Das Ameise Kolonie Optimization (ACO) ist eine Metaheuristik für Verfahren der kombinatorischen Optimierung, die auf dem modellhaften Verhalten von realen Ameisen bei der Futtersuche basiert[1]. Viele Probleme können durch ACO sehr effizient bearbeitet werden. Zum Beispiel Job-Shop[2,3], Flow-Shop[4], Minimum Cost Permutation[5], Maschinenbelegungsprobleme, Minimierung der Transportzeit bei räumlich weit auseinander liegenden Produktionsstätten(Single Machine Total Tardiness problem)[6] usw. Marco Dorigo und Thomas Stützle[7] haben über das Problem des Handlungsreisenden (TSP) viele hilfreiche Formeln vorgestellt, um ein besseres Ergebnis zu bekommen. In dieser Masterarbeit werden durch Formeln einfach getestet bzw. ermittelt, wie gut das Ergebnis aussieht. Anschließend wird ein akuelles Thema GSP (The Gas Station Problem) vorgestellt. Samir Khuller, Azarakhsh Malekain und Julian Mestre[8] haben in ihrer Arbeit einige konkrete Probleme diskutiert. Dort haben sie auf theoretischer Ebene die günstigere Tour ermittelt. Zum Beispiel gibt es einige Tankstellen mit unterschiedlichen Benzin-Preisen. Ein Auto fährt von einer Startstadt zu einer Zielstadt und der Fahrer entscheidet, wieviel und wo das Benzin getankt wird. In dieser Masterarbeit werden zudem noch kompliziertere Annahmen beachten. Es kann entweder mit Strom oder Benzin auf den Straßen fahren. Zusätzlich kann das Auto noch unterwegs von Strom auf Benzin oder umgekehrt umschalten. Es kann beispielsweise das erste Drittel des Wegs mit Strom und den Rest mit Benzin fahren. Das Ziel ist es dabei, einen kürzeren Weg dazu so billig wie möglich zu finden. Wir versuchen, dieses Problem durch ACO durchlaufen zu lassen. Im allgeimeinen Fall findet jede Ameise eine günstige Tour d.h. die Ameise stirbt niemals unterwegs. Aber bei diesem Problem darf die Ameise irgendwo sterben, zum Beispiel stirbt sie in einer Stadt, weil sie nicht genug Benzin oder Strom im Tank hat. In dem Kapitel bzgl. der Zukunft der Arbeit stellen wir noch andere Algorithmen bzw. ACO kombiniert mit PSO vor. Der Unterschied zwischen diesen zwei Methoden ist der, dass bei ACO das Auto von Stadt i zu Stadt j immer auf einer geraden Linie und bei ACO mit PSO in einer Kurve fährt. Falls die Ameise einen Berg oder Fluß passiert, leitet sie den Weg um. Das Ameise Kolonie Optimization (ACO) ist ein sehr mächtiger Algorithmus. Es gibt viele Varianten von ACO, die sich mit TSP beschäftigen. Es gibt keine Ideallösung, sondern es geht darum, immer eine bessere Lösung zu finden. Die konkrete Arbeitsweise wird im folgenden Kapitel mit einigen einfachen Beispielen erklärt.

<div>Experiments were performed on a sharp-nosed 7° half-angle cone at a 6° angle of attack in the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT) to study the stationary crossflow instability and its receptivity to small surface roughness. Heat transfer measurements were obtained using temperature sensitive paint (TSP) and Schmidt Boelter (SB) heat transfer gauges. Great care was taken to obtain repeatable, quantitative measurements from TSP.</div><div></div><div>Consecutive runs were performed at a 0° angle of attack, and the heat transfer measured by the SB was found to drop as the initial model temperature increased, while other initial conditions such as stagnation pressure were held constant. This agreed with calculations done using a similarity solution. It was found that repeatable measurements at a 6° angle of attack could be made if the initial model temperature was controlled and the patch location that was used to calibrate the TSP was picked in a reasonable and consistent manner.</div><div></div><div>The Rod Insertion Method (RIM) roughness, which was used to excite the stationary crossflow instability, was found to be responsible for the appearance of the streaks that were analyzed. The signal-to-noise ratio in the TSP was too low to properly measure the streaks directly downstream of the roughness insert. The heat transfer along the streak experienced linear growth, peaked, and then slightly decayed. It is possible this peak was saturation. The general trend was that the growth of the streaks moved farther upstream as the roughness element height increased, which agreed with past computations and low speed experiments. The growth of the streak also moved farther upstream as the freestream Reynolds number increased. The amplitude of the streaks was calculated by non-dimensionalizing the heat transfer using the laminar theoretical mean-flow solution for a 7° half-angle cone at a 6° angle of attack. The relationship between the amplitude and the non-dimensional roughness height was approximately linear in the growth region of the streaks.</div>

Esta Tesis Doctoral demuestra que la realidad de las redes de transporte que caracterizan los problemas de rutas reales de las empresas, es muy compleja y asimétrica; y esto queda reflejado en las matrices de distancias (tiempos o costes) entre pares de localizaciones que son la base de todo problema de rutas. En esta investigación, se cuantifica la medida en la que el grado de asimetría de las matrices de distancias depende de factores como el territorio y la localización de los clientes; y se subraya la importancia de la obtención de las matrices de distancias reales asimétricas y la barrera de entrada que ello supone. El objetivo principal de esta Tesis Doctoral es cuantificar en qué medida la asimetría tiene un efecto sobre la eficiencia y eficacia de las principales heurísticas y meta-heurísticas reconocidas en la resolución de dos casos fundamentales de los problemas de rutas: el TSP y el CVRP. Adicionalmente, también se estudia el impacto de otros factores (el territorio, la localización, el número de clientes, la demanda y la capacidad máxima) en los resultados (tiempo computacional y bondad de la solución). Mediante la realización de multitud de experimentos computacionales y análisis estadísticos de los resultados (ANOVA entre otros), se demuestra que todas las técnicas estudiadas se ven afectadas en mayor o menor medida por la asimetría y otros factores; y que las soluciones a los problemas simétricos poco o nada tienen que ver con las soluciones en el contexto asimétrico (ni cuantitativa, ni cualitativamente). Con todo ello, se puede inferir que la asimetría tiene un efecto muy importante sobre todos los problemas de rutas de vehículos, y por tanto debe ser considerada como un factor clave de cualquier desarrollo e investigación de aplicación en el contexto real de las empresas. / Rodríguez Villalobos, A. (2012). Estudio del efecto de la asimetría en problemas de rutas de vehículos [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/15184 / Palancia

Fiber deployment is becoming popular and is seen as a way to increase a community’s attractiveness to new inhabitants and companies. A new Open Access network is emerging, leading to a more horizontal network architecture. Combining this architecture with IMS enables developers to easily develop new and attractive services. To facilitate the development of new IMS services there needs to be an easy to use development environment and a reliable hardware/software platform upon which to deploy them. This thesis project will explore the design, development, and evaluation of new IMS applications targeted at municipal networks as well as the service platforms they are deployed on. The thesis will also examined what role IMS plays in Municipalities and why they may need a tailored IMS solution. During the thesis a reference network for Municipalities was put together and tested. Different service platforms were tested and evaluated. / Fiberutbyggnad har blivit mycket populärt och ses som ett sätt att öka en stads attraktivitet för nya invånare och företag. Ett nytt öppen nät håller på att växa fram, detta leder till en mer horisontell nätverksarkitektur. Kombinera denna arkitektur med IMS så kan utvecklare lättare utveckla nya och attraktiva tjänster. För att underlätta utvecklingen av nya IMS-tjänster måste det finnas ett lättanvänd utvecklingsmiljö och en pålitlig hårdvaru/mjukvaru plattform att installera dem på. Detta examensarbete kommer att undersöka design, utveckling och utvärdering av nya IMSlösningar riktade till standsnät samt de tjänsteplattformar de används på. Rapporten kommer även granska vilken roll IMS spelar i stadsnät och varför de kan behöva en skräddarsydd IMS-lösning. Under examensarbetet byggdes och testades ett referensnätverk. Olika tjänsteplatformar testades och utvärderades.

Experimental tests on a transonic annular rig are time-consuming and expensive, so it is desirable to use experimental results to validate a computational model which can then be used to extract much more information. The purpose of this work is to create a numerical model that can be used to simulate many different scenarios and then to apply these results to experimental data.; In the modern world, gas turbines are widely used in aircraft propulsion and electricity generation. These applications represent a massive use of energy worldwide, so even a very small increase in efficiency would have a significant beneficial economic and environmental impact. There are many ways to optimize the operation of a gas turbine, but a fundamental approach is to increase the turbine inlet temperature to increase the basic thermodynamic efficiency of the turbine. However, these temperatures are already well above the melting temperature of the components. A primary cooling methodology, called film cooling, creates a blanket of cool air over the surface and is an effective way to help protect these components from the hot mainstream gasses. This paper focuses on the effect of the film holes upstream of the first row of blades in the turbine because this is the section that experiences the highest thermal stresses. Many factors can determine the effectiveness of the film cooling, so a complete understanding can lead to effective results with the minimum flow rate of coolant air. Many studies have been published on the subject of film cooling, but because of the difficulty and expense of simulating turbine realistic conditions, many authors introduce vast simplifications such as low speed conditions or linear cascades. These simplifications do not adequately represent the behavior of a turbine and therefore their results are of limited use. This study attempts to eliminate many of those simplifications. The test rig used in this research is based on the NASA-GE E³ design, which stands for Energy Efficient Engine. It was introduced into the public domain to provide an advanced platform from which open-literature research could be performed.

Film cooling is a technique whereby air from the compressor stage of a gas turbine engine is diverted for cooling purposes to parts, such as the turbine stage, that operate at very high temperatures. Cooling arrangements include impingement jets, finned, ribbed and turbulated channels, and rows of film cooling holes, all of which over the years have become progressively more complex. This costly, but necessary complexity is a result of the industry's push to run engines at increasingly higher turbine inlet temperatures. Higher temperatures mean higher efficiency, but they also mean that the turbine first stage operates hundreds of degrees Kelvin above the melting point of the metal core of the vanes and blades. Existing cooling technology and materials make it possible to protect these parts and allow them to function for extended periods of time--but this comes at a price: the compressed air that is used for cooling represents a considerable penalty in overall turbine efficiency. The aim of current cooling research is threefold: to improve the protection of components from extreme fluxes in order to extend the life of the parts; to increase the inlet turbine operating temperature; and to reduce the amount of air that is diverted from the compressor for cooling. Current film cooling schemes consist of forcing air through carefully machined holes on a part and ejecting it at an angle with the intent of cooling that part by blanketing the surface downstream of the point of ejection. The last major development in the field has been the use of expanded hole exits, which reduce coolant momentum and allow for greater surface coverage. Researchers and designers are continuously looking for novel geometries and arrangements that would increase the level of protection or maintain it while using less coolant. It was found that the performance of fan-shaped holes inside trenches is actually diminished by the presence of the trench. It is obvious, since the fan diffuses the flow, reducing the momentum of the coolant; the addition of the trench further slows the flow down. This, in turn, leads to the quicker ingestion of the main flow by the jets resulting in lower effectiveness. The next part of the study consisted of systematically increasing the depth of the trench for the fan-shaped holes. The purpose of this was to quantify the effect of the trench on the film cooling effectiveness. It was found that the presence of the trench significantly reduces the film effectiveness, especially for the deeper cases. At the higher blowing ratios, the overall performance of the fans collapses to the same value signifying insensitivity to the blowing ratio. A recent study suggests that having a compound angle could reduce the protective effect of the film due to the elevated interaction between the non-co-flowing coolant jet and the mainstream. Although it has been suggested that a non-symmetric lateral diffusion could mitigate the ill effects of having a compound angle, little has been understood on the effect this non-symmetry has on film cooling effectiveness. The last part of this study investigates the effect of non-symmetric lateral diffusion on film cooling effectiveness by systematically varying one side of a fan-shaped hole. For this part of the study, one of the lateral angles of diffusion of a fan-shaped hole was changed from 5° to 13°, while the other side was kept at 7°. It was found that a lower angle of diffusion hurts performance, while a larger diffusion angle improves it. However, the more significant result was that the jet seemed to be slightly turning. This dissertation investigates such novel methods which one day may include combinations of cylindrical and fan-shaped holes embedded inside trenches, conical holes, or even rows of asymmetric fan-shaped holes. The review of current literature reveals that very few investigations have been done on film cooling effectiveness for uniformly diffusing conical holes. They have been treated as a sort of side novelty since industrial partners often say they are hard to manufacture. To extend our understanding of effectiveness of conical holes, the present study investigates the effect of increasing diffusion angle, as well as the effect of adding a cylindrical entrance length to a conical hole. The measurements were made in the form of film cooling effectiveness and the technique used was temperature sensitive paint. Eight different conical geometries were tested in the form of coupons with rows of holes. The geometry of the holes changed from pure cylindrical holes, a 0° cylindrical baseline, to an 8° pure cone. The coupons were tested in a closed loop wind tunnel at blowing ratios varying from 0.5 to 1.5, and the coolant employed was nitrogen gas. Results indicate that the larger conical holes do, in fact offer appropriate protection and that the holes with the higher expansion angles perform similar to fan-shaped baseline holes, even at the higher blower ratios. The study was also extended to two other plates in which the conical hole was preceded by a cylindrical entry length. The performance of the conical holes improves as a result of the entry length and this is seen at the higher blowing ratios in the form of a delay in the onset of jet detachment. The results of this study show that conical expanding holes are a viable geometry and that their manufacturing can be made easier with a cylindrical entry length, at the same time improving the performance of these holes. This suggests that the jets actually have two regions: one region with reduced momentum, ideal for protecting a large area downstream of the point of injection; and another region with more integrity which could withstand more aggressive main flow conditions. A further study should be conducted for this geometry at compound angles with the main flow to test this theory. The studies conducted show that the temperature sensitive paint technique can be used to study the performance of film cooling holes for various geometries. The studies also show the film cooling performance of novel geometries and explain why, in some cases, such new arrangements are desirable, and in others, how they can hurt performance. The studies also point in the direction of further investigations in order to advance cooling technology to more effective applications and reduced coolant consumption, the main goal of applied turbine cooling research. Trench cooling consists of having film cooling holes embedded inside a gap, commonly called a trench. The walls of this gap are commonly vertical with respect to the direction of the main flow and are directly in the path of the coolant. The coolant hits the downstream trench wall which forces it to spread laterally, resulting in more even film coverage downstream than that of regular holes flush with the surface. Recent literature has focused on the effect that trenching has on cylindrical cooling holes only. While the results indicate that trenches are an exciting, promising new geometry derived from the refurbishing process of thermal barrier ceramic coatings, not all the parameters affecting film cooling have been investigated relating to trenched holes. For example, nothing has been said about how far apart holes inside the trench will need to be placed for them to stop interacting. Nothing has been said about shaped holes inside a trench, either. This dissertation explores the extent to which trenching is useful by expanding the PI/D from 4 to 12 for rows of round and fan holes. In addition the effect that trenching has on fan-shaped holes is studied by systematically increasing the trench depth. Values of local, laterally-averaged and spatially-averaged film cooling effectiveness are reported. It is found that placing the cylinders inside the trench and doubling the distance between the holes provides better performance than the cylindrical, non-trenched baseline, especially at the higher blowing ratios, M > 1.0. At these higher coolant flow rates, the regular cylindrical jets show detachment, while those in the trench do not. They, in fact perform very well. The importance of this finding implies that the number of holes, and coolant, can be cut in half while still improving performance over regular holes. The trenched cylindrical holes did not, however, perform like the fan shaped holes.

Advanced cooling techniques are required to increase the Brayton cycle temperature ratio necessary for the increase of the overall cycle's efficiency. Current turbine components are cooled with an array of internal cooling channels in the midchord section of the blade, pin fin arrays at the trailing edge and impingement channels in the leading edge. Impingement channels provide the designer with high convective coefficients on the target surface. Increasing the heat transfer coefficient of these channels has been a subject of research for the past 20 years. In the current study, a triple row impingement channel is studied with a jet to target spacing of 6, 8 and 10. The effects of sidewalls are also analyzed. Temperature sensitive paint alongside thin foil heaters are used to obtain heat transfer distributions throughout the target and side walls of the three different channels. Thermal performances were also calculated for the two largest channels. It was found that the side walls provide a significant amount of cooling especially when the channels are mounted side by side so that their sidewalls behave as fins. Similar to literature it was found that an increase in Z/D decreases heat transfer coefficient and provides a more uniform profile. It was also found that the Z/D = 6 and 8 target wall heat transfer profiles are very similar, hinting to the fact that successful potential core impingement may have occurred at height of eight diameters. A Computational Fluid Dynamics, or CFD, study was also performed to provide better insight into the flow field that creates such characteristic heat transfer profiles. The Realizable k-µ solution with enhanced wall functions gave surface heat transfer coefficients 30% off from the experimental data.

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