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A PM2.5 Interpolation Method Based on Neural Network for Optimum City Matching
ZHOU Pei, YANG Fan, WEI Jun
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (5): 793-800.   DOI: 10.13209/j.0479-8023.2023.051
Abstract149)   HTML    PDF(pc) (761KB)(78)       Save
In order to solve the problem that some cities have serious PM2.5 concentration data deficiency and can not get prediction model by training their own data, this paper proposes a method to use prediction model of similar cities to fill in historical data of target city. Based on the meteorological data, urban development data and PM2.5 concentration data of 23 cities, an interpolation model of PM2.5 daily concentration data is established based on self-organizing map (SOM) and gated recurrent unit (GRU) neural network and use it and raditional interpolation (linear interpolation and quadratic interpolation) methods are used to fill missing data respectively. The comparision of filling effects show that the SOM city matching model can accurately match the similar cities of the target city. For the missing data less than 5 days, the filling effect of traditional interpolation methods are better than that of GRU interpolation model. For the missing data more than 5 days, the GRU interpolation model is more competent to fill in the missing data for a long time.
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Offshore Comparative Test for HF Ground Wave Radar Based on Integrated Monopole Cross Loop Transceiver Antenna
XU Xinjun, LU Tianyi, YANG Fan, SHI Xinzhi, WEI Jun
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (4): 593-601.   DOI: 10.13209/j.0479-8023.2023.021
Abstract222)   HTML    PDF(pc) (5910KB)(78)       Save
To verify the feasibility of an antenna system with integrated transmitting and receiving antennas for use on OSMAR-S high frequency radar, an experiment of radar observation with time series of sea currents observed by Acoustic Doppler Current Profiler (ADCP) in situ was conducted within the Pearl River Estuary from November 25 to December 1, 2021. The experimental results show that the radar and ADCP observations are in high agreement, with correlation coefficients as high as 0.916. The magnitudes and changes with time of the amplitudes of the main sub-tides (M2 and K1) obtained by the reconciliation analysis and other methods are in high agreement. The experiment indicates that the transceiver antenna system, on the basis of its advantages of small footprint, low cost and convenience to set up on the seashore, still has high accuracy for in situ current observations.
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Current Development Status and Countermeasures of Mangrove Protection and Restoration Standards
LI Ruili, YANG Fang, WANG Hui, WANG Wenqing
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (5): 916-928.   DOI: 10.13209/j.0479-8023.2022.079
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In the past 20 years, mangroves have been strictly protected in China, and the area has been gradually restored through artificial afforestation. The authors reviewed the status of mangrove protection and restoration in China, summarized the problems of the present mangrove standards and proposed the existing problems, and put forward the countermeasures. The corresponding suggestions and countermeasures are as follows. 1) Develop a comprehensive technical standard plan for mangrove protection and ecological restoration in combination with the national carbon neutral strategy and mangrove protection and restoration planning goals, and speed up the introduction of national mangrove standards. 2) While compiling relevant standards for mangrove protection and restoration, attention should be paid to increase mangroves’ carbon sequestration capacity and carbon sinks. 3) Formulate standards for returning ponds to forests to fill the gaps in China. 4) Fully implement the ecological restoration principle of ‘natural restoration as the primary and artificial restoration as supplement’, and attach importance to strengthen the formulation of technical details of mangrove protection and restoration standards. 5) Mangrove professional research institutions and experts should deeply participate in the formulation and implementation of standards to improve the survival rate of afforestation.
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Characteristics of Surface Currents in Guangdong-Hong Kong-Macao Greater Bay Area in Spring Based on High Frequency Radar Observations
REN Lei, YANG Fan, YANG Lingna, CHEN Xiaofan, PAN Guangwei, WEI Jun
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (5): 839-849.   DOI: 10.13209/j.0479-8023.2022.055
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Based on the sea surface currents data of Guangdong-Hong Kong-Macao Greater Bay Area (GBA) in March 2020 obtained from high frequency radar (HFR), the surface currents data from 907 densely distributed points were selected to analyze the characteristics of spatial-temporal variation. Harmonic analysis and some other methods were used to explore the characteristics of tidal currents. The results show that the irregular semidiurnal tide M2 is dominant in the sea area, and the shallow-water effect is significant. The dip angles of the main diurnal and semidiurnal tides are between 120° to 160°. The direction of maximum flow rate is WN-ES, which shows the trend of shore offshore flow. As the distance to the shoreline increases, the tidal current pattern coefficient and the effect of shallow water constituents coefficient gradually increase, and the offshore area in the south of the research area shows the characteristics of irregular diurnal tide. The ranges of probable maximum current velocity and measured maximum current velocity were 0.33 cm/s to 71.01 cm/s and 58.63 cm/s to 149.99 cm/s, respectively, with the upper-end values distributed in the northwest and south of the study area.
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New Discovery of Macroscopic Algae Fossils from Shibantan Bituminous Limestone of Dengying Formation in the Yangtze Gorges Area, South China
YANG Fan, QIN Shujian, DING Weiming, XU Yihe, SHEN Bing
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (3): 563-572.   DOI: 10.13209/j.0479-8023.2017.093
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The macroscopic algae fossils from Shibantan bituminous limestone of Dengying Formation in the Xiadong area, Hubei province were studied. There are one genus and three species (including two new species) and one new macroscopic algae fossils with monopodial branching character (genus and species are unidentified) from the Sixi section. Monopodial-branching type fossil represents the first macro-algae fossil with the monopodial branching discovered in the terminal Ediacaran Dengying and equivalent formations in South China. Vendotaenia sixiense new species and Vendotaenia pavimentpes new species are the algae fossils with branching and holdfast, respectively. The new discovery suggests that the morphology of macroscopic algae fossils might be more complex than previous think, and has the great significance to the evolution research of the early multicellular macroalgae.

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Industrial Organization, Industrial Agglomeration and Chinese Manufacturing Pollution
YANG Fan, ZHOU Yi, HE Canfei
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (3): 563-573.   DOI: 10.13209/j.0479-8023.2016.058
Abstract1017)   HTML    PDF(pc) (1305KB)(1032)       Save

This paper focuses on the influence external economies of scale brought by industrial agglomeration and internal economies of scale brought by industrial organization have on pollution emission intensity. This research takes SO2, soot, polluted water as the examples and two digits manufacturing industrial divisions as the research subjects. Through spatial distribution analysis and penal data econometric analysis during the time from 2005 to 2009, the authors find that the relationship between gini and pollution intensity is positive, state owned and group owned enterprises ratios are negative related to pollution intensity of SO2 and soot, while private and foreign investment enterprises ratios are positive related to pollution intensity. The result shows that industrial pollution is influenced by the trend of marketization, which suggests that the authority may improve the environmental regulations systems and the supervision power, and local government should improve the pollution dissolving facilities’ effectiveness and pollution control efforts within industrial clusters.

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