2,521 research outputs found
Dynamic speckle - Interferometry of micro-displacements
The problem of the dynamics of speckles in the image plane of the object, caused by random movements of scattering centers is solved. We consider three cases: 1) during the observation the points move at random, but constant speeds, and 2) the relative displacement of any pair of points is a continuous random process, and 3) the motion of the centers is the sum of a deterministic movement and random displacement. For the cases 1) and 2) the characteristics of temporal and spectral autocorrelation function of the radiation intensity can be used for determining of individually and the average relative displacement of the centers, their dispersion and the relaxation time. For the case 3) is showed that under certain conditions, the optical signal contains a periodic component, the number of periods is proportional to the derivations of the deterministic displacements. The results of experiments conducted to test and application of theory are given. © 2012 American Institute of Physics
Baykonur
The 'Baykonur' cosmodrome, its functions, operations, and services are described in considerable detail. The launch complex, launching pads, launch structures, launchers with cable masts and propellant loading towers, are included. The sequence of all phases of rocket assembly and preparations for launch are depicted. Prelaunch procedures and the launch itself are described
GL_q(N)-covariant braided differential bialgebras
We study a possibility to define the (braided) comultiplication for the
GLq(N)-covariant differential complexes on some quantum spaces. We discover
such `differential bialgebras' (and Hopf algebras) on the bosonic and fermionic
quantum hyperplanes (with additive coproduct) and on the braided matrix algebra
BMq(N) with both multiplicative and additive coproducts. The latter case is
related (for N=2) to the q-Minkowski space and q-Poincare algebra.Comment: 7 page
A Method to Determine at the Weak Scale in Top Decays at the LHC
Until now, the Cabibbo Kobayashi Maskawa matrix element, , has
always been measured in decays, i.e.~at an energy scale , far below the weak scale. We consider here the possibility of
measuring it close to the weak scale, at , in top decays at the
Large Hadron Collider (LHC). Our proposed method would use data from the LHC
experiments in hadronic top decays , tagged by the semileptonic decay of the associated top. We estimate the
uncertainty of such a measurement, as a function of present and potential
future experimental jet flavour-tagging performances, and conclude that first
measurements using the data collected during 2016 - 2018 could yield a
fractional error on \Vcb\ of order 7\% per experiment. We also give projected
performances at higher luminosities, which could yield sensitivity to any
Standard Model running of \Vcb\ below the weak scale, if present.Comment: 15 pages, 1 figures. Changes for V3: removed earlier Fig. 1,
associated text and citations, added one new citatio
Nonlinear equations for p-adic open, closed, and open-closed strings
We investigate the structure of solutions of boundary value problems for a
one-dimensional nonlinear system of pseudodifferential equations describing the
dynamics (rolling) of p-adic open, closed, and open-closed strings for a scalar
tachyon field using the method of successive approximations. For an open-closed
string, we prove that the method converges for odd values of p of the form
p=4n+1 under the condition that the solution for the closed string is known.
For p=2, we discuss the questions of the existence and the nonexistence of
solutions of boundary value problems and indicate the possibility of
discontinuous solutions appearing.Comment: 16 pages, 3 figure
Efficient fe strategies for springback prediction – material modelling and computational aspects
Blanks of sheet metal are characterized by an intrinsic plastic anisotropic behaviour resulting from the plastic deformation during the rolling of sheets. Another type of anisotropy is elastic anisotropy which might be essential especially during elastic recovery processes during unloading after forming and springback. Thus, this paper focuses on the study of the sensitivity of the amount of springback in unconstrained bending with respect to elastic anisotropy. A finite strain constitutive model for evolving elastic and plastic anisotropy combining nonlinear isotropic and kinematic hardening is discussed. The evolution of elastic anisotropy is described by representing the Helmholtz free energy as a function of a family of evolving structure tensors. In addition, plastic anisotropy is modelled via the dependence of the yield surface on the same family of structure tensors. The constitutive equations of the model are implemented as a user material subroutine UMAT in the commercial solver ABAQUS/Standard, which is then applied to the simulation of springback in unconstrained bending
First Evaluation of the CPU, GPGPU and MIC Architectures for Real Time Particle Tracking based on Hough Transform at the LHC
Recent innovations focused around {\em parallel} processing, either through
systems containing multiple processors or processors containing multiple cores,
hold great promise for enhancing the performance of the trigger at the LHC and
extending its physics program. The flexibility of the CMS/ATLAS trigger system
allows for easy integration of computational accelerators, such as NVIDIA's
Tesla Graphics Processing Unit (GPU) or Intel's \xphi, in the High Level
Trigger. These accelerators have the potential to provide faster or more energy
efficient event selection, thus opening up possibilities for new complex
triggers that were not previously feasible. At the same time, it is crucial to
explore the performance limits achievable on the latest generation multicore
CPUs with the use of the best software optimization methods. In this article, a
new tracking algorithm based on the Hough transform will be evaluated for the
first time on a multi-core Intel Xeon E5-2697v2 CPU, an NVIDIA Tesla K20c GPU,
and an Intel \xphi\ 7120 coprocessor. Preliminary time performance will be
presented.Comment: 13 pages, 4 figures, Accepted to JINS
- …