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Distinguishing Underground Nuclear Test by Matrix Decomposition ZHAO Kechang, ZHANG Xianbing Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (4): 609-614.   DOI: 10.13209/j.0479-8023.2022.042 Abstract （576）   HTML    PDF（pc） （456KB）（396）       Knowledge map    Save Using the seismic data of three underground nuclear tests and three nearby natural earthquakes, the focal seismic moment tensor is obtained by inversion, and the underground nuclear explosion is identified by matrix decomposition method. The results show that there are obvious explosion sources (EXP), compensated linear vector dipole (CLVD) source and double couple (DC) source in the source of underground nuclear explosion earthquake. The physical mechanism of CLVD is medium rupture caused by explosion, which accounts for a large proportion of underground nuclear explosion sources. Compared with underground nuclear explosion, natural earthquake is generally shear dislocation mode, and DC accounts for a large proportion of its source. Related Articles | Metrics | Comments（0）

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Characteristics and Source Apportionment of VOCs in Suzhou, China LI Jiayin, ZHOU Ming, NING Miao, SHI Xurong, YAN Gang, MA Qiang, LU Keding Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (4): 771-781.   DOI: 10.13209/j.0479-8023.2022.051 Abstract （535）   HTML    PDF（pc） （7571KB）（376）       Knowledge map    Save VOCs concentrations based on offline sampling in Suzhou from July to October 2020 were monitored, and temporal and spatial distribution characteristics, ozone formation potential (OFP) and sources of VOCs were conducted and compared with other studies in China. The results showed that the average concentration of VOCs in Suzhou in the summer is 47.1 nL/L, the average OFP is 334.7 μg/m3, and the aromatic hydrocarbons and oxygenated organics (OVOCs) are important components of VOCs in Suzhou and contribute a lot to ozone generation. The trends of VOCs concentration and composition in Suzhou are similar with those in Shanghai. Positive matrix factorization (PMF) model results showed that six major sources of VOCs in Suzhou are liquefied petroleum gas volatilization sources (20.7%), solvent usage sources (19.5%) and industrial sources (17.5%), followed by other sources, vehicle exhaust emission sources and combustion sources, in which the contribution of liquefied petroleum gas volatilization sources is higher than the general level in Yangtze River Delta. The higher concentration of aromatic hydrocarbons in the Yangtze River Delta is related to the higher contribution of industrial and solvent uses. In general, aromatic hydrocarbons and OVOCs have a greater impact on the atmospheric environment of Suzhou. The main sources are surface coating, gas stations, traffic emission, petrochemical sources and electric heating sources, which should be mainly controlled.  Related Articles | Metrics | Comments（0）

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A Reduced-order Sub-region Model for Structural Damage Analysis under Sudden Disasters HAN Xudong, SUN Shuli Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (4): 591-596.   DOI: 10.13209/j.0479-8023.2021.113 Abstract （778）   HTML    PDF（pc） （11866KB）（368）       Knowledge map    Save  A simplified order-reduced sub-region model and the analysis method are proposed to analyze structural damage caused by local failure under sudden disasters. The method firstly divides a complex building into sub-regions. Secondly it evaluates the failure degree of sub-regions according to the state of internal components, then analyzes the failure process from macro regional perspective. Finally it summarizes the law of collapse evolution so as to provide guidance for emergency management.  Related Articles | Metrics | Comments（0）

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Study on Adsorption of H2O Molecules on KDP (100) Surface Based on DFT SU Xinyang, HE Xiantu, CHEN Jun Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (5): 785-794.   DOI: 10.13209/j.0479-8023.2022.087 Abstract （942）   HTML    PDF（pc） （13079KB）（364）       Knowledge map    Save Based on the calculation method of First-Principles in DFT, the authors carry out the study of the properties of H2O molecules adsorbed on the KDP(100) surface. By topological analysis of the electron density. combining analysis methods such as Bader charge, electron density, electron density difference, electron localization function and other parameters, it is found that the best adsorption site for H2O molecules on KDP(100) surface is H-K bridge site where adsorption energy is –0.809 eV, indicating that the KDP(100) surface can absorb H2O molecules spontaneously. The oxygen atoms in H2O molecules form strong hydrogen bonds O—H...Ow involving covalent effect, with bond energy –18.88 kcal/mol. Related Articles | Metrics | Comments（0）

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Instruction Extension Ensuring Time Constraints in Real Time Processor ZHAO Xiujia, LI Lei, LIU Xianhua Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (2): 179-188.   DOI: 10.13209/j.0479-8023.2023.013 Abstract （665）   HTML    PDF（pc） （1298KB）（358）       Knowledge map    Save Hardware software cooperation is one of the effective methods for the design of mixed criticality system, which realize resource isolation by necessary hardware semantics, and ensure that different critical tasks meet time constraints based on efficient thread scheduling. Based on a fine-grained multithreaded processor FlexPRET, this paper designs and implements some temporal instruction extensions, and realizes relevant supports in the processor and compiler respectively, so that the program can describe the timing constraint semantics of the worst-case execution time. Experiments show that the extended instructions can provide users with more accurate timing control. Related Articles | Metrics | Comments（0）

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Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (6): 0-.   Abstract （253）   HTML    PDF（pc） （2175KB）（347）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (5): 0-.   Abstract （299）   HTML    PDF（pc） （2230KB）（332）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Genetic Diversity and Phylogenetic Relationship of the Cosmopolitan Bdelloid Rotifer Rotaria sordida WANG Qing, WANG Wenbo, LI Ying, YANG Yufeng Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (5): 719-728.   DOI: 10.13209/j.0479-8023.2023.054 Abstract （350）   HTML    PDF（pc） （898KB）（329）       Knowledge map    Save In order to understand the phylogeny of Rotaria sordida in China and the world, and to clarify the driving factors of the genetic differentiation of bdelloid rotifers, R. sordida samples were collected from 12 cities in 10 provinces of China, and 32 COⅠ gene sequences were obtained. Moreover, 47 COⅠ gene sequences from Europe and Oceania in the GenBank database were downloaded, and the Bayesian phylogenetic tree was constructed at China and global scales, respectively. The results showed that the COⅠ gene sequences of R. sordida in China were divided into two taxonomic clusters, and their phylogenetic relationships were not only affected by geographical location, but also related to habitat types. At global level, all sequences were also divided into two clusters, and some sequences in China were clustered with sequences from Europe and Oceania. The bdelloids with the same habitat type in the two clusters had high homology. It was speculated that the phylogeny of bdelloid rotifers was driven by geographic distribution and habitat heterogeneity. Genetic diversity analysis based on the Generalized Mixed Yule Coalescent model (GMYC) showed that 22 haplotypes and 12 cryptic species were identified from the COⅠ sequence of R. sordida in China; 45 haplotypes and 28 cryptic species were identified from the global COⅠ sequence. This indicated the high hidden diversity in R. sordida species complexes. Therefore, habitat heterogeneity played an important role in cryptic species differentiation of R. sordida. This study preliminarily explained the phylogenetic relationship and genetic diversity of R. sordida in China and the world. Furthermore, this study supplemented the COⅠ gene database of bdelloid rotifers in China, and provided basic data for lineage biogeographic studies in the future.  Related Articles | Metrics | Comments（0）

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Whole Mount in situ Localization Technology of Plant Hormones WANG Donghui Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (5): 795-800.   DOI: 10.13209/j.0479-8023.2022.020 Abstract （508）   HTML    PDF（pc） （55439KB）（328）       Knowledge map    Save The existing phytohormones measurement methods are relatively cumbersome and difficult to measure the concentration of intracellular hormones. The paper describes whole-mount “immunolocalization” technique for the overall distribution of auxin (IAA) during lateral root and flower development in Arabidopsis. Based on the specific reaction of the antibody to the antigen, this method binds the antibody to the secondary antibody linked to enzymes, fluorescent molecules, etc. to detect the auxin in tissues or organs by light and electron microscopy, realizing the overall in situ localization of auxin (whole mount in situ localization of Hormone, WISIH). This method is not only suitable for growth hormone IAA, but also for rapid and reliable tissue or organ localization of hormones such as abscisic acid (ABA). The protocol is usually done within three to four days. It is a highly sensitive, specific and simple hormone in situ localization method, and is suitable for various plant tender organs and tissues. Related Articles | Metrics | Comments（0）

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Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (5): 0-.   Abstract （277）   HTML    PDF（pc） （490KB）（326）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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A Transformer-Based Model for Short-Term Landslide Displacement Prediction TIAN Yuan, PANG Xiao, ZHAO Wenyi, CHANG Xiaoyin, CHENG Chuyun, ZOU Pei, CAO Xiaocheng Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (2): 197-210.   DOI: 10.13209/j.0479-8023.2022.106 Abstract （798）   HTML    PDF（pc） （1474KB）（311）       Knowledge map    Save A Transformer-based short-term landslide displacement prediction model is proposed by combining temporal convolutional network (TCN) with a Transformer decoder. This model takes the preprocessed displacement and rainfall sequences as input and outputs the displacement predictions for the next three days in a time-series autoregressive manner. The experimental results show that the model achieves higher prediction accuracy than support vector machine (SVM) and long short-term memory (LSTM), and performs particularly well during predicting rapid deformation periods. At the same time, through the analysis of the attention mechanism of the model, it is found that the model focuses on the peak of displacements and heavy rainfalls, indicating that the model is reasonably reliable. Related Articles | Metrics | Comments（0）

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Late-Quaternary Activity of Tongdian-Madeng Basin Segment of Weixi-Qiaohou Fault CHANG Zufeng, LI Jianlin, CHANG Hao, LUO Lin, LIU Changwei, HE Shufang Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (5): 875-887.   DOI: 10.13209/j.0479-8023.2022.057 Abstract （363）   HTML    PDF（pc） （111524KB）（294）       Knowledge map    Save Based on the field survey results, the geological and geomorphic evidences of Late Quaternary activity and paleoseismic events in Tongdian-Madeng basin section of Weixi-Qiaohou fault are studied. The results show that the segment is active during Holocene and dominated by dextral strike slip. Its horizontal slip rate is 1.8-2.4 mm/a, and vertical slip rate is 0.30-0.35 mm/a since the Holocene. The OSL ages of faulted strata revealed by Yushuiping trench are 5.1±0.6, 5.3±0.2, 7.5±0.5 and 10.3±0.9 ka respectively, belonging to Holocene accumulation. Several faults developed on T2 terrace of a small river in Xiataiping offset all the strata under the modern loam layer, and the OSL age of the upper stratum is 5.3±0.6 ka. The activity of fault since Pliocene resulted in strong tectonic deformation of the Pliocene sediments, and its property also changed from thrust to dextral strike slip. Seismic phenomena such as seismic wedge, sand vein and soft sedimentary structural deformation are exposed at Xinmin, Gaichang and other trenches and the offset amount is mostly about 1 m. It is considered to be caused by the same seismic event, with an occurrence time of about 28000 aBP and a magnitude of seven. Related Articles | Metrics | Comments（0）

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Dynamic Analysis of Touchdown Impact for the Landing Gear of Reusable Launch Vehicle and Experimental Evidence YUAN Han, WANG Xiaojun, ZHANG Hongjian, MOU Yu, WANG Lei, WANG Chen Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (6): 977-988.   DOI: 10.13209/j.0479-8023.2022.084 Abstract （722）   HTML    PDF（pc） （3747KB）（294）       Knowledge map    Save In order to describe the lateral vibration of the landing gear caused by landing of launch vehicle, an equivalent model for the excitation of landing impact is proposed. In this model, the excitation is equivalent to the superposition of impact excitation and steady excitation. Secondly, the bending vibration modes of the landing gear are established by the assumed mode method, where the coupling term of the longitudinal deformation caused by transverse deformation is included in the expression of bending vibration. The dynamic response, excited by the landing impact, is solved by the mode superposition method, so as to obtain a semi-analytical solution for the problem. The real product experiments of vertical landing impact show that the proposed model is able to accurately describe the lateral vibration and maximum moment of the landing gear. Finally, we analyze how the parameters of the configuration and strength of materials affect the landing gear using the proposed model. The result can guide the parameter design of the landing gear in the engineering implementation. Related Articles | Metrics | Comments（0）

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Evaluation and Impact Factors of Spatial Supply and Demand of Public Sports Facilities in Shenzhen WU Jiansheng, QIAN Yun, WANG Hongliang, ZHU Huizhen, WANG Han Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (6): 1101-1110.   DOI: 10.13209/j.0479-8023.2022.088 Abstract （424）   HTML    PDF（pc） （1886KB）（293）       Knowledge map    Save From the perspective of 10-minute fitness circle, points of interest (POI), mobile signal data and other data were employed in this research. The accessibility of public sports facilities was measured with network analysis in GIS and Gini coefficient was used to analyze the equity of the supply and demand matching degree of public sports facilities in Shenzhen. The influencing factors of spatial supply and demand of public sports facilities were explored by geographical detectors. The results showed that, first, the overall accessibility of public sports facilities in Shenzhen was relatively high, which basically met the requirements of 10-minute fitness circle. Second, the distribution of public sports facilities was relatively fair. The distribution of facilities in different streets of the same municipal district was highly fair while the equity between municipal districts could be further improved. Third, the relationship between supply and demand in Yantian, Pingshan, Dapeng District was well-matched while sports facilities in the subdistrict at the junction of Futian District and Luohu District were centralized distributed, which set a limitation to the ability of service. Finally, land price was the most important factor affecting the spatial supply-demand relationship of public sports facilities in Shenzhen, followed by the density of road network and the number of bus stops. The total population and the proportion of man-made surface also had a certain impact on the supply and demand relationship. Related Articles | Metrics | Comments（0）

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A Hardware Accelerator for SSD Object Detection Algorithm Based on FPGA XIE Hao, CAO Jian, LI Pu, ZHAO Xiongbo, ZHANG Xing Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (6): 1015-1022.   DOI: 10.13209/j.0479-8023.2022.096 Abstract （737）   HTML    PDF（pc） （1316KB）（277）       Knowledge map    Save A hardware accelerator of object detection algorithm based on FPGA is designed to accelerate the computation of SSD object detection algorithm. Loop tiling and loop unrolling are used to optimize the loops of convolution and pooling, and can be re-configurated in any parallelism. In order to reduce data transmission time, feature maps are reorganized based on AXI, without any hardware resource overhead. After implementing the hardware accelerator to Xilinx ZCU development board, it can accelerate SSD at a performance of 534.72 GOPS, and the inference time is 113.81 ms. Related Articles | Metrics | Comments（0）

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Development and Validation of Avoidant Personality Organization Scale (AVPOS)  ZHANG Youwen, LI Jialu, ZHONG Jie Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (5): 959-966.   DOI: 10.13209/j.0479-8023.2022.080 Abstract （510）   HTML    PDF（pc） （745KB）（273）       Knowledge map    Save This article aims to develop Avoidant Personality Organization Scale (AVPOS) by using Diagnostic criteria for Avoidant Personality Disorder in Diagnostic and Statistical Manual of Mental Disorders-5 (DSM-5) as a basis and framework, integrating Kernberg’s Personality Organization theory, fully combining literature review and clinical experience, and investigating its reliability and validity. Sample 1 of 728 people (197 males and 531 females, average age 26.34±8.37 years) filled out the basic information questionnaire, Millon Clinical Multiaxial Inventory (MCMI) avoidance scale, and the initial version of AVPOS questionnaire to test the validity of the association between AVPOS and MCMI. Sample 2 of 709 people (160 males, 549 females, average age 19.34±1.23 years) filled out the basic information questionnaire, IPO, and the initial version of AVPOS questionnaire to test the validity of the association between AVPOS and IPO. Sample 3 of 65 people (13 males, 52 females) from sample 2 filled out the AVPOS again one month later to test the retest reliability of AVPOS. Sample 4 of 743 people (male 182, female 561, average age 22.76±6.86 years), from the half of the total sample (Sample 1 plus Sample 2), were used for exploratory factor analysis. Sample 5 of 694 (176 males, 518 females, average age 22.81±6.97 years), from the other half of the total sample, were used for confirmatory factor analysis. The results of factor analysis showed that the four-factor model was the best factor model for the AVPOS. The AVPOS was positively correlated with MCMI-III (r = 0.658, p<0.01) and IPO (r = 0.328, p<0.01). The AVPOS’s internal consistency coefficient was 0.786; the test-retest reliability of the total scale is 0.841. The results showed that the AVPOS meets the psychometric requirements. Related Articles | Metrics | Comments（0）

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Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (4): 0-.   Abstract （292）   HTML    PDF（pc） （2248KB）（264）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Reanalysis of the Marine Adaptation of the Archosaurian Qianosuchus mixtus from the Middle Triassic of Guizhou, China Cindy X. SU, ZHOU Min, GU Shulun, Ryosuke Motani, JIANG Dayong Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (6): 961-969.   DOI: 10.13209/j.0479-8023.2023.079 Abstract （357）   HTML    PDF（pc） （29422KB）（261）       Knowledge map    Save A reanalysis of marine adaptation of Qianosuchus mixtus is given by observing and making measurements to a new specimen. The marine adaptation in non-avian tetrapods follows a pattern of five steps (M1-M5). Comparation of the statistics of Qianosuchus mixtus and other clades leads to the result that Qianosuchus mixtus is placed in M2-3 and not considered to be completely marine. Observation and analysis of the morphology of the new specimen shows that its limbs do not exhibit characters of marine adaptation, yet its body shape and tail are morphologically adapted to undulatory or subundulatory swimming, similar to extant crocodiles and marine iguanas. Comparison with extant crocodiles and other clades suggest that despite having a specialized tail, Qianosuchus mixtus is not capable of swimming at high speed or for long distances. With the information above and reference to the habits of tetrapods in the Panxian Fauna, it is assumed that Qianosuchus mixtus possibly inhabits an intraplatform with islands, and that Qianosuchus mixtus and other upper trophic level predators exhibit complex ecology. Related Articles | Metrics | Comments（0）

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Recognition of Complex Entities in Weapons and Equipment Field YOU Xindong, GE Haojie, HAN Junmei, LI Yuxian, LÜ Xueqiang Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (3): 391-404.   DOI: 10.13209/j.0479-8023.2021.118 Abstract （885）   HTML    PDF（pc） （3577KB）（256）       Knowledge map    Save Aiming at the characteristics of complex entities in weapons and equipment field, a complex named entity recognition method is proposed which integrates multi-features and mounts the domain knowledge of weapons and equipment. First, we use the BERT model to pre-train on the weapon equipment field data to obtain the data vector, and use the Word2Vec model to learn context features of Zhengma, Wubi, Pinyin, and strokes to obtain the feature vector. Then the data vector and the feature vector are fused, the Bi-LSTM model is used for encoding, and the CRF decoder is used to obtain the tag sequence. Finally, the detection of complex entities on the label sequence is triggered to complete the recognition of complex named entities. In the experiments, we use the data collected from Global Military Network as the corpus, and analyze the recognition effect of different feature combinations and neural network models. A calculation method suitable for evaluating the recognition results of complex named entities is also proposed. The experimental results show that the F1-value of the proposed method for recognizing complex named entities of weapons and equipment with domain knowledge and fusion of multifeatures reaches 95.37%, which outperforms the existing methods. Related Articles | Metrics | Comments（0）

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Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (4): 0-.   Abstract （185）   HTML    PDF（pc） （2048KB）（253）       Knowledge map    Save Related Articles | Metrics | Comments（0）