Efficient and Featureless Approaches to Bathymetric Simultaneous Localisation and Mapping

This thesis investigates efficient forms of Simultaneous Localization and Mapping (SLAM) that do not require explicit identification, tracking or association of map features. The specific application considered here is subsea robotic bathymetric mapping. In this context, SLAM allows a GPS-denied robot operating near the sea floor to create a self-consistent bathymetric map. This is accomplished using a Rao-Blackwellized Particle Filter (RBPF) whereby each particle maintains a hypothesis of the current vehicle state and map that is efficiently maintained using Distributed Particle Mapping. Through particle weighting and resampling, successive observations of the seafloor structure are used to improve the estimated trajectory and resulting map by enforcing map self consistency. The main contributions of this thesis are two novel map representations, either of which can be paired with the RBPF to perform SLAM. The first is a grid-based 2D depth map that is efficiently stored by exploiting redundancies between different maps. The second is a trajectory map representation that, instead of directly storing estimates of seabed depth, records the trajectory of each particle and synchronises it to a common log of bathymetric observations. Upon detecting a loop closure each particle is weighted by matching new observations to the current predictions. For the grid map approach this is done by extracting the predictions stored in the observed cells. For the trajectory map approach predictions are instead generated from a local reconstruction of their map using Gaussian Process Regression. While the former allows for faster map access the latter requires less memory and fully exploits the spatial correlation in the environment, allowing predictions of seabed depth to be generated in areas that were not directly observed previously. In this case particle resampling therefore not only enforces self-consistency in overlapping sections of the map but additionally enforces self-consistency between neighboring map borders. Both approaches are validated using multibeam sonar data collected from several missions of varying scale by a variety of different Unmanned Underwater Vehicles. These trials demonstrate how the corrections provided by both approaches improve the trajectory and map when compared to dead reckoning fused with Ultra Short Baseline or Long Baseline observations. Furthermore, results are compared with a pre-existing state of the art bathymetric SLAM technique, confirming that similar results can be achieved at a fraction of the computation cost. Lastly the added capabilities of the trajectory map are validated using two different bathymetric datasets. These demonstrate how navigation and mapping corrections can still be achieved when only sparse bathymetry is available (e.g. from a four beam Doppler Velocity Log sensor) or in missions where map overlap is minimal or even non-existent

Migration from non-ovenable food contact materials at elevated temperatures.

A major problem associated with the development of complex polymeric materials for food contact applications is the potential for migration of toxic substances from the polymer to the food. This thesis investigates the transfer of migrants from non-ovenable food contact materials at elevated temperatures, and several applications where migration has occurred have been identified. Boil in the bag applications lead to exposure times of 30 - 120 minutes for complex multilayer laminates, whilst plastic kettles are repeat exposure items, and plastic 'vacuum flasks' have a potential for up to 4 hours exposure. Analytical techniques including, GC-MS, LC-MS, HPLC and UV spectroscopy have been employed to quantify the species migrating from these food contact materials into aqueous and oil simulants, and to ensure that they conform to the implemented EC restrictions. Olive oil is a stipulated EC fatty food simulant, but it is unsuitable for specific migration analyses since it contains many interfering compounds. These could not be eliminated by repeated solvent extraction, and a silicone oil was therefore substituted. In an attempt to identify the species migrating into aqueous and fatty food simulants both the final materials and also the individual components i.e. nylon, adhesive, polyethylene and polypropylene were examined separately. HPLC techniques have been developed to quantify both the known levels of antioxidants present in the polymers and also the anticipated degradation products from these materials. Typical levels of antioxidants in simulants range from <0.1 (aqueous) to 45j..lgdm-2 (oil) and <0.1 (aqueous) to 200j..lgdm" (oil) for antioxidant degradation products. In commercial boil in the bag laminates the major migrants have been shown to be derived principally from the nylon film, and the polyurethane adhesive used to fabricate the laminate. Le-MS investigations have confirmed the presence of the residual monomer Ecaprolactarn and its cyclic oligomers (up to the nonarner) in aqueous food simulants boiled in direct contact with the nylon 6. This technique has also identified the main migrants from the aliphatic and aromatic polyurethane adhesives to be residual oligomers from the polyols. Any residual isocyanates in the adhesive are converted to the corresponding amine, and colourimetric assays have determined levels between 1.1 and O.lj..lgdm". Measured, migration levels into fatty food simulants were found to be greater than in aqueous food simulants. However, none of the material examined showed an overall migration value greater than the EC limit of 10mg dm" for single sided testing. Some instances were found where the consumer was instructed to boil the dry food part of a boil in the bag meal in the same water as that used to heat the pouch containing the meat, and under these circumstances a total migration value for the laminate greater than 10mg dm-2 was measured

Implicit measures of “wanting” and “liking” in humans

Incentive Sensitization Theory (IST; e.g., Robinson and Berridge, 1993. Brain Res. Rev., 18, 291; Robinson and Berridge, 2003 Trends Neurosci., 26, 507) suggests that a common dopamine system that deals with incentive salience attribution is affected by different types of drugs. Repeated drug use will sensitize this neural system, which means that drugs increasingly trigger the experience of incentive salience or "wanting". Importantly, Robinson and Berridge stress that there is a dissociation between drug "wanting" (the unconscious attribution of incentive salience) and drug "liking" (the unconscious hedonic experience when one consumes drugs). Whereas the former plays an essential role in the development and maintenance of drug addiction, the latter does not. Although this model was based mainly on research with non-human animals, more recently the dissociation between "wanting" and "liking" has been examined in humans as well. A widely used and promising means of studying these processes are behavioral implicit measures such as the Implicit Association Test (IAT), the Approach-Avoidance Task (AAT), different types of Stimulus-Response Compatibility (SRC) tasks, and Affective Simon Tasks (AST).IST makes the clear prediction that (1) there should be a positive correlation between indices of "wanting" (e.g., drug consumption) and implicit "wanting" scores. Similarly, there should be a positive correlation between indices of "liking" (e.g., various expressions of subjective pleasure) and implicit "liking" scores; (2) there should be higher "wanting" scores in substance abusers or frequent substance users compared to non-users or infrequent users, and there should be no differences in "liking" between these groups (or even less "liking" in frequent substance users); (3) manipulations of "wanting" should affect implicit "wanting" scores whereas manipulations of "liking" should affect implicit "liking" scores. However, studies that tested these hypotheses did not produce equivocal results. To shed light on these discrepancies, we first discuss the different definitions of "wanting" and "liking" and the different tests that have been used to assess these processes. Then, we discuss whether it is reasonable to assume that these tests are valid measures of "wanting" and "liking" and we review correlational, quasi-experimental, and experimental studies that inform us about this issue. Finally, we discuss the future potential of implicit measures in research on IST and make several recommendations to improve both theory and methodology

Peter Barkby interviewed by Colin Hyde, 11 April 2017 and 3 May 2017

Peter Barkby (PB) interviewed by Colin Hyde (CH), 11 April 2017 and 3 May 2017. [00:00] PB details early life, born in Leicester and grew up in Braunstone. Called up to forces aged 18 during Second World War and left in 1947. Comments on education, attended Alderman Newton's school, left aged 16, went to work at Faire Brothers on Rutland Street, returned to job after war. [08:50] Recalls 1945 election - Parties not extremely different, grandmother very political, 'devastating' result for many people. Suggests Churchill won on personality rather than policy in 1952; country didn't feel socialist at the time, there was support for nationalisation. [19:00] Mentions married in 1948, worked at Faire Brothers up to retirement. Reflects that after war, people who had been at company a long time felt they had priority over young people returning. [24:25] Talks about transition out of forces, mentions living conditions had not improved up to 1950; hardship, little money. Mentions was a Clerk when married, worked with ex-servicemen, became Senior Clerk when Office Manager retired. [00:00] Describes work at Alexandra House, storage and distribution, raw materials, finished goods. Recalls Freeman Hardy & Willis building was burnt in bombing, was told wardens threw bombs off roof. Manufacturing done on Wimbledon Street: laces, parachute cords. Faire Brothers departmentalised production during the war to minimise bomb damage. Mention of copper dome being stolen. [08:48] Mentions after war, atom bomb meant no more movement of troops, waiting for de-mob. Asked parents in-laws to occupy his house to keep squatters out. Describes first house lived in with wife, very cold, no heating, in Western Park area, tram to work, semi-detached three bedroom, struggled with money. Mentions wife was nurse until had children, PB received poor pay at Faire Brothers, tried to move but too young, early returning troops had experience before war, but PB and others didn't. [19:35] Talks about being President of Conservative branch for short time, canvassed for elections, liked characters such as Barnett Janner, saw poorer side of Leicester through this; West Park Street. [23.50] Mentions Sir Ronald Tree was the Harborough MP, although Leicester mainly Labour. PB suggests Conservative Party lacked imagination. PB knew Ken and Thelma Bowder, helped get Ken elected after several failed candidates, Ken was solicitor for PB's purchase of house. [00:00] Talks about Young Britons Foundation, met in church rooms on Brazil Street, played games, PB was living on Fosse Road at this time. Recalls R100 airship over Leicester, watched from Fosse Road outside house. Comments on ambitions as a teenager, wanted to go to university but limited opportunities during war. Mentions father was a Fishmonger in Leicester Fish Market, had fought in First World War, few jobs on return from war, brother in law offered him job as Fishmonger, worked in this trade for rest of his life. [18:30] Talks about army training in 1943 and returning to work. Comments on discipline within business, returned to Faire Brothers in 1947, worked in textiles, shortages of raw materials, talks about coupons given. Mentions Faire Brothers were Mercers by description. [00:00] Comments on little change at Faire Brothers throughout 1950s, later became more venturesome, made arrangement with American company to develop items in shoe trade. [07:40] Talks about Leicester in 1950s, increase in population, service personnel from overseas came to live in Leicester, refugees and German ex-prisoners of war. Brief mention of untrained labour shortages in 1950s. Describe living in Western Park in 1950s, would shop in centre of Leicester at Joseph Johnson's, Fenwick's, Adderly's, Simpkin and James. Mentions cafes visited in 1950s, Winns Cafe, Turkey Cafe, The Oriental. Recalls dance halls opening again after war, PB and wife went dancing at the Bell Hotel, De Montfort Hall. Talks about Brucciani Cafe, baked their own cakes, popular with teenagers. Mentions going to cinema often, half a crown for ticket and chocolate box, Westleigh Cinema, Olympia Cinema, Roxy Cinema. [23:50] Mentions having children, first born in 1950. Little instruction given on child rearing, pregnancy wasn't spoken about. Mentions life became easier in 1960s, younger generation negotiated for greater pay in work place, increase in new small business as old industries declined. [33:50] Talks about modern conveniences, priority was furnishing house, bought three piece suite from shop in Kingston upon Thames, had it delivered to Leicester. [00:00] Mentions holidays with family, recalls first holiday abroad in France in 1960s, stayed in tent, bought new car. Would regularly holiday on east coast of England, stayed in caravan. Mentioned went on further holidays to France, visited Paris on business occasionally. [04:00] Talks about his initial involvement in local Conservative politics, friends were members, parents had been Conservatives. Mentions going canvassing on Hinckley Road and West Park Street, housing was a concern for Leicester residents, both parties wanted to improve on housing. Comments on changes witnessed to canvassing, suggests biggest change was telephones, sees this as an intrusion. [13:10] Reflects on schooling, played cricket in Western Park. [17:00] Recalls announcement of outbreak of Second World War, father made shutters for windows, listened to wireless, recalls feeling anxious seeing pictures of Warsaw bombing