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Spatial heterogeneity of soil water content in the reversion process of desertification in arid areas

Journal of Arid Land 2011年第4期3卷 268-277页

作者： QuanLin MA Fang CHENG YouJun LIU FangLin Wang DeKuai ZHANG HuJia JIN Gansu key laboratory of Desertification Combating ＆ Minqin National Studies Station for Desert Steppe Ecosystem Gansu Desert Control Research Institute Lanzhou 730070 China Institute of Desertification Studies Chinese Academy of Forestry Beijing 100091 China

Sandy soils in arid,rain-fed environments have low and limited water content,which is a principal factor limiting vegetation development,and a key constraint controlling the structure and functions of the ecological systems in arid *** spatial heterogeneity of soil water content is a major soil property,and a focus of soil science and *** the southern edge of the Tengger Desert,sample plots were selected from mobile sand dunes in desertified lands that had been enclosed for 5,15 and 25 years,*** study explored the dynamic and spatial heterogeneity of soil water content in these different layers of soil that were also in the reversion process of *** results showed that the soil water content of the mobile sand dunes was highest when in the initial stages of the reversion process of desertification,while the soil water content in the 0-20 cm,20-40 cm and 40-60 cm layers of soil was 1.769%,3.011%,and 2.967% respectively,presenting a restoring tendency after 25 years of *** were significant differences,as a whole,in the soil water content among different restoration stages and different soil layers,*** in soil water content,in different soil layers,at different restoration stages,exhibited exponential or spherical *** spatial distribution of soil water content exhibited a mosaic patch pattern with obvious spatial *** ratio of the heterogeneity of spatial autocorrelation to gross spatial heterogeneity was greater than 50%.The gross spatial heterogeneity of the 0-20 cm layer of soil improved gradually,while those of the 20-40 cm and 40-60 cm layers improved initially,then weakened in the reversion process of *** study revealed that restoration with sand-binding vegetation reduced soil water content,and increased its spatial heterogeneity in arid ***,after 25 years of vegetation-soil system restoration,the soil water content started to increase and it

关键词： Tengger Desert reversion process of desertification soil water content sand-binding vegetation geostatistical analysis

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Optimal power allocation for homogeneous and heterogeneous CA-MIMO systems

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Science China(Information Sciences) 2013年第2期56卷 177-190页

作者： CUI QiMei KANG PeiChuan HUANG XueQing VALKAMA Mikko NIEMELA Jarno key laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications Department of Communications Engineering Tampere University of Technology

Carrier aggregation (CA) technique has been adopted by 3GPP LTE-Advanced due to its ability of enhancing the spectrum efficiency and peak data rates through aggregating multiple component carriers (CCs). Two main factors make power control optimization very essential for CA-MIMO radio link: the different channel characteristics in multiple CCs, and multiple power constraint conditions (per-CC, per-antenna and pertransmitter power constraints) in the actual CA system deployment. This paper firstly derives the degenerate conditions of optimal power allocation for a single-transmitter CA-MIMO system. Stemming from the derived degenerate conditions, we propose a modified hybrid gradient optimal power allocation(MHGOPA) algorithm to maximize the system performance. Simulation results verify the validity of the proposed resource allocation approach by comparing with baseline average power allocation algorithm. Finally, we extend the MHGOPA algorithm into a heterogeneous CA network with multiple transmitters working simultaneously.

关键词： LTE-advanced carrier aggregation CA-MIMO heterogenous network modified hybrid gradient optimal power allocation

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Magnetic-electric composite coating with oriented segregated structure for enhanced electromagnetic shielding

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Journal of Materials Science & Technology 2022年第1期96卷 11-20页

作者： Jijun Zhang Zexuan Wang Jiawei Li Yaqiang Dong Aina He Guoguo Tan Qikui Man Bin Shen Junqiang Wang Weixing Xia Jun Shen Xin-min Wang CAS key laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application TechnologyNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 610054China University of Chinese Academy of Sciences Beijing 100049China Ningbo key laboratory of Polymer Materials Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China College of Mechatronics and control Engineering Shenzhen UniversityShenzhen 518060China

Manipulation of the internal architecture is essential for electromagnetic interference(EMI)shielding performance of metal-based coatings,which can address the electromagnetic pollution in large-size,complex geometries,and harsh *** this work,oriented segregated structure with conductive networks embedded in magnetic matrix was achieved in Fe-based amorphous coatings via Ni-Cu-P functionalization of(Fe_(0.76)Si_(0.09)B_(0.1)P_(0.05))_(99)Nb_(1)amorphous powder precursors and then thermal spraying them onto aluminum(Al)*** from the unique magnetic-electric structure,the coating@Al composite delivered prominent EMI shielding *** EMI shielding effectiveness(SE)of modified coating@Al composite is~41 dB at 8-12 GHz,doubling the value of Al substrate and is 15 dB greater than that of Ni-Cu-P-free coating@Al *** analysis showed that the introduced Ni−Cu−P insertions forcefully suppress the serious oxidation of the magnetic precursors during thermal spraying and form a dense conductive network in the magnetic *** holography observation and electromagnetism simulation clarified that the modified coating can effectively trap and attenuate the incident radiations because of the electric loss from Ni−Cu−P conductive network,magnetic loss from Fe-based amorphous coating,and the electromagnetic interactions in the oriented segregated ***,the optimized thermal isolation and mechanical properties brought by structural improvement enable the coating to shield complex parts in thermal shock and mechanical loading *** work gives an insight on the design strategies for metal-based EMI shielding materials and enriches the fundamental understanding of EMI shielding mechanisms.

关键词： Fe-based amorphous coatings Ni-Cu-P Oriented segregated structure Electromagnetic shielding

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Corrosion of New Zirconium Claddings in 500 ℃/10.3 MPa Steam: Effects of Alloying and Metallography

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Acta Metallurgica Sinica(English Letters) 2019年第8期32卷 981-994页

作者： Jing-Jing Liao Zhong-Bo Yang Shao-Yu Qiu Qian Peng Zheng-Cao Li Ming-Sheng Zhou Hong Liu Science and Technology on Reactor Fuel and Materials laboratory Nuclear Power Institute of ChinaChengdu 610213China key laboratory of Advanced Materials(MOE) School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Department of Engineering Physics Tsinghua UniversityBeijing 100084China

With the aim of improving corrosion resistance of rod cladding for in-service and accident conditions,six new zirconium alloys(named N1-N6)have been *** contents of Sn and Nb were optimized for better behavior at high-temperature pressurized water,and Fe,Cr,V,Cu or Mo elements were added to the alloys to adjust the corrosion behavioi\The current work focused on the rapid corrosion behavior in 500℃/10.3 MPa steam for up to 1960 h,aiming to test the corrosion resistance at high *** structure of matrix and properties of second-phase particles(SPPs)were characterized to find the main differences among these *** the six alloys exhibited better corrosion resistance than N36,and NI was shown to have the best performance.A careful analysis of the corrosion kinetics curves revealed that Cr was beneficial for severe *** Fe,Cr,V,Cu or Mo aggregated into SPPs with diiferent concentrations and *** was demonstrated to be the main reason for different corrosion *** to good processing control,all alloys had a uniform structure and a uniform distribution of *** for N4,N6 and N36,the existing of large-size SPPs(450 nm)might be a contributing factor of the relatively poor corrosion resistance.

关键词： New zirconium cladding Corrosion behavior Alloying elements Metallography Second-phase particles

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Review of snow water equivalent microwave remote sensing

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Science China Earth Sciences 2016年第4期59卷 731-745页

作者： SHI JianCheng XIONG Chuan JIANG LingMei State key laboratory of Remote Sensing Sciences Jointly Sponsored by Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences and Beijing Normal University and Joint Center for Global Change Studies State key laboratory of Remote Sensing Sciences Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences School of Geography Beijing Normal Universityand Joint Center for Global Change Studies

Accurate quantitative global scale snow water equivalent information is crucial for meteorology, hydrology, water cycle and global change studies, and is of great importance for snow melt-runoff forecast, water resources management and flood control. With land surface process model and snow process model, the snow water equivalent can be simulated with certain accuracy, with the forcing data as input. However, the snow water equivalent simulated using the snow process models has large uncertainties spatially and temporally, and it may be far from the needs of practical applications. Thus, the large scale snow water equivalent information is mainly from remote sensing. Beginning with the launch of Nimbus-7 satellite, the research on microwave snow water equivalent remote sensing has developed for more than 30 years, researchers have made progress in many aspects, including the electromagnetic scattering and emission modeling, ground and airborne experiments, and inversion algorithms for future global high resolution snow water equivalent remote sensing program. In this paper, the research and progress in the aspects of electromagnetic scattering/emission modeling over snow covered terrain and snow water equivalent inversion algorithm will be summarized.

关键词： Snow Microwave remote sensing Model Inversion

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Trace elements and rare earth elements in wet deposition of Lijiang,*** region,southeastern edge of the Tibetan Plateau

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Journal of Environmental Sciences 2017年第2期29卷 18-28页

作者： Junming Guo Shichang Kang Jie Huang Mika Sillanpaa Hewen Niu Xuejun Sun Yuanqing He Shijing Wang Lekhendra Tripathee key laboratory of Tibetan Environment Changes and Land Surface Processes Institute of Tibetan Plateau ResearchChinese Academy of Sciences(CAS)Beijing 100101China State key laboratory of Cryospheric Sciences Cold and Arid Regions Environmental and Engineering of Research InstituteCASLanzhou 730000China CAS Center for Excellence in Tibetan Plateau Earth Sciences Beijing100101China laboratory of Green Chemistry Lappeenranta Uniuersity of TechnologyMikkeli 50130Finland University of Chinese Academy of Sciences Beijing 100049China

In order to investigate the compositions and wet deposition fluxes of trace elements and rare earth elements（REEs） in the precipitation of the southeastern edge of the Tibetan Plateau, 38 precipitation samples were collected from March to August in 2012 in an urban site of Lijiang city in the Mt. Yulong region. The concentrations of most trace elements and REEs were higher during the non-monsoon season than during the monsoon season,indicating that the lower concentrations of trace elements and REEs observed during monsoon had been influenced by the dilution effect of increased precipitation. The concentrations of trace elements in the precipitation of Lijiang city were slightly higher than those observed in remote sites of the Tibetan Plateau but much lower than those observed in the metropolises of China, indicating that the atmospheric environment of Lijiang city was less influenced by anthropogenic emissions, and, as a consequence, the air quality was still relatively good. However, the results of enrichment factor and principal component analysis revealed that some anthropogenic activities（e.g., the increasing traffic emissions from the rapid development of tourism） were most likely important contributors to trace elements, while the regional/local crustal sources rather than anthropogenic activities were the predominant contributors to the REEs in the wet deposition of Lijiang city. Our study was relevant not only for assessing the current status of the atmospheric environment in the Mt. Yulong region, but also for specific management actions to be implemented for the control of atmospheric inputs and the health of the environment for the future.

关键词： Trace elements Rare earth elements Wet deposition Seasonal variation Lijiang city Tibetan Plateau

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Variations and determinants of tissue carbon concentration of 32 sympatric temperate tree species

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Journal of forestry Research 2024年第6期35卷 62-72页

作者： Jun Pan Jing Zhang Xingchang Wang Xiuwei Wang Qi Wang Yankun Liu Yulong Liu Yunfei Diao Xiankui Quan Chuankuan Wang Xiaochun Wang Center for Ecological Research Northeast Forestry UniversityHarbin 150040People’s Republic of China key laboratory of Sustainable forest Ecosystem Management Ministry of EducationNortheast Forestry UniversityHarbin 150040People’s Republic of China key laboratory of Vegetation Restoration and Management of Degraded Ecosystems South China Botanical GardenChinese Academy of SciencesGuangzhou 510650People’s Republic of China University of Chinese Academy of Sciences Beijing 100049People’s Republic of China National-Regional Joint Engineering Research Center for Soil Pollution control and Remediation in South China Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and ManagementInstitute of Eco-Environmental and Soil SciencesGuangdong Academy of ScienceGuangzhou 510650People’s Republic of China Heilongjiang Institute of Ecology Heilongjiang Academy of ForestryHarbin 150040People’s Republic of China

Plant carbon(C)concentration is a fundamental trait for estimating C storage and nutrient ***,the mechanisms of C concentration variations among different tree tissues and across species remains poorly *** this study,we explored the variations and determinants of C concentration of nine tissues from 216 individuals of 32 tree species,with particular attention on the effect of wood porosity(i.e.,non-porous wood,diffuse-porous wood,and ring-porous wood).The inter-tissue pattern of C concentration diverged across the three porosity types;metabolically active tissues(foliage and fine roots,except for the foliage of ring-porous species)generally had higher C levels compared with inactive *** poor inter-correlations between tissue C concentrations indicated a necessity of measuring tissue-and specific-C *** concentration for almost all tissues generally decreased from non-porous,to diffuse-porous and to *** C was often positively correlated with tissue(foliage and wood)density and tree size,while negatively correlated with growth rate,depending on wood *** results highlight the mediating effect of type of wood porosity on the variation in tissue C among temperate *** variations among tissues were more important than that among *** findings provided insights on tissue C concentration variability of temperate forest species.

关键词： Carbon fraction Growth rate Temperate tree species Tissue density Wood porosity

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Role of TRP channels and HSPs in thermal stress response in the aphid parasitoid Aphelinus asychis(Hymenoptera:Aphelinidae)

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Journal of Integrative Agriculture 2020年第6期19卷 1530-1542页

作者： LIU Xiang KANG Zhi-wei YU Xing-lin LI Fan LIU Tong-xian LI Qiang Department of Entomology College of Plant ProtectionYunnan Agricultural UniversityKunming 650000P.R.China State key laboratory of Crop Stress Biology for Arid Areas/key laboratory of Northwest Loess Plateau Crop pest Management of Ministry of Agriculture and Rural Affairs Northwest A&F UniversityYangling 712100P.R.China

Aphelinus asychis is an important aphid *** field and greenhouse conditions,high temperature is one of the factors limiting the application of A asychis for biological pest *** explore the potential role of transient receptor potential(TRP)channels and heat shock proteins(HSPs)in this process,we identified 11 genes encoding TRP channels and nine genes encoding *** proteins(AasyTRPA5,AasyPyrexia,AasyPainless)that belong to transient receptor potential ankyrin(TRPA)subfamily and nine HSPs are involved in the response to high *** also investigated the survival of A asychis and the response of the identified TRP channels and HSPs to high *** results showed that the maximum temperature that allowed *** survival was approximately 41°C;females had higher survival rates than that of the males at 40 and 41°***-term heat-shock resulted in increased expression of Amsysbsp in males,and Aasyhsp40,Aasyhsp68,Aasyhsp70-4,Aasyhsp70-5 and Aasyhsp90 were upregulated and then down regulated,whereas Aasyhsp70-3was upregulated at41°***,Aasyhsp40and Aasyhsp90showed higherexpression levels in females,while Aasyshsp and Aasyhsp70-3 presented opposite expression *** temperature above 35°C,expression of AasyPyrexia in females was significant higher than that in males,whereas AasyPainless mnd AasyTRPA5 presented higher expression in males at 40 and 41°C,***,these results indicate that protect!on against thermal stress in *** is coordinated by TRP channels and *** findings provide a basis for understanding the potential mechanism of A asychis in response to high temperatures.

关键词： Aphelinus asychis TRP channels heat-shock proteins thermal stress gene expression

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VxMn(4-x)Mo3Ce3/Ti catalysts for selective catalytic reduction of NO by NH3

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Journal of Environmental Sciences 2020年第2期32卷 145-154页

作者： Daojun Zhang Ziran Ma Baodong Wang Tao Zhu Duan Weng Xiaodong Wu Hongyan Wang Ge Li Jiali Zhou National Institute of Clean-and-Low-Carbon Energy Beijing 102211China School of Chemical&Environmental Engineering China University of Mining and Technology(Beijing)Beijing 100083China key laboratory of Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

A series of vanadium based catalysts(VxMn(4-x)Mo3Ce3/Ti) with different vanadium(x wt.%) and manganese((4-x) wt.%) contents have been prepared by the wet impregnation method and investigated for selective catalytic reduction(SCR) of NOx by NH3 in the presence of 8 vol.% H2O and 500 ppm V *** physicochemical characteristics of the catalysts were thoroughly *** SCR of NOx by NH3(NH3-SCR) activity, especially the low-temperature activity, significantly increased with increasing V2O5 content in the catalyst until the V2O5 content reached 1.5 wt.%, which corresponds well with the redox properties of the *** of the metal oxides were well dispersed and strongly interacted with each other on the catalyst surface.V mainly exists in the V^5+state in the *** strong synergistic effect between the vanadium and cerium species led to formation of more Ce^3+species, and that between the vanadium and manganese species contributed to formation of more manganese species with low *** of the catalysts exhibited strong acidity, while the redox properties determined the NH3-SCR activity, especially the low-temperature activity.H2O and SO2 had severe inhibiting effects on the activity of V1.5Mn2.5Mo3Ce3/***, good H2O and SO2 resistance and high NOx conversion by V1.5Mn2.5Mo3Ce3/Ti could be achieved in the presence of SO2 and almost no decline was observed in a long-term test at 275℃ for 168 hr in the presence of SO2 and H2O, which can be attributed to the sulfate species formed on the catalyst surface.

关键词： Selective catalytic reduction Vanadium Molybdenum Manganese Cerium

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Damage effect and progressive failure mechanism of sandstone considering different flaw angles under dynamic loading

Rock Mechanics Bulletin

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Rock Mechanics Bulletin 2024年第1期3卷 81-96页

作者： Dongliang Ji Hui Cheng Hongbao Zhao State key laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuangChina key laboratory of Mechanical Behavior Evolution and control of Traffic Engineering Structures in Hebei Shijiazhuang Tiedao UniversityShijiazhuangChina School of Energy and Mining Engineering China University of Mining and Technology(Beijing)BeijingChina

In many engineering applications,it is essential to have information about rocks that inherently contain preexisting flaws under dynamic loading *** impact tests are conducted on samples with varying flaw angles using the split Hopkinson pressure bar(SHPB)test system and the Digital Image Correlation system(DIC).The characteristics of the samples after dynamic loading,including dynamic strength,energy dissipation,and fractal fracture,are compared and *** the flaw angle increases,the peak stress and strain exhibit a typical V-shaped pattern,reaching the minimum value at 30,and the initial initiation position shifts from the flaw tips to the middle of the *** modes can be divided into three modes depending on the flaw *** progressive failure process,taking into account the heterogeneity of the rock,is demonstrated by developing an elastic damage constitutive model that uses dynamic compression and tensile tests to parameterize *** the flaw angle increases,the initial damage zone also moves from the flaw tips to the middle of the *** around the hole with redistributed stress are observed,and the failure mechanisms can be explained with the aid of strain energy density(SED).Using fracture mechanics,the analytical solution of stress around the flaw is provided,and the variation of crack initiation angle,stress distribution,and energy dissipation under different flaw angles is theoretically explained,which is in good agreement with the experimental and simulated results.

关键词： Dynamic loading Damage evolution Constitutive model Flaw angle Energy dissipation

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