In this study, to discuss the effect of the boundary between pipeline and clamp support changed by different pressures to the propagation of guided wave in the pipeline is the main idea. In addition, the author simulates the wave propagation situation by using finite element method. In this work, T(0,1) torsional mode was used to discuss when adding different pressures to the clamp support, the change of its reflection coefficients in different frequencies by the axial symmetric property propagates in the cylinder pipe. In the simulation, we take the ¡§fictitious layer¡¨ was used to describe the situation between the clamp support and pipeline when adding different pressures. Moreover, the stiffness normal to the fictitious layer and the stiffness parallel to the fictitious layer were taken as material parameters to achieve the situation between clamp support and pipeline. According to experimental results, when the torque increases, the reflection coefficients will decrease with increasing frequency. The reflection coefficients are about 0.08 to 0.02. By the result of experiment and simulation, one can know that when adding torque on the clamp support increases, the reflection coefficient will decrease. In addition, the author also prove that if we change the stiffness parallel to the fictitious layer material factor, then the T(0,1) guided wave will be more sensitive by its action of particle motion.

In the past decades, considerable effort has been put into developing high resolution geological models for oil and gas reservoirs. Although the growth of computational power is rapid, the static model size still exceeds the model size for routine reservoir simulation. We develop and apply a variety of grid coarsening and refinement algorithms and single and multiphase upscaling approaches, applied to tight gas and conventional reservoir models. The proposed research is organized into three areas. First the upgridding of detailed three dimensional geologic models is studied. We propose an improved layer design algorithm with considerations of accuracy and efficiency. This involves developing measures of reservoir heterogeneity and using these measures to design an optimal grouping of geologic model layers for flow simulation. The optimal design is shown to be a tradeoff between the desire to preserve the reservoir heterogeneity and a desire to minimize the simulation time. The statistical analysis is validated by comparison with flow simulation results. Accurate upgridding/upscaling of single-phase parameters is necessary. However, it does not always satisfy the accuracy requirements, especially for the model which is aggressively coarsened. We introduce a pseudoization method with total mobility and effective fractional flow as the major targets. This pseudoization method helps to push upgridding/coarsening degree to the limit but still be able to reproduce the fine scale field performance. In practice, it is common to not use a different set of pseudos for every coarse cell; only a limited number of pseudo functions should be generated for different “rock types” or geological zones. For similar well patterns and well control conditions, applying pseudo is able to reproduce the fine scale performance for different simulation runs. This is the second proposed research area. Finally, it is necessary to increase flow resolution for precise field history matching and forecasting. This has received increasing attention, especially when studying hydraulically fractured wells in unconventional reservoirs. We propose a multiscale reservoir simulation model combining local grid refinement (LGR) and pillar-based upscaling for tight gas reservoir performance prediction. Pillar-based coarsening away from the wells is designed for tight gas reservoirs. It compensates for the extra computational cost from LGR, which is used to represent hydraulic fractures. Overall reservoir performances, including the accuracy and efficiency, are evaluated.

This thesis presents several simple, robust, and optimal resource management schemes for multihop wireless access networks with the main focus on multi-channel wireless mesh networks (MC WMNs). In this regard, various resource management optimization problems are formulated arid efficient algorithms are proposed to solve each problem. First, we consider the channel as signment problem in MC-WMNs and formulate different resource management problems within the general framework of network utility maximization (NUM). Unlike most of the previously proposed channel assignment schemes, our algorithms can not only assign the orthogonal (i.e., non-overlapped) channels, but also partially overlapped channels. This better utilizes the avail able frequency spectrum as a critical resource in MC-WMNs. Second, we propose two distributed random medium access control (MAC) algorithms to solve a non-convex NUM problem at the MAC layer. The first algorithm is fast, optimal, and robust to message loss and delay. It also only requires a limited message passing among the wireless nodes. Using distributed learning techniques, we then propose another NUM-based MAC algorithm which achieves the optimal performance without frequent message exchange. Third, based on our results on random MAC, we develop a distributed multi-interface multi-channel random access algorithm to solve the NUM problem in MC-WMNs. Different from most of the previous channel assignment schemes in the literature, where channel assignment is intuitively modeled in the form of combinatorial and discrete optimization problems, our scheme is based on formulating a novel continuous optimization model. This makes the analysis and implementation significantly easier. Finally, we consider the problem of pricing and monetary exchange in multi-hop wireless access networks, where each intermediate node receives a payment to compensate for its offered packet forwarding service. In this regard, we propose a market-based wireless access network model with two-fold pricing. It uses relay-pricing to encourage collaboration among the access points. It also uses interference pricing to leverage optimal resource management. In general, this thesis widely benefits from several mathematical techniques as both modeling and solution tools to achieve simple, robust, optimal, and practical resource management strategies for future wireless access networks.

Las cintas superconductoras de alta temperatura (HTS) han emergido como materiales prometedores para sus uso en el campo de l'energía puesto que permiten reducir a mitad el tamaño de los equipos de energía eléctrica respecto a los convencionales, reducir las pérdidas de energía, aumentar la eficacia en la generación, la transmisión y la distribución de la misma, y así la reducir el impacto ambiental.Sin embargo, diversamente de los conductores típicos, los materiales superconductores basados en óxido son frágiles, se dañado fácilmente y son así difíciles de procesar. Hasta ahora ha sido posible producir longitudes de un kilómetro de cables HTS de primera generación, para el uso en el trasporte de corriente eléctrica. Las cintas superconductoras de YBCO, por ejemplo, pueden soportar altas densidades de corrientes críticas y por esto representan un candidato prometedor en el trasporte de electricidad.Uno del los substratos disponible para suportar el superconductor es un acero policristalino con una película epitaxial de YSZ en cima, YSZ(IBAD)/Stainless. El segundo que hemos utilizado es el NiO(SOE)/Ni(Rabit), una cinta de nickel previamente texturada por laminación y sucesivamente oxidata de manera controlada. Numerosas técnicas están disponible para la deposición de YBCO epitaxiale, nosotros elegimos el proceso más barato y industrialmente interesante: la técnica sol-gel. Para evitar la interacción entre el YBCO superconductor y el substrato epitaxial, evitando así la reducción de la corriente que el superconductor puede trasportar, es importante interponer un material inerte que transfiera su epitaxia al YBCO; este clase de películas se llaman capas tampón. El objetivo principal de esta tesis ha sido optimizar el crecimiento de las capas tampón por técnica química y finalmente estudiar la deposición del YBCO por TFA sobres esas muestras optimizadas. Las capas de cerámica que hemos estudiados han sido: CeO2, BaZrO3, CaZrO3, SrZrO3, SrTiO3, BaCeO3 , y depositadas por el método químico: metal 2-4-&#61538;-diketone disuelto en ácido acético, o los metales isopropoxidos disuelto en metanol. Por depositar las soluciones precursoras hemos utilizado la técnica de spin coating. Controlando los diversos parámetros, velocidad, aceleración y la concentración de la solución obtuvimos películas homogéneas con diverso grosor. La fase de la cristalización se alcanza en un horno donde se controla l'atmósfera, la temperatura y la velocidad de calefacción. Durante esta investigación hemos adquirido un conocimiento total del acrecimiento de las películas delgada de MOD-CeO2. De una combinación de las análisis de TEM, de XRD y de RHEED observamos que el mecanismo de crecimiento tiene un comportamiento anómalo comparado con el otro materiales crecidos con la misma técnica.En este proceso de síntesis de la ceria, la nucleation homogénea de hecho esta favorita debido al bajo valor de Tnuc./Tmel ceria (Tnuc./Tmel=0.21). Solamente los granos nucleados sobre el substrato resultan texturados. La dependencia del tamaño de grano con temperatura sigue una relación de tipo Arrhenius, características de un crecimiento 3D del grano. Los análisis de EELS revelaron una fracción significativa de C residual que adorna los límites de grano, es probable que el crecimiento del límite de grano se quede bloqueando debido estas impurezas.Un proceso del recocido en aire a posteriores, ha demostrado la posibilidad de crecer las películas de CeO2 totalmente epitaxiales. Los análisis de EELS de tales muestras tratadas en oxígeno demuestran claramente que los límites de grano quedan limpios de las impurezas de C, desbloqueando así el crecimiento del grano. Después de un proceso largo de optimización de los parámetros de síntesis, podemos ahora controlar exactamente el crecimiento epitaxiale de la ceria. Se ha verificado que el óxido del cerio se puede crecer en YSZ(IBAD)/SS con solamente la orientación (00l). Para preservar la cinta del metal contra la oxidación, el proceso optimizado se ha adaptado a la deposición sobre substrato de acero inoxidable reduciendo la temperatura de síntesis a 900ºC. Hemos optimizado también la preparación de SrTiO3(STO) y BaZrO3(BZO) sobre MgO y YSZ mono-cristales y en seguida también sobre YSZ(IBAD)/SS y NiO(SOE)/Ni.La arquitectura más prometedora resultó ser STO/BZO/NiO(SOE)/Ni. Por ultimo depositamos YBCO por método TFA (Trifluoracéticetatos) sobre las capas tampones optimizadas. Una muestra de TFA-YBCO sobre CeO2/YSZ(IBAD)/SS preparada en aire a 900ºC en 8 h ha dato como resultado una densidad corriente crítica, Jc de 7 MA/cm2 a 5K, y 6·105A/cm2 a 77K. Estos valores están cerca de objectivo de un millón A/cm2 a 77K. Los experimentos sobre las capas tampón de BZO y de STO han demostrado la posibilidad de usar este sistema doble sobre NiO(SOE)/Ni como plantilla alternativa para el crecimiento de YBCO. Alcanzado una densidad de corriente crítica de Jc(5K) = 5·105A/cm2 con la mejor muestra de YBCO/STO/BZO/NiO(SOE)/Ni. / High-temperature superconducting (HTS) tapes have emerged as promising materials for superconducting power applications since they make possible electric power equipment that is half the size of conventional alternatives, with half energy losses, increasing the efficiency in the generation, transmission and distribution of the electric energy, and thus reducing the impact of power delivery on the environment. However, unlike typical conductors, oxide based superconductor materials are brittle and easily damaged and thus they are difficult to process and handle, specially forming large and flexible wires.Up to now it has been possible to produce kilometre lengths of the first generation of HTS wires for use in electrical transmission cables. YBCO coated conductors can support high critical current densities and is a promising candidate. One of the substrate available is a polycrystalline metal substrate with an epitaxial YSZ film on it, the ion-beam assisted deposition YSZ(IBAD)/Stainless Steel. The second is the textured NiO(SOE)/Ni(Rabit).Numerous methods are available for epitaxial deposition of YBCO, including vacuum techniques but we choose the cheaper non vacuum sol-gel processes.To avoid the interaction between the superconductor it is important to interpose a inert material that can transfer the epitaxy from the substrate to the YBCO, these kind of films are called buffer layers, avoiding than the reduction of the current that the superconductor can support. The main aim of this thesis was optimising the buffer layer growth by chemical technique and finally studying the deposition of TFA-YBCO on those optimised templates.The ceramic buffer layers studied:CeO2 , BaZrO3 , CaZrO3, SrZrO3, SrTiO3,BaCeO3The Sol-Gel system used was the Metal &#61538;-diketone dissolved in Acid Acetic, or Metal isopropoxide dissolved in methanol.The deposition step was performed by spin coating. Controlling the different parameters of rate and acceleration of the spinner and the precursor solution concentration we obtained homogenous films with different thickness. The crystallisation step is achieved in a furnace in a controlled atmosphere, temperature and heating rate.Important knowledge on the MOD-CeO2 thin film growth has been acquired during this research. From a combination of TEM, XRD and RHEED analyses it was observed that its growth mechanism exhibits an anomalous behaviour compared with other CSD derived films. The homogeneous nucleation in fact is favoured in this MOD process due to the low Tnuc./Tmel value for ceria film (Tnuc./Tmel=0.21). Only grains nucleated on the substrate are textured as observed in XTEM images. The grain size dependence with temperature follows an Arrhenius relation: <r>2=&#61537;otexp(-Q/kT), characteristics of 3D undergoing thermally activated grain growth . EELS analyses revealed a significant fraction of residual C decorating the grain boundaries, that very likely acts as a growth by blocking grain boundary motion. A process of post annealing or direct growth in static air, have demonstrated the possibility of growing completely epitaxial CeO2 films. EELS analyses of such samples clearly demonstrates that the oxygen clean up grain boundaries from C impurities thus unblocking grain growth. After a long process of synthesis parameter optimisation, we are now able to control exactly the epitaxial growth of ceria growth. It has been verified that Cerium oxide can be grown on YSZ(IBAD)/SS with only the (00l) orientation. The optimised process has been adapted to stainless steel substrate reducing the synthesis temperature at 900ºC in order to preserve the metal tape against oxidation. We observed an interesting phenomenon of in plane texture improvement of the ceria film with respect to the underlying YSZ(IBAD)/SS substrate, from &#61508;&#61542;YSZ = 8.3º and to &#61508;&#61542;CeO2 = 7.5º.The solution preparation and the deposition conditions for STO and BZO on MgO and YSZ have been also optimised. After several experiments of buffer deposition on YSZ(IBAD)/SS and NiO(SOE)/Ni technical metal substrates the most promising architecture resulted to be the STO/BZO/NiO(SOE)/Ni. We have grown YBCO by the TFA(Trifluor Acetic Acid) method on the optimized buffer layers. A sample of TFA-YBCO on a CeO2/YSZ(IBAD)/SS template prepared in air at 900ºC for 8 h has shown a critical current density, Jc has a value of 7 MA/cm2 at 5K, and 6·105A/cm2 at 77K. These values are near the target of one million A/cm2 at 77K. The experiments on BZO and STO buffer layers have demonstrated the possibility of using the double buffer on NiO(SOE)/Ni as an alternative template for YBCO deposition. A critical current density of Jc(5K)= 5·105A/cm2 has been achieved for the best sample of YBCO/STO/BZO/NiO(SOE)/Ni.

No description available.

Wireless communication is of great importance for safety and entertainment purposes in vehicular networks. Vehicles on roads are required to share sensor data, road traffic information or digital maps with other vehicles on the road. To be able to do this, vehicles require to either communicate directly with each other or to be connected to a wireless communication-based access points on the road side. These wireless access points support short to medium range wireless communication through the protocol 802.11p. 802.11p is designed specifically for vehicular communication and it is an amended form of the widely used 802.11 protocol suit for wireless local area networks (WLAN). Vehicles are able to be associated with these wireless access points for exchange of information. While vehicles move along the road infrastructure, they change their point of attachment from one wireless access point to another wireless access point. During this process, connectivity to the access point breaks down until the vehicle is connected to a new access point in its area. This disconnection causes an interruption in the data flow. This interruption increases when vehicle requires a new IP address, i.e. when the vehicle is going to attach to an access point which is part of another network. In this thesis report, we give an overview of standard handover methods and their enhancements and propose a fast handover scheme for layer 3 of the communication stack. Based on the assumption that vehicles know their route in advance, we enhance the handover process and improve seamless connectivity. We also discuss different issues which are the cause of delay and how they can be overcome in our proposed solution.

Non-repudiation techniques are to ensure any communication taking place between two or more parties will be undeniable. Therefore it is crucial to include digital signatures of the involving parties while the communication is taking place. In medical practices, involved parties include; patient(s), doctor(s), pharmacist(s), who are involved in series of visits, diagnosis, prescriptions, and possible operations. To avoid possible conflicts, deploying non-repudiation techniques help immensely. This thesis considers this issue in a wireless medium and studies the Quality of Service (QoS)/Security requirements in terms of network parameters and performance metrics. In terms of research contributions, this thesis embodies a thorough research on layered and cross-layer QoS and security schemes, in particular, featuring an adaptive Forward Error Correction (FEC) at the application layer, adapting to channel conditions. This leads to a cross layer design, which considers various QoS and security parameters export and import to and from various layers with a special focus on the application layer. The aim of this thesis is to consider a practical implementation and associated complexities of a non-repudiation system, including analytical and experimental testbeds and results. The security schemes are based on Suite-B cryptographic algorithms, including: The Elliptic Curve Diffie-Hellman (ECDH) for key agreement, the Advanced Encryption Standard - Galois/Counter Mode (AES-GCM) for encryption and authentication, the Elliptic Curve Digital Signature Algorithm (ECDSA) for digital signatures, and the Secure Hash Algorithm (SHA) for integrity. A key aspect of Suite-B is the deployment of Elliptic Curve Cryptography (ECC). The non-repudiation aspect of this thesis is based on the Suite-B’s digital signature scheme; ECDSA. The digital signature and the hashing function target the entire multimedia data (i.e., text, video, and voice) and the challenge is to offer such extensive security treatment, while guaranteeing certain Quality of Service settings. These settings include: minimum round trip delay, maximum overhead, and minimum bandwidth allocation.

Die Arbeit untersucht den Einfluss des pH - Wertes auf die Fluoreszenzintensität von Multischichtsystemen während des Beschichtungsvorgangs von Siliziumdioxidpartikeln mit kovalent an Polyallylaminhydrochlorid (PAH) gebundenem Rhodamin - B - Isothiocyanat. Durch eine konsequente Pufferung mit 2 -(N - Morpholino)ethansulfonsäure während der Beschichtung kann eine Verbesserung der Homogenität der Schichtbildung und eine Erhöhung der Fluoreszenzintensität erreicht werden. Außerdem liegt eine lineare Steigerung der Fluoreszenzintensität proportional zur Anzahl der fluoreszenten Schichten vor. Weiterhin sollen kolloidale Partikel unter konstanter Pufferung zusätzlich zu Rhodamin – B – Isothiocyanat mit an PAH – gebundenem Fluoresceinisothiocyanat beschichtet werden. Dieses Farbstoffpaar weist bei Annäherung eine Fluoreszenzsteigerung durch einen Fluoreszenzresonanzenergietransfer aus. Durch Variation von Schichtanzahl und Abstand wurden verschiedene Partikelpopulationen hergestellt, die sich in Ihrer Fluoreszenzintensität analog zu einem Bead Array Assay im Durchflusszytometer klar differenzieren lassen und dabei auch eine gleichmäßige Steigerung der Fluoreszenzintensität analog zur Anzahl der fluoreszenten Schichten aufweisen.

The past decade and a half has seen the rapid emergence of a new material class known as photonic crystals (PCs), structures that exhibit 1, 2, or 3, dimensional periodicity of their dielectric constant, resulting in a modification of the dispersion characteristics from the normal w = vk relationship found in isotropic materials. Several remarkable electromagnetic phenomenon result, including the formation of photonic band gaps (PBGs), which are specific energy ranges where electromagnetic wave propagation is forbidden, and the existence of energies where the photon group velocity is slowed drastically from its normal value. The resulting modification of a materials photonic band structure allows unprecedented control of light, resulting in phenomena such as self-collimation, and spontaneous emission modification or lasing threshold reduction through either band edge effects (low group velocity) or microcavity defect incorporation. PCs for operation at visible wavelengths are difficult to form due to the need for nanoscale fabrication techniques. The research described focused on the fabrication of photonic crystal phosphors by using the infiltration and subsequent removal of self-assembled opal templates to make inverted opal-based photonic crystals. This thesis shows the advantages that atomic layer deposition (ALD) has as an important method for use in photonic crystal fabrication, and highlights the exciting results of use of ALD to fabricate luminescent ZnS:Mn and optically inactive titania inverse opals, as well as ZnS:Mntitania luminescent composite inverse opals.

Since the diamond like carbon features include high hardness and high wear resistance, low friction coefficient, chemical inertness, high resistance, low dielectric constant, the IR Transparency and field emission. The process of Diamond carbon film was usually by CVD or PVD techniques. However, high substrate temperature or low deposition rate and the can not make large area of films leads to limit the applications of diamond like film. Electrodeposition method is an innovative method to prepare DLC film and it meets these demands such as: equipment cheap, high deposition rate and larger area coatings. In this paper, ITO substrate was used for electrodeposition the diamond-like carbon films and to evaluate the possibility for the large area of DLC films.For the process of electrical deposition, the electrolyte consists of acetic acid and DI water mixed in different proportions. The deposition process were conditioned as: electrolyte concentration between 0.01% and 0.8%; voltage from 2.1V to 50V; growth temperature in the range of 300C ~ 850C. In addition, by using the control variables method, the deposition parameters including voltage, deposition temperature and solution concentration of electrolyte were varied to evaluate the characteristics and quality of diamond-like carbon films. The n & k film analyzer (n & k Analyze), X ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) were used to characterize the surface morphology, microstructure and compositional analysis. The reflectivity, transmittance, and refractive index of DLC Films were revealed by the n & k analyzer. Hence, the best conditions used for anti-reflective layer and projections Eopg can be achieved. For SEM analysis, the DLC film with uniformity surface structure can be found. Additionally, the current - time graph can be used to predict the properties of film varied with the applied voltage, percent of concentrations, growth temperature etc.. The microstructure of DLC film was investigated by the XPS measurement; the sp2 / sp3 ratio varies from the growth parameters changes. The hydrogen content of DLC films was obtained by FTIR measurements, the contents decrease as the operating voltage, electrolyte concentration and the substrate temperature increase. As for the DLC deposited on ITO glass as an anti-reflective layer, the experimental results showed that DLC film can reduce the reflectivity from 40% to 70%. Finally, the results obtained show a reasonable match for various measurements. T he characteristics of DLC films also shows that it very depends on the deposited parameters and the relationship beteen them was discussed in detailed. Some of the advance study will be investigated in future.