We discuss the security requirements and analyze the requirements for secure group communication in grid circumstance. When several processes generated by a user want to communicate securely, they have to share a secret key to communicate. We propose a secret key administration algorithm in dynamically circumstance. The security and efficiency of our scheme is analyzed.

promise de port fort is an useful legal basic for justification many civil and commercial transactions. such as bank guaranties, insurance and guaranty of things it divides two legal relations, relation between parties if third party not ratify and relation with third party if she or he ratify that promise. unlike its appearance, it, is not violation the principle of relativity of contracts. be...

In this paper, we adapt the operational Tau Method for personal computers and apply it to a system of two nonlinear second order ordinary differential equations which are related to general relativity. The interesting behaviour this problem exhibits in its numerical treatment is discussed. In this problem, we try to use the Tau perturbation term to locate the correct solution of this nonlin...

The categorical relativity is a groupoid category of massive bodies in mutual motions. The relative velocity is defined to be the basis-free and coordinate-free binary morphism. In categorical relativity there is no need to distinguish separately the constant relative velocities (special relativity) from the variable accelerated velocities, hence the categorical relativity goes beyond boundary ...

István Németi, together with Hajnal Andréka founded and lead the Hungarian logic and relativity school. They havemade numerous significant contributions both in logic and in relativity theory and in their interconnections. To celebrate their contributions, on the occasion of István’s 70th birthday, a series of conferences focusing on logic and relativity theory, and beyond, was inaugurated by T...

In the evaluation of non-efficient units by Data Envelopment Analysis (DEA) referenced Decision Making Units (DMU’s) have an important role. Unfortunately DMU’s with extra ordinary output can lead to a monopoly in a reference set, the fact called abnormality due to the outliers' data. In this paper, we introduce a DEA model for evaluating DMU’s under this circumstance. The layer model can resul...

in this paper, we adapt the operational tau method for personal computers and apply it to a system of two nonlinear second order ordinary differential equations which are related to general relativity. the interesting behaviour this problem exhibits in its numerical treatment is discussed. in this problem, we try to use the tau perturbation term to locate the correct solution of this nonlinear ...

This paper presents some ideas which might assist teachers incorporating special relativity into an introductory physics curriculum. One can define the proper-time/velocity pair, as well as the coordinate-time/velocity pair, of a traveler using only distances measured with respect to a single “map” frame. When this is done, the relativistic equations for momentum, energy, constant acceleration,...