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Dynamic resource allocation for service in mobile cloud computing with Markov modulated arrivals

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International Journal of Modeling, Simulation, and Scientific Computing 2021年第5期12卷 97-117页

作者： Munatel Mohammed abdelkrim Haqiq Hassan First University of Settat Faculty of Sciences and Techniques Computer Networks Mobility and Modeling Laboratory:IR2M Settat 26000Morocco

Mobile Cloud Computing (MCC) is a modern architecture that brings together cloudcomputing, mobile computing and wireless networks to assist mobile devices in storage,computing and communication. A cloud environment is developed to support a widerange of users that request the cloud resources in a dynamic environment with possible constraints. Burstiness in users service requests causes drastic and unpredictableincreases in the resource requests that have a crucial impact on policies of resourceallocation. How can the cloud system efficiently handle such burstiness when the cloudresources are limited? This problem becomes a hot issue in the MCC research area. Inthis paper, we develop a system model for the resource allocation based on the SemiMarkovian Decision Process (SMDP), able of dynamically assigning the mobile servicerequests to a set of cloud resources, to optimize the usage of cloud resources and maximize the total long-term expected system reward when the arrival process is a finitestate Markov-Modulated Poisson Process (MMPP). Numerical results show that ourproposed model performs much better than the Greedy algorithm in terms of achievinghigher system rewards and lower service requests blocking probabilities, especially whenthe burstiness degree is high, and the cloud resources are limited.

关键词： Mobile cloud computing resource allocation burstiness Markov decision process

Shear reinforcement effect of reinforced concrete tie-columns on the lateral resistance of confined masonry walls

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Earthquake Engineering and Engineering Vibration 2016年第2期15卷 313-324页

作者： Samir Bouhedja abdelkrim Bourzam Ahmed Boukhaled Ammar Nechnech University of Sciences and Technology Houari Boumediene(USTHB)Faculty of Civil EngineeringLaboratory of EnvironmentWaterGeomechanics and Structures(LEEGO)BP 32 El AliaBab EzzouarAlgiers16111Algeria University of Sciences and Technology Houari Boumediene(USTHB)Faculty of Civil EngineeringLaboratory of Built Environment Research(LBE)BP 32 El AliaBab EzzouarAlgiers16111Algeria

Tie-columns improve significantly the lateral resistance of masonry bearing walls against persistent, transient and accidental loads. The research work described herein has been carried out to assess the lateral resistance of confined masonry walls, where contribution of the masonry panel is evaluated according to material mechanics and tie-columns effect is estimated by a proposed analytical formulation based on a model reported on previously. This approach takes into account the effect of dowel support on the reaction of its adjacent shear reinforcement： the conditions for the various contributions of transverse reinforcements are better defined following a clear evaluation of the participation ratio of these reinforcements. Lateral resistances of confined masonry walls measured in full-scale tests and gleaned from the literature are compared and checked with resistances calculated using the present approach.

关键词： reinforcement columns confined reinforced walls Shear formulation panel participation herein

A new SINS/GPS sensor fusion scheme for UAV localization problem using nonlinear SVSF with covariance derivation and an adaptive boundary layer

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Chinese Journal of Aeronautics 2016年第2期29卷 424-440页

作者： Fariz Outamazirt Fu Li Lin Yan abdelkrim Nemra School of Automation Science and Electrical Engineering Beihang University School of Control and Automation Ecole Militaire Polytechnique

The state estimation strategy using the smooth variable structure filter （SVSF） is based on the variable structure and sliding mode concepts. As presented in its standard form with a fixed boundary layer limit, the value of the boundary layer width is not precisely known at each step and may be selected based on a priori knowledge. The boundary layer width reflects the level of uncertainty in the model parameters and disturbance characteristics, where large values of the boundary layer width lead to robustness without optimality and small values of the boundary layer width provide optimality with poor robustness. As a solution and to overcome these limitations, an adaptive smoothing boundary layer is required to achieve greater robustness and suitable accuracy. This adapted value of the boundary layer width is obtained by minimizing the trace of the a posteriori covariance matrix. In this paper, the proposed new approach will be considered as another alternative to the extended Kalman filters （EKF）, nonlinear H∞ and standard SVSF-based data fusion techniques for the autonomous airborne navigation and self-localization problem. This alternative is based on strapdown inertial navigation system （SINS） and GPS data using the nonlinear SVSF with a covariance derivation and adaptive boundary layer width. Furthermore, the full mathematical model of the SINS/GPS navigation system considering the unmanned aerial vehicle （UAV） position, velocity and Euler angle as well as gyro and accelerometer biases will be used in this paper to estimate the airborne position and velocity with better accuracy.

关键词： Adaptive smoothing bound-ary layer Autonomous airborne navi-gation GPS Smooth variable structurefilter (SVSF) Strapdown inertial naviga-tion system (SINS)

Resilient Control for Networked Control Systems Subject to Cyber/Physical Attacks

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International Journal of Automation and computing 2018年第3期15卷 345-354页

作者： Taouba Rhouma Karim Chabir Mohamed Naceur abdelkrim Modeling Analysis and Control of Systems(MACS) Laboratory National Engineering School of Gabes (ENIG)University of Gabes

In this paper, we investigate a resilient control strategy for networked control systems（NCSs） subject to zero dynamic attacks which are stealthy false-data injection attacks that are designed so that they cannot be detected based on control input and measurement data. Cyber resilience represents the ability of systems or network architectures to continue providing their intended behavior during attack and recovery. When a cyber attack on the control signal of a networked control system is computed to remain undetectable from passive model-based fault detection and isolation schemes, we show that the consequence of a zero dynamic attack on the state variable of the plant is undetectable during attack but it becomes apparent after the end of the attack. A resilient linear quadratic Gaussian controller, having the ability to quickly recover the nominal behavior of the closed-loop system after the attack end, is designed by updating online the Kalman filter from information given by an active version of the generalized likelihood ratio detector.

关键词： Networked control systems (NCSs) cyber physical attacks Kahnan filtering resilient control anomaly detector.

Flow characterization and dilution effects of N_2 and CO_2 on premixed CH_4/air flames in a swirl-stabilized combustor

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Chinese Physics B 2014年第3期23卷 382-395页

作者：韩乐蔡国飙王海兴 Renou Bruno Boukhalfa abdelkrim School of Astronautics Beijing University of Aeronautics and Astronautics UMR 6614 CORIA INSA de Rouen Avenue de l’UniversitèBP08 76801 Saint-Etienne du Rouvray France

Numerically-aided experimental studies are conducted on a swirl-stabilized combustor to investigate the dilution effects on flame stability, flame structure, and pollutant emissions of premixed CH4/air flames. Our goal is to provide a systematic assessment on combustion characteristics in diluted regimes for its application to environmentally-friendly approaches such as biogas combustion and exhanst-gas recirculation technology. Two main diluting species, N2 and CO2, are tested at various dilution rates. The results obtained by means of optical diagnostics show that five main flame regimes can be observed for Nz-diluted flames by changing excess air and dilution rate. CO2-diluted flames follow the same pattern evolution except that all the domains are shifted to lower excess air. Both N2 and CO2 dilution affect the lean blow- out （LBO） limits negatively. This behavior can be counter-balanced by reactant preheating which is able to broaden the flammability domain of the diluted flames. Flame reactivity is degraded by increasing dilution rate. Meanwhile, flames are thickened in the presence of both diluting species. NOx emissions are significantly reduced with dilution and proved to be relevant to flame stability diagrams： slight augmentation in NOx emission profiles is related to transitional flame states where instability occurs. Although dilution results in increase in CO emissions at certain levels, optimal dilution rates can still be proposed to achieve an ideal compromise.

关键词： dilution effect premixed combustion swirl flow optical diagnostics

Adaptive high-order sliding mode control based on quasi-time delay estimation for uncertain robot manipulator

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Control Theory and Technology 2020年第3期18卷 279-292页

作者： Brahim BRAHMI Mark DRISCOLL Mohamed Hamza LARAKl abdelkrim BRAHMI Department of Mechanical Engineering Musculoskeletal Biomechanics Research Lab McGill UniversityMontrealCanada Department of Electrical Engineering University of QuebecMontrealCanada

This paper presents the design,and validation of a new adaptive control system based on quasi-time delay estimation(Q-TDE)augmented with new integral second-order terminal sliding mode control(ISOTSMC)for a manipulator robot with unknown dynamicuncertainty and *** to the conventional[TDE,the proposed Q-TDE becomes sufficient to invoke a fixed artficial time delay and utilize the past data only of the control input to approximate the unknown system's dynamic *** incorporating of new adaptive reachinglaw with ISOTSMCaugmented with Q-TDE policy ensures the continuous performance tracking of the robot manipulator's trajectories using output *** combination may achieve high performance with a significant chattering reducing *** utilizing the Lyapunov function theory,it can be demonstrated that the robot system is stable and all signals in closed-loop are converging in finite ***,Simulation and comparative studies with two degrees of freedom robot manipulator were carried out to validate the effectiveness of the designed control scheme.

关键词： Second-order sliding mode quasi-time delay estimation(Q-TDE) adaptive reaching law

Optoelectronic properties of SnO2 thin films sprayed at different deposition times

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Chinese Physics B 2016年第4期25卷 296-302页

作者： Allag abdelkrim Saad Rahmane Ouahab Abdelouahab Attouche Hafida Kouidri Nabila Laboratoire de Physique des Couches Minces et Applications Universit de Biskra BP 145 RP 07000 Biskra Alg&ie

This article presents the elaboration of tin oxide （SnO2） thin films on glass substrates by using a home-made spray pyrolysis system. Effects of film thickness on the structural, optical, and electrical film properties are investigated. The films are characterized by several techniques such as x-ray diffraction （XRD）, atomic force microscopy （AFM）, ultraviolet- visible （UV-Vis） transmission, and four-probe point measurements, and the results suggest that the prepared films are uniform and well adherent to the substrates. X-ray diffraction （XRD） patterns show that SnO2 film is of polycrystal with cassiterite tetragonal crystal structure and a preferential orientation along the （110） plane. The calculated grain sizes are in a range from 32.93 nm to 56.88 nm. Optical transmittance spectra of the films show that their high transparency average transmittances are greater than 65% in the visible region. The optical gaps of SnO2 thin films are found to be in a range of 3.64 eV-3.94 eV. Figures of merit for SnO2 thin films reveal that their maximum value is about 1.15 x 10-4 Ω-1 at λ = 550 nm. Moreover, the measured electrical resistivity at room temperature is on the order of 10^-2 Ω.cm.

关键词： thin film SnO2 spray pyrolysis thickness properties

Effect of Water Quality on Heavy Metal Redistribution and Mobility in Polluted Agricultural Soils in a Semi-Arid Region

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Pedosphere 2019年第6期29卷 730-739页

作者： Rim AZOUZI abdelkrim CHAREF Lamia AYED Samia KHADHAR Laboratoire Géoressources Centre des Recherches et Technologies des EauxSoliman 8020(Tunisia) Laboratoire d’Analyse Traitement et Valorisation des Polluants de l’Environnement et des ProduitsFacultéde PharmacieRue AvicenneMonastir 5000(Tunisia)

Mornag Plain is a coastal area of the Mediterranean basin, which has undergone an agricultural industrial boom. The aim of this study was to investigate the different water qualities used for irrigation on heavy metal mobility in these polluted agricultural soils. The geo-accumulation indices for heavy metals (Ni, Cr, Pb, Cd, Cu, and Zn) revealed that industrial activities and used treated wastewater (TWW) contributed to soil pollution, and water irrigation always decreased this contamination. After long-term use of different water types, high perturbation of heavy metal redistribution has occurred. Groundwater use altered all heavy metal redistributions in the irrigated soil among various soil-solid and soil-solution fractions, as compared to the unirrigated soil. Slight acid water use transferred some metals from different solid phase components into water-soluble and exchangeable fractions. However, TWW use transformed some Ni, Cr, Cd, Cu, and Zn from water-soluble and exchangeable fractions to less labile fractions, particularly into organically bound fractions. Reuse of conventional water within the same soil decreased the whole soil redistribution index values, indicating tendency to return to the pattern of distribution of groundwater-irrigated soil.

关键词： Exchangeable fraction Geo-accumulation index Labile fraction Mobility factor Organically bound fraction Redistribution index Treated wastewater Water-soluble fraction

Acoustic radiation-free surface phononic crystal resonator for in-liquid low-noise gravimetric detection

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Microsystems & Nanoengineering 2021年第1期7卷 99-108页

作者： Feng Gao Amine Bermak Sarah Benchabane Laurent Robert abdelkrim Khelif College of Science and Engineering Hamad Bin Khalifa UniversityEducation CityDohaQatar Institut FEMTO-ST CNRSUniversitéde Bourgogne-Franche-ComteBesanconFrance

Acoustic wave resonators are promising candidates for gravimetric ***,they generally suffer from strong acoustic radiation in liquid,which limits their quality factor and increases their frequency *** article presents an acoustic radiation-free gravimetric biosensor based on a locally resonant surface phononic crystal(SPC)consisting of periodic high aspect ratio electrodes to address the above *** acoustic wave generated in the SPC is slower than the sound wave in water,hence it prevents acoustic propagation in the fluid and results in energy confinement near the electrode *** energy confinement results in a significant quality factor improvement and reduces frequency *** proposed SPC resonator is numerically studied by finite element analysis and experimentally implemented by an electroplating-based fabrication *** results show that the SPC resonator exhibits an in-liquid quality factor 15 times higher than a conventional Rayleigh wave resonator at a similar operating *** proposed radiation suppression method using SPC can also be applied in other types of acoustic wave ***,this method can serve as a general technique for boosting the in-liquid quality factor and sensing performance of many acoustic biosensors.

关键词： resonator Acoustic liquid