Dissertations / Theses on the topic 'Performance fabrics'
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Ogunleye, Christopher Olarinde. "High performance nonwovens in technical textile applications." Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/d1021011.
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The aim of this research was to establish the optimum processing conditions and parameters for producing nonwoven fabrics best suited for application in disposable and protective wear for surgical gowns, drapes and laboratory coats. Carded and crosslapped webs, of three basic weights (80, 120, and 150g/m2), from greige (unscoured and unbleached) cotton, viscose and polyester fibres, were hydroentangled, using three different waterjet pressures (60, 100 and 120 bars), on a Fleissner Aquajet hydroentanglement machine. An antibacterial agent (Ruco-Coat FC 9005) and a fluorochemical water repellent agent (Ruco Bac-AGP), were applied in one bath using the pad-dry-cure technique, to impart both antibacterial and water repellent properties to the fabrics, SEM photomicrographs indicating that the finished polymers were evenly dispersed on the fabric surface. The effect of waterjet pressure, fabric weight and type and treatment on the structure of the nonwoven produced, was evaluated by measuring the relevant characteristics of the fabrics. As expected, there was an interrelationship between fabric weight, thickness, and density, the fabric thickness and mass density increasing with fabric weight. An increase in waterjet pressure decreased the fabric thickness and increased the fabric density. The water repellent and antibacterial treatment increased the fabric weight and thickness. The antimicrobial activity of the fabrics was assessed by determining the percentage reduction in Staphylococcus aureus and Escherichia coli bacteria population. The maximum percent reduction at 24hrs contact time for both bacteria ranged from 99.5 to 99.6 percent for all the fabric types. The standard spray test ratings for the three treated fabrics ranged from 80-90 percent, whereas that of the untreated water repellent fabric was zero, while the contact angles for all the fabric types exceeded 90 degrees, indicating good resistance to wetting. It was found that the tensile strength of the fabric in the cross-machine direction was higher than that in the machine direction, for both the treated and untreated fabrics, with the tensile strengths in both the MD and CD of the treated fabrics were greater than that of the untreated fabrics, the reverse being true for the extension at break. An increase in waterjet pressure increased the tensile strength but decreased the extension at break, for both the treated and untreated fabrics. The finishing treatment decreased the mean pore size of all the fabrics, the mean pore size decreasing with an increase in fabric weight and waterjet pressure. An increase in waterjet pressure and fabric weight decreased the air and water vapour permeability, as did the finishing treatment, although the differences were not always statistically significant. The polyester fabrics had the highest water and air permeability. Hence low weight fabrics of 80 g/m2, which were hydroentangled at low water jet pressures of 60 bars, were suitable for use in this study due to their higher air and water vapour permeability as well as higher pore size distribution. These group of fabrics thus meet the requirements for surgical gowns, drapes, nurses’ uniforms and laboratory coats.
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Simile, Craig Burton. "Critical Evaluation of Wicking in Performance Fabrics." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4912.
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A method used to calculate the fundamental properties that predict the overall wicking performance of a fabric was proposed and executed. The combination of a horizontal and downward wicking test provided detailed measurements of the pertinent properties to wicking performance: capillary pressure and permeability. This method was proposed due to flaws found in standard vertical wicking tests as well as erroneous assumptions made in other wicking tests. Assumptions that capillary pressure and permeability are characteristic constants of porous structures are incorrect and will produce misleading information about that substrate. It was experimentally proven that these properties were a function of the saturation level found within the voids of a fabric. To obtain relevant capillary pressure and permeability data for a given fabric, a range of saturation levels were tested and analyzed. It was shown that saturation levels decreased as the vertical distance traveled by moisture increased. This phenomenon occurs as a result of capillary pressure within the voids dropping below the functional range needed to support flow in those voids at increasing heights. As height is increased, capillary pressure needs to also increase; therefore, only smaller radii pores will fill. Once saturation levels are known at specific heights, capillary pressure and permeability calculations were made using Darcys law and the Lucas-Washburn equation. Although this phenomenon is well known in civil engineering, it has not been widely addressed in the textile sciences, especially in its implications for wicking tests.
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Nyoni, Abraham Babs. "Liquid transport in nylon 6.6 yarns and woven fabrics used for outdoor performance fabrics." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401284.
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Meng, Xiaomin. "Influence of yarn and fabric construction parameters on the performance of cotton/dyneema fabrics for tent applications." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/8622.
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Burton, Nigel John. "Simulation and analytical performance studies of generic atm switch fabrics." Thesis, Bournemouth University, 1993. http://eprints.bournemouth.ac.uk/286/.
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As technology improves exciting new services such as video phone become possible and economically viable but their deployment is hampered by the inability of the present networks to carry them. The long term vision is to have a single network able to carry all present and future services. Asynchronous Transfer Mode, ATM, is the versatile new packet -based switching and multiplexing technique proposed for the single network. Interest in ATM is currently high as both industrial and academic institutions strive to understand more about the technique. Using both simulation and analysis, this research has investigated how the performance of ATM switches is affected by architectural variations in the switch fabric design and how the stochastic nature of ATM affects the timing of constant bit rate services. As a result the research has contributed new ATM switch performance data, a general purpose ATM switch simulator and analytic models that further research may utilise and has uncovered a significant timing problem of the ATM technique. The thesis will also be of interest and assistance to anyone planning on using simulation as a research tool to model an ATM switch.
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Yang, Dan. "Design, performance and fit of fabrics for female body armour." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/design-performance-and-fit-of-fabrics-for-female-body-armour(858cc62b-1797-4728-8ec6-e713f15f8209).html.
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This thesis focuses on the development of a new technique which enables a novel type of front panel for female body armour to be engineered, providing female contour, high level protection, and therefore comfort in wearing. The traditional cutting and stitching method can be used to form a dome shape to accommodate the bust area but it gives rise to weakness against projectile impact at the seams. A novel type of fabric with the advantage in mouldability is needed as an alternative to the conventional plain woven fabric in making female body armour without the need of cutting or folding but ease in manufacture. Dome-shaped fabric and angle-interlock woven fabric are two potential candidates. The analysis and comparisons determine the selection of the fabric with superior dome depth which is more suitable for the female body armour application. Ballistic evaluations on the selected fabric were carried out from two aspects: the overall ballistic performance investigation and the parametric study. The result provided a better understanding of kinetic energy absorption capability of single-piece selected fabrics. Additionally, the ballistic performance of fabric panels was further evaluated in the factory in order to ensure the selected fabric could achieve the commercial requirement. After the investigations of mouldability and ballistic resistance of the selected fabric, a mathematical model was created, which determines the pattern geometry for the front panel of the female body armour. This mathematical model takes the body figure size and bra size as the input, and the output is the profile of the front panel of female body armour. This work enables the speedy creation of a front panel of the female body armour in the selected fabric. This is an important advance and a novel approach for making seamless female body armour with satisfactory ballistic performance.
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Chapple, Stephen Anthony. "Improving certain high performance properties of natural fibres." Thesis, Nelson Mandela Metropolitan University, 2007. http://hdl.handle.net/10948/815.
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Cotton possesses many characteristics that make it desirable to the consumer, and this has resulted in its usage in a broad range of products. Cotton, however, is a flammable material that is easily ignited and rapidly consumed. The flame retardant treatment of cotton is, therefore, an important textile process that has received wide attention over many years. There are a number of commercial flame retardant treatments available for cotton, the most common being phosphate-based. These treatments, however, often have drawbacks or have a negative impact on the desirable properties of the fibre and the challenge still exists for designing better flame retardant products and systems that are durable and have limited impact on fibre properties. The study considers the application of the sol-gel as a coating on fabric that was pre-treated with a phosphate-based flame retardant or as a means for applying a phosphate-based flame retardant. Both treatment methods were found to be suitable for imparting flame resistance to the fabric. The effect of various phosphate-based flame retardants on flammability and fabric properties such as colour, handle and strength was investigated and it was shown that a diammonium phosphate and urea combination gave the best flame resistance. In this regard, a flame resistance was achieved with a lower amount of phosphorous than was used in similar conventional treatments. The durability of the coating to rinsing with water and soaping with a detergent was also investigated. It was found that the flame resistance was lost after rinsing or soaping but the prevention of afterglow combustion was retained. It was shown that the preparatory treatment of the fabric influenced the sol-gel coating process and the flammability of the fabric. Mercerisation and bleaching of the fabric increased the “wet pick-up” during the coating process and improved the flame resistance. The influence of various factors was also investigated in further detail. The ratio of the sol-gel components, the delay after coating prior to drying (hang time) and the curing time were investigated using an experimental design. The curing time and the ratio of components in the sol-gel were shown to have the greatest influence on fabric properties and fabric flammability. It was shown that there is a trade-off between the desired high level of fabric flame resistance and preserving the inherent properties of the fabric such as colour, handle and strength.
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Wang, Lejun. "Studies on toner properties and fabric performance properties for xerographic textile printing." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/8693.
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Kanesan, Jayaprakash, and jaykanes@gmail com. "Studies in Development and Design of Hi-Performance Yarns." RMIT University. Fashion and Textiles, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080702.141430.
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The aim of the research was to produce hollow yarn knitted fabrics with improved thermal comfort properties. Thermal comfort properties and utility properties determine the wearing comfort of textiles and the suitability of a new textile product for a particular application. Both, Thermal comfort properties such as thermal absorptiveness, thermal conductivity, air permeability and utility properties like percent stretch, spirality, bursting strength of core yarn knitted fabrics and hollow yarn knitted fabrics were assessed. A new method was proposed and discussed for producing hollow yarns at fabric stage (in this case knitted fabric) which involved the following steps: - a) Production of ring spun yarns, comprising nylon as a core and cotton as a sheath, using Ring Spinning System. b) Production of knitted fabrics of different knit structures viz., single jersey, rib and interlock using above mentioned yarn. c) Dissolution of core element i.e. Nylon into formic acid to obtain hollow yarn knitted fabrics and this hollow yarn knitted fabrics can be tailored for specific end use. The study covers comparative analysis of thermal insulation properties like thermal absorptiveness, thermal conductivity and others for core yarn knitted fabrics and hollow yarn knitted fabrics and the influence of the count of core nylon filament and the type of knit structures on the thermal properties of the fabrics. Based on the results obtained from the work, it can be stated that hollow yarn knitted fabrics offer numerous possibilities for creating fabric properties which influence their comfort of use.
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Kenber, B. "A study of the properties and performance of fabrics used in waterproof clothing." Thesis, University of Leeds, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379560.
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Huang, Gan. "Handle and comfort properties of plain weave fabrics made from high performance fibers." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/8551.
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Neilly, David G. "The development of methods for the study of properties and performance in fabric for industrial and engineering end-users." Thesis, University of Leeds, 1986. http://etheses.whiterose.ac.uk/4055/.
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This work examines the history of industrial fabrics and investigates how certain of these fabrics have developed to meet the changing demands of their end-uses. It also examines how woven textile fabrics are increasingly competing with the traditional engineering materials as new fibres and filaments allow an ever increasing range of properties; improved fabric engineering techniques are also ensuring that industrial fabrics are more suited to their end-uses. To aid fabric engineering a greater knowledge is required of fabric structure and mechanics, so developments in this field are examined. To help improve fabric research of this type, realistic physical testing methods are required both to test the usefulness of mathematical models, and to simulate conditions experienced in use. Due to certain restrictions of this type of testing, a suitable selective fabric extension measuring device is required so that problem areas such as clamping effects can be avoided. The. lack ofa suitable device to help overcome problems such as this has been a long standing difficulty, so the development of a new fabric extension gauge was one of the main objects of this work. Before such a device could be developed research first involved a survey of many of the previous extension measuring devices, however, as expected nothing suitable emerged. After considering many ideas for possible new devices, it was decided to try and develop a gauge using the relatively new material PVDF piezo polymer film. This is a thin, low modulus film which develops an electrical charge proportional to a CHANGE in mechanical stress, and which can be easily cut to any desired dimensions. Initial attempts to develop a suitable extension measuring device were not completely successful, but when suitable following circuitry was found, and a proper mounting procedure determined, the new gauge appeared very promising. When it was considered that a suitable extension measuring device was available, the next task involved the design of a biaxial tensile and shear testing machine for the new Clothworkers' Textile Hechanics and Structures Laboratory. It was considered that the availability of a suitable selective extension measuring device was of paramount importance before the design of the new tester could be considered. This apparatus was based essentially on, the proven principles of Yendell's and Bassett's testers, but a number of unique features were to be added, such as independently controlled clamps, and the ability to cycle in shear. The principles involved in the design of the mechanical hardware are described, as also are certain original recommendations which have been suggested for the second stage of the project in which the sophisticated control, measurement and analysis techniques will be developed.
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Min, Shengnan. "Engineering design of composite military helmet shells reinforced by continuous 3D woven fabrics." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/engineering-design-of-composite-military-helmet-shells-reinforced-by-continuous-3d-woven-fabrics(0cd1faec-1e5b-4d1e-9e38-4220fe8dadc8).html.
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The present research aims at engineering design of military helmet shells with continuous 3D woven fabric reinforcements for improved protection at a lighter weight and a reduced cost. The research was carried out using both the experimental and numerical methods. The results proved that the designed 3D woven wadded through-the-thickness angle interlock (TTAI) fabrics can be successfully moulded as continuous reinforcements for the doubly curved military helmet shells; therefore, costs in pattern cutting in the current composite helmet making process are eliminated. An improved ballistic performance was also demonstrated in the continuously reinforced composite structures. The wadding yarns added into the conventional TTAI fabrics enhanced the mechanical properties along the warp direction significantly. Improved composite in-plane isotropy was achieved by using the wadded TTAI fabrics as reinforcements. The locking angle method was modified based on the deformation behaviour of TTAI fabrics and was used to predict and evaluate the mouldability of both conventional and wadded TTAI structures. Mouldability factor, defined from the locking angle, assists the design and selection of continuous reinforcements that are of the appropriate mouldability. The mouldability limit of a PASGT (Personnel Armour System for Ground Troops) helmet shell was determined as 25.54. Thus, TTAI fabrics with mouldability factor no larger than this value are capable of continuously reinforcing the doubly curved shape. Ballistic tests and post-mortem examinations through ultrasonic C-scan and X-ray computed tomography (CT) demonstrated the advantages of the continuously reinforced composite in energy absorption. Up to 19.3% more of the kinetic energy was absorbed by the continuously reinforced panel through generating a delamination volume that was twice as large as that of the discontinuously reinforced one, and the delamination damages were distributed over a wider area. Under the same level of fabric mouldability and composite areal density, the panels reinforced with fewer plies of heavier fabrics performed better. The wadded TTAI reinforced composite panel demonstrated the optimal ballistic resistance by showing a 25.5% thickness increase and 55.3% penetration through the thickness. The 3D wadded fabric and 2D plain weave fabric continuously reinforced flat panels presented an equivalent ballistic performance. Meanwhile, further numerical analyses were conducted based on the digitally obtained geometry of a PASGT helmet. Although the ballistic limits varied from location to location, an equivalent ballistic limit of the helmet shell was noticed for the PASGT shell when compared to its flat counterparts. The military helmet shells reinforced by 3D wadded TTAI fabrics continuously offer improved ballistic performance. This is attributed to the preserved reinforcement continuity and the enhanced through-the-thickness properties. The research provides a novel reinforcing strategy for the construction of future composite military helmet shells.
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Tshifularo, Cyrus Alushavhiwi. "Comparative performance of natural and synthetic fibre nonwoven geotextiles." Thesis, Nelson Mandela Metropolitan University, 2017. http://hdl.handle.net/10948/21362.
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The aim of this work was to establish a range of suitable process parameters which can be utilized to produce needlepunched nonwoven fabrics for geotextile applications. Nonwoven fabrics were produced from 100% PP, a blend of 50/50% PP/kenaf and 100% kenaf fibres. The depths of needle penetration of 4, 7 and 10 mm, stroke frequencies of 250, 350 and 450 strokes/min and mass per unit area of 300, 600 and 900 g/m2 were utilized for producing the fabrics, on a Dilo loom. The effect of depth of needle penetration, stroke frequency and mass per unit area on the fabric properties, namely, tensile strength, puncture resistance, pore size, water permeability and transmissivity were analysed. In addition, the effect of chemicals, namely, 10% ammonium hydroxide (NH4OH), 10% sodium chloride (NaCl) and 3% sulphuric acid (H2SO4) solutions on degradation of the fabric was also studied. The results have shown that density, thickness and nominal weight of the needlepunched nonwoven fabrics were related to each other and they were influenced by stroke frequency, depth of needle penetration and feed rate of the needlepunching process. The increase in nominal weight of the fabrics also increases thickness and density of the fabrics. The tensile strength and puncture resistance of the fabrics increased with the increases in stroke frequency, depth of needle penetration and fabric mass per unit area. However, lower tensile strength and puncture resistance were achieved in the fabrics produced at lower stroke frequency, lower depth of needle penetration and lower mass per unit area. Bigger pores were resulted in the fabrics produced at lower stroke frequency, lower depth of needle penetration and lower mass per unit area, however, pore size decreased with increases in stroke frequency, depth of needle penetration and mass per unit area. Water permeability depends on the pore size, properties of the fibres, stroke frequency, depth of needle penetration and mass per unit area. Higher tensile strength and higher puncture resistance were achieved in the needlepunched nonwoven fabrics produced from 100% PP fibres, therefore, they are suitable for some load-bearing geotextile applications, such as reinforcement and separation. However, higher water permeability was achieved in the fabrics produced from 100% kenaf fibres, therefore, they are ideal for geotextile applications where good water permeability is required. Higher values for transmissivity were obtained in the fabrics produced from a blend of 50/50% PP/kenaf fibres, therefore they are suitable for drainage applications. The fabrics produced from a blend of 50/50% PP/kenaf fibres achieved better values of tensile strength, puncture resistance, pore size and water permeability in comparison to that produced from 100% PP and 100% kenaf fibres. However, better tensile strength and puncture resistance were achieved in the fabrics produced from 100% PP fibres and bigger pore size and higher water permeability were achieved in the fabrics produced from 100% kenaf fibres. Therefore, it can be suggested that the nonwoven fabrics produced from a blend of 50/50% PP/kenaf fibres can fulfil almost all requirements of geotextile applications, such as, filtration, separation, reinforcement and drainage. The fabrics produced from 100% PP fibres were not damaged or deteriorated when treated with all the three chemicals due to chemical inertness of polypropylene. However, the fabrics produced from a blend of 50/50% PP/kenaf and 100% kenaf fibres were damaged and deteriorated when treated with H2SO4.
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Domvoglou, Dimitra. "The influence of acid hydrolysis on the structure and performance of lyocell fibres and fabrics." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494306.
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Regenerated cellulosic fibres are known to undergo catalytic decomposition during hydrolytic treatment in Bronsted and Lewis acids. This process is taking place short after the depolymerisation or scission-reordering of the cellulosic macromolecular chains. Depolymerisation is believed to be connected with the less accessible regions of the fibrous structure and leads to a rapid reduction of the fibres' mechanical performance. Enzyme hydrolytic action is cunrrently used as a way of generating wetstate fibrillation to the surface regions of lyocell regenerated cellulosic fabrics.
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Bourgeous, Keith Norman. "Cloth media surface filtration : characterization of the performance of the needle felt and pile fabrics /." Connect to Digital dissertations. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
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Aldib, Mohanad. "An investigation of the performance of photochromic dyes and their application to polyester and cotton fabrics." Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2723.
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Six commercial photochromic dyes were applied to polyester and, to a lesser extent, cotton fabrics by different dyeing and printing methods. The photochromic performance of the dyed and printed fabrics was investigated in terms of the degree of photocoloration, background colour, fading characteristics, fatigue resistance and storage stability. A traditional aqueous-based disperse dyeing method was used to apply the photochromic dyes to polyester fabric. Solvent-based dyeing methods also were investigated for application of the photochromic dyes to polyester fabric. Solvent-based inks were formulated and applied to polyester and cotton fabrics by digital inkjet printing. The photochromic performance and colour fastness to light and washing of the photochromic fabrics were evaluated and comparison made. UV/visible spectra of the commercial photochromic dyes in a range of solvents were obtained and interpreted in terms of solvent polarity. On the basis of this study, the photochromic performance of the fabrics was improved by selecting the appropriate application solvents which transferred minimum background colours onto the fabrics. A new method of evaluating lightfastness of photochromic fabrics was established, aimed at replacing the conventional method by an instrumental method. This method was based on comparing the decrease in the degree of photocoloration of photochromic fabrics after light exposure with measured values of the colour differences of the blue wool references after fixed periods of light exposure. Two photochromic dyes were synthesized by azo coupling of a spironaphtho[2,1-b]oxazine with diazonium salts obtained from p-nitroaniline, and m-nitroaniline. Molecular modeling of the new photochromic systems, which are referred to as azospirooxazine dyes, showed that the dyes were predicted to have the potential to show photochromism. Thus, the photochromism of the azospirooxazine dyes in a range of solvents was investigated. The investigations showed that the dyes performed differently in different solvents in terms of the hue, the rate of the photochromic colour change and the colour reversibility.
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Chu, Yanyan. "Surface modification to aramid and UHMWPE fabrics to increase inter-yarn friction for improved ballistic performance." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/surface-modification-to-aramid-and-uhmwpe-fabrics-to-increase-interyarn-friction-for-improved-ballistic-performance(d6e35803-9a2c-478a-a96d-a658292f8890).html.
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Manufacturing more reliable and lighter body armour using the fabrics with high-performance fibres is the development trend of ballistic protection device. However,increasing the reliability of the body armour normally needs to increase weight. Thisinvestigation aims to develop better ballistic performance of body armour withoutaffecting weight. Inter-yarn friction in quasi-static state in fabrics constructed for bodyarmour is one of the important factors affecting ballistic performance. This researchfocuses on increasing inter-yarn friction by surface modification methods for superiorballistic protection of woven fabrics. Finite element (FE) simulation is employed toanalyse the effects of inter-yarn friction on ballistic performance theoretically. BothAPPCVD and sol-gel methods are used to achieve the purpose of practically increasinginter-yarn friction. Ballistic experiments are conducted to evaluate ballistic performanceof the fabrics with different levels of inter-yarn friction after treatments. Through both numerical and experimental investigation, it is confirmed that increasinginter-yarn friction in quasi-static state can improve ballistic performance of fabrics. Theoverall energy absorption will be increased with the increase of inter-yarn frictionbecause higher inter-yarn friction generates higher resistance to the projectile, makesfabric structure more stable, leads to more involvement of the secondary yarns andincreases both KE and FDE percentages. Moreover, higher levels of inter-yarn frictionwill flatten the trauma and make the fabric response more globalised owing to the lesstransverse deflection ability. However, over high inter-yarn friction is counterproductivebecause of stress concentration on the primary yarns. For the surface modification, one of the aramid yarns, Twaron® yarn and one of theUHMWPE yarns, Dyneema® yarn, and their fabric products are used as the substrates. SEM analyses are used to characterise the morphology changes. Both FTIR and EDXanalyses are conducted to identify the coated substance. Based on coefficients of friction test and yarn pull-out test, the APPCVD treatment and sol-gel treatment have been proved as two effective ways to increase inter-yarn friction and at the same time the tensile properties of the yarns and the weight are almost unaffected. Moreover, sol-gel treatment has been established as an effective method for improvingballistic performance without significant weight increase, where the energy absorption ofthe Dyneema® fabric can be increased by 6.74%, and the trauma depth can be decreased by16.99% for Twaron® fabric panel and by10.73% for Dyneema® fabric panel.
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Abounaim, Md. "Process development for the manufacturing of flat knitted innovative 3D spacer fabrics for high performance composite applications." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-65067.
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Innovative 3D spacer fabrics made from individual planes and connecting layers present great potential as complexly shaped textile preforms in lightweight composite applications. As one of the most flexible textile manufacturing methods, flat knitting enables the production of intricately shaped textile structures. The major advantages coupled with flat knitting techniques include the ability to produce multi-layer reinforcements, a diminishing waste, reducing production time and near-net shaping. This research includes the further development of flat knitting technology and the manufacturing processes of innovative, customized 3D spacer fabrics for high performance composite applications. Novel 3D spacer fabrics have been developed in different geometries using glass-polypropylene commingled hybrid yarns for complex shaped thermoplastic composite components. Reinforcement yarns have been integrated into spacer fabric structures with up to 4 reinforcement layers to improve mechanical performance. Furthermore, the successful addition of “sensor networks” created by integrating functional yarns into the 3D spacer fabrics could be used for structural health monitoring. Innovative integration concepts, which accommodate different positioning of the reinforcement yarns into the knit structures, can be used to adjust the mechanical properties of the finished knit composites. Moreover, the tensile properties have been accurately predicted based on the mathematical models formulated. The developed flat knitted 3D spacer fabrics are very promising for applications in lightweight composites, mechanical engineering, protective textiles, civil engineering and architectural designsInnovative 3D-Spacer Fabrics bestehend aus individuellen Deckflächen und Verbindungsstegen bieten ein großes Potential als komplex geformte textile Halbzeuge für Leichtbauverbundwerkstoffanwendungen. Mit Hilfe des Flachstrickens, welches einer der flexibelsten textilen Herstellungsprozesse ist, lassen sich komplex geformte textile Strukturen herstellen. Belastungsgerechte Verstärkungen, Abfallreduzierung, endkonturnahe Fertigung sind nur einige der großen Vorteile der modernen Flachstricktechnik. Die Forschungsarbeit beinhaltet die Entwicklung der Flachstricktechnologie und des Herstellungsprozesses für innovative 3D-Spacer Fabrics für Hochleistungsverbundwerkstoffe. Neuartige 3D-Spacer Fabrics wurden in unterschiedlichen Geometrien entwickelt, in dem Glas-/ Polypropylen Commingling-Hybridgarn für komplex geformte thermoplastische Verbundwerkstoffkomponenten eingesetzt wird. Verstärkungsfäden wurden für hochmechanische Belastungen in die Spacer-Fabric-Strukturen in bis zu 4 Verstärkungschichten integriert. Die erfolgreiche Umsetzung und Entwicklung von Sensornetzwerken durch die Integration von funktionalen Fäden in die 3D-Spacer Fabrics kann für die strukturelle Zustandsüberwachung genutzt werden. Die innovativen Integrationskonzepte erlauben die differenzierte Orientierung von Verstärkungsfäden in den Gestrickstrukturen, wodurch eine starke Beeinflussung der mechanischen Eigenschaften der Gestrickverbundwerkstoffe herbeigeführt wird. Darüber hinaus wurden die Zugeigenschaften basierend auf den entwickelten mathematischen Modellen vorhergesagt. Die entwickelten flachgestrickten 3D-Spacer Fabrics sind sehr vielversprechend beispielweise für die Anwendung in Leichtbauverbundwerkstoffen, im Maschinenbau, in Schutztextilien, im Bauingenieurwesen und Architekturdesign
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Umoren, U. "Assessment of the life expectancy and environmental performance of polylactic acid compared to cotton and polyethylene terephthalate fabrics." Thesis, Coventry University, 2016. http://curve.coventry.ac.uk/open/items/711e912a-886e-4903-b440-03715a63d6b5/1.
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The need to satisfy the increasing global demand for textile and clothing material due to population growth and changes in fashion trends have led to the manufacturing of short life span textiles. Current fabrics such as cotton and polyethylene terephthalate (PET) all have deep environmental impacts. This study examines Polylactic acid (PLA) fabric derived from corn as a contending replacement for cotton and polyethylene terephthalate. The use phase has been identified as the dominant contributor to environmental impacts and consequently this research has focused on how the laundry regime (wash performance) affects the life expectancy and the mechanical properties of PLA, PET and Cotton. This study excludes daily wear, dirt and stains. By testing the constituent fabrics after each laundry regime, the results showed a more significant level of impact on cotton than PLA fabric in different laundry treatments with or without softener. There was no effect on PET. The load-extension behaviour showed that PLA and cotton withstood ten laundry cycles before showing any significant signs of damage; however, PET fabric retained its load-extension behaviour beyond 50 laundry cycles. From a practical standpoint, the result of this study suggests that tumble-drying should be avoided; however, the use of softeners during the laundry and air-drying seems to provide stability for PLA and PET fabrics. The influence on the cotton fabric was more from the drying process than the use or absence of softener, buttressing the fact that tumble-drying should be avoided if possible. The life expectancy of PLA fabric showed a lower lifetime (35 washes/lifecycle) compared to PET and cotton (42 and 43 washes/lifecycle respectively). With these results, a comparative lifecycle assessment was conducted during the life expectancy and after a typical school t-shirt use of 75 laundry regimes, PLA offered environmental benefits compared to PET and Cotton. The result also revealed that the environmental impact of cotton decreased by 2%, PET decreased by about 1.2% while PLA increased by 3% when the laundry lifetime was increased to 75 wash cycles. The results obtained in this study showed that enhancing the fabric to increase its laundry lifetime does not automatically lessen the environmental impacts. Nevertheless, it has proven that even a small rise in the lifetime of PLA fabric can make it comparable and competitive with PET and cotton. In addition, the similarities in properties with PET makes PLA a valuable substitute, with a sustainable low environmental burden. In comparison to cotton (Energy Demand 36.5%, Water Consumption 53%, and Global warming potential Contribution 43%), PLA (Energy Demand 28.5%, Water Consumption 21% and Global warming potential Contribution 22%), demonstrates a better alternative in all aspects and is recommended as a suitable replacement due to its potentially low water and energy use, and CO2 emission.
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Orwin, Claire Nicola. "An evaluation of the performance of an optical measurement system for the three-dimensional capture of the shape and dimensions of the human body." Thesis, De Montfort University, 2000. http://hdl.handle.net/2086/4908.
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As the clothing industry moves away from traditional models of mass production there has been increased interest towards customised clothing. The technology to produce cost effective customised clothing is already in place however the prerequisite to customised clothing is accurate body dimensional data. In response, image capture systems have been developed which are capable of recording a three-dimensional image of the body, from which measurements and shape information may be extracted. The use of these systems for customised clothing has, to date, been limited due to issues of inaccuracy, cost and portability. To address the issue of inaccuracy a diagnostic procedure has been developed through the performance evaluation of an image capture system. By systematically evaluating physical and instrumental parameters the more relevant sources of potential error were identified and quantified and subsequently corrected to form a `closed loop' experimental procedure. A systematic test procedure is therefore presented which may be universally applied to image capture systems working on the same principle. The methodology was based upon the isolation and subsequent testing of variables that were thought to be potential sources of error. The process therefore included altering the physical parameters of the target object in relation to the image capture system and amending the configuration and calibration settings within the system. From the evaluation the most relevant sources of error were identified as the cosine effect, measurement point displacement, the dimensional differences between views and the influence of the operator in measurement. The test procedure proved to be effective in both evaluating the performance of the system under investigation and in enabling the quantification of errors. Both random and systematic errors were noted which may be quantified or corrected to enable improved accuracy in the measured results. Recommendations have been made for the improvement of the performance of the current image capture system these include the integration of a cosine effect correction algorithm and suggestions for the automation of the image alignment process. The limitations of the system such as its reliance on manual intervention for both the measurement and stitching processes, are discussed, as is its suitability for providing dimensional information for bespoke clothing production. Recommendations are also made for the creation of an automated test procedure for testing the performance of alternative image capture systems, which involves evaluating the accuracy of object replication both for multiple and single image capture units using calibration objects which combine a range of surfaces.
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Yu, Lianghong. "Performance of a ATM Lan switching fabric." Master's thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/26109.
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This thesis provides a focus on the architecture of a high-speed packet switching fabric and its performance. The switching fabric is suited for existing transparent protocols, based on Asynchronous Transfer Mode (ATM) technology and standards in an environment of Local Area Network (LAN). A high-speed switching fabric architecture which adopts Time Division mode and bases on a shared medium approach is proposed. This is an architecture for nonblocking performance, no congestion and high reliability. Its principle for performance is a method of sequentially scheduling the inputs and the transferring of bits in parallel. To study the performance of the switching fabric architecture one uses OPNET communication simulation software. Some parameters including the throughputs, the transfer (the switching fabric) delay, the switching overflow and the packet size in the buffer (the input buffer and the output buffer) are implemented through the simulation. And finally, an analysis for the results of the simulation for local ATM IDS fabric architecture is discussed. The results display an architecture that provides a rational design with some expected characteristics.
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Ranadive, Adit Uday. "Virtualized resource management in high performance fabric clusters." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54241.
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Providing performance and isolation guarantees for applications running in virtualized
datacenter environments requires continuous management of the underlying physical
resources. For communication- and I/O-intensive applications running on such platforms,
the management methods must adequately deal with the shared use of the high-performance
fabrics these applications require. In particular, new classes of latency-sensitive and
data-intensive workloads running in virtualized environments rely on emerging fabrics
like 40+Gbps Ethernet and InfiniBand/RoCE with support for RDMA, VMM-bypass and
hardware-level virtualization (SR-IOV). However, the benefits provided by these technology
advances are offset by several management constraints: (i) the inability of the hypervisor
to monitor the VMs’ usage of these fabrics can affect the platform’s ability to provide
isolation and performance guarantees, (ii) the hypervisor cannot provide fine-grained
I/O provisioning or perform management decisions for VMs, thus reducing the degree of
consolidation that can be supported on the platforms, and (iii) without such support it
is harder to integrate these fabrics into emerging cloud computing platforms and
datacenter fabric management solutions. This is made particularly challenging for
workloads spanning multiple VMs, utilizing physical resources distributed across multiple
server nodes and the interconnection fabric.
This thesis addresses the problem of realizing a flexible, dynamic resource management
system for virtualized platforms with high performance fabrics. We make the following key
contributions:
(i) A lightweight monitoring tool, IBMon, integrated with the hypervisor to monitor VMs’
use of RDMA-enabled virtualized interconnects, using memory introspection techniques.
(ii) The design and construction of a resource management system that leverages IBMon
to provide latency-sensitive applications performance guarantees. This system is built
on microeconomic principles of supply and demand and can be deployed on a per-node
(Resource Exchange) or a multi-node (Distributed Resource Exchange) basis. Fine-grained
resource allocations can be enforced through several mechanisms, including CPU capping
or fabric-level congestion control.
(iii) Sphinx, a fabric management solution that leverages Resource Exchange to orchestrate
network and provide latency proportionality for consolidated workloads, based on
user/application-specified policies.
(iv) Implementation and experimental evaluation using InfiniBand clusters virtualized with
the Xen or KVM hypervisor, managed via the OpenFloodlight SDN controller, and using
representative data-intensive and latency-sensitive benchmarks.
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Chen, Xin. "High temperature performance of glass fabric/polyimide composites." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/11165.
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Koh, Eunjoo. "Influence of hydroentangled fabric structure on wiping performance." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522955.
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Mbwette, Tolly Salvator Augustin. "The performance of fabric protected slow sand filters." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47566.
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Duewer, Bruce Eliot. "A Low-Power, High Performance MEMS-based Switch Fabric." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20011015-145122.
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DUEWER, BRUCE ELIOT. A Low-Power, High Performance MEMS-based Switch Fabric. (Under the direction of Paul D. Franzon.)An approach with the potential for building large low power high performance crossbar networks is presented. Thin film polysilicon MEMS devices are developed to provide crosspoints. These devices are vertically moving plates that serve as variable capacitors. Addressing of large arrays using 2n rather than n-squared lines despite no active circuitry on the MEMS chips is facilitated by bistable device operation. Derivations of equations for bistable device operation are presented. Low power operation is possible as the devices are electrostatically controlled and are stationary except during reconfiguration. Early devices are fabricated using the MUMPS process. The bistability and array addressability properties are demonstrated. The substrate effect on device operation is measured and modeled; methods for utilizing the substrate effect to tune device operation are presented. Later devices are fabricated using the SUMMiT process. Changes in the SUMMiT design rules to increase allowable vertical motion range are proposed and designs using them fabricated. S-parameter characteristics of devices in both `on' and `off' states are measured. Addition of metallization after chip fabrication and release is necessary to lower the resistance of interconnect. A self masking method for applying this metallization allowing for decreased resistance at line crossings is proposed. This method is tested using each of sputtering and evaporation as the deposition technique for a gold and adhesion layer stack. Effectiveness of the method with each technique is evaluated. Chips suitable for providing high voltage control for large MEMS arrays are fabricated in a 2um feature size CMOS process. Architectures suitable for building large crossbars employing variable capacitor arrays are discussed. Optimization of hybrid CMOS/MEMS Clos arrays on the basis of criteria other than minimization of crosspoints is discussed. Array sizings to provide 192*192 and 256*256 crossbars are presented, and software examples for sizing and controlling Clos networks are provided. Evaluation of the suitability of the MEMS devices developed for use as digital or broadband crosspoints is evaluated, and potential future directions are proposed.
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Silver, Robert Kenneth. "The compaction and permeability performance of mineral landfill liners." Thesis, University of the West of Scotland, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309630.
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Poellabauer, Christian. "Q-Fabric: System Support for Continuous Online Quality Management." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-04082004-134256/unrestricted/poellabauer%5Fchristian%5F200405%5Fphd.pdf.
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Thesis (Ph. D.)--Computing, Georgia Institute of Technology, 2004.Pande, Santosh, Committee Member ; Pu, Calton, Committee Member ; Schwan, Karsten, Committee Chair ; Franke, Hubertus, Committee Member ; Eisenhauer, Greg, Committee Member. Vita. Includes bibliographical references (leaves 158-169).
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Jack, Richard. "Building diagnostics : practical measurement of the fabric thermal performance of houses." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/19274.
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This thesis is concerned with measuring the fabric thermal performance of houses. This is important because the evidence shows that predictions of performance, based upon a summation of expected elemental performance, are prone to significant inaccuracy and in-situ performance is invariably worse than expected the so-called performance gap . Accurate knowledge of the thermal performance of houses could cause a shift in the way that houses are built, retrofitted and managed. It would enable quality-assurance of newly-built and retrofitted houses, driving an improvement in the energy performance of the housing stock. The current barrier to achieving these benefits is that existing measurement methods are impractically invasive for use on a mass-scale. The aim of this research is to address this issue by developing non-invasive fabric thermal performance measurement methods for houses. The co-heating test is currently the most used method for measuring whole-house fabric thermal performance; it is used to measure the Heat Loss Coefficient (HLC) of a house, which is a measure of the rate of heat loss with units of Watts per degree Kelvin. It has been used extensively in a research context, but its more widespread use has been limited. This is due to a lack of confidence in the accuracy of its results and the test s invasiveness (the house must be vacant for two weeks during testing, which has so far been limited to the winter months, and testing cannot be carried out in newly-built houses for a period of approximately one year due to the drying out period). To build confidence in the results of co-heating testing, the precision with which test results can be reported was determined by the combination of a sensitivity analysis to quantify measurement errors, and an analysis of the reproducibility of the test. Reproducibility refers to the precision of a measurement when test results are obtained in different locations, with different operators and equipment. The analysis of the reproducibility of the test was based upon a direct comparison of seven co-heating tests carried out by different teams in a single building. This is the first such analysis and therefore provides a uniquely powerful analysis of the co-heating test. The reproducibility and sensitivity analyses showed that, provided best practise data collection and analysis methods are followed, the HLC measured by a co-heating test can be reported with an uncertainty of ± 10%. The sensitivity analysis identified solar heat gains as the largest source of measurement error in co-heating tests. In response, a new approach for co-heating data collection and analysis, called the facade solar gain estimation method, has been developed and successfully demonstrated. This method offers a clear advancement upon existing analysis methods, which were shown to be prone to inaccuracy due to inappropriate statistical assumptions. The facade method allowed co-heating tests to be carried out with accuracy during the summer months, which has not previously been considered feasible. The demonstration of the facade method included a direct comparison against other reported methods for estimating solar gains. The comparison was carried out for co-heating tests undertaken in three buildings, with testing taking place in different seasons (winter, summer, and spring or autumn) in each case. This comparison provides a unique analysis of the ability of the different solar gain estimation methods to return accurate measurements of a house s HLC in a wide variety of weather conditions. Building on these results, a testing method was developed: the Loughborough In-Use Heat Balance (LIUHB). The LIUHB is a non-invasive measurement method, designed and tested in this study, which can measure the HLC of a house with an accuracy of ± 15% while it is occupied and used as normal. Measurements of energy consumption and internal temperature are discreetly collected over a period of three weeks, and combined with data collected at a local weather station to inform an energy balance, from which the HLC is calculated. This low impact monitoring approach removes the barriers to fabric thermal performance testing on a mass scale. The LIUHB has been successfully demonstrated in several comparative trials versus a baseline measurement provided by the co-heating test. The trials have included the application of extreme examples of synthetic occupancy conditions, testing in an occupied house, and quantification of the effects of a retrofit. Subject to further validation, the LIUHB has the potential to deliver many of the benefits associated with mass-scale measurement and quality assurance of housing performance.
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Martin, Boris. "Etudes expérimentales de l’influence des paramètres de conception des renforts NCF unidirectionnels sur leurs propriétés de transport et leurs performances mécaniques." Thesis, Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0084.
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L'augmentation des dimensions des éoliennes est nécessaire pour réduire le coût du rendement énergétique des parcs éoliens. L'optimisation de ces structures est liée aux renforts fibreux qu'elles utilisent. La rigidité des pâles d'éoliennes provient des longerons en composites monolithiques mis en forme à partir de renforts NCF (« Non-Crimp Fabrics ») unidirectionnels et de résine thermodurcissable. Les renforts se présentent sous forme d'empilement de deux couches (0° et+/- 80°) cousues dans l'épaisseur par un fil polyester. La structure fibreuse, contrôlée par les paramètres de conception, influence les liens de causes à effets entre les paramètres de conception et les performances du renfort et du composite. Il est donc nécessaire d'optimiser les composites pour leur application. Trois paramètres de conception sont étudiés pour établir ces liens : la longueur de couture, le dessin de couture et la masse linéique de la trame. Ces liens sont dévoilés par la mise en relation de données morphologiques issues d'analyse d'images du renfort sec et du composite avec les propriétés macroscopiques déterminées par le biais de moyens expérimentaux. Ces derniers permettent notamment de déterminer le tenseur de perméabilité hydraulique des renforts ainsi que les propriétés élastiques des composites. Il apparait que chacun des paramètres étudiés influence l'hétérogénéité des composites. Cette caractéristique est favorable pour le procédé d'infusion mais affecte la tenue en fatigue des longerons. L'optimisation des renforts NCF pour leur application requiert donc d'établir un compromis. Une autre solution consisterait à permettre une évolution de la morphologie du composite lors de la mise en forme, pour passer d'un renfort sec hétérogène à un composite homogène en terme de fraction volumique de fibreThe energetic pricing of windmills involves the production cost of wind turbines and theirlifespan. Increasing the performances of these structures comes with an increase of the bladesdimensions. The spar caps of the latters, providing the strength to the blades, are made ofunidirectional glass fiber reinforcement known as NCF (Non-Crimp Fabrics). They involve two layers ofspecific orientations (0° and +/- 80°) stitched together. The architecture formed by the reinforcement isdependent on the design parameters which control the performance, on the fabric during the infusionprocess, and on the composite in the final structure. Therefore, the optimization of the NCF for thewindmill application is controlled by the design parameters. Three parameters (the stitch length, thestitch pattern and the weft Tex) are studied in order to establish the links morphology / process andmorphology / mechanical performances. Experimental investigations are undertaken to determine boththe hydraulic permeability tensor of the fabrics and the elastic properties of their composite. Thesemacroscopic properties are related to the morphology determined using images analysis technics. It isdemonstrated that each of the design parameters impacts the heterogeneity of the composite. Highheterogeneity allows improving the performance during the infusion process while reducing themechanical one. The optimization of the NCF using the design parameters requires setting acompromise in the heterogeneity of the architecture formed by the reinforcement. Another solutionwould consist in allowing the morphology to evolve during the infusion process, to go from an openstructure that eases the flow to a homogeneous structure safer for the windmill application
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Yan, Zhaohui. "Performance Analysis of A Banyan Based ATM Switching Fabric with Packet Priority." PDXScholar, 1995. https://pdxscholar.library.pdx.edu/open_access_etds/5199.
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Since the emergence of the Asynchronous Transfer Mode ( A TM ) concept, various switching architectures have been proposed. The multistage interconnection networks have been proposed for the switching architecture under the A TM environment. In this thesis, we propose a new model for the performance analysis of an A TM switching fabric based on single-buffered Banyan network. In this model, we use a three-state, i.e., "empty", "new" and "blocked" Markov chain model to describe the behavior of the buffer within a switching element. In addition to traditional statistical analysis including throughput and delay, we also examine the delay variation. Performance results show that the proposed model is more accurate in describing the switch behavior under uniform traffic environment in comparison with the "two-state" Markov chain model developed by Jenq, et. al.[4] [6] . Based on the "three-state" model, we study a packet priority scheme which gives the blocked packet higher priority to be routed forward during contention. It is found that the standard deviation of the network delay is reduced by about 30%.
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Burris, Sarah Mittiga. "Creatures: Series of Sculptural Costumes." Kent State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=kent1227280056.
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Ordija, James Louis. "Structural Performance of Fiber-Reinforced and Welded Wire Fabric-Reinforced Concrete Composite Slabs." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/40539.
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The purpose of this research is to evaluate and compare the structural performance of composite floor slabs reinforced with 6 x 6 W1.4/W1.4 welded wire fabric (WWF) and STRUX 90/40 synthetic macro fibers. Slabs were subjected to flexural strength tests and concentrated load tests while monitoring load, steel deck strains, and deflections. Test results obtained from this test program were also compared to results from a similar test program conducted in 2001. Tests were also performed to obtain the average residual-strength of the fiber-reinforced concrete using the ASTM C 1399 (2003) standard test.
All slabs were loaded until a complete failure was observed. The observed failure loads were compared to failure loads calculated by design guides published by the American Society of Civil Engineers (ASCE) and the Steel Deck Institute (SDI).
The flexural strength tests showed that composite slabs reinforced with synthetic macro fibers and WWF exhibited strength and behavior that was almost identical. The observed values of strength were also within the range that was predicted by ASCE prediction models. At a typical office design load of 70 psf, all slabs exhibited midspan deflections that were much smaller than those necessary for serviceability requirements.
The concentrated load tests also showed that the observed strength of all composite slabs tested was above those values predicted by ASCE and SDI models. However, an effective comparison between the WWF-reinforced and synthetic macro fiber-reinforced slab was difficult due to a poor shear bond in the latter slab prior to testing.
The results of the ASTM C 1399 test verified the ability of concrete reinforced with synthetic macro fibers to meet average residual-strength values recommended by the SDI.Master of Science
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Valavala, Pavan Kumar. "Uniaxial Tensile and Creep Behavior of Omnisil Membranes in Membrane Based Wet Electrostatic Precipitator." Ohio University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1129144907.
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Abdul, Ghani Suzaini. "Seam performance : analysis and modelling." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/seam-performance-analysis-and-modelling(da79315f-5f65-4c8d-9715-a7d270d453c8).html.
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Seam quality is affected by various fabric mechanical properties with a combination of their sewing parameters. Previously, a lot of research has been done on identifying the parameters that influencing seam quality by looking into correlation between fabric properties and sewing parameters. The purpose of this current study was to investigate the performance of seam quality in terms of seam appearance and strength constructed with different sewing parameters. Another aim was to identify parameters that influence the seam quality using the Structural Equation Modelling (SEM) by AMOS and leads to the development of multivariable predictive equations using SPSS. Finally, the validation between experimental and predicted results using newly developed equations was examined using a new set of fabrics. The investigation was done for five different fabric categories, namely light, light to medium, medium, medium to heavy and heavy weight. A total of 45 fabrics with different weave densities, fibre types and structures were used. Seams were produced using various sewing parameters such as threads with different fibre types and structures, needle sizes and stitch densities. All fabrics were tested for their mechanical properties using two established items of equipment known as Kawabata Evaluation System for Fabrics (KES-F) and Fabric Assurance by Simple Testing (FAST). Seam evaluations together with thread and fabric mechanical properties obtained from KES-F and FAST were used as input for modelling. From the experimental work, it was concluded that the usage of thicker threads did not always give better strength and the seam appearance was also poor. A combination of finer thread with moderate strength and a medium level of stitch density according to fabric weight category provided an effective result for both seam appearance and strength. From the modelling work, it was found that the extensibility, bending and shearing properties, together with thread properties including extensibility, tensile strength and size, were among the properties selected by SEM to be included in the predictive equations. The validation results showed that the standard deviation between fabric properties used to develop the equations and new fabric properties used for validation plays an important role. The principal conclusion was that the prediction equations developed using SEM and SPSS possible to be used and gave a strong validation between experimental and predicted results when the new fabric properties were within one standard deviation.
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Bergman, Sara. "Permissioned Blockchains and Distributed Databases : A Performance Study." Thesis, Linköpings universitet, Programvara och system, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-152230.
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Blockchain technology is a booming new field in both computer science and economicsand other use cases than cryptocurrencies are on the rise. Permissioned blockchains are oneinstance of the blockchain technique. In a permissioned blockchain the nodes which validatesnew transactions are trusted. Permissioned blockchains and distributed databasesare essentially two different ways for storing data, but how do they compare in terms ofperformance? This thesis compares Hyperledger Fabric to Apache Cassandra in four experimentsto investigate their insert and read latency. The experiments are executed usingDocker on an Azure virtual machine and the studied systems consist of up to 20 logicalnodes. Latency measurements are performed using varying network size and load. Forsmall networks, the insert latency of Cassandra is twice as high as that of Fabric, whereasfor larger networks Fabric has almost twice as high insert latencies as Cassandra. Fabrichas around 40 ms latency for reading data and Cassandra between 150 ms to 250 ms, thusit scales better for reading. The insert latency of different workloads is heavily affected bythe configuration of Fabric and by the Docker overhead for Cassandra. The read latency isnot affected by different workloads for either system.
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Navidpour, Mansour. "Reinforced Concrete Shear Walls with Welded Wire Grids as Boundary Element Transverse Reinforcement." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37702.
Full textAbstract:
Reinforced concrete shear walls as seismic force resisting systems may experience inelastic deformations if subjected to strong seismic excitations. These walls are designed to provide strength, stiffness, energy dissipation capacity and lateral drift control for seismic resistance. Shear wall deformability is largely dependent on adequate confinement of core concrete in boundary elements, prevention of longitudinal bar buckling, as well as proper design and detailing of the web section.
Conventional transverse reinforcement placed in shear wall boundary elements consists of hoops, overlapping hoops and crossties, based on the geometry and number of longitudinal bars used. The confinement steel requirement of current building codes (ACI 318 or CSA A23.3) often results in congestion of steel cage due to the high transverse reinforcement ratio required. Placing multiple hoops with 135-degree bends combined with crossties to satisfy the code confinement requirements can create concrete placement and construction problems. In addition, the required time to assemble conventional steel cages with multiple individual ties per spacing can be time consuming, potentially impacting the overall cost and duration of construction.
Welded Wire Reinforcement (WWR) is available in the construction industry as concrete reinforcement in the form of welded wire fabric (WWF) manufactured from relatively small diameter wires in comparison to the bar sizes typically used in structural applications. As an alternative to using conventional transverse hoops, prefabricated WWR grids can be used to provide required transverse reinforcement in boundary elements. WWR grids are manufactured using robots to weld cut steel pieces accurately before they are shipped to the job site, resulting in better construction quality and reduced construction time. However, research on the use of WWR is limited in the literature. Further experimental and analytical research is needed to establish design requirements for such reinforcement, especially when used in earthquake resistant construction with requirements for ductile response.
The current research project, involved three main phases; i) tests of 3 large-scale reinforced concrete shear walls with WWR grids used as boundary element transverse reinforcement, ii) material tests of grid samples, including those cast in concrete, iii) non-linear finite element analysis. The wall tests were conducted under slowly-applied lateral deformation reversals to investigate their strength and ductility for suitability as seismic resistant structural elements. Material tests were conducted to have a better understanding of WWR behavior, especially their weld capacity. Analytical research was undertaken to expand the experimental findings on shear wall behavior, as well as to conduct parametric investigation to understand the impact of changes in grid strength and ductility.
The results indicated that WWR grids can be used as boundary element transverse reinforcement in earthquake resistant shear wall. However, strength and ductility of grids should be established carefully prior to such application. Design strength of WWR grids should be established through burst tests to ensure ductile yielding of wire reinforcement prior to premature weld failure. Those grids that exhibit weld failures may be used with reduced design strength to permit the development of sufficient inelastic deformability in flexure-dominant shear walls.
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Loba, Frances Burroughs. "Eighteenth Century Men's Civilian Waistcoats." VCU Scholars Compass, 1996. http://hdl.handle.net/10156/1441.
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Guadagnim, João Luís. "Análise dos indicadores de desempenho fabril no setor de usinagem pesada em indústria de produção sob encomenda." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/18/18145/tde-19012011-104406/.
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A indústria brasileira produtora de bens de capital para o setor sucroalcooleiro, teve no início do século XXI grandes taxas de crescimento devido ao aumento do consumo do álcool combustível. Na onda deste crescimento, aumentou também o interesse das empresas em ingressar neste mercado. Para obter êxito, qualquer empresa deve conhecer muito bem os seus recursos de fabricação e gerenciá-los da melhor forma. Uma boa maneira de se conhecer o sistema produtivo de uma empresa é utilizando os indicadores de desempenho fabril. De posse destes indicadores é possível avaliar a eficiência, o índice de ciclo e os tempos de fila do setor. Assim, o objetivo deste trabalho é avaliar os indicadores de desempenho do setor mostrando o impacto que os tempos improdutivos podem causar no resultado final do exercício, usando como objeto de pesquisa o castelo de moenda, principal peça do conjunto do terno de moenda. Para o conhecimento dos indicadores foram acompanhadas 12 peças entre os meses de fevereiro e maio de 2008 e os resultados anotados. Com base nos resultados das 12 amostras a eficiência do setor ficou em 102%, o índice de ciclo em 19,8% e o tempo médio de fila entre as operações foi de 6,4 dias. Por meio da avaliação dos dados, conclui-se que o maior problema do setor é o gargalo formado antes das operações nas mandriladoras, estes gargalos influenciam diretamente no resultado do setor. O conhecimento destes valores pode orientar a empresa na busca por melhores resultados e direcionar esforços de maneira correta.The brazilian industry that produces capital possessions for the sugar and alcohol sector, had, in the beginning of the XXI century, a very high growth due to increasing of the fuel alcohol consumption. With this growth, there also was an increasing in the interests of the companies about entering this market. To be successful, any company should know very well its fabrication resources and manage them as well as possible. A good way to know the production system of a company is to use the indicators for the factory performance. Though these indicators is possible to evaluate the efficiency the cycle indexes and the row times of the sector. Another way to manage the production is through the analysis of the DRE (is the chart that contains the results of the exercise) that is totally connected with the performance indicators. Therefore, the purpose of this work is to evaluate the efficiency of the production, the index of the products cycles and the times of the rows at the sector showing the impact that the non productable times can cause in the final results of the exercise. For the evaluation of the indicators twelve housings were analyzed (main part of the milling tandem) between the months of February and May of 2008 and based in the results of the twelve pieces, the efficiency was 102%, value considered high for the sector, the cycle index was 19,8%, and the mean row times between the operations was 6,4 days. The study of the times and movements at the housings showed that during all the transformation process, the main obstade for the production flow was the milling machine. The evaluation of the efficiency and IC of the sector pointed out that the problem generated by the critical point of the production can damage too much the demonstrative of the results of the exercises (DRE) of the sector.
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Fatihou, Ali. "Amélioration des performances des matériaux fibreux non-tissés chargés par décharge couronne utilisés pour la filtration de l'air." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2286/document.
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La démarche expérimentale menée dans cette thèse a eu comme objectif l'étude des facteurs qui influent l'efficacité de collecte des médias non-tissés chargés par décharge couronne, utilisés pour la filtration de l'air. Les recherches se sont focalisées sur les techniques faisant appel à la décharge couronne en configuration fil-plan et en configuration triode (électrode duale + grille + plan de masse). L'étude s'est déroulée en trois phases : (1) mise au point de dispositifs expérimentaux pour générer la décharge couronne et mesurer le potentiel électrique à la surface des échantillons chargés ; (2) caractérisation de l'état de charge des médias ; (3) évaluation de l'efficacité de collecte, en corrélation avec les résultats des mesures de charge. La distribution de charges a été plus homogène en configuration triode et le niveau de charge a été meilleur en polarité positive. Le déplacement de l'échantillon dans la zone de décharge électrique permet de mieux uniformiser la distribution de la charge. L'augmentation du courant de décharge et du potentiel de grille permet d'amplifier le niveau de charge des médias, suite à l'intensification du champ électrique moyen entre l'électrode active et le plan de masse (en configuration fil – plan), ou entre la grille et le plan de masse (en configuration triode). L'efficacité de la collecte est meilleure si la charge est uniformément déposée, sous l'action d'un champ électrique plus intense. Elle est plus élevée pour les configurations dites « multicouches » où la captation des particules est améliorée par l'association de plusieurs mécanismes physiques, mettant en jeux des forces électriques et mécaniquesThe experimental approach undertaken in this thesis was aimed at the study of the factors affecting the collection efficiency of nonwoven media charged by corona discharge, used for air filtration. Research was focused on techniques using the corona discharge generated by wire-plane and triode configurations (dual electrode + grid + ground plane). The study was conducted in three phases: (1) development of experimental devices to generate corona discharge and measure the electrical potential on the surface of charged samples; (2) characterization of the electrostatic charge state of the media; (3) evaluation of the collection efficiency, correlated with the results of charge measurements. The charge distribution was more homogeneous in triode configuration and the charge level was higher in positive polarity. The sample movement in the electric discharge zone allowed for more uniform distribution of the charge. The increase of the discharge current and gate voltage amplifies the charge level of the media, due to the intensification of the average electric field between the active electrode and the ground plane (configuration wire - plane) or between the gate and the ground plane (in triode configuration). The collection efficiency is better when the charge is uniformly deposited, under the action of a strong electric field. It is higher for the so-called "multi-layer" configurations where the capture of the particles is improved by the combination of several physical mechanisms, involving electrical and mechanical forces
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de, Frias Lopez Ricardo. "Granular Materials for Transport Infrastructures : Mechanical performance of coarse–fine mixtures for unbound layers through DEM analysis." Licentiate thesis, KTH, Jord- och bergmekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-195598.
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Granular materials are widely used as unbound layers within the infrastructure system playing a significant role on performance and maintenance. However, fields like pavement and railway engineering still heavily rely on empirically-based models owing to the complex behaviour of these materials, which partly stems from their discrete nature. In this sense, the discrete element method (DEM) presents a numerical alternative to study the behaviour of discrete systems with explicit consideration of the processes at particulate level governing the macroscopic response. This thesis aims at providing micromechanical insight into the effect of different particle sizes on the load-bearing structure of granular materials and its influence on the resilient modulus and permanent deformation response, both of which are greatly influenced by the stress level. In order to accomplish this, binary mixtures of elastic spheres under axisymmetric stress are studied using DEM as the simplest expression for gap-graded materials, which in turn also can be seen as a simplification of more complex mixtures. First, the effect of the fines content on the force transmission at contact level was studied. Results were used to define a soil fabric classification system where the roles of the coarse and fine fractions were defined and quantified in terms of force transmission. A behavioural correspondence between numerical mixtures and granular materials was established, where the mixtures were able to reproduce some of the most significant features regarding the resilient modulus and permanent strain dependency on stress level for granular materials. A good correlation between soil fabric and performance was also found. Generally, higher resilient modulus and lower deformation values were observed for interactive fabrics, whereas the opposite held for instable fabrics. Mixtures of elastic spheres are far from granular materials, where numerous additional factors should be considered. Nevertheless, it is the author’s belief that this work provides insight into the soil fabric structure and its effect on the macroscopic response of granular materials.Grus i form av krossat bergmaterial används i stor utsträckning som obundna bär- och förstärkningslager inom tranportinfrastrukturen och spelar där en viktig roll för verkningsätt, drift och underhåll. Det finns emellertid begränsad kunskap om de fundamentala mekanismerna på partikelnivå (d.v.s. enskilda gruskorn), mekanismer som styr det makromekaniska verkningssättet. Områden såsom väg- och järnvägsbyggnad bygger fortfarande väsentligen på empiriskta baserade modeller p.g.a. dessa materials komplexa uppträdande under belastning. Denna komplexitet beror delvis på den diskreta naturen hos problemet vilket innebär att traditionell matematisk modellering som vore materialen homogena och kontinuerliga, blir inadekvat. Mot denna bakgrund utgör den s.k. diskreta elementmetoden (DEM) ett numeriskt alternativ för att studera verkningssätt hos diskreta system där man explicit beaktar mekanismerna på partikelnivå. Denna avhandling, som baseras på tre vetenskapliga bidrag, syftar till att ge mikromekaniska insikter vad gäller effekten av olika partikelstorlekar på bärförmågan hos grusmateral och dess inverkan på styvhet och motstånd mot permanenta deformationer. Båda dessa parametrar påverkas kraftigt av spänningsnivån och kan studeras genom triaxialförsök. För att undersöka detta studerades med hjälp av DEM binära blandningar av elastiska kulor – den enklaste modellen av grusmaterial med språng i fördelningskurvan – som utsattes för axialsymmetrisk belastning. Denna modell kan i sin tur ses som en förenkling av mer komplexa blandningar. Inledningsvis studerades effekten av finpartikelinnehållet på partikelkontakternas kraftöverföring. Resultaten användes för att klassificera olika typer av skelettstrukturer i grusmaterialet där den finare och den grövre fraktionens roller kvantifierades med utgångspunkt från kraftöverföringen i stället för från det makromekaniska verkningssättet. Resultaten visade en korrelation vad gäller verkningssättet mellan numeriska blandningar och grusmaterial, där de numeriska blandningarna kunde reproducera några av grusmaterials viktigaste kännetecken vad gäller spänningsberoendet för styvheten vid avlastning och motståndet mot permanent deformation. Vidare visades att styvheten kunde bestämmas ur första belastningscykeln vilket underlättar att övervinna de begränsningar avseende beräkningstid som annars förknippas med DEM. God överensstämmelse mellan grusmaterialets skelettstruktur och verkningssätt kunde också observeras. Generellt observerades högre styvhet och mindre permanenta deformationer för interaktiva skelettstrukturer medan det motsatta gällde för instabila strukturer. Numeriska blandningar av elastiska kulor är långt från verkliga grusmaterial, för vilka ett stort antal ytterligare faktorer måste beaktas. Icke desto mindre är det författarens övertygelse att detta arbete ger insikter i grusmaterialets skelettstruktur och dess effekter på det makromekaniska verkningssättet hos grusmaterial.
QC 20161116
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Büscher, Barbara, and Verena Elisabet Eitel. "Forum Freies Theater Düsseldorf: Geschichte, Raumprogramm, kuratorische Konzeptionen und künstlerische Projekte: Produktionshäuser zeitgenössischer performativer Künste." Hochschule für Musik und Theater Leipzig, 2020. https://slub.qucosa.de/id/qucosa%3A72779.
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Der Institutionalisierungsprozess des freien Theaters und der performativen Künste ist unmittelbar mit der „Eroberung“ oder „Zuteilung“ eigener Räume und Häuser seit der zweiten Hälfte der 1980er-Jahre verbunden. Mittlerweile liegen die Anfänge der Etablierung von Produktionshäusern also mehr als 30 Jahre zurück und ihre Geschichte hat die Möglichkeiten und Bedingungen für Aufführungen aller Art wesentlich verändert und erweitert. Diese Geschichte(n) zurück zu verfolgen und mit ihrer Erschließung zu beginnen, ist wesentliche Voraussetzung für die Untersuchung aktueller Verhältnisse zwischen Raum/Architektur und Produktions-/Spielweisen. Das erste ARBEITSHEFT widmet sich dem Forum Freies Theater Düsseldorf.
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Prado, Monica Faria de Almeida. "Conforto térmico nos edifícios das indústrias de calçados de Jaú." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/102/102131/tde-28022013-104203/.
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Este trabalho aborda o desempenho térmico obtido em edifícios industriais do setor calçadista, perante a importância em obter condições ambientais favoráveis à execução das atividades através de uma arquitetura adequada ao contexto climático. Assim, o objetivo nesta pesquisa é avaliar as condições de conforto térmico oferecidas pelos edifícios das indústrias calçadistas do município de Jaú, um importante pólo industrial do setor no interior de São Paulo. Caracterizam-se as tipologias construtivas dos edifícios quanto à geometria, materiais e sistema de ventilação. As estratégias passivas para obtenção de conforto térmico nos galpões fabris são identificadas e avaliadas utilizando as recomendações presentes na NBR 15220. Para avaliar as condições de conforto térmico, foram medidas as variáveis ambientais, sendo que a temperatura foi analisada sob condições de aceitabilidade térmica, conforme estabelecido pela ASHRAE 55-2010. Para estimar a sensação térmica dos usuários, são utilizados os índices PMV e PPD. Também foi aplicado um questionário para verificar o nível de satisfação dos funcionários com o ambiente de trabalho. Os resultados apontam que a maioria dos edifícios apresenta uma tipologia semelhante, com geometria retangular e ventilação realizada através de esquadrias nas fachadas. A ausência de diversas estratégias passivas resulta em um edifício com baixa inércia térmica e vulnerável às condições climáticas externas, sendo que em períodos quentes a temperatura interna foi superior a 30ºC, e em períodos frios inferior a 15ºC. A sensação térmica dos usuários na maior parte do período do expediente corresponde ao desconforto térmico para o calor, principalmente no período vespertino, sendo que a porcentagem de insatisfeitos ultrapassa 80%. Deste modo, há necessidade de otimizar a adoção de estratégias passivas, para proporcionar melhores condições térmicas de trabalho. Para isto, são indicadas soluções simples, que propiciam melhorias ao desempenho térmico dos edifícios, exemplificando: o uso de sistemas que possibilitem o resfriamento evaporativo e ampliação das áreas de aberturas destinadas à ventilação do edifício.This paper discusses the thermal performance obtained in industrial buildings in the footwear sector, given the importance of obtaining favorable environmental conditions for the execution of activities through an architecture suited to the climate context. Thus, the objective of this research is to evaluate the thermal comfort conditions provided by the buildings of the footwear industries of Jaú city, an important industrial pole. It is characterized the typologies of building\'s construction regarding its geometry, materials and ventilation system. The passive strategies for achieving thermal comfort in the factory sheds are identified and evaluated using the recommendations present in the NBR 15220. To evaluate the thermal comfort conditions it was measured the environmental variables, and the temperature was examined under conditions of thermal acceptability, as established by ASHRAE 55-2010. In order to estimate the thermal sensation of the users, the PMV and PPD indices were used. Also, a questionnaire was applied in order to check the level of employee satisfaction with the working environment. The results show that most of the buildings presents a typology similar with a rectangular geometry and ventilation obtained through frames at the facades. The absence of different passive strategies results in a building with a low thermal inertia and vulnerable to the external weather conditions, and in hot periods, the internal temperature was above 30°C, and during colder periods it was lower than 15°C. The thermal sensation of users in most of the period of the working shift matches the thermal discomfort to the heat, especially in the afternoon, and the percentage of discontentment exceeds 80%. This way, there is a need to optimize the adoption of passive strategies, to provide better thermal conditions of work. For this purpose, simple solutions that provide improvements to the thermal performance of buildings are given, examples: the use of systems which allows evaporative cooling and expansion of openings areas for the ventilation of the building.
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Huguet, Charlotte. "Catalogue raisonné de l’œuvre de Franz Erhard Walther de ses premiers travaux en 1954 à ce jour." Thesis, Paris 4, 2015. http://www.theses.fr/2015PA040089.
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L'objectif de cette thèse est de proposer une étude exhaustive de l’œuvre de l'artiste allemand contemporain Franz Erhard Walther (1939, Fulda - ), accompagnant l'élaboration du catalogue raisonné de l'ensemble de son travail. En effet, pour cet artiste à l’œuvre colossale, la nécessité de la réalisation d'un catalogue raisonné se pose depuis plusieurs années. Bien que son œuvre ait une place fondamentale dans l'histoire de l'art de la deuxième moitié du XXème siècle, le travail de Walther reste encore très mal connu et souvent sujet à confusion. Cette œuvre, caractérisée en grande partie par l'utilisation de la couture comme technique et du tissu comme matériau, et dont la monumentalité n'a été rendue possible que grâce à la collaboration de l'artiste avec sa première femme, Johanna Frieß, trouve sa spécificité à travers l'évolution du concept de Handlung, propre à l'artiste. Cette étude propose donc le premier véritable catalogue raisonné de Franz Erhard Walther, de ses premières œuvres en 1954 à ce jour, accompagné d'une étude précise de chaque groupe d’œuvres, replaçant ainsi l'ensemble dans le contexte de l'histoire de l'artThe objective of this thesis is to propose an exhaustive study of the work of the german contemporary artist Franz Erhard Walther (1939, Fulda - ), as well as the catalogue raisonné of his work. There is indeed since many years an imperative need for such a comprehensive catalogue, given the colossal production of Walther. Although his work plays a prominent role in the Art History of the second half of the XXth century, it remains little-known and is still subject of some confusion. This body of work, mainly characterized by the use of sewing as technique and tissue as material, and whose enormity wouldn't have been possible without the collaboration of the artist's first wife, Johanna Frieß, finds its specificity in the concept of Handlung that Walther developed. This study includes thus the first actual catalogue raisonné of Franz Erhard Walter, from his first-ever works of 1954 until now, as well as a specific study of every group of works, putting it in the context of Art History
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Wonjiga, Amir Teshome. "User-centric security monitoring in cloud environments." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S080.
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Les fournisseurs de services reconnaissent le problème de confiance et fournissent une garantie par le biais d'un contrat appelé Service Level Agreement (SLA). Presque tous les SLAs existants ne traitent que des fonctionnalités du nuage informatique et ne garantissent donc pas l'aspect sécurité des services hébergés pour les locataires. Comme le nuage informatique continue d'être de plus en plus intégré, il est nécessaire d'avoir des services de supervision de la sécurité propres a l'utilisateur, qui sont fondés sur les exigences des locataires. Cet aspect de supervision de la sécurité du système exige également que les fournisseurs offrent des garanties. Dans cette thèse, nous contribuons à l'inclusion de termes de supervision de la sécurité centres sur l'utilisateur dans les SLAs de l'informatique en nuage. Nous concevons des extensions à un langage de SLA existant appelé Cloud SLA (CSLA). Notre extension, appelée Extended CSLA (ECSLA), permet aux locataires de décrire leurs besoins en matière de supervision de la sécurité en termes de vulnérabilités. Plus précisément, un service de supervision de la sécurité est décrit comme une relation entre les besoins de l'utilisateur en tant que vulnérabilités, un produit logiciel présentant ces vulnérabilités et une infrastructure où le logiciel est exécuté. Nous proposons une solution pour réduire le nombre d’évaluations nécessaires par rapport au nombre de configurations possibles. La solution proposée introduit deux nouvelles idées. Tout d'abord, nous concevons une méthode de construction d'une base de connaissances qui repose sur des regroupements de vulnérabilités a partir d'heuristiques. Deuxièmement, nous proposons un modèle pour quantifier l’interférence entre des règles de détection associées à des vulnérabilités différentes. En utilisant ces deux méthodes, nous pouvons estimer la performance d'un dispositif de supervision avec peu d’évaluations par rapport à une approche naïve. Les métriques utilisées dans nos termes de SLA tiennent compte de l'environnement opérationnel des dispositifs de supervision de la sécurité. Afin de tenir compte des paramètres imprévisibles de l'environnement opérationnel, nous proposons un mécanisme d'estimation ou la performance d'un dispositif de supervision est mesurée à l'aide de valeurs connues pour ces paramètres et le résultat est utilisé pour modéliser sa performance et l'estimer pour les valeurs inconnues de ces paramètres. Une définition de SLA contient le modèle, qui peut être utilisé chaque fois que la mesure est effectuée. Nous proposons une méthode d’évaluation in situ de la configuration d'un dispositif de supervision de sécurité. Elle permet de vérifier la performance d'une configuration de l'infrastructure de supervision de sécurité dans un environnement de production. La méthode utilise une technique d'injection d'attaques mais les attaques injectées n'affectent pas les machines virtuelles de production. Nous avons mis en œuvre et évalué la méthode de vérification proposée. La méthode peut être utilisée par l'une ou l'autre des parties pour calculer la métrique requise. Cependant, elle exige une coopération entre les locataires et les fournisseurs de service. Afin de réduire la dépendance entre eux lors de la vérification, nous proposons d'utiliser un composant logique sécurisé. L'utilisation proposée d'un composant logique sécurisé pour la vérification est illustrée dans un SLA portant sur l’intégrité des données dans les nuages informatiques. La méthode utilise un registre sécurisé, fiable et distribué pour stocker les preuves de l’intégrité des données. La méthode permet de vérifier l’intégrité des données sans se fier à l'autre partie. S'il y a un conflit entre un locataire et un fournisseur, la preuve peut être utilisée pour résoudre ce conflitMigrating to the cloud results in losing full control of the physical infrastructure as the cloud service provider (CSP) is responsible for managing the infrastructure including its security. As this incites tenants to rely on CSPs for the security of their information system, it creates a trust issue. CSPs acknowledge the trust issue and provide a guarantee through Service Level Agreement (SLA). The agreement describes the provided service and penalties for the cases of violation. Almost all existing SLAs only address the functional features of the cloud and thus do not guarantee the security aspect of tenants’ hosted services. Security monitoring is the process of collecting and analyzing indicators of potential security threats, then triaging these threats by appropriate action. It is highly desirable for CSPs to provide user-specific security monitoring services which are based on the requirements of a tenant. In this thesis we present our contribution to include user-centric security monitoring terms into cloud SLAs. This requires performing different tasks in the cloud service life-cycle, starting before the actual service deployment until the end of the service. Our contributions are presented as follows : we design extensions to an existing SLA language called Cloud SLA (CSLA). Our extension, called Extended CSLA (ECSLA), allows tenants to describe their security monitoring requirements in terms of vulnerabilities. More precisely, a security monitoring service is described as a relation between user requirements as vulnerabilities, a software product having the vulnerabilities and an infrastructure where the software is running. To offer security monitoring SLAs, CSPs need to measure the performance of their security monitoring capability with different configurations. We propose a solution to reduces the required number of evaluations compared to the number of possible configurations. The proposed solution introduces two new ideas. First, we design a knowledge base building method which uses clustering to categorize a bunch of vulnerabilities together in groups using some heuristics. Second we propose a model to quantify the interference between operations of monitoring vulnerabilities. Using these two methods we can estimate the performance of a monitoring device with few numbers of evaluations compared to the naive approach. The metrics used in our SLA terms consider the operational environment of the security monitoring devices. In order to consider the non-determistic operational environment parameters, we propose an estimation mechanism where the performance of a monitoring device is measured using known parameters and the result is used to model its performance and estimate it for unknown values of that parameter. An SLA definition contains the model, which can be used whenever the measurement is performed. We propose an in situ evaluation method of the security monitoring configuration. It can evaluate the performance of a security monitoring setup in a production environment. The method uses an attack injection technique but injected attacks do not affect the production virtual machines. We have implemented and evaluated the proposed method. The method can be used by either of the parties to compute the required metric. However, the method requires cooperation between tenants and CSPs. In order to reduce the dependency between tenants and CSPs while performing verification, we propose to use a logical secure component. The proposed use of a logical secure component for verification is illustrated in an SLA addressing data integrity in clouds. The method uses a secure trusted and distributed ledger (blockchain) to store evidences of data integrity. The method allows checking data integrity without relying on the other party. If there is any conflict between tenants and CSPs the evidence can be used to resolve the conflict
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Tsaur, Ding-Jyh, and 曹定智. "Scheduling Algorithms and Performance Evaluation of High-Speed Switching Fabrics." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/53706711092318457256.
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博士國立中興大學
資訊科學系
94
This work studies scheduling algorithms and evaluates the performance of high-speed electronic and photonic switching systems. A novel architecture for three-dimensional Virtual Output Queue (3D-VOQ) switches is proposed for use in electronic switching systems, in connection with a scheduling algorithm to improve the competitive transfer of service. This 3D-VOQ switch, which exactly emulates an output-queued switch with a broad class of service scheduling algorithms, requires no speedup, independently of its incoming traffic pattern and switch size. First, an N×N 3D-VOQ switch is proposed. In this contention-free architecture, the head-of-line problems are eliminated using a few virtual output queues (VOQ) from input ports and the output sides were arranged using sufficient separate queues. Next, a Small Time-to-leave Cell First (STCF) algorithm is proposed to generate a stable many-to-many assignment. The proposed 3D-VOQ switch is demonstrated to be able to mimic an exact OQ switch. Finally, analysis and simulation confirm the performance of 3D-VOQ and its satisfying high/low QoS requirements. The photonic switching system applies a threshold-based matching algorithm for Clos (t-MAC) network switches. The studied Clos network uses a central photonic switch fabric for transporting high-speed optical signals and electronic controllers at the input and output ports. The proposed matching algorithm can be used to solve the scheduling problems associated with the Clos network. The matching algorithm incorporates cut-through transmission, variable-threshold adjustment and preemptive scheduling. The performance is evaluated using the bursty and unbalanced traffic model, and simulation results obtained by t-MAC are presented. The results indicate that the proposed algorithm significantly reduces switching latency by approximately 45 to 36 % below that of Chao’s c-MAC.
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邱美珠. "Method of test for evaluating the performance of ultraviolet-protection fabrics." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/15085310380244148474.
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碩士國立臺北科技大學
有機高分子研究所
90
The demand for ultraviolet protective clothing in Taiwan has been increased rapidly since the past few years. Therefore, a national standard method of test for evaluating the performance of ultraviolet protective fabrics should be established as soon as possible. At present, only Australia, New Zealand, Great Britain and the United States of America have their national standard method of test, AS／NZS 4399, BS 7914 and AATCC 183. The differences between these three methods of test were evaluated and the ultraviolet radiation flux density (Sλ) which conforms to Taiwan was set up with data from the Brewer Spectrophotometer at Chengkung Station during July and August of the years 1996─1999. The calculations for Ultraviolet Protection Factor (UPF) or Penetration （p） are very troublesome and time-consuming. We have therefore designed software to achieve results more easily, quickly and accurately. The method of test using relative erythemal effectiveness (Eλ) from Mckinlay and Diffey and Sλ of 290∼400 nm from Chengkung Station to calculate the UPF was also proposed.
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Pedram, Ardavan. "Algorithm/architecture codesign of low power and high performance linear algebra compute fabrics." 2013. http://hdl.handle.net/2152/21364.
Full textAbstract:
In the past, we could rely on technology scaling and new micro-architectural techniques to improve the performance of processors. Nowadays, both of these methods are reaching their limits. The primary concern in future architectures with billions of transistors on a chip and limited power budgets is power/energy efficiency. Full-custom design of application-specific cores can yield up to two orders of magnitude better power efficiency over conventional general-purpose cores. However, a tremendous design effort is required in integrating a new accelerator for each new application. In this dissertation, we present the design of specialized compute fabrics that maintain the efficiency of full custom hardware while providing enough flexibility to execute a whole class of coarse-grain operations. The broad vision is to develop integrated and specialized hardware/software solutions that are co-optimized and co-designed across all layers ranging from the basic hardware foundations all the way to the application programming support through standard linear algebra libraries. We try to address these issues specifically in the context of dense linear algebra applications. In the process, we pursue the main questions that architects will face while designing such accelerators. How broad is this class of applications that the accelerator can support? What are the limiting factors that prevent utilization of these accelerators on the chip? What is the maximum achievable performance/efficiency? Answering these questions requires expertise and careful codesign of the algorithms and the architecture to select the best possible components, datapaths, and data movement patterns resulting in a more efficient hardware-software codesign. In some cases, codesign reduces complexities that are imposed on the algorithm side due to the initial limitations in the architectures. We design a specialized Linear Algebra Processor (LAP) architecture and discuss the details of mapping of matrix-matrix multiplication onto it. We further verify the flexibility of our design for computing a broad class of linear algebra kernels. We conclude that this architecture can perform a broad range of matrix-matrix operations as complex as matrix factorizations, and even Fast Fourier Transforms (FFTs), while maintaining its ASIC level efficiency. We present a power-performance model that compares state-of-the-art CPUs and GPUs with our design. Our power-performance model reveals sources of inefficiencies in CPUs and GPUs. We demonstrate how to overcome such inefficiencies in the process of designing our LAP. As we progress through this dissertation, we introduce modifications of the original matrix-matrix multiplication engine to facilitate the mapping of more complex operations. We observe the resulting performance and efficiencies on the modified engine using our power estimation methodology. When compared to other conventional architectures for linear algebra applications and FFT, our LAP is over an order of magnitude better in terms of power efficiency. Based on our estimations, up to 55 and 25 GFLOPS/W single- and double-precision efficiencies are achievable on a single chip in standard 45nm technology.text
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Dubinsky, Gregg. "Performance Evaluation of Two Silt Fence Geosynthetic Fabrics During and After Rainfall Event." Master's thesis, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6092.
Full textAbstract:
Silt fence is one of the most widely used perimeter control devices and is considered an industry standard for use in the control of sediment transport from construction sites. Numerous research studies have been conducted on the use of silt fence as a perimeter control, including a number of studies involving controlled laboratory flume tests and outdoor tests performed in the field on construction sites with actual monitored storm events. In field tests, due to the random and uncontrollable nature of real storm events and field conditions, studies have shown difficulty in evaluating silt fence performance. These field studies have shown the need for performance testing of silt fence in a more controlled environment, which can also simulate the actual use and performance in the field. This research, which is a continuation of ongoing research on silt fence fabrics at UCF Stormwater and Management Academy, was conducted in order to evaluate silt fence performance under simulated field conditions. Presented in this thesis are evaluation of two silt fence fabrics, a woven (ASR 1400) fabric and nonwoven (BSRF) fabric. Both fabrics were installed separately on a tilted test bed filled with a silty-sand soil and subjected to simulated rainfall.
Previous field studies on the performance of silt fence fabrics have evaluated the turbidity and sediment removal efficiencies only after the rain event, with the assumption that the efficiency values represent the true overall performance of silt fence. The results of this study revealed that the turbidity and suspended sediment performance efficiencies of silt fence were significantly affected by the time of sampling. The performance efficiencies during rainfall remained less than 55 percent, however, after the rainfall event ended, the performance efficiencies increased over time, reaching performance efficiency upwards of 90 percent. The increase in efficiency after rainfall was due to the constant or decreasing ponding depth behind the silt fence, increased filtration due to fabric clogging, and sedimentation of suspended particles.
The nonwoven fabric was found to achieve higher removal efficiencies and flow-through rates both during and after the rain event when compared with the woven fabric. However, over the entire test duration (during and after rainfall combined), the projected overall efficiencies of both fabrics were similar. The projected overall average turbidity performance efficiencies of the woven and nonwoven silt fence fabrics was 80 and 78 percent, respectively. Both fabric types also achieved comparable overall average suspended sediment concentration efficiencies of 79 percent.
This result leads to the conclusion that silt fence performance in the field is dependent on three main processes: filtration efficiency occurring during the rain event, filtration and sedimentation efficiency occurring after the rainfall event, and flow-through rate of the silt fence fabrics. Decreases in the flow-through rate lead to increases in the overall efficiency. This thesis quantifies the different mechanisms by which these processes contribute to the overall efficiency of the silt fence system and shows how these processes are affected by different conditions such as the degree of embankment slope and rainfall intensity.M.S.Env.E.
Masters
Civil, Environmental and Construction Engineering
Engineering and Computer Science
Environmental Engineering