This study is divided in to two main parts. The first part deals with the optimization of process parameters of needle-punched non-woven fabrics for achieving maximum sound absorption by employing a Box-Behnken factorial design. The influence of fibre type, depth of needle penetration and stroke frequency on sound absorption properties were studied. These parameters were varied at three levels during experimental trials. From multiple regression analysis, it was observed that the depth of needle penetration alone was the most dominant factor among the selected parameters, which was followed by the interaction between depth of needle penetration and stroke frequency. Fibre type was the least dominant parameter affecting sound absorption. A maximum sound absorption coefficient of 47% (0.47) was obtained from the selected parameters. The results showed that for a process such as needle-punching, which is influenced by multiple variables, it is important to also study the interactive effects of process parameters for achieving optimum sound absorption. The second part of the study deals with the effect of type of natural fibre (fineness), and the blending ratio (with PET fibres) on the air permeability of the needle-punched non-woven fabrics and then it proceeds to study the effect of the air-gap, type of natural fibre (fineness) and blending ratio (with PET fibres) on sound absorption of needle-punched non-woven fabrics. These parameters are tested individually and their two way interaction (synergy) effect using ANOVA. The air-gap was varied from 0mm to 25mm with 5mm increments, three natural fibre types were used and all were blended with polyester fibres at three blending ratios for each natural fibre type. The Univariate Tests of Significance shows that all three parameters have a significant effect on sound absorption together with two two-way interactions, with the exception of the Blend Ratio × Air Gap two-way interaction which was not significant. It was found that the sound absorption improves with the increase in the air-gap size up to 15mm after which sound absorption decreased slightly with the further increase in the air-gap up to 25mm.

The use of knitting technology with advanced fibres such as glass, carbon and aramid, to produce near-net-shape fabrics has in recent years received increasing interest from the composite materials community. Knitted fabrics have the potential of being used in engineering structures with complex shapes in conjunction with a suitable liquid moulding technique, such as Resin Transfer Moulding (RTM), due to their excellent drapeability and manufacturability. During previous studies in textile reinforced composites, an intimate relationship between the fabric architecture and the damage development has been demonstrated. In this work, the quasi-static tensile loading deformation behaviour and the relation between the fabric architecture and damage development have been studied for a weft knitted glass fabric. Tensile properties have been examined and the failure mechanisms have been identified experimentally by analysing the damage process in-situ with a camera and by studying fracture surfaces using scanning electron microscopy (SEM). The acoustic emission technique was used to support the microscopic analysis. The work has investigated the tensile properties and failure mechanisms of three knitted fabric reinforced composite laminates reinforced with a Milano weft knitted glass fabric. The three composites were (i) a single layer of fabric reinforcing epoxy resin, (ii) a single knitted fabric layer sandwiched between 0° glass fibre unidirectional plies (again with the glass reinforcing epoxy resin), and (iii) the same knitted glass fabric but this time used as the reinforcement in commercially produced high fibre volume fraction composites (using the RTM technique). The variation of mechanical properties with angle (from wale to course) has been measured for the single layer of the fabric reinforcing epoxy resin by orientating the wale direction of the fabric at different angles. Mechanical properties have been measured for each angular orientation and comparisons were made between them, especially with regard to the planes of final failure. The single layer composites failed as soon as the first damage was initiated. Hence, to investigate damage accumulation, a novel technique was employed to manufacture a sandwich laminate, which consisted in placing a single knitted fabric layer between 0° glass fibre unidirectional plies. The success of this method is that the accumulation of damage in the knitted architecture was allowed to be studied and some characteristics of crack initiation and crack propagation could be related to the fabric geometry and structure. Experiments on these model transparent materials have been complemented by tests on two types of commercial knitted fabric composite manufactured by the RTM process. Characterization of these materials under tensile loading has been carried out for monotonic and cyclic loading and the results have been compared with those found for the single layer and the sandwich model material. Various failure mechanisms such as cracking at loop cross-over points, resin matrix cracking, fibre bundle debonding and tensile fracture of fibre bundles in failed specimens were observed. The behaviour of the commercial RTM specimens has been discussed in the light of the results obtained from the model single layer and sandwich specimens.

Although cryptography based remote voting protocols have been researched since 1981, most of the previous protocols [9], [5], [13] assume the existence of public bul- letins or, in other words, a publicly readable, tamper-proof, append-only log. As blockchain or distributed ledger technology (DLT) offers properties like irreversibil- ity, transparency and decentralization, it is suitable for realization of public bulletin board for the voting system. We see a gap in the research of blockchain based voting systems because there either exists work on just the protocol aspect of the voting system or the performance aspect of the blockchain. As blockchain is a general purpose tool, we believe that there lies opportunities for micro-optimizations that could specifically benefit the voting system. This ushered us to focus our effort on the performance aspect of integration of voting protocol with blockchain. Hence, in this thesis, we first introduce a homomorphic encryption based voting protocol that uses blockchain, Hyperledger Fabric (HLF), as bulletin board. The protocol is de- signed such that it leverages the transaction processing characteristics of underlying DLT. We then created an experiment where we designed a smart contract, set up a blockchain network and exposed the system to 40k concurrent voting transactions to profile the code of HLF. From the profile data, it was found that execution of cryptographic operations constitutes most of the transaction processing time. This led us to benchmark cryptographic libraries for SHA256 and digital signature algo- rithm and integrate the faster library into HLF for better performance. We also found that the transaction manager of HLF does not need read-write locks to ensure transaction isolation in special scenarios, which alleviates the performance drop due to lock contention. Altogether we were able to improve the throughput and latency of the baseline system by more than 30%. Lastly, we make a comparison between public and permissioned DLT based remote voting system and discuss the suitability of permissioned blockchain for the application of voting systems. / Graduate

Fibre reinforced polymer matrix composites are used frequently in aerospace applications. Manufacturers of aerospace components favour composites over traditional metallic alloys due to their light weight, high modulus, corrosion resistance and fatigue resistance. Advantages of composites for non-structural interior components over metallic include: ease of manufacturing for single parts of complex geometry as opposed to assemblies, cheaper manufacturing of a limited series of parts and composites greatly reduced noise, vibration and harshness. However, manufacturing interior composite components requires critical attention to detail during the preforming stages and handling of dry fabric textiles. Since these components are handmade they often yield lower profits and therefore efficient preforming is critical. Designing draping strategies for industrial liquid composite moulding processes requires a significant amount of time and testing, in simulation and also working on physical moulds. Mould and part surfaces are often defined by a number of geometric features, labelled base surfaces in the context of this thesis, which can be used to quickly probe multiple draping strategies and identify the best one. Traditionally, trial and error work is performed over a full mould surface until a working or acceptable draping strategy is found, rarely identifying the best strategy. The work in this thesis presents the initial development stages for a draping predictive tool aimed at quickly probing multiple draping scenarios in simulation prior to receiving moulds and identifying the best draping strategy for industrial non-structural aerospace composites. A multi-parameter remodelling tool – the conical frustum – was developed for uniformly identifying base surfaces through 12 geometric parameters linked into a database of in-plane shear and yarn orientations results. The development of the database is discussed, detailing Taguchi methods of experimental design used for developing linear functions from the database results, which allow interpolation of results on base surfaces that do not directly exist within the database. This thesis also includes major developments for the core draping algorithm used for linking individual base surface results together when probing draping strategies. Further investigations were performed on unique elements of in-plane shear behaviour that are encountered during draping, so that these could ultimately be considered during the development of this version of the draping algorithm whilst others may be included in future developments.

The purpose of this research was to identify nonwoven protective fabrics designed to have improved comfort properties over a fabric currently used in limited-use chemical protective clothing by using physiological and perceptual dimensions of comfort. Fabrics that are both waterproof and breathable have potential for use in chemical protective clothing by repelling liquid while allowing the diffusion of moisture vapor from the body. Microporous laminated fabrics used in chemical protective clothing allow moisture to evaporate from the body and move through the fabric while preventing liquid chemicals from coming in contact with the skin. Five fabric types were evaluated by wear testing coveralls and measuring selected physiological and perceptual responses of five subjects performing moderate-intensity exercise in thermoneutral and hot, humid environments. Physiological responses included skin temperature, body temperature, heart rate, sweat rate, and fluid loss. Perceptual responses included moisture sensation, thermal sensation, Rating of Perceived Exertion, and overall comfort. In the thermoneutral environment, results show heart rate to be the only variable affected by the different fabric types, while time effect was significant within all dependent variables. In the hot, humid environment, skin and body temperatures were significantly affected by fabric type, while time effect was significant within all variables except skin temperature. The environment effect was significant within all dependent variables except RPE and heart rate. Based on the statistical insignificance of subjects' overall comfort responses in both environments, it can be said that the differences in the physical characteristics of the fabrics may not be great enough to affect the wearer's comfort level. However, two of the four fabrics were determined to have potential for further investigation. Further research comparing experimental fabrics with fabrics used widely in industry will continue the effort of improving the comfort of limited-use protective clothing. / Master of Science

A city requires the architecture that comprises it to stitch together its urban fabric, creating connections between various, potentially disconnected, parts. Architecture mediates its surrounding public and open spaces, including plazas, streets, and parks. To fully understand a site of a future development, it is first important to understand the current and future conditions of the area within which the site is located, and in some cases its historical context as well. Only then can designers produce architecture that responds to and provides for its urban context for current and future generations. By studying the current, historic, and future contexts of Banneker Overlook, this thesis was developed by a thorough understanding of its site as a means of influencing the program and future architectural design. Banneker Overlook in its current state is a disconnected urban park in Southwest Washington, DC, originally intended as a connection point between two parts of the city. The purpose of this thesis is to reconnect the higher L'enfant Promenade with the lower Maine Avenue and Southwest Waterfront by means of the architecture and exterior public spaces. The program chosen for the site is a large public museum called the National Museum of the American People. It will "tell the story of ALL of the American People from prehistoric times to the present" (National Museum of the American People).  A large cultural building was used because of its capability to pull Washington residents and visitors to a single location coming from various, possibly disconnected, parts of the city. As a product of the site conditions, this thesis along with its site and building program became a study of creating connections of places, spaces, ideas, and people over time and space in an attempt to understand how architecture could represent this idea at both an urban and building scale. All of these ideas can be represented in our original national motto: E Pluribus Unum, "Out of Many, One." / Master of Architecture

The market for nonwoven fabrics has experienced extreme growth in recent years and is expected to double in size from 2010 to 2020. This remarkable growth can be attributed to its numerous applications, ease of manufacturing, and customizable properties such as fabric stiffness, extensibility, and composition. The lifetime of the fabric is extremely important to producers and depends strongly on its micro-mechanical properties. Previously published studies have investigated the bulk fabric properties and the constituent fiber properties. However, nothing has been done to determine the properties of individual thermo-mechanical bonds that connect the constituent fibers of the fabric together. These bonds provide the mechanical integrity of the nonwoven fabrics. This study is the first to examine individual bonds by measuring their mechanical properties via uniaxial tensile tests and by computing the basis weight and orientation of the fibers surrounding the bonds. The results demonstrate that there is a high correlation between the fiber structure around the bond and the bond mechanical properties. The amount and directions of fibers affect how the load is transmitted through the bond and distributed across the fabric. Namely, if there are a few fibers surrounding the bond, or the primary fiber direction is different from the loading direction, then the force sustained by the bond is significantly lower and the bond does not deform. Conversely, if there are many fibers in the loading direction then the bond can sustain a significantly large force and undergoes deformation. The fiber and bond deformation are also observed through microscopic images captured during the uniaxial tensile tests. Ultimately, this research details the results for an effective method to test and analyze the mechanical integrity of thermo-mechanically bond and the lifetime of the nonwoven fabrics. / Master of Science

No

<p> Forty-Three cores were collected from the region of the Killarney Igneous Complex, southeast of the town Killarney. These cores were analysed by measuring geophysical properties such as bulk susceptibility, percent anisotropy, magnetic foliation and lineation and remanence. The magnetic fabric measured indicated a regional fabric. In some areas the fabric was completely overprinted due to localised deformation. Measured remanence may make it possible to determine the effect of previous deformations; however, none was seen in this study. </p> <p> The petrological fabric was also investigated by taking thin sections perpendicular to the long axis of the core. Again it was possible to see a regional and localized deformation pattern due to reduced grain size, grain alignment and recrystallization. </p> <p> Measurements collected from the samples determined that both the magnetic fabric and petrological fabric showed indications of being near areas of greater deformational intensities. A relationship was then established between the magnetic fabric and petrological fabric on a fine scale. This relationship may aid in determining direction and extent of deformation in the rock bodies when it is not easily identifiable in the field. </p> / Thesis / Bachelor of Science (BSc)

No description available.