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Journal of Forestry Research 2016年第5期27卷 1029-1035页

作者： Seung Hyun Han Soonjin Yun Jongyeol Lee Seongjun Kim hanna chang Yowhan Son Department of Environmental Science and Ecological Engineering Graduate SchoolKorea University Department of Forest Conservation Korea Forest Research Institute Department of Biological and Environmental Sciences Qatar University

The aim of this study was to estimate fine root production （FP） and fine root mortality （FM） at 0-10, 10-20, and 20-30 cm soil depths using minirhizotrons in a 75-year-old Pinus densiflora Sieb. et Zucc. forest located in Gwangneung, Korea. We developed the conversion factors （frame cm-2） of three soil depths （0.158 for 0-10 cm, 0.120 for 10-20 cm, and 0.131 for 20-30 cm） based on soil coring and minirhizotron data. FP and FM were estimated using conversion factors from March 26, 2013 to March 2, 2014. The annual FP and FM values at the 0-30 cm soil depth were 3200.2 and 2271.5 kg ha-1 yr -1, respectively. The FP estimate accounted for approximately 17 % of the total net primary production at the study site. FP was highest in summer （July 31-September 26）, and FM was highest in autumn （September 27-November 29）. FP was positively correlated with seasonal change in soil temperature, while FM was not related to that change. The sea- sonality of FP and FM might be linked to above-ground photosynthetic activity. Both FP and FM at the 0-10 cm depth were significantly higher than at 10-20 and 20-30 cm depths, and this resulted from the decrease in nutrient availability with increasing soil depth. The minirhizotron approach and conversion factors developed in this study will enable fast and accurate estimation of the fine root dynamics in P. densiflora forest ecosystems.

关键词： Conversion factor Fine root Minirhizotron Mortality Production

Soil depth- and root diameter- related variations affect root decomposition in temperate pine and oak forests

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Journal of Plant Ecology 2019年第5期12卷 871-881页

作者： Seung Hyun Han Seongjun Kim hanna chang Hyun-Jun Kim Asia Khamzina Yowhan Son Department of Environmental Science and Ecological Engineering Graduate SchoolKorea UniversityAnam-DongSeongbuk-GuSeoul 02841Republic of Korea

Aims Assessment of factors regulating root decomposition is needed to understand carbon and nutrient cycling in forest *** ob-jective of this study is to examine the effects of soil depth and root diameter on root decomposition and to analyze the relationship of root decomposition with factors such as soil environmental conditions and initial litter *** two decomposition experiments were conducted in natural pine(Pinus densiflora)and oak(Quercus serrata)forests over a 2-year period using the litterbag *** the soil depth experiment,216 litterbags containing fine roots(∅=0-2 mm)were buried at 0-10-,10-20-and 20-30-cm soil *** properties and soil enzyme activities and microbial biomass at each soil depth were *** the root diameter experiment,216 litterbags containing roots 0-1-,1-2-and 2-3-mm in diameter were buried at 10-cm soil *** initial litter qualities(carbon(c),nitrogen(N),calcium(ca)and phosphorus(P)concentrations)for each of the root diameter classes were *** were retrieved after 3,6,12 and 24 months in each forest *** Findingsthe root decomposition rate was significantly altered by soil depth and root *** 2 years,the root decay constant at 0-10-cm depth(pine:0.35 and oak:0.41)was significantly higher than that at 10-20-cm(0.31 and 0.37)and 20-30-cm(0.32 and 0.33)depths in the *** and *** *** activities and microbial biomass declined with soil depth,which may be associated with decreasing soil moisture and organic *** decay constant for the 0-1-mm roots(pine:0.32 and oak:0.37)was higher than that of 1-2-mm(0.29 and 0.33)and 2-3-mm roots(0.26 and 0.33)for the *** and *** *** in initial P concentration and c/N ratio among the different diameter roots were linearly related with root *** particular,the increasing c/N ratio with root diameter resulted in decreases in the decomposition *** re

关键词： decomposition stage litter quality soil environmental condition soil microbial activity

Effect of heat treatment on microstructure and mechanical properties of selective laser-melted PH13-8Mo stainless steel

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Journal of Iron and Steel Research International 2024年第4期31卷 945-955页

作者： Yuan Zhang Xiang Liu chang-jun Wang chang Liu School of Material Science and Engineering Kunming University of Science and TechnologyKunming 650093YunnanChina Central Iron&Steel Research Institute Co. Ltd.Beijing 100081China

PH13-8Mo stainless steel powder with high sphericity and well fluidity was prepared by the plasma rotating electrode *** formed parts with ultra-high purity were manufactured by selective laser *** tensile and impact mechanical properties of the printed parts under three heat treatment regimes were compared to those without heat *** microstructure,grain orientation and phase composition were characterized by electron-backscatter diffraction,X-ray diffraction and transmission electron *** characterization results reveal that the addition of heat treatment makes the grains enlarge,and after different heat treatments,the average grain size from 1.51μm in the printed state increases to 2.78,3.09 and 2.06μm,*** formed parts are mainly composed of martensite and retained ***,the NiAl and M23C precipitates form,which are the major strengthening phases of PH13-8Mo stainless *** optimal heat treatment process is 925℃×1 h water cooling(WC)+0℃×2 h air cooling(AC)+540℃×4 h *** this heat treatment process,PH13-8Mo formed parts have the optimal comprehensive mechanical properties:the tensile strength,yield strength and impact energy KU2 are 1492 MPa,1432 MPa and 63 J,*** strengthening and toughening via heat treatment are mainly attributed to dislocation strengthening,the formation of NiAl and M23Co precipitates and the change of volume fraction of the retained austenite.

关键词： High-strength stainless steel-Selective laser melting-Heat treatment Microstructure Mechanical property

Inverse-time Backup Protection Based on Unified Characteristic Equation for Distribution Networks with High Proportion of Distributed Generations

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 202-212页

作者： Nana chang Guobing Song Zhongxue chang Yuping Zheng Xingang Yang the School of Electrical Engineering Xi’an Jiaotong UniversityXi’anChina State Key Laboratory of Smart Grid Protection and Control NARI Group CorporationNanjingChina Electric Power Research Institute of State Grid Shanghai Electric Power Company ShanghaiChina

The setting work of backup protection using steady-state current is tedious,and mismatches occasionally occur due to the increased proportion of distributed generations(DGs)connected to the power ***,there is a practical need to study a backup protection technology that does not require step-by-step setting and can be adaptively *** paper proposes an action sequence adaptive to fault positions that uses only positive sequence fault component(PSFC)*** the influence of DGs,the unified time dial setting can be obtained by selecting specific *** protection performance is improved by using the adjacent upstream and downstream protections to meet the coordination time interval in the case of metallic faults at the near-and far-ends of the ***,the expression and implementation scheme for inverse-time backup protection(ITBP)based on the unified characteristic equation is *** results show that this scheme can adapt to DG penetration scenarios and can realize the adaptive coordination of multi-level relays.

关键词： Inverse-time backup protection(ITBP) distributed generation(DG) positive sequence fault component(PSFC)voltage unified characteristic equation adaptive coordination

Polymeric piezoelectric accelerometers with high sensitivity,broad bandwidth,and low noise density for organic electronics and wearable microsystems

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Microsystems & Nanoengineering 2024年第3期10卷 63-74页

作者： chang Ge Edmond Cretu The Department of Electrical and Computer Engineering The University of British ColumbiaVancouverBCCanada

Piezoelectric accelerometers excel in vibration *** the emerging trend of fully organic electronic microsystems,polymeric piezoelectric accelerometers can be used as vital front-end components to capture dynamic signals,such as vocal vibrations in wearable speaking assistants for those with speaking ***,high-performance polymeric piezoelectric accelerometers suitable for such applications are *** organic compounds such as PVDF have inferior properties to their inorganic counterparts such as ***,most existing polymeric piezoelectric accelerometers have very unbalanced performance *** often sacrifice resonance frequency and bandwidth for a flat-band sensitivity comparable to those of PZT-based accelerometers,leading to increased noise density and limited application *** this study,a new polymeric piezoelectric accelerometer design to overcome the material limitations of PVDF is *** new design aims to simultaneously achieve high sensitivity,broad bandwidth,and low *** samples were manufactured and characterized,demonstrating an average sensitivity of 29.45 pC/g within a±10 g input range,a 5%flat band of 160 Hz,and an in-band noise density of 1.4μg/√*** results surpass those of many PZT-based piezoelectric accelerometers,showing the feasibility of achieving comprehensively high performance in polymeric piezoelectric accelerometers to increase their potential in novel applications such as organic microsystems.

关键词： piezoelectric polymeric overcome

Recent Progresses of the DAMPE Mission

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空间科学学报 2024年第4期44卷 633-642页

作者： chang Jin Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210033 School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026

The DArk Matter Particle Explorer(DAMPE)is a space high-energy particle andγ-ray detector whose major scientific goals are the indirect detection of dark matter particles,the origin of cosmic rays and highenergyγ-ray *** its successful launch in December 2015,the DAMPE has been operated smoothly in orbit for more than 8 *** direct measurements of the boron-to-carbon and boron-to-oxygen flux ratios,and the proton+Helium spectrum up to 316 TeV have been obtained,revealing new spectral features with very high *** search results ofγ-ray spectral line and fractionally charged particles indicate a good potential of DAMPE for indirect dark matter detection and new physical discovery in *** DAMPE measurements are expected to significantly advance our understanding of the fundamental problems in astroparticle physics.

关键词： DAMPE Dark matter Indirect detection Cosmic rays

Preface to the Special Issue:Additive Manufacturing—Expanding Production Horizon

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 1-2页

作者： Lai-chang Zhang Centre for Advanced Materials and Manufacturing School of EngineeringEdith Cowan University270 Joondalup DriveJoondalupPerthWA6027Australia

Additive manufacturing(AM),commonly known as 3D printing,has become a transformative technology that has a profound impact on various industrial *** encompasses a set of techniques for building objects layer by layer from digital *** conventional subtractive manufacturing methods that involve removing material from large blocks,AM adds material incrementally,providing unprecedented design flexibility and efficiency.

关键词： removing printing Expanding

Breakthrough in Li-mediated continuous electrosynthesis of ammonia

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Science China Chemistry 2024年第10期67卷 3191-3192页

作者： Fei Zhan chang Yu State Key Laboratory of Chemical Resource Engineering College of Chemical EngineeringBeijing University of Chemical TechnologyBeijing 100029China State Key Laboratory of Fine Chemicals Liaoning Key Lab for Energy Materials and Chemical EngineeringSchool of Chemical EngineeringDalian University of TechnologyDalian 116024China

Ammonia(NH3)ranks among the manufactured chemicals,with an annual production surpassing 182 million tons[1],which is an indispensable raw material for fertilizer industry and has been recognized as a promising carbon-... 详细信息

关键词： ammonia Ammonia suppl

An interview with *** Zhang

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High Power Laser Science and Engineering 2024年第3期12卷 122-125页

作者： Guoqing chang Institute of Physics Chinese Academy of SciencesBeijingChina

*** Zhang,a distinguished physicist,has made significant contributions in the fields of high-energy-density physics and inertial confinement *** of these,he was elected academician of the Chinese Academy of Sciences in 2003,academician of the German National Academy of Sciences in 2007,Fellow of the Academy of Sciences for the Developing World(TWAS)in 2008,foreign member of the Royal Academy of Engineering in the United Kingdom in 2011 and foreign associate of the National Academy of Sciences in the United States in *** 2015,he was awarded the prestigious Edward Teller Medal,the most important international award in inertial confinement fusion and high-energy-density *** 2021,he was awarded the Future Science Prize in Physical Sciences.

关键词： interview award Jie

Generic Modeling and Control Framework for Power Systems Dominated by Power Converters Connected Through a Passive Transmission and Distribution Grid

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 292-301页

作者： Qing-chang Zhong Marcio Stefanello Department of Electrical and Computer Engineering Illinois Institute of TechnologyChicagoIL 60616USA Syndem LLC USA.M.Stefanello is with the Fundacao Universidade Federal do Pampa at AlegreteRS97546-550Brazil

In this paper,a compact mathematical model having an elegant structure,together with a generic control framework,are proposed for generic power systems dominated by power converters that are interconnected through a passive transmission and distribution(T&D)grid,by adopting the port-Hamiltonian(pH)systems theory and the fundamental circuit *** models of generic T&D lines are developed and then the model of a generic T&D grid is *** the proposed control framework,the controlled converters are proven to be passive and Input-to-State Stable(ISS).The compact mathematical model is scalable and can be applied to power systems with multiple power electronic converters with generic passive controllers,passive local loads,and different types of passive T&D lines connected in a meshed configuration without self-loops,so it is very ***,the resulting power system is proven to be ISS as *** analysis is carried out without assumptions on constant frequency/voltage,constant loads,and/or lossless networks,except the need of passivity for all parts involved,and without using the Clarke/Park transformations or the graph *** simplify the presentation,three-phase balanced systems are adopted but the results can be easily adapted for single-phase or unbalanced three-phase systems.

关键词： Input-to-State Stable(ISS) passivity,portHamiltonian(pH)systems Power electronic converters dominated power systems Synchronized and Democratized(SYNDEM)grid architecture