We discuss the properties of an electromechanical oscillator whose operation is based upon the cyclic, quasiconservative conversion between gravitational potential, kinetic, and magnetic energies. The system consists of a strong-pinning type-II superconductor square loop subjected to a constant external force and to magnetic fields. The loop oscillates in the upright position at a frequency that can be tuned in the range 10-1000 Hz, and has induced in it a rectified electrical current. The emphasis of this paper is on the evaluation of the major remaining sources of losses in the oscillations. We argue that such losses should be associated with the viscous vibration of pinned flux lines in the superconductor Nb-Ti wire, provided the oscillator is kept under vacuum and the magnetic field is sufficiently uniform. Losses of similar or greater magnitude would be associated with dragging of the loop against the He atmosphere remaining in the evacuated cryostat. We discuss how other different sources of loss would become negligible for such operational conditions, so that a very high quality factor Q exceeding 10 10 might in principle be reached by the oscillator. The prospective utilization of such oscillator as a low-frequency high-Q clock is analyzed.

We have performed a magnetic study of a bulk metallic sample of Nb with critical temperature T c ϭ8.5 K. Magnetization versus temperature (M vs T) data obtained for fixed magnetic fields above 1 kOe show a superconducting transition which becomes broader as the field is increased. The data are interpreted in terms of the diamagnetic lowest Landau level ͑LLL͒ fluctuation theory. The scaling analysis gives values of the superconducting transition temperature T c (H) consistent with H c2 (T). We search for universal threedimensional LLL behavior by comparing scaling results for Nb and YBaCuO, but obtain no evidence for universality.

We discuss theoretically the properties of an electromechanical oscillating system whose operation is based upon the cyclic conservative conversion between gravitational potential, kinetic, and magnetic energies.The system consists of a superconducting coil subjected to a constant external force and to magnetic fields. The coil oscillates and has induced in it a rectified electrical current whose magnitude may reach hundreds of Ampere.The design differs from that of most conventional superconductor machines since the motion is linear (and practically unnoticeable depending on frequency) rather than rotatory, and it does not involve high speeds.Furthermore, there is no need for an external electrical power source for the system to start out. We also show that the losses for such a system can be made extremely small for certain operational conditions, so that by reaching and keeping resonance the system main application should be in the generation and storage of electromagnetic energy.

We have measured isofield magnetization curves as a function of temperature in two single crystal of deoxygenated YBaCuO with Tc = 52 and 41.5 K. Isofield magnetization curves were obtained for fields running from 0.05 to 4 kOe. The reversible region of the magnetization curves was analyzed in terms of a scaling proposed by Prange, but searching for the best exponent υ. The scaling analysis carried out for each data sample set with υ=0.669, which corresponds to the 3D-xy exponent, did not produced a collapsing of curves when applied to M vsT curves data obtained for the lowest fields. The resulting analysis for the Y123 crystal with Tc = 41.5 K, shows that lower field curves collapse over the entire reversible region following the Prange's scaling with υ=1, suggesting a two-dimensional behavior. It is shown that the same data obeying the Prange's scaling with υ=1 for crystal with Tc = 41.5 K, as well low field data for crystal with Tc = 52 K, obey the known two-dimensional scaling law obtained in the lowest-Landau-level approximation.

The present paper is based upon the fact that if an object is part of a highly stable oscillating system, it is possible to obtain an extremely precise measure for its mass in terms of the energy trapped in the system, rather than through a ratio between force and acceleration, provided such trapped energy can be properly measured. The subject is timely since there is great interest in Metrology on the establishment of a new electronic standard for the kilogram. Our contribution to such effort includes both the proposal of an alternative definition for mass, as well as the description of a realistic experimental system in which this new definition might actually be applied. The setup consists of an oscillating type-II superconducting loop subjected to the gravity and magnetic fields. The system is shown to be able to reach a dynamic equilibrium by trapping energy up to the point it levitates against the surrounding magnetic and gravitational fields, behaving as an extremely high-Q spring-load system. The proposed energy-mass equation applied to the electromechanical oscillating system eventually produces a new experimental relation between mass and the Planck constant.

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