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Robust interface and excellent as-built mechanical properties of Ti–6Al–4V fabricated through laser-aided additive manufacturing with powder and wire

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 154-168页

作者： Fei Weng Guijun Bi Youxiang Chew Shang Sui Chaolin Tan Zhenglin Du Jinlong Su Fern lan ng key laboratory for liquid-Solid Structural Evolution and Processing of Materials Ministry of EducationShandong Engineering&Technology Research Center for Superhard MaterialSchool of Materials Science and EngineeringShandong UniversityJinan 250061China Institute of Intelligent Manufacturing Guangdong Academy of SciencesGuangzhou 510095China Singapore Institute of Manufacturing Technology 5 Cleantech Loop636732Singapore

The feasibility of manufacturing Ti-6Al-4V samples through a combination of laser-aided additive manufacturing with powder(lAAM_(p))and wire(lAAM_(w))was explored.A process study was first conducted to successfully circumvent defects in Ti-6Al-4V deposits for lAAM_(p) and lAAM_(w),*** the optimized process parameters,robust interfaces were achieved between powder/wire deposits and the forged substrate,as well as between powder and wire *** characterization results revealed the epitaxial prior β grains in the deposited Ti-6Al-4V,wherein the powder deposit was dominated by a finerα′microstructure and the wire deposit was characterized by lamellar α *** mechanisms of microstructure formation and correlation with mechanical behavior were analyzed and *** mechanical properties of the interfacial samples can meet the requirements of the relevant Aerospace Material Specifications(AMS 6932)even without post heat *** fracture occurred within the interfacial area,further suggesting the robust *** findings of this study highlighted the feasibility of combining lAAM_(p) and lAAM_(w) in the direct manufacturing of Ti-6Al-4V parts in accordance with the required dimensional resolution and deposition rate,together with sound strength and ductility balance in the as-built condition.

关键词： laser-aided additive manufacturing powder deposition wire deposition interfacial characteristic mechanical behavior

Control of settlement and volume loss induced by tunneling under recently reclaimed land

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Underground Space 2019年第4期4卷 289-301页

作者： a.k.l.kw.ng C.C.W.ng A.Schwob AECOM Hong KongChina Dragages-Bouygues Joint Venture Hong KongChina

The proposed Tuen Mun-Chek lap kok link(TM-Clkl)project comprises a 9-km-long dual two-lane carriageway between Tuen Mun and North lantau,Hong *** of the two tunnels at the Northern landfall Fall was carried out by two TBMs:the northbound is referred to as Ml03 and has an excavated diameter of 17.63 m,and the southbound is referred to as Ml02 and has an excavated diameter of 14.00 *** use of TBMs minimized the amount of dredging and removal of soft marine deposits,resulting in less impact to the environment within and near the work site of the *** treatment in the form of deep vibro-compaction was carried out at the sand fill and band drains installed in the marine deposit.A surcharge was also added above the final formation level to limit the residual settlement and differential settlement of the reclaimed land to less than 500 mm and 1 in 300,respectively,for a design life of 50 *** element analyses were performed to predict the settlement trough under different confinement pressures along the tunnel *** monitoring of the ground movement was carried out during the driving of the two TBMs to ensure that the design confinement pressure of the slurry would not cause excessive settlement,heave,or blow out at the shallow tunnel sections or different facilities along the tunnel *** monitoring data was then used to back-calculate the percentage of volume loss,which is a key index describing the behavior of the ground during *** monitoring data showed that the measured settlement and back-calculated volume loss were much lower than the predicted values.

关键词： TBM excavation Settlement trough Volume loss Ground treatment Confinement pressure

ON INTEGRITY ASSESSMENT OF AXISYMMETRIC COMPONENTS OPERATIng WITHIN CREEP REGIME

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Chinese Journal of Mechanical Engineering 2006年第4期19卷 492-495页

作者： ZARRABI k lAWRENCE ng School of Mechanical and Manufacturing Engineering University of New South Wales Sydney NSW 2052 Australia

A multiaxial paradigm for predicting creep damage/lives of components is described. Although in principle the paradigm is general, it is verified using axisymmetric experimental data. It is shown that the proposed paradigm is capable of predicting creep lives with an error of less than 2%. It is also shown that the proposed paradigm is more accurate than the reference stress method.

关键词： Creep damage Creep life

Preconditioned Iterative Methods for Algebraic Systems from Multiplicative Half-Quadratic Regularization Image Restorations

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Numerical Mathematics(Theory,Methods and Applications) 2010年第4期3卷 461-474页

作者： Michael k.ng Department of Mathematics Hong Kong Baptist UniversityKowloon TongHong Kong

Image restoration is often solved by minimizing an energy function consisting of a data-fidelity term and a regularization term.A regularized convex term can usually preserve the image edges well in the restored *** this paper,we consider a class of convex and edge-preserving regularization functions,i.e.,multiplicative half-quadratic regularizations,and we use the Newton method to solve the correspondingly reduced systems of nonlinear *** each Newton iterate,the preconditioned conjugate gradient method,incorporated with a constraint preconditioner,is employed to solve the structured Newton equation that has a symmetric positive definite coefficient matrix. The eigenvalue bounds of the preconditioned matrix are deliberately derived,which can be used to estimate the convergence speed of the preconditioned conjugate gradient *** use experimental results to demonstrate that this new approach is efficient, and the effect of image restoration is reasonably well.

关键词： Edge-preserving image restoration multiplicative half-quadratic regularization Newton method preconditioned conjugate gradient method constraint preconditioner eigenvalue bounds

ON AlGORITHMS FOR AUTOMATIC DEBlURRIng FROM A SInglE IMAGE

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Journal of Computational Mathematics 2012年第1期30卷 80-100页

作者： Wei Wang Michael k.ng Department of Mathematics Tongji UniversityShanghai 200092China Centre for Mathematical Imaging and Vision and Department of Mathematics Hong Kong Baptist UniversityKowloon TongHong KongChina

In this paper, we study two variational blind deblurring models for a single linage,The first model is to use the total variation prior in both image and blur, while the second model is to use the flame based prior in both image and blur. The main contribution of this paper is to show how to employ the generalized cross validation （GCV） method efficiently and automatically to estimate the two regularization parameters associated with the priors in these two blind motion deblurring models. Our experimental results show that the visual quality of restored images by the proposed method is very good, and they are competitive with the tested existing methods. We will also demonstrate the proposed method is also very efficient.

关键词： Blind deconvolution Iterative methods Total variation Framelet Generalizedcross validation.

Second-order optimality conditions f or minimizing a maxfunction

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Science China Mathematics 2000年第7期43卷 722-733页

作者：黄力人 k.F.ng Department of Mathematics South China Normal University Guangzhou 510631 China Department of Mathematics The Chinese University of Hong KongHong KongChina Correspondence should be addressed to K.F.Ng

We study Chaney's and Ben-Tal-Zowe's second-order directional derivatives with applications in minimization problem for max-functions of the formh(x): = max {f(x, τ); τ ∈T},where T is a compact metricspace. We impr... 详细信息

关键词： max-f unction sup-type function second-order optimality condition nonsmooth optimization.

Solving sparse non-negative tensor equations： algorithms and applications

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Frontiers of Mathematics in China 2015年第3期10卷 649-680页

作者： Xutao lI Michael k. ng School of Computer Engineering Nanyang Technological University Singapore 639798 Singapore Centre for Mathematical Imaging and Vision and Department of MathematicsHong Kong Baptist University Hong Kong China

We study iterative methods for solving a set of sparse non-negative tensor equations （multivariate polynomial systems） arising from data mining applications such as information retrieval by query search and community discovery in multi-dimensional networks. By making use of sparse and non-negative tensor structure, we develop Jacobi and Gauss-Seidel methods for solving tensor equations. The multiplication of tensors with vectors are required at each iteration of these iterative methods, the cost per iteration depends on the number of non-zeros in the sparse tensors. We show linear convergence of the Jacobi and Gauss-Seidel methods under suitable conditions, and therefore, the set of sparse non-negative tensor equations can be solved very efficiently. Experimental results on information retrieval by query search and community discovery in multi-dimensional networks are presented to illustrate the application of tensor equations and the effectiveness of the proposed methods.

关键词： Nonnegative tensor multi-dimensional network information retrieval community iterative method multivariate polynomial equation

Compressive properties of a novel slurry-infiltrated fiber concrete reinforced with arc-shaped steel fibers

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第6期24卷 543-556页

作者： Hedong lI Yabiao lI Yunfeng PAN P.l.ng Christopher k.Y.lEUng Xin ZHAO School of Civil Engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou 310018China Department of Civil Engineering The University of Hong KongHong Kong 999077China Faculty of Civil Engineering Vilnius Gediminas Technical UniversityVilnius LT-10223Lithuania Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong Kong 999077China School of Civil Engineering and Architecture Zhejiang University of Science and TechnologyHangzhou 310023China

Slurry-infiltrated fiber concrete(SIFCON)is a sort of strain hardening cement-based composite material,typically made with 5%–20%steel *** study focused on a novel type of SIFCON in which hooked-end steel fibers were replaced by arc-shaped steel *** quasi-static compressive properties of the SIFCON were first *** results suggested that using arc-shaped steel fibers in lieu of hooked-end steel fibers increased the quasi-static compressive strength by 47.1%and the strain at peak stress by 56.3%.We attribute these improvements to new crack-resisting mechanisms,namely“fiber crosslock”,“dual bridging”,and“confinement loops”,when the arc-shaped steel fibers are introduced into *** high impact resistance is a special property of SIFCON that is of practical significance,the dynamic compressive properties of arc-shaped steel fiber SIFCON were studied by using an 80-mm-diameter split Hopkinson pressure bar(SHPB).The results showed that the dynamic compressive strength,dynamic increase factor(DIF),and dynamic toughness of SIFCON all increased with the strain *** SIFCON incorporating arc-shaped steel fibers proved to have significant advantages in structural applications requiring high impact resistance.

关键词： Slurry-infiltrated fiber concrete(SIFCON) Arc-shaped steel fiber Quasi-static compressive properties Spilt Hopkinson pressure bar(SHPB) Dynamic compressive properties

Regression analysis of squeezing-induced hybrid nanofluid flow in Darcy-Forchheimer porous medium

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 193-208页

作者： k.MUHAMMAD M.SARFRAZ Department of Humanities and Sciences School of Electrical Engineering and Computer Science National University of Sciences and Technology Department of Mathematics Quaid-i-Azam University

This article presents a mathematical model addressing a scenario involving a hybrid nanofluid flow between two infinite parallel plates. One plate remains stationary, while the other moves downward at a squeezing velocity. The space between these plates contains a Darcy-Forchheimer porous medium. A mixture of water-based fluid with gold(Au) and silicon dioxide(Si O2) nanoparticles is formulated. In contrast to the conventional Fourier's heat flux equation, this study employs the Cattaneo-Christov heat flux equation. A uniform magnetic field is applied perpendicular to the flow direction, invoking magnetohydrodynamic(MHD) effects. Further, the model accounts for Joule heating, which is the heat generated when an electric current passes through the fluid. The problem is solved via NDSolve in MATHEMATICA. Numerical and statistical analyses are conducted to provide insights into the behavior of the nanomaterials between the parallel plates with respect to the flow, energy transport, and skin *** findings of this study have potential applications in enhancing cooling systems and optimizing thermal management strategies. It is observed that the squeezing motion generates additional pressure gradients within the fluid, which enhances the flow rate but reduces the frictional drag. Consequently, the fluid is pushed more vigorously between the plates, increasing the flow velocity. As the fluid experiences higher flow rates due to the increased squeezing effect, it spends less time in the region between the plates. The thermal relaxation, however, abruptly changes the temperature, leading to a decrease in the temperature fluctuations.

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