Investigations into the optimisation of sound suppressor geometry

Health and Safety regulations are becoming ever more stringent in order to protect us in all aspects of our daily lives to prevent noise pollution and damage to hearing. For those in the military and some areas of civilian life working with firearms there is a definite need to reduce the sound levels from them. In order to do this a working knowledge of sound moderators and suppressors is considered vital in order to assess their capabilities and optimise their performance. The project looks at a theoretical model of an integral suppressor for a modified 12 bore shotgun. The model was used to determine the area of holes through the barrel, allowing gas into the suppressor, has the greatest effect on the pressure within the suppressor. It was found that the volume of the suppressor and position of the hole through the barrel did not have such a significant effect on the pressure. The theoretical work was supported by experimental trials which confirmed the barrel hole size has a significant effect on the pressure. The experimental work also showed for the low pressure system the hole size through the baffles did not have a significant effect on the pressure. Work was carried out to establish whether current practice for proofing suppressors was sufficient. The results show that proof rounds give a lower pressure in an external suppressor than standard ammunition. Tests on improvised suppressors showed they are effective and allowed a visual analysis on suppressors. Baffles were shown to be advantageous in a suppressor configuration.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Kinetic energy less lethal weapons and their associated blunt trauma injuries

A widely used class of Less Lethal Weapon is the kinetic energy projectile. This can cause blunt trauma to the targeted person and, under certain circumstances, its use can result in permanent injury or death. The low velocity at which Less Lethal projectiles are launched results in inaccuracy of use thus increasing the possibility that non targeted areas of the body susceptible to injury by blunt trauma will be hit. This research has been focused to investigate the impact characteristics of kinetic energy Less Lethal projectiles using different masses, materials, geometries and impact velocities and how they affect the criteria for injury to the head and the thorax. Computer based models for simulating impacts and possible injuries were investigated. Hydro codes were used to predict the effect of a range of projectile masses and impact velocities for a simplified human target. Physical models were built and tested to compare with the computer predictions. A correlation between projectile mass, velocity and skin penetration was found. Research was carried out on the impact process using an instrumented projectile to measure the acceleration experienced by the projectile and the duration of acceleration for a range of target materials. A simulated head model with a displacement transducer was used to investigate the impact properties of a range of projectile geometries with the objective of identifying the probable effect on blunt trauma and the level of injury that may be sustained. The introduction of air cavities into the projectile reduced the recorded displacement as well as its acceleration whilst extending the duration of the impact. High-speed video was used to investigate the impact process between the projectile and the target using a simulated thorax. The target used was a Behind Armour Blunt Trauma (BABT) test rig originally developed to investigate behind armour blunt trauma associated with combat body armour impacted by high velocity projectiles. A wide range of projectile geometries, materials and masses were investigated to examine the probable effect on blunt trauma and the level of injury that may be sustained. The introduction of air cavities and reduction of projectile mass was found to slightly reduce the rate of displacement in the BABT rig; however the maximum displacement remained similar because of the similar masses and velocities involved.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Research activities arising from the University of Kent

In this paper I describe research activities in the field of optical fiber sensing undertaken by me after leaving the Applied Optics Group at the University of Kent. The main topics covered are long period gratings, neural network based signal processing, plasmonic sensors, and polymer fiber gratings. I also give a summary of my two periods of research at the University of Kent, covering 1985–1988 and 1991–2001

Readiness to change drinking behaviour among heavy-drinking university students in England

There is growing literature on possible ways of reducing alcohol consumption and alcohol-related harm among university students (Larimer and Cronce, 2002; Siegers and Carey, 2010). However, interventions with this aim might be made more effective by information on students’ readiness to change their drinking behaviour (Carey et al., 2007a), where an assessment of readiness to change might influence the kind of approach that is thought most likely to be successful. For example, it has been found that readiness to change moderated the effects of a brief intervention among heavy-drinking students (either brief motivational intervention or alcohol expectancy challenge) such that high readiness to change made an expectancy challenge relatively more effective in reducing drinking (Capone and Wood, 2009). This study also reported an association between higher readiness to change and greater reductions in alcohol consumption in the overall sample, thus supporting previous findings (Fromme and Corbin, 2004; Carey et al., 2007b). Although high readiness to change may increase the chances of successful brief intervention among heavy-drinking students, it has been found that, even among individuals referred to a university-based alcohol intervention programme, there was limited acknowledgement of a drinking problem or interest in changing behaviour (Caldwell, 2002; Vik et al., 2000). Such research has been conducted mainly in the USA and, with the exception of one study (Hosier, 2001), it is unknown whether a comparable lack of concern about heavy drinking is true of students in England. Moreover, there is limited understanding of the different factors associated with, and predictive of, readiness to change in heavy-drinking students. The aims of this paper are therefore (i) to assess levels of readiness to change among heavy-drinking students at universities in England, (ii) to identify variables predictive of readiness to change among heavy-drinking students and (iii) to generate hypotheses that could be tested in further research

Flow impacts on estuarine finfish fisheries of the Gulf of Carpentaria

The estuaries of Australia s tropical rivers support commercial fisheries for finfish and shellfish valued at over $220 million per annum. There are also significant tourism-related and local recreational and indigenous fisheries for icon species such as barramundi. Development of water resources in Australia's Tropical Rivers region is being considered for the Flinders, Mitchell, McArthur, Roper, Daly and Victoria catchments. Greater knowledge of the freshwater requirements of tropical aquatic ecosystems, including estuaries is crucial, so that the communities of catchments where water resource development occurs can be assured that the downstream effects of such development are considered and managed based on the best available knowledge

What are the Prospects of 3D Profiling Systems Applied to Firearms and Toolmark Identification?

This paper details a comparative pilot study of 3D (three dimensional) imaging technologies for potential application in forensic firearms and toolmark identification; as such it reviews the most up-to-date profiling systems. In particular, the paper focuses on the application of 3D imaging and recording technology as applied to firearm identification, being a specialised field within the discipline of toolmark identification. Each technology under test employs a different technique or scientific principle to capture topographic data i.e. focus-variation microscopy, confocal microscopy, point laser profilometry and vertical scanning interferometry. To qualitatively establish the capabilities and limitations of each technology investigated, standard reference samples were used and a set of specific operational criteria devised for successful application in this field. The reference standard crucially included and centred on was the National Institute of Standards and Technology (NIST) 'standard bullet'. This was to ensure that evaluation represented the practical examination of ballistic samples i.e. fired cartridge cases and bullets. It is concluded that focus-variation microscopy has potentially the most promising approach for a forensic laboratory instrument, in terms of functionality and 3D imaging performance, and is worthy of further investigation

Capturing differences in dental training using a virtual reality simulator

Virtual reality simulators are becoming increasingly popular in dental schools across the world. But to what extent do these systems reflect actual dental ability? Addressing this question of construct validity is a fundamental step that is necessary before these systems can be fully integrated into a dental school's curriculum. In this study, we examined the sensitivity of the Simodont (a haptic virtual reality dental simulator) to differences in dental training experience. Two hundred and eighty-nine participants, with 1 (n = 92), 3 (n = 79), 4 (n = 57) and 5 (n = 61) years of dental training, performed a series of tasks upon their first exposure to the simulator. We found statistically significant differences between novice (Year 1) and experienced dental trainees (operationalised as 3 or more years of training), but no differences between performance of experienced trainees with varying levels of experience. This work represents a crucial first step in understanding the value of haptic virtual reality simulators in dental education