Sökning: "oscillations"

Visar resultat 36 - 40 av 475 avhandlingar innehållade ordet oscillations.

1. 36. Self Oscillations and Cooling of Carbon Based NEMS Devices

   Författare :Anders Nordenfelt; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; nano electro-mechanics; carbon nanotubes;

   Sammanfattning : We investigate the electromechanical properties of a number of system geometries featuring a doubly clamped Carbon Nanotube or Graphene sheet with a deflection sensitive resistance and an electronic feedback in the form of a Lorentz force or an electrostatic attraction. The nanotube is subjected to a constant current- or voltage bias and it is shown that when the electro-mechanical coupling exceeds a certain critical value the system becomes unstable to self-excitations of the mechanical vibrations accompanied by oscillations in the voltage drop and current through the nanotube. LÄS MER

3. 37. Analysis of Sub-Synchronous Oscillations in Wind Power Plants

   Författare :Muhammad Taha Ali; Mehrdad Ghandari; Massimo Bongiorno; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Doubly fed Induction generator; eigenvalue analysis; sub-synchronous control interaction; voltage source converter; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : The modern power system is moving towards the high integration of renewable energy sources at a fast pace. The integration of wind power in the power system raises many challenges along with the benefits. One of the recent challenges is the sub-synchronous oscillation (SSO) that occurs in doubly-fed induction generator (DFIG) based wind farms. LÄS MER

4. 38. Oscillatory Ca2+ signaling in glucose-stimulated murine pancreatic β-cells : Modulation by amino acids, glucagon, caffeine and ryanodine

   Författare :Meftun Ahmed; Per Lindström; Uppsala universitet; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Cell biology; pancreatic β-cells; islets of Langerhans; glucose; Ca2 oscillations; Ca2 transients; potassium; ryanodine; caffeine; glucagon; cAMP; inositol 1; 4; 5-trisphosphate; fura-2; glycine; alanine; arginine; Ca2 channels; rats; lean mice; ob ob mice; leptin; Cellbiologi; Cell biology; Cellbiologi; medicinsk cellbiologi; Medical Cell Biology;

   Sammanfattning : Oscillations in cytoplasmic Ca2+ concentration ([Ca2+]i) is the key signal in glucose-stimulated β-cells governing pulsatile insulin release. The glucose response of mouse β-cells is often manifested as slow oscillations and rapid transients of [Ca2+] i. LÄS MER

5. 39. Dynamics of quarks and leptons : theoretical Studies of Baryons and Neutrinos

   Författare :Tommy Ohlsson; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chiral quark model; baryons; conguration mixing; magnetic moments; Coleman{Glashow sum-rule; spin structure; spin polarizations; weak form factors; semileptonic decays; nucleon quark sea isospin asymmetry; neutrinos; neutrino oscillations; neutrino avors; mixing angles; mass squared dierences; MSW eect; numerical calculations; interpretation of experiments; Mathematical physics; Matematisk fysik;

   Sammanfattning : The Standard Model of Elementary Particle Physics (SM) is the present theoryfor the elementary particles and their interactions and is a well-established theorywithin the physics community. The SM is a combination of Quantum Chromodynamics(QCD) and the Glashow{Weinberg{Salam (GWS) electroweak model. LÄS MER

7. 40. Theoretical and Phenomenological Studies of Neutrino Physics

   Författare :Mattias Blennow; Tommy Ohlsson; Eligio Lisi; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; neutrino mass; neutrino mixing; neutrino oscillations; matter effects; non-standard effects; the day-night effect; solar neutrinos; accelerator neutrinos; exact solutions; three-flavor effects; large density; neutrino decay; neutrino decoherence; neutrino absorption; non-standard neutrino interactions; seesaw mechanism; stability criteria; leptogenesis; Physics; Fysik;

   Sammanfattning : This thesis is devoted to the theory and phenomenology of neutrino physics. While the standard model of particle physics has been extremely successful, it fails to account for massive neutrinos, which are necessary to describe the observations of neutrino oscillations made by several different experiments. LÄS MER