最新刊期
卷 58 ， 期 1 ， 2019
- 摘要：Based on daily temperature (maximum, minimum and average) data of 153 meteorological stations, the spatial and temporal characteristics of extreme temperature events in the Huaihe River basin from 1961 to 2014 are analyzed from the perspective of trend and correlation, using statistical methods to calculate 26 extreme temperature indices. The regional response of climate change in the basin is further discussed by comparing with other regional temperature changes. The results are as follows: (1) The maximumTmax and minimumTminrise by a wide range of significant trend, the largest increase was 0.4 ℃ / 10a and 1.3 ℃ / 10a. Warm night days, summer days, hot wave spell duration indicator, and others in the Huaihe River basin as a whole are on the rise. The warm evenings with hot night index showed a trend of wide range increases significantly, with an increase of 6.3 d/10a and 7.1 d/10a. (2) Cold days, cold nights, frost days, icing days, cold spell duration indicator, cold wave spell duration indicator and frost spell duration indicator have significantly decreased by -2.3, -6.8, -10.0, -2.5, -10.0, -7.3, -4.3 d/10a, respectively. (3) The diurnal temperature range in the Huaihe River basin is decreasing in general. The growing season length shows statistically significant increasing trends at rates of 7.6 d/10a, while the temperature index in the growing season length is slightly lower. (4) The extreme temperature indices of the Huaihe River basin have obvious differences in variation range, spatial distribution, time of mutation occurrence and correlation. In terms of change amplitude, the extreme cold index is greater than the extreme warmth index, and the night index is greater than the day index. On spatial distribution, the variation amplitude of these indices and significance test pass rate are greater in eastern region than in western region, and the increase of extreme warm indices in the southeast of the Huaihe River basin is far greater than in other areas. And extreme cold index mutations occur earlier than warm about 10 a. The most extreme temperature indices are correlated with the longitude, latitude and altitude. Particularly, the trend of main extreme temperature indices of the Huaihe River basin is consistent with regional and global scales.关键词：extreme temperature indices;sen slope method;Mann-Kendall test;regional responses;Huaihe River Basin
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发布时间：2023-12-11 - 摘要：Human activities led to many continuous natural forests fragmented into such asFengshuiforests around villages, how their forest carbon sinks are related to forests patch sizes and vegetation biomasses demands academic research. In a case study of aFengshuiforest in eastern Guangzhou suburbs, five large patches for each of three patches with area sizes of 15-25 hm25-8 hm2and 0.5-2 hm2respectively, were selected based on site conditions, vegetation type, forest structure, stand age and growth stage. Then, the above-ground biomass and gradient variation from the edge to center for theFengshuiforest were investigated to figure out the relationship between patch size and above-ground biomass by using combined quadrat survey and remote sensing estimation. The results are as follows: (1) the average above-ground biomass obviously varies from large to small patches (P<0.01), and generally shows an increase trend with the forest size with a biomass of 199.33 t/hm2for large patches, 181.59 t/hm2for medium, and 147.51 t/hm2for small patches. (2) In large patches, the above-ground biomass increases from 290.24 t/hm2226.63 t/hm2to 129.16 t/hm2from center to edge, showing that the edge effect has a great impact on ground biomass in theFengshuiforest patches. (3) There is the largest proportion of tall and thick trees in large patches, which probably results in a larger biomass in large patches than in medium and small patches. So the improvement of forest carbon sink needs the protection and construction of large forest patches.关键词：biomass;patch area;perimeter-area ratio;edge effect;natural forest fragments
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发布时间：2023-12-11 - 摘要：In order to improve the accuracy of the application of remote sensing image in plant classification beyond the weakness of only using spectral information, the texture features ofApocynum venetuma typical wild plant in Xinjiang, are extracted based on fractal theory from Worldview2 satellite images by means of double blanket coverage model which are further analyzed by Gray Level Co-occurrence Matrix (GLCM) methods for its classification. Maximum likelihood method is used to classify the textures, and the classification results from different moving window sizes (3×3, 5×5, 7×7 and 9×9) are compared. The results show that overall classification precision increased by 1.21% to 8.63% for the texture classification compared to traditional spectral information classification, the precision based on fractal theory is more than twice as much as GLCM based texture classification. The classification accuracy ofApocynum venetumincreased to 99.96% when this parameter was combined with fractal-based textures. By contrast, the accuracy reduced by 0.09% to 0.12% with GLCM-based textures, and there is best classification precision when fractal-based texture was extracted with a 5×5 sliding block. Therefore, the textures based on fractal theory could effectively improve the accuracy of Worldview-2 images in plant classification by GLCM and double blanket coverage model.关键词：fractal theory;double blanket coverage model;texture;Worldview-2;Apocynum venetum
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发布时间：2023-12-11 - 摘要：Horizontal and vertical airflow characteristics and pollutant transport & diffusion in a residential area in Haizhu district, Guangzhou, during summer and winter, were simulated by using three-dimensional micro-scale meteorological model ENVI-met based on the distinct meteorological conditions, and then validated with the field observation of CO concentration. The results showed that there existed wind corner flow, climbing airflow and landslide, and backflow in the area, which lead to abnormal concentrations of pollutants at different locations and heights. While incoming flow was parallel to street canyon, a high pollutant area can be observed in the convergence zone of airflows. While incoming flow is perpendicular to street canyon, there exist two situations: airflows in opposite direction of incoming flow were observed in the regions behind independent building or between the lower upwind building and higher downwind building, resulting in highly polluted regions on the leeward side of the street; airflows in the same direction of incoming flow were observed, causing more cumulative pollutants in the mid-east of the street in the regions between the higher upwind building and lower downwind building. The efficiency of vertical diffusion in the street valley was the highest in regions between the lower upwind building and higher downwind building, the second in regions between the higher upwind building and lower downwind building, and the lowest over independent building. The results also showed that ENVI-met model can be used to simulate pollutant dispersion at street scales.关键词：pollutant dispersion;flow field over community;ENVI-met;numerical model;street canyon
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发布时间：2023-12-11 - 摘要：Eastern Junggar of Xinjiang Uygur Autonomous Region is an important area of the Central Asian Orogenic belt, where the Siberia and Kazakhstan plates collided. Late Carboniferous granites are widespread in this area, among which alkali granites in Yundukala are investigated and studied in this paper. Yundukala alkali granites are characterized by high SiO2(72.40%-74.17%), high alkaline (Na2O+K2O=8.41%-10.40%), low TiO2(0.20%-0.40%) and low CaO(0.38%-0.70%) contents. They are significantly enriched in high field strength elements like Zr, Th, and Y, and exhibit highly differentiated REE patterns, showing right dipping lines with strong negative Eu anomaly, whilst their obvious depletion of Sr, Ba and Ti might have resulted from fractional crystallization of feldspar and Ti-oxides. These geochemical characteristics indicate they are typical A-type granites and may be the product of partial melting of the predominantly subducted oceanic crust or Nbrich basalt in the lower crust. The formation of these A-type granites infers that collisional orogenesis ended during late Carboniferous.关键词：A-type alkali granite;geochemistry;tectonic implications;Yundukala
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发布时间：2023-12-11 - 摘要：Heterogeneous network (Het Net) is a typical network structure of the future mobile communication system. And the uplink power control algorithm is of an important technology in the interference management of Het Net. Combining the game theory and the uplink power control algorithm of Het Net , a new uplink power control algorithm of game theory in Het Net is proposed in this paper. The new algorithm applies the price payment function of game theory to the uplink power and power allocation algorithm. In Het Net, any user’s power change should consider the generating interference to the other co-frequency users located in the network and use it as a price-based payment function to control the user uplink power. After multiple iterations, the optimal users‘ uplink power can be obtained which results in the improvement of network performance. Simulation results show that the proposed algorithm can bring the performance gains of Het Net in both the system uplink throughput and energy efficiency ratio.关键词：game theory;Het Net;uplink power control;interference management;mobile communication
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发布时间：2023-12-11 - 摘要：The Hongwan fishing port project is located at the estuary of the Zhujiang River. Due to the influence of water and sand carried by runoff and tidal power of the open sea, the hydrodynamic conditions at this location are very complicated. Based on the theory of fluid dynamics and hydrogeological data for many years, the flow field and sedimentation after the implementation of the Hongwan fishing port construction plan are numerically simulated in this research; an optimization plan based on the simulation results is proposed. Results show that after implementing the construction plan, the flow rate and flow direction of the channel are less affected and the average back sedimentation rate is relatively large. The site of maximum sedimentation is near the harbor entrance and had a thickness of 0.92 m. This feature can be further optimized through large-scale excavation of the entrance or by constructing an artificial masonry dam.关键词：Hongwan fishing port;tidal current and sediment;sedimentation;flow field
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发布时间：2023-12-11 - 摘要：Based on the Weibull distribution, survival patterns of different vehicle types and areas in Guangdong Province were obtained from information collected by Guangdong Vehicle Information Database, following with analysis on their characteristics and influencing factors. Furthermore, by combining vehicle population projection method (the elastic coefficient method specifically in this case), the survival patterns were used in the age distribution projection of different vehicle types in Guangdong, 2030. Result showed that：1) life spans of Heavy-Duty-Passenger-Car (K1), Medium-Duty-Passenger-Car (K2) were 18 years,while that of Light-Duty-Passenger-Car (K3) and Mini-Passenger-Car (K4) were 20 years; 2) life spans of Heavy-Duty-Truck (H1), Medium-Duty-Truck (H2), Light-Duty-Truck (H3), and Mini-Truck (H4) increased in turn;3) the economic developing level affected vehicle survival pattern with the evidence that life spans of K3, K4, H3, H4 in Pearl River Delta (PRD) were 3.39，5.10，4.74，4.26 years shorter than that of non-PRD. The proposed method can be used to conveniently obtain vehicle age distribution. The traffic pollution control polices, the economic developing level and variations among different vehicle types would affect the survival patterns.关键词：age distribution;survival probability;Weibull Distribution;elastic coefficient method
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发布时间：2023-12-11 - 摘要：An identification method of triangular impulse force based on BMO is proposed. In the study the dynamic response equation of the beam is constructed first, to obtain the dynamic responses of the beam under impulse load, the structure is further discretized by finite element method. The parameter identification problem will be treated as an optimization of an objective function based on the deviation of responses between calculated and measured. Bird mating optimizer is utilized to solve the optimization. Four parameters, the location, maximum magnitude, load time and unload time are identified successfully, additional results show that the proposed method is capable to identify the parameters precisely even under noise affection, and BMO achieve better results than other traditional heuristic algorithms, which shows a potential in practical application.关键词：impulse force;finite element model;bird mating optimizer;responses of time domain
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发布时间：2023-12-11 - 摘要：This paper presents a rear-wheel in-wheel motor driven medium speed and light electric vehicle modeling and control analysis integrating kinematics, dynamics and motor mechanical and electrical characteristics including longitudinal motion, lateral motion, yaw motion aroundzaxis, rear-wheel driving force, motor speed and motor toque parameters. Rear-wheel longitudinal driving force is function of slip and side force is related to sideslip angle. Ackermann turning model is applied for ideal speed distribution with driving speed and two motor speeds as control and feedback variables. Responses of three loops PID model, one loop control model and original model are analyzed and compared by simulation under four driving conditions of forward driving with speed steps, forward driving with speed slope, turning angle step change with constant speed and turning angle sine change with constant speed for verification.关键词：in-wheel motor;back-wheel actuation;electrical vehicle;PID control
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发布时间：2023-12-11 - 摘要：Elongation Hartree-Fock (ELG-HF) achieves linear scaling for large systems when coupled with quantum fast multipole method. However, it is a simpler method to form the Fock matrix directly from localized molecular orbitals, which requires transforming the two electron integrals from an atomic orbital basis to a localized molecular orbital basis. For each elongation step, almost constant scaling is achieved when cutoff is used to exclude atomic orbital two electron integrals that are not required in the transformation. The Schwarz inequality, molecular orbital prescreening and using a set of hybridized molecular orbitals reduce the time required to complete the transformation and eliminate additional atomic orbital two electron integrals. The results for water molecule chain verify that linear scaling for ELG-HF methods is achieved. This new method is more effective than forming the Fock matrix from atomic orbital two electron integrals when the size of the interactive region contains fewer than 120 well localized molecular orbitals.关键词：linear scaling;elongation method;localized orbitals
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发布时间：2023-12-11 - 摘要：Conotoxin lt3a was firstly purified and identified from the crude venom ofConus litteratus. The proline in the amino acid sequence of lt3a was undergone hydroxylation modification during the process of conotoxin maturation. To investigate the effect of hydroxyproline on the folding and activity of lt3a, conotoxin lt3a［P6O］ with hydroxyproline in position 6 and conotoxin lt3a without hydroxyproline were chemically synthesized and the oxidative folding rate, thermal stability and biological activity of lt3a［P6O］ and lt3a were investigated. The results demonstrated that the hydroxyproline could increase the folding rate of lt3a, but had no effect on thermal stability, which was different from the situation in the collagen. It might be due to the reason that the number of Hyp in lt3a was not enough to form the helix and the stable “water bridge” structure to enhance the thermal stability. Moreover, Hyp substitution had no impact on the conotoxin activity in the case of lt3a.关键词：hydroxyproline modification;conotoxin;oxidative folding
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发布时间：2023-12-11 - 摘要：The title reaction was performed by ONIOM method combined with QM and MM. Structural analysis showed that the skeleton of valine deformationed obviously induced by confinement effect of SWBNNT(5,5), at the same time SWBNNT(5,5) also had an obvious deformation. Calculation showed that the optical isomeric reaction channel with amino nitrogen as the proton transfer bridge had advantages for valine molecules. When valine molecules confined in SWBNNT(5,5), the intrinsic energy barrier of optical isomers rate-limiting step was 318.41 kJ·mol-1. When proton transfer and hydroxyl rotation occurred simultaneously and stepwise, the related intrinsic energy barrier of optical isomers rate-limiting step were 306.42 and 306.93 kJ·mol-1in SWBNNT(6,6), respectively, which were significantly higher than the intrinsic energy barrier of the bare reaction dominant channel with the value of 262.81 kJ·mol-1. When valine molecules confined in SWBNNT(7,7), the intrinsic energy barrier of optical isomers ratelimiting step was 262.81 kJ·mol-1which was no different from that in the naked reaction. The results showed the confinement of SWBNNT(5,5) and SWCNT(6,6) had an obvious negative catalysis to optical isomers of valine molecules.关键词：valine;optical isomers;single-walled boron nitride nanotubes;ONIOM method;density functional theory;transition state;perturbation theory
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发布时间：2023-12-11 - 摘要：A new electrochemical composite is reported, which is based on redox mediator toluidine blue O (TBO) self-assembled onto the surface of nitrogen, phosphorus and sulfur codoped porous carbons (N, P, S@PC). The N, P, S@PC and N, P, S@PC-TBO composites were characterized by scanning electron microscopy and the results showed surface morphology of the two composites was distinctly different. The N, P, S@PC-TBO composite was used to modify glass carbon (GC) electrode which displayed high conductivity. The electrocatalytic behaviour of N, P, S@PC-TBO/GC electrode was studied by voltammetry and amperometry. The results demonstrated that the N, P, S@PC-TBO/GC electrode provided a positively synergistic effect between N, P, S@PC and TBO on the electrocatalytic oxidation of NADH. This modified electrode exhibited a wide linear range from 1×10－6- 2×10－3mol/L and a detection limit of 3×10－7mol/L (S/N= 3) with a fast response time of 2 s, at a low applied potential of－0203 V. Therefore, the N, P, S@PC-TBO/GC electrode provides a new platform for the detection of NADH.
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发布时间：2023-12-11 - 摘要：A novel approach to prepare the difference samples of traditional Chinese herbal formulae (CHF) was established，the strategy of the approach are: regarding the herb as the test factors, defining the suitable test levels based on the original herb proportion, designing the different herb proportion using Uniform Design method, preparing the different samples according to standard process, analyzing the HPLC chromatography of the difference samples using Cluster Analysis. Different from traditional pattern of separating and combining the component one by one, the proposed approach re-adjusts the herbs as a whole with the advantages of low difficulty and high applicability, conforming to the CHF characters of mixture, integrity, and unity.关键词：traditional Chinese herbal formulae;samples with component differences;Compound Xueshuantong Capsule
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发布时间：2023-12-11 - 摘要：The weak well-posedness for the Cauchy problem of the twocomponent DegasperisProcesi system with the initial value(u0ρ0)∈(H1(R)∩W1,∞(R))×(L2(R)∩L∞(R))is obtained. First, by introducing characteristics, the two-component Degasperis-Procesi systems are transformed into an ODE system. Next, applying the classic well-posedness theory to the solution of ordinary differential equations, the local existence and uniqueness of the solution to the ODE system are obtained. Finally, the local existence and uniqueness of the solution for the two-component Degasperis-Procesi system are investigated. And the conclusion of the weak continuous dependence on initial conditions is proven.关键词：two-component Degasperis-Procesi system;existence and uniqueness;weak continuous dependence
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发布时间：2023-12-11 - 摘要：A dynamic fuzzy neural network algorithm (D-FNN) is proposed. In practical application, Kalman filter (KF) is used to adjust the result parameters of D-FNN. Meanwhile, extended Kalman filter (EKF) is used to update the center and width of the premise parameters, so that all parameters can be modified. This algorithm is used to smooth, filter or predict the state of a nonlinear dynamic system. Comparing to other online algorithms which are based on gradient, EKF can accelerate the convergence speed of D-FNN. The total least squares (TLS) is a pruning technique to select the important fuzzy rules of D-FNN, which also is a technique to compensate data error in linear parameter estimation problem. If the inactive fuzzy rules are detected and removed during the learning process, a more compact D-FNN structure can be obtained. Finally, a simulation analysis for actual case verify the effectiveness and efficiency of the algorithm.关键词：D-FNN;pruning technique;fuzzy rules;RBF neural network
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发布时间：2023-12-11 - 摘要：LetGbe a graph and μ(Gx) denote the matching polynomial ofG. The sum of the absolute values of all the roots (all the coefficients) of μ(G,x) is called the matching energy (the Hosoya index). LetCa+1andCb+1be two cycles with a+1 vertices and b+1 vertices, respectively. The 8-shape graph ∞(a,b) is the graph with a+b+1 vertices obtained fromCa+1∪Cb+1by identifying a vertex ofCa+1with a vertex ofCb+1. A new method for comparing matching energies between two graphs is deduced. By using this new method, the matching energy and Hosoya index of the 8-shape graphs is studied. And a completely order of matching energy and Hosoya index of the 8-shape graphs withnvertices is obtained.
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发布时间：2023-12-11 - 摘要：An interior inverse scattering problem with a Neumann boundary condition is studied by using reciprocity gap method. First, the conclusion that the position and shape of a cavity with a Neumann boundary condition can be uniquely determined by providing measurments of point sources inside the cavity is proven. Next, by following the idea of reciprocity gap method, a numerical algorithm to effectively reconstruct position and shape of an unknown cavity from interior measurements is designed. Finally, some numerical examples to validate the method are presented.关键词：cavity;interior inverse scattering problem;Neumann boundary condition;reciprocity gap method
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发布时间：2023-12-11 - 摘要：The weak well-posedness of the weak solution to a three-component Camassa-Holm system with peakons is studied. After using the technique of flow to get an integral system equivalent to the original one in weak sense under the Lagrange coordinates, the main results is accomplished.关键词：three-component Camassa-Holm system;weak solution;weak well-posedness;flow
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发布时间：2023-12-11
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