Structural sizing of post-buckled thermally stressed stiffened panels

Design of thermoelastic structures can be highly counterintuitive due to design-dependent loading and impact of geometric nonlinearity on the structural response. Thermal loading generates in-plane stresses in a restrained panel, but the presence of geometric nonlinearity creates an extension-bending coupling that results in considerable transverse displacement and variation in stiffness characteristics, and these affects are enhanced in post-bucking regimes. Herein a methodology for structural sizing of thermally stressed post-buckled stiffened panels is proposed and applied for optimization of the blade and hat stiffeners using a gradient-based optimizer. The stiffened panels are subjected to uniform thermal loading and optimized for minimum mass while satisfying stress and stability constraints. The stress constraints are used to avoid yielding of the structure, whereas the stability constraints are used to ensure static stability. Corrugation of the hat stiffeners is also studied through variation of its magnitude and position. A continuation solver has been validated to tackle the highly nonlinear nature of the thermoelastic problem, and formulations for the stability constraints have been derived and imposed to satisfy the static stability of the structure. The study confirms that geometric nonlinearity is an important aspect of sizing optimization and is needed for an accurate modeling of the structural behavior. The results also show that modeling of geometric nonlinearity adds extra complexity to the thermoelastic problem and requires a path-tracking solver. Finally, this work supports that corrugation enhances the stability features of the panel but requires a blending function to reduce stresses at the panel boundaries

Parallel implementation of pulse compression method on a multi-core digital signal processor

Pulse compression algorithm is widely used in radar applications. It requires a huge processing power in order to be executed in real time. Therefore, its processing must be distributed along multiple processing units. The present paper proposes a real time platform based on the multi-core digital signal processor (DSP) C6678 from Texas Instruments (TI). The objective of this paper is the optimization of the parallel implementation of pulse compression algorithm over the eight cores of the C6678 DSP. Two parallelization approaches were implemented. The first approach is based on the open multi processing (OpenMP) programming interface, which is a software interface that helps to execute different sections of a program on a multi core processor. The second approach is an optimized method that we have proposed in order to distribute the processing and to synchronize the eight cores of the C6678 DSP. The proposed method gives the best performance. Indeed, a parallel efficiency of 94% was obtained when the eight cores were activated

Probabilistic Self-Organizing Maps for Text-Independent Speaker Identification

The present paper introduces a novel speaker modeling technique for text-independent speaker identification using probabilistic self-organizing maps (PbSOMs). The basic motivation behind the introduced technique was to combine the self-organizing quality of the self-organizing maps and generative power of Gaussian mixture models. Experimental results show that the introduced modeling technique using probabilistic self-organizing maps significantly outperforms the traditional technique using the classical GMMs and the EM algorithm or its deterministic variant. More precisely, a relative accuracy improvement of roughly 39% has been gained, as well as, a much less sensitivity to the model-parameters initialization has been exhibited by using the introduced speaker modeling technique using probabilistic self-organizing maps

L’ approche par les risques : une alternative de l’approche d’audit classique

Suite à un constat fait lors de notre expérience dans l’un des cabinets de renommée, cette étude portera sur l’approche par les risques qui est peu utilisée dans les cabinets Marocains.  L’objet de cet article est de mettre en évidence l’importance de l’approche par les risques dans la recherche de l’efficacité et l’efficience dans les travaux d’audit. Afin de démontrer cela, nous allons, d’abord, montrer les limites de l’approche classique d’audit, ensuite nous allons illustrer l’importance de l’approche par les risques et enfin nous allons présenter la démarche de l’audit selon cette approch

Towards an Optimal Speaker Modeling in Speaker Verification Systems using Personalized Background Models

This paper presents a novel speaker modeling approachfor speaker recognition systems. The basic idea of this approach consists of deriving the target speaker model from a personalized background model, composed only of the UBM Gaussian components which are really present in the speech of the target speaker. The motivation behind the derivation of speakers’ models from personalized background models is to exploit the observeddifference insome acoustic-classes between speakers, in order to improve the performance of speaker recognition systems.The proposed approach was evaluatedfor speaker verification task using various amounts of training and testing speech data. The experimental results showed that the proposed approach is efficientin termsof both verification performance and computational cost during the testing phase of the system, compared to the traditional UBM based speaker recognition systems

A study of feature extraction for Arabic calligraphy characters recognition

Optical character recognition (OCR) is one of the widely used pattern recognition systems. However, the research on ancient Arabic writing recognition has suffered from a lack of interest for decades, despite the availability of thousands of historical documents. One of the reasons for this lack of interest is the absence of a standard dataset, which is fundamental for building and evaluating an OCR system. In 2022, we published a database of ancient Arabic words as the only public dataset of characters written in Al-Mojawhar Moroccan calligraphy. Therefore, such a database needs to be studied and evaluated. In this paper, we explored the proposed database and investigated the recognition of Al-Mojawhar Arabic characters. We studied feature extraction by using the most popular descriptors used in Arabic OCR. The studied descriptors were associated with different machine learning classifiers to build recognition models and verify their performance. In order to compare the learned and handcrafted features on the proposed dataset, we proposed a deep convolutional neural network for character recognition. Regarding the complexity of the character shapes, the results obtained were very promising, especially by using the convolutional neural network model, which gave the highest accuracy score

SCREENING OF THE ANTIOXIDANT ACTIVITY OF CRUDE EXTRACTS IN 86 ALGAE SPECIES FROM EL JADIDA COAST (MOROCCO)

Objective: This work aimed to screen the antioxidant activity of marine macroalgae from the Moroccan Atlantic coast (region of El Jadida). Methods: Evaluation of the antioxidant activity of different collected species, lyophilized and extracted with a solvent mixture chloroform/methanol (2/1; v/v) was conducted according to two techniques, first by thin layer chromatography (tlc) then by spectrophotometry, using a free radical 2,2-diphenyl-1-picrylhydrazyl (dpph). The sampling on a distance of 110 km allowed to harvest 86 algal species (16 brown algae, 47 red algae, 14 green algae and 9 algae being identified). Results: The analysis by thin layer chromatography reveals an antioxidant activity in nearly half of harvested algal species (52.32 %). This activity varies depending on the concentration of the extract and in function of incubation time in the presence of dpph. The monitoring of the kinetics of degradation of dpph by spectrophotometer in the presence of extracts which were active by tlc allowed to confirm the results and select the most active algal species based on the percentage of remaining dpph in the medium after 120 min of reaction: Fucus spiralis (17.02 %), Cyctoseira ericoides (12.16 %) (Phaeophyceae), and Gracilaria multipartita (36%), Halopitys incurvus (5%) (Rhodophyceae). Conclusion: The results show that the methodology adopted in this work is reliable and can be used for rapid screening of antioxidant property in plants and the species: Fucus spiralis, Cyctoseira ericoides, Gracilaria multipartita, and Halopitys incurvus can be a promising source of natural compounds endowed with high antioxidant potential

SELECTION OF NEW PROMISING SEEDLESS MANDARINS TRIPLOID HYBRIDS FROM CROSSES BETWEEN MONOEMBRYONIC DIPLOID FEMALE AND DIPLOID MALE PARENTS

Morocco is one of the major exporters of small citrus fruits, such as mandarin and Clementine. Seedlessness is a major criterion for this horticultural group. The present study focused on the selection of the best triploid mandarin hybrids (2n=3x=27) characterized by seedless fruits. A series of crosses between ‘Sidi Aissa’ clementine (female parent) and seven mandarin varieties (‘Lee’, ‘Wilking’, ‘Osceola’, ‘Carvalhal’, ‘Satsuma Frost’, ‘Satsuma Owari’ and ‘Chienka’) was performed by the National Institute for Agricultural Research. Forty triploid mandarins were obtained and planted since 2002 in an experimental field at El Menzeh. Varietal evaluation was focusing on fruit quality traits during seven years. Statistical analyzes showed that there is a significant difference for all studied characters and between hybrids. The number of seeds per fruit is the main criterion which differentiates between triploids mandarin’s hybrids and their diploid parent “clementine Sidi Aissa”. The best hybrids selected were: HT11, HT13, HT27, HT43, HT44, and HT49. The best crosses are C1 (‘Sidi Aissa’ × ‘Wilking’) andC2 (‘Sidi Aissa’ בOsceola’). These promising triploid hybrids of mandarin have been multiplied on several rootstock trials and are in the process of quantitative evaluation and multi-site testing

Antimicrobial susceptibility of urinary Klebsiella pneumoniae and the emergence of carbapenem-resistant strains: A retrospective study from a university hospital in Morocco, North Africa

Introduction: Urinary tract infections (UTIs) due to multi-drug resistant Klebsiella pneumoniae (K. pneumoniae) strains are increasing worldwide and have become a major public health problem.Objectives: The aim of this study was to determine the current and local antimicrobial susceptibility of urinary K. pneumoniae isolated from inpatients and outpatients in a university hospital.Subjects and methods: A retrospective study was carried out, covering a 3-year period from January 2010 to December 2012. It focused on all the K. pneumoniae strains isolated from the urine samples analyzed at the microbiology laboratory of the Avicenne Teaching Hospital, Marrakech, Morocco, North Africa.Results: K. pneumoniae represented 22% of all the urinary Enterobacteriaceae isolated during the study period. The bacterial resistance rates of K. pneumoniae isolates not producing extended spectrum - lactamase (ESBL) were as follows: trimethoprim sulfamethoxazole “T/S” (61%), amoxicillin/clavulanic acid (51%), ciprofloxacin (32%), gentamicin (21%) and amikacin (11%). ESBL producing K. pneumoniae strains accounted for 25.5% of all the urinary K. pneumoniae isolates and showed resistance to T/S (89%), gentamicin (89%), ciprofloxacin (84%) and amikacin (50%). For the first time in our region, we also noted the emergence of carbapenem-resistant strains that accounted for 7% of all the urinary ESBL-producing K. pneumoniae isolates.Keywords: Urinary; Klebsiella pneumoniae; Antimicrobial resistanc