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Finite element analysis of slope stability by expanding the mobilized principal stress Mohr's circles-Development, encoding and validation

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第4期14卷 1165-1179页

作者： djillali Amar Bouzid Department of Civil Engineering Faculty of TechnologyUniversity of Blida 1Blida09000Algeria

In recent years,finite element analysis is increasingly being proposed in slope stability problems as a competitive method to traditional limit equilibrium methods(LEMs)which are known for their inherent ***,the application of finite element method(FEM)to slope stability as a strength reduction method(SRM)or as finite element limit analysis(FELA)is not always a success for the drawbacks that characterize both *** increase the performance of finite element analysis in this problem,a new approach is proposed in this *** consists in gradually expanding the mobilized stress Mohr’s circles until the soil failure occurs according to a prescribed non-convergence *** present approach called stress deviator increasing method(SDIM)is considered rigorous for three main ***,it preserves the definition of the factor of safety(FOS)as the ratio of soil shear strength to the mobilized shear ***,it maintains the progressive development of shear stress resulting from the increase in the principal stress deviator on the same plane,on which the shear strength takes ***,by introducing the concept of equivalent stress loading,the resulting trial stresses are checked against the violation of the actual yield criterion formed with the real strength parameters rather than those reduced by a trial *** new numerical procedure was encoded in a Fortran computer code called S^(4)DINA and verified by several *** with other numerical methods such as the SRM,gravity increasing method(GIM)or even FELA by assessing both the FOS and contours of equivalent plastic strains showed promising results.

关键词： Slope stability,Finite element analysis Strength reduction method(SRM),Stress point-based factor of safety(FOS),Limit equilibrium method(LEM),Stress deviator Mohr’s circle,Plastic strain

Sequential extraction of Cs and Sr from Ain Oussera soils around Es-Salam research reactor facility

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Journal of Environmental Sciences 2015年第10期27卷 163-172页

作者： Abdelkader Bouzidi Abderrahmane Ararem djillali Imessaoudene Benalia Yabrir Centre de Recherche Nucléaire de Birine 17200 Ain OusseraAlgeria Laboratory of Exploration and Valorization of Steppic Ecosystems University of Djelfa

Four types of undisturbed soil in Ain Oussera region around the Es-Salam reactor facility,located in the south of Algiers, Algeria, at about 200 km, were artificially contaminated for one year with stable CsCl and SrCl2 in order to simulate an accidental release of these elements. This study was performed using sequential extraction procedure based on Shultz method and containing six fractions. The selectivity of the extraction protocol was confirmed by analyzing some elements（Ca, C, Fe, Mn, Si and Al） designed as indicators of the targeted phases. The obtained results showed an acceptable reproducibility, in view of the coefficients of variation that were in most cases less than 15%. The results revealed a clear proportional correlation between the extracted Cs and Sr in fractions for each soil and some of soils physicochemical properties. Organic matter appears to play an important role in the soil retention, particularly for Cs where the extracted percentage exceeds to 30% in whole soils. In contrast, strontium expresses a remarkable affinity for the fraction bound to carbonates. The obtained data also indicate that the availability of Cs in the four soils is less important compared to Sr availability. This is illustrated by the higher value of extracted Sr in the easily extractible phase, including the water-soluble and the exchangeable fraction.

关键词： Ain Oussera soils CsCl SrCl2 Sequential extraction Selectivity

Influence of Discretization Step on Asymptotic Stability of a Certain Class of Two-dimensional Continuous-discrete Fractional Linear Systems

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Acta Mathematicae Applicatae Sinica 2022年第1期38卷 68-77页

作者： Souad BOUGUESSA djillali BOUAGADA Mohammed Amine GHEZZAR Department of Mathematics and Computer Science ACSY Team-Laboratory of Pure and Applied Mathe-maticsAbdelhamid Ibn Badis University MostaganemP.O.Box 227/118University of Mostaganem27000 MostaganemAlgeria

The effectiveness of this paper lies in the influence of the discretization step on the asymptotic stability of the positive two-dimensional fractional linear *** aims at investigating whether,how and when this step affects the asymptotically stable two-dimensional positive fractional linear continuous-discrete *** accomplish this study,a new test was outlined and used so that the asymptotic stability of the system was measured both before and after being exposed to the sampling ***,the conditions of that stability were *** a result,the outcome of the approximation shows that the stability is preserved under a particular set of *** this basis,the newly proposed approach is recommended for testing the intended stability of such systems.A numerical example is tested to show the accuracy and the applicability of the proposed tests.

关键词： discretization positivity stability two-dimensional systems

Assessment of natural frequency of installed offshore wind turbines using nonlinear finite element model considering soil-monopile interaction

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第2期10卷 333-346页

作者： djillali Amar Bouzid Subhamoy Bhattacharya Lalahoum Otsmane Department of Civil Engineering Faculty of Technology University Saad Dahled of Blida Department of Civil and Environmental Engineering Tomas Telford Building University of Surrey Department of Material Engineering Faculty of Sciences and TechnologyUniversity of Médéa

A nonlinear finite element model is developed to examine the lateral behaviors of monopiles, which support offshore wind turbines(OWTs) chosen from five different offshore wind farms in Europe. The simulation is using this model to accurately estimate the natural frequency of these slender structures, as a function of the interaction of the foundations with the subsoil. After a brief introduction to the wind power energy as a reliable alternative in comparison to fossil fuel, the paper focuses on concept of natural frequency as a primary indicator in designing the foundations of OWTs. Then the range of natural frequencies is provided for a safe design purpose. Next, an analytical expression of an OWT natural frequency is presented as a function of soil-monopile interaction through monopile head springs characterized by lateral stiffness KL, rotational stiffness KRand cross-coupling stiffness KLRof which the differences are discussed. The nonlinear pseudo three-dimensional finite element vertical slices model has been used to analyze the lateral behaviors of monopiles supporting the OWTs of different wind farm sites considered. Through the monopiles head movements(displacements and rotations), the values of KL, KRand KLRwere obtained and substituted in the analytical expression of natural frequency for comparison. The comparison results between computed and measured natural frequencies showed an excellent agreement for most cases. This confirms the convenience of the finite element model used for the accurate estimation of the monopile head stiffness.

关键词： Nonlinear finite element analysis Vertical slices model Monopiles under horizontal loading Natural frequency Monopile head stiffness Offshore wind turbines(OWTs)

Displacement damage cross section and mechanical properties calculation of an Es-Salam research reactor aluminum vessel

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Nuclear Science and Techniques 2017年第11期28卷 217-225页

作者： djillali Saad Hocine Benkharfia Mahmoud Izerrouken Ahmed Ali Benyahia Hamid Ait-Abderrahim Department of nuclear materials and mechanical test Nuclear Research Center of Birine BP 180 17200 Ain-OusseraAlgeria Reactor Physics Department Nuclear Research Center of Birine BP 180 17200 Ain-Oussera Algeria Reactor Physics Department Nuclear Research Center of Draria BP 43 Sebala 16050 Draria Algeria Advanced Mechanics Laboratory University of Sciences and Technology Houari Boumediene BP 32 El Alia16111 Bab Ezzouar Algeria SCK-CEN Belgian Nuclear Research Centre Boeretang 2002400 Mol Belgium

Nuclear facility aging is one of the biggest problems encountered in nuclear engineering. Radiation damage is among one of the aging causes. This kind of damage is an important factor of mechanical properties deterioration. The interest of this study is on the Es-Salam research reactor aluminum vessel aging due to neutron radiation. Monte Carlo(MC) simulations were performed by MCNP6 and SRIM codes to estimate the defects created by neutrons in the vessel. MC simulations by MCNP6 have been performed to determine the distribution of neutron fluence and primary knock-on atom(PKA) creation. Considering our boundary conditions of the calculations, the helium and hydrogen gas production in the model at a normalized total neutron flux of 6.62×10^(12) n/cm^2 s were determined to be 2.86 × 10~8 and 1.33 × 10~9 atoms/cm^3 s,respectively. The SRIM code was used for the simulation of defects creation(vacancies, voids) in the aluminum alloy of the Es-Salam vessel(EsAl) by helium and hydrogen with an approximate energy of 11 MeV *** coupling between the two codes is based upon postprocessing of the particle track(PTRAC) output file generated by the MCNP6. A small program based on the Mat Lab language is performed to condition the output file MCNP6 in the format of a SRIM input file. The concentration of silicon was determined for the vessel by the calculation of the total rate of ^(27)Al(n,γ)^(28)Si reaction. The DPA(displacement per atom) was calculated in SRIM according to R.E. Stoller recommendations; the calculated value is 0.02 at a fast neutron fluence 1.89 × 10^(19) n/cm^***-MRx standard for 6061-T6 aluminum was used for the simulation of the evolution of mechanical properties for high fluence. The calculated values of nuclear parameters and DPA obtained were in agreement with the experimental results from the Oak Ridge High Flux Isotope Reactor(HFIR) reported by Farrell and coworkers.

关键词： Radiation damage EsAl 6061-T6 Silicon production DPA PKA MCNP6 SRIM RCC-MRx HFIR

Corticosteroids for COVID-19

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Journal of Intensive Medicine 2021年第1期1卷 14-25页

作者： djillali Annane Department of Intensive Care Hôpital Raymond Poincare(APHP)Laboratory of Infection&Inflammation-U1173School of Medicine Simone VeilUniversity Versailles Saint Quentin-University Paris SaclayINSERM104 boulevard Raymond PoincareGarches 92380France

Coronavirus disease 19(COVID-19)is placing a major burden on healthcare,economy and social systems world-wide owing to its fast spread and unacceptably high death *** unprecedented research effort has established the role of a deregulated immune response to the severe acute respiratory syndrome coronavirus 2,resulting in systemic *** that,the immunomodulatory approach has been placed in the top list of the re-search agenda for *** have been used for more than 70 years to modulate the immune response in a broad variety of *** drugs have been shown to prevent and attenuate inflammation both in tissues and in circulation via non-genomic and genomic *** the bedside,numerous observational cohorts have been published in the past months and have been *** controlled trials with subsequent high quality meta-analyses have provided moderate to strong certainty for an increased chance of survival and relief from life supportive therapy with corticosteroids given at a dose of 6 mg per day dexametha-sone or equivalent doses of hydrocortisone or *** corticotherapy was not associated with an increased risk of bacterial infection or of delayed viral *** daily practice,physicians may be encouraged to use corticosteroids when managing patients with COVID-19 requiring oxygen supplementation.

关键词： Coronavirus Corticosteroids Inflammatory mediators Trials Survival Superinfections

Structural and Electronic Properties of Bixo<sub>3</sub>(X = Mn, Fe, Cr)

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Journal of Modern Physics 2011年第7期2卷 642-650页

作者： djillali Bensaid Nour-Eddine Benkhettou Ali Kourdassi Laboratoire des Materiaux Magnetiques Faculty of Sciences University of Sidi Bel Abbes

The candidate multiferroic BiCrO3 and its chemical neighbors BiMnO3 and BiFeO3 are known to be ferromagnetic and ferroelectric respectively. With structural distortions driven by the strongly polarizable Bi ions, we present results of the first-principles density functional calculations using the (FP-LMTO) method with the spin-orbit coupling for those materials in the pseudo-cubic perovskite phase. The results showed that the valence bands in these compounds are formed by the 6p orbitals of bismuth and 3d orbital’s of the transition metals. Our results indicate that these materials have metallic behavior for spin-up polarization but being a clear tandance for semiconductor spin-down BiMnO3.

关键词： Multiferroics Perovskite Density Functional Theory ABO3 Oxide Perovskites

Cardiac Decompensation after Dilatation of an Arteriovenous Fistula Stenosis: A Case Report

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Open Journal of Nephrology 2022年第4期12卷 369-374页

作者： Modou Ndongo Sid Ali Toufik Benyaghla Fabrice Tiako Mamadou Mouctar Diallo Misylias Bouaoud Houyem Attia Fatiha Lahouel djillali Ziane Berroudja Nestor Nankeu Tayeb Bensalem Catherine Albert Department of Nephrology Dialysis and Kidney Transplantation of Aristide Le Dantec hospital Dakar Senegal Department of Nephrology Dialysis of Louis Pasteur Hospital Chartres France

The arteriovenous fistula (AVF) has been considered for several decades as the preferred approach for hemodialysis because of its longevity and its lower morbidity and mortality rate. However, it can be the cause of several infectious and especially cardiovascular complications. Stenosis is the most common complication of AVF. It is favored by several hemodynamic, cellular and mechanical factors. Reduced dialysis performance and thrombosis are the main risks associated with stenosis. Intervention for dilation is indicated in the presence of any pre-thrombotic stenosis or stenosis that alters the quality of dialysis. However, in patients with heart disease, an assessment of the risk of decompensation is mandatory before considering any gesture of dilation of a fistula. We report a case of acute cardiac decompensation in an 85-year-old patient with severe but stable dilated cardiomyopathy after dilatation of an AVF stenosis. This observation shows that particular attention should be given to elderly subjects with AVF stenosis, especially in the presence of underlying heart disease where closure of the AVF with placement of a tunneled catheter is an alternative that should always be discussed.

关键词： Arteriovenous Fistula Stenosis Hyperflow Hemodialysis Cardiotoxic

Evaluation of the Therapeutic Management of Hypercalcemia in Myeloma at the Nephrology Department of Louis Pasteur Hospital of Chartres: About 8 Cases

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Open Journal of Nephrology 2022年第4期12卷 403-409页

作者： Modou Ndongo Babacar Ndiaye Nestor Nankeu Abou Sy Houyem Attia Fatiha Lahouel djillali Ziane Berroudja Tayeb Bensalem Sid Ali Toufik Benyaghla Catherine Albert Sidy Mohamed Seck El Hadji Fary Ka Department of Nephrology Dialysis and Kidney Transplantation of Aristide Le Dantec Hospital Dakar Senegal Department of Nephrology Dialysis of Louis Pasteur Hospital Chartres France Department of Nephrology Dialysis of Ouakam Military Hospital Dakar Senegal

Introduction: Hypercalcemia is the most common metabolic complication in myeloma. The aim of this study was to evaluate the management strategy of hypercalcemia in myeloma at the nephrology department of Louis Pasteur hospital of Chartres. Patients and Methods: We carried a retrospective study of patients treated for myeloma-related hypercalcemia between January 1, 2019 to December 31, 2021. The clinical, paraclinical, therapeutic and evolutive characteristics were studied. Results: Eight patients were included in this study with a median age of 67 years [41 - 85] and a sex ratio (M/F) of 1. A quarter of patients were known with chronic kidney disease. Four patients (50%) had symptoms of hypercalcemia. Biologically, the mean hemoglobin was 9.8 ± 2.7 g/dl, all patients had an acute kidney injury with a mean creatinine level of 364.1 ± 173.3 mmol/l, a mean serum calcium of 3.42 ± 0.59 mmol/l and three quarter of patients had bone lesions. Five patients (62.5%) were rehydrated with a mean volume of saline of 2700 ± 836.7 ml/24h. Seven patients (87.5%) received biphosphonates and none received diuretics. The mean normalization time of the serum calcium was 5 days. Conclusion: Hypercalcemia is frequent in malignancy and represents a poor prognosis factor of the disease. A well-conducted therapeutic strategy allows rapid normalization.

关键词： Hypercalcemia Myeloma Treatment Malignancy Neoplasia