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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Contribution au développement de modèles circuits pour l’étude de couplages électromagnétiques à l’intérieur d’enceintes métalliques / Contribution to the development of circuits models for the study of electromagnetic couplings inside metallic enclosures

Boutar, Abdelghafour 29 October 2014 (has links)
La prédiction du couplage d’interférences électromagnétiques avec les systèmes électroniques sensibles situés dans des enceintes blindées est devenue une nécessité dans le domaine de la compatibilité électromagnétique (CEM) des systèmes complexes. L’étude du couplage d’un champ ÉM avec et à l’intérieur de l’enceinte d’un équipement électronique a été réalisée antérieurement en utilisant des méthodes numériques et analytiques. Le travail de recherche présenté tout au long de ce document de thèse à pour but d’apporter une contribution à une meilleure compréhension des modèles analytiques permettant d’évaluer rapidement les niveaux de couplages induits sur un équipement électronique, en représentant celui-ci sous forme d’une enceinte métallique qui contient des monopôles, des dipôles, des plans de masse représentatifs de cartes et des lignes de transmissions. Après avoir établi le modèle physique de la fonction de Green (FG) relative à une cavité rectangulaire, la première partie à été consacrée à l’étude du couplage ÉM à l’intérieur d’une enceinte métallique rectangulaire en employant les modèles ILCM (Intermediat Level Circuit Model). Dans la deuxième partie de ce document, nous avons exploité le modèle ILCM pour l’étude du couplage ÉM avec des structures filaires de petite dimension. Afin d’étudier le couplage ÉM avec une ligne de transmission (LT) située à l’intérieur de l’enceinte d’un équipement électronique, nous avons développé au cours de la dernière partie de ce manuscrit un nouveau modèle du couplage. Différentes configurations ont été analysées, les résultats obtenus par ces analyses ont été comparés et validés avec Temsi-FD et avec les mesures expérimentales. / He electromagnetic interferences (EMI) coupling inside metallic cavities that constitutes the shielding of electronic cards is an important problem in the electromagnetic compatibility (EMC) domain. The electromagnetic (EM) coupling with transmission lines (TL) or other objects located inside an enclosure has been investigated by different authors. Previous analyses have been made using numerical and analytical methods. The goal of the research work presented in this manuscript is to make a contribution to a better understanding of the analytical models allowing to predict the EM coupling level induced on an electronic device. After the establishment the physical model for the modal representation of the Green function (GF), the first part is devoted to analyse the EM coupling within enclosure by using the ILCM (Intermediat Level Circuit Model) technique. In the second part of this manuscript, we have exploited the ILCM model for predicting the EM coupling with elementary antennas fixed within enclosure. Finally, in the last part, a simple and efficient analytical model has been developed for the prediction of the electromagnetic (EM) field coupling with a lossless transmission line (TL) located in a rectangular enclosure. The analytical results have been successfully compared over a wide frequency band with Temsi-FD and experimental results.
92

Pós-efeitos da sincronização em campo e a fase de atividade do roedor subterrâneo tuco-tuco (Rodentia: Ctenomyidae) / Aftereffects of field entrainment and the activity phase of the subterranean rodent tuco-tuco (Rodentia: Ctenomyidae)

Tomotani, Barbara Mizumo 09 December 2011 (has links)
Os tuco-tucos de Anillaco (Ctenomys cf. knighti) são roedores subterrâneos noturnos quando colocados em ciclo claro-escuro no laboratório. Com o interesse de se investigar o quanto um animal subterrâneo se expõe à luz, foi realizado um experimento de observação contínua em campo durante as horas claras do dia. Três indivíduos, um em cada estação, foram observados em uma arena semi-natural. Essas observações revelaram que os tuco-tucos não apenas saíam freqüentemente durante as horas claras do dia, como também apresentavam atividades robustas de forrageamento e remoção de terra de seus túneis. Uma vez que não se tinha conhecimento da atividade abaixo da terra ou durante à noite, foram examinados os pós-efeitos do arrastamento em campo para se investigar se o ritmo estaria sincronizado em campo e o quanto da atividade observada correspondia à atividade total do animal. Os pós-efeitos foram acessados pela transferência dos animais observados diretamente da arena para condições constantes. Surpreendentemente os animais exibiram uma atividade robusta concentrada na fase correspondente à noite ambiental sem transientes e sem traços da atividade diurna previamente observada em campo. Esse padrão foi observado em outros 10 animais trazidos dessa vez diretamente do campo e colocados em condições constantes. Além disso, não foram observadas diferenças na fase de atividade de animais com e sem acesso a rodas de atividade. Portando, nosso estudo com esses animais subterrâneos pode contribuir com elementos ecológicos nas discussões recentes sobre o significado da atividade diurna em animais que são noturnos segundo a fase do oscilador / South American subterranean rodents (Ctenomys cf. knighti), commonly known as tuco-tucos, display robust, nocturnal, wheel-running rhythms under a light-dark condition. To verify whether these subterranean and nocturnal animals ever expose themselves to light in the field, individual animals were continuously observed during light hours in a semi-natural enclosure that was constructed in their natural habitat. Observations during different seasons revealed that tuco-tucos not only emerged aboveground during daylight hours but also that their light exposure was due to robust diurnal activities of foraging and soil removal. Because of the lack of access to these animals´ subterranean and nocturnal activities in the field, the aftereffects of field entrainment were examined instead to verify the contribution of the previously observed diurnal behaviors to the total daily activity. This examination was achieved by transferring the observed animals from a field enclosure to constant laboratory conditions. Surprisingly, tuco-tucos exhibited robust activity concentrated in the phase corresponding to the external night without any trace of transients or of the diurnal activity that was observed in the enclosure. This pattern was also replicated when the aftereffects of the field entrainment of other animals trapped directly from the field were measured in the laboratory. Furthermore, no difference was detected in the activity measured with and without access to a running wheel. Our study of a wild subterranean species in its natural habitat can contribute novel ecological elements to the recently debated issue of the meaning of day-activity displayed by nocturnal rodents in the field
93

Etudes Expérimentales et lois prédictives des foyers d'incendies / Experimental studies and predictive laws for fire sources

Betting, Benjamin 21 September 2018 (has links)
Chaque année en France, les feux de compartiments donnent lieu à plus de 88 000 interventions impliquant plus de 15 000 personnes dont plusieurs centaines de décès et de blessés graves. Aujourd’hui, lors de ces feux, les prises de décision et les délais d’intervention des équipes de secours sont principalement basés sur des décisions humaines, fruits de l'expérience. Une connaissance parfaite de la situation, de son évolution dans le temps et des dangers qui peuvent apparaître est impossible. C’est en partie la cause majeure des mauvais chiffres répertoriés ci-dessus. En effet, les processus physicochimiques qui régissent les feux de compartiments et les situations collatérales extrêmement réactives et dangereuses sont complexes. La transition entre un feu localisé et un feu généralisé peut prendre plusieurs formes. L'un des vecteurs les plus importants dans la propagation de la combustion pour les feux de compartiments sont les fumées, du fait de leur température élevée (souvent supérieure à 600°C) et des quantités importantes d’énergie, sous forme de chaleur, qu'elles contiennent. Malgré leur extrême dangerosité, les fumées restent importantes à étudier car elles véhiculent de précieuses informations, notamment sur l’apparition de phénomènes thermiques redoutés par les pompiers. Afin de mener cette étude, une cellule expérimentale composé de deux containers maritimes a été installée sur le site de formation incendie des sapeurs-pompiers de Seine-Maritime. Cette plateforme va permettre, grâce à un brûleur alimenté en propane, de produire des fumées chaudes dans uneconfiguration dite « feu réel ». Elles seront analysées en partie grâce à une technique de mesure non intrusive, la PIV. Les mesures par PIV grands champs seront comparées à des simulations LES de l’expérience (FDS). La double compétence (numérique / expérimentale) est essentielle dans ce type d’étude où les données expérimentales souffrent d’un manque de résolution (spatiale et temporelle) mais pour autant représentent des informations nécessaires à la validation des codes. / Each year in France, compartment fires result in more than 88,000 interventions involving more than 15,000 people, including several hundred deaths and serious injuries. Today, during fire compartments, the decision-making of the rescue teams is mainly based on human decisions, as a result of the accumulated experience. However, a perfect knowledge of the situation, its evolution over time and the dangers that may appear is impossible. Therefore, studying the fumes is of major interest. Indeed, smoke remains important to study because it conveys valuable information, especially on the appearance of thermal phenomena feared by firemen. In order to carry out this study, an experimental cell made up of two maritime containers was installed on the site of the Seine-Maritime fire brigade fire training. This platform will produce hot smokes in a configuration called "real fire" thanks to a propane burner. In this study, the smoke dynamics in a large scale experimental setup is analyzed using a non-intrusive measurement technique such as PIV (Particle Image Velocity). All the performed measurements are compared with LES (Large Eddy Simulation) simulations of the experiment using Fire Dynamics Simulator (FDS). The double expertise (numerical / experimental) is essential in this type of study where the experimental data suffer from a lack of resolution (spatial and temporal) but nevertheless represents an important source of information necessary for the validation of the codes.
94

Prototyputveckling av fästanordning och strukturellt hölje till avloppsmonterad råttfälla : Samarbete med Nomor AB / Fastening mechanism and enclosure for sewer mounted rattrap : In cooperation with Nomor AB

Jonsson Dahl, Linus, Appelqvist, Martin January 2021 (has links)
Urbanisation has historically led to issues with property damage and sickness, due to pests such as rats. Traditionally, rats have been exterminated using poison and manually loaded traps. As of late however, more effective and humane means of control have been developed, such as automatic and connected traps. As rats use the sewer system as we use the highway, connecting properties together, it is natural to place traps there. Nomor, a service company that performs pest control among other services, is interested in developing their own automatic mechanical sewer mounted trap for their own specific needs. In this thesis, the fastening mechanism and enclosure for such a trap are developed, with a concept developed in a previous collaboration used as a base. In this concept, a fastening mechanism is used to fasten the trap to the open pipes located in the sewer manholes. Rats passing underneath the trap are executed by the striking of a carbon dioxide driven cylinder. The enclosure surrounds the fastening mechanism and provides an interface between it and the executional unit, which is developed separately. The final prototype, which was made mostly using 3D-printing of PLA parts and some light metalwork, was tested and evaluated using a testing rig made from layered MDF pieces. The rig was constructed with an optimal scenario in mind, with dimensions like those in pipes which Nomor are likely to want to mount the trap in. The main use of the rig was to evaluate the dimensions and fastening abilities of the trap. Tests and analysis of the construction gave that the fastening mechanism and enclosure had potential to meet the requirements from Nomor in a reliable manner, if a more sophisticated method of mounting and a better mechanism for keeping the trap fastened was developed.
95

Active Minimization of Acoustic Energy Density to Attenuate Radiated Noise from a Diesel Generator

Boone, Andrew J. 14 November 2006 (has links) (PDF)
The focus of this thesis was to use active noise control (ANC) to globally minimize the tonal and broadband noise radiating from a diesel generator enclosure. The major goal of this research was to show that minimizing the noise within the enclosure can lead to an overall sound pressure level (SPL) reduction of radiated noise. The target levels for overall SPL reduction were at least 2 dBA. The control algorithms used in this research were based on a filtered-x LMS adaptive algorithm, which minimizes energy density (ED). Both feedforward and feedback control approaches were investigated. The noise spectrum produced by the diesel generator enclosure includes tonal and broadband components. The target range for control was from 0 to 300 Hz. Tonal frequencies at exterior locations were often reduced by 20 to 30 dB using feedforward control. With feedback control, tones were reduced 5 to 10 dB. Broadband control results were obtained at an exterior location using a feedforward control configuration. This control was achieved for frequencies between 100 and 600 Hz and levels were reduced by up to 5 dB. Some broadband control was achieved using feedback control, but this was limited to regions at the error sensor. An overall SPL reduction of 1.9 dBA outside the enclosure was achieved near the power terminal side of the enclosure. This was accomplished using tonal and broadband feedforward control. Experimental results show that control source placement, as well as error and reference sensor location, is key to global noise reduction.
96

Effects of anthropogenic disturbances and biotic interactions on stream biota in gulf coastal plain streams

Grubh, Archis R. 14 September 2006 (has links)
No description available.
97

Hölje till övervakningsplattform för gnagare i försöksverksamhet / Enclosure for rodent monitoring platform in research

Dahlqvist, Anders January 2021 (has links)
Försöksdjursverksamhet är en viktig del inom läkemedelsutveckling och annan forskning, men svårigheterna i att övervaka djurens hälsa och aktivitet utan att stressa dem gör att en hel del studier får opålitliga resultat. Idag sker mycket av övervakningen antingen manuellt av personal som tittar till djuren, eller med automatiska metoder som innefattar något stressande moment. TrackPaw är ett svenskt startup-företag som vill ändra på detta. De utvecklar en sensorplattform som ska ligga på burens botten och mäta djurens aktivitet utan att störa dem. Detta arbete har som mål att med produktutvecklingsmetoder, materialval, beräkningar och CAD-modellering utveckla ett koncept för ett hölje till TrackPaws plattform med syfte att möjliggöra vidare utveckling av deras produkt. Kund- samt myndighetskrav sammanställdes och översattes till mätbara egenskaper i form av en målspecifikation. Konceptprocessen utfördes genom att en problemformulering utarbetades för att sedan brytas ner till delproblem. Lösningar till dessa delproblem söktes sedan internt och externt. Lösningarna sattes ihop i en konceptkombinationstabell ur vilken genererades ett antal koncept. Kriterier för ett lyckat koncept arbetades fram med problembeskrivningen och kravspecen som utgångspunkt. Valet av koncept gjordes sedan med hjälp av en matris, i vilken koncepten poängsattes mot varandra efter hur väl de levde upp till kriterierna. Det valda konceptet detaljutveklades sedan genom materialval, beräkningar och CAD-modellering. Resultatet blev ett hölje bestående av fyra delar; en toppskiva med en tunnare sektion i mitten som ska leda rörelseinformation till plattformens sensorer, en botten som rymmer plattformens komponenter, en monteringsplatta som separerar komponenterna från ytterväggarna och en packning som tätar konstruktionen. Nästa steg som bör tas är att producera höljet för att utföra ytterligare tester och säkerställa dess funktion. Av resultatet dras slutsatsen att höljet bör fylla sitt syfte och tillåta TrackPaw att gå vidare med utvecklandet av plattformen. / Animal testing plays an important part in the development of new medication and in other research, but the dificulties in monitoring the health and activity of the animals without stressing them leads quite a few studies to have unreliable results. Today, a lot of the monitoring is being done manually by personnel looking in on the animals or through automated methods that still induce some stress. TrackPaw is a Swedish start-up who are developing a platform which will change all that by being placed in the bottom of the homing cages and monitoring the animals without causing stress. The goal of this project is to, through product development methods, materials selection, calculations and CAD-modeling, develop a concept for a housing for TrackPaw's sensor platform. The purpose being to allow TrackPaw to continue the development of their product. Client and regulatory requirements were compiled and translated to measurable qualities in the form of goal specifications. The concept development process began by the development of a problem definition which was then broken down into a problem list. Solutions to these problems were sought internally and externally. The solutions were entered into a concept combination table out of which a number of complete concepts were generated. Criteria for a successful concept were created using the goal specifications and problem definition as a starting point. The concept choice was made using a decision matrix where the generated concepts were given points, relative to each other, on how well they met the criteria. The chosen concept was developed in further detail using material choice, calculations and CAD-modeling. The resulting concept is a casing consisting of four parts; a platform with a thinner section in the middle to transfer movement information to the platform's sensors, a bottom which houses the platform's components, a middle platform for mounting components on, separating them from the walls and a gasket to seal the casing. The next step in the development of the platform is to manufacture the casing and perform further testing and evaluation of its function. From the results a conclusion can be drawn that the housing should fill its purpose of allowing TrackPaw to continue the development of their platform.
98

A Search for Truth: Investigating the Connection Between Man, Architecture and the Universe

Sullivan, John Austin 21 December 2004 (has links)
The study of architecture is a search for the truth, conceived from a desire to understand the nature of life. Through the process of investigation, discoveries bring us closer to this understanding. Universal truths discovered within the discipline of architecture teach of the universal truths of life itself. Architecture is eternally bound to the universe. It exists as a physical reality, ultimately defined by a specific moment and position within the infinite continuum of time and space. Yet, what creates this inseparable connection between architecture and the universe? Man. Architecture exists as an offering to man. It serves as a stage on which the life of man unfolds; it is the backdrop of the human drama. It is the interaction between man and the physical environment that defines this connection between architecture and the universe. The instant that the hand of man touches the surface of a brick wall, a moment is created, eternally linking the wall to the universe. Thus, a constant dialogue exists between man and architecture. The nature of this dialogue must be explored, as it offers man the opportunity to understand his relationship with architecture on all scales (individual, community, universe). In order for this dialogue to be understood, the relationships which exist within architecture itself must be examined. These relationships exist on many scales, ranging from the connection between the column and the beam, to the relationship between a building and its city. These relationships dictate architecture's meaning. By being sensitive and perceptive of the nature of these relationships, we become closer to understanding the nature of life. Explorations of architecture allow us to question the nature of life. The search for the connection between architecture and the human condition allows us to understand the eternal connection between architecture and the universe. The search allows us to find the truth. / Master of Architecture
99

Aspects of interval analysis applied to initial-value problems for ordinary differential equations and hyperbolic partial differential equations

Anguelov, Roumen Anguelov 09 1900 (has links)
Interval analysis is an essential tool in the construction of validated numerical solutions of Initial Value Problems (IVP) for Ordinary (ODE) and Partial (PDE) Differential Equations. A validated solution typically consists of guaranteed lower and upper bounds for the exact solution or set of exact solutions in the case of uncertain data, i.e. it is an interval function (enclosure) containing all solutions of the problem. IVP for ODE: The central point of discussion is the wrapping effect. A new concept of wrapping function is introduced and applied in studying this effect. It is proved that the wrapping function is the limit of the enclosures produced by any method of certain type (propagate and wrap type). Then, the wrapping effect can be quantified as the difference between the wrapping function and the optimal interval enclosure of the solution set (or some norm of it). The problems with no wrapping effect are characterized as problems for which the wrapping function equals the optimal interval enclosure. A sufficient condition for no wrapping effect is that there exist a linear transformation, preserving the intervals, which reduces the right-hand side of the system of ODE to a quasi-isotone function. This condition is also necessary for linear problems and "near" necessary in the general case. Hyperbolic PDE: The Initial Value Problem with periodic boundary conditions for the wave equation is considered. It is proved that under certain conditions the problem is an operator equation with an operator of monotone type. Using the established monotone properties, an interval (validated) method for numerical solution of the problem is proposed. The solution is obtained step by step in the time dimension as a Fourier series of the space variable and a polynomial of the time variable. The numerical implementation involves computations in Fourier and Taylor functoids. Propagation of discontinuo~swaves is a serious problem when a Fourier series is used (Gibbs phenomenon, etc.). We propose the combined use of periodic splines and Fourier series for representing discontinuous functions and a method for propagating discontinuous waves. The numerical implementation involves computations in a Fourier hyper functoid. / Mathematical Sciences / D. Phil. (Mathematics)
100

Alternative electronic packaging concepts for high frequency electronics

Siebert, Wolfgang Peter January 2005 (has links)
<p>The aim of the research work presented here, is to contribute to the adaptation of electronic packaging towards the needs of high frequency applications. As the field of electronic packaging stretches over several very different professional areas, it takes an interdisciplinary approach to optimize the technology of electronic packaging. Besides this, an extensive knowledge of industrial engineering should be an essential part of this undertaking to improve electronic packaging. Customary advances in technology are driven by new findings and a continuous development of processes in clearly defined fields. However, in the field of the higher levels of the interconnection hierarchy, that is external to the chip level interconnections and chip packaging, it is supposed that a wide combination of disciplines and technical creativity, instead of advanced technology in a special area should produce most added value.</p><p>The thesis is divided into five areas, interlinked by the overall aim of there advantages to the common goal. These areas are the Printed Wiring Board (PWB) technology, PWB connections using flexible printed circuit boards, multiconductor cable connections, shielded enclosures and the related EMC issues, and finally the cooling of electronics. A central issue was to improve the shielded enclosures to be effective also at very high frequencies; it will be shown that shielded enclosures without apertures can cope with frequencies up to and above 15 GHz. Due to this enclosure without apertures, it was necessary to develop a novel cooling structure. This cooling structure consists of a heat sink where the PCB’s are inserted in close contact to the cooling fins on one side, whereas the other side of the heat sink is cooled by forced ventilation. The heat transfer between these parts is completely inside the same body. Tests carried out on a prototype have shown that the performance of the cooling structure is satisfactory for electronic cooling.</p><p>Another problem area that is addressed are the interconnect problems in high frequency applications. Interconnections between parts of a local electronic system, or as within the telecom and datacom field between subscribers, are commonly accomplished by cable connections. In this research work multiconductor cables are examined and a patented novel cable-connector for high frequency use is presented. Further, an experimental complex soldering method between flexible printed circuits boards and rigid printed circuits boards, as part of connections between PCBs, is shown. Finally, different sectors of the PCB technology for high frequency applications are scrutinized and measurements on microstrip structures are presented.</p>

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