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1
Coquelet, Hugo. « Expression hétérogène des ARNt et fonctions non canoniques de la tyrosyl-ARNt synthétase (YARS) dans la régulation de la sénescence chimio-induite et son échappement ». Electronic Thesis or Diss., Angers, 2025. http://www.theses.fr/2025ANGE0005.
Texte intégralRésumé :
La sénescence est un processus physiologique induit en réponse à différents stress tels que l’érosion télomérique, l’expression d’oncogènes ou l’exposition à des traitements de chimiothérapie. Sa mise en place permet de bloquer la prolifération d’une population cellulaire transformée, limitant ainsi le développement tumoral. Néanmoins, cet arrêt prolifératif est parfois réversible, conduisant certaines cellules à échapper à la sénescence et à acquérir des capacités tumorales supplémentaires. Dans ce contexte, la sénescence est donc considérée comme un mécanisme pouvant potentialiser le développement de cancers. Lors de ce travail, nous nous sommes intéressés à mieux comprendre et caractériser les mécanismes régulant la sénescence et sa stabilité. Dans un premier temps, nous avons étudié la régulation de l’ARN polymérase III par la protéine mTORC1 ainsi que l’expression spécifique de certains ARNt, notamment Tyr-GTA (5.3) et Leu-CAA (2.1). Cette régulation hétérogène de certains ARNt pourrait traduire une réorganisation plus large du pool d’ARNt lors de la sénescence, influençant ainsi la synthèse protéique pour soutenir ou déstabiliser ce phénotype. Par la suite, nous avons caractérisé de nouvelles fonctions non canoniques de la tyrosyl-ARNt synthétase (YARS). Cette dernière migre dans le noyau et régule l’activité de l’ARN polymérase II afin de contrôler la transcription du gène LIN9, un régulateur clé du cycle cellulaire. Le blocage de cette fonction non canonique suffit à induire un phénotype sénescent, suggérant une implication de YARS dans l’établissement de ce mécanisme suppresseur. Ainsi, la sénescence est caractérisée par l’implication de nombreux effecteurs de la traduction, un processus encore peu étudié dans ce contexte, et qui pourrait représenter un point clé dans la compréhension des mécanismes influençant sa mise en place et sa stabilitéSenescence is a physiological process triggered in response to various stressors, such as telomeric erosion, oncogene expression, or exposure to chemotherapy treatments. Its implementation halts the proliferation of a transformed cell population, thereby limiting tumor development. However, this proliferative arrest is sometimes reversible, allowing certain cells to escape senescence and acquire additional tumorigenic capabilities. In this context, senescence is considered a mechanism that may potentiate cancer development. In this work, we aimed to better understand and characterize the mechanisms regulating senescence and its stability. First, we studied the regulation of RNA polymerase III by the mTORC1 protein as well as the specific expression of certain tRNAs, notably Tyr-GTA (5.3) and Leu-CAA (2.1). This heterogeneous regulation of certain tRNAs may reflect a broader reorganization of the tRNA pool during senescence, thereby influencing protein synthesis to either support or destabilize this phenotype. Subsequently, we characterized novel non-canonical functions of tyrosyl-tRNA synthetase (YARS). This enzyme migrates to the nucleus and regulates RNA polymerase II activity to control the transcription of the LIN9 gene, a key cell cycle regulator. Blocking this non-canonical function is sufficient to induce a senescent phenotype, suggesting the involvement of YARS in establishing this suppressive mechanism. Thus, senescence is characterized by the involvement of numerous translation effectors—a process still poorly studied in this context—that could represent a key point in understanding the mechanisms influencing its establishment and stability
2
Tang, Nelson K. H. « The design and construction of a prototype yarn brushing machine to produce novel brushed yarns ». Thesis, University of Huddersfield, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292286.
Texte intégral
3
Smigielski, Edward. « The effect of batch yarn felting on the properties of wool carpets and carpet yarns ». Thesis, University of Leeds, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327778.
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4
He, Jingwu. « The role of yarn structure on the hand related low-stress mechanical behavior of enzyme treated yarns by Jingwu He ». Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/9491.
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5
Goksoy, M. « A study of yarn-on-yarn abrasion ». Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382649.
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6
Leslie, Lauren Diana. « Sorting Yard ». The University of Montana, 2009. http://etd.lib.umt.edu/theses/available/etd-06232009-141416/.
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7
Mejía, Meléndez Gianmarco Alessandro, Lachira Luis Felipe Pachas, Rabanal Luis Alejandro Pareja, Palomino Dámaris Sotelo et Pino Santiago Syou Yamamoto. « Proyecto : Yara ». Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2019. http://hdl.handle.net/10757/651850.
Texte intégralRésumé :
El presente trabajo trata de la idealización y estructuración de un aplicativo móvil cuya finalidad es devolverle la sensación de seguridad a quien la utilice. Esta aplicación fue diseñada pensando en los ciudadanos de Lima metropolitana y su constante temor a ser víctimas de algún acto delictivo. En la última década, el 95% de ciudadanos limeños se sienten inseguros dentro de su día a día, sintiendo desconfianza por las autoridades y su entorno social. La aplicación YARA busca remediar la poca falta de alternativas de prevención contra delitos que existe en la actualidad, ofreciendo un dispositivo que brinde las herramientas necesarias para que los ciudadanos se mantengan siempre precavidos y alertas para evitar estas situaciones.
Para la estructuración de este proyecto, se tomó en cuenta las necesidades más importantes que los ciudadanos limeños buscan satisfacer con respecto a la inseguridad ciudadana. Necesidades tales como nivel de inseguridad de las zonas, acceso rápido a las líneas de emergencia disponibles, ayuda colectiva de la comunidad limeña, entre otras más que formarán y fortalecerán una cultura de prevención ante actos delictivos, con colaboración de la comunidad y las autoridades.This paper is about the idealization and structuring of a mobile application whose purpose is to restore the feeling of security to the users. This application was designed with for Lima citizens in mind and their constant fear of being victims of some criminal act. In the last decade, 95% of Lima citizens feel insecure within their daily lives, feeling distrust of the authorities and their social environment. YARA is an application which seeks to remedy the little lack of crime prevention alternatives that currently exists, offering an app that provides the necessary tools so that citizens always remain cautious and alert to avoid these situations. For the structuring of this project, the investigation takes the most important needs that Lima citizens seek. Needs such as the insecurity’s level in the areas, quick access to the emergency lines, collective help from the Lima community, among others that will form and strengthen a culture of prevention against criminal acts, with the collaboration of the community and the authorities.
Trabajo de investigación
8
Daniel, Latson Trudie I. « A GRIOT’S YARN ». Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1310406150.
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Chang, Lingli, et mikewood@deakin edu au. « An investigation of yarn hairiness ». Deakin University. School of Engineering and Technology, 2002. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20060823.141926.
Texte intégralRésumé :
Yarn hairiness affects not only the quality of products, but also the productivity in spinning and weaving. Too much yarn hairiness is undesirable for many end uses as well as the spinning and post spinning processes. The main aims of this project are to examine the hairiness features of various yarns and to reduce yarn hairiness. The thesis covers five related areas hairiness assessment, factors affecting yarn hairiness, the hairiness of newly developed yarns, yarn hairiness reduction, and effect of yarn hairiness on the energy consumption in ring spinning.
The worsted cashmere, pure wool and wool/cashmere blend yarns were employed to investigate the effect of some fibre parameters on the yarn hairiness. A single exponential distribution of the hair-length was confirmed first, using the data from the Zweigle G565 Hairiness Meter. A linear relationship was observed between the blend ratio and the hairiness indexes. In particular, the effect of fibre crimp or curvature on yarn hairiness is examined. The theory of yarn hairiness composition was also developed further.
The effect of draft ratio and spindle speed on the hairiness of worsted wool yarn was examined next with a factorial experiment design. Several new hairiness indexes, namely the relative hairiness indexes, have been used to explain the results obtained.
In the investigation of the hairiness of newly developed yarns, the hairiness of the Compact Spun and Roller-Jet-Spun yarns was examined first. The composition of the yarn hairiness, the hair-length distribution, and the effect of test speed on yarn hairiness were then studied. An important finding is that for both yarns, the predominant hairiness feature is the looped hairs.
A comparison of the hairiness of Solospun yarns and the equivalent ring spun wool yarns was undertaken. The hair-length distribution of the Solospun yarn was examined first. The Solospun yarns used had fewer hairs in most hair-length groups and lower variations in hairiness. In addition, the effect of twist level and spindle speed on the hairiness of Solospun and conventional ring spun yarns has also been discussed.
A novel approach of reducing yarn hairiness spinning with a Diagonal yarn path was examined next. Both Left Diagonal and Right Diagonal yarn arrangements were studied. A new finding is that the Right Diagonal yarn path leads to reduced hairiness for the Z-twist yarn, while yarn evenness and tenacity are not as sensitive to the modified yarn path. The mechanism of hairiness reduction with the Diagonal yarn path has been discussed. The spinning performance of Right Diagonal yarn arrangement has also been evaluated.
Finally, the effect of yarn hairiness on the energy consumption in ring spinning has been investigated theoretically and experimentally. A theoretical model has been developed, which represents the first attempt at theoretically investigating the influence of yarn hairiness on energy consumption during the winding stage of ring spinning. The experimental results have generally confirmed predictions of this model. Recommendations for further research in this area have also been made in the concluding chapter of this thesis.
10
Giannokostas, Vasileios. « Policy-Driven YARN Launcher ». Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-204461.
Texte intégralRésumé :
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.
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Mirfakhrai, Tissaphern. « Carbon nanotube yarn actuators ». Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/17441.
Texte intégralRésumé :
The first demonstration of electromechanical actuation in carbon nanotubes (CNTs), aligned in the form of a twisted yarn, is presented in this thesis. Sheets of CNTs have been known to actuate when charged electrochemically. When an electric potential is applied between a sheet of CNTs and another electrode, both submersed in an electrolyte, the sheet expands. Actuation loads and stresses are low (< 33 MPa); this is partly due to the random orientation of CNTs in those sheets. When actuated under similar conditions, the yarns show significantly higher stress (2.0±0.4 x 10⁸ Pa) with similar strain (0.6 %). However, unlike the sheets, the yarns contract when the electric potential is applied; this is quite unexpected. The mechanism of this contraction is studied and is related to the insertion of ions in the yarn and the structural changes that take place in the yarn due to its helical twisted structure. A model is presented, relating the actuation strain with yarn geometry (diameter, twist rate, internal packing), electrolyte properties such as ion size, and applied potential. The actuation and mechanical properties of the yarn are studied in various electrolytes. Characterization techniques such as cyclic voltammetry and electrochemical impedance spectroscopy are employed to study the charge storage behaviour of the yarn, showing gravimetric capacitances between 10-60 F/g. It is also shown that the yarns can convert mechanical energy into electrical energy, and are thus capable of measuring mechanical forces. Their behaviour as mechanical force sensors is characterized, showing sensitivities about 2.0±0.6 x 10−⁵ V/MPa. The yarns are superior in work density to piezoelectric actuators when normalized by active material. Creep, can still be an issue, while a tensile modulus of about 16±5 GPa and a tensile strength of about 900 MPa mean that creep is much less than other types of artificial muscles at similar loads. Torsional actuation is also shown to take place if one end of the yarn is free to rotate. Thus, the CNT yarn actuators show the highest achieved stress among polymer artificial muscles and are the first to actuate torsionally, opening a wide range possibilities for applications.
12
Sumner, Mark. « Continuous yarn processing systems ». Thesis, University of Manchester, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.601466.
Texte intégralRésumé :
The objective of the Engineering Doctorate project was the development of a continuous yam dyeing system which could meet the needs of a changing textile industry. Through an examination of the changes in the industry, it was found that the system must incorporate waste minimisation principles, be flexible and responsive to the demands of the fashion industry and provide the yam dyer with short lead times. Two yam processing systems were identified and investigated to determine whether they could be used to fulfil the aims of the project. The first system was based on the Fibre 'M' Yam Texturing and Dyeing process previously developed at UMIST. The second was a new development referred to as the Sealed Applicator Device (SAD). It had been shown in the past that the Fibre 'M' based system could simultaneously texture and dye polyester yam to a relatively high standard of fixation and bulk. However, through the process investigation presented here it was found that the system lacked flexibility, ease of use and, in addition, its environmental impact could be considerable. The investigation of the SAD process proved to be more fruitful. It was found that the SAD process could be used to impregnate single ends of yam with liquor to a high degree of accuracy and control. Laboratory trials sho~ed that the SAD system could be used to impregnate worsted yam with dye liquor levelly at yam speeds up to 500 m1min at liquor to goods ratios as low as 0.3 : 1. Also it was shown that the SAD system could be used as a high speed yam washing device as well as a yam drying device. Through a combination of the impregnation, washing and drying capabilities of the SAD process, in conjunction with an autoclave stage, it was demonstrated that the SAD process could be used to continuously dye, wash and dry yams at high speed to commercial standards of penetration, levelness and fastness. The potential savings for a yam dyer through the use of the SAD system were explored. It was also shown, through commercial trials, that the SAD system could be used as an integral part of a simultaneous yam folding, setting, conditioning and lubricating process for worsted yams. Comparable levels of setting, conditioning and lubricating to the industry standard were achieved using the SAD process, with the potential for considerable saving for the spinner.
13
Cartes, Kimberly, et Phatcha Petchrod. « Utformning och användning av växlingsgator på bangårdar, med hänsyn till arbetsmiljön : Ett förslag till regelverk ». Thesis, KTH, Byggteknik och design, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-287764.
Texte intégralRésumé :
Presently there are extremely high expectations on the railway in Sweden. As a result of the political will to strengthen the railways position in the transport market, a number of major railway projects have therefore been decided. However, the political ambition has also resulted in a greater need of capacity than before. Which has led to an overload of the Swedish railway network and therefore also wear of tracks, locomotives and wagons.Since the railway in comparison with for instance the car not always has been the most popular mode of transportation, then only a small part of the investment has been devoted to developing its system. This has resulted in matters and tasks within the area being greatly put aside. An example of a issue that has not been prioritized concerns guidelines for the shaping and usage of the walking ways on railway yards. At present, there are no guidelines for how these walking ways should look and be used, which has resulted in a number of injuries and accidents occurring among the workers.The purpose of this work is therefore to present new suggestions for the design and use of these walking ways. The goal has been to develop an overall assessment of the situation based on a visit to the railway yard in Hagalund, interviews with experts and an information gathering within the topic. This is intended to form the basis for the suggestions and in the future also for a safer environment for the workers.During the site visit to the depot in Hagalund, it was discovered that some of the walking ways in the yard were in need of maintenance. It turned out that they were not being filled up, because the stone fractions are considered to contaminate the macadam laying next to it. During the site visit, one saw how some of the streets disappeared among larger fractions and that there was macadam Class I on the yard, although it is not allowed to be there. With the help of the interviews, one could map out the reason why it looks like it does today at the depot in Hagalund. In the discussions with the various characters, there was clearly a need to renew and standardize the guidelines for how these walking ways should be built and maintained. With the help of the site visit and the interviews, our proposals for guidelines were developed. One proposal is at least a width of 0.7 m along streets intended for walking along existing tracks and 0.7-1 m along future ones.
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Goktepe, Fatma. « The effect of yarn structure on the deformation of the yarn cross-section ». Thesis, University of Leeds, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416091.
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Hasan, M. M. B., M. Offermann, M. Haupt, A. Nocke et Ch Cherif. « Carbon filament yarn-based hybrid yarn for the heating of textile-reinforced concrete ». Sage, 2014. https://tud.qucosa.de/id/qucosa%3A35610.
Texte intégralRésumé :
In this study, the application of carbon filament yarn (CFY)-based conductive hybrid yarn as the heating element in a textile-reinforced concrete structure is reported. For this purpose, a hybrid yarn having a core-sheath structure (the core is made of carbon filament yarn and the sheath consists of a mixture of short glass and polypropylene fibres) is manufactured by DREF-2000 spinning technique and integrated into textile structure by tailored fibre placement method. Heat can be generated in the concrete structure by passing electric current through the conductive carbon filament yarn core of the hybrid yarn using the principle of resistive heating, where the sheath acts as the protection and isolation layer. From the initial investigations made on a small concrete specimen, important information is gathered and a large concrete slab with integrated conductive hybrid yarn is manufactured. The heat ability and the comfort level of the manufactured concrete slab are measured. The investigations have revealed the potential of using such hybrid yarn for a pointwise heating of the concrete surface for possible appliance in outdoor furniture.
16
He, Peng. « Process-structure-property relationships of yarns produced on the card-spinning system ». Thesis, Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-06072004-131148/unrestricted/he%5Fpeng%5F200405%5Fms.pdf.
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Salda, Violeta B. « Ethnobotany and food uses of Philippine highland yams (Dioscorea) ». Thesis, Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B2132637X.
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Kuganesan, Srijeyanthan. « Distributed Resource Management for YARN ». Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187044.
Texte intégralRésumé :
In the last year, Hadoop YARN has become the defacto standard resource management platform for data-intensive applications, with support for a wide range of data analytics platforms such as Apache Spark, MapReduce V2, MPI, Apache Flink, and Apache Giraph. The ResourceManager fulfills three main functions: it manages the set of active applications (Applications service), it schedules resources (CPU, memory) to applications (the FIFO/Capacity/Fair Scheduler), and it monitors the state of resources in the cluster (ResourceTracker service). Though YARN is more scalable and fault-tolerant than its predecessor, the Job-Tracker in MapReduce, its ResourceManager is still a single point of failure and a performance bottleneck due to its centralized architecture. Single point of failure problem of YARN has been addressed in Hops-YARN that provides multiple ResourceManagers (one active and others on standby), where the ResourceManager’s state is persisted to MYSQL Cluster and can quickly be recovered by a standby ResourceManager in the event of failure of the active ResourceManager. In large YARN clusters, with up to 4000 nodes, the ResourceTracker service handles over one thousand heartbeats per second from the nodes in the cluster (NodeManagers), as such become a scalability bottleneck. Large clusters handle this by reducing the frequency of heartbeats from NodeManagers, but this comes at the cost of reduced interactivity for YARN (slower application startup times), as all communication from the ResourceManager to NodeManagers is sent in response to heartbeat messages. Since Hops-YARN is still using a centralized scheduler for all applications, distributing the ResourceTracker service across multiple nodes will reduce the amount of heartbeat messages that need to be processed per ResourceTracker, thus enabling both larger cluster sizes and lower latency for scheduling containers to applications. In this thesis, we will scale-out the ResourceTracker service, by distributing it over standby ResourceManagers using MySQL NDB Cluster event streaming. As such, the distributed Resource Management for YARN that is designed and developed in this project is a first step towards making the monolithic YARN ResourceManager scalable and more interactive.
19
Durur, Gungor. « Cross winding of yarn packages ». Thesis, University of Leeds, 2000. http://etheses.whiterose.ac.uk/4047/.
Texte intégralRésumé :
Random winding is widely used for the preparation of yarn packages used in a variety of textile processes. Ribboning caused by overwinding of yarn turns at certain places within the package is a basic problem encountered in this process. Standard random winders incorporate some means of ribbon breaking, which strictly speaking have limited effectiveness. The research reported in thesis was undertaken to realise a random winder capable of detecting the occurrence of ribboning, and taking the ribbon breaking action at these precise times, and thereby achieve 'active' ribbon breaking. Such a winder was realised by the addition of suitable transducers to a standard random winder, which could be controlled by a PC. Winding trials carried out using this equipment established the effectiveness of the concept and also the greater freedom from ribboning the method achieved in comparison with other available methods. Unwinding trials carried out by suitably modifying the winder for measuring yarn unwinding tension were also used to establish the effectiveness of active ribbon breaking. Preliminary experiments carried out on the above apparatus showed the possibility of constructing a Angle of Double Traverse (ADT) diagram on the VDU of the PC during winding operations, which could serve as a useful aid to follow the progress of the winding operation. It was very useful for showing the occurrence of major and minor ribboning in the wound package, and also for visually indicating the effectiveness of the ribbon breaking procedures. The diagram was of further use in studying the nature of package driving by the grooved drum. The case of driving a deformable body such as a yarn package on a comparatively non-deformable grooved drum is important for understanding how the package rotates without any obvious slipping. By varying the winding conditions, it was in fact shown that some measurable slip occurs, and these relationships were experimentally established. Computer simulation is useful to determine the stresses within a wound package, particularly as these cannot be measured using conventional techniques. The results of such a simulation carried out on a random wound package and the comparison of the results with those obtained for a precision wound package are also presented.
20
Jurkow, Gillian. « Rediscovering and recovering the front yard, a study of garden yard meaning and owner attitudes ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ53164.pdf.
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Kravaev, Plamen, Steffen Janetzko, Thomas Gries, Bong-Gu Kang, Wolfgang Brameshuber, Maike Zell et Josef Hegger. « Commingling Yarns for Reinforcement of Concrete ». Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1244040840310-74290.
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Textile reinforced concrete (TRC) is an innovative composite material, which is being intensely and practice-oriented investigated on national and international level. In the last few years this material has gained increasing importance in the field of civil engineering. In the context of the collaborative research project SFB 532 at the RWTH Aachen University, research was carried out to understand and to predict the behaviour of different yarn structures in fine grained concrete. Based on the results, innovative commingling yarns were made of alkali-resistant glass fibres and water soluble PVA. These hybrid yarns have an open structure, which improves the penetration of the textile reinforcement by the concrete matrix. Hence, the load bearing capacity of TRC structural elements was significantly improved. This paper presents a technique for the production of such commingling yarns for concrete applications. The mechanical properties of the new yarns are determined due to tensile stress tests. The bond behaviour of the commingling yarns was investigated by pull-out- and tensile stress tests on TRC-specimens. The results of the different tests are being presented and briefly discussed.
22
Overington, Y. H. « Aspects of hollow spindle fancy yarn ». Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556105.
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Knipprath, Christian. « Mechanical performance of binder yarn composites ». Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/6774.
Texte intégralRésumé :
This investigation concerns the mechanical response of binder coated carbon tow preforms and laminates. The main focus is on evaluating and modelling the robustness of preforms whilst the methodologies developed are also applied to cured laminates produced using the binder coated preforms. Conventional manufacturing techniques were altered to address the differences in behaviour due to the presence of the binder with the development of infusion schedules. These involve lower temperatures, which eliminate the possibility of binder reactivation during processing. Different development versions of the material in the form of an inhomogeneously or homogeneously bindered tow were characterised in terms of their mechanical response in the preform state. It was observed that the inhomogeneously bindered material had higher modulus and strength in both tension in the fibre direction and shear, while the behaviour of the homogeneous preform is significantly more robust in the transverse to the fibre direction. Laminates produced, using the homogeneously bindered material, were compared to a reference unbindered laminate system, using an aerospace epoxy as a matrix. The out-of-plane properties of the material with binder were superior to the reference laminate, whereas in-plane properties were similar or inferior. The development of models of the mechanical response built around continuum damage mechanics models allowed the simulation of the behaviour of preforms under loading. The implementation of these constitutive models necessitated the development of appropriate parameter estimation techniques capable of solving the inverse problem of identifying the values of 27 material constants that minimise the error between experimental and modelling results. Two novel methodologies were developed and compared to a conventional technique following simplified laminate analysis. The first method performed a gradient-based error minimisation and the second uses the Markov Chain Monte Carlo technique. The gradient-based technique results in a close fit, while this method requires proper definition of the constraints to yield an appropriate solution set. Markov Chain Monte Carlo yields satisfactory results with the additional advantages of overcoming the ill-posedness of the inverse problem without regularisation and providing an output in the form of multivariate probability distributions that can be used directly instochastic simulations. The material parameters obtained and the corresponding constitutive models were used in finite element models of the mechanical response of preforms and laminates. The models were based on the concept of a combination of shell elements representing sub-laminates and cohesive elements simulating the delamination behaviour of interfaces between them. The performance of the models was evaluated using the case of impact of a spar section for preforms and three point bending for the laminates. The agreement between experimental and simulation results was satisfactory. The validated model was used in the context of a design case study based on a helicopter pitch horn component. The aim was to use the results of a draping analysis in the finite element model to evaluate the effects of the assumption of nominal fibre orientations on design and to combine the results of drape optimisation in respect to fibre shear angle with finite element analysis incorporating damage. The results showed that the use of nominal fibre orientation predicts a good performance of the component, whereas the influence of optimising draping on the mechanical performance was inferior.
24
Sunaryo. « Multi-yard ship construction and productivity ». Thesis, University of Strathclyde, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388338.
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Kelly, Jack, et Jim Walworth. « Managing Caliche in the Home Yard ». College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2002. http://hdl.handle.net/10150/144769.
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Millman, Michael Peter. « Computer vision for yarn quality inspection ». Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/34196.
Texte intégralRésumé :
Structural parameters that determine yarn quality include evenness, hairiness and twist. This thesis applies machine vision techniques to yarn inspection, to determine these parameters in a non-contact manner. Due to the increased costs of such a solution over conventional sensors, the thesis takes a wide look at, and where necessary develops, the potential uses of machine vision for several key aspects of yarn inspection at both low and high speed configurations. Initially, the optimum optical / imaging conditions for yarn imaging are determined by investigating the various factors which degrade a yarn image. The depth of field requirement for imaging yarns is analysed, and various solutions are discussed critically including apodisation, wave front encoding and mechanical guidance. A solution using glass plate guides is proposed, and tested in prototype. The plates enable the correct hair lengths to be seen in the image for long hairs, and also prevent damaging effects on the hairiness definition due to yarn vibration and yarn rotation. The optical system parameters and resolution limits of the yarn image when using guide plates are derived and optimised. The thesis then looks at methods of enhancing the yarn image, using various illumination methods, and incoherent and coherent dark-field imaging.
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Kanesan, Jayaprakash, et 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.
Texte intégralRésumé :
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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Demir, Ali. « The air-jet yarn texturing process with particular reference to nozzle design and improved yarn test methods ». Thesis, Loughborough University, 1987. https://dspace.lboro.ac.uk/2134/12477.
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Rypl, Rostislav, Rostislav Chudoba, Miroslav Vorechovský et Thomas Gries. « Evaluation of the Length Dependent Yarn Properties ». Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-77843.
Texte intégralRésumé :
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.
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Allen, Keith John. « Friction spinning : an investigation of yarn formation ». Thesis, Loughborough University, 1991. https://dspace.lboro.ac.uk/2134/27571.
Texte intégralRésumé :
Friction spinning is a relative newcomer to textile technology. It has generated great interest because of its potential for wide application of certain problems regarding the quality of yarn produced at high output rates can be solved. General acceptance of the process is hindered by uncertainty as to its capability of producing yarns of sufficient strength at speeds greater than 300 m/min. (NB: as a guide, maximum output rates of competitive technologies are no more than 150 m/min.) Friction spinning appears to have no intrinsic self-limit to its maximum output rate, unlike ring and rotor spinning which are limited by centrifugal effects leading to excessive yarn breakages. The process will therefore provide something of a quantum leap in output if acceptable yarn quality is achieved.
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Andersson, Robin. « GPU integration for Deep Learning on YARN ». Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-222357.
Texte intégralRésumé :
In recent years, there have been many advancements in the field of machine learning and adoption of its techniques in many industries. Deep learning is a sub-field of machine learning that is largely attributed to many of recent innovative applications such as autonomous driving systems. Training a deep learning model is a computationally intensive task that in many cases is inefficient on a CPU. Dramatically faster training can be achieved by making use of one or more GPUs, coupled with the need to train more complex models on increasingly larger datasets, training on a CPU is not sufficient. Hops Hadoop is an Hadoop distribution that aims to make Hadoop more scalable, by migrating the meta-data of YARN and HDFS to MySQL NDB. Hops is currently making efforts to support distributed TensorFlow. However, GPUs are not currently managed natively by YARN, therefore, in Hadoop, GPUs cannot be scheduled to applications. That is, there is no support for isolating GPUs to applications and managing access to applications. This thesis presents an architecture for scheduling and isolating GPUs-as-aresource for Hops Hadoop. In particular, the work is constrained to supporting YARN’s most popular scheduler, the Capacity Scheduler. The architecture is implemented and verified based on a set of test cases. The architecture is evaluated in a quantitative approach by measuring the performance overhead of supporting GPUs by running a set of experiments. The solution piggybacks GPUs during capacity calculation in the sense that GPUs are not included as part of the capacity calculation. The Node Manager makes use of Cgroups to provide exclusive isolation of GPUs to a container. A GPUAllocator component is implemented that keeps an in-memory state of currently available GPU devices and those which are currently allocated locally on the Node Manager. The performance tests concluded that the YARN resource model can be extended with GPUs, and that the overhead is negligible. With our contribution of extending Hops Hadoop to support GPUs as a resource, we are enabling deep learning on Big Data, and making a first step towards support for distributed deep learning.De senaste åren har många framsteg gjorts inom maskininlärning och användning av dess tekniker inom många olika industrier. Djupinlärning är ett delområde inom maskininlärning som är hänförlig till många av de senaste innovativa applikationerna såsom system för autonom bilkörning. Att träna en djupinlärningsmodell är en beräkningsmässigt intensiv uppgift som i många fall är ineffektivt på endast en processor. Dramatiskt snabbare träning är möjlig genom att använda en eller flera grafikkort, kopplat med behov att träna mer komplexa modeller med större datamängder, är det inte hållbart att endast träna på en processor. Hops Hadoop är en Hadoop distribution med målet att göra Hadoop mer skalbart, genom att migrera metadata från YARN och HDFS till MySQL NDB. Hops utför i nuläget ett arbete med att stödja distribuerad TensorFlow. För närvarande finns inget stöd för grafikkort som en resurs i YARN, därmed, i Hadoop, så kan grafikkort inte schemaläggas för applikationer. Mer specifikt, det finns inget stöd för att isolera grafikkort för applikationer och erbjuda som en resurs. Den här uppsatsen presenterar en arkitektur för att schemalägga och isolera grafikkort som en resurs i Hops Hadoop. Arbetet innefattar stöd för den mest populära schemaläggaren i YARN, kapacitets schemaläggaren. Arkitekturen implementeras och verifieras utifrån en mängd testfall. Arkitekturen utvärderas sedan i ett kvantitativt tillvägagångssätt genom att mäta tidspåverkan att stödja grafikkort genom att utföra ett antal experiment. Lösningen tar inte hänsyn till grafikkort som en del av kapacitetsberäkningen. Node Manager komponenten använder Cgroups för att utföra isolering av grafikkort. En GPUAllocator komponent har implementerats som håller ett tillstånd över vilka grafikkort som allokerats och vilka som är lediga på Node Manager. Experimenten konkluderar att YARN kan stödja grafikkort som en resurs och att tidspåverkan för detta är försumbart. Detta arbete med att stödja grafikkort som en resurs på Hops Hadoop, gör det möjligt att utföra djupinlärnin på stora datamängder, och är ett första steg mot stöd för distribuerad djupinlärning.
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Shaik, Asif Ur Rahman, Stefan Vlad, Pascal Rebreyend et Siril Yella. « Multi-agent simulation of sawmill yard operations ». Högskolan Dalarna, Datateknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:du-11791.
Texte intégralRésumé :
This paper reports the findings of using multi-agent based simulation model to evaluate the sawmill yard operations within a large privately owned sawmill in Sweden, Bergkvist Insjön AB in the current case. Conventional working routines within sawmill yard threaten the overall efficiency and thereby limit the profit margin of sawmill. Deploying dynamic work routines within the sawmill yard is not readily feasible in real time, so discrete event simulation model has been investigated to be able to report optimal work order depending on the situations. Preliminary investigations indicate that the results achieved by simulation model are promising. It is expected that the results achieved in the current case will support Bergkvist-Insjön AB in making optimal decisions by deploying efficient work order in sawmill yard.
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Jayaratne, Dehiwala Liyanagle. « Detection and differentiation of potyviruses affecting yams ». Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266999.
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Ho, Ping-Wing. « Discrete event simulation for yarn manufacturing processes ». Thesis, University of Huddersfield, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315679.
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Fasahat, F., R. Dastjerdi et M. R. M. Mojtahedi. « Thermophysiological Comfort by PA6/TiO2 Nanocomposite Yarns ». Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35603.
Texte intégralRésumé :
Thermophysiological comfort is one of the most important factors for people to choose desirable gar-ments, which can be evaluated via measuring permeability of body heat and sweat. In this paper the water vapor permeability of nanocomposite nylon 6 fabrics produced from melt spun nanocomposite yarns with different TiO2 nanoparticle concentrations have been investigated. Results from measuring water vapor permeability at different environment temperatures for 4 h. indicated that sample with 0.4 wt% of TiO2 nanoparticle can provide fabric with maximum comfort properties. At low temperature 27.5% decline of permeability as compared to pure fabric causes this sample to protect body from cool weather through pre-venting loss of body heat. By increasing temperature from 12 to 35 oC water vapor permeability enhance-ment of nanocomposite improved about 99% as compared to pure one. Consequently nanocomposite with suitable nanoparticle content can provide more comfortable fabrics in different temperatures and applica-tions.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35603
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Rollins, Lynnette S. « Revised lumber yard cost estimator work sample ». Online version, 2000. http://www.uwstout.edu/lib/thesis/2000/2000rollinsl.pdf.
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Rajamanickam, Rangaswamy. « Studies on fiber-process-structure-property relationships in air-jet spinning ». Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/8661.
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Hu, Xiao Ping. « Structure and properties of polyacrylonitrile fibres ». Thesis, University of Leeds, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366460.
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Madipally, Sunil veer Kumar. « Simulation of Sawmill Yard Operations Using Software Agents ». Thesis, Högskolan Dalarna, Datateknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:du-6026.
Texte intégralRésumé :
Bergkvist insjön AB is a sawmill yard which is capable of producing 350,000 cubic meter of timber every year this requires lot of internal resources. Sawmill operations can be classified as unloading, sorting, storage and production of timber. In the company we have trucks arriving at random they have to be unloaded and sent back at the earliest to avoid queuing up of trucks creating a problem for truck owners. The sawmill yard has to operate with two log stackers that does several tasks including transporting the logs from trucks to measurement station where the logs will be sorted into classes and dropped into pockets from pockets to the sorted timber yard where they are stored and finally from there to sawmill for final processing. The main issue that needs to be answered here is the lining up trucks that are waiting to be unload, creating a problem for both sawmill as well as the truck owners and given huge production volume, it is certain that handling of resources is top priority. A key challenge in handling of resources would be unloading of trucks and finding a way to optimize internal resources.To address this problem i have experimented on different ways of using internal resources, i have designed different cases, in case 1 we have both the log stackers working on sawmill and measurement station. The main objective of having this case is to make sawmill and measurement station to work all the time. Then in case 2, i have divided the work between both the log stackers, one log stacker will be working on sawmill and pocket_control and second log stacker will be working on measurement station and truck. Then in case 3 we have only one log stacker working on all the agents, this case was designed to reduce cost of production, as the experiment cannot be done in real-time due to operational cost, for this purpose simulation is used, preliminary investigation into simulation results suggested that case 2 is the best option has it reduced waiting time of trucks considerably when compared with other cases and it showed 50% increase in optimizing internal resources.
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Kakantousis, Theofilos. « Scaling YARN : A Distributed Resource Manager for Hadoop ». Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177200.
Texte intégralRésumé :
In recent years, there has been a growing need for computer systems that are capable of handling unprecedented amounts of data. To this end, Hadoop HDFS and Hadoop YARN have become the de facto standard for meeting demanding storage requirements and for managing applications that can process this data. Although YARN is a major advancement from its predecessor MapReduce in terms of scalability and fault-tolerance, its Resource Manager component that performs resource allocation introduces a potential single point of failure and a performance bottleneck due to its centralized architecture. This thesis presents a novel architecture in which the Resource Manager runs on a distributed network of stateless commodity machines as its state is migrated to MySQL Cluster, a relational write-scalable and highly available in-memory database. By doing so, the Resource Manager becomes more scalable as it can now run on multiple nodes as well as more fault-tolerant as arbitrary node failures do not result in state loss. In this work we implemented the proposed architecture for the Resource Tracker service which performs cluster node management for the Resource Manager. Experimental results validate the correctness of our proposal, demonstrate how it scales well by utilizing stateless Resource Manager machines and evaluate its performance in terms of request throughput, system resource and database utilization.
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Rashid, Zahin Azher. « Intelligent Scheduling for Yarn : Using Online Machine Learning ». Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-219607.
Texte intégralRésumé :
Many big companies who provide cloud infrastructure, platforms and services have to face a lot of challenges in dealing with big data and execution of thousands of tasks that run on servers. Thousands of servers running in cloud consume a large amount of energy which increases operating cost to a great extent for companies hosting infrastructures and platforms as services. Hundreds of thousands of applications are submitted every day on these servers by users. On submission of applications, somehow the total resources are not properly utilized which cause the overall operating cost to increase. A distribution of Apache Hadoop called HOPS is developed at SICS Swedish ICT and efforts are made to make it a better platform for institutions and companies. Yarn is used as the resource management and scheduling framework which is responsible for allocating resources such as memory and CPU cores to submitted applications. Yarn simply allocate resources based on the default set of values or what user has demanded. Yarn has no prior information about the submitted applications so it is very much possible that allocated resources are more or less than required. Energy is being wasted if fewer resources are required or application will probably not succeed if required more. In this research project, different techniques and methods are looked into for the collection of useful metrics related to applications and resources from Yarn, Spark and other sources. Machine Learning is becoming a very popular technique nowadays for the optimization of systems dealing with big data in a cloud environment. The goal is to collect these vital metrics and build a machine learning model to commission smart allocation of resources to submitted applications. This can help to increase the efficiency of the servers in the cloud and reduce the operating cost. Finally, a machine learning model was developed and memory and vCores were successfully predicted to be allocated to applications.Många stora företag som tillhandahåller molninfrastruktur, plattformar och tjänster måste möta många utmaningar när det handlar om stora data och utförandeav tusentals uppgifter som körs på servrar. Tusentals servrar som kör i molnetförbrukar en stor mängd energi vilket i hög grad ökar driftskostnaden för företag som tillhandahåller infrastrukturer och plattformar som tjänster. Hundratusentals applikationer skickas varje dag på dessa servrar av användare. Vid inlämning av ansökningar på något sätt utnyttjas inte de totala resurserna korrekt, vilket medför att de totala driftskostnaderna ökar. En distribution av Apache Hadoop, kallad HOPS, är utvecklad hos SICS Swedish ICT, och det görs ansträngningar för att göra den till en bättre plattform för institutioner och företag. Garn används som resurshanteringsoch schemaläggningsramen som är ansvarig för att allokera resurser som minne och CPU-kärnor till inlämnade applikationer. Garn fördelar helt enkelt resurser utifrån standardvärdet av värden eller vilken användare som har krävt. Garn har ingentidigare information om de inlämnade ansökningarna så det är mycket möjligtatt tilldelade resurser är mer eller mindre än vad som krävs. Energi slösas bort om färre resurser krävs eller ansökan kommer sannolikt inte att lyckas om det behövs mer. I detta forskningsprojekt undersöks olika tekniker och metoder för insamling av användbara mätvärden relaterade till applikationer och resurser från Garn, Spark och andra källor. Machine Learning blir idag en mycket populär teknik för optimering av systemsom hanterar stora data i en molnmiljö.Målet är att samla in dessa viktigamätvärden och bygga en maskininlärningsmodell för att beställa smart fördelning av resurser till inlämnade applikationer. Detta kan hjälpa till att öka effektiviteten hos servrarna i molnet och minska driftskostnaden. Slutligen utvecklades en maskininlärningsmodell och minnet och vCores hade framgångsrikt förutsagt att tilldelas applikationer.
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O'Loan, Timothy, et Tim OLoan@woodsbagot com au. « Urban Yards : Terraires Vagues of inner northern Melbourne ». RMIT University. Architecture and Design, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080513.142506.
Texte intégralRésumé :
This Masters of Landscape Architecture investigates the occurrence of small, temporary urban voids in inner northern Melbourne. The study asks whether these spaces operate as Public Domain (Hajer & Reijndorp 2001) and uses the concept of
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Kesici, Demet Akkaya Vahide Baysal. « Kortikosteroidlerle baskılanmış yara iyileşmesi üzerine Dietilaminoetil - Sefadeks'in etkisi / ». Isparta : SDÜ Tıp Fakültesi, 2003. http://tez.sdu.edu.tr/Tezler/TT00124.pdf.
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Farsi, Dooraki Babak. « Study of parameters affecting the strength of yarns ». Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98960.
Texte intégralRésumé :
Woven fibres and yarns are generally used in the form of a laminate embedded into a matrix. However, these materials are increasingly being used in the pure and the woven form such as fabric for ballistic protection clothing and confinement chambers for jet engines. These applications have created a demand for numerical modelling of the fabrics and more in depth information about the behaviour of fibrous materials and yarns. Manufacturers of yarns usually provide some quasistatic material parameters for the single fibre form of the material. However, this information cannot be scaled up linearly for a yarn consisting of many fibres. Also, the strain rate at which this information is obtained is not in the same order of magnitude as the strain rates observed in ballistic applications.The purpose of this study is to gain an understanding of parameters that affect the strength of yarns. Quasistatic and dynamic strength of various yarns are obtained using hydraulic and Hopkinson bar testing methods respectively and the rate dependency of the failure strength of each yarn is quantified. Weibull models are applied to each set of tests to observe whether the parameters obtained can be used as size independent material properties. The scaling effect will also be studied experimentally in order to observe the effect of specimen size to the failure stress of yarn.
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Zhou, Fenglei. « Flat Spinneret Electrospinning and Nanocoating for Hybrid Yarns ». Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508557.
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Smit, Eugene A. « Studies towards high-throughput production of nanofiber yarns ». Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/4785.
Texte intégralRésumé :
Thesis (PhD)--Stellenbosch University, 2008.ENGLISH ABSTRACT: Electrospinning is a simple yet versatile method used for producing nanofibers from various materials, including natural and synthetic polymers, polymer blends, ceramics and metals. The high specific surface areas, high aspect ratios (length/diameter), and the biomimicking nature of nanofibers make them ideally suited for application in diverse areas, including high-performance filtration, biomedical materials for tissue engineering scaffolds, wound dressings and controlled drug release, fiber-reinforced composites and highly sensitive nano-sensors. Two of the main requirements that need to be met for electrospun nanofiber materials to become commercially viable are: (1) a process for manufacturing continuous aligned nanofiber yarns, and (2) a drastic increase in the fiber production rate of the electrospinning process. The objectives of this study were to develop a scalable process for making continuous yarns of aligned electrospun nanofibers, and to develop a needleless electrospinning method for the high-throughput production of nanofibers. Three novel processes were developed while exploring innovative ways for making yarns from electrospun fibers. Finally, a fourth process, the so-called the NanoCaterpillar process, was developed. This process can be used as a scalable method for obtaining continuous yarns of aligned nanofibers. Advantages of the process include the requirement for relatively simple equipment, the simple process variations required for obtaining yarns of different linear densities, and the fact that, as a 'dry' process, it can be used to manufacture yarns from most materials that can be electrospun. The second goal of this study was to develop a needle-less electrospinning process, capable of making nanofibers at commercially viable throughput rates. The phenomenon of bubble electrospinning was discovered and developed further. Initial exploratory studies showed that bubble electrospinning could be employed to produce nanofibers from polymers in aqueous as well as organic solutions, and that the process follows similar trends to classic electrospinning such as the dependence of fiber diameter on polymer solution concentration and the possibility of including substances in the formed fibers by including them in the spin solution. A second, more in-depth study of the bubble electrospinning process revealed that fibers could be produced at very high rates with estimates, under ideal spinning conditions, reaching 5 kg/h per square meter of bubble bath surface. Furthermore it was found that fiber yield did not depend on the size or the lifetime per bubble. Investigations into several interesting aspects of bubble and jet behaviour during bubble electrospinning, such as child bubble formation and jet-splitting, led to predictive multiple linear regression models being fitted to the experimental data to describe process variables like yield per bubble, number of jets per bubble and fiber diameters.
AFRIKAANSE OPSOMMING: Die elektrospintegniek is 'n eenvoudige, dog veelsydige metode wat gebruik word om nanovesels van verskeie materiale, insluitend natuurlike en sintetiese polimere, polimeermengsels, keramieke, en ook metale te vervaardig. Die hoë spesifieke oppervlakareas, hoë lengte tot deursnee verhoudings en bio-naboodsende eienskappe van nanovesels maak hulle ideaalgeskik vir toepassing in uiteenlopende velde soos filtrasie, biomediese materiale vir weefselingenieurswese, wondbedekkings en beheerde vrystelling van geneesmiddels, veselversterkte saamgestelde materiale en hoogs-sensitiewe nanosensors. Twee van die hoofvereistes waaraan voldoen moet word, voordat elektrogespinde nanovesels kommersieël-lewensvatbaar kan word, is: (1) 'n proses vir die vervaardiging van kontinuë garings van gerigte nanovesels, en (2) 'n drastiese toename in die vervaardigingstempo van die elektrospinproses. Die doelwitte van hierdie studie was om 'n skalleerbare proses te ontwikkel vir die vervaardiging van kontinuë garings van gerigte nanovesels, en om 'n naaldlose elektrospinmetode te ontwikkel vir die hoë-uitset vervaardiging van nanovesels. Drie nuwe prosesse is ontwikkel tydens ondersoeke na innoverende maniere om garings van elektrogespinde nanovesels te vervaardig. Laastelik is 'n vierde proses, die sogenaamde NanoCaterpillar proses ontwikkel. Hierdie proses kan gebruik word as 'n skalleerbare metode vir die vervaardiging van kontinuë garings van gerigte nanovesels. Voordele van die proses sluit in dat relatief eenvoudige toerusting benodig word om die konsep toe te pas, dat slegs eenvoudige veranderinge aan die proses benodig word om garings van verskillende liniêre digthede te verkry, en dat die proses, synde 'n 'droë' proses, gebruik kan word om garings te maak van meeste materiale wat gespin kan word met die elektrospintegniek. Die tweede doelwit van hierdie studie was om 'n naaldlose elektrospinproses te ontwikkel wat nanovesels kon vervaardig teen kommersieël-lewensvatbare tempo's. Die borrelelektrospin verskynsel is ontdek en verder ontwikkel. Aanvanklike ondersoeke het getoon dat die borrelelektrospinproses gebruik kon word om nanovesels te vervaardig van polimere in water- sowel as organiese oplossings. Dit het ook getoon dat die proses soortgelyke tendense toon as die klassieke elektrospintegniek, soos die afhanklikheid van veseldeursnee aan polimeeroplossingkonsentrasie en die moontlikheid om ander stowwe in die gevormde vesels in te sluit deur dit aanvanklik in die spinoplossing in te sluit. 'n Verdere indiepte ondersoek van die borrelelektrospinproses het onthul dat vesels, onder geïdealiseerde omstandighede, vervaardig kon word teen baie hoë tempo's, na beraming 5 kg/h per vierkante meter borrelbadoppervlakarea. Verder is bevind dat die veselopbrengs nie afhanklik was van die borrelgrootte of -lewensduur nie. Ondersoeke na verskillende aspekte van die borrel- en polimeerstraalgedrag tydens die borrelelektrospinproses, soos die vorming van kind-borrels en polimeerstraalsplitsing, het gelei tot die passing van voorspellende meerfoudige liniêre regressiemodelle op die eksperimentele data, ten einde prosesveranderlikes soos opbrengs per borrel, aantal polimeerstrale, en vesels deursnee te kan beskryf.
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Sun, XingXian. « Technology and economics of sizing single worsted yarn ». Thesis, University of Huddersfield, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307839.
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Borjian, Boroujeni Setareh. « Optimization of yard operations in maritime container terminals ». Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99589.
Texte intégralRésumé :
Thesis: S.M. in Transportation, Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.Thesis: S.M., Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 107-109).
With the continuous growth in international container shipping, many container terminals in maritime ports face congestion, particularly during peak hours of service, and when there is limited space in the storage area. Thus, there has been increasing interest in improving operations efficiency in container terminals. An efficient terminal, in general, is one that discharges containers from the ships in a timely manner and delivers containers to customers with a reasonable wait time. Moreover, a key performance measure in the storage area is the number of moves performed by yard cranes. Due to limited space in the storage area, containers are stacked on top of each other, forming a column of containers that can be accessed by yard cranes only from the top. Therefore, in order to retrieve a container that is covered by other containers, the blocking containers must be relocated to other slots. Because such relocation moves are costly for the port operators and result in service delays, one of the main challenges in the storage area is to plan the moves such that the number of relocations is minimized. This problem is referred to as the Container Relocation Problem (CRP). The CRP in its most simplified setting is concerned with finding a sequence of moves that retrieves all containers in a pre-defined order with a minimum number of relocations, assuming that no new containers are stacked during the retrieval process. Also, it is often assumed that the non-blocking containers cannot be relocated (i.e., repositioning moves are not allowed), an assumption that can result in a sub-optimal solution. Other variants of the container relocation problem include the dynamic CRP and the CRP with incomplete information. The former involves minimizing the number of relocations when containers are continuously stacked in and retrieved from the storage area, and the latter refers to the case that the departure times of containers are not fully known in advance. For example, a probabilistic distribution of container departure orders, or approximate departure times (in the form of time windows) might be known. Another important efficiency metric, in addition to the number of relocations, is customer wait times during the retrieval process. In particular, when repositioning moves are allowed in the system, there is a trade-off between the total number of relocations (including repositionings) and wait times, because such repositioning moves make the retrieval process faster for trucks arriving in the future. Also, it might be desired to prioritize some customers so that those prioritized experience shorter wait times. For example, in terminals with appointment systems, shorter waiting time guarantees can be given to customers who book in advance a time slot for picking up their containers. In this thesis, we propose optimization models that capture service-based and cost-based objectives and study different service policies. In the first part of this thesis, we study the CRP with complete information using an optimization model and heuristic approach. In particular, we formulate CRP (with no restrictive assumptions on repositioning moves) as an Integer Program that minimizes the weighted sum of the number of relocations and the total wait time of customers. Our integer program provides the optimal sequence of moves for retrieving containers subject to various service policies. For example, it can be used by port operators to minimize customer wait times, or to give different waiting time guarantees to different customers to reflect relative priorities. Moreover, by assigning different weight factors to the two objectives, one can use our model to plan repositioning moves. We also extend our model to the dynamic CRP and illustrate how the flexibility in the stacking process can be exploited to optimize jointly the sequence of moves and the stacking position of containers. Additionally, we propose a class of flexible retrieval policies. We demonstrate that flexible policies can result in fewer relocations and shorter wait times, thereby benefiting both the port operators and customers. In the second part of this thesis, we study the CRP with incomplete information in a 2-stage setting where the departure times of a subset of containers are initially known and the departure times of other containers are revealed at once at a later time. The contributions are twofold. First, we propose an approximate stochastic optimization algorithm, called ASA*, which is a branch-and-bound framework combined with a sampling technique, and to the best of our knowledge is the first optimization algorithm proposed for this problem. We provide theoretical bounds on the approximation errors and present numerical results showing the computational tractability and efficiency of our algorithm. Second, we use the ASA* algorithm and a myopic heuristic to study the value of information, that is, the effect of the number of containers initially known on the number of relocations. In the last part of this thesis, we introduce a simulator that is capable of integrated simulation of port operations, including the retrieval process, the stacking process, and other aspects such as allocating cranes to containers and allocating trucks to cranes. Our simulator captures the practical details of operations that cannot be modelled in an optimization framework and is capable of simulating long periods (e.g. a week) of realistic-scale operations.
by Setareh Borjian Boroujeni.
S.M. in Transportation
S.M.
49
Bazbouz, Mohamed Basel. « An investigation of yarn spinning from electrospun nanofibres ». Thesis, Heriot-Watt University, 2009. http://hdl.handle.net/10399/2245.
Texte intégralRésumé :
The aim of the thesis is to investigate yarn spinning from electrospun nanofibres. The concepts of staple and core yarn spinning on electrospun nanofibres has been investigated by examining nanofibre uniformity, alignment, twist insertion and yarn take up by engining and engineering a new take up mechanism. Nylon 6 nanofibres have been fabricated and used throughout this work. The effects of varying the electrospinning parameters such as applied voltage, polymer solution concentration and electrospinning distance on fibre morphology have been established for process optimization. A novel nanofibre aligning mechanism has been devised and systematically revised to enable optimization of alignment process parameters. MWCNTs have been successfully dispersed into nylon 6 nanofibres and have been aligned along the nanofibre body by manipulating the electric and stretching forces with the aid of the alignment mechanism. Novel mechanisms for spinning continuous twisted nanofibre/composite nanofibre yarn and core electrospun yarn have been researched, developed and implemented by making samples. It has been found that defining the velocity and count of the nanofibres entering the spinning zone is important for controlling the yarn count and twist per unit length. By modelling the electrospinning jet, mathematical equations for theoretically calculating the velocity of the jet and nanofibres and their count have been established, necessary for process control. Aspects of practical measurement and comparison of jet and nanofibre velocities have been described and discussed. Tensile testing of single nanofibre and nanofibre mats has been attempted for mechanical characterization. Initial results show the range of tensile strength of nylon 6 nanofibre assemblies and indicate the effect of change of process parameters. A review of those engineering mechanisms related to various nanofibre architectures and their industrial and commercial importance has also been reviewed, described and discussed.
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Alshukur, Malek. « On the structure of multi-thread boucle yarn ». Thesis, Heriot-Watt University, 2017. http://hdl.handle.net/10399/3362.
Texte intégralRésumé :
This research had two dimensions. The first one was theoretical and the geometry of doubled fancy yarn, including bouclé yarn, was modelled mathematically. As a result, the length of the effect component that is necessary to make a copy of those types of fancy yarn was estimated. Further, a geometrical model for the width of the effectthread helices in the First Spinning Zone was presented. One important benefit of this model was using it to control the structure of the bouclé yarn and to prevent the formation of faults and loops on the bouclé yarns. The second dimension was experimental. The mathematical, geometrical model of doubled fancy yarn was tested and the coefficient of correlation between the predicted values and the actual values was r=0.90. This was accomplished by providing methods and roadmaps to help making copies of the bouclé and semi-bouclé fancy yarns after using the output of the geometrical model of the structure. Further, it was found that the technological factors which affected the bouclé yarn structure and geometry were the bending stiffness of the effect thread(s), the rotational speed of the hollow spindle, the level of Tension of the core thread, the overfeed ratio, the number of wraps, and the interaction between those factors. Furthermore, when narrow effect helices have formed in the First Spinning Zone, the thickness of the effect thread was as important as its bending stiffness. To measure the bending stiffness of the input threads, the Beam Method was applied using a simple apparatus, called the Bending Frame, which was built for this purpose.