The dissertation thesis deals with optimization of the selected areas of the hydraulic system for small and medium transport aircrafts. Newly developed small aircraft EV-55 is a representative in the category of the small aircrafts . The selected areas of the hydraulic systems , important and useful for domestic producers of the hydraulic devices and whole hydraulic systems for the airplane EV-55 , are subjected to optimization efforts in the dissertation thesis. Design parameters of the hydraulic system (type of hydraulic source, level of pressure, weight of connecting tube), hydraulic devices ( tribology, machining process), simulation of the servomechanism and areas of diagnostic of technical status of the hydraulic system are optimized in the dissertation thesis.

Microseismic monitoring is an integral part of scientific experiments or industrial operations associated with the hydraulic fracturing of bedrock, which is an effort to increase the permeability of rocks in the area and improve the exploitation, whether of heat, oil or natural gas. Monitoring of such newly formed or growing original fractures, usually followed by seismic events, is very important for observation and describing the hydraulic fracturing itself and its progress over time. Since the number of such events recorded is usually very high, classical methods of earthquake processing, where the arrival times of seismic waves are determined manually, seem to be very inappropriate. For this reason, automatic methods are used to process such datasets, which do not require manual determination of the arrival times of the seismic waves. In our case, the data were recorded by a dense network of surface receivers arranged in the shape of a ten-arm star. It was a total of more than nine hundred groups of vertical geophones, of which more than a quarter were also supplemented by a three-component seismic sensor. We then created an automatic procedure for the described network, the result of which is the determination of the location and the source mechanism for each seismic event. The recorded...

Die Berücksichtigung der flächenhaften bodenhydraulischen Variabilität gilt bei der Modellierung von Wasser- und Stofftransportprozessen als problematisch. Dies liegt vorrangig an ihrer Erfassung, die kosten- und zeitintensiv ist. Die vorliegende Arbeit untersucht verschiedene Messstrategien, die zur Abbildung der flächenhaften Bodenhydraulik mit wenigen, einfach zu bestimmenden und physikalisch begründeten Bodenparametern führen. Die Vorgehensweise erfolgt mit der Anwendung eines Ähnlichkeitskonzeptes, das die Böden in bodenhydraulisch ähnliche Klassen unterteilt. Innerhalb einer Klasse kann die Variabilität der Retentions- und hydraulischen Leitfähigkeitcharakteristik auf einen freien Parameter (Skalierungsparameter) reduziert werden. Die Analyse der Zusammenhänge zwischen Boden- und Skalierungsparametern führt letztendlich zu den geeigneten Parametern die eine flächenhafte Abbildung möglich machen. Diese Untersuchungen bilden die Grundlage für die weitere Entwicklung eines stochastischen Modellansatzes, der die Variabilität der Bodenhydraulik bei der Modellierung des Bodenwassertransportes im Feldmaßstab berücksichtigen kann. An Hand von drei Datensätzen unterschiedlicher Skalenausbreitung konnte dieses Konzept angewendet werden. Die Ergebnisse zeigen, dass die Beschreibung der hydraulischen Variabilität nur für die vertikale (Profil) nicht aber für die flächenhafte Ausbreitung mit einfachen Bodenparametern möglich ist. Mit einer ersten Modellanwendung konnte gezeigt werden, dass über die Variabilität der Bodenparameter Trockenrohdichte und Tongehalt auch die Variabilität der Bodenhydraulik und damit die Berechnung des Bodenfeuchteverlaufs am Standort darstellbar ist. / The consideration of the spatial variability of the unsaturated soil hydraulic characteristics still remains an unsolved problem in the modelling of the water and matter transport in the vadose zone. This can be mainly explained by the rather cumbersome measurement of this variability, which is both, time-consuming and cost-intensive. The presented thesis analyses various measurement strategies which aim at the description of the soil-hydraulic heterogeneity by a small number of proxy-parameters, which should be easily measurable and still have a soil-physical meaning. The developed approach uses a similarity concept, which groups soils into similar soil hydraulic classes. Within a class, the variability of the retention and hydraulic conductivity curves can be explained by a single parameter (scaling parameter). The analysis of the correlation between the soil parameters and the scaling parameters can eventually indicate which soil parameters can be used for describing the soil hydraulic variability in a given area. This investigation forms the basis for the further development of a stochastic model, which can integrate the soil-hydraulic variability in the modelling of the soil water transport. Three data sets, all covering different scales, were subsequently used in the application of the developed concept. The results show that depth development of the soil-hydraulic variability in a soil profile can be explained by a single soil parameter. Contrarily, the explanation of the horizontal variability of the soil-hydraulic properties was not possible with the given data sets. First model applications for a soil profile showed that including the variability of the soil parameters bulk density and clay fraction in the water transport simulations could describe the variability of the soil-hydraulic variability and thus, the dynamics of the soil water content at the investigated profile.

[pt] Este trabalho faz uma análise da variação dos parâmetros que têm importância na propagação de fraturas hidráulicas e da influência desses parâmetros na conten-ção do fraturamento. Os experimentos numéricos foram feitos em um modelo 2D utilizando um simulador de elementos finitos com acoplamento sequencial hidro-dinâmico, tendo como premissa o comportamento dos processos envolvidos em es-tado estacionário. Inicialmente foram feitos testes de validação das soluções numé-ricas empregadas neste trabalho a partir de casos cujas soluções são bem conheci-das. Então, efeitos de variações de poropressão, de estado de tensões, propriedades das rochas, intervalos de início da fratura hidráulica, efeitos térmicos e o dano à permeabilidade da formação permoporosa foram utilizados para avaliar a contenção da fratura hidráulica. Primeiramente os efeitos foram avaliados separadamente e, em seguida, foram combinados aos pares, por meio de sorteio, e então avaliados. Os estudos levaram à conclusão de que o fator de maior influência para o início da propagação da fratura hidráulica na rocha capeadora (primeiros metros) é o valor da tensão mínima de confinamento do reservatório e a continuidade da propagação vertical na rocha selante é dominada pelo contraste de tensões entre rochas reserva-tório e capeadora. Entretanto, os demais parâmetros exercem influência na conten-ção do fraturamento hidráulico e devem ser levados em consideração neste tipo de estudo, principalmente os que servirão de insumo para a tomada de decisões. / [en] This master thesis analyzes the parameter s variation on the hydraulic frac-ture s propagation importance and the influence of these parameters on fracture containment. The numerical experiments were performed in a 2D model using a finite element simulator with sequential hydrodynamic coupling, having the sta-tionary behavior of the processes involved as premise. Validation tests were ini-tially performed for the numerical solutions used in this thesis from cases which solutions are well known. Then, effects of pore pressure variations, stress state, rock properties, hydraulic fracture opening intervals, thermal effects, and damage to the permoporous formation were used to evaluate the hydraulic fracture containment. At first, the effects were evaluated separately, then sorted for pair combinations, so they could be analyzed. These analyzes led to the conclusion that the most influen-tial factor for the hydraulic fracture initial propagation in the cap rock (first meters) is the reservoir’s minimum confinement stress value, and the vertical propagation continuity in the sealing rock is dominated by the stress contrast between reservoir and cap rocks. However, other parameters influence the hydraulic fracturing con-tainment and should be considered for this type of study, especially those that will serve as input for decision-making.

In civil and environmental engineering numerous are the applications that require prior collection of data on the ground. When it comes to hydraulic modelling, valuable topographic and morphology features of the region are one of the most useful of them, yet often unavailable, expensive or difficult to obtain. In the last few years UAVs entered the scene of remote sensing tools used to deliver such information and their applications connected to various photo-analysis techniques have been tested in specific engineering fields, with promising results. The content of this thesis aims contribute to the growing literature on the topic, assessing the potentialities of UAV and SfM photogrammetry analysis in developing terrain elevation models to be used as input data for numerical flood modelling. This thesis covered all phases of the engineering process, from the survey to the implementation of a 1D hydraulic model based on the photogrammetry derived topography The area chosen for the study was the Limpopo river. The challenging environment of the Mozambican inland showed the great advantages of this technology, which allowed a precise and fast survey easily overcoming risks and difficulties. The test on the field was also useful to expose the current limits of the drone tool in its high susceptibility to weather conditions, wind and temperatures and the restricted battery capacity which did not allow flight longer than 20 minutes. The subsequent photogrammetry analysis showed a high degree of dependency on a number of ground control points and the need of laborious post-processing manipulations in order to obtain a reliable DEM and avoid the insurgence of dooming effects. It revealed, this way, the importance of understanding the drone and the photogrammetry software as a single instrument to deliver a quality DEM and consequently the importance of planning a survey photogrammetry-oriented by the adoption of specific precautions. Nevertheless, the DEM we produced presented a degree of spatial resolution comparable to the one high precision topography sources. Finally, considering four different topography sources (SRTM DEM 30 m, lidar DEM 1 m, drone DEM 0.6 m, total station&RTK bathymetric cross sections o.5 m) the relationship between spatial accuracy and water depth estimation was tested through 1D, steady flow models on HECRAS. The performances of each model were expressed in terms of mean absolute error (MAE) in water depth estimations of the considered model compared to the one based on the bathymetric cross-sections. The result confirmed the potentialities of the drone for hydraulic engineering applications, with MAE differences between lidar, bathymetry and drone included within 1 m. The calibration of SRTM, Lidar and Drone based models to the bathymetry one demonstrated the relationship between geometry detail and roughness of the cross-sections, with a global improvement in the MAE, but more pronounced for the coarse geometry of SRTM.

No description available.

Master of Science / Department of Computing and Information Sciences / Mitchell L. Neilsen / People are more inclined to use tablets instead of other computing devices due to their portability and ease of use. A number of desktop applications are now becoming available as tablet applications, with increasing demand in the market. Android is one of the largest and most popular open source platforms that offer developers complete access to framework APIs in order to develop innovative tablet applications. The objective of this project is to develop an Android application for the U.S. Department of Agriculture (USDA) Structural Design Software. The GUI for this software is developed to run on tablet devices powered by Android platform. The main features provided by the User Interface include: • Allowing the input to be saved in ASCII text format and displaying the simulation results in PDF format • Allowing the user to select the type of project or view help contents for the projects • Allowing the user to build the simulation for the selected type of project • Allowing the user to send the simulation results to an e-mail The backend for this software is supposed to replace the old FORTRAN source files with Java source files. FORTRAN to Java translation is performed using the FORTRAN to Java (F2J) translator. F2J is intended to translate old FORTRAN math libraries, but was not completely successful in translating these FORTRAN programs. To accomplish successful translation, some features (such as Common Blocks, IO operations) were removed from the FORTRAN source files before translation. After successful translation, the removed features were added again to the translated Java source files. The simulation results provided by the software are useful to design engineers to develop new structural designs.

The modelling of multi-phase water flow is an important modern-day design tool used by engineers to develop practical systems which are beneficial to society . Multi-phase water flow can be found in many important industrial applications such as large scale conventional and nuclear power systems, heat transfer machinery, chemical process plants, and other important examples. Because of many inherent complexities in physical two-phase flow processes, no generalised system of equations has been formulated that can accurately describe the two-phase flow of water at all flow conditions and system geometries. This has led to the development of many different models for the simulation of two-phase flow at specific conditions. These models vary greatly in complexity. The simplest model that can be used to simulate two-phase flow is termed the homogeneous equilibrium (HEM) two-phase flow model. This model has been found useful in investigations of choking and flashing flows, and as an initial investigative model used before the formulation of more complex models for specific applications. This flow model is fully de ned by three conservation equations, one each for mass, momentum and energy. To close the model, an equation of state (EOS) is required to deliver system pressure values. When solving the HEM, a general practice is to employ an equation of state that is derived from a fundamental expression of the second law of thermodynamics. This methodology has been proven to deliver accurate results for two-phase system simulations. This study focused on an alternative formulation of the equation of state which was previously developed for the time dependent modelling of HEM two-phase flow systems, termed the rate form of the equation of state (RFES). The goal of the study was not to develop a new formulation of the EOS, but rather to implement the RFES in a transient simulation model and to verify that this implementation delivers appropriate results when compared to the conventional implementation methodology. This was done by formulating a transient pipe and reservoir network model with the HEM, and closing the model using both the RFES and a benchmark EOS known to deliver accurate system property values. The results of the transient model simulations were then compared to determine whether the RFES delivered the expected results. It was found that the RFES delivered sufficiently accurate results for a variety of system transients, pressure conditions and numerical integration factors. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

The modelling of multi-phase water flow is an important modern-day design tool used by engineers to develop practical systems which are beneficial to society . Multi-phase water flow can be found in many important industrial applications such as large scale conventional and nuclear power systems, heat transfer machinery, chemical process plants, and other important examples. Because of many inherent complexities in physical two-phase flow processes, no generalised system of equations has been formulated that can accurately describe the two-phase flow of water at all flow conditions and system geometries. This has led to the development of many different models for the simulation of two-phase flow at specific conditions. These models vary greatly in complexity. The simplest model that can be used to simulate two-phase flow is termed the homogeneous equilibrium (HEM) two-phase flow model. This model has been found useful in investigations of choking and flashing flows, and as an initial investigative model used before the formulation of more complex models for specific applications. This flow model is fully de ned by three conservation equations, one each for mass, momentum and energy. To close the model, an equation of state (EOS) is required to deliver system pressure values. When solving the HEM, a general practice is to employ an equation of state that is derived from a fundamental expression of the second law of thermodynamics. This methodology has been proven to deliver accurate results for two-phase system simulations. This study focused on an alternative formulation of the equation of state which was previously developed for the time dependent modelling of HEM two-phase flow systems, termed the rate form of the equation of state (RFES). The goal of the study was not to develop a new formulation of the EOS, but rather to implement the RFES in a transient simulation model and to verify that this implementation delivers appropriate results when compared to the conventional implementation methodology. This was done by formulating a transient pipe and reservoir network model with the HEM, and closing the model using both the RFES and a benchmark EOS known to deliver accurate system property values. The results of the transient model simulations were then compared to determine whether the RFES delivered the expected results. It was found that the RFES delivered sufficiently accurate results for a variety of system transients, pressure conditions and numerical integration factors. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: As a renewable energy source, wave energy has the potential to contribute to the increasing global demand for power. In South Africa specifically, the country’s energy needs may easily be satisfied by the abundance of wave energy at the South-West coast of the country. Commercially developing and utilizing wave energy devices is not without its challenges, however. The ability of these devices to survive extreme weather conditions and the need to achieve cost-efficacy while achieving high capacity factors are but some of the concerns. Constant changes in wave heights, lengths and directions as well as high energy levels and large forces during storm conditions often lead to difficulties in keeping the complexity of the device down, avoiding over-dimensioning and reaching high capacity factors. The point absorber device developed as part of this research is based on an innovation addressing the abovementioned issues. An approach is followed whereby standard "offthe- shelf" components of a proven hydraulics technology are used. The size of the device is furthermore adaptable to different wave climates, and the need for a control system is not necessary if the design parameters are chosen correctly. These characteristics enable low complexity of the device, excellent survivability and an exceptionally high capacity factor. This may lead to low capital as well as low operationand maintenance costs. In this paper the working principle of this concept is presented to illustrate how it utilises the available wave energy in oceans. The results obtained from theoretical tests correlate well with the experimental results, and it is proven that the device has the ability to achieve high capacity factors. As the device makes use of existing, "off-the-shelf" components, cost-efficient energy conversion is therefore made feasible through this research. / AFRIKAANSE OPSOMMING: As ’n hernubare/ herwinbare energiebron bied golfenergie die potensiaal om by te dra tot die bevrediging van die stygende globale energie-navraag. In spesifiek Suid-Afrika kan die oorvloed van beskikbare golfenergie aan die Suid-Weskus van die land gebruik word om aan die land se energiebehoeftes te voldoen. Betroubaarheid en oorlewing in erge weerstoestande, koste-effektiwiteit en die behaal van hoë kapasiteitsfaktore is beduidende struikelblokke wat oorkom moet word in die poging om ’n golfenergie-omsetter wat kommersieël vervaardig kan word, te ontwikkel. Daarby dra voortdurende veranderings in golfhoogtes, -lengtes en -rigtings sowel as hoë energievlakke en groot kragte tydens storms by to die feit dat dit moeilik is om die kompleksiteit van die stelsel laag te hou. Dit terwyl daar voorkom moet word dat die toestel oorontwerp en verhoed word dat hoë kapsiteitsfaktore bereik word. Die puntabsorbeerder-toestel wat in hierdie navorsing ontwikkel is, bestaan uit ’n ontwerp wat spesifiek ontwikkel is om die bogenoemde probleme aanspreek. ’n Unieke benadering is gevolg waardeur standaard, maklik-bekombare komponente gebruik is en die komponent-groottes ook aangepas kan word volgens golfgroottes. Indien die ontwerpsdimensies akkuraat gekies word, is die moontlikheid verder goed dat ’n beheerstelsel nie geïmplementeer hoef te word nie. Hierdie eienskappe verseker lae stelselkompleksiteit, uitstekende oorlewingsvermoë en ’n uitstaande kapasiteitsfaktor. Lae kapitaal- sowel as onderhoudskostes is dus moontlik. Die doel van hierdie dokument is om die werking van die konsep voor te stel en teoreties sowel as prakties te evalueer. Die resultate van teoretiese toetse stem goed ooreen met eksperimentele resultate, en dit is duidelik dat die toestel hoë kapasiteitsfaktore kan behaal. Aangesien die toestel verder gebruik maak van bestaande komponente wat alledaags beskikbaar is, word die koste-effektiewe omsetting van golfenergie dus moontlik gemaak deur hierdie navorsing.