Robust Nonlinear Control of a Mobile Robot

Ghania Zidani,Said Drid,Larbi Chrifi-Alaoui,Djemai Arar,Pascal Bussy 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.4

A robust control intended for a nonholonomic mobile robot is considered to guarantee good tracking a desired trajectory. The main drawbacks of the mobile robot model are the existence of nonholonomic constraints, uncertain system parameters and un-modeled dynamics. in order to overcome these drawbacks, we propose a robust control based on Lyapunov theory associated with sliding-mode control, this solution shows good robustness with respect to parameter variations, measurement errors, noise and guarantees position and velocity tracking. The global asymptotic stability of the overall system is proven theoretically. The simulation results largely confirm the effectiveness of the proposed control.

Optimization of a finite element mesh for plates subjected to in-plane patch loading

Ghania Ikhenazen,Messaoud Saidani,Madina Kilardj 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.3

In designing in-plane stressed thin plates, the loading condition where the uniform distributed edge forces are locally applied along one or more of the plate’s boundaries is often encountered. We investigated the optimal grid pattern that can be used in the analysis of the displacement and stress fields of a simply supported thin plate partially compressed. The plate modelling was created by means of an isoparametric rectangular element. This grid pattern was designed to satisfy good accuracy with low density. A convergence analysis was performed through different sets of meshes locally refined in a judicious way. For each focused field, the critical plate area was searched. Displacement and max stress values were recorded in the respective searched critical zone. Good results were obtained in seeking stress and displacement fields using, respectively, a small and a more expanded local refinement.

Sperm DNA Fragmentation and Standard Semen Parameters in Algerian Infertile Male Partners

Ghania Belaaloui,Sarah Boushaba 대한남성과학회 2015 The World Journal of Men's Health Vol.33 No.1

Purpose: To date, standard semen parameters have been the only parameters investigated in sperm samples of infertile men in Algeria. We investigated, for the first time, semen parameters according to sperm DNA fragmentation (SDF) in these subjects. Materials and Methods: SDF was determined by a validated sperm chromatin dispersion test in 26 infertile men. Patients were split into two groups according to the SDF level estimated by the DNA fragmentation index (DFI): the low fragmentation group (LFG; LFG with DFI ≤18%) and high fragmentation group (HFG; HFG with DFI >18%). The standard semen parameters were measured in both groups.Results: We found that semen concentration and motility were negatively correlated with DFI (r=−0.65, r=−0.45, respectively; p<0.05), while morphology and semen volume were not correlated with it (r=0.24, r=−0.18, respectively; p>0.05). Comparison of the sperm concentration revealed that it was significantly higher in LFG than in HFG (37.57%±13.16% vs. 7.32%±3.59%, respectively; p<0.05), whereas no significant difference was observed regarding sperm motility and morphology.Conclusions: Our findings suggest that SDF correlates well with both sperm motility and concentration but not with morphology. Thus, we conclude that SDF evaluation provides additional information regarding sperm quality, and should be used as a complementary test for assessing semen characteristics in infertile males.

Monitoring for Mutual Effects of Switching Power Capacitors in Power Systems

Ghania, Samy M.,Elwer, Ayman S.,Morsi, Reda,Salama, M.M.A. The Korean Institute of Power Electronics 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.4

Power system perturbations are due to many reasons; one of the most common perturbation causes is switching off/on the power capacitors. This paper monitors and discusses the overvoltages which appear on local and remote capacitor connected buses in power systems. Using the Fast Fourier Transfer (FFT), the total harmonic content of voltages and currents waveforms is also estimated at all buses. The power factor during different cases of switching modes "off/on" is monitored. The monitoring technique tackles not only the longitudinal long distance mutual effects of switching power capacitors between different buses but also evaluates the overvoltage durations. A relative long term monitoring is implemented using the Matlab/Simulink environment to show severity assessments in different switching modes on the transformers' voltages and currents' waveforms.

Robust Nonlinear Control of a Mobile Robot

Zidani, Ghania,Drid, Said,Chrifi-Alaoui, Larbi,Arar, Djemai,Bussy, Pascal The Korean Institute of Electrical Engineers 2016 Journal of Electrical Engineering & Technology Vol.11 No.4

A robust control intended for a nonholonomic mobile robot is considered to guarantee good tracking a desired trajectory. The main drawbacks of the mobile robot model are the existence of nonholonomic constraints, uncertain system parameters and un-modeled dynamics. in order to overcome these drawbacks, we propose a robust control based on Lyapunov theory associated with sliding-mode control, this solution shows good robustness with respect to parameter variations, measurement errors, noise and guarantees position and velocity tracking. The global asymptotic stability of the overall system is proven theoretically. The simulation results largely confirm the effectiveness of the proposed control.

Monitoring for Mutual Effects of Switching Power Capacitors in Power Systems

Samy M. Ghania,Ayman S. Elwer,Reda Morsi,M. M. A. Salama 전력전자학회 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.4

Power system perturbations are due to many reasons; one of the most common perturbation causes is switching off/on the power capacitors. This paper monitors and discusses the overvoltages which appear on local and remote capacitor connected buses in power systems. Using the Fast Fourier Transfer (FFT), the total harmonic content of voltages and currents waveforms is also estimated at all buses. The power factor during different cases of switching modes “off/on” is monitored. The monitoring technique tackles not only the longitudinal long distance mutual effects of switching power capacitors between different buses but also evaluates the overvoltage durations. A relative long term monitoring is implemented using the Matlab/Simulink environment to show severity assessments in different switching modes on the transformers’ voltages and currents’ waveforms.

Linear and nonlinear buckling analysis of a locally stretched plate

Madina Kilardj,Ghania Ikhenazen,Tanguy Messager,Toufik Kanit 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.8

Uniformly stretched thin plates do not buckle unless they are in special boundary conditions. However, buckling commonly occurs around discontinuities, such as cracks, cuts, narrow slits, holes, and different openings, of such plates. This study aims to show that buckling can also occur in thin plates that contain no defect or singularity when the stretching is local. This specific stability problem is analyzed with the finite element method. A brief literature review on stretched plates is presented. Linear and nonlinear buckling stress analyses are conducted for a partially stretched rectangular plate, and various load cases are considered to investigate the influence of the partial loading expanse on the critical tensile buckling load. Results are summarized in iso-stress areas, tables and graphs. Local stretching on one end of the plate induces buckling in the thin plate even without geometrical imperfection.

SOME TOPOLOGICAL RESULTS AND A FIXED POINT THEOREM IN A-METRIC SPACES

Zeid I. AL-Muhiameed,Ghania Benhamdda,Mahmoud Bousselsal 경남대학교 기초과학연구소 2018 Nonlinear Functional Analysis and Applications Vol.23 No.3

In this paper, we prove some topological properties and a common fixed point type theorem for two self mappings on new generalized metric spaces, called A−metric spaces.

The relationship of sperm DNA integrity with serum vitamin levels (folate and cobalamin) and food consumption in infertile men

Sara Boushaba,Yassine Helis,Rachida Lebaal,Sabah Beldjebel,Ayache Benhamza,Chafia Ziti,Ghania Belaaloui The Korean Society for Reproductive Medicine 2023 Clinical and Experimental Reproductive Medicine Vol.50 No.1

Objective: The aim of this study was to investigate the relationships of serum folate (vitamin B9), cobalamin (vitamin B12) levels and diet with semen parameters (semen standard parameters [SSP] and DNA fragmentation index [DFI]) in infertile men. Methods: Sperm samples were assessed for SSP and DFI (using the sperm chromatin dispersion test). Serum vitamin concentrations were measured with an immuno-electrochemiluminescence assay, and men completed a semi-quantitative food frequency questionnaire (FFQ). Results: Serum folate levels were positively correlated with sperm progressive motility and DFI. A comparison of SSP between two groups of patients according to serum folate concentration (B9 <4.840 ng/mL and B9 ≥4.840 ng/mL) showed significantly higher sperm concentration and sperm progressive motility in the latter group. However, there was no difference between these groups regarding DFI. Interestingly, serum folate levels were significantly higher in patients with a high DFI (using the cut-offs of 30% or 18%). FFQ data showed that the consumption of fruits and egg yolk correlated positively with sperm concentration and sperm motility, respectively. Conclusion: Serum folate levels showed significant associations with sperm concentration and sperm progressive motility. However, the positive association of serum folate with DFI raises the need for careful prescription of folate supplements.