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Assessment of whipping and springing on a large container vessel
Mondher Barhoumi,Gaute Storhaug 대한조선학회 2014 International Journal of Naval Architecture and Oc Vol.6 No.2
Wave induced vibrations increase the fatigue and extreme loading, but this is normally neglected in design. The industry view on this is changing. Wave induced vibrations are often divided into springing and whipping, and their relative contribution to fatigue and extreme loading varies depending on ship design. When it comes to dis-placement vessels, the contribution from whipping on fatigue and extreme loading is particularly high for certain container vessels. A large modern design container vessel with high bow flare angle and high service speed has been considered. The container vessel was equipped with a hull monitoring system from a recognized supplier of HMON systems. The vessel has been operating between Asia and Europe for a few years and valuable data has been collected. Also model tests have been carried out of this vessel to investigate fatigue and extreme loading, but model tests are often limited to head seas. For the full scale measurements, the correlation between stress data and wind data has been investigated. The wave and vibration damage are shown versus heading and Beaufort strength to indicate general trends. The wind data has also been compared to North Atlantic design environment. Even though it has been shown that the encountered wind data has been much less severe than in North Atlantic, the extreme loading defined by IACS URS11 is significantly exceeded when whipping is included. If whipping may contribute to collapse, then proper sea-manship may be useful in order to limit the extreme loading. The vibration damage is also observed to be high from head to beam seas, and even present in stern seas, but fatigue damage in general is low on this East Asia to Europe trade.
Assessment of whipping and springing on a large container vessel
Barhoumi, Mondher,Storhaug, Gaute The Society of Naval Architects of Korea 2014 International Journal of Naval Architecture and Oc Vol.6 No.2
Wave induced vibrations increase the fatigue and extreme loading, but this is normally neglected in design. The industry view on this is changing. Wave induced vibrations are often divided into springing and whipping, and their relative contribution to fatigue and extreme loading varies depending on ship design. When it comes to displacement vessels, the contribution from whipping on fatigue and extreme loading is particularly high for certain container vessels. A large modern design container vessel with high bow flare angle and high service speed has been considered. The container vessel was equipped with a hull monitoring system from a recognized supplier of HMON systems. The vessel has been operating between Asia and Europe for a few years and valuable data has been collected. Also model tests have been carried out of this vessel to investigate fatigue and extreme loading, but model tests are often limited to head seas. For the full scale measurements, the correlation between stress data and wind data has been investigated. The wave and vibration damage are shown versus heading and Beaufort strength to indicate general trends. The wind data has also been compared to North Atlantic design environment. Even though it has been shown that the encountered wind data has been much less severe than in North Atlantic, the extreme loading defined by IACS URS11 is significantly exceeded when whipping is included. If whipping may contribute to collapse, then proper seamanship may be useful in order to limit the extreme loading. The vibration damage is also observed to be high from head to beam seas, and even present in stern seas, but fatigue damage in general is low on this East Asia to Europe trade.
walid Trabelsi,Mondher Belhaj Amor,Mohamed Anis Lebbi,Chiheb Romdhani,Sami Dhahri,Mustapha Ferjani 대한마취통증의학회 2013 Korean Journal of Anesthesiology Vol.64 No.4
Background: Infraclaviculr Brachial plexus (ICBP) block is useful for upper extremity surgery. The aim of this study was to compare the ultrasound (US) technique with the nerve stimulation (NS) technique in their success rates and times to perform ICBP block. Methods: 60 patients undergoing surgery of the upper limb were randomly allocated into two groups (n = 30 per group). Group 1; US, and Group 2; NS. Procedure time (including time for initial ultrasound examination), the success rate and the onset time of sensory and motor blockade were assessed. Results: The time needed to perform the ICBP block is similar in both groups (220 seconds ± 130 in US group versus 281 ± 134 seconds in NS group; P = 0.74). The success rate of all the nerve blocks in the US group was 100%. The success rate in the NS group was 73.3%, 76.7%, 76.7% and 100% for radial, ulnar, medial, and musculocutaneous nerve, respectively. A significantly faster onset of sensory block for the radial, ulnar, median, musculocutaneous, and the four nerves considered together were observed. The onset of motor block for the radial, ulnar, and medial nerves was faster in the US group. However, the onset of motor block for the musculocutaneous nerve and the four nerves considered together was comparable between the two groups. Conclusions: The ultrasound-guided infraclavicular brachial plexus block is a significantly efficacious method with faster onset but similar procedure time compared to the nerve stimulation technique.
CAPITAL ACCOUNT OPENNESS, POLITICAL INSTITUTIONS AND FDI IN MENA REGION: AN EMPIRICAL INVESTIGATION
MOUNA GAMMOUDI,MONDHER CHERIF 중앙대학교 경제연구소 2016 Journal of Economic Development Vol.41 No.2
This paper examines how capital account liberalization (CAL) affects Foreign Direct Investment (FDI) inflows. We use the System Generalized-Method-of-Moments (GMM) estimator developed for the dynamic panel model for a sample of 17 Middle East North and Africa (MENA) countries from 1985 to 2009. Our findings reveal that the positive impact of CAL on FDI depends on the political stability in a host country. Furthermore, results show that enhancing democratic institutions, enforcing property rights, reducing the risk of expropriation and the religious tension seem to be some of the most promising policies in terms of attracting FDI in the region. Also, we find that foreign investors value the quality of institutions more than the level of corruption or bureaucracy quality in the location choice. Our results are robust by using a different database of institutional qualities. Research findings are relevant for MENA countries given that many of them have engaged in a process of liberalization and have weak institutions.
An extended finite element method for modeling elastoplastic FGM plate-shell type structures
Hanen Jrad,Jamel Mars,Mondher Wali,Fakhreddine Dammak 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.3
In this paper, an extended finite element method is proposed to analyze both geometric and material non-linear behavior of general Functionally Graded Material (FGM) plate-shell type structures. A user defined subroutine (UMAT) is developed and implemented in Abaqus/Standard to study the elastoplastic behavior of the ceramic particle-reinforced metal-matrix FGM plates-shells. The standard quadrilateral 4-nodes shell element with three rotational and three translational degrees of freedom per node, S4, is extended in the present study, to deal with elasto-plastic analysis of geometrically non-linear FGM plate-shell structures. The elastoplastic material properties are assumed to vary smoothly through the thickness of the plate-shell type structures. The nonlinear approach is based on Mori-Tanaka model to underline micromechanics and locally determine the effective FGM properties and self-consistent method of Suquet for the homogenization of the stress-field. The elasto-plastic behavior of the ceramic/metal FGM is assumed to follow Ludwik hardening law. An incremental formulation of the elasto-plastic constitutive relation is developed to predict the tangent operator. In order to to highlight the effectiveness and the accuracy of the present finite element procedure, numerical examples of geometrically non-linear elastoplastic functionally graded plates and shells are presented. The effects of the geometrical parameters and the volume fraction index on nonlinear responses are performed.
An extended finite element method for modeling elastoplastic FGM plate-shell type structures
Jrad, Hanen,Mars, Jamel,Wali, Mondher,Dammak, Fakhreddine Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.3
In this paper, an extended finite element method is proposed to analyze both geometric and material non-linear behavior of general Functionally Graded Material (FGM) plate-shell type structures. A user defined subroutine (UMAT) is developed and implemented in Abaqus/Standard to study the elastoplastic behavior of the ceramic particle-reinforced metal-matrix FGM plates-shells. The standard quadrilateral 4-nodes shell element with three rotational and three translational degrees of freedom per node, S4, is extended in the present study, to deal with elasto-plastic analysis of geometrically non-linear FGM plate-shell structures. The elastoplastic material properties are assumed to vary smoothly through the thickness of the plate-shell type structures. The nonlinear approach is based on Mori-Tanaka model to underline micromechanics and locally determine the effective FGM properties and self-consistent method of Suquet for the homogenization of the stress-field. The elasto-plastic behavior of the ceramic/metal FGM is assumed to follow Ludwik hardening law. An incremental formulation of the elasto-plastic constitutive relation is developed to predict the tangent operator. In order to to highlight the effectiveness and the accuracy of the present finite element procedure, numerical examples of geometrically non-linear elastoplastic functionally graded plates and shells are presented. The effects of the geometrical parameters and the volume fraction index on nonlinear responses are performed.
( Mohamed Hedi Bchir ),( Hakim Ben Hammouda ),( Mondher Mimouni ),( Xavier Pichot ) 세종대학교 경제통합연구소(구 세종대학교 국제경제연구소) 2011 Journal of Economic Integration Vol.26 No.2
The Barcelona process is an ongoing process and its first economic results are still insignificant. This study had two objectives. The first is to provide a global assessment of its impacts on the three North African countries that have already became members of this process, namely Tunisia, Morocco and Egypt. The second objective is to explore its potentials by a larger inclusion of agriculture in the Euromed partnership. The approach adopted in this paper is the use of the MIRAGE global Computable General equilibrium Model and the MacMAPS database that gives a very detailed picture of the bilateral protection between all the WTO members. This approach allowed us to consider all the economic interactions that exist between the North African countries and the European Union as well as the economic interaction between the North African countries themselves. In addition a special emphasis was given to the compute methods used to aggregate tariffs. Indeed, existing methods of aggregation are underestimating the level of tariffs applied by the European Union on agricultural products. This underestimation induces an underestimation of the effects of agriculture liberalization on North African economies. In this paper, we develop an original method of aggregation that attempts to deal with this problem and that gives a more accurate approximation of the market access barriers applied by the European countries. Our main contribution in this article is to develop an original approach of aggregation that aims to obtain a more realistic estimation of the tariffs faced by developing countries and by consequence to obtain a more realistic estimation of the economic impacts of agricultural liberalization between developed and developing countries.
High Gain Adaptive Observer Design for Sensorless State and Parameter Estimation of Induction Motors
Abdelaziz Maouche,Mohammed M’Saad,Bachir Bensaker,Mondher Farza 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.5
This paper addresses the problem of accurately estimating the mechanical and magnetic state variables as well as the stator and rotor resistances of induction motors using only the stator current measurements and the supplied stator voltages from an appropriate nonlinear parametrization. The involved estimation is carried out by a high gain adaptive observer designed bearing in mind the available fundamental results together with the useful implementation features, namely conception simplicity and computational efficiency. An exponential convergence of the state and parameter estimation errors is established under admissible assumptions, namely the persistent excitation requirement has been particularly reduced thanks to the introduction of unknown parameter characteristic indices. The effectiveness of the adaptive observer is highlighted throughout simulation results involving a typical induction motor.