Skin detection is very challenging because of the differences in illumination, cameras characteristics, the range of skin colours due to different ethnicities and many other variations. New effective and accurate methodologies are developed for skin colour detection to easily identify human’s skin colour threw databases which are specifically designed to assist research in the area of face recognition. One of these is the recently built SFA database that showed high accuracy for segmentation of face images. The approach described in this paper exploits skin and non-skin samples provided by SFA for skin segmentation on the basis of the well-known Euclidean and Manhattan distance metrics. Most importantly, the scheme proposed tries to segment facial colour images inside or outside SFA by means of skin samples belonging to SFA. Simulation results in both SFA and UTD colour face databases indicate that detection rates higher than 95% can be achieved with either measure.
Direct steam generation (DSG) in parabolic trough solar collectors is a feasible option for economic improvement in solar thermal power generation. Three-dimensional Eulerian two-fluid simulations are performed under OpenFOAM to study the turbulent flow in the evaporation section of the parabolic trough receiver and investigate the phase change, and pressure drop of water as a heat transfer fluid. First, the model's validity has been tested by comparing the numerical results of a laboratory scale boiler with the available correlations and semi-correlations of boiling flows from the literature. Simulations agreed well with Rouhani–Axelsson correlation for horizontal tubes, with a mean relative error of less than 7.1% for all studied cases. However, despite a mean relative error of less than 13.19% compared to the experimental data in the literature, the reported pressure drop factor remains valid; overprediction remains tolerable for most engineering applications. Second, the scaling effect on the mathematical model, from laboratory to commercial-scale configuration, was tested with experimental data of the DISS test loop in Platforma Solar de Almeria, Spain. The Monte Carlo Ray Tracing method under the Tonatiuh package allowed for obtaining the nonuniform heat flux distribution. Due to the large size of the evaporation section in the DISS loop (eight collectors), each collector is considered independently in the simulations. Thus, simulations follow each other, taking the numerical results of each collector output as input data in the next collector and so on until the last. The numerical results showed an excellent agreement for the void fraction with 3.53% against the Rouhani–Axelsson correlation. Frictional pressure losses are within a 17.06% error of the Friedel correlation, in the range of previous work in the literature, and the heat loss is less than 4.69% error versus experimental correlation.
In this chapter, we have conducted a statistical study of the annual extreme precipitation (AMP) for 856 grid cells and during the period of 1979–2012 in Algeria. In the first step, we compared graphically the forecasts of the three parameters of the generalized extreme value (GEV) distribution (location, scale and shape) which are estimated by the Spherical model. We used the Cross validation method to compare the two methods kriging and Co-kriging, based on the based on some statistical indicators such as Mean Errors (ME), Root Mean Square Errors (RMSE) and Squared Deviation Ratio (MSDR). The Kriging forecast error map shows low errors expected near the stations, while co-Kriging gives the lowest errors on average at the national level, which means that the method of co-Kriging is the best. From the results of the return periods, we calculate that after 50 years the estimated of the annual extreme precipitation will exceed the maximum AMP is observed in the 33-year.
In this chapter, we have conducted a statistical study of the annual extreme precipitation (AMP) for 856 grid cells and during the period of 1979–2012 in Algeria. In the first step, we compared graphically the forecasts of the three parameters of the generalized extreme value (GEV) distribution (location, scale and shape) which are estimated by the Spherical model. We used the Cross validation method to compare the two methods kriging and Co-kriging, based on the based on some statistical indicators such as Mean Errors (ME), Root Mean Square Errors (RMSE) and Squared Deviation Ratio (MSDR). The Kriging forecast error map shows low errors expected near the stations, while co-Kriging gives the lowest errors on average at the national level, which means that the method of co-Kriging is the best. From the results of the return periods, we calculate that after 50 years the estimated of the annual extreme precipitation will exceed the maximum AMP is observed in the 33-year.
In this study, a statistical analysis method such as cluster analysis was used to group the effective ther- mal conductivity models of nanofluids. Ten models were selected for each nanofluid Al2O3, SiO2, TiO2, Cu, Ag, and Al, and then four models were proposed to estimate the thermal conductivity of nanoflu- ids. For the proposed models, the volume fraction is regarded as the best predictor. The nine statistical indicators and global performance indicators are calculated to evaluate different suggested models. For all used nanofluids, the recommended Global Performance Index (GPI) for the model ranges from –6.4197 to 2.5742. The highest GPI represents the best performing model.
External confinement by the GFRP composites offers an actual process for retrofitting glass fibre reinforced concrete columns (GFRC) subject to static or seismic loads. This paper presents an experimental investigation and analytical modelling of the axial compression of confined circular concrete columns of different strengths (8.5, 16, and 25 MPa). Furthermore, the columns contain different percentages of glass fibres (0.3 to 1.2 %), and their confinement is given by GFRP composites of various thicknesses (0.8 to 2.4 mm). The uniaxial compression test on these specimens reveals that the glass fibre percentage and the thickness of the GFRP play a vital role in improving the load-deformation behaviour and crack propagation. Whatever the concrete strength, the ultimate axial strain and stress predicted using the suggested confinement model almost agrees with the available experimental results.
