NUMERICAL AND EXPERIMENTAL INVESTIGATION OF THE DYNAMIC BEHAVIOR OF A VERTICAL ROTOR

Mohand Ouali Si-Chaib,Ahmed Chellil,Abdelkader Nour,Rachid Saci,Nouredine Chikh,Yvon Chevalier 한국소음진동공학회 2008 한국소음진동공학회 국제학술대회논문집 Vol.2008 No.7

Dynamic behavior of piezoelectric bimorph beams with a delamination zone

Adel Zemirline,Mohammed Ouali,Ali Mahieddine 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.19 No.3

The First Order Shear Deformation Theory (FOSDT) is considered to study the dynamic behavior of a bimorph beam. A delamination zone between the upper and the lower layer has been taken into consideration; the beam is discretised using the finite elements method (FEM). Several parameters are taken into consideration like structural damping, the geometry, the load nature and the configurations of the boundary conditions. Results show that the delamination between the upper and the lower layer affects considerably the actuation.

Modeling and simulation of partially delaminated composite beams

A. Mahieddine,M. Ouali,A. Mazouz 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.5

A finite-element model for beams with partially delaminated layers is used to investigate their behavior. In this formulation account is taken of lateral strains and the first-order shear deformation theory is used. Both displacement continuity and force equilibrium conditions are imposed between the regions with and without delamination. Numerical results of the present model are presented and its performance is evaluated for static and dynamic problems.

Global Stabilization of a Class of Delay Discrete-Time Nonlinear Systems via State and Output Feedback

Kheir Eddine Bouazza,Mohammed Ouali 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.6

This paper deals with stabilization of a class of delay discrete-time nonlinear systems through state and output feedback. We provide an explicit bounded state feedback law as an extension of the Jurdjevic-Quinn method, from nonlinear theory, to this class of systems. Next, we present a useful and systematic approach to design an observer for the same class of systems. Then, we show how the global stabilization problem via dynamic output feedback can be solved by using the two previous results. Finally, numerical examples are given to illustrate the effectiveness of the proposed design method.

Thermomechanical material parameters characterization of the superalloy PN 3601669-7 under low-velocity impacts

Abdelkader Nour,Samir Lecheb,Nouredine Chikh,M. Ouali Si-Chaïb 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.7

This work concerns the characterization of the thermodynamic behavior of the superalloy Airsist 215 (PN 3601669-7) containing cobalt. Such superalloys are used in aeronautical construction, in the hot parts of the turbine. They are frequently used for the production of the paddles. The parts in service are subjected to dynamic solicitations and thermal fluctuations over the course of time. They are responsible for modification and degradation of material properties. This can lead to the appearance of cracks and, in the long term, to the rupture of these parts. In this paper, a preliminary physical study is made on the appearance of the cracks, followed by experiments using shocks at ambient temperature and under a heating situation which simulates combustion. It is found that these dynamic loads have a significant impact on the development of the cracks that appear on the segments of the turbine nozzle. The study is devoted to the elastic shock of Hertz-Boussinesq extended to viscoelastic bodies by direct convolution of Riemann-Stielges. The interest resides in the local convolution and the distribution of stresses in the contact zone. The shock excitation method includes a deduced force in the load and disload phases. This force is an impulse which approaches a Dirac function. The sample can be modeled approximately by a system of one degree of freedom for natural frequency, damping and transfer function. The spectral response of the specified shock allows calculation of the damping. Every point of this spectrum gives the response for the linear system of the transfer function. Then, viscoelastic shock parameters are deduced.

An Efficient Chloride Ingress Model for Long-Term Lifetime Assessment of Reinforced Concrete Structures Under Realistic Climate and Exposure Conditions

Phu Tho Nguyen,Emilio Bastidas-Arteaga,Ouali Amiri,Charbel-Pierre El Soueidy 한국콘크리트학회 2017 International Journal of Concrete Structures and M Vol.11 No.2

Chloride penetration is among the main causes of corrosion initiation in reinforced concrete (RC) structures producing premature degradations.Weather and exposure conditions directly affect chloride ingress mechanisms and therefore the operational service life and safety of RC structures. Consequently, comprehensive chloride ingress models are useful tools to estimate corrosion initiation risks and minimize maintenance costs for RC structures placed under chloride-contaminated environments. This paper first presents a coupled thermo-hydro-chemical model for predicting chloride penetration into concrete that accounts for realistic weather conditions. This complete numerical model takes into account multiple factors affecting chloride ingress such as diffusion, convection, chloride binding, ionic interaction, and concrete aging. Since the complete model could be computationally expensive for long-term assessment, this study also proposes model simplifications in order to reduce the computational cost. Long-term chloride assessments of complete and reduced models are compared for three locations in France (Brest, Strasbourg and Nice) characterized by different weather and exposure conditions (tidal zone, de-icing salts and salt spray). The comparative study indicates that the reduced model is computationally efficient and accurate for long-term chloride ingress modeling in comparison to the complete one. Given that long-term assessment requires larger climate databases, this research also studies how climate models may affect chloride ingress assessment. The results indicate that the selection of climate models as well as the considered training periods introduce significant errors for mid- and long- term chloride ingress assessment.

An Efficient Chloride Ingress Model for Long-Term Lifetime Assessment of Reinforced Concrete Structures Under Realistic Climate and Exposure Conditions

Nguyen, Phu Tho,Bastidas-Arteaga, Emilio,Amiri, Ouali,Soueidy, Charbel-Pierre El Korea Concrete Institute 2017 International Journal of Concrete Structures and M Vol.11 No.2

Chloride penetration is among the main causes of corrosion initiation in reinforced concrete (RC) structures producing premature degradations. Weather and exposure conditions directly affect chloride ingress mechanisms and therefore the operational service life and safety of RC structures. Consequently, comprehensive chloride ingress models are useful tools to estimate corrosion initiation risks and minimize maintenance costs for RC structures placed under chloride-contaminated environments. This paper first presents a coupled thermo-hydro-chemical model for predicting chloride penetration into concrete that accounts for realistic weather conditions. This complete numerical model takes into account multiple factors affecting chloride ingress such as diffusion, convection, chloride binding, ionic interaction, and concrete aging. Since the complete model could be computationally expensive for long-term assessment, this study also proposes model simplifications in order to reduce the computational cost. Long-term chloride assessments of complete and reduced models are compared for three locations in France (Brest, Strasbourg and Nice) characterized by different weather and exposure conditions (tidal zone, de-icing salts and salt spray). The comparative study indicates that the reduced model is computationally efficient and accurate for long-term chloride ingress modeling in comparison to the complete one. Given that long-term assessment requires larger climate databases, this research also studies how climate models may affect chloride ingress assessment. The results indicate that the selection of climate models as well as the considered training periods introduce significant errors for mid- and long- term chloride ingress assessment.

Numerical investigation of the hysteretic response analysis and damage assessment of RC column

Abdelmounaim Mechaala,Benazouz Chikh,Hakim Bechtoula,Mohand Ould Ouali,Aghiles Nekmouche Techno-Press 2023 Advances in computational design Vol.8 No.2

The Finite Element (FE) modeling of Reinforced Concrete (RC) under seismic loading has a sensitive impact in terms of getting good contribution compared to experimental results. Several idealized model types for simulating the nonlinear response have been developed based on the plasticity distribution alone the model. The Continuum Models are the most used category of modeling, to understand the seismic behavior of structural elements in terms of their components, cracking patterns, hysteretic response, and failure mechanisms. However, the material modeling, contact and nonlinear analysis strategy are highly complex due to the joint operation of concrete and steel. This paper presents a numerical simulation of a chosen RC column under monotonic and cyclic loading using the FE Abaqus, to assessthe hysteretic response and failure mechanisms in the RC columns, where the perfect bonding option is used for the contact between concrete and steel. While results of the numerical study under cyclic loading compared to experimental tests might be unsuccessful due to the lack of bond-slip modeling. The monotonic loading shows a good estimation of the envelope response and deformation components. In addition, this work further demonstrates the advantage and efficiency of the damage distributions since the obtained damage distributions fit the expected results.

Ethnobotanical survey of herbs used in the preservation of food products in Fez, Morocco

Ez zoubi Yassine,Lairini Sanae,El Amrani Soukaina,El-Akhal Fouad,Farah Abdellah,Bouslamti Rabia,El Ouali Lalami Abdelhakim 한국식품연구원 2022 Journal of Ethnic Foods Vol.9 No.-

Morocco has a rich plant biodiversity and an ancient ethnobotanical knowledge influenced by the ethnic diversity of the Moroccan population. This heritage has been preserved from generation to generation by traditional herbalists. In this study, data were collected via a survey of herbalists based on the direct interview technique. Questions addressed the herbalists’ age and education level as well as the vernacular names and parts of the plants used for the preservation of food. The species use value was used to identify the most important species recommended by herbalists. The average age of the participants was 52.55 years, and the illiteracy rate was 46%. A total of 32 plant species representing 16 families were identified as being used in the preservation of various food products. The most important family was Lamiaceae, followed by Apiaceae and Rosaceae. The most frequently used parts of the plant were the leaves (26.37%), followed by the fruit (24.7%), and the whole plant (12.7%). The highest use values were recorded for Citrus limon (0.16), Thymus vulgaris (0.14), Rosmarinus officinalis (0.12), Artemisia herba alba (0.11) and Lavandula dentata (0.1). Meat, vegetables and fish were the most commonly preserved food products. This ethnobotanical survey on the preservation of food products is the first of its kind conducted in Morocco and has implications for meeting consumer demands and understanding the potential uses of plants in the preservation of food products.

Vasopressin and oxytocin expression in hypothalamic supraoptic nucleus and plasma electrolytes changes in water-deprived male Meriones libycus

Boumansour Lydia,Benhafri Nadir,Guillon Gilles,Corbani Maithe,Touati Hanane,Dekar-Madoui Aicha,Ouali-Hassenaoui Saliha 한국통합생물학회 2021 Animal cells and systems Vol.25 No.5

In mammals, plasmatic osmolality needs to be stable, and it is highly related to the hydric state of the animals which depends on the activity of the hypothalamic neurohypophysial system and more particularly by vasopressin secretion. Meriones, a desert rodent, can survive even without drinking for more than one month. The mechanism(s) by which they survive under these conditions remains poorly understood. In this study, we examine the water’s deprivation consequences on the: (1) anatomy, morphology, and physiology of the hypothalamic supraoptic nucleus, (2) body mass and plasma electrolytes changes in male desert rodents ‘Meriones libycus’ subjected to water deprivation for 30 days. The effect of water deprivation was evaluated on the structural and cellular organization of the supraoptic nucleus by morphological observations and immunohistochemical approaches, allowing the labeling of AVP but also oxytocin. Our finding demonstrated that upon water deprivation (1) the body weight decreased and reached a plateau after a month of water restriction. (2) The plasmatic osmolality began to decrease and return to values similar to control animals at day 30. (3) The SON, both in hydrated and water-deprived animals, is highly developed.(4) The AVP labeling in the SON increased upon dehydration at variance with OT. These changes observed in body mass and plasma osmolality reveal an important adaptive process of male Meriones in response to prolonged water deprivation. Overall, this animal represents an interesting model for the study of water body homeostasis and the mechanisms underlying the survival of desert rodents to xeric environments.