Avancerad sökning

Visar resultat 1 - 5 av 164 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Groundwater Recharge in Crystalline Bedrock : Processes, Estimation, and Modelling

   Författare :Niclas Bockgård; Sven Halldin; Allan Rodhe; Auli Niemi; Lars O. Ericsson; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Hydrology; groundwater recharge; bedrock; crystalline rocks; tracers; CFC; surface loading; loading efficiency; barometric effect; heterogeneity; stochastic modelling; Hydrologi; Hydrology; Hydrologi;

   Sammanfattning : Kunskap om grundvattenbildningen är nödvändig för att man ska kunna förutsäga konsekvenserna av grundvattenuttag och underjordsbyggande. Grundvattenbildningen i berggrunden är dock svår att uppskatta. LÄS MER

3. 2. Estimering av efterfrågan på långväga persontransporter : En ekonomisk-teoretisk belysning av gängse modeller samt en ny ansats till uppskattning av efterfrågesamband

   Författare :Thomas Sonesson; Linköpings universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Intercity travel demand; gravity model; legit model; entropy maximising; BoxCox; demand elasticities;

   Sammanfattning : This dissertation deals with the estimation of intercity travel demand. The purpose is to discuss the derivations and characteristics of existing models, to derive a demand model based on microeconomic theory and to estimate the parameters of the model in order to gain information on important characteristics of the transport system. LÄS MER

4. 3. Reliability-based fatigue assessment of existing steel bridges

   Författare :Ruoqi Wang; John Leander; Raid Karoumi; John Dalsgaard Sørensen; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fatigue; steel bridges; reliability analysis; spatial correlation; risk analysis; Monte Carlo simulation; Utmattning; stålbroar; tillförlitlighet; rumslig korrelation; riskanalys; Monte Carlo-simulering; Structural Engineering and Bridges; Bro- och stålbyggnad;

   Sammanfattning : Fatigue is among the most critical forms of deterioration damage that occurs tosteel bridges. It causes a decline of the safety level of bridges over time. Therefore,the performance of steel bridges, which may be seriously affected by fatigue, shouldbe assessed and predicted. LÄS MER

5. 4. Strong Cosmic Censorship and Cosmic No-Hair in spacetimes with symmetries

   Författare :Katharina Maria Radermacher; Hans Ringström; James Isenberg; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Cosmic Censorship; Cosmic No-Hair; Big Bang; symmetry; Bianchi; T2-symmetry; Gowdy; general relativity; cosmology; late time; initial time; asymptotic behaviour; perfect fluid; scalar field; Einstein equations; Mathematics; Matematik;

   Sammanfattning : This thesis consists of three articles investigating the asymptotic behaviour of cosmological spacetimes with symmetries arising in Mathematical General Relativity.In Paper A and B, we consider spacetimes with Bianchi symmetry and where the matter model is that of a perfect fluid. LÄS MER

7. 5. Observational Uncertainties in Water-Resources Modelling in Central America : Methods for Uncertainty Estimation and Model Evaluation

   Författare :Ida Westerberg; Sven Halldin; Jan Seibert; Lars-Christer Lundin; Chong-Yu Xu; Deliang Chen; Alberto Montanari; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Central America; Discharge; Flow-duration curve; Fuzzy regression; GLUE; Model evaluation; Non-stationarity; Observational uncertainty; Precipitation; Quality control; Rating curve; Regionalisation; Uncertainty estimation; Ungauged basins; Water resources; Avbördningskurva; Centralamerika; GLUE; icke-stationaritet; kvalitetskontroll; modellutvärdering; nederbörd; observationsosäkerheter; avrinningsområden utan vattenfö-ringsdata; oskarp regression; osäkerhetsuppskattning; regionalisering; varaktighetskurva; vattenföring; vattenresurser; Hydrology; Hydrologi; Hydrology; Hydrologi;

   Sammanfattning : Knowledge about spatial and temporal variability of hydrological processes is central for sustainable water-resources management, and such knowledge is created from observational data. Hydrologic models are necessary for prediction for time periods and areas lacking data, but are affected by observational uncertainties. LÄS MER