The quenching of undesired flames by cold surfaces has been investigated for more than a century. The current quenching theory can predict simple configurations, this is not the case for real environments such as fuel management systems. Flames are sensitive to numerous parameters, such as fuel, mixture fraction, pressure, temperature, flow properties, acoustics, radiation, and surface interactions. The effects of some of these parameters are very well documented but there is a lack of information regarding the effects of acoustics and flow. This dissertation work will focus on improving the understanding of flow effect on the quenching of premixed gaseous flames. First, the effect of apparent velocity on flame quenching was investigated for different fuels and equivalence ratios. An experimental facility is designed such that the apparent flame velocity at which the flame enters and propagates through the channel can be varied without changing the initial mixture condition. High-speed (15,000 frames per second (FPS)) Schlieren and dynamic pressure measurement were used to measure the apparent flame velocity and to assess the flame quenching, respectively. This study showed that the high-speed laminar flames are harder to quench compared to self-propagating and turbulent flames. A similar trend was obtained for all the conditions investigated, lean and stoichiometric methane-air, lean propane-air, and lean ethylene-air mixtures. Further investigation was carried out to understand the quenching of high-speed laminar flames. The flame propagation through the channel was investigated using Hydroxyl (OH) planar laser induced fluorescence (PLIF). This study showed that the OH intensity fell below the detection threshold in the later part of the channel when quenching is observed. Then, the influence of heat transfer was investigated using spatial and temporal evolution of the temperature in the quenching channel. A high-speed (10 kHz) filtered Rayleigh scattering (FRS) technique was used to measure the one-dimensional time-resolved temperature profile. Three different channel heights (H = 1.3, 1.5, 2.0 mm) were investigated. Based on the evolution of the temperature profile in the quenching channel, a new parameter was identified and the importance of its evolution on the flame quenching was discussed.

In the Spring of 1998, the Virtual Corporation at Virginia Tech demonstrated the ability of Linear Switched Reluctance Propulsion (LSRP) to propel a vehicle on a track using only the interaction of a passive magnetic component carried on the vehicle with electromagnets built into the track. The Mark II project was a follow-on effort to complete a thorough design analysis of a second iteration vehicle which features the complete functionality of the original vehicle, with the addition of the ability to enter and exit the LSRP track system using remote control and an electric motor. The new vehicle also features certain design improvements in communications and structural rigidity. This paper elaborates on the process of design and analysis of the vehicle and ramp systems, including detail design drawings, finite element analysis of the vehicle chassis, powertrain subsystem analysis, and detailed analysis of the ramp surface contour design. / Master of Engineering

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第22797号 / エネ博第411号 / 新制||エネ||79(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授 片平 正人, 准教授 小瀧 努, 教授 森井 孝 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22894号 / 工博第4791号 / 新制||工||1749(附属図書館) / 京都大学大学院工学研究科原子核工学専攻 / (主査)教授 横峯 健彦, 教授 佐々木 隆之, 講師 河原 全作 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Mätning av fotbollsspelares fysiska kapacitet har blivit allt vanligare och viktigare för att optimera spelarnas återhämtning och kapacitet, speciellt i slutet av matcherna i den så kallade kritiska fasen av en match. I dagens elitfotboll mäts spelarnas fysiska prestation med hjälp av global positioning systems (GPS). GPSerna har utvecklats enormt de senaste åren och kan i dag ta fram hundratals parametrar för tränare och spelare att analysera. På lägre nivåer finns inte samma möjligthet att använda GPSer, ofta på grund av eknomiska skäl, och fystester av olika sorter, bland annat agility T-test, används ofta för att mäta spelarnas fysiska kapacitet. Syftet med denna studie var att undersöka om ett enkelt fystest, ett modifierat agility T-test (T3-test) korrelerar med fysiska matchparametrar inom fotbollen. Totalt i studien deltog 8 stycken manliga elitfotbollsspelare från ett svenskt seniorfotbollslag. Deltagarna bar STATSport Apex GPS-system en hel säsong, av vilket fem parametrars (total distans, höghastighetslöpningar, sprints, accelerationer och decelerationer) procentuella värde sista 15 minuterna i ordinarie matchtid (minut 75-90) i förhållande till hela matchens genomsnitt mättes och jämfördes sedan med deras prestation på T3-test. T3-testet utfördes i säsongens sista kvartal. Korrelationen analyerades genom Spearman’s rho korrelationsanalys. Resultatet från denna studie visade inga signifikanta korrelationer mellan de nämnda fysiska matchparametrarna och prestationen på T3-testet. Då studiens statistiska power var lågt på grund av otillräckligtdeltagarantalet, bör inga säkra slutsatser dras utifrån studiens resultat. Mer forskning av T3-test eller liknanden enkla fystester som prediktorer av fysisk matchkapacitet inom fotbollen krävs innan eventuell tillämpning i elitfotbollen bör säkerställas eller avvisas. / Measuring the physical capacity of football players has become more important in optimizing players' recovery and capacity, especially at the end of matches in the so-called critical phase of a match. In today's elite football, players' physical performance is measured using global positioning systems (GPS). The GPSs have developed enormously in recent years and can today produce hundreds of parameters for coaches and players to analyze. At lower levels, there is not the same possibility to use GPSs, often due to economic reasons, and fitness tests of various kinds, including agility T-test, are often used to measure players' physical capacity. The purpose of this study was to investigate whether a simple fitness test, a modified agility T-test (T3-test) correlates with physical match parameters in football. A total of 8 male elite football players from a Swedish senior football team participated in the study. Participants wore the STATSport Apex GPS system for an entire season, of which five parameters (total distance, high-speed runs, sprints, accelerations and decelerations) percentage value in the last 15 minutes of regular match time (minutes 75-90) in relation to the entire match average were measured and compared with their performance on T3-test. The T3-test was performed in the last quarter of the season. The correlation was analyzed by Spearman's rho correlation analysis. The results from this study showed no significant correlations between the mentioned physical match parameters and the performance on the T3-test. As the statistical power of the study was low, due to insufficient number of participants, no definite conclusions should be drawn based on the results of the study.

When the light passes through optical elements it can cause deformation of wavefront light due to the damage of materials and optical aberrations. The deformation leads to unprecise imaging and deformation of an image. The diploma work mentions wavefront sensing techniques which are important for determination inappropriate errors of optical elements and the specification of their properties. The purpose of the master's thesis is to suggest and investigate wavefront sensing methods after the light passes through the optical element while using the digital micromirror device. The work deals with the topic of wavefront aberrations and geometric optical defects of optical elements. Different kinds of commercial products determined for wavefront sensing are described too.

<div>A common assumption often made of dynamic compressors is that they are considered adiabatic, due to the fast-moving flow passing through the turbomachine and the small amount of any heat transfer relative to the large amount of work transferred to/from the flow. This research investigation combined the use of experimental measurements and computational simulations to take a deeper look into the implications that arise from applying this adiabatic assumption or neglecting heat transfer within a high-speed, multi-stage, axial compressor.</div><div><br></div><div>Preliminary testing of the Purdue 3-Stage (P3S) Axial Compressor Research Facility indicated the presence of heat transfer through stagnation temperature rises across stationary blade rows and higher than expected temperatures on the outside of the aluminum compressor casing, particularly in the front stages. Further experiments performed on the PAX200 compressor in the P3S facility involved a combination of surface temperatures, heat fluxes, and flow stagnation temperatures within the shrouded stator cavities and flowpath. These measurements confirmed that heat transfer was present throughout the stationary components (stators and casing) of the compressor and showed that they could noticeably affect the thermal flow properties within the compressor.</div><div><br></div><div>The influence of the heat transfer through these components was further explored through computational simulations, which showed the importance of incorporating conjugate heat transfer into the model and applying the correct thermal boundary conditions on the outside of the casing. Additionally, the effects on the spanwise temperature of the flow through increased spanwise mixing, convection, and different geometric and material properties of the casing were also explored. Overall, this investigation seeks to establish a correct thermal boundary condition and approach for validation of computational model. It also aims to reconcile the differences between computational models and experimental data by quantifying the impact that heat transfer has on isentropic efficiency for diabatic compressors.</div>

Frost formation is of a major research interest as it can affect many industrial processes. Frost appears as a thin deposit of ice crystals when the temperature of the surface is below the freezing point of the liquid. The objective of this research is to study icing with hope to propose new anti-icing and deicing methods. In the beginning of the research, cracking of the ice layer was observed when a deionized water droplet impacts a ?50 oC cooled sphere surface that is in contact with dry ice. To further investigate the cracks occurrence, multiple experiments were conducted. It was observed that the sphere surface temperature and droplet temperature (ranges from 10-80 oC) have no effect on the crack formation. On the other hand, it was observed that formation of a thin layer of frost on the sphere before the drop impact leads the lateral cracking of the ice. Thus, attempts to reproduce the cracks on clean super cold sphere surfaces were made using scratched and sandblasted spheres as well as superhydrophobized and polymer particle coated spheres. Furthermore, innovative methods were tried to initiate the cracks by placing epoxy glue bumps and ice-islands coatings on the surface of the spheres. All of these attempts to reproduce the crack formation without the presence of frost, failed. Nonetheless, the adding of isolated frost on the sphere surfaces always leads to the crack formation. Generally, frost forms on the small spheres faster than it does on the bigger ones. Additionally, the cold water droplet produces thicker water and ice layer compared to a hot water droplet; and the smaller the sphere the larger its water and ice layer thicknesses.

The impact of a spherical object onto a surface of a liquid, solid or granular material, is a configuration which occurs in numerous industrial and natural phenomena. The resulting dynamics can produce complex outcomes and often occur on very short time-scales. Their study thereby requires high-speed video imaging, as is done herein. This three-part dissertation investigates widely disparate but kindred impact configurations, where the impacting object is a solid steel sphere, or a molten metal droplet. The substrate, on the other hand, is either granular material, a liquid, or solid ice. Therefore both fluid mechanics and thermodynamics play a key role in some of these dynamics. Part I, investigates the penetration depth of a steel sphere which impacts onto a granular bed containing a mixture of grains of two different sizes. The addition of smaller grains within a bed of larger grains can promote a “lubrication” effect and deeper penetration of the sphere. However, there needs to be enough mass fraction of the smaller grains so that they get lodged between the larger grains and are not simply like isolated rattlers inside the voids between the larger grains. This lubrication occurs even though the addition of the small grains increases the overall packing fraction of the bed. We compare the enhanced penetration for the mixtures to a simple interpolative model based on the results for monodispersed media of the constitutive sizes. The strongest lubrication is observed for large irregular shaped Ottawa sand grains, which are seeded with small spherical glass beads. Part II, tackles the topic of a molten metal drop impacting onto a pool of water. When the drop temperature is far above the boiling temperature of water, a continuous vapor layer can form at the interface between the metal and water, in what is called the Leidenfrost phenomenon. This vapor layer can become unstable forming what is called a vapor explosion, which can break up the molten metal drop. We study the details of these explosions and characterize the metal debris. We contrast the results for two different metals, i.e. tin and a special metal alloy called Field’s metal. For tin the drop solidifies and forms a porous foam-like solid, whereas the Field’s metal breaks up into a multitude of spherical beads, with a range of sizes as small as a few microns. We attribute this difference to the much lower melting point of the Field’s metal, which is only 60oC, compared to 230oC for the tin. This allows more fragmentation of the Field’s metal drop before it solidifies. When the temperature of the impacting metal is increased, high-speed imaging reveals a sequence of up to three vapor explosions, each of increasing intensity. We measure the acceleration of the vapor interface and compare the size-distribution of the microbeads to the fastest growing instability mode of the corresponding Rayleigh-Taylor instability. Part III, investigates the coefficient of restitution when a steel sphere impacts on an ice surface. As observed in earlier studies the restitution coefficient is largest for the smallest impact velocities, where the surface is not greatly fragmented. Our focus is on greatly heating the sphere up to 400oC to investigate how the thermal load affects the short term interaction of the sphere with the ice. We see a clear trend where hotter spheres rebound less than cold spheres. We also track the speed of ice-fragments ejected during the earliest stages of the impact.

The master's thesis solve the problem of setting new TCP variants for high-speed IP networks. The first goal was to describe in detail the behaviour of TCP and then analyse a problem of utilization the available bandwidth with standard TCP in high-speed network. Work consequently deals with selection and description the most perspective ones. Further the reader is familiarized with reasonable simulation tools of existing problems and their brief description. Main part of this thesis presents examination of performance of new TCP variants for high-speed network. During the examination the aspects on efficiency and fairness of competition flows on shared bottleneck are taken. The results are tabularly displayed plus compared with each other.