Effective vibration control of multimodal structures with low power requirement

Loukil, Thamina,Ichchou, Mohamed,Bareille, Olivier,Haddar, Mohamed Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.13 No.3

In this paper, we investigate the vibration control of multimodal structures and present an efficient control law that requires less energy supply than active strategies. This strategy is called modal global semi-active control and is designed to work as effectively as the active control and consume less power which represents its major limitation. The proposed law is based on an energetic management of the optimal law such that the controller follows this latter only if there is sufficient energy which will be extracted directly from the system vibrations itself. The control algorithm is presented and validated for a cantilever beam structure subjected to external perturbations. Comparisons between the proposed law performances and those obtained by independent modal space control (IMSC) and semi-active control schemes are offered.

Effective vibration control of multimodal structures with low power requirement

Thamina Loukil,Mohamed Ichchou,Olivier Bareille,Mohamed Haddar 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.13 No.3

In this paper, we investigate the vibration control of multimodal structures and present anefficient control law that requires less energy supply than active strategies. This strategy is called modal global semi-active control and is designed to work as effectively as the active control and consume less power which represents its major limitation. The proposed law is based on an energetic management of theoptimal law such that the controller follows this latter only if there is sufficient energy which will beextracted directly from the system vibrations itself. The control algorithm is presented and validated for acantilever beam structure subjected to external perturbations. Comparisons between the proposed lawperformances and those obtained by independent modal space control (IMSC) and semi-active controlschemes are offered.

Filtering and Intrusion Detection Approach for Secured Reconfigurable Mobile Systems

Idriss, Rim,Loukil, Adlen,Khalgui, Mohamed,Li, Zhiwu,Al-Ahmari, Abdulrahman The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.5

This paper deals with reconfigurable secured mobile systems where the reconfigurability has the potential of providing a required adaptability to change the system requirements. The reconfiguration scenario is presented as a run-time automatic operation which allows security mechanisms and the addition-removal-update of software tasks. In particular, there is a definite requirement for filtering and intrusion detection mechanisms that will use fewer resources and also that will improve the security on the secured mobile devices. Filtering methods are used to control incoming traffic and messages, whereas, detection methods are used to detect malware events. Nevertheless, when different reconfiguration scenarios are applied at run-time, new security threats will be emerged against those systems which need to support multiple security objectives: Confidentiality, integrity and availability. We propose in this paper a new approach that efficiently detects threats after reconfigurable scenarios and which is based on filtering and intrusion detection methods. The paper's contribution is applied to Android where the evaluation results demonstrate the effectiveness of the proposed middleware in order to detect the malicious events on reconfigurable secured mobile systems and the feasibility of running and executing such a system with the proposed solutions.

A damage model predicting moderate temperature and size effects on concrete in compression

Wiem Ben Hassine,Marwa Loukil,Oualid Limam 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.23 No.5

Experimental isotherm compressive tests show that concrete behaviour is dependent on temperature. The aim of such tests is to reproduce how concrete will behave under environmental changes within a moderate range of temperature. In this paper, a novel constitutive elastic damage behaviour law is proposed based on a free energy with an apparent damage depending on temperature. The proposed constitutive behaviour leads to classical theory of thermo-elasticity at small strains. Fixed elastic mechanical characteristics and fixed evolution law of damage independent of temperature and the material volume element size are considered. This approach is applied to compressive tests. The model predicts compressive strength and secant modulus of elasticity decrease as temperature increases. A power scaling law is assumed for specific entropy as function of the specimen size which leads to a volume size effect on the stress-strain compressive behaviour. The proposed model reproduces theoretical and experimental results from literature for tempertaures ranging between 20°C and 70°C. The effect of the difference in the coefficient of thermal expansion between the mortar and coarse aggregates is also considered which gives a better agreement with FIB recommendations. It is shown that this effect is of a second order in the considered moderate range of temperature.

Cloning and molecular characterization of a new fungal xylanase gene from Sclerotinia sclerotiorum S2

( Olfa Elleuch Ellouze ),( Sana Loukil ),( Mohamed Nejib Marzouki ) 생화학분자생물학회(구 한국생화학분자생물학회) 2011 BMB Reports Vol.44 No.10

Sclerotinia sclerotiorum fungus has three endoxylanases induced by wheat bran. In the first part, a partial xylanase sequence gene (90 bp) was isolated by PCR corresponding to catalytic domains (β 5 and β 6 strands of this protein). The high homology of this sequence with xylanase of Botryotinia fuckeliana has permitted in the second part to amplify the XYN1 gene. Sequence analysis of DNA and cDNA revealed an ORF of 746 bp interrupted by a 65 bp intron, thus encoding a predicted protein of 226 amino acids. The mature enzyme (20.06 kDa), is coded by 188 amino acid (pI 9.26). XYN1 belongs to G/11 glycosyl hydrolases family with a conserved catalytic domain containing E86 and E178 residues. Bioinformatics analysis revealed that there was no Asn-X-Ser/Thr motif required for N-linked glycosylation in the deduced sequence however, five O-glycosylation sites could intervene in the different folding of xylanses isoforms and in their secretary pathway. [BMB reports 2011; 44(10): 653-658]

Filtering and Intrusion Detection Approach for Secured Reconfigurable Mobile Systems

Rim Idriss,Adlen Loukil,Mohamed Khalgui,Zhiwu Li,Abdulrahman Al-Ahmari 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.5

This paper deals with reconfigurable secured mobile systems where the reconfigurability has the potential of providing a required adaptability to change the system requirements. The reconfiguration scenario is presented as a run-time automatic operation which allows security mechanisms and the addition-removal-update of software tasks. In particular, there is a definite requirement for filtering and intrusion detection mechanisms that will use fewer resources and also that will improve the security on the secured mobile devices. Filtering methods are used to control incoming traffic and messages, whereas, detection methods are used to detect malware events. Nevertheless, when different reconfiguration scenarios are applied at run-time, new security threats will be emerged against those systems which need to support multiple security objectives: Confidentiality, integrity and availability. We propose in this paper a new approach that efficiently detects threats after reconfigurable scenarios and which is based on filtering and intrusion detection methods. The paper’s contribution is applied to Android where the evaluation results demonstrate the effectiveness of the proposed middleware in order to detect the malicious events on reconfigurable secured mobile systems and the feasibility of running and executing such a system with the proposed solutions.

A Virtual Laboratory to Practice Mobile Wireless Sensor Networks: A Case Study on Energy Efficient and Safe Weighted Clustering Algorithm

Dahane, Amine,Berrached, Nasr-Eddine,Loukil, Abdelhamid Korea Information Processing Society 2015 Journal of information processing systems Vol.11 No.2

In this paper, we present a virtual laboratory platform (VLP) baptized Mercury allowing students to make practical work (PW) on different aspects of mobile wireless sensor networks (WSNs). Our choice of WSNs is motivated mainly by the use of real experiments needed in most courses about WSNs. These experiments require an expensive investment and a lot of nodes in the classroom. To illustrate our study, we propose a course related to energy efficient and safe weighted clustering algorithm. This algorithm which is coupled with suitable routing protocols, aims to maintain stable clustering structure, to prevent most routing attacks on sensor networks, to guaranty energy saving in order to extend the lifespan of the network. It also offers a better performance in terms of the number of re-affiliations. The platform presented here aims at showing the feasibility, the flexibility and the reduced cost of such a realization. We demonstrate the performance of the proposed algorithms that contribute to the familiarization of the learners in the field of WSNs.

A Virtual Laboratory to Practice Mobile Wireless Sensor Networks: A Case Study on Energy Efficient and Safe Weighted Clustering Algorithm

( Amine Dahane ),( Nasr Eddine Berrached ),( Abdelhamid Loukil ) 한국정보처리학회 2015 Journal of information processing systems Vol.11 No.2

In this paper, we present a virtual laboratory platform (VLP) baptized Mercury allowing students to make practical work (PW) on different aspects of mobile wireless sensor networks (WSNs). Our choice of WSNs is motivated mainly by the use of real experiments needed in most courses about WSNs. These experiments require an expensive investment and a lot of nodes in the classroom. To illustrate our study, we propose a course related to energy efficient and safe weighted clustering algorithm. This algorithm which is coupled with suitable routing protocols, aims to maintain stable clustering structure, to prevent most routing attacks on sensor networks, to guaranty energy saving in order to extend the lifespan of the network. It also offers a better performance in terms of the number of re-affiliations. The platform presented here aims at showing the feasibility, the flexibility and the reduced cost of such a realization. We demonstrate the performance of the proposed algorithms that contribute to the familiarization of the learners in the field of WSNs.

Bio-based composite as phase change material including spent coffee grounds and beeswax paraffin

Souissi Moez,Trigui Abdelwaheb,Jedidi Ilyes,Loukil Mohamed Sahbi,Abdelmouleh Makki 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.9

New types of bio-composite phase change materials (BCPCM) with improved thermal properties were made from spent ground coffee powder (C), beeswax (W) and low density polyethylene (LDPE). Beeswax is a relatively accessible phase change material of organic origin, with a significantly lower unit price compared to conventional phase change materials (PCM). The observations by SEM and FTIR spectroscopy showed that the BCPCMs were physically combined. Through these techniques, it was discovered that ground coffee was effectively impregnated with natural wax and LDPE. According to the thermal gravimetric analysis (TGA), the thermal stability of BCPCM was improved, due to the use of waste coffee grounds, in the working temperature range. The biocomposite possesses excellent performance as characterized by 136.9 J/g (W70C10PE20)>, 127.31 J/g (W70C20PE10)>, 126.95 J/g (W70C30)>, 121.08 J/g (W70PE30) of latent heat storage and tends to decrease the supercooling degree as compared with pure beeswax during melting/solidification process. By adding LDPE to the PCM, the melting time is reduced, demonstrating an improvement in thermal energy storage (TES) reaction time to the demand. The experimental results showed that the fraction of oils (12%) in spent ground coffee powder can participate in the improvement of the thermal properties of BCPMC. The use of biocompatible PCM by-products is suitable for applications in the field of heat storage because it is affordable and environmentally beneficial.

Shooting method applied to porous rotating disk: Darcy-Forchheimer flow of nanofluid

Muzamal Hussain,Humaira Sharif,Mohamed A. Khadimallah,Abir Mouldi,Hassen Loukil,Mohamed R. Ali,Abdelouahed Tounsi Techno-Press 2023 Advances in nano research Vol.14 No.3

The characteristics of motile microorganism and three dimensional Darcy-Forchheimer nanofluid flow by a porous rotatable disk with heat generation/absorption is reported. Thermophoretic and Brownian motion aspects are included by utilizing Buongiorno model. Moreover, slip conditions are considered on velocity, thermal, concentration and microorganism. Shooting procedure is implemented to find the numerical results of physical quantities are evaluated parametrically. The different physical parameters like heat sink/source parameter, thermal, Brownian number, thermophoresis parameter, concentration, Peclet number, bioconvected Lewis number, microorganism on concentration and density of motile microorganism distributions is considered. Graphs of concentration and microorganism are plotted to examine the influence of distinct prominent flow parameters.