Over the last few decades, algorithms inspired by nature have matured into a widely used class of computing methods. They have shown the ability to adjust to variety of conditions, and have been frequently employed for solving complex, real-world optimization problems. They are especially suitable for problems that require adaptation, and that involve optimization of complex, distributed system...

In opportunistic mobile networks (OppNets), nodes should be in listening state to discover the neighbors for opportunistic message forwarding. While in OppNets, contacts between nodes are sparse, most of the node’s energy is consumed in idle listening state, which highlights the need for energy saving in contact probing. Duty cycle operation can be applied to address this problem. However, it m...

Spatially organized clusters are basic structure for large-scale wireless sensor networks. A cluster is generally composed by a large amount of energy-limited low-tier nodes (LNs), which are managed by a powerful cluster head (CH). The low-tier nodes that are close to the cluster head generally become bottlenecks in data collection applications. Energy efficient scheduling is important for the ...

A strategy for energy saving in wireless sensor networks is to manage the duty cycle of sensors, by dynamically selecting a different set of nodes to be active in every moment. We propose a strategy for node selection in multihop sensor networks that prioritizes nodes with larger residual energy and relevance for the application. The proposed scheme is based on an implementation of the knapsack...

Spectrum sensing has been an active research area for the past two decades. Nonetheless, current spectrum sensing systems provide only coarse occupancy data. They lack information about the detailed signal patterns in each band and can easily miss fleeting signals like radar. This paper presents SpecInsight, a system for acquiring a detailed view of 4 GHz of spectrum in realtime. SpecInsight’s ...

Mission-critical surveillance applications such as intrusion detection or disaster response have strong requirements in communication delays. We consider a Wireless Image Sensor Network (WISN) with a scheduling of image sensor node’s activity based on the application criticality level. Sentry nodes capable of detecting intrusions with a higher probability than others will alert neighbor nodes a...

In this paper, we propose on energy efficient token based MAC protocol for WSNs, in order to reduce energy consumption of each sensor node which is one of the important issues to prolong the network lifetime. WSN consists of a large number of small and low-cost sensor nodes powered by small batteries and equipped with various sensing devices. Due to limited energy in WSN energy efficiency is an...

this study is focused on investigating the parameters of laser percussion drilling process of nickel-base super alloy inconel 718 with thickness of 1 mm. fiber laser with the power of 500 watts was used as the laser source. laser pulse frequency, duty cycle, laser power, focal point position, were assumed as the laser drilling process variables. the hole geometry features, i.e. entrance hole di...