Sökning: "active scalar"

Visar resultat 1 - 5 av 7 avhandlingar innehållade orden active scalar.

  1. 1. Turbulence modeling of compressible flows with large density variation

    Författare :Igor Grigoriev; Arne Johansson; Stefan Wallin; Geert Brethouwer; Stefan Hickel; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbulence; DRSM; EARSM; active scalar; compressible flow; reacting flow; supercritical flow; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : In this study we highlight the influence of mean dilatation and mean density gradient on the Reynolds stress modeling of compressible, heat-releasing and supercritical turbulent flows.Firstly, the modeling of the rapid pressure-strain correlation has been extended to self-consistently account for the influence of mean dilatation. LÄS MER

  3. 2. Modeling and Linear Quadratic Optimal Control of Wind Turbines

    Författare :Thommy Ekelund; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; periodic system; structural dynamics; yaw control; variable speed; wind turbines; active stall; estimation; LQG; identification;

    Sammanfattning : Control can improve the performance of wind turbines by enhancing the energy capture and reducing dynamic, as well as static, loads. There are several possible configurations of the control system, depending on the available actuators. LÄS MER

  4. 3. Mapping Primary Production for the West African Sahel with Satellite Data

    Författare :Jonathan Seaquist; Institutionen för naturgeografi och ekosystemvetenskap; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physical geography; Sahel; CENTURY; Monte Carlo; GPP; transpiration; LUE; CLAVR; PAR; compositing; MVC; geostatistics; noise; NDVI; NOAA AVHRR; geomorphology; pedology; cartography; climatology; Fysisk geografi; geomorfologi; marklära; kartografi; klimatologi;

    Sammanfattning : A light Use Efficiency (LUE) model is developed that allows the mapping of total growing season Gross Primary Production (GPP) for the West African Sahel, using the Normalized Difference Vegetation Index (NDVI) together with other data. Image quality may be poor in monthly NDVI maximum value composites as shown by an improved geostatistical noise estimation technique. LÄS MER

  5. 4. Revenue Maximization in Resource Allocation : Applications in Wireless Communication Networks

    Författare :Nilo Casimiro Ericsson; Anders Ahlén; Mikael Sternad; Jens Zander; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Signalbehandling; wireless; resource; scheduling; revenue; admission control; service level control; service level agreement; Signalbehandling; Signal processing; Signalbehandling; Signal Processing; signalbehandling;

    Sammanfattning : Revenue maximization for network operators is considered as a criterion for resource allocation in wireless cellular networks. A business model encompassing service level agreements between network operators and service providers is presented. LÄS MER

  7. 5. Robust Multimedia Communications over Packet Networks

    Författare :Guoqiang Zhang; W. Bastiaan Kleijn; Vinay Vaishampayan; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Telecommunication; Telekommunikation;

    Sammanfattning : Multimedia communications over packet networks, and in particular the voice over IP (VoIP) application, have become an integral part of society. However, the unreliable and heterogeneous nature of packet networks has led to a best-effort delivery of services. LÄS MER