1,640 research outputs found

    Design and evaluation of a virtual gearshift application

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    When a customer buys a new car, he or she wants it to address personal preferences with respect to its driving behavior. By utilizing virtual reality technology, a virtual prototyping environment (VPE) can be created in which the behavior of a vehicle or part of a vehicle can be evaluated and adjusted to match the driver's desires. This paper describes the design and the evaluation of a VPE for manually operated gearboxes. The test group considered the simulated "virtual" gearshift feel to be quite similar to the "real" gearshift feel of a test vehicle. By further developing this VPE, it should become possible to define gearshift feel by customer assessment through haptic simulation, after which the physical gearbox is designed in such a way that it matches the preferred shifting behavior

    Observing Zitterbewegung for photons near the Dirac point of a two-dimensional photonic crystal

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    It is shown, for the first time, that the zitterbewegung of photon can appear near the Dirac point in two-dimensional photonic crystal. The superiority of such a phenomenon for photons is that it can be found in different scaling structures with wide frequency regions. It can be observed by measuring the time dependence of the transmission coefficient through photonic crystal slabs. Thus, it is particularly suited for experimentally observing this effect. We have observed such a phenomenon by exact numerical simulations, confirming a long-standing theoretical prediction

    Magnetic Kronig-Penney model for Dirac electrons in single-layer graphene

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    The properties of Dirac electrons in a magnetic superlattice (SL) on graphene consisting of very high and thin (delta-function) barriers are investigated. We obtain the energy spectrum analytically and study the transmission through a finite number of barriers. The results are contrasted with those for electrons described by the Schrodinger equation. In addition, a collimation of an incident beam of electrons is obtained along the direction perpendicular to that of the SL. We also highlight the analogy with optical media in which the refractive index varies in space.Comment: 21 pages, 13 figures, to appear in New Journal of Physic

    Charge transport through weakly open one dimensional quantum wires

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    We consider resonant transmission through a finite-length quantum wire connected to leads via finite transparency junctions. The coherent electron transport is strongly modified by the Coulomb interaction. The low-temperature current-voltage (IVIV) curves show step-like dependence on the bias voltage determined by the distance between the quantum levels inside the conductor, the pattern being dependent on the ratio between the charging energy and level spacing. If the system is tuned close to the resonance condition by the gate voltage, the low-voltage IVIV curve is Ohmic. At large Coulomb energy and low temperatures, the conductance is temperature-independent for any relationship between temperature, level spacing, and coupling between the wire and the leads

    Critical reflection as a concept and technique of behavioural change

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    Intraband electron focusing in bilayer graphene

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    We propose an implementation of a valley selective electronic Veselago lens in bilayer graphene. We demonstrate that in the presence of an appropriately oriented potential step, low-energy electrons radiating from a point source can be re-focused coherently within the same band. The phenomenon is due to the trigonal warping of the band structure that leads to a negative refraction index. We show that the interference pattern can be controlled by an external mechanical strain.Comment: 14 pages, 8 figure

    Thermoelectric effects in Kondo correlated quantum dots

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    In this Letter we study thermoelectric effects in ultra small quantum dots. We study the behaviour of the thermopower, Peltier coefficient and thermal conductance both in the sequencial tunneling regime and in the regime where Kondo correlations develope. Both cases of linear response and non-equilibrium induced by strong temperature gradients are considered. The thermopower is a very sensitive tool to detect Kondo correlations. It changes sign both as a function of temperature and temperature gradient. We also discuss violations of the Wiedemann-Franz law.Comment: 7 pages; 5 figure
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