Journals
  Publication Years
  Keywords
Search within results Open Search
Please wait a minute...
For Selected: Toggle Thumbnails
Effects of Refrigerate Incubation on Nitrogen Removal Performance and Microbial Community of Anammox
ZHANG Kuo, WANG Lina, FENG Yiming, ZHOU Jianhang, LI Xinjue, LIU Sitong
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (6): 1003-1010.   DOI: 10.13209/j.0479-8023.2023.091
Abstract （93）   HTML    PDF（pc） （12521KB）（27）       Save
The anaerobic ammonia oxidation (anammox) consortia were incubated at 5℃ to explore the nitrogen removal performance of the recovered anammox bacteria at 10–15℃. The results showed that after 92 days of low temperature incubation, the nitrogen removal rate of anammox bacteria reached 225±25 mg N/(L·d) at 12±1℃, which reached 68% of the nitrogen removal rate at 22±1℃. It was significantly higher than previous research results. 16S rRNA gene high-throughput sequencing was used to analyze the microbial composition in the reactor. Low temperature incubation had significant impact on the microbial community, especially for anammox bacteria. Candidatus_Kuenenia, as typical anammox bacteria, have a higher adaptability to low temperature than Candidatus_Brocadia and Candidatus_Jettenia, thus dominated the microbial community. The increased abundance and low-temperature metabolic capacity of Candidatus Kuenenia after low temperature incubation play an important 
role in improving the nitrogen removal performance of anammox reactor at 10–15℃.
Related Articles | Metrics | Comments（0）
Emission Characteristics of Intermediate-Volatility Organic Compounds in Petrochemical Industrial Area
ZHANG Feng, LU Sihua, LI Congyi, SHAO Min, LI Yue, LÜ Daqi, LI Xin, LIU Ying
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (2): 281-289.   DOI: 10.13209/j.0479-8023.2022.123
Abstract （261）   HTML    PDF（pc） （10164KB）（140）       Save
A typical petrochemical industrial area was selected as the research object, and particulate phase and gas phase samples of intermediate-volatility organic compounds (IVOCs) were collected in the air of the plant area in summer (July and August in 2021) to explore the pollution characteristics of IVOCs emission from petrochemical industrial sources and estimate their corresponding SOA (secondary organic aerosols) formation potential. The results show that, 1) the average concentration of IVOCs particle phase in typical petrochemical area is 4.22±1.54 μg/m3, and the average concentration of IVOCs gas phase is 108.87±78.93 μg/m3. The average concentration of IVOCs during the day is higher than that at night both in the gas phase and in the particle phase. 2) The n-alkanes in gas phase are concentrated from C12 to C22, while the n-alkanes in particle phase are concentrated from C22 to C35. The gas phase of polycyclic aromatic hydrocarbons is concentrated in naphthalene and phenanthrene, and the particle phase is concentrated in fluorene. 3) The IVOCs in the petrochemical industrial zone are quantitatively disassembled. The concentration is mainly concentrated in the interval B18–B21. The mass concentration sum of these four zones accounts for 60.41% of the total mass of IVOCs.
Related Articles | Metrics | Comments（0）
Exploration of Knowledge Driven Event Hyperbolic Embedding Temporal Relation Extraction Method
DUAN Jianyong, DAI Shiwei, WANG Hao, HE Li, LI Xin
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (1): 76-82.   DOI: 10.13209/j.0479-8023.2022.066
Abstract （236）   HTML    PDF（pc） （542KB）（90）       Save
Aiming at the problem of asymmetric temporal relations of events, the event representation is mapped to hyperbolic space to extract temporal relations of events. The word embedding representation of the event is constructed by using the pre-trained word vector and external knowledge through simple operation. Experimental results on publicly released datasets show that the F1 value of the model is generally 2% higher than that of the baseline model, which can improve the effect of event temporal relation extraction.
Related Articles | Metrics | Comments（0）
Effects of Different Light Qualities on the Growth of Thermophilic Cyanobacteria Synechococcus sp. PCC6715
LI Kai, GONG Yiwei, LI Xingkang, ZHANG Yanting, Maurycy Daroch, JIN Peng
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (4): 739-744.   DOI: 10.13209/j.0479-8023.2020.036
Abstract （1058）   HTML    PDF（pc） （864KB）（221）       Save
 In order to understand the lighting quality effects on the light-adaptive growth of cyanobacteria which does not express phycoerythrin, the thermophilic cyanobacteria PCC6715 in logarithmic growth phase was cultured by using white light (control), red light, and blue light with photosynthetically effective photon quantum density (PAR) of 100 μmol/(m2·s). Compared with the growth characteristics of PCC6715 under white light conditions, the changes in the measured and analyzed values of PCC6715 under other light qualities were as follows: the dry weight of PCC6715 significantly increased under blue light and significantly reduced under red light; the red and blue light have different effects on the start time and duration of the photosynthetic pigment synthesis of PCC6715; the maximum light energy conversion efficiency (Fv/Fm) of PCC6715 significantly increased under blue light and decreased significantly under red light; after 6 days of culture, the Fv/Fm of PCC6715 under red and blue light conditions tends to stable. In conclusion, the blue spectrum lighting promotes the growth of PCC6715, while red light inhibits the growth of PCC6715. At the same time, PCC6715 produces light-adaptive growth under both red and blue light, the reduction of phycocyanin content caused light-adaptive growth of PCC6715 in red light, and the light-adaptive growth of PCC6715 in blue light was due to the increase of phycocyanin content.
Related Articles | Metrics | Comments（0）
Recognition of Urban Polycentric Structure Based on Spatial Aggregation Characteristics of POI Elements: A Case of Zhengzhou City
LI Xin
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (4): 692-702.   DOI: 10.13209/j.0479-8023.2020.044
Abstract （2006）   HTML    PDF（pc） （2067KB）（287）       Save
In order to improve the recognition efficiency and accuracy of urban polycentric structure and provide scientific basis for urban planning, this paper uses kernel density analysis, hotspot analysis and weighted overlay analysis to explore the spatial aggregation patterns and characteristics of urban elements, and designs a spatial weighted overlay analysis method based on public dependence, spatial aggregation degree and attribute values. By using the POI data with high accuracy, fast update and full coverage, which can reflect the spatial aggregation characteristics of urban elements, the method realizes the measurement of aggregation characteristics and the polycentric recognition of Zhengzhou city. The results show that the POI elements in main urban area of Zhengzhou city present an annular spatial distribution structure. It has the characteristics of centralizing in the center and spreading along the road. The polycentric structure is unbalanced. There are some differences between the planned sub-centers and the identified ones. Because of the remote location and lack of supporting facilities, the peripheral functional centers with lower development level is far from achieving the dispersal and evacuation role they should have. Therefore, it is necessary to improve the overall planning of the industry to enhance the outward radiation and inward attraction of the sub-center through the link of transportation.
Related Articles | Metrics | Comments（0）
Distant Supervision for Relation Extraction with Gate Mechanism
LI Xingya, CHEN Yufeng, XU Jin’an, ZHANG Yujie
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (1): 39-44.   DOI: 10.13209/j.0479-8023.2019.101
Abstract （1141）   HTML    PDF（pc） （699KB）（164）       Save
A piecewise convolutional neural network with gating mechanism is proposed, which would automatically filter positive correlation features at word-level. Moreover, the idea of soft-label is introduced to the gating mechanism to weaken the impact of hard labels on noise filtering. Combined with sentence-level noise filtering, the overall performance of the model is improved. The experimental results on the public dataset show that the proposed model has a significant improvement compared to the sentence-level noise filtering methods. 
Related Articles | Metrics | Comments（0）
Efficient Traffic Flow Data Processing Method and Its Application Based on Spark Framework
LI Xin
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (6): 1227-1234.   DOI: 10.13209/j.0479-8023.2018.070
Abstract （780）   HTML    PDF（pc） （4776KB）（141）       Save

A traffic flow data processing and forecasting framework based on Spark is designed, and it can complete the efficient cleaning, statistics, storage and query of traffic flow data. A multi-order spatial weight matrix STARIMA model is used to predict the traffic flow, and it can verify the efficiency of data processing and the support for the prediction. By comparative experiments, the results show that the traffic flow data processing framework is efficient, and it is suitable for realizing complex data cleaning and mining algorithms and establishing data support for the prediction model. The traffic flow prediction model optimizes the multi-order spatial weight matrix, and it takes both efficiency and accuracy into consideration. The prediction results can provide reference for traffic guidance.

Related Articles | Metrics | Comments（0）
A Soil Moisture Co-retrieval Approach Based on AMSR-E and ASAR Data
LI Xin, ZENG Qiming, WANG Xinyi, HUANG Jianghui, JIAO Jian
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (5): 902-910.   DOI: 10.13209/j.0479-8023.2015.142
Abstract （1355）   HTML    PDF（pc） （2781KB）（1264）       Save

It is difficult to monitor land surface soil moisture in high temporal and spatial resolution within a wide range for lack of ground observation data when the satellite is passing over. To solve this problem, a new integrated approach termed as “soil moisture retrieval with combined active and passive microwave remote sensing observation” was proposed. AMSR-E soil moisture product is compensated as “high temporal resolution observation control data” and soil moisture benchmark is retrieved together with ASAR alternating polarization mode data. Then both of them are integrated to build up a co-inversion model for soil moisture retrieval. This approach applies to areas where the land surface roughness is small and vegetation index (NDVI) is low. The approach is evaluated in Weibei Upland of Shaanxi Province. According to the regression analysis based on AIEM (advanced integrated equation model), the correlation coefficient between compensated AMSR-E soil moisture and downscaled ASAR backscattering coefficient was approximately 0.81. Verification analysis with the in-situ data of Fengxiang County in the study area shows that the soil moisture retrieved with combined active and passive microwave remote sensing observation displays a correlation coefficient of 0.92, and the root mean square errors (RMSE) of the soil volumetric moisture is 0.025. It indicates that the approach is credible and the soil moisture retrieval results could be used in simulating regional crop growth under water-limited environments.

Related Articles | Metrics | Comments（0）
Influence of Air on the Performance of InAs Nanowire FET
ZHANG Xintong;LI Xing;WANG Xiaoye;FU Mengqi;YANG Tao;CHEN Qing
   2015, 51 (4): 585-590.   DOI: 10.13209/j.0479-8023.2015.013
Abstract （978）      PDF（pc） （3920KB）（446）       Save
Planar field effect transistor nanodevices were fabricated based on individual InAs nanowires. The electrical performance of the devices was measured and studied in vacuum, air, N2, O2, H2O and pollutant in air, NO2. Compared with the performance in vacuum, the performance of the device in air changes, e.g. the threshold voltage of the device (VT) shifts to positive direction, the off-state current (Ioff) increases and the on-off ratio (Ion/Ioff) decreases in air. The main air component, N2, does not have distinguishable impact on the performance of the device. The effect of O2 is very weak. H2O increases Ioff, decreases Ion/Ioff and shifts VT negatively. The component of the pollutant in air, NO2 is found to bring a positive shift of VT, and an unchanged Ion/Ioff.
Reference | Related Articles | Metrics | Comments（0）
Influence of a Weakened Atlantic Thermohaline Circulation on Tropical Pacific Climate Mean State and ENSO Variability
LI Xinrong,YANG Haijun,WANG Yuxing
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （1229）      PDF（pc） （2297KB）（698）       Save
The responses of the global mean climate and the ENSO to a substantial weakening of the Atlantic Meridional Overturning Circulation (AMOC) are studied using water-hosing experiment in a coupled ocean-atmosphere general circulation model. With 1 Sv freshwater input in the North Atlantic, the AMOC slows down rapidly and weakens by almost 90%, reducing the northward oceanic heat transport, leading to a sea surface temperature (SST) dipole in the Atlantic. Through atmospheric teleconnections and local air-sea interaction, warm SST anomalies are found over the tropical Pacific. However, neither zonal SST gradient nor zonal wind stress changes significantly. The depth and slope of thermocline in tropical Pacific do not change too much, either. Accordingly, the variability of ENSO activity is essentially unchanged. These results indicate that in this model, fresh water perturbation may influence global mean climate, but has little impact on ENSO.
Related Articles | Metrics | Comments（0）
Verifiable Multi-secret Sharing Scheme Based on Homogeneous Linear Recursion
CHEN Yangkui,YU Jia,CHENG Xiangguo,HAO Rong,LIU Hongyan,LI Xin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （619）            Save
A new multi-secret sharing scheme based on homogeneous linear recursion is proposed, and then it is converted into a verifiable scheme. In the distribution phase, very few of public values are needed to publish. In the recovery phase, each participant only needs to submit a pseudo shadow instead of his secret shadow, and his secret shadow cannot be disclosed. When secrets are changed, secret shadows don?t need to be redistributed, which makes secret shadow able to be used multiple times. The proposed scheme has many advantages, for example, the secret shares can be used multiple times and the scheme publishes very few parameters as well as the reconstructed polynomial has a low degree. This makes the proposed scheme more efficient. Therefore, it better satisfies demands of various applications.
Related Articles | Metrics | Comments（0）
Joint Layered and Multiple Description Image Coding Based on Directional Wavelet Transform
LI Xin,ZHANG Feizhou
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （495）            Save
With the goal of achieving both robustness to unreliable channels and adaptivity to client bandwidth heterogeneity and network congestion, the authors explore constructions for layered multiple description codes, where base layer descriptions can be transmitted to low bandwidth clients, while both base and enhancement layer descriptions can be transmitted to high bandwidth clients The multiple description coding is used to resolve the problem of transmission over unreliable channel Directional wavelet transform is selected to remove redundancy among neighboring pixels in order to high coding efficiency Through comparisons with other traditional multiple description the new architecture can obtain better quality of image in unreliable network channels
Related Articles | Metrics | Comments（0）
A Sheetflood Dominated Alluvial Fan---FengYG Alluvilal Fan，Taiyuan Basin
LI Xinpo,MO Duowen,ZHU Zhongli,MA Yuanxu,LIU Yunming
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （900）            Save
FengYG alluvial fan is a large fan that lies to the northwest of Taiyuan basin. It has a widen plan view. Exposures with typical parallel bedding sediments were found at fanhead. It shows that FengYG alluvial fan is mainly formed by upper flow regime sheetflood process. Sheetflood deposits comprise pebble to granule gravel bar deposits with small thickness that extend far on side directions, and between bar deposits with finer grain size. Geomorphic and geologic features of its drainage basin shows that larger accommodation space formed by uplift of Lüliang mountain possibly led to sheetflood deposits on FengYG alluvial fan.
Related Articles | Metrics | Comments（0）
Effect of Nanometer-Sized B Powder on Phase Formation of Polycrystalline MgB2
AN Ling,CHENG Chinping,WANG Bo,ZHUANG Chenggang,LI Xingguo,ZHOU Zengjun,FENG Qingrong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （641）            Save
The size effect of the raw B powder on the MgB2 phase formation is studied by the technique of in-situ high temperature resistivity (HT-ρT) measurement. The onset temperature, Tonset, and the completion temperature, TPF, of the phase formation are determined directly during the ongoing thermal process. These two temperatures, Tonset and TPF of the sample synthesized using nanometer B and Mg powders (NanoB-MgB2) are 440 and 490℃, respectively, the same as those of the sample using micrometer B and nanometer Mg powders (MicroB-MgB2). This indicates that the phase formation temperature of MgB2 do not depend on the B powder size. The upper limit of the sintering temperature, TN, above which the sample loses superconductivity, is below 750℃ for NanoB-MgB2, much lower than 980℃ for the MgB2 prepared using micron-sized B powder and millimeter sized Mg powder (DM-MgB2). In comparison with the sample directly sintered at 650℃<TN, an interesting, irreversible transformation in the crystal structure of the MgB2 phase is observed with the sample going through the stages of initial sintering at 750℃, then re-sintering at 650℃ in an Mg-rich environment after the processes of regrinding and pressing.
Related Articles | Metrics | Comments（0）
Robust Lagrange Stabilization of Uncertain Pendulum-Like Systems Based on Nonlocal Reduction Method
LI Xinbin,ZHONG Jiaqing
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （591）            Save
The robust Lagrange stabilization problem is considered as a class of uncertain nonlinear systems with infinite equilibria set,called pendulum-like systems. Firstly,sufficient conditions of Lagrange stability for nominal unperturbed pendulum-like systems are derived based on the nonlocal reduction method. Then the static state feedback controller design methods are presented for uncetain pendulum-like systems with time-varying norm-bounded parameter uncertainty to obtain robust Lagrange stability. It is shown that the above problem can be reduced to the existence of the solutions to a set of LMIs.
Related Articles | Metrics | Comments（0）
Genesis of Reticulate Clay in the Laterite of the Dongting Basin
LAI Hongzhou,MO Duowen,LI Xinpo
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （754）            Save
The authors studied the characteristics of element geochemistry, mineral assemblage and microtexture of the white reticulate clay in the Quaternary laterite of the Dongting Basin with some experimental analysis methods, such as chemical analysis, X-ray diffraction analysis, IR and SEM analysis. The genesis of the vermiculate reticulate clay and the rhizomatic reticulate clay in the Quaternary laterite of the Dongting Basin are discussed. The formation of crannies or holes in the soil and the transference of soil elements are absolutely necessary conditions to form the white reticulate clay in laterite. The formation of crannies of the vermiculate reticulate clay results from the stratigraphical pressure and the seasonal fluctuating of the groundwater level. The formation of holes of the rhizomatic reticulate clay results from the decomposition of the botanic roots. The intense eluviation and weathering of soil with groundwater and run-off result in the enhancing of capacity of transference of some elements, such as Si, Al, Fe, Mn. The chemical reactions of the colloid particles in the soil water make those crannies or holes filled by some epigenetic clay minerals and quartz. Then a great deal of white reticulate clay comes into being in the Quaternary laterite of the Dongting Basin.
Related Articles | Metrics | Comments（0）
Study of the Anti-Chemical Terrorism on Numerical Simulation
HUANG Shunxiang,HU Fei,LI Xin,CHEN Haiping,QIAN Yixin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （620）            Save
Aiming at terrorists attack chemical plants or chemical establishments, the model, based on the 3-D atmospheric diffusion on complex terrain, is completed. The model can be used to simulate the wind fields, concentration fields, dose fields, and make certain the danger areas and make the harm evaluation. The model can provide necessary scientific data for working-out counterplan, emergence response and emergence rescue. The model can be applied to the analogous chemical affairs in character for emergence response and emergence rescue as well as to the risk evaluation in disposed ACW (Abandoned Chemical Weapons) in performing CWC (Chemical Weapons Convention).
Related Articles | Metrics | Comments（0）
Study on A Nitrogen-Fixing Pantoea Agglomeras Isolated from the Root of Sugar Cane
LI Xinghong,LI Dachei,LI Wei,PENG Lie
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （634）            Save
A strain of nitrogen-fixing bacteria, W11, isolated from the root of sugar cane has been identificated as Pantoea agglomeras using an auto-identificat ion system for bacterium based on 96 biochemical test data. W11 has the properties of tolerance to acid(pH3.5) and high sucrose concentration (30%), A amount of acid was formed and reduced the acidity of medium to pH of 4.41, the nitrogenase activity was inhibited in presence of 3.1mmol NH4NO3 or 58.5mmol NaNO3. The optimum growth and maximum nitrogenase activity of W11 occurs at the medium containing 10% sucrose and 0.25g/L sodium glutamate, pH5.5, 28-30oC. Its behaviours of tolerance to acid and high sucrose concentration, acid production and the use of carbon substrates is simiiar to that the Acetobacter diazotrophicus has. The strain W11 was inferred to have a nitrogen-fixing relationship associated with the root of sugar cane.
Related Articles | Metrics | Comments（0）
Optimization Calculation of the Roof Thickness for 15MeV X-Ray Linear Accelerator
LI Xinghong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （905）            Save
Presents a methods for calculation of the thickness of a concrete roof for shielding the angularity distributed X-ray radiation produced by a L-6000HRO 15MeV X-ray Linear Accelerator. The required roof thickness was found to be 31cm in order to ensure the dose equivalent rate to be 0.0025mSv. h-1 at an observation point 20 m away from the machine. This radiation comes mainly from skyshine. The thickness of that concrete roof was further optimized and found to be 50 cm. The dosimetric measurements made after the accelerator building had constructed showed that the shielding design was safe and econonic, and the skyshine radiation had been decreased to a level as low as reasonably achievable.
Related Articles | Metrics | Comments（0）
Mineralization Time, Space, Geodynamic Background and Metallogenic Model of the Skarn Gold Deposits, China
CHEN Yanjing,QIN Shan,LI Xin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （1129）            Save
Skarn type is one of the major types of the gold deposits of China, with at least 14 large and 28 medium deposits discovered. The total skarn type reservoir is more than 700 tons which accounting for more than 15% in the total gold reservoir of China. The mineralizing time of skarn gold deposits is mainly of late Mesozoic (Yanshanian), contemporaneous with the collision orogenesis occurred in the mainland of China; the gold orebodies emplaced in the late stage of the collision orogenesis. Almost all the skarn gold deposits distributed in the collision orogenic belts, fault-magmatic belts and marginal mobile belts, especially in the Lower Yangtze River district. Their metallogenic geodynamic background was the compression-extension transition stage of collision orogenesis. The geological and the geochemical characteristics of the skarn gold deposits and their related igneous intrusions are exclusively coincident with the metallogenic model for collision orogensis or for A-type subduction. It shows that the metallogenic model for collision orogenesis is the oreforming models for the most of the skarn gold deposits, China.
Related Articles | Metrics | Comments（0）
Determination of Nitrogenase Activity of Induced Cucumber Nodules by 15N Trace Method
LI Xinghong,TIAN Dexiang,YU Zhongju,WANG Yongmin,CHEN Deyuan
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （806）            Save
Reports the determination results of nitrogenase activity of induced cucumber root nudules by 15N trace method. The root systems bearing induced nodules of cucumber were exposed to a gas mixture containing 15N2 for 48h and partial root systems soaked in free-nitrgen culture solution simultaneusly. After exposure the 15N content in the modulated root systems of cucumber is 0.431 Atom % 15N by mass spectrometric analysis, whereas in the contrast samples without exposure to 15N is 0.369 Atom % 15N. The statiatical t test for the results of 15N trace experiments is: t=3.15 > t0.01=2.819, It has been demonstrated that the nitrogenase activity in cucumber nudules is at a remarkable level of 99.9%. The nitrogenase activity in detached nodules of cucumber was also determined by conventional acetylene reduction method. In both methods clear evidences of nitrogenase activity were obtained for the induced nodules of cucumber.
Related Articles | Metrics | Comments（0）
Determination of Volatile Benzenes in Water by Twice Phase Equilibration/GC
WANG Yonghua,TAO Shu,ZHANG Junhua,LI Xinyun,SHI Jie,WANG Xincheng,ZHAO Qiuhua,SHI Tingxiu
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （670）            Save
The article presents the method of determination of volatile benzenes in water with twice phase equilibration/Headspace GC.Analysis of only gas phase after two succesive phase equilibrations gives concentration of volatile benzenes in water and their Henry law constants. The relative standard deviation of the method is better than 20% for seven volatile benzenes. The limit of detection is the range of 2～3 μg/L. The recovery of the method is quantitative.
Related Articles | Metrics | Comments（0）
Recognition of Urban Polycentric Structure Based on Spatial Aggregation Characteristics of POI Elements: A Case of Zhengzhou City
LI Xin
Acta Scientiarum Naturalium Universitatis Pekinensis    0, (): 692-702.   DOI: 10.13209/j.0479-8023.2020.044
Abstract （496）   HTML          Save
In order to improve the recognition efficiency and accuracy of urban polycentric structure and provide scientific basis for urban planning, this paper uses kernel density analysis, hotspot analysis and weighted overlay analysis to explore the spatial aggregation patterns and characteristics of urban elements, and designs a spatial weighted overlay analysis method based on public dependence, spatial aggregation degree and attribute values. By using the POI data with high accuracy, fast update and full coverage, which can reflect the spatial aggregation characteristics of urban elements, the method realizes the measurement of aggregation characteristics and the polycentric recognition of Zhengzhou city. The results show that the POI elements in main urban area of Zhengzhou city present an annular spatial distribution structure. It has the characteristics of centralizing in the center and spreading along the road. The polycentric structure is unbalanced. There are some differences between the planned sub-centers and the identified ones. Because of the remote location and lack of supporting facilities, the peripheral functional centers with lower development level is far from achieving the dispersal and evacuation role they should have. Therefore, it is necessary to improve the overall planning of the industry to enhance the outward radiation and inward attraction of the sub-center through the link of transportation.
Related Articles | Metrics | Comments（0）
Recognition of Urban Polycentric Structure Based on Spatial Aggregation Characteristics of POI Elements: A Case of Zhengzhou City
LI Xin
Acta Scientiarum Naturalium Universitatis Pekinensis    0, (): 692-702.   DOI: 10.13209/j.0479-8023.2020.044
Abstract （0）            Save
In order to improve the recognition efficiency and accuracy of urban polycentric structure and provide scientific basis for urban planning, this paper uses kernel density analysis, hotspot analysis and weighted overlay analysis to explore the spatial aggregation patterns and characteristics of urban elements, and designs a spatial weighted overlay analysis method based on public dependence, spatial aggregation degree and attribute values. By using the POI data with high accuracy, fast update and full coverage, which can reflect the spatial aggregation characteristics of urban elements, the method realizes the measurement of aggregation characteristics and the polycentric recognition of Zhengzhou city. The results show that the POI elements in main urban area of Zhengzhou city present an annular spatial distribution structure. It has the characteristics of centralizing in the center and spreading along the road. The polycentric structure is unbalanced. There are some differences between the planned sub-centers and the identified ones. Because of the remote location and lack of supporting facilities, the peripheral functional centers with lower development level is far from achieving the dispersal and evacuation role they should have. Therefore, it is necessary to improve the overall planning of the industry to enhance the outward radiation and inward attraction of the sub-center through the link of transportation.
Related Articles | Metrics | Comments（0）
Copyright © Acta Scientiarum Naturalium Universitatis Pekinensis, All Rights Reserved.
Powered by Beijing Magtech Co., Ltd.