34,613 research outputs found
Quantitative test of a quantum theory for the resistive transition in a superconducting single-walled carbon nanotube bundle
The phenomenon of superconductivity depends on the coherence of the phase of
the superconducting order parameter. The resistive transition in
quasi-one-dimensional (quasi-1D) superconductors is broad because of a large
phase fluctuation. We show that the resistive transition of a superconducting
single-walled carbon nanotube bundle is in quantitative agreement with the
Langer-Ambegaokar-McCumber-Halperin (LAMH) theory. We also demonstrate that the
resistive transition below T^*_c = 0.89T_c0 is simply proportional to exp
[-(3\beta T^*_c/T)(1-T/T^*_c)^3/2], where the barrier height has the same form
as that predicted by the LAMH theory and T_c0 is the mean field superconducting
transition temperature.Comment: 4 pages, 3 figure
Dark viscous fluid described by a unified equation of state in cosmology
We generalize the CDM model by introducing a unified EOS to describe
the Universe contents modeled as dark viscous fluid, motivated by the fact that
a single constant equation of state (EOS) () reproduces the
CDM model exactly. This EOS describes the perfect fluid term, the
dissipative effect, and the cosmological constant in a unique framework and the
Friedmann equations can be analytically solved. Especially, we find a relation
between the EOS parameter and the renormalizable condition of a scalar field.
We develop a completely numerical method to perform a minimization to
constrain the parameters in a cosmological model directly from the Friedmann
equations, and employ the SNe data with the parameter measured
from the SDSS data to constrain our model. The result indicates that the
dissipative effect is rather small in the late-time Universe.Comment: 4 pages, 2 figures. v2: new materials added. v3: matches the version
to appear in IJMP
An Efficient Method for GPS Multipath Mitigation Using the Teager-Kaiser-Operator-based MEDLL
An efficient method for GPS multipath mitigation is proposed. The motivation for this proposed method is to integrate the Teager-Kaiser Operator (TKO) with the Multipath Estimating Delay Lock Loop (MEDLL) module to mitigate the GPS multipath efficiently. The general implementation process of the proposed method is that we first utilize the TKO to operate on the received signal’s Auto-Correlation Function (ACF) to get an initial estimate of the multipaths. Then we transfer the initial estimated results to the MEDLL module for a further estimation. Finally, with a few iterations which are less than those of the original MEDLL algorithm, we can get a more accurate estimate of the Line-Of-Sight (LOS) signal, and thus the goal of the GPS multipath mitigation is achieved. The simulation results show that compared to the original MEDLL algorithm, the proposed method can reduce the computation load and the hardware and/or software consumption of the MEDLL module, meanwhile, without decreasing the algorithm accuracy
Low-lying states in Mg: a beyond relativistic mean-field investigation
The recently developed model of three-dimensional angular momentum projection
plus generator coordinate method on top of triaxial relativistic mean-field
states has been applied to study the low-lying states of Mg. The effects
of triaxiality on the low-energy spectra and E0 and E2 transitions are
examined.Comment: 6 pages, 3 figures, 1 table, talk presented at the 17th nuclear
physics conference "Marie and Pierre Curie" Kazimierz Dolny, 22-26th
September 2010, Polan
Massive Overlap Fermions on Anisotropic Lattices
We formulate the massive overlap fermions on anisotropic lattices.
We find that the dispersion relation for the overlap fermion resembles the
continuum form in the low-momentum region once the bare parameters are properly
tuned. The quark self-energy and the quark field renormalization constants are
calculated to one-loop in bare lattice perturbation theory.
We argue that massive domain wall quarks might be helpful in lattice QCD
studies on heavy-light hadron spectroscopy.Comment: 21 pages, 5 figures, one reference added compared with v.
Deflection and frequency monitoring of the Forth Road Bridge, Scotland, by GPS
Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees. Copyright © 2012 Thomas Telford Ltd.The use of carrier phase kinematic GPS (global positioning system) has evolved into a reliable technique to measure both the three-dimensional magnitudes and frequencies of movements of structures. Techniques have been developed that tackle errors caused by multipath, tropospheric delay and issues relating to satellite geometry. GPS-derived movements compare well with data from both design predictions and structural models. Results from field trials carried out on the Forth Road Bridge are presented. This paper brings together key results that outline the procedure as well as a series of new data that indicate other potential applications. GPS data were collected continuously over a period of 46 h at a minimum rate of 10 Hz. During the trials wind speed, wind direction, relative humidity and temperature were also recorded. Frequently there was very heavy traffic flow, and at one point a special load (a 100-t lorry) passed over simultaneously to the heavy daytime flow of traffic. Data from a planned load trial during a brief bridge closure are reported and compared with the limited results available from a finite element model. Measured vibration frequencies are also computed from GPS data and compared with those given in the literature. In addition, results indicating the change in structural characteristics are also presented – in particular changes of mass associated with changes in traffic loading are observed. The results show the performance of GPS as it has developed in recent years, and that it can now reliably be used as a significant part of structural health monitoring schemes, giving both the magnitude of quasi-static deflections in known time periods and hence the frequency of dynamic movements of structures.Forth Estuary Transport Authorit
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