An energy aware algorithm for OLSR clustering

One of the important aspects of a mobile ad hoc network (MANET) is the limitation of the amount of available energy and the network lifetime. The tremendous amount of using mobile nodes in wireless communication medium makes energy efficiency a fundamental requirement for MANETs. In this paper, we propose a novel energy aware clustering algorithm for the optimized link state routing (OLSR) routing protocol. This algorithm takes into account the node density and mobility and gives major improvements regarding the number of elected cluster heads. Our objective is to elect a reasonable number of cluster heads that will serve for hierarchical routing based on OLSR. The proposed algorithm aims to increase the network lifetime by considering the ad hoc residual energy while taking routing decisions. It also optimizes the delay of carried flows by adopting a selective forwarding approach based on a hierarchical routing model.     

Observation of empty liquids and equilibrium gels in a colloidal clay

The relevance of anisotropic interactions in colloidal systems has recently emerged in the context of the rational design of new soft materials. Patchy colloids of different shapes, patterns and functionalities are considered the new building blocks of a bottom-up approach toward the realization of self-assembled bulk materials with predefined properties. The ability to tune the interaction anisotropy will make it possible to recreate molecular structures at the nano- and micro-scales (a case with tremendous technological applications), as well as to generate new unconventional phases, both ordered and disordered. Recent theoretical studies suggest that the phase diagram of patchy colloids can be significantly altered by limiting the particle coordination number (that is, valence). New concepts such as empty liquids—liquid states with vanishing density—and equilibrium gels—arrested networks of bonded particles, which do not require an underlying phase separation to form—have been formulated. Yet no experimental evidence of these predictions has been provided. Here we report the first observation of empty liquids and equilibrium gels in a complex colloidal clay, and support the experimental findings with numerical simulations.     

TEM investigation of irradiation damage in single crystal CeO2

In order to understand the evolution of radiation damage in oxide nuclear fuel, 150-1000 keV Kr ions were implanted into single crystal CeO₂, as a simulation of fluorite ceramic UO₂, while in situ transmission electron microscopy (TEM) observations were carried out. Two characteristic defect structures were investigated: dislocation/dislocation loops and nano-size gas bubbles.The growth behavior of defect clusters induced by 1 MeV Kr ions up to doses of 5 × 10¹⁵ ions/cm² were followed at 600 °C and 800 °C. TEM micrographs clearly show the development of defect structures: nucleation of dislocation loops, transformation to extended dislocation lines, and the formation of tangled dislocation networks. The difference in dislocation growth rates at 600 °C and 800 °C revealed the important role which Ce-vacancies play in the loop formation process. Bubble formation, studied through 150 keV Kr implantations at room temperature and 600 °C, might be influenced by either the mobility of metal-vacancies correlated with at threshold temperature or the limitation of gas solubility as a function of temperature.     

High-level design flow and environment for FPGA-based dynamic partial reconfiguration

The main motivation of this paper is related to the lack of a high-level design flow for field-programmable gate array (FPGA) partial dynamic reconfiguration management. Our contribution consists in proposing a high-level add-on methodology to the Xilinx’s design flow for dynamic partial reconfiguration (DPR). The main objective is to give an abstract view of the developed application in order to facilitate the designer task. The suggested design flow offers an application-centric view on dynamic reconfiguration designs, which permits simplifying the optimisation and generation of such designs. A new formulation of the reconfigurable modules’ mapping process is put forward. This allows a design space exploration so as to find the convenient number of reconfigurable regions and their sizes as well as the reconfiguration sequence. A new tool was proposed to support our methodology by allowing creating and synthesising graphical models of the developed application. We introduce a new block diagram to represent this latter and a sequence model that can be used for the design optimisations. To validate the proposed DPR design environment, two application examples are given at the end of the paper. They demonstrate the usefulness of the suggested models and methods.     

Effect of jamming and diversity on the performance of a wavelet packet based multicarrier multicode CDMA communication system

In this paper, the performance of multicarrier (MC), multicode (MCD), code division multiple access (CDMA) system employing wavelet packets (WPs) as subcarriers for modulation in the presence of narrowband interference is investigated. The performance analysis include the effects of diversity techniques such as selection, equal gain and maximal ratio combining. The system performance is evaluated by means of bit error rate (BER) and outage probability. The effects of system parameters such as channel intensity profile, diversity order and fading parameter on the system performances were investigated by means of analytical methods and numerical results. Also, the effect of jamming power is investigated. The performance of the system is compared to that of MC/MCD-CDMA based on sinusoidal carrier. Results reveal considerable performance improvement of the system that employ diversity techniques over the one without diversity and of our proposed system over the other system.     

Computational insights into the structure of barium titanosilicate glasses

Understanding the role of TiO₂ in BaO-TiO₂-SiO₂ (BTS) glasses is one of the keys to develop new glasses and glass-ceramics for different technological applications. For the first time, molecular dynamics simulations were conducted to get new insights into the atomic structure of the BTS glasses and their elastic moduli. Various compositions are studied where SiO₂ have been replaced by TiO₂. The calculated mechanical properties of our models are observed to depend linearly on TiO₂ content. However, the structure-induced changes are far from such dependence. The structural results indicate that BTS glasses are mainly built on four types of basic units: SiO₄, TiO₄, TiO₅ and TiO₆. This high structural heterogeneity induced by the three coordination states of Ti is found to have an impact on the medium range order by increasing the rings number, the polymerized regions, and by transforming Q₃-Q₄ and Q₂ without neglecting the increase in Q₅ and Q₆ species. Those structural modifications of the BTS glass network features have been found to be consistent with available experimental data.     

Direct normal irradiation-based approach for determining potential regions for concentrated solar power installations in Morocco

In this study, potential sites for concentrated solar power (CSP) installations in Morocco are investigated based on direct normal irradiation (DNI). The DNI data of four Moroccan sites (Missour, Erfoud, Zagora and Tantan) were collected from different satellite databases (NASA SSE, PV GIS-Helioclim, Climate-SAF PVGIS and Solar Med Atlas). However, it is required to mitigate the risks resulting from uncertainties of satellite-based irradiation data by combining satellite data to ground measurements of at least 1 year. The ground-measured data reported in this work are collected from MHP and MDI meteorological stations installed by IRESEN in collaboration with DLR and ONEE in the framework of the enerMENA project. The Liu and Jordan and the Collares Pereira and Rabl models were also used to determine the monthly and yearly average hourly DNI values. The results of this study suggest that Missour, Erfoud and Zagora represent potential sites for CSP power plants installations, except for Tantan.     

A Method for Predicting Long-Term Municipal Water Demands Under Climate Change

Water Resources Management - The accurate forecast of water demand is challenging for water utilities, specifically when considering the implications of climate change. As such, this is the first...     

Ability of the Performance Criteria to Assess and Compare Reservoir Management Approaches

Water Resources Management - A reservoir management approach requires, regularly, an update of its parameters in order to assure that the reservoir continue to fulfill its role without major...