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Breaking the barriers: advances in acoustic functional materials

National Science Review 2018年第2期5卷 159-182页

作者： Hao Ge Min Yang Chu Ma ming-Hui Lu Yan-feng Chen Nicholas Fang Ping sheng National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering College of Engineering and Applied SciencesNanjing University Department of Physics Hong Kong University of Science and Technology Department of Mechanical Engineering Massachusetts Institute of Technology Collaborative Innovation Center of Advanced Microstructures Nanjing University

Acoustics is a classical field of study that has witnessed tremendous developments over the past 25 *** by the novel acoustic effects underpinned by phononic crystals with periodic modulation of elastic building blocks in wavelength scale and acoustic metamaterials with localized resonant units in subwavelength scale, researchers in diverse disciplines of physics, mathematics, and engineering have pushed the boundary of possibilities beyond those long held as unbreakable limits. More recently, structure designs guided by the physics of graphene and topological electronic states of matter have further broadened the whole field of acoustic metamaterials by phenomena that reproduce the quantum effects classically. Use of active energy-gain components, directed by the parity–time reversal symmetry principle,has led to some previously unexpected wave characteristics. It is the intention of this review to trace historically these exciting developments, substantiated by brief accounts of the salient milestones. The latter can include, but are not limited to, zero/negative refraction, subwavelength imaging, sound cloaking, total sound absorption, metasurface and phase engineering, Dirac physics and topology-inspired acoustic engineering, non-Hermitian parity–time synthetic active metamaterials, and one-way propagation of sound waves. These developments may underpin the next generation of acoustic materials and devices, and offer new methods for sound manipulation, leading to exciting applications in noise reduction, imaging, sensing and navigation, as well as communications.

关键词： acoustic metamaterials phononic crystals topological acoustics PT-symmetry synthetic acoustics sound absorption

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Combined Impacts of Antecedent Earthquakes and Droughts on Disastrous Debris Flows

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Journal of Mountain Science 2014年第6期11卷 1507-1520,1-6页

作者： CHEN Ning-sheng LU Yang ZHOU Hai-bo DENG ming-feng Han Da-wei Key Laboratory of Mountain Hazards and Surface Processes Institute of Mountain Hazards and Environment Chinese Academy of Sciences Changjiang River Scientific Research Institute Sichuan Provincial Transport Department Highway Planning Survey Design and Research Institute Department of Civil Engineering University of Bristol

This paper describes a study on the combined impacts of antecedent earthquakes and droughts on disastrous debris *** is a novel attempt in quantifying such impacts using the effective peak acceleration(EPA)(to represent earthquakes) and standardized precipitation index(SPI)(to represent droughts).The study is based on the analysis of 116 disastrous debris flow events occurred in China's Mainland in the last 100 years covering a wide spectrum of climate types and *** has been found that the combined impacts from earthquakes and droughts on disastrous debris flows do exist and vary from low to very high according to different climate conditions and *** impacts from earthquakes increase with the increased terrain relief,and the impacts from droughts are strongest in semi-humid climate condition(with reduced impacts in humid and semi-arid /arid climate conditions).Hypothetical explanations on the study discoveries have been *** study reveals the possible reasons for the disastrous debris flow distributions around the world and has significant implications in paleo-climate-seismicanalysis and disastrous debris flow risk management.

关键词： Debris flow Erosion Earthquake Drought Natural hazard

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Novel Synthesis of Sol-gel Derived Nanosized Mullite Powder

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Chinese Journal of Aeronautics 2006年第B12期19卷 71-73页

作者： LIANG Long LI Jian-bao LIN Hong GUO Gang-feng HE ming-sheng State Key Lab of New Ceramics and Fine Processing Dept of Materials Science and Engineering Tsinghua University Beijing 100084 China

Using hydrous aluminum chloride （AlCl3·6H2O） and silicon ethoxide （Si （OC2H5）4） as raw materials, a kind of nano-sized mullite powder was synthesized with the sol-gel process at the medium calcination temperature. The microstructures of the alumina-silica binary aerogel and calcined nano-sized materials were investigated by means of thermogravimetry-differential thermal analysis （TG-DTA）, scanning electron microscopy （SEM） and X-ray diffractometer （XRD）. The results show that the mullitization of Al2O3-SiO2 in gel starts from about 1 000℃ and its formation ofmullite takes place in the range of 1 100℃-1 250 ℃. The size of the nano-sized mullite powder calcined at 1 250 ℃ is measured to be about 30 nm.

关键词： mullite sol-gel synthesis temperature

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Tunable synchrotron-like radiation from centimeter scale plasma channels

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Light(Science & Applications) 2016年第1期5卷 819-825页

作者： Min Chen Ji Luo Fei-Yu Li feng Liu Zheng-ming sheng Jie Zhang Key Laboratory for Laser Plasmas(MOE) Department of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA(CICIFSA) Shanghai Jiao Tong UniversityShanghai 200240China SUPA Department of PhysicsUniversity of StrathclydeGlasgow G40NGUK

Synchrotron radiation(SR)sources are immensely useful tools for scientific researches and many practical ***,the state-of-the-art synchrotrons rely on conventional accelerators,where electrons are accelerated in a straight line and radiate in bending magnets or other insertion ***,these facilities are usually large and ***,we study a compact all optical synchrotron-like radiation source based on laser-plasma acceleration either in a straight or a curved plasma *** the laser pulse off-axially injected,its centroid oscillates transversely in the plasma *** results in a wiggler motion of the whole accelerating structure and the self-trapped electrons behind the laser pulse,leading to strong synchrotron-like radiations with tunable *** is further shown that a palmtop ring-shaped synchrotron is possible with current high power laser *** its potential of high flexibility and tunability,such light sources once realized would find applications in wide areas and make up the shortage of large SR facilities.

关键词： laser guiding laser wakefield acceleration synchrotron radiation

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Carrier Dynamics Determined by Carrier-Phonon Coupling in InGaN/GaN Multiple Quantum Well Blue Light Emitting Diodes

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Chinese Physics Letters 2019年第2期36卷 92-95页

作者： sheng Cao Xiao-ming Wu Jun-Lin Liu feng-Yi Jiang National Institute of LED on Si Substrate Nanchang University

Phonon sidebands in the electrolumiescence(EL) spectra of InGaN/GaN multiple quantum well blue light emitting diodes are investigated. S-shaped injection current dependence of the energy spacing(ES) between the zero-phonon and first-order phonon-assisted luminescence lines is observed in a temperature range of 100–150 *** S-shape is suppressed with increasing temperature from 100 to 150 K, and vanishes at temperature above200 K. The S-shaped injection dependence of ES at low temperatures could be explained by the three stages of carrier dynamics related to localization states:(i) carrier relaxation from shallow into deep localization states,(ii) band filling of shallow and deep localization states, and(iii) carrier overflow from deep to shallow localization states and to higher energy states. The three stages show strong temperature dependence. It is proposed that the fast change of the carrier lifetime with temperature is responsible for the suppression of S-shaped *** proposed mechanisms reveal carrier recombination dynamics in the EL of InGaN/GaN MQWs at various injection current densities and temperatures.

关键词： Carrier Dynamics Determined Carrier-Phonon Coupling InGaN/GaN Multiple Quantum Well Blue Light Emitting Diodes

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Influence of niobium and yttrium on plastic deformation energy and plasticity of Ti-based amorphous alloys

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China Foundry 2021年第1期18卷 60-67页

作者： sheng-feng Shan Hao Wang Bing Zhang Yuan-zhi Jia ming-zhen Ma Department of Physics Jining UniversityQufu273155China Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesNingbo315201China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao066004China

Many amorphous alloys have been developed to date,but the low plasticity has limited their *** achieve an amorphous alloy with high plasticity,a series of(Ti_(40)Zr_(25)Cu_(9)Ni_(8) Be_(18))_(100-x)TM_(x)(x=0,1,2,3,4 at.%,TM=Nb,Y)alloys were designed to study the influence of Nb and Y addition on the *** amorphous samples were prepared using the vacuum melting and copper mold casting *** microstructures,glass forming ability and mechanical properties of the alloys were investigated by X-ray diffractometry(XRD),scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),depth-sensitive nanoindentation,and uniaxial compressive *** plasticity of different bulk amorphous alloys was investigated by measuring the plastic deformation energy(PDE)during *** relationship between the PDE value and plasticity in bulk amorphous alloys was *** show that Nb addition decreases the PDE value and promotes the generation of multiple shear bands,which significantly increases the fracture strength and plasticity,while the addition of Y element reduces the fracture strength and plastic strain of the alloy.

关键词： copper mold casting bulk amorphous alloy plastic deformation energy plasticity

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Future Digital Design and Manufacturing: Embracing Industry 4.0 and Beyond

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Chinese Journal of Mechanical Engineering 2017年第5期30卷 1047-1049页

作者： sheng-feng Qin Kai Cheng School of Design Northumbria University College of Engineering Design and Physical SciencesBrunel University London

Digital design and manufacturing have been around for several decades from the numerical control of machine tools and automating engineering design in 1960s, through early Computer Aided Design （CAD）/Computer Aided Engineering analysis （CAE）/Computer Aided Manufacturing （CAM）, to modem digital design and manufacturing [1], and cloud manufacturing [2] converging into product lifecycle management （PLM） [3, 4] and Internet-enabled personalized manufacturing [5].

关键词： Digital design Future manufacturing Industry 4.0

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Development and progress on hydrogen metallurgy

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International Journal of Minerals,Metallurgy and Materials 2020年第6期27卷 713-723页

作者： Jue Tang Man-sheng Chu feng Li Cong feng Zheng-gen Liu Yu-sheng Zhou School of Ferrous Metallurgy Northeastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

Hydrogen metallurgy is a technology that applies hydrogen instead of carbon as a reduction agent to reduce CO2 emission,and the use of hydrogen is beneficial to promoting the sustainable development of the steel *** metallurgy has numerous applications,such as H2reduction ironmaking in Japan,ULCORED and hydrogen-based steelmaking in Europe;hydrogen flash ironmaking technology in the US;HYBRIT in the Nordics;Midrex H2TM by Midrex Technologies,Inc.(United States);H2FUTURE by Voestalpine(Austria);and SALCOS by Salzgitter AG(Germany).Hydrogen-rich blast furnaces(BFs)with COG injection are common in *** BFs have been industrially tested by AnSteel,XuSteel,and *** a currently under construction pilot plant of a coal gasification–gas-based shaft furnace with an annual output of 10000 t direct reduction iron(DRI),a reducing gas composed of 57 vol%H2 and 38 vol%CO is prepared via the Ende *** life cycle of the coal gasification–gas-based shaft furnace–electric furnace short process(30 wt%DRI+70 wt%scrap)is assessed with 1 t of molten steel as a functional *** plant has a total energy consumption per ton of steel of 263.67 kg standard coal and a CO2 emission per ton of steel of 829.89 kg,which are superior to those of a traditional BF converter *** domestic materials and fuels,hydrogen production and storage,and hydrogen reduction characteristics,we believe that a hydrogen-rich shaft furnace will be suitable in *** production and storage with an economic and large-scale industrialization will promote the further development of a full hydrogen shaft furnace.

关键词： hydrogen hydrogen metallurgy blast furnace shaft furnace low carbon

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Using computational fluid dynamic simulation with Flow-3D to reveal the origin of the mushroom stone in the Xiqiao Mountain of Guangdong, China

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Journal of Mountain Science 2022年第1期19卷 1-15页

作者： LI Jian-cheng WANG Wei ZHENG Yan-ming WEN Xiao-hao feng Jing sheng Li WANG Chen QIU ming-kun Department of Geography Hanshan Normal UniversityChaozhou 521041China Geographic School South China Normal UniversityGuangzhou 510631China

Mushroom shaped rocks are not uncommon in nature, but their origin is often misunderstood because they can be formed by different natural forces. A huge mushroom stone in a stream valley of the Xiqiao Mountain of Guangdong,China is widely believed to be formed through the way of stream water erosion. However, the result of the simulation performed with Flow-3 D in this study indicates that the mushroom shape of the rock could not have been sculpted by the flowing water erosion because the simulation result contradicts that of the field investigations:(1) the sediment brought by upstream flowing water tends to be deposited on the leeward side of the flowing water preventing the rock on this side form being eroded, but the narrowest part of the rock bottom is exactly located on this side of the rock and(2) the stream flow should erode the bed sediment and produce high abrasion on the rock surface on the upstream and lateral sides of the rock,respectively, but no abrasion marks are found on the same sides of the rock. Subsequent geological analyses in this study provide evidence that the narrow bottom of the mushroom stone was resulted from chemical and physical weathering happening within the sediment that used to deposit on the lee side of the stone.

关键词： Mushroom Stone Computational fluid dynamics(CFD)model Mineralogical analysis Chemical weathering Xiqiao Mountain happening

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Stepwise approach for view synthesis

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第8期8卷 1218-1226页

作者： CHAI Deng-feng PENG Qun-sheng State Key Lab of CAD and CG Zhejiang University Hangzhou 310027 China Institute of Spatial Information Technique Zhejiang University Hangzhou 310027 China

This paper presents some techniques for synthesizing novel view for a virtual viewpoint from two given views cap-tured at different viewpoints to achieve both high quality and high efficiency. The whole process consists of three passes. The first pass recovers depth map. We formulate it as pixel labelling and propose a bisection approach to solve it. It is accomplished in log2n(n is the number of depth levels) steps,each of which involves a single graph cut computation. The second pass detects occluded pixels and reasons about their depth. It fits a foreground depth curve and a background depth curve using depth of nearby fore-ground and background pixels,and then distinguishes foreground and background pixels by minimizing a global energy,which involves only one graph cut computation. The third pass finds for each pixel in the novel view the corresponding pixels in the input views and computes its color. The whole process involves only a small number of graph cut computations,therefore it is efficient. And,visual artifacts in the synthesized view can be removed successfully by correcting depth of the occluded pixels. Experimental results demonstrate that both high quality and high efficiency are achieved by the proposed techniques.

关键词： View synthesis Occlusion Graph cut

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