18 research outputs found

    Towards an uncausal practice of visual communication

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    This practice-based PhD introduces the concept of uncausality as both method and methodology to uncover potentialities for action and thought beyond habitual patterns of causality and experience. The concept derives from an investigation of asemic writing’s paradoxical dynamic, also referred to as ‘asemic effect’. Asemic writing’s formal and gestural resemblance to conventional writing evokes expectations of legibility and semantic meaning. At the same time, any effort to retrieve meaning remains unsuccessful. The asemic effect is detached from its immediate context and explored to offer a dynamic that is divergent from the ‘causal pleasure’ of human-computer interaction. The direct and predictable causality between human action and computer reaction not only appeals to, but also consolidates the human being in their position as the all-knowing agent in the face of an increasingly complex world. This thesis critiques the emphasis on pleasure, power and control that confines human thought and action to the comfortable, protected realm of the already known, hindering any venture into the unknown. The concept of uncausality taps into the potential of an encounter with the unknown, the nonsensical and the dissonant. The contemporary condition that asks humans to revaluate their habitual ways of being underlines the urgency for such an exploration. While this research originates from a practice of visual communication with a focus on interactive type design, it follows a transdisciplinary methodology, after Guattari, to weave a heterogeneous net of connections across disciplines and modes of research. It draws on the philosophical explorations of Deleuze and Guattari, their own sources and thinkers who followed them. This research engages in a practice and process of programming visually abstract real-time human-computer interfaces to explore, test and expand on the concept of uncausality. The iterative nature of the process of programming becomes an entry point to create, and encounter, a continuous mutation of the relation between cause and effect, action and reaction. The practice, conscious of the symbiotic relationship between culture and technology, explores an approach to interactivity that maintains human action and thought in a state of physical and intellectual tension. Introducing the concept of uncausality, this research hopes to invigorate practices that keep the human mind elastic in a confrontation with a changing world

    Viral Bodies: AIDS and Other Contagions in Latin American Life Narratives

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    The HIV/AIDS crisis in Latin America was overshadowed by the late phase of the Cold War, while authoritarian governments promoted discourses reflecting moral and ethical exceptionalism. People with AIDS (PWAs) experienced multiple crises—moral excision by the state, marginalization, and the certainty of death. Existing societal infrastructures of class, race, ethnicity, gender, and sexuality urged their marginalized lives into even more precarious ways of being. The authoritarian and hegemonic discourses complicated and intensified how PWAs experienced isolation, internal exile, neglect, condemnation, discrimination, and death. These exceptional conditions led to a 10-year delay before works by Latin American artists and writers emerged. My dissertation examines works by Reinaldo Arenas (Cuba), Pedro Lemebel (Chile), and Pablo Perez (Argentina) since they reveal a spectrum of intersectional AIDS subjectivities exhibiting accommodation, resistance, and transgression of prevailing national and religious norms. Drawing from the fields of exile studies, transfeminism, contagion theory, and virality, my dissertation argues that these narratives break imposed silences by radically exteriorizing the insularity, anonymity, and decomposing bodies of those dying, and living, with the disease. They intervene in national, transnational, and religious discourses. They also challenge the limits of gender and genre, while contributing to a (re)imagining of homosexual history. They offer utopian visions of kinship, belonging, and community formation and bring practices of difference such as transvestism, sadomasochism, and spiritual fetishism into focus

    Технології виробництва заготовок литтям

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    У навчальному посібнику «Технології виробництва заготовок литтям» розглянуто еволюцію ливарного виробництва, сучасні методи одержання литих заготовок, класифікацію способів виробництва заготовок литтям, їх переваги та недоліки. Подано фундаментальні основи сучасного виробництва литих заготовок, раціональні варіанти їх виготовлення; обладнання, інструменти та технологічне оснащення для різних технологічних режимів і умов. Для перевірки отриманих знань запропоновано тестові завдання з кожного розділу посібника. Начальний посібник рекомендовано для здобувачів вищої освіти галузі знань 13 «Механічна інженерія», а також для інженерно-технічних працівників ливарної промисловостіThe manual «Technologies of Workpieces Manufacturing by Castings» provides knowledge regarding different foundry processes and their industrial importance. It is considered the modern techniques of processing raw materials by casting as an important stage of solving the tasks of designing technological processes for manufacturing the parts. The manual includes fundamentals of metal casting, the evolution of the foundry industry, basic casting techniques, the metal casting operations, methods of manufacturing the cast blanks; the most rational variants of their manufacturing; equipment, tools and machining attachments for making workpieces of machine elements and parts in different process specifications and conditions. Also focused on efficient design of casting runner, riser and gating system with minimal casting defects and solidification process. Multiple choice questions from each section of the manual are offered to test the acquired knowledge. Recommended for higher education seekers in 13 «Mechanical Engineering» majors, and can also be useful for engineering and technical specialists of foundry technologies in the mechanical engineering industryINTRODUCTION...7 1. EVOLUTION OF THE METAL CASTING INDUSTRY...8 Multiple Choice Questions...18 2. METAL CASTING AS A MANUFACTURING PROCESS...22 Multiple Choice Questions...33 3. METALS AND ALLOYS USED IN METAL CASTING...38 Multiple Choice Questions...54 4. CLASSIFICATION OF METAL CASTING PROCESSES...58 Multiple Choice Questions...62 5. FUNDAMENTALS OF METAL CASTING 5.1. Metal casting basics...64 5.2. Metal casting operations...73 5.3. Gases in metal casting...80 5.4. Metal casting design...82 Multiple Choice Questions...90 6. EXPENDABLE MOLD CASTING 6.1. Sand casting...129 6.2. Plaster mold casting...140 6.3. Ceramic mold casting...143 6.4. Shell molding...146 6.5. Vacuum casting...152 6.6. Expanded polystyrene casting...158 6.7. Investment casting Multiple ...162 Choice Questions...169 7. PERMANENT MOLD CASTING 7.1. Basic permanent mold casting...204 7.2. Vacuum permanent mold casting...213 7.3. Slush casting...216 7.4. Die casting...223 7.4.1. Hot chamber die casting...233 7.4.2. Cold chamber die casting...240 7.5. Pressure die casting...248 7.5.1. Low pressure die casting...253 7.5.2. High pressure die casting...260 7.5.3. Gravity die casting...270 7.6. Centrifugal casting...276 7.6.1. True centrifugal casting...283 7.6.2. Semi-centrifugal casting...288 7.6.3. Centrifuge casting...294 7.7. Squeeze casting...299 7.8. Continuous casting...307 7.9. Evaporative pattern casting...314 7.9.1. Lost foam casting...325 7.9.2. Full mold casting...331 7.10. Stir casting...337 7.11. Ingot casting manufacture...341 Multiple Choice Questions...346 8. CASTING DEFECTS 8.1. Casting microstructure...411 8.2. Casting defects and remedies... Multiple Choice Questions...427 9. COMPUTER SYSTEMS FOR CASTING PROCESSES SIMULATION...433 GLOSSARY...446 REFERENCES...48

    Crystal growth of functional materials by using CSVS and MOCVD:The AIIMnBVI and II-oxides case

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    En esta tesis se presenta un estudio en profundidad del crecimiento cristalino y la caracterización de algunos materiales funcionales de la familia II-VI. Las propiedades estructurales, morfológicas, ópticas y eléctricas estudiadas se han correlacionado con la metodología y condiciones de crecimiento cristalino utilizadas. Entre la variedad de materiales II-VI, se han elegido 2 familias de semiconductores debido a sus propiedades singulares. El primero incluye los óxidos del grupo II, con elementos como el Zinc y el Cadmio, con una alta transparencia en el rango óptico visible. Estos compuestos se pueden usar en diversas aplicaciones en optoelectrónica, incluyendo su uso como óxidos conductores transparentes (TCO). El otro conjunto de materiales estudiados son algunos semiconductores magnéticos diluidos (DMS) basados en los compuestos ZnS y ZnTe con Manganeso que además de las propiedades semiconductoras habituales, tienen propiedades magnéticas interesantes. Con el fin de crecer los compuestos binarios y ternarios estudiados en esta tesis, se han utilizado dos métodos de crecimiento: un sistema de deposición CVD basado en la descomposición de compuestos metal-orgánicos (MOCVD), técnica con control multiparamétrico y un método más simple como es la sublimación en vacío a corta distancia (CSVS). De acuerdo con los objetivos de la tesis, la caracterización de las muestras se ha realizado utilizando las siguientes técnicas: microscopía de fuerza atómica (AFM), microscopía electrónica de barrido (SEM) y microscopía electrónica de transmisión (TEM), análisis de difracción de rayos-X (XRD), espectroscopía dispersiva de rayos-X (EDX), mediciones de emisión de rayos-X inducida por partículas (PIXE) y medidas de reflectividad y transmision óptica. Así pues, se crecieron capas delgadas de ZnO mediante el método MOCVD sobre diferentes planos de corte del zafiro. La banda prohibida directa del ZnO (~ 3.4 eV) proporciona un buen grado de transparencia óptica en la region visible del espectro electromagnético, y sus propiedades piezoeléctricas son ideales para la aplicación en filtros de ondas acústicas de superficie (SAW). El uso de este material en campos como la fotónica y la microelectrónica hace que la obtención de capas de espesor nanométrico, manteniendo una buena calidad morfológica y estructural, sea un desafío fundamental. En esta tesis se ha realizado un estudio sistemático de la disminución del espesor y rugosidad de las capas de ZnO en función de las condiciones de crecimiento (flujo del precursor, temperatura de crecimiento y tiempo de crecimiento). De manera complementaria se ha realizado un tratamiento químico del sustrato con el objetivo de aumentar los puntos de nucleación. Este estudio sistemático ha resultado en el logro y caracterización de capas de alta calidad con espesores de aproximadamente 34 nm y una rugosidad del orden de 2 nm. Teniendo en cuenta la posibilidad de cambiar las propiedades de los compuestos binarios (como la densidad de portadores o la energía del bandgap) mediante la aleación del material con otro elemento, se llevó a cabo el crecimiento de la aleación CdZnO. Una de las principales dificultades para obtener este compuesto ternario con propiedades deseables y buena calidad cristalina es la debida a la diferencia entre las estructuras cristalinas del ZnO (wurtzita) y el CdO (cúbico). La mayor parte del trabajo que se puede encontrar en la literatura está dedicado a compuestos ternarios con un alto contenido de zinc o cadmio, mientras que el estudio de la transición entre las fases cúbica y wurtzita ha recibido menos atención. En esta tesis hemos profundizado en el crecimiento de la región rica en cadmio de la aleación sobre R-zafiro, mostrando el límite de solubilidad del Zn, en las condiciones experimentales analizadas, y cómo la transición de la fase cúbica a una en la que coexisten ambas fases afecta a las propiedades estructurales de este compuesto ternario. Además, se ha analizado la influencia del gas portador sobre las características estructurales y ópticas de las capas delgadas obtenidas. En el mismo marco de estudio de la familia II-VI, el CdTe ocupa un lugar de privilegio. Este material se utiliza a menudo como capa absorbente en heteroestructuras de CdTe/CdS. Por otro lado, las heteroestructuras con TCO, en particular la heterounión p-n CdTe/CdO, han sido menos estudiadas. La complejidad en la obtención de esta heteroestructura se debe, entre otros factores, al desajuste de red entre el CdO y el CdTe. Los parámetros de crecimiento se eligieron de tal manera que las tensiones entre las capas de la heteroestructura de CdTe/CdO/R-zafiro crecida por el método MOCVD se minimizaran. El estudio de la diferencia de potencial de contacto (CPD) y el cambio en el fotovoltaje superficial (SPV) en función de la potencia aplicada del láser incidente, se han analizado en correlación a la temperatura de crecimiento. Por otro lado, los DMS combinan elementos de la física de los semiconductores y el magnetismo, lo que constituye una oportunidad única para la investigación y la tecnología. A diferencia de las aleaciones de semiconductores clásicas, la distribución aleatoria de iones magnéticos conduce a la aparición y desarrollo de fases magnéticas individuales. La inclusión de átomos de Mn en la red II-VI es particularmente interesante ya que conduce a fenómenos como la magnetorresistencia negativa, la rotación de Faraday gigante y el comportamiento del vidrio de spin. Así, hemos estudiado el crecimiento y caracterización de la aleación de ZnS y ZnTe con Mn, debido a la banda prohibida ancha que presentan y a las características ópticas derivadas que pueden presentar estas aleaciones, que las hace atractivas para aplicaciones fotovoltaicas. Así, hemos obtenido capas delgadas de ZnMnTe y ZnMnS sobre vidrio mediante la técnica CSVS. Nuestro estudio mostró el límite de solubilidad del Mn en nuestras condiciones experimentales, y cómo la incorporación de manganeso afecta las características estructurales, subestructurales y ópticas de los correspondientes compuestos ternarios.This thesis presents an in-depth study of the crystal growth and characterization of some functional materials of the II-VI family. The studied structural, morphological, optical and electrical properties have been correlated with the crystal growth methodology and growth conditions used. Among the variety of II-VI materials, 2 groups of semiconductors have been chosen due to their unique properties. The first includes oxides of II-group, with elements such as Zinc and Cadmium, with high transparency in the visible optical range. These compounds can have applications in optoelectronics and can be used as transparent conductive oxides (TCOs). The other group of studied materials is some diluted magnetic semiconductors (DMS) based on Manganese and the II-VI semiconductors ZnS and ZnTe. In addition to the usual semiconductor properties, the Mn alloyed materials can have interesting magnetic properties. In order to grow the binary and ternary compounds studied in this thesis, two growth methods have been used, the more accurate, multiparameter-controlled Metal-Organic Chemical Vapor Deposition (MOCVD) method and the simpler Close Space Vacuum Sublimation (CSVS). The characterization of the samples has been done using the following techniques: atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), energy-dispersive X-ray spectroscopy (EDX), particle-induced X-ray emission (PIXE) and optical reflectance and transmission measurements. Thus, ZnO thin films were grown using the MOCVD method on the crystal planes C-, A-, M- and R- of sapphire substrates. The ZnO direct bandgap of ~ 3.4 eV provides a good degree of optical transparency in the visible region of the electromagnetic spectrum, and its piezoelectric properties are ideal for application on surface acoustic waves (SAWs) filters. Moreover, ZnO has shown its potentiality in fields such as photonics and microelectronics. In this regard, obtaining layers of nanometric thickness, while maintaining a good morphological and structural quality, is both a requirement and a challenge. In this thesis, a systematic study of the thickness and roughness decrease of the ZnO layers has been undertaken as a function of the growth conditions (precursor flux, growth temperature and time). In a complementary manner, a chemical treatment of the substrate has been carried out, in order to increase the nucleation points. This systematical study has resulted in the attainment and characterization of high-quality layers with thicknesses of about 34 nm and roughness of about 2 nm. Taking into account the possibility of changing the properties of binary compounds (such as the carrier density or bandgap energy) by alloying the material with another element, the growth of the CdZnO alloy was carried out. One of the main difficulties in obtaining this ternary compound with desirable properties and good crystal quality is due to the difference in crystal structures between ZnO (wurtzite) and CdO (cubic). Most of the works that can be found in the literature are devoted to the ternary with high content of zinc or cadmium, while the study of the transition between the cubic and wurtzite phases has received less attention. In this thesis, we have delved into the growth of the cadmium rich region of the alloy on R-sapphire, and we have found the solubility limit of Zn under our experimental conditions, and how the transition from the cubic phase to a mixed one affects the structural properties of this ternary compound. Additionally, the influence of the carrier gas on some structural and optical features of the CdZnO thin layers has been analyzed. In the same frame of studying the II-VI family, CdTe stands out as one of the most significant of this family. CdTe is often used as an absorber layer in CdTe/CdS heterostructures. Nevertheless, heterostructures with TCO, in particular the p-n-heterojunction CdTe/CdO, have been less studied. The complexity in obtaining this structure is due to, among other factors, the lattice mismatch between CdO and CdTe. In this thesis, the growth parameters were chosen in such a way that the stresses between the layers of the CdTe/CdO/R-sapphire heterostructure grown by the MOCVD method are minimized. The study of the Contact potential difference (CPD) and the change in the Surface photo voltage (SPV) as a function of the applied power of the incident laser have been analyzed in correlation with the growth temperature. On the other hand, DMS, as said before, combine elements of the physics of semiconductors and magnetism, which is a unique opportunity for research and technology. Unlike in classical semiconductor alloys, the random distribution of magnetic ions leads to the appearance and development of individual magnetic phases. Among alloying elements, the inclusion of Mn atoms in the II–VI lattice is particularly interesting since it leads to phenomena such as negative magnetoresistance, giant Faraday rotation and spin glass behavior. We have studied the growth and characterization of the ZnS and ZnTe alloying with Mn, due to the wide bandgap and optical features that these alloys can present, which make them attractive for photovoltaic applications. Thus, ZnMnTe and ZnMnS thin films were obtained on glass substrates by the CSVS technique. The study has shown the Mn solubility limit under our experimental conditions, and how the incorporation of manganese affects the structural, substructural, and optical characteristics of the ternary compounds

    Store-and-forward CDC packet transmission in digital systems

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    Data transmission across clock domains is a major point of interest by ASIC designers as a limited bandwidth can be responsible for a processing power bottleneck that affects the entire system. Clock domain crossing is inherently expensive in terms of area and latency as it requires overcoming issues related to the physical nature of integrated circuit latches, in particular metastability. These issues are dangerous as they do not manifest in RTL simulation. Due to this, designers often opt for generic data synchronisation solutions that are not fully suited to the nature of the data being transferred.This dissertation presents a clock domain crossing mechanism that allows two clock domains to share a common memory to transfer packet-based data. The mechanism consists in a memory controller that coordinates commands from a push (write) domain and a pop (read) domain.The main objective of the memory controller project consists in the implementation of efficient synchronisation methods in order to eliminate the need for separate synchronisation and storage memories. In essence, the controller is an extension of an asynchronous FIFO controller with added functionality, supporting multiple virtual FIFOs and variable length data packets

    In Gameplay : the invariant structures and varieties of the video game gameplay experience

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    This dissertation is a multidisciplinary study on video game gameplay as an autonomous form of vernacular experience. Plays and games are traditional research subjects in folkloristics, but commercial video games have not been studied yet. For this reason, methods and concepts of the folkloristic research tradition have remained unknown in contemporary games studies. This thesis combines folkloristics, game studies and phenomenological enactive cognitive science in its investigations into player–game interaction and the video game gameplay experience at large. In this dissertation, three representative survey samples (N=2,594, N=845, N=1,053) on “Rewarding gameplay experience” are analyzed using statistical analysis methods. The samples were collected in 2014–2017 from Finnish and Danish adult populations. This dissertation also analyzes data from 32 interviews, through which the survey respondents’ gameplay preferences, gaming memories, and motivations to play were further investigated. By combining statistical and qualitative data analyses, this work puts forward a mixed-methods research strategy and discusses how the findings relate to prior game research from several disciplines and schools of thought. Based on theoretical discussions, this dissertation argues that the video game gameplay experience as a cultural phenomenon consists of eight invariants in relation to which each individual gameplay experience can be interpreted: The player must demonstrate a lusory attitude (i), and a motivation to play (ii). The gameplay experience consists of explorative and coordinative practices (iii), which engender a change in the player’s self-experience (iv). This change renders the gameplay experience inherently emotional (v) and performative (vi) in relation to the gameworld (vii). The gameplay experience has the dramatic structure of a prototypical narrative (viii) although a game as an object cannot be regarded a narrative in itself. As a key result of factor analytical studies and qualitative interview analyses, a novel approach to understanding player–game interaction is put forward. An original gameplay preference research tool and a player typology are introduced. This work argues, that, although video games as commercial products would not be intuitive research subjects for folkloristics, video game gameplay, player–game interaction, and the traditions in experiencing and narrating gameplay do not differ drastically from those of traditional social games. In contrast to this, all forms of gameplay are argued to be manifestations of the same vernacular phenomenon. Indeed, folkloristic research could pay more attention to how culture is experienced, modified, varied and expressed, regardless of whether the research subject is a commercial product or not.Käsillä oleva väitöskirja on monitieteellinen tutkimus videopelien pelaamisesta itsenäisenä kansanomaisen kokemuksen muotona. Pelien ja leikkien tutkimus on perinteikäs tutkimusaihe folkloristiikassa, mutta kaupallisten videopelien tutkimusta ei ole juuri tehty. Tästä syystä folkloristiikan tutkimusmenetelmät ja -käsitteet ovat jääneet tuntemattomaksi nykyaikaisessa pelitutkimuksessa. Tutkimus yhdistää folkloristiikan ja pelitutkimuksen näkökulmien lisäksi enaktiivisen kognition fenomenologista teoriaa pelaaja–peli-vuorovaikutuksen tutkimukseen sekä pelikokemuksen analyysiin. Tutkimuksessa analysoidaan tilastotieteellisin menetelmin kolmea aikuisväestöä edustavaa ”Palkitseva pelikokemus” -kyselytutkimusaineistoa (N=2,594, N=845, N=1,053), jotka kerättiin Suomesta ja Tanskasta vuosina 2014–2017. Kyselytutkimusaineiston rinnalla analysoidaan 32 teemahaastattelun aineistoa. Haastatteluilla tuotettiin syvempää ymmärrystä kyselyyn vastanneiden henkilöiden pelimieltymyksistä, pelimuistoista ja pelimotivaatioista. Tilastoaineiston ja haastatteluaineiston analyysi tuodaan yhteen monimenetelmällisellä ja dialogisella tutkimusotteella, joka yhdistää havainnot usealla eri tutkimusalalla tehtyyn pelitutkimukseen. Teoreettisen analyysin tuloksena argumentoidaan, että videopelien pelikokemusta ilmiönä määrittää kahdeksan muuttumatonta ominaisuutta, joiden suhteen kunkin yksittäisen pelikokemuksen ainutlaatuisuutta voidaan tarkastella: Pelaajalla tulee olla leikkisä asenne (i) ja motivaatio pelaamiseen (ii). Pelaamisen kokemus rakentuu tutkivista ja suorittavista käyntänteistä (iii), jotka tuovat väliaikaisen muutoksen pelaavan henkilön minäkokemukseen (iv). Tämän muutoksen myötä pelaajuudesta muodostuu emotionaalinen (v) ja performatiivinen (vi) positio suhteessa pelimaailmaan (vii). Näin syntyvän omakohtaisen pelikokemuksen rakenne vastaa kertomuksen dramaattista perusrakennetta (viii), vaikka peliä itsessään ei voida pitää kertomuksena. Tutkimuksen empiirisenä tuloksena esitellään faktorianalyyttisiin tapaustutkimuksiin ja laadullisten aineistojen analyysiin perustuva uudenlainen näkökulma ja menetelmä pelaaja–peli-vuorovaikutuksen ja pelimieltymyksen tutkimukseen, sekä edelliseen perustuva pelaajatyyppiluokittelu. Samalla väitetään, että vaikka videopelit kaupallisina esineinä eivät olisi folkloristiikan tutkimuskohteita, videopelien pelaaminen, pelaaja–peli-vuorovaikutus ja pelien kokemisen tavat eivät eroa ratkaisevasti pihaleikeistä vaan ovat saman kansanomaisen ilmiön esiintymiä. Folkloristisen tutkimuksen soisikin kiinnittävän nykyistä painokkaampaa huomiota kulttuurin kokemisen, muokkaamisen ja ilmaisun tapoihin riippumatta siitä, onko tarkastelun kohteena kaupallinen tuote vai ei

    CO2 separation by cryogenic and hydrate

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    According to the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4), fossil fuels are utilised to produce more than 80% of the world's energy and this is likely to remain unchanged in the nearest future, especially as industrialisation is pursued by such economic giants as China. Without substantial change in energy policies with primary focus on the development of sustainable technologies for power generation, mitigation of associated Green House Gas (GHG) emissions cannot be fully implemented, and will require continual improvement in order to achieve objectives set by the Kyoto protocol. Research and development in the field of Carbon Capture and Sequestration is therefore being thoroughly explored. In this work a new sustainable technology for CO2 capture from IGCC power stations is developed and discussed in detail. This technology is based on cryogenic condensation integrated with gas hydrate formation.With the massive global reduction in recoverable oil and the potential size in a few decades time, the accent started to shift towards the other available fossil fuels such as gas and coal. The amount of Natural Gas trapped in the form of solid hydrate sunk in the deep ocean and permafrost areas cannot be estimated precisely, however, the scientific community agrees that values in order of 1015 to 1017 cubic metres are realistic. This has caused overwhelming research into gas hydrates as storage media for different gases. Gas hydrates are highly organized crystalline structures with molecules of light gases encaged in a framework created by water molecules. They can form at any place where free water in intimate contact with hydrate forming gas is exposed to elevated pressures and low temperatures. The ability to store large quantity of gas per unit volume makes gas hydrates an attractive option for any application requiring gas preservation. One of such modern applications for gas hydrates has arisen from the global warming problem and addresses the potential capability to efficiently capture and safely store the CO2.Coal remains the main energy source in the world; for example, in Australia it is providing 40% of total energy and up to 80% of electricity (Cuevas-Cubria et al., 2010). The main advantages of coal over the other fossil energy resources are its abundance, its easy recoverability and lower cost. Massive pollution produced during burning of this fuel forced the creation of new technologies that allow for GHG reduction. Integrated Gasification Combined Cycle (IGCC) is the most favoured advanced option for energy recovery from a variety of sources, particularly coal, the so-called 'clean coal technology'. IGCC generates a high pressure shifted syngas stream composed essentially of Hydrogen and Carbon Dioxide. Historically, the CO2 was separated from rich sources (such as natural gas) via the Ryan-Holmes cryogenic condensation process. However, applied at the gas or oil refinery this method can consume up to 50% of the generated energy to bring the CO2 levels down to pipeline requirements which does not seem attractive in terms of cost of CO2 avoided. High temperatures utilised for coal gasification are also not favourable for the implementation of cryogenic condensation to an IGCC stream.On the other hand, high pressure and high CO2 content in the IGCC flue gas provide the ideal conditions for CO2 capture in the form of solid hydrates. This option has been investigated under the guidance of the US Department of Energy by a team of researchers (Los Alamos National Laboratory, Nexant, Inc., and SIMTECHE) since 1999 and at the Chinese Academy of Science. A few proof-of-concept reports can be found stating that the utilisation of the hydrate formation phenomenon for purification of gas streams is less energy intensive than any of the other existing CO2 capture methods. The ability to encapsulate significant amounts of gas in little space and relatively mild conditions of storage make the hydrates an extremely attractive option for easy handling of high rates of GHG emissions. However, this research is still on a laboratory scale.In this thesis a new method is developed for cost and energy efficient CO2 sequestration from IGCC sources based on a simple configuration. High feed pressure facilitates bulk removal of CO2 by cryogenic methods, and high energy recovery is achieved through process integration with hydrate formation. Liquid CO2 produced as a result of condensation carries most of the cold energy required for initial refrigeration, and the hydrate unit does not consume any substantial additional energy. Separated CO2 is characterised by high purity sufficient for utilisation in enhanced oil and gas recovery processes. The hydrate can be easily handled and stored. Although the focus is made on IGCC flue gas application, the method can be extended to other sources with high CO2 levels and supplied at high pressure.Additional value is brought to this research by extensive investigation of the phase behaviour of gas mixtures containing CO2. Particular attention is paid to the distinctive features of gas hydrates produced in different systems including mixtures with hydrocarbons and non-hydrocarbons in various concentrations and in the presence of chemicals dissolved in water. This knowledge will contribute to the future development in the field of hydrates and will be useful for both academic research and industrial application

    Hardware synthesis for asynchronous communications mechanisms

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    Asynchronous data communication mechanisms (ACMs) have been extensively studied as data connectors between independently timed concurrent processes. In this work an automatic method for synthesis of re-reading ACMs is introduced. This method is is oriented to the generation of hardware artifacts. The behavior of re-reading ACMs is formally defined and the correctness properties are discussed. Then it is shown how to generate the ACMs specifications and how they can be translated into a proper hardware implementation. Verilog has been used as the target language to describe the hardware being synthesized.Peer ReviewedPostprint (published version

    Forty years of antiprotons

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    The discovery of the antiproton some 40 years ago and the almost synchronous fall of parity (P) and charge conjugation (C) symmetries were soon followed by the realization that CPT rather than C invariance is the fundamental symmetry connecting matter and antimatter, and that consequently any measurement of the antiproton ' s properties can be interpreted as a test of that symmetry. It is the latter view of the antiproton, as an object of study in its own right, rather than as a means to such other ends as the production of gauge bosons and meson resonances, that is presented here. The authors review the technical steps that have led from the handful of antiprotons observed by Chamberlain, Segre, Wiegand, and Ypsilantis to the intense, high-quality beams available today and show how the state of rest and isolation required for high precision high-quality beams available today and show how the state of rest and isolation required for high precision measurements of their properties can be achieved by confining them in electromagnetic traps or in their microscopic counterparts, exotic atoms. The test bench role of antiprotons and antihydrogen atoms for both CPT symmetry and the gravitational weak equivalence principle is discussed, and the body of experimental results obtained since 1955 critically reviewed from this standpoint. Future experiments are then discussed in the light of the closure of the CERN Low Energy Antiproton Ring (LEAR), its replacement in 1999 by the Antiproton Decelerator (AD), and the likely antiproton source at the Japan Hadron Facility
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