Дисертації з теми "Grid of optical frequencies"
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Lukin, K. A., Yu P. Machekhin, and D. N. Tatyanko. "Grid of optical frequencies in a near infra-red range spectrum." Thesis, Paris, France, 2011. http://openarchive.nure.ua/handle/document/8671.
Повний текст джерелаIsaac, Thomas Henry. "Tunable plasmonic structures for terahertz frequencies." Thesis, University of Exeter, 2009. http://hdl.handle.net/10036/90193.
Повний текст джерелаMcNiff, James Edward. "An experimental study of nonlinear dielectrics at microwave frequencies." Thesis, University of Salford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261855.
Повний текст джерелаCheung, Chun Tung Rutledge David B. "Waveguide packaging of quasi-optical grid amplifiers /." Diss., Pasadena, Calif. : California Institute of Technology, 2003. http://resolver.caltech.edu/CaltechETD:etd-05192003-161134.
Повний текст джерелаHu, Ziang. "Characterisation of orbital angular momentum at optical and radio frequencies." Thesis, University of Bristol, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.738525.
Повний текст джерелаZhu, Min. "Research on key techniques in passive optical networks and optical grid applications." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2012. http://tel.archives-ouvertes.fr/tel-00907280.
Повний текст джерелаQuadir, A. "Finite element characterisation of plasmonic waveguides in terahertz and optical frequencies." Thesis, City, University of London, 2017. http://openaccess.city.ac.uk/17568/.
Повний текст джерелаAlmousa, Shaikhah F. "Extraordinary Optical Transmission in Aligned Carbon Nanotube Devices at Terahertz Frequencies." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1493566948712806.
Повний текст джерелаBodkin, David Bradley. "Color, tilt, and the Hermann grid illusion /." Adobe Acrobat Reader required to view document, 2008. http://library.neco.edu/theses/BodkinThesisApr08.pdf.
Повний текст джерелаTerra, Osama [Verfasser]. "Dissemination of ultra-stable optical frequencies over commercial fiber network / Osama Terra." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover, 2010. http://d-nb.info/1010837621/34.
Повний текст джерелаLuo, Xubin. "Wavelength Division Multiplexing Optical Networks for Supporting Grid Computing." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1221753325.
Повний текст джерелаSmith, Graham Murray. "Transferred electron oscillators at mm wave frequencies and their characterisation using quasi-optical techniques." Thesis, University of St Andrews, 1990. http://hdl.handle.net/10023/11106.
Повний текст джерелаJarrar, Majed. "Radio Over Fibre Passive Optical Network Integration for The Smart Grid." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32779.
Повний текст джерелаTakahashi, Satoshi Ph D. Massachusetts Institute of Technology. "Design and fabrication of micro- and nano- dielectric structures for imaging and focusing at optical frequencies." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67602.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (p. 115-[121]).
In this thesis work, design and fabrication of micro- and nano-photonic structures both in the diffraction regime and sub-wavelength regime have been investigated. In the diffraction regime, two types of optical systems and optical elements were investigated for application in LCD manufacturing. With the increasing demand for larger LCD screens at lower cost, technology for low-cost high-throughput manufacturing systems, as well as efficient repair systems within the manufacturing line for any manufacturing defects, are crucial for manufacturers. The first system investigated in this work is a novel optical lithography system for LCD manufacture using a computer generated hologram (CGH). The fabrication challenges for a highly complex pattern inherent in CGHs are addressed. The second system is a defect repair system utilizing a blazed grating matrix (BGM). The BGM generates multiple high intensity spots from a high-power pico-second pulsed laser, controlled by a spatial light modulator, which can ablate the surface of the substrate to eliminate residues and excess material. In both systems, high efficiency and pattern fidelity are required for the optical element, and micro- and nano-fabrication techniques were used in order to achieve the required specifications. In the sub-wavelength regime, locally periodic dielectric photonic structures with adiabatic variation were designed and verified, with application in lensing in optical frequencies. Structures such as rod lenses and Luneburg lenses are investigated. Especially the latter type of lenses have been conventionally difficult to implement in optical frequencies due to its specific refractive index profile. With the high flexibility of gradient effective index design with the " aperiodic" dielectric nanostructures, along with the design method using Hamiltonian Optics investigated in this research, the Luneburg lens was designed, fabricated, and verified at the wavelength of A[gamma] = 1.55[mu]m.
by Satoshi Takahashi.
Ph.D.
Durkoš, Michal. "Datová síť pro smart grid v energetice." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220116.
Повний текст джерелаRumipamba, Zambrano Rubén Darío. "Contributions to network planning and operation of Flex-Grid/SDM optical core networks." Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/666326.
Повний текст джерелаLa demanda de ancho de banda cada vez más exigente para soportar servicios de telecomunicación emergentes tales como la transmisión de video de alta calidad, computación en la nube, vehículo conectado, realidad virtual/aumentada, etc.…, ha puesto de manifiesto la necesidad de actualizar constantemente la tecnología detrás de las redes de transporte óptico con la finalidad de ir a la par de este incremento exponencial del tráfico. De esta manera, todo parece indicar que las redes basadas en la multiplexación por division de longitud de onda (Wavelength Division Multiplexing, WDM) de ancho espectral fijo serán actualizadas adoptando un ancho de banda espectral flexible, que ofrece asignaciones de ancho de banda con granularidad más fina acorde a las demandas de tráfico; y por lo tanto, incremanta el Grado de Servicio de la red, ya que se permite acomodar mayor información en la misma banda espectral de las fibras monomodo (Single Mode Fibers, SMFs). Sin embargo, desafortunadamente, el límite de Shannon de las fibras monomodo se está aproximando cada vez más, y cuando esto ocurra las investigaciones para incrementar la capacidad de las fibras monomodo serán infructuosas. Una posible solución para superar este colapso de las fibras monomodo es habilitar la dimensión espacial a más de la frecuencial, desplegando 𝑆� caminos paralelos con la finalidad de multiplicar por 𝑆� (en el mejor de los casos) la capacidad de las fibras monomodo. No obstante, es necesario disminuir el costo y la energía por bit con la finalidad de proveer soluciones comerciales atractivas. Para tal propósito debe llevarse a cabo una actualización moderada conforme nuevos dispositivos y componentes integrados son desarrollados para la implementación de la tecnología basada en la multiplexación por división de espacio (Space Division Multiplexing, SDM). Esta tesis se concentra en la planificación y operación de la combinación de las redes WDM flexibles y SDM (es decir, de las redes Flex-Grid/SDM) proponiendo varias estrategias dirigidas a optimizar el uso de los recursos de red junto con el análisis de la complejidad del hardware que viene acompañada. Para este fin, primeramente, los problemas de red son cuidadosamente estudiados y descritos. A continuación, se han diseñado e implementado algoritmos basados en programación lineal entera o heurísticas en un simulador de redes ópticas. Después de una introducción inicial, el capítulo 2 de esta tesis presenta el marco teórico sobre los conceptos tratados y los trabajos publicados anteriormente. A continuación, el capítulo 3 se concentra en el estudio de las redes Flex-Grid/SDM con la dimensión espacial rígida; es decir, cuando un número fijo de canales espaciales son reservados por cada demanda de tráfico establecida. Por su parte, el capítulo 4 estudia las redes Flex-Grid/SDM considerando flexibilidad tanto en el dominio espacial como espectral (Spectrally and Spatially Flexible Optical Networks, SS-FONs), las cuales proveerían la capacidad máxima de las redes SDM. Adicionalmente, los costos y requerimientos de hardware implicados en la provisión de esta flexibilidad son analizados. El capítulo 5 presenta la evaluación de nodos orientados a reducir los costos de las SS-FONs. Finalmente, el capítulo 6 expone las principales contribuciones y las posibles líneas de trabajo futuro
Els requisits incessants d’ample de banda per al suport de nous serveis de telecomunicació, com poden ser la difusió en directe de vídeo de molt alta definició, la informàtica en el núvol, els cotxes intel·ligents connectats a la xarxa, la realitat virtual/augmentada, etc…, han exigit una millora contínua de les tecnologíes de les actuals xarxes de transport de dades. Tot sembla indicar que les xarxes de transport òptiques actuals, basades en la tecnologia de multiplexació per divisió de longitud d’ona (Wavelength Division Multiplexing, WDM) sobre un grid espectral rígid, hauran de ser reemplaçades per tecnologies òptiques més flexibles, amb una granularitat més fina a l’hora de suportar noves connexions, incrementat el grau de servei de les xarxes gràcies a aprofitament major de l’ample de banda espectral proporcionat per les fibres òptiques monomode (Single Mode Fibers, SMFs). Tanmateix, estem exhaurint ja la capacitat màxima de les fibres òptiques SMF segons ens indica el límit fonamental de Shannon. Per tant, qualsevol esforç enfocat a millorar la capacitat d’aquestes xarxes basades en SMFs pot acabar sent infructuós. Una possible solució per superar aquestes limitacions de capacitat és explorar la dimensió espacial, a més de l’espectral, desplegant 𝑆 camins en paral·lel per tal de multiplicar per 𝑆, en el millor cas, la capacitat de les SMFs. Tot i això, és necessari reduir el cost i el consum energètic per bit transmès, per tal de proporcionar solucions econòmicament viables. Amb aquest propòsit, pot ser necessària una migració progressiva, a mesura que es desenvolupen nous dispositius i components per aquesta nova tecnologia de multiplexació per divisió espacial (Spatial Division Multiplexing, SDM). La present tesi es centra en la planificació i operació de xarxes òptiques de nova generació que combinin tecnologies de xarxa WDM flexible i SDM (és a dir, xarxes Flex-Grid/SDM), proposant estratègies per a l’optimització de l’ús dels recursos de xarxa i, en definitiva, el seu cost (CapEx). Amb aquest propòsit, s’analitzen en primer moment els problemes adreçats. Tot seguit, es dissenyen algorismes per tal de solucionar-los, basats en tècniques de programació matemàtica i heurístiques, els quals s’implementen i es proven en un simulador de xarxa òptica. Després d’una introducció inicial, el capítol 2 d’aquesta tesi presenta tots els conceptes tractats i treballs relacionats publicats amb anterioritat. Tot seguit, el capítol 3 es centra en l’estudi de les xarxes Flex-Grid/SDM fixes en el domini espai, és a dir, on sempre es reserva un nombre rígid de canals espacials per qualsevol demanda suportada. El capítol 4 estudia les xarxes flexibles en els dominis espectrals i espacials (Spectrally-Spatially Flexible Optical Nextworks, SS-FONs), com aquelles que poden proporcionar una capacitat de xarxa màxima. En aquest context, s’analitzen els requeriments en termes de cost i hardware per tal de proporcionar aquesta flexibilitat. Llavors, en el capítol 6 es presenten opcions de node de xarxa capaces de reduir els costos de les xarxes SS-FONs. Finalment, en el capítol 7 es repassen totes les contribucions de la tesi, així com posibles línies de treball futur
Sun, Xuan. "A study of ion acceleration, asymmetric optical pumping and low frequency waves in two expanding helicon plasmas." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4319.
Повний текст джерелаTitle from document title page. Document formatted into pages; contains v, 152 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.
Soman, Deepa. "Channel modelling for Wireless Networks on Chip at Oprtical frequencies: simulations and measurements." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/22036/.
Повний текст джерелаOlugbenga, Olubodun. "High speed optical phase modulated signaling with offset filtering in a 50 GHz grid." Thesis, Swansea University, 2011. https://cronfa.swan.ac.uk/Record/cronfa42896.
Повний текст джерелаYang, Bin. "Assessment of Magnetic material for use in quasi-optical non-reciprocal devices operating at frequencies above 90 ghz." Thesis, Queen Mary, University of London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502604.
Повний текст джерелаMiller, Darren Alexis. "SELECTIVE POLARIZATION IMAGER FOR CONTRAST ENHANCEMENT IN EXTENDED SCATTERING MEDIA." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202512.
Повний текст джерелаTrota, Tiago Ferreira Grade Dinis. "Design and optimization of elastic optical networks." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12786.
Повний текст джерелаThe traffic volume in backbone optical networks has increased in the last few years and it is expected to continue to exhibit a high growth, with bandwidth-hungry services being the key drivers of this growth. Furthermore, the tra c is becoming more dynamic, being characterized by a strong heterogeneity. Thus, in order to cope with these changes, optical transport networks are developing towards the operation with mixed-line rates and the elastic usage of spectrum through exible frequency grids. Regarding this paradigm shift, telecommunication network operators seek to assess solutions that enable transport networks to provide capacity enhancement and scalability. However, due to the reduction in pro t margins, another parameter taken into account is the network cost, either investment or operational. Therefore, planning and optimization tools arise as valuable instruments to exploit the features of next generation optical networks, and quantify their cost-e ciency impact. The aim of this dissertation is to study the problem of optical network design. For this purpose, an optimization algorithm was developed where the objective function minimizes the network deployment cost. This algorithm allows the use of di erent terminal equipments with di erent line rates and comprises features such as regenerator placement, multi-hop grooming, inverse-multiplexing and spectrum assignment with low granularity. Moreover, in order to improve the algorithm e ciency, a multi-thread approach was used to fully take advantage of computational resources of current platforms. The algorithm was applied and examined under di erent tra c and network topology sets. The design outcomes allow us to study the trade-o between equipment prices. Also, allow to understand the importance of each of the previously mentioned features in each of the proposed sets. The computational outcomes obtained show gains in multi-thread approach, particularly when a mechanism that lets sharing information between all threads is implemented
O volume de tráfego nas redes ópticas de transporte tem aumentado nos últimos anos e espera-se que continue a apresentar um crescimento elevado, com os serviços de largura de banda intensivos a serem os principais impulsionadores desse crescimento. Adicionalmente, o tráfego está a tornar-se mais dinâmico, e sendo caracterizado por uma forte heterogeneidade. Assim, de forma a lidar com estas alterações, as redes ópticas de transporte estão a evoluir no sentido de operar com taxas de linha mistas e a utilizar o espectro de forma elástica através do uso de grelhas flexíveis na frequência. Face a esta mudança de paradigma, os operadores de redes de telecomunicações procuram avaliar soluções que permitam às redes de transporte fornecer maior capacidade e escalabilidade. No entanto, devido à redução das margens de lucro, outro parâmetro tido em consideração é o custo da rede, quer de investimento quer operacional. Consequentemente, as ferramentas de planeamento e optimização surgem como instrumentos valiosos para explorar as funcionalidades das redes ópticas de próxima geração, e quantificar o seu impacto na relação custo-benefício. O objectivo desta dissertação é estudar o problema de dimensionamento de redes ópticas. Para este fim, foi desenvolvido um algoritmo de optimização cuja função objectivo minimiza o custo da rede. Este algoritmo permite considerar a utilização de diferentes equipamentos terminais com diferentes taxas de linha e inclui as funcionalidades de colocação de regeneradores, de multi-hop grooming, de inverse-multiplexing e de alocação de espectro com baixa granularidade. Além disso, de forma a melhorar a eficiência do algoritmo, utilizou-se uma abordagem multi-thread para aproveitar ao máximo os recursos computacionais das plataformas actuais. O algoritmo foi aplicado e avaliado em diferentes cenários de tráfego e de topologias de rede. Os resultados de dimensionamento permitem estudar o compromisso entre os preços dos equipamentos. Também permitem interpretar a importância de cada uma das funcionalidades previamente mencionadas em cada um dos cenários propostos. Os resultados computacionais obtidos revelam ganhos na abordagem multi-thread, em particular quando é implementado um mecanismo de partilha de informação entre todas as threads.
Adhikari, Pan P. "Optical Study of Inter-band Transitions in Topological Insulators Bi2Se3, Bi2Te3, and Sb2Te3." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1497994862971012.
Повний текст джерелаCetnar, John. "Full Wave Electromagnetic Simulations of Terahertz Wire Grid Polarizers and Infrared Plasmonic Wire Gratings." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1398356024.
Повний текст джерелаAmar, Djamel. "Performance assessment and modeling of flexible optical networks." Thesis, Evry, Institut national des télécommunications, 2016. http://www.theses.fr/2016TELE0007/document.
Повний текст джерелаWith the exponential growth of traffic driven by video and Internet services, WDM systems evolve regularly to increase optical fiber capacity. To meet the relentless need for capacity, advanced features have been integrated into optical layer leading to the notion of channel flexibility (datarate elasticity, flex-grid). In contrast, with the potential benefits that optical channel flexibility provides, network dimensioning gets even more complicated, and traditional dimensioning tools should be rethought. Moreover, some strategic and technological problems appear with optical layer flexibility. Almost, all legacy equipment in the optical layer needs to be replaced by greenfield and well-adapted equipment, which requires new investments. Furthermore, spectrum fragmentation has been identified as the main disadvantage of optical layer flexibility. This work proposes and implements different mathematical multilayer tools for network dimensioning with the aim of evaluating optical layer flexibility. It identifies profitable and advantageous use cases and networking scenarios that bring forward the interest of flex-grid and elasticity. This work also deals with the potential troubles of flexibility and provides solutions to them. Specifically, we thoroughly investigate spectrum fragmentation in operator network context, and propose some traffic engineering strategies. We propose and evaluate a new use case that combines datarate elasticity and optical restoration within a multilayer context. Finally, we state a new drawback of flex-grid technology regarding the use of legacy optical amplifiers with flex-grid networks and provide a solution to overcome this problem
Tinini, Rodrigo Izidoro. "Agendamento e reserva futura de caminhos ópticos em ambientes de lambda grid por meio de otimização por colônia de formigas." reponame:Repositório Institucional da UFABC, 2014.
Знайти повний текст джерелаDissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência da Computação, 2014.
Por conta da grande demanda por computação de alto desempenho, maiores taxas de envio de dados e disponibilidade de recursos de um ambiente de computação em grade, este trabalho apresenta um estudo realizado sobre o uso de redes ópticas que operam com Multiplexação por Divisão de Comprimento de Onda (Wavelength Division Multiplexing (WDM)) no suporte a grades computacionais, cujo ambiente é chamado de lambda grid. Assim, é proposto neste trabalho uma nova arquitetura de lambda grid capaz de ampliar a disponibilidade de seus recursos computacionais e de rede, por meio da inserc~ao de um suporte a reserva futura destes recursos, ampliando a disponibilidade da grade a tempos futuros e não apenas a tempos correntes de operação. Para o gerenciamento desse ambiente, foi proposto o uso de um algoritmo baseado em Otimização por Colônia de Formigas (Ant Colony Optimization (ACO)) integrado ao plano de controle Generalized Multi-Protocol Label Switching (GMPLS), o qual é capaz de gerenciar dinamicamente e de forma conjunta os recursos de processamento e de rede, alem de prover os mecanismos de agendamento e de reserva futura desses recursos. A arquitetura proposta, juntamente com os demais algoritmos desenvolvidos, foi testada e validada por meio de simulações. Os resultados das simulações permitiram a avaliação do desempenho da nova arquitetura e da necessidade de se incorporar o agendamento conjunto com reserva futuras na execução da ação da probabilidade de bloqueio.
Due to the increasing demand of high-performance computing, higher data transport rates and the availability of the resources on a grid computing environment, this work presents a study of the use of Wavelength Division Multiplexing (WDM) optical networks on the support of grid computing, whose environment is known as lambda grid. It is proposed in this work a new architecture of lambda grid which is capable of increasing the availability of its network and computing resources by the use of an advance reservation approach, which makes the grid able to other its resources in future times of operation and not only in the current time. For the management of this environment, it was proposed the use of an Ant Colony Optimization (ACO) based algorithm integrated to the Generalized Multi-Protocol Label Switching (GMPLS) control plane, which is capable to dynamically manage the server and network resources, in addition to provide the co-scheduling and advance reservation of those resources. The proposed architecture and algorithms were tested and evaluated by means of simulations. The obtained results allowed the evaluation of the performance of the new architecture and the need to incorporate the co-scheduling of server and optical network resources in their advance reservation in order to minimize the blocking probability.
Burian, Tomáš. "Apodizace Braggových vláknových mřížek vyráběných UV expozicí přes fázovou masku." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-399594.
Повний текст джерелаGiovannelli, Luca. "Direct creation of patient-specific Finite Element models from medical images and preoperative prosthetic implant simulation using h-adaptive Cartesian grids." Doctoral thesis, Universitat Politècnica de València, 2018. http://hdl.handle.net/10251/113644.
Повний текст джерелаEs creu que la medicina in silico suposarà un dels canvis més disruptius en el futur pròxim. Al llarg de l'última dècada, s'ha invertit un gran esforç en el desenvolupament de models computacionals predictius per millorar el poder de diagnòstic dels metges i l'efectivitat de les teràpies. Un punt clau d'aquesta revolució, serà la personalització, que comporta en la majoria dels casos la creació de models computacionals específics de pacient. Aquesta pràctica està actualment estesa en la investigació i hi ha al mercat diversos software que permeten obtenir models a partir d'imatges. Tot i això, per a poder-se utilitzar en la pràctica clínica aquests métodes es necessita reduir dràsticament el temps i el treball humà necessaris per a la seva creació. Aquesta tesi es centra en la proposta d'una versió basada en imatges del Cartesian grid Finite Element Method (cgFEM), una técnica per obtenir de forma automàticament models a partir d'imatges i dur a terme anàlisis estructurals lineals d'ossos, implants o materials heterogenis. Després de relacionar l'escala del imatge a propietats macàniques corresponents, s'usa tota la informació continguda en els píxels per a integrar les matrius de rigidesa dels elements que homogeneïtzen el comportament elàstic dels grups de píxels continguts en cada element. Es emphh-adapta una malla inicialment uniforme a les característiques de la imatge usant un procediment eficient que té en compte les propietats elàstiques locals associades als valors dels píxels. Amb això, s'evita un suavitzat excessiu de les propietats elàstiques a causa de la integració dels elements en àrees altament heterogénies, però, tot i això, s'obtenen models finals amb un nombre raonable de graus de llibertat. El resultat d'aquest procés és una malla no conforme en la qual s'imposa la continuïtat C0 de la solució mitjançant restriccions multi-punt en els hanging nodes. Contràriament als procediments estàndard per a la creació de models d'Elements finits a partir d'imatges, que normalment requereixen la definició completa i watertight de la geometria i tracten el resultat com un CAD estàndard, amb cgFEM no cal definir cap entitat geométrica. No obstant això, és immediat incloure-les en el model en el cas que sigui necessari, com ara superfícies suaus per imposar condicions de contorn de forma més precisa o volums CAD de dispositius per a la simulació d'implants. Com a conseqüéncia d'això, la quantitat de treball humà per a la creació de models es redueix dràsticament. En aquesta tesi, s'analitza en detalls el comportament del nou métode en problemes 2D i 3D a partir de CT-scan i radiografies sintétiques i reals, centrant-se en tres classes de problemes. Aquestes inclouen la simulació d'ossos, la caracterització de materials a partir de TACs, per a la qual s'ha desenvolupat la cgFEM virtual characterisation technique, i l'anàlisi estructural de futurs implants, aprofitant la capacitat del cgFEM de combinar fàcilment imatges i models de CAD.
In silico medicine is believed to be one of the most disruptive changes in the near future. A great effort has been carried out during the last decade to develop predicting computational models to increase the diagnostic capabilities of medical doctors and the effectiveness of therapies. One of the key points of this revolution, will be personalisation, which means in most of the cases creating patient specific computational models, also called digital twins. This practice is currently wide-spread in research and there are quite a few software products in the market to obtain models from images. Nevertheless, in order to be usable in the clinical practice, these methods have to drastically reduce the time and human intervention required for the creation of the numerical models. This thesis focuses on the proposal of image-based Cartesian grid Finite Element Method (cgFEM), a technique to automatically obtain numerical models from images and carry out linear structural analyses of bone, implants or heterogeneous materials. In the method proposed in this thesis, after relating the image scale to corresponding elastic properties, all the pixel information will be used for the integration of the element stiffness matrices, which homogenise the elastic behaviour of the groups of pixels contained in each element. An initial uniform Cartesian mesh is h-adapted to the image characteristics by using an efficient refinement procedure which takes into account the local elastic properties associated to the pixel values. Doing so we avoid an excessive elastic property smoothing due to element integration in highly heterogeneous areas, but, nonetheless obtain final models with a reasonable number of degrees of freedom. The result of the process is non-conforming mesh in which C0 continuity is enforced via multipoint constraints at the hanging nodes. In contrast to the standard procedures for the creation of Finite Element models from images, which usually require a complete and watertight definition of the geometry and treat the result as a standard CAD, with cgFEM it is not necessary to define any geometrical entity, as the procedure proposed leads to an implicit definition of the boundaries. Nonetheless, they are straightforward to include in the model if necessary, such as smooth surfaces to impose the boundary conditions more precisely or CAD device volumes for the simulation of implants. As a consequence, the amount of human work required for the creation of the numerical models is drastically reduced. In this thesis, we analyse in detail the new method behaviour in 2D and 3D problems from CT-scans and X-ray images and synthetic images, focusing on three classes of problems. These include the simulation of bones, the material characterisation of solid foams from CT scans, for which we developed the cgFEM virtual characterisation technique, and the structural analysis of future implants, taking advantage of the capability of cgFEM to easily mix images and CAD models.
Giovannelli, L. (2018). Direct creation of patient-specific Finite Element models from medical images and preoperative prosthetic implant simulation using h-adaptive Cartesian grids [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/113644
TESIS
Nakazawa, Takeshi. "THREE-DIMENSIONAL NON-CONTACT SURFACE PROFILERS FOR SEMICONDUCTOR IC PACKAGE INSPECTION." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/205472.
Повний текст джерелаHuang, Yao-Wei, and 黃耀緯. "Plasmonic Toroidal Response at Optical Frequencies." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/99584827489485429695.
Повний текст джерела國立臺灣大學
應用物理所
100
Toroidal shapes are often found in bio-molecules, viruses and proteins, but only recently it was proved experimentally that toroidal structures can support exotic high-frequency electromagnetic excitations that are neither electric or magnetic multipoles. Such excitations, known as toroidal moments, could be playing an important role in inter-molecular interaction and directive energy transfer on the molecular level, but are weekly coupled to free space and are difficult to observe. Whether or not the toroidal dipoles will resonate at higher frequencies remains to be answered, since Joule loss of metals is higher at optical frequencies. In this paper, we present two new related classes of plasmonic metamolecules composed of purposely arranged of four U-shaped split-ring resonators (SRRs) that show profound resonant toroidal responses at optical frequencies. First, the toroidal and magnetic responses were investigated by the finite-element simulations. A phenomenon of reversed toroidal responses at higher and lower resonant energy has also been reported between this two related metamaterials which results from the electric and magnetic dipoles interaction. We propose a physical model based on coupled LC circuits to quantitatively analyze the inter-molecular interaction system of the plasmonic toroidal metamaterials. Using a model metamaterial system we show that coupling optical gain medium with toroidal molecules can enhance the single pass amplification on up to 65 dB of the toroidal resonance frequency. This offers an opportunity of creating the “lasing spaser” a source of coherent optical radiation that is fueled by toroidal plasmonic oscillations in the nanostructure. Finally, we experimentally demonstrate the toroidal dipolar resonance at optical frequencies in the U-shaped metamolecules, which are manufactured using a double exposure e-beam lithographic process.
Cheung, Chun Tung. "Waveguide Packaging of Quasi-Optical Grid Amplifiers." Thesis, 2003. https://thesis.library.caltech.edu/1867/1/final_master.pdf.
Повний текст джерелаPereira, Paulo José da Costa Marinho. "Superchannel transmission over flexible-grid optical networks." Master's thesis, 2019. http://hdl.handle.net/10071/20936.
Повний текст джерелаO uso de super-canais tem sido proposto como uma boa relação custo-benefício para suportar a futura procura de capacidade de dados nas redes de transporte a longa distância. Contudo, nos super-canais, o espectro dos sub-canais está muito compactado e a interferência entre sub-canais pode tornar-se uma limitação. Enquanto atravessa a rede óptica, um super-canal passa através de vários multiplexadores ópticos reconfiguráveis de inserção e extracção (ROADMs, em inglês). O efeito acumulado da filtragem de uma cascata de filtros baseados em comutadores selectivos no comprimento-de-onda (WSS em inglês) que se encontram dentro dos ROADMs, reduz a largura-de-banda disponível e causa distorção no sinal óptico. A performance dos sub-canais é significativamente dependente do espaçamento entre sub-canais, da interferência entre sub-canais e da filtragem nos WSS’s. Neste trabalho, avalia-se exaustivamente a penalidade na relação sinal-ruído óptica (OSNR, em inglês) devido a filtragem óptica e interferência entre sub-canais, usando diferentes formatos de modulação M-QAM, ritmos de símbolos, factores de excesso de banda, número de WSS’s, larguras-de-banda dos WSS’s, número de sub-canais e espaçamento entre portadoras. Fornece-se um procedimento para obter valores optimizados para estes parâmetros que garantem que a penalidade na OSNR é menor que 1.5 dB em todos os sub-canais depois de 20 WSS’s. Comparam-se também dois modelos espectrais para o filtro WSS, denominados analítico e super-Gaussiano. Investiga-se o uso da penalidade da EVM, computacionalmente muito mais rápida, como métrica de desempenho e conclui-se que fornece resultados mais pessimistas que a penalidade da OSNR para estimar a distorção da cascata de filtros.
Ray, Sanith. "Optical and dielectric properties of ZnO nanostructures at terahertz frequencies." 2006. http://digital.library.okstate.edu/etd/umi-okstate-1771.pdf.
Повний текст джерелаShaikh, Ali Asghar. "Optical Grid Network Dimensioning, Provisioning, and Job Scheduling." Thesis, 2014. http://spectrum.library.concordia.ca/978506/1/Shaikh_PhD_S2014.pdf.
Повний текст джерела"Analytical Control Grid Registration for Efficient Application of Optical Flow." Doctoral diss., 2013. http://hdl.handle.net/2286/R.I.17831.
Повний текст джерелаDissertation/Thesis
Ph.D. Bioengineering 2013
Hong, Chen Chiong, and 陳火冏宏. "Microwave Quasi-Optical High Power Hybrid MESFET Grid Array Oscillator." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/41883626211441634228.
Повний текст джерела國立交通大學
電信研究所
82
Solid-state devices can not generate large power at very high frequency,it is necessary to combine many solid-state devices to obtain high power. In the thesis, the quasi-optical high power hybrid MESFET grid array oscillator is designed. The fabrication and measurement are also present. The project is based on the circuit designed by Prof. Rutledge's group in California Institute of Technology. The frequency of oscillator is determined by the period and the lead width of grid, and the substrate used. Therfore, it is necessary to study the electromagnetic field in the grid and obtain the equivalent circuit. The equivalent circuit of oscillator is simulated by Libra. When bias at Vds=3 V, Vgs=-0.9V, Fabry-Perot mirror locate at the back of grid at about 3.5mm, the oscillation frequency is measured to 4.1GHz. Because the grid require high symmetry, we sampled 50 MESFET to find 16 FET with similar quality. The duroid has a dielectric constant of 10.5, and the thickness is 100mil. The oscillator is formed by combining 16MESFET in Fabry-Perot cavity. The distance between horn and grid is 22cm. Using the spectrum analyzer, at Vds=3V, Id=12.5mA, the oscillation frequency is measured at 4.0GHz. The power received by spctrum analyzer is 7.66dBm, it is about more than 150mW. The harmonic distortion is less -35dBc. If use the monolithic technique, it will generate much more power.
Guerreiro, Mark Emanuel Cavaco. "Signaling strategies for consumer oriented Grid over Optical Burst Switching networks." Master's thesis, 2009. http://hdl.handle.net/10400.1/603.
Повний текст джерелаThe concept of Grid networks has recently emerged as an infrastructure able to support, both scientific and commercial applications. The Grid is a dynamic, distributed collection of heterogeneous computational, storage and network resources geographically distributed and shared between organizations. Optical Burst Switching (OBS) networks have been identified as a technology with potential to support the requirements of the Grids. This approach, known as Grid over Optical Burst Switching (GOBS) is currently the object of intensive research. This dissertation focus is on GOBS architectures employing Active OBS Routers with centralized control. This approach enables the balance of the overall network traffic potentially minimizing congestion and consequently reducing job blocking. Two different strategies are explored. The first strategy is a novel signaling scheme applied to a GOBS network employing Active Routers. The Active Router reduces the job blocking probability, because the path used by the Data Burst to reach the Grid Job Resource is selected based on the network actual status. Since the Active Router maintains the network status always updated, the bursts are only dropped when is not possible to connect the source to the end node. Another study associated with this signaling scheme is the reservation time. It is demonstrated that this approach decreases the network blocking probability at the same time that decreases the time delay that a job suffers until it reaches the Grid service provider. In the second strategy, the Active Router only select the Grid Resource used to resolve the job, the path used to reach it is selected by the Grid client based on the probabilistic model for the link demands. The probabilistic model is used to predict a possible network usage based on the demands from all nodes to all nodes. The results obtained show overall performance improvement.
Krishnamurthy, R. "Physical Layer Impairments Aware Transparent Wavelength Routed and Flexible-Grid Optical Networks." Thesis, 2015. http://etd.iisc.ernet.in/2005/3771.
Повний текст джерела"Video Deinterlacing using Control Grid Interpolation Frameworks." Master's thesis, 2012. http://hdl.handle.net/2286/R.I.15048.
Повний текст джерелаDissertation/Thesis
M.S. Electrical Engineering 2012
Wand, Vinzenz [Verfasser]. "Interferometry at low frequencies : optical phase measurement for LISA and LISA pathfinder / von Vinzenz Wand." 2007. http://d-nb.info/987045156/34.
Повний текст джерелаHsu, Chiao-Wei, and 徐喬威. "Resonant Coupling of TE Wave Incidence to Asymmetric Metal-Dielectric Multilayered Structures at Optical Frequencies." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/86518907113110269070.
Повний текст джерела國立中央大學
光電科學與工程學系
101
This thesis employs the transmission line theory and a commercial software package based on Finite-Difference-Time-Domain method to investigate the transverse electric (TE) wave incidence upon two-dimensional planar metal-dielectric multilayered structures at optical frequencies. Results from both approaches show that a minimum reflectance could occur due to the resonant coupling between the incident electromagnetic wave and a guided mode in the high-index layer. From the guided-wave theory, since the phase accumulated by the wave at two boundaries in the guiding layer determines the guidance condition, the resonant coupling is largely affected by the thickness and refractive index of the high-index layer. It changes with the thickness and refractive index of the high-index layer periodically. In addition, under the same structure, since the effective index becomes smaller when the operating wavelength is increased, a smaller incident angle is required to excite the guided mode. On the other hand, metal thickness also affects the full-width-at-half-maximum (FWHM) angle of the reflectance. If the metal thickness becomes thicker, the incident angle required for the resonant coupling gets closer to the critical angle and the FWHM angle is smaller. On the contrary, the required incident angle is closer to when the thickness of the metal is decreased and the corresponding FWHM angle increases. Nevertheless, when the thickness of the metal is large than 60 nm, the TE resonant coupling vanishes.
Cheng-Lin, Sung, and 宋政霖. "Generation of Optical Beat Frequencies from Megahertz to Terahertz with Daul-Wavelength Mode-Locked Lasers." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/u6b46y.
Повний текст джерела國立交通大學
電子物理系所
106
The aim of the thesis is focused on exploring various methods to realize the dual-wavelength lasers at mode-locked operation for generating the optical beat frequencies from megahertz to gigahertz. To begin with, the criterion for the employment of a single gain medium to operate at dual-wavelength oscillation is constructed with a simple formula as a function of the reflectivity of the output coupler, roundtrip cavity losses, and the emission cross section for each desirable lasing wavelength. In the experiments, we design the reflectivity of the output coupler to realize the synchronously self-mode-locked operation at 1064 and 1123 nm in a diode-end-pumped Nd:YAG laser for generation of 14.7-THz optical beat waves and an experiment of the synchronously self-mode-locked operation at 1061 and 1064 nm for achieving 0.67-THz optical beating by exploiting a monolithic Nd:YAG laser under cryogenic process. The two experiments offer a simple way to fulfill the dual-wavelength lasing for the 4F3/2 → 4I11/2 transition in a single Nd:YAG crystal. Next, we demonstrate the dual-gain-media laser systems for emitting the dual-wavelength emissions with the advantage of controllable output intensities for each lasing line. We experimentally utilize a diffusion-bonded Nd:YVO4/Nd:GdVO4 composite crystal and a semiconductor saturable absorber to achieve a dual-wavelength mode-locked laser with full modulation in the 0.31-THz optical beating. For achieving the higher order beat frequency, the other experiment is conducted by coupling the self-mode-locked monolithic Nd:YAG laser with 946-nm emission to an self-mode-locked Nd:YVO4 resonator with 1064-nm emission. With the synchronization of the 1064- and 946-nm mode-locked pulses, the optical beating is up to 35.2 THz. Finally, the simultaneous self-mode-locking of two orthogonally polarized states in Nd:YAG lasers are generated to produce the tunable optical beating. The mechanism of the orthogonal polarized Nd:YAG laser is theoretically and experimentally explained by thermally-induced birefringence of the Nd:YAG crystal. The order of optical beat frequencies induced by pump power is found to be in the order of tens of megahertz. In order to extend the optical beat frequencies between orthogonally polarized components to gigahertz regimes, the mechanical stresses are additionally applied to a monolithic Nd:YAG laser. The experimental results reveal that the beat frequencies can be tuned from 0.14 GHz to 1.48 GHz by controlling the external forces from 0.056 N to 0.620 N.
Hong, Shuo Ting, and 洪碩廷. "A Study on Sub-wavelength Wire-grid Polarizer Used in Optical Approach Accelerometer." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/d3zhys.
Повний текст джерелаWei-MingCheng and 鄭瑋銘. "Study of transformation optics with uniform and non-uniform grid in electro-optical simulation." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/82751147164607532399.
Повний текст джерелаLin, Guan-Cheng, and 林瓘洆. "Improve the Optical Characteristics of Polarized White Light Emitting Diodes with a Nano-wire Grid Polarizer." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/86293787934646930562.
Повний текст джерела國立臺灣科技大學
光電工程研究所
101
The PWLED(Polarized white light-emitting-diode) which packaged with NWGP(Nano-wire grid polarizer) can generate polarized light with high ER(Extinction ratio), improving the problem of the glare in interior lighting and automobile lighting, and having better stability of color performance at different viewing angles and currents than traditional WLED. Because of NWGP’s high ER and the absorption-loss of the metal material, the transmittance of NWGP is limited. In experiment, we realized that scattering and down-conversion of phosphors dominate the PRM(Polarization randomized mechanism) instead of micro-structural surfaces by measuring the PSDF(Polarized scattering distribution function) of phosphor layer in different structural surfaces. So we decide to add the nano-particle resin to the PWLED package for increasing the transmittance of NWGP by promoting the PRP. In terms of same CCT, the transmittance and luminous efficiency of the PWLED which add the nano-particle resin are 0.76% and 0.21 lm/W more than the PWLED which only has phosphor resin. In terms of different CCT, transmittance gain increases with the increase of concentration of nano-particle resin, but the luminous efficiency gain has a maximum in 7% of nano-particle resin is 1.0498, and the transmittance gain is 1.0292 . No matter the CCT of PWLED is changed after adding the nano-particles resin or not, the transmittance of NWGP, luminous efficiency and stability of color performance at different viewing angles and currents will all increase. We can only adjust the concentration of nano-particles resin to get different CCT of PWLED which supply the needs of different applications, enhance the competitiveness of PWLED.
Balagangadhar, B. G. "QoS Aware Quorumcasting Over Optical Burst Switched Networks." Thesis, 2008. http://hdl.handle.net/2005/908.
Повний текст джерелаWu, Bo-Yi, and 吳柏毅. "Using the Excitation Surface Plasma Waves by the Method of Optical Frustrated Total Internal Reflection in Kretschmann configuration to Room Temperature Water at Various Frequencies for Resonating angle influence Measurement." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/01513576699378975769.
Повний текст джерела清雲科技大學
電子工程所
98
This thesis is based on the frustrated total internal reflection and the use of prism-coupled Kretschmann configuration to the surface plasma wave stimulation. Because the water has different dielectric constants at various frequencies, which can be used to stimulate the surface of plasma waves to identify the different water at various frequencies and the depth of absorption sensitively. Th is research is using three-layer formula to do the computer simulation. The computer simulation first focuses on water of different frequencies to analyze and compare and changes the configuration of the Kretschmann metallic film thickness to observe its difference. During the tests of rays designs we first used the helium neon laser assigns out the parallel light to stimulate the surface of plasma wave’s incident photo source and used the revolving platform to change the angle of incident light injection, which will affect the intensity size of the reflected light. Finally we used computer to save the variation data of reflected light''s intensity to the analysis and the research.
Romero, Reyes Ronald. "Online Resource Allocation in Dynamic Optical Networks." 2018. https://monarch.qucosa.de/id/qucosa%3A33916.
Повний текст джерелаConventional optical transport networks have leveraged the provisioning of high-speed connectivity in the form of long-term installed, constant bit-rate connections. The setup times of such connections are in the order of weeks, given that in most cases manual installation is required. Once installed, connections remain active for months or years. The advent of grid computing and cloud-based services brings new connectivity requirements which cannot be met by the present-day optical transport network. This has raised awareness on the need for a changeover to dynamic optical networks that enable the provisioning of bandwidth on demand (BoD) in the optical domain. These networks will have to serve connections with different bit-rate requirements, with random interarrival times and durations, and with stringent setup latencies. Ongoing research has shown that grid computing and cloud-based services may in some cases request connections with holding times ranging from seconds to hours, and with setup latencies that must be in the order of milliseconds. To provide BoD, dynamic optical networks must perform connection setup, maintenance and teardown without manual labour. For that, software-configurable networks are needed that are deployed with enough capacity to automatically establish connections. Recently, network architectures have been proposed for that purpose that embrace flex-grid wavelength division multiplexing, reconfigurable optical add/drop multiplexers, and bandwidth variable and tunable transponders as the main technology drivers. To exploit the benefits of these technologies, online resource allocation methods are necessary to ensure that during network operation the installed capacity is efficiently assigned to connections. As connections may arrive and depart randomly, the traffic matrix is unknown, and hence, each connection request submitted to the network has to be processed independently. This implies that resource allocation must be tackled as an online optimization problem which for each connection request, depending on the network state, decides whether the request is admitted or rejected. If admitted, a further decision is made on which resources are assigned to the connection. The decisions are so calculated that, in the long-run, a desired performance objective is optimized. To achieve its goal, resource allocation implements control functions for routing and spectrum allocation (RSA), connection admission control (CAC), and grade of service (GoS) control. In this dissertation we tackle the problem of online resource allocation in dynamic optical networks. For that, the theory of Markov decision processes (MDP) is applied to formulate resource allocation as an online optimization problem. An MDP-based formulation has two relevant advantages. First, the problem can be solved to optimize an arbitrarily defined performance objective (e.g. minimization of blocking probability or maximization of economic revenue). Secondly, it can provide GoS control for groups of connections with different statistical properties. To solve the optimization problem, a fast, adaptive and state-dependent online algorithm is proposed to calculate a resource allocation policy. The calculation is performed recursively during network operation, and uses algorithms for RSA and CAC. The resulting policy is a course of action that instructs the network how to process each connection request. Furthermore, an implementation of the method is proposed that uses a 3-way handshake protocol for connection setup, and an analytical performance evaluation model is derived to estimate the connection setup latency. Our study is complemented by an evaluation of the capital expenditures of dynamic optical networks. The main cost drivers are identified. The performance of the methods proposed in this thesis, including the accuracy of the analytical evaluation of the connection setup latency, were evaluated by simulations. The contributions from the thesis provide a novel approach that meets the requirements envisioned for resource allocation in dynamic optical networks.
Κρέτσης, Αριστοτέλης. "Μελέτη και ανάπτυξη τεχνικών για την αποτελεσματική διαχείριση πόρων σε δίκτυα πλέγματος και υποδομές υπολογιστικών νεφών". Thesis, 2014. http://hdl.handle.net/10889/8813.
Повний текст джерелаDistributed computing technologies, like grids and clouds, shape today a new environment, regarding the way tasks are executed, data are stored and retrieved, and applications are used. Though grids and desktop grids have been the focus of the research community for a long time, a shift has become evident today towards cloud and virtualization related technologies in general, which are supported by large computing factories, namely the data centers. As a result there is also a shift from the model of several powerful resources distributed at various locations in the world (as in grids) towards fewer huge data centers consisting of thousands of “simple” computers that host Virtual Machines. The research performed over the course of my PhD followed this shift, investigating algorithmic issues in the context of grids and then of clouds and developing a number of tools and applications that manage, monitor and utilize these kinds of resources. Initially, we describe the steps followed, the difficulties encountered, and the solutions provided in developing and evaluating a scheduling policy, initially implemented in a simulation environment, in the gLite grid middleware. Our focus is on a scheduling algorithm that allocates in a fair way the available resources among the requested users or jobs. During the actual implementation of this algorithm in gLite, we observed that the validity of the information used by the scheduler for its decisions affects greatly its performance. To improve the accuracy of this information, we developed an internal feedback mechanism that operates along with the scheduling algorithm. Also, a Grid computation resource cannot be shared concurrently between different users or jobs, making it difficult to provide actual fairness. For this reason we investigated the use of virtualization technology in the gLite middleware. We implement and evaluate our scheduling algorithm and the proposed mechanisms in a small gLite testbed. Next, we present a methodology, called communication-aware virtual infrastructures (COMAVI), for the concurrent migration of multiple Virtual Machines (VMs) in computing infrastructures, which aims at the optimum use of the available computational and network resources, by capturing the interdependencies between the communicating VMs. This methodology uses multiple criteria for selecting the VMs that will migrate, with different weights assigned to each of them. COMAVI also selects the computing sites where the migrating VMs will be hosted, by accounting for the way migration affects the logical (or virtual) topologies formed by the communicating VMs and viewing this selection as a logical topology reconfiguration problem. We apply COMAVI to two basic computing infrastructures that exhibit different constraints/criteria and characteristics: a grid infrastructure operating over a wide area network (WAN) and a data center infrastructure operating over a local area network (LAN). Through the presented methodology different communication-aware VM migration algorithms can be tailored to the needs of the resource provider. The algorithms presented resolve the maximum possible number of VM violations (due to computing or communication resource shortages), while tending to minimize the number of migrations performed, the induced network overhead, the logical topology reconfigurations required, and the corresponding service interruptions. We evaluate the proposed methods through simulations in realistic computing environments, and we exhibit their performance benefits. We also consider the use of social network analysis methods on communication traces, collected from Virtual Machines (VMs) located in computing infrastructures, like a data center. Our aim is to identify important VMs, for example VMs that require more bandwidth than other VMs or VMs that communicate often with other VMs. We believe that this approach can handle the large number of VMs present in computing infrastructures and their interactions in the same way social interactions of millions of people are analyzed in today’s social networks. We are interested in identifying measures that can locate these important VMs or groups of interacting VMs, missed through other usual metrics and also capture the time-dynamicity of their interactions. In our work we use real traces and evaluate the applicability of the considered methods and measures. In addition, we consider the analysis and optimization of public clouds. For this reason, we identify important algorithmic operations that should be part of a cloud analysis and optimization tool, including resource profiling, performance spike detection and prediction, resource resizing, and others, and we investigate ways in which the collected monitoring information can be processed towards these purposes. The analyzed information is valuable since it can drive important virtual resource management decisions. We also present an open-source tool we developed, called SuMo, which contains the necessary functionalities for collecting monitoring data from Amazon Web Services (AWS), analyzing them and providing resource optimization suggestions. We also present a Cost and Utilization Optimization (CUO) mechanism for optimizing the cost and the utilization of a set of running Amazon EC2 instances, which is formulated as an Integer Linear Programming (ILP) problem. This CUO mechanism receives information regarding the current set of instances used (their number, type, utilization) and proposes a new set of instances for serving the same load, so as to minimize cost and maximize utilization and performance efficiency. Finally, we present a network planning and operation tool, called Mantis, for designing the next generation optical networks, supporting both flexible and mixed line rate WDM networks. Through Mantis, the user is able to define the network topology, current and forecasted traffic matrices, CAPEX/OPEX parameters, set up basic configuration parameters, and use a library of algorithms to plan, operate, or run what-if scenarios for an optical network of interest. Mantis is designed to be deployed either as a cloud service or as a desktop application. Using the cloud infrastructures features Mantis can scale according to the user demands, executing fast and efficiently the scenarios requested. Mantis supports different cloud platforms either public such as Amazon Elastic Compute Cloud (Amazon EC2) and ~okeanos the GRNET’s cloud service or private based on OpenStack, while its modular architecture allows other cloud infrastructures to be adopted in the future with minimum effort.