Search results for "Statistical"
showing 10 items of 4960 documents
Optimal pareto solutions of a dynamic C chart: An application of statistical process control on a semiconductor devices manufacturing process
2015
The present paper proposes a novel economic-statistical design procedure of a dynamic c control chart for the Statistical Process Control (SPC) of the manufacturing process of semiconductor devices. Particularly, a non-linear constrained mathematical programming model is formulated and solved by means of the ε-constraint method. A numerical application is developed in order to describe the Pareto frontier, that is the set of optimal c charts and the related practical considerations are given. The obtained results highlight how the performance of the developed dynamic c chart overcome that of the related static one, thus demonstrating the effectiveness of the proposed procedure.
Inferring slowly-changing dynamic gene-regulatory networks
2015
Dynamic gene-regulatory networks are complex since the interaction patterns between their components mean that it is impossible to study parts of the network in separation. This holistic character of gene-regulatory networks poses a real challenge to any type of modelling. Graphical models are a class of models that connect the network with a conditional independence relationships between random variables. By interpreting these random variables as gene activities and the conditional independence relationships as functional non-relatedness, graphical models have been used to describe gene-regulatory networks. Whereas the literature has been focused on static networks, most time-course experi…
Dynamical decoupling efficiency versus quantum non-Markovianity
2015
We investigate the relationship between non-Markovianity and the effectiveness of a dynamical decoupling protocol for qubits undergoing pure dephasing. We consider an exact model in which dephasing arises due to a bosonic environment with a spectral density of the Ohmic class. This is parametrised by an Ohmicity parameter by changing which we can model both Markovian and non-Markovian environments. Interestingly, we find that engineering a non-Markovian environment is detrimental to the efficiency of the dynamical decoupling scheme, leading to a worse coherence preservation. We show that each dynamical decoupling pulse reverses the flow of quantum information and, on this basis, we investig…
Short chaotic strings and their behaviour in the scaling region
2008
Coupled map lattices are a paradigm of higher-dimensional dynamical systems exhibiting spatio-temporal chaos. A special case of non-hyperbolic maps are one-dimensional map lattices of coupled Chebyshev maps with periodic boundary conditions, called chaotic strings. In this short note we show that the fine structure of the self energy of this chaotic string in the scaling region (i.e. for very small coupling) is retained if we reduce the length of the string to three lattice points.
Overload breakdown in models for photosynthesis
2015
In many models of the Calvin cycle of photosynthesis it is observed that there are solutions where concentrations of key substances belonging to the cycle tend to zero at late times, a phenomenon known as overload breakdown. In this paper we prove theorems about the existence and non-existence of solutions of this type and obtain information on which concentrations tend to zero when overload breakdown occurs. As a starting point we take a model of Pettersson and Ryde-Pettersson which seems to be prone to overload breakdown and a modification of it due to Poolman which was intended to avoid this effect.
Analytical properties of horizontal visibility graphs in the Feigenbaum scenario
2012
Time series are proficiently converted into graphs via the horizontal visibility (HV) algorithm, which prompts interest in its capability for capturing the nature of different classes of series in a network context. We have recently shown [1] that dynamical systems can be studied from a novel perspective via the use of this method. Specifically, the period-doubling and band-splitting attractor cascades that characterize unimodal maps transform into families of graphs that turn out to be independent of map nonlinearity or other particulars. Here we provide an in depth description of the HV treatment of the Feigenbaum scenario, together with analytical derivations that relate to the degree di…
Feigenbaum graphs: a complex network perspective of chaos
2011
The recently formulated theory of horizontal visibility graphs transforms time series into graphs and allows the possibility of studying dynamical systems through the characterization of their associated networks. This method leads to a natural graph-theoretical description of nonlinear systems with qualities in the spirit of symbolic dynamics. We support our claim via the case study of the period-doubling and band-splitting attractor cascades that characterize unimodal maps. We provide a universal analytical description of this classic scenario in terms of the horizontal visibility graphs associated with the dynamics within the attractors, that we call Feigenbaum graphs, independent of map…
Time operators, innovations and approximations
2003
Abstract We present a new approach to the spectral analysis and prediction of such complex systems for which the time evolution is described by a semigroup of operators. This approach is based on an extended concept of time operator and can be interpreted as a shift representation of dynamical systems. The time operator method includes the multiresolution analysis of wavelets as a particular case but can also be applied for a substantially larger class of dynamical systems. Among the examples where shift representation have been explicitly derived are exact endomorphisms, the diffusion equation, generalized shifts associated with the Haar or Faber–Schauder basis and some classes of stochast…
The thin and medium filters of the EPIC camera on-board XMM-Newton: measured performance after more than 15 years of operation
2016
After more than 15 years of operation of the EPIC camera on board the XMM-Newton X-ray observatory, we have reviewed the status of its Thin and Medium filters. We have selected a set of Thin and Medium back-up filters among those still available in the EPIC consortium and have started a program to investigate their status by different laboratory measurements including: UV/VIS transmission, Raman scattering, X-Ray Photoelectron Spectroscopy, and Atomic Force Microscopy. Furthermore, we have investigated the status of the EPIC flight filters by performing an analysis of the optical loading in the PN offset maps to gauge variations in the optical and UV transmission. We both investigated repea…
L'ontogenèse complexe du spatangue Echinocardium cordatum: Un test des standards des trajectoires hétérochroniques
1991
The growth of the spatangoid echinoid Echinocardium cordatum is described by using the three standards (size,shape and age) that are classicaly involved in analyses of heterochronies. A population from Normandy, including all the growth stages, allows an ontogenetic reference to be established, while comparisons are performed with adult samples from other localities (Brittany, Aquitaine, and New-Zealand). The morphology of E. cordatum is characterized by 23 measured parameters and 13 calculated indexes. The ontogenetic trajectory of the species is depicted from the measurements of the size increments, from the analysis of the shape changes, and from an estimate of age. An estimate of the ag…