Moisture sorption isotherms – Experimental and mathematical investigations of orange (Citrus sinensis) peel and leaves

The aims of this work were to determine chemical composition and sorption isotherms of Tunisian orange peel and leaves of the “Maltaise” variety. These by-products were found to be rich in fibre, soluble sugars, protein, minerals and phenols. The equilibrium moisture contents of “Maltaise” peel and leaves were measured using the static gravimetric method at three temperatures (40, 50 and 60 °C) and in wide range of water activity (0.109–0.891). Desorption and adsorption data of peel and leaves were best fitted by the Peleg model at 40, 50 and 60 °C. The net isosteric heats of desorption and adsorption were determined from sorption isotherms. For both peel and leaves, the net isosteric heat of desorption was higher than the net isosteric heat of adsorption and both decreased continuously with increasing of the equilibrium moisture content.     

Chemical composition,angiotensin I-converting enzyme (ACE) inhibitory,antioxidant and antimicrobial activities of the essential oil from Periploca laevigata root barks

The present study describes the chemical composition, and antimicrobial, antioxidant and angiotensin I-converting enzyme (ACE) inhibitory activities of essential oil from Periploca laevigata root barks (PLRB), an aromatic plant widely distributed in Tunisia and used as a traditional medicinal plant. Gas chromatography/mass spectrometry was used to determine the composition of the PLRB oil. Forty-three components were identified in the essential oil and the main compounds were benzaldehyde (56%), methyl 4-methoxysalicylate (6.55%) and carvacrol (4.75%). The PLRB essential oil exhibited a dose-dependent manner of inhibitory activity toward ACE. The highest ACE inhibitory activity (54%) was observed at a concentration of 30 μg/ml. The PLRB oil was also found to possess antioxidant activities, as evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical method, β-carotene bleaching and reducing power assays. The antimicrobial activity of the essential oil was also investigated on several microorganisms. The inhibition zones and minimal inhibitory concentration (MIC) values of bacterial strains were in the range of 12–46 mm and 50–300 μg/ml, respectively. The inhibitory activity of the PLRB essential oil against Gram-positive bacteria was significantly higher than against Gram-negative. It also exhibited remarkable activity against several fungal strains.     

Maximuma posteriori fast fading channel estimation for alamouti’s space-time transmit diversity

This paper considers the Alamouti’s two-branch transmit diversity scheme. This scheme supports a maximum likelihood detection based on linear processing at the receiver. When no knowledge of the channel is available — at the transmitter and the receiver- the above scheme requires in general the estimation of the two discrete propagation channels seen from the two transmit antennas. Our objective is to evaluate the Alamouti’s technique of diversity with a realistic estimation algorithm considering a very fast time-varying channel. For a robust channel estimation, we propose an EM-based maximuma posteriori semi-blind algorithm. This algorithm requires a convenient representation of the time-varying fading channel using a discrete version of the Karhunen-Loève expansion theorem. The iterative receiver optimally uses pilot as well as unknown data symbols for improving channel estimation quality. The validity of the proposed algorithm is highlighted by simulation results. Moreover, a complexity evaluation of this algorithm and a comparison is provided for different scenarii.     

Front face fluorescence spectroscopy: a rapid tool for determining the effect of replacing soybean meal with scotch bean in the ration on the quality of Sicilo-Sarde ewe’s milk during lactation period

The present study aimed to determine the effects of substitution of a high degradable protein source, namely, soybean meal, with scotch bean, a Tunisian local product, on ewe’s milk quality. Twelve 5-year-old lactating Sicilo-Sarde ewes (third lambing) were kept in environmentally controlled sheepfold and were divided into two homogenous weight matched groups (n = 6). Ewes were fed ad libitum with two iso-energetic diets (20% barley, 3% vitamin and mineral premix, and 77% soybean meal or scotch bean). Physico-chemical analyses and fluorescence spectra were performed on milk samples during lactation period. The replacement of soybean meal by scotch bean induced a significant decrease in fat content (7.85 vs. 6.75 g 100 g⁻¹) and a significant increase in lactose level (3.49 vs. 3.61 g 100 g⁻¹). The principal component analysis (PCA) applied separately to the fluorescence spectral data set showed some discrimination between milk samples according to the lactation period and diet compositions. Finally, common components and specific weights analysis (CCSWA) applied to the physico-chemical data and spectral data sets allowed an obvious discrimination of milks of ewes fed soybean meal from those fed scotch bean throughout the whole lactation period.     

A Central Limit Theorem for the SINR at the LMMSE Estimator Output for Large-Dimensional Signals

This paper is devoted to the performance study of the linear minimum mean squared error (LMMSE) estimator for multidimensional signals in the large-dimension regime. Such an estimator is frequently encountered in wireless communications and in array processing, and the signal-to-interference-plus-noise ratio (SINR) at its output is a popular performance index. The SINR can be modeled as a random quadratic form which can be studied with the help of large random matrix theory, if one assumes that the dimension of the received and transmitted signals go to infinity at the same pace. This paper considers the asymptotic behavior of the SINR for a wide class of multidimensional signal models that includes general multiple-antenna as well as spread-spectrum transmission models. The expression of the deterministic approximation of the SINR in the large-dimension regime is recalled and the SINR fluctuations around this deterministic approximation are studied. These fluctuations are shown to converge in distribution to the Gaussian law in the large-dimension regime, and their variance is shown to decrease as the inverse of the signal dimension.     

A pretreatment to improve the quality metrics performance for encoding H264/AVC

The study of the human visual system is very interesting to quantify the quality of an image or to predict perceived information. The contrast sensitivity function is one of the main ways to incorporate the human visual system properties in an imaging system. It characterizes its sensitivity to spatial frequencies. In this paper, we are interested in establishing a pretreatment for existing metrics with full reference (“peak signal‐to‐noise ratio”, “digital video quality”) for the H.264/MPEG‐4 (Motion Picture Expert Group) advanced video coding standard. We realize in our algorithm the FFT transformation to apply the contrast sensitivity function. Our method is applicable to any size of image and video sequence by increasing its size at powers of two. This increase is achieved by adding “mirror image.” We evaluate the performance of the proposed pretreatment by using subjective “LIVE” video databases. The performance metrics, that is, Pearson (PLCC), Spearman correlation coefficients (SROCC) and root mean square prediction error (RMSE) indicate that the proposed method gives a good performance in H264 codec distortions.     

An improved Backstepping technique using sliding mode control for transient stability enhancement and voltage regulation of SMIB power system

The problem of transient stability and voltage regulation for a single machine infinite bus (SMIB) system is addressed in this paper. An improved Backstepping design method for transient stability enhancement and voltage regulation of power systems is discussed beginning with the classical Backstepping to designing the nonlinear excitation control of synchronous generator. Then a more refined version of this technique will be suggested incorporating the sliding mode control to enhance voltage regulation and transient stability. The proposed method is based on a standard third-order model of a synchronous generator connected to the grid (SMIB system). It is basically implemented on the excitation side of the synchronous generator and compared to the classical Backstepping controller as well as the conventional controllers which are the automatic voltage regulator and the power system stabiliser. Simulation results prove the effectiveness of the proposed method which ameliorates to a great extent the transient stability compared to the other methods.     

A Deep-CNN Crowd Counting Model for Enforcing Social Distancing during COVID19 Pandemic: Application to Saudi Arabia’s Public Places

With the emergence of the COVID19 virus in late 2019 and the declaration that the virus is a worldwide pandemic, health organizations and governments have begun to implement severe health precautions to reduce the spread of the virus and preserve human lives. The enforcement of social distancing at work environments and public areas is one of these obligatory precautions. Crowd management is one of the effective measures for social distancing. By reducing the social contacts of individuals, the spread of the disease will be immensely reduced. In this paper, a model for crowd counting in public places of high and low densities is proposed. The model works under various scene conditions and with no prior knowledge. A Deep CNN model (DCNN) is built based on convolutional neural network (CNN) structure with small kernel size and two fronts. To increase the efficiency of the model, a convolutional neural network (CNN) as the front-end and a multi-column layer with Dilated Convolution as the back-end were chosen. Also, the proposed method accepts images of arbitrary sizes/scales as inputs from different cameras. To evaluate the proposed model, a dataset was created from images of Saudi people with traditional and non-traditional Saudi outfits. The model was also trained and tested on some existing datasets. Compared to current counting methods, the results show that the proposed model has significantly improved efficiency and reduced the error rate. We achieve the lowest MAE by 67%, 32% .and 15.63% and lowest MSE by around 47%, 15% and 8.1% than M-CNN, Cascaded-MTL, and CSRNet respectively.     

Structural and magnetic properties of Bi doped in the A site of (Pr1 − xBix)0.6Sr0.4MnO3 (0 ≤ x ≤ 0.4) perovskite manganites

We studied the effect of Bi doping in the A-site on the structural, magnetic, and magneto-caloric properties of the (Pr_1 − xBi_x)_0.6Sr_0.4MnO₃ (0 ≤ x ≤ 0.4) perovskite manganese oxides. In this study, the average ionic radius < r_A> of the A cation site was systematically varied while keeping fixed the carrier concentration (Mn^3 + /Mn⁴⁺ ratio). All our samples have been elaborated by the conventional solid state reaction at high temperature. X-ray powder diffraction at room temperature showed that all our synthesized samples are single phase and crystallize in the orthorhombic system with Pbnm space group. The unit cell volume decreases linearly with increasing Bi content. Magnetization measurements versus temperature in a magnetic applied field of 50 mT show that all our samples exhibit a paramagnetic to ferromagnetic transition when temperature decreases. The Curie temperature T_C decreases from 310 K for x = 0 to 252 K for x = 0.4.The critical exponent γ defined by and deduced from M(H) curves is found to be 0.315 for Pr_0.54Bi_0.06Sr_0.4MnO₃ sample. Furthermore, a large magnetocaloric effect near T_C has been detected with a maximum of magneto-entropy change, of 1.11 Jkg⁻¹ K⁻¹ and 4.78 Jkg⁻¹ K⁻¹at 1 T and 7 T, respectively, for Pr_0.54Bi_0.06Sr_0.4MnO₃ sample.