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Spatial Simulation of Agricultural Land Use Change Based on Agent-Based Model: A Case Study of Tongdu Town, Dongchuan District in Kunming City
YANG Weishi, DAI Erfu, WU Jiansheng, ZHANG Hui, XING Zhaoting, FAN Fan, WANG Hongliang, GUAN Yufeng, CHEN Feng, CHEN Minglei
Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (5): 976-986.   DOI: 10.13209/j.0479-8023.2025.073
Abstract （512）   HTML    PDF（pc） （5000KB）（922）       Save
This study focuses on Tongdu Town in Dongchuan District, Kunming City, and constructs a model for agricultural land use change based on human-environment interactions using an agent-based model. By utilizing census data, geographical environmental data, and field survey data, the study simulates the spatially distinct processes of agricultural labor, annual income of farming households, and agricultural land use changes in Tongdu Town from 2010 to 2015. The result shows that changes in agricultural land use are strongly correlated with labor, household income, and slope, but less so with soil fertility. Approximately 63.35% of agricultural land use changes occurred among low-income farming households, particularly the conversion of farmland to grassland — 87.60% of this specific conversion took place in low-income households. The transition from farmland to forest predominantly occurred in areas with relatively higher population densities and steeper slopes. The simulation model demonstrated excellent performance, with a spatial accuracy of 92.23%. The method developed for simulating agricultural land use changes in this study can offer valuable references for other regions, and thus provide scientific support for the implementation of ecological conservation, rural revitalization, and other related projects in China.
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Study on Media Attenuation, Site Response and Source Parameters in Yunnan Area
YANG Zhousheng, YANG Jingqiong, ZHANG Huiyuan, QIN Min, XU Yaji
Acta Scientiarum Naturalium Universitatis Pekinensis    2024, 60 (4): 615-625.   DOI: 10.13209/j.0479-8023.2024.055
Abstract （1453）   HTML    PDF（pc） （9573KB）（332）       Save
Based on the seismic waveform records of the Yunnan regional seismic network from 2012 to 2023, the joint inversion method was used to obtain the media attenuation Q value, the site response of 67 stations, and the source parameters of 2819 earthquakes above ML 2.0 in the study area. The results show that in Yunnan region, based on the geometric attenuation model of three seismic waves, the non elastic attenuation model accurately reflects the complex structure and strong seismic activity characteristics of the region. Among the 67 stations in the study area, the overall site response does not show much amplification effect, but there is obvious high-frequency attenuation phenomenon, and the amplification factor of the site in the excellent frequency band 1–6 Hz is mostly 1–4 times, while the attenuation of the site in the high band (above 10 Hz) is mostly between 0 to 95%. Among them, the site response value of 12 stations fluctuates around 1; the site response of the four stations is close to 1 at low frequency, and is amplified at high frequency. The overall response calculation result of the five stations is slightly less than 1. 46 stations show a slight amplification at low frequency and attenuation at high frequency. Through the correlation analysis of the parameters of each seismic source, it is found that the local magnitude is positively correlated with moment magnitude, seismic moment, stress drop, apparent stress and radiant energy, and negatively correlated with corner frequency. In general, the aftershock areas of Yangbi, Yingjiang and Mangshi earthquakes in western Yunnan and the southern section of the Honghe fault in southern Yunnan have relatively high levels of stress relief from small and medium-sized earthquakes, while the areas along the Jinshajiang-Honghe fault zone, especially along the southern section of the Honghe fault zone in southern Yunnan, are concentrated areas of high stress and seismic drops, indicating that the faults here may be subjected to relatively strong tectonic shear stress.
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Using Mobile Phone Data to Estimate the Temporal-Spatial Distribution and Socioeconomic Attributes of Population in Megacities: A Case Study of Beijing
HAI Xiaodong, LIU Yunshu, ZHAO Pengjun, ZHANG Hui
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (3): 518-530.   DOI: 10.13209/j.0479-8023.2020.035
Abstract （4151）   HTML    PDF（pc） （3739KB）（3280）       Save
This study proposes a technique to identify the temporal-spatial distribution and socioeconomic attributes of population by using mobile phone data. This technique has a fine geographic scale, which is called as Spatial Pattern Unit. The study uses Beijing as a case and conducts an empirical application of the technique. Firstly, it investigates the temporal-spatial distribution of population in Beijing by using multiple data sources, including mobile phone data, travel survey data and heat map data. Secondly, it classifies the spatial pattern unit into different categories in terms of socioeconomic attributes of population and travel behavior features. Thirdly, it applies machine learning approach to estimate socioeconomic attributes of population for all spatial pattern units. Finally, it compares and verifies the results of analysis. The approaches and findings would be valuable to monitoring population distribution, locating business services and planning urban infrastructure.
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Cross Site Script Prevention Based on Delimiters
ZHANG Huilin, LI Guancheng, DING Yu, DUAN Lei, HAN Xinhui, XIAO Jianguo
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (2): 320-330.   DOI: 10.13209/j.0479-8023.2017.172
Abstract （2331）   HTML （82）    PDF（pc） （529KB）（973）       Save

The authors propose a practical and accurate cross site script prevention method based on delimiters for UTF-8 encoded web applications. Only trusted delimiters are tainted into corresponding UTF-8 shadow bytes, and these tainted shadow bytes are automatically propagated in web applications and can be directly delivered into output pages. Cross site script is prevented by analyzing the tainted delimiters and HTML context of output pages. A prototype called XSSCleaner is implemented on PHP. The evaluation shows that XSSCleaner can accurately protect web applications from real world cross site script attacks with an average overhead 12.9%.

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Petrogenesis of the Early Cretaceous Qingcaoshan Strongly Peraluminous S-Type Granitic Pluton, Southern Qiangtang, Northern Tibet: Constraints from Whole-Rock Geochemistry and Zircon U-Pb Geochronology
LIU Hong, ZHANG Hui, LI Guangming, HUANG Hanxiao, XIAO Wanfeng, YOU Qin, MA Dongfang, ZHANG Hai, ZHANG Hong
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (5): 848-860.   DOI: 10.13209/j.0479-8023.2016.045
Abstract （2733）   HTML    PDF（pc） （2447KB）（1484）       Save

The Qingcaoshan granitic pluton, located in the Zhapu-Duobuza magmatic arc in southern Qiangtang, consists of granite porphyry and quartz monzonitic porphyry. However, the age and genesis are not studied due to absence of geochemical and geochronological data. The weighted average 206Pb/238U age of 122±1 Ma (MSWD=3.9) for quartz monzonitic porphyry and 114.6±1.2 Ma (MSWD=1.1) for granite porphyry is present by LA-ICPMS and SHRIMP zircon U-Pb dating. The intrusion have minor muscovite and cordierite, no hornblende. The granitic pluton is characterized by enriched Al (A12O3: 14.81%-15.86%), depleted Ca (CaO: 1.10%-2.44%), and high content of alkali (K2O+Na2O: 6.86%-8.80%). Father more, it is also characterized by ASI of 1.1 (A/CNK: 1.06-1.20), corundum (1.20%-2.86%) and absence of diopside showed through CIPW calculation, which are indicative of peraluminous sub-alkaline S-type graniten. The intrusive rock is relatively enriched in large ion lithophile elements (Rb, Th, U, K, La, Ce) and depleted in high field strength elements (Ta, Nb, P, Ti, Y), and exhibits LREE-enriched ((La/Yb)N: 3.24-16.20) with right-inclined REE distribution patterns. A synthesis of all these characteristics indicates that the Qingcaoshan granitic pluton was probably derived from partial melting of greywacke components in the upper crust as a result of norward subduction of the Bangong Co-Nujiang oceanic crust towards the Qiangtang block.

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Numerical Simulation Analysis for Low Temperature Plasma Ignition of Propane/Air
MU Yuntao;ZHENG Dianfeng;WANG Yuqing;LI Lihan;ZHANG Huiqiang
   2015, 51 (5): 791-798.   DOI: 10.13209/j.0479-8023.2015.083
Abstract （2264）      PDF（pc） （3148KB）（2206）       Save
In order to study the initiate mechanism of pulse detonation engine ignited by low temperature plasma through numerical simulation method, the low temperature plasma ignition discharge area was simplified into heat kernel with high temperature and high pressure considering the propane/air chemical reaction kinetics mechanism. The laminar finite-rate model in the FLUENT was used to simulate the combustion process from deflagration to detonation transition (DDT) initiated by low temperature plasma, and the process was analyzed minutely. The experimental results show that it is feasible to simplify the low temperature plasma ignition to the fire kernel of a certain pressure and temperature in numerical simulation under a reasonable boundary condition that the pressure is atmospheric pressure and the wall temperature is normal temperature. The ignition delay and measurement error results in that the detonation wave development time of the numerical simulation is shorter than that of experimental result. The measurement value of the experiment is close to the result in numerical simulation under the condition of normal pressure heat kernel and normal temperature wall.
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Self-Other Decision-Making Differences Derived from Construal Level
ZHANG Hui,LU Jingyi,XIE Xiaofei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （1190）      PDF（pc） （438KB）（542）       Save
The authors review the self-other decision-making differences, and propose that such differences are derived from decision makers’ cognitive differences in construal level. The mental construals are low when people make decisions for themselves, whereas the mental construals are high when they decide for others. Theoretically, self-other decision-making differences are illustrations of bounded rationality. Practically, understanding such differences as well as their mechanisms helps to achieve optimal decisions.
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Stable Carbon Isotopic Composition and Source of Nonmethane Hydrocarbons in Urban Air, Lanzhou
REN Zhaofang,PENG Lin,ZHANG Jianqiang,ZHANG Huimin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （1174）            Save
Isotopic composition of nonmethane hydrocarbons, sampled by Tenax TA adsorption tube and detected by thermal desorption-gas chromatography-isotope ratio mass chromatography was analyzed in the main functional area, Lanzhou. The results show that the average δ13C values of transportation related sources is - 28. 7‰, significantly below the value of coal-combustion exhaust( - 24. 1‰) . In summer the average δ13C values of atmospheric NMHCs are close to each other( from - 29. 5‰ to - 27.4‰), while in winter the average δC values in Xigu industrial estate(-25.5‰) is larger than that in Panxuanlu(-28.8‰) and Erdianchang(- 31.2‰). The results of source analysis indicate that the atmospheric NMHCs in Panxuanlu are mainly emitted by transportation related sources both in summer and winter; the atmospheric NMHCs in Xigu industrial estate in winter are mainly influenced by coal-combustion exhaust, while in summer n-alkanes and benzene are mainly from transportation related sources; in winter atmosphere in Erdianchang pentane, hexane and benzene are from transportation related sources; in summer atmosphere in residential area the NMHCs are mainly influenced by transportation related sources and some unknown sources; benzene is mainly emitted by transportation related sources and was detected in every sampling site both in winter and summer. To reduce the pollution of NMHCs, it is important to control transportation related sources.
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Bypass Demonstration Work of the Step-Feeding Biological Contact Oxidation Process for River Water Purification
ZHANG Hui ,WEN Donghui ,LI Lu ,XIE Shuguang
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （1194）            Save
The Daqing River is the most seriously polluted river in the Dianchi Lake watershed. A bypass demonstration work of step-feeding biological contact oxidation process ( SBCOP), with the treatment scale of 1000 m3day and the hydraulic retention time (HRT) of 4.75 hours, was built aroundthe river bank to purify the river water. During the winter dry seasonfrom Nov. 2007 to Mar. 2008, three sets of parameters of the demonstration work were operated by regulating step-feeding ratio and air-water rate according to the influent qualities and climatic conditions. The results show that the SBCOP demonstration work kept good removal efficiencies for COD and NH+4 - N, and the averager emoval rates were 37.3% and 32.9% each. The step-feeding ratio of 1∶1∶1 was beneficial for removing COD and NH+4 - N. The removal rate of NH+4 - N decreased when the concentration of NH+4 - N increased. The average removal rate of TN was as lowas 10.5%, owing to the negative impacts of low temperature, carbon source shortage, high DO level of the influent, and loose and porous bio film. Theremoval of TP depended on the deposition of sludge and adsorption of Spirogyra sp., and the average removal rate of TP was 13.7%. To avoid the minus removal rate of TP, sludge discharge and removing of dead Spirogyra sp. were needed. The air-water rate of 2 ∶1 was suitable when influent was Dianchi Lake water.
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Quantum Local Theory of Two-Photon Interference by a Nonlocal Double Slits
WANG Ruopeng,ZHANG Huirong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （1047）            Save
The authors shows a quantum local theory that can explain the interference experiment which is designed based on the nonlocal double slits experiment. The theoretical results are consistent with the experimental data perfectly.
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Brain Imaging Studies of Semantic Representations in Bilinguals
ZHANG Huijuan,LI Lianjing,ZHOU Xiaolin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract （1099）            Save
The authors review current brain imaging (fMRI and PET) studies of semantic representations in bilinguals and point out that the three issues have taken central ground in these studies: (1) whether semantic representations of different languages have identical neural mechanisms? (2) What effects do the proficiency in languages and the age of second language acquisition have on semantic representation in the brain? (3) Which brain areas are responsible for the switching and translation between languages? And whether these areas are devoted exclusively to language switching and/or translation?
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