Numerical study of a three-dimensional forced laminar flow in a channel equipped with a perforated baffle

The present work concerns a numerical study of a three-dimensional laminar flow in forced convection crossing a rectangular channel provided with a baffle attached on its lower wall. The conservation equations for mass, momentum, and energy are solved by the finite volume method based on the SIMPLE algorithm for pressure–velocity coupling scheme. The effect of the insertion of a perforated baffle at different perforation volumes was analyzed. The results presented show the temperature and velocity contours obtained for two different planes (XY and XZ) passing through the center of the baffle. The average friction coefficient, the average Nusselt number and the heat flux are presented for different perforation volumes of the baffle and for different Reynolds numbers. The study shows that although the solid baffle improves heat transfer, the use of a perforated baffle attached to the same position, further enhances heat transfer (from 0.03% to 14.52%), which provides, economically, a very good material reduction (from 5.18% to 82.96%) and mechanically, less flow resistance and therefore better performance.     

A Box-Behnken design for predicting the combined effects of relative humidity and temperature on antagonistic yeast population density at the surface of apples

The objective of this work was to develop models predicting the combined effects of relative humidity (RH, 75-98%), temperature (5-25 degrees C), and initial applied yeast concentration (10(4)-10(8) CFU/ml) on the apple-surface population densities of two biocontrol agents fused against postharvest diseases; the antagonistic yeasts Pichia anomala strain K and Candida oleophila strain O. Experiments were carried out according to a Box-Behnken matrix. Multiple regression analyses showed that both models yielded a good prediction of yeast density. The effect of relative humidity appeared greater than that of temperature. The number of yeast colony-forming units per square centimeter of apple fruit surface increased with increasing relative humidity, temperature, and initial applied yeast concentration. The models predict that under optimal growth conditions (25 degrees C, 98%), strains O and K should reach a density of 10(4) CFU/cm2 when applied initially at 2 x 10(7) (strain O) or 10(7) CFU/ml (strain K). The model results suggest that rainfall was likely the principal cause of the variability of yeast efficacy reported for previous preharvest orchard trials spanning two successive years. Temperature may also contribute to this variation. The models developed here are important tools for predicting population densities of both strains on the apple surface within the experimental limits. The use of these results should contribute to achieving yeast densities of 10(4) CFU/cm2 on apples by controlling yeast application and environmental factors such as relative humidity and temperature. The results of this study also confirm our previous in vitro findings that water activity has a greater effect than temperature on yeast population density.     

Development of an experimental platform for research in energy and electrical machine control

This paper presents the development of a test bench dedicated for electrical machines and energy control, as realized by the research team of the Power Systems and Electrical Machines Laboratory (RME) of the National Institute of Applied Sciences and Technology (INSAT) in Tunisia. The principal components of the proposed test bench are explained, and the respective characteristics are given. This paper focuses on mounting low-cost sensors and developing reliable scientific results. The relevant obtained results in photovoltaic (PV) and wind energy fields, power measurement and control, as well as alternating current (AC) machine drives are likewise presented. These are supported by two signal processing controller boards based on Technosoft MCK240 and dSPACE DS1104 kits. In the wind energy field, some results relative to Self Excited Induction Generator dedicated to supplying isolated sites are discussed; in addition, water pumping is discussed for PV energy. In the AC drives area, the results of a closed loop control are presented using a developed direct voltage control (DVC) scheme implemented on dSPACE DS1104. Maps and interesting details of some realized sensors are also presented.     

Gabor filter-based texture for ancient degraded document image binarization

Pattern Analysis and Applications - Binarization of ancient degraded document images is a very important step for their preservation and digital use. In this paper, a new simple threshold-based...     

Efficient fall activity recognition by combining shape and motion features

Computational Visual Media - This paper presents a vision-based system for recognizing when elderly adults fall. A fall is characterized by shape deformation and high motion. We represent shape...     

Salmonella contamination of laying-hen flocks in two regions of Algeria

A preliminary epidemiological study of Salmonella contamination in laying-hen flocks was carried out in the regions of Annaba and Eltarf, Algeria, from March to October 2008 and March to November 2009. Our objectives were (i) to estimate the prevalence of infection by Salmonella spp. in seven pooled samples during the hens' laying period (ii) to identify the serotypes and antimicrobial resistance phenotypes of isolates, and (iii) to characterize the factors that may be related to Salmonella contamination in Algerian henhouses. For this purpose, 18 out of 22 operational laying-hen houses were sampled one to three times during these periods: once at the start of laying (pullets aged 22–31 weeks), once in the middle of laying (47–60 week) and once at the end of laying prior to depopulation (70–86 week). The flocks'Salmonella status was assessed by collecting 2754 environmental samples that were analyzed according to the ISO 6579 method. The antibiotic resistance of Salmonella strains was tested as per the guidelines of the Clinical and Laboratory Standards Institute (CLSI). The relationship between each potential risk factor and the Salmonella status of laying-hen flocks was evaluated by calculating the relative risk with 95% confidence intervals. Eight flocks tested positive for Salmonella spp., with a higher prevalence at the end of laying than at either the beginning or middle. Only 19 isolates were recovered from the 2754 samples analyzed and nine different serotypes identified. S. enteritidis (n = 4) was the most prevalent serovar, along with S. Kentucky and S. Hadar (n = 3), followed by S. Heidelberg, S. Manhattan and S. Virchow (n = 2), whereas S. Dublin, S. Typhimurium and S. Albany were found only once. Thirteen isolates were resistant to at least one antimicrobial agent. Of these, six were resistant to at least three different antimicrobial classes. Salmonella serovar Kentucky isolates were resistant to fluoroquinolones with ciprofloxacin MIC ≥ 8 mg/L. Six risk indicators were identified as potentially related to the Salmonella status of layer houses.