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Plant assemblage and diversity variation with human disturbances in coastal habitats of the western Arabian Gulf

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Journal of Arid Land 2016年第5期8卷 787-798页

作者： Raafat h ABD el-WAhAB Botany Department Faculty of ScienceSuez Canal University Science Department Faculty of Basic EducationPublic Authority for Applied Education and Training

Knowledge about plant diversity along disturbance gradients is essential for conservation and management of fragmented coastal *** study examined the effects of human disturbance intensity in coastal habitats of Kuwait on diversity,composition,identity and assemblage of vascular plant *** survey data from 113 plots （5m×5m each） were randomly selected in 51 sites at coastal fragmented habitats at three levels of disturbance intensities （high,moderate and low） and were statistically *** results revealed that about 76% of the recorded species are considered threatened species in Kuwait,most of which are being lost in high disturbed *** led to the dominance of Zygophyllum qatarense,Cornulaca aucheri and Salsola imbricata,which are species of disturbance ***,total plant cover and species diversity were higher in moderate and low disturbed habitats than in high disturbed *** diversity between high and low disturbed habitats was higher than either between high and moderate,or between moderate and low disturbed *** analyses showed statistically significant differences in composition of plant assemblages,which indicate high beta diversity between the habitat *** urbanization and industrialization are among the most serious threats that contribute to declines in biological diversity and rapid fragmentation of coastal habitats in *** protective enclosures in the disturbed habitats,planting endangered and vulnerable species,and establishing a natural reserve at Nuwaiseeb are recommended conservation actions to avoid loss of the fragmented coastal habitats and to facilitate restoration of native plants.

关键词： plant diversity disturbance gradient threatened species habitat fragmentation coastal habitat salt marsh restoration

Radionuclides measurements and mineralogical studies on beach sands, East Rosetta Estuary, Egypt

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Chinese Journal Of Geochemistry 2013年第2期32卷 146-156页

作者： Abd el Wahab M. el Nahas h.A. Physics Department Faculty of Women for Arts Science and Education Ain Shams University Cairo P.O 11757 Egypt Nuclear Materials Authority Cairo P.O. Box 530 Egypt

Radiometric measurements were carried out for the beach sands from East Rosetta estuary to determine the activity concentrations of 238 U, 226 Ra, 232 Th, and 40 K, using a hyper Pure Germanium spectrometer, to estimate the dose rates and radiation hazard indices. The average specific activities are 778.20 Bq/kg for 238 U; 646.89 Bq/kg for 226 Ra; 621.92 and 627.85 Bq/kg for the 222 Rn daughters 214 Pb and 214 Bi respectively. The average specific activity of 232 Th is 1510.25 Bq/kg, while the calculated specific activity for 40 K has an average of 8.41 Bq/kg. The average specific activity of 235 U is 38.61 Bq/kg. The average absorbed dose rate is 1211.36 nGy/h, 20 times higher than the estimated average global primordial radiation of 60 nGy/h and 6 times higher than that of the world range (10-200 nGy/h). The radium equivalent (Ra eq ) values are from 6 to 9 times the recommended value. The internal and external hazard indices (h int , h ex ) indicate that their values are from 6 to 11 times the permissible values of these indices. These higher values may be due to the presence of economic heavy minerals containing radionuclides as zircon and monazite as well as some trace minerals, thorite and uranothorite. The mineralogical study indicates the beach sands contain heavy minerals, zircon, monazite, rutile, ilmenite, leucoxene, magnetite and garnet. The average abundance of zircon is 0.175 wt% ranging from 0.125 wt% to 0.239 wt%, while it is 0.004wt% ranging from 0.001 wt% to 0.007 wt% for monazite. The average abundance is 0.087 wt% for rutile; 2.029 wt% for ilmenite; 1.084 wt% for magnetite; 0.384 wt% for leucoxene and 0.295 wt% for garnet.

关键词：放射性核素海滩砂矿物学核素测量河口平均丰度埃及辐射测量

FIRST-ORDER METhODS FOR SOLVING ThE OPTIMAL STATIC h∞-SYNThESIS PROBLEM

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Journal of Computational Mathematics 2007年第6期25卷 672-689页

作者： el-Sayed M.E. Mostafa Department of Mathematics Faculty of Science Alexandria University Alexandria Egypt

In this paper, we consider the static output feedback （SOF） h∞-synthesis problem posed as a nonlinear semi-definite programming （NSDP） problem. Two numerical algorithms are developed to tackle the NSDP problem by solving the corresponding Karush- Kuhn-Tucker first-order necessary optimality conditions iteratively. Numerical results for various benchmark problems illustrating the performance of the proposed methods are given.

关键词： Static output feedback h∞-synthesis Semi-definite programming Nonlinear programming.

Dynamic stress concentration in an infinitely long cylindrical cavity due to a point spherical source embedded within a fluid-saturated poroelastic formation of infinite extent

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 139-156页

作者： h.hOSSEINI O.BALILAShAKI Department of Mechanical Engineering Faculty of EngineeringGolestan University

The effects of a harmonically exciting monopole source on an infinitely long cylindrical cavity embedded entirely within a fluid-saturated poroelastic formation of infinite extent are examined theoretically. It is assumed that the source is located outside the cavity at a specified distance from the borehole axis. The magnitudes of the hoop and radial stresses beside the pore pressures exerted on the interface and inside the porous medium surrounding the borehole are calculated and discussed. Biot's poroelastic modeling along with three types of boundary conditions for the cylindrical interface including the ideal fluid, empty borehole, and rigid inclusion with a hard boundary is employed for the analysis. Utilizing a proper translational addition theorem for expressing the incident spherical wave in terms of cylindrical wave expansions, the proposed boundary conditions at the interface are satisfied. Stresses are formulated by means of wave potential functions in a three-dimensional(3D) manner. The effects of the frequency and the radial distance between the source and borehole on the induced stresses are examined for the first cylindrical modes over frequency spectra. Two permeability conditions for the interface and three types of soils for the porous formation are considered throughout the analysis. To give an overall outline of the study, a numerical example is presented. The results clearly indicate that the distance is a key parameter and has considerable effects on the induced stress values. In addition, the interface permeability condition and soil characteristics play an important role in determining the dynamic response of the borehole. Finally,the obtained results are compared with the relevant analyses existing in the literature for some limit cases, and good agreement is achieved.

关键词： Stress concentration

First-principles prediction of the magnetism of 4f rare-earth-metal-doped wurtzite zinc oxide

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Journal of Rare Earths 2014年第8期32卷 715-721页

作者： A.G.el hachimi h.Zaari A.Benyoussef M.el Yadari A.el Kenz Laboratoire de Magnétisme et Physique des hautes Energies LMPHE (URAC 12) Département de Physique B.P.1014 Faculté des SciencesUniversité Mohammed V-Agdal Institut of Nanomaterials and Nanotechnology hassan II Academy of Science and Technology Department of Science Moulay Ismail University Faculté Polydisciplinaire

electronic structure and magnetic properties of wurtzite ZnO semiconductor doped with rare earth （RE=La, Ce, Pr, Pm, Nd, Sm, Eu, Gd, Tb, Dy, ho, Er, Tm and Yb） atoms were studied using spin-polarized density functional theory based on the full-potential linear augmented plane wave （FP-LAPW） method as implemented in the Wien2k code. In this approach the generalized gradient approximation （GGA） was used for the exchange-correlation （XC） potential. Our results showed that the substitution of RE ions in ZnO induced spins polarized localized states in the band gap. Moreover, the studied DMSs compounds retained half metallicity at dopant concentration x=0.625%for most of the studied elements, with 100%spin polarization at the Fermi level （EF）. The total magnetic moments of these compounds existed due to RE 4f states present at EF, while small induced magnetic moments existed on other non-magnetic atoms as well. Finally, the energy difference between far and near configurations was investigated. It was found that the room temperature ferromagnetism was possible for RE-doped ZnO at near configuration. Since the RE-RE separation was long enough （far configuration） for magnetic coupling, the system became paramagnetic or antiferromagnetic ground state.

关键词： ZnO rare earths ferromagnetism DMS electronic structure magnetic properties half-metallic RE-doped ZnO FP-LAPW method density functional theory

Effect of Pd or Ir on the catalytic performance of Mo/h-ZSM-5 during the non-oxidative conversion of natural gas to petrochemicals

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Journal of Natural Gas Chemistry 2008年第4期17卷 337-343页

作者： Ahmed K.Aboul-Gheit Ahmed E.Awadallah Salah M.el-Kossy Abdel-Lateef h.Mahmoud Process Development Division Egyptian Petroleum Research Institute Faculty of Science Department of ChemistryMNF University Ageeba Petroleum Co.

Natural gas conversion to petrochemicals, principally, benzene, naphthalene, toluene, as well as ethylene under non-oxidative conditions was examined in a fixed bed flow reactor at 700 ℃ and gaseous hourly space velocity （GhSV） of 1500 ml·g ^-1·h^-1 at time-on-stream ranging from 5 rain to 4 h using catalysts containing 6.0%Mo/h-ZSM-5 promoted with Pd or Ir metal. The catalysts were characterized by XRD, TPD, and TGA. The addition of Pd or Ir to 6%Mo/h-ZSM-5 catalyst promoted ethylene production but inhibited the cyclization reaction to aromatics owing to the strong interaction between these noble metals and the framework Al species, which were attached to the acid sites during the impregnation process. Coke deposition on the catalysts was found to decrease upon addition of 0.5wt% of Pd or Ir to 6%Mo/h-ZSM-5 catalyst owing to the hydrogenating activity of these metals.

关键词： natural gas methane benzene ethylene molybdenum Pd Ir h-ZSM-5

Vibration suppression of magnetostrictive laminated beams resting on viscoelastic foundation

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Applied Mathematics and Mechanics(English Edition) 2020年第8期41卷 1269-1286页

作者： A.M.ZENKOUR h.D.el-ShAhRANY Department of Mathematics Faculty of ScienceKing Abdulaziz UniversityJeddah 21589Saudi Arabia Department of Mathematics Faculty of ScienceKafrelsheikh UniversityKafrelsheikh 33516Egypt Department of Mathematics Faculty of ScienceBisha UniversityBisha 61922Saudi Arabia

The vibration suppression analysis of a simply-supported laminated composite beam with magnetostrictive layers resting on visco-Pasternak’s foundation is *** constant gain distributed controller of the velocity feedback is utilized for the purpose of vibration *** formulation of displacement field is proposed according to Euler-Bernoulli’s classical beam theory(ECBT),Timoshenko’s first-order beam theory(TFBT),Reddy’s third-order shear deformation beam theory,and the simple sinusoidal shear deformation beam ***’s principle is utilized to give the equations of motion and then to describe the vibration of the current *** on Navier’s approach,the solution of the dynamic system is *** effects of the material properties,the modes,the thickness ratios,the lamination schemes,the magnitudes of the feedback coefficient,the position of magnetostrictive layers at the structure,and the foundation modules are extensively studied and discussed.

关键词： vibration suppression laminated composite beam magnetostrictive material visco-Pasternak’s foundation

SUPPORTING AND SEPARATING SUBSETS FOR INVEX BODIES

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Acta Mathematica Scientia 2008年第4期28卷 818-822页

作者： h.K.el-Sayied Mathematics Department Faculty of ScienceTanta University

Invex bodies represent an important class of bodies which are considered as a generalization of convex *** this article,the author studies the supporting for this class of bodies as well as the separating subsets of t... 详细信息

关键词： Invex bodies focal points-supporting separating

Synthesis and reactions of 2-[α-(3,4-disubstituted phenacyl)-p-substituted styryl]-4h-3,1-benzoxazin-4-ones

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Chinese Journal of Chemistry 1996年第5期14卷 437-446页

作者： SOLIMAN,Ahmed Youssef ATTIA,Ibrahim Abd el-Mogoud SALEM,Moneer Abdu Ibrahim SOLIMAN,el-SayedAhmed GABER,Adel Mohy el-Deen Science Department Faculty of TeachersP.O.Box 2313Al Hasa31982Saudi Arabia Faculty of Engineering Ain Shames UniversityEgypt Chemistry Department Faculty of ScienceAin Shames UniversityEgypt

Conversion ofβ-aroyl propionic acids into furanone derivatives(2)and benzoxazinone derivatives(3)for the study of the reactivity of these nucleus towards different nucleophilic and elec-trophilic reagents.

关键词： Synthesis reaction beuzoxazinone derivatives