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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.
11

Hydraulic Characteristics Of Tyrolean Weirs

Yilmaz, Aslican Nazli 01 December 2010 (has links) (PDF)
Tyrolean type water-intake structures are widely used on mountain rivers to provide water to hydropower stations. The main concern encountered in these kinds of structures is the amount of water diverted from the main channel and sediment carried by this flow. The diverted flow should not be less than the design discharge of the hydropower station and the amount of the sediment entering the hydraulic system should be minimum. In this study a physical model of a Tyrolean weir was constructed at the Hydromechanics Laboratory and by varying the dimensions of the various components of this system / the length, the inclination angle of the rack and the distance between the rack bars, the amount of water and sediment entering the system were measured for a wide range of discharges. The experiments were conducted in two stages. In the first stage the tests were made with only water, and in the second stage, water and sediment having different gradation were used. Applying dimensional analysis to the related parameters of the system dimensionless terms were defined for water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel flow.
12

Hydraulic Characteristics Of Tyrolean Weirs Having Steel Racks And Circular-perforated Entry

Sahiner, Halit 01 March 2012 (has links) (PDF)
Tyrolean type water-intake structures are commonly used on mountain rivers to supply water to hydropower stations. The amount of water to be diverted from the main channel is the major concern in these kind of structures and should not be less than the design discharge. In this study a physical model of a Tyrolean type water-intake structure was built at the laboratory and the diverted flow from the main channel through the intake structure having steel racks and perforated plates of different types were measured. The experiments were conducted in two stages. In the first stage the tests were carried out with only steel racks having three different bar openings and slopes, and in the second stage, perforated screens of three different circular openings and screen slopes were used. Applying dimensional analysis to the related parameters of the system the dimensionless terms were defined for the water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel discharge.
13

Návrh konstrukce nové verze vozíku a dokovací stanice pro kanálové regály / Design of a new version of a trolley and docking station for channel racks

Pastrnková, Markéta January 2021 (has links)
The master's thesis deals with the analysis of the current version of the trolley and the docking station of the channel racks and the design of modifications. The theoretical part describes the components of the storage channel system. There is also explained principle of pallet storage in this part. In the following chapter, several variants of the design of the lifting mechanism of the lifting platform are elaborated. The work also presents static structural analysis of the current version of the trolley and docking station, parametric study and topological optimization of one of the components. Static structural analyzes were partially solved in the finite element software RFEM by Dlubal Software s.r.o company, and mainly in the software ANSYS Workbench 2020 R2 by ANSYS, Inc. company.
14

Automatisering av det interna flödet på ett tillverkande företag : En studie om den interna hanteringen av kretskortställningar och hur det kan effektiviseras i flödet

Kadhim Abed, Ahmed, Rappestad, Erik January 2023 (has links)
Purpose: The purpose of the study was to identify the current transport flow for circuit board racks and to investigate the potential implementation of an automated solution for the transportation of circuit board racks in order to increase efficiency in the flow. The research questions answered during this study were: What does the transport flow for circuit board racks look like today?  What could an automated transport flow for circuit board racks look like?  Is an automated transport flow for circuit board racks a sufficient solution to improve efficiency in the flow? Theoretical framework: The study applied several different theories, with waste being a central part. This, in combination with bottleneck identification, mapping, and automation, has been theories used to study the flow and find improvements. Method: A case study was conducted to analyze the transport flow of circuit board racks and identify potential improvements. The method included a literature review, observations, interviews, brainstorming, Value Stream Mapping, and spaghetti diagrams to collect and analyze data from different perspectives. Results: With a combination of theories and empirical data, an analysis of the current transport flow for the circuit board racks could be made. Furthermore, bottlenecks and waste were identified, and automated transport solutions linked to AMR systems were found as a potential solution for a more efficient transport flow. The result showed that an AMR system is the most advantageous solution. However, the study showed that the automated solution was not sufficient without eliminating the bottlenecks in order to generate maximum efficiency in the automated transport flow. Implications: This study has the implication of highlighting the challenges and opportunities of a more efficient transport flow using AMR systems. This includes an improved working environment, reduced work-related injuries, increased production efficiency by eliminating bottlenecks, and waiting times.
15

Mechanický čistící stroj / Mechanical cleaner-machine

Čejda, Robert January 2009 (has links)
The aim of my diploma thesis is to design a construction of a mechanical fine rack cleaner machine including an appropriate design of gear mechanism and its attachment to the frame. The cleaner machine is located in the inflow system of a turbine in front of the object of small hydro power station. The design of the construction of the cleaner machine will be based on a drawing documentation and a report with needed analytic and FEM calculations.
16

Experimental and Analytical strategies to assess the seismic performance of auxiliary power systems in critical infrastructure

Ghith, Ahmed January 2020 (has links)
The performance of nonstructural components in critical infrastructure, such as nuclear power plants (NPPs), has been primarily based on experience and historical data. This topic has been attracting increased interest from researchers following the Fukushima Daiichi nuclear disaster in 2011. This disaster demonstrated the importance of using batteries in NPPs as an auxiliary power system, where such systems can provide the necessary power to mitigate the risk of serious accidents. However, little research has been conducted on such nonstructural components to evaluate their performance following the post- Fukushima safety requirements, recommended by several nuclear regulators worldwide [e.g., Nuclear Regulatory Commission (NRC), and Nuclear Safety Commission (NSC)]. To address this research gap, this dissertation investigates the lateral performance of an auxiliary battery power system (ABPS) similar to those currently existing/operational in NPPs in Canada. The ABPS was experimentally tested under displacement-controlled quasi-static cyclic fully-reversed loading that simulates lateral seismic demands. Due to the presence of sliding batteries, the ABPS was then tested dynamically under increased ground motion levels on a shake table. The experimental results demonstrated that the design guidelines and fragility curves currently assigned to battery rack systems in the FEMA P58 prestandards do not encompass all possible failure mechanisms. A 3D numerical model was also developed using OpenSees software. The model was validated using the experimental results. The model results showed that the lateral performance of ABPS with different configurations (i.e. different lengths, tiers, and seismic categories) is influenced by the capacity of the L-shaped connection between the side rails and the end rail. However, the model was not able to predict all the damage states from the dynamic experimental tests, since the rocking/sliding/impact behavior of the batteries is a highly complex nonlinear problem by nature and beyond the scope of this study. The model presented is limited to the assessment of the lateral performance of different ABPS statically. This dissertation demonstrated the difference between the observed behavior of laboratory-controlled lateral performance tests of ABPSs operational/existing in NPPs and the behavior of ABPSs found in the literature that relied on limited historical and experience data. Finally, this dissertation laid the foundations for the need to further investigate the behavior of other safety-related components in NPPs and assess their compliance with new post-Fukushima design requirements. / Thesis / Doctor of Philosophy (PhD)
17

Beteendevariation hos europeisk blankål (Anguilla anguilla) vid tre typer av ß-galler och deras ledningsförmåga / Behavioral variation in European Silver eel (Anguilla anguilla) at three different ß-racks and its guiding ability

Karlsson, Madeleine January 2024 (has links)
Den europeiska blankålen (Anguilla anguilla) har genomgått en stor populationsminskning de senaste decennierna på grund av antropogena strukturer i form av vattenkraftverk som orsakar fragmentering. Vid vattenkraftverks intagskanaler finns intagsgaller installerade för att förhindra drivgods från att skada turbinerna. Forskning har utvecklat lösningar i form av anpassade galler, med låg lutning, som leder fisken till en flyktöppning vid sidan av kraftverket. Det har observerats att utformningen av gallret påverkar fiskars beteenden och beteendeobservationer kan därför ge viktig kunskap om hur väl åtgärder funkar och vilka förbättringar som krävs. Syftet med denna studie var att undersöka beteenderespons och passageframgång för europeisk blankål (Anguilla anguilla) vid tre olika typer av låglutande ß-galler med 30 mm spaltvidd. Man ville också undersöka om det finns någon koppling mellan ålarnas beteenderespons och gallrens vägledande funktion.  Experimentet utfördes vid Vattenfalls Research and Development laboratorium i Älvkarleby. En artificiell miljö i form av en ränna användes för att simulera ett turbinintag. Här testades blankålars (n=69) beteende och passage av tre olika typer av ß-galler med (i) horisontella järn orienterade i linje med vattnets strömriktning (H0), (ii) vertikala järn orienterade i linje med vattnets strömriktning (V0) och (iii) vertikala järn med 60° vinkel mot strömmen (V60). Resultatet visar att det inte finns någon signifikant skillnad i ålarnas beteenderespons mellan de tre olika gallren. Däremot såg man att det fanns en koppling mellan ålarnas beteenderespons och gallrens vägledande förmåga. De ålar som vägleddes av gallren hade huvud som första fysiska kontakt med gallret. Vidare forskning på ålbeteenden vid intagsgaller är nödvändigt för att öka migrationsframgången hos europeisk ål. / The European silver eel (Anguilla anguilla) has undergone a large population decline in recent decades due to anthropogenic factors such as hydropower plant river fragmentation. At the intake channel of hydropower plants there are trash racks for preventing drifting obstacles to damage the turbines. Research has developed solutions such as angled bar racks, which guide fish to a bypass. The design of the racks has been observed has an effect on fish behavior and its therefore important to provide actions and improvements. The aim of this study was to investigate behavioral and passage success of the European silver eel (Anguilla anguilla) of three different types of low-sloping angled bar racks with 30 mm clear spacing and whether there is any connection between the behavioral response of the eels and the guiding function of the racks. The experiment took place at Vattenfall's Research and Development laboratory located in Älvkarleby. A flume resembling an intake channel was used. Here (n=69) eels were tested on three different types of low-sloping angled bar racks: (i) horizontally bars oriented in line with the water current streamwise (H0), (ii) vertical bars oriented in line with the water current streamwise (V0) and (iii) vertical bars with a 60° angle to the current (V60). The result shows that there is no significant difference in the eels behavioral response between the three different racks. However, it was seen that there was a connection between the behavioral response of the eels and the guiding ability of the racks. Al eels that were guided by the racks, only had head as first physical contact with the rack. Further research on eel behaviors at intake racks is necessary to increase the migration success of European eel.
18

Alternativní řešení a pevnostní kontrola mechanických česlí / Alternative solution and strength check of mechanical screens

Sommer, Matěj January 2020 (has links)
This master’s thesis deals with a new design of bar screens. The goal was to come up with an alternative design to already existing device by INKOS a. s. In the first part, there is a summary of various machines working in similiar conditions. The insights gained by this research influenced the design of the new device. It utilizes well proven solutions from previous projects, but some of these were reworked and a few new functions were added. Second part of the thesis describes the analytical solutions, which were used to determine the forces in the assembly during the operation of the device. Based on the results of these calculations, a strength analysis of important components was performed using the finite element method. The result of this thesis is the design and optimization of new bar screens, including engineering drawings and tools for its further development.

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