of different materials by measuring the incoming and outgoing muon tracks. We carried out simulations in Geant4 of uranium objects of different lengths, enclosed in concrete. These lengths were measured with a new algorithm and compared to the simulated lengths, resulting in a resolution of 0.9 mm, with a 0.2 mm error. The smallest length measured was a uranium sheet with a width of 2 mm. In the material discrimination study, a multivariate analysis was performed with the variables obtained, such as scatter angle distribution, and other correlated variables, in order to distinguish materials from different simulations with the same geometry. Cubic blocks of different sizes and materials were simulated, with sides ranging from 2 cm to 10 cm, with scanning times ranging from a few hours up to 80 hours depending on the sizes of the blocks. From these simulations, we show that it is possible to distinguish uranium blocks from lead, tungsten and plutonium blocks of the same size. The smallest blocks with a good discrimination were cubes with 2 cm side.Item Open Access Insulating Polymer Nanocomposites for High Thermal Conduction and Fire Retarding Applications(Cranfield University, 2017-12-06 14:27) Gupta, Ranjeetkumar; Huo, Dehong; Pancholi, Mehul; Njuguna1, James; Pancholi, KetanTechnical paper presented at the 2017 Defence and Security Doctoral Symposium.The possibility of combining the flexibility and light-weight of polymers with the highest insulation and dielectric permittivity of ceramics, drives the field of nanocomposites for potential commercial application. The inclusion of nano-sized insulating particles in the polymer matrix, and orienting the fillers along the direction of heat flow results in modifying the induced interfaces for effective phonon propagation. Such flexible polymer nanocomposites (PNC) offer easy workability and refined insulating effect with high thermal conductivity and fire-retardancy. Hence, opening a wider arena of applications with the advantage of their light-weight. With selective combination of the inclusions, other properties like anti-corrosion, UV-protection, etc. can be effortlessly induced. The engineering of the interfaces, is the key for dictating the desired properties at the macro-scale. Consequently, silane functionalisation of nanoparticles with designed dispersion technique was tried for achieving this purpose. This paper reports that surface modification of the nanoparticles can effectively solve the dispersion problem and reduces the electric field charge concentration at the interface. Presenting an effective way of resulting in a promising PNC suitable for various defence applications of radome technology, energy storage (like batteries), structural bodies and cables in general, etc.Item Open Access Invisible Random Media and Diffraction Gratings That Don’t Diffract(Cranfield University, 2017-11-15 12:00) King, Christopher; Horsley, S.A.R.; Philbin, T.G.Technical paper presented at the 2017 Defence and Security Doctoral Symposium. Electromagnetic waves propagating through inhomogeneous media will, in general, be scattered in multiple directions. In practical situations this is often undesirable. In this work we discuss ways to mathematically design lossless linear isotropic graded index permittivity profiles in one and two dimensions which suppress scattering. This has some counter-intuitive implications, such as disordered media exhibiting perfect transmission, and periodic gratings which don’t diffract.