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Pseudo-static stability analysis of rock slopes reinforced by passive bolts using the generalized Hoek-Brown criterion

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第4期9卷 659-670页

作者： mounir Belghali Zied Saada Denis Garnier Samir Maghous Laboratoire de Génie Civil ENIT Université de Tunis El Manar Tunis Tunisia Université Paris-Est Laboratoire Navier (UMR8205) ENPC-IFSTTAR-CNRS Marne-la-Vallée France Department of Civil Engineering Federal University of Rio Grande do Sul Av. Osvaldo Aranha 99 Porto Alegre RS 90350-190 Brazil

The stability analysis of passive bolt-reinforced rock slopes under seismic loads is investigated within the framework of the kinematic approach of limit analysis theory.A pseudo-static method is adopted to account for the inertial forces induced in the rock mass by seismic *** strength properties of the rock material are described by a modified Hoek-Brown strength criterion,whereas the passive bolts are modeled as bar-like inclusions that exhibit only resistance to tensile-compressive *** advantage of the ability to compute closed-form expressions for the support functions associated with the modified Hoek-Brown strength criterion,a rotational failure mechanism is implemented to derive rigorous lower bound estimates for the amount of reinforcement strength to prevent slope *** approach is then applied to investigating the effects of relevant geometry,strength and loading parameters in light of a preliminary parametric *** accuracy of the approach is assessed by comparison of the lower bound estimates with finite element limit analysis solutions,thus emphasizing the ability of the approach to properly predict the stability conditions and to capture the essential features of deformation localization ***,the extension of the approach to account for slipping at the interface between reinforcements and surrounding rock mass is outlined.

关键词： Reinforced rock slope Modified Hoek-Brown criterion Seismic loading Limit analysis Rotational failure mechanism

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A coal rib monitoring study in a room-and-pillar retreat mine

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International Journal of Mining Science and Technology 2021年第1期31卷 127-135页

作者： Gamal Rashed khaled Mohamed Robert Kimutis GCB/PMRD//NIOSH/CDC PittsburghPA 15236USA

The National Institute for Occupational Safety and Health(NIOSH)conducted a comprehensive monitoring program in a room-and-pillar mine located in Southern *** deformation and the stress change in an instrumented pillar were monitored during the progress of pillar retreat mining at two sites of different geological conditions and depths of *** main objectives of the monitoring program were to better understand the stress transfer and load shedding on coal pillars and to quantify the rib deformation due to pillar retreat mining;and to examine the effect of rib geology and overburden depth on coal rib *** instrumentation at both sites included pull-out tests to measure the anchorage capacity of rib bolts,load cells mounted on rib bolts to monitor the induced loads in the bolts,borehole pressure cells(BPCs)installed at various depths in the study pillar to measure the change in vertical pressure within the pillar,and roof and rib extensometers installed to quantify the vertical displacement of the roof and the horizontal displacement of the rib that would occur during the retreat mining *** outcome from the monitoring program provides insight into coal pillar rib support optimization at various depths and geological ***,this study contributes to the NIOSH rib support database in U.S coal mines and provides essential data for rib support design.

关键词： Coal rib performance Coal rib design Coal rib monitoring Coal rib failure Load transfer Retreat mining

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Physical modeling and visualization of soil liquefaction under high confining stress

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Earthquake Engineering and Engineering Vibration 2005年第1期4卷 47-57页

作者： Lenart González Tarek Abdoun Mourad zeghal Vivian Kallou Michael K.Sharp Dept.of Civil and Environmental Engineering Rensselaer Polytechnic Inst.(RPI)TroyNYUSA Mueser Rutledge Consulting Engineers 225 W 34th StreetNew YorkNYUSA US Army Engineer Research and Development Center VicksburgMSUSA

The mechanisms of seismically-induced liquefaction of granular soils underhigh confining stresses are still not fully *** of these mechanisms is generallybased on extrapolation of observed behavior at shallow *** centrifuge model tests wereconducted at RPI's experimental facility to investigate the effects of confining stresses on thedynamic response of a deep horizontal deposit of saturated *** was observed at highconfining stresses in each of the tests.A system identification procedure was used to estimate theassociated shear strain and stress time *** histories revealed a response marked byshear strength degradation and dilative *** recorded accelerations and pore pressures wereemployed to generate visual animations of the *** visualizations revealed a liquefactionfront traveling downward and leading to large shear strains and isolation of upper soil layers.

关键词： centrifuge modeling high confining stress liquefaction system identification visualization

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Exact solutions for nonlinear partial fractional differential equations

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Chinese Physics B 2012年第11期21卷 32-38页

作者： khaled A.Gepreel Saleh Omran Mathematics Department Faculty of ScienceZagazig University Mathematics Department Faculty of ScienceTaif University Mathematics Department Faculty of scienceSouth Valley University

′In this article, we use the fractional complex transformation to convert nonlinear partial fractional differential equations to nonlinear ordinary differential equations. We use the improved （G′/G）-expansion function method to calculate the exact solutions to the time- and space-fractional derivative foam drainage equation and the time- and space-fractional derivative nonlinear KdV equation. This method is efficient and powerful for solving wide classes of nonlinear evolution fractional order equations.

关键词： fractional calculus complex transformation modified Riemann-Liouville derivative im- proved (G′/G)-expansion function method

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Influence of the layer parameters on the performance of the CdTe solar cells

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Optoelectronics Letters 2018年第2期14卷 98-103页

作者： Assiya Haddout Abderrahim Raidou mounir Fahoume Laboratory of1Condensed Matter Physics Department of Physics Faculty of Science Ibn Tofail University

Influence of the layer parameters on the performances of the CdTe solar cells is analyzed by SCAPS-1 D. The Zn O: Al film shows a high efficiency than SnO_2:F. Moreover, the thinner window layer and lower defect density of Cd S films are the factor in the enhancement of the short-circuit current density. As well, to increase the open-circuit voltage, the responsible factors are low defect density of the absorbing layer CdTe and high metal work function. For the low cost of cell production, ultrathin film CdTe cells are used with a back surface field(BSF) between CdTe and back contact, such as PbTe. Further, the simulation results show that the conversion efficiency of 19.28% can be obtained for the cell with 1-μm-thick CdTe, 0.1-μm-thick PbTe and 30-nm-thick CdS.

关键词： Influence of the layer parameters on the performance of the CdTe solar cells

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Experimental and Numerical Analyses of the Pull-out Response of a Steel Post/Bovine Bone Cementless Fixation

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Journal of Bionic Engineering 2012年第4期9卷 501-507页

作者： khaled Gammoudi Mohamed Kharrat Maher Dammak National Engineering School of Sfax Electromechanical Systems Laboratory Soukra road km 3.5 B.P. 1173 3038 Sfax Tunisia Higher Institute of Technological Studies of Gafsa University campus Sidi Ahmed Zarrouk 2112 Gafsa Tunisia Faculty of Sciences of Gafsa University campus Sidi Ahmed Zarrouk 2112 Gafsa Tunisia Preparatory Institute for Engineering Studies of Sfax Menzel Chaker Road Km 0.5 B.P. 1172 3018 Sfax Timisia

Effect of initial interference fit on pull-out strength in cementless fixation between bovine tibia and smooth stainless steel post was investigated in this study. Compressive behavior of bovine spongious bone was studied using mechanical testing in order to evaluate the elastic-plastic properties in different regions of the proximal tibia. Friction tests were carried out in the aim to evaluate the friction behavior of the contact between bovine spongious bone and stainless steel. A cylindrical stainless steel post inserted in a pre-drilled bovine tibia with an initial interference fit was taken as an in vitro model to assess the contribution of post fixation to the initial stability of the Total Knee Arthroplasty （TKA） tibial component. Pull-out experiments were carried out for different initial interference fits. Finite Element Models （FEM） using local elastic-plastic properties of the bovine bone were developed for the analysis of the experimental ultimate pull-out force results. At the post/bone interface, Coulomb friction was considered in the FEM calculations with pressure-dependent friction coefficient. It was found that the FEM results of the ultimate force are in good agreement with the experimental results. The analysis of the FEM interfacial stresses indicates that the micro-slip initiation depends on the local bone properties.

关键词： total knee arthroplasty bovine bone/steel post fixation interference fit puU-out strength FEM

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Effect of axial load and transverse reinforcements on the seismic performance of reinforced concrete columns

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Frontiers of Structural and Civil Engineering 2019年第4期13卷 831-851页

作者： mounir Ait BELKACEM Hakim BECHTOULA Nouredine BOURAHLA Adel Ait BELKACEM Department of Earthquake Engineering National Earthquake Engineering Research Centre (C.G.S) Algiers 16005 Algeria Department of Civil Engineering LGGC Laboratory Blida 1-University Blida 09000 Algeria Department of Civil Engineering Science & Technology University (USTHB) Algiers 16111 Algeria

The aim of this research is to assess the seismic performance of reinforced concrete columns under different axial load and transverse reinforcement ratios. These two parameters are very important as for the ductility, strength, stiffness, and energy dissipation capacity for a given reinforced concrete column. Effects of variable axial load ratio and transverse reinforcement ratio on the seismic performance of reinforced concrete columns are thoroughly analyzed. The finite element computer program Seismo-Structure was used to perform the analysis of series of reinforced concrete columns tested by the second author and other researchers. In order to reflect the reality and grasp the actual behavior of the specimens, special attention was paid to select the models for concrete, confined concrete, and steel components. Good agreements were obtained between the experimental and the analytical results either for the lateral force-drift relationships or for the damage progress prediction at different stages of the loading.

关键词： reinforced concrete columns axial load transverse reinforcement ductility

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Enhanced Parallelized DNA-Coded Stream Cipher Based on Multiplayer Prisoners’Dilemma

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Computers, Materials & Continua 2023年第5期75卷 2685-2704页

作者： khaled M.Suwais Faculty of Computer Studies Arab Open UniversityRiyadh11681Saudi Arabia

Data encryption is essential in securing exchanged data between connected *** is the process of transforming readable text into scrambled,unreadable text using secure *** ciphers are one type of an encryption algorithm that relies on only one key for decryption and as well as *** existing encryption algorithms are developed based on either a mathematical foundation or on other biological,social or physical *** technique is to utilise the behavioural aspects of game theory in a stream *** this paper,we introduce an enhanced Deoxyribonucleic acid(DNA)-coded stream cipher based on an iterated n-player prisoner’s dilemma *** main goal is to contribute to adding more layers of randomness to the behaviour of the keystream generation process;these layers are inspired by the behaviour of multiple players playing a prisoner’s dilemma *** implement parallelism to compensate for the additional processing time that may result fromadding these extra layers of *** results show that our enhanced design passes the statistical tests and achieves an encryption throughput of about 1,877 Mbit/s,which makes it a feasible secure stream cipher.

关键词： Encryption game theory DNA cryptography stream cipher parallel computing

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Impact of lateral force-resisting system and design/construction practices on seismic performance and cost of tall buildings in Dubai, UAE

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Earthquake Engineering and Engineering Vibration 2013年第3期12卷 385-397页

作者： Mohammad AlHamaydeh khaled Galal Sherif Yehia Department of Civil Engineering American University of SharjahSharjah UAE Department of Building Civil & Environmental Engineering Concordia UniversityMontréal Québec Canada

The local design and construction practices in the United Arab Emirates （UAE）, together with Dubai＇s unique rate of development, warrant special attention to the selection of Lateral Force-Resisting Systems （LFRS）. This research proposes four different feasible solutions for the selection of the LFRS for tall buildings and quantifies the impact of these selections on seismic performance and cost. The systems considered are： Steel Special Moment-Resisting Frame （SMRF）, Concrete SMRF, Steel Dual System （SMRF with Special Steel Plates Shear Wall, SPSW）, and Concrete Dual System （SMRF with Special Concrete Shear Wall, SCSW）. The LFRS selection is driven by seismic setup as well as the adopted design and construction practices in Dubai. It is found that the concrete design alternatives are consistently less expensive than their steel counterparts. The steel dual system is expected to have the least damage based on its relatively lesser interstory drifts. However, this preferred performance comes at a higher initial construction cost. Conversely, the steel SMRF system is expected to have the most damage and associated repair cost due to its excessive flexibility. The two concrete alternatives are expected to have relatively moderate damage and repair costs in addition to their lesser initial construction cost.

关键词： special moment-resisting frames (SMRF) special shear wall Dubai, UAE seismicity steel concrete dual system

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Occurrence and ecotoxicological risk assessment of pesticides in sediments of the Rosetta branch,Nile River, Egypt

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Journal of Environmental Sciences 2022年第8期34卷 21-31页

作者： Fawzy Eissa Mahmoud Al-Sisi khaled Ghanem Environment and Bio-agriculture Department Faculty of AgricultureAl-Azhar UniversityNasr CityCairo 11884Egypt Central Laboratory of Residue Analysis of Pesticides and Heavy Metals in Food(QCAP) Agricultural Research CenterDokkiGiza 12311Egypt

This study aimed to(1) monitor the occurrence and spatiotemporal variations of 100 pesticides in sediments collected monthly from July 2018 to June 2019 from sampling sites in El-Rahawy, Sabal, and Tala, along the Rosetta branch of the Nile River, Egypt, and(2) perform an ecological risk assessment for aquatic organisms upon exposure to the detected sediment pesticides based on the risk quotient(RQ) method. Out of the 100 pesticides monitored, 16 pesticides belonging to seven chemical families were detected, and 55% of the sediment samples were contaminated with one or more pesticide residues. The mean concentration(mg/kg dry weight(dw)) and detection frequency(%) of the four most frequently detected pesticides in the sediment samples were as follows: chlorpyrifos(0.18 mg/kg dw and 34%), p,p-DDE(0.018 mg/kg dw and 30%), cypermethrin(0.03 mg/kg dw and 14%), and deltamethrin(0.026 mg/kg dw and 13%). The spatial distribution exhibited that El-Rahawy had the highest pesticide load(2.86 mg/kg dw) among the studied sites, whereas the temporal variations revealed that the highest total pesticide concentrations were detected in winter season(1.73 mg/kg dw). Meanwhile, 12 pesticides showed high RQs(>1), posing a potential ecological risk to aquatic species that live and feed on such sediments.

关键词： Pesticide residues Sediments Spatiotemporal variations Risk quotient

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