Search results for: Dorra Kallel

Authors: Dorra Kallel, Ines Kanoun, Diala Dhouib

Abstract:

This paper elaborates a Systematic Literature Review SLR) to select the most outstanding studies that address the Menu Planning Problem (MPP) and to classify them according to the to the three following criteria: the used methods, types of patients and the required constraints. At first, a set of 4165 studies was selected. After applying the SLR’s guidelines, this collection was filtered to 13 studies using specific inclusion and exclusion criteria as well as an accurate analysis of each study. Second, the selected papers were invested to answer the proposed research questions. Finally, data synthesis and new perspectives for future works are incorporated in the closing section.

Keywords: Menu Planning Problem (MPP), Systematic Literature Review (SLR), classification, exact and approaches methods

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Authors: Dorra Gherib

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This article explores in depth the technological innovations by the Top Managements of banks in the Tunisian banking sector. The framework of this research is based on an amalgamation of four theories related to the decision of adopting technological innovations: The Theory of Reasoned Action (TRA), the Theory of Planned Behaviour (TPB), Technology Acceptance Model (TAM), and Diffusion of Innovation (DI). The result of our qualitative study highlights four variables which influence the attitude of the Top Managements towards the adoption of internet banking: Relative advantage, Perceived Ease of Use, compatibility and Perceived risk.

Keywords: top management, attitude, internet banking, TRA, TAM, TPB, DI

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Authors: Soumaya Ben Kheilifa, Dorra Mezzez Hmaied

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We propose two approaches to examine whether European hedge fund managers can time market liquidity. Using a sample of 1616 European hedge funds, we find evidence of liquidity timing. More importantly, this ability adds economic value to investors. Thus, it represents valuable managerial skill and a major source of European hedge funds’ performance. Also we show that the majority of these funds demonstrate liquidity timing ability especially during liquidity crisis. Finally, it emerged that our main evidence of liquidity timing remains significant after controlling for market timing and volatility timing.

Keywords: european hedge funds, liquidity timing ability, market liquidity, crisis

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Authors: Fathi Kallel, Saida Khachira, Mohamed Ben Slima, Ahmed Ben Hamida

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Speckle noise is a main characteristic of cardiac ultrasound images, it corresponding to grainy appearance that degrades the image quality. For this reason, the ultrasound images are difficult to use automatically in clinical use, then treatments are required for this type of images. Then a filtering procedure of these images is necessary to eliminate the speckle noise and to improve the quality of ultrasound images which will be then segmented to extract the necessary forms that exist. In this paper, we present the importance of the pre-treatment step for segmentation. This work is applied to cardiac ultrasound images. In a first step, a comparative study of speckle filtering method will be presented and then we use a segmentation algorithm to locate and extract cardiac structures.

Keywords: medical image processing, ultrasound images, Speckle noise, image enhancement, speckle filtering, segmentation, snakes

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Authors: Soumaya Gahrsalah Falhi, Houda Kohli Kallel

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The first groups of hominids appeared ten million years ago in Africa and they congregated several species that had coexisted. Hence, the Homo genus appeared about two million years ago. By time, several species coexisted, succeded one after another, evolved then disappeared. Yet, the sole surviving species are those of the Homo Sapiens, the species to which we all belong.They brought along the pastoral and agricultural life. They were also the first to use weapons and metal tools as well. The flint which they have notably continued to use, is no longer only chipped but polished. They have also used fire to harden clay and make pottery. However, they were the first to introduce the metals of copper, bronze and iron later. Their arts are above all those where fire intervenes and their era is that known for the most arduous efforts of the inventive activity. These same men, who introduced metals, have in fact established themselves as the creators of a such powerful mechanisms allowing the maneuver of the monstrous blocks making the first monuments of the architecture. Thus, they gave birth to Cave Art.

Keywords: homo sapiens, prehistoric art, cave art, The old stone age (paleolithic Era)

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Authors: Randa Boukhris, Alima Damak, Dorra Sellami

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Fingervein biometric authentication is one of the most popular and accurate technologies. However, low cost embedded solution is still an open problem. In this paper, a real-time implementation of fingervein recognition process embedded in Raspberry-Pi has been proposed. The use of Raspberry-Pi reduces overall system cost and size while allowing an easy user interface. Implementation of a target technology has guided to opt some specific parallel and simple processing algorithms. In the proposed system, we use four structural directional kernel elements for filtering finger vein images. Then, a Top-Hat and Bottom-Hat kernel filters are used to enhance the visibility and the appearance of venous images. For feature extraction step, a simple Local Directional Code (LDC) descriptor is applied. The proposed system presents an Error Equal Rate (EER) and Identification Rate (IR), respectively, equal to 0.02 and 98%. Furthermore, experimental results show that real-time operations have good performance.

Keywords: biometric, Bottom-Hat, Fingervein, LDC, Rasberry-Pi, ROI, Top-Hat

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Authors: Tasnim Kallel, Rim Taktak

Abstract:

In this experimental work, fiber reinforced polymer (FRP) composite laminates were manufactured using hand lay-up technique. The unsaturated polyester (UP) and vinylester (VE) were considered as resins reinforced with different woven fabrics (bidirectional and quadriaxial rovings). The mechanical behaviour of the resulting composites was studied and then compared. A focus was essentially done on the evaluation of the effect of E-Glass fiber and ply orientation on the mechanical properties such as tensile strength, flexural strength, and hardness of the studied composite laminates. Also, crack paths and fracture surfaces were examined, and failure mechanisms were analyzed. From the main results, it was found that the quadriaxial composite laminates (QA/VE and QA/UP) with stacking sequences of [0°, +45°, 90°, -45°] present a very ductile tensile behaviour. The other laminate samples (R500/VE, RM/VE, R500/UP and RM/UP) show a very brittle behaviour whatever the used resin. The intrinsic toughness KIC of QA/VE laminate, obtained in fracture tests, are found more important than that of RM/VE composite. Thus, the QA/VE samples, as multidirectional laminate, presents the highest interlaminar fracture resistance.

Keywords: crack growth, fiber orientation, fracture behavior, e-glass fiber fabric, laminate composite, mechanical behavior

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Authors: Doaa M. Atia, Faten H. Fahmy, Ninet M. A. El-Rahman, Hassan T. Dorra

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In this paper, the optimum design for renewable energy system powered an aquaculture pond was determined. Hybrid Optimization Model for Electric Renewable (HOMER) software program, which is developed by U.S National Renewable Energy Laboratory (NREL), is used for analyzing the feasibility of the stand-alone and hybrid system in this study. HOMER program determines whether renewable energy resources satisfy hourly electric demand or not. The program calculates energy balance for every 8760 hours in a year to simulate operation of the system. This optimization compares the demand for the electrical energy for each hour of the year with the energy supplied by the system for that hour and calculates the relevant energy flow for each component in the model. The essential principle is to minimize the total system cost while HOMER ensures control of the system. Moreover the feasibility analysis of the energy system is also studied. Wind speed, solar irradiance, interest rate and capacity shortage are the parameters which are taken into consideration. The simulation results indicate that the hybrid system is the best choice in this study, yielding lower net present cost. Thus, it provides higher system performance than PV or wind stand-alone systems.

Keywords: wind stand-alone system, photovoltaic stand-alone system, hybrid system, optimum system sizing, feasibility, cost analysis

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Authors: Fathi Kallel, Ahmed Ben Hamida, Christian Berger-Vachon

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In this paper, a Speech Enhancement Algorithm based on Multi-Band Spectral Subtraction (MBSS) principle is evaluated for Bilateral Cochlear Implant (BCI) users. Specifically, dual-channel noise power spectral estimation algorithm using Power Spectral Densities (PSD) and Cross Power Spectral Densities (CPSD) of the observed signals is studied. The enhanced speech signal is obtained using Dual-Channel Multi-Band Spectral Subtraction ‘DC-MBSS’ algorithm. For performance evaluation, objective speech assessment test relying on Perceptual Evaluation of Speech Quality (PESQ) score is performed to fix the optimal number of frequency bands needed in DC-MBSS algorithm. In order to evaluate the speech intelligibility, subjective listening tests are assessed with 3 deafened BCI patients. Experimental results obtained using French Lafon database corrupted by an additive babble noise at different Signal-to-Noise Ratios (SNR) showed that DC-MBSS algorithm improves speech understanding for single and multiple interfering noise sources.

Keywords: speech enhancement, spectral substracion, noise estimation, cochlear impalnt

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Authors: H. Bouaziz-Ketata, G. Ben Salah, Z. Aidi, C. Kallel, H. Kammoun, F. Fakhfakh, N. Zeghal

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The present study was performed to evaluate the potential protective effect of Hyparrhenia hirta methanolic extract in NaNO3-induced genotoxic and hematotoxic effects. Male Wistar rats were randomly divided into three groups: a control group and two treated groups during 50 days with NaNO3 administered at a dose of 400 mg kg-1 bw either alone in drinking water or co-administered with Hyparrhenia hirta at a dose of 200 mg kg-1 bw. NaNO3 treatment showed a significant increase in the frequencies of total chromosomal aberrations, aberrant metaphases and micronucleus in bone-marrow cells. In parallel, the NaNO3-treated group showed a significant decrease in red blood cell count, hemoglobin and hematocrit and a significant increase in total white blood cell, in neutrophil and eosinophil counts. Platelet count, mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration remained unchanged in treated groups compared to those of controls. Hyparrhenia hirta methanolic extract appeared to be effective against genotoxic and hematotoxic changes induced by nitrate, as evidenced by the improvement of the markers cited above.

Keywords: Hyparrhenia hirta, sodium nitrate, erythrocytes, genotoxicity

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Authors: Houda Kohli Kallel, Soumaya Gharsallah Falhi

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Kerkennah Islands are a group of islands lying off the eastern coast of Tunisia, 15 miles from the Sfaxian coast. This archipelago covers an area of 150 square kilometres, and it consists of two main islands : The Gharbi and The Chergui . It also covers twelve more islets. Kerkennah is endowed with an exceptional cultural, natural and ecological potential, essential for the sustainability of the island community. Hence ,the inhabitants there have mobilized the natural resources of their land for decades. However, today, and despite these heritage treasures, Kerkennian islanders are facing social, economic and environmental challenges which are currently hindering the development of the traditional activities of fishing and farming. Other than being isolated and having a non-diversified economy, we cite the erosion of the stream banks, the exodus of young people and the population aging. "This study find the solutions that are likely to allow a sustainable development of the island territory, its enhancement and the strengthening of its identity. It is also necessary to study the key factors impacting the archipelago’s cultural tourism of decision makers and citizens. First, we will present the archipelago. Second, we will describe its tangible as well as intangible heritage. Then, we will present the new modes of the site exploitation. Finally, we will identify some new projects paving the way to a sustainable tourism in Kerkennah such as Borj EL Lahssar archaeological digs and Kerkennah insular heritage museum. To conclude, the archipelago of Kerkennah needs to reintegrate all its historical, architectural and archaeological assets in order to enhance its cultural tourism based on the cultural circuits of the territorial identities and the island values.

Keywords: kerkennah, identity, heritage, historical architectural

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Authors: Moujib Bahri, Ouafa Sakka, Kallel Rahim

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This study builds on the literature about the effects of corruption on economic growth at the firm level, which analyzes how the payment of bribes affect organizational performance. Traditionally, the literature distinguishes two points of view regarding the impact of corruption: grease view and sand view. The grease view is based on the idea that corruption can compensate for the negative effect of red tape on firms’ activities such as innovation and exports. Therefore, some firms will be motivated to pay some additional money to officials in order to reduce the delay related to bureaucratic procedures. On the contrary, the second point of view considers that corruption sands the wheels of the economy and distorts resource allocation because it increases agency and transaction costs and reduces the returns on the investment. We have tested the effect of corruption on innovation and export activities on a sample of 537 Tunisian manufacturing small and medium enterprises (SMEs) using structural equation modeling and path analysis. Tunisia has undergone a revolution in 2010 and since then, the country is experiencing a political instability and economic hardships. Our results do not support the greasing hypothesis suggesting that corruption can reduce the negative effect of bureaucratic delays and the hard access of companies to public services related to exports. Instead, our results support the sanding hypothesis according to which corruption hinders SMEs’ exports through its negative influence on innovation. Furthermore, our results show that the interaction between excessive bureaucratic red tape and corruption has a negative effect on exports. However, the interaction between political instability and corruption increases exports.

Keywords: corruption, exports, SMEs, economic conditions

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Authors: Omneya N. Mekhaimer, Elkhayam M. Dorra, A. Samer Ezeldin

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Over the recent decades, studies on organizational culture have gained global attention in the business management literature, where it has been established that the cultural factors embedded in the organization have an implicit yet significant influence on the organization’s success. Unlike other industries, the construction industry is widely known to be operating in a dynamic and adversarial nature; considering the unique characteristics it denotes, thereby the level of disputes has propagated in the construction industry throughout the years. In the late 1990s, the International Council for Research and Innovation in Building and Construction (CIB) created a Task Group (TG-23), which later evolved in 2006 into a Working Commission W112, with a strategic objective to promote research in investigating the role and impact of culture in the construction industry worldwide. To that end, this paper aims to study the influence of organizational culture in the contractor’s organization on the frequency of disputes caused between the owner and the contractor that occur in commercial projects based in Egypt. This objective is achieved by using a quantitative approach through a survey questionnaire to explore the dominant cultural attributes that exist in the contractor’s organization based on the Competing Value Framework (CVF) theory, which classifies organizational culture into four main cultural types: (1) clan, (2) adhocracy, (3) market, and (4) hierarchy. Accordingly, the collected data are statistically analyzed using Statistical Package for Social Sciences (SPSS 28) software, whereby a correlation analysis using Pearson Correlation is carried out to assess the relationship between these variables and their statistical significance using the p-value. The results show that there is an influence of organizational culture attributes on the frequency of disputes whereby market culture is identified to be the most dominant organizational culture that is currently practiced in contractor’s organization, which consequently contributes to increasing the frequency of disputes in commercial projects. These findings suggest that alternative management practices should be adopted rather than the existing ones with an aim to minimize dispute occurrence.

Keywords: construction projects, correlation analysis, disputes, Egypt, organizational culture

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Authors: Fathi Kallel, Abdulelah Alabd Uljabbar, Abdulrahman Aldukhail, Abdulaziz Alomran

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The brain is an important organ in our body since it is responsible about the majority actions such as vision, memory, etc. However, different diseases such as Alzheimer and tumors could affect the brain and conduct to a partial or full disorder. Regular diagnosis are necessary as a preventive measure and could help doctors to early detect a possible trouble and therefore taking the appropriate treatment, especially in the case of brain tumors. Different imaging modalities are proposed for diagnosis of brain tumor. The powerful and most used modality is the Magnetic Resonance Imaging (MRI). MRI images are analyzed by doctor in order to locate eventual tumor in the brain and describe the appropriate and needed treatment. Diverse image processing methods are also proposed for helping doctors in identifying and analyzing the tumor. In fact, a large Computer Aided Diagnostic (CAD) tools including developed image processing algorithms are proposed and exploited by doctors as a second opinion to analyze and identify the brain tumors. In this paper, we proposed a new advanced CAD for brain tumor identification, classification and feature extraction. Our proposed CAD includes three main parts. Firstly, we load the brain MRI. Secondly, a robust technique for brain tumor extraction is proposed. This technique is based on both Discrete Wavelet Transform (DWT) and Principal Component Analysis (PCA). DWT is characterized by its multiresolution analytic property, that’s why it was applied on MRI images with different decomposition levels for feature extraction. Nevertheless, this technique suffers from a main drawback since it necessitates a huge storage and is computationally expensive. To decrease the dimensions of the feature vector and the computing time, PCA technique is considered. In the last stage, according to different extracted features, the brain tumor is classified into either benign or malignant tumor using Support Vector Machine (SVM) algorithm. A CAD tool for brain tumor detection and classification, including all above-mentioned stages, is designed and developed using MATLAB guide user interface.

Keywords: MRI, brain tumor, CAD, feature extraction, DWT, PCA, classification, SVM

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Authors: Moujib Bahri, Rahim Kallel, Ouafa Sakka

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Corruption is a phenomenon that increases uncertainty and risk of SMEs as it undermines the quality of the business environment and the easy access to public services. Our research builds on existing research on corruption's effects on economic growth at the firm level. Several papers have analyzed the effect of firms’ payments of bribes on their performance; however, only limited research has investigated the link between corruption, innovation, and exports. Drawing on principal-agent theory, we explore how corruption weakens the institutional context and makes the business environment unsound and not conducive to innovation and exports. This study employs data from The Enterprise Surveys conducted in Tunisia between March 2013 and July 2014 by the World Bank, the European Bank for Reconstruction and Development (EBRD) and the European Investment Bank (EIB). The main objective of this survey was to gain a better understanding of Tunisian firms’ perception of the environment in which they operate. Since 2011, the country's political situation has become fragile and unstable, and public services are perceived as inefficient and corrupt. We test our hypotheses on a sample of 537 Tunisian manufacturing SMEs using structural equation modeling and path analysis. We find that political instability leads to higher level of corruption, and that excessive business licensing regulations create a fertile ground for bribery. Our findings do not support the greasing hypothesis suggesting that corruption can reduce the negative effect of bureaucratic delays and the hard access of companies to public services related to innovation and exports. Instead, our results support the sanding hypothesis according to which corruption hinders innovation activities and exports. Furthermore, corruption is found to, negatively and significantly, impact firms’ ownership of quality certificates. Our results suggest that, in an environment with a high level of corruption, governments and policymakers interested in assisting SMEs with their innovation and export activities should have a better control on corruption to allow them developing those activities without being forced to bribe government officers.

Keywords: corruption, innovation, exports, SMEs

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