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Analysis of the Reasons why Surface Wave Magnitude is Higher than Moment Magnitude in the Mainland of China from the Perspective of Source Rupture Parameters
XU Yueyi, ZHANG Yong
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (3): 407-414.   DOI: 10.13209/j.0479-8023.2023.020
Abstract173)   HTML    PDF(pc) (1026KB)(69)       Save
The influence of the source parameters on Ms is studied through numerical simulations based on finite-fault models. The results show that the Ms is negatively correlated with earthquake rupture duration when moment magnitude remains unchanged. The source parameters that can impact the rupture duration contain the sub-fault duration, rupture velocity, and rupture length. Among them, the sub-fault duration and rupture length is negatively correlated with Ms, while the rupture velocity is positively correlated with Ms, if the moment magnitude remains unchanged. The fact that the measured Ms of strong earthquakes in the mainland of China are significantly larger than moment magnitudes may be due to two reasons. First, the strong earthquakes in the mainland of China are mostly intraplate earthquakes with relatively higher stress drop values, which may have short rupture duration and rupture length. Secondly, Ms determined by China Earthquake Networks Center (CENC) is systematically larger than Ms(20) determined by National Earthquake Information Center.
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Multi-turn Event Argument Extraction Based on Role Information Guidance
YU Yuanfang, ZHANG Yong, ZUO Haoyang, ZHANG Lianfa, WANG Tingting
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (1): 83-91.   DOI: 10.13209/j.0479-8023.2022.064
Abstract236)   HTML    PDF(pc) (685KB)(119)       Save
Aiming at the two problems of insufficient utilization of role information and lack of interaction between arguments in general domain event argument extraction research, a role information-oriented multi-turn event argument extraction model is proposed to enhance the semantic information of texts and interactions between arguments. The interactive capability can improve the performance of event argument extraction. First, to better utilize role knowledge to guide argument extraction, the model builds role knowledge based on role definitions, independently encodes role information and text, and uses a method based on attention mechanism to obtain label-knowledge-enhanced representations. Then the augmented embeddings are used to predict whether or not each token is a start or end position for some category. At the same time, in order to make full use of the interaction between event arguments in the extraction process, inspired by the multi-turn dialogue model, this paper designs a multi-turn event argument extraction algorithm. The algorithm refers to the natural logic of “easiness to hardness”, and selects the character with the highest prediction probability, that is, the most predictable character, for extraction each time. In the process of argument extraction, in order to model the interaction between arguments, the model introduces historical embedding, and updates the historical embedding after each prediction to help the extraction of the next round of event arguments. The experimental results show that the guidance of role information and multi round extraction algorithm effectively improve the performance of argument extraction, and the method achieves state-of-the-art performance.
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Origin of Cherts during the Ediacaran-Cambrian Transition in Hunan and Guizhou Provinces, China: Evidences from REE and Ge/Si
WEI Shuaichao, CHEN Qifei, FU Yong, CUI Tao, LIANG Houpeng, GE Zhihua, ZHANG Peng, ZHANG Yong
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (5): 1010-1020.   DOI: 10.13209/j.0479-8023.2018.035
Abstract799)   HTML    PDF(pc) (5222KB)(137)       Save

Two types of Liuchapo Formation cherts, bedded cherts and mounded cherts, were deposited in Bahuang section of Tongren in Guizhou Province and Ganziping section of Zhangjiajie in Hunan Province. The origin of the cherts was discussed by analyzing the characteristics of major, trace elements and REE compositions and Ge/Si ratios. It was revealed that the content of SiO2 in bedded cherts was range from 96.06% to 99.61%, and the content of SiO2 in mounded cherts was range from 98.62% to 99.56%, averaging 99.13%, and the contents of other chemical components were very low. Thus, two types of cherts are pure cherts. Moreover, the ΣREE of the bedded cherts in Bahuang section is ranged from 20.14 to 248.56 μg/g (averaging 100.62 μg/g), and no obvious abnormality in Eu/Eu* which is ranged from 0.90 to 1.10 (averaging 1.06), and the ratio of Ge/Si is 0.13−0.98 μmol/mol (averaging is 0.50 μmol/mol), indicating that the origin of bedded cherts affected terrigenous input. Whereas, the ΣREE of the mounded cherts in Ganziping district is ranged from 3.75 to 7.24 μg/g (averaging 5.73 μg/g), the ratio of Ce/Ce* is 0.46−0.66 (averaging 0.57) which shows a negative abnormal, Eu/Eu* is ranged from 2.28 to 11.07 (averaging 4.60) which shows a positive abnormal, and Ge/Si ratio is 1.09−1.43 μmol/mol, (averaging 1.25 μmol/mol) all of which reflect a hydrothermal origin of the mounded cherts. Otherwise, the relationship between Al2O3 and ΣREE in the bedded cherts has an excellent correlation, while in the mounded cherts has a poor correlation. It also illustrates that continental substance plays an important role in controlling the formation of bedded cherts, and the mounded cherts is originated from submarine volcanic or hydrothermal activity. The relationship between Al2O3 and Ge/Si also reflect the origin of cherts. Combined with the paleogeographic environment, it can conclude that the mounded cherts were deposited in syngenetic fault at the margin of the basin, originated from submarine hydrothermal activity, while the bedded cherts were deposit in the deep basin, mainly influenced by terrigenous input. What’s more, using 1 μmol/mol as the critical value of Ge/Si may provide a new way to trace the material sources of cherts.

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The HLBP and CHLBP Features for Pedestrian Detection
CHENG Ruzhong, ZHANG Yongjun, LI Jingjing, WANG Guopin, LEI Kai, ZHAO Yong
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (5): 935-945.   DOI: 10.13209/j.0479-8023.2018.017
Abstract1097)   HTML    PDF(pc) (11351KB)(125)       Save

Two improved texture features (hybrid local binary pattern, HLBP) and (color based hybrid local binary pattern, CHLBP) which are based on gray image texture and color space are proposed for pedestrian detection. The experimental results show that, when FPPW is 10–4, the detection rate of HLBP is 93.96% which is about 3.46% and 9.68% higher than Uniform LBP and CSLBP respectively. At the same time, when combined with the HIKSVM classifier, CHLBP feature based on L′C′C′ space makes the detection rate up to 98.58%, and its detection performance has been greatly improved, by this method an good result could be obtained in pedestrian detection.

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Degradation Mechanism of Three Nitrogen Heterocyclic Compounds by a Microbial Consortium
ZHANG Yin,ZHENG Zhongyuan,ZHAO Cui,ZHANG Yongming,LIU Rui,WEN Donghui
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract562)      PDF(pc) (499KB)(270)       Save
A microbial consortium M19, originated from four degrading bacteria for degrading pyridine (Shinellazoogloeoides BC026), quinoline (Pseudomonas sp. BW004), and carbazole (Pseudomonas sp. BC039 and BC046) were used to explore the simultaneous degradation mechanism of nitrogen heterocyclic compounds (NHCs). The experimental results showed that the simultaneous degradation efficiency of the three NHCs by M19 was higher than those by any single strain. The intermediate products from quinoline degraded by M19 were the same as those by BW004. All four bacterial strains grew well in the media containing three NHCs, and the quinoline degradation gene (qorL) and carbazole degradation gene (carAa) had been held and expressed. The mechanism of NHCs’ simultaneous degradation by M19 was the simple superposition of the 3 degradation processes carried by each strain, however, the strains benefited from each other due to the rapid reduction of toxicity from NHCs.
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Polymer White Light-Emitting Diodes with p-Type Si Anode and Nanometer-Thick Polycrystalline p-Si Anode
GU Yongtao,WEI Feng,SUN Tuo,XU Wanjin,RAN Guangzhao,ZHANG Yong,NIU Qiaoli,QIN Guogang
Acta Scientiarum Naturalium Universitatis Pekinensis   
Design and Development of 3D Urban Geological Data Management and Service System
QU Honggang,PAN Mao,LV Xiaojian,LIU Xueqing,ZHANG Yongbo,YU Chunlin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract588)            Save
The history and current status of urban informationization are firstly analyzed The design for 3DUGS (3D geological data management and service system), including system target, architecture and main functions, data analysis and processing procedure, key tecknologies, is introduced Finally, the application of this design in the development of Beijing 3DUGS is presented
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Phenomenological Theory of Interdiffusion Growth of Solid Phase
CHEN Yongchong,QI Lu,ZHANG Yonggang,CHEN Changqi
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract826)            Save
Recently the phenomena of diffusion-induced stresses and strains have been highlighted but the systematic theoretical analysis is still scarce. Traditional theory of chemical diffusion in solid states can not describe the relation of diffusion fluxes and diffusion-induced stresses because the research subject of the traditional theory is the diffusing atom or atomic flux, not the volume unit in the interdiffusion field. For this reason, the concept "flow point" in the interdiffusion field is proposed and the methods of fluid mechanics are applied to construct the phenomenological theory for describing the interdiffusion growth of solid phase. Two types of phase growth, i.e. volume and interface growths, are then mathematically defined and the diffusion-induced stresses and strains related to the two types of phasegrowth are elucidated. Also, the interesting periodic layer formation during solid state reactions is discussed as the result of diffusion-induced stresses.
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Another Proof for A Combinatorial Lemma of Liao
ZHANG Yong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract789)            Save
It is given a geometrical proof of an essential combinatorial lemma of Liao.
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On the Average-shadowing Property
ZHANG Yong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract588)            Save
It is proved that a homeomorphism on a compact metric space with the average-shadowing property has only one chain component which is the whole space. In particular, every point is chain recurrent. Using this result it is given a short proof for a recent theorem of Sakai.
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