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High strength Al-Cu-mg based alloy with synchronous improved tensile properties and hot-cracking resistance suitable for laser powder b e d fusion

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Journal of materials Science & Technology 2023年第10期141卷 155-170页

作者： Q.Z.Wang N.Kang X.Lin m.EL mansori W.d.Huang State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Arts et metiers Institute of Technology MSMPHESAM UniversitéChâlons-en-Champagne F-51006France Key Laboratory of metal High Performance Additive manufacturing and Innovative design MIIT ChinaNorthwestern Polytechnical UniversityXi’an 710072China Texas A&m Engineering Experiment Station Institute for Manufacturing SystemsCollege StationTX 77843USA

In present work,a novel crack-free Al-Cu-mg-Si-Ti alloy with synchronous improved tensile properties and hot-cracking resistance was proposed and successfully manufactured by laser powder bed fusion(LPBF).The microstructure evolution behaviors and the corresponding strengthening mechanisms were investigated in *** LPBF-processed Al-Cu-mg-Si-Ti alloy presents a heterogeneous microstructure consisting of ultrafine equiaxed grains(UFGs)at the boundary and coarse columnar grains(CGs)at the center of the single molten ***-precipitated d022-Al 3 Ti particles were found to act as the nuclei to refine the grains at the boundary of the molten pool during solidification process,which is attributed to the low cooling rate providing the sufficient incubation time for the precipitation of d022-Al 3 *** are two orientation relationships(ORs)betweenα-Al and d022-Al 3 Ti,i.e.[001]α-Al//[001]d022-Al3Ti,(200)α-Al//(200)d022-Al3Ti and[1¯1¯2]α-Al//[¯111]d022-Al3Ti,(1¯11)α-Al//(¯11¯2)d022-Al3Ti,which are two of the eight ORs predicted with the E2Em *** grains in present alloy,no matter for UFGs or CG,exhibited high critical hot-cracking stress,which means a strong hot-cracking ***-nanoprecipitation of Cu-,mg-,and Si-rich Q’and S’phases was introduced to enhance the mechanical performance ofα-Al *** as-built sample exhibits superior tensile properties,with the yield strength(YS)of 473±8 mPa,ultimate tensile strength(UTS)of 541±2 mPa and elongation(EI)of 10.9%±1.2%.

关键词： Laser powder bed fusion High strength Al-Cu-mg alloys duplex microstructure Precipitation Tensile properties

Electrons matter in ferromagnetic criticality

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Science Bulletin 2021年第14期66卷 1369-1371页

作者： Joe d.Thompson jon m.Lawrence Los Alamos National Laboratory Los AlamosNM 87545USA University of California IrvineCA 92697USA

When elemental iron is cooled from high temperatures,magnetic moments carried by its d-electrons begin a continuous transition to a state of parallel aligned moments below its Curie temperature T_(C)of about 1040 *** established in the m.d.1900s,the statistical physics of this second order phase transition is universal,independent of the ordering temperature,material structure and chemical composition as well as the character of moment-bearing electrons.

关键词： transition 铁磁 character

A NUmERICAL mETHOd FOR THE SImULATION OF FREE SURFACE FLOWS OF VISCOPLASTIC FLUId IN 3d

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Journal of Computational mathematics 2011年第6期29卷 605-622页

作者： Kirill d. Nikitin maxim A. Olshanskii Kirill m. Terekhov Yuri V. Vassilevski Institute of Numerical mathematics Russian Academy of Sciences Moscow Russia department of mechanics and mathematics Moscow State University Moscow Russia

In this paper we study a numerical method for the simulation of free surface flows of viscoplastic （Herschel-Bulkley） fluids. The approach is based on the level set method for capturing the free surface evolution and on locally refined and dynamically adapted octree cartesian staggered grids for the discretization of fluid and level set equations. A regu- larized m.d.l is applied to handle the non-differentiability of the constitutive relations. We consider an extension of the stable approximation of the Newtonian flow equations on staggered grid to approximate the viscoplastic m.d.l and level-set equations if the free boundary evolves and the mesh is dynamically refined or coarsened. The numerical method is first validated for a Newtonian case. In this case, the convergence of numerical solutions is observed towards experimental data when the mesh is refined. Further we compute several 3d viscoplastic Herschel-Bulkley fluid flows over incline planes for the dam-break problem. The qualitative comparison of numerical solutions is done versus experimental investigations. Another numerical example is given by computing the freely oscillating viscoplastic droplet, where the motion of fluid is driven by the surface tension forces. Altogether the considered techniques and algorithms （the level-set method, compact discretizations on dynamically adapted octree cartesian grids, regularization, and the surface tension forces approximation） result in efficient approach to m.d.ling viscoplastic free-surface flows in possibly complex 3d geometries.

关键词： Free surface flows Viscoplastic fluid Adaptive mesh refinement Oetree meshes.

Evaluation of 1031 primary titanium nitride coated mobile bearing total knee arthroplasties in an orthopedic clinic

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World Journal of Orthopedics 2017年第12期8卷 922-928页

作者： Stefan J m Breugem Jeroen Linnartz Inger Sierevelt jon d Bruijn marcel J m.d.iessen Orthopedium Orthopedic Clinic Slotervaart Hospital

AIm To evaluate the influence of the titanium nitride(TiN) coating on the results of a total knee arthroplasty(TKA). mETHOdS A total of 910 patients(338 men; 572 woman), with a mean age of 65(range 36-94) undergoing 1031 primary TKAs were assessed. Clinical evaluation and patientreported outcomes were gathered one year after surgery. The questionnaires included the Knee injury and Osteoarthritis Outcome Score(KOOS)-dutch version, Visual Analogue Scale(VAS) pain scores in rest and during active knee movement, VAS-satisfaction scores, and EQ-5 d-3 L health scores. This was aim.d.to assess the overall knee function and patient satisfaction, and to enable us to make a gross comparison to other *** At a mean follow-up of 46 mo(range 1-92) the overall implant survival was 97.7% and 95.1% for any operative reason related to the implant. Twenty-three knees(2.2%) required revision surgery. Arthrofibrosis was the most common indication for a re-operation. The clinical evaluation and patient-reported outcomes revealed good to excellent patient satisfaction and function of the arthroplasty. The m.d.an postoperative VAS-pain scores on a scale of 0-100, at one year after surgery were 1 in rest and 2 during *** The Ti N coated, mobile bearing TKA results are excellent and similar to those of other widely used TKA designs. Residual pain of the knee remains a concern and the Ti N coating in combination with the mobile bearing does not seem to be the simple solution to this problem. Future research will have to show that the coating gives a better survival than the cobalt chrome version.

关键词： Total knee arthroplasty Titanium nitride coating mobile bearing Pain Satisfaction and survival

Prediction and analysis of process failures by ANN classification during wire-Edm of Inconel 718

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Advances in manufacturing 2020年第4期8卷 519-536页

作者： Abhilash P.m. Chakradhar d. department of mechanical Engineering Indian Institute of Technology PalakkadPalakkadKeralaIndia

Wire breakages and spark absence are two typical machining failures that occur during wire electric discharge machining(wire-Edm),if appropriate parameter settings are not *** after several attempts to optimize the process,machining failures cannot be eliminated completely.A n offline classification m.d.l is presented herein to predict machining *** aim of the current study is to develop a multiclass classification m.d.l using an artificial neural network(ANN).The training dataset comprises 81 full factorial experiments with three levels of pulse-on time,pulse-off time,servo voltage,and wire feed rate as input *** classes are labeled as normal machining,spark absence,and wire *** m.d.l accuracy is tested by conducting 20 confirmation experiments,and the m.d.l is discovered to be 95%accurate in classifying the machining *** effects of process parameters on the process failures are discussed and analyzed.A microstructural analysis of the machined surface and worn wire surface is *** developed m.d.l proved to be an easy and fast solution for verifying and eliminating process failures.

关键词： Wire electric discharge machining(wire-Edm) Process failure Spark absence Wire breakage Artificial neural network(ANN)classification Failure prediction

Efficient approaches of determining the motion of a spherical particle in a swirling fluid flow using weighted residual methods

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Particuology 2015年第6期13卷 68-74页

作者： Seiyed E. Ghasemi m. Vatani d.d. Ganji Young Researchers and Elite Club Qaemshahr Branch Islamic Azad University Qaemshahr lran department of mechanical Engineering Babol University of Technology Babol lran

The motion of a spherical particle released in a swirling fluid flow is studied employing the least-squares method and method of moments. The governing equations are obtained and solved employing the two methods. The accuracy of the results is examined against the results of a fourth-order Runge-Kutta numer- ical method. The effects of various parameters, namely the initial radius, initial radial velocity, initial angular velocity, and drag-to-inertia ratio, on the non-dimensional velocity profiles and particle position distribution are considered. The results show that the radial velocity increases over time while the angular velocity decreases, and that an increase in the initial radial velocity increases the particle radial distance and angular velocity but decreases the radial velocity profile.

关键词： Spherical particle Swirling flow Radial velocity Angular velocity Least-squares method method of moments

Computational Studies of Flow through Cross Flow Fans-Effect of Blade Geometry

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Journal of Thermal Science 2005年第3期14卷 220-229页

作者： m . GOVARdHAN d. LAKSHmANA SAmPAT School of mechanical Engineering Universiti Malaysia Sabah Sabah Malaysia ProfessorThermal Turbomachines Laboratory Department of Mechanical Engineering Indian Institute of Technology Madras Chennai India

This present paper describes three dimensional computational analysis of complex internal flow in a cross flow fan. A commercial computational fluid dynamics (CFd) software code CFX was used for the computation. RNG k-ε two equation turbulence m.d.l was used to simulate the m.d.l with unstructured mesh. Sliding mesh interface was used at the interface between the rotating and stationary domains to capture the unsteady interactions. An accurate assessment of the present investigation is m.d. by comparing various parameters with the available experimental data. Three impeller geometries with different blade angles and radius ratio are used in the present study. maximum energy transfer through the impeller takes place in the region where the flow follows the blade curvature. Radial velocity is not uniform through blade channels. Some blades work in turbine m.d. at very low flow coefficients. Static pressure is always negative in and around the impeller region.

关键词： cross flow fans computational fluid dynamics quasi steady state multiple frames of reference

Evolution of X-pinch loads for pulsed power generators with current from 50 to 5000 kA

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matter and Radiation at Extremes 2018年第6期3卷 267-277页

作者： T.A.Shelkovenko S.A.Pikuz I.N.Tilikin m.d.mitchell S.N.Bland d.A.Hammer Cornell University IthacaNY14850USA P.N.Lebedev Institute Moscow119991Russia Blackett Laboratory Imperial College LondonLondonSW72AZUK University of Evansville EvansvilleINUSA

A review of X-pinches of various configurations and of different materials as an X-ray source for various applications is presented. Theadvantages and disadvantages of different designs of X-pinches as a load for generators with a wide range of output parameters and as a sourceof X-ray radiation for X-ray point-projection imaging were analyzed.

关键词： X-pinch X-ray source X-ray point-projection imaging

Effect of p-d exchange with an itinerant carrier in a GamnAs quantum.d.t

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Journal of Semiconductors 2013年第7期34卷 1-6页

作者： d.Lalitha A.John Peter department of Physics GTN College department of Physics Government Arts College

Hydrogenic acceptor binding energy as a function of dot radius in a GamnAs/Ga_（0.6）Al_（0.4）As quantum.d.t is calculated including the exchange interaction of mn alloy content with an itinerant *** are perform.d.by varying its dot radius,for various mn alloy contents in GamnAs quantum.d.t within a single band effective mass approximation using variational *** spin polaronic energy of the acceptor impurity for different mn^（2＋） is evaluated for different dot radii using a mean field theory in the presence of magnetic field *** magnetization is computed in the influence of magnetic field and the mn *** effective g-factor of the valence band electron with the inclusion of effects of mn ion impurities is found in the influence of the magnetic *** exchange coupling constant is calculated for various magnetic field *** results show that the p-d exchange interaction in the GamnAs/Ga_（0.6）Al_（0.4）As quantum.d.t has a strong dependence on spatial confinement,effect of magnetic field strength and the mn alloy *** results are in good agreement with the other investigators.

关键词： quantum.d.t acceptor diluted magnetic semiconductors