Sectoriality and essential spectrum of non symmetric graph Laplacians

We consider a non self-adjoint Laplacian on a directed graph with non symmetric edge weights. We give necessary conditions for this Laplacian to be sectorial. We introduce a special self-adjoint operator and compare its essential spectrum with that of the non self-adjoint Laplacian considered

Dimensioning of an Autonomous Photovoltaic Installation: Case Study in Msaken, Sousse (Tunisia)

Renewable energy production has the potential to replace traditional fossil energy and reduce the consumption invoice. In this context, a client wants to realize an autonomous photovoltaic installation for his house that is under construction, located in the city of Msaken, Sousse (Tunisia), in an isolated area of the network of the Tunisian Company of Electricity and Gas (STEG) and will be inhabited by the end of the year 2019. The installation autonomy must be 72 hours in case of bad weather. Therefore, in this chapter, we will determine the technical characteristics of each component of the installation to meet the customer’s energy needs and ultimately provide the total price

Electronic gaming addiction and its correlation with psychological loneliness among orphaned adolescents

The aim of this study was to investigate the relationship between electronic gaming addiction and the level of psychological loneliness. To address and control this issue, a selection of secondary schools in the province of Bordj Bou Arreridj was chosen to implement field study procedures.The researchers employed a descriptive-analytical methodology in this study, relying on a questionnaire as a tool for investigation. The questionnaire included an electronic gaming addiction scale prepared by [Author Name] and the Russell Loneliness Scale. It was distributed to a sample of 80 orphaned adolescents. To verify the study hypotheses, appropriate statistical methods were utilized for analysis and interpretation, including means, Cronbach's alpha coefficient, Pearson correlation coefficient, among others. The study arrived at several conclusions: The level of electronic gaming addiction is high among orphaned adolescents. The level of psychological loneliness among orphaned adolescents is high. There is a statistically significant correlation between electronic gaming addiction and the level of psychological loneliness among orphaned adolescents

Semaine d'Etude Mathématiques et Entreprises 5 : Sélection de variables statistiquement représentatives pour la production électrique photovoltaïque

La production électrique des panneaux photovoltaïques dépend de nombreux paramètres météorologiques : rayonnement du soleil, présence ou absence de nuages, température, ... La problématique que nous a soumise l'entreprise RTE et à laquelle nous réfléchissons dans ce document est de sélectionner les variables les plus influentes sur cette production au moyen d'une étude statistique, et de proposer un modèle descriptif de cette production qui adhère le mieux possible à la réalité. Dans cet objectif, nous faisons dans un premier temps un tour d'horizon des modèles statistiques existants. Nous étudions ensuite un modèle additif pour analyser les données fournies par RTE et effectuer une première sélection de variables grâce au modèle GAM. Enfin, on reprend cette étude avec le modèle MARS dans l'objectif de pouvoir regrouper des variables entre elles pour pouvoir transformer notre modèle additif très restrictif en un modèle plus adapté à la situation considérée

Performance analysis of image transmission with various channel conditions/modulation techniques

This paper investigates the impact of different modulation techniques for digital communication systems that employ quadrature phase shift keying (QPSK) and quadrature amplitude modulation (16-QAM and 64-QAM) to transmit images over AWGN and Rayleigh fading channels for the cellular mobile networks. In the further steps, wiener and median filters has been adopted to the simulation are used at the receiver side to remove the impulsive noise present in the received image. This work is performed to evaluate the transmission of two dimensional (2D) gray-scale and color-scale (RGB) images with different values from signal to noise ratios (SNR), such as; (5, 10 and 15) dB over different channels. The correct conclusions are made by comparing many of the observed Matlab simulation results. This was carried out through the results that measure the quality of received image, which is analyzes in terms of SNRimage peak signal to noise ratio (PSNR) and mean square error (MSE)

Performance analysis of image transmission with various channel conditions/modulation techniques

This paper investigates the impact of different modulation techniques for digital communication systems that employ quadrature phase shift keying (QPSK) and quadrature amplitude modulation (16-QAM and 64-QAM) to transmit images over AWGN and Rayleigh fading channels for the cellular mobile networks. In the further steps, wiener and median filters has been adopted to the simulation are used at the receiver side to remove the impulsive noise present in the received image. This work is performed to evaluate the transmission of two dimensional (2D) gray-scale and color-scale (RGB) images with different values from signal to noise ratios (SNR), such as; (5, 10 and 15) dB over different channels. The correct conclusions are made by comparing many of the observed Matlab simulation results. This was carried out through the results that measure the quality of received image, which is analyzes in terms of SNRimage peak signal to noise ratio (PSNR) and mean square error (MSE)

Modification of Prepared (Al 2024/Alumina/Mn) Composite by Laser Surface SiC Clad Layer

The present work shows the cladding process of silicon carbide on the substrate of prepared composite (Al 2024/Alumina/Mn) by using a laser beam (pulsed Nd-YAG). To obtain the desired results, the best laser parameters were chosen. The parameters of the laser beam that have chief affected during the experiments in this work are peak power (1.9)kW, work frequency (8)Hz and pulse duration (5.3)ms, the preplaced powder technique favorite during a cladding process and the results in this work were proved by SEM, micro-hardness, EDS, and chemical corrosion tests. The results of the experimental work have shown that a micro-hardness increased about (28%) times for Aluminum/Alumina composite by silicon carbide cladding compared with the original value of micro-hardness, and thickness of the cladding layer was about (34μm). The resistance of corrosion was enhanced with about (35%) for the Aluminum/Alumina composite with SiC cladding

Hepcidin and its Related Hematological Biomarkers of Anemia in Children on Hemodialysis: Role of Carnitine Deficiency

BACKGROUND: Anemia is one of the most common complications in end-stage renal disease (ESRD) patients. Hepcidin is a hormone that regulates iron homeostasis in patients with ESRD. Carnitine deficiency is commonly seen in hemodialysis (HD) patients. AIM: This study aimed to investigate the relationship between hepcidin and inflammatory and other anemia markers in children with ESRD and to evaluate the association of carnitine deficiency with anemia in these patients. SUBJECTS AND METHODS: Thirty pediatric patients with ESRD undergoing HD, and thirty healthy, age- and sex-matched children served as controls were included in the study. Serum levels hepcidin, iron status, high-sensitivity C-reactive protein, and total carnitine were measured. RESULTS: Statistically significant increases in serum levels of hepcidin (100.7 ± 0.99 ng\ml vs. 77.43 ± 0.8 ng\ml, p = 0.000), was found in HD children as compared to healthy controls. Statistically significant increase in serum levels of hs-CRP (3.94 ± 0.19 mg/l vs. 1.36 ± 0.07 mg/l, p = 0.04) was found in HD children as compared to healthy controls. However, serum levels of carnitine (29.59 ± 2.46 μmol/L vs. 36 ± 2.39 μmol/L, p = 0.000) showed statistically significant decreases in HD children as compared to healthy controls positive correlation was found between hepcidin and hs-CRP (r = 0.059, p = 0.042). Furthermore, a positive correlation was present between serum carnitine levels and serum iron levels (r = 0.651, p = 0.042). CONCLUSION: Serum hepcidin may be a more useful biomarker of functional iron deficiency in children on HD. The efficacy of carnitine treatment for children on HD with carnitine deficiency and its effect on anemia needs to be studied

Caractérisation à l'usure du couple céramique-céramique utilisé dans les prothèses totales de hanche

L'arthroplastie totale de la hanche représente une solution efficace pour les maladies osseuses et ostéo-articulaires. Plusieurs biomatériaux sont actuellement utilisés comme les aciers inoxydables, les polymères, les céramiques... Un nouveau composite est récemment introduit en orthopédie afin de réunir les avantages de l'alumine (Al2O3) et de la zircone (ZrO2). Notre étude consiste à l'amélioration de la durée de vie des prothèses. Cette amélioration commence par la caractérisation des origines du dysfonctionnement, le phénomène d'usure, la résistance à la fatigue et principalement le « squeaking » dans le cas des prothèses en biocéramiques. Cette étude porte sur une expertise d'une PTH fabriquées avec un couple céramique-céramique en particulier la composite BIOLOX delta. Cette prothèse est étudiée dans les conditions in vivo et récupérée d'un patient très actif après six mois de pose. La caractérisation des surfaces de contact est effectuée à l'aide de la Microscopie Electronique à Balayage (MEB) et la microscopie numérique VHX. Ces observations ont permis d'identifier les zones d'endommagement et/ou l'usure sous forme des stries et arrachement des particules dans le cas de la tête et dépôt de matière sur la cupule des PTH.