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Corrosion Penetration and Crystal structure of AA5022 in HCl solution and Rare Earth Elements

Journal of Materials science & Technology 2005年第3期21卷 324-330页

作者： A.A.El-Meligi s.H.sanad A.A.Ismail A.M.Barakat Electrochem. and Corrosion Lab. Physical Chemistry Dept. National Research Centre Dokki Cairo EgypElectrochem. and Corrosion Lab. Physical Chemistry Dept. National Research Centre Dokki Cairo EgypElectrochem. and Corrosion Lab. Physical Chemistry Dept. National Research Centre Dokki Cairo EgypChemistry Dept. Faculty of Science Cairo University Cairo Egypt

Al-alloy (AA5022) corrosion penetration (CP) and crystal structure were investigated after running static immersion corrosion tests in 1 mol/L HCl solution and different concentrations of rare earth elements (La3+), (Ce3+) and their combination, at different temperatures. X-ray diffraction (XRD) was used to examine the surface structure before and after immersion, and secondary electron detector (sED) was operated to study surface morphology. In 1 mol/L HCI solution the corrosion penetration increased with increasing temperature and immersion time. The increase of La3+ concentrations up to 1000×10-6 g/L led to the decrease in the corrosion penetration, and the decrease in Ce3+ concentrations up to 50×10-6 g/L decreases the corrosion penetration of the alloy. Mix3 (combination of La3+ and Ce3+) dramatically reduced the corrosion penetration. This suggests that a synergistic effect exists between La3+ and Ce3+. The reaction kinetics both in absence and presence of La3+ and Ce3+ and their combination would follow a parabolic rate law. The XRD patterns revealed that the intensities of certain hkl phases are affected. The crystalline structure has not been deformed either before or after testing and there are no additional peaks except that of the as-received alloy. In the case of accelerating CP, the surface morphology shows that the roughness and voids of surface are increased.

关键词： Al-alloy Corrosion penetration Crystal structure XRD

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Collaborative learning via social computing

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Frontiers of Information Technology & Electronic Engineering 2019年第2期20卷 265-282页

作者： Ricardo s.ALONsO Javier PRIETO óscar GARCíA Juan M.CORCHADO BIsITE Research Group University of Salamanca

Educational innovation is a field that has been greatly enriched by using technology in its processes, resulting in a learning model where information comes from numerous sources and collaboration takes place among multiple students. One attractive challenge within educational innovation is the design of collaborative learning activities from the social computing point of view, where collaboration is not limited to student-to-student relationships, but includes student-to-machine interactions. At the same time, there is a great lack of tools that give support to the whole learning process and are not restricted to specific aspects of the educational task. In this paper, we present and evaluate context-aware framework for collaborative learning applications(CAFCLA) as a solution to these problems. CAFCLA is a flexible framework that covers the entire process of developing collaborative learning activities, taking advantage of contextual information and social interactions. Its application in the experimental case study of a collaborative WebQuest within a museum has shown that, among other benefits, the use of social computing improves the learning process, fosters collaboration, enhances relationships, and increases engagement.

关键词： Context-awareness Collaborative learning social computing Virtual organizations Wireless sensor networks Real time location system

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Localized CO_2 laser bonding process for MEMs packaging

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中国有色金属学会会刊：英文版 2006年第B02期16卷 577-581页

作者： sUN Li A. P. MALsHE s. CUNNINGHAM A. MORRIs Department of Mechanical Engineering University of Arkansas Fayetteville AR 72701 USA wispry Inc. Irvine CA 92618 USA wispry Inc. Cary NC 27513 USA

The packaging poses a critical challenge for commercialization of MEMs products. Major problems with the packaging process include degraded reliability caused by the excess stress due to thermal mismatch and altered performance of the MEMs device after packaging caused by thermal exposure. The localized laser bonding technique for ceramic MEMs packaging to address above-mentioned challenges was investigated. A continuous wave CO2 laser was used to locally heat sealing material for ceramic MEMs package lid to substrate bonding. To determine the laser power density and scanning speed, finite element analysis thermal models were constructed to simulate the localized laser bonding process. Further, the effect of external pressure at sealing ring on the bonding formation was studied. Pull testing results show that the scanning speed and external pressure have significant influence on the pull strength at the bonding interface. Cross-sectional microscopy of the bonding interface indicates that the packages bonded with relatively low scanning speed and external pressure conditions have higher bonding quality. This research demonstrates the potential of localized laser bonding process for ceramic MEMs packaging.

关键词：微电子机械系统 MEMs 封装局部激光焊接过程有限元分析

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Analysis on EAsT LHCD Operation space by Using simple Core-sOL-Divertor Model

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Plasma science and Technology 2009年第4期11卷 389-393页

作者： R.HIWATARI A.HATAYAMA s.ZHU Y.TOMITA Central Research Institute of Electric Power Industry Faculty of science and Technology Keio University Institute of Plasma Physics Chinese Academy of Sciences National Institute for Fusion science

A simple core-sOL-divertor model （CsD model） was developed to investigate qual- itatively the overall features of the operational space for the integrated core and edge plasma. In the CsD model, the core plasma model of ITER physics guidelines and the two-point sOL-divertor model are applied, This CsD model is validated by the two dimensional divertor transport code （B2-EIRINE） and by the JT-60U divertor recycling database, and this model is applicable to the low- and high-recycling state of the divertor plasma. The CsD model is applied to the study of the EAsT operational space with lower hybrid current drive under various kinds of trade-off for the basic plasma parameters, and the relationship between the operational space and the plasma discharge duration is also discussed.

关键词： core transport sOL-divertor transport operation space EAsT LHCD

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Analysis of the Biotribological Behavior for the stainless steel/Polyethylene Contact Using a Knee Prosthesis simulator

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Journal of Bionic Engineering 2012年第1期9卷 59-65页

作者： M. Boujelbene s. Dhouibi M. Kharrat M. Dammak Laboratoire des systkmes Electromeeaniques Ecole Nationale d＇Ingenieurs de Sfax Route de Soukra km 35 B.P. 1173 3038 Sfax Tunisia Institut superieur de Gestion Industrielle de sfax Route de Mharza Km 15 B.P. 954 3018 Sfax Tunisia Faeulte des sciences de Gafsa Campus Universitaire Sidi Ahmed Zarrouk 2112 Gafsa Tunisia Institut Preparatoire aux Etudes d＇Ingenieurs de sfax Route de Menzel Chaker Km 05 B.P. 1172 3018 Sfax Tunisia

In this work, a friction and wear simulator was used to reproduce the Anterior-Posterior （AP） sliding and the Flex- ion-Extension （FE） rotation generated in the knee joint during human gait cycle. We chose to simplify the contact geometry between the Total Knee Arthroplasty （TKA） femoral component and tibial insert. A 304L stainless steel cylinder which replaces the femoral component was loaded onto a flat High Density Polyethylene （HDPE） block which replaces the tibial insert. The tribological behavior of the considered contact was analyzed by tracking the number of cycles, the friction coefficient, the roughness of the wear track on HDPE, the HDPE weight loss and the damage mechanisms. The friction coefficient shows a gradual increase with the number of cycles for both AP and FE kinematics. The evolution of friction coefficient with the number of cycles is not affected by the value of the imposed normal load in the case of AP sliding. For the FE rotation, decreased friction coefficient is obtained when the imposed normal load increases. For both considered AP and FE kinematics, the roughness of the wear track on the HDPE is not affected by the imposed normal load. It shows a progressive decrease when the number of cycles increases. The wear of HDPE obeys the Archard law and the wear coefficient increases with the normal force. For a given value of normal load, the obtained wear coefficient for the AP sliding is larger than that obtained for FE rotation. A predominant adhesive wear mechanism was identified for both AP and FE kinematics. Under the same normal load, damage development in terms of plastic deformation, micro-cracking and debonding is more pronounced for the AP sliding if compared with the FE rotation. For a given kinematics, the damage severity increases with the normal load. This finding is in good agreement with the predicted values of the wear coefficient according to the Archard law.

关键词： knee prosthesis polyethylene friction wear gait cycle

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Application of Dvoretzky’s Theorem of Measure Concentration in Physics and Cosmology

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Open Journal of Microphysics 2015年第2期5卷 11-15页

作者： Mohamed s. El Naschie Department of Physics University of Alexandria Alexandria Egypt

Using Dvoretzky’s theorem in conjunction with Bohm’s picture of a quantum particle inside a guiding quantum wave akin to De Broglie-Bohm pilot wave we derive Einstein’s famous formula E = mc2 as the sum of two parts E(O) = mc2/22 of the quantum particle and E(D) = m c2 (21/22) of the quantum wave where m is the mass, c is the speed of light and E is the energy. In addition we look at the problem of black holes information in the presence of extra dimensions where it seems initially that extra dimensions would logically lead to a hyper-surface for a black hole and consequently a reduction of the corresponding information density due to the dilution effect of these additional dimensions. The present paper argues that the counterintuitive opposite of the above is what should be expected. Again this surprising result is a consequence of the same well known theorem on measure concentration due to I. Dvoretzky. We conclude that there are only two real applications of the theorem and we expect that many more applications in physics and cosmology will be found in due course.

关键词： spacetime Extra Dimensions Dvoretzky’s Theorem Information Paradox E-Infinity Theory Counterintuitive Geometry Dark Energy of the Quantum Wave 'tHooft-susskind Black Holes Wave-Particle Duality De Broglie-Bohm Pilot Wave

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Coordinating plant pigment production:A green role for ORANGE family proteins

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Molecular Plant 2023年第9期16卷 1366-1369页

作者： Andrew Hitchcock Matthew s.Proctor Roman sobotka Plants Photosynthesis and SoilSchool of BiosciencesUniversity of SheffieldSheffield S102TNUK institute of Microbiology of the Czech Academy of sciences Opatovicky mlynTrebon 37901Czech Republic Faculty of science University of South BohemiaCeske Budejovice 37005CzechRepublic

Chlorophylls and carotenoids are essential pigments for photosynthesis and plastid/plant *** are utilized for light harvesting and primary charge separation,whereas carotenoids are accessory light-harvesting pigments that also play major roles in photoprotection,in the assembly and stability of photosystems,and as precursors to phytohormones and other important signaling *** biosynthesis of these pigments must be precisely regulated to ensure their balanced production for the synthesis,assembly,and maintenance of the photosynthetic apparatus.

关键词： harvesting utilized apparatus

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Thermal-hydraulic and stress analysis of AP1000 reactor containment during LOCA in dry cooling mode

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Nuclear science and Techniques 2017年第6期28卷 73-85页

作者： sh.sheykhi s.Talebi M.soroush E.Masoumi Department of Energy Engineering and Physics Amirkabir University of Technology(Tehran Polytechnic) Young Researchers and Elite Club Islamic Azad UniversitySouth Tehran Branch

some kinds of break in the reactor coolant system may cause the coolant to exit rapidly from the failure site,which leads to the loss of coolant accident(LOCA).In this paper,a stress analysis of an AP1000 reactor containment is performed in an LOCA,with the passive containment cooling system(PCCs) being available and not available for cooling the wall's *** variations in the mechanical properties of the wall's containment,including elastic modulus,strength,and stress,are analyzed using the ABAQUs code.A general two-phase model is applied for modeling thermal-hydraulic behavior inside the *** pressure and temperature from thermal-hydraulic models are considered as boundary conditions of the ABAQUs code to obtain distributions of temperature and stress across steel shell of the containment in the *** results indicate that if the PCCs fails,the peak pressure inside the containment exceeds the design ***,the stress would still be lower than the yield stress value,and no risk would threaten the integrity of the containment.

关键词： Two-phase flow LOCA Containment integrity AP1000 reactor

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A Numerical Fluid Analysis for Early Nonlinear Mode Evolution of Fast Electron Beams in Dense Plasmas

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Plasma science and Technology 2009年第6期11卷 661-665页

作者： s.REHMAN 王晓钢刘健雷奕安刘悦 Laboratory of Materials Modification by Laser Ion and Electron BeamsSchool of Physics & Optoelectronic TechnologyDalian University of Technology state Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking University

Nonlinear mode evolution for relativistic electrons in dense plasmas is analyzed in a three-dimensional fluid approach. similar to the results previously obtained in particle-in-cell simulations, it is found that oblique modes dominate two-stream and filamentation modes in the linear stage. On the other hand a power spectrum analysis shows the nonlinear development of the high wavenumber modes.

关键词： relativistic electron beams power spectrum analysis instabilities

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Anomalies in(semi)-leptonic B decays B~±→τ~±ν,B~±→Dτ~±ν and B~±→D~*τ~±ν,and possible resolution with sterile neutrino

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Chinese Physics C 2017年第11期41卷 14-27页

作者： Gorazd Cveti Francis Halzen C.s.Kim sechul Oh Department of Physics Universidad Tcnica Federico Santa María Wisconsin Ice Cube Particle Astrophysics Center and Department of Physics University of Wisconsin Department of Physics and IPAP Yonsei University University College Yonsei University

The universality of the weak interactions can be tested in semileptonic b→c transitions,and in particular in the ratios R（D＊） ≡ Γ（B → D（＊）τν）/Γ（B → D＊lν）（where 1 = μ or e）.Due to the recent differences between the experimental measurements of these observables by Ba Bar,Belle and LHCb on the one hand and the standard Model predicted values on the other hand,we study the predicted ratios R（D＊）=Γ（B→D＊τ＋＂missing＂）/Γ（B→D（＊）lν）in scenarios with an additional sterile heavy neutrino of mass ～1 Ge ***,we evaluate the newly defined ratio R（0）≡Γ（B→τ＋＂missing＂）/Γ（B→μν） in such scenarios,in view of the future possibilities of measuring the quantity at Belle-Ⅱ.

关键词： sterile neutrino lepton universality semileptonic B decays

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