Bond graph modeling,design and experimental validation of a photovoltaic/fuel cell/ electrolyzer/battery hybrid power system

This work presents a complete bond graph modeling of a hybrid photovoltaic-fuel cell-electrolyzer-battery system. These are multi-physics models that will take into account the influence of temperature on the electrochemical parameters. A bond graph modeling of the electrical dynamics of each source will be introduced. The bond graph models were developed to highlight the multi-physics aspect describing the interaction between hydraulic, thermal, electrochemical, thermodynamic, and electrical fields. This will involve using the most generic modeling approach possible for managing the energy flows of the system while taking into account the viability of the system. Another point treated in this work is to propose. In this work, a new strategy for the power flow management of the studied system has been proposed. This strategy aims to improve the overall efficiency of the studied system by optimizing the decisions made when starting and stopping the fuel cell and the electrolyzer. It was verified that the simulation results of the proposed system, when compared to simulation results presented in the literature, that the hydrogen demand is increased by an average of 8%. The developed management algorithm allows reducing the fuel cell degradation by 87% and the electrolyzer degradation by 65%. As for the operating time of the electrolyzer, an increment of 65% was achieved, thus improving the quality of the produced hydrogen. The Fuel Cell's running time has been decreased by 59%. With the ambition to validate the models proposed and the associated commands, the development of this study gave rise to the creation of an experimental platform. Using this high-performance experimental platform, experimental tests were carried out and the results obtained are compared with those obtained by simulation under the same metrological conditions.     

Batch cultures of Penicillium camembertii on glucose and amino acids—model for growth and ammonium production

BACKGROUND: Three groups of amino acids were previously characterized based on their ability to be assimilated as carbon source by Penicillium camembertii. To describe the diauxic growth recorded on glucose and amino acids from the second group, such as arginine, an unstructured model was previously developed, based on the sequential consumption of both carbon substrates, glucose, followed after its exhaustion, by arginine. The model was modified to describe also the behaviour recorded during growth on other amino acids. RESULTS: The growth model involved the carbon substrate consumption (Verlhust model) and the biomass on carbon substrate yield. Glucose was therefore considered during P. camembertii growth on nitrogen source amino acids (lysine—first group); and amino acid consumption was considered during growth on carbon source amino acids (glutamate—third group), with glucose being dissimilated only for energy supply. The excess nitrogen from amino acids was released as ammonium; the linking of this production to growth was found to increase with the ability of the amino acid to be assimilated as carbon source by P. camembertii. CONCLUSION: The various metabolic behaviours recorded during P. camembertii growth on amino acids, in the presence of a primary carbon source such as glucose, were proved to be satisfactorily described by the model, showing the robustness of the model. Copyright © 2007 Society of Chemical Industry     

Spatiotemporal evolution of the El Biar landslide (Algiers): new field observation data constrained by ground-penetrating radar investigations

Bulletin of Engineering Geology and the Environment - A better understanding of the spatiotemporal evolution of landslides in urban zones is a key factor in assessing the risk of future slides...     

Effect of Power Amplifier Nonlinearity on the Physical Layer Security of MIMO Systems

Wireless Personal Communications - This paper presents an analytical investigation on the effect of nonlinear high-power amplifiers on the physical layer security of multiple-input-multiple-output...     

Performance evaluation and tuning of an IEEE 802.11 audio video multicast collision prevention mechanism

Wireless Networks - Since the introduction of the original IEEE 802.11 medium access mechanism, the definition of the multicast access mechanism has been the subject of numerous amendments and...     

Achievement in hydrogen storage on adsorbents with high surface-to-bulk ratio – Prospects for Si-containing matrices

In hydrogen storage, the concept of the reversible capture still remains a major issue to be addressed. The advances in chemical storage provide useful data that demonstrate that purely physical adsorption offer promising prospects, even though the hydrogen uptakes barely attain 11 wt%. The emerging nanotubes, fullerenes, metal-organic frameworks are sophisticated structures that display weak affinity toward hydrogen, and require complex synthesis procedures. Adsorption rather consists of a gas condensation at low temperatures and/or high pressures. That is why the present review is devoted to the most recent achievements in developing novel microporous materials with emphasis on silicon-based structures, aluminosilicates and related materials. Their large availability and low production costs open promising prospects. On aluminosilicates, low Si:Al ratio, high porosity and specific surface area, along with alkali or alkaline-earth exchangeable cations are essential requirements for effective hydrogen adsorption even at room temperature.     

Optimization of medium composition for enhanced chitin extraction from Parapenaeus longirostris by Lactobacillus helveticus using response surface methodology

Chitin extraction by biological way, using the lactobacilli Lactobacillus helveticus, is a non-polluting method and offers the opportunity to preserve the exceptional qualities of chitin and its derivatives. However, the major disadvantage of the fermentative way is the low efficiency of demineralization and deproteinization. The aim of our study is to improve the yield of extraction.     

Quartz Ore Beneficiation by Reverse Flotation for Silicon Production

Silicon - In this work the reverse flotation as beneficiation process for high-purity silica valorization from Draissa quartz deposits (Algeria) is studied as a potential raw material for...     

The food preservative potential of essential oils: is lemongrass the answer?

Several essential oils of medicinal plants possess proven antimicrobial activity and are suitable for applications on the food industry. The oil from Cymbopogon citratus (lemongrass) has been reported to have a wide range of biological activities. However, there are few controlled studies confirming its antimicrobial activity. The aim of our study was to assess the antimicrobial potential of lemongrass oil against a wide spectrum of food spoilage and pathogenic bacteria and yeast in liquid and vapour phase. The chemical composition of the oil was analyzed by gas chromatography; 14 components were identified and geranial (28.93 %), neral (24.30 %) and myrcene (23.92 %) were the most abundant constituents. Lemongrass oil showed potent antimicrobial activity against Gram positive bacteria and exhibited the strongest antifungal effect against Candida albicans and C. parapsilosis. Minimum inhibitory concentration varied from 0.019 to 1.25 mg mL^?1 for Gram positive bacteria and yeasts, indicating Staphylococcus aureus, S. epidermidis and C. albicans as the most susceptible strains. Moreover, the diameter of inhibition zone (DIZ) increased with increasing essential oil (EO) volume. Considerably superior antimicrobial activity was observed in the vapour phase. The DIZ resulting from the exposure to EO vapour was significantly larger than that from the same volume in the liquid phase. The DIZ varied from 22 to 90 mm for Candida strains. There is growing evidence that EO in vapour phase are effective antimicrobial systems and that they do have advantages over the use of oil in liquid phase. Our results imply that lemongrass oil could be useful for the development of novel types of natural preservatives for food control.