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    Journal of East China Normal University(Natural Science)    2020, 2020 (3): 0-0.  
    Abstract100)      PDF (311KB)(60)      
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    Trade: Hard or soft infrastructure? China’s Maritime Silk Road Initiative and what it means for Kenya
    Asenath MAOBE
    Journal of East China Normal University(Natural Science)    2020, 2020 (S1): 179-183.   DOI: 10.3969/j.issn.1000-5641.202092321
    Online available: 22 January 2021

    Abstract92)   HTML7)    PDF (344KB)(96)      
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    Historical overview of hypoxia in the Bay of Bengal
    Md Jaker HOSSAIN, Aftab Uddin SHEIKH, Jing ZHANG
    Journal of East China Normal University(Natural Science)    2020, 2020 (S1): 109-113.   DOI: 10.3969/j.issn.1000-5641.202092218
    Online available: 22 January 2021

    Abstract41)   HTML9)    PDF (497KB)(15)      
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    Asymptotic properties of a class of delay differential equations with a sub-linear neutral term
    Zhongyue HAN, Yuanhong YU
    Journal of East China Normal University(Natural Science)    2021, 2021 (1): 1-7.   DOI: 10.3969/j.issn.1000-5641.201911020
    Abstract38)   HTML160)    PDF (652KB)(25)      

    This paper studies the oscillation and asymptotic properties of delay differential equations with damping and sub-linear neutral terms using the generalized Riccati transformation technique and the mean value theorem. After analyzing the function of the cross-link between the condition $\int^\infty_{t_0}(\frac{1}{R(t)})^{\frac{1}{\gamma}}{\rm{d}}t=\infty$ and the relationship of parameters $\gamma$ and $\beta$ in the differential equations oscillation, the sufficient conditions for the existence of vibration solutions are provided to extend the existing results in the cited literature. Lastly, some applications are given to illustrate the significance of these results.

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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

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    Journal of East China Normal University(Natural Science)    2021, 2021 (1): 0-0.  
    Abstract32)      PDF (359KB)(8)      
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    Building a community for a shared future: The 21st Century Maritime Silk Road and its impact on the economic, security, and environmental global governance of oceans and seas— The case of the Gulf of Guinea
    Godfred Sowah KHARTEY
    Journal of East China Normal University(Natural Science)    2020, 2020 (S1): 48-52.   DOI: 10.3969/j.issn.1000-5641.202092113
    Online available: 22 January 2021

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    Asymptotic behavior of solutions for the non-autonomous classical reaction-diffusion equation with nonlinear boundary conditions and fading memory
    Yuting LIANG, Xuan WANG
    Journal of East China Normal University(Natural Science)    2021, 2021 (1): 16-27.   DOI: 10.3969/j.issn.1000-5641.201911046
    Abstract30)   HTML7)    PDF (856KB)(12)      

    In this paper, we study the long-time dynamic behavior of solutions for the non-autonomous classical reaction-diffusion equation with nonlinear boundary conditions and fading memory, where the internal nonlinearity and boundary nonlinearity adheres to polynomial growth of arbitrary order as well as the balance condition. In addition, the forcing term is translation bounded, rather than translation compact, by use of contractive function method and process theory. The existence and the topological structure of uniform attractors in $L^{2}(\Omega)\times L_\mu^2(\mathbb R^+; H_{0}^1(\Omega))$ are proven. This result extends and improves existing research in the literature.

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    Influence of the ground state wave function on the atomic high-order harmonic generation spectrum
    Zhongyuan LI, Yingchun GUO, bingbing WANG
    Journal of East China Normal University(Natural Science)    2021, 2021 (1): 103-111.   DOI: 10.3969/j.issn.1000-5641.202022002
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    High-order harmonic generation (HHG) may occur during the interaction between an intense laser field and an atom or molecule; HHG has become an important xtreme utility vehicle(XUV) light source which can be used to probe atomic and molecular structures. In this paper, we investigate the effect of the radial distribution of electric density on the HHG spectra by calculating the HHG spectrum of noble atomic gases in a polarized laser field using s and p orbital functions as ground state wave functions. The results show that the form of the wave function does not influence the cutoff value of the harmonic spectrum, which is determined by the ionization threshold energy and the laser intensity. However, different types of orbital wave functions do lead to different envelopes for the HHG spectrum. In particular, there is an additional dip in the plateau area for the p orbital case compared with the spectrum for the s orbital case. By analyzing the formula for the HHG spectrum, we attributed the dip position on the HHG spectrum to the density distribution of the ground state wave function in momentum space. This work may shed light on applications for using the HHG spectrum to visualize atomic orbitals.

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    Coupling behavior of WSe2 exciton and photon in an optical microcavity
    Shuang LIANG, Yichi ZHONG, Wei XIE
    Journal of East China Normal University(Natural Science)    2021, 2021 (1): 112-118.   DOI: 10.3969/j.issn.1000-5641.202022003
    Abstract25)   HTML3)    PDF (894KB)(4)      

    In this paper, we study the strong and weak coupling between excitons of a WSe2 monomolecular thin film and a light field in a self-made Fabry–Pérot semiconductor microcavity at 300 K. The optical properties of the sample were studied using a micro-fluorescence / white light reflection spectroscopy system with integrated angular resolution; the formation of exciton polaritons was observed in the strong coupling region, corresponding to a Rabi splitting energy of 46.7 meV. The theoretical fitting results agree with the experimental phenomena. This lays the foundation for further research on the coherent properties of exciton polaritons, and the study also provide ideas for the application of industrial optoelectronic devices in the future..

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    Comparative biological analysis to investigate the genetic hierarchy of the Indus valley civilization
    Muhammad Hidayatullah KHAN, Muhammad Asadullah KHAN, Ali AKBAR, Jian YUE
    Journal of East China Normal University(Natural Science)    2020, 2020 (S1): 62-66.   DOI: 10.3969/j.issn.1000-5641.202092116
    Online available: 22 January 2021

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    Overseas mergers and acquisitions: Political affiliation and equitable nature based on Belt and Road Initiative
    Nazia FEROZE, Tongshun CHENG, Muhammad Sabil FAROOQ, Tongkai YUAN
    Journal of East China Normal University(Natural Science)    2020, 2020 (S1): 15-23.   DOI: 10.3969/j.issn.1000-5641.202092104
    Online available: 22 January 2021

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    Empirical analysis of the impact of education on total factor productivity: Case of the Republic of Congo
    Jody Excellent BATANTOU-ALLAN, Qiang WANG, André MOULÉMVO, Christian Gatien PASSI BATANTOU
    Journal of East China Normal University(Natural Science)    2020, 2020 (S1): 57-61.   DOI: 10.3969/j.issn.1000-5641.202092115
    Online available: 22 January 2021

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    Betrothal gifts: A comparative study of Chinese and Yoruba marriage traditions
    Ajibola OGUNBIYI, Yangqian KE, Wenzhi LI, Adenike ADEGELU, Baikai ZHANG
    Journal of East China Normal University(Natural Science)    2020, 2020 (S1): 44-47.   DOI: 10.3969/j.issn.1000-5641.202092112
    Online available: 22 January 2021

    Abstract21)   HTML1)    PDF (354KB)(4)      
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    Zeros and uniqueness of a class of difference polynomials
    Yiping WANG, Zhigang HUANG
    Journal of East China Normal University(Natural Science)    2021, 2021 (1): 28-35.   DOI: 10.3969/j.issn.1000-5641.201911044
    Abstract20)   HTML4)    PDF (683KB)(9)      

    In this paper, we investigate the uniqueness and distribution of zeros of a class of difference polynomials by using Nevanlinna’s value distribution theory. We obtain results about the uniqueness of the difference polynomials $P(f)\sum_{i=1}^{k}t_{i}f(z+c_{i})$ and the distribution of zeros of the difference polynomials $P(f)(\sum_{i=1}^{k}b_{i}(z)f(z+c_{i}))^s-b_0(z)$ , where $f(z)$ is a transcendental entire function of finite order, $c_i, t_i\;(i=1, 2, \cdots,k)$ are non-zero constants, and $b_i(z)\;(i=0, 1, \cdots,k)$ are small functions with respect to $f(z)$ .

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    Electric field modulated photoluminescence from WS2 monolayers
    Meng FEI, Wei XIE
    Journal of East China Normal University(Natural Science)    2021, 2021 (1): 137-143.   DOI: 10.3969/j.issn.1000-5641.202022010
    Abstract20)   HTML3)    PDF (988KB)(1)      

    Two-dimensional materials have been used in applications across a variety of fields; transition metal dichalcogenides(TMDCs), in particular, are a candidate for use in the field of optoelectronics due to the presence of a band gap. In this paper, WS2 monolayers prepared by micro-mechanical exfoliation are transferred to two micro-period electrode structures. We found that the photoluminescence of the material is modulated by external bias. We studied the effects of bias on the photoluminescence of the WS2 monolayer at room temperature and low temperature. The corresponding characteristics and physical mechanisms of the photoluminescence(PL) spectra, moreover, are analyzed and discussed. With the application of bias to modulate the optical properties of the WS2 monolayer, it is expected that the technology can be applied to many photoelectric products, including field effect transistors, photodetectors, flexible electronic devices, and heterojunction devices.

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    Plane circular restricted three-body problem using modified Newtonian dynamics
    Yanfang BI, Tao WANG
    Journal of East China Normal University(Natural Science)    2021, 2021 (1): 53-59.   DOI: 10.3969/j.issn.1000-5641.201922016
    Abstract20)   HTML4)    PDF (593KB)(2)      

    Modified Newtonian dynamics is a major competitor of dark matter theory and contains not only a gravitational constant but also an acceleration constant. Based on a circular orbit solution for a two-body problem, this paper is devoted to studying a plane circular restricted three-body problem using modified Newtonian dynamics. We work out the Lagrangian points and the Hill curves akin to those observed in Newtonian dynamics. In contrast, however, the location and number of Lagrangian points, as well as the profile of the Hill region, are dependent on both the acceleration constant and the mass ratio of the main celestial bodies. These findings reveal a new avenue for testing modified Newtonian dynamics.

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    Spatial flatness and large-scale Lorentz violation
    Jing LI, Xun XUE
    Journal of East China Normal University(Natural Science)    2021, 2021 (1): 67-81.   DOI: 10.3969/j.issn.1000-5641.202022004
    Abstract19)   HTML3)    PDF (1736KB)(2)      

    There is an inconsistency between the Hubble parameter obtained from local measurements and model-based parameters obtained from cosmic microwave background (CMB) measurements. This inconsistency motivated us to consider new cosmological models based on $\Lambda {\rm{CDM}}$ (Lambda Cold Dark Matter Model), such as a large-scale Lorentz violation model with non-vanishing spatial curvature. The degeneracy among the spatial curvature, cosmological constant, and cosmological contortion distribution makes the model viable for interpretation of the observation data. By comparing the luminosity distance modulus and redshift with the model prediction and calculating the change in matter density as well as the cosmological constant over time, we limit the spatial curvature density to a certain range. Accordingly, we discuss the performance of the large-scale Lorentz violation model with non-vanishing spatial curvature under these constraints.

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    Second order mean field approach of non-Markovian susceptible-infected model for complex networks
    Ting QI, Zhaohua LIN, Mi FENG, Ming TANG
    Journal of East China Normal University(Natural Science)    2021, 2021 (1): 144-151.   DOI: 10.3969/j.issn.1000-5641.20202s2001
    Abstract19)   HTML3)    PDF (929KB)(6)      

    The objective of this paper is to propose a mathematical theory that can describe the non-Markovian characteristics of the network spreading process, thereby establishing theoretical support for controlling the propagation of diseases or rumors in the real world. According to the second-order mean-field approximation method and the concept of idle edges, a series of partial differential equations are presented that can be used to solve the non-Markovian spreading dynamics of a susceptible-infected (SI) model in complex networks. By comparing the simulation outputs with the theoretical results, this mathematical method can accurately predict the spreading process of the SI model on complex networks. The theory, moreover, can be used to predict the average time for a single node to be infected. The correctness and accuracy of the theory is verified by experimental simulation results.

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    Review of deep learning in cognitive radio
    Bo LIU, Xiaodong BAI, Gengxin ZHANG, Jun SHEN, Jidong XIE, Laiding ZHAO, Tao HONG
    Journal of East China Normal University(Natural Science)    2021, 2021 (1): 36-52.   DOI: 10.3969/j.issn.1000-5641.201922017
    Abstract19)   HTML3)    PDF (1163KB)(8)      

    The development of wireless communication has made spectrum resources increasingly scarce. Existing spectrum resources, however, are not currently used in an efficient way. This contradiction can usually be attributed to the problem created by static spectrum allocation strategies. Cognitive radio (CR) is widely regarded as a feasible solution to solve the problem of static spectrum allocation. In recent years, deep learning, an emerging field of machine learning, has contributed to a number of notable research and application achievements. It has become one of the driving technologies behind artificial intelligence. In this paper, we investigated the application of deep learning to CR; this includes the development of cognitive radio and deep learning as well as the usage of deep learning models in key technologies for CR (such as spectrum prediction, spectrum environment sensing, signal analysis, etc.). Lastly, we summarize and discuss conclusions from this review.

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