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Dynamic Evolution Characteristics of Fractional Vegetation Cover and Its Response to Climate Change in the Lower Reaches of the Heihe River
PEI Xiaolong, MAO Lei, ZHANG Jinlong, XU Bo, ZHANG Panwang
Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (6): 1105-1114.   DOI: 10.13209/j.0479-8023.2025.096
Abstract738)   HTML    PDF(pc) (796KB)(277)       Save
This study focuses on the lower reaches of the Heihe river in Northwest China’s arid region, utilizing MOD13 Q1-NDVI data from 2000 to 2022, complemented by concurrent temperature (Tem) and precipitation (Pre) records, to investigate the spatiotemporal dynamics of fractional vegetation cover (FVC) and its response mechanisms in the context of climate change. The findings reveal that: 1) The FVC in the lower Heihe river region exhibits an overall trend of slow, fluctuating improvement, indicating a gradual recovery. However, the FVC remains relatively low, with the core oasis areas displaying weak ecological stability. These regions are highly susceptible to the impacts of climate change and human activities, thus exhibiting significant ecological fragility. 2) Climate change in the lower Heihe river region is influenced by global trends while it exhibits distinct local characteristics. The region has experienced a pronounced warming trend with notable fluctuations in Tem increases. Meanwhile, Pre has shown a slight decline, characterized by highly unstable interannual variability. The increasing aridity of the climate has further exacerbated the risk of vegetation degradation. 3) The relationship between FVC changes and Tem or Pre is weakly correlated. These climatic factors have influence on FVC, but they are not the primary drivers. FVC is also significantly affected and constrained by other factors such as surface water availability, groundwater levels, and soil salinity. 
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Influence of Campus Exclusion on Adolescents’ Externalizing Problem Behaviors: A Moderated Mediation Model
YU Hongyu, XU Xinyang, ZHANG Jing
Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (3): 601-607.   DOI: 10.13209/j.0479-8023.2024.108
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This paper intends to understand the relationship between campus exclusion, resilience, parental-child relationship and adolescents’ externalization behavior. To explore the mediating role of resilience in the impact pathway of campus exclusion on adolescents’ externalization behavior, as well as the moderating role of the parent-child relationship in this pathway, 543 junior high school students in Guizhou were measured by using the adapted inventories of the Adolescent School Exclusion Scale, the Resilience Scale for Adolescents, the Parent-Child Intimacy Scale, and the Conduct Problem Tendency Scale. The results indicated that campus exclusion can positively predict the externalization problem behaviors of adolescents. Resilience played a partial mediating role in the impact pathway of campus exclusion on adolescent externalization behavior. This means campus exclusion can not only directly predict adolescent externalization behavior positively, but also indirectly predict adolescent externalization behavior through resilience. Parent-child relationships positively regulated the mediating effect of resilience, specifically the first half of the pathway, where parent-child relationships significantly positively regulated the impact of campus exclusion on adolescent resilience. As adolescent parent-child relationships improved, the predictive effect of campus exclusion on adolescent resilience increased. From this, it can be seen that campus environment, family relationships, and individual resilience can all affect adolescent externalizing problem behaviors. 
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Simulations of Nitrous Acid (HONO) and Its Impact on Ozone in Kunming, China
ZHANG Jingwei, GONG Yuanjun, RAN Haiyan, TAN Yaxian, QU Yu, AN Junling, LU Keding, DONG Huabin, QIU Fei, YANG Jian
Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (2): 325-334.   DOI: 10.13209/j.0479-8023.2024.113
Abstract2807)   HTML    PDF(pc) (8474KB)(2636)       Save
The first nitrous acid (HONO) observation was conducted in Kunming of Yunnan Province, from April to May 2021 with frequent ozone (O3) pollution events. To evaluate the impact of HONO on O3, the WRF-Chem model simulations were conducted, with two cases including or excluding potential HONO sources. Based on the comparison between simulations and the corresponding observations, it was found that the application of the MEIC inventory (version 2020) could reasonably simulate HONO, nitrogen dioxide (NO2), O3 and fine particulate matter (PM2.5) in urban Kunming. The additional HONO sources noticeably enhanced atmospheric oxidation capacity in Kunming and accelerated the hydroxyl radical (OH) production rate, leading to an O3 enhancement of (2–6)×10⁻⁹ with the corresponding percentage enhancement of 2%–8% at the Kunming site within the height of 0–4 km and an O3 enhancement of (4–7)×10⁻⁹ near the ground at the Kunming site and its surrounding area. The O3-VOCs-NOx sensitivity was also influenced by the potential HONO sources. This study deepened the understanding of HONO, atmospheric oxidation capacity and O3 formation in the Yunnan-Guizhou Plateau, and could be helpful for regional O3 pollution control. 
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Phase Transitions and Elastic Properties of NH4Cl at High Pressures
ZHANG Jingyi, HUANG Shengxuan, QIN Shan
Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (1): 121-129.   DOI: 10.13209/j.0479-8023.2024.086
Abstract1435)   HTML    PDF(pc) (1622KB)(2702)       Save
Synchrotron radiation single crystal X-ray diffraction (XRD), Raman spectroscopy and infrared spectroscopy were used to analyze natural ammonium chloride (NH4Cl) under high pressure. The results show that NH4Cl transforms from phase IV (space group ) to phase V (space group P4/nmm) at 13.6 GPa. The parameters of the third-order Birch-Murnaghan equation of state are determined with K0=24.9(1) GPa, V0=56.4(1) Å3, K0′=5.5 for phase IV, and K0=35(25) GPa, V0=110(11) Å3, K0′=3.8(13) for phase V. The Raman spectrum of NH4Cl shows new peaks and discontinuity at 13.7 GPa, and the Raman shift are linearly related to pressure. dνi/dP and Grüneissen parameters for each vibration of phase IV and V are obtained. The infrared spectrum of N—H vibration split at 11.7–14.8 GPa. The transition pressures from phase IV to V of NH4Cl, NH4Br and NH4I decrease in turn, which are inversely proportional to the anion radius. 
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Synthesis of Remote Sensing Optical Images with Ship Targets Based on Generative Adversarial Networks
JI Rui, MA Lei, ZHANG Jing, WANG Weihong, GUO Zhizhou, WAN Xianci, XIAO Lei, WAN Wei
Acta Scientiarum Naturalium Universitatis Pekinensis    2024, 60 (5): 883-892.   DOI: 10.13209/j.0479-8023.2024.067
Abstract2079)   HTML    PDF(pc) (21009KB)(430)       Save
Due to real-world constraints, the quantity of ship datasets derived from remote sensing data is substantially limited and can’t fulfill the extensive sample demands required for training deep learning algorithms. According to this problem, a high-quality synthesizing method for three-band optical high-resolution remote sensing images containing ship targets is introduced, which utilizes 3D models and generative adversarial networks with style transfer capabilities. Based on the constructed dataset, synthetic samples are generated and evaluated. The experiments indicate that the approach can synthesize images visually close to real images. Incorporating these synthetic samples into the training process of detection models results in an increase of 2.6% in mAP for Faster R-CNN and 2.3% for YOLOv5.
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Prediction and Path of Carbon Peak in Shannan Region of Tibet Based on Multi Scenario Analysis
ZHANG Yang, ZHANG Jinbo, JIANG Shaorui, GUO Huaicheng, WANG Shuhang, FU Zhenghui
Acta Scientiarum Naturalium Universitatis Pekinensis    2024, 60 (2): 350-356.   DOI: 10.13209/j.0479-8023.2023.101
Abstract1593)   HTML    PDF(pc) (812KB)(464)       Save
This study takes Shannan City in Tibet as the research object, and proposes peak paths and specific policy suggestions based on the prediction results of carbon emission peak values in different scenarios by constructing a GM-ImPACT model. The results show that, the current economic growth rate coupled with strong emission reduction strategies is the optimal path for Shannan City to achieve carbon peak. Shannan City is expected to achieve carbon peak 10 years ahead of schedule in 2024, reducing its total carbon emissions by 20.72%, and its carbon emission intensity will drop by 7.89 percentage points higher than the national level. The proposed model framework could be applied to explore the optimal path of carbon peak for other cities.
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Investigating Fish Diversity in Huangjinxia Section of the Upper Hanjiang River Based on Environmental DNA Metabarcoding
DING Yang, LI Yanyan, ZHAO Jinyong, PENG Wenqi, ZHANG Jing, REN Jinhao
Acta Scientiarum Naturalium Universitatis Pekinensis    2024, 60 (1): 157-164.   DOI: 10.13209/j.0479-8023.2023.080
Abstract1732)   HTML    PDF(pc) (15908KB)(156)       Save
 In 2020, Environmental DNA Metabarcoding was used to study the fish diversity in the Huangjinxia section of the upper Hanjiang River, and the historical survey data were compared to construct a fish list in the Huangjinxia section of the upper Hanjiang River. A total of 20 fish species were detected from 9 sampling sites, accounting for 45.45% of the list; Cyprinus_carpio, Carassius_auratus, Distoechodon_tumirostris and Squalidus_argentatus are the dominant species. The Shannon index of fish in the upper and lower reaches of the Huangjinxia was significantly different (P < 0.01, n=9), and the Shannon index of fish in the upper reaches was significantly larger than that in the lower reaches. The main reason for the spatial differences in fish diversity is the Huangjinxia hydraulic hub. The fish composition detected by environmental DNA was similar to that obtained by traditional methods. As an emerging biomonitoring tool, environmental DNA macrobarcoding technology can complement traditional fish monitoring methods to rapidly detect fish diversity and its spatial distribution in the upper reaches of the Hanjiang River. 
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Analysis of Air Pollution Emission Effects of the Industrial Sector in Hebei Province Based on the Emission Decomposition
WANG Han, ZHANG Jinbo, GUO Huaicheng, ZHANG Wenjie, WANG Shulan
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (5): 823-832.   DOI: 10.13209/j.0479-8023.2023.048
Abstract1695)   HTML    PDF(pc) (870KB)(434)       Save
In order to explore the impact of social, economic and industrial energy factors on air pollution emissions of the industrial sector in Hebei Province, the LMDI model was adopted to decompose the air pollutant emissions of the industrial sector in Hebei Province from 2013 to 2020. Four economic and industrial energy consumption scenarios were set according to the current economic development and pollutant emission trend. The contributions of future socio-economic and industrial energy effects to pollutant emission in Hebei Province by 2035 were predicted under these scenarios. The results show that the industrial structure and energy structure of Hebei Province have been thoroughly adjusted in recent years, and the dependence of economic development on industry has been reduced. The reduction of industrial sector capacity and the elimination of outdated production capacity have achieved remarkable results. Clean use of energy is still an effective means of industrial green and clean transformation. In addition, the current energy structure of the industrial sector still needs to be further adjusted, and the application of new energy and clean energy in the industrial sector is the main adjustment direction in future. The prediction results indicate that the slowdown of gross regional domestic product growth will promote the emission reduction of air pollutants in the industrial sector, and the contribution of the adjustment of industrial and energy structure to the emission reduction of air pollutants in the industrial sector will gradually increase. 
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Adsorption of Phenol by Oxidized Multi-Walled Carbon Nanotubes
HAI Hao, WANG Ke, MA Yibo, ZHANG Jing, XIA Jianxin, XING Xuan, WANG Ting
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (5): 961-967.   DOI: 10.13209/j.0479-8023.2019.061
Abstract3259)   HTML    PDF(pc) (7875KB)(833)       Save
Organic compounds pollution, especially phenolic compounds, has been a serious problem recently. Multi-walled carbon nanotubes (MWCNTs) were oxidized by mixed acid oxidation method to remove phenolic compounds by adsorption. Five typical phenolic compounds including phenol, p-cresol, p-methoxyphenol, phydroxybenzaldehyde and p-nitrophenol were selected and to be adsorbed on MWCNTs and MWCNTs-O, respectively. Results showed that compared with the unmodified MWCNTs, the adsorption capacity of five phenolic compounds on MWCNTs-O increased significantly. The adsorption amount of five phenols on MWCNTs-O was different and the order was p-nitrophenol >p-methoxyphenol > p-hydroxybenzaldehyde > p-cresol > phenol. Adsorption isotherm data for the five phenols fitted Langmuir model well, which proved that phenolic compounds on MWCNTs was monolayer chemisorption. Surface functional groups analyzation of MWCNTs-O indicated that acidic oxygen-containing functional groups increased. TEM and Raman spectroscopy showed the winding degree of MWCNTs decreased, and overall dispersion and the degree of graphitization increased. π-π conjugation between vertical π electrons on MWCNTs-O and π electrons of phenolic compounds was formed and the electronic energy (EE) could be used as indicator for phenols adsorption on MWCNTs-O.
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Dynamic Variation Characteristics and Influencing Factors of Evaporation Intensity of Permeable Pavement
ZHANG Jingyi, QIN Huapeng, ZHAI Yanyun
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (5): 934-940.   DOI: 10.13209/j.0479-8023.2019.060
Abstract2052)   HTML    PDF(pc) (2018KB)(533)       Save
A typical evaporation simulation platform for permeable concrete pavement is designed and built. The variation process of moisture content, evaporation, moisture absorption, surface temperature and the weather conditions in Shenzhen city are continuously monitored and recorded under the natural environment conditions, which are carried out to analyze the variations in the evaporation intensity of the pavement, and to explore the main influencing factors. The results show that, in the rainy season, the rainfall can significantly increase the evaporation intensity of permeable concrete pavement, but its influence is limited, and this enhancement effect will gradually weaken to a lower level in eight hours. With the variation of time and rainfall conditions, the influence degree of many factors is different in different periods. During the daytime, the evaporation intensity of permeable concrete pavement is positively correlated with the solar radiation and moisture content. During the nighttime, the evaporation intensity is close to zero when there is no rain in the early stage, which is only correlated with the change of wind speed. While after the rainfall, the higher air temperature, greater wind speed, higher moisture content and surface temperature of the pavement will increase the evaporation intensity, however the increase of the relative humidity will lead to the decrease of the evaporation. In the dry season, permeable concrete pavement, as a porous medium, can increase moisture content and promote evaporation intensity by the moisture absorption on the surface of the pavement, which is an important factor affecting the dynamic variations of the evaporation intensity.
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Reductive Removal of Four Halogenated Organic Compounds by Different Sizes of Zero-Valent-Iron
ZHAO Xufei, WEI Caijie, ZHANG Jin, WU Weizhong, WANG Xiaomao, YANG Hongwei, XIE Yuefeng
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (2): 435-442.   DOI: 10.13209/j.0479-8023.2017.165
Abstract2635)   HTML79)    PDF(pc) (1022KB)(1742)       Save

Based on the chlorinated organic compounds pollution existed in underground water of China, Zero-Valent-Iron (ZVI) technology is employed for the removal of four representative halogenated organic compounds (HOCs) (tetrachloroethylene, PCE; tricholoroethylene, TCE; tetrachlormethane, TCM; and chloroform, CT). The results indicated that the reduction rates of four target compounds, of which the initial concentration is 400 μg/L, negatively correlated with the size of Zero-Valent-Iron particles. The reduction kinetics of the targeted HOCs were all well fitted with the Pseudo-firstorder kinetics, and the ranking of obtained first order rate constants (K) among different particle sizes was K20nm>K100nm>K10μm>K100μm. Comparing K among four target HOCs, the reduction rates of chlorinated methane (CT, TCM) are higher than chlorinated ethylene (PCE, TCE), and highly chlorinated HOCs (PCE, CT) were degraded more easily than lower one (TCE, TCM). pH of aqueous solution all increased along the chlorinated compounds reduction which was raised by the reaction between ZVI and water. The oxygen in water consumed the ZVI particle either and competed with the surface adsorbed chlorinated compounds. In summary, Zero-Valent-Iron proved to be an efficient technology for typical HOCs removal, which can be considered as a promising process added in the beginning part of drinking water treatment plant.

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An ICA Based Method for Grid Radio Signal Monitoring
ZHANG Jingshu, Lü Mengfei, LI Dou, YANG Yanjun, ZHAO Yuping
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (2): 307-314.   DOI: 10.13209/j.0479-8023.2017.173
Abstract2009)   HTML141)    PDF(pc) (791KB)(881)       Save

An independent component analysis (ICA) based method is designed for improving the effect of grid radio monitoring and providing an effective layout of the monitoring system, in which the source signals can be retrieved and sudden emergence of abnormal signal sources can be detected. To analyze the multiple factors affecting the performance of the method, a MATLAB simulation modeling is built. The feasibility and efficiency of the proposed ICA based method are also demonstrated.

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A Study of Articulatory Features Based Detection of Mandrain Pronunciation Erroneous Tendency for Automatic Annotation
WEI Xing, WANG Wei, CHEN Jingping, XIE Yanlu, ZHANG Jinsong
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (2): 243-248.   DOI: 10.13209/j.0479-8023.2017.152
Abstract2807)   HTML147)    PDF(pc) (1670KB)(1392)       Save

For the purpose of relieving the time cost and inconformity in annotation, the authors use an articulatory features based mispronunciation detection system to give an Top-N feedback and use this feedback to assist manual annotation. As a result, the consistency rate of phoneme labels in proposed system increases from 80.7% to 92.48%. In addition, the time cost for annotating each sentence reduce from 10 to 3 minutes. The results indicate that proposed automatic annotation system is practical, and there is also a room for further improvement.

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Simulation of Temporal and Special Land Use Changes in Jing-Jin-Ji Urban Agglomeration Using CLUE-S Model
ZHANG Jin, ZHU Wenbo, WU Shuyao, LI Shuangcheng
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (1): 115-124.   DOI: 10.13209/j.0479-8023.2017.137
Abstract2926)   HTML156)    PDF(pc) (9653KB)(1312)       Save

For the land use demands of Jing-Jin-Ji urban agglomeration cooperative development strategies, four kinds of land use policies, i.e. status quo continuation, food security, nature protection and urban expansion were made. A modified Cobb-Douglas utility function was developed to quantify the influence of different policies on various land use demands, and a CLUE-S model was built to simulate the spatial and temporal evolution of Jing-Jin-Ji land use under different policies. Results show that, compared with year 2010, great changes occur on land use areas and patterns in the year 2020 under different policies. “Status quo continuation” is characterized by the continuous expansion of urban groups, increasing the construction land by 2280 km2. “Food Security” significantly increases the arable land by 3611.4 km2, while reducing the ecological land including forest and grassland. “Nature protection” greatly reduces the area of arable land by 3082.13 km2, while increasing forest, grassland and water area by 3726.4 km2. “Urban expansion” substantially increases the construction land by 3375 km2, while decreasing other types of land use. Spatially, every land use policy has its significant regional characteristics in land use conversion. The increase of construction land always comes together with the decrease of arable land, which tends to occur in the existing urban surroundings. The increase of ecological land is more often seen in Bashang plateau, Yanshan Mountains as well as Taihang Mountains. This study has great reference value in designing optimal land use policies, especially in the gradual implementation stage of the Jing-Jin-Ji collaborative development strategies.

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Geometry and Tectonic Evolution of the Laojunmiao Break-Thrust Belt in the Northern Margin of Qilian Mountain
XIAO Yuxiang, DU Wenbo, ZHANG Bo, ZHANG Jinjiang, HOU Xiulin, WANG Wei, HE Xin, LI Xiaojun, YIN Congyuan
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (5): 891-901.   DOI: 10.13209/j.0479-8023.2016.054
Abstract3159)   HTML    PDF(pc) (6159KB)(2475)       Save

On the base of the 3D seismic profile interpretations, combined with the previous findings, geometry and tectonic evolution across and along the Laojunmiao break-thrust belt in the northern margin of the Northern Qilian belt are deciphered. The Laojunmiao belt is a bi-layer thrust system, consisting of a trishear faultpropagation fold system in the upper part, wedge-shaped thrust in the lower part. The Laojunmiao thrust system is linked with the NE-SW striking-slip 134 fault in the western segment, which forms a unified system of fracture on the Laojunmiao belt. Thrusting sheet above the hanging wall of the 134-Laojunmiao fault system is folded under nearly E-S compressive stress field, which results in the N-S striking folding to superpose on the Cenozoic bedding.

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Prediction and Zoning Evaluation of Urban Sprawl in Shenzhen
ZHANG Jin,LI Shuangcheng,WANG Yang
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1277)      PDF(pc) (1999KB)(733)       Save
Taking Shenzhen, Guangdong Province, China as an example, CLUE-S model was used to simulate its urban sprawl in 2020. An evaluation system was established based on indicators from speed, strength, morphology, social economic benefits and ecological benefits of urban sprawl. By using SOFM network, the authors zoned the region and evaluated the urban sprawl for each zone. Main conclusions include that 1) Shenzhen can be divided into four regions according to future (2020) urban sprawl, i.e. the highly urbanized zone, the developing zone, the potential zone and the ecology priority zone, and therefore reasonable adjustments of development strategy need to be made; 2) by 2020, the overall quality of urban sprawl in Shenzhen will be high according to current trend, however, problems such as the low efficiency of land use and the incoordination of social-economic and ecological benefits still exist; 3) based on CLUE-S and SOFM, combined with urban sprawl comprehensive evaluation index system, the future urban sprawl can be predicted and analyzed effectively.
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Recognition and Classification of Emotions in the Chinese Microblog Based on Emotional Factor
ZHANG Jing,ZHU Bo,LIANG Linlin,HOU Min,TENG Yonglin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1880)      PDF(pc) (528KB)(1461)       Save
Based on basic emotional words and phrases, an emotional dictionary was bulit. According to the special expressions of emotions and functions of punctuations and emoticons in the emotional analysis, a set of emotional rules were set up. The authors recognized and classified the emotions in microblogs according to the algorithm based on the emotional rules and dictionary, and achieved preferable result in the task of emotional analysis of Chinese microblogs in the 2nd Conference on NLP&CC hosted by CCF in 2013. Experiment results show that this algorithm can work effectively.
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Rapid Pliocene Uplift of Western Kunlun: Evidenced by the Heavy Mineral Assemblages and Detrital Rutile Geochemistry
YAN Shuyu,ZHANG Jinjiang,SONG Yan,LI Benliang,WANG Xiaoxian,WANG Meng
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1109)      PDF(pc) (632KB)(932)       Save
The heavy mineral assemblages and detrital rutile geochemistry of Cenozoic sandstone at Kekeya profile near the western Kunlun Orogenic belt were analyzed. Two mineral sections were identified based on the contents and features of the heavy mineral assemblages: stable and unstable heavy mineral segment, which were divided by the bottom of Atushi group (N2a). These implied a rapid uplift in the western Kunlun in the Pliocene. The content of detrital rutile derived from metapelitic decreased, while that derived from metamafic increased with rising of the profile. This result suggests that basement rocks were denudated and deposited due to rapid uplift and erosion. The metamorphic stages of detrital rutile were mainly amphibolite/elogite and granulite facies, which may result from a differential uplifting of the Western Kunlun. Since Oligocene, the west part is higher than the eastern part and becomes the main provenance area.
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Numerical Simulation of Shear Strain-Localization on Rock Specimen under Uniaxial Compression to Verify the Maximum Effective Moment Criterion
SHEN Falong,ZHANG Jinjiang
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1257)      PDF(pc) (881KB)(1918)       Save
Based on the strain softening theory, the authors present a simulation of the development from localized ductile zone to crenulation cleavage in specimen which can be used to verify the theory of MEMC. With the FLAC3D, the rock specimen with the shape parameters and the stress of loading rate ruled by corresponding standard regulations were designed. The numerical simulation of the forming process of the localized shear belts under the uniaxial compression shows that the conjugate angle of the shear belt is 107.7° after strain softening, verifying the MEMC and explaining the random behavior expression of the contour map of shear strain on the cross section.
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Automatic Recognition Research on Chinese Adverb DOU’s Usages
ZHANG Jingjie,ZAN Hongying
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1280)      PDF(pc) (420KB)(553)       Save
The authors recognized the adverb DOU’s usages with two methods, rule-based and statistics-based, and analyzed theirs advantages and disadvantages, respectively. And then, the methods of rule-based and statistical- based were combined. The accuracies of these three methods are 82%, 89.62% and 98.54%. The experiments show that combination method of rule-based and statistical-based is more effective in automatically recognizing of adverb DOU’s usages.
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Study on Urban Change of the Yangzhou City within 2500 Years Based on 3S
YANG Jing,ZHANG Jinchi,ZHUANG Jiayao,MAO Feng
Acta Scientiarum Naturalium Universitatis Pekinensis   
Triassic Tectonic Decoupling in Weiyuan Uplift (Sichuan) and Its Implications
GU Zhidong,YAN Shuyu,ZHANG Bo,ZHANG Jinjiang
Acta Scientiarum Naturalium Universitatis Pekinensis   
Kink-Band Structure and Its Geophysical Forward Modeling
ZHANG Bo,ZHANG Zhongpei,ZHENG Yadong,ZHANG Jinjiang,YAN Shuyu
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1547)      PDF(pc) (8859KB)(330)       Save
Finite-difference method-single-shot record method is applied to forward-model kink-band models. Based on the analysis of forward modeling results and the features of seismic images response to the various kink-band belt models, the conclusions are summarized as follow. 1) In the seismic profile, kink-band belt is characterized by the substantial width of low-reflectivity, low-signal-to-noise zone and their sub-parallel edges in cross section, which are different from the features of the fault structure. 2) Their orientations at a high angle to layering can impact on the seismic imaging efforts. 3) Steeply or nearly vertical dipping bedding in the kink-band belt often misguide the reflection interface tracking by some overvalued and other false information. These results can provide first references for interpretation of the seismic profiles, such as identifying structural type, and distinguishing the fault from the kink-band.
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Geometric and Tectonophysical Simulate of the Bachu Fold Belt: Central Region of Tarim Basin
ZHANG Bo,YAN Shuyu,ZHANG Zhongpei,ZHANG Jinjiang,ZHENG Yadong,WANG Xiaoxian,WANG Meng,WANG Jiamin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1229)      PDF(pc) (15321KB)(258)       Save
Based on structural geometries, kinematic observations, and sand-box simulation results, the new interpretation explains that the Bachu fold belt in the Tarim basin is composed of detachment folds flanked by various-scale kink bands primarily unassociated with faulting. The Bachu antiform belt is characterized by the detachment fold. The detachment fold crests are bounded by kink bands, which are narrow zones of angularly folded strata. The substantial width of these kink bands, their sub-parallel edges in the outcrop cross-sections, and their orientation at a high angle to layering, as well as their organized spacing and conjugate geometry, support a kink-band interpretation. Application of sandbox models for tectonic simulate modeling regenerates kink-band development and evolution: wide-gentle detachment folding → tight detachment folding → fold pop-up → fault adjusting. The analog results strongly support that the kink-band is one of the structure types to form the Bachu fold zone.
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A New Insight into the High-Angle Deformation Bands in the Central Region of Basin
ZHANG Bo,ZHANG Zhongpei,ZHANG Jinjiang,YAN Shuyu,WANG Xiaoxian ZHENG Yadong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1284)      PDF(pc) (15133KB)(273)       Save
Based on the review of rock mechanics theory and recent simulated experiment results, as well as sand-box simulation and seismic profile interpretation, the new interpretation explains that some uplifts/folds with high-angle deformation bands in the Tarim basin to be composed of folds flanked by megascopic-scale kink bands. The low-reflectivity, low-signal-tonoise zones seen in seismic profiles across the Bachu fold belt are poorly imaged sections of the folds that result from steeply dipping bedding in the kink bands. These fuzzy seismic zones show a substantial width in the seismic profile. According to the Maximum Effective of Moment Criterion (MEMC), the substantial width of these low reflectivity zones, their subparallel edges in cross section, and their orientation at a high angle to layering, as well as their organized spacing and the obtuse angle in the contraction direction of conjugate kink-bands, indicate that there are kink-band structures and kink-related folds in the Bachu uplift.
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A Landmark-Based Linear Referencing Method
GAO Yong,ZHANG Jing,ZHANG Yi,LIU Yu
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1243)            Save
The traditional linear referencing methods utilize network nodes as the references, but positioning and way finding in linear networks are always referenced by landmarks in common sense. Based on landmarks, a new linear referencing method is presented. Landmarks are adopted into alinear network by defining their projections to substitute network nodes as the referenced originpoints. And a landmark-based network Voronoi diagramis constructed. Then any point on the network can be linear referenced relatively by its Voronoi generator using a pair of the neighbor landmark and their shortest path. This landmark-based linear referencing method is proved sound, complete, and unique except the boundaries. It is coordinated to the human’s commonsense spatial cognation and straightforward to be understood and utilized. This method can also support many complex GIS applications such as route cognition, wayfinding, k-nearest neighbor search, and retail stores analysis, etc.
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Tectonic and Environmental Evolution of Gyirong Basin, and its Relationship to the Uplift of Tibetan Plateau
WANG Dechao,ZHANG Jinjiang,YANG Xiongying,QI Guowei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1262)            Save
The Gyirong faulted basin, located in the northern slope of Himalayas, received over 300m thick sediments of lacustrine and fluvial facies scince late Miocene to early Pleistocene. Based on the analyses of the sedimentology, carbon-oxygen isotope and basin-controlling structures, integrated with previous studies of paleontology and palynology, this paper gave reconstructions on the controlling structures, sedimentary environment, climate changes and the evolutionary processes of this basin in the late Cenozoic. The coupling relationship between tectonic evolution and climate changes was also discussed. This study shows that the Gyirong basin underwent a evolution successively from a half-closed faulted lake basin in the early stage,to an open lake basin in the middle stage, and to a closed lake basin in the final stage.
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Urbanization Effects on Local Climate in Shenyang in Recent 47 Years
MA Mingmin,JIANG Xiaoyan,LIU Shuhua ZHANG Jing
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1431)            Save
Based on the meteorological data from five weather stations of Shenyang during 1959-2005, the change trends and characteristics of the temperature, precipitation, relative humidity, wind speed of urban and rural areas of Shenyang are analyzed. The effect of urbanization on local climate in Shenyang is discussed. The results show that: 1 in recent 47 years, the temperature of Shenyang has increased remarkably, with the most obvious warming occurring in winter and spring, and a little warming trend in summer. Meanwhile, the warming trend of rural areas increases slightly faster than that of urban areas. 2 The change trends of precipitation, relative humidity, wind speed of Shenyang decreases mostly, of which wind speed decreases most and precipitation decreases least. Compared with relative humidity and wind speed, the seasonal change trend of precipitation is complex, with a little increase in winter. The analysis indicates that the development of urbanization in Shenyang has a serious effect on local climate, especially on the climate of rural areas. Furthermore, the effect of urbanization on temperature and wind speed is more obvious and direct than that on relative humidity and precipitation.
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Climate Change in Shenzhen during 1953-2004
ZHANG Enjie,ZHAO Xinyi,ZHANG Jingjing
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1736)            Save
Based on the meteorological data during 1953-2004, the characteristics of climate change in Shenzhen in the recent 50 years are studied. The results are summarized as below: the temperatures have increased, with a warming rate of 0.34 ?/10 a; the warming rate is larger in summer and autumn; temperature increase at night is more remarkable. Daily temperature ranges become smaller, particularly in autumn and winter. The lowest temperature shows an increasing trend. Hot days is increasing. Precipitation days, sunshine times and relative humidity are obviously decreasing. These characteristics are more remarkable after 1980s, when Shenzhen started developing rapidly. The results suggest that the effect of urbanization in Shenzhen should be considered in future study of climate change.
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Spatio Temporal Topological Relation Modeling of Moving Objects
GAO Yong,ZHANG Jing,ZHU Xiaoxi,LIU Yu
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1360)            Save
Researches on spatio temporal characteristics of moving objects gained more and more attentions because of the increasing application demands. Spatio temporal topological relation, one of the main topics about moving objects, contributes much to such researches on data model, index and query, etc. Aimed to planar moving objects in Euclidean space, a time sliced date model is presented firstly. Then based on the point set theory, a qualitative model about spatio temporal topological relations between moving objects is defined. The temporal relation and spatial relation are expressed by the 9 Intersection model separately, and then the sptio temporal topological relation is defined as their combination considering the dynamic behavior of moving objects. To compute the spatio temporal topological relations, the validation, computability and computation rules about this model are given as well. This model can aggregately express the spatial distribution and temporal evolvement of moving objects, especially the dynamic characteristics. And it will conduce to researches about moving objects databases and spatio temporal query.
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