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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

Stanovení Q/h charakteristiky přelivů stavidlové komory ČOV Brno-Modřice v podmínkách nedokonalého proudění / Determination of Q/h characteristics of spillways of the sluice chamber of the Brno-Modřice WWTP in conditions of influenced flow

Škrancová, Markéta January 2022 (has links)
The work deal with the measurement, processing and analysis of Q/h characteristics of the sluice chamber in the wastewater treatment plant on a physical hydraulic model in the conditions of influencing the overflow phenomenon by the groundwater level. Based on the achieved results, a measuring system has been projected in the area of the sluice chamber to measure the flow and flow rate of lightened water into the Svratka river. The measurements on the model were performed in the premises of the Laboratory of water Management Research of the Institute of Water Structures of the Faculty of Civil Engineering of Brno University of Technology by the author of this work. The results of the diploma thesis is a flow chart describing the calculation procedure used to determine the immediate flow, on the basis of which a new software of the evaluation unit of the measuring system was realized.
42

Low-complexity algorithms for the fast and safe charge of Li-ion batteries

Goldar Davila, Alejandro 24 February 2021 (has links) (PDF)
This thesis proposes, validates, and compares low-complexity algorithms for the fast-and-safe charge and balance of Li-ion batteries both for the single cell case and for the case of a serially-connected string of battery cells. The proposed algorithms are based on a reduced-order electrochemical model (Equivalent Hydraulic Model, EHM), and make use of constrained-control strategies to limit the main electrochemical degradation phenomena that may accelerate aging, namely: Lithium plating in the anode and solvent oxidation inthe cathode. To avoid the computational intensiveness of solving an online optimization as in the Model Predictive Control (MPC) framework, this thesis proposes the use of Reference Governor schemes. Variants of both the Scalar Reference Governors (SRG) and the Explicit Reference Governors (ERG) are developed to deal with the non-convex admissible region for the charge of a battery cell, while keeping a low computational burden. To evaluate the performance of the proposed techniques for the single cell case, they are experimentallyvalidated on commercial Turnigy LCO cells of 160 mAh at four different constant temperatures (10, 20, 30 and 40 °C). In the second part of this thesis, the proposed charging strategies are extended to take into account the balance of a serially-connected string of cells. To equalize possible mismatches, a centralized policy based on a shunting grid (active balance) connects or disconnects the cells during the charge. After a preliminary analysis, a simple mixed-integer algorithm was proposed. Since this method is computationally inefficient due to the high number of scenarios to be evaluated, this thesis proposes a ratio-based algorithm based on a Pulse-Width Modulation (PWM) approach. This approach can be used within both MPC and RG schemes. The numerical validations of the proposed algorithms for the case of a string of four battery cells are carried out using a simulator based on a full-order electrochemical model. Numerical validations show that the PWM-like approach charges in parallel all the cells within the pack, whereas the mixed-integer approach charges the battery cells sequentially from the battery cell with the lowest state of charge to the ones with the highest states of charge. On the basis of the simulations, an algorithm based on a mixed logic that allows to charge in a “sequential parallel” approach is proposed. Some conclusions and future directions of research are proposed at the end of the thesis. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished
43

Analysis of Flash Flood Routing by Means of 1D - Hydraulic Modelling

Tesfay Abraha, Zerisenay 17 September 2010 (has links)
This study was conducted at the mountainous catchment part of Batinah Region of the Sultanate of Oman called Al-Awabi watershed which is about 260km2 in area with about 40 Km long Wadi main channel. The study paper presents a proposed modeling approach and possible scenario analysis which uses 1D - hydraulic modeling for flood routing analysis; and the main tasks of this study work are (1) Model setup for Al-Awabi watershed area, (2) Sensitivity Analysis, and (3) Scenario Analysis on impacts of rainfall characteristics and transmission losses. The model was set for the lower 24 Km long of Al-Awabi main channel (Figure 13). Channel cross-sections were the main input to the 1D-Hydraulic Model used for the analysis of flash flood routing of the Al-Awabi watershed. As field measurements of the Wadi channel cross-sections are labor intensive and expensive activities, availability of measured channel cross-sections is barely found in this study area region of Batinah, Oman; thereby making it difficult to simulate the flood water level and discharge using MIKE 11 HD. Hence, a methodology for extracting the channel cross-sections from ASTER DEM (27mX27m) and Google Earth map were used in this study area. The performance of the model setup was assessed so as to simulate the flash flood routing analysis at different cross-sections of the modeled reach. And from this study, although there were major gap and problems in data as well as in the prevailing topography, slope and other Hydro Dynamic parameters, it was concluded that the 1D-Hydraulic Modelling utilized for flood routing analysis work can be applied for the Al-Awabi watershed. And from the simulated model results, it was observed that the model was sensitive to the type of Boundary Condition chosen and taken, channel cross sections and its roughness coefficient utilized throughout the model reach.
44

Key Influences on Hydraulic Efficiency in Treatment Wetlands

Wahl, Mark D. January 2013 (has links)
No description available.
45

Konnektivitetsåtgärder i Emån : En fallstudie vid Högsby vattenkraftverk / Measures for increasing connectivity in Em River : A case study at Högsby hydropower plant

Kuoljok, Simon Pirak January 2021 (has links)
Den nationella planen för vattenverksamheter antogs år 2020 och innebär att vattenverksamheter ska förses med moderna miljövillkor för att öka vattenmiljönytta och att bibehålla den effektiva tillgången till vattenkraftsel. Emån som är ett Natura 2000-område är det största vattendraget i sydöstra Sverige och vattendraget är utifrån konnektiviteten klassificerat som måttlig. Högsby vattenkraftverk, som ligger i Emån och ägs av Uniper, ska omprövas utifrån miljövillkor enligt den nationella planen och idag har Högsby vattenkraftverk ingen fastställd minimitappning för sin anläggning. Målet med studien är att undersöka storleken på vattenflödet av minimitappningen som kan användas i den ursprungliga naturfåran i Högsby för att möjliggöra longitudinella spridningsmöjligheter i uppströms och nedströms riktning för de fiskarter som historiskt sett har kunnat vandra genom Högsby. En sektion i naturfåran är uppdämd av en tröskeldamm som bedöms vara den svåraste passagen i naturfåran med undantag från utskovsdammen. Metoden som används i rapporten är en endimensionell stationär modellering i HEC-RAS över den naturfåra som kan möjliggöra fiskvandring förbi vattenkraftverk. Två modeller har skapats – med och utan tröskeldamm. Utifrån resultatet är den högsta medelvattenhastigheten i sektionen nedanför tröskeldammen i båda scenarion, detsamma gäller medelvattendjupet.  De konnektivitetshöjande åtgärder som diskuteras är minimitappning och olika fiskvägar i naturfåran för att behålla den historiska forsmiljön som funnits. Både rivning av tröskeldamm och fiskväg runt dammen har diskuterats. Därutöver anses havsöring och lax vara fiskarter som med stor säkerhet har kunnat passera Högsby historiskt sett. Högsby är klass 1 i relativt reglerbidrag, vilket bör tas i beaktning vid bedömning av minimitappning. Det finns osäkerheter med modellen, såsom batymetri och randvillkor samt validering av modellen. Därför går det inte med säkerhet att säga att vattendjup eller vattenhastigheter stämmer överens med verkligheten. Slutsatsen är att det inte heller med säkerhet går att säga vilka fiskarter som historiskt sett har vandrat genom Högsby, inte heller en minimitappning kan fastställas som kan möjliggöra fiskvandring för alla fiskarter. Däremot kommer implementeringen av en fastställd minimitappning och fiskvägar öka konnektiviteten. / In 2020 the national plan for hydropower plants was implemented in Sweden. The national plan aims to increase the environmental standards for hydropower plants for the benefit of the water body and still maintain an efficient access to electricity originated from hydropower. Emån is the largest river in the south-eastern part of Sweden. The river a Natura 2000 area and it is classified as moderate based on connectivity according to environmental norm for rivers and water bodies. Högsby hydropower plant located along Emån is owned by Uniper and are included within the national plan, which indicate that it needs to meet the environmental standard. Högsby hydropower plant currently has no established minimum discharge. The aim of the study is to investigate a minimum discharge for the natural dry stream located in Högsby to enable higher connectivity for the fish species that have historically been able to migrate through Högsby.  The natural stream is downstream the spillway dam in Högsby. Within the stream a weir is considered to be the most difficult passage for fish migration, with the exception of the spillway dam. The method used in the report is a one-dimensional steady flow model in HEC-RAS for the natural stream to investigate the possibility for fish migration past the hydropower plant. Two scenarios have been considered – with and without the crest dam present. Based on the result from the model, the highest mean water velocity is the section below the weir for both scenarios and same applies to the mean water depth. Implementation of a minimum discharge and various fish ways in the natural stream is measures for increasing connectivity that are being discussed which would also maintain the rapids that has existed in the stream. The fish ways that have been discussed is based on the scenarios if the weir is present or not. The fish species that with great certainty have been able to migrate through Högsby historically is sea trout and salmon. Högsby hydropower plant have the highest classified regulation of the hydropower plants in Emån which need to be considered when determining minimum discharge.  There are a few uncertainties with the hydraulic model such as bathymetry and the boundary conditions. The model is not validated which means that the water depth and the velocity might not reflect the true values. It is not certain which fish species that have migrated through Högsby historically, nor can an established minimum discharge be said to enable fish migration. However, an implementation of a minimum discharge and the fish ways that have been discussed will increase the connectivity in Högsby.
46

Impact de la résolution et de la précision de la topographie sur la modélisation de la dynamique d’invasion d’une crue en plaine inondable / Ảnh hưởng của độ phân giải và độ chính xác của số liệu tới mô phỏng lũ lụt

Nguyen, Thanh Don 09 November 2012 (has links)
Nous analysons dans cette thèse différents aspects associés à la modélisation des écoulements à surface libre en eaux peu profondes (Shallow Water). Nous étudions tout d’abord le système d’équations de Saint-Venant à deux dimensions et leur résolution par la méthode numérique des volumes finis, en portant une attention particulière sur les aspects hyperboliques et conservatifs. Ces schémas permettent de traiter les équilibres stationnaires, les interfaces sec/mouillé et aussi de modéliser des écoulements subcritique, transcritique et supercritique. Nous présentons ensuite la théorie de la méthode d’assimilation variationnelle de données adaptée à ce type d’écoulement. Son application au travers des études de sensibilité est longuement discutée dans le cadre de l'hydraulique à surface libre. Après cette partie à caractère théorique, la partie tests commence par une qualification de l’ensemble des méthodes numériques qui sont implémentées dans le code DassFlow, développé à l’Université de Toulouse, principalement à l’IMT mais aussi à l’IMFT. Ce code résout les équations Shallow Water par une méthode de volumes finis et est validé par comparaison avec les solutions analytiques pour des cas tests classiques. Ces mêmes résultats sont comparés avec un autre code d’hydraulique à surface libre aux éléments finis en deux dimensions, Telemac 2D. Une particularité notable du code DassFlow est de permettre l’assimilation variationnelle de données grâce au code adjoint permettant le calcul du gradient de la fonction coût. Ce code adjoint a été obtenu en utilisant l'outil de différentiation automatique Tapenade (Inria). Nous testons ensuite sur un cas réel, hydrauliquement complexe, différentes qualités de Modèles Numériques de Terrain (MNT) et de bathymétrie du lit d’une rivière. Ces informations proviennent soit d’une base de données classique type IGN, soit d’informations LIDAR à très haute résolution. La comparaison des influences respectives de la bathymétrie, du maillage et du type de code utilisé, sur la dynamique d’inondation est menée très finement. Enfin nous réalisons des études cartographiques de sensibilité aux paramètres du modèle sur DassFlow. Ces cartes montrent l’influence respective des différents paramètres ou de la localisation des points de mesure virtuels. Cette localisation optimale de ces points est nécessaire pour une future assimilation de données efficiente. / We analyze in this thesis various aspects associated with the modeling of free surface flows in shallow water approximation. We first study the system of Saint-Venant equations in two dimensions and its resolution with the numerical finite volumes method, focusing in particular on aspects hyperbolic and conservative. These schemes can process stationary equilibria, wetdry interfaces and model subcritical, transcritical and supercritical flows. After, we present the variational data assimilation method theory fitted to this kind of flow. Its application through sensitivity studies is fully discussed in the context of free surface water. After this theoretical part, we test the qualification of numerical methods implemented in the code Dassflow, developed at the University of Toulouse, mainly at l'IMT, but also at IMFT. This code solves the Shallow Water equations by finite volume method and is validated by comparison with analytical solutions for standard test cases. These results are compared with another hydraulic free surface flow code using finite elements in two dimensions: Telemac2D. A significant feature of the Dassflow code is to allow variational data assimilation using the adjoint method for calculating the cost function gradient. The adjoint code was obtained using the automatic differentiation tool Tapenade (INRIA). Then, the test is carried on a real hydraulically complex case using different qualities of Digital Elevation Models (DEM) and bathymetry of the river bed. This information are provided by either a conventional database types IGN or a very high resolution LIDAR information. The comparison of the respective influences of bathymetry, mesh size, kind of code used on the dynamics of flooding is very finely explored. Finally we perform sensitivity mapping studies on parameters of the Dassflow model. These maps show the respective influence of different parameters and of the location of virtual measurement points. This optimal location of these points is necessary for an efficient data assimilation in the future.
47

Un couplage de modèles hydrologique et hydraulique adapté à la modélisation et à la prévision des crues à cinétique rapide – Application au cas du bassin versant du Gardon (France). / A coupling of hydrologic and hydraulic models appropriate for modelling and forecasting fast floods – Application to the Gardon river basin (France).

Laganier, Olivier 29 August 2014 (has links)
Les bassins versants du pourtour méditerranéen français sont touchés par des pluies parfois intenses et à fort cumuls, qui peuvent engendrer des crues à cinétique rapide. Les derniers exemples majeurs en date sont ceux de l’Aude en 1999, du Gard en 2002 et du Var en 2010, dont les conséquences furent dramatiques. Ces travaux de thèse visent à évaluer une approche de modélisation complémentaire aux outils dont disposent déjà les Services de Prévision des Crues pour la prévision des crues à cinétique rapide : le couplage de modèles hydrologique et hydraulique, qui est a priori adapté pour la modélisation à l’échelle des grands bassins méditerranéens, de superficies supérieures à 1 000 km² (Ardèche, Cèze, Gardon, Vidourle…). Des éléments de réponses aux 4 questions suivantes sont recherchés : 1) le couplage est-il adapté pour la modélisation des débits atteints lors d’évènements passés, d’importance intermédiaire ? 2) le couplage est-il performant pour la modélisation des débits, cotes atteintes, et extension d’inondation, observés lors d’un épisode majeur? 3) comment envisager d’améliorer la modélisation des apports latéraux non-jaugés au modèle hydraulique, tout en adoptant une démarche adaptée à la prévision ? 4) le couplage est-il performant en prévision ? Le couplage employé combine le modèle hydrologique SCS-LR de la plateforme ATHYS (Bouvier et al., 2004), et le code de modélisation hydraulique 1D MASCARET (EDF-CETMEF, 2011). Il est appliqué au bassin versant du Gardon (2 040 km²), dans le sud de la France. / The French catchments around the Mediterranean Sea are affected by intense rains, which can cause fast and flash floods. The last major events are the one of the Aude river in 1999, of the Gard area in 2002, and of the Var area in 2010, whose consequences were tragic. This PhD intends to assess a modeling strategy complementary to the tools that are already used by the regional flood warning services: the coupling of hydrologic and hydraulic models, which is a priori well-adapted for the modelling of catchments of large-scale areas (larger than 1 000 km²) around the Mediterranean Sea (such as the ones of the Ardèche river, the Cèze river, the Vidourle river, the Gardon river…). The works aim at bringing elements of responses to the following questions: 1) is the coupling adapted to the modelling of floods hydrographs of past events of moderate importance? 2) in case of an extreme event (like in September 2002), is the coupling effective for the modelling of discharges, of water levels, and of flood extension? 3) how can we improve the modelling of ungauged lateral inflows to the hydraulic model, while applying a method adapted to forecasting? 4) Is the coupling efficient at forecasting? The coupling used combines the SCS-LR hydrologic model of the ATHYS platform (Bouvier et al., 2004), and the MASCARET 1D hydraulic model (EDF-CETMEF, 2011). It is applied to the Gardon river basin (2 040 km²), in the South of France.
48

Testing and Refining a Unique Approach for Setting Environmental Flow and Water Level Targets for a Southern Ontario Subwatershed

Beaton, Andrew 15 August 2012 (has links)
In this study Bradford’s (2008) approach for setting ecological flow and water level targets is tested and refined through application within the Lake Simcoe Region Conservation Authority’s (LSRCA) subwatershed of Lover’s Creek. A method for defining subwatershed objectives and identifying habitat specialists through expert input is proposed and tested. The natural regime of each streamflow and wetland site is characterized along with the hydrological alteration at each site. Potential ecological responses to the hydrologic alterations are then hypothesized for the different types of changes calculated at each site. Methods for setting overall ecosystem health and specific ecological objective flow targets are proposed and tested. These targets are integrated into a flow regime for each site and a process for using this information for decision making is suggested. Flow magnitude quantification is attempted using hydraulic modelling and sediment transport equations, however the data used were found to be inadequate for this application. The accuracy of the targets developed using the method presented in this paper is mainly limited by the accuracy of the hydrological model and quantified flow magnitudes. Recommendations for improving these components of the assessment are made. The unique approach and recommendations presented in this paper provide explicit steps for developing flow targets for subwatersheds within the LSRCA. This research contributes toward the advancement of EFA within the LSRCA, which provides opportunity for enhanced protection and restoration of ecosystem health across the watershed. / Lake Simcoe Region Conservation Authority

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