Effect of Silicon Wafer Resistivity on Morphology and Wettability of Silicon Nanowires Arrays

Silicon - Herein, we prepare vertical and single crystalline silicon nanowires (SiNWs) via a one-step metal-assisted chemical etching method in aqueous NH4HF2/AgNO3 solution. The effects of silicon...     

Performance analysis of a solar chimney power plant in the southwestern region of Algeria

In this paper, we present the performance analysis of a solar chimney power plant expected to provide the remote villages located in Algerian southwestern region with electric power. Solar energy and the psychometric state of the air in the south of Algeria are important to encourage the full development of solar chimney power plant for the thermal and electrical production of energy for various uses. We are interested in Adrar where solar radiation is better than other areas of Algeria. The obtained results show that the solar chimney power plant can produce from 140 to 200 kW of electricity on a site like Adrar during the year, according to an estimate made on the monthly average of sunning. This production is sufficient for the needs of the isolated areas.     

Wind energy conversion system associated to a flywheel energy storage system

This paper deals with the study of a variable speed wind induction generator associated to a flywheel energy storage system. Direct torque control strategy is applied to control the induction generator where both rotor flux and DC bus voltage are controlled through the application of the standard switching table for operations in the 4 quadrants. The flywheel energy storage system is used to improve the quality of the electric power delivered by the wind generator. The proposed system, controlled thanks to Direct Torque Control (DTC) strategy, is validated through simulations. The obtained results are presented and discussed.     

Software‐defined satellite cloud RAN

This paper provides an assessment study on the virtualization of a Digital Video Broadcasting ‐ Satellite ‐ Second Generation (DVB‐S2)/ Digital Video Broadcasting ‐ Return Channel Satellite ‐ Second Generation (DVB‐RCS2) satellite ground infrastructure and proposes a framework, named Satellite Cloud Radio Access Network (SatCloudRAN), that aims to ease the integration of satellite components in forthcoming 5G systems. Special attention is given to the design of SatCloudRAN by considering the split and placement of virtualized and nonvirtualized functions while taking into account the characteristics of the transport links connecting both type of functions. We assess how virtualization and softwarization technologies, namely, network function virtualization and software‐defined networking, can deliver part of the satellite gateway functionalities as virtual network functions and achieve a flexible and programmable control and management of satellite infrastructure. Under the network function virtualization paradigm, building virtual network function blocks that compose a satellite gateway have been identified, and their interaction exhibited. This paper also gives insights on how the SatCloudRAN approach can allow operators to provide software‐defined networking‐based (1) bandwidth on demand, (2) dynamic Quality of Service, and (3) satellite gateway diversity. Copyright © 2017 John Wiley & Sons, Ltd.     

P2P Object-based adaptivE Multimedia Streaming (POEMS)

Peer-to-peer (P2P) paradigm has recently gained tremendous attraction and is widely used for content distribution and sharing. The future multimedia communication applications have to support the user’s needs, the terminal capabilities, the content specification and the underlying networking technologies. They should be network-aware, topology-aware, and end-user-centric. Thus, in this paper, we use the characteristics of the object-based encoding scheme and P2P network topology to propose adaptive content delivery architecture for P2P networks. We propose an efficient mechanism for transmission of real-time content over P2P networks, called POEMS (P2P Object-based adaptivE Multimedia Streaming). This object-based audio-visual quality adaptive mechanism over P2P networks is media-aware, network-aware, and user-centric that is carried-out through (1) selection of appropriate sending peers willing to participate in the streaming mechanism, (2) organization of sending peers by constructing an overlay network to facilitate content delivery and adaptation, (3) dynamicity management of peers when some peer enters or leaves the system to maintain an acceptable level of perceived video quality, and (4) ensuring the end-to-end QoS (Quality of Services) by orchestrating the overall streaming mechanism. The obtained results demonstrate that combining content adaptation using object-based encoding and advance network-aware peers selection based on peer monitoring leads to intelligent, efficient, and large-scale support of multimedia services over complex network architectures.

Investigation of the use of a central unique renewable energy system versus distributed units for crop irrigation

This paper discusses a comparison study of the use of 100% renewable energy systems for desert and remote areas, investigating both a central unique unit and distributed units. An initial HRES consisting of a photovoltaic (PV) array and wind generator is used to power an agricultural area of 4 ha once with a central unit and then with four distributed units. The selection of the optimal size is accomplished through linear programming based on the simplex algorithm to minimize the total life cycle cost. The results show for the first time that the use of a distributed renewable energy system containing a full PV array is cost-effective compared to a central unit.     

Performance and scalability evaluation of IEEE 802.11v/aa multicast transport

IEEE 802.11v and 802.11aa are two recent amendments that define new functionalities in order to support a reliable multicast transport over wireless networks. The first amendment introduces directed multicast service (DMS). On the other hand, 802.11aa defines the groupcast with retries (GCR) service, which proposes two retransmission policies: block acknowledgement (GCR‐BACK) and unsolicited retry (GCR‐UR). In this paper, we evaluate the throughput and the scalability of these new proposals using both analytical and simulation approaches. We show that DMS has the lowest scalability, while GCR‐BACK is not appropriate for groups with a large number of receivers. We conclude that GCR‐UR is the most appropriate for large groups. However, increasing the number of transmission retries reduces significantly the achieved throughput of the unsolicited retry policy. Copyright © 2016 John Wiley & Sons, Ltd.