Energy efficient teaching-learning-based optimization for the discrete routing problem in wireless sensor networks

Wireless sensor networks (WSNs) are composed of sensor nodes, having limited energy resources and low processing capability. Accordingly, major challenges are involved in WSNs Routing. Thus, in many use cases, routing is considered as an NP-hard optimization problem. Many routing protocols are based on metaheuristics, such as Ant Colony Optimization (ACO) and Particle Swarm Optimization (PSO). Despite the fact that metaheuristics have provided elegant solutions, they still suffer from complexity concerns and difficulty of parameter tuning. In this paper, we propose a new routing approach based on Teaching Learning Based Optimization (TLBO) which is a recent and robust method, consisting on two essential phases: Teacher and Learner. As TLBO was proposed for continuous optimization problems, this work presents the first use of TLBO for the discrete problem of WSN routing. The approach is well founded theoretically as well as detailed algorithmically. Experimental results show that our approach allows obtaining lower energy consumption which leads to a better WSN lifetime. Our method is also compared to some typical routing methods; PSO approach, advanced ACO approach, Improved Harmony based approach (IHSBEER) and Ad-hoc On-demand Distance Vector (AODV) routing protocol, to illustrate TLBO’s routing efficiency.     

Discrete kinetic theory for 2D modeling of a moving crowd: Application to the evacuation of a non-connected bounded domain

This paper concerns the mathematical modeling of the motion of a crowd in a non connected bounded domain, based on kinetic and stochastic game theories. The proposed model is a mesoscopic probabilistic approach that retains features obtained from both micro- and macro-scale representations; pedestrian interactions with various obstacles being managed from a probabilistic perspective. A proof of the existence and uniqueness of the proposed mathematical model’s solution is given for large times. A numerical resolution scheme based on the splitting method is implemented and then applied to crowd evacuation in a non connected bounded domain with one rectangular obstacle. The evacuation time of the room is then calculated by our technique, according to the dimensions and position of a square-shaped obstacle, and finally compared to the time obtained by a deterministic approach by means of randomly varying some of its parameters.     

Efficiency Improvement of Dual-Band Wireless Power Transfer (DB-WPT) System with U-shape Resonator and Capacitively Loaded E-shape Defected Ground Structure (DGS)

Wireless Personal Communications - The ceaseless increase in the number of the wireless Internet of Things (IoT) devices has resulted in the need of different traffic engineering techniques to...     

IARP: An Intelligent ACO-Based Routing Protocol with Multiple Mobile Sinks Support for Wireless Sensor Networks

Wireless Personal Communications - Using a single fixed sink in wireless sensor networks (WSNs) creates the hotspot problem. Recently, the mobile sink technique is considered as a good solution to...     

A pure geometric theory of gravity and a material distribution

A field theory is constructed in the context of parameterized absolute parallelism geometry. The theory is shown to be a pure gravity one. It is capable of describing the gravitational field and a material distribution in terms of the geometric structure of the geometry used (the parallelization vector fields). Three tools are used to attribute physical properties to the geometric objects admitted by the theory. Poisson and Laplace equations are obtained in the linearized version of the theory. The spherically symmetric solution of the theory, in free space, is found to coincide with the Schwarzschild exterior solution of general relativity. The theory respects the weak equivalence principle in free space only. Gravity and the material distribution are not minimally coupled.     

Infrastructure Deployment in Vehicular Communication Networks Using a Parallel Multiobjective Evolutionary Algorithm

This article describes the application of a multiobjective evolutionary algorithm for locating roadside infrastructure for vehicular communication networks over realistic urban areas. A multiobjective formulation of the problem is introduced, considering quality‐of‐service and cost objectives. The experimental analysis is performed over a real map of Málaga, using real traffic information and antennas, and scenarios that model different combinations of traffic patterns and applications (text/audio/video) in the communications. The proposed multiobjective evolutionary algorithm computes accurate trade‐off solutions, significantly improving over state‐of‐the‐art algorithms previously applied to the problem.     

Efficient and dynamic scaling of fog nodes for IoT devices

It is predicted by the year 2020, more than 50 billion devices will be connected to the Internet. Traditionally, cloud computing has been used as the preferred platform for aggregating, processing, and analyzing IoT traffic. However, the cloud may not be the preferred platform for IoT devices in terms of responsiveness and immediate processing and analysis of IoT data and requests. For this reason, fog or edge computing has emerged to overcome such problems, whereby fog nodes are placed in close proximity to IoT devices. Fog nodes are primarily responsible of the local aggregation, processing, and analysis of IoT workload, thereby resulting in significant notable performance and responsiveness. One of the open issues and challenges in the area of fog computing is efficient scalability in which a minimal number of fog nodes are allocated based on the IoT workload and such that the SLA and QoS parameters are satisfied. To address this problem, we present a queuing mathematical and analytical model to study and analyze the performance of fog computing system. Our mathematical model determines under any offered IoT workload the number of fog nodes needed so that the QoS parameters are satisfied. From the model, we derived formulas for key performance metrics which include system response time, system loss rate, system throughput, CPU utilization, and the mean number of messages request. Our analytical model is cross-validated using discrete event simulator simulations.     

Shear effect on dynamic behavior of microcantilever beam with manufacturing process defects

This paper is concerned with the investigation of the shear effect on the dynamic behavior of a thin microcantilever beam with manufacturing process defects. Unlike the Rayleigh beam model (RBM), the Timoshenko beam model (TBM) takes in consideration the shear effect on the resonance frequency. This effect become significant for thin microcantilever beams with larger slenderness ratios that are normally encountered in MEMS devices such as sensors. The TBM model is presented and analyzed by numerical simulation using Finite Element Method (FEM) to determine corrective factors for the correction of the effect of manufacturing process defects like the underetching at the clamped end of the microbeam and the nonrectangular cross section of the area. A semi-analytical approach is proposed for the extraction of the Young’s modulus from 3D FEM simulation with COMSOL Multiphysics software. This model was tested on measurements of a thin chromium microcantilever beam of dimensions (80 × 2 × 0.95 μm³). Final results indicate that the correction of the effect of manufacturing process defects is significant where the corrected value of Young’s modulus is very close to the experimental results and it is about 280.81 GPa.

     

Understanding the Thermal Regime of Rivers Influenced by Small and Medium Size Dams in Eastern Canada

Although small and medium‐size dams are prevalent in North America, few studies have described their year‐round impacts on the thermal regime of rivers. The objective of this study was to quantify the impacts of two types of dams (run‐of‐river, storage with shallow reservoirs) on the thermal regime of rivers in eastern Canada. Thermal impacts of dams were assessed (i) for the open water period by evaluating their influence on the annual cycle in daily mean water temperature and residual variability and (ii) for the ice‐covered winter period by evaluating their influence on water temperature duration curves. Overall, results showed that the run‐of‐river dam (with limited storage capacity) did not have a significant effect on the thermal regime of the regulated river. At the two rivers regulated by storage dams with shallow reservoirs (mean depth < 6 m), the annual cycle in daily mean water temperature was significantly modified which led to warmer water temperatures in summer and autumn. From August to October, the monthly mean water temperature at rivers regulated by storage dams was 1.4 to 3.9°C warmer than at their respective reference sites. During the open water period, the two storage dams also reduced water temperature variability at a daily timescale while increased variability was observed in regulated rivers during the winter. Storage dams also had a warming effect during the winter and the winter median water temperature ranged between 1.0 and 2.1°C downstream of the two storage dams whereas water temperature remained stable and close to 0°C in unregulated rivers. The biological implications of the altered thermal regimes at rivers regulated by storage dams are discussed, in particular for salmonids. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of hydrodynamics on dynamics of phase separation in polystyrene/poly(vinyl methyl ether) blend

Polystyrene/poly(vinyl methyl ether) (PS/PVME) phase diagram was assessed by rheological tools and by on-line microscopy observations both under quiescent and shear flow conditions. Shear flow was found to induce both mixing and demixing of the mixture depending on the amplitude of the imposed shear rate. Viscoelastic properties of PS/PVME blends were also measured under steady shear flow near the phase separation temperature. At lower shear rate, flow enhances concentration fluctuation and induces phase segregation. At high shear rate, flow suppresses fluctuations and the polymer mixture keeps its miscible state. Several rheological signatures of phase transition were found. In steady shear flow, a secondary plateau in viscosity was observed when the temperature was close to T_s whereas, at the start-up shear flow, transient shear stress showed a second overshoot after a few minutes of shearing.