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Gradient Structured Copper by Rotationally Accelerated Shot Peening

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Journal of Materials Science & technology 2017年第7期33卷 758-761页

作者： X.Wang y.S.Li Q.Z.ang y.H.Zhao y.t.Zhu Nano Structural Materials Center School of Materials Science and Engineering Nanjing University of Science and Technology Nanjing 210094 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing 210094 China Department of Materials Science and Engineering North Carolina State University Raleigh NC 27695 USA

A new technology-rotationally accelerated shot peening（RASP）, was developed to prepare gradient structured materials. By using centrifugal acceleration principle and large steel balls, the RASP technology can produce much higher impact energy compared to conventional shot peening. As a proof-of-concept demonstration, the RASP was utilized to refine the surface layer in pure copper（Cu） with an average grain size of 85 nm. the grain size increases largely from surface downwards the bulk, forming an800 ？m thick gradient-structured surface layer and consequently a micro-hardness gradient. the difference between the RASP technology and other established techniques in preparing gradient structured materials is discussed. the RASP technology exhibits a promoting future for large-scale manufacturing of gradient materials.

关键词： Microstructure Rotationally accelerated shot peening Gradient structure Hardness Copper

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Combined approach for analysing evolutionary power spectra of a track-soil system under moving random loads

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Acta Mechanica Sinica 2019年第3期35卷 674-690页

作者： y.Zhao L.t.Si H.Ouyang State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsInternational Center for Computational MechanicsDalian University of TechnologyDalian 116023Chin School of Engineering University of LiverpoolLiverpool L69 3GHUK

the pseudo-excitation method combined with the integral transform method (PEM-ItM) is presented to investigate the ground vibration of a coupled track-soil system induced by moving random loads. Commonly in the track model, the rail, sleepers, rail pads, and ballast are modelled as an infinite Euler beam, discretely distributed masses, discretely distributed vertical springs, and a viscoelastic layer, respectively. the soil is regarded as a homogenous isotropic half-space coupled with the track using the boundary condition at the surface of the ground. By introducing a pseudo-excitation, the random vibration analysis of the coupled system is converted into a harmonic analysis. the analytical form of evolutionary power spectral density responses of the simplified coupled track-soil system under a random moving load is derived in the frequency/wavenumber domain by PEM-ItM. In the numerical examples, the effects of different parameters, such as the moving speed, the soil properties, and the coherence of moving loads, on the ground response are investigated.

关键词： track-soil system Moving random loads Evolutionary power spectrum Pseudo-excitation method Integral transform method Vibration transmission

A 3D Numerical Method for Studying Vortex Formation Behind a Moving Plate

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Communications in Computational Physics 2006年第2期1卷 207-228页

作者： t.y.Hou V.G.Stredie t.y.Wu Department of Applied and Computational Mathematics California Institute of TechnologyPasadenaCA 91125USA Department of Mechanical Engineering California Institute of TechnologyPasadenaCA 91125USA

In this paper,we introduce a three-dimensional numerical method for computing the wake behind a flat plate advancing perpendicular to the *** numerical method is inspired by the panel method of *** and ***[*** and ***,Low-speed Aerodynamics,2001]and the 2D vortex blob method of Krasny[***,Lectures in ***.,28(1991),pp.385–402].the accuracy of the method will be demonstrated by comparing the 3D computation at the center section of a very high aspect ratio plate with the corresponding two-dimensional ***,we compare the numerical results obtained by our 3D numerical method with the corresponding experimental results obtained recently by Ringuette[***,***,2004]in the towing *** numerical results are shown to be in excellent agreement with the experimental results up to the so-called formation time.

关键词： Aerodynamics vortex dynamics potential flows

Oxidation mechanism of aluminum nitride revisited

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Journal of Advanced Ceramics 2017年第1期6卷 27-32页

作者： Chun-ting yeh Wei-Hsing tUAN Department of Materials Science and Engineering 'National Taiwan University' Taipei Taiwan 106 China

Different from the oxidation kinetics of other nitrides,the oxide layer on AlN can easily reach tens of micrometers at a temperature above 1200 ℃.In the present study,the oxidation mechanism of AlN is investigated through microstructure *** analysis indicates that the oxide layer is full of small *** formation of pores generates additional surface area to induce further *** reaction thus controls the oxidation in the temperature range from 1050 to 1350 ℃.the oxidation rate becomes slow as the oxide layer reaches a critical thickness.

关键词： oxidation mechanism aluminum nitride diffusion reaction

the Optimization Design of the Nozzle Section for theWater Jet Propulsion System Applied in Jet Skis

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Computer Modeling in Engineering & Sciences 2024年第3期138卷 2277-2304页

作者： Cheng-yeh Li Jui-Hsiang Kao Department of Systems Engineering and Naval Architecture Taiwan Ocean UniversityKeelungTaiwanChina

the performance of a water jet propulsion system is related to the inlet duct,rotor,stator,and ***,the flow inlet design must fit the bottom line of the hull,and the design of the inlet duct is often limited by stern *** entire section,from the rotor to the nozzle through the stator,must be designed based on system integration in that the individual performance of these three components will influence each ***,the section from the rotor to the nozzle significantly impacts the performance of a water jet propulsion *** study focused on nozzle design and established referable analysis results to facilitate subsequent integrated studies on the design parameters regarding nozzle *** existing studies concentrate on discussions on rotor design and the tip leakage flow of rotors or have replaced the existing complex computational domain with a simple flow ***,research has yet to implement an integrated,optimal design of the section from the rotor to the *** the above,our program conducted preliminary research on this system integration design issue,discussed the optimal nozzle for this section in-depth,and proposed design suggestions based on the *** program used an existing model as the design *** study referred to the actual trial data as the design conditions for the proposed *** prior references’simple flow field form,this study added a jet ski geometry and free surface to the computational *** the linear hull shape was considered,the inflow in the inlet duct would be closer to the actual *** on the numerical calculation result,this study recommends that the optimal nozzle outlet area should be 37%of the inlet area and that the nozzle contour should be ***,for the pump head,static pressure had a more significant impact than dynamic pressure.

关键词： Water jet propulsion system rotor nozzle outlet area nozzle contour

Influence of nickel addition on the microstructure and mechanical properties of Al2O3–5vol%ZrO2 ceramic composites prepared via precipitation method

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International Journal of Minerals,Metallurgy and Materials 2019年第7期26卷 908-914页

作者： Betül Kafkasl?o?lu y?ld?z Hüseyin y?lmaz yahya Kemal tür Department of Materials Science and Engineering Gebze Technical University

the aim of this work was to investigate the microstructure and mechanical properties of 1vol%-Ni-added yttria-stabilized zirconia (ySZ) toughened alumina composites. First, Ni powders were heterogeneously precipitated in an alumina–zirconia powder mixture suspended in water;the prepared specimens were then pressureless sintered at 1550°C/2 h in a 90vol%Ar/10vol% H2 atmosphere. the structure of phases and microstructure of the composites were characterized by X-ray diffraction and scanning electron microscopy, respectively. Mechanical characterization of the specimens was carried out through Vickers hardness, Vickers indentation toughness, and three-point flexural bending tests. the fine Ni particles were homogeneously dispersed throughout the alumina matrix because of the employed processing method. Furthermore, hardness and toughness values were found to increase by 8% and 50%, respectively, with Ni addition, whereas the relative densities and flexural strength values were found to remain unchanged.

关键词： alumina zirconia ceramic matrix microstructure hardness strength toughness

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Respiratory training interventions improve health status of heart failure patients: A systematic review and network meta-analysis of randomized controlled trials

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World Journal of Clinical Cases 2019年第18期7卷 2760-2775页

作者： Mei-Hua Wang Mei-Ling yeh School of Nursing National Taipei University of Nursing and Health Sciences

BACKGROUND Prior studies indicate that doing breathing exercises improves physical performance and quality of life (QoL) in heart failure patients. However, these effects remain unclear and contradictory. AIM to determine the effects of machine-assisted and non-machine-assisted respiratory training on physical performance and QoL in heart failure patients. MEtHODS this was a systematic review and network meta-analysis study. A literature search of electronic databases was conducted for randomized controlled trials (RCts) on heart failure. Respiratory training interventions were grouped as seven categories: IMt_Pn (inspiratory muscle training without pressure or tory pressure, MIP), IMt_Pl (inspiratory muscle training with low pressure, 10%-15% MIP), IMt_Pm (inspiratory muscle training with medium pressure, 30%-40% MIP), IMt_Ph (inspiratory muscle training with high pressure, 60% MIP or MIP plus aerobics), Aerobics (aerobic exercise or weight training), Qi_Ex (tai chi, yoga, and breathing exercise), and none. the four outcomes were heart rate, peak oxygen uptake (VO2 peak), 6-min walking distance test (6MWt), and Minnesota Living with Heart Failure QoL. the random-effects model, side-splitting model, and the surface under the cumulative ranking curve (SUCRA) were used to test and analyze the data. RESULtS A total of 1499 subjects from 31 RCt studies were included. IMt_Ph had the highest effect sizes for VO2 peak and 6MWt, IMt_Pm highest for QoL, and Qi_Ex highest for heart rate. Aerobics had the second highest for VO2 peak, Qi_Ex second highest for 6MWt, and IMt_Ph second highest for heart rate and *** this study supports that high- and medium-intensity machine-assisted training improves exercise capacity and QoL in hospital-based heart failure patients. After hospital discharge, non-machine-assisted training continuously improves cardiac function.

关键词： Heart failure Network meta-analysis Respiratory training Cardiac function Exercise capacity Quality of life

Free vibration and transient response of double curved beams connected by intermediate straight beams

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 37-62页

作者： R.A.JAFARI-tALOOKOLAEI H.GHANDVAR E.JUMAEV S.KHAtIR t.CUONG-LE School of Mechanical Engineering Babol Noshirvani University of Technology Department of Mechanical Engineering Faculty of Engineering New Uzbekistan University University of Business and Science Center for Engineering Application and technology Solutions Ho Chi Minh City Open University

this paper investigates the free vibration and transient response of interconnected structures including double curved beams and intermediate straight beams,which are all constructed from functionally graded porous(FGP) materials. the strain potential and kinetic energies of each beam along with the work done by the external force are calculated. Additionally, a higher-order beam element is introduced to derive stiffness and mass matrices, along with the force vector. the curved and straight beams are discretized, and their assembled stiffness, mass matrices, and force vectors, are *** conditions at the joints are used to derive the total matrices of the entire structure. Subsequently, the natural frequencies and transient response of the system are determined. the accuracy of the mathematical model and the self-developed computer program is validated through the comparison of the obtained results with those of the existing literature and commercial software ANSyS, demonstrating excellent ***, a comprehensive study is conducted to investigate the effects of various parameters on the free vibration and transient response of the considered structure.

关键词： Kinetic energy

StRESS RELAXAtION AND RELIABILIty EVALUAtION OF SODA-LIME GLASS

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 460-464页

作者： y.W.Bao y.F.Han F.t.Gong China Building Materials Academy China Beijing 100024

Stress relaxation of glass is a dualism effect, it often lead to strength degradation in strengthened glass, but on the other hand, it improves the reliability and stress-uniformity of glasses. In this work, stress relaxation of soda-lime glass was investigated using three-point bending tests at 400-560℃ which is near the brittle to ductile transition temperature, for enhancing the safety of glass productions and exploring the most economic anneal process. the experimental results show that the speed of stress relaxation increases but the ultimate stress decreases with increasing temperature. the stress uniformity of the glass samples before and after anneal was examined using spherical indentation at arranged testing points. It indicates that the scatter of the local strength measured by the Hertzian indentation is smaller in the anneal glass than in initial specimen, so that the estimated Weibull modulus for the anneal specimen is higher. Furthermore, the strength evaluation by Hertzian indentation a

关键词： glass stress relaxation local strength reliability