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Progress, problems and prospects of palynology in reconstructing environmental change in inland arid areas of Asia

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Research in Cold and Arid Regions 2021年第4期13卷 271-291页

作者： yongtao zhao YunFa Miao Yan Lei XianYong Cao MingXing Xiang Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Alpine Ecology Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China

Studying the climatic and environmental changes on different time scales in inland arid regions of Asia can greatly im‐prove our understanding of climatic influences for the Qinghai-Tibet Plateau in the context of global change. Pollen, as a remnant of seed plants, is sensitive to environmental factors including precipitation, temperature and altitude, and is a clas‐sic proxy in environmental reconstruction. In the last two decades, great progress in the application of palynology to in‐land areas of Asia has highlighted the role of palynology in paleoclimatic and paleoenvironmental research. The main progress is as follows. (1) On the tectonic time scale of the late Cenozoic, the palaeoclimatological sequence has been es‐tablished on the basis of pollen percentage, concentration and taxon. Pollen data have revealed a continuous enhancement of drought in the inland arid region of Asia, in contrast to evidence acquired based on other proxies. (2) In the late Quater‐nary, an increase in herbaceous plants further supports the intensification of drought associated with global cooling. In more detail, the palynological record shows a glacial-interglacial pattern consistent with changes in global ice volume. (3) The Holocene pollen record has been established at a high resolution and across a wide range of inland areas. In general, it presents an arid grassland environment in the early Holocene, followed by the development of woody plants in the mid- to late-Holocene climate optimum. This pattern is related to moisture changes in areas dominated by the westerlies. There are also significant regional differences in the pattern and amplitude of vegetation response to the Holocene environment. (4) Modern pollen studies based on vegetation surveys, meteorological data and statistics show that topsoil palynology can better reflect regional vegetation types (e. g., grassland, meadow, desert). Drier climates yield higher pollen contents of drought-tolerant plants such as Chenopod

关键词： Palynology inland arid areas Late Cenozoic Quaternary Holocene modern environmental processes

Relationships between modern pollen and vegetation and climate on the eastern Tibetan Plateau

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Research in Cold and Arid Regions 2023年第2期15卷 92-104页

作者： Lin Lin YunFa Miao yongtao zhao Dong Yang Gen Wang College of Geography and Environmental Science Northwest Normal UniversityLanzhouGansu 730070China Key Laboratory of Oasis Resources Environment and Sustainable DevelopmentNorthwest Normal UniversityLanzhouGansu 730070China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China Key Laboratory of Petroleum Resources Gansu Province/Key Laboratory of Petroleum Resources ResearchInstitute of Geology and GeophysicsChinese Academy of SciencesLanzhouGansu 73000China

The Tibetan Plateau ecosystem is fragile and sensitive to climate change. Understanding the relationships between modern pollen and the vegetation and climate of the region is critical for the evaluation of ecological ***, we explore modern pollen assemblages of typical land-cover types at a large spatial scale by analyzing 36surface samples from the southeastern Tibetan Plateau, supplemented by typical desert, desert-steppe, and steppe meadow transition data selected from the Chinese Surface Pollen Database, giving a total of 75 samples. We used redundancy analysis(RDA) to explore the responses of vegetation in the assemblages to regional climate. Our results show that pollen assemblages generally reflect the vegetation composition: assemblages from alpine meadow samples are dominated by Cyperaceae, Asteraceae, Rosaceae, and Polygonaceae;alpine shrublands mainly comprise Fabaceae, Rosaceae, Ericaceae, and Quercus(Q. spinosa);and coniferous forest surface samples mainly comprise Picea, Abies, Pinus, and Betulaceae. Our RDA shows that mean annual precipitation(MAP) is the main meteorological factor affecting the pollen assemblage and vegetation type;MAP positively correlates with percentages of Cyperaceae, Poaceae, Rosaceae, and Asteraceae, and negatively correlates with percentages of Chenopodiaceae, Ephedraceae, Nitraria, and Tamaricaceae. The ratio of Artemisia to Chenopodiaceae is a useful indicator to distinguish temperate desert from other land-cover types on the Tibetan Plateau, while the ratio of Cyperaceae + Asteraceae to Artemisia + Chenopodiaceae can be used to distinguish arid desert from other landcover types, and may provide a useful altitude index for the eastern Tibetan Plateau.

关键词： Surface pollen Tibetan Plateau Climate change Vegetation

Modulating surface cation vacancies of nickel-cobalt oxides as efficient catalysts for lithium-oxygen batteries

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Journal of Materials Science & Technology 2023年第8期139卷 147-155页

作者： Yuan Yang Linna Dai Jianwei Qiu Zhibiao Hu Peng Wang yongtao zhao Huanhuan Guo Pengchao Si Rui Song Center for Robotics School of Control Science and EngineeringShandong UniversityJinan 250061China Research Center for Carbon Nanomaterials Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education)School of Materials Science and EngineeringShandong UniversityJinan 250061China School of Mechanical Electrical and Information EngineeringShandong UniversityWeihai 264209China College of Chemistry and Chemical Engineering Xingtai UniversityXingtai 054001China

Rechargeable lithium-oxygen batteries(LOBs)have received incremental attention owing to their high energy density and applicability to mobile devices and electric ***,the lack of robust,low-cost,and environmentally benign bifunctional catalysts is a major impediment to the commercial *** introduction of vacancies is one of the effective strategies to enhance the performance of cathode catalysts for lithium-oxygen batteries,but the preparation is *** this work,needle-like microsphere cathode catalysts of nickel-cobalt oxide containing cationic vacancies are constructed by controlling the annealing *** is demonstrated that the presence of cationic vacancies can modulate the electronic structure of the catalyst,reduce the energy barrier for the oxygen electrode re-action,meanwhile enhance the bifunctional catalytic ***,the nickel-cobalt oxide-based LOB with cationic vacancies exhibits large specific capacity(12,205 mAh g^(-1)at 200 mA g^(-1))and good *** work provides worthwhile insight into the formation and catalytic enhancement mech-anism of transition metal oxide catalysts with cationic vacancies,and to some extent,the creation of efficient and low-cost oxygen electrocatalysts for LOBs.

关键词： Li-O_(2)batteries Metal oxides Cation vacancies Catalytic kinetic

Mechanical and Galvano-chemistry Property Variation within Dissimilar Metal Weld between 1Cr18Ni9Ti and 1Cr13 Stainless Steel

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Journal of Materials Science & Technology 2010年第5期26卷 477-480页

作者： yongtao zhao ,Junhui Dong,Yonglin Ma,Liping zhao and Xiaobing Pei Material and Metallurgy Engineering School,University of Science and Technology Inner Mongolia,Baotou 014010,China [a] Material and Metallurgy Engineering School University of Science and Technology Inner Mongolia Baotou 014010 China

The purpose of this study is to discuss the microstructure and properties variation of the weld metal in the dissimilar stainless steels during the argon tungsten-arc welding *** of the existence of different materials and chemistry variation within welds,properties,such as tensile and fracture properties and so on,are expected to show spatial *** the study,microstructures were observed by optical and electron *** appearance and uniform structure and typical dendrite structure were observed in welding *** micro-hardness tester and electronic universal stretcher were used to measure the mechanical properties of the weldments and base *** heat affected zone（HAZ） near 1Cr13 hardness is up to peak value of 1150 HV,the strength of weldments is nearly same as austenite stainless *** addition,through seawater immersion test,polarization curves and AC impedance spectroscopy of the weldments and base metals are *** was found that corrosion resistance at welding joint lies between 1C13 and 1Cr18Ni9Ti.

关键词： 1Cr13,1Cr18Ni9Ti Welding joint Mechanical and galvano-chemistry property

Vegetation and climate history of Anggertu Lake in the Tengger Desert over the last millennium

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Journal of Oceanology and Limnology 2018年第6期36卷 2166-2180页

作者： DUAN Futao AN Chengbang zhao yongtao WANG Wei CAO Zhihong ZHOU Aifeng College of Earth Environmental Sciences MOE Key Laboratory of Western China's Environmental SystemsLanzhou University

Reconstructing climate change of the last millennium is important to understand the current relationship between human-social activities and natural environmental changes. Pollen assemblages, losson-ignition(LOIo rg at 550°C), and grain size data collected from sediment core AGE15 A from the center of Anggertu lake(eastern Tengger Desert, Inner Mongolia) were used to reconstruct the regional vegetation and climate history of the last millennium. Desert or steppe desert, dominated by A rtemisia and Amaranthaceae, expanded around this region during the period of 988–1437 AD indicating a generally dry climate condition with two short humid periods(1003–1082 AD and 1388–1437 AD). These two wet periods were characterized by relatively high vegetation cover and bioproductivity, as reflected by high pollen concentrations and LOIo rg values. Increases in steppe and meadow vegetation communities(Poaceae, Cyperaceae) and vegetation cover during 1437–2015 AD suggest a wetting trend, which was also deduced from a gradual trend towards fine grains and higher lake biological productivity as reflected by LOIo rg values. An unstable lacustrine environment was identified via frequent fluctuations in pollen concentration and grain size after 1842 AD. This study also recorded a relatively dry Medieval Warm Period(MWP, 1082–1388 AD) and a wet Little Ice Age(LIA, 1437–1842 AD). Increased Amaranthaceae and high abundance of Poaceae may be related to overgrazing and agricultural activities that took place during those time periods. The evolution of vegetation in the lake region was influenced by climate change and human activities. These results could provide more fundamental support for studies of the environmental evolution of the Tengger Desert.

关键词： Anggertu Lake Tengger Desert lacustrine record vegetation climate changes the last millennium

The effect of welding materials on 1Cr18Ni9Ti and 2Cr13 steel welded joints electrochemical properties

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China Welding 2022年第3期31卷 42-47页

作者： zhao yongtao Hu Yuqing Dong Junhui Zhou Junwei Material and Metallurgy School Inner Mongolia University of Science and TechnologyBaotou014010China Materials Science and Engineering school Inner Mongolia University of TechnologyHuhhot010051China Steel-making factory Iron and steel group companyBaotou014010China

By method of TIG,two kinds of welding materials were filled in and under certain welding craft conditions,1Cr18Ni9Ti and 2Cr13 were *** microstructure of two kinds of welded joints were observed and analyzed by OM,*** seawater immersion test,polarization curves and AC impedance spectroscopy of two kinds of welding joints were *** results show that 2Cr13 and 1Cr18Ni9Ti welded joints are typical columnar crystal,the microstructure is lath martensite+austenite+*** welded joints that filled in 308 and H1Cr21Ni10Mn7Mo welding wires,corrosion resistance has same change rule:Austenite base metal>HAZ near Austenite>welded joint>HAZ near Martensite>Martensite base *** every zone contrast of two kinds of welded joint corrosion resistance obtains:the welded joints filled in 308>the welded joints filled in H1Cr21Ni10Mn7Mo.

关键词： 1Cr18Ni9Ti 2Cr13 welding materials electrochemical properties

A Remote Sensing-based Analysis on the Impact of Wenchuan Earthquake on the Core Value of World Nature Heritage Sichuan Giant Panda Sanctuary

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Journal of Mountain Science 2011年第3期8卷 458-465页

作者： YU Hu zhao yongtao MA Yuewei SUN Yulian ZHANG Hu YANG Shihong LUO Yong Institute of Mountain Hazards and Environment ChineseAcademy of Sciences No. 9. Section 4. South Renmin Road China Graduate University of Chinese Academy of Sciences Beijing 100049 China Sichuan World Heritage Administrative Office

In this study,we used remotely sensed data,GIS modeling,and statistical methods to evaluate the damage caused by the Wenchuan Earthquake (May 12,2008) to the giant panda (Ailuropoda melanoleuca) habitat in the World Nature Heritage Sichuan Giant Panda Sanctuary (WHSGPS) in China.A landscape ecological analysis found increases of landscape heterogeneity,complexity,and fragmentation in the giant panda habitat after the earthquake.A terrain analysis found that slope and elevation are directly associated with the distribution of the damaged *** slope and elevation increase,the size of the damaged area keeps increase until to a peak,and then starts to *** total area of the damaged vegetation in our study area is 114.26 km 2,accounting for 3.78% of the study area;30.46% of that 114.26 km 2 is located in the Core Zone of *** are 18.57km 2 of the damaged vegetation located in the identified suitable giant panda habitat,accounting for 1.75% of the total area of suitable giant panda habitats in the study *** on these findings,we conclude that the Wenchuan Earthquake does not have significant impact on the WHSGPS as a whole.

关键词： World Nature Heritage Giant Panda Sanetuaries Suitable giant panda habitat Model Wenehuan Earthquake Landscape pattern GIS RS

Comparative Analysis between Acoustic Emission Testing and Magnetic Flux Leakage Testing

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Comparative Analysis between Acoustic Emission Testing and M...

Areal density and spatial resolution of high energy electron radiography

2018远东无损检测新技术论坛

作者： yongtao zhao Xuewei Shao Xingyou zhao Yuming Lin CNPC Research Institute of Safety & Environment Technology China University of Petroleum-Beijing

Storage tanks are used as the main equipment for storage of petroleum and petrochemical raw materials and products, and are widely used in petroleum and petrochemical enterprises. Safe operation of storage tanks is the premise to ensure the normal production of enterprises. In recent years, in accordance with the requirements of the Safety and Environmental Protection Department of the group company, a large number of on-line acoustic emission testing testing has been carried out in our institute. At the same time, Magnetic flux leakage testing of some storage tanks is carried out according to the actual situation, and the comparison is made in depth. The results show that acoustic emission testing can well reflect the corrosion of tank bottom and can provide decision support for the daily management and maintenance of tanks.

关键词： Tank Acoustic emission testing Magnetic flux leakage testing

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Chinese Physics B 2018年第3期27卷 321-326页

作者： Jiahao Xiao Zimin Zhang Shuchun Cao Ping Yuan Xiaokang Shen Rui Cheng Quantang zhao Yang Zong Ming Liu Xianming Zhou Zhongping Li yongtao zhao Chuanxiang Tang Wenhui Huang Yingchao Du Wei Gai Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Department of Engineering Physics Tsinghua UniversityBeijing 100084China Argonne National Lab ArgonneIL 60439USA

Ultrafast imaging tools are of great importance for determining the dynamic density distribution in high energy density(HED)*** this work,we designed a high energy electron radiography(HEER)system based on a linear electron accelerator to evaluate its capability for imaging HED matter.40 MeV electron beams were used to image an aluminum target to study the density resolution and spatial resolution of *** results demonstrate a spatial resolution of tens of *** interaction of the beams with the target and the beam transport of the transmitted electrons are further simulated with EGS5 and PARMELA codes,with the results showing good agreement with the experimental ***,the experiment can be improved by adding an aperture at the Fourier plane.

关键词： high energy density matter high energy electron radiography areal density resolution spatial resolution