44,138 research outputs found
Cross-Correlation-Function-Based Multipath Mitigation Method for Sine-BOC Signals
Global Navigation Satellite Systems (GNSS) positioning accuracy indoor and urban canyons environments are greatly affected by multipath due to distortions in its autocorrelation function. In this paper, a cross-correlation function between the received sine phased Binary Offset Carrier (sine-BOC) modulation signal and the local signal is studied firstly, and a new multipath mitigation method based on cross-correlation function for sine-BOC signal is proposed. This method is implemented to create a cross-correlation function by designing the modulated symbols of the local signal. The theoretical analysis and simulation results indicate that the proposed method exhibits better multipath mitigation performance compared with the traditional Double Delta Correlator (DDC) techniques, especially the medium/long delay multipath signals, and it is also convenient and flexible to implement by using only one correlator, which is the case of low-cost mass-market receivers
Etching-dependent reproducible memory switching in vertical SiO2 structures
Vertical structures of SiO sandwiched between a top tungsten electrode
and conducting non-metal substrate were fabricated by dry and wet etching
methods. Both structures exhibit similar voltage-controlled memory behaviors,
in which short voltage pulses (1 s) can switch the devices between high-
and low-impedance states. Through the comparison of current-voltage
characteristics in structures made by different methods, filamentary conduction
at the etched oxide edges is most consistent with the results, providing
insights into similar behaviors in metal/SiO/metal systems. High ON/OFF ratios
of over 10 were demonstrated.Comment: 6 pages, 3 figures + 2 suppl. figure
Relativistic description of nuclear matrix elements in neutrinoless double- decay
Neutrinoless double- () decay is related to many
fundamental concepts in nuclear and particle physics beyond the standard model.
Currently there are many experiments searching for this weak process. An
accurate knowledge of the nuclear matrix element for the decay
is essential for determining the effective neutrino mass once this process is
eventually measured. We report the first full relativistic description of the
decay matrix element based on a state-of-the-art nuclear
structure model. We adopt the full relativistic transition operators which are
derived with the charge-changing nucleonic currents composed of the vector
coupling, axial-vector coupling, pseudoscalar coupling, and weak-magnetism
coupling terms. The wave functions for the initial and final nuclei are
determined by the multireference covariant density functional theory (MR-CDFT)
based on the point-coupling functional PC-PK1. The low-energy spectra and
electric quadrupole transitions in Nd and its daughter nucleus
Sm are well reproduced by the MR-CDFT calculations. The
decay matrix elements for both the
and decays of Nd are evaluated. The effects
of particle number projection, static and dynamic deformations, and the full
relativistic structure of the transition operators on the matrix elements are
studied in detail. The resulting decay matrix element for the
transition is , which gives the most optimistic
prediction for the next generation of experiments searching for the
decay in Nd.Comment: 17 pages, 9 figures; table adde
SPSA-Based Tracking Method for Single-Channel-Receiver Array
A novel tracking method in the phased antenna array with a single-channel receiver for the moving signal source is presented in this paper. And the problems of the direction-of-arrival track and beamforming in the array system are converted to the power maximization of received signal in the free-interference conditions, which is different from the existing algorithms that maximize the signal to interference and noise ratio. The proposed tracking method reaches the global optimum rather than local by injecting the extra noise terms into the gradient estimation. The antenna beam can be steered to coincide with the direction of the moving source fast and accurately by perturbing the output of the phase shifters during motion, due to the high efficiency and easy implementation of the proposed beamforming algorithm based on the simultaneous perturbation stochastic approximation (SPSA). Computer simulations verify that the proposed tracking scheme is robust and effective
Rise of Kp Total Cross Section and Universality
The increase of the measured hadronic total cross sections at the highest
energies is empirically described by squared log of center-of-mass energy sqrt
s as sigma(tot)= B (log s)2, consistent with the energy dependence of the
Froissart unitarity bound. The coefficient B is argued to have a universal
value, but this is not proved directly from QCD. In the previous tests of this
universality, the p(pbar)p, pi p, and K p forward scatterings were analyzed
independently and found to be consistent with B(pp) = B(pip) = B(Kp), although
the determined value of B(Kp) had large uncertainty. In the present work, we
have further analyzed forward Kp scattering to obtain a more exact value of
B(Kp). Making use of continuous moment sum rules(CMSR) we have fully exploited
the information of low-energy scattering data to predict the high-energy
behavior of the amplitude hrough duality. The estimation of B(Kp) is improved
remarkably, and our result strongly supports the universality of B.Comment: 12 pages, 3 figure
Tensor coupling effects on spin symmetry in anti-Lambda spectrum of hypernuclei
The effects of -tensor coupling on the spin
symmetry of spectra in -nucleus systems have
been studied with the relativistic mean-field theory. Taking
C+ as an example, it is found that the tensor coupling
enlarges the spin-orbit splittings of by an order of magnitude
although its effects on the wave functions of are negligible.
Similar conclusions has been observed in -nucleus of different
mass regions, including O+, Ca+ and
Pb+. It indicates that the spin symmetry in
anti-lambda-nucleus systems is still good irrespective of the tensor coupling.Comment: 12 pages, 3 figures
Robust Quantum State Transfer in Random Unpolarized Spin Chains
We propose and analyze a new approach for quantum state transfer between
remote spin qubits. Specifically, we demonstrate that coherent quantum coupling
between remote qubits can be achieved via certain classes of random,
unpolarized (infinite temperature) spin chains. Our method is robust to
coupling strength disorder and does not require manipulation or control over
individual spins. In principle, it can be used to attain perfect state transfer
over arbitrarily long range via purely Hamiltonian evolution and may be
particularly applicable in a solid-state quantum information processor. As an
example, we demonstrate that it can be used to attain strong coherent coupling
between Nitrogen-Vacancy centers separated by micrometer distances at room
temperature. Realistic imperfections and decoherence effects are analyzed.Comment: 4 pages, 2 figures. V2: Modified discussion of disorder, added
references - final version as published in Phys. Rev. Let
- …