1,561 research outputs found

    A model for the influence of pressure on the bulk modulus and the influence of temperature on the solidification pressure for liquid lubricants

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    Two pressure chambers, for compression experiments with liquids from zero to 2.2 GPa pressure, are described. The experimentally measured compressions are then compared to theoretical values given by an isothermal model of equation of state recently introduced for solids. The model describes the pressure and bulk modulus as a function of compression for different types of lubricants with a very high accuracy up to the pressure limit of the high pressure chamber used (2.2 GPa). In addition the influence of temperature on static solidification pressure was found to be a simple function of the thermal expansion of the fluid

    An Algebraic Model for the Multiple Meixner Polynomials of the First Kind

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    An interpretation of the multiple Meixner polynomials of the first kind is provided through an infinite Lie algebra realized in terms of the creation and annihilation operators of a set of independent oscillators. The model is used to derive properties of these orthogonal polynomials

    A Quantum Analogue of the Z{\cal Z} Algebra

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    We define a natural quantum analogue for the Z{\cal Z} algebra, and which we refer to as the Zq{\cal Z}_q algebra, by modding out the Heisenberg algebra from the quantum affine algebra Uq(sl(2)^)U_q(\hat{sl(2)}) with level kk. We discuss the representation theory of this Zq{\cal Z}_q algebra. In particular, we exhibit its reduction to a group algebra, and to a tensor product of a group algebra with a quantum Clifford algebra when k=1k=1, and k=2k=2, and thus, we recover the explicit constructions of \uq-standard modules as achieved by Frenkel-Jing and Bernard, respectively. Moreover, for arbitrary nonzero level kk, we show that the explicit basis for the simplest Z{\cal Z}-generalized Verma module as constructed by Lepowsky and primc is also a basis for its corresponding Zq{\cal Z}_q-module, i.e., it is invariant under the q-deformation for generic q. We expect this Zq{\cal Z}_q algebra (associated with \uq at level kk), to play the role of a dynamical symmetry in the off-critical Zk Z_k statistical models.Comment: 32 pages, LATEX, minor change

    A tunable, dual mode field-effect or single electron transistor

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    A dual mode device behaving either as a field-effect transistor or a single electron transistor (SET) has been fabricated using silicon-on-insulator metal oxide semiconductor technology. Depending on the back gate polarisation, an electron island is accumulated under the front gate of the device (SET regime), or a field-effect transistor is obtained by pinching off a bottom channel with a negative front gate voltage. The gradual transition between these two cases is observed. This dual function uses both vertical and horizontal tunable potential gradients in non-overlapped silicon-on-insulator channel

    SOLUTIONS OF THE LANDAU-VLASOV EQUATION IN NUCLEAR PHYSICS

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    The properties of Vlasov equation solutions obtained by projection on coherent state basis are discussed. Such solutions satisfy stationarity conditions and satisfactorily describe the average diffusivity of nuclear phase space and reproduce the bulk properties of nuclei. Sampling methods and their effects on dynamics are discussed for the study of heavy ion reactions at intermediate energies. The non-local Gogny force is easily computable on this basis which allows to use it for dynamical nuclear studies

    A hybrid metal/semiconductor electron pump for quantum metrology

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    Electron pumps capable of delivering a current higher than 100pA with sufficient accuracy are likely to become the direct mise en pratique of the possible new quantum definition of the ampere. Furthermore, they are essential for closing the quantum metrological triangle experiment which tests for possible corrections to the quantum relations linking e and h, the electron charge and the Planck constant, to voltage, resistance and current. We present here single-island hybrid metal/semiconductor transistor pumps which combine the simplicity and efficiency of Coulomb blockade in metals with the unsurpassed performances of silicon switches. Robust and simple pumping at 650MHz and 0.5K is demonstrated. The pumped current obtained over a voltage bias range of 1.4mV corresponds to a relative deviation of 5e-4 from the calculated value, well within the 1.5e-3 uncertainty of the measurement setup. Multi-charge pumping can be performed. The simple design fully integrated in an industrial CMOS process makes it an ideal candidate for national measurement institutes to realize and share a future quantum ampere

    Time Delay Interferometry for LISA with one arm dysfunctional

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    In order to attain the requisite sensitivity for LISA - a joint space mission of the ESA and NASA- the laser frequency noise must be suppressed below the secondary noises such as the optical path noise, acceleration noise etc. By combining six appropriately time-delayed data streams containing fractional Doppler shifts - a technique called time delay interferometry (TDI) - the laser frequency noise may be adequately suppressed. We consider the general model of LISA where the armlengths vary with time, so that second generation TDI are relevant. However, we must envisage the possibility, that not all the optical links of LISA will be operating at all times, and therefore, we here consider the case of LISA operating with two arms only. As shown earlier in the literature, obtaining even approximate solutions of TDI to the general problem is very difficult. Since here only four optical links are relevant, the algebraic problem simplifies considerably. We are then able to exhibit a large number of solutions (from mathematical point of view an infinite number) and further present an algorithm to generate these solutions
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