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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.
341

Horseshoe Bending Machine : Bending Mechanism

Quesada Díaz, Raquel January 2014 (has links)
Horseshoes are manufactured metal plates developed in an extensive assortment of materials and shapes and their main function is to protect the horse’s hooves and legs against abrasion and rupture. After a certain period of time the horseshoes are lost, worn out, or the hoof needs to be treated. Horseshoeing is a repetitive time consuming process for the farrier who has to heat the horseshoe inside a forge until it reaches the required temperature and shape it with a hammer until it fits perfectly to the horses’ hoof. The main goal of this project is to develop a horseshoe bending machine able to shape the horseshoe so its shape fits perfectly the horse’s hoof. The calculation of the bending force needed to be applied to the horseshoe in order to provoke a plastic deformation will be done with Euler-Bernoulli beam theory. The bending force is then used to design and dimension each element of the bending mechanism so that it may be able to resist the stresses and prevent the parts from collapsing during its working life span. A study of the springback effect will be done followed by the analysis of the hertzian contact stresses between the rollers and the horseshoe. In addition, a clamping system is selected to constrain the movements of the horseshoe during the bending process. This machine will reduce the final user’s horse maintenance costs at the same time that makes the fitting process easier and less demanding, which will improve the farrier’s working life span and quality.
342

Hydraulique somptuaire et transferts techniques vers l'Espagne au XVIIIe siècle : l'activité des fontainiers français dans les jardins de La Granja de San Ildefonso / Sumptuary hydraulics and technical transfers to Spain during the 18th century : french hydraulic engineers’ activity in the gardens of La Granja de San Ildefonso

Omere, Sophie 06 November 2018 (has links)
La diffusion des techniques et du savoir-faire est un thème fort en matière d’hydraulique somptuaire. Les recherches menées sur la communauté des fontainiers français au service du roi d’Espagne Philippe V permettent d’approfondir cette problématique. Installés sur le domaine royal de La Granja de San Ildefonso dans la Sierra de Guadarrama près de Ségovie, les fontainiers mettent en œuvre les innovations techniques déjà appliquées sur le chantier de Versailles. Cette étude de cas ouvre la réflexion, d'une part, sur les transferts techniques et la circulation des savoirs entre France et Espagne à l'époque moderne, à une période où des liens étroits se sont tissés entre la cour madrilène et la cour versaillaise, et d'autre part, sur la place de l'Espagne comme centre d'innovation technologique.Les jardins et leurs fontaines deviennent objet de démonstration du pouvoir, expression de la domination politique et de la puissance royale. La symbolique de faste associée aux effets d'eau des fontaines de La Granja de San Ildefonso nécessite l'installation d'un nouveau réseau de techniciens spécialisés. Le roi d'Espagne fait alors appel à des fontainiers issus de Sceaux, Versailles, Trianon, Marly et Chantilly. Ces experts hydrauliciens participent pleinement au succès de l'opération, aux côtés des jardiniers, sculpteurs et architectes, prenant part à la conception des systèmes d’alimentation en eau des jardins et à l'entretien de ces infrastructures au quotidien.Tout au long du XVIIIe siècle, les innovations techniques mises en œuvre sur les jardins royaux français, transmises par l'intermédiaire de cette communauté de fontainiers expatriés, vont s'agréger à la tradition locale hydraulique espagnole, déjà le fruit de plusieurs transferts technologiques. Les jardins de San Ildefonso doivent être replacés dans une perspective à dimension européenne de diffusion des savoir-faire du personnel technique royal français. / The study about the community of French hydraulic engineers in Spain in the service of King Philip V is to question the history of technology focusing on royal palaces hydraulics and the circulation of knowledge. The arrival of the French hydraulic engineers in La Granja de San Ildefonso changed the hydraulic technologies in Spain. From this perspective, hydraulics is an expression of political domination. This case study allows to investigate technological innovations and their transfers between France and Spain during modern times, a period when the links between both the Madrid and the Versailles courts were very close.A new network of specialized technicians was necessary to give full dimension to the political domination which was perfectly conveyed by the fountains of La Granja de San Ildefonso with their highly symbolic and breath-taking water effects. That is why the King of Spain hired hydraulic engineers from Sceaux, Versailles, Trianon, Marly and Chantilly. It was thanks to these experts who designed water supply systems and daily routines to take care of the installations, by the side of gardeners, sculptors and architects, that the project ended up being a great success.During the whole 18th century, technical innovations were implemented in the French royal gardens, taught through this community of expatriated hydraulic engineers and enriched the local hydraulic Spanish tradition which was already the result of various technological transfers. The San Ildefonso gardens must be placed on a European perspective regarding the expertise of the French royal technical workforce.
343

The role of riverbed on suspended sediment transport dynamics in Alpine Catchments / Rôle du lit des rivières sur la dynamique du transport solide par suspension dans les bassins versants alpins

Misset, Clément 18 October 2019 (has links)
Les grandes quantités de sédiments transportés par suspension dans les rivières alpines sont associées à d’importantes problématiques socio-économiques et environnementales telles que le transport de polluants, la dégradation des milieux aquatiques ou l’envasement des retenues hydroélectriques. Pour faire face à ces enjeux, il est nécessaire de mieux comprendre le rôle joué par le lit des rivières alpines sur la dynamique de ce transport. A partir de larges bases de données issues de la littérature et de nouvelles mesures de terrain, la première partie de cette thèse propose une étude à une échelle régionale de i) l’influence de la configuration des sources sédimentaires sur la variabilité du transport solide par suspension, ii) l’estimation de la quantité et de la disponibilité des particules fines dans le lit des rivières alpines et iii) l’analyse de la relation entre transport solide par suspension et mobilité du lit de ces rivières. Ces analyses montrent que la configuration du bassin versant en amont du point d’observation contrôle significativement la dynamique du transport solide par suspension observée en aval. De grandes quantités de sédiments fins sont en effet stockées dans les rivières alpines alluviales et il est ainsi possible de prédire une partie significative de leurs flux en suspension pour les forts débits à partir d’une modélisation de la mobilité de leurs lits. La seconde partie de la thèse teste ces résultats à une échelle locale. Pour cela, une campagne de mesures a été réalisée durant une saison complète de fonte sur un cours d’eau alpin typique, la Séveraisse. Un large panel de mesures directes et indirectes a été mis en œuvre pour mesurer la suspension, le charriage et les évolutions topographiques sur un tronçon de 3.5 km. Ces mesures confirment que les particules fines transportées par suspension interagissent fortement avec le lit dans ce type de tronçon morphodynamiquement actif. Ce dernier peut être perçu comme une zone tampon intermédiaire contrôlée par le forçage amont sédiments-débit liquide ainsi que par la mobilité et la morphologie de son lit. / The large quantities of sediments transported as suspension in Alpine rivers are associated with important socio-economic and environmental issues such as pollutant transfer, aquatic habitat degradation or dam siltation. To address these issues, it is required to better understand the role of Alpine river beds on the dynamics of this transport. In the first part of this thesis, we use large datasets from the literature and new field measurements to investigate at a regional scale i) the influence of sediment sources configuration on suspended load variability, ii) the quantity and availability of fine particles in Alpine river beds and iii) the relation between suspended load and river bed mobility. These analyses show that the catchment configuration upstream the observation point can significantly control the suspended load dynamics observed downstream. This first part also shows that large quantities of fine particles can be stored in alluvial Alpine rivers. For these rivers and for high flow rates, it was possible to predict a significant part of suspended load based on riverbed mobility modeling. The second part of the thesis tests these results at a local scale. To do so, an important field campaign was performed during the entire melting season of a typical Alpine river, the Séveraisse. A large panel of direct and indirect measurements was used to measure suspended load, bedload and topographic changes on a 3.5-km reach. These measurements confirm that suspended particles strongly interact with the river bed in that kind of morphodynamically active streams. The latter can be considered as an intermediate buffer controlled by the upstream hydro-sedimentary forcing and by the river bed mobility and morphology.
344

Feasibility study on Thermal Anemometry at LWR conditions / Genomförbarhetsstudie om Thermal Anemometry vid LWR-förhållanden

Baskar, Abishek January 2021 (has links)
Dryout and Departure from Nucleate boiling (DNB) are utmost thermal-hydraulic concerns for the safety of LWRs. The behavior of two-phase flows at these conditions is still not fully understood. There is at least a need for a good local velocity and void fraction database at these conditions. This database can be exploited by CFD codes, thereby leading to understanding and predicting DNB and boiling crisis. Since these conditions occur in LWR at pressures greater than 70 bar and temperatures above 285 $^oC$, most instrumentations fail at these conditions. So there is a need for developing or optimizing new instruments for this specific objective. This study will look into the application of Hot Wire Anemometry (HWA) for this application. Previous experiments at near saturation conditions were studied, the hurdles of application of HWA in the HWAT loop at KTH were also investigated. Finally, the deposition of thin film on the HWA sensors for protection was studied. / Dryout och avvikelse från kärnkokning (DNB) är extrema termiska hydrauliska problem för säkerheten för LWR. Tvåfasflödets beteende under dessa förhållanden är fortfarande inte helt förstådd. Det finns ett behov av en god lokal hastighets- och tomrumsfraktionsdatabas under dessa förhållanden. Denna databas kan användas av CFD-koder, vilket leder till att förstå och förutsäga DNB och den kokande krisen. Eftersom dessa förhållanden förekommer i LWR vid tryck större än 70 bar och temperaturer över 285 oC, misslyckas de flesta instrument vid dessa förhållanden. Så det finns ett behov av att utveckla eller optimera nya instrument för detta specifika mål. Denna studie kommer att undersöka tillämpningen av Hot Wire Anemometry (HWA) för denna applikation. Tidigare experiment vid nästan mättnadsförhållanden dissekerades, hinder för tillämpningen av HWA i HWAT-slingan vid KTH undersöktes också. Slutligen undersöks avsättningen av tunn film på HWA-sensorerna för skydd.
345

Computer-Based Instruction for Engineering Education in the Developing World

Singley, Bradford G. 30 August 2007 (has links) (PDF)
Although civil engineers continually develop new ways to solve problems involving water, energy, infrastructure and environmental sustainability, these innovations can take years – or even decades – to reach developing countries. Computer-based instruction has the potential to dramatically decrease this lag time by improving engineering education in the developing world. This paper discusses the development of instructional simulations, based on the theory of model-centered instruction. These simulations can serve as self-paced learning modules, which can be accessed for free over the Internet. A pilot learning module was developed for the United Nations Educational Scientific and Cultural Organization (UNESCO) on the topic of reservoir sedimentation. This pilot learning module is described in terms of widely-accepted instructional design principles. Preliminary assessment of the pilot module demonstrated that instructional simulations can effectively teach engineering principles within the context of real-world problems. Students found this type of learning to be both challenging and engaging.
346

Public Safety at Low-Head Dams: Fatality Database And Physical Model of Staggered Deflector Retrofit Alternative

Kern, Edward William 19 March 2014 (has links) (PDF)
Low-head dams can cause dangerous currents near the downstream face of the structure. Fatalities at low-head dams are poorly documented. This thesis introduces a website with an interactive map and database of fatalities at low-head dams in the United States. The purpose of the web site is to generate interest among the general public to increase support to remediate dangerous structures and to serve as a tool for public education. The user interface allows the general public to browse fatal incidents by geographic location and to read incident circumstances. The site allows submission of public contributions including all metadata needed to characterize the incident. The database is structured to include documentation verifying each entry. The site can be viewed at http://krcproject.groups.et.byu.net. The danger is due to a uniform channel-wide countercurrent which causes upstream directed surface velocities. Previously, few inexpensive retrofit alternatives have been studied which prevent the uniform countercurrent. This thesis investigates two cost-effective retrofit options: (1) a channel wide horizontal flow deflector and (2) staggered flow deflectors. The channel wide flow deflectors cause uniform downstream directed surface velocities for a narrow range of tailwater elevations. The staggered flow deflectors prevent the uniform countercurrent for a wide range of tailwater elevations.
347

A Novel Multi-objective Risk-informed Rehabilitation Framework for Sewerage Systems

Cai, Xiatong 12 August 2020 (has links)
Stormwater sewer infrastructure is at risk due to ageing, structural deterioration, population growth, and climate change. Since the consequences of the sewer system failure can adversely impact the community safety, environment and economy, a resilient infrastructure system is of essential importance. However, limited reinvestment budget and insufficient asset management practices impact the rehabilitation of urban sewerage systems. Therefore, an effective and efficient rehabilitation plan is needed to help proper investment decisions. An effective rehabilitation plan will maximize hydraulic performance while minimizing the overall failure risk within a limited budget. The current study aims to address this issue through designing a risk-informed methodology in three steps. First, the hydraulic risk index (obtained using the SWMM model) was combined with the ageing pipe index. The framework uses multi-objective optimization technique to generate solutions under specific sewerage conditions. We named this new framework as Hydraulics and Risk Combined Model (HRCM). Several scenarios including high hydraulic risk, high ageing risk, hydraulic risk and ageing risk (combined problems), and limited budget problems, are used to test the performance of the proposed methodology. The results show that the proposed model could provide a satisfactory solution. Then, in order to increase the calculation speed and improve the accuracy, sensitivity and cost-effectiveness analyses were also conducted for the proposed methodology with different algorithms. The results show that different algorithms offer various benefits. A new calculation method was offered by combining the advantages of the previous methods. Finally, a new optimization method named Phenotype Searching Method, which was enlightened by sexual selection processes, was offered. This method can enhance the selection processes to specific phenotypes (pipes) so that it can increase the convergence speed and increase the performance of the HRCM model.
348

Analysis of dropbox assisted hydraulic traction / Analys av en dropboxstödd hydraulisk drivlina

LI, Zhen January 2017 (has links)
The research looks at the advantages and disadvantages of a hydraulic auxiliary drive (HAD) system which is installed on a 25 meter long timber transport vehicle. The purpose is to investigate the performance with regard to energy, economy and environment of the system due to the added components, the hydraulic accumulators. The auxiliary system that is used on the vehicle is simply a hydrostatic transmission system. Ideally, the fuel consumption and cost can be reduced by using accumulators. To verify this hypothesis, model-based simulations were performed in a software environment and the result was analyzed for a linear and repeatedly accelerating and decelerating driving cycle. Additionally, comparisons were made between the HAD system with and without the assistance of accumulators. From the simulation results, the system assisted by accumulators consumes approximately 14% less fuel than the other. And it produces 15% more tractive effort when the vehicle is accelerating. The paper also includes the determination of the size of accumulators, both theoretically and with simulations. By comparison, there is a small difference between the results from the theoretical calculation and the simulations, which might be caused by a neglecting the volumetric losses in the simulation process. Ideally, an accumulator with a size of 57 L was found to be the most efficient size for the studied driving cycle. Beyond that speed, the efficiency will decrease to some extent. Physical tests are not presented in this paper, but they will be done in the future. / Den presenterade forskningen studerade fördelar och nackdelar med ett hydraulisk hjälpsystem för fordonsdrift (HAD) för en 25 meter lång timmerlastbil. Syftet var att undersöka hur drivlinans prestanda med avseende på energy, ekonomi och miljöpåverkan, påverkas av de adderade komponenterna, de hydrauliska ackumulatorerna. Hjälpsystemet är helt enkelt ett hydrostatiskt transmissionssystem. Idealt, kan bränsleförbrukning och kostnad reduceras genom att använda ackumulatorer i systemet. För att verifiera denna hypotes, har modell-baserade simuleringar utförts och resultaten har analyserats för konstantfartskörning och en körcykel med upprepade accelerationer och inbromsningar. Dessutom, har ett HAD-system med och utan ackumulator jämförts. Simuleringsresultaten visar att ett system med ackumulatorer förbrukar ca 14% mindre bränsle än ett system utan ackumulatorer. Ett ackumulatorstött system ger också 15% högre framdrivningseffekt vid accelereration. I avhandlingen dimensionera också storleken på ackumulatorerna, både teoretiskt och med simuleringar. Det finns en liten skillnad mellan resultaten från den teoretiska beräkningen och simuleringarna, som kan bero på att volymetriska förlusterna inte har tagits med i simuleringarna. En ackumulator med en storlek på 57 L visar sig ha den mest effektiva storleken för den studerade körcykeln. Vid högre körhastigheter, kommer verkningsgraden att minska till viss del. Inga fysiska tester har gjorts, men de kommer att utföras i framtiden.
349

Validation of TRACE Code against ROSA/LSTF Test for SBLOCA of Pressure Vessel Upper-Head Small Break

Xing, Mian January 2012 (has links)
OECD/NEA ROSA/LSTF project tests are performed on the Large Scale Test Facility (LSTF). LSTF is a full-height, full-pressure and 1/48 volumetrically-scaled two-loop system which aims to simulate Japanese Tsuruga-2 Westinghouse-type 4-loop PWR. ROSA-V Test 6-1 simulates a pressure vessel (PV) upper-head small break loss-of-coolant accident (SBLOCA) with a break size equivalent to 1.9% of the volumetrically scaled cross-sectional area of the reference PWR cold leg.The main objective of present thesis is to build a TRACE calculation model for simulating thermal hydraulic behaviors in LSTF and PV upper-head SBLOCA, so as to assess different modeling options and parameters of TRACE code. The results show that TRACE code well reproduce the complex physical phenomena involved in this type of SBLOCA scenarios. Almost all the events in the experiment are well predicted by the model based on TRACE code. In addition, the sensitivity of different models and parameters are investigated. For example, the code slightly overestimates the break mass flow from upper head which affects the accuracy of the results significantly. The rising of core exit temperature (CET) is significantly influenced by the flow area of leakage between downcomer and hot leg. Besides, the effect of the break location, low pressure injection system (LPIS) and accumulator setup are also studied.
350

TRACE Analysis of LOCA Transients Performed on FIX-II Facility

HU, XIAO January 2012 (has links)
As a latest developed computational code, TRACE is expected to be useful and effective for analyzing the thermal-hydraulic behaviors in design, licensing and safety analysis of nuclear power plant. However, its validity and correctness have to be verified and qualified before its application into industry. Loss-of-coolant accident (LOCA) is a kind of transient thermal hydraulic event which has been emphasized a lot as a most important threat to the safety of the nuclear power plant. In the present study, based on FIX- II LOCA tests, simulation models for the tests of No. 3025, No. 3061 and No. 5052 were developed to validate the TRACE code (version 5.0 patch 2). The simulated transient thermal-hydraulic behaviors during the LOCA tests including the pressure in the primary system, the mass flow rate in certain key parts, and the temperature in the core are compared with experimental data. The simulation results show that TRACE model can well reproduce the transient thermal-hydraulic behaviors under different LOCA situations. In addition, sensitivity analysis are also performed to investigate the influence of particular models and parameters, including counter current flow limitation (CCFL) model, choked flow model , insulator in the steam dome, K-factor in the test section, and pump trip, on the results. The sensitivity analyses show that both the models and parameters have significant influence on the outcome of the model.

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