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Tensile and compression properties of Zr-based bulk amorphous alloy at different temperatures

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Science China(Technological Sciences) 2005年第5期48卷 489-495页

作者： WANG Xu1,3, LOU Decheng1, GAO Zhanjun4. LIU Lei1, LIANG Hongmei1, WANG Qingfeng1, LI Qiang1,3 & ma Mingzhen1,2 1. Key Laboratory of Metastable materials Science & Technology of Hebei, Yanshan university, Qinhuangdao 066004. China 2. National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001, China 3. College of mechanical engineering, Yanshan university, Qinhuangdao 066004. China 4. Chinese Academy of engineering, Beijing 100038, China Key Laboratory of Metastable materials Science & Technology of Hebei Yanshan University

mechanical properties of the Zr4.Ti14.u12.5Ni10Be22.5 bulk amorphous alloy at different temperatures were investigated. The compression test was carried out on a Gleebe-3200 machine at 34. and 375°C, respectively, in the supercooled liquid region. It is shown that decreasing the compressive rate and increasing temperature have a similar influence trend on the compressive behavior of the bulk amorphous alloy. Room and low temperature tensile strengths were tested on the Instron materials testing system. At low temperature, the tensile strength decreased with decreasing of the testing temperature. Hardness measurement indicated that below the glass transition temperature, the hardness decreased with increasing of the annealing temperature and duration time. It, however, increased when the annealing treatment was performed above the glass transition temperature.

关键词： Zr4.Ti14.u12.5Ni10Be22.5 bulk amorphous alloy, mechanical properties, compressive deformation.

A COMPUTATIONAL STUDY ON BACKWARDS WI MMING HYDRODYNAMICS IN THE EELANGUILLA ANGUILLA

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Journal of Hydrodynamics 2005年第4期17卷 438-447页

作者： HU Wen-rong TONG Bin-gang ma Hui-yang LIU Hao department of Physics Graduate School of the Chinese Academy of Sciences Beijing 100039 China department of engineering Mechanics Shanghai Jiaotong University Shanghai 200240 China department of Electronics and mechanical engineering Chiba University Japan

Eels can perform both forward and backward undulatory swimming but few studies are seen on how eels propel themselves backward. A computational study on the unsteady hydrodynamicsoof the backward swimming in the eel anguilla anguilla is carried out and presented. A two-dimensional geometric model of the European eel body in its middle horizontal section is appropriately approximated by a NACA0005 airfoil. Kinematic data of the backward and forward swimming eel used in the computational modeling are based on the experimental results of the European eel. Present study provided the different flow field characteristics of three typical cases in the backward swimming, and confirmed the guess of Wu： When the eel swims steadily, the vortex centers of the reversed von Kármán vortex street are aligned approximately. An extensive comparison between the backward and forward swimming further reveals that the controllable parameters, such as frequency, amplitude and wavelength of the traveling wave, have a similar influence on the propulsion performance as in forward swimming. But it is shown that the backward swimming does not be a ＂reversed＂ forward swimming one. The backward swimming does show significant discrepancy in the propulsion performance： utilization of a constant-amplitude wave profile enables larger force generation for maneuverability but with much lower propulsive efficiency instead of the linear-increasing amplitude wave profile in the forward swimming. The actual swimming modes eels choose is the best choice associated with their propulsive requirement, as well as their physiological and ecological adaptation.

关键词： anguilla anguilla backward swimming hydrodynamics 2-D N-S equation solution

Tuning mechanical and electrical performances of B_(4.C-TiB_(2)ceramics in a two-step spark plasma sintering process

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Journal of Advanced Ceramics 2024年第4期13卷 518-528页

作者： Jun Zhao Xingshuo Zhang Zongning ma Dong Wang Xing Jin Songlin Ran Advanced Ceramics Research Center School of Materials Science and EngineeringAnhui University of TechnologyMaanshan 243002China Anhui engineering Research Center for High Efficiency Intelligent Photovoltaic Module Chaohu UniversityHefei 238024China

B_(4.C–TiB_(2)is an advanced electrically conductive ceramic with excellent mechanical and electrical discharge machinable *** is challenging and rewarding to achieve highly conductive and hard B_(4.C–TiB_(2)composites at a minimum content of conductive TiB2 that has inferior hardness but double specific gravity of the B_(4.C matrix.A novel strategy was used to construct conductive networks in B_(4.C‒15 vol%TiB2 composite ceramics with B_(4.C,TiC,and amorphous B as raw materials by a two-step spark plasma sintering *** influences of particle size matching between B_(4.C and TiC on the conducting of the strategy and the microstructure were discussed based on the selective matrix grain growth *** mechanical and electrical properties were also systematically *** B_(4.C–15 vol%TiB2 composite ceramic prepared from 10.29µm B_(4.C and 0.05µm TiC powders exhibited a perfect three-dimensional interconnected conductive network with a maximum electrical conductivity of 4.25×10^(4.S/m,together with excellent mechanical properties including flexural strength,Vickers hardness,and fracture toughness of 691±58 MPa,30.30±0.61 GPa,and 5.75±0.32 MPa·m^(1/2),respectively,while the composite obtained from 3.12µm B_(4.C and 0.8µm TiC powders had the best mechanical properties including flexural strength,Vickers hardness,and fracture toughness of 827±35 MPa,32.01±0.51 GPa,and 6.4.±0.22 MPa·m^(1/2),together with a decent electrical conductivity of 0.65×10^(4.S/m.

关键词： B_(4.C-TiB_(2) mechanical properties electrical conductivity conductive network

The　Treatment　of　Non-zero　Slacks　in　Data　Envelopment　Analysis

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Journal of Systems engineering and Electronics 1997年第1期8卷 46-50页

作者： Hu Hanhui ( School of management , Southeast university, Nanjing 210018, P. R. China ) Joe Zhu( department of mechanical and lndustrial engineering, university of massacbusetts, Amherst, ma 01003, usa ) School of management southeast University Nanjing 210018 P. R. China department of mechanical and Industrial engineering University of Massachusetts Amherst MA 01003 USA

The paper studies the non-zero slacks in data envelopment analysis. A procedure is developed for the treatment of non-zero slacks. DEA projections can be done just in one step.

关键词： Data envelopment analysis (DEA) Slack Efficient Multiplier.

Skin-inspired interface modification strategy toward a structurefunction integrated hybrid smart fabric system with self-powered sensing property for versatile applications

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Nano Research 2024年第9期17卷 8200-8208页

作者： Xiang Cheng Teng Chen De Gong Pengcheng ma Bo Chen Jun Cai aerospace Information Research Institute Chinese Academy of SciencesBeijing 100190China School of mechanical engineering and Automation Beihang UniversityBeijing 100191China Beijing U-Precision Tech Co. Ltd.Beijing 100176China university of Chinese Academy of Sciences Beijing 100049China

Fabric-based composites with superior mechanical properties and excellent perceptive function are highly ***,it remains a huge challenge to attain structure-function integration,especially for hybrid fabric ***,a skin-inspired interface modification strategy is proposed toward this target by constructing a hybrid smart fabric system consisting of two types of smart fabrics:carbon nanotube(CNT)/MXene-modified aramid fabrics and zinc oxide nanorod(ZnO NR)-modified carbon *** on that,flexible piezoelectric pressure sensors with skin-like hierarchical perception interfaces are fabricated,which demonstrate superb sensitivity of 2.39 V·kPa^(-1)and are capable of various wearable monitoring ***,the interface-modified hybrid fabric reinforced plastics can also be fabricated,which are proven to possess 13.6%higher tensile strength,10.1%elastic *** impressively,their average energy absorption can be improved by 111.9%,accompanied with inherent damage alert *** offers a paradigm to fabricate structure-function integrated hybrid smart fabric composites for the smart clothing and intelligent aerial vehicles.

关键词： hybrid fabrics interface modification piezoelectric pressure sensors self-diagnostic composites structure-function integration

Incorporating Lasso Regression to Physics-Informed Neural Network for Inverse PDE Problem

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Computer Modeling in engineering & Sciences 2024年第10期141卷 385-399页

作者： Meng ma Liu Fu Xu Guo Zhi Zhai National Key Lab of aerospace Power System and Plasma Technology Xi’an Jiaotong UniversityXi’an710049China School of mechanical engineering Xi’an Jiaotong UniversityXi’an710049China department of Electrical and Computer engineering University of Massachusetts LowellLowellMA 01854USA

Partial Differential Equation(PDE)is among the most fundamental tools employed to model dynamic *** PDE modeling methods are typically derived from established knowledge and known phenomena,which are time-consuming and ***,discovering governing PDEs from collected actual data via Physics Informed Neural Networks(PINNs)provides a more efficient way to analyze fresh dynamic systems and establish *** study proposes Sequentially Threshold Least Squares-Lasso(STLasso),a module constructed by incorporating Lasso regression into the Sequentially Threshold Least Squares(STLS)algorithm,which can complete sparse regression of PDE coefficients with the constraints of l0 *** further introduces PINN-STLasso,a physics informed neural network combined with Lasso sparse regression,able to find underlying PDEs from data with reduced data requirements and better *** addition,this research conducts experiments on canonical inverse PDE problems and compares the results to several recent *** results demonstrated that the proposed PINN-STLasso outperforms other methods,achieving lower error rates even with less data.

关键词： Physics-informed neural network inverse partial differential equation Lasso regression scientific machine learning

Elasticity meets topology

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National Science Review 2024年第06期 84-85页

作者： Guancong ma department of Physics Hong Kong Baptist University

We are surrounded by environments and items that are made from solid materials in our daily life. Any physical contact with any items is a mechanical disturbance that produces mechanical *** underlines the crucial role that such vibrations play in our daily interactions,highlighting the need for a deeper understanding and improved manipulation of these fundamental phenomena.

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Grating-free autofocus for single-pixel microscopic imaging

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Photonics Research 2024年第6期12卷 1313-1321页

作者： GUAN WANG HUAXIA DENG YU CAI MENGCHAO ma XIANG ZHONG XINGLONG GONG CAS Key Laboratory of mechanical Behavior and Design of materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230027China School of Instrument Science and Opto-electronics engineering Hefei University of TechnologyHefei 230009China

As a computational technology,single-pixel microscopic imaging(SPMI)transfers the target’s spatial information into a temporal *** traditional focusing method of imaging before evaluation is not applicable to the SPMI *** propose a grating-free autofocus strategy derived from the physical mechanism of optical *** the amplitude information of just one high-frequency point in the spectrum is all that is needed to achieve fast autofocus with the SPMI ***,only four patterns need to be cyclically projected,enabling efficient localization of the focal plane based on the measurement *** demonstrate SPMI autofocus experiments at micrometer and even nanometer depths of *** proposed method can be extended to achieve SMPI autofocus with invisible optical pattern illumination.

关键词： optical system illumination

A Reconstructed Discontinuous Galerkin Method for Compressible Flows on Arbitrary Grids

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A Reconstructed Discontinuous Galerkin Method for Compressib...