10,601 research outputs found

    The applicability of MFD thrusters to satellite power systems

    Get PDF
    The high power self field MPD thruster uses electromagnetic forces rather than electrostatic to accelerate a neutral plasma. The most attractive application of MPD thrusters to satellite power systems is in the area of electric propulsion for a cargo orbit transfer vehicle (COTV). Calculations were performed in order to compare the performance of a COTV using an ion or MPD propulsion system. Results show that the MPD propulsion system gives a shorter trip time with the same power and payload when compared to the ion thruster propulsion system at either value of specific impulse. More important than the trip time benefit may be the advantage a MPD propulsion system provides in system simplicity. Another interesting COTV concept using MPD thrusters is the use of a remote power supply located on the Earth, at GEO, or somewhere in between to transmit power to the COTV in a microwave transmission. The specific impulse at thrust levels of tens of newtons makes a MPD propulsion system a candidate for stationkeeping and attitude control of large space structures such as a SPS

    The Limits of Judicial Review in Constitutional Adjudication

    Get PDF
    Constitutional adjudication presently requires that in order for a party to challenge a governmental act he must claim that the act has violated his constitutional rights. The purpose of this article is to show that such a requirement undermines constitutional limits on governmental actions and is inconsistent with a proper interpretation of the Constitution. I. Introduction II. The Police Power III. The Government Operations Power IV. The Law Declaration Power V. Conclusio

    Plume Characterization of a One-Millipound Solid Teflon Pulsed Plasma Thruster, Phase 2

    Get PDF
    Measurements of the pulsed plasma thruster (PPT) plume upstream mass flux were made in the Molecular Sink (MOLSINK) vacuum facility in order to minimize the plume-tank wall reflected mass flux. Using specially designed collimators on 4 rows of Quartz Crystal Microbalanced (QCMs) mounted on a support extending radially away from the plume axis, measurements were made of the mass flux originating in a thin slice of the PPT primary plume at an arbitrary dip angle with respect to the thruster axis. The measured and analytically corrected mass flux from particles reflected from the MOLSINK walls was substracted from the collimated QCM measurements to improve their accuracy. These data were then analytically summed over dip angle to estimate the total plume backflow upstream of the thruster nozzle. The results indicate that the PPT backflow is of order 10 to the minus 10th power g/square cm/pulse in the region from 38 to 86 cm from the PPT axis in the nozzle exit plane. This flux drops with the square of the radial distance from the PPT axis and is comparable to the backflow of an 8 cm ion thruster, which has performance characteristics similar to those of the PPT

    Experimental Quantum Process Discrimination

    Full text link
    Discrimination between unknown processes chosen from a finite set is experimentally shown to be possible even in the case of non-orthogonal processes. We demonstrate unambiguous deterministic quantum process discrimination (QPD) of non-orthogonal processes using properties of entanglement, additional known unitaries, or higher dimensional systems. Single qubit measurement and unitary processes and multipartite unitaries (where the unitary acts non-separably across two distant locations) acting on photons are discriminated with a confidence of 97\geq97% in all cases.Comment: 4 pages, 3 figures, comments welcome. Revised version includes multi-partite QP

    (2+1) resonant enhanced multiphoton ionization of H_2 via the E, F^(1)Σ^+_g state

    Get PDF
    In this paper, we report the results of ab initio calculations of photoelectron angular distributions and vibrational branching ratios for the (2+1) REMPI of H_2 via the E, F^(1)Σ^+_g state, and compare these with the experimental data of Anderson et al. [Chem. Phys. Lett. 105, 22 (1984)]. These results show that the observed non‐Franck–Condon behavior is predominantly due to the R dependence of the transition matrix elements, and to a lesser degree to the energy dependence. This work presents the first molecular REMPI study employing a correlated wave function to describe the Rydberg–valence mixing in the resonant intermediate state

    A simple encoding of a quantum circuit amplitude as a matrix permanent

    Full text link
    A simple construction is presented which allows computing the transition amplitude of a quantum circuit to be encoded as computing the permanent of a matrix which is of size proportional to the number of quantum gates in the circuit. This opens up some interesting classical monte-carlo algorithms for approximating quantum circuits.Comment: 6 figure

    Investigations into the triggered lightning response of the F106B thunderstorm research aircraft

    Get PDF
    An investigation has been conducted into the lightning characteristics of the NASA F106B thunderstorm research aircraft. The investigation includes analysis of measured data from the aircraft in the time and frequency domains. Linear and nonlinear computer modelling has also been performed. In addition, new computer tools have been developed, including a new enhanced nonlinear air breakdown model, and a subgrid model useful for analyzing fine details of the aircraft's geometry. Comparison of measured and calculated electromagnetic responses of the aircraft to a triggered lightning environment are presented

    Gauge Orbit Types for Theories with Classical Compact Gauge Group

    Full text link
    We determine the orbit types of the action of the group of local gauge transformations on the space of connections in a principal bundle with structure group O(n), SO(n) or Sp(n)Sp(n) over a closed, simply connected manifold of dimension 4. Complemented with earlier results on U(n) and SU(n) this completes the classification of the orbit types for all classical compact gauge groups over such space-time manifolds. On the way we derive the classification of principal bundles with structure group SO(n) over these manifolds and the Howe subgroups of SO(n).Comment: 57 page

    Further results on the cross norm criterion for separability

    Full text link
    In the present paper the cross norm criterion for separability of density matrices is studied. In the first part of the paper we determine the value of the greatest cross norm for Werner states, for isotropic states and for Bell diagonal states. In the second part we show that the greatest cross norm criterion induces a novel computable separability criterion for bipartite systems. This new criterion is a necessary but in general not a sufficient criterion for separability. It is shown, however, that for all pure states, for Bell diagonal states, for Werner states in dimension d=2 and for isotropic states in arbitrary dimensions the new criterion is necessary and sufficient. Moreover, it is shown that for Werner states in higher dimensions (d greater than 2), the new criterion is only necessary.Comment: REVTeX, 19 page

    Particle alignments and shape change in 66^{66}Ge and 68^{68}Ge

    Full text link
    The structure of the NZN \approx Z nuclei 66^{66}Ge and 68^{68}Ge is studied by the shell model on a spherical basis. The calculations with an extended P+QQP+QQ Hamiltonian in the configuration space (2p3/22p_{3/2}, 1f5/21f_{5/2}, 2p1/22p_{1/2}, 1g9/21g_{9/2}) succeed in reproducing experimental energy levels, moments of inertia and QQ moments in Ge isotopes. Using the reliable wave functions, this paper investigates particle alignments and nuclear shapes in 66^{66}Ge and 68^{68}Ge. It is shown that structural changes in the four sequences of the positive- and negative-parity yrast states with even JJ and odd JJ are caused by various types of particle alignments in the g9/2g_{9/2} orbit. The nuclear shape is investigated by calculating spectroscopic QQ moments of the first and second 2+2^+ states, and moreover the triaxiality is examined by the constrained Hatree-Fock method. The changes of the first band crossing and the nuclear deformation depending on the neutron number are discussed.Comment: 18 pages, 21 figures; submitted to Phys. Rev.
    corecore