185 research outputs found

    Solar cell degradation under open circuit condition in out-doors-in desert region

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    AbstractThe reliability of solar cells is an important parameter in the design of photovoltaic systems and particularly for cost estimation. Solar cell degradation is the result of various operating conditions; temperature is one of most important factors. Installed PV modules in desert regions are subjected to various temperature changes with significant gradient leading to accelerated degradation. In the present work, we demonstrate the influence of open-circuit condition on the degradation of PV modules. The experiment is carried out in the desert region of ADRAR (southern Algeria) using two modules IJISEL of single-crystal silicon. A continuous monitoring allows analysis of both performances of modules for duration of 330days. The module in open-circuit condition reaches higher temperature means than the module in charging condition; therefore, it undergoes a higher degradation. By simulation, we found that the life of a PV module (whose power output is close to 50%) in a condition of an open-circuit in the desert region could be reduced to 4years, and that has a significant impact on economy

    Using LDGM Codes and Sparse Syndromes to Achieve Digital Signatures

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    In this paper, we address the problem of achieving efficient code-based digital signatures with small public keys. The solution we propose exploits sparse syndromes and randomly designed low-density generator matrix codes. Based on our evaluations, the proposed scheme is able to outperform existing solutions, permitting to achieve considerable security levels with very small public keys.Comment: 16 pages. The final publication is available at springerlink.co

    Effect of Partial Root Zone Drying on Growth, Yield and Biomass Partitioning of a Soilless Tomato Crop

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    The object of the present research was to assess the effects of partial root zone drying (PRD) as a water supply strategy on tomato growth, productivity, biomass allocation and water use efficiency (WUE). Plants were grown under greenhouse, on a sand substrate. Three treatments were applied: a control that was fully and conventionally irrigated, PRD-70 and PRD-50 in which, respectively, 70% and 50% of water requirements were supplied using PRD. At planting, the root volume was devided into two halves each half was irrigated separately. Alternation of irrigation between the two root halves took place each three days. The total yield statistically differed (P < 0.05) with control giving the highest total yield (252 tons/ha). Compared to PRD-70 and control, PRD-50 yield decrease rates were, respectively, 16% and 30%. In terms of fruit number, PRD-50 showed 23% and 16% less fruits than PRD-70 and control, respectively. Fruit size was affected by treatment with PRD-50 treatment producing 66% and 53% more class 3 fruits (small size) than, control and PRD-70 (P< 0.05), respectively. For plant growth, the difference was not significant when comparing control to PRD-70 but was significant when comparing PRD-70 and control to PRD-50 (P < 0.05). No effect was on total biomass but root biomass was higher for stressed plants compared to control (P<0.05). WUE was 66% and 27% higher for PRD-50 and PRD-70 respectively compared to control

    Thrombose du sinus lateral et de la veine jugulaire apres un traumatisme cranien ferme

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    Introduction Les traumatismes crâniens fermés représentent une étiologie exceptionnelle des thromboses veineuses cérébrales (TVC). Seule une trentaine de cas sont rapportés, contrastant avec la grande fréquence des traumatismes crâniens. Cette situation pose des difficultés diagnostiques pouvant expliquer le pronostic relativement mauvais des TVC post traumatiques.Objectif Rapporter un cas de thrombose veineuse après un traumatisme crânien fermé.Observation Un patient de 23 ans suivi pour une schizophrénie, a présenté suite à une tentative de suicide, un traumatisme crânien fermé sans anomalie clinique ou à la TDM cérébrale initiale. Après un intervalle de 48 heures, un syndrome d’hypertension intracrânienne est apparu de façon rapide. Une thrombose du sinus latéral droit, étendue à la veine jugulaire a été découverte fortuitement sur la TDM cérébrale et confirmée par l’angio-IRM. Le reste du bilan étiologique de cette TVC est resté négatif et les anticoagulants ont permis une amélioration rapide des symptômes.Conclusion Dans les suites d’un traumatisme crânien, l’apparition de symptômes neurologiques, en particulier d’une HTIC doit faire rechercher une TVC après avoir éliminé des causes plus classiques à ce contexte (hématomes intracrâniens).Mots clés : Thrombose veineuse cérébrale; traumatisme crânien; anticoagulants

    Study of Cu/In/Se/Se thin films prepared by the Stacked Elemental Layer (SEL) technique

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    CuInSe2 thin films have been grown on Corning glass and Si (100) substrates using stacked elemental layers (SEL) processing. The influence of substrate’s nature and substrate’s temperature were studied. X-ray diffraction and SEM measurements have shown that the films exhibit an excellent crystallinity and crystallize in a tetragonal structure. Scanning electron microscopy investigations have shown that the films consist in a structure with large grains in the range 80 – 200 nm. Increasing the deposition temperature from room temperature to 300 °C has lead to a change in the composition and morphology of the films. Characteristic peaks of the chalcopyrite structure such as (101), (211) and (311) were clearly observed for both layers upon annealing at 450°C as evidenced by X-ray diffraction study. The determined lattice parameters were a = 0.57725 (6) nm, b = 1.1621 (2) nm for sample prepared at room temperature and a = 0.57770 (4) nm, b = 1.1602 (1) nm for Ts = 300°C. The crystallographic structure of the CuInSe2 sample was analyzed by Rietveld analysis using X-ray powder diffraction data. UV-Vis-NIR Spectrophotometry was used to investigate the optical characteristics of different Cu/In/Se/Se thin layers in the spectral range between 300 – 2000 nm. The optical band-gap of our materials increases from 0.98 to 1.01 eV

    Variations of the McEliece Cryptosystem

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    Two variations of the McEliece cryptosystem are presented. The first one is based on a relaxation of the column permutation in the classical McEliece scrambling process. This is done in such a way that the Hamming weight of the error, added in the encryption process, can be controlled so that efficient decryption remains possible. The second variation is based on the use of spatially coupled moderate-density parity-check codes as secret codes. These codes are known for their excellent error-correction performance and allow for a relatively low key size in the cryptosystem. For both variants the security with respect to known attacks is discussed
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