Händelser: Centrum Grafenhttp://www.chalmers.se/sv/om-chalmers/kalendariumAktuella händelser på Chalmers tekniska högskolaFri, 20 May 2022 14:53:46 +0200http://www.chalmers.se/sv/om-chalmers/kalendariumhttps://www.chalmers.se/sv/institutioner/mc2/kalendarium/Sidor/michael-hein.aspxhttps://www.chalmers.se/sv/institutioner/mc2/kalendarium/Sidor/michael-hein.aspxImpact of equilibration on the heat conductance and noise of non-Abelian fractional quantum Hall edges<p>C511, seminar room, Kemivägen 9, MC2-huset</p><p>Michael Hein, MPNAT Nanotechnology, presenterar sitt examensarbete med titeln &quot;Impact of equilibration on the heat conductance and noise of non-Abelian fractional quantum Hall edges&quot;​</p><div><strong>Handledare</strong>: Christian Spånslätt Rugarn</div> <div><span style="background-color:initial"><b>Examinator</b>: Janine Splettstößer </span></div> <div><span style="background-color:initial"><strong>Opponent</strong>: Victor Lanai</span><span style="background-color:initial"></span><strong><br /></strong></div> <div><strong><br /></strong></div> <div><strong>Abstrakt: </strong></div> <div>In a sufficiently strong magnetic field, a cold 2D electron gas forms fractional quantum Hall states. These are prominently characterized by a quantized Hall conductance and the appearance of 1D edge</div> <div>channels. Certain states, called non-Abelian, are predicted to have exotic particles with potential use for quantum computation. However, unambiguously identifying these states is experimentally challenging since many measurements cannot uniquely distinguish between theoretical candidate states.</div> <div>In this Master thesis defence, I present how to distinguish between non-Abelian candidates for the 5/2 state with edge transport spectroscopy. My focus lies on computing the heat conductance, the generated noise, and their dependence on the degree of thermal equilibration between the edge channels. I compare these results to recent experimental findings.</div>https://www.chalmers.se/sv/institutioner/mc2/kalendarium/Sidor/athanasios-theodoridis-.aspxhttps://www.chalmers.se/sv/institutioner/mc2/kalendarium/Sidor/athanasios-theodoridis-.aspxCharacterization of Graphene based porous structures for noise damping in transmission systems<p>Fasrummet, meeting room, Kemivägen 9, MC2-huset</p><p>​Athanasios Theodoridis, MPNAT Nanotechnology, presenterar sitt examensarbete med titeln &quot;Characterization of Graphene based porous structures for noise damping in transmission systems&quot;​</p>​<strong style="background-color:initial">Handledare: </strong><span style="background-color:initial">Dr. Yifeng Fu (Chalmers), Dr. Flavio Presezniak (Volvo AB)</span><div><strong>Opponent: </strong><span style="background-color:initial">Awse S. A. Salha</span></div> <div><span style="background-color:initial"><strong>Examinator: </strong></span><span style="background-color:initial"></span><span style="background-color:initial">Prof. Johan Liu</span></div> <div><span style="background-color:initial"><br /></span></div> <div><span style="background-color:initial"><strong></strong></span><span style="background-color:initial"><strong>Abstrakt</strong>: Noise pollution is an environmental issue that has been gaining more and more attention over the last years. Heavy machinery such as trucks are a big contributor to this problem, and stricter environmental regulations drive companies into finding better solutions where they can keep noise levels to a minimum, while still being profitable. Recently developed porous graphene films (PGFs) can be a promising solution, since they are thin, lightweight and industrially produced. Due to their film structure and inherent porosity, in the form of air pockets, they are studied, for the first time, for their potential to be incorporated into today's acoustic applications. In this project, PGFs are investigated in terms of their thermal, structural and acoustical properties. For the first two, several characterization methods are employed, namely a self-heating method, the buoyancy method, tensile stress measurements, BET analysis and SEM imaging, among others. For the latter impedance tube measurements are conducted, in order to investigate the acoustic performance and characterize the PGFs in terms of their acoustic properties. For that matter, both measurements on sample acoustic devices and simulations are employed. Thin membrane-type acoustic devices are designed and fabricated where they exhibit absorption peaks in the low-frequency range and are compared with today's standard acoustic materials that are used in the automotive industry. Additionally, acoustical characterization leads to the estimation of certain material parameters, which are then used in the JCA model to simulate different device configurations. Simulations have shown, that in applications consisting of PU/fabric structures, the substitution of the thin fabric with a graphene film, can improve the sound absorption performance and also shift the absorption peak to lower frequencies. Finally, the recyclability of waste PGFs is investigated, in which graphene film pieces are crushed and shear exfoliated into graphene powder. This graphene powder can later be incorporated into various applications.</span></div> <div><span style="background-color:initial"><br /></span></div> <div><span style="background-color:initial"><br /></span></div>