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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.
401

Effet de la concentration en solide sur les performances de séparation d'un hydrocyclone (simulations numériques et expériences de références) / Understanding the effect of solids concentration on hydrocyclone performance (CFD and experiment)

Davailles, Aurélien 21 November 2011 (has links)
L'exploitation minière des sables bitumineux requiert une succession de nombreuses opérations pour séparer le bitume, l'eau et le sable. La séparation solide/liquide fait intervenir un hydrocyclone. Afin de limiter l'ajout d'eau, l'hydrocyclone doit fonctionner dans des conditions inhabituelles correspondant à une concentration élevée à l'alimentation. Une étude expérimentale a permis de caractériser l'ensemble des régimes de fonctionnement, l'influence de la concentration et des caractéristiques géométriques. De plus, des simulations numériques ont été réalisées avec NEPTUNE_CFD@Tlse. Deux méthodes sont proposées pour modéliser les comportements observés à faible et à forte concentration. Les résultats numériques sont en bon accord avec les expériences sur toute la gamme de concentration. L'étude des phénomènes locaux permet une meilleure compréhension des mécanismes de séparation. / Tar sands beneficiation requires a series of processing steps for separation of bitumen, water and sand particles. In this process, hydrocyclones are used to separate sand from water and bitumen, thereby recovering additional bitumen and concentrating sand particles before sending them off to tailing ponds. In order to reduce fresh water consumption (environmental policy), hydrocyclones need to operate with high feed solids content, say 50% in mass, which lays outside their standard operating regime. The response and performance of hydrocyclones need to be understood under such stringent operating conditions. A pilot scale experiment was commissioned for testing a 100mm diam. hydrocyclone under different operating regimes of discharge and measuring the corresponding separation performance. Feed solids concentration and geometrical properties were varied extensively. Separation performance indicators, including partition curve, cut-size, sharpness index and water recovery to underflow were obtained by standard data reconciliation. The experimental data provided all the information required to test the CFD model that was derived to simulate the hydrocyclone. Eulerian simulations of the three-dimensional liquid-solid flow inside the hydrocyclone were carried out, using a multi-fluid model (NEPTUNE_ CFD@Tlse). The actual geometrical features and operating conditions of the hydrocyclone were accurately matched in the simulations. Two simulation approaches have been proposed for hydrocyclone modelling, depending on their operating under dilute conditions, with a spray discharge or dense conditions, with a rope discharge. Numerical simulation results are in good agreement with experiments. Local analysis of hydrodynamic features yields new insights into the behaviour of hydrocyclones at high feed solids concentration.
402

Reologické vlastnosti vazelíny bílé / Rheological properties of White Soft Paraffin

Hánová, Anna January 2015 (has links)
CHARLES UNIVERSITY IN PRAGUE Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical technology Name of the student: Anna Hánová Title of diploma thesis: Rheological properties of White Soft Paraffin Consultant: PharmDr. Eva Šnejdrová, Ph.D. This diploma thesis deals with the evaluation of consistency and rheological properties of the Soft Paraffin after viscosity modification by either Liquid or Solid Paraffin. The theoretical part focuses the characteristics and application of the hydrocarbon excipients, their use in pharmacy and comparison with other substances, rheological properties of semisolids and their consistency. Consistency by penetrometry according the Czech Pharmacopoeia 2009 and rheological properties using Kinexus rheometer were measured. Consistency of Soft Paraffin was significantly influenced with 5 % of Liquid Paraffin and 10 % of Solid Paraffin. The result of consistency assessment is significantly influenced by the method of the samples preparation. Rheograms and viscosity curves was constructed. Plastic systems were described in detail by the parameters of power law model and yield stress value. The addition of 5 % of Liquid Paraffin to the Soft White Paraffin caused the decrease of the coefficient of consistency and the flow index. A further addition of Liquid...
403

Stanovení konzupmčních křivek na vybraných hydrologicých profilech KFGG / Assessment of rating curves on selected hydrological profiles of the KFGG

Kabelka, Tomáš January 2016 (has links)
This thesis deals with the creation of rating curves and evaluating these curves on profiles KFGG. There are described various methods of extrapolating discharge beyond instrumentally measured data. On selected profiles is performed extrapolation using 1D hydrological model MIKE 11. Data used in this work are obtained by field survey made by workers KFGG. Key words: rating curve, extrapolation, hydrological modeling, ADCP, MIKE 11
404

Světelné křivky zákrytových dvojhvězd / The light curves of eclipsing binaries

Korda, David January 2016 (has links)
New CCD photometric observations of ten short-period LMB (Low Mass Binaries) were carried out. Data were obtained using 65 cm telescope in Ondřejov in the filters I, R and V from 2014 to 2016. Light curves were analysed using the program PHOEBE. The obtained masses and radii of the stars were compared with the theoretical mass-radii relation. There arises that the short-period binaries have the radii of about 4 % larger than the theoretical prediction from the stellar evolution models. Powered by TCPDF (www.tcpdf.org)
405

Algorithme de reconnaissance visuelle d’intentions : application au pilotage automatique d’un fauteuil roulant / Visual intention detection algorithm for wheelchair motion

Luhandjula, Thierry 10 July 2012 (has links)
Dans cette thèse, nous proposons une approche méthodologique et algorithmique pour la reconnaissance visuelle d'intentions, basée sur la rotation et le mouvement vertical de la tête et de la main. Le contexte dans lequel cette solution s'inscrit est celui d'une personne handicapée, dont la mobilité est assurée par un fauteuil roulant. Le système proposé constitue une alternative intéressante aux interfaces classiques de type manette, boutons pneumatiques, etc. La séquence vidéo, composée de 10 images, est traitée en utilisant différentes méthodes pour construire ce qui dans cette thèse est désigné par « courbe d'intention ». Une base de règles est également proposée pour classifier chaque courbe d'intention. Pour la reconnaissance basée sur les mouvements de la tête, une approche utilisant la symétrie du visage est proposée pour estimer la direction désirée à partir de la rotation de la tête. Une Analyse en Composantes Principales (ACP) est utilisée pour détecter l'intention de varier la vitesse de déplacement du fauteuil roulant, à partir du mouvement vertical de la tête. Pour la reconnaissance de la direction basée sur la rotation de la main, une approche utilisant à la fois la symétrie verticale de la main et un algorithme d'apprentissage (réseaux neuronaux, machines à vecteurs supports ou k-means), permet d’obtenir les courbes d'intentions exploitées par la suite pour la détection de la direction désirée. Une autre approche, s’appuyant sur l'appariement de gabarits de la région contenant les doigts, est également proposée. Pour la reconnaissance de la vitesse variable basée sur le mouvement vertical de la main, deux approches sont proposées. La première utilise également l'appariement de gabarits de la région contenant les doigts, et la deuxième se base sur un masque en forme d'ellipse, pour déterminer la position verticale de la main. Les résultats obtenus montrent de bonnes performances en termes de classification aussi bien des positions individuelles dans chaque image, que des courbes d'intentions. L’approche de reconnaissance visuelle d’intentions proposée produit dans la très grande majorité des cas un meilleur taux de reconnaissance que la plupart des méthodes proposées dans la littérature. Par ailleurs, cette étude montre également que la tête et la main en rotation et en mouvement vertical constituent des indicateurs d'intention appropriés / In this thesis, a methodological and algorithmic approach is proposed, for visual intention recognition based on the rotation and the vertical motion of the head and the hand. The context for which this solution is intended is that of people with disabilities whose mobility is made possible by a wheelchair. The proposed system is an interesting alternative to classical interfaces such as joysticks and pneumatic switches. The video sequence comprising 10 frames is processed using different methods leading to the construction of what is referred to in this thesis as an “intention curve”. A decision rule is proposed to subsequently classify each intention curve. For recognition based on head motions, a symmetry-based approach is proposed to estimate the direction intent indicated by a rotation and a Principal Component Analysis (PCA) is used to classify speed variation intents of the wheelchair indicated by a vertical motion. For recognition of the desired direction based on the rotation of the hand, an approach utilizing both a vertical symmetry-based approach and a machine learning algorithm (a neural network, a support vector machine or k-means clustering) results in a set of two intention curves subsequently used to detect the direction intent. Another approach based on the template matching of the finger region is also proposed. For recognition of the desired speed variation based on the vertical motion of the hand, two approaches are proposed. The first is also based on the template matching of the finger region, and the second is based on a mask in the shape of an ellipse used to estimate the vertical position of the hand. The results obtained display good performance in terms of classification both for single pose in each frame and for intention curves. The proposed visual intention recognition approach yields in the majority of cases a better recognition rate than most of the methods proposed in the literature. Moreover, this study shows that the head and the hand in rotation and in vertical motion are viable intent indicators
406

H-reflex při provádění pasivních pohybů / H reflex during pasive movements

Borský, Ondřej January 2012 (has links)
Title: Motoneuron excitability depending on the level of muscle stretch Aim: The aim of this thesis is to evaluate if passive muscle lenght change may influence parameters of H - reflex of soleus muscle Method: Tibial nerve stimulation in the fossa poplitea area was performed on 6 persons while passive stretching or lengthening of the muscle. Action potentials were captured on soleus muscle. Stimulation was performed in three different time periods - 4s, 2s, 1s. Each period was performed twice. First in passive muscle stretching then the passive shortening. The Hmax and Mmax values during passive muscle stretching and shortening were evaluated and compared. Results: The measurment results showed that there was a significant decrease in the Hmax values during passive muscle stretching. Mmax values were evaluated as passive muscle length change independent. Keywords: EMG, recruitment curve, H-reflex, M-wave, m.soleus, excitability
407

Vlastnosti a aplikace ploch nízkého stupně / Properties and applications of low degree surfaces

Mirová, Aneta January 2011 (has links)
My thesis "Properties and applications of low degree surfaces" deals mainly with properties of two quadrics. We introduce so called canonical forms of two quadrics and classification of intersection curve of two quadrics. There are used index and signature sequence to obtain classification of intersection curve of two quadrics. These sequence can determine the number of component of the intersection curve, their algebraic degrees and singularities. Our work also contains many examples with pictures. One part of the thesis also presents possible application of intersection curve of two quadrics in practice. This thesis also contains an enclosed CD, with the thesis in an electronic form and the source files of all pictures in the thesis.
408

Křivky s konstantní šířkou / Curves of constant width

Němec, Miroslav January 2013 (has links)
Title: Curves of constant width Author: Miroslav Němec Department: Department of Mathematics Education Supervisor: RNDr. Antonín Slavík, Ph.D., Department of Mathematics Education Abstract: The aim of this thesis is to familiarize the reader with the notion of the width of a given plane curve, and with curves having the same width in all directions. We focus our attention especially on those curves that are constructible using straightedge and compass. The chapters presenting the definition and measurement of curve width, as well as the construction of curves from circular arcs, are accessible to high-school students. We also briefly mention other related topics, such as the solids of constant width. Keywords: Width of a curve, constant width, construction, properties
409

Náborová křivka H-reflexu v diagnostice pseuradikulárních syndromů / Recruitment curve of H reflex in diagnostics of pseudoradicular syndrom

Vocilka, Jindřich January 2013 (has links)
Title: Recruitment curve of H-reflex in diagnostics of non-radicular syndroms Objectives: The main objective of this work is to verify the conductivity of nerve structures examination recruitment curves H-reflex and M-wave in the EMG examination in probands with non-radicular syndrome L5/S1. Methods: We tested 12 probands clinical trial diagnosed with non-radicular syndrome L5/S1. The test sample was compared with an equally large group of control probands. H-reflex of m.soleus was examined by bipolar stimulation in the fossa poplitea of tibial nerve. The results of an electromyographic examination was evaluated to asymptomatic and symptomatic side. Amplitude of H-reflex and M-wave, slope of recruitment curve, peaks of recruitment curves for the H-reflex and M-wave and the ratio Hmax / Mmax were evaluated and statistically compared. Results: Results of non-radicular syndrome L5/S1showed no significant change in the H-reflex. Due to this result we can suggests that there is no damage in nerve fibres in patients with non-radicular syndrome. Keywords: non-radicular syndrome, H-reflex, M-wave, recruitment curve
410

Hystereze nezaměstnanosti v České republice / Unemployment hysteresis in the Czech Republic

Bechný, Jakub January 2016 (has links)
This thesis presents an empirical analysis of the unemployment hysteresis in the Czech Republic on quarterly data from 1999 to 2015. The hysteresis is modelled by allowing for: (i) impact of the cyclical unemployment on the NAIRU; (ii) impact of the long-term un- employment on the NAIRU. Models are written in state space form and estimated using Bayesian approach. The main contributions of this thesis are as follows. The results pro- vide robust evidence in favour of the hysteresis in the Czech Republic, but precise size of the hysteresis effect is surrounded by relatively large uncertainty. Posterior mean estimates of key parameters indicate that in response to increase in the cyclical unemployment of 1 percentage point, the NAIRU increases by 0.15 percentage points. The first specification of the hysteresis implies that the hysteresis induced changes in the Czech Republic's NAIRU of at most 1 percentage point. The hysteresis specified as impact of the long-term unemploy- ment on the NAIRU then implies even weaker effect, inducing changes in the NAIRU of at most 0.6 percentage points. The models are estimated jointly with the hybrid Phillips curve identified using survey forecasts as proxies for the expectations. Estimate of the expecta- tions' parameter 0.65 indicates the forward-looking nature of the Czech...

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