This thesis describes the application of Large-Eddy Simulation (LES) to the internal flows within turbomachines. In particular, the work sought to investigate whether LES could give an improved predictive tool for flows through a turbine rim seal where other methods of modelling turbulence give disappointing results for the simulation of hot annulus gas ingestion into the rim seal cavity. The applicability of LES to flow regimes within a rotor-stator cavity were investigated with reference to two experimental studies, those of Daily & Nece [1] and of Itoh et al. [2]. LES simulations were run using the commercial Computational Fluid Dynamics (CFD) code FLUENT and the Rolls-Royce CFD code HYDRA. Both gave good agreement for the velocity field even when the boundary layer was not fully resolved. HYDRA was then used to simulate a turbine rim seal cavity with external flow through an annulus with NGV and rotor blades, modelled using a small sector with periodic boundary conditions in the circumferential direction. LES was found to predict higher levels of ingestion than Unsteady Reynolds- Averaged Navier-Stokes (URANS) simulations at a number of different values of cavity throughflow. This resulted in better, but not close, agreement with the experiments of Gentilhomme [3]. The sensitivity of the LES to changes in the size of the sector and to the resolution of the CFD grid were investigated. A larger sector simulation, corresponding to 40°, gave almost identical results to those on the smaller sector, 13.3°. Refinement to the CFD grid did lead to different results, particularly in the annulus flow, though critically the prediction of ingestion in the stator boundary layer was largely unaffected.

L. J. Chu, H. A. Haus and P. Penfield, Jr. / Cover title. / Includes bibliographical references (p. 39). / Supported by the Joint Services Electronics Programs (U.S. Army, U.S. navy, and U.S. Air Force) DA36-039-AMC-03200 (E)

In this thesis we study the essential spectrum of composition operators on the Hardy space of the unit disc and of the upper half-plane. Our starting point is the spectral analysis of the composition operators induced by translations of the upper half-plane. We completely characterize the essential spectrum of a class of composition operators that are induced by perturbations of translations

In this study, we investigate several facets of a due-date quotation problem and develop a model considering jointly due-date quotation, order acceptance and base-stock decisions in a hybrid make-to-stock (MTS) / make-to-order (MTO) and multi-class system with lead time sensitive Poisson demand and exponentially distributed service times. We seek to maximize profit considering lateness penalties and holding costs in the model. We consider three alternative due-date quotation policies each having different properties in terms of due-date flexibility as well as the utilization of state information. In order to evaluate the value of due-date flexibility as well as state information, the performances of the optimal policy and alternative policies are evaluated for various performance measures under different operating conditions. We also discuss the benefit of joint pooling of inventory and capacity under optimal policy and an accept-all policy.

The generalized moment of order k of a mass distribution sigma for a natural number k is given by integral of lambda to the power k with respect to mass distribution sigma and variable lambda. In extended moment problem, given a sequence of real numbers, it is required to find a mass distribution whose generalized moment of order k is k&#039 / th term of the sequence. The conditions of existence and uniqueness of the solution obtained by Hamburger are studied in this thesis by the use of orthogonal polynomials determined by a measure on real line. A chapter on the study of asymptotic behaviour of orthogonal functions on compact subsets of complex numbers is also included.

Existence of basis in locally convex space has been an important problem in functional analysis for more than 40 years. In this thesis the conditions for the existence of basis are examined. These thesis consist of three parts. The first part is about the exterior interpolative conditions. The second part deals with the inner interpolative conditions on nuclear frechet space. These are sufficient conditions on existence of basis. In the last part, it is shown that for a regular nuclear K&ouml / the space the inner interpolative conditions are satisfied and moreover another type of inner interpolative conditions are introduced.

In this thesis, I present 4 new, high-resolution observations of the Galactic microquasar SS 433, obtained from the Very Long Baseline Array (VLBA). I show that we can resolve the same ejecta in successive observations separated by ~ 35 d. I will demonstrate a method to uniquely determine launch vectors of the jet bolides, and I use this unprecedented baseline in time to show that the expansion rate of these bolides may reach 0.03c. I also present the first scientific results from the study of the radio jets in a unique set of historic observations of SS 433: the 39 images that comprise the 2003 VLBA movie of Mioduszewski et al. (2004). This unmatched time sampling allows us to see daily changes in the dynamics of SS 433's jets. I present evidence that these observations caught SS 433 as it transitioned from quiescence into a flare, and I show that this manifests itself as an increase in both the jet launch speed and the brightness of the jet bolides. Using these data, I examine the evolution of the particle energies, densities and magnetic fields within the bolides. We see that the estimates of the mass-loss rates via the jets cannot be reconciled with the those inferred from X-ray or optical data, if we posit equipartition of energy in synchrotron emitting plasma. The time resolution of the 2003 data allows us to observe the flux evolution of the jet bolides, and I show that the bolides undergo a power law decay as t^−2.8. Lastly, I examine X-ray monitoring data from the Swift/BAT satellite and the MAXI All-Sky- Monitor. From these lightcurves, I examine the geometry of the X-ray emission from close to the compact object itself, and I discuss SS 433's place within the current paradigm of accretion in microquasars. Throughout, we will see that it is the accessible time scales of the SS 433 phenomenon that allow us to learn about its exciting, complex physics.

This diploma thesis contains description and realization of smart home system SmartFlat. In the first part of the thesis is analysis of issue and listing of most common variants of home systems with examples. Further into the thesis is the description of parts of system SmartFlat, hardware solution of main unit and there are also explained core software functions of the system. At the end of this thesis are commented results of debugging and testing with real peripheral devices. Conclusion at the end includes brief summary of diploma thesis and commentary of achieved results.

One channel model that characterises multipath fading effect of a wireless channel is called Flat Rayleigh Fading channel model. Given the properties of Flat Rayleigh Fading channel, an equation to find the capacity of a Flat Rayleigh fading channel with hard decision decoding is derived. The difference of power requirement to achieve the Additive White Gaussian Noise (AWGN) capacity over a Flat Rayleigh Fading channel fading is found to increase exponentially with Es /N0 . Upper and lower bounds of error performance of linear block codes over a Flat Rayleigh Fading channel are also studied. With the condition that the excess delay of a channel is known earlier, it is shown that a correlator with shorter length, according to excess delay of the channel, can be constructed for use in wireless channel response measurements. Therefore, a rule of construction of a shorter length correlator is defined, involving concatenation of parts of a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence. Simulation of [136,68,24] Double Circulant Code with Dorsch List Decoding is also done in order to evaluate error performance of the channel coding scheme over one of the IEEE Wireless Metropolitan Area Network (WirelessMAN) channel models, the Stanford University Interim Channel Model No. 5 (SUI-5) channel. Performance of the channel cod- ing was severely degraded over the SUI-5 channel when it is compared to its performance over the AWGN channel. Indoor path losses within three multifloor office buildings were investigated at 433 MHz, 869 MHz and 1249 MHz. The work involved series of extensive received signal strength measurements within the buildings for all of the considered frequencies. Results have shown that indoor path loss is higher within a square footprint building than indoor path loss in a rectangular building. Parameters of Log-Distance Path Loss and Floor Attenuation Factor Path Loss models have been derived from the measurement data. In addition, a new indoor path loss prediction model was derived to cater for path loss pre- diction within multifloor buildings with indoor atriums. The model performs with better prediction accuracy when compared with Log-Distance Path Loss and Floor Attenuation Factor Path Loss models.

La capacité à se localiser est d’une importance cruciale pour la navigation des robots. Cette importance a permis le développement de plusieurs techniques de localisation de grande précision. Notre contribution consiste à proposer un passage de la technique de localisation visuelle inertielle du cas individuel, au cas multi collaboratif. Ce travail a pour objectif d’aboutir à une localisation collaborative aussi rapide, robuste et précise que la technique individuelle de départ. Notre approche se base sur le filtrage en couplage serré Multi State Constraint Kalman Filter (MSCKF) pour la fusion de données. Les caractéristiques de ce filtrage sont d’abord étudiées dans le cas individuel pour tester la robustesse et la précision dans différentes conditions et avec différents modèles d’observation. Les résultats de cette étude nous ont orienté vers la structure la mieux adaptée à une augmentation au cas de localisation collaborative. L’algorithme collaboratif proposé, est basé sur un processus hiérarchique en trois étapes. Une localisation collaborative est initialisée sur la base des mesures relatives de distances Ultra Large Bande (ULB). Une localisation collaborative améliorée se base ensuite sur le chevauchement des images en utilisant un modèle de mesure adapté, et une structure de fusion de données qui absorbe l’excédent en temps de calcul provoqué par le traitement collaboratif. Enfin, pour augmenter la précision, une extraction des contraintes de structure environnement, suivie d’une intégration à l’aide d’une troncature dans le filtre sont proposées. / Localization is of crucial importance for robots navigation. This importance has allowed the emergence of several precise localization techniques. Our contribution consists of proposing a transition from an individual inertial visual localization technique to the multi-robots collaborative localization case. This work aims to achieve a collaborative localization as fast, robust and accurate as the individual starting technique. We adopt a tightly coupled MSCKF (Multi State Constraint Kalman Filter) approach to achieve the data fusion. The characteristics of this data fusion are first studied in the individual case to test the robustness and the precision under different conditions and with different observation models. The results of this study directed us towards the best structure adapted to an augmentation to the collaborative localization case. The proposed collaborative algorithm is a hierarchical process of three stages. A collaborative localization is initialized based on the relative distance measurements using Ultra-Wide Band (ULB) sensors. Then, a collaborative localization based on images overlapping using a suitable measurement model, and a data fusion structure that absorbs the computation time excess caused by the collaboration is achieved. Finally, to increase precision, an extraction of the environment constraints, followed by an integration using a truncation in the filter are proposed.