Improving the Basin Type Solar Still Performances Using an Internal Solar Collector

his paper presents a new experimental approach proposed to improve the conventional basin type solar still performances by integrating an internal solar collector. A serpentine heat exchanger is integrated inside the still acting as a solar collector to form an active solar still. The still productivity enhancement is verified experimentally through a comparative study with and without the internal solar collector during typical summer days. The effect of water depth is evaluated by varying the water amount in the basin still. The experimental tests show that the integrated internal solar collector acts as an effective heat source allowing more solar energy absorption which contributes to improving the still productivity. It was found that the still daily output is increased by about 20% and its thermal efficiency is improved by 16.8%

An Experimental Study of the Drying of Papayes by Solar Panels

One of the major problems concerning the use of solar panels for heating is the low level of thermal interchange with air in the dynamic vein of the solar panel. This weakness in such systems does not enable an optimum performance or high level of thermal efficiency to be obtained from their use. There is, however, a very noticeable improvement to thermal transfer when baffles are placed in rows in the ducts. To conduct the experiments, solar energy was simulated, the aim being to improve the ratio between temperature and thermal efficiency of an air heating plane solar panel and to make use of the system to reduce the drying time of papayes

Pensare l’educazione in un tempo di crisi. Itinerari pedagogici antropo-sostenibili

“Nessuno si salva da solo” recita il titolo di un celebre romanzo (Mazzantini, 2011) assunto come monito di una generazione che vive l’avventura del presente in maniera alienata, sfiduciata, non nutrendo alcuna aspettativa per il futuro. Lo spazio/tempo che abitiamo è quello del disincanto, della crisi dell’umano e del bisogno di una educazione/formazione illuminata, guidata da una intenzionalità pedagogica aperta e matura, che guardi alla sostenibilità come principio di generatività e perfettibilità dell’uomo oltre che di cura e salvaguardia dell’ambiente. Questo principio, affinché possa contribuire a ristabilire un nuovo ordine sociale, dovrà rinsaldare quei legami che oggi risultano sfilacciati dell’io con se stesso, con l’altro, con la società, con la natura ma, soprattutto, con l’orizzonte opaco del futuro. La crisi del nostro tempo che emerge in filigrana nei diversi contributi dei due autori, frutto di riflessioni maturate nel tempo, rappresenta nel volume lo sfondo e insieme la premessa per pensare l’educazione oggi e per delineare alcuni itinerari antroposostenibili, capaci di attraversare le sfide attuali del sapere, della diversità, della tecnoscienza, della famiglia, del lavoro, della fratellanza tra i popoli e di una cittadinanza europea e globale

Modeling and simulation of fuzzy logic controller for optimization of the greenhouse microclimate management

Abstract. Agricultural greenhouse is largely answered in the agricultural sphere, despite the shortcomings it has, including overheating during the day and night cooling which sometimes results in the thermal inversion mainly due to its low inertia. The glasshouse dressed chapel is relatively more efficient than the conventional tunnel greenhouse. Its proliferation on the ground is more or less timid because of its relatively high cost. Agricultural greenhouse aims to create a favorable microclimate to the requirements of growth and development of culture, from the surrounding weather conditions, produce according to the cropping calendars fruits, vegetables and flower species out of season and widely available along the year. It is defined by its structural and functional architecture, the quality thermal, mechanical and optical of its wall, with its sealing level and the technical and technological accompanying. The greenhouse is a very confined environment, where multiple components are exchanged between key stakeholders and the factors are light, temperature and relative humidity. This state of thermal evolution is the level sealing of the cover of its physical characteristics to be transparent to solar, absorbent and reflective of infrared radiation emitted by the enclosure where the solar radiation trapping effect otherwise called "greenhouse effect" and its technical and technological means of air that accompany. The socio-economic analysis of populations in the world leaves appear especially the last two decades of rapid and profound transformations These changes are accompanied by changes in eating habits, mainly characterized by rising consumption spread along the year. To effectively meet this demand, greenhousesystems have evolved, particularly towards greater control of production conditions (climate, irrigation, ventilation techniques, CO supply, etc.). Technological 2 progress has allowed the development of greenhouses so that they become increasingly sophisticated and of an industrial nature (heating, air conditioning, control, computer, regulation, etc.) New climate driving techniques have emerged, including the use of control devices from the classic to the use of artificial intelligence such as neural networks and / or fuzzy logic, etc. As a result, the greenhouse growers prefer these new technologies while optimizing the investment in the field to effectively meet the supply and demand of these fresh products cheaply and widely available throughout the year, The application of artificial intelligence in the industry known for considerable growth, which is not the case in the field of agricultural greenhouses, where enforcement remains timid. It is from this fact, we undertake research work in this area and conduct a simulation based on meteorological data through MATLAB Simulink to finally analyze the thermal behavior - greenhouse microclimate energy

Etude experimentale des performances thermiques de diverses configurations de chicanes placees dans la veine d'ecoulement

No Abstract. Technologies Avancess Vol. 16 2003: pp. 37-5

Etude experimentale des capteurs solaires a air: le sechage de la figue

No Abstract. Technologies Avancees Vol. 17 2005: pp. 15-2

The Apparent Thermal Conductivity of Pozzolana Concrete

AbstractThe recent development of some lightweight construction materials, such as light concrete, can play an important role as an insulator, while maintaining sufficient levels of mechanical performance. The quality of insulation to provide depends on the climate, the exposure of the walls and also the materials used in the construction. The choice of a material to be used as an insulator, obviously, depends on its availability and its cost.This is a study of natural pozzolanas as basic components in building materials. It is intended to highlight their thermal advantage. It is economically advantageous to use pozzolana in substitution for a portion of the clinker as hydraulically active additions, as well as in compositions of lightweight concretes in the form of pozzolanic aggregate mixtures, which provide mechanical strengths that comply with current standards.A theoretical study is conducted on the apparent thermal conductivity of building materials, namely concrete containing pozzolana. Thermal modeling, apparent to that commonly used for porous materials, has been applied to pozzolana concrete.Experimental results on measurements of the apparent thermal conductivity of pozzolana concrete are reported in this study, using an approach that considers that concrete is composed of two solid ingredients, a binding matrix (hydrated cement paste) and all aggregates. A second comparative theoretical approach is used for the case where concrete consists of a solid phase and a fluid phase (air)

Vitamin D status and determinants of deficiency in non-supplemented athletes during the winter months in Tunisia

Recent reports suggest that hypovitaminosis D in athletes is as common as in the general population. This study was devised to examine vitamin D status and determinants of deficiency in athletes living in a sunny country (Tunisia). One hundred and fifty national elite athletes, training outdoors (n=83) or indoors (n=67), were enrolled from January to February 2012. Plasma 25-hydroxyvitamin D was measured by radioimmunoassay. Concentrations were between 50 and 75 nmol · l -1 in 21.3% of participants, between 25 and 50 nmol · l -1 in 55.3% of participants and <25 nmol · l -1 in 14.7% of participants. The concentrations were significantly lower in indoor athletes than outdoor athletes (36.2±19.0 nmol · l -1 vs. 49.1±19.2 nmol · l -1 ; p<0.001). In multivariate analysis, vitamin D deficiency (25-hydroxyvitamin D <50 nmol · l -1 ) was associated with indoor sports [multi-adjusted odds ratio (95% confidence interval), 5.03 (1.64-15.4); p=0.005], female gender [3.72 (1.44-9.65); p=0.007] and age < 18 years [2.40 (1.01-5.85); p=0.05]. Athletes living in sun-rich environments are exposed to a high risk of vitamin D inadequacy. Given the importance of vitamin D in health and athletic ability, targeting sufficient levels of plasma 25-hydroxyvitamin D in athletes is well justified

Guillain barre syndrome as initial presentation of systemic lupus erythematosus

Background: Systemic Lupus Erythematosus (SLE) is an autoimmune disease characterized by multiple organ involvement including the peripheral nervous system. Guillan- Barrè syndrome (GBS) has an established association with SLE as one of its neurologic manifestations. However, GBS as an initial manifestation of SLE is only sparingly reported in the literature.Methods: We present a case of a 26 year old woman who was initially managed by neurology unit for GBS but subsequently developed body swelling, hypertension and polyarthritis. She was evaluated and managed by both rheumatology and nephrology units.Results: Renal biopsy showed histological features of membranous nephropathy suggestive of stage V lupus nephritis. The patient responded well to high dose corticosteroid, intravenous cyclophosphamide and azathioprine.Conclusion: This case highlights that GBS can be an initial presentation of SLE and the usefulness of immunosuppressants in the management of such cases.Keywords: Guillan-Barrè syndrome, Systemic Lupus Erythematosus, Lupus Nephritis, Immunosuppressant