Search for dissertations about: "gate valves"

Found 4 swedish dissertations containing the words gate valves.

2. 1. Heterogeneous Integration of Shape Memory Alloysfor High-Performance Microvalves

   Author : Henrik Gradin; Göran Stemme; Peter Woias; KTH; []
   Keywords : Microelectromechanical systems; MEMS; silicon; wafer-level; integration; heterogeneous integration; wafer bonding; Au-Si; eutectic bonding; release etching; electrochemical etching; microvalves; microactuators; shape memory alloy; SMA; NiTinol; TiNi; NiTi; cold-state reset; bias spring; gate valves; wire bonding;

   Abstract : This thesis presents methods for fabricating MicroElectroMechanical System (MEMS) actuators and high-flow gas microvalves using wafer-level integration of Shape Memory Alloys (SMAs) in the form of wires and sheets. The work output per volume of SMA actuators exceeds that of other microactuation mechanisms, such as electrostatic, magnetic and piezoelectric actuation, by more than an order of magnitude, making SMA actuators highly promising for applications requiring high forces and large displacements. READ MORE

4. 2. Magnetodynamics in Spin Valves and Magnetic Tunnel Junctions with Perpendicular and Tilted Anisotropies

   Author : Quang Tuan Le; Johan Åkerman; Erik Wahlström; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; perpendicular magnetic anisotropy; tilted-polarizer; spintronics; STT; MTJ; pseudospin-valve; STO; ST-FMR; magnonics; magnetic droplet; droplet nucleation; droplet annihilation; vinkelrät magnetisk anisotropi; lutande polarisator; spinntronik; STT; MTJ; pseudospinnventil; STO; ST-FMR; magnonics; magnetisk droppe; nukleering av droppe; anihilering av droppe.; Physics; Fysik;

   Abstract : Spin-torque transfer (STT) effects have brought spintronics ever closer to practical electronic applications, such as MRAM and active broadband microwave spin-torque oscillator (STO), and have emerged as an increasingly attractive field of research in spin dynamics. Utilizing materials with perpendicular magnetic anisotropy (PMA) in such applications offers several great advantages such as low-current, low-field operation combined with high thermal stability. READ MORE

5. 3. On Design of a Compact Primary Switched Conversion System for Electric Railway Propulsion

   Author : Tommy Kjellqvist; Stefan Östlund; Alfred Rufer; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Isolated AC DC converter; Mutual commutation; Soft Switching; Cyclo converter; Medium-Frequency Transformer; Electric Railway Propulsion; Electrical engineering; Elektroteknik;

   Abstract : In this thesis, a compact and light primary switched conversion system for AC-fed railway propulsion is investigated. It is characterized by soft switching of all converter stages and a source commutated primary converter comprising series connected valves. READ MORE

6. 4. On the Mechanisms behind the Tribological Performance of Stellites

   Author : Daniel H. E. Persson; Sture Hogmark; Staffan Jacobson; Mikael Olsson; Uppsala universitet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Materials science; Stellite; Co-based; phase transformation; fcc; hcp; texture; alignment; low-friction; laser cladding; Materialvetenskap; Materials science; Teknisk materialvetenskap;

   Abstract : This thesis reveals the tribological mechanisms behind the intrinsic low friction potential of the Co-based family of alloys called Stellites. Although being an established and important group of materials, a satisfactory explanation to why they exhibit low-friction properties under severe sliding conditions has not previously been found in the literature. READ MORE