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Spatiotemporal Trends and Ecological Determinants in Population by Elevation in China Since 1990

Chinese Geographical Science 2021年第2期31卷 248-260页

作者： ma chaoqun HE Yanfen College of Earth Science and Resources Chang’an UniversityXi’an 710054China Yellow River Institute of Shaanxi Province College of Urban and Environment SciencesNorthwest UniversityXi’an 710127China

It is very important to understand the ecological and socio-economic factors in population distribution and their changes over time for the compilation of regional development planning and the guidance of rational population *** surface-based population data for China from 1990 to 2015,the national distribution and dynamics of the human population by elevation are quantified based on 1-km cell-size gridded distribution datasets and 1-km cell-size DEM(digital elevation model).A geographical detector model is used to quantitatively analyze the dominant role of natural geographical factors,such as topography and climate,on the spatial distribution of *** show that:1)the population size and density decrease rapidly with elevation below 1000 m above the sea level,and the gap in population density between low-altitude areas and high-altitude areas increases with time because of the continuous growth of population density in low-altitude areas;2)the distribution of the population can be divided into five steps according to integrated population density(IPD),in proportions of 43∶35∶21∶1∶0,and that these proportions have remained stable over the last 25 yr;3)the basic pattern of population spatial distribution is determined by natural geographical environment factors,such as topography,climate,geomorphology,and their interactions;and 4)the development of society and the economy are the driving forces for the dynamic change in the population distribution during the study period,with the distribution pattern and dynamics of population by altitude in China providing a comprehensive reflection of various geographical elements on different spatial scales.

关键词： population distribution vertical distribution hypsographic demography geographical detector model China

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不同格网尺度下生态系统服务价值空间分异及影响因素分析--以秦岭西安段为例

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水土保持研究 2025年第1期32卷 389-399页

作者：马超群弋志强员学锋张硕蒙张莎莎长安大学土地工程学院西安710064 陕西省土地整治重点实验室西安710064

[目的]探究生态系统服务价值空间分异的尺度效应,为秦岭地区的生态保护和经济发展决策提供参考。[方法]运用改进当量因子法,计算了2020年秦岭西安段5 km,3 km,2 km,1 km和0.5 km共5个格网尺度水平上的生态系统服务价值;采用空间自相关... 详细信息

[目的]探究生态系统服务价值空间分异的尺度效应,为秦岭地区的生态保护和经济发展决策提供参考。[方法]运用改进当量因子法,计算了2020年秦岭西安段5 km,3 km,2 km,1 km和0.5 km共5个格网尺度水平上的生态系统服务价值;采用空间自相关分析和冷热点分析归纳了不同尺度下地均ESV空间分异特征;并利用地理探测器对各尺度下的影响因素作用强度进行定量分析。[结果](1)地均ESV总体上呈北低南高的分布格局,具有小分散、大集聚的空间分布特征,并随尺度降低,其局部越丰富,但整体性降低;(2)2 km尺度适合进行宏观分析和做整体性布局规划,1 km尺度适合进行水域变化对区域ESV影响的研究;(3)格网尺度越小,各影响因素内部差异增加,其整体性特征减少,局部特征差异凸显,空间分异性增强;(4)人类活动带来的土地利用方式转变显著影响区域生态系统服务价值,多因素耦合作用显著影响区域地均ESV空间分异,随尺度降低,其影响减弱。[结论]秦岭西安段的生态保护要重点关注区域土地利用性质的转变,可继续加强退耕还林政策,管控建设用地的规模,在兼顾生态保护的基础上,制定经济发展的布局规划。

关键词：生态系统服务价值空间分异地理探测器多尺度秦岭西安段

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Long memory and nonlinear dependence structure in crude oil futures returns and volatility

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Journal of Southeast University(English Edition) 2008年第S1期24卷 82-87页

作者： Li, Hongquan Wang, Shouyang ma, chaoqun Academy of mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China School of Business Administration Hunan University Changsha 410082 China

In order to investigate the nature of international crude oil futures and present evidence of long memory and nonlinear dependence for crude oil futures volatility as well as returns, a certain number of recent statistical tests, such as the powerful BDS test, the fractional integration test and other known statistics, are applied. The results show that though the returns themselves contain little serial correlation, the market volatility series have significant long-term dependence structures which may have important implications for volatility forecasts and derivative pricing. On the other hand, evidence of strong ARCH effect is also presented, and, moreover, the BDS statistics on the standardized residuals of the fitted GARCH model indicate that the ARCH-type process may generally explain the nonlinearities in the data. It seems that the crude oil futures market can be appropriately modeled by ARCH and fractal processes. These findings indicate that it would be beneficial to assess the behavior of the crude oil and price the oil derivative contracts by encompassing long memory and nonlinear structure.

关键词： long memory nonlinearity volatility fractal crude oil futures

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Comparisons of Three-Dimensional Variational Data Assimilation and Model Output Statistics in Improving Atmospheric Chemistry Forecasts

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Advances in Atmospheric Sciences 2018年第7期35卷 813-825页

作者： chaoqun ma Tijian WANG Zengliang ZANG Zhijin LI School of Atmospheric Sciences Nanjing University Nanjing 210023 China Cma-NJU Joint Laboratory for Climate Prediction Studies Nanjing 210023 China jiangsu Collaborative Innovation Center for Climate Change Nanjing 210023 China Institute of Meteorology and Oceanography PLA University of Science and Technology Nanjing 210000 China Joint Institute for Regional Earth System Science and Engineering University of California Los Angeles 90001 California USA

Atmospheric chemistry models usually perform badly in forecasting wintertime air pollution because of their uncertainties. Generally, such uncertainties can be decreased effectively by techniques such as data assimilation（DA） and model output statistics（MOS）. However, the relative importance and combined effects of the two techniques have not been clarified. Here,a one-month air quality forecast with the Weather Research and Forecasting-Chemistry（WRF-Chem） model was carried out in a virtually operational setup focusing on Hebei Province, China. Meanwhile, three-dimensional variational（3 DVar） DA and MOS based on one-dimensional Kalman filtering were implemented separately and simultaneously to investigate their performance in improving the model forecast. Comparison with observations shows that the chemistry forecast with MOS outperforms that with 3 DVar DA, which could be seen in all the species tested over the whole 72 forecast hours. Combined use of both techniques does not guarantee a better forecast than MOS only, with the improvements and degradations being small and appearing rather randomly. Results indicate that the implementation of MOS is more suitable than 3 DVar DA in improving the operational forecasting ability of WRF-Chem.

关键词： data assimilation model output statistics WRF-Chem operational forecast

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Performance evaluation of anti-radiation based on the gamma degradation process

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Science China(Technological Sciences) 2017年第4期60卷 501-509页

作者： SONG BingHua ZHOU ZhongBao ma chaoqun JIN Guang GENG ShaoFeng School of Business Administration Hunan University Changsha 410082 China College of Information System and management National University of Defense Technology Changsha 410073 China College of Computer Science and Electronic Engineering Hunan University Changsha 410082 China

In the environment of space radiation, the high-energy charged particles or high-energy photons acting on a spacecraft can cause either temporary device degradation or permanent failure. The traditional probability model is difficult to obtain reliable estimation of unit radiation resistance performance with small samples. Considering that different products will change differently after high-energy particle radiation, we construct a model based on the gamma degradation process. This model can efficiently describe the law of unit radiation resistance variation with the total radiation dose levels under the effect of the total dose and displacement damage. Finally, the proposed model is used to assess the anti-radiation performance of the N-channel power MOSFET device STRH60N20FSY3 produced by STM to obtain average unit radiation resistance, survival probability, survival function, etc.

关键词： performance evaluation unit radiation resistance gamma degradation process survival probability

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Reliability analysis of monotone coherent multi-state systems based on Bayesian networks

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Journal of Systems Engineering and Electronics 2016年第6期27卷 1326-1335页

作者： Binghua Song Zhongbao Zhou chaoqun ma Jinglun Zhou Shaofeng Geng School of Business Administration Hunan University School of Information System and management National University of Defense Technology College of Computer Science and Electronic Engineering Hunan University

The Bayesian networks (BNs) provide a robust probabilistic method of reasoning under uncertainty and have been successfully applied to a variety of real-world tasks. Aiming to explore the capabilities of the BN formalism in reliability analysis of monotone coherent multi-state systems, the BNs are compared with a popular tool for reliability analysis of monotone coherent multi-state systems, namely the multi-state fault trees (MFTs). It is shown that any MFT can be directly mapped into BN and the basic inference techniques on the latter may be used to obtain classical parameters computed from the former (i.e. probability distribution of top variable, minimal upper vectors and maximum lower vectors for any performance level, importance measures of components). Furthermore, some additional information can be obtained by using BN, both at the modeling and analysis level. At the modeling level, several restrictive assumptions implicit in the MFT methodology can be removed and various kinds of dependencies among components can be accommodated. At the analysis level, a general diagnostic analysis can be performed. The comparison of these methods is illustrated by an example of the water supply system. © 2016 Beijing Institute of Aerospace Information.

关键词： Bayesian networks Probability distributions Reliability Reliability theory Vectors Water supply Water supply systems

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The privacy protection mechanism of Hyperledger Fabric and its application in supply chain finance

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Cybersecurity 2019年第1期2卷 91-99页

作者： chaoqun ma Xiaolin Kong Qiujun Lan Zhongding Zhou Business School Hunan UniversityChangsha 410082China

Blockchain technology ensures that data is tamper-proof,traceable,and *** article introduces a wellknown blockchain technology implementation—Hyperledger *** basic framework and privacy protection mechanisms of Hyperledger Fabric such as certificate authority,channel,Private Data Collection,*** *** an example,a specific business scenario of supply chain finance is figured *** accordingly,some design details about how to apply these privacy protection mechanisms are described.

关键词： Privacy protection Supply chain finance Hyperledger Fabric

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Surface hydrophobic modification of MXene to promote the electrochemical conversion of N_(2) to NH_(3)

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Journal of Energy Chemistry 2023年第12期87卷 439-449,I0011页

作者： Xu Wang Rui Zhang chaoqun ma Wei Yan Yanjiao Wei Jian Tian Min ma Qing Li Minhua Shao School of materials Science and Engineering Shandong University of Science and TechnologyQingdao 266590ShandongChina Department of Chemical and Biological Engineering The Hong Kong University of Science and TechnologyClear Water BayKowloonHong Kong 999077China Energy Institute and Chinese National Engineering Research Center for Control&Treatment of Heavy Metal PollutionThe Hong Kong University of Science and TechnologyClear Water BayKowloonHong Kong 999077China College of Chemistry and Chemical Engineering Xiamen UniversityXiamen 361005FujianChina College of Chemistry and Chemical Engineering Dezhou UniversityDezhou 253023ShandongChina

Hydrophobic treatment of the catalyst surfaces can suppress the competitive hydrogen evolution reaction(HER) during the nitrogen reduction reaction(NRR).In this work,the surface of Ti_(3)C_(2)Ti_(x) MXene is modified by cetyltrimethylammonium bromide(CTAB) and trimethoxy(3,3,4,4,5,5,6,6,7,7,8,8,8-trideca fluorooctyl) silane(FOTS) to increase the hydrophobicity of *** ammonia(NH_(3)) production rate and faradaic efficiency(FE) are improved from 37.62 to 54.01 μg h^(-1)mg_(cat)^(-1).and 5.5% to 18.1% at-0.7 V ***,respectively after surface modification.^(15)N isotopic labeling experiment confirms that nitrogen in produced ammonia originates from N_(2) in the *** excellent NRR activity of surface hydrophobic MXenes is mainly due to surfactant molecules,which inhibit the entry of water molecules and the competitive HER,which have been verified by in situ FT-IR,DFT and molecular dynamics *** strategy provides an ingenious method to design more active NRR electrocatalysts.

关键词： Electrocatalysis Nitrogen reduction reaction Surface hydrophobic modification MXene Ti_(3)C_(2)Ti_(x)

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Zinc finger 4 negatively controls the transcriptional activator Fzf1 in Saccharomyces cerevisiae

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mLife 2024年第3期3卷 391-402页

作者： Ying Du chaoqun ma Stanley A.Moore Wei Xiao Department of Biochemistry Microbiology and ImmunologyUniversity of SaskatchewanSaskatoonSaskatchewanCanada

Fzf1 is a Saccharomyces cerevisiae transcription factor containing five zinc fingers(ZFs).It regulates the expression of at least five downstream genes,including SSU1,YHB1,DDI2/3,and YNR064c,by recognizing a consensus sequence,CS2,found in these gene *** gene products are involved in cellular responses to various chemical *** example,SsU1 encodes a sodium sulfite efflux protein that confers sulfite ***,the underlying molecular mecha-nism through which Fzf1 responds to chemical stress and coordinates target gene activation remains ***,several mutations in the fourth ZF(ZF4)of Fzf1 have previously been reported to confer either sulfite resistance or elevated basal-level expression of YHB1,indicating that ZF4 negatively impacts Fzf1 *** ZF4 is dispensable for CS2 binding in vitro,we hypothesized that ZF4 is a negative regulator of Fzf1 and that chemically induced Fzf1-regulated gene expression occurs via *** five genes examined were cross-induced by corresponding chemicals in an Fzf1-dependent manner,and all three ZF4 mutations and a ZF4 deletion conferred increased basal-level expression and ssU1-dependent sulfite resistance.A ZF4 deletion did not alter the target DNA binding,consistent with the observed codominant *** observations collectively reveal that Fzf1 remains inactive by default at the target promoters and that its activation is at least partially achieved by self-derepression through chemical modification and/or a conformational change.

关键词： chemical toxicity Fzf1 Saccharomyces cerevisiae transcription regulation zinc finger

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Will Tax Burden Be a Stumbling Block to Carbon-Emission Reduction? Evidence from OECD Countries

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Journal of Systems Science and Information 2021年第4期9卷 335-355页

作者： Yishuai REN Yong JIANG chaoqun ma Jianglong LIU Jing CHEN School of Public Administration Hunan UniversityChangsha 410082China Research Institute of Digital Society and Blockchain Hunan UniversityChangsha 410082China Centre for Resource and Environmental management Hunan UniversityChangsha 410082China China Institute for Urban-Rural Development and Community Governance Hunan UniversityChangsha 410082China The Energy Centre University of AucklandAuckland 1142New Zealand School of Finance Nanjing Audit UniversityNanjing 211815China Business School Hunan UniversityChangsha 410082China School of Economics and management Xidian UniversityXVan 710071China College of Natural Sciences and mathematics The University of West AlabamaLivingston 35470USA

The influence of taxation on the economy and society is everywhere. Given the fact that CO_(2) emission is closely connected with human activities, the question naturally arises whether the tax burden affects the carbon emissions. To address this issue, based on the data of 21 OECD countries over the period from 1991–2014, we use the ratio of tax revenue to GDP as a proxy of the tax burden and employ a panel quantile model with the non-additive fixed effects for analysis. The results suggest that the impact of the tax burden on carbon emissions is heterogeneous across countries based on the level of carbon emissions. Moreover, we find a stable U-shaped relationship between the tax burden and carbon emissions whether for countries with a high or low level of carbon emissions. Our findings suggest that moderate taxes could help reduce carbon emissions, but the effect of excessive taxation is the opposite.

关键词： tax burden carbon emissions panel quantiles OECD countries

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