• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 610
  • 285
  • 141
  • 102
  • 93
  • 18
  • 18
  • 17
  • 14
  • 12
  • 10
  • 10
  • 9
  • 8
  • 8
  • Tagged with
  • 1532
  • 329
  • 205
  • 176
  • 131
  • 121
  • 113
  • 106
  • 90
  • 81
  • 80
  • 78
  • 71
  • 68
  • 66
  • 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.
721

Stabilizační 2D plošina pro digitální obrazový snímací systém / Two-axis Stabilized Aerial Photography Platform

Vácha, Lukáš January 2012 (has links)
This diploma thesis deals with design and realization of control board with controlling program for stabilization platform application. Thesis is splitted in to six parts. In first part of thesis are summarized required parameters and properties of proposed system together with explanation of necessary theoretical basics. In second part of thesis is made analysis of sensors which are designated for sensing necessary magnitudes. Namely then magnetometer, accelerometer, gyroscope. For every sensor is there made analysis of influence caused by parasitic effects. In conclusion of second part is made choice of concrete sensors by choosing sensory module. Third part deals with conception of mechanical solution. Fourth part of thesis deals with design and construction of control board and also with description of circuit functional blocks. This is followed with fifth part which describing program equipment of board with setting up sensory module. In last part of thesis are described conclusions of testing.
722

Posouzení stavu břehového území a návrh stabilizace na vybrané údolní nádrži / Assessment of state banks and a proposal for stabilizing the selected dam reservoir

Kroček, Tomáš January 2013 (has links)
This thesis covers the state assessment of the selected bank sections of dam reservoirs Vranov and Boskovice. Data used and processed in this thesis were acquired by visiting both sites several times in order to perform measurements and make photographic documentation. Futhermore, data on reservoirs' water levels from 2000-2011 provided by Povodí Moravy s.p. were used. In order to determine bank line regression, the above-mentioned data were processed using the Šlezingr's modification of the method of abrasion terminants determination. Results for dam reservoirs Vranov and Boskovice are then compared with results of dam reservoir Brno, which were produced by the author within the framework of his bachelor thesis using the same method. At the end of the thesis, the author presents several possible forms of stabilization and protection of disrupted banks of dam reservoirs, including their drawings.
723

Normál vlnové délky pro optické komunikace v pásmu C / Wavelength Standard for Optical Communication in C Band

Růžička, Bohdan January 2008 (has links)
The thesis presents design, development and realization of laser system with stabilized optical frequency which could become the basis of an etalon of wavelength for the telecommunication band of the near-infrared spectral region. Semiconductor DFB laser diode is used as a tunable source of radiation with narrow linewidth. Its optimum operation is ensured by especially designed current and temperature controller. The laser is prestabilized using FM spectroscopy technique to the passive Fabry-Perot cavity. This fast feed-back loop is able to improve spectral characteristics of the laser. The center frequency of the F.-P. cavity - the laser optical frequency is locked by a slow second feed-back loop to the absorption spectral line of acetylene 13C2H2 gas. The slow control loop is based on the third derivative spectroscopy technique. Relative stability at the level of 10E-12 was achieved.
724

Reaktivní zpracování polypropylénu / Reactive Modification of Polypropylene

Matláková, Jana January 2017 (has links)
The theoretical part describes the principles of the free-radical induced grafting and the influence of various parameters on the reactions course. The literature research summarizes the latest knowledge in the field of the reactive modification of polypropylene (PP), it is mainly focused on the PP modification using an unsaturated acid anhydrides. Theoretical part describes the various procedures and modification of technology in order to increase the grafting yield of maleation. The experimental part is determined by the influence of the stabilizers concentration, the peroxide structure, and the binary mixture of monomers on the grafting yield and the reaction course. In the first part, the critical stabilizers concentration was determined based on the experimentally obtained relationship between the grafting yield and the stabilizers concentration. A kinetic schema of grafting of MAH onto PP in the presence of stabilizers has been proposed and compared with the experimental results. The effect of the stabilizers on the extent of the undesirable b-scission was evaluated based on the melt flow rate (MFR) and the rheological curves of PP-g-MAH. In the second part, the effect of the peroxide structure and the concentration of reactants on the grafting yield of PP modification with MAH and itaconic anhydride (IAH) was observed. The initial grafting yield Rg has been experimentally determined and compared with a defined area of theoretical values of Rg. The extent of b-scission was significantly influenced by the structure and the concentration of peroxide, as shown by the results of MFR and the rheological curves of PP-g-MAH. The last part of the doctoral thesis is focused on the assessment of the combination of MAH and IAH as comonomers on the grafting yield. At first, the reference polymers were prepared using the solution polymerization of MAH, and IAH, and copolymerization of MAH with IAH. The reference polymers were analyzed by FTIR, DSC, WAXS to confirm the probable copolymerization of MAH and IAH. The dependence of the reaction enthalpy on the reaction time was observed using simulations of bulk polymerization of MAH, IAH and mixtures MAH and IAH "in situ" in isothermal calorimeter. PP was subsequently modified with a combination of MAH and IAH as comonomers in order to assess its effect on the grafting yield
725

Kvantifikační aspekty ortéz ve vztahu k distorzi hlezenního kloubu / Quantifying aspects of orthosis in relation to ankle sprain

Znášiková, Ivona January 2010 (has links)
Title: Quantifying aspects of orthosis in relation to ankle sprain Objectives: To detect whether various types of ankle bracing affect dynamic postural stability. Investigation of attenuation of vertical forces in different conditions. To determine range of motion for each orthosis. Methods: Monitoring of dynamic variables by piezoelectric measuring device - Kistler recording of dynamic changes. Mathematical modeling of damping characteristics and detected variables. Measuring of range of motion by goniometer with and without orthosis. Results: Results suggest, that bracing conditions have an effect on dynamic postural stability and orthosis limit range of motion. Attenuation of vertical forces is affected by using orthosis. Keywords: ankle instability, orthosis, mathematical modeling, stabilization
726

Korelace hodnocení funkčních posturálních testů se schopností aktivace břišní stěny měřenou pomocí digitálních tlakových senzorů / Correlation between clinical evaluation by functional postural tests and ability to activate abdominal wall measured by digital pressure sensors

Stříbrný, Martin January 2020 (has links)
The theoretical part of the diploma thesis describes the role of abdominal muscles in intra-abdominal pressure and the effect on postural stabilization. The issue of postural stabilization was analyzed in a physiological situation and frequent pathologies related with inadequate postural stabilization have been described. The current possibilities of evaluating the activity of abdominal muscles and intra-abdominal pressure were presented. Methodology: 25 healthy probands (mean age 22.4 years, SD ± 1.76) were evaluated in five posturally different situations - breathing stereotype test, intra-abdominal pressure regulation test, diaphragm test, hip flexion test and arm elevation test. Testing was performed with a prototype of the DNS Brace digital pressure sensor. The resulting pressure values of the abdominal wall expansion were correlated with the corresponding postural tests according to the DNS concept, which were performed by two DNS instructors with more than five years of experience. Results: A statistically significant correlation (p = 0.001 to 0.24) between abdominal wall pressure values and palpation-evaluated postural tests was demonstrated in four of the five tested positions. Correlation was strong in diaphragm test (r = 0.75 and 0.661) and mean in other tests (r = 0.567 to 0.415). Only...
727

Stabilization and comparison of manufacturing technologies for production of nano-crystalline suspensions / Stabilisation et comparaison des technologies de production des suspensions nanocristallines

Nakach, Mostafa 23 September 2016 (has links)
La faible taille des nanoparticules permet d’améliorer significativement la biodisponibilité des médicaments et faciliter leur administration par voie parentérale sous forme de particules sans risque de bouchage des vaisseaux sanguins. Cependant, cette faible taille peut être un facteur d’instabilité physique pendant le stockage ou/et pendant l’administration. Le principal défi lié à la fabrication des nano-suspensions réside dans leur stabilisation ainsi que dans le choix de la technologie appropriée pour leur fabrication. La présente thèse est centrée sur la stabilisation et la fabrication des suspensions nano-crystallines. Pour la partie formulation, la thèse décrit une approche systématique pour le choix des stabilisants. Ceux-ci peuvent être soit des dispersants ou soit une combinaison de dispersants et d’agents mouillant. La méthode proposée pour le criblage des stabilisants est rapide et efficace. Elle permet d’investiguer un grand nombre de stabilisant en se basant sur des principes physico-chimiques et en utilisant une approche étape par étape. Cette méthodologie a été divisée en deux parties : la première partie a été centrée sur un criblage qualitatif dont l’objectif est de sélectionner une tête de série à investiguer dans la seconde partie. La seconde partie est centrée sur un criblage quantitative qui a pour objectif d’optimiser le ratio est la quantité d’agent mouillant et de dispersant. Les résultats obtenus ont montré clairement que le système SDS/PVP 40/60 % (m/m) à la concentration de 1.2 % est le stabilisant optimum qui a permis de stabiliser la suspension à température ambiante. Par ailleurs, la robustesse de la formulation a été évaluée en mesurant l’agrégation sous cisaillement ainsi qu’en fonction de la force ionique, la température et du pH. Les résultats ont montré que la concentration critique de coagulation du système étudiée est cinq fois plus importante que celle décrite dans la littérature pour des nano-suspensions concentrées et stables. En revanche, l’agrégation des nanoparticules a été observée à haute température et à haut taux de cisaillement. Pour la partie développement du procédé de fabrication, la thèse est centrée sur la comparaison technologique de l’homogénéisation haute pression (HHP) par rapport au broyage à billes. L'impact de la formulation de la suspension, des paramètres du procédé et de la configuration technologique sur la qualité physique de la suspension produite par chacune des technologies ont été investigués. En outre, les deux technologies ont été comparées en termes de leur robustesse et de leur conformité à la réglementation pharmaceutique. Les conclusions principales de cette étude ont mis en évidence que le broyage à billes conduit à une suspension plus fine que celle obtenue par le HHP. De plus, il a été montré pour les 2 technologies que la relation d90 versus d50 est décrite par une seule courbe maîtresse indépendamment des paramètres du procédé et de l’échelle utilisée. Ceci a clairement mis en évidence que la HPH conduit à une distribution granulométrique plus resserrée que celle obtenue par broyage à billes. Finalement, nous avons modélisé le procédé de broyage à bille en adaptant les équations de Tanka et Chodakov. Le modèle conçu a permis un lissage précis des cinétiques de broyage ainsi que la simulation et la prédiction du procédé de broyage. / The small particle size of nano-crystalline suspension increases the bioavailability of water insoluble drug and facilitates their direct injection into the systemic circulation as particles. However, this small particle size can be responsible for their physical instability during storage and/or administration. The main challenges related to the production of nano-crystalline suspensions are to select the best stabilizer agent to ensure process-ability and to stabilize the API. Moreover, it is necessary to select the suitable technology for the suspension manufacturing taken into account the industrial constraints (scale-down/scale-up, process robustness and equipment reliability). The present thesis is focused on the formulation and the process development of nano-crystalline suspension. For the formulation part, we described a systematic approach to select optimum stabilizer for the preparation of nano-suspensions of given drug. The stabilizer can be either a dispersant or a combination of dispersant and wetting agents. The proposed screening method is a fast and efficient way to investigate a large number of stabilizers based on the principles of physical-chemistry and employs a stepwise approach. The methodology has been divided in two main parts; the first part focused on qualitative screening with the objective of selecting the appropriate candidate(s) for further investigations. The second part discussed quantitative screening with the objective of optimizing the ratio and the amount of wetting and dispersing agents. The results clearly showed that SDS/PVP as wetting/dispersing 40/60% (w/w) at a total concentration of 1.2% was the optimum stabilizer composition, at which the resulting nano-suspensions were stable at room temperature. Furthermore, the formulation robustness was assessed by measuring the rate of perikinetic, orthokinetic aggregation rate as a function of ionic strength (using NaCl), temperature and of pH variation. The results show that using the SDS/PVP mixture, the critical coagulation concentration is about five times higher than that observed in the literature for suspension colloidaly stable at high concentration. The nano-suspension was also found to be very stable at different pH conditions. Desorption test confirmed the high affinity between API and wetting/dispersing agent. However, the suspension undergoes aggregation at high temperature due to desorption of the wetting/dispersing agent and disaggregation of SDS micelles. Furthermore, aggregation occurs at very high shear rate by overcoming the energy barrier responsible for colloidal stability of the system. With respect to process engineering, a technological comparison (high pressure homogenization (HPH) versus bead milling) for the manufacturing of nano-suspension was carried out in terms of impact of suspension formulation, process parameters and technological configuration on the physical quality of the produced suspension. In addition both technologies were compared in terms of their robustness and their compliance to pharmaceutical regulations. The main findings are that, insofar the formulation is sufficiently robust and stable, both technologies are suitable for processing nano-crystalline suspensions. Bead milling is more powerful than HPH. It leads to a limit of milling (d50) lower than that obtained with HPH (100 vs 200 nm). In addition, for both technologies, one can observe that regardless, the process parameters used for milling and the scale, the relationship of d90 versus d50 could be described by a unique master curve (technology signature of milling pathway) outlining that the HPH leads to a tighten particle size distributions. Finally, a modelling approach based on adapted Tanka and Chodakov’s equation was proposed for modelling the milling kinetic. The generated model provides an accurate fit of milling kinetic, to predict and to simulate the milling manufacturing process.
728

Propuesta de solución de estabilización en un pavimento sustituyendo la capa granular espumada por una emulsionada para condiciones críticas en el proyecto de conservación vial Puno-Tacna, tramo Tarata-Capazo / Proposal of stabilization solution in a pavement that replaces the foamed granular layer with an emulsion for the thermodynamic conditions of the Puno-Tacna Road Conservation Project, Tarata-Capazo seccion

Sánchez Núñez, Joaquín Ernesto, Shoji Hirano, Naomi Patricia 30 July 2020 (has links)
Con la finalidad de lograr la estabilización de pavimentos, surgen nuevas tecnologías de agentes estabilizadores como el asfalto espumado y la emulsión asfáltica. En el Proyecto del corredor vial Dv-Humajalso-Desagüadero y Tacna-Capazo-Mazocruz, se tenía como solución técnica aplicar en el Tramo 7 Tarata-Capazo el asfalto espumado. Sin embargo, la condición termodinámica es fundamental para el asfalto espumado y esto se evidencia en el Tramo 7, donde a temperaturas de 5°C en descenso, las partículas de asfalto no se dispersan sobre el mástic, éstas caen sobre otras partículas de asfalto, provocando una aglomeración de asfalto en forma de chicles e imposibilitando la compactación de la capa del pavimento. Frente a esta problemática, se plantea estabilizar el material granular con emulsión asfáltica, donde las partículas de asfalto están dispersas en una solución acuosa a 25°C y no se requiere calentar al asfalto a elevadas temperaturas. El objetivo de la tesis es lograr la estabilización del pavimento utilizando emulsión asfáltica. Para el diseño de la mezcla asfáltica en frío, se utiliza la metodología Illinois y una emulsión catiónica de rotura lenta como ligante. Prosigue, el diseño del pavimento con la metodología AASHTO 93, para determinar los espesores de las capas del pavimento que satisfarán las cargas de tráfico para la vida útil del proyecto. Finalmente, se logra validar la estabilización del pavimento en campo con los controles de compactación y deflectometría, quedando demostrado la versatilidad de la emulsión como mezcla asfáltica en frío frente a las condiciones termodinámicas críticas del Proyecto. / In order to achieve the stabilization of pavements, emerge new technologies of stabilizing agents such as foamed bitumen and asphalt emulsion. In the Roadway Project Dv-Humajalso-Desagüadero and Tacna-Capazo-Mazocruz, the technical solution was to apply foamed bitumen in road Section 7 Tarata-Capazo. Thermodynamic condition is fundamental where foamed bitumen is evidenced in Section 7, the temperature is lower than 5 °C, so the asphalt don’t disperse on the Mastic, causing an agglomeration of asphalt in the form of chewing gum and making impossible the compaction of the pavement layer. In this problem, It’s proposed to stabilize the granular material with asphalt emulsion, so the asphalt particles are dispersed in a solution to 25°C. The technique is a mixture of cold asphalt and is feasible for the critical thermodynamic conditions of the Section 7 Tarata-Capazo. The objective is to achieve the stabilization of the pavement using asphalt emulsion. The design of the cold asphalt mix applies the Illinois Methodology to determine the optimum quantity of residual asphalt. So that, the design of the pavement is done with the methodology of AASHTO 93, which allows to determine the thicknesses of the pavement layers that will satisfy the serviceability and traffic for the useful life of the project. Finally, It´s possible to validate the stabilization of the pavement in the field with the compaction and deflectometry controls, demonstrating the versatility of the emulsion as a cold asphalt mixture against the critical thermodynamic conditions of the Project. / Tesis
729

Análisis de la optimización del suelo de la base con aditivo químico terrasil para el diseño de pavimentos industriales del almacén de concentrados mineros – Almacenes Logisminsa, Ventanilla – Callao / Analysis of the optimization of the base soil with terrasil chemical additive for the design of industrial flooring of the warehouse of mining concentrates - Almacenes Logisminsa, Ventanilla - Callao

Gutiérrez Rosales, Jessica Milagros, Ceron Rivera, Eduardo Cesar 12 July 2020 (has links)
Durante la ejecución de proyectos, el ingeniero civil se encuentra con diversos suelos en distintas zonas de construcción con problemas particulares; tales como, la presencia de suelos expansivos, una mala distribución granulométrica, también se encuentra los suelos con baja capacidad de soporte reflejados en el valor de CBR, entre otros. Frente a estas problemáticas, se plantean diversas soluciones como la estabilización de suelos ya sea por medios físicos y químicos. El presente estudio se realizará en el almacén Logisminsa de concentrados mineros, actualmente en construcción, ubicada en el distrito de Ventanilla. Cabe mencionar que este estudio se ha realizado con material de cantera, el cual cumple con los estándares de calidad de agregados vigentes para una base, con la excepción del valor de soporte del terreno CBR, siendo esta inferior al parámetro establecido por el manual de carreteras: suelos, geología y pavimentos, esto al tratarse de vehículos industriales, y además de presentar altas cargas concentradas y distribuidas por los concentrados mineros puede ocasionar daños en la losa de concreto lo que implicará un adicional de costo en el mantenimiento, reparación, tiempo de trabajo y horas máquinas. Por ello, se plantea la incorporación del aditivo químico Terrasil en distintos porcentajes de aplicación en la base del pavimento industrial del almacén de concentrados mineros Logisminsa con el fin de evaluar la influencia del aditivo químico en el valor del CBR, además en el espesor de losa al diseñar el pavimento industrial con cada porcentaje de adicción. / During the execution of projects, the civil engineer encounters various types of soils with particular problems in different construction areas; such as the presence of expansive soils, a poor particle size distribution, there are also soils with low bearing capacity reflected in the CBR value, among others. Faced with these problems, various solutions are proposed, such as soil stabilization by physical and chemical means. The investigation will be carried out in the Logisminsa mine concentrates warehouse, currently under construction, located in Ventanilla district. It is worth mentioning that this study has been carried out with quarry material, which complies with the quality standards of aggregates in force for a base, with the exception of the capacity of soil support through the CBR, this being less than the parameter established by the road manual: soils, geology and pavements, this when dealing with industrial vehicles and in addition to presenting high concentrated loads distributed by the mining concentrates, can cause damage to the concrete slab, which will imply an additional cost in maintenance, repair, working time and machine hours. For this reason, the incorporation of the chemical additive Terrasil in different percentages of application in the base of the industrial pavement of the Logisminsa mining concentrates warehouse is proposed in order to evaluate the influence of the chemical additive on the CBR value, in addition to the slab thickness when designing the industrial pavement with each percentage of addiction. / Tesis
730

Efektivita McGillovy metody při léčbě vertebrogenního algického syndromu. / Effectiveness of McGill method at therapy of vertebrogenic algic syndrom.

Vlasák, Martin January 2020 (has links)
Title: The effectiveness of McGill's method in the treatment of Vertebrogenic algic syndrome. Objectives: The goal of this thesis was to determine the applicability of McGill's method to patients with diagnoses, that are collectively referred to as Vertebrogenic algic syndrome by comparing the measured data of proband with different locations of diagnosis of Vertebrogenic algic syndrome in the Czech Republic. Methods: This is a pilot experimental research involving 10 probands diagnosed with Vertebrogenic algic syndrome in the cervical spine, 10 probands diagnosed with Vertebrogenic algic syndrome in the thoracic spine and 10 probands diagnosed with Vertebrogenic algic syndrome in the lumbar spine. Each participant underwent a kinesiological examination according to the McGill's principles together with a SF-36 questionnaire. Measured values were compared and provided a basis for testing the hypotheses. The thesis uses methods of research, observation, querying and comparison of collected data. Results: Using the statistical analysis of the measured data demonstrated a positive effect of the McGill's treatment in terms of reduced pain in probands suffering from Vertebrogenic algic syndrome in all investigated locations. Comparing the measured data of individual groups shown that the difference in...

Page generated in 0.1779 seconds