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Synergistic effects of multiple driving factors on the runoff variations in the Yellow River Basin,China 被引量:4
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作者 WANG Junjie SHI Bing +2 位作者 ZHAO Enjin CHEN Xuguang YANG Shaopeng 《Journal of Arid Land》 SCIE CSCD 2021年第8期835-857,共23页
River runoff plays an important role in watershed ecosystems and human survival,and it is controlled by multiple environmental factors.However,the synergistic effects of various large-scale circulation factors and met... River runoff plays an important role in watershed ecosystems and human survival,and it is controlled by multiple environmental factors.However,the synergistic effects of various large-scale circulation factors and meteorological factors on the runoff on different time-frequency scales have rarely been explored.In light of this,the underlying mechanism of the synergistic effects of the different environmental factors on the runoff variations was investigated in the Yellow River Basin of China during the period 1950-2019 using the bivariate wavelet coherence(WTC)and multiple wavelet coherence(MWC)methods.First,the continuous wavelet transform(CWT)method was used to analyze the multiscale characteristics of the runoff.The results of the CWT indicate that the runoff exhibited significant continuous or discontinuous annual and semiannual oscillations during the study period.Scattered inter-annual time scales were also observed for the runoff in the Yellow River Basin.The meteorological factors better explained the runoff variations on seasonal and annual time scales.The average wavelet coherence(AWC)and the percent area of the significant coherence(PASC)between the runoff and individual meteorological factors were 0.454 and 19.89%,respectively.The circulation factors mainly regulated the runoff on the inter-annual and decadal time scales with more complicated phase relationships due to their indirect effects on the runoff.The AWC and PASC between the runoff and individual circulation factors were 0.359 and 7.31%,respectively.The MWC analysis revealed that the synergistic effects of multiple factors should be taken into consideration to explain the multiscale characteristic variations of the runoff.The AWC or MWC ranges were 0.320-0.560,0.617-0.755,and 0.819-0.884 for the combinations of one,two,and three circulation and meteorological factors,respectively.The PASC ranges were 3.53%-33.77%,12.93%-36.90%,and 20.67%-39.34%for the combinations one,two,and three driving factors,respectively.The combinations of precipitation,evapotranspiration(or the number of rainy days),and the Arctic Oscillation performed well in explaining the variability in the runoff on all time scales,and the average MWC and PASC were 0.847 and 28.79%,respectively.These findings are of great significance for improving our understanding of hydro-climate interactions and water resources prediction in the Yellow River Basin. 展开更多
关键词 synergistic effects PRECIPITATION runoff variations atmospheric circulations multiple wavelet coherence Yellow River Basin
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Interannual Variation of Multiple Tropical Cyclone Events in the Western North Pacific 被引量:4
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作者 高建芸 李天明 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2012年第6期1279-1291,共13页
The interannual variability of occurrence of multiple tropical cyclone (MTC) events during June-October in the western North Pacific (WNP) was examined for the period 1979-2006. The number of the MTC events ranged... The interannual variability of occurrence of multiple tropical cyclone (MTC) events during June-October in the western North Pacific (WNP) was examined for the period 1979-2006. The number of the MTC events ranged from 2 to 9 per year, exhibiting a remarkable year-to-year variation. Seven active and seven inactive MTC years were identified. Compared to the inactive years, tropical cyclone genesis locations extended farther to the east and in the meridional direction during the active MTC years. A composite analysis shows that inactive MTC years were often associated with the E1 Nifio decaying phase, as warm SST anomalies in the equatorial eastern-central Pacific in the preceding winter transitioned into cold sea surface temperature (SST) anomalies in the concurrent summer. Associated with the SST evolution were suppressed low-level cyclonic vorticity and weakened convection in the WNP monsoon region. In addition to the mean flow difference~ significant differences between active and inactive MTC years were also found in the strength of the atmospheric intraseasonal oscillation (ISO). Compared with inactive MTC years, ISO activity was much stronger along the equator and in the WNP region during active MTC years. Both westwardand northward-propagating ISO spectrums strengthened during active MTC years compared to inactive years. The combined mean state and ISO activity changes may set up a favorable environment for the generation of MTC events. 展开更多
关键词 multiple tropical cyclone events interannual variation
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A New Method for the Detections of Multiple Faults Using Binary Decision Diagrams 被引量:1
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作者 PAN Zhongliang CHEN Ling ZHANG Guangzhao 《Wuhan University Journal of Natural Sciences》 CAS 2006年第6期1943-1946,共4页
With the complexity of integrated circuits is continually increasing, a local defect in circuits may cause multiple faults. The behavior of a digital circuit with a multiple fault may significantly differ from that of... With the complexity of integrated circuits is continually increasing, a local defect in circuits may cause multiple faults. The behavior of a digital circuit with a multiple fault may significantly differ from that of a single fault. A new method for the detection of multiple faults in digital circuits is presented in this paper, the method is based on binary decision diagram (BDD). First of all, the BDDs for the normal circuit and faulty circuit are built respectively. Secondly, a test BDD is obtained by the XOR operation of the BDDs corresponds to normal circuit and faulty circuit. In the test BDD, each input assignment that leads to the leaf node labeled 1 is a test vector of multiple faults. Therefore, the test set of multiple faults is generated by searching for the type of input assignments in the test BDD. Experimental results on some digital circuits show the feasibility of the approach presented in this paper. 展开更多
关键词 digital circuits multiple faults fault detection binary decision diagrams
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Construction of the Intelligent and Multiple Object Decision Support System for Making Train Diagram 被引量:1
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作者 彭其渊 席庆 阎海峰 《Journal of Modern Transportation》 1999年第2期125-132,共8页
Multiple objects decision is used widely in many complex fields. In this paper an idea is provided to construct a train diagram intelligent multiple objects decision support system (TDIMODSS). And the reference point ... Multiple objects decision is used widely in many complex fields. In this paper an idea is provided to construct a train diagram intelligent multiple objects decision support system (TDIMODSS). And the reference point method is used to solve the complicated and large scale problems of making and adjusting train schedule. This paper focuses on the principle and framework of the model base, knowledge base of train diagram. It is shown that the TDIMODSS can solve the problems and their uncertainty in making train diagram, and can combine the expert knowledge, experience and judgement of a decision maker into the system. In addition to that, a friendly working environment is also presented, which brings together the human judgement, the adaptability to environment and the computerised information. 展开更多
关键词 train diagram COMPUTER multiple objects intelligent decision support system
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Pathogenic Variation and Occurrence of Multiple Resistance-Breaking <i>Rice yellow mottle virus</i>Strains in Tanzania
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作者 Judith Hubert Herman J. F. Lyimo Ashura Luzi-Kihupi 《American Journal of Plant Sciences》 2017年第8期1820-1841,共22页
Rice yellow mottle virus (RYMV) is a major biotic constraint for rice production in Africa. The resistance-breaking ability of Tanzanian RYMV strains and phylotypes (S4lm (Tz526), S4lv (Tz516), S4ug (Tz508), S5 (Tz429... Rice yellow mottle virus (RYMV) is a major biotic constraint for rice production in Africa. The resistance-breaking ability of Tanzanian RYMV strains and phylotypes (S4lm (Tz526), S4lv (Tz516), S4ug (Tz508), S5 (Tz429, Tz445), S6c (Tz486) and S6w (Tz539)) were tested by inoculating rice cultivars with RYMV1 resistant alleles (Gigante (rymv1-2), Tog12387 (rymv1-3), Tog5681 (rymv1-3), Tog5438 (rymv1-4), Tog5672 (rymv1-4+rymv2) and Tog5674 (rymv 1-5)) in a screen house. The results revealed multiple resistance-breaking strains and phylotypes on resistant cultivars Gigante, Tog12387, Tog5438 and Tog5681. However, the resistance breakdown was highly variable depending on the strain used, and disease severity ranged from 11% - 75.3%. The virulence potential of RYMV phylotype S4lm (Tz526) was similar to phylotype S6w (Tz539). The impact of strains and phylotypes on yield and its components in rice cultivars revealed highly significant differences (P ≤ 0.001). The lowest percent plant height reduction (2.8%), number of tillers per plant (2.5%), 1000 grain weight (2.7%), spikelet sterility (3.5%) and yield (5%) was recorded in rice cultivar Gigante inoculated with RYMV phylotype S6c (Tz486). Phylotype S6c (Tz486) despite being less virulent compared to other strains, its virus titer in rice cultivar Gigante (1.833) was higher than S5 (Tz429, Tz445) inoculated on Tog5674 (0.171, 0.207) and S6w (Tz539) inoculated on Tog5681 (0.283). The resistant-breaking strain S5 (Tz445) multiplied in resistant rice cultivar Tog5674 without inducing visible symptoms but showed positive reaction to ELISA with low virus titer. The strain S5 overcame wide range of resistant alleles including rymv1-2, rymv1-3, rymv1-4 and rymv1-5 resistance, with exception of rymv1-4 + rymv2. The current results gave a new perspective for future identification of resistance-breaking mutations through sequencing of the RYMV genome in infected rice cultivars and mutagenesis of an infectious viral clone useful for future RYMV resistant breeding programs. 展开更多
关键词 Pathogenic variation VIRULENCE multiple Resistance-Breaking RYMV STRAINS Yield Losses Tanzania
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The trend on runoff variations in the Lhasa River Basin 被引量:19
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作者 LIN Xuedong ZHANG Yili +5 位作者 YAO Zhijun GONG Tongliang WANG Hong CHU Duo LIU Linshan ZHANG Fei 《Journal of Geographical Sciences》 SCIE CSCD 2008年第1期95-106,共12页
Taking the Lhasa River Basin above Lhasa hydrological station in Tibetan Plateau as a study area, the characteristics of the annual and monthly mean runoff during 1956-2003 were analyzed, based on the hydro-data of th... Taking the Lhasa River Basin above Lhasa hydrological station in Tibetan Plateau as a study area, the characteristics of the annual and monthly mean runoff during 1956-2003 were analyzed, based on the hydro-data of the two hydrological stations (Lhasa and Tanggya) and the meteorological data of the three meteorological stations (Damxung, Lhasa and Tanggya). The trends and the change points of runoff and climate from 1956 to 2003 were detected using the nonparametric Mann-Kendall test and Pettitt-Mann-Whitney change-point statistics. The correlations between runoff and climate change were analyzed using multiple linear regression. The major results could be summarized as follows: (1) The annual mean runoff during the last 50 years is characterized by a great fluctuation and a positive trend with two change points (around 1970 and the early 1980s), after which the runoff tended to increase and was increasing intensively in the last 20 years. Besides, the monthly mean runoff with a positive trend is centralized in winter half-year (November to April) and some other months (May, July and September). (2) The trends of the climate change in the study area are generally consistent with the trend of the runoff, but the leading climate factors which aroused the runoff variation are distinct. Precipitation is the dominant factor influencing the annual and monthly mean runoff in summer half year, while temperature is the primary factor in winter season. 展开更多
关键词 Lhasa River Basin trend of runoff variation Pettitt change-point test Mann-Kendall trend analysis multiple linear regressions
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MULTIPLE SOLUTIONS FOR AN INHOMOGENEOUS SEMILINEAR ELLIPTIC EQUATION IN R^N 被引量:1
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作者 邓引斌 李亦 赵学进 《Acta Mathematica Scientia》 SCIE CSCD 2003年第1期1-15,共15页
In this paper, the authors study the existence and nonexistence of multiple positive solutions for problem(*)μwhere h ∈ H-1(RN), N ≥ 3, |f(x,u)| ≤ C1up-1 + C2u with C1 > 0, C2∈ [0,1) being some constants and 2... In this paper, the authors study the existence and nonexistence of multiple positive solutions for problem(*)μwhere h ∈ H-1(RN), N ≥ 3, |f(x,u)| ≤ C1up-1 + C2u with C1 > 0, C2∈ [0,1) being some constants and 2 < p < ∞. Under some assumptions on f and h, they prove that there exists a positive constant μ* <∞ such that problem (*)μ has at least one positive solution uμ if μ,∈ (0,μ*), there are no solutions for (*)μ if μ, > μ* and uμ is increasing with respect to μ∈ (0,μ*); furthermore, problem (*)μ has at least two positive solution for μ ∈ (0,μ*) and a unique positive solution for μ, =μ* if p ≤2N/N-2. 展开更多
关键词 multiple solutions variational method elliptic equations
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Multiquadric Radial Basis Function Approximation Scheme for Solution of Total Variation Based Multiplicative Noise Removal Model 被引量:1
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作者 Mushtaq Ahmad Khan Ahmed BAltamimi +4 位作者 Zawar Hussain Khan Khurram Shehzad Khattak Sahib Khan Asmat Ullah Murtaza Ali 《Computer Modeling in Engineering & Sciences》 SCIE EI 2021年第1期55-88,共34页
This article introduces a fastmeshless algorithm for the numerical solution nonlinear partial differential equations(PDE)by Radial Basis Functions(RBFs)approximation connected with the Total Variation(TV)-basedminimiz... This article introduces a fastmeshless algorithm for the numerical solution nonlinear partial differential equations(PDE)by Radial Basis Functions(RBFs)approximation connected with the Total Variation(TV)-basedminimization functional and to show its application to image denoising containing multiplicative noise.These capabilities used within the proposed algorithm have not only the quality of image denoising,edge preservation but also the property of minimization of staircase effect which results in blocky effects in the images.It is worth mentioning that the recommended method can be easily employed for nonlinear problems due to the lack of dependence on a mesh or integration procedure.The numerical investigations and corresponding examples prove the effectiveness of the recommended algorithm regarding the robustness and visual improvement as well as peak-signal-to-noise ratio(PSNR),signal-to-noise ratio(SNR),and structural similarity index(SSIM)corresponded to the current conventional TV-based schemes. 展开更多
关键词 Denoised image multiplicative and speckle noises total variation(TV)filter Euler-Lagrange restoration equation multiquadric radial basis functions meshless and mesh-based schemes
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Diagrams Produced by Secondary Students in Multiplicative Comparison Word Problems 被引量:1
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《Journal of Mathematics and System Science》 2014年第2期83-92,共10页
关键词 中学生 应用题 乘法 制作 启发式策略 数学问题 数据对象 图表
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A Fast Total Variation Algorithm for Multiplicative Noise Removal
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作者 JIN Zheng-meng LI Zhi-xin 《南京邮电大学学报(自然科学版)》 2011年第5期124-128,共5页
In this paper,based on the work in[5],some theoretical analysis on a variational model for multiplicative noise removal is further studied.Moreover,the primal-dual technique is incorporated to design a fast algorithm ... In this paper,based on the work in[5],some theoretical analysis on a variational model for multiplicative noise removal is further studied.Moreover,the primal-dual technique is incorporated to design a fast algorithm for the variational model.Some numerical results are presented to illustrate the efficiency of the 展开更多
关键词 calculus of variation weak solutions BV primal-dual technique multiplicative noise image restoration
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Multiple internal resonances of rotating composite cylindrical shells under varying temperature fields
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作者 Yunfei LIU Jun WANG +2 位作者 Jiaxin HU Zhaoye QIN Fulei CHU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2022年第10期1543-1554,共12页
Composite cylindrical shells,as key components,are widely employed in large rotating machines.However,due to the frequency bifurcations and dense frequency spectra caused by rotation,the nonlinear vibration usually ha... Composite cylindrical shells,as key components,are widely employed in large rotating machines.However,due to the frequency bifurcations and dense frequency spectra caused by rotation,the nonlinear vibration usually has the behavior of complex multiple internal resonances.In addition,the varying temperature fields make the responses of the system further difficult to obtain.Therefore,the multiple internal resonances of composite cylindrical shells with porosities induced by rotation with varying temperature fields are studied in this paper.Three different types of the temperature fields,the Coriolis forces,and the centrifugal force are considered here.The Hamilton principle and the modified Donnell nonlinear shell theory are used to obtain the equilibrium equations of the system,which are transformed into the ordinary differential equations(ODEs)by the multi-mode Galerkin technique.Thereafter,the pseudo-arclength continuation method,which can identify the regions of instability,is introduced to obtain the numerical results.The detailed parametric analysis of the rotating composite shells is performed.Multiple internal resonances caused by the interaction between backward and forward wave modes and the energy transfer phenomenon are detected.Besides,the nonlinear amplitude-frequency response curves are different under different temperature fields. 展开更多
关键词 multiple internal resonances rotation effect nonlinear temperature variation multi-mode Galerkin technique pseudo-arclength continuation method coupled effect
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Dominant early heading without yield drag in a sister-line BC breeding progeny DEH_229 is controlled by multiple genetic factors with maineffect loci
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作者 Muhiuddin Faruquee Qiang Zhang +7 位作者 Lubiao Zhang Linyun Xu Wensheng Wang Jiansan Chen Jianlong Xu Zhikang Li Binying Fu Tianqing Zheng 《The Crop Journal》 SCIE CSCD 2021年第2期400-411,共12页
Dominant early heading(DEH)in rice(Oryza sativa L.)is of interest in both breeding and genetics.The genetic mechanisms underlying DEH have remained largely unclear.We have developed a near-isogenic DEH line without yi... Dominant early heading(DEH)in rice(Oryza sativa L.)is of interest in both breeding and genetics.The genetic mechanisms underlying DEH have remained largely unclear.We have developed a near-isogenic DEH line without yield drag named DEH_229 by sister-line backcross(BC)breeding with MH63,a restorer,as the genetic background.We conducted a pilot genetic investigation under both short-day(SD)and long-day(LD)conditions.The DEH line harbored only 1.06%variation in the genome sequence relative to MH63.The variants were distributed throughout the genome.Using QTL mapping by sequencing(QTL-seq)on an F_(2) population derived from a cross of MH63×DEH_229,57 loci were detected under the SD condition.Joint mapping employing a genome-wide association study with accessions from the 3000 rice genome sequencing project(3K-RG),reduced the number of QTL by 43.9%.Using Rice Functional Genomics&Breeding(RFGB)database,the number of SNP cluster regions within the QTL regions reduced by 27.3%.Further comparison of the genome variation between DEH_229 and MH63 in addition to gene annotation information revealed a new DEH allele of DTH3 with multiple variable sites as a possible major factor underlying the early-heading phenotype of DEH_229.An InDel marker,ZMEH_1,was designed based on the variation between DEH_229 and MH63 within this region.It accounted for 86.0%of heading date variation under both SD and LD conditions in 109 randomly chosen progeny derived from extreme lines of the MH63×DEH_229 population.This study reveals the genetic complexity of DEH in the near-isogenic line and may provide useful material and marker information for plant molecular breeding. 展开更多
关键词 Dominant early heading Yield drag Sister-line BC breeding multiple genetic factors Cryptic genetic variation(CGV) Rice(Oryza sativa L.)
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Diagrams Present in the Resolution of Problems of Multiplicative Comparison with High School Students
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作者 Fany M.Gonzalez Barrios 《Journal of Mathematics and System Science》 2019年第3期90-94,共5页
The purpose of this study is to identify the use(or not)of diagrams when solving problems of multiplicative comparison in eighth-grade students of the Rafael Antonio Moreno secondary school located in Macaracas,provin... The purpose of this study is to identify the use(or not)of diagrams when solving problems of multiplicative comparison in eighth-grade students of the Rafael Antonio Moreno secondary school located in Macaracas,province of Los Santos-Panama.The methodology used is mixed and descriptive with a non-experimental design.As an instrument,a written test consisting of two parts(part a and part b)is prepared,which is applied to eighth-grade students who take the mathematics subject of said study center. 展开更多
关键词 Problem solving diagramS multiplICATIVE COMPARISON
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Practical Application of Two-Way Multiple Overlapping Relationships in a BDM Network
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作者 Seon-Gyoo Kim 《Journal of Civil Engineering and Architecture》 2016年第12期1318-1328,共11页
关键词 网络技术 BDM 应用 调度程序 建设项目 地下公用设施 EXCEL 直线图解法
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Existence and Multiplicity of Positive Solutions to Quasilinear Elliptic Systems Involving Multiple Hardy-Type Terms and Concave-Convex Nonlinearities
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作者 Tsing-San Hsu 《Journal of Mathematics and System Science》 2013年第3期150-161,共12页
关键词 半线性椭圆系统 非线性 拟线性 正解 多重性 HARDY不等式 奇异系统 分析技巧
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基于特征图像组合与改进ResNet-18的电能质量扰动识别方法
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作者 张逸 欧杰宇 +1 位作者 金涛 毕贵红 《中国电机工程学报》 EI CSCD 北大核心 2024年第7期2531-2544,I0003,共15页
针对传统电能质量扰动(power quality disturbance,PQD)识别体系中单一图像特征信息受限与算法识别能力不足等问题,依据特征融合的思想,提出一种基于特征图像组合与改进ResNet-18的PQD识别方法。首先,对PQD信号进行变分模态分解(variati... 针对传统电能质量扰动(power quality disturbance,PQD)识别体系中单一图像特征信息受限与算法识别能力不足等问题,依据特征融合的思想,提出一种基于特征图像组合与改进ResNet-18的PQD识别方法。首先,对PQD信号进行变分模态分解(variational mode decomposition,VMD)得到一系列固有模态函数(intrinsic mode functions,IMFs)与残差分量;其次,将IMFs、残差分量、原始扰动信号与Subtract分量纵向拼接成分量矩阵,利用信号-图像转化方法生成特征分量彩色图;再次,对原始扰动信号进行连续小波变换(continuous wavelet transform,CWT)生成小波时-频图;最后,将特征分量彩色图与小波时-频图组合输入改进的六通道ResNet-18中训练学习并完成扰动识别。通过仿真对PQD识别方法进行分析并将其与目前常用识别体系进行比较。结果表明,所提方法具有较好的抗噪性能并且能够更好地提取PQD特征信息,达到更高的识别准确率。 展开更多
关键词 电能质量扰动 变分模态分解 特征分量彩色图 小波时-频图 残差网络
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一种基于稀疏重构的多视角MIMO雷达关联成像算法研究
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作者 张弓 田雨薇 +1 位作者 袁家雯 张宇 《系统工程与电子技术》 EI CSCD 北大核心 2024年第2期470-477,共8页
为改善复杂目标的成像表现、提升雷达图像的视觉效果,提出一种基于稀疏重构的多视角多输入多输出(multiple input multiple output,MIMO)雷达关联成像方法,设计了多视角雷达散射面积(radar cross section,RCS)起伏的稀疏重构关联成像模... 为改善复杂目标的成像表现、提升雷达图像的视觉效果,提出一种基于稀疏重构的多视角多输入多输出(multiple input multiple output,MIMO)雷达关联成像方法,设计了多视角雷达散射面积(radar cross section,RCS)起伏的稀疏重构关联成像模型。所提算法能提高辐射场信号随机性,改善复杂目标雷达关联成像参考信号与回波之间相关性退化的情况,减小多视角RCS起伏对相关性的影响,提升多视角下的关联成像质量。最后,通过仿真验证了所提方法的有效性。 展开更多
关键词 雷达成像 多输入多输出 雷达关联成像 正则化 全变差
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基于变分图自动编码器与K均值聚类的虚拟网络嵌入算法应用
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作者 姚丽敏 《哈尔滨师范大学自然科学学报》 CAS 2024年第1期47-54,共8页
将虚拟网络映射到物理网络是网络功能虚拟化中一项重要的任务.为了有效地分配虚拟网络请求,需要将虚拟网络嵌入到物理网络拓扑中.然而,由于虚拟网络的复杂性和物理网络的限制,这一任务变得非常具有挑战性.鉴于此,研究在现有虚拟网络嵌... 将虚拟网络映射到物理网络是网络功能虚拟化中一项重要的任务.为了有效地分配虚拟网络请求,需要将虚拟网络嵌入到物理网络拓扑中.然而,由于虚拟网络的复杂性和物理网络的限制,这一任务变得非常具有挑战性.鉴于此,研究在现有虚拟网络嵌入算法(Virtual Network Embedding, VNE)模型基础上进行改进,融入了变分图自动编码器(Variational Graph Auto-Encoders, VGAE),提出了一种新型虚拟网络嵌入算法模型.通过编码器对虚拟网络的嵌入特征进行提取,随后利用K-means聚类算法对所得到的嵌入特征进行分类,最终得到合适的嵌入分配方法.实验结果表明,该新模型相较于其他同类型的嵌入算法性能表现最佳,稳定性最好,其平均嵌入请求接受率为60%,长期平均CPU资源利用率最高达97%.综上所述,研究提出的新型虚拟网络嵌入算法在资源利用率和嵌入质量方面表现出色,能够有效应对复杂的网络环境和大规模的虚拟网络请求. 展开更多
关键词 虚拟网络 变分图自动编码器 K-MEANS 嵌入算法 特征分配
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NaHCO_(3)溶液浓度改变引起的支配质子转移反应变化:从HCO_(3)^(-)质子自递反应到HCO_(3)^(-)水解反应
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作者 柳青 刘建宇 王海水 《大学化学》 CAS 2024年第1期305-308,共4页
NaHCO_(3)水溶液中存在多个质子转移反应和多重化学平衡。随溶液浓度改变,各质子反应所占的相对比重将发生变化,与质子转移相关的产物H_(2)CO_(3)、H^(+)、OH^(-)和CO_(3)^(2-)的相对含量也会发生变化。绘制了[H_(2)CO_(3)]、[H^(+)]、[... NaHCO_(3)水溶液中存在多个质子转移反应和多重化学平衡。随溶液浓度改变,各质子反应所占的相对比重将发生变化,与质子转移相关的产物H_(2)CO_(3)、H^(+)、OH^(-)和CO_(3)^(2-)的相对含量也会发生变化。绘制了[H_(2)CO_(3)]、[H^(+)]、[OH^(-)]和[CO_(3)^(2-)]随溶液浓度c变化的动态图。从动态图上,可以直观地观察到哪些酸碱组分是主要组分,哪些组分是次要组分。较浓溶液中,[H_(2)CO_(3)]≈[CO_(3)^(2-)]>>[OH^(-)]>>[H^(+)],表明能够产生H^(+)或OH^(-)的质子反应占据次要地位,质子反应HCO_(3)^(-)+HCO_(3)^(-)-H_(2)CO_(3)+CO_(3)^(2-)占据支配地位。9.1×10^(-6) mol-L^(-1)溶液中,[OH^(-)]≈[H_(2)CO_(3)]>>[H^(+)]≈[CO_(3)^(2-)],表明质子反应H_(2)O+HCO_(3)^(-)-H_(2)CO_(3)+OH^(-)占据支配地位。极稀溶液中,[OH^(-)]≈[H^(+)]>>[H_(2)CO_(3)]>[CO_(3)^(2-)],表明H_(2)O-H^(+)+OH^(-)占据支配地位。溶液的酸碱性质主要由起支配作用的质子转移反应控制。 展开更多
关键词 碳酸氢钠溶液 多重平衡 支配反应 反应产物含量图
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连续弯段溢洪道糙条消能工整流特性试验研究
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作者 马豪 牧振伟 +1 位作者 樊帆 顾元皓 《长江科学院院报》 CSCD 北大核心 2024年第3期71-78,共8页
为探究糙条消能工在连续弯段溢洪道上导流效果影响因子排序和糙条导流特性,采取9因素3水平的正交试验设计方案进行物理模型试验,引入超高变异系数C v对导流效果进行评价;对影响水流结构的因子进行量纲分析及多元回归处理,建立评价导流... 为探究糙条消能工在连续弯段溢洪道上导流效果影响因子排序和糙条导流特性,采取9因素3水平的正交试验设计方案进行物理模型试验,引入超高变异系数C v对导流效果进行评价;对影响水流结构的因子进行量纲分析及多元回归处理,建立评价导流效果的多因素影响模型。结果表明:糙条布设角度和糙条高度分别对2个弯段中水流结构影响最大,这2个因素直接影响糙条平衡水面差、稳定流态效果的优劣。剔除影响较小的共用因素,得出糙条消能工最优导流布置方案;各类函数模型中最大拟合优度为0.822,拟合方程对实测值进行对比验证,二者相对误差范围在2.78%~7.15%之间。研究成果可为连续弯段溢洪道整流分析提供理论参考。 展开更多
关键词 糙条消能工 连续弯段溢洪道 超高变异系数 正交设计 多元回归分析
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