Energy-aware dynamic resource allocation in virtual sensor networks

Sensor network virtualization enables the possibility of sharing common physical resources to multiple stakeholder applications. This paper focuses on addressing the dynamic adaptation of already assigned virtual sensor network resources to respond to time varying application demands. We propose an optimization framework that dynamically allocate applications into sensor nodes while accounting for the characteristics and limitations of the wireless sensor environment. It takes also into account the additional energy consumption related to activating new nodes and/or moving already active applications. Different objective functions related to the available energy in the nodes are analyzed. The proposed framework is evaluated by simulation considering realistic parameters from actual sensor nodes and deployed applications to assess the efficiency of the proposals

A Novel Direct Extraction Method for Internal Equivalent Circuit Parameters of HBT Small-Signal Hybrid-Pi Model

A novel and accurate method for the direct extraction of HBT small-signal hybrid-Pi model parameters is proposed. The main feature of this method is that a unique set of intrinsic parameters is calculated for the whole frequency range of operation using a least-squares data fitting algorithm. This algorithm consists of an estimation from measured S-parameters of a set of new analytical equations derived from the intrinsic HBT equivalent-circuit Y-parameters. Experimental validation on an HBT device with a 2x25 mm emitter was carried out, and excellent results were obtained up to 30 GHz

Acute rheumatic fever in Tunisia. Serotypes of group A streptococci associated with rheumatic fever.

International audienceRheumatic fever (RF) is a serious health threat in our country. The annual incidence of cases of acute rheumatic fever (ARF) in 1990 was 30 per 100,000 school-aged children, the prevalence of rheumatic heart diseases (RHD) was 3–6% in school children. The incidence of ARF have declined in North America and Western Europe over the past four decades. However, recent outbreaks of ARF in the United States have been reported