最新刊期
卷 59 ， 期 5 ， 2020
- 摘要：Derived noncommutative algebraic geometry is one of the most active research fields in mathematics.Several important results that mathematicians have obtained in this field are reviewed，with an emphasis on the derived noncommutative symplectic structure，noncommutative Poisson structure，and their relationships with Calabi-Yau algebras and Calabi-Yau categories.关键词：derived noncommutative geometry;noncommutative Poisson structure;noncommutative symplectic structure;Calabi-Yau category
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发布时间：2023-11-01
Invited review
- 摘要：The optimal investment strategy of the participants in the DC pension plan is studied.The financial market consists of a risk-free asset and a risky asset,and the market price of risk depends on affine-form square-root stochastic model.By using the stochastic control theory and solving the corresponding Hamiltion-Jacobi-Bellman (HJB) equation,the analytic expressions of the optimal value function and the optimal investment strategy under the CRRA utility are obtained.Finally,through numerical examples,the impact of stochastic factor and appreciation rate of the risky asset on the optimal investment strategy are explained,and it is found that the wealth proportion invested in the risky asset will continue to increase when the market state is developing to a positive state;but in the same market state,the optimal investment proportion is almost not affected by the investment period when the initial wealth is large enough.关键词：DC pension plan;optimal investment strategy;affine-form square-root stochastic model;Hamiltion-Jacobi-Bellman equation
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发布时间：2023-11-01 - 摘要：The almost-periodic solutions for BAM neural networks with time-varying delays in leakage terms on time scales are concerned. Some sufficient conditions about the existence, uniqueness and global exponential stability of almost-periodic solutions are given. An example and numerical simulations are established to illustrate the feasibility and effectiveness of the results.关键词：BAM neural networks;time scales;almost-periodic solutions;global exponential stability
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发布时间：2023-11-01 - 摘要：This paper proposes a method based on sparse regularization to identify groundwater point pollution sources. Firstly, the time domain finite element discretized equation of groundwater one-dimensional convection-diffusion equation is used to obtain the frequency domain equation by Laplace transform, and then the objective function of the groundwater point pollution source identification problem constrained by the l1 norm term is established, thus overcoming the ill-posed problem of the point source identification due to sparse spatial distribution. The identification equation is then solved iteratively using the alternating optimization method. The research results show that the proposed method can effectively identify the position and intensity changes of groundwater pollution sources under noise conditions.关键词：convection-dispersion;sparse regularization;pollution source identification;alternating optimization method;regularization parameter
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发布时间：2023-11-01 - 摘要：We performed systematically spin-polarized density functional calculations to study the structural configurations, electronic and magnetic properties of the single Ni doped endohedral Ni@B40 and exohedral Ni‒B40 metallofullerene complexes. The results revealed different stable configurations of the Ni‒doped metallofullerenes depending on the positions of the doped Ni atoms. The calculated binding energies of all the considered Ni‒doped metallofullerenes are ranged from 5.18 to 7.12 eV/atom, which indicates the chemical interactions between the doped‒Ni atom and the B atom of B40. Thus we conclude that a single Ni atom can be chemically adsorbed on the surface or encapsulated in the hollow cage of B40 to form stable Ni‒doped metallofullerenes. By introducing dopant states, the energy gap of the Ni‒doped metallofullerenes has been partly reduced, due to the local distortions and charge transfer. As a consequence of the high hybridization and confinement effect, the hybrid Ni‒doped metallofullerene complexes have an attractive characteristic of the magnetic properties: nonmagnetic complexes systems with the inherent magnetic moments of the Ni atom completely disappeared, whether the Ni adsorbed on the surface of B40 or encapsulated in the cage. These fascinating findings of the tunable electronic and magnetic properties of the Ni‒doped B40 metallofullerenes imply that this type of metallofullerenes may be a promising candidate for electronic devices, especially expected to be applicable as a single molecular device.关键词：all-boron fullerene B40;metallofullerene;single molecular device;ab initio calculation
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发布时间：2023-11-01 - 摘要：Taking Lechangxia Egongdai landslide as the research object, the influence of daily rainfall and osmotic pressure on slope deformation is considered. By establishing BP, SVM, PSO-BP, PSO-SVM four landslide body deformation prediction models, the research data of the last 4 years is derived from the Lechangxia safety inspection system, and 410 sets of data are used for training through screening, and 30 sets of deformation displacements are taken as an output,after analysis, the PSO-SVM model is found to be the accurate model. Taking the PSO-SVM model as the basic model, the factors such as the number of iterations of the particle swarm algorithm, the population size, and velocity position correlation coefficient (k) are studied, and the best PSO-SVM is obtained when the three are 100, 30, and 0.5, respectively. In this model, the RMSE, MAPE, and
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发布时间：2023-11-01 - 摘要：Aiming at the problems caused by the data increase in the early fault monitoring of modern rolling bearings, a fault diagnosis model for deep bidirectional long and short memory neural network (DBiLSTM) based on variational mode decomposition (VMD) and TEO energy window was put forward. Firstly, the instantaneous energy characteristics of bearing vibration signals were extracted by the VMD-TEO window function that optimized by the improved fruit fly algorithm. Meanwhile, the characteristic matrix with time characteristic was constructed. Secondly, DBiLSTM network model was trained by using the training set to determine the model parameters. Finally, the trained model was applied in the test set to generate fault recognition results. The test used Case Western Reserve University bearing fault data set, and the results show that this method can effectively identify vibration signals of rolling bearings with various fault types and different damage levels when dealing with large amounts of data problems.关键词：variational modal decomposition;TEO energy window function;DBiLSTM;bearing failure diagnosis
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发布时间：2023-11-01 - 摘要：Aiming at the problem of large randomness and difficulty in grasping the displays on the display assembly line, a display grabbing system of random pose based on the vision was proposed. The system used the visual toolkit of Labview to collect and calculate the images, and generated the position data of different types of displays, and sended the data to the PLC to control the grasping action of the robot. The experimental platform was built with cartesian robot, industrial camera and industrial computer as the hardware foundation, and the human-computer interaction interface was configured with Labview software. The experimental shows that the coordinate error of the system is less than 0.4 mm, and the maximum angle error is within 0.3°. It is suitable for different types of displays, and the grasping system has good accuracy and high reliability.关键词：Labview;vision;cartesian robot;image processing
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发布时间：2023-11-01 - 摘要：An optimization model of bus arrival timetable utilizing historical data is proposed to increase the riding success ratio, reduce the waiting time, and improve the level of service of buses. The concept of service reliability is introduced to indicate the probability that the riders successfully take the bus according to the timetable, and the historical percentile arrival time is proposed as the control points; then the model to maximize service reliability with the constraints conditions of rider waiting time and bus running time is proposed, and the riding success ratio and waiting time are employed to evaluate the performance of the proposed method. A case study of a bus route in Guangzhou is presented, and the results show that the proposed model can produce a timetable with higher riding success ratio and less waiting time, comparing with traditional method.关键词：traffic engineering;bus timetable;service reliability;rider waiting time
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发布时间：2023-11-01 - 摘要：The maximum 1-hour rainfall (rain peak), maximum 6-hour rainfall and maximum 24-hour rainfall recorded at Zhuhai meteorological stations from 1961 to 2018 are taken as case study. The two typical rainstorm hydrographs of rainfall joint distribution with three time periods were constructed based on the asymmetric Archimedean Gumbel-Hougaard(GH) copula. The main conclusions were reached as follows: The designed rainstorm value in Zhuhai city calculated by using the combined distribution of three time periods of rainfall is larger than the designed rainstorm value of the combined distribution with two time periods and that of a single time period; The ‘OR’ joint return periods of rainfall in combined distribution of three time periods is more suitable for dealing with the flood risk of Zhuhai city. The designed typical rainstorm hydrographs amplified by the same frequency can be selected as the reference for the design of drainage and flood prevention engineering.关键词：asymmetrical GH-copula;design rainstorm hydrograph;’OR’return period
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发布时间：2023-11-01 - 摘要：Based on the continuous monitoring data of O3 and its precursors NO2 and CO from 10 air monitoring stations and meteorological observation data in the urban area of Guiyang during a natural year from March 1st, 2015 to February 29th, 2016, temporal and spatial distribution characteristics of O3, meteorological effects and the relationship with its precursors were studied in Guiyang city. The results showed that the diurnal variation of O3 showed a "single peak" distribution characteristic, which generally reaching its peak around 16：00 - 17：00. From March to October and in February of the next year, the monthly average O3 concentration was relatively high, while in November, December and January of the next year, the O3 concentration was relatively low. O3-8h-max concentration was positively correlated with sunshine hours, daily maximum temperature and wind speed, and negatively correlated with air pressure and average relative humidity. The O3 concentration was relatively low in the urban area and relatively high in the suburbs, and the pollution gradually increased from the downtown to the suburbs. The diurnal variation of atmospheric oxidizer OX was characterized by "single peak" distribution, with the strongest oxidization in spring and summer. OX was controlled by different factors during the day and night. OX was mainly controlled by O3 during the day and NO2 during the night,respectively.关键词：Guiyang;ozone (O3);meteorological effects;precursors;atmospheric oxidants (OX)
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发布时间：2023-11-01 - 摘要：The interannual variation of early rainy season precipitation over the storm center of eastern Guangdong from 1967 to 2018, and the association with the large-scale atmospheric circulation characteristics and the precursory oceanic conditions were analyzed in this present paper. The interannual variation has strengthened since 1990s. The years with rainfall amount above normal have occurred more frequently since 2005. The circulation features were significantly between wet and dry years. The atmospheric conditions of enhanced upper-tropospheric jet, the larger subtropical high area than normal, the deepened East Asian trough, as well as the weakened southerly wind over Jiangnan area were favorable for the convergence over the storm center of eastern Guangdong in wet years. The atmospheric features of northward shift of upper- tropospheric jet, the smaller subtropical high area, strengthened continental high over East Asia, and consistent weakened southerly winds went against the convergence over the storm center of eastern Guangdong in dry years. The less (more) ice concentration in polar area and warm (cold) SST over eastern Pacific Ocean were the most significant precursors responsible for the precipitation anomalies. Further investigation showed the significant relation between ice concentration in polar area and upper- tropospheric jet, East Asian trough. On the other hand, the strong association between SST over eastern Pacific Ocean and subtropical high over western Pacific was also confirmed.关键词：precipitation in early rainy season;upper- tropospheric jet;subtropical high;ice concentration in polar area;SST over eastern Pacific;rainstorm center of eastern Guangdong
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发布时间：2023-11-01 - 摘要：By using the standardized precipitation evapotranspiration index (SPEI), the dry-wet climate changes on the 3-month time scale in the past 55 years were documented based on monthly temperatures and precipitation data from 1961 to 2015 from 55 meteorological stations in Xinjiang. The results are shown as follows: (1) The analysis of SPEI-3 on dry and wet change rates every 10 years suggested a weak trend of dryness, with a change rate of 0.055. The dry and wet change rates varied at different sites with the maximum wet rate of 0.229 and the maximum drying rate of 0.400. (2) There existed an alternating period of drought and drought relief from 1961 to 1987 and a drought relief period from 1987 to 1996. The severe drought occurred in 1997 and 2008, with the proportions of drought sites of 82% and 78%, respectively, under the threshold R1 = -0.20, -0.30, -0.40. The drought intensity and the duration of drought reached the maximum in 1997. (3) The maximum EOF1 feature vector value was 0.150, reflecting that the overall dry and wet changes were weakening and tended to become dry in the study area. EOF2 and REOF2 showed reverse changes in northern and southern Xinjiang, with the maximum feature vector values of 0.210 and 0.250, respectively. The linear trend indicated that the drought was increasing in northern Xinjiang, while the trend of drying out was weakening in southern Xinjiang. EOF3 and REOF3 were in the opposite distribution form. The maximum feature vector value was 0.320, suggesting that the east Tianshan tended to dry out, while the western South Xinjiang showed a drought relief trend.关键词：dry and wet change;empirical orthogonal function;SPEI index;temporal sequence;Xinjiang
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发布时间：2023-11-01 - 摘要：The study aimed to explore the possible mechanism of “Astragalus membranaceus - Atractylodes macrocephala koidz” for the treatment of lung cancer through network pharmacology．The active ingredients of “Astragalus membranaceus - Atractylodes macrocephala koidz ” were queried through the TCMSP database, the targets of the active ingredients were screened through the TCMSP database, and the targets were standardized and named through the Uniprot database. The lung cancer related targets were queried through the “TTD” database, “DisGeNET” database and “OMIM” database. The “compound-disease” common targets were obtained using Venn Diagram, and the protein interaction network (PPI) was constructed using STRING database, and R language was used for GO enrichment analysis and KEGG pathway enrichment analysis.“Astragalus membranaceus-Atractylodes macrocephala koidz” drugs were screened to obtain 19 active ingredients, 180 potential targets, 29 potential targets for the treatment of lung cancer, including AKT1,VEGFA,EDFR,etc. GO functional enrichment was analyzed and screened according to P <0.05, which involved 1 260 biological processes, 12 cell groups, 32 molecular functions, such as reactive oxygen species metabolic process, response to steroid hormone, regulation of apoptotic signaling pathway, T cell activation, etc. KEGG signal pathway enrichment was analyzed and screened according to P <0.05, involving 26 signal pathways, including PI3K-Akt signaling pathway, EGFR tyrosine kinase inhibitor resistance, Platinum drug resistance, HIF-1 signaling pathway, MAPK signaling pathway, Cellular senescence, Rap1 signaling pathway, Ras signaling pathway, etc." Astragalus membranaceus - Atractylodes macrocephala koidz " plays a role in inhibiting tumor angiogenesis, inducing tumor cell apoptosis and inhibiting tumor metastasis by regulating signaling pathways and anti-cancer drug resistance, thereby treating lung cancer. “Astragalus membranaceus-Atractylodes macrocephala koidz” involves multiple active ingredients, multiple targets and multiple signaling pathways in the treatment of lung cancer.关键词：network pharmacology;lung cancer;Astragalus membranaceus - Atractylodes macrocephala koidz;mechanism of action
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发布时间：2023-11-01 - 摘要：To reveal the role of TNF-α receptor genes TNF-R1 and TNF-R2 in the Nile tilapis (Oreochromis niloticus) immune processes, we cloned the full-length cDNA sequences of TNF-R1 and TNF-R2 from Nile tilapia by RACE. Sequence analysis showed that the full length of TNF-R1 cDNA was 2 275 bp, containing an open reading frame of 1 335 bp, and encoding a protein with 444 amino acids; the full length of TNF-R2 cDNA was 1 719 bp, containing an open reading frame of 1 476 bp, and encoding a protein with 491 amino acids. Protein structure prediction showed that TNF-R1 have three cysteine-rich domains and an intracellular death domain, while TNF-R2 have four cysteine-rich domains and without death domain. Systematic evolutionary analysis showed that the tilapia TNF-R1 and TNF-R2 were highly homologous with those of other vertebrates. Phylogenetic tree showed that TNF-R1 and TNF-R2 were clustered separately. By qRT-PCR, the highest expression levels of TNF-R1 and TNF-R2 mRNA were found in the gill, head kidney and spleen, and the lowest levels were in pituitary and muscle. The expression of TNF-α, TNF-R1 and TNF-R2 genes can be increased to varying degrees by stimulating the tilapia kidneys and spleen white cells incubated with LPS and Poly Ⅰ:C, respectively. The expressions of three genes in the head, kidney and spleen can be increased after intra-peritoneal injection of Streptococcus agalactiae. This study has some reference value to show the immune regulation mechanisms of TNF-R1 and TNF-R2 to improve the level of healthy breeding of tilapia.关键词：TNF-α;TNF-R1;TNF-R2;Oreochromis niloticus;immunity;Streptococcus agalactiae
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发布时间：2023-11-01 - 摘要：The title response was studied using the M06 method based on density functional theory and SMD model method combined with self-consistent reaction field theory. The study showed that the zwitterionic chelate S-A_1 formed by alanine (Ala_1) and Mg2+ di-coordination with intramolecular single hydrogen bond is the most stable. The neutral ion chelate S-A_2 formed by the double coordination of Ala_2 and Mg2+ with intramolecular double hydrogen bond is the second stable. The chiral transition of both S-A_1 and S-A_2 has three pathways. Potential energy surface studies showed that the chiral transition dominant pathways activation energies of S-A_1 and S-A_2 are 297.5 kJ·mol-1 and 266.5 kJ·mol-1 respectively in gas phase, and are 157.9 kJ·mol-1 and 165.7 kJ·mol-1 respectively with the effect of water molecules (clusters). Alanine and Mg2+ chelates exist mainly in the form of zwitterions in water solvent environment, and the chiral transition dominant pathways activation energies are 157.5 kJ·mol-1. The results showed that the alanine and Mg2+ chelate can maintain its chiral characteristics well and is easy to be preserved. It can be used as an ideal medicine or nutrition supplement for alanine and magnesium ions.关键词：α-alanine(α-Ala);magnesium ion (Mg2+);chiral transition;density functional theory;transition state;self-consistent reaction field theory;energy barrier
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发布时间：2023-11-01
Research articles
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