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Contributions of natural systems and human activity to greenhouse gas emissions

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Advances in Climate Change Research 2018年第4期9卷 243-252页

作者： YUE Xi-Liu gao qing-xian China Reinsurance (Group) Corporation Post-doctoral Workstation Beijing 100033 China Beijing Normal University Beijing 100875 China Chinese Research Academy of Environmental Sciences Beijing 100012 China

In this study, we conducted a literature review of relevant research and then statistically analyzed global greenhouse gas (GHG) emissions from natural systems, including forest fires, oceans, wetlands, permafrost, mud volcanoes, volcanoes, and earthquakes. Drawing on the Global Carbon Project (GCP) report, we also summarized the global anthropogenic GHG emissions. We then compared the global annual GHG emissions from natural systems with those generated by human activity. The results indicate that the global annual GHG emissions range approximately between 54.33 and 75.50 Gt CO2-eq, of which natural emissions account for 18.13e39.30 Gt CO2-eq, with the most likely value being approximately 29.07 Gt CO2-eq. According to the GCP report, the global anthropogenic emissions have increased from 22 Gt CO2-eq in 1990 to 36.2 Gt CO2-eq in 2016. The amounts of natural and anthropogenic GHGs emissions are roughly of the same order of magnitude. Anthropogenic emissions account for approximately 55.46% of the total global GHGs emissions (2016 value), i.e., the ratio of natural to anthropogenic emissions is approximately 0.8. In addition, the annual amount of GHGs absorbed by Earth systems (ocean and terrestrial ecosystems) ranges between approximately 14.4 Gt CO2-eq and 26.5 Gt CO2-eq, with natural system GHG emissions and sinks also having roughly the same order of magnitude. This finding indicates that the GHG emissions generated by human activity exert extra pressure on what is otherwise a self-balancing Earth system.

关键词： Greenhouse gases Natural emission Anthropogenic emission Global emission Natural system

体外循环下瓣膜置换术患者右美托咪定用量及对患者微循环和血流动力学的影响

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微循环学杂志 2024年第1期34卷 41-47页

作者：程雪淋王青青尹治清高清贤南通瑞慈医院麻醉科南通221000

目的:探讨体外循环(CPB)期间右美托咪定(Dex)用量对瓣膜置换术患者血流动力学的影响。方法:选取2020-06-2022-12于本院接受择期CPB瓣膜置换术患者85例作为研究对象,随机分为低剂量组(n=28)、高剂量组(n=28)和对照组(n=29),在麻醉诱导前1... 详细信息

目的:探讨体外循环(CPB)期间右美托咪定(Dex)用量对瓣膜置换术患者血流动力学的影响。方法:选取2020-06-2022-12于本院接受择期CPB瓣膜置换术患者85例作为研究对象,随机分为低剂量组(n=28)、高剂量组(n=28)和对照组(n=29),在麻醉诱导前10min分别输注0.2μg/kg·h^(-1)Dex、0.4μg/kg·h^(-1)Dex、生理盐水至术毕。比较麻醉诱导后(T1)、CPB转机开始前(T2)、CPB转机后1h(T3)、CPB转机停止时(T4)、术毕4h(T5)、术毕24h(T6)的各组血流动力学指标;分析Dex输注时长对脑电双频谱指数(BIS)的影响及术后恢复情况。结果:低剂量组和高剂量组给药12min、给药15min、插管后1min的BIS值均低于对照组(P<0.05);低剂量组T2-T4时HR、T2-T5时MAP、T2-T6时LA和cTnI、术后心血管不良事件、鼻温肛温复温时间、术后24h N端脑钠肽前体(NT-proBNP)水平低于对照组,而T2-T6时ScvO_(2)和尿量、心脏自动复跳率高于对照组(P<0.05);高剂量组T2时HR和MAP低于低剂量组,而鼻温肛温复温时间、术后24h NT-proBNP高于低剂量组(P<0.05)。结论:低剂量的Dex即可取得良好的麻醉镇静效果,维持血流动力学的相对稳定,在麻醉诱导开始前10min时输注0.2μg/kg·h^(-1)Dex可有效改善CPB下瓣膜置换术对微循环的影响,降低LA和cTnI水平、提高ScvO_(2)和尿量、缩短鼻温肛温的复温时间。

关键词：右美托咪定脑电双频谱指数体外循环瓣膜置换术微循环

CH_4 emissions and reduction potential in wastewater treatment in China

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Advances in Climate Change Research 2015年第3期6卷 216-224页

作者： MA Zhan-Yun FENG Peng gao qing-xian LU Yan-Na LIU Jun-Rong LI Wen-Tao Chinese Research Academy of Environmental Sciences China Center for Resource Satellite Data and Applications College of Forestry Gansu Agricultural University

The treatment of domestic and industrial wastewater is one of the major sources of CH_4 in the Chinese waste sector. On the basis of statistical data and country-specific emission factors, using IPCC methodology, the characteristics of CH_4 emissions from wastewater treatment in China were analyzed. The driving factors of CH_4 emissions were studied, and the emission trend and reduction potential were predicted and analyzed according to the current situation. Results show that in 2010, CH_4 emissions from the treatment of domestic and industrial wastewater were0.6110 Mt and 1.6237 Mt, respectively. Eight major industries account for more than 92% of emissions, and CH_4 emissions gradually increased from 2005 to 2010. From the controlling management scenario, we predict that in 2020, CH_4 emissions from the treatment of domestic and industrial wastewater will be 1.0136 Mt and 2.3393 Mt, respectively, and the reduction potential will be 0.0763 Mt and 0.2599 Mt, *** 2010 to 2020, CH_4 emissions from the treatment of domestic and industrial wastewater will increase by 66% and 44%, respectively.

关键词： Domestic and industrial wastewater CH4 emissions Reduction scenario Emission reduction potential

A compact X-band backward traveling-wave accelerating structure

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Nuclear Science and Techniques 2024年第5期35卷 13-29页

作者： xian-Cai Lin Hao Zha Jia-Ru Shi Qiang gao Fang-Jun Hu qing-Zhu Li Huai-Bi Chen Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle and Radiation Imaging(Tsinghua University) Ministry of EducationBeijing 100084China

Very high-energy electrons(VHEEs)are potential candidates for FLASH radiotherapy for deep-seated *** proposed a compact VHEE facility based on an X-band high-gradient high-power *** this study,we investigated and realized the first X-band backward traveling-wave(BTW)accelerating structure as the buncher for a VHEE facility.A method for calculating the parameters of single cell from the field distribution was introduced to simplify the design of the BTW ***-domain circuit equations were applied to calculate the transient beam parameters of the buncher in the unsteady state.A prototype of the BTW structure with a thermionic cathode-diode electron gun was designed,fabricated,and tested at high power at the Tsinghua X-band high-power test *** structure successfully operated with 5-MW microwave pulses from the pulse compressor and outputted electron bunches with an energy of 8 MeV and a pulsed current of 108 mA.

关键词： Backward traveling-wave accelerating structure Equivalent circuit model High-power test Very high-energy electron radiotherapy

Communication Resource-Efficient Vehicle Platooning Control With Various Spacing Policies

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IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 362-376页

作者： Xiaohua Ge qing-Long Han xian-Ming Zhang Derui Ding IEEE School of Science Computing and Engineering TechnologiesSwinburne University of TechnologyMelbourne VIC 3122Australia

Platooning represents one of the key features that connected automated vehicles may possess as it allows multiple automated vehicles to be maneuvered cooperatively with small headways on roads. However, a critical challenge in accomplishing automated vehicle platoons is to deal with the effects of intermittent and sporadic vehicle-to-vehicle data transmissions caused by limited wireless communication resources. This paper addresses the co-design problem of dynamic event-triggered communication scheduling and cooperative adaptive cruise control for a convoy of automated vehicles with diverse spacing policies. The central aim is to achieve automated vehicle platooning under various gap references with desired platoon stability and spacing performance requirements, while simultaneously improving communication efficiency. Toward this aim, a dynamic event-triggered scheduling mechanism is developed such that the intervehicle data transmissions are scheduled dynamically and efficiently over time. Then, a tractable co-design criterion on the existence of both the admissible event-driven cooperative adaptive cruise control law and the desired scheduling mechanism is derived. Finally, comparative simulation results are presented to substantiate the effectiveness and merits of the obtained results.

关键词： Automated vehicles constant time headway spacing constant spacing cooperative adaptive cruise control event-triggered communication vehicle platooning

Spatial covariant gravity with two degrees of freedom in the presence of an auxiliary scalar field:Perturbation analysis

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Chinese Physics C 2024年第8期48卷 198-212页

作者： Zhi-Chao Wang xian gao School of Physics and Astronomy Sun Yat-sen UniversityZhuhai 519082China

We investigate a class of gravity theories respecting only spatial covariance,termed spatially covariant gravity,in the presence of an auxiliary scalar *** examine the conditions on the Lagrangian required to eliminate scalar degrees of freedom,allowing only two tensorial degrees of freedom to *** of strict constraint analysis,in this paper,we employ the perturbation method and focus on the necessary conditions to evade the scalar mode at the linear order in perturbations around a cosmological *** with a general action and solving the auxiliary perturbation variables in terms of a would-be dynamical scalar mode,we derive the condition to remove its kinetic term,thus ensuring that no scalar mode *** an application of the general condition,we study a polynomial-type Lagrangian as a concrete example,in which all monomials are spatially covariant scalars containing two *** find that the auxiliary scalar field is essential,and new terms in the Lagrangian are *** analysis provides insights into constructing gravity theories with two degrees of freedom in the extended framework of spatially covariant gravity.

关键词： modified gravity cosmological perturbation theory gravitational theory

Trace elements in magmatic and hydrothermal quartz:Implications on the genesis of the Xingluokeng Tungsten Deposit,South China

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Acta Geochimica 2024年第3期43卷 441-458页

作者： qing-qing Zhang You-Wei Chen Jian-Feng gao State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China University of Chinese Academy of Sciences Beijing 100049China

The Xingluokeng deposit is the largest gran-ite-related tungsten deposit within the Wuyi metallogenic belt in South *** Xingluokeng intrusion primarily consists of porphyritic biotite granite,biotite granite,andfine-grained *** deposit is represented by veinlet-disseminated mineralization with K-feldspathization and biotitization,alongside quartz-vein mineralization with gre-isenization and *** study investigates in-situ analyses of quartz compositions from both the intrusion and hydrothermal veinlets and *** element correlations indicate that trivalent Al^(3+)and Fe^(3+)replace Si^(4+)within the quartz lattice,with monovalent cations(such as Li^(+),Na^(+),and K^(+))primarily serving as charge *** Ge/Al ratios(<0.013)of quartz from granites suggest a mag-matic *** low Al/Ti and Ge/Ti ratios,accompanied by high Ti contents in quartz,suggest that the porphyritic biotite granite and biotite granite are characterized by rela-tively low levels of differentiation and high crystallization *** contrast,thefine-grained granite exhibits a higher degree of fractionation,lower crystallization tem-peratures,and a closer association with tungsten *** contents in quartz from quartz veins indicate Qz-Ⅰformed at temperatures above 400°C,while Qz-Ⅱto Qz-Ⅴformed at temperatures below 350°*** in different generations of quartz,as indicated by Al content and(Al+Fe)/(Li+Na+K)ratio,suggest that Qz-Ⅰprecipi-tated from a less acidicfluid with a stable pH,whereas Qz-Ⅱto Qz-Ⅴoriginated from a more acidicfluid with notable pH ***,alkaline alteration and acidic alteration supplied the essential Ca and Fe for the precipita-tion of scheelite and wolframite,respectively,highlighting a critical mechanism in tungsten mineralization at the Xin-gluokeng deposit.

关键词： Quartz Xingluokeng Tungsten deposit Trace elements South China

Estimation of Methane Emissions from Municipal Solid Waste Landfills in China Based on Point Emission Sources

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Advances in Climate Change Research 2014年第2期5卷 81-91页

作者： CAI Bo-Feng LIU Jian-Guo gao qing-xian NIE Xiao-Qin CAO Dong LIU Lan-Cui ZHOU Ying ZHANG Zhan-Sheng Chinese Academy for Environmental Planning School of Environment Tsinghua University Chinese Research Academy of Environmental Sciences China Urban Construction Design and Research Institute

The methane(CH4) emissions from municipal solid waste(MSW) landfills in China in 2007 were estimated based on database of the three-dimensional emission factors matrix and point sources, by an IPCC recommended FOD(firstorder decay) model. The location, capacity and age of landfills constitute the three dimensions of the emission factors matrix, which were obtained by laboratory analysis and in situ investigation. Key parameters such as waste composition,degradable organic carbon ratio, CH4 correction factor, oxidation factor and recovery rate, were carefully analyzed in terms of these three dimensions. The point sources database consists of 2,107 MSW landfills in cities and towns of China in 2007. The results show that the CH4 emissions from MSW landfills were 1.186 Mt in 2007. Compared with the CH4 emissions of 2.20 Mt in 2005, the significant discrepancy mainly comes from statistical data of landfills, e.g., number of landfills and amount of waste disposed in landfills. CH4 emissions were lower than 700 t for most of the landfills, whereas there were 279 landfills with emissions larger than 1,000 t, and only 10 landfills with emissions larger than 10,000 *** province ranks the largest emitter with 98,700 t while Tibet is the smallest emitter with 2,100 t. In general,the emissions from eastern provinces, such as Jiangsu, Guangdong and Zhejiang, were larger than those from western provinces, such as Ningxia, Tibet and qinghai.

关键词： municipal solid waste landfill CH4 emissions point emission sources

Projected changes in Köppen-Trewartha climate zones under 1.5-4℃global warming targets over mid-high latitudes of Northern Asia using an ensemble of RegCM4 simulations

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Advances in Climate Change Research 2024年第2期15卷 185-196页

作者： Jie WU Xue-Jie gao xian-Bing TANG Filippo GIORGI School of Geography and Environmental Engineering Gannan Normal UniversityGanzhou 341000China Climate Change Research Center Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044China University of Chinese Academy of Sciences Beijing 100049China The Abdus Salam International Centre for Theoretical Physics Trieste 34100Italy

Mid-high latitude Northern Asia is one of the most vulnerable and sensitive areas to global warming,but relatively less studied *** used an ensemble of a regional climate model(RegCM4)projections to assess future changes in surface air temperature,precipitation and Köppen-Trewartha(K-T)climate types in Northern Asia under the 1.5-4℃global warming ***4 is driven by five CMIP5 global models over an East Asia domain at a grid spacing of 25 *** of the present day(1986-2005)simulations shows that the ensembles of RegCM4(ensR)and driving GCMs(ensG)reproduce the major characters of the observed temperature,precipitation and K-T climate zones reasonably *** and more realistic spatial detail is found in RegCM4 compared to the driving GCMs.A general warming and overall increases in precipitation are projected over the region,with these changes being more pronounced at higher warming *** projected warming by ensR shows different spatial patterns,and is in general lower,compared to ensG in most months of the year,while the percentage increases of precipitation are maximum during the cold *** future changes in K-T climate zones are characterized by a substantial expansion of Dc(temperature oceanic)and retreat of Ec(sub-arctic continental)over the region,reaching∼20%under the 4℃warming *** most notable change in climate types in ensR is found over Japan(∼60%),followed by Southern Siberia,Mongolia,and the Korean Peninsula(∼40%).The largest change in the K-T climate types is found when increasing from 2 to 3℃.The results will help to better assess the impacts of climate change and in implementation of appropriate adaptation measures over the region.

关键词： Mid-high latitudes of Northern Asia Köppen climate zones Global warming targets Regional climate model