The expression for the (π + π −) atom lifetime is derived within the Bethe-Salpeter approach. First-order perturbative corrections due to the contribution of strong interactions are taken into account. It is demonstrated that the atom lifetime can be expressed in terms of the solutions of the Coulombic problem (the wave function of the 1S state at the origin Ψ 1 (0), the binding energy of the S...

Clustering in wireless sensor networks (WSNs) is an important technique to ease topology management and routing. Clustering provides an effective method for prolonging lifetime of a WSN. This paper proposes energy efficient multilevel clustering schemes for wireless sensor networks. Wireless sensor nodes are extremely energy constrained with a limited transmission range. Due to large area of de...

the objective of this paper is to provide an overview of various approaches on iran’s nuclear program and the frameworks within which the approaches can be located. it first addresses different views held in relevant think tanks and academic circles in the u.s. regarding iran’s nuclear program, including motivation-based and consequence-based arguments in their different variants. then iranians...

In this work, we present an energy efficient hierarchical cooperative clustering scheme for wireless sensor networks. Communication cost is a crucial factor in depleting the energy of sensor nodes. In the proposed scheme, nodes cooperate to form clusters at each level of network hierarchy ensuring maximal coverage and minimal energy expenditure with relatively uniform distribution of load withi...

The effect of a finite space–time extent of particle production region on the lifetime measurement of hadronic atoms produced by a high energy beam in a thin target is discussed. Particularly, it is found that the neglect of this effect on the pionium lifetime measurement in the experiment DIRAC at CERN could lead to the lifetime overestimation on the level of the expected 10% statistical error...

Energy limitation of a sensor network is a very important feature which distinguishes it from traditional networks and a number of methods to saving energy consumption have been studied in sensor networks. Most of those works have focused on Network, MAC or PHY layer and the lifetime of a sensor network cannot be pre-determined. But some sensor network might be able to survive for some specifie...

Customer activity has received more attention due to the increase of social network applications. Moreover, customer activity could be an answer to the research debate about the significant relationship between retention rate and lifetime profitability of customers. Several researchers believe that an increase in the retention rate of customers may enhance their customer lifetime value (CLV), o...