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Geochemistry of island arc assemblage in the Eastern Desert of Egypt and the role of Pan-African magmatism in crustal growth of the Arabian–Nubian Shield:A review

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Acta Geochimica 2024年第3期43卷 588-622页

作者： abdel-Aal Mabdel-karim Mohamed MHamdy Adel A.Surour Geology Department Faculty of ScienceZagazig UniversityZagazig 44519Egypt Geology Department Faculty of ScienceTanta UniversityTanta 31527Egypt Department of Geological Sciences Faculty of ScienceNew Galala City 43511Egypt Geology Department Faculty of ScienceCairo UniversityGiza 12613Egypt

Neoproterozoic island arc assemblage of the Arabian–Nubian Shield(ANS)in the Eastern Desert(ED)of Egypt comprises juvenile suites of metavolcanics(MV),large amounts of meta-sedimentary rocks(MS),and voluminous metagabbros-diorites(MGD)and syn-tectonic intrusions of older granitoids(OG).We report here the updates of these four rock units in terms of classification,distribution,chemical characteristics,geodynamic evolution,metamorphism,and *** addition,we discuss these integrated data to elucidate a reasonable and reliable model for crustal evolution in the *** main features of these rock units indicate their relation to each other and the geodynamic environment dominated by early immature oceanic island arcs to primitive continental *** information of the island arc metavolcanic and plutonic rocks(gabbros,diorites,tonalites,and granodiorites)furnish evidence of the genetic *** include proximity and a coeval nature in the field;all protolith magmas are subalkaline in nature following calc-alkaline series with minor tholeiitic affinities;common geochemical signature of the arc rocks and subduction-related magmatism;their similar enrichment in LREEs;and similar major element compositions with mafic melts derived from metasomatized mantle *** volcano-sedimentary and the OG rocks underwent multiphase deformation events whereas the MGD complexes deformed *** on the magmatic,sedimentological,and metamorphic evolutions constrained by geochronological data as well as the progressive evolutionary trend from extensional to compressional regimes,a possible gradual decrease in the subducted slab dip angle is the most infl uential in any geodynamic model for arc assemblage in the ED of Egypt.

关键词： Island arc assemblage Magmatism Crustal growth Neoproterozoic Arabian–Nubian Shield Eastern Desert Egypt

Performance Comparison of Hyper-V and KVM for Cryptographic Tasks in Cloud Computing

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Computers, Materials & Continua 2024年第2期78卷 2023-2045页

作者： Nader abdel karim Osama A.Khashan Waleed K.Abdulraheem Moutaz Alazab Hasan Kanaker Mahmoud E.Farfoura Mohammad Alshinwan Department of Intelligent Systems Faculty of Artificial IntelligenceAl-Balqa Applied UniversityAl-Salt1705Jordan Research and Innovation Centers Rabdan AcademyP.O.Box 114646Abu DhabiUnited Arab Emirates Department of Information Systems and Networks TheWorld Islamic Sciences and Education UniversityAmman11947Jordan Department of Cyber Security Isra UniversityAmman1162Jordan Faculty of Science and Information Technology Al-Zaytoonah University of JordanAmman11733Jordan Middle East University Research Unit Middle East UniversityAmman11831Jordan

As the extensive use of cloud computing raises questions about the security of any personal data stored there,cryptography is being used more frequently as a security tool to protect data confidentiality and privacy in the cloud environment.A hypervisor is a virtualization software used in cloud hosting to divide and allocate resources on various pieces of *** choice of hypervisor can significantly impact the performance of cryptographic operations in the cloud *** important issue that must be carefully examined is that no hypervisor is completely superior in terms of performance;Each hypervisor should be examined to meet specific *** main objective of this study is to provide accurate results to compare the performance of Hyper-V and Kernel-based Virtual Machine(KVM)while implementing different cryptographic algorithms to guide cloud service providers and end users in choosing the most suitable hypervisor for their cryptographic *** study evaluated the efficiency of two hypervisors,Hyper-V and KVM,in implementing six cryptographic algorithms:Rivest,Shamir,Adleman(RSA),Advanced Encryption Standard(AES),Triple Data Encryption Standard(TripleDES),Carlisle Adams and Stafford Tavares(CAST-128),BLOWFISH,and *** study’s findings show that KVM outperforms Hyper-V,with 12.2%less Central Processing Unit(CPU)use and 12.95%less time overall for encryption and decryption operations with various file *** study’s findings emphasize how crucial it is to pick a hypervisor that is appropriate for cryptographic needs in a cloud environment,which could assist both cloud service providers and end *** research may focus more on how various hypervisors perform while handling cryptographic workloads.

关键词： Cloud computing performance virtualization hypervisors Hyper-V KVM cryptographic algorithm

The use of carbon nanomaterials in membrane distillation membranes:a review

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Frontiers of Chemical Science and Engineering 2021年第4期15卷 755-774页

作者： Sebastian Leaper Ahmed abdel-karim Patricia Gorgojo Department of Chemical Engineering and Analytical Science School of EngineeringThe University of ManchesterManchesterM139PLUK Water Pollution Research Department National Research CentreGiza 12622Egypt

Membrane distillation(MD)is a thermal-based separation technique with the potential to treat a wide range of water types for various applications and *** challenges remain however,which prevent it from becoming commercially widespread including moderate permeate flux,decline in separation performance over time due to pore wetting and high thermal energy ***,its attractive characteristics such as high rejection(ca.100%)of nonvolatile species,its ability to treat highly saline solutions under low operating pressures(typically atmospheric)as well as its ability to operate at low temperatures,enabling waste-heat integration,continue to drive research interests *** particular interest is the class of carbon-based nanomaterials which includes graphene and carbon nanotubes,whose wide range of properties have been exploited in an attempt to overcome the technical challenges that MD *** low dimensional materials exhibit properties such as high specific surface area,high strength,tuneable hydrophobicity,enhanced vapour transport,high thermal and electrical conductivity and *** use in MD has resulted in improved membrane performance characteristics like increased permeability and reduced fouling *** have also enabled novel membrane capabilities such as in-situ fouling detection and localised heat *** this review we provide a brief introduction to MD and describe key membrane characteristics and fabrication *** then give an account of the various uses of carbon nanomaterials for MD applications,focussing on polymeric membrane *** research directions based on the findings are also suggested.

关键词： carbon nanomaterials graphene membrane distillation desalination carbon nanotubes

Petrology and Geochemistry of Some Ophiolitic Metaperidotites from the Eastern Desert of Egypt:Insights into Geodynamic Evolution and Metasomatic Processes

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Acta Geologica Sinica(English Edition) 2021年第4期95卷 1139-1157页

作者： abdel-Aal M.abdel-karim Mokhles K.AZER Shaimaa A.EL-SHAFEI Geology Department Faculty of ScienceZagazig UniversityZagazig 44519Egypt Geological Sciences Department National Research Centre12622-DokkiCairoEgypt

Ophiolitic peridotites exposed in the Eastern Desert(ED)of Egypt record multiple stages of evolution,including different degrees of partial melting and melt extraction,serpentinization,carbonatization and *** present study deals with metaperidotites at two selected localities in the central and southern ED,namely Wadi El-Nabáand Wadi Ghadir,*** represent residual mantle sections of a Neoproterozoic dismembered ophiolite that tectonically emplaced over a volcano-sedimentary succession that represents island–arc *** studied metaperidotites are serpentinized,with the development of talc-carbonate and quartz-carbonate rocks,especially along shear and fault *** relics of primary minerals(olivine,orthopyroxene and Cr-spinel)are preserved in a few samples of partiallyserpentinized *** of the Cr-spinel crystals have fresh cores followed by outer zones of ferritchromite and Crmagnetite,which indicates that melt extraction from the mantle protolith took place under oxidizing *** protoliths of the studied metaperidotites were dominated by harzburgites,which is supported by the abundance of mesh and bastite textures in addition to some evidence from mineral and whole-rock chemical *** high Cr#(0.62–0.69;Av.0.66)and low TiO_(2)(<0.3 wt%)contents of the fresh Cr-spinels,the higher Fo(89–92;Av.91)and NiO(0.24–0.54 wt%,Av.0.40)contents of the primary olivine relics,together with the high Mg#(0.91–0.93;Av.91)and low CaO,Al2 O3 and TiO_(2)of the orthopyroxene relics,are all comparable with depleted to highly depleted forearc harzburgite from a suprasubduction zone *** investigated peridotites have suffered subsequent phases of metasomatism,from oceanfloor hydrothermal alteration(serpentinization)to magmatic hydrothermal *** enrichment of the studied samples in light rare earth elements(LREEs)relative to the heavy ones(HREEs)is attributed to most probably be due to the contamination

关键词： ophiolitic metaperidotites partial melting melt extraction geodynamic evolution Eastern Desert Egypt

CONTINUUM TOPOLOGY OPTIMIZATION FOR MONOLITHIC COMPLIANT MECHANISMS OF MICRO-ACTUATORS

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Acta Mechanica Solida Sinica 2006年第1期19卷 58-68页

作者： Luo Zhen Du Yixian Chen Liping Yang Jingzhou karim abdel-Malek School of Mechanical Science ＆ Engineering Huazhong University of Science and Technology Wuhan 430074 China Center for Computer-Aided Design Mechanical Engineering Research Facility The University of Iowa Iowa City IA 52246 USA

A multi-objective scheme for structural topology optimization of distributed compliant mechanisms of micro-actuators in MEMS condition is presented in this work, in which mechanical flexibility and structural stiffness are both considered as objective functions. The compliant micro-mechanism developed in this way can not only provide sufficient output work but also have sufficient rigidity to resist reaction forces and maintain its shape when holding the work-piece. A density filtering approach is also proposed to eliminate numerical instabilities such as checkerboards, mesh-dependency and one-node connected hinges occurring in resulting mechanisms. SIMP is used as the interpolation scheme to indicate the dependence of material modulus on element-regularized densities. The sequential convex programming method, such as the method of moving asymptotes （MMA）, is used to solve the optimization problem. The validation of the presented methodologies is demonstrated by a typical numerical example.

关键词： structural optimization topology optimization compliant mechanisms microactuators filtering approach convex programming

Real-Time Optimal Reach-Posture Prediction in a New Interactive Virtual Environment

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Journal of Computer Science & Technology 2006年第2期21卷 189-198页

作者：杨景周 R. Timothy Marler Steven Beck karim abdel-Malek Joo Kim US Army Virtual Soldier Research (VSR) Program Center for Computer-Aided Design The University of Iowa 111 Engineering Research Facility Iowa City IA 52242-1000 U.S.A.

Human posture prediction is a key factor for the design and evaluation of workspaces, in a virtual environment using virtual humans. This work presents a new interface and virtual environment for the direct human optimized posture prediction （D-HOPP） approach to predicting realistic reach postures of digital humans, where reach postures entail the use of the torso, arms, and neck. D-HOPP is based on the contention where depending on what type of task is being completed, and human posture is governed by different human performance measures. A human performance measure is a physics-based metric, such as energy or discomfort, and serves as an objective function in an optimization formulation. The problem is formulated as a single-objective optimization （SO0） problem with a single performance measure and as multiobjective-optimization （MOO） problem with multiple combined performance measures. We use joint displacement, change in potential energy, and musculoskeletal discomfort as performance measures. D-HOPP is equipped with an extensive yet intuitive user-interface, and the results are presented in an interactive virtual environment.

关键词： reach posture prediction MOO human modeling and simulation virtual environment

Mineralogy,Chemical Characteristics and Upgrading of Beach Ilmenite of the Top Meter of Black Sand Deposits of the Kafr Al-Sheikh Governorate,Northern Egypt

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Acta Geologica Sinica(English Edition) 2017年第4期91卷 1326-1338页

作者： abdel-Aal M. abdel-karim Mohamed I. MOUSTAFA Adel H. EI-AFANDY Mohamed G. BARAKAT Faculty of Science Zagazig University Egypt Engineering Colleges Northern Border University Saudi Arabia Nuclear Materials Authority P. O. Box 530 Maadi Cairo Egypt

Egyptian beach ilmenite occurs in a relatively high content in the naturally highly concentrated superficial black sand deposits at specific beach zones in the northern parts of the Nile Delta at Rosetta. Microscopic study shows that the ilmenite occurs as fresh homogeneous black or heterogeneous multicoloured altered grains and exhibits three types （homogeneous, exsolved and altered） of ilmenite varieties. XRD data of ilmenite indicates their association with minor hematite and quartz, whereas leucoxene shows its association with Nb-rutUe, pseudorutile and hematite. Grain size distribution suggests a very fine sand size of 〉89% and 80% and a fine sand size of 10.5% and 18.3% for fresh and altered ilmenites, respectively. The density of fresh, altered ilmenite and leucoxene concentrates varies from 2.70, 2.50 to 2.40 ton/m^3, suggesting a gradual decrease from high grade fresh to leucoxene and consistent with variation in magnetic susceptibility as a consequence of the leaching of iron. Mass magnetic susceptibility reveals 97.6% of ilmenite and 92% of the altered form are obtained at 0.20 and 0.48 ampere. Fresh iimenite exhibits variable TiO2 （47.18%） and Fe2O3^T （46.10%） with minor MnO, MgO and Cr2O3 （1.22, 1.10 and 0.51%）. The altered ilmenite is higher in TiO2 （76.16%） and SiO2 （4.68%） and lower in Fe2O3^T （14.45%）, MnO, MgO and Cr2O3 （0.39, 0.52 and 0.11%） compared with the fresh form. Three concentrates of ilmenites （G1, G2 and G3） were prepared from crude ore using a Reading cross belt magnetic separator under different conditions, revealing a gradual increase of TiO2, SiO2, Al2O3 and CaO accompanied by a decrease of Fe2O3^T, MgO and Cr2O3 with repetition of the separation processes. Several ore dressing techniques were carried out to upgrade the iimenite concentrate.

关键词： Beach ilmenite mineralogy chemistry upgrading Northern Egypt

Reach Envelope of Human Extremities

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Tsinghua Science and Technology 2004年第6期9卷 653-666页

作者：杨景周张云清陈立平 abdel-MALEK karim Center for Computer-Aided Design University of Iowa Iowa City IA 52242-1000 USA Center for Computer Aided Design Huazhong University of Science and Technology Wuhan 430074 China

Significant attention in recent years has been given to obtain a better understanding of human joint ranges, measurement, and functionality, especially in conjunction with commands issued by the central nervous system. While researchers have studied motor commands needed to drive a limb to follow a path trajectory, various computer algorithms have been reported that provide adequate analysis of limb modeling and motion. This paper uses a rigorous mathematical formulation to model human limbs, understand their reach envelope, delineate barriers therein where a trajectory becomes difficult to control, and help visualize these barriers. Workspaces of a typical forearm with 9 degrees of freedom, a typical finger modeled as a 4-degree-of-freedom system, and a lower extremity with 4 degrees of freedom are discussed. The results show that using the proposed formulation, joint limits play an important role in distinguishing the barriers.

关键词： human extremities degree of freedom biomechanics barriers

Effect of Zn/Mg ratio on cathodic protection of carbon steel using Al-Zn-Mg sacrificial anodes

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Transactions of Nonferrous Metals Society of China 2020年第8期30卷 2067-2078页

作者： Mosaad SADAWY Saad SAAD Randa abdel-karim Department of Mining and Petroleum Engineering Faculty of EngineeringNasr CityAl-Azhar UniversityCairo 11371Egypt Department of Metallurgy Faculty of EngineeringCairo UniversityGiza 12613Egypt

Al-Zn-Mg alloys with different Zn/Mg mass ratios were evaluated as sacrificial anodes for cathodic protection of carbon steel in 3.5 wt.%Na Cl *** anodes were fabricated from pure Al,Zn and Mg metals using casting *** microscopy,SEM-EDS,XRD and electrochemical techniques were *** results indicated that with decreasing Zn/Mg mass ratio,the grain size ofα(Al)and the particle size of the precipitates decreased while the volume fraction of the precipitates *** anode with Zn/Mg mass ratio>4.0 exhibited the lowest corrosion rate,while the anode with Zn/Mg mass ratio<0.62 gave the highest corrosion rate and provided the highest cathodic protection efficiency for carbon steel(AISI 1018).Furthermore,the results showed that the anode with Zn/Mg mass ratio<0.62 exhibited a porous corrosion product compared to the other anodes.

关键词： cathodic protection Al-Zn-Mg sacrificial anode current capacity passive film precipitate grain size