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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.
101

The development of cotton spinning and weaving industries in Hong Kong, 1946-1966.

Mok, Ching-heng, Marina. January 1968 (has links)
Thesis (M.A.)--University of Hong Kong, 1969. / Typewritten.
102

BENCH-SCALE, MULTIFILAMENT SPINNING CONDITIONS EFFECT ON THE STRUCTURE AND PROPERTIES OF POLYACRYLONITRILE PRECURSOR FIBER

Morris, Elizabeth Ashley 01 January 2011 (has links)
Due to its unique characteristics, carbon fiber is one of the leading materials for light weight, high strength and stiffness applications in composite materials. The development of carbon fibers approaching theoretical strengths and stiffness is a continuing process which has led to improved mechanical and physical properties over the recent years. Improvements in carbon fiber properties are directly dependent on the quality of the precursor fiber. Research and development of PAN precursor fiber requires extensive experimentation to determine how processing conditions affect the structure and properties of the precursor fibers. Therefore, it is the goal of this thesis to analyze the results of varying coagulation rates on fiber shape, density and porosity, to determine the effect of cross-sectional shape, density, and fiber diameter on the tensile strength of the fiber, and to investigate the most effective method for the reduction of fiber diameter. Results indicate a low temperature, high solvent concentration coagulating bath leads to a rounder cross section with lower void content. Reduction in fiber diameter was found to increase tensile strength while increased molecular orientation experienced during high draw down ratios led to an increase in fiber modulus.
103

Women, whorls and wheels

Plummer, Janilee L. 24 July 2010 (has links)
Spinning, a task modern western society has eliminated from the list of household chores, was once a staple of every medieval woman’s life. This facet of medieval women’s work should not be neglected, since its shift appears to play a fundamental role in allowing industrialization through relocation of workload. When the new tool, the spinning wheel, was added to a woman’s possible ways of finishing this task, was it universally adopted? A look at the pervasive task from three perspectives shows that this new tool was slowly accepted and did not replace the original tool, the spindle. These perspectives are, first a literary review of how and when the term spinning wheel entered the the the cultural vocabulary. The second is a pictorial review of what type of spinning implements are shown in artwork and when the spinning wheel joins these pictures. An archaeological review of spindle whorls form York and Sweden to see if the introduction of the spinning wheel can be inferred from their inertial values is last. / Access to thesis permanently restricted to Ball State community only / Department of Anthropology
104

Análisis, desarrollo y evaluación de un plan de entrenamiento sobre bicicletas estáticas ESBE

Ríos Zorrilla, Marco Antonio 04 December 2013 (has links) (PDF)
Este trabajo de tesis propone desarrollar y evaluar un plan de entrenamiento realizado en bicicletas estáticas. El hecho de haber estado inmerso en esta actividad durante 11 años me permite aportar conocimientos prácticos al tema. Trabajé en esto desde el 2002 al 2004 en los gimnasios Laureles, Match, Santillana y Ser Activo en Medellín, Colombia. En la ciudad de La Plata trabajé durante el 2005 en los gimnasios La Horqueta y Palestra, y a partir del 2006 únicamente en el gimnasio La Horqueta hasta que regresé a Colombia en el año 2008. En este último gimnasio es donde se llevó a cabo el desarrollo del programa de entrenamiento, las pruebas y también las encuestas. Luego del regreso a Colombia se retomo el trabajo con bicicletas estáticas hasta noviembre del 2012. Hasta el momento, y a pesar de la gran aceptación que tiene el ciclismo de salón en el mundo, no existe ninguna investigación donde se analice el impacto de este tipo de actividad. Para este trabajo se hizo una adaptación de los planes de entrenamiento para el ciclismo profesional de alto rendimiento a las posibilidades del entrenamiento de personas que llevan una vida cotidiana, especialmente mujeres no deportistas que concurren a un gimnasio. El propósito de este trabajo es investigar el impacto y la repercusión funcional de este tipo de entrenamiento, así como la percepción en la calidad de vida de los practicantes. Para este trabajo se revisaron una serie de libros y documentos, principalmente de ciclismo, debido al limitado número de publicaciones científicas en el campo específico del entrenamiento con bicicletas estáticas. Las conclusiones de este estudio son muy importantes, aunque debe tenerse en cuenta que se utilizó un número limitado de participantes y, sin duda, harán falta investigaciones posteriores para profundizar las conclusiones de la presente tesis. Se contó con la colaboración de usuarios practicantes para responder las encuestas, y para las evaluaciones se optó por trabajar con personas que pasaban de la inactividad total a ejercitarse 2 y 3 veces por semana.
105

Polyacrylonitrile/carbon nanotube composite fibers

Chae, Han Gi January 2008 (has links)
Thesis (M. S.)--Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Satish Kumar; Committee Member: Anselm Griffin; Committee Member: Dong Yao; Committee Member: Naresh Thadhani; Committee Member: Samuel Graham
106

The development of cotton spinning and weaving industries in Hong Kong, 1946-1966

Mok, Ching-heng, Marina. January 1968 (has links)
Thesis (M.A.)--University of Hong Kong, 1969. / Also available in print.
107

Kadenssensor med en accelerometer och ANT+

Westerholm, Glenn January 2015 (has links)
Rapporten presenterar det examensarbetet som har gått ut på att undersöka möjligheterna att konstruera en sensor som mäter kadens med hjälp av en accelerometer. Implementation av kadensprofilen till ANT+ har gjorts för att möjliggöra synkronisering mellan en sportklocka och sensorn. Kadens är hur fort cyklisten trampar med pedalerna mätt i enheten Varv per minut vanligt förkortat RPM från engelskans Revolutions Per Minute. Hur fort en cyklist trampar påverkar kroppen på många olika sätt och ofta vill cyklisten veta vad aktuell kadens är för att optimera sin prestation. Den undersökta principen att använda en accelerometer för att mäta kadens syftar till att en eventuell prototyp skulle vara lämplig till inomhuscykling även kallad spinning. På en vanlig traditionell cykel har man oftast två hårdvarudelar för att mäta kadens, en monterad på pedalarmen och den andra på cykelramen. Cykelramen på en spinningcykel skiljer sig så pass mot en vanlig cykel att hårdvarudelen som ska sitta på cykelramen inte kan monteras med samma lätthet. Med en accelerometer behövs bara en hårdvarudel som lätt kan monteras på pedalarmen på cykeln. Programutvecklingen har skett med ett Arduino Uno  som består av en ATmega328 mikrokontroller från Atmel. Sensorenheten som mäter kadensen består av Arduino Uno, accelerometern LSM303DLHC från STMicroelectronics och ANT-chippet nRF24AP2 från Nordic Semiconductor. Huvudenheten har bestått av en persondator som har agerat mottagare med programmet ANT+ Simulator. Det utvecklade programmet på mikrokontrollen upptäcker när det sker ett pedalvarv och skickar den totala varvtiden tillsammans med antal pedalvarv som totalt inträffat till nRF24AP2 vidare till huvudenheten. Kadensprofilen är den som räknar ut vad aktuell kadens är. Avslutningsvis presenteras ett minimumkrav av hårdvaran och ett förslag av en energisnål mikrokontroller för en eventuell prototyp.
108

Peptide processing via silk-inspired spinning enables assembly of multifunctional protein alloy fibers

Jacobsen, Matthew Michael 10 July 2017 (has links)
Diverse fiber-forming proteins are found in nature that accomplish a wide range of functions including signaling, cell adhesion, and mechanical support. Unique sequence characteristics of these proteins often lead to their specialized roles. However, these proteins also share a common organizational hierarchy in primary and secondary structures that strongly influence both their intramolecular folding and intermolecular interactions. Based on what is known regarding protein fiber assembly of silk peptides, shear-induced elongation of the molecular strands drives interchain secondary structure crystallization via anisotropic alignment, which creates a molecular superstructure that forms the basis a fiber network. In this work, the hypothesis is this type of protein fiber assembly is not unique to silk sequences and that other proteins can be spun into fibers in similar fashion while maintaining unique functionality given by their specialized amino acid sequences such as RGD, GX1X2, and so forth. This was investigated by modeling the manner in which hydrophobic and hydrophilic blocks of amino acids create interacting secondary structures at the chain level when exposed to shear. It was determined computationally and then verified experimentally that fiber spinning success is most likely to occur after shear processing if the protein sequence exhibits a balance of hydrophobic and hydrophilic content and has sufficient length. Applied to the biological scale, both pure and mixed solutions of proteins such as fibronectin, laminin, and silk fibroin were spun into fibers. In particular, alloy protein fibers of silk fibroin mixed with fibronectin exhibited the characteristic mechanical integrity of silk and the bioactivity of fibronectin. This simple method of creating protein fibers with hybrid characteristics is significantly faster, less expensive, and less technically intensive than chimeric protein production, which purports to do the same. This finding also provides insight into a fundamental means by which protein fibers may be assembled in vivo by taking advantage of the thermodynamically favorable assembly of peptide sequences at the chain level under proper molecular orientation. Taken together, a high throughput means of producing a wide-range of pure and hybrid protein fibers has been developed for various biological applications and research investigations into the fibrous elements of biology.
109

Är det möjligt att tillverka antibakteriellt papper med hjälp av kitosan fibrer? / Is it possible to make antibacterial paper using chitosan fibers

Junel, Kristina January 2015 (has links)
Fibers are classified into two groups; natural fibers and man-made fibers (MMF). There are three kinds of MMF: those made by transformation of natural polymers, those made from synthetic polymers and those made from inorganic material. Chitosan is classified as a biobased polymer and can be spun into man-made fibers. Due to its various functions, including anti-microbial, biocompatibility, biodegradability, metal-chelating, metal ions-coupling properties and general high molecular affinity, much attention has been paid recently to include chitosan into various concepts. The overall aim of this master thesis was to investigate the possibilities to make an antibacterial paper. Because chitosan contain primary amino groups that are cationic under mildly acidic conditions, it has antibacterial properties. Lab scale spinning of chitosan filaments was attempted in order to produce chitosan staple fibers that could be mixed with pulp fibers to make paper with antibacterial properties. Spinning methods used for a particular polymer is determined by the characteristics of the polymer. In the development of chitosan spinning at laboratory scale three different spinning methods were tested. A successful filament was produced by dry wet spinning. The filament was superior to the others in terms of dope composition and weight ratio of chitosan/acetic acid for protonation of the amino groups. Furthermore, the addition of glycerol improved the swelling of the chitosan hydrogel (or dope). Moreover, the condition of the coagulation step resulted in a good solidified filament with satisfactory elasticity and strength to be able to be taken up by a drawing cylinder. However, too small amounts of chitosan were produced in the development of chitosan spinning at lab scale and for production of antibacterial paper of chitosan. A second option was melt spinning of polylactide (PLA) filaments containing various amounts of chitosan. In this case PLA act as a carrier of chitosan into the paper sheet. Continuous filaments were spun in a sufficient amount. The antibacterial activity of PLA/chitosan fibers on E. coli bacteria was tested both on PLA/chitosan fibers as well as on suspensions. Under nutrient free conditions weak antibacterial effects was observed both for fibers and suspensions. However, in a more nutrient rich environment no effect was observed. This suggests that the produced fibers only had a weak antibacterial activity. To my knowledge the use of PLA in fiber form to carry chitosan into paper has not been attempted previously although different approaches to use chitosan as e.g. wound dressing is well described. In conclusion, there is a possibility to produce man made biodegradable fibers using chitosan and PLA that potentially could be added to paper. This paper might exert antibacterial properties that could have an interest to the market, e.g. for cleaning, in hospitals, and in the food industry.
110

The Development and Application of In Situ NMR Methods for Lithium-Ion Batteries

Freytag, Annica I. January 2020 (has links)
This body of work is tackling some of the challenges in the field of lithium-ion batteries (LIBs) for electric vehicles through in situ nuclear magnetic resonance (NMR). In situ NMR allows for the simultaneous monitoring of both liquid and solid components (electrolyte, cathode, anode, separator) and provides timely data acquisition making it a great method to extract real-time information about structural changes, degradation products and failure mechanisms in batteries. A combined in situ 7Li NMR and ex situ 29Si magic-angle spinning (MAS) NMR study on silicon and silicon monoxide was used to compare structural differences in these anode materials using a custom-made in situ cell. Some key differences between the two materials were obtained, highlighting the importance of in situ NMR to be used for identifying phases, which are not present under ex situ conditions. In addition, fast charging of silicon anodes was investigated to gain a better understanding of their performance at high current rates. Magnetic resonance imaging was also implemented to localize lithium metal deposition under these conditions, which was made possible by a unique in situ parallel-plate resonator setup. Finally, the successful development of a novel in situ MAS NMR technique is introduced, which for the first time allows for an in situ analysis of a LIB under MAS. This strategy paves the way toward acquisition of valuable in situ data on the formation and transformations of metastable states within the active materials of both electrodes; data that is difficult to obtain from static in situ NMR experiments alone. / Thesis / Doctor of Philosophy (PhD)

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