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Continuum damage mechanics for sintered powder metals

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Science China(Physics,Mechanics & Astronomy) 2015年第1期58卷 95-106页

作者： yuan huang ma SongYun ZHANG Long Beijing Institute of Technology School of Mechanical Engineering University of Wuppertal Department of Mechanical Engineering

Sintered metals are characterized by the high porosity(8%)and voids/micro-cracks in *** behavior of the materials is coupled with micro-crack propagation and coalescence of open *** the present work the damage evolution of the sintered iron under multi-axial monotonic loading conditions was investigated experimentally and *** tests indicated that damage of the sintered iron initiated already at a stress level much lower than the macroscopic yield *** damage process can be divided into the stress-dominated elastic damage and the plastic damage described by the plastic *** on the uniaxial tensile tests an elastic-plastic continuum damage model was developed which predicts both elastic damage and plastic damage in the sintered iron under general multi-axial monotonic loading *** predictions agree with experiments with different multi-axial loading paths.A phenomenological continuum damage model for the sintered metal is developed based on the experimental observations to predict the inelastic behavior and damage process to failure under multi-axial loading *** proposed damage model is experimentally verified under different loading conditions.

关键词： sintered metal porous material damage evolution multi-axial damage continuum damage model

Hydration lubrication modulated by water structure at TiO2–aqueous interfaces

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Friction 2024年第4期12卷 591-605页

作者： Pingsu ma yuan LIU Ke HAN Yu TIAN Liran ma State Key Laboratory of Tribology in Advanced Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

The nature of solid-liquid interfaces is of great significance in *** advances have been made in lubrication based on hydration ***,a detailed molecular-level understanding is still ***,we investigated water molecule behaviors at the TiO2-aqueous interfaces by the sum-frequency generation vibrational spectroscopy(SFG-VS)and atomic force microscope(AFM)to elucidate the fundamental role of solid-liquid interfaces in *** contributions of water structures and hydration effects were revealed,where water structures played the dominant role in lubrication for TiO2 surfaces of varying hydrophilicity,while hydration effects dominated with the increasing of ion *** lubrication is observed on the initial TiO2 surfaces with strongly H-bonded water molecules compared to the hydrophilic TiO2 surfaces with more disordered *** stable ordered water arrangement with strong hydrogen bonds and the shear plane occurring between the ordered water layer and subsequent water layer may play a significant role in achieving lower *** adsorbed hydrated molecules with the increasing ionic concentration perturb ordered water but lead to the enhancement of hydration effects,which is the main reason for the improved lubrication for both *** work provides more insights into the detailed molecular-level understanding of the mechanism of hydration lubrication.

关键词： hydration lubrication interfacial water structures hydration effects titanium dioxide(TiO2)

Cationic Conjugated Oligomers for Efficient and Rapid Antibacterial Photodynamic Therapy via Both Type Ⅰ and Type Ⅱ Pathways

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Chinese Journal of Chemistry 2024年第1期42卷 61-66页

作者： huan Wang Shuwen Guo Qiong yuan Meiqi Li Yanli Tang Country Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province Key Laboratory of Applied Surface and Colloid ChemistryMinistry of EducationSchool of Chemistry and Chemical EngineeringShaanxi Normal UniversityXi'anShaanxi 710119China

Recently,photodynamic therapy(PDT)has attracted wide attention due to its less susceptibility to drug resistance,broad-spectrum biocidal activity and biosafety in normal ***,the traditional photosensitizers(Ps)face the disadvantage of poor therapeutic efficacy due to the requirement of an aerobic environment to generate ^(1)O_(2) through Type Ⅱ ***,we designed and synthesized a novel cationic conjugated oligomer oligo(phenylene vinylene)(OPV)and studied its antibacterial photodynamic activity against both Gram-negative Escherichia coli(***)and Gram-positive bacteria methicillin-resistant Staphylococcus aureus(MRSA).Importantly,the OpV can rapidly produce reactive oxygen species(ROs)through double pathways,Type Ⅰ and Ⅱ mechanism under white light irradiation,and efficiently kill *** and MRSA at a nanomolar *** dual type photosensitizing capability makes OPV promising for enhanced PDT to treat pathogens and tumors in complex environments.

关键词： Conjugated oligomers Antibacterial photodynamic therapy Oligo(phenylene vinylene) Reactive oxygen species Typelandll pathways

Photoinduced Intramolecular Charge Transfer in Donor-acceptor Dyad and Donor-bridge-acceptor Triad

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Chinese Journal of Chemical Physics 2008年第2期21卷 111-117页

作者： Yong Ding yuan-zuo Li Feng-cai ma Department of Physics Liaoning University Shenyang 110036 China Department of Physics Peking University Beijing 100871 China

The ground and excited state properties of the [60]fullerene, diphenylbenzothiadiazole-triphenylamine （PBTDP-TPA） dyad and fullerene-diphenylbenzothiadiazole-triphenylamine （fullerene-PBTDP-TPA） triad were investigated theoretically using density functional theory with B3LYP functional and 3-21G basis set and time-dependent density functional theory with B3LYP functional and STO-3G basis set as well as 2D and 3D real space analysis methods. The 2D site representation reveals the electron-hole coherence on excitation. The 3D transition density shows the orientation and strength of the transition dipole moment, and the 3D charge difference density gives the orientation and result of the intramolecular charge transfer. Also photoinduced intermolecular charge transfer （ICT） in PBTDP-TPA-fullerene triad are identified with 2D and 3D representations, which reveals the mechanisms of ICT in donor-bridge-acceptor triad on excitation. Besides that we also found that the direct superexchange ICT from donor to acceptor （tunneling through the bridge） strongly promotes the ICT in the donor-bridge-acceptor triad.

关键词： Donor-acceptor dyad Donor-bridge-acceptor triad Intramolecular charge transfer Superexchange

Hybrid piezo/triboelectric nanogenerator for stray magnetic energy harvesting and self‐powered sensing applications

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High Voltage 2021年第6期6卷 978-985页

作者： Aijun Yang Chaoyu Wang Jing ma Chengyu Fan Pinlei Lv Yuchen Bai Yiming Rong Xiaohua Wang huan yuan Mingzhe Rong State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityXi’anChina

Stray magnetic fields with a fixed frequency of 50/60 Hz are ubiquitous in buildings,factories,and power system *** are increasingly focusing on har-vesting electrical energy from stray magnetic fields to provide sustainable energy for the Internet of Things(IoT)***‐mechano‐electric energy conversion is the most efficient way to convert low‐frequency stray magnetic fields into *** this study,we proposed a hybrid piezo/triboelectric nanogenerator(HP/TENG)on the basis of a cantilever beam to use stray magnetic fields from the surrounding *** hybrid nanogenerator provided high output voltage/current and power of∼176 V/375μA and 4.7 mW(matched impedance of 20 kΩ)in a magnetic field environment of 4 *** device provided a stable 3.6 V direct current output by incorporating energy management circuitry to sustainably drive power to commercial wireless temperature/humidity *** HP/TENG has a significant application potential in IoT,which can use stray magnetic energy and a power wireless sensor system.

关键词： IoT generator magnetic

Recent developments in novel silica-based optical fibers

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Frontiers of Information Technology & Electronic Engineering 2019年第4期20卷 481-489页

作者： Ting-yun WANG Fu-fei PANG Su-juan huanG Jian-xiang WEN huan-huan LIU Li-bo yuan Key Laboratory of Specialty Fiber Optics and Optical Access Networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication Shanghai Institute for Advanced Communication and Data ScienceShanghai University Photonics Research Center Guilin University of Electronic Technology

We have summarized our recent work in the area of novel silica-based optical fibers, which can be classified into two types: silica optical fiber doped with special elements including Bi, Al, and Ce, and micro-structured multi-core fibers. For element-doped optical fiber, the Bi/Al co-doped silica fibers could exhibit a fluorescence spectrum covering the wavelength range between 1000 and 1400 nm with a full width at half maximum(FWHM) of about 150 nm, which enables its use in fiber amplifiers and laser systems. The Ce-doped fiber's center wavelengths of excitation and emission are about 340 and 430 nm, respectively. The sapphire-derived fiber(SDF) with high alumina dopant concentration in the core can form mullite through heating and cooling with arc-discharge treatment. This SDF can be further developed for an intrinsic Fabry-Perot interferometric that can withstand 1200 ℃, which allows it to be used in high-temperature sensing applications. Owing to the strong evanescent field, microstructured multi-core fiber can be used in a wide range of applications in biological fiber optic sensing, chemical measurement, and interference-related devices. Coaxial-core optical fiber is another novel kind of silica-based optical fiber that has two coaxial waveguide cores and can be used for optical trapping and micro-particle manipulation by generating a highly focused conical optical field. The recent developments of these novel fibers are discussed.

关键词： Optical fiber Fiber optic device Silica-based special fiber

Determination of spatial resolution of plastic scintillation fiber array with a simple method

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Nuclear Science and Techniques 2007年第2期18卷 111-114页

作者： TANG Shibiao ma Qingli YIN Zejie huanG huan Department of Modern Physics University of Science and Technology of China Hefei 230027 China Electronics Department Electronic Engineering Institute Hefei 230038 China

The spatial resolution of a position sensitive gamma-ray detector configuration based on plastic scintillation fiber array was measured using a Monte Carlo simulation method. Both point spread function and modulation transfer function (MTF) were presented. The factors that influence the spatial resolution were also discussed. The results of the simulation showed that the intrinsic spatial resolution was consistent with the size of the physical pixels and a few centimeters spatial resolution could be obtained under certain circumstances.

关键词：塑料闪烁光纤阵空间分辨率测定简单方法

Sociological Reflection on Live Broadcast Form Alternation

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学术界 2017年第12期 310-321页

作者： ma yuan School of Journalism and Communication Wuhan University School of Journalism and Communication Anhui Normal University

Live broadcast refers to a television broadcast mode that compresses the space time,and synchronously transmits with the occurrence of events,and along with the development of internet technology,the live broadcast form that takes network and mobile network as the carrier comes into existence. T his new broadcast form has eliminated the physical context of traditional live broadcast and the boundary line of information context,realized context virtualization,fragmentization and socialization,and built a new relation context. In such a context,on one hand,t he live broadcast subject uses individuals to replace the media organization; on the other hand,t he transaction behaviors among individuals constitute new communities with mobility and interaction,and this has reflected the individual structure characteristics of post-modern society,and the social practice of"disembedding"and"re-embedding". However,network live broadcast also brings the carnival of sensibility consumption,the addiction of virtual narcissism as well as the spectacle of post-modern society. In the face of human alienation and social hidden worries,there is no doubt that the post-modern reflection in marxist theory has important significance and value.

关键词： network live broadcast context individuality community

Simulation study of BGO array for characteristic gamma rays from neutron-stimulated elements

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Nuclear Science and Techniques 2007年第6期18卷 354-357页

作者： TANG Shibiao ma Qingli YIN Zejie huanG huan Department of Modern Physics University of Science and Technology of China Hefei 230026 China Electronics Department Electronic Engineering Institute Hefei 230038 China

Characteristic gamma rays of 100 keV to about 6 MeV from different elements stimulated by neutrons have been applied to diagnosis biological *** this paper,BGO detectors are used for the spectrum simulation. Signals from a single crystal and after correction are both obtained,and the energy spectrum summing adjacent signals seems possible to achieve excellent energy resolution for such high-energy *** ideal suppositions are in- troduced and some other information,such as spatial resolution and difficult electronics,should be considered after this correction.

关键词： α射线能量光谱 BGO 中子