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Ma, Ran, and 马然. "Chinese independent cinema and international film festival network at the age of global image consumption." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B46676314.
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Gallivan, Rebecca Anne. "Investigating coordinate network based films through mechanical and optical properties." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111257.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (page 31).
Both biological and synthetic materials crosslinked via metal coordinate dynamic chemistry display interesting advanced behavior. In particular, coordinate networks have been shown to form self-healing, self-assembling, and stimuli-responsive behaviors through its tunable optical and mechanical properties as well as its ability to for dynamic networks. However, while the majority of research has focused on characterization of bulk coordinate networks, coordinate complexes have also been shown to be useful in molecular film formation [1 and 2]. This study investigates the mechanical and optical properties of tannic acid and 4 arm catechol polyethylene glycol based coordinate network films. It shows that these films can contribute to energy dissipation and undergo pH-induced optical shifts when used as coatings on soft hydrogels. It also provides evidence that the molecular architecture of the network formers may have considerable effect on the properties and behavior of coordinate network films. Ultimately this work lays the foundation for further investigation of the underlying mechanisms and engineering potential of coordinate network based films.
by Rebecca Anne Gallivan.
S.B.
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Patra, Leena. "Volume-Phase Transitions in Responsive Photo-Cross-Linked Polymer Network Films." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4197.
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The overall thrust of this project is to gain an insight into a class of surface-tethered cross-linked thin films of poly(N-alkylacrylamides) that display a lower critical solution temperature (LCST).The structure of the alkyl group and the modification of the amide groups determine the LCST and resultant volume-phase transition behavior. The aim of this study involves synthesis and characterization of thin films and to correlate the volume-transition behavior to the structure of the alkyl group. For better understanding the volume-transition behavior, the polymer films are perturbed by the Hofmeister salt series to examine trends between different alkyl groups. While most of the studies have been done with bulk gels, the majority of the applications require the use of gels at surfaces and interfaces. Surface attached polymer networks provide an alternative to bulk gels showing superior response times, thus efficiency. Hence it is significant to understand the impact of confinement on the phase transition behavior of a polymer network. Anchoring a polymer network to a surface produces volume phase transition perpendicular to the substrate. The parallel swelling and collapse of the network is highly restricted due to lateral confinement, thus impacting properties such as structure, mechanical properties, dynamics and permeability of the network. Several studies have been done with poly(N-isopropylacrylamide) anchored to a substrate, which have shown significantly different behavior than unconstrained networks. Notable examples include a gradual as opposed to a sharp volume-phase transition, and significantly less swelling above and below the LCST. These studies only looked at poly(NIPAAm); therefore it
remains unknown if these results are universal and will apply to other LCST polymers. Hence, we expanded upon these studies to also investigate a library of different LCST polymers belonging to the category of N-alkylacrylamides.
I have synthesized the copolymers comprising of N-alkylacrylamides and methacryloxybenzophenone (MaBP). The benzophenone moiety in MaBP is photoreactive, allowing us to cross-link the copolymers by UV irradiation. Surface attached thin films were fabricated by spin coating the solution of copolymers and cross-linking by UV irradiation. The volume phase transitions of the coatings were studied under the influence of temperature and the salts of the Hofmeister series. Information concerning the state of responsive layers, the precise temperature at which the collapse occurs, and the changes in the molecular environment during the transition were investigated by ellipsometry and ATR-FTIR. In a longer perspective, understanding the transition behavior and the influence of salts governing this transition provides a better understanding of the interactions of biopolymers in natural systems.
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Wilde, Jason N. "Optical sensing of organic vapours using Langmuir-Blodgett films." Thesis, Durham University, 1998. http://etheses.dur.ac.uk/4763/.
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This thesis describes hydrocarbon vapour sensing using Langmuir-Blodgett films prepared from: a co-ordination polymer; substituted phthalocyanines containing copper and zinc as the central metal ions; and a polysiloxane. The physical and chemical properties of the co-ordination polymer, 5,5'-methylenebis (N- hexadecylsalicylidenamine), at the air water interface were investigated using Brewster angle microscopy and surface pressure versus area measurements. Langmuir-Blodgett films were built-up on a variety of substrates. The addition of copper acetate to the subphase caused a change in both the physical and optical properties of the Langmuir- Blodgett layers. Film thickness data suggest that a true monolayer (thickness ca 2 nm) is only formed under these conditions. The multilayer films were studied using X-ray diffraction, UV/Visible spectroscopy, ellipsometry, surface plasmon resonance, surface profiling and electron spin resonance. The response of each film when exposed to, benzene, toluene, ethanol and water vapours were recorded. Two optical systems were used, both based on surface plasmon resonance. The first incorporated a silicon photodiode to record the intensity of the reflected light. The second was similar to that of surface plasmon microscopy, using a charge coupled device camera to monitor the reflected light intensity from the Langmuir-Blodgett film/metal interface. The co-ordination polymer was found to be most sensitive to benzene and could reliably detect concentrations of this vapour down to 100 vapour parts per million. Data obtained when the co-ordination polymer was exposed to benzene and water vapour (using the latter system) were presented to a neural network for recognition.
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Howard, Brandon Daniel. "Shear and Composition Effects on Porous Network Properties and the Permeability of Lipid Films." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1593680466745792.
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Johansson, August. "Interlayer exchange coupling in Co/Pd-NiFe films studied by Vector Network Analyser Ferromagnetic Resonance." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/interlayer-exchange-coupling-in-copdnife-films-studied-by-vector-network-analyser-ferromagnetic-resonance(cdb5170e-aa10-43ef-86c7-f61cf8a187f9).html.
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A greater understanding of precessional dynamics in magnetic systems is central to several emerging technologies. This thesis presents the design, construction and development of a Vector Network Analyser based Ferromagnetic Resonance measurement instrument (VNA-FMR), and its application in characterising dynamic material properties in hybrid anisotropy [CoPd]8-NiFe films, produced by remote plasma sputtering. Potential applications for hybrid films include Spin Torque Oscillators (STOs) or Vortex Oscillators (VO) for use as microwave emitters in, for example in Microwave Assisted Magnetic Recording (MAMR). The VNA-FMR system was first used to measure thin films of NiFe (permalloy) which allowed its capabilities to be quantified and compared to systems reported in the literature. The instrument demonstrated the capability of measuring permalloy films down to a thickness of 3 nm and was used to measure resonance and damping behaviour which agreed well with theory. The results obtained forMs were in agreement with measurement using Vibrating Sample Magnetometry. The effect of interlayer exchange on FMR was explored in hybrid films using a sample series with varying Pd spacer layer thickness, t, [Co/Pd]-Pd(t)-NiFe. As Pd spacer thickness increased, a transition was observed from near complete coupling with a single resonance mode to separate acoustic and optical branches of resonance. As spacing was further increased, the branches converged towards the resonances of the individual component layers of the hybrid films. The results suggest exchange coupling has a range of less than 2 nm, and is completely extinguished at 5 nm, in agreement with previous measurements. However, a change in damping behaviour was observed between 10 and 20 nm spacer thickness, independent of field orientation.
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Pinzon, Monica. "Beyond human and science documentaries 'Molotov Alva' and 'Waltz with Bashir' as new study cases in the representation of reality /." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/pinzon/PinzonM0509.pdf.
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Although the use of animation to support science documentaries has been well studied, and is easily accepted by viewers, the public has little familiarity with animations or virtual realities as being appropriate tools for other kinds of documentary storytelling. This paper contrasts previous studies of the use of animation and CGI in documentary filmmaking with issues generated by some of the more recent evolutions in the field. I find that although the public may have more difficulty understanding the link between an animated image on the screen and its real world referent, when used effectively animations and virtual realities can offer a new, though potentially problematic, range of storytelling tools.
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Markó, Daniel. "Magnetostatics and Dynamics of Ion Irradiated NiFe/Ta Multilayer Films Studied by Vector Network Analyzer Ferromagnetic Resonance." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-64289.
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In the present work, the implications of ion irradiation on the magnetostatic and dynamic properties of soft magnetic Py/Ta (Py = Permalloy: Ni80Fe20) single and multilayer films have been investigated with the main objective of finding a way to determine their saturation magnetization. Both polar magneto-optical Kerr effect (MOKE) and vector network analyzer ferromagnetic resonance (VNA-FMR) measurements have proven to be suitable methods to determine µ0MS, circumventing the problem of the unknown effective magnetic volume that causes conventional techniques such as SQUID or VSM to fail. Provided there is no perpendicular anisotropy contribution in the samples, the saturation magnetization can be determined even in the case of strong interfacial mixing due to an inherently high number of Py/Ta interfaces and/or ion irradiation with high fluences. Another integral part of this work has been to construct a VNA-FMR spectrometer capable of performing both azimuthal and polar angle-dependent measurements using a magnet strong enough to saturate samples containing iron. Starting from scratch, this comprised numerous steps such as developing a suitable coplanar waveguide design, and writing the control, evaluation, and fitting software. With both increasing ion fluence and number of Py/Ta interfaces, a decrease of saturation magnetization has been observed. In the case of the 10×Py samples, an immediate decrease of µ0MS already sets in at small ion fluences. However, for the 1×Py and 5×Py samples, the saturation magnetization remains constant up to a certain ion fluence, but then starts to rapidly decrease. Ne ion irradiation causes a mixing and broadening of the interfaces. Thus, the Py/Ta stacks undergo a transition from being polycrystalline to amorphous at a critical fluence depending on the number of interfaces. The saturation magnetization is found to vanish at a Ta concentration of about 10–15 at.% in the Py layers. The samples possess a small uniaxial anisotropy, which remains virtually unaffected by the ion fluence, but slightly reduces with an increasing number of Py/Ta interfaces. In addition to magnetostatics, the dynamic properties of the samples have been investigated as well. The Gilbert damping parameter α increases with both increasing number of Py/Ta interfaces and higher ion fluences, with the former having a stronger influence. The inhomogeneous linewidth broadening ΔB0 increases as well with increasing number of Py/Ta interfaces, but slightly decreases for higher ion fluencesIn dieser Dissertation ist der Einfluss von Ionenbestrahlung auf die magnetostatischen und dynamischen Eigenschaften von weichmagnetischen Py/Ta-Einzel- und Multilagen (Py = Permalloy: Ni80Fe20) untersucht worden, wobei das Hauptziel gewesen ist, eine Methode zur Bestimmung der Sättigungsmagnetisierung zu finden. Sowohl polare magneto-optische Kerr-Effektmessungen (MOKE) als auch ferromagnetische Resonanzmessungen mittels eines Vektornetzwerkanalysators (VNA-FMR) haben sich als geeignet erwiesen, um µ0MS zu bestimmen, wobei das Problem des unbekannten effektiven magnetischen Volumens umgangen wird, welches bei der Verwendung von Techniken wie SQUID oder VSM auftreten würde. Unter der Voraussetzung, dass die Proben keinen senkrechten magnetischen Anisotropiebeitrag besitzen, kann die Sättigungsmagnetisierung selbst im Fall starker Grenzflächendurchmischung infolge einer großen Anzahl an Py/Ta-Grenzflächen und/oder Ionenbestrahlung mit hohen Fluenzen bestimmt werden. Ein weiterer wesentlicher Bestandteil dieser Arbeit ist die Konstruktion eines VNA-FMR-Spektrometers gewesen, welches vollautomatisiert ist, polare und azimutale Winkelabhängigkeiten messen kann und einen Magneten besitzt, der Proben, die Eisen beinhalten, sättigen kann. Von Grund auf beginnend umfasste dies zahlreiche Schritte wie z. B. die Entwicklung eines geeigneten koplanaren Wellenleiterdesigns sowie das Schreiben von Steuerungs-, Auswertungs- und Fitprogrammen. Mit steigender Fluenz und Zahl an Py/Ta-Grenzflächen ist eine Abnahme der Sättigungsmagnetisierung beobachtet worden. Im Fall der 10×Py-Proben findet diese bereits bei kleinen Fluenzen statt. Im Gegensatz dazu bleibt µ0MS der 1×Py- und 5×Py-Proben bis zu einer bestimmten Fluenz konstant, bevor sie sich dann umso schneller verringert. Die Bestrahlung mit Ne-Ionen verursacht eine Durchmischung und Verbreiterung der Grenzflächen. Infolgedessen erfahren die Py/Ta-Proben bei einer kritischen Fluenz, die von der Zahl der Grenzflächen abhängig ist, einen Phasenübergang von polykristallin zu amorph. Die Sättigungsmagnetisierung verschwindet ab einer Ta-Konzentration von etwa 10–15 Atom-% in den Py-Schichten. Die Proben besitzen eine kleine uniaxiale Anisotropie, die praktisch unbeeinflusst von der Fluenz ist, sich jedoch mit steigender Zahl an Py/Ta-Grenzflächen leicht verringert. Neben den statischen sind auch die dynamischen magnetischen Eigenschaften der Proben untersucht worden. Der Gilbert-Dämpfungsparameter α erhöht sich sowohl mit steigender Zahl an Py/Ta-Grenzflächen als auch mit höheren Fluenzen, wobei Erstere einen größeren Einfluss hat. Die inhomogene Linienverbreiterung ΔB0 nimmt ebenfalls mit steigender Zahl an Py/Ta-Grenzflächen zu, verringert sich jedoch bei größeren Fluenzen leicht
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Zhou, Bo. "The preparation and characterization of thermo-sensitive colored hydrogel film and surfactant-free porous polystyrene three-dimensional network." Thesis, University of North Texas, 2001. https://digital.library.unt.edu/ark:/67531/metadc3019/.
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Polymer hydrogel films change their properties in response to environmental change. This remarkable phenomenon results in many potential applications of polymer hydrogel films. In this thesis colored thermo-sensitive poly(N-isopropylacrylamide) (PNIPAAm) hydrogel film was prepared by firstly synthesizing polymer latex and secondarily crosslinking the nanoparticles and casting the polymers onto glass. The shape-memory effect has been observed when changing the environmental temperature. The temperature-dependent of turbidity of polymer hydrogel film was measured by HP UVVisible spectrophotometer. This intelligent hydrogel might be used in chemomechanical systems and separation devices as well as sensors. Polymer adsorption plays an important role in many products and processes. In this thesis, surfactant-free three-dimensional polystyrene (PS) nanoparticle network has been prepared. The infrared spectroscopy and solubility experiment are performed to prove the crosslinking mechanism, also the BET method was used to measure the adsorption and desorption of polystyrene network. The BET constant (C) is calculated (C=6.32). The chemically bonded polymer nanoparticle network might have potential applications as catalyst or used for chromatographic columns.
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Wiedenmann, Verena [Verfasser]. "Building block and network properties of β-lactoglobulin gels and films as affected by solid lipid nanoparticles / Verena Johanna Wiedenmann." München : Verlag Dr. Hut, 2020. http://d-nb.info/1222352788/34.
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Wiedenmann, Verena Johanna [Verfasser]. "Building block and network properties of β-lactoglobulin gels and films as affected by solid lipid nanoparticles / Verena Johanna Wiedenmann." München : Verlag Dr. Hut, 2020. http://d-nb.info/1222352788/34.
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Bu, Lei. "Computational and experimental studies of strain sensitive carbon nanotube films." Doctoral thesis, Universitätsbibliothek Chemnitz, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-156473.
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The excellent electrical and mechanical properties of carbon nanotubes (CNTs) provide interesting opportunities to realize new types of strain gauges. However, there are still challenges for the further development of CNT film strain gauges, for instance the lack of design rules, the homogeneity, stability and reproducibility of CNT films. This thesis aims to address these issues from two sides: simulation and experiment. Monte Carlo simulations show that both the sheet resistance and gauge factor of CNT films are determined essentially by the two-dimensional exclude area of CNTs. It was shown, for the first time, that the variation of the CNT film gauge factor follows the percolation scaling law. The sheet resistance and gauge factor both have a power-law divergence when approaching the percolation threshold. The standard deviation of film resistances, however, also increases correspondingly. These findings of simulations provide a general guide to the tailoring of material property of CNT films in strain sensing applications: a compromise should be made between the reproducibility, conductivity and sensitivity of CNT films depending on application purposes. From the experimental side, the processing parameters for the preparation of CNT dispersions were first investigated and optimized. The reproducibility of the film resistance is significantly improved by selecting a suitable sonication time. In strain measurements it was found that for most CNT films the film resistance responses nonlinearly to the applied strain. The dependence of the film resistance on the strain can be roughly divided into two regions with nearly linear behavior respectively. The gauge factor varies with the quality of CNTs and the depositing method. A gauge factor up to 8 was achieved in the high strain region. The nonlinear response behavior was found in simulations when the CNT waviness is properly taken into account. To achieve a high gauge factor and simultaneously retain the high conductivity and reproducibility, good-quality MWCNTs were integrated in polyethylene oxide (PEO). A high gauge factor up to 10 was achieved for the composite film with CNT weight fraction of 2.5%. The resistance and gauge factor can be tuned by changing the MWCNT weight fraction with respect to PEO. A careful comparison of simulation and experiment results show that a good qualitative agreement can be achieved between them in many respects.
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Aydin, Ali. "An Alternative Auteurist Approach to Sidney Lumet's Films : In Search of a Transgressive Cinema." Thesis, Stockholms universitet, Filmvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-128407.
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Branham, Matthew R. Murray Royce W. "Monolayer-protected metal clusters (1-2 nm) Part A) synthesis and characterization, Part B) vapor-sensing and electron transfer kinetics in network polymer films /." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2006. http://dc.lib.unc.edu/u?/etd,585.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2006.Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry." Discipline: Chemistry; Department/School: Chemistry.
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Johnson, Jay Tillay. "Defect and thickness inspection system for cast thin films using machine vision and full-field transmission densitometry." Thesis, Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/37234.
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Quick mass production of homogeneous thin film material is required in paper, plastic, fabric, and thin film industries. Due to the high feed rates and small thicknesses, machine vision and other nondestructive evaluation techniques are used to ensure consistent, defect-free material by continuously assessing post-production quality. One of the fastest growing inspection areas is for 0.5-500 micrometer thick thin films, which are used for semiconductor wafers, amorphous photovoltaics, optical films, plastics, and organic and inorganic membranes. As a demonstration application, a prototype roll-feed imaging system has been designed to inspect high-temperature polymer electrolyte membrane (PEM), used for fuel cells, after being die cast onto a moving transparent substrate. The inspection system continuously detects thin film defects and classifies them with a neural network into categories of holes, bubbles, thinning, and gels, with a 1.2% false alarm rate, 7.1% escape rate, and classification accuracy of 96.1%. In slot die casting processes, defect types are indicative of a misbalance in the mass flow rate and web speed; so, based on the classified defects, the inspection system informs the operator of corrective adjustments to these manufacturing parameters. Thickness uniformity is also critical to membrane functionality, so a real-time, full-field transmission densitometer has been created to measure the bi-directional thickness profile of the semi-transparent PEM between 25-400 micrometers. The local thickness of the 75 mm x 100 mm imaged area is determined by converting the optical density of the sample to thickness with the Beer-Lambert law. The PEM extinction coefficient is determined to be 1.4 D/mm and the average thickness error is found to be 4.7%. Finally, the defect inspection and thickness profilometry systems are compiled into a specially-designed graphical user interface for intuitive real-time operation and visualization.
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Masood, Syed Haani. "Distribution of files using network-coding in opportunistic networks." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106560.
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The immense growth in mobile data usage has placed mobile operators in a challenging position. User experience is threatened to degrade due to network capacity issues. The route towards network upgrades is an expensive one especially due to the high licensing fees attached to spectrum acquisition. We propose a scheme based on community identification for distributing large files to subscribers using opportunistic communication. The scheme is able to offload large files from the cellular network and without having to invest in any infrastructure. The cellular network initially seeds the file to the most central subscriber in each community which is then spread to all subscribers via opportunistic contacts. Network coding is utilized for the opportunistic exchange of file packets between subscribers. We show that seeding the file in each community is important to ensure better file delivery times and also reduces the overhead of the number of packet exchanges required during file dissemination. Our scheme also provides incentives for influential subscribers in the network which contribute more towards the opportunistic dissemination of file.L'immense croissance de l'utilisation des données mobiles a placé les opérateurs mobiles dans une position difficile. L'expérience utilisateur est menacée de se dégrader en raison de problèmes de capacité du réseau. La route vers la mise à niveau du réseau est coûteuse en particulier en raison des frais de licence élevés attachés à l'acquisition du spectre. Nous proposons un schéma basé sur l'identification communautaire pour la distribution de gros fichiers à des abonnés en utilisant la communication opportuniste. Le système est capable de se décharger de gros fichiers sur le réseau cellulaire et sans avoir à investir dans n'importe quelle infrastructure. Le réseau cellulaire d'abord les graines du fichier à l'abonné la plus centrale dans chaque communauté, qui est ensuite étendue à tous les abonnés via des contacts opportunistes. Réseau de codage est utilisé pour l'échange de paquets de fichiers opportunistes entre les abonnés. Nous montrons que l'ensemencement du fichier dans chaque communauté est important pour assurer une meilleure délais de livraison du fichier et réduit également la surcharge du nombre d'échanges de paquets nécessaires pendant la diffusion de fichiers. Notre programme prévoit également des incitations pour les abonnés influents dans le réseau qui contribuent davantage vers la diffusion opportuniste de fichier.
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Deng, Guodong. "Self-Assembly of Poly(Ethylene Oxide)-Block-Poly(Ethyl Acrylate)-Block-Polystyrene with Phenolic Resins." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1399044329.
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Ahmad, Ghazali. "Small firm network in tourism and hospitality : chalet firms and its owner-managers networks." Thesis, University of Strathclyde, 2005. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21601.
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Firms participate in network relationships with others to access resources that are not otherwise available. The resources may consist of goods, services, information, advice or support. This flow of resources into a firm has the potential to enhance the capability of a firm to react to the external competitive environment. Generally network relationships can be formal and/or informal. For a small firm, a network is more likely to be informal and have social links with individuals such as family, friends and acquaintances. This thesis investigates the network features and networking activities of small tourism and hospitality firms. The context of the research is that of owner-managers of chalet accommodation firms located at coastal and island destinations in the east of Peninsular Malaysia. Thirty-seven chalet owner-managers were interviewed face-to-face, using standardised interview questions and procedures, and case protocol. The research found that chalet firms were set-up mainly for economic motives rather that for lifestyle motives. The networks are composed of family and ethnic links and predominantly bounded by specific localities such as the 'village'. Informal ties are with those with a common interest in tourism products and services within a destination. The networks' contacts for business and social purposes consist of the same people. They represent less diverse, low cost and low maintenance networks. Chalet owner-managers became attached to family for financial reasons and to friends for other matters throughout their business life. This was due to the trust that was built up through the years of the relationship, which led to strong ties. The main reason for networking with the contacts was to exchange ideas, advice, and help. The local culture and religious believes have some influence in the selection of network members, network content and networking motivation as well as become guidelines in the networking activities.
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Gontijo, Erik Sartori Jeunon [UNESP]. "Distribuição, complexação e mobilidade de íons arsênio em águas superficiais do Quadrilátero Ferrífero-MG/Brasil: ênfase nas interações com substâncias húmicas aquáticas." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150398.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Deutscher Akademischer Austauschdienst (DAAD)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O As está distribuído em diversas formas químicas em sistemas aquáticos, o que determina o seu comportamento e destino no ambiente. Nesse contexto, as substâncias húmicas (SH) têm um importante papel por serem capazes de complexar esse metaloide e alterar sua mobilidade e biodisponibilidade. O Fe também tem grande importância por poder formar complexos ternários SH-Fe-As. Apesar da química do As já ter sido bem estudada, o seu comportamento em ambientes ricos em SH e Fe ainda não é totalmente compreendido. Os objetivos desse trabalho foram investigar a distribuição do As, Al e Fe em águas superficiais de uma região mineira no sudeste do Brasil (Quadrilátero Ferrífero, QF) e entender como características de SH extraídas de diferentes regiões (Brasil e Alemanha) afetam a complexação do As(V) na presença de Fe(III). Amostras de águas foram coletadas em 12 pontos do QF, filtradas (0,45 µm) e ultrafiltradas (1 kDa) para separar as frações particulada (>0,45 µm), coloidal (<0,45 µm e >1 kDa) e livre (<1 kDa) de As, Al e Fe. A técnica de difusão em filmes finos por gradientes de concentração (DGT) foi usada em 5 dos 12 pontos para estudar a fração lábil dos elementos estudados. Carbono orgânico total (COT) e dissolvido (COD) também foram medidos. SH foram extraídas de quatro pontos (um no Brasil nas estações seca e chuvosa e três na Alemanha) para testar a influência de diferentes tipos de SH e Fe(III) na complexação do As(V). As SH foram caracterizadas e foram feitos testes de complexação utilizando sistema de ultrafiltração com membrana de 1 kDa. Todos os dados foram analisados pela rede neural de Kohonen. Os resultados mostraram que a maior parte do Al e Fe total no QF estava presente na fração particulada e o As na fração livre. A maior parte do Al e Fe dissolvido estava na fração coloidal e inerte, diferente do As que era mais lábil e potencialmente biodisponível. A maioria das amostras apresentou comportamento similar nas estações seca e chuvosa no QF. Diferenças entre os resultados de ultrafiltração e DGT foram atribuídos a distinções metodológicas e processos químicos. Os resultados de caracterização dos extratos mostraram que a maior parte do As e Fe estavam predominantemente nas frações de maior tamanho molecular. Todos os extratos de SH complexaram quantidades similares de As(V) nos testes de complexação, exceto o extrato do rio Selke, onde foi encontrado menos As(V) livre (mais complexado). Essa diferença foi atribuída ao S e à grupos N-C aromático na estrutura de SH. Isso reforça que a qualidade das SH é um importante fator capaz de influenciar o comportamento do As em ambientes ricos em matéria orgânica e Fe, que também pareceram ser fatores limitantes nas interações com o As. A rede neural de Kohonen foi uma ferramenta importante nas investigações de distribuição do As e complexação do As(V) por Fe(III) e SH.
As is distributed in different chemical forms in aquatic systems. These different forms control its behaviour and fate in the environment. The humic substances (HS) have an important role in the As cycle since they can complex this metalloid and change its mobility and bioavailability. Fe is also important because it can form ternary complexes HS-Fe-As. Although the As chemistry is well studied, the behaviour of As in HS and Fe-rich environments is not totally known. This thesis aimed to investigate the distribution of As, Al and Fe in surface waters from a mining region in the southeast of Brazil (Quadrilátero Ferrífero, QF) and understand how characteristics of HS extracted from different regions (Brazil and Germany) affect the complexation of As(V) in the presence of Fe(III). Water samples were taken in 12 points in QF, filtered (0.45 µm) and ultrafiltered (1 kDa) to separate the fractions particulate (>0.45 µm), colloidal (<0.45 µm and >1 kDa) and free (<1 kDa) of As, Al and Fe. The technique of diffusive gradients in thin films (DGT) was used in 5 of the 12 points to study the labile fraction of the elements studied. Total organic carbon (TOC) and dissolved organic carbon (DOC) were also measured. HS were extracted from four points (one in Brazil in dry and rainy seasons and three in Germany) to analyse the influence of HS from different origins and Fe(III) on the complexation of As(V). The HS were characterised and complexation experiments were performed using an ultrafiltration system with 1 kDa membrane. All data were analysed using the Kohonen neural network. The results showed that most of total Al and Fe in QF was in the particulate fraction and As was in the free fraction. Most of the dissolved Al and Fe was in the colloidal and inert fraction, while As was more labile and potentially more bioavailable. Most samples had similar behaviour in the dry and rainy seasons in the QF. Differences between results of ultrafiltration and DGT were attributed to methodological distinctions and chemical processes. The results of characterisation of extracts showed that most of As and Fe was in the fractions of higher molecular size. All HS extracts complexed similar amounts of As(V), except Selke, where a lower amount of free As(V) was detected (more complexed). This difference was attributed to S and N-aromatic C groups in HS structure. It supports that the quality of HS is an important factor able to influence the behaviour of As in environments rich in organic matter and Fe. The Kohonen neural network was an important tool in the investigation of the distribution of As and As(V) complexation by Fe(III) and HS.
FAPESP: 2012/17727-8
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Farooqi, Fahad, and Robert Miog. "Influence of Network forms on the internationalization process : A study on Swedish SMEs." Thesis, Umeå universitet, Företagsekonomi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-57903.
Full textAbstract:
Internationalization is a key concept in today’s globalized world. Globalization has brought about a major shift in the way firms internationalize. Previously, large firms were thought to follow an incremental internationalization process. However, as a result of the rise of international new ventures, the internationalization process has seen a dramatic shift in the internationalization process of firms. Firms no longer follow the traditional models of internationalization. Instead, there are three general phases an international new venture may pass through which are identified by Leonidou and Katsikeas (1996, p. 524): namely: pre-engagement, initial, and advanced. The change in the internationalization process of firms has led firms access networks to internationalize. The use of networks have been shown to help international new ventures to skip the traditional phases of internationalization and expand rapidly by linking themselves to established networks (Coviello & Munro, 1995, p. 53). Participation in networks, among other benefits, includes acquiring the necessary knowledge for international operations. Several important network forms have been identified by different authors. This raises the question what effect these network forms have at the phases of the internationalization process. Three major networks were identified, namely, social, business and intermediaries where each form has its own benefits in the internationalization process of an Small-to-Medium-Size Enterprise (SME). The forms of networks are often described as positive drivers for internationalization. We, however, think that there might also be negative aspects concerning the use of network for internationalization. This study sets out to find what the benefits of each form of network is and also how the networks are used in the internationalization process of an SME. We take into account the perspective of the entrepreneurs as to how they perceive network forms affecting SMEs’ performance at each phase of the internationalization process. Along with that, we also aim to find out how the forms of networks interact with each other and how they evolve from one network to the other. We use qualitative methods, in our study, by interviewing six SMEs located in northern Sweden. Multiple case studies were developed, in order to analyse the collected data from the semi-structured interviews. The collected data was transcribed and categorized in order to find the phases of internationalization, benefits of networks, interaction between networks and the negative aspects of networks. It was then analysed using the three predefined forms of networks: social, business and intermediaries. The findings of the study show that business networks were the most widely used network form throughout the phases of the internationalization process. Social networks and intermediaries were used equally. However, social networks had a greater influence than intermediaries. Our research also identified three phases in the internationalization process. Networks were found to influence each other at all the phases of internationalization and therefore cannot be seperated from each other.
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Ball, David Klaus. "From 2D CoCrPt:SiO2 films with perpendicular magnetic anisotropy to 3D nanocones — A step towards bit patterned media —." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-113029.
Full textAbstract:
Due to the ever-increasing worldwide consumption of memory for digital information, new technologies for higher capacity and faster data storage systems have been the focus of research and development. A step towards achieving higher data storage densities or magnetic recording media is the concept of bit patterned media, where the magnetic recording layer is divided up into magnetically isolated bit units. This approach is one of the most promising technologies for increasing data storage densities and could be implemented by nanostructuring the wafer. Therefore, the fabrication of the appropriate nanostructures on a small scale and then be able to manufacture these structures on an industrial scale is one of the problems where science and industry are working on a solution. In addition, the answer to the open question about the influence that patterning on the nano length scale has on the magnetic properties is of great interest. The main goal of this thesis is to answer the open question, which magnetic properties can be tailored by a modification of the surface texture on the nanometre length scale. For this purpose the following properties: anisotropy, remanence, coercivity, switching field distribution, saturation magnetisation, Gilbert damping, and inhomogeneous linebroadening were compared between planar two dimensional thin ferromagnetic films and three dimensional magnetic structures. In addition, the influences of the tailored morphology on the intergranular or the exchange coupling between the structures, which is called interdot exchange coupling, was investigated. For the ferromagnetic thin films, the focus of the investigations was on the granular CoCrPt:SiO2 and [Co/Pd] layer, which currently are the state-of-the-art material for magnetic data storage media. These materials are characterised by their high coercivity and high perpendicular anisotropy, which has a low spatial distribution in the preferred direction of magnetisation. In this work the pre-structured GaSb(001) substrate with self-assembled periodic nanocone structures at the surface are used. The preparation by ion beam erosion of these structures is simple, fast, and highly reproducible and therefore this method is particularly beneficial for fundamental research. To compare the 2D thin films with the 3D magnetic structures, besides the pre-structured specimen, planar samples were also fabricated. The first sample series prepared was coated by Py. Due to the fact that the magnetic properties of this material are well-known, it was also possible to do some OOMMF simulations in addition to the VNA-FMR and MOKE measurements. Afterwards two planar samples with CoCrPt and CoCrPt:SiO2 were prepared. The planar CoCrPt:SiO2 samples were Co+ ion implanted to study the influence of such irradiation on the intergranular and interdot exchange coupling, switching field distribution, and in particular on the spin dynamics. Moreover, both samples were measured by TRMOKE in order to obtain information about the spin dynamics. Subsequently, the perpendicular storage media materials CoCrPt:SiO2 and [Co/Pd] were deposited on a prestructured GaSb(001) nanocone substrate surface. These sample series were measured by MOKE, SQUID, and vector-VSM. The measurements demonstrate the influence of the periodicity and height of the nanocones on the intergranular and interdot exchange coupling. They also show the reorientation of the magnetisation with respect to the curvature of the substrate template and furthermore, the morphology-induced influences on the magnetic domains. From the comparison between the results for the planar and the pre-structured samples, a decrease of the interdot exchange coupling was observed, which scales together with the periodicity of the nanocone pattern. In addition, it was shown that for all samples with thin magnetic films on nanocones,the magnetisation aligns along the curvature of the underlying nanocone structure. For Py on nanocones, planar granular CoCrPt:SiO2, and planar granular CoCrPt, measurements by VNA-FMR and TRMOKE could be carried out, which yielded information about the spin dynamics. The results obtained for both of the planar sample are comparable to values from the literature for the Gilbert damping. The results for the Py samples showed that the commonly used 2D model resonance condition is, in case of a 3D magnetic structure, no longer valid due to the alignment of the magnetisation along the underlying substrate structure and therefore an new model has to be derivedAufgrund des weltweiten, immer weiter steigenden Bedarfs an Speicherplatz von digitalen Information, sind neue Technologien für größere und schnellere Speichermedien im Fokus von Forschung und Entwicklung. Ein Schritt hin zu einer höheren Speicherdichte in der magnetischen Datenspeicherung ist dabei das sogenannte Konzept der ”Bit patterned media”, das definierte Informationseinheiten auf regelmäßig angeordneten Nanostrukturen beschreibt. Dieser Ansatz ist einer der derzeit vielversprechendsten Optionen die Speicherdichte zu erhöhen. Dabei ist die Herstellung der benötigten Nanostrukturen und deren Skalierung hin zu makroskopischen Dimensionen eines der Probleme an deren Lösung die Wissenschaft und Industrie derzeit arbeitet. Desweiteren ist die Antwort auf die noch offene Frage nach der Beeinflussung der nanoskaligen Strukturen auf die magnetischen Eigenschaften von großem Interesse. Das Hauptziel in dieser Arbeit ist es, einen Beitrag zur Beantwortung der Frage, welche magnetischen Eigenschaften sich durch eine Veränderung der Oberflächenstruktur im Nanometerbereich beeinflussen lassen, zu leisten. Hierzu wurden die folgenden Eigenschaften, wie zum Beispiel die Anisotropie, Remanenz,Koerzitivität, Schaltfeldverteilung, Sättigungsmagnetisierung, Gilbertdämpfung und inhomogene Linienverbreiterung von planaren zweidimensionalen dünnen ferromagnetische Schichten mit denen von dreidimensionalen magnetischen Strukturen verglichen. Zusätzlich wurde der Einfluss der angegpassten Morphologie auf die intergranularen- beziehungsweise auf die zwischen den Strukturen wirkende (interdot) Austauschkopplung untersucht. Der Hauptaugenmerk bei den ferromagnetisch dünnen Schichten lag dabei auf den granularen CoCrPt:SiO2 und [Co/Pd] Filmen, die heutzutage ein Standardmaterial für die magnetischen Speichermedien darstellen. Diese Materialien zeichnen sich durch eine hohe Koerzivität und senkrechte Anisotropie, mit geringer räumlicher Verteilung der Vorzugsrichtung der Magnetisierung, aus. Die hier vorgestellten vorstrukturierten GaSb(001) Substrate mit selbstordnenden periodischen Nanokegeln auf der Oberfläche, sind mittels Ionenstrahlerosion einfach, schnell und sehr gut reproduzierbar herzustellen. Deshalb ist diese Methode besonders für die Grundlagenforschung von Vorteil. Um einen Vergleich zwischen 2D Filmen und 3D Strukturen ziehen zu können, wurden neben den vorstrukturierten Substraten auch planare Proben beschichtet. Eine erste Versuchsreihe wurde mit einem dünnen Py Film präpariert. Da dessen magnetische Eigenschaften wohlbekannt sind, konnten neben den Untersuchungen mit VNA-FMR und MOKE auch einige OOMF Simulationen erstellt werden. Danach wurden zwei Proben mit planarem CoCrPt beziehungsweise CoCrPt:SiO2 untersucht. Bei den planaren CoCrPt:SiO2 Proben wurden außerdem noch Co+ Ionen implantiert, um deren Auswirkungen auf die intergranulare Austauschkopplung, Schaltfeldverteilung und besonders auf die Spindynamik zu bestimmen. Bei beiden Probensystemen konnte zusätzlich die Spindynamik mittels zeitaufgelöstem MOKE gemessen werden. Im Anschluss wurden die beiden senkrechten Speichermedien CoCrPt:SiO2 and [Co/Pd] auf Substraten mit Nanokegeln vorstrukturierten GaSb(001) Oberflächen abgeschieden. Diese Proben wurden mit MFM, MOKE, SQUID und Vektor-VSM vermessen. Aus den Messungen konnnten dann die Einflüsse auf die intergranulare- beziehungsweise interdot Austauschkopplung in Abhängigkeit von der Periodizität und Höhe der Nanokegel bestimmt werden, sowie die Umorientierung der Magnetisierung bezüglich der Substratkrümmung und den Morphologie induzierten Einfluss auf die magnetischen Domänen. Anhand der Vergleiche zwischen den Messungen der planaren und den vorstrukturierten Proben konnte eine Verringerung der Austauschkopplung zwischen den Strukturen gezeigt werden, die mit der Nanokegelstrukturperiodizität skaliert. Außerdem wurde in allen dünnen magnetischen Filmen auf Nanokegeln gezeigt, dass die Magnetisierung sich in Abhängigkeit der darunterliegenden Struktur ausrichtet. Bei den Py auf Nanokegeln, den planaren CoCrPt und dem planaren CoCrPt:SiO2 Proben konnten außerdem mit VNA-FMR und TRMOKE Informationen bezüglich der Spindynamik gemessen werden. Die erzielten Ergebnisse, der beiden planaren Proben, sind vergleichbar mit denen, aus der Literatur bekannten Werten, für die Gilbertdämpfung. Darüber hinaus wurde durch die Messungen an den Py Proben gezeigt, dass die Theorie, des bisher genutzten 2D Modells, nicht mehr gültig ist, da sich die Magnetisierung entlang der Substratstruktur ausrichtet, und deshalb ein neues Model aufgestellt werden muss
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Ball, David Klaus. "From 2D CoCrPt:SiO2 films with perpendicular magnetic anisotropy to 3D nanocones — A step towards bit patterned media —." Doctoral thesis, Helmholtz-Zentrum Dresden-Rossendorf, 2012. https://tud.qucosa.de/id/qucosa%3A26882.
Full textAbstract:
Due to the ever-increasing worldwide consumption of memory for digital information, new technologies for higher capacity and faster data storage systems have been the focus of research and development. A step towards achieving higher data storage densities or magnetic recording media is the concept of bit patterned media, where the magnetic recording layer is divided up into magnetically isolated bit units. This approach is one of the most promising technologies for increasing data storage densities and could be implemented by nanostructuring the wafer. Therefore, the fabrication of the appropriate nanostructures on a small scale and then be able to manufacture these structures on an industrial scale is one of the problems where science and industry are working on a solution. In addition, the answer to the open question about the influence that patterning on the nano length scale has on the magnetic properties is of great interest.
The main goal of this thesis is to answer the open question, which magnetic properties can be tailored by a modification of the surface texture on the nanometre length scale. For this purpose the following properties: anisotropy, remanence, coercivity, switching field distribution, saturation magnetisation, Gilbert damping, and inhomogeneous linebroadening were compared between planar two dimensional thin ferromagnetic films and three dimensional magnetic structures. In addition, the influences of the tailored morphology on the intergranular or the exchange coupling between the structures, which is called interdot exchange coupling, was investigated. For the ferromagnetic thin films, the focus of the investigations was on the granular CoCrPt:SiO2 and [Co/Pd] layer, which currently are the state-of-the-art material for magnetic data storage media. These materials are characterised by their high coercivity and high perpendicular anisotropy, which has a low spatial distribution in the preferred direction of magnetisation.
In this work the pre-structured GaSb(001) substrate with self-assembled periodic nanocone structures at the surface are used. The preparation by ion beam erosion of these structures is simple, fast, and highly reproducible and therefore this method is particularly beneficial for fundamental research. To compare the 2D thin films with the 3D magnetic structures, besides the pre-structured specimen, planar samples were also fabricated. The first sample series prepared was coated by Py. Due to the fact that the magnetic properties of this material are well-known, it was also possible to do some OOMMF simulations in addition to the VNA-FMR and MOKE measurements.
Afterwards two planar samples with CoCrPt and CoCrPt:SiO2 were prepared. The planar CoCrPt:SiO2 samples were Co+ ion implanted to study the influence of such irradiation on the intergranular and interdot exchange coupling, switching field distribution, and in particular on the spin dynamics. Moreover, both samples were measured by TRMOKE in order to obtain information about the spin dynamics.
Subsequently, the perpendicular storage media materials CoCrPt:SiO2 and [Co/Pd] were deposited on a prestructured GaSb(001) nanocone substrate surface. These sample series were measured by MOKE, SQUID, and vector-VSM. The measurements demonstrate the influence of the periodicity and height of the nanocones on the intergranular and interdot exchange coupling. They also show the reorientation of the magnetisation with respect to the curvature of the substrate template and furthermore, the morphology-induced influences on the magnetic domains.
From the comparison between the results for the planar and the pre-structured samples, a decrease of the interdot exchange coupling was observed, which scales together with the periodicity of the nanocone pattern. In addition, it was shown that for all samples with thin magnetic films on nanocones,the magnetisation aligns along the curvature of the underlying nanocone structure. For Py on nanocones, planar granular CoCrPt:SiO2, and planar granular CoCrPt, measurements by VNA-FMR and TRMOKE could be carried out, which yielded information about the spin dynamics. The results obtained for both of the planar sample are comparable to values from the literature for the Gilbert damping. The results for the Py samples showed that the commonly used 2D model resonance condition is, in case of a 3D magnetic structure, no longer valid due to the alignment of the magnetisation along the underlying substrate structure and therefore an new model has to be derived.Aufgrund des weltweiten, immer weiter steigenden Bedarfs an Speicherplatz von digitalen Information, sind neue Technologien für größere und schnellere Speichermedien im Fokus von Forschung und Entwicklung. Ein Schritt hin zu einer höheren Speicherdichte in der magnetischen Datenspeicherung ist dabei das sogenannte Konzept der ”Bit patterned media”, das definierte Informationseinheiten auf regelmäßig angeordneten Nanostrukturen beschreibt. Dieser Ansatz ist einer der derzeit vielversprechendsten Optionen die Speicherdichte zu erhöhen. Dabei ist die Herstellung der benötigten Nanostrukturen und deren Skalierung hin zu makroskopischen Dimensionen eines der Probleme an deren Lösung die Wissenschaft und Industrie derzeit arbeitet. Desweiteren ist die Antwort auf die noch offene Frage nach der Beeinflussung der nanoskaligen Strukturen auf die magnetischen Eigenschaften von großem Interesse. Das Hauptziel in dieser Arbeit ist es, einen Beitrag zur Beantwortung der Frage, welche magnetischen Eigenschaften sich durch eine Veränderung der Oberflächenstruktur im Nanometerbereich beeinflussen lassen, zu leisten. Hierzu wurden die folgenden Eigenschaften, wie zum Beispiel die Anisotropie, Remanenz,Koerzitivität, Schaltfeldverteilung, Sättigungsmagnetisierung, Gilbertdämpfung und inhomogene Linienverbreiterung von planaren zweidimensionalen dünnen ferromagnetische Schichten mit denen von dreidimensionalen magnetischen Strukturen verglichen. Zusätzlich wurde der Einfluss der angegpassten Morphologie auf die intergranularen- beziehungsweise auf die zwischen den Strukturen wirkende (interdot) Austauschkopplung untersucht. Der Hauptaugenmerk bei den ferromagnetisch dünnen Schichten lag dabei auf den granularen CoCrPt:SiO2 und [Co/Pd] Filmen, die heutzutage ein Standardmaterial für die magnetischen Speichermedien darstellen. Diese Materialien zeichnen sich durch eine hohe Koerzivität und senkrechte Anisotropie, mit geringer räumlicher Verteilung der Vorzugsrichtung der Magnetisierung, aus. Die hier vorgestellten vorstrukturierten GaSb(001) Substrate mit selbstordnenden periodischen Nanokegeln auf der Oberfläche, sind mittels Ionenstrahlerosion einfach, schnell und sehr gut reproduzierbar herzustellen. Deshalb ist diese Methode besonders für die Grundlagenforschung von Vorteil. Um einen Vergleich zwischen 2D Filmen und 3D Strukturen ziehen zu können, wurden neben den vorstrukturierten Substraten auch planare Proben beschichtet. Eine erste Versuchsreihe wurde mit einem dünnen Py Film präpariert. Da dessen magnetische Eigenschaften wohlbekannt sind, konnten neben den Untersuchungen mit VNA-FMR und MOKE auch einige OOMF Simulationen erstellt werden. Danach wurden zwei Proben mit planarem CoCrPt beziehungsweise CoCrPt:SiO2 untersucht. Bei den planaren CoCrPt:SiO2 Proben wurden außerdem noch Co+ Ionen implantiert, um deren Auswirkungen auf die intergranulare Austauschkopplung, Schaltfeldverteilung und besonders auf die Spindynamik zu bestimmen. Bei beiden Probensystemen konnte zusätzlich die Spindynamik mittels zeitaufgelöstem MOKE gemessen werden. Im Anschluss wurden die beiden senkrechten Speichermedien CoCrPt:SiO2 and [Co/Pd] auf Substraten mit Nanokegeln vorstrukturierten GaSb(001) Oberflächen abgeschieden. Diese Proben wurden mit MFM, MOKE, SQUID und Vektor-VSM vermessen. Aus den Messungen konnnten dann die Einflüsse auf die intergranulare- beziehungsweise interdot Austauschkopplung in Abhängigkeit von der Periodizität und Höhe der Nanokegel bestimmt werden, sowie die Umorientierung der Magnetisierung bezüglich der Substratkrümmung und den Morphologie induzierten Einfluss auf die magnetischen Domänen. Anhand der Vergleiche zwischen den Messungen der planaren und den vorstrukturierten Proben konnte eine Verringerung der Austauschkopplung zwischen den Strukturen gezeigt werden, die mit der Nanokegelstrukturperiodizität skaliert. Außerdem wurde in allen dünnen magnetischen Filmen auf Nanokegeln gezeigt, dass die Magnetisierung sich in Abhängigkeit der darunterliegenden Struktur ausrichtet. Bei den Py auf Nanokegeln, den planaren CoCrPt und dem planaren CoCrPt:SiO2 Proben konnten außerdem mit VNA-FMR und TRMOKE Informationen bezüglich der Spindynamik gemessen werden. Die erzielten Ergebnisse, der beiden planaren Proben, sind vergleichbar mit denen, aus der Literatur bekannten Werten, für die Gilbertdämpfung. Darüber hinaus wurde durch die Messungen an den Py Proben gezeigt, dass die Theorie, des bisher genutzten 2D Modells, nicht mehr gültig ist, da sich die Magnetisierung entlang der Substratstruktur ausrichtet, und deshalb ein neues Model aufgestellt werden muss.
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Bengtsson, Gonzáles de Olarte María Isabel, and Ian O’Donoghue. "The Role of Network Relationships in the Internationalization of Peruvian Firms." Thesis, Uppsala universitet, Företagsekonomiska institutionen, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-356713.
Full textAbstract:
To offer a deeper understanding of how Peruvian firms internationalize this paper aims to throw in an acknowledged theoretical gap in international business research by giving a contribution towards the internationalization of Multilatinas based on a network perspective. The purpose is to investigate what drives Peruvian Multilatina's to internationalize, what market they select, how they enter these markets, and how different network relationships can influence their internationalization. Research question: What does the internationalization process look like for a Peruvian Multilatina? Method: Includes a qualitative research method with the use of semi-structured interviews. A multiple case study was utilized to gain comparative insights into how Peruvian Multilatinas internationalized through their networks relationships. For the analysis, the theoretical framework consisted of: internationalization drivers, market selection, choice entry mode, and importance of networks. Conclusions: The results conclude that Multilatinas do not follow a unique pattern of internationalization, but follow an accelerated expansion strategy based on the context of their political and economic environment. The Multilatinas studied started off by exporting to markets that had similar characteristics to their own. Once they had adequate experience and knowledge of operating there, they followed up with contractual and investment entry modes. The Multilatinas relied on different network relationships in order to internationalize. The most important being the business relationship and institutional relationship in order to gain insidership.
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Fortner, Scott. "Multi-resolution playback of network trace files." Thesis, Monterey, California: Naval Postgraduate School, 2015. http://hdl.handle.net/10945/45856.
Full textAbstract:
Approved for public release; distribution is unlimitedMarine Corps Tactical Systems Support Activity (MCTSSA) has put forth a requirement for a non-proprietary network traffic replay system that is user friendly and can provide both replay of a network trace file as well as replay based on a statistical model of a network trace file. This thesis attempts to create such a system and to fulfil the requirements set forth by MCTSSA. The system performs as much preprocessing of data as possible, to include loading packet data into a database and creating binary copies of replay packets, which facilitates performing replays multiple times without repetitive processing work. The final system proved to accurately reproduce a capture file with a trace-based replay, while maintaining TCP semantics and the ability to match high volumes of traffic. The major limitation is the need to potentially sacrifice timing accuracy in order to maintain TCP semantic integrity. To accommodate different user implementations, the system supports an option to place the priority on either sequencing or timing, which will guarantee one at the possible expense of the other. Lastly, the statistical model generated from characteristics of the original trace proved to accurately model the original capture and provide for a user-defined replay length. In the end, the MCTSSA requirements were met and further expansion and enhancements were identified to improve performance and usefulness of the system.
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Cui, Lianguang. "Innovation and network development of logistics firms." Doctoral thesis, Internationella Handelshögskolan, Högskolan i Jönköping, IHH, Marketing and Logistics, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-31955.
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This compilation thesis consists of a cover and five appended articles. The research purpose of this thesis is to investigate the third party logistics phenomena from the logistics firm’s perspective with a focus on logistics innovation and network development. The thesis applies a qualitative research method and employs multiple case studies. Resource-based view, industrial network approach and strategy-as-practice perspective have been applied and combined to analyze the empirical findings. It is found that logistics firms focus on customers’ requirements and they provide differentiated services accordingly. Based on the type of customers and the region served, each logistics firm innovates in a different way. The logistics innovation process is complicated and it includes both top-down and bottom-up process. Both intra-organizational interactions and inter-organizational interactions are critical for logistics firms to generate logistics innovation. Besides, the interaction capabilities are crucial for logistics firms to innovate. The development of interaction capabilities enables logistics firms to proactively identify customer needs and to translate customer requirements into new service offerings. The development of interaction capabilities also guides logistics firms to innovate in the right direction and helps them to overcome barriers. Further, a theoretical model is developed to illustrate that logistics firms have clear differences in capabilities and network focus. These firms follow different dominating logics of value creation, developing their service networks in various ways. The thesis addresses two critical issues, logistics innovation and network development. Theoretically, it contributes to the third party logistics literature in general and to the logistics innovation research in particular as well as the network development of logistics firms. Adopting several theoretical frameworks, the thesis takes a closer look at the logistics innovation process in logistics firms. Empirically, the thesis covers logistics firms both in Sweden and China, turning it into an international investigation of the how and why of logistics innovation.
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Patel, Sameer H. "Design of the Network Multimedia File System protocol : a protocol for remote access of networked multimedia files /." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-07292009-090502/.
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Menard, Claire M. "L'homme des réseaux, Figure de l'Entre-deux, dans Ressources Humaines et L'Emploi du Temps, de Laurent Cantet." Miami University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=miami1249035935.
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Menard, Claire M. "L'homme des réseaux, figure de l'entre-deux, dans ressources humaines et l'emploi du temps, de laurent cantet." Oxford, Ohio : Miami University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1249035935.
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Gebremeskel, Tesfaye Helen, and Thi Hong Nhung Nguyen. "Incumbent firms and Response to Disruptive Innovation through Value Network Management : Lessons from Eastman Kodak‟s failure in the digital era." Thesis, Linköpings universitet, Företagsekonomi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-81930.
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AbstractTitle: Incumbent firms and Response to Disruptive Innovation through Value Network Management - Lessons from Eastman Kodak‟s failure in the digital eraAuthors: Helen Gebremeskel Tesfaye & Thi Hong Nhung NguyenSupervisor: Marie BengtssonBackgroundThe question of why incumbent or established firms get into difficulties when they are faced with disruptive innovations has been extensively researched and discussed by many authors. Many explanations given for such failure seem to take “inside-out” approach by focusing on problems of organizational inertia, complacency, lack of insight and incompetence. On the other hand, Christensen‟s (1997; 2003) explanation takes an “outside-in” approach by focusing on the role of established firms‟ value network, particularly mainstream customers, as a determining factor to what incumbent firms can and cannot do.Purpose(i) Examine comprehensively the impacts of the value network on the incumbent firms when they are challenged by the arrival of disruptive innovations; (ii) Developing a model for the incumbent firms to recognize and manage effectively changes occurring in the value network in the face of disruptive innovations; and (iii) Gain a new insight into Kodak‟s failure in the reign of digital technology from the value network management perspective.DefinitionsDisruptive Innovation: Disruptive innovations in this study are considered as new products based on new technologies and which provide different attributes or product characteristics than what the company‟s mainstream or established customer segments historically value, while at the same time bringing new performance attributes to the market.iiValue Network: Value network is the context or environment within which a firm identifies and responds to customers‟ needs, solves problems, procures input, reacts to competitors and strives for profit.ResultsA Value Network Management model is developed for the incumbent firms to recognize and manage effectively changes occurring in the value network caused by the arrival of disruptive innovations. More specifically, the model aims at helping firms to overcome insight and action inertia and to choose the right partners among various new actors entering the value network. This model is iterative in essence and incorporates steps of searching/scanning, value network analysis and partner selection on the basis of appropriate role selection in the value network.
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Mongkhontreerat, Surinthra. "Advanced Functional Thin Films and Networks towards Biological Applications." Doctoral thesis, KTH, Ytbehandlingsteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166600.
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Functional polymeric scaffolds have been employed in biological applications as several utilities, from nano-sized drug delivery systems to concrete implants. The progression in biological fields essentially relies on finding an appropriate material to fulfil the critical requirements for various types of applications with great potential for tuning functionality and mechanical properties. Therefore, the generation of new materials in extensive libraries is desirable for researchers. In this thesis, two main varieties of functional scaffolds have been constructed; these include i) periodic structure isoporous membranes and ii) three dimension (3D) crosslinked networks with programmable functionalities and mechanical properties. In the first case, a library of linear dendritic (LD) block copolymers was synthesised from biocompatible 2,2-bis(methylol)propionic acid (bis-MPA) dendrons and 2- hydroxyethyl methacrylate (HEMA) derivatives. These materials were successfully employed for the fabrication of isoporous membranes via the facile Breath Figure (BF) method. The dendritic periphery end groups control the manipulation of film morphology, as well as introduction of desired functionalities, either pre- or post- film formation. The introduction of azide functional group along the polymer backbone allows crosslinking reaction, which enhances the stability of the isoporous films. The stability towards temperature was improved from around its glass transition temperature (Tg) to 400 °C after crosslinking; simultaneously the porosity is maintained after immersion in the whole range of pH (1-14). These materials show great potential use as high performance isoporous membranes in futuristic applications such as micro-reactors, sensors and cell patterning platforms. In the second case, the facile fabrication of functional networks employs off-stoichiometric crosslinking, which resulted in residual reactive functional groups after film formation and networks with different crosslinking density. This straightforward off-stoichiometric concept is applied with commercially available materials and well-controlled dendritic-linear-dendritic (DLD) hybrid polymers, generating functional networks with different properties from high stiffness film to soft hydrogels. The network post-modification can be performed topologically and throughout the scaffold. Several crosslinking chemistries were employed for construction of hydrogels from DLD hybrid polymers. The Copper(I) Catalysed Azide-Alkyne Cycloaddition (CuAAC) click reaction results in hydrogels with higher compressive modulus compared to other hydrogels constructed from thiol-ene, thiol-yne and amine-N-hydroxysuccinimide (NHS) esters coupling methods with similar building blocks. These functional crosslinked networks are suitable for numerous applications including fabrication of microfluidic devices, cell culture platforms and bone adhesives.QC 20150520
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Van, der Pol Johannes. "Social network of firms, innovation and industrial performance." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0207/document.
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L’objectif de cette thèse est de répondre à trois questions principales ; commentexpliquer et interpréter un réseau de collaboration, est-ce que des firmes avec une positionparticulière dans un réseau bénéficient d’une performance accrue et enfin, existe-t-il desstructures de réseaux qui favorisent l’innovation ?Pour répondre à ces questions, la thèse est organisée en trois parties. La première partieprésente, dans un premier chapitre, une revue analytique de la littérature suivie d’un chapitrequi présente la théorie derrière une des méthodes d’analyse réseau utilisée dans cette thèse :les Exponential Random Graph Models (ERGM).La seconde partie présente trois analyses empiriques. Le premier chapitre empirique analysel’impact du cycle de vie de la technologie sur la dynamique du réseau de collaboration autourdes composites structuraux en aéronautique. Les deux chapitres suivants se concentrent sursecteur aéronautique et le secteur des biotechnologies respectivement. L’objectif de ceschapitres est d’analyser la dynamique structurelle et d’identifier s’il existe un lien entreposition dans le réseau et la performance de la firme.La dernière partie cherche à identifier des structures de réseaux qui favorisent l’innovation.Un modèle à base d’agents (ABM) est proposé pour répondre à cette questionThis thesis aims to answer three main questions ; how can one explain andinterpret the structure of an innovation network, are there positions in a network which allowfor an increased performance for firms and finally, are there network structures which favourinnovation ? In order to answer these questions, the thesis is organised in three parts.The first part presents, in a first chapter, an analytical review of the literature followed by achapter presenting the theory behind one of the network analysis methods: ExponentialRandom Graph Models (ERGM).The second part of the thesis presents three empirical analyses. The first empirical chapteranalyses the impact of the life-cycle of the technology on the structural dynamics of thecollaboration network for Structural Composite Materials. The following two chapters focuson two sectors, the aerospace and biotech sector. The aim of these chapters is to analyse thestructural dynamics of collaboration networks as well as identifying a link between networkposition and firm performance.The third and final part of this thesis searches for network structures which might favourinnovation. An Agent-Based Model is used to answer this final question
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Benfattoum, Youghourta. "Network coding for quality of service in wireless multi-hop networks." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112267/document.
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Dans cette thèse, nous nous intéressons à l’application du codage réseau pour garantir la qualité de service (QoS) dans les réseaux sans fil multi-sauts. Comme le support de transmission est partagé, les réseaux sans fil souffrent de l’impact négatif des interférences sur la bande passante. Il est alors intéressant de proposer une approche basée sur le codage réseau qui prenne en compte ces interférences durant le processus de routage. Dans ce contexte, nous proposons d’abord un algorithme minimisant l’impact des interférences pour des flux unicast tout en respectant la bande passante qu’ils exigent. Puis, nous le combinons avec le codage réseau afin d’augmenter le nombre des flux acceptés et avec le contrôle de topologie pour améliorer davantage la gestion des interférences. Nous montrons par simulation l’intérêt de combiner les trois domaines : codage réseau, gestion des interférences et contrôle de topologie. Nous abordons également la gestion du délai pour les flux multicast et utilisons le codage réseau basé sur les générations (GBNC) qui combine les paquets par bloc. La plupart des travaux portant sur le GBNC considèrent une taille de génération fixe mais à cause des variations de l’état du réseau le délai de décodage et de récupération du bloc de paquets peut varier, dégradant la QoS. Pour résoudre ce problème, nous proposons une méthode qui ajuste la taille de la génération de façon dynamique pour respecter un certain délai de décodage avec prise en compte des contextes réseau et contenu. De plus, nous améliorons notre approche pour contrecarrer les pertes des acquittements. Puis, nous proposons de l’utiliser dans un réseau de domicile pour la diffusion de vidéo à la demande. Notre solution améliore la QoS et la qualité d’expérience pour l’utilisateur final sans équipement additionnel. Finalement, nous abordons un sujet plus théorique dans lequel nous présentons un nouveau réseau basé sur le schéma Butterfly pour des flux multi-sources multi-destinations. Nous caractérisons la taille du buffer du nœud source en utilisant la théorie des files d’attente et montrons qu’elle correspond aux résultats de simulationIn this thesis we deal with the application of Network Coding to guarantee the Quality of Service (QoS) for wireless multi-hop networks. Since the medium is shared, wireless networks suffer from the negative interference impact on the bandwidth. It is thus interesting to propose a Network Coding based approach that takes into account this interference during the routing process. In this context, we first propose an algorithm minimizing the interference impact for unicast flows while respecting their required bandwidth. Then, we combine it with Network Coding to increase the number of admitted flows and with Topology Control to still improve the interference management. We show by simulation the benefit of combining the three fields: Network Coding, interference consideration and Topology Control. We also deal with delay management for multicast flows and use the Generation-Based Network Coding (GBNC) that combines the packets per blocks. Most of the works on GBNC consider a fixed generation size. Because of the network state variations, the delay of decoding and recovering a block of packets can vary accordingly degrading the QoS. To solve this problem, we propose a network-and content-aware method that adjusts the generation size dynamically to respect a certain decoding delay. We also enhance it to overcome the issue of acknowledgement loss. We then propose to apply our approach in a Home Area Network for Live TV and video streaming. Our solution provides QoS and Quality of Experience for the end user with no additional equipment. Finally, we focus on a more theoretical work in which we present a new Butterfly-based network for multi-source multi-destination flows. We characterize the source node buffer size using the queuing theory and show that it matches the simulation results
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Lima, Michele Mara de Araujo Espindula. "Projeto de controladores otimos para gerenciamento ativo de filas." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276334.
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Orientador: Nelson Luis Saldanha da FonsecaTese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação
Made available in DSpace on 2018-08-05T04:20:10Z (GMT). No. of bitstreams: 1 Lima_MicheleMaradeAraujoEspindula_D.pdf: 987855 bytes, checksum: 0b48a6acb474d2be5e0d437581cada01 (MD5) Previous issue date: 2005
Resumo: A ocorrência de congestionamento degrada o desempenho das redes de computadores. Dentre as conseqüências negativas da sua ocorrência cita-se a diminuição da vazão, a perda de pacotes, e o aumento do atraso. Para prevenir e controlar o congestionamento, o protocolo Transmission Control Protocol (TCP) varia a taxa de transmissão de dados de acordo com o nível de congestionamento existente. As políticas de Gerenciamento Ativo de Filas, do Inglês Active Queue Management (AQM), monitoram o nível de ocupação das filas, afim de notificar o congestionamento incipiente aos nós emissores. Esta notificação é realizada através da marca¸c¿ao ou do descarte de pacotes. O sistema de controle de congestionamento em redes TCP/IP, pode ser visto como um sistema de controle por retroalimentação, no qual, a taxa de transmissão dos n'os fontes é ajustada de acordo com o nível de ocupação da fila. Os controladores para o gerenciamento ativo de filas determinam o valor da probabilidade de descarte ou de marcação, buscando a maximização da vazão e a minimiza¸c¿ao das perdas, garantindo, assim, a estabilidade do tamanho da fila independentemente das variações das condições da rede. Nesta tese, são utilizadas técnicas da teoria de controle ótimo para definir uma política ótima de gerenciamento ativo de filas, denominada H2-AQM. A principal característica da H2-AQM é o uso de controladores não racionais, superando-se, assim, a dificuldade de se incorporar no projeto do controlador a garantia de estabilidade em relação ao atraso da retroalimentação. Outrossim, a estabilidade e os objetivos de desempenho do sistema são completamente expressos e solucionados através de desigualdades matriciais lineares, permitindo que os parâmetros do controlador possam ser calculados através da solução de um problema convexo simples. Diferentes controladores operando no mesmo ponto de equilíbrio definem diferentes caminhos entre um ponto qualquer de operação do sistema e o ponto de equilíbrio. Por outro lado, o caminho percorrido para atingir a estabilidade depende dos objetivos usados para projetar o controlador. Nesta tese, é discutida, também, a escolha dos objetivos do projeto de um controlador ótimo para o gerenciamento ativo de filas. Os desempenhos dos diferentes controladores são avaliados e a eficácia do controlador que apresentou o melhor desempenho foi comparado com o desempenho das políticas RED e PI-AQM
Abstract: Congestion is one of the most significant problems in networking. When congestion occurs, the network performance degrades, leading to throughput decrease, delay increase and packet losses. In order to avoid congestion the Transmission Control Protocol (TCP) changes its transmission rate according to the level of congestion. AQM policies notify incipient congestion to TCP source by marking or dropping packets. In TCP/ICP networks, congestion control system can be viewed as a feedback control system in which the transmission rate of the sources are adjusted according to the level of congestion inferred by the queue occupancy. Controllers are responsible for determining the appropriate value of the dropping/marking probability values that stabilizes the queue size regardless of the network condition. In this thesis, optimal control theory is used to conceive an optimal AQM policy, called H2-AQM. The novelty of the proposed approach lies in the use of non-rational controllers that overcomes the difficulty of incorporating guarantees of the stability with respect to the delayed part of the system in the controller design. Furthermore, in the proposed approach stability and performance objectives are completely expressed as Linear Matrix Inequalities (LMIs), thus requiring the solution of a single convex problem for the computation of the controller parameters. Different controllers define different pathes for taking the system state to a target point of equilibrium. Moreover, the path depends on the objectives established for the design of the controller. In this thesis, a discussion on the design of AQM optimal controllers for optimal performance is also presented. The performance produced by different optimal controllers was investigated. The efficacy of the controller which presented the best performance was, then, compared to the performance of both RED and PI-AQM policies
Doutorado
Redes de Computadores
Doutor em Ciência da Computação
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Håkansson, Andreas, Magnus Gustafson, and Peter Jankevics. "The Role of Networks for Micro Firms." Thesis, Jönköping University, Jönköping International Business School, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-111.
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Introduction: Each year thousands of micro firms are established in Sweden, not all firms will survive and grow; instead many will be forced out of business. Possible explanations of this phenomena could lie in the personality of the entrepreneur, the network of the micro firm as well as support from society and so on.
Problem: Prior research has showed that networks and networking are important for the establishment, development and growth of micro firms. The majority of prior research has been of a quantitative nature, which has resulted in great knowledge about structural dimensions while less is known about the interactional dimensions. It is because of the lack of qualitative knowledge that little is known about interactional dimensions in networks and networking activities.
Purpose: The purpose of the study is to investigate the role of networks and networking activities for micro firms.
Method: The research has the character of a qualitative case study. Data gathering has been done through six in-depth interviews with the founder or manager of six micro firms located in the facilities of Science Park in Jönköping. All information obtained from the interviews were transcribed and then analysed with a model developed by O’Donnell (2004).
Summary of analysis: The role of networks and networking activities for micro firms are of great importance for generating business. Our analysis show that many of the micro firms are proactive towards their customers while their relationship with suppliers and competitors varies in characteristics.
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Löfgren, Max. "Deep learning for measuring radon on plastic films." Thesis, Uppsala universitet, Signaler och system, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-441986.
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Exposure to high levels of radon can be very harmful and lead to serious health issues. Measuring radon in buildings and houses is an important measure to prevent this. One way of measuring radon is to place out plastic films to be exposed over a period and then analyze images of them. Image processing together with deep learning has become very useful for image recognition and analysis. Training artificial neural networks using huge amount of data to learn to classify and predict new data is a widely used approach. In this project, artificial neural networks were trained to be able to predict the radon measurement of exposed plastic films. The data used was microscopic images of these films that first was modified to fit the training better and then sorted into two datasets. The datasets were divided into 10 classes with measurement values in intervals of 100 up to 1000. Two main types of neural networks were used in different shapes and with different training parameters: Convolutional neural networks and Dense neural networks. The convolutional model was able to predict new data with a 70 percent accuracy and the performance increased with a bigger image size (more pixels) but not with a deeper network architecture. Over 90 percent of the wrong data predictions also belonged to a class in the interval just above or below the predicted result which shows that the network has potential for improvements. The dense model only had a 35 percent accuracy but had a training accuracy of over 90 percent. This is because the model was heavily overfitted. A way to get better results could be to increase the dataset that was used with more images.
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Ezran, Philippe. "Optimisation de la Topologie des Réseaux Sans Fils." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLC014/document.
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L'industrie des télécommunications sans fil fait actuellement face à une croissance considérable pour des débits toujours plus hauts, stimulée par le développement des services mobiles de données. Ce développement rend le spectre disponible de plus en plus rare et nécessite des solutions afin d'optimiser l'usage de ses ressources limitées.Le principal défi auquel les réseaux sans fils font face est de maximiser la disponibilité, la résilience et la qualité de service, tout en minimisant les coûts et en assurant entre les utilisateurs une allocation de ressources équitable. Cette thèse tente de présenter des solutions à ces problèmes et se focalise sur trois thèmes.Sur le premier thème, le but est de trouver la topologie en anneau qui optimise la disponibilité. Il est montré que les algorithmes développés dans le cadre de la théorie des graphes peuvent être utilisés de manière efficace pour définir en temps polynomial la topologie en anneau optimale si les anneaux sont petits (deux nœuds en plus du nœud d'agrégation). Pour les anneaux plus grands, le problème est NP-hard.Le deuxième thème concerne la polarisation. Nous proposons une solution innovante qui peut améliorer efficacité spectrale jusqu'à 50% par comparaison avec l'état de l'art. Le paradigme proposé introduit de nouvelles perspectives au sujet de l'optimisation de la topologie et de l'allocation de canal.Le troisième thème concerne l'allocation de ressources. Nous remettons en question l'approche présente, basée sur l'optimisation de l'efficacité du réseau. Nous montrons que cette approche est similaire au modèle d'utilité espérée de Bernoulli, qui a été réfuté par les paradoxes d'Allais. C'est pourquoi nous introduisons le concept d'aversion au manque d'équité et considérons la question d'allocation de ressources comme un compromis entre efficacité du réseau et équitéThe wireless telecommunication sector is presently facing a tremendous growth of demand for higher data rates, driven by the development of mobile data services. This development makes the available spectrum scarcer and scarcer and requires solutions in order to optimize the use of its limited resources.The main challenge wireless networks are facing is to maximize availability, resiliency and Quality of Service, while minimizing costs and ensuring fair resource allocation among users.The present thesis will try to present solutions to these issues and will focus on three topics.On the first topic, the purpose is to find the ring-based topology which optimizes availability. It will be shown that algorithms which have been developed in the field of graph theory can be used efficiently to define in polynomial time the optimal ring network topology if the rings are small (two nodes in addition to the aggregation node). For bigger rings, the problem will be NP-hard. The second topic deals with polarization. We propose an innovative solution which can improve spectral efficiency in wireless ring networks by up to 50% in comparison with the state of the art. The proposed paradigm brings new perspectives regarding topology optimization and channel allocation.The third topic deals with resource allocation. We question the present approach based on optimization of network effciency. We show that this approach is similar to Bernoulli's expected utility model, which has been disproved by Allais' paradoxes. For this reason, we introduce the concept of unfairness aversion and consider the question of resource allocation as a trade-off between network efficiency and fairness
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Nguyen, Viet Hoai Petroleum Engineering Faculty of Engineering UNSW. "A dynamic network model for imbibition and film flow." Awarded by:University of New South Wales. Petroleum Engineering, 2006. http://handle.unsw.edu.au/1959.4/25495.
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This thesis describes a new dynamic network model for imbibition which is based on a physically realistic description of the complex dynamics of corner film flow, swelling and snap-off. The model shows that film flow is a capillary driven non-linear diffusive process and that the competition between snapoff and frontal displacements is rate dependent and results in rate dependent relative permeabilities and residual saturations. In contrast to previously published models in which length scales for snap-off are either specified a priori or calculated assuming steady-state film flow and constant film conductivities, in the present model, snap-off arises as a natural consequence of the fully transient nature of film flow and swelling. The network model is used to analyse the complex interaction between displacement rate, contact angle, aspect ratio and pore and throat shape on relative permeability and residual saturation. Computed relative permeabilities and residual saturations are compared with laboratory measurements reported in the literature. It is concluded that the magnitude of the rate effect on imbibition relative permeabilities and residual saturations for a particular rock microstructure and wettability condition depends largely on the pore-throat aspect ratio. Higher aspect ratios result in stronger rate effects than do smaller aspect ratios.
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Kohlschein, Ingo. "Consequences of Network-effects for the Financing of Media Firms." Diss., lmu, 2006. http://nbn-resolving.de/urn:nbn:de:bvb:19-48060.
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Struben, Sarah-Annique. "Constructing brand loyalty via social networks." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13348.
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Includes bibliographical references.Identifying the construction of brand loyalty via social networks requires an analysis of the information sharing of a product or brand amongst a social network, therefore indicating the strength of the brand loyalty members of a social network not only have towards a brand, but also promote to other members of the same social network. This exchange of information amongst social network members is called ‘homophily’, where “similarity breeds connection” (McPherson, 2001, p.415). In order to determine the strength of brand loyalty amongst a social network, a qualitative study was performed on a sample of consumers from the ‘digital age’ generation (Castells, 2010, p.xviii), examining the extent of information exchange via social media as well as via the social networks. In addition to this a minor case study was conducted where participants were asked a serious of questions that pertained to a specific brand, that of Woolworths. This was done in order to determine the strength of the brand loyalty they had for a particular brand that may then be theoretically applied on a general scale. As a result the strength of their brand loyalty was determined, indicating whether or not brand loyalty can be constructed via social networks. On the whole it can be determined that social networks play a strong role in the development of brand loyalty, particularly as it pertains to the current digital generation. Keywords: Social Network, Habitus, Purchase Behaviour, Networked Society, Brand Loyalty, Consumer satisfaction, Homophily, Brand Trustworthiness
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Kang, Jasmine, and Kirill Korotkov. "Network mobilisation in Project based organizations such as film making." Thesis, Umeå University, Umeå School of Business, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1502.
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Project networks are gaining importance for many project based organizations nowadays. Project based organizations carry non-routine and complex tasks by temporarily employing various specialists, allow more flexibility and are ideally suited for managing complexity and dynamic external environment. For managing a project based organization it is not only essential to have good know-how about the tasks involved but also to have good knowledge of potential project members and project partners. This leads to an increased interdependency among projects and focuses on the importance of project networks. In order to initiate a project a PBO mobilizes its network to bring potential project participants together.
Film making represents the pure form of project based organization since companies in this industry are formed in order to pursue specific project outcomes and are dismantled once project is completed. Organizations in the movie industry are highly dependent on project networks mobilization to carry out their project tasks. Since the mechanism of such mobilization process still remains unclear the main focus of this research is on how networks are mobilized in project based organization such as film making during the pre-production stage to carry out a specific project.
For the purposes of the research primary data was obtained as a result of semi-structured interviews with ten people involved in the film industry in Sweden. A mixture of specific and open-ended questions allowed receiving practical insight of film initiation process and narrating industry participants’ experiences on network mobilization for a film project.
During the study several factors were revealed that contribute to network mobilization process during the pre-production stage of film making as well as main activities of film making pre-production stage were discovered. The model was develop that combines the factors and pre-production stage activities to see which factors drive network mobilization for realizing each activity in this stage. The developed model permitted to analyze in details each factor and to reveal the degree of its influence on the pre-production stage in general. Results of the study show that network mobilization process is explained by several discovered factors and almost all of them help to mobilize the network to carry out each of the four activities in the pre-production stage to making a film.
The study concludes that since the identified factors contribute to network mobilization for realization of almost all of the activities in the pre-production stage of a movie project then they contribute to general network mobilization process in the preproduction stage for carrying out a movie project. The discovered factors facilitate the network mobilization process and help producers to attach potential participants to their projects.
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Labraoui, Mohamed. "Les réseaux maillés sans fils assistés par le SDN." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066636.
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Avec les progrès dans les communications sans fil, le réseau maillé sans fils (WMN) est apparu comme une solution à la couverture et à la capacité limitée des réseaux d'infrastructure. Un WMN est un réseau ad-hoc multi-sauts dans lequel les routeurs participants acheminent le trafic pour le compte de tiers. Malgré les avantages et l'efficacité accrue de nombreuses applications, plusieurs problèmes doivent encore être résolus, notamment des facteurs critiques influant sur les performances des WMNs tels que l'évolutivité, la stabilité de la connectivité réseau, la qualité de service, la sécurité et les problèmes d'interférence. Face à ce défi, cette thèse explore une nouvelle approche des réseaux, à savoir le concept de réseau défini par logiciel (SDN). Dans une configuration SDN, l'intelligence située au niveau des périphériques réseau est déplacée dans une entité centrale communément appelée le contrôleur SDN. Dans cette architecture, le contrôleur SDN prend toutes les décisions et dicte à chaque périphérique réseau comment router les flux de données. Dans cette thèse, l'accent est mis sur l'évaluation des améliorations de la gestion de réseau que SDN pourrait apporter aux WMNs. En particulier, nous avons analysé et déterminé le type de granularité de contrôle SDN envisageable pour ce type de réseaux ainsi que les solutions techniques permettant de mettre en œuvre ce concept pour de meilleures performancesWith advances in wireless communications, Wireless Mesh Network (WMN) has emerged as one solution to the limited coverage and capacity of infrastructure networks. A WMN is a multihop ad-hoc network where participating routers forward traffic on behalf of others. Despite the advantages and increased efficiency in many applications, several challenges still need to be solved and especially critical factors influencing the performance of WMNs such as scalability, network connectivity steadiness, Quality of Service (QoS), security, and interference problems. In the face of this challenge, this thesis explores a new approach for networks, namely the concept of Software-Defined Network (SDN). In an SDN configuration, the intelligence located at network devices level is moved within a central entity commonly referred to as the SDN controller. In this architecture, the SDN controller takes all decisions and dictates to each network device how to route data flows. In this thesis, the focus is on evaluating network management improvements that SDN could make in WMNs. Particularly, we analyzed and determined what kind of SDN control granularity that could be envisaged for this type of networks as well as the technical solutions to implement this concept for better performance
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Pourmand, Firouze. "How do Small Firms Manage their Political Environment? : - A Network Perspective." Doctoral thesis, Uppsala universitet, Företagsekonomiska institutionen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-151942.
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To this point research on firms’ political behavior has contributed knowledge concerning large firms’ relationships and strategies with political actors and their surrounding environment. Less is known about small firms’ behavior towards political organizations. As a matter of fact, the fields of international marketing, international business and corporate political science have left the political behavior of small firms almost untouched. Therefore, extant literature assumes that small firms due to their resource constraints are passive receivers of political initiatives. About 99 percent of all firms within the European Union are small firms, and it is therefore questioned whether all these firms are passive receivers of political initiatives. The intention with this thesis is to challenge some assumptions regarding how small firms manage their relationships with political actors concerning EU related rules and regulations. Consequently, the study raises the overarching research question; how do small firms manage their political environment? Theoretically, the study takes a network perspective on business political interaction to examine both individual and/or collective political behavior of small firms. It develops a theoretical view constituted of knowledge, commitment and legitimacy. Methodologically, two sequential stages are followed: first an in-depth qualitative case study of three successful cases is presented and second, the in-depth understanding is broadened to a wider population of firms based on a quantitative survey. A central contribution of this thesis is to aid research on the political behavior of small firms. It is found that small firms, in contrast to prevailing assumptions, do possess political resources. They are not passive receivers of political initiatives. Instead, the findings show that small firms are active and can exercise influence. This, however, is shown to be dependent on the firm’s political commitment, political knowledge and competency and business-political legitimacy. It is also shown that small firms mobilize these critical resources not only directly, but also indirectly through various intermediating actors. Besides the theoretical contributions, these conclusions are important not just because of the managerial implications but also, and perhaps more importantly, for the policy implications that can be drawn from the study. Being exploratory and opening up the black box of small firm’s political behavior, the thesis ends with a number of future research directions.
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Augusto, Leonardo Rangel. "Controladores otimos para gerenciamento ativo de filas na arquitetura de serviços diferenciados da Internet." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276179.
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Orientador: Nelson Luis Saldanha da FonsecaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação
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Resumo: A classe de Serviço Assegurado da arquitetura de Serviços Diferenciados (DiffServ) da Internet inclui a provisão de diferenciação de banda passante, o que depende do adequado USG de mecanismos de condicionamento de tráfego e gerenciamento ativo de filas (AQM). Nesta dissertação, propõe-se um controlador ótimo para gerenciamento ativo de filas para a arquitetura Diffserv. Seu projeto considera intrinsecamente a influência de fluxos não adaptativos na dinâmica do controle de congestionamento. Apesar de o controlador obtido ser racional, seu projeto utiliza uma abordagem não-racional, o que aumenta a precisão do modelo. Simulações conduzidas demonstram que o controlador proposto reduz o descarte desnecessário de pacotes, aumentando o goodput e diminuindo a quantidade de RTOs dos emissores TCP.
Abstract: The Assured Service of Differentiated Services Arehitecture (DiffServ) is currently used for providing throughput differentiation in the Internet. For this, traffic policing and active queue management (AQM) mechanisms must be used. In this dissertation, we use a non-rational approach to develop an optimal AQM controller. Its design considers both adaptative and non-adaptative like UDP. Simulations were conducted for comparison with other proposals. Results show that the proposed controller reduces unnecessary packet drops, increases the goodput and reduces the TCP sender's Retransmission Timeouts.
Mestrado
Redes de Computadores
Mestre em Ciência da Computação
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Wincent, Joakim. "On building competitiveness in strategic SME networks : empirical analysis of 54 firms in two networks." Doctoral thesis, Luleå : Luleå University of Technology, 2006. http://epubl.ltu.se/1402-1544/2006/04/index.html.
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Smits, Charles. "Gatekeepers and gatekeeping networks in the film distribution business." Thesis, University of York, 2017. http://etheses.whiterose.ac.uk/20159/.
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Cultural flow, the access producers have to markets and the range of films available to audiences are heavily circumscribed by gatekeeping arrangements that have developed between sales agents and distributors in the film distribution business. This thesis examines how sales agents and distributors operate in that business: the sort of roles they have taken on over time, their ability to regulate the circulation of and access to films, the way they exercise power over distribution, and how they operate as part of gatekeeping networks.
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Vassiliadis, Stefanos. "Knowledge networks in management consultancies : case studies of Hellenic firms /." Bamberg : Difo-Druck, 2002. http://www.gbv.de/dms/zbw/356747573.pdf.
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Wang, Lina, and Qiong Wu. "Enterprises Internationalize with Firm-specific Advantages : Case Study of Swedish Firms." Thesis, Halmstad University, School of Business and Engineering (SET), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-2538.
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Business has changed and developed fast and drastically through internationalization, which has drawn many scholars’ attentions. The dissertation will focus on the firm-specific advantages (FSAs) which allow firms to go to the international markets.
The theoretical framework of this dissertation contains four proxies of the firm’s specific advantages, including entrepreneur, market knowledge, network, and technology. In this dissertation, this framework will guide us to collect and analyze the empirical data.
The qualitative research strategy is employed in this dissertation. Utilizing the multiple case study, we choose two sample companies, both from Halmstad. The empirical data was gathered through semi-structured personal interviews. Data was also supplemented with secondary data, such as web pages and scientific articles.
The finding of this dissertation is that market knowledge and experience is a crucial, firm-specific advantage, which facilitates firm’s international expansion. In addition, the entrepreneur and network variables also have an impact on the internationalization process in direct or indirect ways. However, the study does not find obvious evidence that technology does help firms go to the foreign markets a lot.
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Suby, Carl. "Representative Biodiversity: The Ecosystem of Cartoon Network." Chapman University Digital Commons, 2019. https://digitalcommons.chapman.edu/film_studies_theses/4.
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As a capitalist organism the television program, as explained by Todd Gitlin, uses its slant to sell itself to advertisers with similar leanings on contemporary social issues to maintain its flow of revenue. However, this concept of slant does not account for the broader network, which, like the singular program, cultivates a catalog of programming into a singular slanted message becoming an ecosystem of shows relying on each other to maintain viewership. The successful televised ecosystem will then be home to programs who enjoy long runs and display an easily recognized shared slant. As an example of the televised ecosystem, this thesis explores seven animated programs from Cartoon Network including The Marvelous Misadventures of Flapjack,Regular Show, Adventure Time, The Amazing World of Gumball, Steven Universe,We Bare Bears, and Craig of the Creek.Recognizing the programs ranging in release from 2008 to 2018, Cartoon Network’s ecosystem is highlighted for its evolving display of progressive representations of race and gender and presenting them to a child audience.
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Palma, Cando Alex Uriel [Verfasser]. "Electrogenerated Films of Carbazole- and Thiophene-Based Microporous Polymer Networks / Alex Uriel Palma Cando." Wuppertal : Universitätsbibliothek Wuppertal, 2017. http://d-nb.info/1128844540/34.
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Dakessian, Areck Ardack. "Casting nets and framing films : an ethnography of networks of cultural production in Beirut." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31464.
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Filmmakers first received widespread academic attention as case studies into the increasing casualisation of labour in post-industrial economies. Their precarious existence in project-based labour markets provided much food for thought about the future of work, while their status as artists and producers of culture entered them into debates around just what art is and how to approach it. But in light of recent transformations in the cultural industries and the accompanied blurring of boundaries between production and consumption, academic understandings of the lives filmmakers lead have also been somewhat blurred. This ethnography of networks of cultural production in Beirut re-introduces filmmakers into the very sociological debates that they helped spark. Might a return to the situated experience of these theoretically and methodologically challenging people, who form workgroups and collaborate with each other repeatedly across projects as they craft their own careers, shed productive light on academic understandings of precarity, cultural production and indeed our increasingly confusing relationships with the objects around us? With that in mind, in this thesis I ask the following research question: how are networks of film production formed and maintained in Beirut? Based on an 'insider' ethnography of various film projects weaved into a mixed-methods social network analytic methodology, I adopt a relational sociological approach that conceives of production networks as akin to social worlds and find three analytic planes to delve deeper into: markets, objects and relationships. In relation to markets, I echo the argument that current classification systems of cultural production are too consumption-based and adopt a social network markets framework more sensitised towards production. Here, I find that the cyclical, project-based relationship of patronage that ties production networks to their clients is highly varied and contingent, shaping not only the process of cultural production but also its organisational structure. Further, I argue that the management of these contingencies is key to the potential repeat collaboration not just with clients (and their own social networks), but fellow producers as well. But past projects do not simply disappear once completed, they might well come back to haunt their makers. Drawing upon ethnographic and recent historical data on a number of web-series that emerged out of Beirut between 2009 and 2012, I compare using two-mode networks the past and more recent projects my interlocutors were involved in. Here, I find that one's past projects shape one's future by conducing or hindering their chances of finding new work. Moreover, and perhaps more importantly, I find that filmmakers (and those around them) increasingly define themselves (and are defined by others) in relation to the past projects they have done. Over time, though, as filmmakers collaborate on an increasing number of films, their relationships take on deeper characteristics than monochrome economic considerations. Here I draw upon the notion of embeddedness to shed light on emergent meaning at the network level across a number of projects and, therefore, the emergent social world-ness of networks. While the first set of findings relates to debates in the sociology of work and the second to those in the sociology of cultural production, my final analysis shows just how intimately the two are connected. I conclude by highlighting the potential of empirically-grounded relational sociological approaches to finessing our understandings of cultural work in its economic, social, but also material and technical contingencies.