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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Spinning Methods for Carbon Nanotube Fibers

Wang, Anli 23 October 2014 (has links)
No description available.
72

Policy-Driven YARN Launcher

Giannokostas, Vasileios January 2016 (has links)
In recent years, there has been a rising demand for IT solutions that are capable to handle vast amount of data. Hadoop became the de facto software framework for distributed storage and distributed processing of huge datasets with a high pace. YARN is the resource management layer for Hadoop ecosystem which decouples the programming model from the resource management mechanism. Although Hadoop and YARN create a powerful ecosystem which provides scalability and flexibility, launching applications with YARN currently requires intimate knowledge of YARN’s inner workings. This thesis focuses on designing and developing support for a human-friendly YARN application launching environmen twhere the system takes responsibility for allocating resources to applications. This novel idea will simplify the launching process of an application and it will give the opportunity to inexperienced users to run applications over Hadoop. / De senaste åren har haft en ökad efterfrågan på IT-lösningar som är kapabla att hantera stora mängd data. Hadoop är ett av de mest använda ramverken för att lagra och behandla stora datamängder distribuerat och i ett högt tempo. YARN är ett resurshanteringslager för Hadoop som skiljer programmeringsmodellen från resurshanteringsmekanismen. Även fast Hadoop och YARN skapar ett kraftfullt system som ger flexibilitet och skalbarhet så krävs det avancerade kunskaper om YARN för att göra detta. Detta examensarbete fokuserar på design och utveckling av en människovänlig YARN applikationsstartsmiljö där systemet tar ansvar för tilldelning av resurser till program. Denna nya idé förenklar starten av program och ger oerfarna användare möjligheten att köra program över Hadoop.
73

Evaluation of the Length Dependent Yarn Properties

Rypl, Rostislav, Chudoba, Rostislav, Vorechovský, Miroslav, Gries, Thomas 01 December 2011 (has links) (PDF)
The paper proposes a method for characterizing the in-situ interaction between filaments in a multifilament yarn. The stress transfer between neighboring filaments causes the reactivation of a broken filament at some distance from the break. The utilized statistical bundle models predict a change in the slope of the mean size effect curve once the specimen length becomes longer than the stress transfer length. This fact can be exploited in order to determine the stress transfer length indirectly using the yarn tensile test with appropriately chosen test lengths. The identification procedure is demonstrated using two test series of tensile tests with AR-glass and carbon yarns.
74

Evaluation of the Length Dependent Yarn Properties

Rypl, Rostislav, Chudoba, Rostislav, Vorechovský, Miroslav, Gries, Thomas January 2011 (has links)
The paper proposes a method for characterizing the in-situ interaction between filaments in a multifilament yarn. The stress transfer between neighboring filaments causes the reactivation of a broken filament at some distance from the break. The utilized statistical bundle models predict a change in the slope of the mean size effect curve once the specimen length becomes longer than the stress transfer length. This fact can be exploited in order to determine the stress transfer length indirectly using the yarn tensile test with appropriately chosen test lengths. The identification procedure is demonstrated using two test series of tensile tests with AR-glass and carbon yarns.
75

Development and investigation of weft knitted strain sensor

Atalay, Ozgur January 2015 (has links)
This thesis presents a study of the sensing properties exhibited by textile-based knitted strain sensors. Sensing fabrics were manufactured from silver-plated conductive nylon and non-conducting elastomeric yarns. The component yarns offered similar diameters, bending characteristics and surface friction, but their production parameters differed in respect of the yarn input tension, the number of conductive courses in the sensing structure and the elastomeric yarn extension characteristics. The knitted sensors were manufactured using flat-bed knitting technology, and electro-mechanical tests were performed on the specimens using a tensile testing machine to apply strain whilst the sensor was incorporated into a Wheatstone bridge arrangement to allow electrical monitoring. The novel operational principle relies on the separation under strain of adjacent conducting knitted loops which are normally held in contact by the elastomeric yarn. The results confirm that production parameters play a fundamental role in determining the physical behaviour and the sensing properties of knitted sensors and the response could be engineered by varying the production parameters of specific designs. Results showed that the knitted structures could be manipulated to produce gauge factor values between 2.26 and 0.23 for sensors with working ranges of 8.4 % and 3.3 % respectively when the elastomeric yarn had 8 cN input tension. The generated signals were stable and repeatable, and under cyclic testing proved to be substantially free from long-term drift. A textile-based strain sensor was developed to create a respiration belt; this was realised by bringing together the extensible knitted sensor and a relatively inelastic textile strap. Machine simulations and real time measurements on a human subject were performed to calculate average breathing frequencies under different static and dynamic conditions. Various respiration rates were monitored to simulate different medical conditions and with the belt located either round the torso or in the abdominal area, the sensor yielded a satisfactory response. However, body motion artefacts affected the signal quality under dynamic conditions and an additional signal-processing step was added to separate unwanted interference from the breathing signal. Electro-mechanical modelling was developed by exploiting Peirce`s loop model in order to describe the fabric geometry under static and dynamic conditions. Kirchhoff`s node and loop equations were employed to create a generalised solution for the equivalent electrical resistance of the textile sensor for a given knitted loop geometry and for a specified number of loops. Experimental results were obtained from the sensor for strain levels up to 40% and these correlate well with the modelled data; a maximum error of 2.13 % was found between the experimental and modelled resistance-strain relationships.
76

Melt spun piezoelectric textile fibres : an experimental study

Lund, Anja January 2013 (has links)
The manufacturing and characterisation of piezoelectric textile fibres are described in this thesis. A piezoelectric material is one that generates an electric voltage when deformed, a property which exists in a number of materials. The polymer with the strongest known piezoelectric effect today is poly(vinylidene fluoride) (PVDF), however it must be processed under certain conditions to become piezoelectric. This study shows that piezoelectric bicomponent PVDF-based fibres can be produced by melt spinning, which is a common and relatively simple fibre spinning method. The melt spinning process must include cold drawing, as this introduces a polar crystalline structure in the polymer. The fibres must also be electroded, which is done by producing bicomponent fibres with a core-and-sheath structure. The core is electrically conductive and constitutes an inner electrode consisting of a carbon black/polymer compound, whereas the sheath is PVDF and constitutes the piezoelectric component. Being sensitive to both deformation and temperature changes, these fibres are anticipated to be useful in a number of sensor applications. The flexibility and small size of the fibres makes it possible to include them as miniature-sensors in structures or garment without affecting the shape or comfort.
77

Improvement of Work-to-Break Characteristics of Cotton (Gossypium hirsutum L.) Fibers and Yarn through Breeding and Selection for Improved Fiber Elongation

Osorio Marin, Juliana 1982- 14 March 2013 (has links)
The development of cottons with improved fiber quality has been a major objective in breeding programs around the world. Breeders have focused their attention on improving fiber strength and length, and have generally not used fiber elongation in the selection process. Although literature has reported a negative correlation between fiber elongation and tenacity, this correlation is weak and should not prevent breeders from simultaneously improving fiber tenacity and fiber elongation. Furthermore, the work of rupture property, important in the spinning process, could be best enhanced by improving both fiber tenacity and fiber elongation. Fifteen populations were developed in 2007 by crossing good quality breeding lines with high elongation measurements to ‘FM 958’; a High Plains standard cultivar with good fiber quality but reduced elongation. Samples in every generation were ginned on a laboratory saw gin, and the lint was tested on HVI (High Volume Instrument). The F2 and F3 generations showed a wide range of variation for elongation (6.9% - 12.8% for the F2 and 4% - 9.20% for the F3) allowing divergent selection for low and high fiber elongation. A correlation (r) of -0.32 between strength and elongation was observed in the F2 individual plant selections. In the F3, the correlation (r) between strength and elongation was -0.36, and in the F4 the correlation (r) was -0.08. Nine lines were selected from the original 15 populations for spinning tests. The correlation between fiber elongation and strength for these lines was positive (r=0.424), indicating that with targeted selection, fiber elongation and strength can be simultaneously improved. Fiber elongation was positively correlated with yarn tensile properties tenacity (r=0.11), work-to-break (r=0.68) and breaking elongation (r=0.87); and was negatively correlated with yarn evenness properties, number of thin places (r=-0.16), number of thick places (r=-0.9), nep count (r=-0.24), hairiness (r=-0.38) and total number of imperfections (r=-0.38). All selections for high elongation were superior for all tensile properties compared to the low selections and the check in the analysis over locations and in each location. Furthermore, selections for high elongation were significantly different from the selections for low elongation and the check. In addition to developing lines for fiber spinning tests with improved, or differentiated, fiber elongation, this project was amended to evaluate and determine the heritability of fiber elongation. Three different methodologies were used to obtain estimates of heritability; variance components, parent off-spring regression, and realized heritability using F3, F4, and F5 generation. No inbreeding was assumed because there was no family structure in the generations within this study. Estimates of heritability by the variance component methods in the F3, F4 and F5 were 69.5%, 56.75% and 47.9% respectively; indicating that 40-50% of the variation was due to non-genetic effects. Parent off-spring regression estimates of heritability were 66.1% for the F3-4 and 62.8% for the F4-5; indicating a high resemblance from parents to off-spring. Estimates of realized heritability were obtained to determine the progress realized from selection for the low and high selection for fiber elongation. Estimates were intermediate (0.44–0.55), indicating moderately good progress from selection. The results from this project demonstrate that it is possible to improve fiber elongation and to break the negative correlation between elongation and strength. Furthermore, it has been demonstrated that improving fiber elongation results in the increase of length uniformity index and decreased short fiber content. Additionally, directed divergent selection was a successful methodology for the improvement of fiber elongation, and was useful to demonstrate that higher fiber elongation has a positive effect on yarn tensile properties, yarn evenness and processing. The development of new cultivars with improved fiber elongation will improve the quality and reputation of U. S.-grown cotton. The ultimate result will be better yarn quality and improved weaving efficiency, and particularly address current weaknesses in U. S. –grown cotton cultivars, especially from the High Plains of Texas, of more short fiber content, lower uniformity ratios, and weaker yarn strength.
78

COMPARISON OF PICKER AND STRIPPER HARVESTERS ON IRRIGATED COTTON ON THE HIGH PLAINS OF TEXAS

Faulkner, William B. 16 January 2010 (has links)
Over a fourth of the cotton produced in the US since 2002 has been produced in Texas, with most coming from the High Plains. In recent years, Texas has accounted for almost half of all US cotton production (USDA-NASS, 2008b). Most cotton on the High Plains is of more storm-proof varieties that have traditionally been harvested using stripper harvesters. However, improvements in irrigation technology and shifting markets for US cotton have increased interest in picker harvesters in the region. A holistic comparison of picker and stripper harvesters in irrigated cotton on the High Plains of Texas was conducted focusing on differences in system efficiencies, the costs of ginning, fiber and yarn quality, and potential economic returns under comparable crop yields and conditions. Harvester performance was evaluated based on harvest efficiency, time-inmotion, and fuel consumption. Stripper harvesters left less cotton in the field, but most of the cotton left by the picker was of low quality. While the time spent in each operation of harvest was highly dependent on the operator and support equipment available, in general, picker harvesters were able to harvest a unit area of high-yielding cotton more quickly than stripper harvesters. The cost of ginning picked and stripped cotton was evaluated considering current fee schedules from gins on the High Plains. On average, it cost a producer $4.76 more per bale to gin stripped-and-field-cleaned cotton than picked cotton. Fiber quality parameters were compared between harvest treatments based on results from High Volume Instrument (HVI) and Advanced Fiber Information System (AFIS) tests. Samples were ring-spun into carded and carded-and-combed yarns. Differences in fiber quality between harvest treatments were more pronounced when growing conditions were less favorable. Few differences were detected in carded yarn quality between harvest treatments, while more pronounced differences favoring picked cotton were seen in carded-and-combed yarns. A cost-benefit analysis was conducted to determine the production scenarios in which picker and stripper harvesters were most appropriate. Results indicate that, if a producer has sufficient yields coupled with sufficient area to harvest per machine, picker harvesting is a more profitable alternative to producers of on the High Plains.
79

Structure-process-property relationships in polyester spun yarns : the role of fiber friction

Hong, Joohyun 12 1900 (has links)
No description available.
80

An investigation into reducing time dependent creep of a polyethylene geotextile using glass fiber yarns

Xiong, Jun 16 January 2014 (has links)
An investigation has been carried out to reduce the deformation behavior of polyethylene (PE) woven geotextile fabric by making PE fabric-glass yarn composite structure using stitching and laminating. The results showed that reinforcement significantly reduced the creep and IED as long as the tensile stress is lower than the total load bearing capacity of the glass yarns in the composite structure. However, the strength of PE-glass composite fabric was solely dependent on the strength of the glass yarns. The strength from PE yarns only contributes when all glass yarns are broken. Cast result of concrete columns using the glass yarn reinforced PE fabric by stitching method suggested that the glass yarn must face outside of the fabric formwork to avoid damage of both fabric surface and column surface.

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