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25 November 2022, Volume 2022 Issue 6 Previous Issue    Next Issue

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Mathematics

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Several q-congruences on a double series Chuan’an WEI, Tong YU 2022, 2022 (6):  1-7.  doi: 10.3969/j.issn.1000-5641.2022.06.001 Abstract ( 284 )   HTML ( 258 )   PDF (420KB) ( 143 )   Save There are rare $q $ -congruences on double series in the literature. In this paper, we present several $q $ -congruences involving double series. When $q $ tends to 1, the proposed approach provides the corresponding conclusions for congruences. References | Related Articles | Metrics

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De Moivre’s theorem for a matrix representation of hyperbolic split quaternions Xiangqiang KONG 2022, 2022 (6):  8-16.  doi: 10.3969/j.issn.1000-5641.2022.06.002 Abstract ( 354 )   HTML ( 10 )   PDF (699KB) ( 185 )   Save In this paper, de Moivre’s theorem for a matrix representation of a class of hyperbolic split quaternions is studied. Firstly, the study of hyperbolic split quaternions is transformed into the study of a matrix representation of hyperbolic split quaternions. Secondly, by using the polar representation of a hyperbolic split quaternion, the three forms of de Moivre’s theorem for a matrix representation of the hyperbolic split quaternion are obtained, and Euler’s formula is extended. Thirdly, the root-finding formula of the hyperbolic split quaternion matrix representation equation is obtained. Finally, the validity of the conclusions is verified with some examples. References | Related Articles | Metrics

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Blow-up investigation of solutions to a class of nonlocal porous medium systems with space-dependent coefficients and inner absorption terms Baiping OUYANG 2022, 2022 (6):  17-29.  doi: 10.3969/j.issn.1000-5641.2022.06.003 Abstract ( 231 )   HTML ( 4 )   PDF (595KB) ( 137 )   Save In this paper, we explore the blow-up of solutions to a class of nonlocal porous medium systems with space-dependent coefficients and inner absorption terms under nonlinear boundary conditions in ${\mathbb{R}}^{n}\left(n \geqslant 3\right)$ . By constructing an energy expression and using the differential inequality technique, we obtain sufficient conditions for the global existence of solutions to the problem. Then, upper bound and lower bound estimates of the blow-up time are derived by means of the Sobolev inequalities and other differential methods when blow-up occurs. References | Related Articles | Metrics

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Blow-up phenomenon of a parabolic system with a nonlinear gradient term Yuanfei LI 2022, 2022 (6):  30-37.  doi: 10.3969/j.issn.1000-5641.2022.06.004 Abstract ( 226 )   HTML ( 4 )   PDF (510KB) ( 87 )   Save In this paper, the blow-up problem of a parabolic equation with a nonlinear gradient term in finite time is studied. By constructing an auxiliary function, using the method of energy estimation and the differential inequality technique, the lower bound of blow-up time is obtained. After limiting the parameters of the equation, the existence of a global solution is proved. References | Related Articles | Metrics

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Existence of anti-periodic solutions for a class of nonlinear discrete dynamical systems Xin MENG 2022, 2022 (6):  38-43.  doi: 10.3969/j.issn.1000-5641.2022.06.005 Abstract ( 223 )   HTML ( 7 )   PDF (461KB) ( 170 )   Save This paper explores the existence of anti-periodic solutions for a class of nonlinear discrete dynamical systems with summable dichotomy. Using the Banach fixed-point theorem, sufficient conditions for the existence and uniqueness of anti-periodic solutions for nonlinear discrete dynamical systems are established. Lastly, an example is presented to illustrate the main results. References | Related Articles | Metrics

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Finite coarse asymptotic property C-decomposition complexity Guoqiang LI 2022, 2022 (6):  44-53.  doi: 10.3969/j.issn.1000-5641.2022.06.006 Abstract ( 245 )   HTML ( 7 )   PDF (1038KB) ( 125 )   Save This paper establishes a coarse version of finite asymptotic property C-decomposition complexity in the context of coarse spaces. In particular, permanence properties of finite asymptotic property C-decomposition complexity are studied, and it is shown that finite coarse asymptotic property C-decomposition complexity implies coarse property A. In addition, the paper explores coarse property C and coarse decomposition complexity. References | Related Articles | Metrics

Computer Science

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3D obstacle-avoidance for a unmanned aerial vehicle based on the improved artificial potential field method Lanfeng ZHOU, Mingyue KONG 2022, 2022 (6):  54-67.  doi: 10.3969/j.issn.1000-5641.2022.06.007 Abstract ( 668 )   HTML ( 21 )   PDF (2858KB) ( 455 )   Save This paper aims to address the challenge of seeking an optimal safe path for a UAV (unmanned aerial vehicle) from an initial position to a target position, while avoiding all obstacles in a three-dimensional environment. An improved APF (artificial potential field) method combined with the regular hexagon guidance method is proposed to solve unreachable and local minimum problems near obstacles as observed with traditional artificial potential field methods. First, we add a distance correction factor to the repulsive potential field function to solve problems associated with unreachable targets. Then, a regular hexagon-guided method is proposed to improve the local minimum problem. This method can judge the environment when the UAV is trapped in a local minimum point or trap area and select the appropriate planning method to guide the UAV to escape from the local minimum area. Then, 3D modeling and simulation were carried out via Matlab, taking into account a variety of scenes involving complex obstacles. The results show that this method has good feasibility and effectiveness in real-time path planning of UAVs. Lastly, we demonstrate the performance of the proposed method in a real environment, and the experimental results show that the proposed method can effectively avoid obstacles and find the optimal path. Figures and Tables | References | Related Articles | Metrics

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Research on a knowledge tracking model based on the stacked gated recurrent unit residual network Caidie HUANG, Xinping WANG, Liangyu CHEN, Yong LIU 2022, 2022 (6):  68-78.  doi: 10.3969/j.issn.1000-5641.2022.06.008 Abstract ( 426 )   HTML ( 8 )   PDF (1600KB) ( 270 )   Save The concept of knowledge tracking involves tracking changes in a student’s knowledge level based on historical question records and other auxiliary information, and predicting the result of a student’s subsequent answer to a question. Since the performance of existing neural network knowledge tracking models needs to be improved, this paper proposes a deep residual network based on a stacked gated recurrent unit (GRU) network named the stacked-gated recurrent unit-residual (S-GRU-R) network. The proposed solution aims to address over-fitting caused by too many parameters in a long short-term memory (LSTM) network; hence, the solution uses a GRU instead of LSTM to learn information on the sequence of questions. The use of stacked GRU can expand sequence learning capacity, and the use of residual connections can reduce the difficulty of model training. Experiments on the Statics2011 data set were completed using S-GRU-R, and AUC (area under the curve) and F1-score were used as evaluation functions. The results showed that S-GRU-R surpassed other similar recurrent neural network models in these two indicators. Figures and Tables | References | Related Articles | Metrics

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Distant supervision relation extraction via the influence function Ziyin HUANG, Yuanbin WU 2022, 2022 (6):  79-86.  doi: 10.3969/j.issn.1000-5641.2022.06.009 Abstract ( 305 )   HTML ( 7 )   PDF (809KB) ( 157 )   Save Distant supervision relation extraction captures noisy instances while reducing the burden of manual annotation, which hinders the training and testing process. To alleviate this problem, we proposed a de-noising method based on the influence function. The influence function measures the influence of each training point; the influence of one training point is defined as the change in test loss after removing the training point. We observed that this property could be used to determine whether a training instance involves noisy data. First, we designed a scoring function based on the influence function. Then, we integrated the scoring function into a bootstrapping framework to obtain the final denoising dataset from a small clean set. Using this preprocessing method, every distantly supervised dataset could be denoised by our method. Experimental results showed that the proposed denoised dataset can achieve good performance on a public dataset. Figures and Tables | References | Related Articles | Metrics

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Personalized course recommendations based on a learner’s knowledge and personality Qimin BAN, Wen WU, Wenxin HU, Hui LIN, Wei ZHENG, Liang HE 2022, 2022 (6):  87-101.  doi: 10.3969/j.issn.1000-5641.2022.06.010 Abstract ( 540 )   HTML ( 14 )   PDF (1363KB) ( 233 )   Save Adaptive learning is an educational method that uses computer algorithms to coordinate interaction with learners, and provides customized learning resources and learning activities to address the unique needs of each learner. With the impact of COVID-19, adaptive learning has become increasingly important. One of the challenges with adaptive learning is how to provide personalized learning resources for learners—i.e., how to generate personalized recommendation for learners from a large set of learning resources. Existing methodologies mainly generate recommendations based on a learner’s knowledge level; however, this approach has some limitations. Firstly, when assessing a learner’s knowledge level, learners’ forgetting phenomenon has to date not been well modeled. Secondly, recommendations are generated separately from knowledge tracing tasks, ignoring the interconnectedness between these aspects. In addition, learners’ preferences for the type of learning resources and learning strategies is normally ignored if the knowledge level alone is used. To solve the aforementioned problems, this paper proposes a knowledge and personality incorporated multi-task learning framework (KPM) to boost course recommendations (i.e., the above-mentioned learning resources); the proposed method regards an enhanced knowledge tracing task (EKTT) as an auxiliary task to assist the primary course recommendation task (CRT). Specifically, using EKTT, we design a personalized forgetting controller to enhance the deep knowledge tracing model for accurately assessing a learner’s knowledge level. With CRT, we combine the learner’s knowledge level and sequential behavior with their personality adapted to the specific context to obtain learner’s profile; this data is subsequently used to generate a course recommendation list. Experimental results on real-world educational datasets demonstrate the superiority of our proposed method in terms of hit ratio (HR), normalized discounted cumulative gain (NDCG), and precision, indicating that our method can generate more personalized recommendations. Figures and Tables | References | Related Articles | Metrics

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High resolution panorama generation method for irregular cylindrical murals Wei HE, Weiqing TONG 2022, 2022 (6):  102-122.  doi: 10.3969/j.issn.1000-5641.2022.06.011 Abstract ( 253 )   HTML ( 10 )   PDF (54894KB) ( 114 )   Save The issue of how to unfold an irregular cylindrical mural from the top surface of a cave corridor into a panorama is a challenge for researchers involved with ancient mural protection and secondary development. This paper presents a method of dividing cylindrical murals into many overlapping small areas for sampling firstly, and then stitching these sampled images into a panorama. The constituents of this method include the following key elements: ① Reconstructing the 3D model with the sampled image set; ② Mapping the image texture to the 3D model; ③ Fitting the reconstructed irregular 3D cylindrical surface to the ideal cylindrical surface which is closest to the original form; and ④ Projecting the mural of the ideal cylindrical surface to a panorama. The method proposed in this paper was verified on an actual cave image set. The experimental results showed that the proposed method can generate the panorama in full; moreover, there was no evidence of stitching traces or texture deformation on the panorama. The proposed method offers practical value for mural protection. Figures and Tables | References | Related Articles | Metrics

Life Sciences

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Spatial and temporal distribution of Tettigonioidea and Grylloidea at different altitudes of Tianmu Mountain Zhuqing HE, Xinyi LIAO, Nuo DING 2022, 2022 (6):  123-129.  doi: 10.3969/j.issn.1000-5641.2022.06.012 Abstract ( 442 )   HTML ( 6 )   PDF (865KB) ( 203 )   Save In this research, we carried out a survey based on one fixed transect for Tettigonioidea and Grylloidea insects distributed in Tianmu Mountain from April to October of 2019. The results showed that there were 28 species of Tettigonioidea and 19 species of Grylloidea in Tianmu Mountain. Among them, six species of Tettigonioidea and eight species of Grylloidea were recorded in Tianmu Mountain for the first time. The insects became adults in August, September, and October. The insects distributed at lower altitudes tended to become adults earlier than those at higher altitudes. The number of species declined initially with increasing altitude, and subsequently increased. The Tettigonioidea species are distributed at various altitudes while Grylloidea species are primarily distributed at low altitudes. Because Truljalia tylacantha, Ruidocollaris truncatolobata, Goniogryllus punctatus and some other species are only distributed in a narrow scope at high altitudes, they can be used as indicator species for climate change in Tianmu Mountain. Figures and Tables | References | Related Articles | Metrics

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Species diversity of Plagiochila in Anhui Province Hui ZHANG, Xueqin SHI, Xiafang CHENG 2022, 2022 (6):  130-138.  doi: 10.3969/j.issn.1000-5641.2022.06.013 Abstract ( 320 )   HTML ( 6 )   PDF (3536KB) ( 203 )   Save Plagiochila is one of the genera with the largest number of species among liverworts. A study was conducted to understand the diversity and distribution of the Plagiochila genus in Anhui Province. Based on the results of the study, there were 23 species of Plagiochila found in the region, of which seven species and one subspecies were first observed in Anhui Province. Floristic analysis showed that tropical Asian elements were the most abundant, accounting for 47.83%, and East Asian elements were the second most abundant, accounting for 34.78%. In the future, the accuracy of bryophyte identification can be further improved; meanwhile, the scope and depth of future investigations should be reinforced. Figures and Tables | References | Related Articles | Metrics

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Research on diagnosis of leukemia by flow detection based on quantum dot coded microspheres Junfei YANG, Yeying WANG, Jing’e ZHOU, Jing WANG, Zhiqiang YAN, Lei YU 2022, 2022 (6):  139-149.  doi: 10.3969/j.issn.1000-5641.2022.06.014 Abstract ( 563 )   HTML ( 6 )   PDF (2251KB) ( 164 )   Save In this work, micro-scale porous carboxyl polystyrene microspheres (PS) were prepared using seed polymerization. Quantum dots (QDs) were used as fluorescent molecules to synthesize QDs with different emission wavelengths and successfully loaded into porous microspheres to form fluorescent coding microspheres (QDs@PS). Subsequently, serum samples of patients with acute leukemia (AL) were detected, and the antigen in the serum was quantitatively analyzed using flow cytometry. Scanning electron microscope (SEM) and flow cytometry images showed that the microspheres were regular and uniform in size. Fluorescence microscopy showed that the QDs permeated uniformly into the whole microsphere. In addition, QDs@PS showed good fluorescence stability, no QD leakage was observed, and the QDs@PS maintained its fluorescence for a period of at least two weeks. The use of fluorescence spectroscopic analysis for the detection of human immunoglobulin G (IgG) showed that the carboxyl groups on the surface of fluorescent microspheres are beneficial for the efficient covalent binding of biological macromolecules, which can be used for sandwich immunosandwich reaction coupling with leukemic high expression antigen interleukin 6 (IL-6). Combined with serum samples from leukemia patients, the fluorescence of QDs was detected by flow cytometry, and the mean fluorescence intensity (MFI) was calculated to determine the content of IL-6 in the serum. These results indicate that the designed optically-encoded microcarrier can be successfully applied to high-throughput and multichannel biomolecular analysis and has great potential in blood disease detection and diagnosis. Figures and Tables | References | Related Articles | Metrics

Ecological and Environmental Sciences

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Study on local phytoremediation of arsenic pollution in soil from sludge reforestation Yue REN, Weisong ZHOU, Guofu HE, Chunyi YANG, Gensen YANG, Jiayan GU, Yuanshu HU 2022, 2022 (6):  150-156.  doi: 10.3969/j.issn.1000-5641.2022.06.015 Abstract ( 248 )   HTML ( 7 )   PDF (633KB) ( 164 )   Save Exploring the remediation effect of native plants on soil contaminated with heavy metals has significant value for real-world applications. In this study, two native plants—reed and metasequoia—were selected for remediation of heavy metal arsenic in the soil of a woodland in Shanghai, and changes in soil indexes before and after phytoremediation were monitored. The results showed that: ① The arsenic content in rhizosphere soil of Ph. australis and Metasequoia was 52.4% and 28.6% lower, respectively, than the arsenic content in non-rhizosphere soil. The arsenic content in non-rhizosphere soil, moreover, was lower than the screening value for soil environmental risk. ② After comparing the microecological characteristics of rhizosphere between reed and metasequoia, it was found that metasequoia had a better nutrient enrichment effect than reed, demonstrating that metasequoia would have a better restoration effect in terms of soil fertility. Figures and Tables | References | Related Articles | Metrics

Chemistry and Chemical Engineering

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Preparation and photocatalysis properties of I-TiO2/Sr2MgSi2O7:Eu,Dy composite photocatalyst Jiaxiang CHEN, Zhejuan ZHANG, Er NIE, Yenan SONG, Xianqing PIAO, Zhuo SUN 2022, 2022 (6):  157-168.  doi: 10.3969/j.issn.1000-5641.2022.06.016 Abstract ( 227 )   HTML ( 7 )   PDF (1860KB) ( 127 )   Save A I-TiO2/Sr2MgSi2O7:Eu,Dy composite photocatalyst was prepared via hydrolysis for efficient degradation of organic pollutants in the absence of light. In this paper, the photocatalytic degradation of Rhodamine B (RhB) by the composite photocatalyst was studied. The results show that the degradation ability of I-TiO2/Sr2MgSi2O7:Eu,Dy composite photocatalyst with a I-TiO2 ratio of 30% is better, and the degradation efficiency of RhB pollutants reached 31.9% in 6 h without a light source. These results indicate that a Sr2MgSi2O7:Eu,Dy composite photocatalyst, supported by long afterglow phosphor, can absorb light energy and become a new light source in light-free or low-light environments for the photocatalytic reaction of I-TiO2 in order to achieve 24-hour catalytic purification. Figures and Tables | References | Related Articles | Metrics

Estuary and Coastal Research

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Study on sediment stability between vegetation and bare flats in a muddy intertidal flat: A case study for Chongming Dongtan in the Yangtze River Estuary Yingxin ZHANG, Wenxiang ZHANG, Benwei SHI, Yaping WANG 2022, 2022 (6):  169-177.  doi: 10.3969/j.issn.1000-5641.2023.03.017 Abstract ( 407 )   HTML ( 24 )   PDF (3028KB) ( 250 )   Save With the present global warming scenario, the erosion of intertidal flats in estuarine zones often occurs due to rising sea levels and an increase in human activities. Intertidal flats have an important ecological function and economic value, including for carbon sequestration, preventing flooding, water purification, attenuating waves, and tourism development. Hence, it is of great theoretical and practical significance to study the stability of the wetland ecosystem for intertidal flats. Previous studies mainly focused on the stability of intertidal bare flats, while the stability of salt marsh ecosystems has attracted relatively less attention. The mechanisms of their respective influencing factors are, as of yet, poorly understood. In this study, we took a typical muddy intertidal zone of Chongming Dongtan in the Yangtze River Estuary as an example and made a comparative analysis on sediment stability for both the salt marsh zone and the adjacent bare flat using in-situ sampling and laboratory tests. The results indicate that: ① Sediment stability improves with an increase of clay content in the bare flat. ② Sediment stability in the salt marsh zone is significantly higher than that in the adjacent bare flat because of the “reinforcing” effect of the root system. ③ Underground biomass determines sediment stability for the same type of vegetation. The sediment becomes more stable with an increase of the underground biomass in vegetation. The sediment stability of different vegetation is determined by characteristics of the vegetation root system. The sediment stability of Spartina alterniflora vegetation zone with coarser roots was worse than that of Scirpus mariqueter with finer roots. Our results not only advance theoretical research on sediment stability in intertidal flats, but also provide scientific guidance for the construction of Green Sea Defence and other coastal green protection measures. Figures and Tables | References | Related Articles | Metrics