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    25 January 2022, Volume 2022 Issue 1 Previous Issue    Next Issue
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    Mathematics
    Stability of the solution to a singularly perturbed semilinear second-order differential equation with discontinuous right-hand side
    Aleksei LIUBAVIN, Mingkang NI
    2022, 2022 (1):  1-9.  doi: 10.3969/j.issn.1000-5641.2022.01.001
    Abstract ( 170 )   HTML ( 1042 )   PDF (428KB) ( 127 )   Save

    In this paper, a stationary problem for the reaction-diffusion equation with a discontinuous right-hand side is considered. Based on ideas from contrast structure theory, the asymptotic representations for eigenvalues and eigenfunctions are constructed by solving a Sturm-Liouville problem and an estimation of the remainder is obtained. Moreover, a sufficient condition which guarantees the stability of the solution to this task is established.

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    Neighbor sum distinguishing total choice number of graphs with bounded maximum average degree
    Donghan ZHANG
    2022, 2022 (1):  10-16.  doi: 10.3969/j.issn.1000-5641.2022.01.002
    Abstract ( 140 )   HTML ( 1171 )   PDF (640KB) ( 62 )   Save

    This paper explores the neighbor sum distinguishing list total coloring of graphs $G$ with maximum degree $\varDelta \left( G \right) \geqslant 8$ and maximum average degree ${\rm{mad}}\left( G \right) < \frac{{14}}{3}$ . By applications of the Combinatorial Nullstellensatz and discharge method, moreover, it is shown that the neighbor sum distinguishing total choice number of the graphs does not exceed $\varDelta \left( G \right) + 3$ .

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    The decycling number of join graphs
    Hongbo YE, Chao YANG, Fuxiang CUI
    2022, 2022 (1):  17-21.  doi: 10.3969/j.issn.1000-5641.2022.01.003
    Abstract ( 145 )   HTML ( 839 )   PDF (2052KB) ( 57 )   Save

    Let $G = (V, E)$ be a simple graph. For any vertex set $S$ of V, if $G - S$ is acyclic, then $S$ is a decycling set of G; the minimum size of a decyling set is called the decycling number of G, denoted by $\phi \left( G \right)$ . In this paper, we consider the decycling problem of join graphs and obtain the exact value for the decycling number of some types of join graphs. Let ${G_m}$ and ${G_n}$ be simple connected graphs of the order m and n, respectively. Then the decycling number of the join graph ${G_m} \vee {G_n}$ satisfies: $\min \{ m,n\} \leqslant \phi ({G_m} \vee {G_n}) \leqslant $ $ \min \{ m + \phi ({G_n}),n + \phi ({G_m})\}$ . The results presented in this paper confirm that the upper bound for the above inequality is tight. In particular, if ${G_m}$ and ${G_n}$ are trees, then we can obtain the exact value for the decycling number of ${G_m} \vee {G_n}$ .

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    Phisics and Electronic Science
    Yolk-shell silicon anode material coated with nitrogen-doped carbon
    Kaijing BAO, Zhaokai ZHANG, Xianqing PIAO, Zhuo SUN
    2022, 2022 (1):  22-30.  doi: 10.3969/j.issn.1000-5641.2022.01.004
    Abstract ( 191 )   HTML ( 202 )   PDF (1375KB) ( 87 )   Save

    Using resorcinol-formaldehyde resin as the carbon source, melamine as the nitrogen source, and NaOH as the etchant, a nitrogen-doped carbon-coated silicon (Si@void@N-C) anode material with a yolk-shell structure was synthesized. The samples were characterized and tested by XRD, SEM and X-ray photoelectron spectroscopy, TEM, and electrochemical tests; the results confirmed that a Si@void@NC composite anode material with a yolk-shell structure was successfully synthesized. The material was found to have excellent electrochemical performance. The initial capacity reached 1282.3 mA/g after charging and discharging at a current density of 0.1 A/g. After 100 cycles, its specific capacity was as high as 994.2 mAh/g with a capacity retention of 77.5%, demonstrating good cycle performance. The nitrogen-doped carbon shell of the Si@void@N-C material helps with the electrical conductivity of the composite material. Meanwhile, the yolk-shell structure effectively alleviates the volume effect of silicon; this feature is beneficial to the formation of a stable SEI film and improves the cycle stability of the battery.

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    Study of electronic structures and the micro-solvation effect of SO3 and HSO3 in atmospheric aerosols
    Jianan CHEN, Zhipeng LI, Yanrong JIANG, Zhubin HU, Haitao SUN, Zhenrong SUN
    2022, 2022 (1):  31-42.  doi: 10.3969/j.issn.1000-5641.2022.01.005
    Abstract ( 133 )   HTML ( 37 )   PDF (942KB) ( 137 )   Save

    In this study, we used negative ion photoelectron spectroscopy (NIPES) combined with quantum chemical calculation to explore the electronic structures, micro-solvation effect, and stabilization mechanism of two compounds, SO3 and HSO3, that are readily abundant in the atmosphere. Vertical detachment energies of (3.31 ± 0.02) and (3.91 ± 0.02) eV and adiabatic detachment energies of (3.02 ± 0.05) and (3.56 ± 0.05) eV were measured for SO3 and HSO3, respectively. These results are reproduceable when using a nuclear ensemble approach and Dyson orbitals in the calculation. The typical density of states method, however, cannot demonstrate the nuclear vibration effect, ionization probability, and orbital relaxation effect during the ionization process. We studied the micro-solvation effect of HSO3·(H2O)n (n = 0 ~ 5) and found that system stability was enhanced by an increase in the surrounding water molecules, whereby electrostatic interaction played a dominant role and the induction effect made an increasingly important contribution. We believe this work will help improve the modeling of atmospheric sulfate aerosols and provide a scientific basis for the effective control of haze formation.

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    Preparation and characterization of Ag@Au bimetallic nanoparticles
    Tianchen ZHAO, Xiaolei ZHANG, Shitao LOU
    2022, 2022 (1):  43-51.  doi: 10.3969/j.issn.1000-5641.2022.01.006
    Abstract ( 151 )   HTML ( 39 )   PDF (973KB) ( 90 )   Save

    Ag nanoparticles were first prepared using a seed-based thermal synthetic procedure. The monometallic particles were then transformed into bimetallic particles via a galvanic replacement reaction. A transmission electron microscope (TEM), scanning transmission electron microscope (STEM), and absorption spectrum were subsequently used for characterization. By controlling the amount of seed added, the ultrasonic exposure, and the centrifugal time, we can effectively tune the size of the particles and the localized surface plasmon resonance peak positions. The TDBC film can be wrapped on the surface of the metallic nanostructures by a ligand exchange reaction to achieve strong coupling between surface plasmon and molecular excitons.

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    Effect of silicon/carbon composite structure on its electrochemical performance as a lithium-ion battery anode
    Xiaohua TIAN, Chenlu YU, Han ZHENG, Zhuo SUN, Zhejuan ZHANG, Xianqing PIAO
    2022, 2022 (1):  52-61.  doi: 10.3969/j.issn.1000-5641.2022.01.007
    Abstract ( 200 )   HTML ( 42 )   PDF (1541KB) ( 126 )   Save

    Porous silicon/hard carbon composite (Si@CTS) was successfully fabricated using liquidphase encapsulation and a low-temperature pyrolysis process, in which silicon particles from cutting waste in the manufacturing of crystalline silicon solar cells was used as a raw material and chitosan as carbon source. In this paper, the electrochemical performance of Si@CTS and a mixture of Si@CTS and graphite (Si@CTS/G) as anode materials of a lithium-ion battery was studied. The Si@CTS electrode showed a high discharge specific capacity of 1672.8 mAh/g and a high initial coulombic efficiency of 84.45%. After 100 cycles, the Si@CTS retained a reversible capacity of 626.4 mAh/g. The discharge specific capacity of the Si@CTS/G composite was 698.1 mAh/g; hence, the discharge specific capacity of the Si@CTS/G composite was higher than that of Si@CTS and offered better stability. The findings are critical for mass manufacture and deployment of silicon/carbon anodes with high capacity and stability in lithium-ion batteries.

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    Life Sciences
    New records of liverwort species in Zhejiang Province
    Ruiping SHI, Shichen XING, Xia TANG, Shuwen TU, Youfang WANG, Jian WANG
    2022, 2022 (1):  62-69.  doi: 10.3969/j.issn.1000-5641.2022.01.008
    Abstract ( 150 )   HTML ( 38 )   PDF (783KB) ( 80 )   Save

    To better understand the diversity of bryophytes in East China, bryophytes were systematically investigated and collected in the Huangshan - Tianmu Mountain range and Xianxia - Wuyi Mountain range in the region. In the course of field investigation, eighteen new records of liverwort species were found in Zhejiang Province, belonging to 10 families and 13 genera, respectively. Notably, Hattoria is a new genus record for Zhejiang Province. In this paper, the habitats, geographical distributions, and main identifying features of these new records are provided. Moreover, illustrations of rare and endemic liverwort species in China are presented. These new findings further enrich the bryophyte flora of Zhejiang Province and provide new basic information about the flora of the province.

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    Two new records of epiphyllous Cheilolejeunea species recorded in Zhejiang Province
    Shichen XING, Zun DAI, Xing CHEN, Jian WANG
    2022, 2022 (1):  70-75.  doi: 10.3969/j.issn.1000-5641.2022.01.009
    Abstract ( 141 )   HTML ( 37 )   PDF (805KB) ( 53 )   Save

    Two epiphyllous species, namely Cheilolejeunea chenii and C. obtusilobula, were newly recorded in Zhejiang Province. The specimens were collected from Gaoshanwan Village, Yushang Township, Qingyuan County, Zhejiang Province. It is worth noting that C. chenii has a very narrow distribution range in China and is a particularly rare species that should be protected as soon as possible. In this paper, the morphological characteristics, distribution, and habitats of the two species are briefly described and discussed. Given that the two species are not currently within the protection scope of the nature reserve, we also propose new ideas for in-situ conservation of epiphyllous liverworts.

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    Bryophyte diversity of a grassland mining area and its relationship with soil physical and chemical properties
    Chao FENG, Yuchen GAN, Xiao HE, Shaogang LEI, Wei CHENG, Jiu HUANG, Jin KOU
    2022, 2022 (1):  76-84.  doi: 10.3969/j.issn.1000-5641.2022.01.010
    Abstract ( 182 )   HTML ( 37 )   PDF (797KB) ( 78 )   Save

    In this study, the Shengli Coal Mine—a representative coal mine in the semi-arid grassland of Inner Mongolia—and the adjacent Beizi Temple, Botanical Garden, and Nanshan Reservoir were selected as the study areas. By studying the correlation between the characteristics of the bryophyte community and the physical and chemical properties of the soil, the influence of soil on the distribution of bryophytes was analyzed during the reclamation process. The results showed that there were 4 families, 6 genera, and 7 species of bryophytes in the Shengli mining area. The total coverage of bryophytes in each habitat could be ranked according to the following order: Beizi Temple > Botanical Garden > south dump of the mining area > Nanshan Reservoir > plantation in the mining area > north dump of the mining area. An analysis of the diversity index, moreover, showed that the Shannon-Wiener index at the south dump was the highest, indicating that the species complexity of the moss community at the south dump was relatively high. An analysis of the correlation between the coverage of the bryophyte community and the physical and chemical properties of the soil showed that the soil pH value, silt content, sand content, and gravel content all had significant effects on the distribution of bryophytes. Multivariate analysis of the bryophyte community structure and soil physical and chemical properties showed that the differences in bryophyte community structure between different study areas was related to the cumulative influence of environmental factors.

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    Geography
    Spatial accessibility of elderly healthcare facilities based on an improved potential model: A case study on Fengxian District in Shanghai
    Tianyan WU, Qingtao XIA, Zhen CHEN
    2022, 2022 (1):  85-96.  doi: 10.3969/j.issn.1000-5641.2022.01.011
    Abstract ( 171 )   HTML ( 39 )   PDF (1193KB) ( 67 )   Save

    Spatial accessibility is an important reference index to determine whether the layout of various types of facilities is reasonable. Scientific evaluation of the spatial accessibility of service facilities is an important basis for judging regional service differences and optimizing the spatial allocation of resources. Using the basic potential model as a basis for our analysis, we introduced a demand-side threshold, designed a three-level service radius based on the scale requirements for elderly care institutions, and implemented regional priority matching principles. Taking Fengxian District of Shanghai as an example, we analyzed the spatial accessibility of elderly care institutions in the region based on the actual driving time between supply and demand points and ArcGIS spatial analysis technology. The results show that the spatial accessibility of nursing homes in Fengxian District is uneven, and the spatial accessibility in some areas of Nanqiao Town, Zhuanghang Town, and Jinhui Town is significantly higher. A trend of gradually decreasing accessibility can be observed from the city center to the periphery. In some towns and villages of the central region, there are dense elderly care institutions and relatively concentrated elderly resources. The improved potential model considers the influence of factors such as the service capacity of elderly care institutions and the needs of the elderly, which can evaluate the spatial accessibility of institutions more effectively. The research results provide a reference point and offer suggestions for scientific planning and decision-making of elderly care institutions.

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    Effect of compulsory education school quality on housing prices from a spatial perspective
    Hui YANG, Jin ZENG, Nai YANG, Fanmin KONG
    2022, 2022 (1):  97-108.  doi: 10.3969/j.issn.1000-5641.2022.01.012
    Abstract ( 120 )   HTML ( 30 )   PDF (2662KB) ( 37 )   Save

    In this study, we used the geographic weighted regression (GWR) method to explore the impact of compulsory education quality on housing prices. For the purpose of this analysis, we considered Wuhan in Hubei Province as the study area and collected school and housing price data from websites such as Sofang.com, Jzb.com, Whjyj.gov.cn, etc. We also used the inverse distance weighted (IDW) method for visual analysis. The results showed that: ① The quality of compulsory education has a positive impact on housing prices, and provincial demonstration schools, in particular, create a relatively high price premium on housing prices; ② The capitalization effect of the quality of junior high school is higher than that of elementary school; ③ The quality of primary and junior high school education in new urban areas has the greatest impact on housing prices. The quality of the combination of primary and junior high schools in the central and northern areas of Jiangan District had a significant impact on housing prices, while the quality of schools in the Wuchang, Qiaokou, and Jianghan districts had relatively less impact on housing prices as a whole.

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    Research on the evolution of the spatiotemporal pattern of China’s automobile parts supply network
    Dalong FAN, Weidong CAO, Xuewei WANG
    2022, 2022 (1):  109-121.  doi: 10.3969/j.issn.1000-5641.2022.01.013
    Abstract ( 126 )   HTML ( 26 )   PDF (3483KB) ( 64 )   Save

    A supply network is an important carrier for the spatial flow of industrial elements, and its structure and evolution can reflect the spatial clustering characteristics of related industries. In this study, we used thermal analysis, network analysis, and other methods to understand and analyze China’s automobile parts supply network at the national and regional levels in 2009, 2014, and 2019; in addition, we explored the evolution of spatiotemporal pattern characteristics of the network’s structure. The study found that: ① Automobile parts companies are primarily distributed across the eastern part of China, followed by the central and western regions. The companies form six clusters centered on the Yangtze River Delta region, Beijing-Tianjin-Hebei region, Northeast region, Pearl River Delta region, Central China region, and Chengdu-Chongqing region. ② The density of the network continues to increase. In 2019, the network density reached 0.5017, showing strong connectivity. Changchun had the highest extroversion in 2009, and Wuhan had the highest in 2014 and 2019. Shanghai has always maintained the highest introversion and continues to increase. More than 50% of the top ten cities are located in the Yangtze River Delta, and the remaining cities are located in the Beijing-Tianjin-Hebei, Northeast, Chengdu-Chongqing, and Central China regions. In addition, the automobile parts supply network has obvious hierarchical characteristics. The first-level links included Shanghai-Changchun in 2009, Shanghai-Changchun and Shiyan-Wuhan in 2014, and Shanghai-Changchun and Shanghai-Wuhan in 2019. ③ If we analyze the spatiotemporal characteristics of the supply network of China’s six major clusters with OEMs and automobile parts factories as nodes, we find that the Northeast region forms a vehicle-parts concentric inward supply network structure, the Yangtze River Delta and Chengdu-Chongqing regions form vehicle-parts concentric outbound supply network structures, the Beijing-Tianjin-Hebei and Pearl River Delta regions form vehicle-parts eccentric outbound supply network structures, and Central China forms a vehicle-parts eccentric inward supply network structure.

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    Quick estimation of three-dimensional vegetation volume based on images from an unmanned aerial vehicle: A case study on Shanghai Botanical Garden
    Jiabei LUO, Yingfei ZHOU, Hanbing LENG, Chen MENG, Zhengyang HOU, Tongtong SONG, Zhengyun HU, Chao ZHANG, Shucheng FENG
    2022, 2022 (1):  122-134.  doi: 10.3969/j.issn.1000-5641.2022.01.014
    Abstract ( 130 )   HTML ( 30 )   PDF (1265KB) ( 77 )   Save

    Three-dimensional vegetation volume is a comprehensive index that can be used to represent the ecological benefits of urban vegetation. However, the challenge of how to accurately and quickly carry out three-dimensional vegetation volume monitoring in highly heterogeneous urban habitats is an urgent problem that requires attention. In this paper, we used Shanghai Botanical Garden as a case study. We acquired low-altitude, high-resolution images of Shanghai Botanical Garden through a UAV aerial photography system; after extracting the data, we calculated the surface elevation and canopy height models, estimated the three-dimensional vegetation volume, and analyzed the spatial distribution pattern. The results showed that: ① The overall plane and elevation accuracy of UAV images was better than 0.1 m, and the average error and standard deviation of the canopy height model accuracy was 0.27 m and 0.58 m, respectively. ② The vegetation volume of Shanghai Botanical Garden was distributed in a pattern from northeast low to southwest high, with a total vegetation volume of 3538944.50 m3. The average green density of the botanical garden was 6.51 m3/m2. The three gardens with the highest vegetation volume were: Peony Garden (289491.00 m3), Pinetum Garden (338322.10 m3), and the Green Space Attached to The Greenhouse (360587.50 m3). The three gardens with the lowest vegetation volume were: Recreational Green Space (24761.50 m3), Monocotyledon Botanical Garden (31621.40 m3), and Rose Garden (74607.30 m3). The three gardens with the highest vegetation volume density were: Tropical Orchid Room (9.23 m3/m2), Fern Garden (11.30 m3/m2), and Magnolia and Camphor Avenue (13.11 m3/m2). The three gardens with the lowest vegetation volume density were Recreational Green Space (1.57 m3/m2), Scientific Research Center Green Space (1.81 m3/m2), and Rose Garden (2.58 m3/m2). ③ The vegetation volume of each specialized garden was significantly related to the distribution area of the arbor community, the height of the constructive species, and the product thereof. The vegetation volume density of each specialized garden was significantly related to the proportion of the area of the arbor community in the specialized garden, the height of the constructive species, and the product thereof. This research can serve as a methodology reference for the quick estimation of urban vegetation volume, and provide basic data vegetation volume estimates and spatial pattern optimization for Shanghai Botanical Garden.

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    Remote sensing inversion and time-series analysis of critical parameters for eutrophication assessment of urban waters in Shanghai
    Jiahao LI, Bo TIAN, Fang CAO, Yuekai HU, Yuanqiang DUAN, Zehao XIE, Ya PENG, Wenhao JIANG, Huifang FAN
    2022, 2022 (1):  135-147.  doi: 10.3969/j.issn.1000-5641.2022.01.015
    Abstract ( 148 )   HTML ( 31 )   PDF (6823KB) ( 95 )   Save

    Estuarine cities are heavily influenced by anthropogenic activities. In turn, their water bodies often face serious eutrophication and pollution problems, thereby exerting significant pressure on the urban production and living environment. This study focuses on the water bodies in the city of Shanghai, an important estuarine megacity in China. Using the Sentinel-2 satellite and in situ measured water spectrum data, we built an inversion model for rapid identification of two critical parameters for eutrophication assessment, namely chlorophyll-a concentration and turbidity. We subsequently analyzed the spatial and temporal variability of these two parameters using time-series satellite data. Our results showed that the correlation coefficient (R2) of turbidity and chlorophyll-a concentration inversion based on remote sensing was 0.95 and 0.87, respectively; the root mean square error (RMSE) was 4.33 μg/L and 8.93 NTU, respectively. Time-series analysis from 2019 showed that both chlorophyll-a concentration and turbidity in different urban water bodies were highest in the summer and lowest in the winter in Shanghai. Specifically, chlorophyll-a concentrations across water bodies decreased in the following sequence: aqua-culture/planting ponds, permanent freshwater lakes, reservoir ponds, permanent rivers, and canals/transportation rivers. In the case of turbidity, the water bodies ordered from highest to the lowest followed the sequence: aqua-culture/planting ponds, permanent rivers, canals/water delivery rivers, permanent freshwater lakes, and reservoir ponds. Time series analysis of chlorophyll-a concentrations and turbidity from 2019 showed that in water bodies with less human disturbance, the correlation between chlorophyll-a concentration and turbidity was stronger than those that were heavily influenced by anthropogenic activities. The use of Sentinel-2 satellite images to retrieve the chlorophyll-a concentration and turbidity in water bodies can generally provide information on the eutrophication status of water bodies in Shanghai; the data, moreover, can serve as a reference for aquatic environmental monitoring of inland water bodies in other cities.

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    The basis of late Pleistocene activity at the Tianzhuang fault in Taiyuan, Shanxi Province
    Xiaofei HAN, Yanlin DU, Jianxi JIA, Bin DONG, Shuangshuang SHI
    2022, 2022 (1):  148-158.  doi: 10.3969/j.issn.1000-5641.2022.01.016
    Abstract ( 95 )   HTML ( 30 )   PDF (17842KB) ( 23 )   Save

    In this paper, the presence of the Tianzhuang fault was confirmed using a combination of petroleum geophysical exploration, geology, remote sensing, and other data. The study concluded that the fault originated from the west of Tiancun, Jinyuan District, Taiyuan City with a total length of about 35 km from Houjiazhai to Tianzhuang. The fault trends from west to east with the pattern EW-NEE-NE, and tends to the SE as a high-angle normal fault. The Tianzhuang fault is a concealed fault associated with the piedmont fault of the East and West Mountains of the Taiyuan Basin. Through the joint drilling exploration across the Tianzhuang fault, near the Ma Lianying Road, there were three distinct sedimentary cycles of river lake swamp facies found in the strata: in the 80 ~ 60 m section, the sedimentary environment tends to frequent gradually, and the sedimentary facies is lake→swamp; in the 60 ~ 30 m section, the sedimentary environment tends to be stable and frequent twice, and the sedimentary facies is river→swamp→river→lake→swamp→river; in the 30 ~ 0 m section, the sedimentary environment tends to be stable gradually, and the sedimentary facies is swamp→lake→swamp. The Quaternary strata in the site gradually thickens from north to south in the horizontal direction, and the coarse-grained deposits become thinner. There is a magnitude change in the borehole, ZK3←→ZK4←→ZK7, and the first layer is thick in the vertical direction. Particle deposition occurs at 20 ~ 30 m, and the floating is not large; the sedimentation cycle number is roughly “M” from deep to shallow, and the sedimentation number reaches a peak at 30 ~ 40 m and 50 ~ 60 m. From the perspective of detecting the strata, all the boreholes in the silty layer of the Holocene boundary were exposed, and the depth was relatively small. It is believed that the sampling rate of the bored sand layer is not the same and hence it is expected that the fault of the Tianzhuang fault is not broken. There are three primary sets of fault-breaking strata in the Tianzhuang fault, all of which are from the Late Pleistocene strata; these did not penetrate the Upper Pleistocene, and thus the target fault was determined to be the late Pleistocene active fault. From top to bottom, the offset of faulted strata increases gradually: 0.4 m, 3.5 m, and 7.2 m, in turn. There are two coseismic displacements of about 3 meters in the exposed depth of the borehole, which can be used to judge the occurrence of two main dislocation events in the identified layer. This provides reliable geological evidence for analyzing the seismic risk of the Tianzhuang fault.

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