No description available.

No description available.

Detonation cycles are identified as an efficient alternative to the Brayton cycles used in power and propulsion applications. Rotating Detonation Engine (RDE) operating on a detonation cycle works by compressing the working fluid across a detonation wave, thereby reducing the number of compressor stages required in the thermodynamic cycle. Numerical analyses of RDEs are flexible in understanding the flow field within the RDE, however, three-dimensional analyses are expensive due to the differences in time-scale required to resolve the combustion process and flow-field. The alternate two-dimensional analyses are generally modeled with perfectly premixed fuel injection and do not capture the effects of improper mixing arising due to discrete injection of fuel and oxidizer into the chamber. To model realistic injection in a 2-D analysis, the current work uses an approach in which, a Probability Density Function (PDF) of the fuel mass fraction at the chamber inlet is extracted from a 3-D, cold-flow simulation and is used as an inlet boundary condition for fuel mass fraction in the 2-D analysis. The 2-D simulation requires only 0.4% of the CPU hours for one revolution of the detonation compared to an equivalent 3-D simulation. Using this method, a perfectly premixed RDE is comparing with a non-premixed case. The performance is found to vary between the two cases. The mean detonation velocities, time-averaged static pressure profiles are found to be similar between the two cases, while the local detonation velocities and peak pressure values vary in the non-premixed case due to local pockets fuel rich/lean mixtures. The mean detonation cell sizes are similar, but the distribution in the non-premixed case is closer due to stronger shock structures. An analytical method is used to check the effects of fuel-product stratification and heat loss from the RDE and these effects adversely affect the local detonation velocity. Overall, this method of modeling captures the complex physics in an RDE with the advantage of reduced computational cost and therefore can be used for design and diagnostic purposes. / Master of Science / The conventional Brayton cycle used in power and propulsion applications is highly optimized, at cycle and component levels. In pursuit of higher thermodynamic efficiency, detonation cycles are identified as an efficient alternative and gained increased attention in the scientific community. In a Rotating Detonation Engine (RDE), which is based on the detonation cycle, the compression of gases occurs across a shock wave. This method of achieving high compression ratios reduces the number of compressor stages required for operation. In an RDE (where combustion occurs between two coaxial cylinders), the fuel and oxidizer are injected axially into the combustion chamber where the detonation is initiated. The resultant detonation wave spins continuously in the azimuthal direction, consuming fresh fuel mixture. The combustion products expand and exhaust axially providing thrust/mechanical energy when coupled with a turbine. Numerical analyses of RDEs are flexible over experimental analysis, in terms of understanding the flow physics and the physical/chemical processes occurring within the engine. However, three-dimensional numerical analyses are computationally expansive, and therefore demanding an equivalent, efficient two-dimensional analysis. In most RDEs, fuel and oxidizer are injected from separate plenums into the chamber. This type of injection leads to inhomogeneity of the fuel-air mixture within the RDE which adversely affects the performance of the engine. The current study uses a novel method to effectively capture these physics in a 2-D numerical analysis. Furthermore, the performance of the combustor is compared between perfectly premixed injection and discrete, non-premixed injection. The method used in this work can be used for any injector design and is a powerful/efficient way to numerically analyze a Rotating Detonation Engine.

Det här projektet handlar om att utveckla en metod för real driving emission (RDE). RDE är ett komplement till Worldwide Light Duty Test Procedure (WLTP) som kommer att ersätta New European Driving Cycle (NEDC). Dessa cykler och metoder används för att mäta personbilars avgaser. Huvudanledningen till varför NEDC ska bytas ut är för att körcyklerna inte längre är realistiska och reflekterar inte hur en bil presterar egentligen. Detta har lett till att bilar har högre bränsleförbrukning och högre avgasutsläpp när dom körs i trafiken jämfört med resultaten från NEDC.Metoden utvecklades genom hänvisningar till den officiella WLTP rapporten. Tillsammans med Vehicle Emission gruppen från AVL fastställdes en komplett steg för steg metod.Utrustningen som användes förseddes av AVL och flera tester av varje steg av metoden genomfördes för att förfina metoden så mycket som möjligt. Bilen som användes var en SAAB 9-5 2.0l bensin.Resultaten visade att både bilen och testet inte mötte kriterierna för RDE och godkändes inte av programmet som användes för att utvärdera testet. Detta var delvis för att kriterierna för RDE är strikta och delvis för att ingen pre och post test genomfördes eftersom det tar mycket tid för att dom testerna ska bli godkända.I överlag ger WLTP och RDE potentiella bilköpare en bättre detaljerad sammanfattning av hur bra bilen presterar i trafiken jämfört med NEDC. / This project is about developing a method for real driving emission (RDE). RDE is a complement to Worldwide Light Duty Test Procedure (WLTP) which will replace the New European Driving Cycle (NEDC). These cycles and procedures are used for measuring emissions for light duty vehicles. The main reason why NEDC is being replaced is because the driving cycles does not reflect how vehicles are normally driven. This has resulted in vehicles having higher fuel consumption and emitting more poisonous gases when driven on actual roads compared to the results from the NEDC.The method was developed by referring to the laws of the official WLTP report written by EU. Together with the Vehicle Emissions team at AVL a complete step by step method was established.All the equipment and instruments were provided by AVL and several tests of each step of the method was made to perfect the method as much as possible. The vehicle that was used was a 2005 SAAB 9-5 2.0l petrol.The results displayed that the car and the test did not meet the criteria for RDE and was not passed by the evaluating software. This was partly because the driving criteria for RDE are strict and can be difficult to achieve and partly because no pre and post test was made since it can take several tries before those tests are passed.Overall, WLTP and RDE give buyers a more detailed and better conclusion of how a car performs on the road compared to NEDC.

The Remote Distractor Effect (RDE) is a robust phenomenon where a saccade to a lateralised target is delayed by the appearance of a distractor in the contralateral hemifield (Walker, Kentridge, & Findlay, 1995). The main aim of this thesis was to test whether the RDE generalises to response modalities other then the eyes. In Chapter 2, the RDE was tested on saccadic and simple manual keypress responses, and on a choice discrimination task requiring a covert shift of attention. The RDE was observed for saccades, but not simple manual responses, suggesting that spatially oriented responses may be necessary for the phenomenon. However, it was unclear whether distractor interference occurred in the covert task. Chapter 4 compared the effects of distractors between spatially equivalent tasks requiring saccadic and manual aiming responses respectively. Again, the RDE was observed for the eyes but not for the hands. This dissociation was also replicated in a more naturalistic task in which participants were free to move their eyes during manual aiming. In order to examine the time-course of distractor effects for the eyes and the hands, a third experiment investigated distractor effects across a wider range of target-distractor delays, finding no RDE for manual aiming responses at distractor delays of 0, 100, or 150 ms. The failure of the RDE to generalise to manual aiming suggests that target selection mechanisms are not shared between hand and eye movements. Chapter 5 further investigated the role of distractors during covert discrimination. The first experiment showed that distractor appearance did not interfere with discrimination performance. A second experiment, in which participants were also asked to saccade toward the target, confirmed the lack of RDE for covert discrimination while saccades were slower in distractor trials. The dissociation between covert and overt orienting suggests important differences between shifts of covert attention and preparation of eye movements. Finally, Chapter 6 investigated the mechanism driving the RDE. In particular it was assessed whether saccadic inhibition (Reingold & Stampe, 2002) is responsible for the increase in saccadic latency induced by remote distractors. Examination of the distributions of saccadic latencies at different distractor delays showed that each distractor produced a discrete dip in saccadic frequency, time-locked to distractor onset, conforming closely to the character of saccadic inhibition. It is concluded that saccadic inhibition underlies the remote distractor effect.

No description available.

<div>Rotating detonation engines (RDE) have the potential to significantly advance the efficiency of chemical propulsion. They are approximately one order of magnitude shorter than constant pressure engines, a savings benefit that is especially important for upper stage engines. There are many challenges to advancing their technological readiness level, but one area this thesis attempts to help mitigate is the understanding of heat loads and the viability of regenerative jacket cooling.<br></div><div> A one-dimensional, steady-state heat transfer and regenerative cooling model for the upper stage RL10A-3-3A (RL10) engine is developed in MATLAB. This model considers forced convection in the boundary layer between the combustion product gases and the hot-gas-side wall, conduction through the wall, and forced convection in the boundary layer between the hydrogen coolant and coolant-side wall. Variable gas and coolant transport properties are utilized to increase physical accuracy. The model also quantifies pressure drop through the cooling channels due to wall friction. This allows for overall heat flux, and consequently hot-gas-side and coolant-side wall temperatures to be predicted along the length of the engine. Properties of the coolant can also be predicted including the jacket outlet temperature and pressure. These cooling circuit final parameters, temperature rise and pressure drop, were matched to a more detailed, three-dimensional, transient RL10 system model developed by NASA, thereby anchoring this model.</div><div> An RDE is designed to notionally meet the thrust level of RL10. Model design decisions are documented and explained, and a detailed comparison of the two engine geometries is made. The regenerative cooling model is adapted for the RDE considering such unique aspects as detonative heat flux and the centerbody/plug nozzle. Steady state heating and cooling analysis is performed on the RDE and the results are compared to RL10. Investigation into the effects of the RDE’s differing cooling jacket output conditions on the turbine are calculated and discussed.</div><div> Appendix analyses consider more realistic detonative heat flux approximations according to recent RDE calorimetry studies and the effect of altering detonation chamber heat flux.</div><div> Even with the conservative assumption of throat-level heat flux everywhere in the RDE’s annular combustion chamber, regenerative jacket cooling shows promise as a means of thermal survival. Wall temperatures are reasonable, coolant temperature rise is lower, and coolant pressure drop is lower. The reduced temperature rise presents the new challenge of correctly powering the turbine since the incoming coolant is less energized. Further studies should also look at channel optimization specific to the RDE to maximize cooling performance and ease of system integration.<br></div>

<p>In the chlorate process, natural convection arises thanks to the hydrogen evolving cathode. This increases the mass transport of the different species in the chlorate electrolyte. There is a strong connection between mass transport and the kinetics of the electrode reactions. A better knowledge about these phenomena and their interactions is desirable in order to understand e.g. the reasons for deactivation of anode coatings and what process conditions give the longest lifetime and the highest efficiency.</p><p>One of the aims of his work was to understand how the chlorate process has to be run to avoid exceeding the critical anode potential (<em>E</em>_cr) in order to keep the potential losses low and to achieve a long lifetime of the DSAs. At <em>E</em>_cr anodic polarisation curves in chlorate electrolyte bend to higher Tafel slopes, causing increasing potential losses and accelerated ageing of the anode. Therefore the impact on the anode potential and on <em>E</em>_cr of different electrolyte parameters and electrolyte impurities was investigated. Additionally, the work aimed to investigate the impact of an addition of chromate on oxygen evolution and concentration profiles under conditions reminiscent of those in the chlorate process (high ionic strength, 70 °C, ruthenium based DSA, neutral pH), but without chloride in order to avoid hypochlorite formation. For this purpose a model, taking into account mass transport as well as potential- and concentration-dependent electrode reactions and homogeneous reactions was developed. Water oxidation is one of the side reactions considered to decrease the current efficiency in chlorate production. The results from the study increase the understanding of how a buffer/weak base affects a pH dependent electrode reaction in a pH neutral electrolyte in general. This could also throw light on the link between electrode reactions and homogeneous reactions in the chlorate process.</p><p>It was found that the mechanism for chloride oxidation is likely to be the same for potentials below <em>E</em>_cr as well as for potentials above <em>E</em>_cr. This was based on the fact that the apparent reaction order as well as α_a seem to be of the same values even if the anode potential exceeds<em> E</em>_cr. The reason for the higher slope of the polarisation curve above <em>E</em>_cr could then be a potential dependent deactivation of the active sites. Deactivation of active ruthenium sites could occur if ruthenium in a higher oxidation state were inactive for chloride oxidation.</p><p>Concentration gradients of H⁺, OH^-, CrO₄ ^2- and HCrO₄ ^-during oxygen evolution on a rotating disk electrode (RDE) were predicted by simulations. The pH dependent currents at varying potentials calculated by the model were verified in experiments. It was found that an important part of the chromate buffering effect at high current densities occurs in a thin (in the order of nanometers) reaction layer at the anode. From comparisons between the model and experiments a reaction for the chromate buffering has been proposed. Under conditions with bulk pH and chromate concentration similar to those in the chlorate process, the simulations show that the current density for oxygen evolution from OH^- would be approximately 0.1 kA m^-2, which corresponds to about 3% of the total current in chlorate production.</p>

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-01-15T21:33:32Z No. of bitstreams: 1 AmandaLucenaGermano_DISSERT.pdf: 7217536 bytes, checksum: 25a20d10202bb0af3f3b8e89539d2fbb (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-01-17T12:52:40Z (GMT) No. of bitstreams: 1 AmandaLucenaGermano_DISSERT.pdf: 7217536 bytes, checksum: 25a20d10202bb0af3f3b8e89539d2fbb (MD5) / Made available in DSpace on 2018-01-17T12:52:40Z (GMT). No. of bitstreams: 1 AmandaLucenaGermano_DISSERT.pdf: 7217536 bytes, checksum: 25a20d10202bb0af3f3b8e89539d2fbb (MD5) Previous issue date: 2017-07-31 / Com a necessidade do aumento da qualidade dos produtos e do desempenho dos processos, o grau de automa??o cresceu bastante nas ind?strias. Com isso, os sistemas est?o cada vez mais complexos e v?m acompanhados por problemas dif?ceis de resolver devido ? alta dimensionalidade desses sistemas e do grande volume do fluxo de informa??es necess?rias, al?m da aleatoriedade de falhas e defeitos. Uma falha inesperada pode levar a riscos operacionais, por isso a import?ncia de detectar e localizar a falha, principalmente quando a planta industrial ainda est? operando em uma regi?o control?vel e ? poss?vel agir para trazer o processo de volta para o estado normal, seguro e operacional. Assim, ? desej?vel que o sistema de detec??o de falhas forne?a respostas r?pidas e confi?veis com um esfor?o computacional adequado para processamento em tempo real, mesmo necessitando tratar com grandes quantidades de dados. Para trabalhar com grandes quantidades de dados em tempo real, surgiu o modelo de fluxo de dados, que consiste de uma sequ?ncia ordenada de pontos que s? podem ser lidos apenas uma ou algumas poucas vezes. Essa ?rea cresceu bastante nos ?ltimos anos, principalmente devido a grande quantidade de sistemas que precisavam tratar com dados desse tipo, que incluem desde dados do mercado financeiro, registros telef?nicos, transa??es web a dados m?dicos, redes de sensores ou mesmo dados multim?dia. Diante da relev?ncia do tema de detec??o de falhas, nessa tese foram utilizados o TEDA (Typicality and Eccentricity Data Analytics), o RDE (Recursive Density Estimation) e o R-PCA (Recursive Principal Component Analysis) como ferramentas para detec??o de falhas em processos industriais. Para a an?lise do desempenho de cada uma dessas abordagens foi utilizado o cl?ssico benchmark Tennessee Eastman Process. / In order to increase product quality and process performance, the degree of automation has grown significantly in industries. As a result, systems are increasingly complex and are accompanied by problems that are difficult to solve due to the high dimensionality of these systems and the large amount of information flow, as well as the randomness of faults and defects. An unexpected failure can lead to operational risks, so the importance of detecting and locating the fault, especially when the industrial plant is still operating in a controllable region and it is possible to act to bring the process back to normal, safe and operational. Thus, it is desirable for the fault detection system to provide fast and reliable responses with a computational effort appropriate for real-time processing, even though it requires handling large amounts of data. In this context, data stream-oriented algorithms to outlier detection may be promising candidates for fault detection of industrial process, because they work with sequences of temporarily ordered samples. In addition, they handle well with large amount of data because they are recursive and online algorithms that do not need to store past samples. Thus, in this dissertation two algorithms of this class are analyzed, named TEDA (Typicality and Eccentricity Data Analytics) and RDE (Recursive Density Estimation), when applied to fault detection of industrial processes. Their performances are compared to R-PCA (Recursive Principal Component Analysis) algorithm. The classic Tennessee Eastman Process benchmark was used as case study to evaluate these algorithms.

<div>The results of two experimental studies are presented in this document. The first is an investigation on the transient response of plain orifice liquid injectors to transverse detonation waves at elevated pressures of 414, 690, and 1,030 kPa (60, 100, and 150 psia). Detonations were produced using a predetonator which utilized hydrogen and</div><div>oxygen or ethylene and oxygen as reactants. For injectors of identical diameter, an increase in length correlated with a decrease in the maximum back-flow distance. A preliminary study using an injector of larger diameter suggested that for injectors of the same length under the same pressure drop, the larger injector was more resistant to back-flow. Refill time of the injectors was found to be inversely-proportional to detonation pressure ratio and injector stiffness, and a curve fit was produced to relate the three parameters.</div><div><br></div><div>The second experimental campaign was the hotfire testing of an RP-2-GOX rotating detonation engine. Total engine mass flow rates ranged from 0.8 to 3.5 kg/s (1.7 to 7.7 lbm/s) and static chamber pressures between 316 and 1,780 kPa (46 and 258 psia) were produced. In a majority of tests, between four and six co-rotating detonation waves were observed. Using an array of 36 embedded thermocouple probes, chamber outer wall heat fluxes between 2.8 and 8.3 MW/m² were estimated using an inverse heat transfer method of calculation. Performance of the RP-2 injector was assessed by relating to the information obtained in the prior injector response study.</div>