Radio range adjustment for energy efficient wireless sensor networks.

In wireless ad hoc sensor networks, energy use is in many cases the most important constraint since it corresponds directly to operational lifetime. Topology management schemes such as GAF put the redundant nodes for routing to sleep in order to save the energy. The radio range will affect the number of neighbouring nodes, which collaborate to forward data to a base station or sink. In this paper we study a simple linear network and deduce the relationship between optimal radio range and traffic. We find that half of the power can be saved if the radio range is adjusted appropriately compared with the best case where equal radio ranges are used

Hybrid Sliding Mode Control for a Set of Interconnected Nonlinear

Reports the use of sliding mode control in the design of a hybrid controller for a distributed system comprising a pair of loosely-coupled inverted pendulums. A sliding mode controller is designed to independently drive each pendulum mechanism to provide stabilization and profiled motion control. Then, to accomplish a reschedulable sequence of tasks, a supervisory system is developed using compositional methods and is modelled and analysed using controlled Petri nets. It is shown that using an appropriate coordination strategy it is possible to achieve a stability envelope for the composite system which is greater than that of the individual components

Constructing tests of cognitive abilities for schooled and unschooled children.

It is frequently necessary to assess children with little or no schooling to determine their level of cognitive functioning, especially in developing countries. It is not possible, however, to assume that assessments will hold equal validity for children with and without the experience of schooling. The authors, therefore, set out to create a battery of tests suitable for both schooled and unschooled children. They assessed 973 schooled and 645 unschooled children in rural coastal Kenya using culturally adapted cognitive tests. Significant effects of age and schooling were found on all tests. On some tests (verbal knowledge, speeded figure matching, and pattern copying), unschooled children did not improve as much with age as schooled children. The effects of length of exposure to schooling and of age were greater than that of initial enrollment in school. The authors conclude that it is possible to assess unschooled children, but test batteries must be carefully constructed and standardized