465 research outputs found
Differentially Coherent Code Acquisition in the MIMO-Aided Multi-Carrier DS-CDMA Downlink
Both differentially coherent and non-coherent code acquisition schemes designed for the multiple-input multiple-output (MIMO)-aided multi-carrier (MC)-DS-CDMA downlink are analysed, when communicating over uncorrelated Rayleigh channels. The attainable mean acquisition time (MAT) performance is studied as a function of both the number of multiple transmit/multiple receive antennas and that of the number of subcarriers. It is demonstrated that in contrast to the expectations, when the number of multiple transmit antennas and/or that of the subcarriers is increased in both the differentially coherent and the non-coherent code acquisition scenarios, the achievable MAT deteriorates over the entire signal-to-interference plus noise ratio (SINR) per chip (Ec/Io) range considered, except for the scenario of single-carrier (SC)-DS-CDMA using P Œ 2 transmit antennas and R Œ 1 receive antenna. As expected, the degree of performance degradation depends upon the specific scheme and the Ec/Io ratio considered, although paradoxically, the correctly synchronised MIMO-aided system is capable of attaining its target bit error ratio performance at reduced SINR values
Iterative Code Acquisition for DS-UWB Downlink using Multiple-Component Decoders
Iterative code acquisition schemes employing beneficially chosen higher-order generator polynomials and multiple-component decoders are analysed in terms of the correct detection probability of the direct sequence-ultra-wideband (DS-UWB) downlink. The proposed technique can maintain high acquisition performance, while reducing associated complexity by up to 30%
Fire resistance performance of submerged floating tunnel under various fire conditions
Submerged Floating Tunnels (SFT) were researched by countries had many island as Norway, Italy,\ud
China, and Japan. Several sites were examined in China and Norway. Most of them investigated about seismic, dynamic,\ud
and collision performance. However, present researches lack to apply the construction fields, therefore, additional\ud
researches need. Fire resistance performance of the SFT is important one of the various researches. If fire break out in\ud
SFT, it is damaged by thermal loads. The damage of the SFT varies by type of fire. Structure of the SFT is able to\ud
collapse partially by fire scale and fire exposure time. For this reason, fire resistance design of the SFT must be\ud
suggested. Fire resistance performance of SFT could be investigating for fire resistance design of SFT. Fire condition\ud
could be expressed fire curves which are suggested by fire scale and fire exposure time. In this paper, temperature\ud
distributions of the SFT were investigated through FE analysis under various fire conditions. Heat transfer analysis was\ud
applied to investigate conduction of heat by fire. And there was to draw the biggest influence fire condition to the SFT\ud
from FE analysis results. Also, preliminary study was performed for fire resistance design
Evolving Networks with Multi-species Nodes and Spread in the Number of Initial Links
We consider models for growing networks incorporating two effects not
previously considered: (i) different species of nodes, with each species having
different properties (such as different attachment probabilities to other node
species); and (ii) when a new node is born, its number of links to old nodes is
random with a given probability distribution. Our numerical simulations show
good agreement with analytic solutions. As an application of our model, we
investigate the movie-actor network with movies considered as nodes and actors
as links.Comment: 5 pages, 5 figures, submitted to PR
Bending strength analysis of steel-composite submerged floating tunnels
A submerged floating tunnel (SFT) must have enough strength to resist to various external loadings such\ud
as bending, torsion, tension, and compression. The expected main deformation of SFT is caused by bending moment.\ud
And this bending moment makes tensile stress and compression stress on the wall of SFT. Thus, bending moment is a\ud
main affecting factor on the safety of SFT. Until now, a reinforced concrete tunnel was suggested for SFT by other\ud
researchers. In this study, an internally confined hollow reinforced concrete tunnel and a double skinned composite\ud
tubular tunnel were proposed. And their bending strengths were studied and compared with that of a reinforced concrete\ud
tunnel. The analysis results showed the proposed SFT structures had enough strength to guarantee safety
Zeeman effects on the impurity-induced resonances in d-wave superconductors
It is shown how the resonant states induced by a single spinless impurity in
a d-wave superconductor evolve under the effect of an applied Zeeman magnetic
field. Moreover, it is demonstrated that the spin-orbit coupling to the
impurity potential can have important and characteristic effects on the
resonant states and their response to the Zeeman field, especially when the
impurity is close to the unitary limit. For zero or very small spin-orbit
interaction, the resonant states becomes Zeeman splitted by the magnetic field
while when the spin-orbit coupling is important, new low-lying resonances arise
which do not show any Zeeman splitting.Comment: 5 pages with 5 eps figures embedded. To appear on Phys. Rev.
Neutron beam test of CsI crystal for dark matter search
We have studied the response of Tl-doped and Na-doped CsI crystals to nuclear
recoils and 's below 10 keV. The response of CsI crystals to nuclear
recoil was studied with mono-energetic neutrons produced by the
H(p,n)He reaction. This was compared to the response to Compton
electrons scattered by 662 keV -ray. Pulse shape discrimination between
the response to these 's and nuclear recoils was studied, and quality
factors were estimated. The quenching factors for nuclear recoils were derived
for both CsI(Na) and CsI(Tl) crystals.Comment: 21pages, 14figures, submitted to NIM
A Theory for High- Superconductors Considering Inhomogeneous Charge Distribution
We propose a general theory for the critical and pseudogap
temperature dependence on the doping concentration for high- oxides,
taking into account the charge inhomogeneities in the planes. The well
measured experimental inhomogeneous charge density in a given compound is
assumed to produce a spatial distribution of local . These differences
in the local charge concentration is assumed to yield insulator and metallic
regions, possibly in a stripe morphology. In the metallic region, the
inhomogeneous charge density yields also spatial distributions of
superconducting critical temperatures and zero temperature gap
. For a given sample, the measured onset of vanishing gap
temperature is identified as the pseudogap temperature, that is, , which
is the maximum of all . Below , due to the distribution of
's, there are some superconducting regions surrounded by insulator or
metallic medium. The transition to a superconducting state corresponds to the
percolation threshold among the superconducting regions with different
's. To model the charge inhomogeneities we use a double branched
Poisson-Gaussian distribution. To make definite calculations and compare with
the experimental results, we derive phase diagrams for the BSCO, LSCO and YBCO
families, with a mean field theory for superconductivity using an extended
Hubbard Hamiltonian. We show also that this novel approach provides new
insights on several experimental features of high- oxides.Comment: 7 pages, 5 eps figures, corrected typo
Measurement of the Branching Fraction for B->eta' K and Search for B->eta'pi+
We report measurements for two-body charmless B decays with an eta' meson in
the final state. Using 11.1X10^6 BBbar pairs collected with the Belle detector,
we find BF(B^+ ->eta'K^+)=(79^+12_-11 +-9)x10^-6 and BF(B^0 ->
eta'K^0)=(55^+19_-16 +-8)x10^-6, where the first and second errors are
statistical and systematic, respectively. No signal is observed in the mode B^+
-> eta' pi^+, and we set a 90% confidence level upper limit of BF(B^+->
eta'pi^+) eta'K^+- decays is
investigated and a limit at 90% confidence level of -0.20<Acp<0.32 is obtained.Comment: Submitted to Physics Letters
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