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Brahim Gaies,Mahmoud-Sami Nabi 세종대학교 경제통합연구소 2019 Journal of Economic Integration Vol.34 No.3
This study examines how external financing (EF) affects growth in developing countries by distinguishing between two forms of external financing: debt and foreign direct investment (FDI). We show that both types favor growth by boosting investment through the credit channel. However, excessive external debt increases vulnerability to financial crises. Contrariwise, FDI plays an amortizing role by reducing a crisis’ effects. The empirical evidence confirms these results and demonstrates that, despite the more secure nature of FDI, mixed financing (debt and FDI) remains more profitable for developing countries because of the inverted U-shaped growth effect of the FDI-to-debt ratio. Moreover, exchange rate stability decreases vulnerability to financial crises, whereas higher stability turns into exchange rate rigidity and thus increases crisis occurrence.
Analysis of edge defects in an elastic plate using SH-waves
Brahim Mohammedi,Nahil A Sobh,Diab Abueidda,Belgacem-Bouzida Aissa 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1
The interaction of guided SH-waves with the beveled free end of a semi-infinite plate is analytically and numerically investigated. The material of the plate is assumed to be elastic, homogenous, and isotropic. The plate is modeled as a combination of a semi-infinite region and bounded wedged region separated by a common boundary. The analytical solution of the vertical free end case for the two regions is derived and used in verifying the numerical implementation. In this study, the SH 0 and the SH 1 first two incident modes are individually applied to analyze the corresponding reflected modes from the free end. Specifically, the elastic energy carried by the reflected modes is reported for a wide range of beveled angles and incident frequencies.
Optical Properties of a Two-Dimensional GeTe Layer
Brahim Marfoua,홍지상 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.3
Using the first principles calculations, we explored the optical properties of the two-dimensional -GeTe structure. The 2D monolayer -GeTe had an indirect band gap of 1.79 eV, and that indirect band gap was still observed in the bilayer although the band gap had decreased to 0.61 eV. We found that the optical band gap was much larger than the electrical band gap, which was due to the indirect band gap feature of the 2D -GeTe system. In both systems, we found a very large refractive index in the visible range. Particularly, the bilayer system had a refractive index larger than 2.5 for blue light. Furthermore, the bilayer structure was found to have a larger reflectivity at ultraviolet frequencies. Consequently, we propose that the bilayer -GeTe film can be utilized for potential optical device applications.
Brahim Brahmi,Ibrahim El Bojairami,Maarouf Saad,Mark Driscoll,Samir Zemam,Mohamed Hamza Laraki 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.1
This paper presents the design and validation of a new adaptive variable gain reaching law, integrated with sliding mode control (SMC), to control perturbed and unperturbed nonlinear systems. The novelty behind this law stems from its capability to overcome the main limitations involved with SMC. In contrast to existing reaching laws, system’s performance can be substantially enhanced via this law, with signifi cant reduction in the chattering phenomenon, along ensuring rapid convergence time of system’s trajectories towards equilibrium. The designed law not only integrates the features of both the exponential reaching law (ERL) and the power rate reaching law (PRL), but also overcomes their limitations. Simulation and comparison studies against ERL and PRL were carried out to validate the eff ectiveness and advantages of the proposed reaching law scheme (Proposed-RL). Furthermore, controlled experimental investigations were conducted using an exoskeleton robot (ETS-MARSE) to validate the scheme in real-time.
A C5 Parallel Robot Identification and Control
Brahim Achili,Boubaker Daachi,Arab Ali-cherif,Yacine Amirat 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.2
The paper proposes a controller scheme based on a priori identification for a C5 parallel robot. First we realize the identification of dynamic parameters of the robot using the Least Squares technique. Different data are used for this step of identification. The cross validation permitted to select and confirm the identified parameters. After, a control scheme (computed torque) is applied to control the C5 parallel robot. The functions of this control scheme are based on precedent identified parameters. In order to reduce the effect of the identification error, we have added a robustness term based on sliding mode technique. The stability of the system in closed loop is presented using the Lyapunov principle. Experimental results of identification and control are presented and show the effectiveness of our methodology.