1,800 research outputs found
Dynamics towards the Feigenbaum attractor
We expose at a previously unknown level of detail the features of the
dynamics of trajectories that either evolve towards the Feigenbaum attractor or
are captured by its matching repellor. Amongst these features are the
following: i) The set of preimages of the attractor and of the repellor are
embedded (dense) into each other. ii) The preimage layout is obtained as the
limiting form of the rank structure of the fractal boundaries between attractor
and repellor positions for the family of supercycle attractors. iii) The joint
set of preimages for each case form an infinite number of families of
well-defined phase-space gaps in the attractor or in the repellor. iv) The gaps
in each of these families can be ordered with decreasing width in accord to
power laws and are seen to appear sequentially in the dynamics generated by
uniform distributions of initial conditions. v) The power law with log-periodic
modulation associated to the rate of approach of trajectories towards the
attractor (and to the repellor) is explained in terms of the progression of gap
formation. vi) The relationship between the law of rate of convergence to the
attractor and the inexhaustible hierarchy feature of the preimage structure is
elucidated.Comment: 8 pages, 12 figure
Tsallis' q index and Mori's q phase transitions at edge of chaos
We uncover the basis for the validity of the Tsallis statistics at the onset
of chaos in logistic maps. The dynamics within the critical attractor is found
to consist of an infinite family of Mori's -phase transitions of rapidly
decreasing strength, each associated to a discontinuity in Feigenbaum's
trajectory scaling function . The value of at each transition
corresponds to the same special value for the entropic index , such that the
resultant sets of -Lyapunov coefficients are equal to the Tsallis rates of
entropy evolution.Comment: Significantly enlarged version, additional figures and references. To
be published in Physical Review
Numeric and symbolic evaluation of the pfaffian of general skew-symmetric matrices
Evaluation of pfaffians arises in a number of physics applications, and for
some of them a direct method is preferable to using the determinantal formula.
We discuss two methods for the numerical evaluation of pfaffians. The first is
tridiagonalization based on Householder transformations. The main advantage of
this method is its numerical stability that makes unnecessary the
implementation of a pivoting strategy. The second method considered is based on
Aitken's block diagonalization formula. It yields to a kind of LU (similar to
Cholesky's factorization) decomposition (under congruence) of arbitrary
skew-symmetric matrices that is well suited both for the numeric and symbolic
evaluations of the pfaffian. Fortran subroutines (FORTRAN 77 and 90)
implementing both methods are given. We also provide simple implementations in
Python and Mathematica for purpose of testing, or for exploratory studies of
methods that make use of pfaffians.Comment: 13 pages, Download links:
http://gamma.ft.uam.es/robledo/Downloads.html and
http://www.phys.washington.edu/users/bertsch/computer.htm
Intermittency at critical transitions and aging dynamics at edge of chaos
We recall that, at both the intermittency transitions and at the Feigenbaum
attractor in unimodal maps of non-linearity of order , the dynamics
rigorously obeys the Tsallis statistics. We account for the -indices and the
generalized Lyapunov coefficients that characterize the
universality classes of the pitchfork and tangent bifurcations. We identify the
Mori singularities in the Lyapunov spectrum at the edge of chaos with the
appearance of a special value for the entropic index . The physical area of
the Tsallis statistics is further probed by considering the dynamics near
criticality and glass formation in thermal systems. In both cases a close
connection is made with states in unimodal maps with vanishing Lyapunov
coefficients.Comment: Proceedings of: STATPHYS 2004 - 22nd IUPAP International Conference
on Statistical Physics, National Science Seminar Complex, Indian Institute of
Science, Bangalore, 4-9 July 2004. Pramana, in pres
La RSE est - elle applicable dans les établissements publics comme dans n'importe quelle autre organisation ? Un exemple : les Universités
De responsabilité sociétale des entreprises à responsabilité sociétale des organisations, une évolution mais pour quelle mise en application ? Le service public peut-il s\u27adapter ? Pourquoi ? Avec qui ? A quelles conditions ? Dispose-t-il des outils nécessaires ? Réflexions sur ce thème
Sensitivity to initial conditions at bifurcations in one-dimensional nonlinear maps: rigorous nonextensive solutions
Using the Feigenbaum renormalization group (RG) transformation we work out
exactly the dynamics and the sensitivity to initial conditions for unimodal
maps of nonlinearity at both their pitchfork and tangent
bifurcations. These functions have the form of -exponentials as proposed in
Tsallis' generalization of statistical mechanics. We determine the -indices
that characterize these universality classes and perform for the first time the
calculation of the -generalized Lyapunov coefficient . The
pitchfork and the left-hand side of the tangent bifurcations display weak
insensitivity to initial conditions, while the right-hand side of the tangent
bifurcations presents a `super-strong' (faster than exponential) sensitivity to
initial conditions. We corroborate our analytical results with {\em a priori}
numerical calculations.Comment: latex, 4 figures. Updated references and some general presentation
improvements. To appear published in Europhysics Letter
The Key Success Factors for Lean Manufacturing versus Six Sigma
The aim of this study is to investigate and identify the key success factors of implementing lean manufacturing and six sigma in separate ways. The study applies a quantitative approach and statistical analysis to determine the results collected from the French industry. Findings revealed that there exist statistically significant differences in the level of importance between the implementation of lean manufacturing and six sigma across the common success factors such as culture change, communication and involvement of employees, among others. On the other hand, there were similarities in the degrees of importance regarding the common success including top management commitment, skill and expertise and linking method to supplier, etc. The findings can assist an organization to be more careful with the success factors of each method, in addition to helping them in determining the appropriate method that enables exploration between lean manufacturing and six sigma based on the capacity of an organization to apply the success factors. Literature reviews regarding comparison of key success factors of lean manufacturing and six sigma had not been tested earlier, which have been considered in this study.
Impacts of Lean Manufacturing and Six sigma
International audienceThe purpose of this article is to determine the companies performance for industries applied lean manufacturing and six sigma. Study results indicate that companies implementing lean manufacturing and six sigma have wealthy performance across financial performance, operational performance and innovation performance. It discovers various lean six sigma tools such as Kanban, TPM, 5S, VOC, Gemba etc, associated to improve financial or operational or innovation performance. Corporations get more advantage in using quality practices to improve quality, reduce cost, improve productivity and so on, compared to companies that have not implemented at all
Evaluation of the Operational Performance in Implementing Lean Manufacturing and Six Sigma
International audienc
- …