UWB channel modeling for objects evolving in impulsive environnements

International audienceWe consider channel modeling issues in the context where communicating objects are evolving in impulsive environments. It was shown recently that α-stable random processes are attractive solution for representing the ultra wide band communication channel in relatively large spatial areas. In this paper, we consider the α-stable channel modeling in an evolutionary context where the model features depend on spatial locations. We introduce a methodological approach consisting of two parametric and non parametric components: the latter can be seen as black box model to describe the spatial evolution and it can be learned from historical observations of the transfer function. The other component concerns the frequency dependence and has an auto-regressive structure

Spectral representation of some non stationary alpha-stable processes

In this paper, we give a new covariation spectral representation of some non stationary symmetric $\alpha$-stable processes (S$\alpha$S). This representation is based on a weaker covariation pseudo additivity condition which is more general than the condition of independence. This work can be seen as a generalization of the covariation spectral representation of processes expressed as stochastic integrals with respect to independent increments S$\alpha$S processes (see Cambanis (1983)) or with respect to the general concept of independently scattered S$\alpha$S measures (Samorodnitsky and Taqqu 1994). Relying on this result we investigate the non stationarity structure of some harmonisable S$\alpha$S processes especially those having periodic or almost-periodic covariation functions

CHRONOLOGICAL STUDY OF THE VEGETATION OF FOREST MASSIF OF SDAMAS

The massif of Sdamas to which our contribution relates is located in West Algeria, it is an integral part of the mountains of Tiaret. The main objective of this work is to quantify the plant diversity of existing plant groups, and to understand the architecture and the structure of the various groups of vegetation by the method of floristic analysis and statistical analysis

SHORT-TERM EFFECT OF DISPERSION OF RESIDUAL SLUDGE ON THE SOIL EUCALYPTUS CAMALDULENSIS DEHNH, TIARET (ALGERIA)

Silvicultural upgrading of sewage sludge is an alternative to current solutions. It presents a lower risk of contamination of the human food chain than its use in agriculture. In this context, the use of forest plantations can offer many advantages

Phytoecological study of Tetraclinis articulata in the woodland of Beni Affene, Sdamas Chergui (Tiaret, Algeria)

The Mediterranean flora is definitely considered as an exceptional diversity that deserves particular attention to be conserved. This work aims to quantify the floristic diversity of Tetraclinis articulata of Beni Affane located at the woodland of Sdamas Chergui (Tiaret, Algeria). The factorial analysis of correspondences allowed us to jointly process the floristic and ecological variables, and confirm that there is presently an original floristic facies of Tetraclinis articulata. This study area contains 13 families and 21 species, where the dominating biological type is Chamaephytics (52 %). We have described as well five frequent species: Tetraclinis articulata 33 %, Pistacia lentiscus 11 %, Globularia alypum 8 %, Phylleria angustifolia 9 %, Rosmarinus tournefortii 15 %.Keywords: Tetraclinis articulata, Phytoecology, factorial analysis of correspondences, Beni Affane, Tiare

NEURO-GENETIC OPTIMIZATION OF MAGNETIC HYSTERESIS INTEGRATES IN ELECTROMAGNETIC SYSTEMS

International audienceIn this work we have presented an approach for calculating the hysteresis loop of Jiles-Atherton model using the magnetic inductance as the independent variable is proposed to be used directly in the calculation time step finite volume applied to the numerical analysis of nonlinear magnetic fields. This model is characterized by five parameters that must be identified and optimized for better representation of the measured characteristics. The parameters set of the Jiles–Atherton hysteresis model identified by using a real coded genetic algorithm. The parameters identification performed by minimizing the mean squared error between experimental and simulated magnetic field curves. The method verified by applying it to an axi-symmetrical ferromagnetic system. The calculated results validated by experiences performed in a Single Sheet Tester's frame (SST). In this work, we are interested to develop a model based on feed-forward neural networks of which can describe magnetic hysteresis by taking account the influence of some external sizes

Analysis of COVID-19 evolution based on testing closeness of sequential data

A practical algorithm has been developed for closeness analysis of sequential data that combines closeness testing with algorithms based on the Markov chain tester. It was applied to reported sequential data for COVID-19 to analyze the evolution of COVID-19 during a certain time period (week, month, etc.)