The possibility of misalignments at interfaces would be increased due to individual parts' assembly and external factors during its operation. In actual engine representative conditions, the upstream misalignments have effects on turbines performance through the nozzle guide vane passages. The current experimental aerodynamic investigation over the nozzle guide vane passage was concentrated on the backward-facing step of upstream misalignments. The tests were performed using two types of vane endwall platforms in a 2D linear cascade: flat endwall and axisymmetric converging endwall. The test conditions were a Mach number of 0.85, Re_ex 1.5*10^6 based on exit condition and axial chord, and a high freestream turbulence intensity (16%), at the Virginia tech transonic cascade wind tunnel. The experimental results from the surface flow visualization and the five-hole probe measurements at the vane-passage exit were compared with the two cases with and without the backward-facing step for both types of endwall platforms. As a main source of secondary flow, a horseshoe vortex at stagnation region of the leading edge of the vane directly influences other secondary flows. The intensity of the vortex is associated with boundary layer thickness of inlet flow. In this regard, the upstream backward-facing step as a misalignment induces the separation and attachment of the inlet flow sequentially, and these cause the boundary layer of the inlet flow to reform and become thinner locally. The upstream-step positively affects loss reduction in aerodynamics due to the thinner inlet boundary layer, which attenuates a horseshoe vortex ahead of the vane cascade despite the development of the additional vortices. And converging endwall results in an increase of the effect of the upstream misalignment in aerodynamics, since the inlet boundary layer becomes thinner near the vane's leading edge due to local flow acceleration caused by steep contraction of the converging endwall. These results show good correlation with many previous studies presented herein. / Master of Science

Although spectral methods have been in use for decades, there is still room for innovation, refinement and improvement of the methods in terms of efficiency and accuracy, for generalized homogeneous turbulent flows, and especially for specialized applications like the computation of atmospheric flows and numerical weather prediction. In this thesis, two such innovations are presented. First, inspired by the adaptive mesh refinement (AMR) technique, which was developed for the computation of fluid flows in physical space, an algorithm is presented for accelerating direct numerical simulation (DNS) of isotropic homogeneous turbulence in spectral space. In the adaptive spectral resolution (ASR) technique developed here the spectral resolution in spectral space is dynamically refined based on refinement criteria suited to the special features of isotropic homogeneous turbulence in two, and three dimensions. Applying ASR to computations of two- and three-dimensional turbulence allows significant savings in the computational time with little to no compromise in the accuracy of the solutions. In the second part of this thesis the effect of explicit filtering on large eddy simulation (LES) of atmospheric flows in spectral space is studied. Apply an explicit filter in addition to the implicit filter due to the computational grid and discretization schemes in LES of turbulent flows allows for better control of the numerical error and improvement in the accuracy of the results. Explicit filtering has been extensively applied in LES of turbulent flows in physical space while few studies have been done on explicitly filtered LES of turbulent flows in spectral space because of perceived limitations of the approach, which are shown here to be incorrect. Here, explicit filtering in LES of the turbulent barotropic vorticity equation (BVE) as a first model of the Earth's atmosphere in spectral space is studied. It is shown that explicit filtering increases the accuracy of the results over implicit filtering, particularly where the location of coherent structures is concerned. / Ph. D.

We consider edge-colorings and flows problems in Graph Theory that are hard to solve for Class 2 graphs. Most of them are strongly related to some outstanding open conjectures, such as the Cycle Double Cover Conjecture, the Berge-Fulkerson Conjecture, the Petersen Coloring Conjecture and the Tutte's 5-flow Conjecture. We obtain some new restrictions on the structure of a possible minimum counterexample to the former two conjectures. We prove that the Petersen graph is, in a specific sense, the only graph that could appear in the Petersen Coloring Conjecture, and we provide evidence that led to propose an analogous of the Tutte's 5-flow conjecture in higher dimensions. We prove a characterization result and a sufficient condition for general graphs in relation to another edge-coloring problem, which is the determination of the palette index of a graph.

The analysis of turbulent flows provides a unique scientific challenge whose solution remains central to unraveling the fundamental nature of all fluid dynamics. Measuring and predicting turbulent flows becomes even more difficult when considering a two-phase flow, which is a commonly encountered engineering problem across many disciplines. One such example, the ingestion of foreign debris into a gas turbine engine, provided the impetus for this study. Despite more than 40 years of research, operation with a particle-laden inlet flow remains a significant problem for modern turbomachines. The purpose, therefore, is to develop experimental methods for investigating multi-phase flows relevant to the cooling of gas turbine components. Initially, several generic components representing turbine cooling designs were evaluated with a particle-laden flow using a special high temperature test facility. The results of this investigation revealed that blockage was highly sensitive to the carrier flowfield as defined by the cooling geometry. A second group of experiments were conducted in one commonly used cooling design using a Time Resolved Digital Particle Image Velocimetry (TRDPIV) system that directly investigated both the carrier flowfield and particle trajectories. Traditional PIV processing algorithms, however, were unable to resolve the particle motions of the two-phase flow with sufficient fidelity. To address this issue, a new Particle Tracking Velocimetry (PTV) algorithm was developed and validated for both single-phase and two-phase flows. The newly developed PTV algorithm was shown to outperform other published algorithms as well as possessing a unique ability to handle particle laden two-phase flows. Overall, this work demonstrates several experimental methods that are well suited for the investigation of wall-bounded turbulent two-phase flows, with a special emphasis on a turbine cooling method. The studies contained herein provide valuable information regarding the previously unknown fluid and particle dynamics within the turbine cooling system. / Ph. D.

No / The ability to provide support to a group of designers, analysts and other users who are collaborating on an evolving design requires the dual capabilities of managing options for an individual designer while at the same time managing the dependencies between different sets of designer's options. For example, if designer A is creating a design for a helicopters hydraulics system and this is dependent on electrical power (EP) from a sub-system from designer B then how can the workflows, decisions and options of the two designers be managed so that each can understand the implications of their own design decisions and more importantly the implications and design decisions they force on others? The proposed CAPS system employs two dependency reasoning engines: one handles quantitative values and other qualitative ones. The quantitative engine can identify that a motor with an output of 3000 rpm allows a generator to output 100 V or that a hydraulic pump is dependent on the 240v output of the motor. Alternatively, the qualitative engine could rule out several motors options if the overall design state that the weight of a helicopter's transmission needs to be comparable to that of the engine or the positioning of a sensor makes it susceptible to an EM process that could affect its function. A mapping capability is provided allowing analysis to be passed between the two engines. Three different types of dependency-based quantitative engine designs have been developed and evaluated. The first quantitative engine design focuses on modeling components at their output level and propagating level values from component to component, component to sub-system, etc. The second quantitative engine design focuses on modeling components at the node level so as to identify key components, sub-systems, etc. in terms of their overall dependency to the design. The third engine employs a hybrid of the previous two approaches and was identified through feedback from designers. These engines are designed to be complimentary with the node-based and hybrid approaches being used to identify the key capabilities and dependencies of the design. The output-based approach is then used to explore in greater detail the outputs and dependencies of the components and sub-systems identified as key via the node/hybrid-based approach. The proposed CAPS architecture has been initially evaluated against a large collaborative design task involving the design of a helicopter's electrical, hydraulic, structural and mechanical systems.

Natural ventilation is an effective method to save energy required to condition buildings and to improve indoor air quality. Computational fluid dynamics (CFD) was used to model single-sided buoyancy-driven natural ventilation in a single room with a heater and door. The velocity and temperature profiles at the doorway agreed fairly well with published literature that includes Mahajan's experimental [2] and Schaelin et al's numerical studies [1]. The 2D and 3D models predicted the neutral level with a difference of 5.6 % and 0.08 % compared to the experimental results, respectively. Using solutions at the doorway, heat transfer rates were calculated. More realistic situations were studied considering conduction, various ambient conditions, wind speeds, and additional heat sources and furniture in the room. The heat loss through the wall was modeled and the airflow and temperature within the room showed no significant changes despite modeling conduction through the walls. Various ambient temperatures and wind speeds were tested, and the neutral level height and total heat transfer rate through the doorway increased with decreasing ambient temperatures. However, the neutral level did not significantly change as wind speeds varied. Total heat transfer rate at the doorway became positive, that is heat transferred into the room, with wind speed. Lastly, the effect of additional heat sources (mini-refrigerator, monitor and computer) and furniture (bookshelf, desk, chair and box) on airflow and heat transfer in the room was analyzed by comparing with a simple case of a room with a heater. Large velocities and high temperatures were predicted in the vicinity of the heat sources. However, the spatially averaged velocity and temperature did not change significantly despite additional heat sources. The room with furniture was modeled at lower ambient temperature, where the spatially averaged velocities were larger and temperatures were lower than the simple case. The room heated up and reached its thermal comfort level, but the velocities exceeded the maximum acceptable level set by ASHRAE guidelines [8]. Wind was considered simultaneously with the lower temperature, and the room was cooled faster with wind. However, the room was never able to achieve the comfortable level both in velocity and temperature. / Master of Science

Yes / Quantification of stocks and flows of construction materials is a key first stage in assessing the potential for creating higher value at end-of-life decisions compared to destructive demolition. Steel and concrete are amongst the most widely used construction materials primarily in structural components. Such components are highly variable in design, type, and dimensions. In the absence of urban-scale digitised models of structural components or building plans, accurate assessment relies on either onsite inspection or modelling by material intensity (MI) co-efficient which can vary by up to a factor of 100. In this study, we extend previous stock modelling approaches through the development of a method that relies on building archetypes and produces MI coefficients of steel and concrete that are representative of frame types, temporally explicit and disaggregated at product level. This is compared to the common existent method of calculating MI to demonstrate the capabilities of the proposed method. Coupled with a spatiotemporal model of urban buildings, the developed MI of both methods are applied to a case study in the UK. The total in-use stock of steel and concrete within multi-storey buildings is estimated at 81,000 tonnes and 655,000 m3 respectively. The stocks of steel and concrete are disaggregated based on their functions as products, for instance steel beams are distinguished from reinforcement steel. Subsequently, the embodied carbon of the in-use stock is calculated as 350 kt CO2eq. The results show the proposed method enables a more granular assessment of the embodied carbon of the structural material quantities. / This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) research grant ‘REBUILD - REgenerative BUILDings and products for a circular economy’ [Grant reference: EP/ P008917/1]

We provide geometric inequalities on $R^n$ and on general manifolds with nonnegative Ricci curvature by employing suitable monotone quantities along the flow of capacitary and $p$-capacitary potentials, as well as through related boundary value problems. Among the main achievements, we cite [(i)] a Willmore-type inequality on manifolds with nonnegative Ricci curvature leading in turn to the sharp Isoperimetric Inequality on $3$-manifolds with nonnegative Ricci curvature ; [(ii)] enhanced Kasue/Croke-Kleiner splitting theorems ; [(iii)] a generalised Minkowski-type inequality in $R^n$ holding with no assumptions on the boundary of the domain considered except for smoothness ; [(iv)] a complete discussion of maximal volume solutions to the least area problem with obstacle on Riemannian manifolds and its relation with the variational $p$-capacity.

Yes / A classification of coating flows is presented to facilitate a fundamental approach to their study. Four categories are observed: free, metered, transfer and gravure coating flows. They are all limited by free surface(s) which make their analysis difficult. Various analytical approaches have been used and these are briefly reviewed in this paper.

Bakgrund: Inom vården hanteras dagligen stora mängder material och det är av stor vikt att rätt material är på rätt plats, i rätt tid, i rätt mängd och med rätt kvalitet för att en så god vård som möjligt ska kunna erbjudas. För att säkerställa effektiva och välfungerande gods- och informationsflöden med hög servicenivå inom vården, krävs det förståelse för hur flödena fungerar, hur dessa är relaterade till varandra samt hur de samverkar. Det är en stor fördel för en organisation att kartlägga sina flöden då man genom en kartläggning kan identifiera kvalitetsbrister samt orsakerna till dessa och därefter vidta förbättringsåtgärder som resulterar i kvalitetsökningar. Syfte: Detta examensarbete avser att göra en nulägesbeskrivning med hjälp av flödekartläggningar av regionservice godsflöde och informationsflöde av förbrukningsmaterial. Syftet är att identifiera de nuvarande kvalitetsbristerna och orsakerna till dessa samt föreslå åtgärder som ska leda till förbättringar. Metod: Denna fallstudie har utgått från en kvalitativ undersökningsdesign där data har samlats in genom ostrukturerade intervjuer, semistrukturerade intervjuer samt deltagande observationer. För att möjliggöra identifieringar av kvalitetsbrister och de bakomliggande orsakerna till dessa upprättades flödeskartläggningar respektive orsak-verkandiagram som har legat till grund för förbättringsåtgärderna. Slutsatser: I studien framgår det att majoriteten av kvalitetsbristerna som uppstår i flödet av förbrukningsmaterial beror på att det saknas ett aktivt informationsutbyte mellan aktörerna, att rätt förutsättningar och utrustningar för spårning av godset inte finns tillgängligt samt att kvalitetskontroller inte genomförs. Utifrån dessa bakomliggande orsaker har tre åtgärder som tillsammans utgör grunden till ett bra logistikflöde och skapar förutsättningar för mer3 (106)effektiva och välfungerande gods- och informationsflöden föreslagits. För att regionservice ska kunna ha kontroll över flödet av förbrukningsmaterial och erhålla en högre kvalitet krävs det att de implementerar ett godsspårningssystem som kommer kunna säkerställa denna kvalitet genom att felen som uppstår i flödet snabbt kan spåras och åtgärdas. Godsspårningssystemet bör sedan kompletteras av ett informationssystem som skapar förutsättningar för en god kommunikation och informationstillgänglighet som på så sätt kan effektivisera informationsflödet och stärka samarbetet mellan de involverade aktörerna. Genom att kvalitetskontroller genomförs regelbundet i hela flödet kan även fel och brister upptäckas och minimeras. / Background: A large amounts of material is handled on a daily basis in health care and it is of great importance that the right material is at the right place at the right time, in the right quantity and the right quality in order to be able to offer as good care as possible. In order to ensure efficient and functional flows of goods and flows of information with a high level of service, it requires an understanding of how the flows operate, how they are related to each other and how they interact. It is beneficial for an organization to map their flows since it can help identify quality deficiencies and their causes and thereafter take improvement measures that increases the quality. Purpose: This thesis intends to describe the present situation through a flow mapping of the flow of materials of consumption in Regionservice. The aim is to identify existing quality deficiencies and their causes to thereafter be able to recommend measures that will result in improvements. Method: This case study is based on a qualitative research design where data were collected through unstructured interviews, semi-structured interviews and participating observations. In order to enable identifications of quality deficiencies and the underlying causes of these, flow mappings and cause-effect diagrams were established and have been the basis of the improvement measures. Conclusions: This study indicates that the majority of the quality defeiciencies that occur in the flow of materials of consumption is due to the lack of an active exchange of information between the actors, the right conditions and equipments for tracking the goods and that quality controls are not implemented. Based on these underlying causes there are three measures that have been suggested that together form the foundation for an optimal logistics 5 (106) and creates conditions for more efficient and functional flows of goods and information. In order for Regionservice to be able to control the flow of materials of consumption and obtain a higher quality, they are required to implement a tracking system that will ensure this quality since the deficincies that occur in the flow can be tracked and fixed. The tracking system should be complemented by an information system that creates oppurtunites for good communication and information accessibility which will enhance the cooperation between the actors involved. By conducting quality controls regularly throughout the flow, faults and deficiencies can be discovered and minimized.