Pourquoi ya-t-il une vitésse indépassable en physique modérne ? cette idée vient entre autres du refus d'Einstein d'admettre des actions immédiates à distance ? en particulier l'idée de la gravitation de Newton qui implique une transition instantanée d'information.
le refus d'une telle action a pour conséquence que si un evenement se produit en A, son effet prend un temps fini pour se transmettre à un point B situé à une distance finie non nulle, mais s'il faut un certain temps pour parcourir cette distance, cela signifie qu'il ne peut pas y avoir une vitésse qui représente la borne supérieure de toutes le vitésses.

mehdialami

On the use of mathematical modeling in biotechnological systems.
the methodology involved in the modeling and simulation of physical, life and social science systems is viewed in perspective a critical factor determining the validity of a model is the extent to which it can be derived from basic laws and insights into the internal structure of the system using deductive methods, rather than relying upon observations and measurements of the system input and outputs, accordingly the mathematical models as they arise in various application disciplinesq arranged along a spectrum according to the relative amount of deduction and induction involved in their construction, this provides an insight into the ultimate validity of simulations and to what use they can properly be put.

mehdialami

periodic solutions of the volterra's model for the interaction between the biological species.
We first study the volterra's model for k=1 by the liapunov's method.
a family of periodic solutions is obtained in the form of convergent series easly computed in terms of elementary periodic functions, comparison with the results of the numerical integration gives a good coincidence of the two first approximations of the solutions in rather large neighbourhood of the point d'equilibrium.
For the 2k-species set we can prove the existence of k families of periodic selection depending on two parameters in the previous form, this existence is proved in nearly all the cases if there is a certain equilibrium between the disappearance of the species we also study the evolution of periodic solutions (k=1) if the coefficients of the equations are adiabetic variable and periodic.
the thorem of V.Arnold and adiabatic invariants is applied, it proves that for most initial data, the movement is quasi periodic.

mehdialami

mathematical models are found in different subdomains of psychology :
- From early beginnings the test and scaling methodology have been important fields in psychology, sophisticated mathematical models have increasngly been used in these fields, we refer to the development of functional probabilistic models and multivariants models, another trend which shows itself in the last years is the development of axiomatic systems.
- The contributions of those psychologists who since the sixties, call themselves " mathematical psychologists", consist mainly in the development of mathematical model as hypothetical descriptions of specific psychological processes , e.g. models on memory processes, concept learning, perception, perceptual and motor performance, reaction time,choice and decision, social interaction, the modelling is adapted to the kind of phenomenon under study and consequently there exists a great heterogeneity of models as well in form as in content.
- Within the framework of the evolution of computer applications several computer models have been developped for perceptual and cognitive processes, more ambitions computer models try to simulate different personality types (e.g. simulation of pathological processes) and social organizational behaviour.

mehdialami

Reveil tôt ce matin !
même s 'ils ont annoncé une mauvaise meteo, la journée se déclare plutot ensoleillée !

Revenez souvent ! je promet de partager un maximum de choses avec le lecteurs de ce blog !

bonne journée.

najiboo