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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.
41

Transfer matrix analysis of an electrohydraulically driven rotary- vibratory drilling system

Ohanehi, Donatus Chukwubueze 09 June 2010 (has links)
This research develops transfer matrix model for the longitudinal vibratory component of a rotary-vibratory drilling (RVD) system driven with an electrohydraulic inertial mass exciter. The RVD system is a hybrid drilling system consisting of a conventional rotary drilling system assisted by forced harmonic vibrations. The model includes a drill string with continuously distributed inertia, stiffness, internal material, and external fluid damping. These properties were introduced through a new continuum transfer matrix for a damped pipe element. The model allows for the inclusion of realistic geometrical representations for the drill string, and the inclusion of masses, springs, dashpots, and other axial structural elements. The force exerted on the drill string by the drilling fluid was included using the theory of a flat plate oscillating in a newtonian fluid. The force had an inertia and a viscous damping component. These were incorporated into the inertia and external fluid damping terms in the new continuum transfer matrix. The exciter had force and power limits. The rock-rock bit boundary was represented as a structurally damped spring. / Ph. D.
42

Experimental Evaluation of JP-8-Based Fire Resistant Fuels

Dress, Jason Michael 20 January 2011 (has links)
The Army's Fire Resistant Fuel (FRF) program is currently being used to defend against the threat of vehicle fuel fires resulting from unconventional warfare encountered in the Middle East. Fire Resistant Fuels are based upon JP-8, which is now the primary fuel for the Army ground services. The goal of FRF development is to reduce susceptibility to ignition at standard storage conditions while still serving as a fuel for the Army's diesel vehicles. Two preliminary tests were conducted to narrow down a field of candidates developed by Luna Innovations to a final set of five FRF. Dynamometer testing was used to determine peak power of the supplied Yanmar 2V750 engine. Fuel fire resistance characteristics were defined and compared using a rotating disk anti-misting characterization system. Fuels were characterized based upon spray characteristics including velocity and droplet diameter as well as through ignition testing. For these tests, FRF were compared to Diesel and Jet-A results. Results from this testing has shown that two fuels, both JP-8 emulsions, met the basic criteria of a fire resistant fuel. Engine testing trends showed that both fuels surpassed the peak power output of Diesel. Rotary atomization ignition testing resulted in no ignition for both fuels. As a supplementary study, cone calorimetry testing was performed to determine effective heats of combustion. Results from experimentation demonstrated that the energy content of the FRF is not of primary importance to engine performance or flame resistance. All data, analysis and trends are located in the appendices. / Master of Science
43

Caracterização da geometria e do funcionamento do conceito do motor rotativo de palhetas

Tessaro, Ioannes Paulus Bohn January 2012 (has links)
O conceito de um motor rotativo de palhetas é apresentado e o modelo que opera similar aos motores recíprocos dois tempos é analisado. Este motor é formado por estator cilíndrico, rotor descentralizado, palhetas radiais e tampas laterais, similar aos compressores de palhetas radiais. Parâmetros geométricos estão definidos para que o motor possua características similares a dois motores recíprocos comerciais igualmente modelados. Suas geometrias estão detalhadas, assim como a modelagem termodinâmica e suas hipóteses, as quais devido ao caráter comparativo do trabalho não têm grande influência no alcance dos objetivos. Em relação aos motores recíprocos, o novo conceito prospecta algumas vantagens: maior compacidade; menor nível de vibrações; maior facilidade de alteração da razão de compressão; possibilidade de produção e montagem em módulos; e devido a todas estas, as maiores possibilidades para o projeto, fabricação, montagem e operação dos motores. Para melhor entendimento de algumas tendências relativas a estas vantagens, a sensibilidade dos parâmetros geométricos é estudada, com variações nos diâmetros do estator e do rotor, na espessura do rotor e das palhetas, na excentricidade entre rotor e estator, e no número de palhetas do conceito. Este estudo demonstra características únicas do motor rotativo de palhetas, dentre elas, a variação da espessura do rotor se destaca por proporcionar a alteração do tamanho do motor sem modificar os demais aspectos. A excentricidade entre o rotor e estator demonstra grande potencial na capacidade de alterar a razão de compressão do equipamento, inclusive podendo ser modificada após a construção do motor ou até mesmo durante sua operação. Também se destaca o número de palhetas, o qual tem influência direta sobre a curva de torque do ciclo e a efetividade do posicionamento das janelas de admissão e exaustão. Com isto, é concluída a caracterização da geometria e do funcionamento do motor rotativo de palhetas, obtendo uma boa base para as próximas etapas de seu desenvolvimento. / The concept of a rotary vane engine is presented and the model that operates similar to twostroke reciprocating engines is analyzed. This engine is formed by a cylindrical stator, decentralized rotor, radial vanes and side housing plates, similar to the radial vane compressors. Geometrical parameters are defined so that the motor has similar characteristics to two commercial reciprocating engines also modeled. Their geometries are detailed, as well as the thermodynamic model and its assumptions, which due to the comparative nature of the work do not have significant influence in achieving the objectives. With respect to reciprocating engines, the new concept is prospecting some advantages: higher compactness; lowest level of vibration; ease of adjustment of compression ratio; possibility of manufacture and assembly in modules; and due to all these, the numerous possibilities to the design, manufacture, assembly and operation of the engines. For a better understanding of some these advantages trends, the sensitivity of geometric parameters are studied, with variations in the diameters of the stator and rotor, in the thickness of the rotor and the vanes, in the eccentricity between rotor and stator, and in the number of vanes of the concept. This study demonstrates unique rotary vane engine characteristics, among them, the range of rotor thickness stands out for providing a change in engine size without changing other aspects. The eccentricity between the rotor and stator shows great potential for the ability to change the compression ratio of the equipment and can be modified even after the construction or even during operation of the engine. It also highlights the number of vanes, which has a direct influence on the torque curve of the cycle and the effectiveness of the positioning of inlet and exhaust ports. Therewith, the characterization of rotary vane engine geometry and operational design is complete, obtaining a good basis for its next development stages.
44

Automatiserad provrörskarusell : Elektronikkonstruktion och utvärdering / Automated sample tube mover

Rosenfeld, Carl January 2010 (has links)
<p>Den här rapporten beskriver arbetet med en automatiserad provrörsförflyttare. Det är ett examensarbete som har gjorts på företaget Q-linea AB. En karuselliknande konstruktion med en stegmotor användes för att flytta prover mellan ett antal positioner. En mikrokontroller som hanterar styrning och sensordata har programmerats i C. LabVIEW och en USB-kamera har använts som hjälp till att göra utvärderingar och tester av systemet. Målet var att konstruera en prototyp som uppfyllde de precisionskrav och tidskrav som ställdes, vilket också uppnåddes. Rapporten beskriver arbetsgången och avslutas med rekommendationer för fortsatt arbete. Rapporten innehåller en teoridel som kan användas till hjälp för att konstruera liknande system, d.v.s. roterande positioneringstillämpningar.</p> / <p>This thesis describes the work of an automated sample tube mover. This is a degree project and has been done at the company Q-linea AB. A carousel similar construction with a stepper motor has been designed for the task to move samples between a numbers of positions. A microcontroller has been programmed to control the movements and handle sensor data. LabVIEW have been used together with an USB-camera in order to do evaluations and tests of the system. The goal was to design a prototype that fulfills the demanded requirements of precision and timing, which also was achieved. The thesis describes the work process and concludes with recommendations for further work.</p>
45

Automatiserad provrörskarusell : Elektronikkonstruktion och utvärdering / Automated sample tube mover

Rosenfeld, Carl January 2010 (has links)
Den här rapporten beskriver arbetet med en automatiserad provrörsförflyttare. Det är ett examensarbete som har gjorts på företaget Q-linea AB. En karuselliknande konstruktion med en stegmotor användes för att flytta prover mellan ett antal positioner. En mikrokontroller som hanterar styrning och sensordata har programmerats i C. LabVIEW och en USB-kamera har använts som hjälp till att göra utvärderingar och tester av systemet. Målet var att konstruera en prototyp som uppfyllde de precisionskrav och tidskrav som ställdes, vilket också uppnåddes. Rapporten beskriver arbetsgången och avslutas med rekommendationer för fortsatt arbete. Rapporten innehåller en teoridel som kan användas till hjälp för att konstruera liknande system, d.v.s. roterande positioneringstillämpningar. / This thesis describes the work of an automated sample tube mover. This is a degree project and has been done at the company Q-linea AB. A carousel similar construction with a stepper motor has been designed for the task to move samples between a numbers of positions. A microcontroller has been programmed to control the movements and handle sensor data. LabVIEW have been used together with an USB-camera in order to do evaluations and tests of the system. The goal was to design a prototype that fulfills the demanded requirements of precision and timing, which also was achieved. The thesis describes the work process and concludes with recommendations for further work.
46

Caracterização da geometria e do funcionamento do conceito do motor rotativo de palhetas

Tessaro, Ioannes Paulus Bohn January 2012 (has links)
O conceito de um motor rotativo de palhetas é apresentado e o modelo que opera similar aos motores recíprocos dois tempos é analisado. Este motor é formado por estator cilíndrico, rotor descentralizado, palhetas radiais e tampas laterais, similar aos compressores de palhetas radiais. Parâmetros geométricos estão definidos para que o motor possua características similares a dois motores recíprocos comerciais igualmente modelados. Suas geometrias estão detalhadas, assim como a modelagem termodinâmica e suas hipóteses, as quais devido ao caráter comparativo do trabalho não têm grande influência no alcance dos objetivos. Em relação aos motores recíprocos, o novo conceito prospecta algumas vantagens: maior compacidade; menor nível de vibrações; maior facilidade de alteração da razão de compressão; possibilidade de produção e montagem em módulos; e devido a todas estas, as maiores possibilidades para o projeto, fabricação, montagem e operação dos motores. Para melhor entendimento de algumas tendências relativas a estas vantagens, a sensibilidade dos parâmetros geométricos é estudada, com variações nos diâmetros do estator e do rotor, na espessura do rotor e das palhetas, na excentricidade entre rotor e estator, e no número de palhetas do conceito. Este estudo demonstra características únicas do motor rotativo de palhetas, dentre elas, a variação da espessura do rotor se destaca por proporcionar a alteração do tamanho do motor sem modificar os demais aspectos. A excentricidade entre o rotor e estator demonstra grande potencial na capacidade de alterar a razão de compressão do equipamento, inclusive podendo ser modificada após a construção do motor ou até mesmo durante sua operação. Também se destaca o número de palhetas, o qual tem influência direta sobre a curva de torque do ciclo e a efetividade do posicionamento das janelas de admissão e exaustão. Com isto, é concluída a caracterização da geometria e do funcionamento do motor rotativo de palhetas, obtendo uma boa base para as próximas etapas de seu desenvolvimento. / The concept of a rotary vane engine is presented and the model that operates similar to twostroke reciprocating engines is analyzed. This engine is formed by a cylindrical stator, decentralized rotor, radial vanes and side housing plates, similar to the radial vane compressors. Geometrical parameters are defined so that the motor has similar characteristics to two commercial reciprocating engines also modeled. Their geometries are detailed, as well as the thermodynamic model and its assumptions, which due to the comparative nature of the work do not have significant influence in achieving the objectives. With respect to reciprocating engines, the new concept is prospecting some advantages: higher compactness; lowest level of vibration; ease of adjustment of compression ratio; possibility of manufacture and assembly in modules; and due to all these, the numerous possibilities to the design, manufacture, assembly and operation of the engines. For a better understanding of some these advantages trends, the sensitivity of geometric parameters are studied, with variations in the diameters of the stator and rotor, in the thickness of the rotor and the vanes, in the eccentricity between rotor and stator, and in the number of vanes of the concept. This study demonstrates unique rotary vane engine characteristics, among them, the range of rotor thickness stands out for providing a change in engine size without changing other aspects. The eccentricity between the rotor and stator shows great potential for the ability to change the compression ratio of the equipment and can be modified even after the construction or even during operation of the engine. It also highlights the number of vanes, which has a direct influence on the torque curve of the cycle and the effectiveness of the positioning of inlet and exhaust ports. Therewith, the characterization of rotary vane engine geometry and operational design is complete, obtaining a good basis for its next development stages.
47

Caracterização da geometria e do funcionamento do conceito do motor rotativo de palhetas

Tessaro, Ioannes Paulus Bohn January 2012 (has links)
O conceito de um motor rotativo de palhetas é apresentado e o modelo que opera similar aos motores recíprocos dois tempos é analisado. Este motor é formado por estator cilíndrico, rotor descentralizado, palhetas radiais e tampas laterais, similar aos compressores de palhetas radiais. Parâmetros geométricos estão definidos para que o motor possua características similares a dois motores recíprocos comerciais igualmente modelados. Suas geometrias estão detalhadas, assim como a modelagem termodinâmica e suas hipóteses, as quais devido ao caráter comparativo do trabalho não têm grande influência no alcance dos objetivos. Em relação aos motores recíprocos, o novo conceito prospecta algumas vantagens: maior compacidade; menor nível de vibrações; maior facilidade de alteração da razão de compressão; possibilidade de produção e montagem em módulos; e devido a todas estas, as maiores possibilidades para o projeto, fabricação, montagem e operação dos motores. Para melhor entendimento de algumas tendências relativas a estas vantagens, a sensibilidade dos parâmetros geométricos é estudada, com variações nos diâmetros do estator e do rotor, na espessura do rotor e das palhetas, na excentricidade entre rotor e estator, e no número de palhetas do conceito. Este estudo demonstra características únicas do motor rotativo de palhetas, dentre elas, a variação da espessura do rotor se destaca por proporcionar a alteração do tamanho do motor sem modificar os demais aspectos. A excentricidade entre o rotor e estator demonstra grande potencial na capacidade de alterar a razão de compressão do equipamento, inclusive podendo ser modificada após a construção do motor ou até mesmo durante sua operação. Também se destaca o número de palhetas, o qual tem influência direta sobre a curva de torque do ciclo e a efetividade do posicionamento das janelas de admissão e exaustão. Com isto, é concluída a caracterização da geometria e do funcionamento do motor rotativo de palhetas, obtendo uma boa base para as próximas etapas de seu desenvolvimento. / The concept of a rotary vane engine is presented and the model that operates similar to twostroke reciprocating engines is analyzed. This engine is formed by a cylindrical stator, decentralized rotor, radial vanes and side housing plates, similar to the radial vane compressors. Geometrical parameters are defined so that the motor has similar characteristics to two commercial reciprocating engines also modeled. Their geometries are detailed, as well as the thermodynamic model and its assumptions, which due to the comparative nature of the work do not have significant influence in achieving the objectives. With respect to reciprocating engines, the new concept is prospecting some advantages: higher compactness; lowest level of vibration; ease of adjustment of compression ratio; possibility of manufacture and assembly in modules; and due to all these, the numerous possibilities to the design, manufacture, assembly and operation of the engines. For a better understanding of some these advantages trends, the sensitivity of geometric parameters are studied, with variations in the diameters of the stator and rotor, in the thickness of the rotor and the vanes, in the eccentricity between rotor and stator, and in the number of vanes of the concept. This study demonstrates unique rotary vane engine characteristics, among them, the range of rotor thickness stands out for providing a change in engine size without changing other aspects. The eccentricity between the rotor and stator shows great potential for the ability to change the compression ratio of the equipment and can be modified even after the construction or even during operation of the engine. It also highlights the number of vanes, which has a direct influence on the torque curve of the cycle and the effectiveness of the positioning of inlet and exhaust ports. Therewith, the characterization of rotary vane engine geometry and operational design is complete, obtaining a good basis for its next development stages.
48

CFD modelování toku partikulárních látek v rotační peci / CFD modelling of granular flow in rotary kiln

Slowik, Roman January 2020 (has links)
This work deals with modeling the flow of particulate matter in rotary kilns. For this purpose, a combined CFD and Discrete Element Method (DEM) model was used. Using Ansys Fluent software, several simulations were performed in order to determine the mean residence time and movement of the material in the rotary drum dryer. Results of the computational model were used to develop a regression model of the mean residence time and compared to the values as given by empirical equations. Furthermore, a simplified sensitivity analysis was performed for the selected input parameters of the model such as the stiffness constant, air mass flow rate and the particle size.
49

Nová řada kuličkových šroubů / New series of ball screws

Chalupa, Josef January 2016 (has links)
This thesis deals with construction of rotary-nut ball screw. In the first chapter technical research at the current state of linear positioning systems and matters associated with them is listed. The next chapter treats of basic concepts and designs referring to ball screws. Further on the boundary between rotary ball screw and rotary- nut ball screw is described. On basis of restrictions and selected criterions solution of one size of rotary – nut ball screw with all the calculations.
50

CFD Modelling of a Rotary Lime Kiln

Macphee, James January 2010 (has links)
McDonalds Lime Ltd, situated in Otorohanga, New Zealand, operate two dry process rotary lime kilns producing burnt and hydrated lime for a range of industries including agriculture, roading, water treatment, gold mining and steel making. The following Technology in Industry Fellowship (TIF) funded Masters Project is structured around investigating the combustion characteristics of Kiln Two at McDonald’s Lime Ltd using Computational Fluid Dynamics (CFD). Numerical results obtained using the commercial CFD code FLUENT were first validated against experimental data from the International Flame Research Foundation’s (IFRF) Furnace No.1. The validation study focussed on comparing the finite rate and mixture fraction/PDF approaches to combustion chemistry, as well as different methods for defining coal particle size distributions. Numerical modelling of Kiln Two at McDonald’s Lime Ltd began with full three-dimensional simulations, however due to their complexity and large computational times, two-dimensional axisymmetric models were primarily used for investigations. Comparisons were made between the two approaches. Investigations into the original pulverised coal fired system focussed on how the kiln aerodynamics and heat transfer properties were affected by changes to the coal and air inlet properties. The performance of a recently installed waste oil firing system was also investigated, with results showing that firing the kiln with a 25% thermal substitution of oil is the most efficient mode of operation. As the investigations focussed on the combustion characteristics the effects of the reacting limestone bed were ignored in all simulations. CFD modelling of the combustion characteristics within a large scale rotary kiln proved to be an extremely complex task. The work presented in this thesis has however provided some promising results which will ultimately assist McDonalds Lime Ltd in reducing their operating costs and environmental impact. Futhermore, the project has laid the foundation for further investigations.

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