Sökning: "matematiska modeller"

Visar resultat 21 - 25 av 123 avhandlingar innehållade orden matematiska modeller.

  1. 21. Multiphase models for freeze-thaw actions and mass transport in concrete hydraulic structures

    Författare :Daniel Eriksson; Anders Ansell; Richard Malm; Erik Nordström; Stefan Jacobsen; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Degradation; Hydraulic structures; Air-entrained concrete; Multiphase models; Multiphysics; Long-term moisture conditions; Freeze-thaw; Hysteresis; Absorption; Calcium leaching; Finite Element Method; Concrete Structures; Betongbyggnad;

    Sammanfattning : A crucial task for civil engineers is to make appropriate designs of new concrete structures and assessments of existing structures to ensure a long service life and sustainable use of the infrastructure. This doctoral thesis aims to increase the understanding of how advanced mathematical models can be used to describe phenomena and processes governing concrete degradation and thereby ultimately contribute to improving tools for design and assessments. LÄS MER

  3. 22. Satistical Modelling Of CO2 Exchange Between Land And Atmosphere : Using Stochastic Optimisation And Gaussian Markov Random Fields

    Författare :Unn Dahlén; Spatio-Temporal Stochastic Modelling Group; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Gaussiska Markovfält; Stokastisk optimering; CO2-flöden; Spatial statistik; Stochastic Optimisation; Gaussian Markov Random Fields; Atmospheric inverse modelling; Spatial statistics; Computational statistics;

    Sammanfattning : This thesis focuses on the development and application of efficient mathematicaltools for estimating and modelling the exchange of carbon dioxide (CO2) between the Earth and its atmosphere; here referred to as the global CO2 surface flux.There are two main approaches for estimating the CO2 flux: Processed based(bottom-up) modelling and atmospheric inversion (top-down) modelling. LÄS MER

  4. 23. Digital twinning for ports : from characterization to operations’ modelling

    Författare :Robert Klar; Vangelis Angelakis; Anna Fredriksson; Anders Andersson; Niklas Arvidsson; Theo Tryfona; Statens väg- och transportforskningsinstitut; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Digital twins; Ports; Operational efficiency; Collaborative decision-making; Port decarbonization;

    Sammanfattning : Ports are actively pursuing greater operational efficiency to effectively handle the increasing global flow of goods, while striving to improve the energy efficiency of their operations to comply with new environmental regulations. As a result, innovation-leading ports have begun to recognize the potential of digital twins to overview, coordinate and optimize port processes, resulting in energy savings, and reductions of costs and of CO2 emissions. LÄS MER

  5. 24. European ecosystems on a changing planet : Integrating climate change and land-use intensity data

    Författare :Jan Hendrik Blanke; Institutionen för naturgeografi och ekosystemvetenskap; []
    Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; LPJ-GUESS; land-use intensity; climate change; carbon; nitrogen; ecosystem functions; trade-offs; vegetation;

    Sammanfattning : Dynamic global vegetation models are mathematical models that provide a bottom-up description of plant communities. They explicitly model physiological and population-level processes such as growth, photosynthesis, carbon allocation, regeneration and mortality. LÄS MER

  7. 25. Design and Implementation of Object-Oriented Model Libraries using Modelica

    Författare :Hubertus Tummescheit; Institutionen för reglerteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; modeling languages; thermo-fluid systems; process modeling; process control; control systems; thermo-hydraulic systems; non-linear models; model library design; object-oriented; modeling; simulation; Automation; robotics; control engineering; Automatiska system; robotteknik; reglerteknik;

    Sammanfattning : This thesis describes basic models for thermo-fluid systems and the implementation of the models using a flexible object-oriented structure in the ThermoFluid library. Model libraries provide an excellent way to package engineering knowledge of systems to be reused by non-experts. LÄS MER