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Propuesta de sistema constructivo de losas industriales sin juntas de contracción, reforzadas con fibras metálicas y aditivo, minimizando su retracción y cambio volumétrico, en Lima / Proposal of constructive systems of industrial slabs without retraction joints, reinforced with metallic fibers and additives, that minimizing retraction and volumetric change, in limaEffio Reátegui, Manuel Angel Alessandro, Quiñones Ticse, Igor Jesús 26 November 2021 (has links)
Hoy en día con el aumento exponencial de las industrias a nivel mundial situadas sobre grandes extensiones de terreno, requieren construcciones con un alto grado de desempeño que optimicen al máximo los tiempos de ejecución y, sobre todo, costos mínimos de manteniendo, mediante el presente estudio se propone una solución para las losas industriales, las cuales son de concreto sin juntas de retracción (cortes), con incorporación de fibras de acero y aditivo de retracción compensada, minimizando considerablemente los problemas que se puedan presentar, como es el caso del fenómeno de la retracción en una losa industrial el cual causa agrietamiento y/o despostillamiento de esta, generando pérdidas económicas a largo plazo.
Al conocer este problema, se requerirá de materiales y sistemas constructivos que minimicen los efectos de la retracción en las losas industriales sin juntas, como por ejemplo un aditivo de retracción compensada que utilizaría químicos dilatadores en conjunto con aditivos que ayuden a frenar de forma paulatina el fraguado que expande la composición durante, al menos, los primeros días de existencia del elemento. Esa expansión debe asemejarse a la retracción calculada para finalmente alcanzar un cambio de volumen muy cercano a cero. / Nowadays, the exponential growth of the worldwide industries established on large land areas requires constructions with a high-performance level that maximizes the execution times and, especially, minimal operational costs. Through the present study, we propose a solution for industrial slabs, which are made of concrete without retraction joints (cuts), with the inclusion of steel fibers and additives of compensated retraction, substantially minimizing the problems that may arise, such as the case of the retraction phenomenon on industrial slabs, that causes cracking and spalling of it, generating long-term economic losses.
Due to this problem, material and constructive systems that minimize the effects of retraction on industrial slabs without joints will be required; for example, an additive of compensated retraction that would use dilating chemicals ensembled with additives that gradually helps to restrain the curing that expands the compositions during, at least, the first days of existence of the element. This expansion must resemble the estimated retraction to finally achieve a change of volume very close to zero. / Tesis
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Realistický model oblohy / Realistic Model of the SkyKussior, Zdeněk January 2007 (has links)
The paper describes a theoretical base and realization of realistic volumetric clouds visualization in an environment of real-time simulator. The first part is concerned with a meteorological background of this problem. I show international classification of ten basic cloud types including a short description and cases of occurence. The following part is concerned with an interaction between cloudiness and simulation core, which is based on the fact, that each cloud acts as a mechanical or an electromagnetic obstacle. This should be considered on some way in simulation. The next part describes technologies and practical implementations of visualization and evaluates their characteristics. Finally, the last chapter describes my implementation and tries to outline project advancement.
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3D Object Manipulation in Volumetric Video Production / 3D-objektmanipulation i volymetrisk videoproduktionWang, Xinyi January 2023 (has links)
Remote communication methods have been changing these years and becoming even more important due to the global pandemic. Holographic communication, often represented by volumetric video, is one of the emerging communication methods. Unfortunately, there are few researches on combining 3D objects with volumetric videos. Based on a review of 3D object manipulation methods, two input modalities including laptop trackpad and mobile touchscreen are selected to combine with the volumetric video production. This study aims to explore human factors in volumetric video production and determines the differences between different 3D object input modalities in volumetric video production. A prototype of a volumetric video production tool is built and refined. NASA-TLX, SUS sub-scale, and semi-structured interview are performed in a pilot study and the main study, in order to measure the perceived workload and learnability of the prototype. Analysis of the subjective data demonstrates that there are no significant differences between those two input modalities. Several implications for the design and research gap of combining 3D object manipulation with volumetric video production have been brought up based on the results of this study. / Metoder för fjärrkommunikation har förändrats under dessa år och blivit ännu viktigare på grund av den globala pandemin. Holografisk kommunikation, ofta representerad av volymetrisk video, är en av de framväxande kommunikationsmetoderna. Tyvärr finns det få undersökningar om att kombinera 3D-objekt med volymetriska videor. Baserat på en genomgång av 3D-objektmanipulationsmetoder, väljs två inmatningsmodaliteter inklusive styrplatta för bärbar dator och mobil pekskärm för att kombineras med den volymetriska videoproduktionen. Denna studie syftar till att utforska mänskliga faktorer i volymetrisk videoproduktion och fastställa skillnaderna mellan olika 3D-objektinmatningsmodaliteter i volymetrisk videoproduktion. En prototyp av ett volymetriskt videoproduktionsverktyg byggs och förfinas. NASA-TLX, SUS sub-scale och semi-strukturerad intervju utförs i en pilotstudie och huvudstudien, för att mäta den upplevda arbetsbelastningen och inlärbarheten av prototypen. Analys av subjektiva data visar att det inte finns några signifikanta skillnader mellan dessa två inmatningsmodaliteter. Flera implikationer för design- och forskningsgapet av att kombinera 3D-objektmanipulation med volymetrisk videoproduktion har tagits upp baserat på resultaten av denna studie.
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Methods for Identifying Acoustic Emissions From the Front Face of a Small Piezoelectric BlowerSolomon, Brad K. 12 December 2012 (has links) (PDF)
This thesis focuses on identifying acoustic noise generating components in piezoelectric blowers through transverse velocity measurements and the development of a numerical fluid model. Piezoelectric ceramics have proven useful for many industries and areas of research involving: high precision actuators, noise control, ultrasonic devices, and many other areas. As of late, a unique adaptation of piezoelectric ceramics is surfacing in the area of pumping and cooling. Air pumps that use these ceramics replace the traditional electric motor, resulting in lower power consumption, less moving parts, constant pressure gradients, lower overall weight, and a low profile. The current drawback of this application is the acoustic radiation produced by the blowers. Since these blowers are new to market, little research or development has been done to characterize the noise emissions. This thesis studies the acoustic emissions from the front face of a Murata piezoelectric blower. Jet noise and structural vibrations are two acoustic sources of interest that are studied in this research. A Direct Numerical Simulation (DNS) of the fluid flow through a Murata blower is developed to better identify noise generating mechanisms. The model solutions predict trends in sound pressure levels (SPL) of the jet noise and volumetric flow rates. Both the SPL and flow rate are shown to be functions of critical geometrical dimensions within the flow path of a Murata blower. Important dimensional components are identified as well as non-influential ones. Design guidelines are given to reduce noise emission from the front side of a blower and increase the volumetric flow rate. The results of this research have a direct impact on the piezoelectric blower industry and future blower designs.
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Increasing the dosing accuracy of a screw dosing device by inline measurement of the product densityKruppa, Felix, Weiß, Uta, Oberdorfer, Berend, Wilke, Bernd 19 March 2024 (has links)
Fine-powdered bulk materials exhibit high compressibility even under low pressure. The dosing error in volumetric dosing devices increases fundamentally with increasing product compressibility. In order to increase the dosing accuracy of a volumetric dosing of powdered bulk solids, the dosing process must be adapted to the product parameters. The most important parameter is the time-variable product density. With a pure volumetric dosage, it has a direct influence on the actually filled product quantity. Attempts are often made to obtain feedback by means of a scale in order to continuously adjust the volume. However, this is often associated with a delay. In this article, the approach is to measure the product mass flow directly by means of a microwave sensor and to regulate it to a predetermined mass flow. The experimental investigations were carried out with a screw dosing device FVS 3111. Two scenarios were tested: on the one hand, the integration of the sensor directly at the product delivery point, whereby the difference of the average value of the dosed quantity to the target weight could be improved with the sample product coffee; on the other, the sensor was integrated directly at the beginning of the screw and the remaining product flow was simulated. A reduction of the standard deviation compared with the conventional control could also be achieved, but here, the difference between the average of the dosed quantity and the nominal quantity is greater. The cause is presumed to be the too generalized assumption of product behaviour in the case of vertical conveying by means of a screw. In summary, the dosing accuracy of a screw dosing device could be increased by measuring and regulating the mass flow and thus the costs of a manufactured packaging could be reduced.
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Étude des paramètres affectant le transfert d'oxygène dans les vinsChiciuc, Igor 07 December 2010 (has links)
La micro-oxygénation des vins, par la dispersion de bulles d’oxygène, est une pratique de plus en plus utilisée dans le domaine de l’œnologie. Cette technique n’est pas toujours convenablement maitrisée par manque de connaissances scientifiques sur les paramètres régissant le transfert de l’oxygène. La recherche s'est focalisée sur l'étude des coefficients de transfert en fonction des composés du vin (CO2, éthanol, sucrose, consommateurs d’oxygène) et des conditions opératoires (type de diffuseur, température, rapport entre hauteur et diamètre du contenant de liquide). Les résultats montrent que lors de la micro-oxygénation, le dioxyde de carbone dissous et le sucrose ont une incidence négative sur le transfert alors que la présence d’éthanol améliore le transfert. En ce qui concerne les conditions opératoires, l’augmentation de débit de gaz et l’augmentation de rapport entre la hauteur et le diamètre de la cuve de micro-oxygénation joue positivement sur le transfert d’oxygène La surface spécifique des bulles et le coefficient de transfert de matière ont pu être dissociés pour les vins. La nature tensio-active des composés du vin semble être un élément important sur le transfert de matière. Les connaissances acquises ont été appliquées à la micro-oxygénation au cours de deux étapes de l'élaboration des vins : la fermentation alcoolique avec la maitrise de l’apport d’oxygène et la simulation de la technique d’élevage en barrique par micro-oxygénation couplée à l’ajout de copeaux de bois. Une nouvelle approche concerne l'étude d'un contacteur membranaire qui permet le transfert d’oxygène par diffusion. / Micro-oxygenation of the wines, by the dispersion of oxygen bubbles, is a practice increasingly used in oenology. This technique is not always suitably controlled for lack of scientific knowledge on the parameters governing the transfer of oxygen. Research was focused on the study of transfer coefficients in function of wine components (CO2, ethanol, sucrose, consuming oxygen) and of operating conditions (type of diffuser, temperature, relationship between height and diameter of the container of liquid). The results show that during micro-oxygenation, the dissolved carbon dioxide and the sucrose have a negative incidence on the transfer whereas the presence of ethanol improves the transfer. As operating conditions are concerned, the increase in gas output and the increase in micro-oxygenation tank height/diameter ratio positively influence oxygen transfer. For wines, the specific surface of the bubbles and the mass transfer coefficient could be dissociated. The surfactant nature of wine components seems to be the most important factor in mass transfer. The knowledge so acquired was applied to micro-oxygenation during two stages of wine making: alcoholic fermentation with the oxygen yield control and the simulation of ageing technique in barrels coupled with the wood chips addition. A new approach relates to the study of a membrane contactor application allowing the oxygen transfer by diffusion.
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Effet du réchauffement climatique sur le fonctionnement biogéochimique de deux cryosols arctiques dans la région de Salluit, Nunavik, Canada / Global warming impacts on the biogeochemical functioning of two arctic cryosols in the Salluit region, Nunavik, CanadaFouché, Julien 17 March 2014 (has links)
L'augmentation de la décomposition de la matière organique des cryosols arctiques sous l'effet du réchauffement et de la dégradation du pergélisol contribuerait à une rétroaction positive sur les changements climatiques. Nous étudions le fonctionnement biogéochimique de deux Cryosols: un cryosol histique (H) et un cryosol turbique (T), en conditions naturelles et réchauffés. Les profils ont été instrumentés à Salluit (Nunavik, Canada) et les mesures ont été faites pendant les étés 2010 et 2011. Le réchauffement augmente la respiration de l'écosystème (ER) de manière plus intense pour H que pour T, bien que ER pour H soit plus faible. La sensibilité thermique de ER (Q10) est supérieure pour T que pour H et diminue avec le réchauffement. L'étude montre que les cycles journaliers de ER en fonction de la temperature forment des hystérésis. La variance de ER est mieux expliquée en utilisant la température minimale de la journée et la profondeur du front de dégel pour H. Pour T, l'ajout de la vitesse du vent et la radiation solaire améliore l'explication de la variance de ER. Nous montrons trois dynamiques spécifiques aux écosystèmes nordiques: 1) ER dépendant des propriétés du sol et de la solution du sol ; 2) rôle de variables thermo-indépendantes sur ER et 3) variations journalières du Q10 et interannuelles de la respiration basale. La décomposition de la matière organique est la principale source de CO2 pour H alors que les processus végétaux contrôlent ER pour T. Nos résultats contribuent à la compréhension et à l'extrapolation des mesures ponctuelles dans les écosystèmes de toundra, améliorant ainsi la modélisation du cycle du carbone dans les cryosols. / Increased organic mater decomposition rate in Arctic Cryosols due to warming and to permafrost thawing can lead to the release of greenhouse gases, thus potentially creating a positive feedback on climate change. We studied the biogeochemical functioning of two different permafrost-affected soils (i.e. Cryosols): a Histic Cryosol (H) and a Turbic Cryosol (T), both in natural conditions and under an experimental warming. Profiles were instrumented in Salluit (Nunavik, Canada) and monitored during summers 2010 and 2011. The induced warming increased CO2 fluxes in both soils; this impact was however more striking at H even if ER was lower than at T. Temperature sensitivity of ER (Q10) was higher at T than at H and decreased both with warming. We highlighted that diurnal ER cycles as a function of temperature showed hysteretic loops. Linear models performed to explain ER variance were improved adding daily minimum temperature and thaw front depth at H. In contrast at T, adding wind speed and solar radiation in models improved the ER variance explanation. We showed three specific CO2 flux dynamics related to northern ecosystems: 1) the large difference of ER depending on soil properties and soil solution composition; 2) environmental variables strongly alter CO2 fluxes and 3) the diurnal Q10 variations and the inter annual variability of basal respiration. Our results support the assumption that organic matter decomposition might be the major source of CO2 at H while plant-derived processes dominated ER at T. Our results contribute to understand and extrapolate the numerous punctual measurements of CO2 fluxes from tundra ecosystems improving carbon cycle modeling in Cryosols.
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Étude des réseaux neuronaux et des mécanismes cognitifs impliqués dans les déficiences intellectuelles liées au chromosome X / Study of neuronal networks and cognitive mecanisms involved in X linked intellectual disabilityCurie, Aurore 08 April 2011 (has links)
Grâce aux progrès de la génétique moléculaire qui ont permis d’identifier de nouveaux gènes de déficience intellectuelle liée à l’X, il nous a été possible de travailler sur des groupes homogènes de malades présentant une mutation dans le même gène. Nous avons d’une part, pu mettre en évidence un dysfonctionnement du circuit cérébello-thalamo-préfrontal grâce à une étude en IRM morphométrique réalisée chez des patients ayant une mutation dans le gène Rab-GDI. D’autre part, nous avons identifié un phénotype tout à fait spécifique lié aux mutations du gène ARX, tant clinique que neuropsychologique, et cinématique, associant une atteinte très particulière de la motricité distale des membres supérieurs et du langage. La préhension des patients est pathognomonique, avec une préférence pour la pince pouce-majeur, une difficulté accrue pour l’utilisation du bord cubital de la main, et un trouble de la pronosupination. Sur le plan neuroanatomique, il existe une diminution de volume des noyaux gris centraux et des épaisseurs corticales des régions contrôlant la motricité, bien corrélées au paramètres de cinématique. Enfin, nous avons exploré les stratégies de raisonnement des patients déficients intellectuels atteints du syndrome de l’X fragile, d’une mutation du gène ARX ou de trisomie 21 en élaborant un paradigme de raisonnement visuel analogique issu des matrices de Raven. Nous en avons établi la trajectoire développementale. Les stratégies utilisées par les patients (étude en eyetracking) sont différentes de celles des contrôles y compris de même âge mental, avec un défaut d’inhibition majeur, encore plus franc chez les patients X fragiles que ceux porteurs de trisomie 21 / Thanks to progress in molecular genetics, that allowed identification of new genes responsible for X linked intellectual disability, we studied on homogeneous groups of patients presenting with a mutation in one or the other gene. In the first section, we showed dysfunction of cerebello-thalamo-prefrontal networks, thanks to morphological MRI study performed on patients with a mutation in the Rab-GDI gene. In the second section, we highlighted a very specific phenotype related to ARX gene mutations, clinically, neuropsychologically, and kinematically, with a very peculiar impairment of upper limbs distal motricity, and language disorder. Patients hand-grip is pathognomonic, with a preference for the middle finger instead of the index for the grip of object, major impairment of fourth finger use, and lack of pronation movements. Neuroimaging study showed decreased volume of basal ganglia, and cortical thickness of motor regions, well correlated to kinematic parameters. In the third section, we explored reasoning strategies in three groups of patients with intellectual deficiency: fragile X, ARX mutated and Down syndrome patients and controls (both chronological and mental age-matched subjects). We notably elaborated a visual analogical reasoning paradigm, inspired from Raven’s matrices. We established a developmental trajectory of this paradigm. The strategy used by patients (eyetracking study) was different from the one used by controls, with a huge lack of inhibition, even greater for fragile X patients than for Down syndrome patients
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Bacterial leaching from dairy shed effluent applied to a fine sandy loam under flood and spray irrigationsJiang, Shuang January 2008 (has links)
Land application of wastes has become increasingly popular, to promote nutrient recycling and environmental protection, with soil functioning as a partial barrier between wastes and groundwater. Dairy shed effluent (DSE), may contain a wide variety of pathogenic micro-organisms, including bacteria (e.g. Salmonella paratyphyi, Escherichia coli. and Campylobacter), protozoa and viruses. Groundwater pathogen contamination resulting from land-applied DSE is drawing more attention with the intensified development of the dairy farm industry in New Zealand. The purpose of this research was to investigate the fate and transport of bacterial indicator-faecal coliform (FC) from land-applied DSE under different irrigation practices via field lysimeter studies, using two water irrigation methods (flood and sprinkler) with contrasting application rates, through the 2005-2006 irrigation season. It was aimed at better understanding, quantifying and modelling of the processes that govern the removal of microbes in intact soil columns, bridging the gap between previous theoretical research and general farm practices, specifically for Templeton soil. This study involved different approaches (leaching experiments, infiltrometer measurements and a dye infiltration study) to understand the processes of transient water flow and bacterial transport; and to extrapolate the relationships between bacterial transport and soil properties (like soil structure, texture), and soil physical status (soil water potential ψ and volumetric water content θ). Factors controlling FC transport are discussed. A contaminant transport model, HYDRUS-1D, was applied to simulate microbial transport through soil on the basis of measured datasets. This study was carried out at Lincoln University’s Centre for Soil and Environmental Quality (CSEQ) lysimeter site. Six lysimeters were employed in two trials. Each trial involved application of DSE, followed by a water irrigation sequence applied in a flux-controlled method. The soil columns were taken from the site of the new Lincoln University Dairy Farm, Lincoln, Canterbury. The soil type is Templeton fine sandy loam (Udic-Ustochrept, coarse loamy, mixed, mesic). Vertical profiles (at four depths) of θ and ψ were measured during leaching experiments. The leaching experiments directly measured concentrations of chemical tracer (Br⁻ or Cl⁻) and FC in drainage. Results showed that bacteria could readily penetrate through 700 mm deep soil columns, when facilitated by water flow. In the first (summer) trial, FC in leachate as high as 1.4×10⁶ cfu 100 mL⁻¹ (similar to the DSE concentration), was detected in one lysimeter that had a higher clay content in the topsoil, immediately after DSE application, and before any water irrigation. This indicates that DSE flowed through preferential flow paths without significant treatment or reduction in concentrations. The highest post-irrigation concentration was 3.4×10³ cfu 100 mL⁻¹ under flood irrigation. Flood irrigation resulted in more bacteria and Br⁻ leaching than spray irrigation. In both trials (summer and autumn) results showed significant differences between irrigation treatments in lysimeters sharing similar drainage class (moderate or moderately rapid). Leaching bacterial concentration was positively correlated with both θ and ψ, and sometimes drainage rate. Greater bacterial leaching was found in the one lysimeter with rapid whole-column effective hydraulic conductivity, Keff, for both flood and spray treatments. Occasionally, the effect of Keff on water movement and bacterial transport overrode the effect of irrigation. The ‘seasonal condition’ of the soil (including variation in initial water content) also influenced bacterial leaching, with less risk of leaching in autumn than in summer. A tension infiltrometer experiment measured hydraulic conductivity of the lysimeters at zero and 40 mm suction. The results showed in most cases a significant correlation between the proportion of bacteria leached and the flow contribution of the macropores. The higher the Ksat, the greater the amount of drainage and bacterial leaching obtained. This research also found that this technique may exclude the activity of some continuous macropores (e.g., cracks) due to the difference of initial wetness which could substantially change the conductivity and result in more serious bacterial leaching in this Templeton soil. A dye infiltration study showed there was great variability in water flow patterns, and most of the flow reaching deeper than 50 cm resulted from macropores, mainly visible cracks. The transient water flow and transport of tracer (Br⁻) and FC were modelled using the HYDRUS-1D software package. The uniform flow van Genuchten model, and the dual-porosity model were used for water flow and the mobile-immobile (MIM) model was used for tracer and FC transport. The hydraulic and solute parameters were optimized during simulation, on the basis of measured datasets from the leaching experiments. There was evidence supporting the presence of macropores, based on the water flow in the post-DSE application stage. The optimised saturated water content (θs) decreased during the post-application process, which could be explained in terms of macropore flow enhanced by irrigation. Moreover, bacterial simulation showed discrepancies in all cases of uniform flow simulations at the very initial stage, indicating that non-equilibrium processes were dominant during those short periods, and suggesting that there were strong dynamic processes involving structure change and subsequently flow paths. It is recommended that management strategies to reduce FC contamination following application of DSE in these soils must aim to decrease preferential flow by adjusting irrigation schemes. Attention needs to be given to a) decreasing irrigation rates at the beginning of each irrigation; b) increasing the number of irrigations, by reducing at the same time the amount of water applied and the irrigation rate at each irrigation; c) applying spray irrigation rather than flood irrigation.
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Analysis of Hyperelastic Materials with Mechanica - Theory and Application ExamplesJakel, Roland 03 June 2010 (has links) (PDF)
Part 1: Theoretic background information
- Review of Hooke’s law for linear elastic materials
- The strain energy density of linear elastic materials
- Hyperelastic material
- Material laws for hyperelastic materials
- About selecting the material model and performing tests
- Implementation of hyperelastic material laws in Mechanica
- Defining hyperelastic material parameters in Mechanica
- Test set-ups and specimen shapes of the supported material tests
- The uniaxial compression test
- Stress and strain definitions in the Mechanica LDA analysis
Part 2: Application examples
- A test specimen subjected to uniaxial loading
- A volumetric compression test
- A planar test
- Influence of the material law
Appendix
- PTC Simulation Services Introduction
- Dictionary Technical English-German / Teil 1: Theoretische Hintergrundinformation
- Das Hookesche Gesetz für linear-elastische Werkstoffe
- Die Dehnungsenergiedichte für linear-elastische Materialien
- Hyperelastisches Material
- Materialgesetze für Hyperelastizität
- Auswählen des Materialgesetzes und Testdurchführung
- Implementierung der hyperelastischen Materialgesetze in Mechanica
- Definieren der hyperelastischen Materialparameter in Mechanica
- Testaufbauten und Prüfkörper der unterstützten Materialtests
- Der einachsige Druckversuch
- Spannungs- und Dehnungsdefinition in der Mechanica-Analyse mit großen
Verformungen
Teil 2: Anwendungsbeispiele
- Ein einachsig beanspruchter Prüfkörper
- Ein volumetrischer Drucktest
- Ein planarer Test
- Einfluss des Materialgesetzes
Anhang:
- Kurzvorstellung der PTC Simulationsdienstleistungen
- Wörterbuch technisches Englisch-Deutsch
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