3,896 research outputs found
Parton Energy Loss and the Generalized Jet Transport Coefficient
We revisit radiative parton energy loss in deeply inelastic scattering (DIS)
off a large nucleus within the perturbative QCD approach. We calculate the
gluon radiation spectra induced by double parton scattering in DIS without
collinear expansion in the transverse momentum of initial gluons as in the
original high-twist approach. The final radiative gluon spectrum can be
expressed in terms of the convolution of hard partonic parts and unintegrated
or transverse momentum dependent (TMD) quark-gluon correlations. The TMD
quark-gluon correlation can be factorized approximately as a product of initial
quark distribution and TMD gluon distribution which can be used to define the
generalized or TMD jet transport coefficient. Under the static scattering
center and soft radiative gluon approximation, we recover the result by
Gylassy-Levai-Vitev (GLV) in the first order of the opacity expansion. The
difference as a result of the soft radiative gluon approximation is
investigated numerically under the static scattering center approximation.Comment: 33 pages in RevTeX with 30 figures, final version appeared in PRD
with additional typos correcte
Service life design for infrastructure
In the past few years more and more attention has been devoted to the safety and serviceability as well as durability and sustainability of structures. Meanwhile there are intensive research and development activities going on, e.g. on materials properties, deterioration mechanisms, geometric- and structural design, execution aspect and maintenance. Furthermore, codes and standards on service life design are being discussed and partially established world wide. It is now time to present a focused picture of the current status and future trends in this field, including theory, practice and education. The aim of the symposium is to provide a forum to researchers and practitioners for presenting the newest findings and to discuss new ideas on service life design and serviceability of infrastructural Works, effectiveness of service life design methods and experiences from the practice
Controllability Analysis and Degraded Control for a Class of Hexacopters Subject to Rotor Failures
This paper considers the controllability analysis and fault tolerant control
problem for a class of hexacopters. It is shown that the considered hexacopter
is uncontrollable when one rotor fails, even though the hexacopter is
over-actuated and its controllability matrix is row full rank. According to
this, a fault tolerant control strategy is proposed to control a degraded
system, where the yaw states of the considered hexacopter are ignored.
Theoretical analysis indicates that the degraded system is controllable if and
only if the maximum lift of each rotor is greater than a certain value. The
simulation and experiment results on a prototype hexacopter show the
feasibility of our controllability analysis and degraded control strategy.Comment: 21 pages, 7 figures, submitted to Journal of Intelligent & Robotic
System
Twist-3 contribution to the pion electromagnetic form factor
Non-leading contribution to the pion electromagnetic form factor which comes
from the pion twist-3 wave function is analyzed in the modified hard scattering
approach (MHSA) proposed by Li and Sterman. This contribution is enhanced
significantly due to bound state effect (the twist-3 wave function is
independent of the fractional momentum carried by the parton and has a large
factor with being the pion meson mass and
being the mean u- and d-quark masses). Consequently, although it is suppressed
by the factor , the twist-3 contribution is comparable with and even
larger than the leading twist (twist-2) contribution at intermediate energy
region of being .Comment: 10 pages, 2 fgures, latex. More discussions on the Sudakov effect
added, references added. To appear in European Physical Journal C
(Zeitschrift fur Physik C
The Affection of Independent Innovation on Employment
The paper reviews the theories on the relationship between innovation and employment, and finds that innovation can provide more employment opportunities in the long run and promote the upgrade of employment structure. Then considering the particular situation of China and its present strategic target, we analyze the features of independent innovation, a kind of innovation, and its affection on China’s employment. On this basis, we give some suggestions for government to reduce the impact of independent innovation on employment. Key words: Independent innovation; Employmen
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