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    Journal of East China Normal University(Natural Science)    2023, 2023 (6): 0-x.  
    Abstract94)   HTML13)    PDF (365KB)(1116)      
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    Recognition of classroom learning behaviors based on the fusion of human pose estimation and object detection
    Zejie WANG, Chaomin SHEN, Chun ZHAO, Xinmei LIU, Jie CHEN
    Journal of East China Normal University(Natural Science)    2022, 2022 (2): 55-66.   DOI: 10.3969/j.issn.1000-5641.2022.02.007
    Abstract1325)   HTML120)    PDF (1026KB)(1511)      

    As a result of ongoing advances in artificial intelligence technology, the potential for learning analysis in teaching evaluation and educational data mining is gradually being recognized. In classrooms, artificial intelligence technology can help to enable automated student behavior analysis, so that teachers can effectively and intuitively grasp students’ learning behavior engagement; the technology, moreover, can provide data to support subsequent improvements in learning design and implementation of teaching interventions. The main scope of the research is as follows: Construct a classroom student behavior dataset that provides a basis for subsequent research; Propose a behavior detection method and a set of feasible, high-precision behavior recognition models. Based on the global features of the human posture extracted from the Openpose algorithm and the local features of the interactive objects extracted by the YOLO v3 algorithm, student behavior can be identified and analyzed to help improve recognition accuracy; Improve the model structure, compress and optimize the model, and reduce the consumption of computing power and time. Four behaviors closely related to the state of learning engagement: listening, turning sideways, bowing, and raising hands are recognized. The accuracy of the detection and recognition method on the verification set achieves 95.45%. The recognition speed and accuracy of common behaviors, such as playing with mobile phones and writing, are greatly improved compared to the original model.

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    Comprehensive review on green synthesis of bio-based 2,5-furandicarboxylic acid
    Lei ZHAO, Zelin LI, Bolong LI, Shuchang BIAN, Jianhua WANG, Hailan ZHANG, Chen ZHAO
    Journal of East China Normal University(Natural Science)    2023, 2023 (1): 160-169.   DOI: 10.3969/j.issn.1000-5641.2023.01.016
    Abstract1578)   HTML82)    PDF (1090KB)(962)      

    Bio-based 2,5-furandicarboxylic acid (FDCA) is expected to partially replace petroleum-based terephthalic acid (PTA) for the synthesis of high-performance polymer materials. This review article summarizes the latest achievements on the various synthesis routes of FDCA from 5-hydroxymethylfurfural (HMF), furoic acid, furan, diglycolic acid, hexaric acid, 2,5-dimethylfuran, and 2-methylfuran. In particular, the direct oxidation, heterogeneous thermal catalytic oxidation, photoelectric catalytic oxidation of HMF and furoic acid carboxylation, disproportionation, carbonylation, and other routes to synthesize FDCA are reviewed in detail. Based on the comparative analysis of the advantages and disadvantages of each route, the HMF route and the furoic acid route are considered the most promising candidates for the large-scale production of FDCA. Further exploration and future research should be carried out to improve the catalytic production and separation efficiency of FDCA, simplify the reaction process, and reduce production wastes.

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    Study on the mechanism of methylene blue degradation by TiO2 photocatalyst
    ZHANG Dan, XU Bin, ZHU Pei-juan, LIAN Zheng-hao, ZHAO Ya-ping
    Journal of East China Normal University(Natural Sc    2013, 2013 (5): 35-42.  
    Abstract3571)      PDF (2193KB)(4087)      
    In order to carry out the study, the experiments of photodegradation of methylene blue under different conditions were conducted, using different kinds of free radical scavengers, such as (CH3)3OH, H2O2, KI, NaN3 and C6H4O2. The effects of these free radical scavengers were observed. The concentration of H2O2 generated during the photodegradation of methylene blue by TiO2 was also reported. And the results of these experiments indicated that the main active oxygen substances in the reaction are ·OH, O·-2 and 1O2.
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    Review of zeolite-confined subnanometric cluster catalysts
    Yue MA, Hao XU, Yueming LIU, Kun ZHANG, Peng WU, Mingyuan HE
    Journal of East China Normal University(Natural Science)    2023, 2023 (1): 82-94.   DOI: 10.3969/j.issn.1000-5641.2022.00.009
    Abstract590)   HTML26)    PDF (5085KB)(421)      

    The design of efficient and stable supported metal catalysts to prevent metal species from sintering into large nanoparticles under harsh preparation and reaction conditions is key for various important processes, including the conversion of C1 resources and dehydrogenation of low carbon alkanes to C2 and C3 olefins. Zeolites with uniform subnano micropores and various three-dimensional crystalline structures have been proven as ideal supports for preparing highly efficient and stable metal catalysts via encapsulating subnanometric metal clusters within their pores, cages, and channels. Interactions between metal clusters and the zeolite skeleton can regulate their geometric and electronic structure. The development of zeolite-confined subnanometric cluster catalysts aims to take advantage of this joint confinement effect and induce synergy between guest metal species and active sites in host zeolite frameworks. This can further improve the catalytic activity of resultant composite catalysts, for applications in multiple catalytic reaction processes . In this review, typical preparation methods of zeolite-confined subnanometric clusters and their catalytic applications in selective hydrogenation of CO2 and alkynes, hydrogen generation by formic acid decomposition and ammonia borane hydrolysis, and propane dehydrogenation to propene are discussed.

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    Application of Cu-based catalysts in the electroreduction of carbon dioxide
    Jing TANG, Zining ZHANG, Xiang ZHENG
    Journal of East China Normal University(Natural Science)    2023, 2023 (1): 149-159.   DOI: 10.3969/j.issn.1000-5641.2023.01.015
    Abstract801)   HTML32)    PDF (1081KB)(518)      

    To achieve the national strategy of carbon neutralization, the electroreduction of carbon dioxide into usable reagents via renewable energy has caused widespread concern in the scientific community. Cu-based electrocatalysts can reduce carbon dioxide to high value-added multi carbon products, but the catalytic mechanism still needs to be studied to improve its selectivity and efficiency. Depending on the state of the Cu, Cu-based catalysts can be divided into Cu alloy/composite catalysts, single-atom, oriented crystalline, and oxidized Cu-based catalysts. This paper introduced the common preparation methods, structural characteristics, effect of electro catalytic reduction of carbon dioxide, and possible catalytic mechanism of the four types of Cu-based catalysts mentioned above.

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    Catalytic asymmetric synthesis of chiral heterocyclic compounds with CO2 as the C1 synthon
    Zhipeng ZHAO, Ying SUN, Xiaotong GAO, Feng ZHOU
    Journal of East China Normal University(Natural Science)    2023, 2023 (1): 31-40.   DOI: 10.3969/j.issn.1000-5641.2023.01.004
    Abstract328)   HTML10)    PDF (1463KB)(427)      

    As the main component of greenhouse gases, CO2 represents an inexpensive and readily available renewable C1 synthon. In the past few decades, great efforts have been made toward the development of chemical processes that use CO2 as a promising fossil fuel alternative for C1 feedstocks for the production of industrially attractive chemicals. This could provide access to materials of commercial interest from an abundant, nontoxic, renewable, and low-cost carbon source, thus offering interesting opportunities for the chemical industry, organic synthesis, and so on. Considering the importance of chiral heterocycles in organic synthesis and drug development, the development of highly stereoselective and efficient catalytic asymmetric reactions using CO2 as a C1 synthon for these chiral heterocycles has received considerable attention. Successful examples for chiral lactones, carbonates, and carbamates have already been demonstrated. In this paper, we summarize the recent advances in this field.

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    Structure-conductive property relationship of polypyrrole
    YU Bo, XU Xue-cheng
    Journal of East China Normal University(Natural Sc    2014, 2014 (4): 77-87.  
    Abstract2295)      PDF (1700KB)(4127)      
    Polypyrrole was synthesized by oxidative chemical polymerization. Samples presenting different conductivities were obtained by adjusting the preparing temperature. The polypyrrole samples have been investigated by means of four probe method, Solid state 13C NMR spectrum, XRD, FTIR spectroscopy, Raman spectrum and XPS, respectively. The experimental result suggested the fact that the conductivity of polypyrrole samples gradually decreases as the preparation temperature increases. The analysis indicates it is because the changing of internal structure follows the varying of external preparation conditions. The commonly structure of polypyrrole is a linear chain of monomers bonded by α-α carbons at a low preparation temperature. Through such a structure polypyrrole can form both a relatively planar configuration and a relatively planar conformation. This sort of structure provides the sample with a preferable regularity, a longer conjugated chain length and a higher conductivity. However, the ratio of α-α linkage drops as the preparation temperature increases, by which the structure of molecular is damaged, the degree of order declines. The carrier mobility of polypyrrole, as well as the conductive property, became lower.
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    Joint extraction of entities and relations for domain knowledge graph
    Rui FU, Jianyu LI, Jiahui WANG, Kun YUE, Kuang HU
    Journal of East China Normal University(Natural Science)    2021, 2021 (5): 24-36.   DOI: 10.3969/j.issn.1000-5641.2021.05.003
    Abstract801)   HTML71)    PDF (842KB)(637)      

    Extraction of entities and relationships from text data is used to construct and update domain knowledge graphs. In this paper, we propose a method to jointly extract entities and relations by incorporating the concept of active learning; the proposed method addresses problems related to the overlap of vertical domain data and the lack of labeled samples in financial technology domain text data using the traditional approach. First, we select informative samples incrementally as training data sets. Next, we transform the exercise of joint extraction of entities and relations into a sequence labeling problem by labelling the main entities. Finally, we fulfill the joint extraction using the improved BERT-BiGRU-CRF model for construction of a knowledge graph, and thus facilitate financial analysis, investment, and transaction operations based on domain knowledge, thereby reducing investment risks. Experimental results with finance text data shows the effectiveness of our proposed method and verifies that the method can be successfully used to construct financial knowledge graphs.

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    JIANG Dong-Xing, FU Xiao-Long, YUAN Fang, WU Hai-Yan, LIU Qi-Xin
    Journal of East China Normal University(Natural Sc    2015, 2015 (S1): 119-125.   DOI: 10.3969/j.issn.1000-5641.2015.z1.020
    Abstract1728)      PDF (984KB)(4527)      
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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
    Journal of East China Normal University(Natural Science)    2022, 2022 (1): 31-42.   DOI: 10.3969/j.issn.1000-5641.2022.01.005
    Abstract363)   HTML49)    PDF (942KB)(751)      

    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
    Journal of East China Normal University(Natural Science)    2022, 2022 (1): 43-51.   DOI: 10.3969/j.issn.1000-5641.2022.01.006
    Abstract618)   HTML49)    PDF (973KB)(805)      

    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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    Survey of early time series classification methods
    Mengchen YANG, Xudong CHEN, Peng CAI, Lyu NI
    Journal of East China Normal University(Natural Science)    2021, 2021 (5): 115-133.   DOI: 10.3969/j.issn.1000-5641.2021.05.011
    Abstract898)   HTML419)    PDF (1503KB)(827)      

    With the increasing popularity of sensors, time-series data have attracted significant attention. Early time series classification (ETSC) aims to classify time-series data with the highest level of accuracy and smallest possible size. ETSC, in particular, plays a critical role in fintech. First, this paper summarizes the common classifiers for time-series data and reviews the current research progress on minimum prediction length-based, shapelet-based, and model-based ETSC frameworks. There are pivotal technologies, advantages, and disadvantages of the representative ETSC methods in separate frameworks. Next, we review public time-series datasets in fintech and commonly used performance evaluation criteria. Lastly, we explore future research directions pertinent to ETSC.

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    Trade between Poland and China within the Belt and Road Initiative and 17 + 1 Framework: Opportunity and challenge
    Natalia BORUCZKOWSKA, Yuna DI
    Journal of East China Normal University(Natural Science)    2020, 2020 (S1): 188-192.   DOI: 10.3969/j.issn.1000-5641.202092324
    Online available: 22 January 2021

    Abstract464)   HTML43)    PDF (433KB)(2175)      
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    The 21st century Maritime Silk Road and the role of Myanmar
    Khin Kyi TUN, Zaisheng XIANG
    Journal of East China Normal University(Natural Science)    2020, 2020 (S1): 1-5.   DOI: 10.3969/j.issn.1000-5641.202092101
    Online available: 22 January 2021

    Abstract329)   HTML66)    PDF (282KB)(1020)      
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    Research progress in Chinese named entity recognition in the financial field
    Qiurong XU, Peng ZHU, Yifeng LUO, Qiwen DONG
    Journal of East China Normal University(Natural Science)    2021, 2021 (5): 1-13.   DOI: 10.3969/j.issn.1000-5641.2021.05.001
    Abstract1116)   HTML659)    PDF (821KB)(533)      

    As one of the basic components of natural language processing, named entity recognition (NER) has been an active area of research both domestically in China and abroad. With the rapid development of financial applications, Chinese NER has improved over time and been applied successfully throughout the financial industry. This paper provides a summary of the current state of research and future development trends for Chinese NER methods in the financial field. Firstly, the paper introduces concepts related to NER and the characteristics of Chinese NER in the financial field. Then, based on the development process, the paper provides an overview of detailed characteristics and typical models for dictionary and rule-based methods, statistical machine learning-based methods, and deep learning-based methods. Next, the paper summarizes public data collection tools, evaluation methods, and applications of Chinese NER in the financial industry. Finally, the paper explores current challenges and future development trends.

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    Application of BD RDSS for marine data transmission
    HE Si-long, YE Fang-zhou, WANG Yuan-fei
    Journal of East China Normal University(Natural Sc    2014, 2014 (4): 173-179.  
    Abstract1496)      PDF (998KB)(2136)      
    The ocean is always one of the biggest blind spot of traditional communication technologies. Because of lack of effective means of communication, resulting in information communication difficulties between ship and shore, highly informatization of offshore marine engineering ships have become floating “information islands” in the sea. Beidou Satellite Navigation System has integrated navigation and communication, which has provided a feasible technology way to solve the
     Vessel-Shore Integration. This paper proposed a Beidou cluster data transmission technology solution based on short message communication principle of Beidou RDSS (radio determination satellite Service), which solves the problem of large amount of data transmission for marine engineering ships. The software can transmit thousands of physical quantity containing ship machine state data, construction condition data, position information to shore command center in real-time through the development of the communication protocol, the establishment of an effective algorithm of data processing and compression algorithms, which realizes the Vessel-Shore Integration of offshore operations and provides an information technology security for the ship scheduling of production and business management.
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    The development and application of a physical-biogeochemical coupling model based on FVCOM
    SHI Shenyang, GE Jianzhong, CHEN Jianzhong, ZHENG Xiaoqin, DING Pingxing
    Journal of East China Normal University(Natural Science)    2020, 2020 (3): 55-67.   DOI: 10.3969/j.issn.1000-5641.201941008
    Abstract609)   HTML160)    PDF (1395KB)(502)      
    By combining the hydrodynamic model FVCOM with the biological model ERSEM, based on FABM, this paper develops a new physical-biogeochemical model: FVCOM-FABM-ERSEM. The combined model is suitable for application to coastal areas and is one of the most comprehensive ecosystem models for the lower trophic levels of the marine food-web. Using the combined model, a one-dimensional vertical (1DV) model and a three-dimensional Changjiang Estuary model were established. The results of the 1DV model were consistent with observation data from the European L4 Station. This paper also simulates the physical and biogeochemical processes of Changjiang Estuary from 2013 to 2016 with the 3D Changjiang Estuary model. The distribution of temperature, salinity, nitrate, phosphate, and chlorophyll-a levels were all found to be consistent with observation data from cruises and MODIS data in the spring when algal blooms occur. The characteristics of the front dynamics of Changjiang Estuary were well represented. The relationship between salinity, turbidity, nutrients, and chlorophyll around the plume front was determined through modeling, indicating a significant co-occurrence effect along the front of physical and biological processes.
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    What can the Maritime Silk Road learn from the rise and fall of the Songhai Empire?
    Ibrahim KONE
    Journal of East China Normal University(Natural Science)    2020, 2020 (S1): 24-26, 43.   DOI: 10.3969/j.issn.1000-5641.202092105
    Online available: 22 January 2021

    Abstract504)   HTML40)    PDF (333KB)(403)      
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    Resonant modes and peak gain analysis of LLC resonant converter
    ZHANG Li-Sheng
    Journal of East China Normal University(Natural Sc    2015, 2015 (1): 203-211.   DOI: 10.3969/j.issn.1000-5641.2015.01.025
    Abstract1958)      PDF (944KB)(2067)      
    LLC resonant converter has outstanding advantages in high power conversion efficiency and wide range adaptability of input voltage, but research on the peak gain is clearly insufficient. Therefore, the peak gain of LLC resonant converter is studied. According to the operation process of the series-parallel resonance, the converter can be divided into three resonant modes: inadequate resonant mode, complete resonant mode and over resonant mode. When the converter operates in complete resonant mode, it reaches its maximum value, and the corresponding switching frequency is named critical frequency. Finally, derivation of time-domain expression of the peak gain and the critical frequency is completed through the establishment of the converter state equations, and the accuracy of theoretical analysis is verified through simulation and experiment.
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