最新刊期
卷 55 ， 期 2 ， 2016
- 摘要：The existence and Ulam stability of solutions of a discrete nonlinear fractional boundary value problem are studied. The existence results are established based on Schaefer fixed point theorem and inequality analysis technique. Meanwhile, new criteria for Ulam stability of solutions to the nonlinear fractional difference equation are provided and examples are presented to illustrate the effectiveness of the main results.关键词：fractional difference equation;fixed point;existence;Ulam stability
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发布时间：2023-12-11 - 摘要：An adaptive fuzzy controller(AFC) is proposed by considering the uncertain payload as well as robot dynamics in task space. To eliminate the noise from the velocity obtained by the differential of position, the velocity is filtered by a low-pass filter, while, the task-space velocity is estimated by the Jacobian matrix. The estimation error is considered in the controller design. And another low-pass filter is used to build the error function. The control law is composed of two parts. The first part is a fuzzy logic system approximating the nonlinear term of the robot dynamics, including friction; and the second part is a robust term to reduce the approximate error of the fuzzy logic system as well as the uncertain external disturbance. Using Lyapunov theory, the controller is given and the stability of the closedloop system is proved. Comparing simulink results by using matlab show that, the tracking tajectory of the endeffector under the proposed AFC controller has good accuracy and smoothness.关键词：robot manipulator;task-space tracking;fuzzy logic system;adaptive control;uncertain parameters
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发布时间：2023-12-11 - 摘要：It is always an important topic in probability theory and mathematical statistics to estimate the tail probability of random variables. By using truncation technique and exponential inequality, the complete convergence is obtained for END random variables with all moments exist, but the moment generating function does not exist. The main result extends the related work due to Gut and Stadtmuller.关键词：END sequence;complete convergence
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发布时间：2023-12-11 - 摘要：The distance spectral radius μ(G) of a graph G is the largest eigenvalue of the distance matrix D(G). By using diameter of circulant graphs, some upper bounds for μ(G) are obtained. Furthermore, the upper bound of Cartesian product graph for circulant graphs are discussed.关键词：circulant graph;distance spectral radius;diameter;Cartesian product graph
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发布时间：2023-12-11 - 摘要：The nonlinear singular perturbation interior layer initial boundary value problem for the reaction diffusion equation is considered. Under suitable conditions, the reduced problem generalized outer solution is discussed. By introducing a stretched variable, the formal asymptotic expansion for the generalized solution with interior layer and initial layer corrective terms is constructed. Finally, using the fixed point theory of functional analysis, the existence and uniformly valid interior shock asymptotic solution for the original initial boundary value problems are proved.关键词：nonlinear;shock;asymptotic solution
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发布时间：2023-12-11 - 摘要：In certain condition, the shallow water wave may emerge in solitary wave form, interacting with offshore structures. Based on wave reflection theory and Biot wave seepage consolidation theory, the analytical solutions of the reflected solitary wave potentials and the solitary wave-induced seepage pressures inside permeable elastic seabed are derived by applying the eigenfunction expansion approach, and the wave-induced lift force and overturning moment caused by the seepage pressure on the bottom of the vertical breakwater are accordingly calculated. The results show that the variation of sea and seabed conditions and breakwater geometry condition may have some influence on wave-induced seepage uplift force and overturning moment. The solitary wave-induced seepage effects may have the same order of magnitude as the direct horizontal wave effects. Compared with the results from small amplitude wave theory, the solitary wave theory can reflect shallow wave nonlinear effects.关键词：solitary wave;vertical breakwater;wave reflection;wave force;wave-induced seepage uplift force and overturning moment
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发布时间：2023-12-11 - 摘要：The outage performance of the secondary user is investigated for cognitive relay networks with underlay spectrum sharing model. An exact closedform of outage probability is derived over independent but nonidentically distributed (noni.d.) Rayleigh fading channels. The derived formula is verified by MonteCarlo simulations and is served as an effective tool to evaluate the outage performance under different channel parameters. Simulation results show that the channel state of the relaying link (ST→SR) and the interference link (ST→PD) dominate the outage performance in cognitive relay networks.关键词：cognitive relay networks;underlay spectrum sharing;non-identically distributed Rayleigh fading channel;exact form of outage probability
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发布时间：2023-12-11 - 摘要：The disadvantage of the concept of temporal consistency is that it only describes binary states of real-time data objects. The concept of validity degree function is presented to overcome the problem. Based on the new concept, two sensor transaction scheduling schemes VM-DS and VM-SN are proposed. Both schemes maximize the data validity degree by judiciously setting the lengths of data validity intervals and the execution frequencies of sensor transactions. Experiments are conducted to evaluate the performance of two schemes. The results show VM-SN outperforms in terms of the average data validity degree and the ratio of validity degree to workload, thus it can better satisfy the timeliness requirements of the systems.关键词：cyber physical systems;sensor transactions;validity degree function
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发布时间：2023-12-11 - 摘要：Indoor location is a key technology in the application of pervasive computing, and aims at solving the problem of least square support vector machine parameters. An indoor localization algorithm based on the least square support vector machine is proposed. The principal component analysis is used to extract important features, and then, least square support vector machine is established for indoor localization model using particle swarm optimization algorithm. The simulation experiment is used to test location performance. The results show that the proposed algorithm improves the accuracy of indoor location, and the location time is less than other indoor location algorithm.关键词：pervasive computing;indoor location;parameter optimization;principal component analysis
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发布时间：2023-12-11 - 摘要：A mobile manipulator is composed of a mobile platform and a stationary manipulator fixed to the platform. In order to achieve the coordinated motion control of mobile manipulators, the mobile platform and the manipulator have to fulfill tasks simultaneously. According to the analysis of kinematics for the mobile manipulator, a coordinated motion scheme based on the minimum velocity norm is proposed and investigated. Such a scheme can not only control the motion of the mobile platform, but also coordinate the manipulator to complete tasks simultaneously. Besides, the coordinated motion scheme can be converted equivalently to a standard quadratic program, which can be solved by an effective numerical algorithm. Finally, the mobile manipulator is applied to perform a circular path and the corresponding simulative results validate the effectiveness of the coordinated motion scheme.关键词：mobile manipulator;quadratic programming;coordinated motion;numerical algorithm
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发布时间：2023-12-11 - 摘要：The Noether symmetries and conserved quantities for non-conservative systems are proposed and studied with fractional model. Based on the Hamilton principle for the non-conservative systems, the fractional differential equations of motion are derived. With using the invariance of the fractional Hamilton action under the infinitesimal transformations of group which depends on the time, the generalized coordinates and velocities, the definition and the criterion of the fractional Noether generalized quasi-symmetry for the non-conservative systems are given. The relation between the fractional Noether quasi-symmetry and the conserved quantity is established, and the fractional conserved quantities are obtained. The special cases, which the generalized nonpotential forces do not exit or the gauge function is equal to zero, are discussed. At the end, two examples are given to illustrate the application of the results.关键词：fractional model;non-conservative system;Noether quasi-symmetry;conserved quantity
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发布时间：2023-12-11 - 摘要：In order to obtain wollastonite filled β-polypropylene composites, calcium pimelate-supported wollastonite (β-W) was prepared through the chemical reaction between wollastonite and pimelic acid, and the heterogeneous nucleating effect of wollastonite and β-W on PP crystallization was investigated. FTIR and TGA analyses confirmed the formation of calcium pimelate on the surface of wollastonite. The results of DSC, XRD and POM indicated that calcium pimelate formed on the surface of wollastonite, resulting in α→β transition of nucleation mechanism of wollastonite surface. The β-W filled PP composites mainly formed β-phase, and the β-nucleating ability of β-W was dependent of the mass ratio of wollastonite/pimelic acid.关键词：polypropylene (PP);wollastonite;β-nucleating effect
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发布时间：2023-12-11 - 摘要：Based on the B3LYP methods of density functional theory and the MP2 methods of perturbation theory, the chiral transformation mechanism of the Val monomer molecule, the catalytic effect of water molecules and hydroxyl radicals on the hydrogen transfer reaction were studied. The reaction channel analysis showed that there were four channels a, b, c and d in the Val chiral enantiomer transformation reaction. Channels a and c, the chiral shift was achieved by the H of chiral carbon transferring to the other side from the bridge of Amino N and Carbonyl O respectively. Channel b, the chiral shift was achieved by the H of chiral carbon transferring to the other side from the bridge of Amino N and Carbonyl O in turn. Channel d, the chiral shift was achieved by the H of chiral carbon transferring to the other side from the bridge of Hydroxyl O. From the calculation of potential energy surface, channel a was the optimal reaction channel, the highest energy barrier is 257.6 kJ·mol-1. One water molecule, two water molecules chain and the chain of one water molecule and Hydroxyl radical showed better catalytic effect on the H shift reaction, which decreased the high energy barrier in channel a to 160.3,124.4 and 104.0 kJ·mol-1 accordingly. The result revealed that optical isomer of valine molecule in living body was formulized mainly under the joint action of water molecule and hydroxyl radical.关键词：chiral;valine;density functional theory;transition state;perturbation theory
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发布时间：2023-12-11 - 摘要：Previous experiments showed that triterpenoid saponins of Guangdong Liangcha were mainly from the roots of ilex asprella and Rosa laevigata Michx.. However, chemical constituents mainly focus on leaves and fruits of Rosa laevigata Michx., and the secondary metabolites from the roots of Rosa laevigata Michx. were very few published. So, on the basis of previous study, six compounds were isolated from the roots of Rosa laevigata Michx. by various chromatographic techniques and their structures were identified by spectroscopic analysis and literature confrontation method, such as 2α, 3α, 19α-trihydroxyurs-12-en-28-oic acid β-D- glucopyranosyl ester(1), 2α, 3β, 19α-trihydroxyurs-12-en-28-oic acid β-D-glucopyranosyl ester (2), 2α, 3β, 19α, 23-tetrahydroxyurs-12-en-28-oic acid β-D-glucopyranosyl ester(3), oleanolic acid(4), ursolic acid(5), (+)-catechin(6). Compounds 1，2，3 as triterpenoid saponins in Guangdong Liangcha have been firstly obtained from the roots of Rosa laevigata Michx..关键词：Rosa laevigata Michx.;chemical constituents;triterpenoid saponins;structural identification
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发布时间：2023-12-11 - 摘要：To study the secondary metabolites of endophytic fungus Neurospora sp. DHLRH-F from Meconopsis grandis Prain from Tibet, its fermentation products were isolated and purified by silica gel, Sephadex LH-20, ODS-18 column chromatography, and HPLC. The structures of obtained compounds were identified by NMR and MS analysis, and the absorption spectrums of the compounds-iron (Ⅱ) or iron (Ⅲ) were investigated by UV/Vis spectroscopy, respectively. The results showed that three polyphenols were isolated from the fermentation compounds of Neurospora sp. DHLRH-F. Their structures were identified as 2-chloro-6-methoxybenzene-1,4-diol (1), 6-epi-5′-hydroxymycosporulone (2), and mycophenolic acid (3); compound 1 was a new natural product and showed a certain complexation ability for iron (Ⅲ). We firstly reported about secondary metabolites of endophytic fungus from Meconopsis Vig..关键词：Meconopsis grandis Prain;endophytic fungus;secondary metabolites;complex iron(Ⅱ;Ⅲ)
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发布时间：2023-12-11 - 摘要：The exterior surfaces of the TiO2nanotube (TNT) were modified by a silane coupling agent to make nano-Ru selectively deposit on the inner wall. The as prepared catalysts were characterized by transmission electron microscope (TEM), high-resolution transmission electron microscopy (HREM), energy dispersive spectrometer (EDS), high-angle annular dark field image(HAADF), scanning transmission electron microscopy (STEM) and UV-vis absorption spectra. The results confirm that nano-Ru particles in the range of 2~3 nm in diameter are entrapped in the TNTs. TNTs-confined 2% Ru exhibits the best photocatalytic performance, which photocatalytic efficient is 1-8 times of pure TNTs.关键词：hydrothermal method;confinement catalysis;TiO2nanotube;noble metals
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发布时间：2023-12-11 - 摘要：Culter alburnus is one of the most economically important edible freshwater fish in the Pearl River and is widely distributed in the Yangtze River and the Yellow River. To assess the level of genetic diversity and genetic variation of C.alburnus populations within the Pearl River，the samples were collected from the eleven geographical populations from Guangxi and Guangdong Province (Wuzhou, Zhaoping, Pingle, Liucheng, Guiping, Pingguo, Tianyang, Longzhou, Fusui). Among the 176 D-loop sequences, there were 286 polymorphic sites, including 115 variation sites and 59 parsimony informative sites. Overall, 41 haplotypes were defined among 176 Culter alburnus individuals. C.alburnus populations in the Pearl River were being a high haplotypic diversity index (Hd= 0.875 06) and low nucleotide diversity index (π=0.007 00). The AMOVA (analysis of molecular variance) index of total populations was 0188 28, indicating that the genetic differentiation among populations was moderate. It was predicted that differentiation time was about 50×103years. FSTindex between WZ and GP, WZ and ZQ, ZP and PL, TY and PG, especially, FS and LC, GP, TY, SG, was showed significant genetic differences (FST>025). The Phylogenetic tree and the Median joining drawing showed that haplotype 1 and 2 were the ancestors of other haplotypes. The relationship between genetic distance and geographical distance should be explored in the future.关键词：The Pearl River;Culter alburnus;D-loop;genetic diversity;genetic differentiation
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发布时间：2023-12-11 - 摘要：Tilapia samples were collected from five main tilapia farms in Guangdong. The characteristics of the isolates were determined by virulence gene detection, Multilocus Sequencing Type (MLST), and PulsedField Gel Electrophoresis (PFGE). The frequency of virulence gene in all isolates varied from 60.59% to 100%. Ten distribution patterns of virulence gene were identified, dltR-bca-sodA-spb1-cfb-bac (38.24%,65/170), dltr-bca-sodA-spb1-bac (23.53%，40/170), and dltr-bca-sodA-spb1-cfb-bac-scpB (22,35%,38/170) were the predominant patterns, followed by dltr-bca-sodA-spb1-bac-scpb (8.24%, 14/170) and dltr-bca-sodA-spb1 (4.71%, 8/170). The single allele was observed in each of seven loci, adhP（10）, pheS（1）, atr（2）, glnA（1）, sdhA（3）, glcK（2）, tkt（2）and result in unique ST 7 (Sequencing Type 7). One hundred and fortysix isolates were assigned to six clusters based on the PFGE results. The similarity between these clusters ranged from 86% to 100%. Cluster A (18), B (16), C (103) and D (7) were the predominant clusters, account for 98.63% of all isolates. Cluster A and C were distributed in all four areas, Cluster B were mainly isolated from Wuchuan, Maoming and Yangjiang, whereas Cluster D were isolated from Maoming, Zhuhai and Yangjiang. The unique clusters F and G were isolated from Maoming and Zhuhai, respectively. In addition, the clones in Clusters A--D isolated from different areas in Guangdong showed 100% similarity. High proportion of strains with virulence gene was observed in Streptococcus agalactiae strains isolated from tilapia farm in Guandong. All of isolates belonged to the unique ST7. The clones with 100% similarity were identified in different area suggesting the cross infection and transmission in Guangdong, China.关键词：tilapia;Streptococcus agalactiae;virulence gene;MLST;PFGE
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发布时间：2023-12-11 - 摘要：In this study, DNA cytosine methylation modification level and MSAP amplification graphs of Lycoris longituba were obtained from seed embryo, callus and seedling via methylation sensitive amplification polymorphism technology. We found that 51 pairs of MSAP selective amplifying primer combinations were good in 64 pairs of the MSAP selective amplifying primer combinations.The results showed that the cytosine methylation rates were 68.0% in seed embryo (full methylation:50.2% and half methylation:49.8%), 60.0% in callus(full methylation:52.2% and half methylation:47.8%) and 64.3% in seeding(full methylation:40.8% and half methylation:59.2%).The level of methylation differed with each other in the three different statges. So, it is suggested that changes of the level of methylation may had led to their different organs of Lycoris longituba based on the modification mechanism of super methylation/demethylation analysis.关键词：Lycoris longituba;MSAP;organogenesis
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发布时间：2023-12-11 - 摘要：Using lipase to change waste cooking oil into biodiesel can achieve the goal of green, recycling of food waste. A gene encoding Rhizopus oryzae lipase containing prosequence(ProROL) was cloned into the pGAPZαA and electrotransformed into the Pichia pastoris X-33 strain. The lipase was functionally expressed and secreted with a molecular weight of 35 000. The lipase activity was (426.6±0.8) U/mL when using olive oil as substract. Using waste cooking oil as the raw material and alcohol as acyl receptor, lipase as catalyst for the production of fatty acid ethyl ester, 49% of the fatty acid ethyl ester yield was obtained when the water content is 5%, the alcohol oil molar ratio is 4∶1, and lipase adding amount is 10%, under this condition the fatty acid ethyl ester yield is 49%.关键词：food waste;biodiesel;Rhizopus oryzae;lipase;Pichia pastoris
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发布时间：2023-12-11 - 摘要：In this study, a two-dimensional water dynamic and water quality model based on MIKE21 was developed to simulate the water quality at the intake of Dongshen water supply project. The study was carried out in the tidal reach between the Dongjiang HydroProject and Shilong in the downstream of the Dongjiang River, and NH-3-N was taken as the water quality indicator. Different scenarios of flood discharge from the Shima River and the release discharge of the Dongjiang Hydro-Project were used to drive the model for the simulation of the water quality at the intake of the Dongshen water supply project. The results indicate that: ① the change of the NH-3-N concentration at the intake is related to the tidal change, the NH-3-N concentration over-standard occurs during higher high water level period; ② flood tide is the main factor which impacts the water quality at the intake, and the NH-3-N concentration is more than 0.5mg/L during higher high water lever period; ③ more flood discharge from Shima River has the greater effect on the water quality, and the water regulation of the Dongjiang Hydro-Project can cause a significant improvement on water quality in the downstream. The results of this study contribute to the decision-making for the joint operation of the flood discharge from Shima River and the intake of Dongshen water supply project, also have great significance for the emergency operation of the Dongjiang Hydro-Project.关键词：reservoir regulation;flood discharge;MIKE21 model;Shima River;Dongjiang River
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发布时间：2023-12-11 - 摘要：Drought is perhaps the most complex natural hazard. Drought monitoring is an essential component of drought risk management. It is usually performed with the use of various drought indices. A number of drought indices have been introduced and applied in the drought monitoring in different regions to date all over the world. Xinjiang was divided into five sub-regions with Fuzzy Clustering Method along with considering its geographic and geomorphic conditions and different vapor sources: northern Xinjiang, southern Xinjiang, northern slope of Tianshan Mountain, southern slope of Tianshan Mountain, and the eastern part of Tianshan Mountain. Comparability analyses and correlation analyses have been carried out between the Standardized Precipitation Index (SPI), the Standardized Precipitation Evapotranspiration Index (SPEI), the Effective Drought Index (EDI), and the Self-calibrating PDSI (scPDSI) to investigate advantages and disadvantages of four drought indices and to pick out the most applicable drought index for the five sub-regions in Xinjiang based on daily precipitation and temperature data from 50 meteorological stations in Xinjiang. SPI, SPEI, and EDI respond quickly to precipitation and temperature. The tendency and changing characteristics were in consistent with each other. Drought classes and wet classes defined with SPI are higher and lower than with EDI, respectively. Since SPEI can take into account of combined action of precipitation and temperature in the evaluation of drought and wet, some severe droughts that cannot be detected with SPI and scPDSI can be monitored with SPEI. The correlation between SPI and EDI is better than it between SPEI and EDI. The difference of variation tendency between SPI, SPEI, EDI and scPDSI is very large and the relationship between scPDSI and other drought indices is worst. Therefore, scPDSI is not applicable to drought monitoring in Xinjiang. In addition, drought frequency, drought severity, drought stations proportion of different classes of annual and seasonal drought have been analyzed with SPEI12. No matter annual or seasonal droughts, there are obvious regional and seasonal characteristics. And the influence area has been reduced to an extent.关键词：drought monitoring;meteorological drought indices;correlation analysis;Xinjiang
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发布时间：2023-12-11 - 摘要：Teleconnections between El Nio/Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Indian Ocean Dipole (IOD) and Pacific Decadal Oscillation (PDO) and seasonal and annual precipitation regimes over the Pearl River basin have been analyzed based on the Rotated Empirical Orthogonal Functions decomposing the seasonal and annual precipitation into temporal and the associated spatial patterns. Furthermore, changes in the seasonal and annual occurrence and intensity of wet days linked to the ENSO, NAO, IOD and PDO indices have also been investigated to discover the influences of the climate indices on precipitation regimes. The results show that: ① ENSO and NAO are the leading driving factors for seasonal and annual precipitation variability over the Pearl River basin. The spring precipitation is positively related with NAO and PDO, and is negatively related with ENSO and IOD. The summer precipitation is negatively related with NAO. The autumn precipitation is positively related with ENSO and IOD. The winter precipitation is positively related with ENSO and NAO. And the annual precipitation is positively related with NAO and IOD. ② ENSO, NAO, IOD and PDO affect seasonal and annual precipitation mainly by changing the occurrence and intensity of wet days in the Pearl River basin, and this effect has seasonal differences.关键词：climate indices;precipitation regimes;Rotated Empirical Orthogonal Functions;ENSO;Pearl River basin
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发布时间：2023-12-11 - 摘要：Based on the monthly rain gauge data (1960-2010) from 20 stations in Hunan Province, the interdecadal change of winter precipitation over Hunan and its physical factors are investigated. The results indicate that there were two abrupt changes of winter precipitation, which appeared in 1988 and 1998, respectively. The precipitation was less during the years of 1973-1987 and 1998-2009, while the precipitation was more during the years of 1988-1997. The interdecadal change of winter precipitation in Hunan was attributed to the collaborative variations of Siberian High, Arctic Oscillation, the East Asian jet stream and Eurasian teleconnection pattern. During the 1988-1997 period, the intensity of Siberian High and the East Asian jet stream was weaker, Arctic Oscillation index was higher, and the Eurasian teleconnection pattern was in the negative phase. The aforementioned factors worked cooperatively to induce more precipitation. During the periods of 1973-1987 and 1998-2009, these factors showed roughly opposite changes, resulting in less winter rainfall.关键词：winter precipitation;Hunan;EOF analysis;interdecadal change
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发布时间：2023-12-11 - 摘要：The black-box model based on multivariate hybrid linear regression is applied for waterlevel simulation of the upper and middle reaches of the Heilongjiang mainstream, including the Mohe station, the Oupu station, the Sandaoka station, the Changfatun station, the Wuyun station, and the Qindeli station. The model structure is determined by AIC and DW method; parameters of the model are estimated by the least square method. The models are calibrated with day timescale hydrologic data of 2006-2010 in the flood season(May to September), and verified with day time-scale hydrologic data in the flood season(May to September) in 2011. And the model's uncertainty and parameters sensivitity are analyzed. The results are as follows: ① The model is applied well in the Heilongjiang mainstream and accurate within acceptable range. Forecast schemes-pass rate reaches more than 85% and coefficients of determination are above 0.97 for six stations. The model can be used for water-level forecasting. ② The paper quantifies uncertainty of the Multivariate hybrid linear regression model results using the Monte Carlo methods. The larger the standard deviation, the more uncertain the flood hydrograph forecasting, and thus model is more uncertain. The parameters-sensitivity analysis based on standardized regression coefficients shows that the parameters with minimum values in time order of mainstream are the most sensitive, the parameters with minimum values in time order of tributary take the second place, and the parameters with higher values in time order are less sensitive.关键词：water-level forecasting;mixed linear regression;Heilongjiang mainstream;uncertainty analysis;Monte Carlo
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发布时间：2023-12-11
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