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Relationship between multi-scale climate factors and performance of ecological engineering on the Loess Plateau, China

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Journal of Forestry Research 2022年第3期33卷 789-800页

作者： Panxing He Jun Ma Zhiming Han Mingjie Shi Dongxiang Xu Zongjiu Sun Ministry of Education Key Laboratory for Biodiversity Science and Ecological EngineeringNational Observations and Research Station for Wetland Ecosystems of the Yangtze EstuarySchool of Life SciencesFudan UniversityShanghai200438People’s Republic of China Ministry of Education Key Laboratory for Western Arid Region Grassland Resources and Ecology College of Grassland and Environment SciencesXinjiang Agricultural UniversityUrumqi830052People’s Republic of China State Key Laboratory Base of Eco-Hydraulic Engineering in Arid Areas Xi’an University of TechnologyXi’an710077People’s Republic of China School of Earth and Environmental Sciences University of QueenslandSt Lucia4072Australia

The long-term “Grain-to-Green Program” (GGP) on China’s Loess Plateau is a major global ecological engineering project which has significantly boosted vegetation renewal. Some studies have found that the rate of restoration is quite rapid during the implementation of ecological engineering, however, the influence of multi-scale climatic conditions on the performance of ecological engineering is unclear. In this study, multiple sources of remote sensing data were used to estimate the dynamics of vegetation structural and functional indicators, water-related local climatic factors, and atmospheric circulation factors. These datasets were also used to detect possible causes for vegetation restoration on the Loess Plateau over the past 20 years. The results show that widespread increases in rates of normalized difference vegetation indexes (NDVI), leaf area indexes (LAI), gross primary production (GPP), and aboveground biomass carbon (ABC) during 2000–2016 were significantly higher than before 2000. GPP was significantly correlated with rainfall and surface runoff on a monthly scale, and there were significant positive correlations between GPP and atmospheric circulation. Our results demonstrate that both vegetation structural and functional indicators rapidly increase, and ecological engineering greatly accelerated vegetation restoration after 2000. Local climatic conditions and atmospheric circulation patterns enhance vegetation growth and impact of ecological engineering.

关键词： Vegetation restoration Ecological engineering Water-related climatic factors Atmospheric circulation and sunspot Loess Plateau

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Combining gradual and abrupt analysis to detect variation of vegetation greenness on the loess areas of China

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Frontiers of Earth Science 2022年第2期16卷 368-380页

作者： Panxing HE Zongjiu SUN Dongxiang Xu Huixia LIU Rui YAO Jun MA Ministry of Education Key Laboratory for Western Arid Region Grassland Resources and Ecology College of Grassland and Environment SciencesXinjiang Agricultural UniversityUrumqi 830000China Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering Institute of Biodiversity ScienceFudan UniversityShanghai 200438China School of Earth and Environmental Sciences University of QueenslandQueensland 4072Australia Hubei Key Laboratory of Critical Zone Evolution School of Geography and Information EngineeringChina University of GeosciencesWuhan 430074China

The annual peak growth and trend shift of vegetation are critical in characterizing the carbon sequestration capacity of ecosystems.As the well-known area with the fastest vegetation growth in the world,the Loess Plateau(LP)lands find an enhanced greening trend in the annual and growing-season.However,the spatiotemporal dynamics of vegetation peak growth and breakpoints characteristics on time series still needs to be explored.Here,we performed tendency analysis to characterize recent variations in annual peak vegetation growth through a satellite-derived vegetation index(NDVI_(max),Maximum Normalized Difference Vegetation Index)and then applied breakpoint analysis to capture abrupt points on the time series.The results demonstrated that the vegetation peak trend had been significantly increasing,with a growth rate at 0.68×10^(-2)·a^(-1) during 2001-2018,and most pixels(70.81%)have a positive linear greening trend over the entire LP.In addition,about 83%of the breakpoint type on the monthly NDVI time series is a monotonic increase at the pixel level,and most pixels(57%)have detected breakpoints after 2010.Our results also showed that the growth rate accelerates in the northwest and decelerates in the southeast after the breakpoint.This study indicates that combining abrupt analysis with gradual analysis can describe vegetation dynamics more effectively and comprehensively.The findings highlighted the importance of breakpoint analysis for monitor timing and shift using time series satellite data at a regional scale,which may help stakeholders to make reasonable and effective ecosystem management policies.

关键词： vegetation greenness gradual trend breakpoint BFAST algorithm the Loess Plateau area

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Enhanced charge separation by incomplete calcination modified co-doped TiO_(2)nanoparticle for isothiazolinone photocatalytic degradation

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Nano Research 2024年第6期17卷 4834-4843页

作者： Zhiren Guo Xiao Zhang Xinyuan Li Chang Cui Zilei Zhang Hansheng Li dongxiang Zhang Jinying Li Xiyan xu Jiatao Zhang School of Chemistry and Chemical Engineering Beijing Institute of TechnologyBeijing 102488China Department of Chemistry MSU-BIT UniversityShenzhen 517182Chin

Photocatalytic oxidation techniques are promising for degradation of the highly ecotoxic and refractory isothiazolinone bactericides in relevant industrial wastewaters.However,low charge separation and directional transport efficiency under solar light radiation restrain their practical application.Here,we report a nanostructured photocatalyst doped with Gd and B in TiO_(2)with carbon incorporation and defect formation through incomplete calcination.The specific surface area,grain size,and hydrophilicity of TiO_(2)are improved,which is beneficial for the interfacial reaction between the photocatalyst and pollutants.The reduction of the bandgap,the broadening of the photo-absorption range,and the retarded electron-hole recombination promote the photocatalytic performance due to the improved oxygen vacancies based on the electron distribution modification.The difference in partial density of states(ΔPDOS)between the current catalyst and raw TiO_(2)indicates that the co-doping of Gd and B with incomplete calcination changes the electronic hybridization of conduction band and valence band near the Fermi level,and affects the band gap energy.It improved charge separation and directional transport efficiency and benefited the formation of main active species,including•OH and O2•−,for the pollutant decomposition.The rate of photocatalytic removal of benzisothiazolinone(BIT)by the current photocatalyst reaches 1.25 h^(−1),being 4.31 times that of TiO_(2).The current work offers a constructive approach to the design and synthesis of nanostructured photocatalysts for the photocatalytic degradation of refractory organic pollutants.

关键词： TiO_(2)nanoparticle charge separation oxygen vacancies electron distribution modification photocatalytic degradation

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A BODIPY-based Fluorescent Probe for Thiophenol

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Chinese Journal of Chemistry 2018年第2期36卷 119-123页

作者： dongxiang Zhang Ning xu Liman Xian Haoying Ge Jiangli Fan Jianjun Du Xiaojun Peng State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 116024 China

Thiophenol has been listed as one of the main sources of pollution. Sensitive probes for thiophenol are very significant. Herein, a BODIPY-based fluorescent probe, named BDP, for poisonous thiophenol detection has been reported. BDP shows rapid response （15 s） and clear fluorescence enhancement （30 folds） to thiophenol in solution. The intensity of fluorescence and concentration of thiophenol have a good linear relationship. The detection limit is as low as 13.6 nmol·L^-1： BDP is stable towards pH and light radiation. Cell experiments demonstrate that BDP has good cell membrane penetrability, low cell toxicity and excellent imaging properties in living cells. Therefore, BDP has significant value on the detection of thiophenol in solution and in living cell.

关键词： thiophenol BODIPY fluorescent probe cell imaging

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Preparation and photocatalytic kinetics of nano-ZnO powders by precipitation stripping process

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Frontiers of Chemical Science and Engineering 2008年第3期2卷 319-324页

作者： dongxiang ZHANG Hang xu Min xuE Wenguo xu V TARASOV School of Chemical Engineering and the Environment Beijing Institute of TechnologyBeijing 100081China School of Science Beijing Institute of TechnologyBeijing 100081China D.I.Mendeleyev University of Chemical Technology of Russia 125190 MoscowRussia

Ultra-fine zinc oxalate powders were prepared through a precipitation stripping method with bis(2-ethylhexyl)phosphate(HDEHP)diluted by tetrachloride carbon as the extractant,and oxalic acid ethanol aqueous solution as the re-extractant and precipitator.Zinc oxide powders were obtained by decomposing zinc oxalate powders at 450℃.The prepared zinc oxide powders were characterized by transmission electron microscope(TEM),Scanning electron microscope(SEM),Thermogravimetric analysis(TG),X-ray diffraction(XRD)and Fourier transmission infrared(FT-IR)spectrum.The photocatalytic performance of methylene blue by zinc oxide was studied based on the Langmuir model and Photo-Layer model.The results show that some zinc oxide powders were micro-multipore materials with hexagonal crystal.The particle size was around 32 nm.The photocatalytic process was the control step in the chemical reaction.The photo catalytic process followed pseudo-first order kinetics and NOH concentration inside the photo-layer in different reaction condition were calculated according to the Photo-Layer model.

关键词： precipitation stripping method ZnO photocatalysis kinetics

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面向不平衡数据集的机器学习分类策略

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计算机工程与应用 2020年第24期56卷 12-27页

作者：徐玲玲迟冬祥上海电机学院电子信息学院上海201306

由于不平衡数据集的内在固有特性,使得分类结果常受数量较多的类别影响,造成分类性能下降。近年来,为了能够从类别不平衡的数据集中学习数据的内在规律并且挖掘其潜在的价值,提出了一系列基于提升不平衡数据集机器学习分类算法准确率的... 详细信息

由于不平衡数据集的内在固有特性,使得分类结果常受数量较多的类别影响,造成分类性能下降。近年来,为了能够从类别不平衡的数据集中学习数据的内在规律并且挖掘其潜在的价值,提出了一系列基于提升不平衡数据集机器学习分类算法准确率的研究策略。这些策略主要是立足于数据层面、分类模型改进层面来解决不平衡数据集分类难的困扰。从以上两个方面论述面向不平衡数据集分类问题的机器学习分类策略,分析和讨论了针对不平衡数据集机器学习分类器的评价指标,总结了不平衡数据集分类尚存在的问题,展望了未来能够深入研究的方向。特别的,这些讨论的研究主要关注类别极端不平衡场景下的二分类问题所面临的困难。

关键词：不平衡数据集重采样策略分类模型评价指标

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舰载激光武器毁伤能力的建模与仿真

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系统仿真技术 2021年第2期17卷 94-97页

作者：徐东翔解放军91404部队河北秦皇岛066001

随着舰载激光武器的不断发展,利用激光武器防御反舰导弹成为了一种重要手段。现有的激光武器毁伤效果模型较为简单,与实际应用存在一定差距。通过分析激光在大气中的传输特性,结合实际应用中存在的跟踪误差,建立了一种激光武器功率密度... 详细信息

随着舰载激光武器的不断发展,利用激光武器防御反舰导弹成为了一种重要手段。现有的激光武器毁伤效果模型较为简单,与实际应用存在一定差距。通过分析激光在大气中的传输特性,结合实际应用中存在的跟踪误差,建立了一种激光武器功率密度模型。通过仿真,分析了跟踪误差对功率密度的影响,为今后制定激光武器使用策略提供参考依据。

关键词：激光武器功率密度跟踪误差

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Effect of age on aortic atherosclerosis

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Journal of Geriatric Cardiology 2013年第2期10卷 135-140页

作者： Michael A. Chen Miwa Kawakubo Patrick M. Colletti Dongxiang Xu Laurie LaBree Dustin Robert Detrano Stanley P Azen Nathan D. Wong xue-Qiao Zhao Department of Medicine Division of Cardiology Harborview Medical Center/University of Washington 325 9th Avenue Box 359748 Seattle WA 98104 USA Department of Preventive Medicine Division of Biostatistics Keck School of Medicine of the University of Southern California 2001 N Soto Street SSB 201A M/C 9234 Los Angeles CA 90089-9237 USA Department of Radiology Keck School of Medicine of the University of Southern California1 1500 San Pablo Street Second Floor Imaging Los Angeles CA 90033 USA Department of Radiology University of Washington School of Medicine Box 357115 1959 Pacific Street RR-215 Seattle WA 98195-7117 USA Department of Radiological Sciences University of California Irvine School of Medicine 101 the City Drive South Route 140 Orange CA 92868 USA Department of Medicine UC Irvine School of Medicine 333 City Blvd. West Suite 400 Orange CA 92868-3298 USA

Objective To examine the association of atherosclerosis burden in the survivors of an asymptomatic elderly cohort study and its relationship to other coronary risk factors (specifically, age) by evaluating aortic atherosclerotic wall burden by magnetic resonance imaging (MRI). Methods A total of 312 participants in an ongoing observational cohort study underwent cardiac and descending thoracic aorta imaging by MRI. Maximum wall thickness was measured and the mean wall thickness calculated.Wall/outer wall ratio was used as a normalized wall index (NWI) adjusted for artery size difference among participants. Percent wall volume (PWV) was calculated as NWI ×100.Results In this asymptomatic cohort (mean age: 76 years), the mean (SD) aortic wall area andwall thicknesswere 222 ±45 mm2 and 2.7 ±0.4 mm, respectively. Maximum wall thickness was 3.4 ±0.6 mm, and PWV was 32% ±4%. Women appeared to have smaller wall area,but after correcting for their smaller artery size, had significantly higher PWV than men (P = 0.03). Older age was associatedwith larger wall area (P = 0.04 for trend) with similar PWVs. However, there were no statistically significant associations between standard risk factors,Framingham global risk, or metabolic syndrome status, therapy for cholesterol or hypertension, coronary or aortic calcium score, and the aortic wall burden. Aortic calcificationwas associated with coronary calcification. Conclusions Asymptomatic elderly in this cohort had a greater descending thoracic aortic wall volume that correlated with age, andwomen had a significantly increased PWV compared to men. In these survivors, the atherosclerotic aortic wall burden was not significantly associated with traditional risk factors or with coronary or aortic calcium scores or coronary calcium progression. Results suggest that age, or as yet unidentified risk factor(s), may be responsible for the increase in atherosclerosis.

关键词：磁共振成像动脉硬化动脉粥样硬化钙高血压基因男人幸存患者老年人人类

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Preparation and Commercial Application of ZHC-01 Hydrocracking Catalyst

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China Petroleum Processing & Petrochemical Technology 2007年第2期9卷 43-47页

作者： xu xuejun Liu dongxiang Wang Haitao Feng Xiaoping Wang Jifeng Fushun Research Institute of Petroleum and Petrochemicals Fushun 113001

ZHC-01 氢化裂解催化剂，由高加氢活动描绘了，为中间的精华的好选择，强壮的抵抗到氮毒害，被 co-gelling.The 催化剂准备不仅适合到单个阶段的氢化裂解过程，而且到连续氢化裂解过程的第一个阶段。与在 SINOPEC Qilu 石油化学的公司的... 详细信息

ZHC-01 氢化裂解催化剂，由高加氢活动描绘了，为中间的精华的好选择，强壮的抵抗到氮毒害，被 co-gelling.The 催化剂准备不仅适合到单个阶段的氢化裂解过程，而且到连续氢化裂解过程的第一个阶段。与在 SINOPEC Qilu 石油化学的公司的 1.4 Mt/a 氢化裂解单位的充分装载的操作同时， theZHC-01 催化剂的飞行员测试也在氢化裂解单位上被执行。测试结果显示这项活动，主要目标产品的收益和 ZHC-01 催化剂的质量能遵循设计要求因为氢化裂解单位，和这催化剂能在氢化裂解单位被使用。商业测试结果证明在生产的 ZHC-01 催化剂，展示好活动，稳定性，和灵活性，不是能仅仅为 producingenvironmentally 友好的中间的精华遇见需求，但是能也增加优化蒸气裂开的资源化工物品。

关键词：碳氢化合物分裂氢化裂解催化剂植物试验

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面向小样本学习的嵌入学习方法研究综述

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计算机工程与应用 2022年第3期58卷 34-49页

作者：黄彦乾迟冬祥徐玲玲上海电机学院电子信息学院上海201306

为了解决机器学习在样本量较少的情况下所面临的巨大挑战,研究人员提出了小样本学习的概念。在现有的小样本学习研究工作中,嵌入学习方法取得了不错的效果,引发了大量关注。根据训练特征嵌入函数时结合任务特征信息的方式,将嵌入学习方... 详细信息

为了解决机器学习在样本量较少的情况下所面临的巨大挑战,研究人员提出了小样本学习的概念。在现有的小样本学习研究工作中,嵌入学习方法取得了不错的效果,引发了大量关注。根据训练特征嵌入函数时结合任务特征信息的方式,将嵌入学习方法划分为单一嵌入模型和混合嵌入模型两大类。依据划分的类别,对现有的嵌入学习方法的研究工作展开进行研究。汇总了现有的小样本标准数据集,阐述了每一类嵌入学习方法的表现,分析了影响小样本学习性能的因素。讨论嵌入学习方法目前面临的挑战,并展望未来的研究方向。

关键词：机器学习小样本学习特征嵌入函数嵌入学习方法

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