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A Methodology for Assessing Axial Compressor Stability with Inlet Temperature Ramp Distortion

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Journal of Thermal Science 2024年第3期33卷 856-871页

作者： SUN Dakun GU Benhao ning fangfei fang Yibo DONG Xu XU Dengke SUN Xiaofeng School of Energy and Power Engineering Beihang UniversityBeijing102206China Research Institute of Aero-engine Beihang UniversityBeijing102206China

Based on a small perturbation stability model for periodic flow,the effects of inlet total temperature ramp distortion on the axial compressor are investigated and the compressor stability is quantitatively *** the beginning,a small perturbation stability model for the periodic flow in compressors is proposed,referring to the governing equations of the Harmonic Balance *** stability model is validated on a single-stage low-speed compressor TA36 with uniform inlet ***,the unsteady flow of TA36 with different inlet total temperature ramps and constant back pressure is simulated based on the Harmonic Balance *** on these simulations,the compressor stability is analyzed using the proposed small perturbation ***,the Dynamic Mode Decomposition method is employed to accurately extract pressure *** two parameters of the temperature ramp,ramp rate and Strouhal number,are discussed in this *** results indicate the occurrence and extension of hysteresis loops in the rows,and a decrease in compressor stability with increasing ramp *** performance is divided into two phases,stable and limit,based on the ramp ***,the model predictions suggest that a decrease in period length and an increase in Strouhal number lead to improved compressor *** DMD results imply that for compressors with inlet temperature ramp distortion,the increase of high-order modes and oscillations at the rotor tip is always the signal of decreasing stability.

关键词： axial compressor stability small perturbation model inlet temperature ramp distortion harmonic balance method dynamic mode decomposition method

Electrospun nanofibrous membranes with antimicrobial activity for air filtration

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Chinese Chemical Letters 2024年第10期35卷 147-157页

作者： Guangyao Wang Zhitong Xu Ye Qi Yueguang fang Guiling ning Junwei Ye State Key Laboratory of Fine Chemicals and School of Chemical Engineering Dalian University of TechnologyDalian 116012China Engineering Laboratory of Boric and Magnesic Functional Material Preparative and Applied Technology Dalian 116024China

Air pollution,including airborne pathogens and particulate matter(PM),has become a prominent issue affecting human health and *** air filtration materials do not meet the requirements for efficient PM capture or do not instantly kill pathogens,leading to increased risk of direct/indirect contact transmission and infection due to the accumulation of pathogens during *** nanofibrous membranes have emerged as a promising platform due to their rich porous structure,finer fiber diameters,good internal connectivity,and the ability to easily incorporate active chemicals for antimicrobial *** this review,antimicrobial mechanisms of nanofibrous membranes for air filtration and PM capture mechanisms of nanofibers were firstly investigated,and various types of electrospun nanofibrous membranes with different antimicrobial agents for efficient air filtration were described in detail,including organic antimicrobial agents,inorganic antimicrobial agents and metal-organic *** hope this work could provide a better practical insight for designing novel electrospun nanofibrous membranes with antimicrobial efficacy for efficient air filtration.

关键词： Electrospinning Nanofibrous membrane Antimicrobial Particulate matter Airfiltration

Fracture network types revealed by well test curves for shale reservoirs in the Sichuan Basin,China

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Energy Geoscience 2024年第1期5卷 264-274页

作者： Yanyan Wang Hua Liu Xiaohu Hu Cheng dai Sidong fang State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development Petroleum Exploration and Development Research InstituteSinopecBeijing100083China

Pressure buildup testing can be used to analyze fracture network characteristics and conduct quantitative interpretation of relevant parameters for shale gas wells,thus providing bases for assessing the well productivity and formulating proper development *** study establishes a new well test interpretation model for fractured horizontal wells based on seepage mechanisms of shale reservoirs and proposes a method for identifying fracturing patterns based on the characteristic slopes of pressure buildup curves and curve combination *** pressure buildup curve patterns are identified to represent three types of shale reservoirs in the Sichuan Basin,namely the moderately deep shale reservoirs with high pressure,deep shale reservoirs with ultra-high pressure,and moderately deep shale reservoirs with normal *** on this,the relationship between the typical pressure buildup curve patterns and the fracture network types are put *** effects of three types of shale gas reservoir are compared and *** results show that typical flow patterns of shale reservoirs include bilinear flow in primary and secondary fractures,linear flow in secondary fractures,bilinear flow in secondary fractures and matrix,and linear flow in *** fracture network characteristics can be determined using the characteristic slopes of pressure buildup curves and curve *** linear flow in early secondary fractures is increasingly distinct with an increase in primary fracture ***,the bilinear flow in secondary fractures and matrix and the subsequent linear flow in the matrix occur as the propping and density of secondary fractures *** increase in the burial depth,in-situ stress,and stress difference corresponds to a decrease in the propping of primary fractures that expand along different directions in the shale gas wells in the Sichuan *** pressure buildup curve patterns exist in the Sichuan Basin and it

关键词： Shale gas Fractured horizontal well Well testing interpretation Flow pattern characterization Parameter inversion Fracture network characteristics Sichuan basin

Simultaneous detection of flare-associated kink oscillations and extreme-ultraviolet waves

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Science China(Technological Sciences) 2024年第5期67卷 1592-1601页

作者： LI Dong HOU ZhenYong BAI XianYong LI Chuan fang Matthew ZHAO HaiSheng WANG JinCheng ning ZongJun Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing210023China Yunnan Key Laboratory of the Solar Physics and Space Science Kunming650216China School of Earth and Space Sciences Peking UniversityBeijing100871China National Astronomical Observatories Chinese Academy of SciencesBeijing100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing100049China School of Astronomy and Space Science Nanjing UniversityNanjing210023China Key Laboratory of Modern Astronomy and Astrophysics Ministry of EducationNanjing UniversityNanjing210023China Columbus Academy GahannaOhio43230USA Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing100049China Yunnan Observatories Chinese Academy of SciencesKunming650216China

Kink oscillations,which are frequently observed in coronal loops and prominences,are often accompanied by extreme-ultraviolet(EUV)***,much more needs to be explored regarding the causal relationships between kink oscillations and EUV *** this article,we report the simultaneous detection of kink oscillations and EUV waves that are both associated with an X2.1 flare on 2023 March 03(SOL2023-03-03T17:39).The kink oscillations,which are almost perpendicular to the axes of loop-like structures,are observed in three coronal loops and one *** short loop shows in-phase oscillation within the same period of 5.2 min at three *** oscillation could be triggered by the pushing of an expanding loop and interpreted as the standing kink *** lags are found between the kink oscillations of the short loop and two long loops,suggesting that the kink wave travels in different *** kink oscillations of one long loop and the prominence are possibly driven by the disturbance of the coronal mass ejection(CME),and that of another long loop might be attributed to the interaction of the EUV *** onset time of the kink oscillation of the short loop is nearly same as the beginning of an EUV *** fact demonstrates that they are almost *** EUV wave is most likely excited by the expanding loop structure and shows two *** leading component is a fast coronal wave,and the trailing one could be due to the stretching magnetic field lines.

关键词： coronal loops solar flares solar prominence solar oscillations extreme-ultraviolet wave magnetohydrodynamic

High-power Pr^(3+):YLF continuous wave lasers at 691.7 nm,701.4 nm,705.0 nm,and 708.7 nm

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Chinese Optics Letters 2024年第8期22卷 82-86页

作者： Run fang Rongbin dai Huiying Xu Zhiping Cai Department of Electronic Engineering Xiamen UniversityXiamen 361005China School of Physics and Electronic Science Guizhou Normal UniversityGuiyang 550001China Fujian Key Laboratory of Ultrafast Laser Technology and Applications Xiamen UniversityXiamen 361005China

Lasers from^(1)I_(6)to^(3)F_(4)transitions were first demonstrated in a Pr^(3+):YLF crystal by inserting a birefringent *** powers up to 2.44 W,2.10 W,2.01 W,and 2.42 W were obtained at 691.7 nm,701.4 nm,705.0 nm,and 708.7 nm,*** slope efficiencies were 19.8%,16.5%,15.8%,and 19.4%,*** M_(x)^(2)and M_(y)^(2)factors were measured to be 2.29and 2.03 at 691.7 nm,2.23 and 1.86 at 701.4 nm,2.31 and 2.08 at 705.0 nm,and 2.41 and 2.04 at 708.7 nm,with corresponding power fluctuations of less than 5.3%,5.6%,5.8%,and 2.9%.

关键词： Pr^(3+):YLF laser high power laser Pr^(3+):YLF crystal

Polypore funga and species diversity in tropical forest ecosystems of Africa,America and Asia,and a comparison with temperate and boreal regions of the Northern Hemisphere

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Forest Ecosystems 2024年第4期11卷 391-400页

作者： Heng Zhao Yingda Wu Zhirong Yang Honggao Liu fang Wu Yucheng dai Yuan Yuan State Key Laboratory of Efficient Production of Forest Resources School of Ecology and Nature ConservationBeijing Forestry UniversityBeijing 100083China Key Laboratory of Forest and Grassland Fire Risk Prevention Ministry of Emergency ManagementChina Fire and Rescue InstituteBeijing 102202China Yunnan Key Laboratory of Gastrodia and Fungi Symbiotic Biology Zhaotong UniversityZhaotong 657000China Yunnan Engineering Research Center of Green Planting and Processing of Gastrodia Zhaotong UniversityZhaotong 657000China

Polypores play a cru cial role in energy recycling and forest regeneration in forest *** majority of them are wood degraders;some are forest pathogens and others are ectomycorrhizal *** basidiocarps provide food and shelter for many organisms,mostly invertebrates,but also some vertebrates,as well as food and medicine for *** extensive research on the species diversity and phylogenetic relationships of polypores in recent years,there remains a lack of comprehensive understanding of their distribution patterns and species composition at the large *** of polypores from the tropical zone,including tropical Africa,tropical America,and tropical Asia,were analyzed for species diversity,distribution patterns,major taxa,and nutritional modes.A total of 1,902 polypore species was found in the three regions,representing 8 orders,46families,and 250 genera of *** orders Polyporales(especially the family Polyporaceae)and Hymenochaetales(especially the family Hymenochaetaceae)had the most prolific taxa,with their species accounting for 93.4%of the total polypores *** of 1,565(or 82.3%)of the total 1,902 species were found in only one of the three regions studied,and we treat them temporarily as"regional endemic species".Only 141species were shared among all three regions,accounting for a mere 7.4%.Tropical Africa and tropical America had the greatest number of shared species and the highest S?rensen similarity index(SC)*** forests had a higher species richness compared with temperate to boreal forests of the Northern Hemisphere,and in addition,also a higher proportion of white rot polypores compared to brown rot and ectomycorrhizal *** study outlines the distribution patterns and species diversity of polypores in the world,shedding light on their ecological significance in diverse ecosystems.

关键词： Agaricomycetes Macrofungi Species composition Wood-decay fungi

Efficient electroreduction of nitrate via enriched active phases on copper-cobalt oxides

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Chinese Chemical Letters 2024年第4期35卷 204-209页

作者： Ling fang Sha Wang Shun Lu Fengjun Yin Yujie dai Lin Chang Hong Liu Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China University of Chinese Academy of Sciences Beijing 100049China

Electrochemical conversion of nitrate(NO_(3)~-) to ammonia(NH_(3)) can target two birds with one stone well, in NO_(3)^(-)-containing sewage remediation and sustainable NH_(3) production. However, single metalbased catalysts are difficult to drive high-efficient NO_(3)~- removal due to the multi-electron transfer ***, we present a tandem catalyst with simple structure, Cu-Co binary metal oxides(Cu-Co-O), by engineering intermediate phases as catalytic active species for NO_(3)~- conversion. Electrochemical evaluation,X-ray photoelectron spectroscopy, and in situ Raman spectra together suggest that the newly-generated Cu-based phases was prone to NO_(3)~- to NO_(2)~- conversion, then NO_(2)~- was reduced to NH_(3) on Co-based species. At an applied potential of -1.1 V vs. saturated calomel electrode, the Cu-Co-O catalyst achieved NO_(3)~- -N removal of 90% and NH_(3) faradaic efficiency of 81% for 120 min in 100 m L of 50 mg/L NO_(3)~- -N,consuming only 0.69 k Wh/mol in a two-electrode system. This study provides a facile and efficient engineering strategy for developing high-performance catalysts for electrocatalytic nitrate conversion.

关键词： NO_(3)^(-)-containing sewage remediation Electrocatalytic reduction Copper-cobalt oxides Tandem reactivity Enriched active phases

Debris flow runout behaviors considering the influences of densely populated buildings

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Journal of Mountain Science 2024年第8期21卷 2696-2712页

作者： ZHANG Shuai fang Zhe dai Cong WANG Shuairong PENG Jingyu ZHOU Yiling SHEN Ping MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang UniversityHangzhou 310058China State Key Laboratory of Internet of Things for Smart City and Department of Ocean Science and Technology University of MacaoMacao SAR 999078China

Debris flows pose serious risks to communities in mountainous areas,often resulting in large losses of human life and *** impeding presence of urban buildings often affects the runout behavior and deposition of debris *** the impact of different building densities and sizes on debris flow dynamics has yet to be quantified to guide urban planning in debris flow risk *** study focused on a debris flow that occurred in Zhouqu County,Gansu Province,China on August 7th,2010,which was catastrophic and destroyed many *** FLO-2D software was used to simulate this debris flow in two scenarios,*** presence and the absence of buildings,to obtain debris-flow intensity *** developed model was then used to further analyze the influence of large buildings and narrow channels within the urban *** simulation results show that considering the presence of buildings in the simulation is essential for accurate assessment of debris flow intensity and deposition *** layout of buildings in the upstream urban area,such as large buildings or parallel buildings which form narrow channels,can affect the flow velocity and depth of debris flow heading towards downstream *** mitigate damage to downstream buildings,the relative spacing(d/a)between upstream and downstream buildings should not exceed a value of two and should ideally be even *** findings provide valuable insights for improving the resistance of mountainous cities to urban debris flows.

关键词： Debris flow Risk Building blockage effect Zhouqu Urban layout

High efficiency removal of NO using waste calcium carbide slag by facile KOH modification

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Journal of Environmental Sciences 2024年第5期139卷 182-192页

作者： fang Wang Hui Li Jiyun Gao Na Geng Enzhu Jiang Futing Xia Mingwu Xiang Lijuan Jia Ping ning School of Chemistry and Environment Yunnan Minzu UniversityKunming 650504China Faculty of Environmental Science and Engineering Kunming University of Science and TechnologyKunming 650500China

Waste calcium carbide slags(CS),which are widely applied to desulfurisation,are not typically used in ***,to well achieve waste control by waste,a facile and highefficiency denitration strategy is developed using KOH to modify the calcium carbide slags(KCS).Various KCS samples were investigated using a series of physical and chemical *** performance test results showed that the KOH concentration and reaction temperature are the main factors affecting the denitration efficiency of KCS,and CS modified with 1.5 mol/L KOH(KCS-1.5)can achieve 100% denitration efficiency at 300℃.Such excellent removal efficiency is due to the catalytic oxidation of the oxygen-containing functional groups derived from the *** studies showed that KOH treatment significantly increased the concentration of oxygen vacancies,nitro compounds,and basic sites of *** study provides a novel strategy for the resource utilisation of waste CS in the future.

关键词： Waste Carbide slag KOH Effective denitration