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Blind Channel Estimation and Equalization
Said Elkassimi,Said Safi,B. Manaut 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.12
This paper presents the problem of blind channel estimation of a non-minimum phase system using three algorithms. These algorithms play an important role for blindly estimate the parameters of radio mobile channel. Thus studying the problem of blind channel equalization based on, the proposed algorithm, CMA and SKMAA algorithms. The simulation results in noisy environment and for different SNR values demonstrate that the proposed algorithm is more performing than other algorithms. In addition the Sign Kurtosis Maximization Adaptive Algorithm (SKMAA) is more powerful in comparison to constant modulus algorithm (CMA) at the blind channel equalization, that is to say gives the right equalization.
Highly Efficient Control of the Doubly Fed Induction Motor
Said Drid,Abdesslam Makouf,Mohamed-Said Nait-Said,Mohamed Tadjine 대한전기학회 2007 Journal of Electrical Engineering & Technology Vol.2 No.4
This paper deals with the high efficient vector control for the reduction of copper losses of the doubly fed motor. Firstly, the feedback linearization control based on Lyapunov approach is employed to design the underlying controller achieving the double fluxes orientation. The fluxes' controllers are designed independently of the speed. The speed controller is designed using the Lyapunov method especially employed to the unknown load torques. The global asymptotic stability of the overall system is theoretically proven. Secondly, a new Torque Copper Losses Factor is proposed to deal with the problem of the machine copper losses. Its main function is to optimize the torque in keeping the machine saturation at an acceptable level. This leads to a reduction in machine currents and therefore their accompanied copper losses guaranteeing improved machine efficiency. The simulation and experimental results in comparative presentation confirm largely the effectiveness of the proposed DFIM control with a very interesting energy saving contribution.
Highly Efficient Control of the Doubly Fed Induction Motor
Drid, Said,Makouf, Abdesslam,Nait-Said, Mohamed-Said,Tadjine, Mohamed The Korean Institute of Electrical Engineers 2007 Journal of Electrical Engineering & Technology Vol.2 No.4
This paper deals with the high efficient vector control for the reduction of copper losses of the doubly fed motor. Firstly, the feedback linearization control based on Lyapunov approach is employed to design the underlying controller achieving the double fluxes orientation. The fluxes# controllers are designed independently of the speed. The speed controller is designed using the Lyapunov method especially employed to the unknown load torques. The global asymptotic stability of the overall system is theoretically proven. Secondly, a new Torque Copper Losses Factor is proposed to deal with the problem of the machine copper losses. Its main function is to optimize the torque in keeping the machine saturation at an acceptable level. This leads to a reduction in machine currents and therefore their accompanied copper losses guaranteeing improved machine efficiency. The simulation and experimental results in comparative presentation confirm largely the effectiveness of the proposed DFIM control with a very interesting energy saving contribution.
2D Inverse Problem in a Distributed Parameter System
Said Rachidi,Rafik Channa,Asma Karama 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.6
In this paper, we present a numerical solution for an inverse heat problem to estimate 2D space-wise coefficient in a parabolic system describing heat transfer. The inverse problem is recast into an optimization problem solved with a conjugate gradient method. This approach use the non linear optimization formulation by minimizing a cost function taking into account both the measured outputs of the system and the outputs calculated by means of the model. The solution is performed by using the free finite element software FreeFem. Numerical example is carried out to check the validity of the proposed method.
Finite element analysis of elastic property of concrete composites with ITZ
Said Abdelmoumen,Brandon Lynge,Michele Queneudec-t'Kint,Emmanuel Bellenger 사단법인 한국계산역학회 2010 Computers and Concrete, An International Journal Vol.7 No.6
For better estimation of elastic property of concrete composites, the effect of Interfacial Transition Zone (ITZ) has been found to be significant. Numerical concrete composites models have been introduced using Finite Element Method (FEM), where ITZ is modeled as a thin shell surrounding aggregate. Therefore, difficulties arise from the mesh generation. In this study, a numerical concrete composites model in 3D based on FEM and random unit cell method is proposed to calculate elastic modulus of concrete composites with ITZ. The validity of the model has been verified by comparing the calculated elastic modulus with those obtained from other analytical and numerical models.
New Delay Dependent Robust Stability Criteria for T–S Fuzzy Systems with Constant Delay
Said Idrissi,El Houssaine Tissir,Ismail Boumhidi,Noreddine Chaibi 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.5
This paper deals with the problem of delay dependent robust stability for T–S fuzzy time delay systems. The approach based on constructing a new Lyapunov-Krasovskii functional by dividing uniformly the delay interval into N segment with N is positive integer, and using Finsler’s lemma. This new Lyapunov-Krasovskii functional is chosen with different weighted matrices corresponding to dif-ferent segments. The perturbations considered are norm bounded, and the results are expressed in terms of linear matrix inequality (LMIs). Numerical examples are provided to show the effectiveness of the present method, compared with some recent previous ones.
Investigating the Cash Holding Factors of Mining Industries in Indonesia Stock Exchange
Said Musnadi,Ghazali Syamni,Nasir,Faisal,Jumadil Saputra 대한산업공학회 2020 Industrial Engineeering & Management Systems Vol.19 No.3
The purpose of this study is to explore determinant factors that enable mining companies for cash holding in Indonesia. The panel data gathered from 40 financial statements of mining companies in Indonesia for the period 2013-2017 with a total of 200 observations. The panel data regression analysis used to examine and select the best model by utilizing the common effect model, fixed effect model and random effect model. The results of the study found that a cash holding company was determined by the return on assets, return on equity, net capital working, firm size, leverage and cash conversion cycle. All research variables mentioned above support trade-off theory except return on assets. The limitation of this study emerged since it made no separate discussion between the largest and the smallest cash holding companies. The results of this study have implications for management and companies to investigate other indicators enabling companies to conduct cash holding. Some suggested variables are macroeconomic factors, payment of dividends and investment opportunities and separation of large and small companies. The management of mining companies in managing cash holding was required to observe closely to the independent variables that match the trade-off or pecking order theory even the free cash flow theory.
Said R. Grace,Sandra Pinelas 장전수학회 2010 Proceedings of the Jangjeon mathematical society Vol.13 No.2
We establish several growth theorems for second order nonlinear differential and integro-differential equations. We also give necessary and suffcient conditions for solutions of second order non-linear differential equations to be bounded together with their frst derivatives and investigate its asymptotic behavior.
Numerical study of reinforced natural slope by retaining wall with prestressed anchor
Said, Nouri,Amar, Nechnech Techno-Press 2021 Advances in materials research Vol.10 No.2
The slope design under geological and hydraulic conditions has always been a different geotechnics problem. There have been potential main landslide and an undisturbed thin layer of saturated clays soil under the slopes in urban construction development area of Miliana city province of Algeria; its terrain is mountains. The landslide was framed by gravity creeping of thin layer of alluvium and mares cracks along steep clays. The favorable sliding surface larger than 2500 m<sup>2</sup> had destroyed the foundation of the building. In order to learn from the comparison between stabilized and non-stabilized slopes with different improvement, the authors also investigated the slopes reinforced by retaining wall with prestressed anchor and discussed their behavior parameters. Based on finite element method, the analysis of slope stability under natural conditions is discussed first, then the support structure of retaining wall and anchor reinforced and their effect of slope stability are analyzed, and also the slope stability of each case is able to be compared. The results show that the stability of slope was significantly improved after reinforcement, and anchor reinforced with retaining wall has obvious reverse anchoring effect on soil. By comparing the factor of safety, stress level and displacement field before and after slope reinforcement, it is found that better reinforcement results can be achieved if strong reinforcement is applied upon the regions with high sliding surface. Furthermore, the increase in stress level at the zone dangerous is more favorable of improving the safety of the critical region.