• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 261
  • 56
  • 47
  • 38
  • 31
  • 21
  • 19
  • 12
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • Tagged with
  • 626
  • 193
  • 95
  • 85
  • 83
  • 77
  • 69
  • 65
  • 55
  • 49
  • 43
  • 42
  • 40
  • 39
  • 37
  • 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.
421

Changes in South Atlantic Cyclones due Climate Change / Mudanças nos Ciclones do Atlântico Sul devido às Mudanças Climáticas

Gramcianinov, Carolina Barnez 04 October 2018 (has links)
Cyclones distribution and intensities impact directly on human activities, mainly due to their associated intense precipitation and winds. The main aim of this thesis is to understand changes in the cyclones originated in the South Atlantic focusing on their genesis and intensifying mechanisms. Cyclones are identified and tracked based on the relative vorticity field at 850 hPa computed from the winds. The characteristics of the cyclones are obtained by diagnostic variables sampled within a radial distance from each cyclone center and to produce a spatial distribution of the cyclone properties at the time of genesis. Also, cyclone centered composites are used to analyze the cyclone structure and the evolution of cyclones during their genesis. The climatology of cyclones was done using NCEP-CFSR and shows four main cyclogenesis regions in the South Atlantic Ocean: on the Southern Brazilian coast (SE-BR, 30°S), over the continent near the La Plata river discharge region (LA PLATA, 35°S), on the southeastern coast of Argentina (ARG, 40°S-55°S) and on the Southeastern Atlantic (SE-SAO, centered at 55°S and 10°W). To access changes in cyclone development, we used the CMIP5 HadGEM2-ES historical experiment (1980-2005) and RCP8.5 future projection (2074-2099). The HadGEM2-ES can represent the main South Atlantic characteristics of cyclones according to NCEP-CFSR climatology. However, there is an underestimation in cyclone frequency in the equatorward side of the storm track, particularly in the LA PLATA region. The HadGEM2-ES RCP8.5 future projection shows a general decrease of approximately 10% of cyclogenesis in the South Atlantic domain, which is mainly related to the poleward shift of the storm track. However, LA PLATA region presents a slight increase in its cyclogenetic activity (6.1 and 3.6%), in the summer and winter, respectively). The increase in genesis at 30°S over the continent is associated with the strengthening of the upper-level jet and the increase of warm and moisture advections at the same location. The enhance in the moisture transport from the tropics is also related to the intensification of the cyclone in the domain, mainly northward of 35°S. Finally, a downscaling using WRF was performed in an attempt to improve the climate model resolution. However the downscaling produces less and weaker cyclones in the NCEP-CFSR and HadGEM2-ES runs. The only region that presented an improvement was LA PLATA, due to the better representation of local features related to orography and moisture processes. The downscaled HadGEM2-ES RCP8.5 also shows an increase in cyclogenesis in the LA PLATA region and other locations. The HadGEM2-ES RCP8.5 projection and its downscaling shows that the cyclogenesis in some locations of South America is increasing, mainly due to the increase in the low-level moisture content and the strengthening of the equatorward flank of the upper-level jet. The cyclones in this locations will be slightly intense (between 20°S and 30°S) and will affect a narrow area close to the South American coast. / A distribuição e intensidade dos ciclones afeta diretamente as atividades humanas devido a precipitação e fortes ventos associados a esses sistemas. O objetivo principal deste trabalho é entender as mudanças nos ciclones gerados no Atlântico Sul devido às mudanças climáticas, focando em seus mecanismos geradores e intensificadores. Os ciclones foram identificados e rastreados utilizando a vorticidade relativa em 850hPa, calculada a partir do campo de ventos horizontal. Também foram usadas composições centradas para a análise da estrutura e evolução dos ciclones durante seu desenvolvimento. A climatologia de ciclones feita com o NCEP-CFSR mostra quatro regiões ciclogenéticas principais no Oceano Atlântico Sul: na costa sul do Brasil (SE-BR, 30°S), sobre o continente próximo da desembocadura do Rio da Prata (LA PLATA, 35°S), na costa sudeste da Argentina (ARG, 40°S-55°S) e no Sudeste do Atlântico (SE-SAO, centrada em 55°S, 10°W). Para analisar as mudanças no desenvolvimento dos ciclones, nós utilizamos os experimentos histórico (1980-2005) e RCP8.5 (2074-2099) do HadGEM2-ES (CMIP5). O HadGEM2-ES é capaz de reapresentar as principais características dos ciclones do Atlântico Sul, quando comparado à climatologia. No entanto, existe uma subestimativa do número de ciclones no lado equatorial da região de máxima atividade ciclônica, principalmente na região LA PLATA. A projeção futura HadGEM2-ES no cenário RCP8.5 mostra uma redução de aproximadamente 10% na ciclogêneses no domínio do Atlântico Sul, principalmente associada ao deslocamento em direção ao polo da região de máxima atividade ciclônica. Porém, a região LA PLATA apresenta um pequeno aumento em sua atividade ciclogenética (6.1 e 3.6%), no verão e inverno, respectivamente). O aumento na ciclogênese em 30°S está associada ao fortalecimento do jato de altos níveis e ao aumento da advecção quente e de umidade nessa localidade. O aumento do transporte de umidade dos trópicos está associado também à intensificação dos ciclones observada na projeção futura, principalmente ao norte de 35°S. Por fim, uma regionalização com o modelo WRF foi usada para melhorar a resolução do modelo climático. Porém, as simulações regionais subestimaram os ciclones em número e intensidade. A única região que em as regionalizações apresentaram melhor desempenho foi a LA PLATA, devido a uma melhor representação de feições locais associadas a orografia e processos úmidos. A regionalização do cenário futuro RCP8.5 também apresentou aumento da ciclogênese do LA PLATA, mas para o inverno. Tanto a projeção RCP8.5 do HadGEM2-ES quanto sua regionalização mostram que a ciclogênese em algumas regiões da América do Sul está aumentando, principalmente devido ao aumento de umidade em baixos níveis da atmosfera e fortalecimento do lado ramo equatorial do jato de altos níveis. Os ciclones nessas localidades serão intensos (entre 20°S e 30°S) e tendem a afetar uma região mais próxima à costa.
422

Les paradoxes de l'engagement chez Tennessee Williams : les pièces des années trente / The paradoxical aspects of commitment in Tennessee Williams’ work : the plays from the thirties

Systermans, Valérie 11 May 2010 (has links)
Cette thèse se propose d'appréhender le parcours du dramaturge américain Tennessee Williams en démontrant qu'il existe une authentique dimension engagée dans son œuvre. Ceci va à l'encontre de la critique traditionnelle qui tend à le dépeindre comme l'homme de la nostalgie et du rêve, le dramaturge apolitique du désir et des passions, en faisant abstraction du contexte idéologique. Or, Williams a commencé sa carrière dans les années trente comme écrivain protestataire en produisant de violentes pièces de dénonciation dans la tradition du théâtre de gauche. L'analyse de ces pièces écrites entre 1936 et 1938 – Candles to the Sun, Fugitive Kind, Spring Storm et Not About Nightingales – permet de rendre intelligible le parcours d'un dramaturge qui s'est toujours défini comme un révolutionnaire et revendique sa conscience sociale comme l'élément déterminant de son œuvre. Dans ces pièces, il intègre les stratégies formelles du théâtre de gauche comme le réalisme révolutionnaire ou l'esthétique du Front Populaire tout en créant des œuvres atypiques qui se distinguent de la production de l'époque. Préférant l'ambiguïté à des messages clairs ou didactiques, il inscrit ses premiers écrits sous le signe de la non clôture et joue avec les mécanismes identificatoires. Théâtre de l'émotionnel, son théâtre parait être à l'opposé de celui de Brecht. Pourtant son impact est souvent remarquablement similaire. C'est finalement en théorisant le phénomène des identifications fluctuantes que l'on peut comprendre la manière dont Williams s'approprie les fondements du théâtre de Brecht en en transposant les structures stéréoscopiques. Ceci nous conduit à redéfinir l'engagement au théâtre. / The object of my thesis is to reconsider the critical studies on Tennessee Williams by focusing on the political dimension of his early work. This is done by analysing the protest plays he wrote in the 1930s: Candles to the Sun, Fugitive Kind, Spring Storm and Not about Nightingales. These seminal plays reveal a virtually unknown Tennessee Williams, committed to fighting social injustice. This discovery is all the more important as the dramatist is often portrayed as an apolitical writer and described as a poet of the flesh and a depictor of sexual instincts and conflicts. This approach challenges the conventional vision of Williams' literary ambitions by showing that he may have been more socially and even politically subversive than generally admitted. A careful reading of Williams’s plays written in the thirties reveals that he closely followed the developments of left-wing theatre both in the choice of his subjects and of dramaturgical forms such as revolutionary realism or the aesthetics of the Popular Front. Still, he created original plays that went far beyond rigid formulaes or predictable plots. Because they propose no clearcut message, and through their permeating ambiguity and the feelings of empathy they trigger, these plays radically differ from the other productions of the period. Williams’ theatre could be described as a theatre of emotions at the opposite of Brecht’s theatre of alienation. However its impact is often remarkably similar. This can be explained by the phenomenon of fluctuating identifications that is Williams’s way of absorbing Brecht’s stereoscopic structures. This leads us to redefine the very principles of commitment in the theatre.
423

Variação temporal de pequena escala da macrofauna bentônica da zona costeira rasa da Enseada Martel (Baía do Almirantado, Antártica), com ênfase em Annelida Polychaeta / Short-term variation of macrofauna in the nearshore zone of Martel Inlet (Admiralty Bay, Antarctica), with emphasis to Annelida Polychaeta

Gabriel Sousa Conzo Monteiro 28 April 2011 (has links)
A distribuição, composição e alguns aspectos da variação temporal de grande escala da macrofauna bentônica da zona costeira rasa da baía do Almirantado já são conhecidos. O presente trabalho investigou a variação temporal de pequena escala da macrofauna, com ênfase nos Polychaeta, aos 20 metros de profundidade na enseada Martel. Foram feitas amostragens de sedimento, com um pegador de fundo tipo van Veen, em um mesmo ponto durante 35 dias, em intervalos aproximados de uma semana. Foram verificadas variações significativas na densidade de alguns grupos taxonômicos (Amphipoda e Polychaeta) e na composição granulométrica sedimentar. Bivalvia, Amphipoda, Cumacea e Oligochaeta, que vivem nas primeiras camadas do sedimento, constituíram um grupo sensível ao impacto causado por intensas tempestades. As espécies dominantes de Polychaeta (87% do total) foram Rhodine intermedia, Ophelina syringopige, O. gymnopyge, Apistobranchus glacierae e Tharyx cf. cincinnatus. Somente a densidade de O. gymnopyge apresentou variação significativa, o que não ocorreu com os descritores ecológicos do grupo. Estes resultados colaboram para o INCT-APA, fornecendo informações importantes para a interpretação dos dados obtidos no atual programa de monitoramento desenvolvido na baía do Almirantado. Este estudo integra o projeto do Ano Polar Internacional \"MABIREH\" e contribuirá para bases de dados \"SCAR-MarBin\" e \"ABBED\". / The distribution, composition and some aspects of long-term temporal variation of macrofauna from shallow waters of Admiralty Bay are reasonably well know. The present study aimed to investigate the short-term variation of macrofauna, with emphasis on Polychaeta, in Martel Inlet. Sediment was sampled, at 20 m depth, with a van Veen grab for approximately 35 days, almost every week. During the study period, significant variations were verified on the density of some taxa (Amphipoda and Polychaeta), as well as on the sediment composition. Bivalvia, Amphipoda, Cumacea and Oligochaeta at the first sediment layers were more susceptible to the impact of the severe storms. The dominant species of Polychaeta were Rhodine intermedia, Ophelina syringopyge, O. gymnopyge, Apistobranchus glacierae and Tharyx cf. cincinnatus, counting for 87% of the total group. The density of Ophelina gymnopyge presented a significant short-term variation, however, ecological descriptors for Polychaeta assemblages did not vary at the same way. These results collaborate to the INCT-APA, by providing important information to interpret the acquired data about the environmental monitoring program developed in Admiralty Bay. This study is part of the International Polar Year project \"MABIREH\" and will integrate \"SCAR-MarBin\" and \"ABBED\" data bases.
424

Root-enhanced Infiltration in Stormwater Bioretention Facilities in Portland, Oregon

Hart, Ted David 03 March 2017 (has links)
I evaluated the effectiveness of plant roots to increase infiltration rates within stormwater bioretention facilities (SBFs), roadside planter compartments that filter stormwater. SBFs attenuate harmful effects of stormwater by reducing peak flow and retaining pollutants, with increased infiltration that improves both these functions. Researchers have shown that roots can increase infiltration within greenhouse, lab, field, and test SBF settings. However, no researchers have yet measured either the extent to which different root characteristics can increase infiltration or the variation in root characteristics and their effect on infiltration rates among plant assemblages within currently functioning SBFs. To determine if root-enhanced infiltration was occurring within SBFs, I hypothesized 1) there is a relationship between root characteristics and infiltration during late spring, and 2) seasonal root growth increases infiltration rates. Within Portland, OR, I measured infiltration rate from January 2014 to February 2015 and root characteristics from January-February (J-F) and May-June (M-J) 2014 in ten SBFs with "Elk Blue" rush (Juncus patens) and 1 or 2 trees of less than 8.4 cm stem diameter. During M-J, four root characteristics showed a positive relationship with infiltration rate, and two root characteristics showed a strong positive relationship with infiltration rate within the topsoil. Also, a relationship was shown between the increase (J-F to M-J 2014) in three root characteristics and the increase in infiltration rate. To determine if root morphology and infiltration rates differed among SBFs with two different dominant vegetation taxa (small and large root biomass), I hypothesized 3) Juncus patens and tree dominant assemblage (greater root biomass) exhibits greater infiltration compared to the Carex dominant assemblage, 4) the increase in infiltration rate and root characteristics from J-F to M-J is greater in the Juncus compared to the Carex assemblage, and 5) root surface area density (RSAD) within Juncus SBFs shows a positive relationship with infiltration rate in late spring. I measured infiltration rate from January 2014 to February 2015 and root characteristics from January-February (J-F) and May-June (M-J) 2014 among five large-root (Juncus and tree) and five small-root biomass (Carex sp) SBFs. Juncus SBFs showed greater values for three root characteristics during J-F and five root characteristics during M-J 2014 compared to Carex SBFs. Also, Juncus SBFs showed an increase from J-F to M-J 2014 for five root characteristics while Carex SBFs showed no root increase. Juncus SBFs showed a relationship with four root characteristics and Carex SBFs a showed relationship with one root characteristic and infiltration rate. This work strongly suggests plant roots increase infiltration, and thus the primary functions of SBFs. Different root characteristics appear to increase infiltration rate at different depths. Data also show larger-root biomass plants increase infiltration rate to a greater degree than smaller-root biomass plants. I recommend considering several site and facility characteristics when determining the potential for root-enhanced infiltration. When selecting plant species to enhance infiltration, I recommend using several criteria, determining root characteristic values at certain depths, considering installation approaches, and accounting for regional climate changes.
425

Förekomst av mikroplast i dagvatten : En jämförande studie av dagvatten från vägtrafik och konstgräs i Uppsala / Prevalence of Microplastics in Storm water : A Comparative Study of Storm water Runoff from traffic roads and artificial turfs in Uppsala

Trinh, Yvonne January 2019 (has links)
Material av plast är praktiska och användbara, vilket medför att de återfinns i många produkter som används i vardagen. På grund av dess egenskaper har framställning av produkter och användning av plast ökat sedan massproduktionen av plast började. Mikroplast definieras som plastobjekt med en storlek mindre än 5 millimeter. Eftersom att material av plast förekommer i många produkter så har det lett till en spridning av mikroplast som påträffas på flertalet platser i naturen runtom i världen. Svenska Miljöinstitutet, IVL, har granskat kartlagda uppkomstkällor till och spridningen av mikroplaster i Sverige. De två största landbaserade källorna till mikroplast är slitage av vägbanor och däck respektive mikroplast från konstgräsplaner. Utifrån kartläggningen sker spridning vidare till omgivningen och därför är det angeläget att undersöka belastningen som kan förekomma i dagvattnet från dessa källor. I den här studien har mängden mikroplast undersökts med en minsta storleksfraktion på 100 mikrometer i dagvatten från trafikvägen Bolandsgatan och konstgräsplanen Stenhagens IP i Uppsala. Provtagning utfördes på dagvatten i dagvattenbrunnar genom att ta stickprov och med en provtagare som möjliggjorde flödesproportionell provtagning. Insamlade prover filtrerades där mikroplast sedan analyserades visuellt i stereomikroskop. Analysen av mikroplast kombinerades även med ett smälttest. I undersökningen av den trafikerade vägen Bolandsgatan var 98 % av alla partiklar svarta. De svarta partiklarna kategoriserades som mikroplast som har uppkommit i samband med slitage av vägtrafik. Vid undersökning av konstgräsplanen Stenhagens IP påträffades ett gräsfragment som kategoriserades som mikroplast från konstgräsplanen.  Mikroplastmängden i dagvatten från den trafikerade vägen Bolandsgatan erhölls till 33 kg/år. Emissionsfaktorn för blandad trafik beräknades till 2,2∙10-5 kg/fordonskm. Emissionsfaktor för mikroplast från däck, som beräknats utifrån mätningar i dagvatten från vägtrafik, har inte presenterats i tidigare studier. Från vägtrafiken i Uppsala kommun och Sverige erhölls mängden till 27 000 kg/år respektive 1,5∙106 kg/år. Från konstgräsplanen Stenhagens IP var mängden mikroplast 6,3∙10-2 kg/år. Från konstgräsplaner i Uppsala kommun och Sverige erhölls mängden till 0,56 kg/år respektive 48 kg/år. Vid beräkning av mikroplastmängder finns det en osäkerhet i bestämningen av volymen, ökar partikelradien med en faktor 2 så ökar volymen 8 gånger. Enligt den här studien är mikroplastmängder från vägtrafik i Sverige ungefär 5 gånger mindre än Naturvårdsverkets uppskattning, mängder från konstgräsplaner i Sverige är ungefär 30-50 gånger mindre än Naturvårdsverkets resultat. / Materials made from plastic are practical and durable, therefore plastic is found in many every day products. Because of the properties of plastics, the manufacturing of products and usage of the material has increased consequently leading to the creations of microplastics in varying sizes. The definition of microplastics is plastic materials with a size smaller than 5 millimeters. Because of a huge prevalence in products the consequence is microplastics being found on many places in nature around the world. The Swedish Environmental Research Institute, IVL, has been assigned by the Swedish Environmental Protection Agency to review identified origins and the pathways of microplastics in Sweden. According to the study the largest source of microplastics from outdoor activities on land is from road wear and the abrasion of tyres followed by artificial turfs. Since microplastics are presumed to be spread to the environment, it is of concern to investigate potential microplastic load in storm water from these sources. The investigation of microplastic amounts has been studied in sizes ≥100 micrometres in storm water from the traffic road Bolandsgatan and the artificial turf Stenhagens IP in Uppsala. Samples were collected, using random sampling and with an automatic sampler enabling flow proportional sampling. Filtration of collected water samples were carried out followed by analysing microplastic visually in a stereo microscope. The analyses of microplastics were also combined with a melting test. In the study of the traffic road Bolandsgatan 98 % of all particles were black colored. The black colored particles were identified as microplastic originated from road wear. When studying the artificial turf Stenhagens IP a grass fragment was identified as microplastic originated from the artifical turf. Microplastic amounts from the traffic road Bolandsgatan are 33 kg/year. The emission factor for mixed fleet is 2.2∙10-5 kg/vehicle km. An emission factor for microplastic from road traffic has not been presented in other studies before. The amount of microplastics from road traffic in Uppsala was estimated to 27 000 kg/year and in Sweden to 1.5∙106 kg/year. From the artificial turf Stenhagens IP the amount was 6.3∙10-2 kg/year. By upscaling the amounts of microplastics from artificial turfs in Uppsala and Sweden the amounts were estimated to 0.56 and 48 kg/year, respectively. According to this study, the spread of microplastic from road traffic in Sweden is 5 times less than the estimated value and the amount from artificial turfs is 30-50 times less compared to the investigation by the Swedish Environmental Protection Agency.
426

Naturliga filtermaterial för reduktion av metaller i dagvatten

Skogsfjord, Michael, Blom, Minna January 2006 (has links)
<p>Förorenat dagvatten från Stena Gotthards metallåtervinningsanläggning i Eskilstuna har filtrerats genom kolonner innehållande två olika adsorbenter, torv och furubarksflis. Torv är en organisk jordart som främst används som bränsle och furubarksflis är en biprodukt från skogsindustrin. Båda filtermaterialen är relativt billiga och finns i stora kvantiteter i Sverige. Filtermaterialen har visat sig ha varierande kapacitet att adsorbera metaller i vatten på grund av själva materialet samt vattnets sammansättning. Resultatet från den här studien visar att av de två undersökta filtermaterialen så har furubarksflis störst kapacitet att reducera bly, koppar och zink från det specifika dag vattnet.</p> / <p>Polluted storm water from a metal recycling industry has been filtrated through columns that contained two different adsorbents, peat and pine bark. Peat is an organic soil, mainly used for energy production, and pine bark, a by-product from the forest industry. In Sweden, there are a lot of resources of peat as well as pine bark. Used as filter materials, they are relatively cheep and, like other kinds of filtermaterial used as adsorbents, they have varied capacity to adsorb metals in water. The capacity for the filter materials to adsorb metals depends on the physical structure and chemical contents of the peat and pine bark as well as the water metal composition. Results from this study show that pine bark had the highest adsorption capacity to reduce copper, lead and zinc from the specific storm water.</p>
427

Metodik för beräkning av anslutna hårdgjorda ytor till spillvattennätet / Techniques for calculation of impervious surfaces connected to the sewer system

Larsson, Johan January 2010 (has links)
<p>Sveriges avloppsledningsnät förnyas och utvidgas kontinuerligt. Idag finns ett flertal datorprogram för hydraulisk modellering av flöden och uppdämningsnivåer i spill- och dagvattennät. Modellerna kan även användas som planeringsverktyg för att bedöma effekter av planerade åtgärder samt för uppföljning av utförda åtgärder. Vid uppbyggnaden av en modell krävs beräkningsresultat från en hydrologisk avrinningsmodell som indata. Det största arbetet vid modelluppbyggandet ligger just i beskrivningen av hydrologin. För att kunna simulera avrinningsförlopp i samband med nederbörd på ett verklighetsliknande sätt är kännedom om storleken på och fördelningen av anslutna hårdgjorda ytor till ledningsnätet med snabb nederbördsavrinning väsentligt. </p><p> </p><p>Till kalibreringen och valideringen av avloppsmodellen krävs mätdata. Flödesmätningar är dyra att genomföra vilket har skapat ett intresse att hitta metoder som säkert beräknar de anslutna hårdgjorda ytorna redan från de uppgifter som finns på kartor och i databaser. Svenska riktlinjer för beräkning av hårdgjorda ytor tillhandahålls av branschorganisationen Svenskt Vatten som företräder VA-verken och VA-bolagen i Sverige. Beräkningar med dessa riktlinjer ger dock inte alltid den korrekta storleken på de hårdgjorda ytorna. Syftet med examensarbetet har varit att undersöka olika metoder att beräkna anslutna hårdgjorda ytor till spillvattennätet samt att undersöka huruvida det finns ett samband mellan de avrinningsområden där beräkningarna av de hårdgjorda ytorna inte stämmer. Nio befintliga modeller framtagna i modelleringsverktyget MIKE URBAN användes vid undersökningen. Sex av dessa modeller användes till kalibrering och tre modeller användes till validering.</p><p> </p><p>Undersökningen visade inget samband mellan ytavrinning (reduktionsfaktor) och lutning. Fördelningen av mätpunkter mellan olika jordartskategorier var väldigt ojämn vilket gjorde det svårt att studera huruvida det finns ett samband mellan avrinning och jordart. Resultatet från undersökningen visar att avrinningskoefficienter bör delas upp efter typ av ledningsnät i avrinningsområdet. Metoden med olika avrinningskoefficienter för olika typer av ytor visar på bra resultat för tätbebyggda områden. Metoden med sammanvägda avrinningskoefficienter för olika bebyggelsetyper visar relativt bra resultat med tanke på att det är en överslagsberäkningsmetod.</p><p> </p><p>För tätbebyggda områden bedöms metoden med avrinningskoefficienter för olika typer av ytor fungera bra. Vid mindre tätbebyggda områden ökar osäkerheten. Metoden med sammanvägda avrinningskoefficienter för olika bebyggelsetyper bedöms fungera väl för överslagsberäkningar då den är mindre tidskrävande än den andra metoden. Ingen av de undersökta metoderna bedöms kunna ersätta flödesmätningar. </p> / <p>Sweden’s sewage systems are continuously being maintained and expanded. Several computer programs are today available for hydraulic modeling in sewage and storm water systems. The models can also be used as a planning tool to evaluate effects of planned interventions and to follow up performed interventions. Input data from a runoff model is required at the model build-up. Most of the work in model build-up lies at the description of the hydrology. In order to simulate runoff processes in connection with precipitation, understanding of the size and distribution of impervious surfaces with fast response runoff are essential.</p><p> </p><p>Measurements are required for the calibration and validity check of the model. Unfortunately, flow measurements are expensive to perform. This has created an interest to find methods that safely calculate the connected impervious surfaces already from the information that can be found in maps and in databases. The Swedish guidelines for calculation of impervious surfaces are provided by the Swedish Water and Wastewater Association. Calculations with these guidelines do not always give the true size of the impervious surfaces. The aim of this master thesis was to examine various methods to calculate impervious surfaces connected to the sewage system and whether there is a correlation between drainage areas where the calculations do not agree. Nine existing models developed in the computer program MIKE URBAN were used in this study. Six of these models were used in the calibration and three models were used in the validity check of the methods.</p><p> </p><p>The study did not show any correlation between runoff (reduction factor) and slope. The distribution of datum points between different soil types varied so much that it made it difficult to study whether there was correlation between runoff and soil type. The result from the study showed that the runoff coefficients should be divided after type of sewage system in the drainage area. The method with runoff coefficients for different types of surfaces showed fairly good results for highly urbanized areas. The method with weighted runoff coefficients for different types of habitations showed relatively good results considering that it is a method for rough calculations.</p><p> </p><p>The method with runoff coefficients for different types of surfaces is considered well-functioning for highly urbanized areas. In less urbanized areas, this method showed shorter results. The method with weighted runoff coefficients for different types of habitations is considered well for rough calculations when it is less time consuming than the other method. None of the examined methods are considered able to replace flow measurements.</p>
428

Desarrollo de un sistema de tratamiento del agua de escorrentía superficial procedente de aparcamientos impermeables usando flujo ascendente y geotextiles

Fernández Barrera, Andrés H. 18 February 2010 (has links)
Esta tesis doctoral presenta la investigación del desarrollo de un prototipo de laboratorio de un sistema de captación, pretratamiento y tratamiento (SCPT) de la escorrentía proveniente de aparcamientos con firmes impermeables. El prototipo de SCPT fue estudiado en condiciones de funcionamiento inicial y a largo plazo. Las respuestas analizadas son las concentraciones de aceites y sólidos en el efluente y las eficiencias de depuración de dichos contaminantes. Finalmente, se analizó la capacidad del sistema de filtrado del SCPT para albergar colonias de microorganismos depuradores de hidrocarburos. Los niveles de depuración alcanzados por el prototipo de SCPT son superiores al 80% para el caso de los sólidos y al 90 % para los aceites, tanto en condiciones de inicio de operación, como a largo plazo tras catorce eventos de lluvia consecutivos. Además, se demostró que el sistema de filtrado es capaz de albergar colonias de microorganismos degradadores de hidrocarburo
429

Assessing coastal vulnerability: Advanced modeling methods and dynamic hydraulic characteristics of Gulf Coastal systems

January 2012 (has links)
The United States coastline contain some of the most valued ecological resources, the most populated urban areas, the most complex infrastructure systems, the most prolific economic engines, and the busiest ports of trade. However important the coastline may be to our nation, the history of our coastal communities suggests that they are extremely vulnerable to natural disasters, including hurricane landfall. There are many potential reasons for this vulnerability, and several of them are considered in this work. The common goal of research presented here is to better understand the hydrodynamic forces developed as hurricanes impact the coast so that the resulting effects on coastal resources can be better understood and managed, and vulnerability can be significantly minimized. This work begins with consideration of the hydraulic domain at the interface between inland riverine and coastal environments. Regulators, and therefore those being regulated, generally prefer to separate riverine systems from coastal systems in the design and analysis of coastal infrastructure. Although analysis is greatly simplified, important synergistic hydrodynamic effects are not considered which can have dramatic negative effects on the ability of infrastructure to withstand hurricane impact. Research continues by evaluating how society delineates the coastal flood hazard. Current methods apply a deterministic, steady-state approach to defining this highly dynamic feature influenced by multiple uncertain and variable parameters. By ignoring the variability inherent in the coastal floodplain, society is not able to correctly define the flood hazard, and therefore cannot fully asses the risk to which it is exposed. A methodology is presented to more realistically quantify the coastal flood hazard and to calculate an appropriate flood risk metric. Finally, this research considers the reliability of a coastal community's water distribution system under hurricane impact. By understanding system vulnerability and system interdependence, community leaders can provide more reliable infrastructure systems, thereby reducing the magnitude of disaster and shortening the recovery time. A methodology is presented to quantify the reliability of a water system under several hurricane impact scenarios.
430

Naturliga filtermaterial för reduktion av metaller i dagvatten

Skogsfjord, Michael, Blom, Minna January 2006 (has links)
Förorenat dagvatten från Stena Gotthards metallåtervinningsanläggning i Eskilstuna har filtrerats genom kolonner innehållande två olika adsorbenter, torv och furubarksflis. Torv är en organisk jordart som främst används som bränsle och furubarksflis är en biprodukt från skogsindustrin. Båda filtermaterialen är relativt billiga och finns i stora kvantiteter i Sverige. Filtermaterialen har visat sig ha varierande kapacitet att adsorbera metaller i vatten på grund av själva materialet samt vattnets sammansättning. Resultatet från den här studien visar att av de två undersökta filtermaterialen så har furubarksflis störst kapacitet att reducera bly, koppar och zink från det specifika dag vattnet. / Polluted storm water from a metal recycling industry has been filtrated through columns that contained two different adsorbents, peat and pine bark. Peat is an organic soil, mainly used for energy production, and pine bark, a by-product from the forest industry. In Sweden, there are a lot of resources of peat as well as pine bark. Used as filter materials, they are relatively cheep and, like other kinds of filtermaterial used as adsorbents, they have varied capacity to adsorb metals in water. The capacity for the filter materials to adsorb metals depends on the physical structure and chemical contents of the peat and pine bark as well as the water metal composition. Results from this study show that pine bark had the highest adsorption capacity to reduce copper, lead and zinc from the specific storm water.

Page generated in 0.0648 seconds