427 research outputs found
Asymmetry Parameter of the by Analyzing the Transition Form Factors within QCD
Separating the mixture of the and states, the
transition form factors are calculated in
the three-point QCD sum rules approach. The longitudinal, transverse and total
decay widths as well as the asymmetry parameter, characterizing the
polarization of the axial and the branching ratio for these
decays are evaluated.Comment: 25 pages, 3 figures, 3 table
A demand-driven approach for a multi-agent system in Supply Chain Management
This paper presents the architecture of a multi-agent decision support system for Supply Chain Management (SCM) which has been designed to compete in the TAC SCM game. The behaviour of the system is demand-driven and the agents plan, predict, and react dynamically to changes in the market. The main strength of the system lies in the ability of the Demand agent to predict customer winning bid prices - the highest prices the agent can offer customers and still obtain their orders. This paper investigates the effect of the ability to predict customer order prices on the overall performance of the system. Four strategies are proposed and compared for predicting such prices. The experimental results reveal which strategies are better and show that there is a correlation between the accuracy of the models' predictions and the overall system performance: the more accurate the prediction of customer order prices, the higher the profit. © 2010 Springer-Verlag Berlin Heidelberg
Grey-box model identification via evolutionary computing
This paper presents an evolutionary grey-box model identification methodology that makes the best use of a priori knowledge on
a clear-box model with a global structural representation of the physical system under study, whilst incorporating accurate blackbox
models for immeasurable and local nonlinearities of a practical system. The evolutionary technique is applied to building
dominant structural identification with local parametric tuning without the need of a differentiable performance index in the
presence of noisy data. It is shown that the evolutionary technique provides an excellent fitting performance and is capable of
accommodating multiple objectives such as to examine the relationships between model complexity and fitting accuracy during the
model building process. Validation results show that the proposed method offers robust, uncluttered and accurate models for two
practical systems. It is expected that this type of grey-box models will accommodate many practical engineering systems for a better
modelling accuracy
Dynamical electron transport through a nanoelectromechanical wire in a magnetic field
We investigate dynamical transport properties of interacting electrons moving
in a vibrating nanoelectromechanical wire in a magnetic field. We have built an
exactly solvable model in which electric current and mechanical oscillation are
treated fully quantum mechanically on an equal footing. Quantum mechanically
fluctuating Aharonov-Bohm phases obtained by the electrons cause nontrivial
contribution to mechanical vibration and electrical conduction of the wire. We
demonstrate our theory by calculating the admittance of the wire which are
influenced by the multiple interplay between the mechanical and the electrical
energy scales, magnetic field strength, and the electron-electron interaction
Decreased Fibroblast and Increased Osteoblast Functions on Ionic Plasma Deposited Nanostructured Ti Coatings
Bioactive coatings are in high demand to control cellular functions for numerous medical devices. The objective of this in vitro study was to characterize for the first time fibroblast (fibrous scar tissue forming cells) adhesion and proliferation on an important polymeric biomaterial (silicone) coated with titanium using a novel ionic plasma deposition (IPD) process. Fibroblasts are one of the first anchorage-dependent cells to arrive at an implant surface during the wound healing process. Persistent excessive functions of fibroblasts have been linked to detrimental fibrous tissue formation which may cause implant failure. The IPD process creates a surface-engineered nanostructure (with features usually below 100 nm) by first using a vacuum to remove all contaminants, then guiding charged metallic ions or plasma to the surface of a medical device at ambient temperature. Results demonstrated that compared to currently used titanium and uncoated silicone, silicone coated with titanium using IPD significantly decreased fibroblast adhesion and proliferation. Results also showed competitively increased osteoblast (bone-forming cells) over fibroblast adhesion on silicone coated with titanium; in contrast, osteoblast adhesion was not competitively increased over fibroblast adhesion on uncoated silicone or titanium controls. In this manner, this study strongly suggests that IPD should be further studied for biomaterial applications in which fibrous tissue encapsulation is undesirable (such as for orthopedic implants, cardiovascular components, etc.)
QCD sum rules analysis of the rare B_c \rar X\nu\bar{\nu} decays
Taking into account the gluon correction contributions to the correlation
function, the form factors relevant to the rare B_c \rar X \nu\bar{\nu}
decays are calculated in the framework of the three point QCD sum rules, where
stands for axial vector particle, , and vector particles,
. The total decay width as well as the branching ratio of these
decays are evaluated using the dependent expressions of the form factors.
A comparison of our results with the predictions of the relativistic
constituent quark model is presented.Comment: 21 Pages, 2 Figures and 5 Table
The transition form factors for semi-leptonic weak decays of in QCD sum rules
Within the Standard Model, we investigate the semi-leptonic weak decays of
. The various form factors of transiting to a single charmed
meson () are studied in the framework of the QCD sum rules.
These form factors fully determine the rates of the weak semi-leptonic decays
of and provide valuable information about the non-perturbative QCD
effects. Our results indicate that the decay rate of the semi-leptonic weak
decay mode is at order of .Comment: 28 pages, 6 figures, revised version to be published in Eur.Phys.J.
Measurement of the Atmospheric Muon Spectrum from 20 to 3000 GeV
The absolute muon flux between 20 GeV and 3000 GeV is measured with the L3
magnetic muon spectrometer for zenith angles ranging from 0 degree to 58
degree. Due to the large exposure of about 150 m2 sr d, and the excellent
momentum resolution of the L3 muon chambers, a precision of 2.3 % at 150 GeV in
the vertical direction is achieved.
The ratio of positive to negative muons is studied between 20 GeV and 500
GeV, and the average vertical muon charge ratio is found to be 1.285 +- 0.003
(stat.) +- 0.019 (syst.).Comment: Total 32 pages, 9Figure
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
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