Performances of the Barra–Costantini passive heating system under Algerian climate conditions

The present work studies the Barra–Costantini passive solar heating system, with particular emphasis on the aspect of economics. The system which is studied is developed by Barra and Constantini. This system seems to be well adapted to the climatic and economic conditions in Algeria. In the first part of this work, an ideal model representing the thermal behavior of a room provided with the heating device is elaborated. The results of this model are compared with the results of an experimental study carried out on an Italian site. Initially, the model was used to determine the temperature variation for the different elements of a room with the Barra–Costantini (B-C) system. The model is then used for conditions corresponding to several Algerian sites. This study makes it possible to quantify the energy savings obtained by the addition of the B-C system to a traditional gas heating system. The introduction of a ratio between the cost of energy and the cost of equipment makes it possible to conclude that only the intervention of the authorities can make the passive solar system economically viable.     

Electrochemical stability of core–shell structure electrode for high voltage cycling as positive electrode for lithium ion batteries

The core–shell type cathode material Li[(Ni_0.8Co_0.1Mn_0.1)_0.8(Ni_0.5Mn_0.5)_0.2]O₂ (CS) for Li-ion battery was synthesized via co-precipitation method. The electrochemical and thermal properties of the core–shell structured Li[(Ni_0.8Co_0.1Mn_0.1)_0.8(Ni_0.5Mn_0.5)_0.2]O₂ were compared with those of the average composition of core–shell Li[Ni_0.74Co_0.08Mn_0.18]O₂ (ACCS) and the mixture of the core Li[Ni_0.8Co_0.1Mn_0.1]O₂ and the shell Li[Ni_0.5Mn_0.5]O₂ material (MCS). The CS shows the enhanced electrochemical properties in a high voltage range (4.5 V and 4.6 V) as well as the typical cut-off voltage range (4.3 V). The capacity retentions of CS, core, and ACCS material were 94.2% (176.9 mAh g⁻¹), 86.6% (172 mAh g⁻¹), and 88.4% (169.3 mAh g⁻¹) after 120 cycles, respectively.     

GPU fuzzy c-means algorithm implementations: performance analysis on medical image segmentation

Multimedia Tools and Applications - Image segmentation in the medical imagery such as MRI, is an essential step to the sensitive analysis of human tissues lesions with the objective to improve the...     

Internet of Things for the Future of Smart Agriculture: A Comprehensive Survey of Emerging Technologies

This paper presents a comprehensive review of emerging technologies for the internet of things(IoT)-based smart agriculture.We begin by summarizing the existing surveys and describing emergent technologies for the agricultural IoT,such as unmanned aerial vehicles,wireless technologies,open-source IoT platforms,software defined networking(SDN),network function virtualization(NFV)technologies,cloud/fog computing,and middleware platforms.We also provide a classification of IoT applications for smart agriculture into seven categories:including smart monitoring,smart water management,agrochemicals applications,disease management,smart harvesting,supply chain management,and smart agricultural practices.Moreover,we provide a taxonomy and a side-by-side comparison of the state-ofthe-art methods toward supply chain management based on the blockchain technology for agricultural IoTs.Furthermore,we present real projects that use most of the aforementioned technologies,which demonstrate their great performance in the field of smart agriculture.Finally,we highlight open research challenges and discuss possible future research directions for agricultural IoTs.     

Dodecylhydroxydiphosphonic Acid for Solvent Extraction

Abstract

The extraction behavior of Zn(II) and Cu(II) in acetate media has been investigated using dodecylhydroxydiphosphonic acid, DHDPA, which was previously synthesized and characterized. The extraction of both cations was carried out in different media with the addition of CH₃COOH, HCl or H₂SO₄ at different pH. The maximum extraction yield of 80% for zinc, was obtained in one step after the addition of sulfuric acid at pH_i=5.5 and for copper after the addition of 10 mg of sodium acetate. The authors plan additional tests using polar solvents.     

Investigating the impact of Cloisite® 15A nanoclays on the diffusivity of Irganox 1035 antioxidant in high-density polyethylene nanocomposite

Knowing the diffusion coefficients of antioxidants in packaging materials is essential to assess their effectiveness in protecting materials against oxidation, but also to prevent their eventual migration to food. In this work, the diffusion of a commercial phenolic antioxidant (Irganox 1035) was measured experimentally in pristine high-density polyethylene (HDPE) and in HDPE nanocomposite filled with 3 wt% of nanoclays (Cloisite® 15A). Diffusion experiments were performed using the Roe's method between 60 and 100°C. The local concentration of Irganox1035 in each film was measured by UV–Vis spectroscopy from the UV absorbance at 282 nm. The adjustment of the experimental data by Fick's second law allowed us to deduce the values of the diffusion coefficient of Irganox1035 at each temperature and to show that the temperature dependence of this coefficient obeys an Arrhenius' law. It is shown that the incorporation of 3 wt% of Cloisite®15A into HDPE significantly hinders the diffusion of Irganox 1035 and increases its activation energy. Several mechanistic assumptions could explain this result, first the increase in the tortuosity of diffusion paths, but also the possible establishment of strong intermolecular interactions between the antioxidant and some chemical groups on the nanofiller surface, or even the formation of an interphase with reduced molecular mobility around the nanofillers.     

Numerical and experimental investigations of mixing in T-shaped and cross-shaped micromixers

Mass transfer within the T-shaped and cross-shaped micromixers has been studied using CFD and confocal laser scanning microscopy methods. The concentration profiles, based on flow regimes, were used to compare the T- and cross-geometries. The cross-shaped micromixer tends to intensify the mixing and this is occurring for lower flow rates in comparison to the T shape. The improvement made by the cross geometry is attributed to the stronger vortex stretching and high shear rate, which reduces the liquid transfer length. The presence of a single outlet in the T-shaped micromixer induces a smaller degree of freedom for the fluid. A higher pressure drop is calculated in T-shaped micromixer than in cross-shaped micromixer.     

Four‐parameter beta distribution estimation and skewness test

Sequential tolerance control (STC) is a tolerance control methodology used in discrete parts manufacturing. Recently, an adaptive sphere‐fitting method for STC (ASF–STC) was developed to account for potential skewness in manufacturing operations' distributions, a factor not considered in conventional STC. ASF–STC offers significant improvements over conventional STC when such skewness exists. The direction of skewness of an operations' distribution is a necessary input to ASF–STC. Thus, a novel approach to determining the skewness of a distribution for small sample sizes is presented here. ASF–STC has an additional requirement of distribution information for each operation. The beta distribution is an ideal candidate here, as it is very flexible in shape. The literature on four‐parameter beta estimation is very limited, and their performance for small sample sizes is poor. STC was designed for low‐volume production, thus the estimation for small sample sizes is necessary here. This study presents a heuristic, based on the method of moments estimates for a beta distribution, that estimates the four parameters for a beta distribution with small sample size. Several computational results are provided to compare this heuristic to the best‐known procedure, with the heuristic found to perform better for the test problems considered. Copyright © 2002 John Wiley & Sons, Ltd.     

Distributed energy efficiency in future home environments

In this paper, a new architecture for sharing resources among home environments is proposed. Our approach goes far beyond traditional systems for distributed virtualization, like PlanetLab or grid computing, as it relies on complete decentralization in a peer-to-peer (P2P) like manner and, above all, aims at energy efficiency. Energy metrics are defined, which have to be optimized by the system. The system itself uses virtualization to transparently move tasks from one home to another to optimally utilize the existing computing power. We present an overview of our proposed architecture, consisting of a middleware interconnecting computers and routers in possibly millions of homes using P2P techniques. For demonstrating the potential energy saving of distributed applications, we present an analytical model for sharing downloads, which is verified by discrete event simulation. The model represents an optimistic case without P2P overhead and fairness. The model allows to assess the upper limit of the saving potential. An enhanced version of the simulation model also shows the effect of fairness. The fairer the system gets, the less efficient it is.