L’un des défis majeurs pour la conception des capsules de rentrée concerne la modélisation des transferts convectifs et radiatifs à la surface du véhicule. A certains points des trajectoires de rentrée super-orbitale, jusqu’à 40% du flux radiatif total émane du domaine spectral VUV (vacuum ultraviolet), or c’est dans ce domaine que les incertitudes sont les plus fortes. Ce haut niveau d’incertitudes est dû en particulier à un manque de données expérimentales fiables. Le rayonnement VUV est en effet difficile à mesurer en raison de la forte absorption de l’air et des optiques utilisées pour sa mesure. Des difficultés d’analyse supplémentaires sont causées par le fort degré d’auto-absorption et par l’élargissement spectral des raies dans le VUV. L’objectif central de cette étude était d’obtenir des spectres d’émission expérimentaux calibrés dans le VUV afin d’étudier les processus physico-chimiques dans la couche de choc qui contrôlent le flux radiatif. Plus précisément, les objectifs étaient de comparer les spectres observés parallèlement et perpendiculairement à la couche de choc, d’étudier les effets sur l’intensité des raies spectrales émises dans le VUV de l’auto-absorption et de l’élargissement spectral en fonction de la profondeur de champ radiatif (épaisseur optique). Les mesures effectuées perpendiculairement et parallèlement à la surface d’une maquette placée dans l’écoulement représentent un premier jeu de données expérimentales calibrées dans le VUV qui seront utiles pour valider les codes de calcul destinés à prédire le flux radiatif incident. Les mesures obtenues pour différentes profondeurs de champ radiatif représentent quant à elles un ensemble de données expérimentales uniques pour la validation des modèles de transport radiatif et des coefficients d’élargissement des raies. Cette étude s’appuie également sur des simulations numériques afin d’évaluer les prédictions d’un solveur d’écoulement couplé à deux schémas cinétiques à travers la comparaison des spectres mesurés avec les spectres simulés par le code radiatif Specair. Pour atteindre ces objectifs, un banc optique a été conçu et mis en place pour mesurer l’intensité du rayonnement VUV produit autour d’une maquette bidimensionnelle émoussée, avec une résolution spatiale suffisante pour résoudre le profil d’émission dans la couche de choc. La résolution spatiale a été choisie de façon à pouvoir effectuer des mesures du rayonnement dans les zones d’équilibre et hors équilibre de la couche de choc. Un deuxième système a été conçu pour obtenir des mesures du rayonnement VUV incident sur la surface de la maquette. Ce système est constitué d’un hublot placé sur la surface de la maquette et d’un miroir logé à l’intérieur de la maquette pour transmettre le rayonnement vers le système de détection. La profondeur du champ radiatif peut être variée en modifiant la longueur de la maquette, ce qui change l’épaisseur de la couche de choc observée. Le tunnel à détente X2 a été utilisé pour créer les écoulements à haute enthalpie nécessaires pour produire les couches de choc émissives. Deux conditions d’écoulement ont été générées pour cette étude de façon à reproduire des vitesses équivalentes de vol de 10 et 12.2 km/s. Le système spectroscopique utilisé pour ces études comprend un spectromètre McPherson NOVA 225 sous vide couplé à une caméra ICCD Andor iStar de réponse renforcée dans le VUV. Un tube optique scellé par une fenêtre en fluorine a été installé pour prolonger le trajet optique sous vide jusqu’à la maquette de façon à éliminer l’absorption par l’oxygène moléculaire. Le système spectroscopique a été calibré in situ avec une lampe à deutérium placée à l’endroit de la couche de choc rayonnante. L’intensité spectrale incidente sur la surface de la maquette, intégrée entre 115 et 180 nm, est de 0,744 W/cm²sr pour une vitesse d’écoulement de 10 km/s et 12,3 W/cm²sr à 12.2 km/s. [...] / A major design challenge for re-entry capsules lies in the modelling of convective and radiative heat transfer to the surface of the vehicle. At certain points on superorbital re-entry trajectories, up to 40% of the total radiative heat flux is contributed by the vacuum ultra-violet (VUV) spectral range and it is in this spectral range that the largest uncertainties lie. The high level of uncertainty in the VUV is a result of a lack of published experimental data due to difficulties encountered in measuring radiation in the VUV, such as strong absorption by most optical materials and air. Additional complexities of the VUV spectral range include its strongly self-absorbing nature and spectral line broadening. The primary goal of this study was to obtain calibrated spectral measurements in the VUV that enable the investigation of physical processes occurring in the shock layer that influence the incident radiative heat flux. In particular, the issues to be investigated were the variation in spectral radiance observed across a shock layer compared to the spectral radiance measured through the surface, the effects of self-absorption on spectral line intensity and the broadening of spectral lines in the VUV as a function of depth of radiating flow field. The measurements made across and through the surface of a model provide the first set of calibrated experimental results for the validation of computational codes used to predict incident radiative heat flux. Measurements made with a varying depth of radiating flow field provide a unique set of experimental data for the validation of radiation transport models and broadening coefficients. This study also used computational simulations to investigate the accuracy of a flow field solver coupled with two reaction rate schemes and compared the spectra produced using Specair with experimentally measured values. To achieve these goals, an optical system was designed to measure the VUV radiative emission produced around a blunt two-dimensional model in a spatially resolved manner across the shock layer. Spatial resolution allowed for spectral measurements to be made in both the equilibrium and non-equilibrium parts of the shock layer. A second optical system was designed to obtain measurements of VUV radiation incident on the surface of the model. This system incorporated a window in the surface with a mirror housed within the model to deflect the radiation out of the test section and into the detection system. To effectively vary the depth of the radiating flow field, the length of a two-dimensional model was varied, changing the depth of the shock layer being observed. The X2 expansion tube was used to create the high enthalpy flows required to produce radiating shock layers. Two flow conditions were created for this study that represented flight equivalent velocities of 10.0 km/s and 12.2 km/s. The spectroscopy system utilized for this study consisted of an evacuated McPherson NOVA 225 spectrometer coupled to an Andor iStar VUV enhanced intensified charge coupled device. An evacuated light tube sealed with a magnesium fluoride window was required to extend the evacuated light path to the model and avoid any absorption by molecular oxygen. An in-situ calibration of the VUV spectroscopy system was conducted using a deuterium lamp located in the position of the radiating shock layer. The integrated incident spectral radiance measured through the surface of the model between 115 nm and 180 nm was 0.744 W/cm2 sr for the 10.0 km/s condition and 12.3 W/cm2sr for the faster 12.2km/s condition. [...]

Orientador: Vitor Baranauskas / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-06T07:59:42Z (GMT). No. of bitstreams: 1 Amorim_MauroVanderleide_M.pdf: 4658675 bytes, checksum: 1d0d3ce62cb40cd86d00a29631b96508 (MD5) Previous issue date: 2005 / Resumo: Foi desenvolvida uma câmara de vácuo para estudo das propriedades elétricas de emissão de elétrons por catodos frios de vários materiais de interesse tecnológico, por exemplo, diamante dopado, filmes de carbono diamantífero e silício. Na parte experimental realizamos um sistema de alto vácuo (bomba mecânica mais a bomba difusora), um sistema de posicionamento de 6 graus de liberdade e um sistema de medida da corrente de emissão de elétrons. A modelagem matemática da emissão foi baseada na teoria de Fowler ¿ Nordheim. Foram feitos os cálculos relativos às propriedades de vácuo do sistema utilizado e a seguir a caracterização de algumas amostras de estruturas nanométricas produzidas utilizando o processo de deposição química a partir da fase vapor do etanol (HFCVD) com altas concentrações de hélio e argônio / Abstract: A vacuum chamber was developed for study the physical properties of electron emission by cold cathodes of several materials of technological interest as for example, doped diamond, films of diamond-like carbon and silicon. In the experimental part we accomplished a system of high vacuum (mechanic and diffusion pumps), a positioning system of 6 degrees of freedom and a system to measure of the electron emission current. The mathematical modeling of the emission was based on the theory of Fowler - Nordheim. Relative calculation of the properties of vacuum in the used system was made to check the characterization of some samples of nanometric structures produced using the process of chemical deposition starting from the phase vapor of the ethanol (HFCVD) with high concentrations of helium and argon / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

This diploma thesis is about designing vacuum pressing device for plastics as an important method of manufacturing semi-finished plastic products. In introduction part of this thesis there is described a process of this method, the application field among the another plastics processing technologies, basic information about using semi-finished products and moulding forms. There are three versions of solution. After the estimation of this versions there is a decision about a final form vacuum pressing device. One’s own design work contains a project of a device like this with the help of Autodesk Inventor CAD system. In the end of the work, there is financial balance-sheet too.

No description available.

In der Milchviehhaltung nimmt die Anzahl der eingesetzten Onlinesensoren zu. Somit können bedeutende biologische Veränderungen bei Kühen z. B. Sekretveränderungen frühzeitig erkannt werden. Hohe mechanische Belastungen am Zitzengewebe, die z. B. zu Ringbildungen führen, treten beim Melken jedoch immer noch häufig auf. Eine nicht optimal angepasste Melktechnik kann einer der Gründe dafür sein. Hauptziel dieser Arbeit ist es, ein Vakuumregelungssystem für das zitzenendige Melkvakuum zu entwickeln, das in engen Zeitabständen reagiert. Das zitzenendige Melkvakuum soll durch die Regelung in der Saugphase bei großen Milchflüssen einen konstant niedrigen Vakuumabfall aufweisen. In der Entlastungsphase soll die Regelung dagegen einen konstant hohen Vakuumabfall erzeugen. Bei Nassmessungen (ISO 6690, 2007) wurden verschiedene viertelindividuelle Melksysteme im Melklabor und in Praxisbetrieben in Bezug auf ihr zitzenendiges Melkvakuum untersucht. Nachfolgend wurden verschiedene Vakuummess- und Aktorsysteme zur Vakuumbeeinflussung untersucht. Die wichtigsten Ergebnisse der Untersuchungen bestehen darin, dass die Konzeption für ein Vakuumregelungssystem gefunden und ein Prototyp gebaut werden konnte. Weiter wurden die Anforderungen an ein optimales zitzenendiges Melkvakuum erarbeitet. Das Konzept für das entwickelte Vakuumregelungssystem lässt erwarten, dass das zitzenendige Melkvakuum in der Saugphase auf 20 kPa bei einem Milchfluss von 0,25 l/min/ Euterviertel reduziert werden kann. Bei hohen Milchflüssen von 1,5 l/min/ Euterviertel und mehr wird das Vakuum in derselben Phase hingegen auf einen Mittelwert von 30 kPa eingestellt. Damit kann erstmals ein hohes Melkvakuum bei hohen und ein niedriges Melkvakuum bei niedrigen Milchflüssen erreicht werden. In Zukunft sollte das entwickelte Vakuumregelsystem zur Nutzung in allen viertelindividuellen Melksystemen angepasst werden. / The number of online-sensors in dairy farming is increasing. In this manner, important biologically changes in cows as for example changes in secretion can be detected at an early stage. But high mechanical strains on the teat tissue during milking still occur frequently and can for example lead to formation of teat rings. A suboptimal adjusted milking technology can be one of the reasons for the mentioned observations. The objective of this dissertation was to develop a vacuum control system for the teat-end vacuum that can react in short time intervals. The teat-end vacuum produced by that control system should be with constant low vacuum reduction in suction phase at high milk flows. Moreover, in release phase the control system should provide constantly high vacuum reductions. In wet-tests (ISO 6690, 2007) several individual quarter milking systems in laboratory and practical milking parlours were evaluated in terms of their associated teat-end vacuum conditions. Several vacuum measuring and actuator systems for controlling the vacuum were tested. The most important result of the studies was that the general concept for a teat-end vacuum control system was developed, and a prototype of that system was produced. Important requirements for an optimum teat-end vacuum were revealed during that work. The concept for the planned vacuum control system suggests that it is possible to reduce the mean teat-end milking vacuum in the suction phase to 20 kPa at a flow rate of 0.25 l/min per udder quarter. At higher flow rates of 1.5 l/min and more per udder quarter, the teat-end vacuum is similar to the machine vacuum with a mean value of approximately 30 kPa. Therefore, for the first time, it is possible to supply a high teat-end vacuum at a high and a low teat-end vacuum at low milk flow rates. In the future, the developed vacuum control system should be adapted for installation in all types of individual quarter milking systems.

Call number: LD2668 .T4 1963 W87 / Master of Science

Cette étude pilote évalue le coût et des éléments d'efficacité du traitement conventionnel d'un ulcère du pied diabétique et de la combinaison de la thérapie par pression négative combiné à un pansement d'argent nanocristallin, de manière rétrospective, à partir des dossiers archivés. Cette étude coût-conséquence s'effectue selon la perspective du système public de soins de santé durant la période d'hospitalisation. Des analyses de survie pour des événements récurrents ont également été effectuées afin d'évaluer l'efficacité du traitement combiné par rapport au traitement conventionnel concernant le risque d'amputation. Seize personnes présentant un ulcère du pied diabétique sévère se détériorant, admises dans un même hôpital de la Montérégie ont été incluses dans l'étude. Tous les patients identifiés entre 2003 et 2007, traités par la combinaison de la thérapie par pression négative et du pansement d'argent nanocristallin ont été inclus (n = 5). Les autres patients ont été traités de façon conventionnelle (n = 5). Un troisième groupe a fait l'objet d'une évaluation au moyen de la combinaison, mais après une amputation (n = 6). Tous les frais hospitaliers disponibles ont été inclus dans les calculs à un niveau de précision le plus élevé possible. Les résultats de notre recherche dévoilent que, sur un suivi moyen d'environ trois ans, le coût moyen du traitement d'un ulcère du pied diabétique sévère s'élève à 71 420,98 $ pour le groupe des patients traités de façon conventionnelle et à 78 771,10 \$ pour le groupe traité par la combinaison. Pour tous les groupes confondus, le coût du traitement local de la plaie représente environ 4 % du coût total alors que les frais reliés à l'hospitalisation en représentent 60 %. De plus, les résultats des analyses de survie montrent un risque significatif six fois moins élevé de subir une amputation lorsque le patient reçoit le traitement combiné par rapport au traitement conventionnel. Nos résultats se démarquent de ceux publiés jusqu'à maintenant, par une méthode de calcul la plus précise possible. Les résultats nous permettent de conclure que le traitement combiné représente une minime partie du coût total du traitement par rapport aux frais hospitaliers et permet d'éviter des amputations.

Digitalization is finding it’s way into production and machine-building. Autonomous, sefoptimizing and highly interconnected units will determine the functionality of machines and production facilities. Communication and automation layout will fundamentally change, data will be more and more the base for new business modells. Innovation is determining pneumatics and handling technology. The innovation topics performance improvement, modular and mechatronic design of systems, sustainability and efficiency are keeping pneumatics and vacuum technology on the pathway of success. But is the technology field also prepared for the tremendous challenges caused by the digitalization? This paper is focusing on the significance of digitalization for fluid technology, especially for pneumatics and vacuum technology. The new concepts of digitalization and autonomization are based on the Internet of Things with open Communication of cyber-physical systems. These cyber-physical systems are able to react autonoumously. Cyber-physical systems can collect, interpret and analys data and transfer it into valuable information. Based on these data, cyberphysical systems will provide services to all participants of the smart factory. There will be a digital image inside the factory cloud, which is the base of new business models. Systems of pneumatics, vacuum technology and hydraulics will play a core role in this world. They are placed directly at the interface to the real technical process, they have direct contact with the workpieces, they are collecting multitude of sensor data and are evaulating it, they have functionality like Condition Monitoring and Energy Efficiency optimization on board and are able to communicate with the world of automation. This paper will show, that the innovation trends of the last years are supporting the way towards digitalization and Industrial Internet of Things. There are already a lot of different approaches to establish vacuum and pneumatic systems as adequate elements of the digitalized world. It will also be shown, that fluid technology still is facing tremendous challenges It will be not sufficient to equip the systems with more functionality and better communication. It will be essential, that from the interpretation and correlation of data will be derived valuable services with real customer benefit. This should happen under control of the vendors of smart field devices in fluid technology. Then it will be possible to turn this new kind of value generation also into new business models.

Thesis (MSc (Physics))--University of Stellenbosch, 2005. / A tunable vacuum ultra-violet (VUV) laser source was recently developed for VUV spectroscopy using state selective excitation and total fluorescence detection. The VUV laser source makes use of a four-wave mixing process to provide tunable VUV radiation for the electronic excitation of the molecules. The theory of four-wave mixing, with the emphasis on parameters that are important for our experimental setup to generate efficient tunable VUV radiation is discussed. The experimental setup, and in particular the metal vapor heat-pipe, which provides Mg vapor as the nonlinear medium, is described. New diagnostic equipment described in this work was added to the experimental setup. This equipment was characterized and utilized together with the existing setup. The additional diagnostic equipment introduced enabled us to measure the tunable VUV output of the source (using a VUV monochromator), making it possible to significantly improve the efficiency of the existing tunable VUV laser source.

Thesis (PhD)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: A tunable narrow-bandwidth laser source combined with a supersonic gas jet as sample is wellsuited for obtaining high-resolution spectra of cold isolated molecules and complexes. In the present study such a laser source in the vacuum ultraviolet was applied to the spectroscopic investigation of rare carbon monoxide (CO) isotopomers and CO-noble gas van der Waals complexes in supersonic gas pulses seeded with natural CO gas. Tunable coherent vacuum ultraviolet radiation was generated by two-photon resonant fourwave sum-frequency mixing of two pulsed dye laser beams in a magnesium vapour medium. Laser induced fluorescence excitation spectra of the A(v'=3)-X(v"=0) vibronic band of CO molecules in a noble gas (neon or argon) jet were obtained by measuring the total undispersed fluorescence from the irradiated sample volume in dependence of the excitation wavelength. The dynamics of the flow-cooling process in the supersonic jet were investigated and the experimental parameters optimised using the rotational temperature of 12C160as determined from rotational line intensities. Rotational temperatures as low as 2 ± I K were observed. Spectroscopic detection of the rare 12C170and 12C180isotopomers was facilitated by the low rotational temperature and high spectral resolution. Six rotational lines of 12C170and four of 12C180were detected in the A(v'=3)-X(v"=0) vibronic band. This demonstrates the low detection limit (circa 3 parts per million) obtained in the experiment. The line wavelengths were determined to an accuracy of 0.2 pm using the well-documented 12C160and 13C160lines for calibration. The spectral results on 12C170are, to our knowledge, the first rotationally resolved laboratory measurements published on the A-X band of this isotopomer. Accurate wavelength data of the stable isotopomers of CO is of importance in the interpretation of astrophysical observations of CO in the interstellar medium. The newly determined 12C170wavelengths were successfully applied to a recent problem in astrophysics (Astrophys. J. Lett. 2003). The conditions in a supersonic jet facilitate the study of weakly bound van der Waals complexes, of which CO-noble gas complexes are prototypes. However, there is no experimental data available on the electronic excitation spectra of the CO-noble gas complexes, lying in the vacuum ultraviolet region. In the present experiment evidence of extensive complexation of the CO in the noble gas jet has been found, but in the spectral region around the A(v'=3)-X(v"=O) band of CO no distinct spectral features that could be associated with these complexes were observed. Having considered the existing knowledge on CO and CO-noble gas complexes and experimental studies on the excitation and dissociation dynamics of Iz-noble gas complexes, we regard complex induced inter-system crossing or electronic predissociation as the most likely causes for these observations. The results on the rare CO isotopomers demonstrate the potential of our experimental setup for high-resolution, isotope and state selective spectroscopy in the vacuum ultraviolet with a high sensitivity for fluorescent species. The availability of the now well-characterised experimental setup in our laboratory opens the way for further investigation of molecular or complex species with spectroscopic features in the vacuum ultraviolet region. / AFRIKAANSE OPSOMMING: Vakuum ultraviolet laser spektroskopie van CO molekules in 'n supersoniese gasstraal: 'n Afstembare smal bandwydte laserbron en 'n supersoniese gasstraal as monster is 'n geskikte kombinasie vir hoë-resolusie spektroskopie van geïsoleerde afgekoelde molekules en komplekse. In hierdie studie is so 'n laserbron in die vakuum ultraviolet gebruik in die spektroskopiese ondersoek van skaars koolstofmonoksied (CO) isotopomere en CO-edelgas van der Waals komplekse in supersoniese gaspulse wat 'n klein persentasie natuurlike CO gas bevat. Afstembare koherente vakuum ultraviolet lig is verkry deur twee-foton resonante vier-golf som-frekwensie vermenging van twee gepulseerde kleurstoflaserbundels in 'n magnesiumdamp medium. Laser-geïnduseerde fluoressensie opwekkingspektra van die A(v'=3)-X(v"=0) vibroniese band van die CO molekules in die edelgasstraal (neon of argon) is uitgemeet deur die totale fluoressensie van die beligte gasmonster, sonder golflengteskeiding, te meet as funksie van die opwekkingsgolflengte. Die dinamika van die vloeiverkoelingsproses in die supersoniese gasstraal is ondersoek en die eksperimentele parameters geoptimeer deur gebruik te maak van die rotasionele temperatuur van 12Cl60 soos bepaal uit die intensiteitsverhoudings van die rotasielyne. Rotasionele temperature tot so laag as 2 ± 1 K is waargeneem. Spektroskopiese waarneming van die skaars 12C170 and 12Cl80 isotopomere is moontlik gemaak deur die lae rotasionele temperatuur en die hoë spektrale resolusie. Ses rotasielyne van 12C170 en vier van 12C180 is waargeneem in die A(v'=3)-X(v"=0) vibroniese band. Dit demonstreer die lae deteksielimiet (ongeveer 3 dele per miljoen) wat bereik kon word. Die golflengtes van die lyne is bepaal met 'n akkuraatheid van 0.2 pm deur die bekende lyne van 12C160en 13C160vir kalibrasie te gebruik. Die resultate ten opsigte van 12C170 is sover vasgestel kon word die eerste rotasioneel-opgeloste laboratorium metings van die A-X band van hierdie isotopomeer. Akkurate golflengte data vir die stabiele CO isotopomere is van belang vir die interpretasie van die astrofisiese waarnemings van CO in die interstellêre medium. Die nuwe 12C170 golflengtes is suksesvol aangewend in die oplossing van 'n onlangse interpretasieprobleem in astrofisika (Astrophys. J. Lett. 2003). Die toestande in 'n supersoniese gasstraal maak die bestudering van swak-gebonde van der Waals komplekse moontlik. Hoewel CO-edelgas van der Waals komplekse as prototipes beskou word, is daar geen eksperimentele data beskikbaar oor die elektroniese opwekkingspektra van hierdie spesies, wat in die vakuum ultraviolet gebied lê, nie. In hierdie studie is daar eksperimentele getuienis gevind vir uitgebreide kompleksering van CO in die edelgasstraal, maar in die spektraalgebied rondom die A(v'=3)-X(v"=O) band van CO is geen duidelike spektrale kenmerke wat met hierdie komplekse geassosieer kan word, waargeneem nie. Na oorweging van die bestaande kennins oor CO en CO-edelgas komplekse en eksperimentele studies oor die opwekking en dissosiasie-dinamika van Iz-edelgas komplekse, beskou ons kompleksgeïnduseerde intersisteemoorgange of elektroniese predissosiasie as die waarskynlikste redes vir hierdie waarnemings. Die resultate oor die skaars CO isotopomere toon die potensiaal van ons eksperimentele opstelling vir hoë-resolusie, isotoop- en toestandselektiewe spektroskopie in die vakuum ultraviolet met uitstekende sensitiwiteit vir fluoresserende spesies. Die beskikbaarheid van hierdie nou deeglik gekarakteriseerde eksperimentele opstelling in ons laboratorium maak verdere ondersoek na molekulêre of kompleks-spesies met spektroskopiese kenmerke in die vakuum ultraviolet moontlik.