Sökning: "drag reduction"

Visar resultat 36 - 40 av 57 avhandlingar innehållade orden drag reduction.

  1. 36. Numerical simulation of multi-scale transport processes and reactions in pem fuel cells using two-phase models

    Författare :Munir Khan; Jinliang Yuan; Bengt Sundén; Värmeöverföring; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; numerical analysis; multi-scale; multi-phase; reacting flows; multi-component;

    Sammanfattning : A numerical study for the cathode of a PEM fuel cell has been performed in this study. The results have been limited to cathode only because, in PEM fuel cells, the oxygen reduction reactions, ORRs, are considered the rate limiting reactions and govern the fuel cell performance. LÄS MER

  3. 37. Techniques for Efficient Constraint Propagation

    Författare :Mikael Zayenz Lagerkvist; Seif Haridi; Christian Schulte; Pierre Flener; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; constraint programming; constraint propagation; optimization; Computer science; Datalogi;

    Sammanfattning : This thesis explores three new techniques for increasing the efficiency of constraint propagation: support for incremental propagation, improved representation of constraints, and abstractions to simplify propagation.  Support for incremental propagation is added to a propagator centered propagation system by adding a new intermediate layer of abstraction, advisors, that capture the essential aspects of a variable centered system. LÄS MER

  4. 38. FE modelling of friction connections in tubular tower for wind turbines

    Författare :Marouene Limam; Jean-Francois Demonceau; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Steel Structures; Stålbyggnad;

    Sammanfattning : During the last few decades the demand for renewable energy has led to a myriad of innovative solutions. The present assembling solution between two segments of a tubular tower is accomplished by conventional ring flange connection. This connection suffers from economical and technological barriers. LÄS MER

  5. 39. The process atmosphere as a parameter in the Laser-Powder Bed Fusion process

    Författare :Camille Nicole Géraldine Pauzon; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; process stability; 316L stainless steel; Ti-6Al-4V; Laser-Powder Bed Fusion; processing atmosphere; process control; powder degradation; Additive Manufacturing;

    Sammanfattning : Laser-Powder Bed Fusion (L-PBF) is an Additive Manufacturing (AM) technique that allows to produce near-net shape components of complex design. Applied to metallic materials, L-PBF allows to consolidate subsequent layers of powder using the heat from laser radiation. LÄS MER

  7. 40. Experimental Study on Truck Related Power Losses: The Churning Losses in a Transmission Model and Active Flow Control at an A-pillar of Generic Truck Cabin Model

    Författare :Erwin Adi Hartono; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hot wire anemometry; Machine learning; Computational Fluid Dynamics; A-Pillar; Transmission; Flow separation; Churning losses; CFD; Gearbox; Torque measurement; Particle Image Velocimetry; Smoothed Particle Hydrodynamics.; Active Flow Control; SPH; Curve fit; Synthetic Jets; Load independent power losses; Aeration; Flow visu- alization;

    Sammanfattning : The fight with global warming constantly forces vehicle manufacturers to innovate, in order to be able to reduce the CO2 emissions of their product. This means that marginal efficiency gains in every component are considered beneficial for total reduction of CO2 emissions. LÄS MER