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Magnetic transitions and butterfly-shaped hysteresis of Sm-Fe-Al-based perovsk.te-type orthoferrite

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Journal of Rare Earths 2015年第9期33卷 965-971页

作者： M.A.ahmed N.G.Imam M.k.Abdelmak.oud Y.A.Saeid Materials Science Lab. Physics Department Faculty of Science Cairo University Materials Science Lab. Experimental Physics Department Nuclear Research Center Atomic Energy Authority

A1 doped SmFeO3 （SmFel_xmlxO3; 0.0〈x〈0.15; step 0.05） were prepared by double sintering ceramic technique. The obtained samples were crystallized in single phase structure except the sample with x=0.15. The unit cell volume was found to decrease with increasing AI substitution in orthoferrite. The effective magnetic moment （μeff） and the Curie constant （C） were calculated from the reciprocal of the molar magnetic susceptibility （Z-1） versus absolute temperature plot and found to attain maximum value for the parent sample. The magnetic behavior showed two different magnetic transitions, viz, N6el temperature （TN） and spin reorientation （TsR） transitions. The M-H hysteresis loop of the parent sample took.butterfly-shape as a result of different contributions anisotropies. From the magnetic properties measurements, it was obviously found that B-site cation dilution resulted in a drastic decrease in the magnetization. Surprisingly large value of the coercive field was obtained for the undoped sample;Hc=6198.80e. Based on the mentioned results, one can recommend the use of such orthoferrite in magnetic recording media and as pining layer in spin valve for spin- tronic applications.

关键词： SmFeO3 magnetization FESEM crystal structure spintronics spin reorientation butterfly-shaped hysteresis anisotropy rare earths

Crystal lattice free volume in a study of initiation reactivity of nitramines:Friction sensitivity

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Defence Technology（防务技术） 2018年第2期14卷 132-136页

作者： Svatopluk.Zeman Ning Liu Marcela Jungová ahmed k.Hussein Qi-long Yan Institute of Energetic Materials Faculty of Chemical TechnologyUniversity of PardubiceCZ-532 10PardubiceCzech Republic Xi'an Modern Chemistry Research Institute Xi'anShaanxi710065China School of Astronautics Northwestern Polytechnical UniversityXi'an 710072ShaanxiChina

The relationship between friction sensitivity(FS) and the crystal lattice free space per molecule, △V. of thirteen nitramines is described by a linear equation, divided into a number of the partial relationships with strong limitations by their molecular structure characteristics. Increasing FS due to raising of the △V values is not clearly confirmed. The influence of the △V values on friction sensitivity of nitramines is similar to that of their aza atoms which influence the mutual orientations of nitro groups in neighboring molecules. The dipole-dipole interaction of the oxygen and nitrogen atoms of nitro groups in neighboring nitramine molecules has a major effect on their own FS. In accordance with this interaction, a directly proportional relationship was derived between FS and the intrinsic gas phase molecular volume, V_(int), of the nitramines mentioned, which is divided also into several straight lines according to relatively tight molecular structure similarity. The relationships found again confirm a level of disorder in the distribution of the forces in the crystal lattice of the "common" quality of ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, in comparison with its reduced sensitivity(RS) or chemically pure analogue.

关键词： Crystal lattice Friction Initiation reactivity Nitramines

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Accretion on high derivative asymptotically safe black.holes

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Chinese Physics C 2020年第6期44卷 154-161页

作者： M.Umar Farooq Ayyesha k.ahmed Rong-Jia Yang Mubasher Jamil DBS and H College of E and MENational University of Sciences and Technology(NUST)H-12IslamabadPakistan Department of Mathematics School of Natural Sciences(SNS)National University of Sciences and Technology(NUST)H-12IslamabadPakistan College of Physical Science and Technology Hebei UniversityBaoding 071002China Institute for Theoretical Physics and Cosmology Zhejiang University of TechnologyHangzhou 310023China

Asymptotically safe gravity is an effective approach to quantum *** is important to differentiate modified gravity,which is inspired by asymptotically safe *** this study,we examine particle dynamics near the improved version of a Schwarzschild black.*** assume that in the context of an asymptotically safe gravity scenario,the ambient matter surrounding the black.hole is of isothermal nature,and we investigate the spherical accretion of matter by deriving solutions at critical *** analysis of various values of the state parameter for isothermal test fluids,viz.,k.1,1/2,1/3,1/4 show the possibility of accretion onto an asymptotically safe black.*** formulate the accretion problem as Hamiltonian dynamical system and explain its phase flow in detail,which reveals interesting results in the asymptotically safe gravity theory.

关键词： accretion black.holes asymptotically safe gravity

SUSTAINABILITY ASSESSMENT OF REINFORCED CONCRETE BEAM MIXES CONTAINING RECYCLED AGGREGATES AND INDUSTRIAL BY-PRODUCTS

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Journal of Green Building 2020年第3期15卷 95-119页

作者： Faiz Uddin ahmed Shaik. Anwar Hosan Wahidul k.Biswas School of Civil and Mechanical Engineering Curtin UniversityPerthAustralia

A vast amount of construction and demolition(C&D)wastes are generated in Western Australia(WA)of which a major portion goes to *** diversion of C&D waste from landfills would be the single most significant opportunity for WA to improve its recovery performance.C&D waste materials have already been investigated for their appropriateness and use in pavement and *** work.is the continuation of the authors’previous work.involving further experimental tests to prove the structural suitability of a building’s structural member(i.e.,beam)made of recycled aggregates and industrial *** concrete mixes considered in this study are 100NA+100 OPC(Control),100RA+100OPC,50RA+50NA+90OPC+10SF and 50RA+50NA+60OPC+30FA+*** Reinforced Concrete(RC)beam made of 50RA+50NA+60OPC+30FA+10SF concrete mix was found to be the only eco-efficient *** option has reduced the level of environmental impacts in a cost-competitive *** use of this eco-efficient option could also provide new employment opportunities and significant improvements in terms of land and energy resources conservation and bio-diversity enhancement.

关键词： OPC=ordinary Portland cement NA=Natural Aggregate RA=Recycled Aggregates SF=Silica Fumes FA=Fly Ash

Rangeland water requirement satisfaction index under rainfall variability and predicting future rainfall scenarios: implication for availability of feed resources

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Ecological Processes 2017年第1期6卷 264-272页

作者： Hassen M.ahmed Zewdu k.Tessema Adugna Tolera Diriba k.recha School of Animal and Range Sciences College of Agriculture and Environmental SciencesPO Box 138Dire DawaEthiopia School of Animal and Range Sciences Hawassa UniversityPO Box 222HawassaEthiopia Famine Early Warning Systems Network PO Box 1090Addis AbabaEthiopia School of Animal and Range Sciences College of Agriculture and Environmental SciencesHaramaya UniversityPO Box 1632Dire DawaEthiopia

Introduction:Rangeland ecosystems provide multiple ecosystem services,including feed resources for wild and domestic herbivores in semi-arid ***,under the ever increasing environmental changes,the impact of rainfall variability on the productivity and vegetation dynamics of rangelands are the great challenges that pastoral community are facing *** a result,the potentials of most rangelands in semi-arid ecosystems affect the ***,we studied the interconnections between the long-term rainfall variation and the rangeland Water Requirement and Satisfaction Index(WRSI)in Mieso,Jigjiga,and Shinile districts under pastoral conditions of ***:The base period rainfall data(1984–2015)was obtained from the National Meteorological Agency of Ethiopia,whereas the future rainfall trend was predicted using Mark.im software(Representative Concentration Pathways 4.5 GHG concentration trajectory).Mann-k.ndall’s statistical tests,coefficient of variation,LEAP software(version 2.61),and Minitab Software(version 15)were used to assess the relationship between rangeland WRSI and long-term rainfall ***:The result indicated that mean annual rainfall anomaly had strong positive correlation with rangeland WRSI in Mieso(P<0.05),Jigjiga(P<0.001),and Shinile(P<0.001)pastoral ***,short and long rainy seasons had positive association(P<0.001)with rangeland WRSI,especially in Jigjiga and Shinile pastoral *** base period rainfall as well as the predicted annual rainfall showed variability in amount and distribution in all studied districts in pastoral areas of ***:The mean annual rainfall anomaly is correlated with the rangeland ***,the future rainfall trend analysis indicated that variability of rainfall would be expected in between the years 2020–2049,2040–2069,and 2070–***,the future rainfall variability would limit future rangeland WRSI under pastoral conditions of Ethiopia.

关键词： LEAP software Pastoralist Rangeland water requirement Trend analysis

Performance studies on an oscillating water column employing a Savonius rotor

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Science China(Technological Sciences) 2011年第7期54卷 1674-1679页

作者： Sandeep k.PATEL k.ishnil RAM M.Rafiuddin ahmed Young-Ho LEE Division of Mechanical Engineering the University of the South Pacific Division of Mechanical and Information Engineering Korea Maritime University Busan Republic of Korea

A new oscillating water column (OWC) design is proposed in this study to incorporate a simpler Savonius type turbine. Conventional OWC devices employ a bi-directional turbine such as a Wells or an Impulse turbine to extract energy from the air. The disadvantages of the Wells turbine include its inability to self start and stalling. The Savonius turbine is much cheaper and is an effective option at low Reynolds numbers. In the current rectangular OWC device, unlik. the circular OWC, the width of entry of the capture chamber can be increased without being influenced by the diameter at the turbine section. To improve its primary capture efficiency, the front and rear walls of the OWC are inclined to minimize reflection. The Savonius rotor characteristics are studied with respect to the change in frequency of the incoming waves. The rotor rpm is sensitive to wave period and primary conversion efficiency while changes in depth only affect the rotor rpm at lower frequencies. The Savonius rotor shows promising results and can be incorporated into large scale OWC devices to reduce costs of the turbine component of the system.

关键词： wave energy Savonius rotor oscillating water column inclined chamber

Efficient energy harvesting from PV Panel with reinforced hydrophilic nano-materials for eco-buildings

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Energy and Built Environment 2024年第3期5卷 393-403页

作者： ahmed Elnozahy Heba Abd-Elbary Farag k.Abo-Elyousr Department of Electrical Engineering Faculty of EngineeringAssiut UniversityAssiut 71516Egypt

The main target of this research is to allow solar PV to contribute economically to an on-grid energy-efficient building where the dust accumulation is a significant ***-cleaning coatings such as hydrophobic or hy-drophilic materials have recently been introduced to reduce dust deposition on building-integrated PV(BIPV)*** hydrophilic Nano-coated material is examined as a solution to decrease the impact of the dust on the BIPV panels and harvest more solar *** impartial comparison of the BIPV panels performance under natu-ral dust conditions,manual cleaning,and hydrophilic nanomaterial coating is *** an exhaustive and qualitative experimental analysis,the anti-reflection and anti-static properties of the utilized Nano-coated material are *** experimental results show that the hydrophilic Nano-coated material significantly improves the gathered maximum output power by 18%compared to the manually wiped *** calculated efficiencies of the Nano-coated,manual cleaning,and dusty panels are 11%,9%,and 6%,respectively,which highlights the futureproofing of the Nano-coated solar *** to the dusty panels,the ecological and economical results show that the BIPV carbon emissions are desirably dropped by 11%while using Nano-coated PV panels and the payback.period is reduced to 3.9 years,which is approximately 12.8%faster.

关键词： Hydrophilic Self-cleaning BIPV panels Nano-coating Techno-economic

Serpentinized Peridotites at the North Part of the Wadi Allaqi District(Egypt): Implications for the Tectono-Magmatic Evolution of Fore-arc Crust

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Acta Geologica Sinica(English Edition) 2014年第5期88卷 1421-1436页

作者： ahmed E.S.k.ALIL Mohamed A.OBEID Mok.les k.AZER Geological Sciences Department National Research CentreP.O.Box 12622-Dokki Cairo Egypt Geology Department Faculty of Science Fayoum UniversityP.O.Box 63514- Fayoum Egypt

The Neoproterozoic Allaqi-Heiani suture （800-700 Ma） in the south Eastern Desert of Egypt is the northernmost linear ophiolitic belt that defines an arc-arc suture in the Arabian- Nubian shield （ANS）. The Neoproterozoic serpentinized peridotites represent a distinct lithology of dismembered ophiolites along the Allaqi-Heiani suture zone. The alteration of peridotites varies, some contain relicts of primary minerals （Cr-spinel and olivine） and others are extremely altered, especially along thrusts and shear zones, with development of talc, talc-carbonate and quartz-carbonate. The fresh cores of the chromian spinels are rimmed by ferritchromite and Cr- magnetite. The fresh chromian spinels have high Cr# （0.62 to 0.79）, while Mg# shows wider variation （0.35-0.59）. High Cr# in the relict chromian spinels and Fo content in the primary olivines indicate that they are residual peridotites after extensive partial melting. The studied ophiolitic upper mantle peridotites are highly depleted and most probably underwent high degrees of partial melting at a supra-subduction zone setting. They can be produced by up to -20%-22% dynamic melting of a primitive mantle source. The mineralogical and geochemical features of the studied rock. reflect that the mantle peridotites of the north part of the Wadi Allaqi district are similar to the fore-arc peridotites of a supra-subduction zone.

关键词： Neoproterozoic serpentinite Arabian-Nubian Shield Egypt Chromian spinel,olivine fore-arc

Spatiotemporal variation and mechanisms of temperature inversion in the Bay of Bengal and the eastern equatorial Indian Ocean

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Acta Oceanologica Sinica 2022年第4期41卷 23-39页

作者： k.M Azam Chowdhury Wensheng Jiang Guimei Liu Md k.wser ahmed Shaila Ak.ter College of Oceanic and Atmospheric Sciences Ocean University of ChinaQingdao 266100China k.yLab of Marine Environment and Ecology of Ministry of Education Ocean University of ChinaQingdao 266100China Department of Oceanography&International Centre for Ocean Governance(ICOG) University of DhakaDhaka 1000Bangladesh National Marine Environmental Forecasting Center Beijing 100081China

In the northern Bay of Bengal,the existence of intense temperature inversion during winter is a widely accepted ***,occurrences of temperature inversion during other seasons and the spatial distribution within and adjacent to the Bay of Bengal are not well *** this study,a higher resolution spatiotemporal variation of temperature inversion and its mechanisms are examined with mixed layer heat and salt budget analysis utilizing long-term Argo(2004 to 2020)and RAMA(2007 to 2020)profiles data in the Bay of Bengal and eastern equatorial Indian Ocean(EEIO).Temperature inversion exists(17.5%of the total 39293 Argo and 51.6%of the 28894 RAMA profiles)throughout the year in the entire study *** shows strong seasonal variation,with the highest occurrences in winter and the lowest in *** winter inversion in the northern Bay of Bengal,two other regions with frequent temperature inversion are identified in this study for the first time:the northeastern part of the Bay of Bengal and the eastern part of the EEIO during summer and *** processes of temperature inversion for different subregions are revealed in the current *** of heat(mean~25 W/m;)below the haline-stratified shallow mixed layer leads to a relatively warmer subsurface layer along with the simultaneous cooling tendency in mixed layer,which controls more occurrence of temperature inversion in the northern Bay of Bengal throughout the *** lower cooling tendency due to net surface heat loss and higher mixed layer salinity leaves the southern part of the bay less supportive to the formation of temperature inversion than the northern *** the EEIO,slightly cooling tendency in the mixed layer along with the subduction of warm-salty Arabian Sea water beneath the cold-fresher Bay of Bengal water,and downwelling of thermocline creates a favorable environment for forming temperature inversion mainly during summer and *** isothermal layer

关键词： temperature inversion Bay of Bengal Argo and RAMA data intrusion of the Arabian Sea water eastern equatorial Indian Ocean penetrative heat below mixed layer depth