Uniform Stabilization of an Axially Moving Kirchhoff String by a Boundary Control of Memory Type

In this paper, we study the stabilization of solutions of an axially moving string of kirchhoff type by a viscoelastic boundary control. We prove that the dissipation produced by the viscoelastic term is sufficient to suppress the transversal vibrations that occur during the axial motion of the string, and we also show that the string displacement decays in an arbitrary rate. When comparing with immobile strings, we conclude that the movement of the string itself produces enough extra damping ensuring the stabilization.     

A Deep Learning Spatiotemporal Prediction Framework for Mobile Crowdsourced Services

Mobile Networks and Applications - This papers presents a deep learning-based framework to predict crowdsourced service availability spatially and temporally. A novel two-stage prediction model is...     

Closed loop torque SVM-DTC based on robust super twisting speed controller for induction motor drive with efficiency optimization

This paper presents a space vector modulation (SVM) based Direct Torque Control strategy (DTC) for induction motor (IM) in order to overcome the drawbacks of the classical DTC. SVM can reduce the high torque and flux ripples by preserving a fixed switching frequency. This technique is known by the closed loop torque SVM-DTC. Moreover, the control scheme performance is improved by inserting a second order sliding mode super twisting controller in the outer loop for speed regulation. This nonlinear technique ensures a good dynamic and high robustness against external disturbance. Furthermore, the IM energy optimization is treated in the second objective of this paper. A proposed model based loss minimization strategy is presented for efficiency optimization. This strategy chooses an optimal flux magnitude for each applied load torque. The proposed optimized SVM-DTC algorithm will be investigated by simulation and real time implementation using Matlab/Simulink with real time interface based on dSpace 1104 signal card.     

A faulty node detection scheme for wireless sensor networks that use data aggregation for transport

This paper presents a faulty node detection approach for wireless sensor networks that aggregate measurement data on their way toward the sink (base station). The approach is based on the idea of commanding sensor nodes on the aggregation paths to temporarily stop including their readings in the received aggregated readings from their upstream neighbors. The scheme is dependent on the ability of the sink to detect faulty nodes through changes in the received aggregated readings at the sink using a Markov Chain Controller (MCC). The algorithm that is run in the sink uses the MCC to assign a state to each sensor node based on transitions that are triggered by receiving aggregated path readings, and accordingly deduces the nodes that may be faulty. The experimental results show at least 98% detection rate at the cost of reasonable detection delays and generated wireless network traffic. Copyright © 2016 John Wiley & Sons, Ltd.     

Properties of the super-alpha composite transistor at high frequencies

The equivalent circuit of the composite transistor, the input impedance and the current gain have been developed by analysing its equivalent circuit, in terms of the various parameters of the individual transistors in the common base and common emitter configuration. It is found that in the C.E. configuration, the short-circuit input impedance hi_e has a negative resistance component over a frequency range in which the current gain in the C.B. configuration h/b is greater than 1.     

Coupled heat and moisture transfer in multi-layer building materials

A dynamic mathematical model for simulating the coupled heat and moisture migration through multi-layer porous building materials was proposed. Vapor content and temperature were chosen as the principal driving potentials. The discretization of the governing equations was done by the finite difference approach. A new experimental set-up was also developed in this study. The evolution of transient temperature and moisture distributions inside specimens were measured. The method for determining the temperature gradient coefficient was also presented. The moisture diffusion coefficient, temperature gradient coefficient, sorption–desorption isotherms were experimentally evaluated for some building materials (sandstone and lime-cement mortar). The model was validated by comparing with the experimental data with good agreement. Another advantage of the method lies in the fact that the required transport properties for predicting the non-isothermal moisture flow only contain the vapor diffusion coefficient and temperature gradient coefficient. They are relatively simple, and can be easily determined.     

Electric power generation based on variable speed wind turbine under load disturbance

This study was interested in the management of an energy production unit. A variable speed wind turbine (VSWT) was used as a principal source and a supercapacitor (SC) module was used as an energy storage system. Both were connected through a direct current bus. This unit was supplying a three-phase load using an inverter and an inductor and capacitor filter. In order to regulate the direct current bus voltage, the SC storage state was controlled by using a buck-boost converter according to load instructions and wind speed fluctuations. Then, a resonant controller was established to avoid any disturbances and to control the alternating line-to-line voltages of the load which may be unbalanced. This study has shown that the stability of the three-phase voltage source depends on the direct current bus power management and also on the line-to-line voltage control. Simulation results are presented to validate the efficiency of the control strategies used.     

Exploring deep insights into the interaction mechanism of a quinazoline derivative with mild steel in HCl: electrochemical,DFT, and molecular dynamic simulation studies

A novel quinazoline derivative, 3-cyclopropyl-3,4-dihydroquinoline-2(1H)-One (CPHQ), was successfully designed and synthesized. Then, its corrosion inhibition behavior on carbon steel (CS) surface in 1.0?M HCl at different temperatures was investigated using chemical, electrochemical and theoretical techniques. The experiments confirmed that the studied inhibitor shows inhibition efficiency as high as 95% even at very low concentration of 5?×?10^?3 M. To ascertain the nature of adsorption of CPHQ molecules on CS surface, Langmuir adsorption isotherm model was best fitted. From potentiodynamic polarization (PDP) calculations, it was concluded that the CPHQ acted as a mixed type corrosion inhibitor. Electrochemical impedance spectroscopy (EIS) studies revealed that increase in CPHQ concentration, resulted in an increase in the polarization resistance with a simultaneous decrease in the double-layer capacitance values. PDP tests were also performed to understand the corrosion behavior of CS as a function of temperature without and with varying concentrations of CPHQ, at temperatures 303, 313, 323, and 333?K. It can be concluded that the corrosion inhibition effect was dependent on the concentration of the inhibitor and the solution temperature. In order to understand the basic insights of the action mode of CPHQ molecules, Density Functional Theory (DFT) method, and Molecular Dynamic (MD) simulations were also employed on the optimized structure of CPHQ.     

Analyse de la stabilité spectrale d’un laser DFB à trois sauts de phase (3PS-DFB)

The aim of this article is to analyze the spectral stability of the three phase shift distributed feedback (3ps-dfb) laser by using Time domain model (tdm). We have developed a software that simulates static and dynamic properties of distributed feedback (dfb) multi-sections laser at large signal. The best single-mode stability operation up to 18mW of the 3ps-dfb is achieved for three phase shifts at (π, π, π) whatever the phase position. These results showed that the 3ps-dfb laser was a much more suitable structure to realize stable single-mode high-power operation for a coherent optical communication system.