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Effect of Co on Solidification Characteristics and Microstructural Transformation of Non-equilibrium Solidified Cu-Ni Alloys

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 444-453页

作者：安红恩 Bih-Lii Chua Ismail Saad Willey Yun Hsien liew Materials Engineering Research Group Faculty of EngineeringUniversity Malaysia Sabah88400 Kota KinabaluSabahMalaysia College of Mechanical and Electronic Engineering Huanghe Jiaotong UniversityJiaozuo 454950China Henan Engineering Technology Research Center on Intelligent Manufacturing Technology and Equipment Jiaozuo 454950China Centre of Research in Energy and Advanced Materials Faculty of EngineeringUniversiti Malaysia SabahJalan UMS88400 Kota KinabaluSabahMalaysia Nano Engineering and Materials Research group Faculty of EngineeringUniversity Malaysia Sabah88400 Kota KinabaluSabahMalaysia

Non-equilibrium solidification structures of Cu55Ni45 and Cu55Ni43Co2 alloys were prepared by the molten glass purification cycle superheating *** variation of the recalescence phenomenon with the degree of undercooling in the rapid solidification process was investigated using an infrared *** addition of the Co element affected the evolution of the recalescence phenomenon in Cu-Ni *** images of the solid-liquid interface migration during the rapid solidification of supercooled melts were captured by using a high-speed *** solidification rate of Cu-Ni alloys,with the addition of Co elements,was ***,the grain refinement structure with low supercooling was characterised using electron backscatter diffraction(EBSD).The effect of Co on the microstructural evolution during nonequilibrium solidification of Cu-Ni alloys under conditions of small supercooling is investigated by comparing the microstructures of Cu55Ni45 and Cu55Ni43Co2 *** experimental results show that the addition of a small amount of Co weakens the recalescence behaviour of the Cu55Ni45 alloy and significantly reduces the thermal strain in the rapid solidification *** the rapid solidification phase,the thermal strain is greatly reduced,and there is a significant increase in the characteristic undercooling ***,the addition of Co and the reduction of Cu not only result in a lower solidification rate of the alloy,but also contribute to the homogenisation of the grain size.

关键词： non-equilibrium solidification recalescence effect solidification character microstructure

The improved element-free Galerkin method for three-dimensional transient heat conduction problems

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Science China(Physics,Mechanics & Astronomy) 2013年第8期56卷 1568-1580页

作者： ZHANG Zan WANG JianFei CHENG YuMin liew Kim Meow School of Science East China University of Science and Technology Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai University Department of Civil and Architectural Engineering City University of Hong Kong

With the improved moving least-squares (IMLS) approximation, an orthogonal function system with a weight function is used as the basis function. The combination of the element-free Galerkin (EFG) method and the IMLS approximation leads to the development of the improved element-free Galerkin (IEFG) method. In this paper, the IEFG method is applied to study the partial differential equations that control the heat flow in three-dimensional space. With the IEFG technique, the Galerkin weak form is employed to develop the discretized system equations, and the penalty method is applied to impose the essential boundary conditions. The traditional difference method for two-point boundary value problems is selected for the time discretization. As the transient heat conduction equations and the boundary and initial conditions are time dependent, the scaling parameter, number of nodes and time step length are considered in a convergence study.

关键词： weighted orthogonal function improved moving least-squares (IMLS) approximation improved element-free Galerkin (IEFG) method penalty method transient heat conduction

Comparative studies on Zn_(0.95)Co_(0.05)O thin films on C- and R-sapphire substrates

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Chinese Physics B 2009年第12期18卷 5501-5506页

作者：彭英姿 Thomas liew Song Wen-Dong Chong Tow Chong Data Storage Instit u re DSI Building 5 Engineering Drive 1 Singapore 117608 Electrical and Computer Engineering Department National University of Singapore Singapore 119260 School of Science Hangzhou Dianzi University Hangzhou 310018 China

Zn0.95Co0.05O precipitate-free single crystal thin films were synthesized by a dual beam pulsed laser deposition method. The films form a wurtzite structure whose hexagonal axis is perpendicular or parallel to the plane of the surface depending on the C-plane （0001） or R-plane （1120） sapphire substrate. Based on the results of high-resolution transmission electron microscopy and x-ray diffraction, C-plane films show larger lattice mismatch. The films exhibit magnetic and semiconductor properties at room temperature. The coercivity of the film is about 8000 A/m at room temperature. They are soft magnetic materials with small remanent squareness S for both crystal orientations. There is no evidence to show that the anisotropy is fixed to the hexagonal axis （C-axis） for the wurtzite structure.

关键词： Co-doped ZnO thin films diluted magnetic semiconductor anisotropy

Experimental evaluation of force analogy method(FAM) by element type

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Earthquake Engineering and Engineering Vibration 2020年第1期19卷 137-147页

作者： Iraj Toloue Mohd Shahir liew Indra Sati Hamonangan Harahap Hsiu Eik Lee Civil Engineering Department Universiti Teknologi PETRONASBandar Seri Iskandar32610 PerakMalaysia Research&Innovation Offi ce Universiti Teknologi PETRONASBandar Seri Iskandar32610 PerakMalaysia

The force analogy method(FAM) is considered as one of the most time-saving and cost-efficient methods for analyzing frames. Through a set of assumptions and restoring forces, FAM analyzes nonlinear frames responses through Hooke’s law. This study evaluates the effect of element type on FAM through numerical and experimental tests. The conventional Euler Bernoulli(EB) element is replaced by the Timoshenko(TS) beam-column element and the results are interpreted and compared with experimental findings. Three experimental tests were conducted for benchmarking and comparison purposes via 2 D aluminum frames. The results indicated that during the analysis, when the frame response is in the linear region, there is no difference between the element types in the response of the frames. When the frame entered the plastic region, the frames which were analyzed by the TS element revealed closer responses to the experimental outcomes. The gap between the results of the frame which was analyzed by EB and TS enlarged especially when the frame experienced a sharp or huge rotation of more than 0.2 rad. The final recorded deformations based on the TS element revealed an accuracy between 98.05% to 98.65%, while the EB element showed 14.66% to 45.14% for rotations of more than 0.2 rad at plastic hinge locations(PHLs).

关键词： FAM Timoshenko Euler Bernoulli nonlinear vibration

The influence of pressure waves in tidal gravity records

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Geodesy and Geodynamics 2023年第1期14卷 15-25页

作者： bernard Ducarme Catholic University of Louvain Georges Lemaître Centre for Earth and Climate Research(ELI)Louvain-la-NeuveBelgium

For the reduction of atmospheric effects,observed gravity has initially been corrected by using the computed barometric admittance k of the in situ measured pressure,expressed in nms-2/hPa units and estimated by least squares ***,the local pressure changes alone cannot account for the atmospheric mass attraction and loading when the coherent pressure field exceeds a specific size,i.e.,with increasing *** overcome this difficulty,it is necessary to compute the total atmospheric effect at each station using the global pressure ***,the direct subtraction of the total gravity effect,provided by the models of pressure correction,is not yet satisfactory for S2 and other tidal components,such as K2 and P1,which include solar heating pressure *** paper identifies the origin of the problem and presents strategies to obtain a satisfactory ***,we set up a difference vector between the tidal factors of M2 and S2 after correction of the pressure and ocean tides *** vector,hereafter denoted as RES,presents the advantage of being practically insensitive to calibration *** minimum discrepancy between the tidal parameters of M2 and S2 corresponds to the minimum of the RES vector norm *** we adopt the hybrid pressure correction method,separating the local and the global pressure contribution of the models and replacing the local contribution by the pressure measured at the station multiplied by an admittance *** tested this procedure on 8 stations from the IGETS superconducting gravimeters network(former GGP network).For stations at an altitude lower than 1000 m,the value of dopt is always smaller *** discrepancy between the tidal parameters of the M2 and S2 waves is always lower than0.05% on the amplitude factors and 0.025° on the *** these stations,a correlation exists between the altitude and the value *** results at the three Central European stations Conrad,Pecny and Vienna are

关键词： Atmospheric pressure waves Atmospheric pressure correction in tidal records Atmospheric pressure models ERA5 and MERRA-2

The improved element-free Galerkin method forthree-dimensional wave equation

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Acta Mechanica Sinica 2012年第3期28卷 808-818页

作者： Zan Zhang Dong-Ming Li Yu-Min Cheng Kim Moew liew Shanghai Institute of Applied Mathematics and Mechanics Shanghai University200072 ShanghaiChina Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai University200072 ShanghaiChina Department of Civil and Architectural Engineering City University of Hong KongTat Chee AvenueKowloonHong Kong SARChina

The paper presents the improved element-free Galerkin （IEFG） method for three-dimensional wave propa- gation. The improved moving least-squares （IMLS） approx- imation is employed to construct the shape function, which uses an orthogonal function system with a weight function as the basis function. Compared with the conventional moving least-squares （MLS） approximation, the algebraic equation system in the IMLS approximation is not ill-conditioned, and can be solved directly without deriving the inverse matrix. Because there are fewer coefficients in the IMLS than in the MLS approximation, fewer nodes are selected in the IEFG method than in the element-free Galerkin method. Thus, the IEFG method has a higher computing speed. In the IEFG method, the Galerkin weak form is employed to obtain a dis- cretized system equation, and the penalty method is applied to impose the essential boundary condition. The traditional difference method for two-point boundary value problems is selected for the time discretization. As the wave equations and the boundary-initial conditions depend on time, the scal- ing parameter, number of nodes and the time step length are considered for the convergence study.

关键词： Weighted orthogonal function Improved mov-ing least squares (IMLS) approximation. Improved element-free Galerkin (IEFG) method Penalty method Temporaldiscretization Wave equation

A Fresh Look at the Structures of Nylons and the Brill Transition

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Advanced Fiber Materials 2021年第4期3卷 203-209页

作者： bernard Lotz Institut Charles Sadron CNRS and Universitéde Strasbourg23Rue du Loess67034 StrasbourgFrance

The common knowledge of the crystal structures of nylons dates back to the early 1950s with the work of Bunn and *** describes the packing of sheets made of hydrogen-bonded stems in an extended chain *** alpha phase structures have a specific powder X-ray diffraction pattern with reflections at 4.4Åand 3.7Å.On heating,reflections trans-form progressively and merge at≈4.2Åat the so-called“Brill transition”.Other diffraction patterns have been recorded for different types of nylons and thermal *** patterns were interpreted only as indicating the existence of“variants”of the alpha ***,neither their structure,nor the origin of the Brill transition were *** structural analyses and molecular modeling approaches have provided new insights in these long-standing structural ***“variants”feature chain conformations that are“pleated”.The Brill transition does not involve the standard extended chains of the alpha phase but corresponds to a dynamic interconversion(≈10^(10)/s)between mirror conformations of these pleated stems.

关键词： Nylons Crystal structures Phase transitions Brill transition

After Sendai:Is Africa Bouncing Back or Bouncing Forward from Disasters?

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International Journal of Disaster Risk Science 2016年第1期7卷 41-53页

作者： bernard Manyena International Disaster Management Humanitarian and Conflict Response Institute University of Manchester

The 187 countries that adopted the Sendai Framework for Disaster Risk Reduction 2015–2030 at the March 2015 UN World Conference on Disaster Risk Reduction included most African countries. Many developing regions of the world, particularly in Asia and Latin America, made considerable progress in implementing the previous Hyogo Framework for Action 2005–2015. But,despite the fact that Africa is one of the regions most vulnerable and least resilient to disasters, which continue to be exacerbated by poverty, climate change, rapid urbanization, and structural transformation, it saw only slow progress. This article considers the challenges Africa faces in implementing the Sendai Framework and recommends that besides ‘‘Africanizing'' Sendai goals and strengthening the region's political commitment to disaster risk reduction(DRR), Africa should also develop a single framework that integrates DRR, sustainable development, climate change adaptation, and conflict prevention. Equally important is the need for a strong recognition that disasters are created endogenously as well as exogenously, and thus require local solutions and local investment.

关键词： Sub-Saharan Africa Climate change adaptation Disaster risk reduction Resilience Sendai framework Sustainable development

The apical plasma membrane of chitin-synthesizing epithelia

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Insect Science 2013年第2期20卷 139-146页

作者： bernard Moussian Animal Genetics Interfaculty Institute for Cell Biology University of Tubingen 72076 TEtbingen Germany

Chitin is the second most abundant polysaccharide on earth. It is produced at the apical side of epidermal, tracheal, fore-, and hindgut epithelial cells in insects as a central component of the protective and supporting extracellular cuticle. Chitin is also an important constituent of the midgut peritrophic matrix that encases the food supporting its digestion and protects the epithelium against invasion by possibly ingested pathogens. The enzyme producing chitin is a glycosyltransferase that resides in the apical plasma membrane forming a pore to extrude the chains of chitin into the extracellular space. The apical plasma membrane is not only a platform for chitin synthases but, probably through its shape and equipment with distinct factors, also plays an important role in orienting and organizing chitin fibers. Here, I review findings on the cellular and molecular constitution of the apical plasma membrane of chitin-producing epithelia mainly focusing on work done in the fruit fly Drosophila melanogaster.

关键词： apical undulae cuticle extracellular matrix epidermis microvilli