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A fractal and scale-free model of complex networks with hub attraction behaviors

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Science China(Information Sciences) 2015年第1期58卷 178-187页

作者： KUANG li ZHENG BoJin li DeYi li yuanxiang SUN Yu State Key Laboratory of Software Engineering Computer SchoolWuhan University College of Computer Science South-Central University For Nationalities School of Software Tsinghua University School of Computer and Electronics and Information Guangxi University

It is widely believed that fractality of complex networks originate from hub repulsion behaviors(anticorrelation or disassortativity), which means that large degree nodes tend to connect with small degree *** hypothesis was demonstrated by a dynamical growth model, which evolves as the inverse renormalization procedure, proposed by Song et al. Now we find that the dynamical growth model is based on the assumption that all the cross-box links have the same probability e to link to the most connected nodes inside each ***, we modify the growth model by adopting the flexible probability e, which makes hubs to have higher probability to connect with hubs than non-hubs. With this model, we find that some fractal and scale-free networks have hub attraction behaviors(correlation or assortativity). The results are the counter-examples of former beliefs. Actually, the real-world collaboration network of movie actors also is fractal and shows assortative mixing.

关键词： scale-free fractal network self-similarity fractal dimension hub attraction

Transcriptome analysis of carotenoid biosynthesis in Dunaliella salina under red and blue light

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Journal of Oceanology and limnology 2020年第1期38卷 177-185,I0016-I0018页

作者： li yuanxiang CAI Xuehua GU Wenhui WANG Guangce Key Laboratory of Experimental Marine Biology Institute of OceanologyCenter for Ocean Mega-ScienceChinese Academy of SciencesQingdao 266071China Laboratory for Marine Biology and Biotechnology Qingdao National Laboratory for Marine Science and TechnologyQingdao 266071China College of Earth Sciences University of Chinese Academy of SciencesBeijing 100049China

The quality of light is an important abiotic factor that affects the growth and development of photosynthetic *** this study,we exposed the unicellular green alga Dunaliella salina to red(660 nm)and blue(450 nm)light and analyzed the cell growth,total carotenoid content,and *** growth of *** was enhanced by illumination with red light,whereas blue light was not able to promote the algal *** contrast,the total carotenoid content increased under both red and blue *** RNA of *** was sequenced and the transcriptomic response of algal cells to red and blue light was *** transcripts encoding for the blue light receptor cryptochrome were identified,and transcripts involved in the carotenoid metabolism were up-regulated under both red and blue *** encoding for photoprotective enzymes related to the scavenging of reactive oxygen species were up-regulated under blue *** present transcriptomic study provides a more comprehensive understanding of carotenoid biosynthesis in *** under different wavelengths of light.

关键词： blue light carotenoid Dunaliella red light transcriptome

Variational PCA fusion for Pan-sharpening very high resolution imagery

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Science China(Information Sciences) 2014年第11期57卷 100-109页

作者： ZHOU ZeMing MA Ning li yuanxiang YANG PingL ZHANG Peng li YunYing Institute of Meteorology and Oceanography PLA University of Science and Technology School of Aeronautics Shanghai JiaoTong University

The Pan-sharpening approach based on principle component analysis(PCA) is affected by severe spectral distortion. To address this problem, a new pan-sharpening model based on PCA and variational technique is proposed to construct the substitute image of the first principal component(PC1). The energy functional consists of three terms. The first term injects PC1 with the geometric structure of the panchromatic(Pan) image. The second term preserves the spectral pattern of the multi-spectral image in the merged *** the third term guarantees the smoothness of the functional optimization solution. The fusion result is given by the minimum of the energy functional, which is computed with the gradient descend flow. The experiments on QuickBird and IKONOS datasets validate the effectiveness of the proposed model. Compared with the stateof-the-art pan-sharpening approaches, this model exhibits a better trade-off between improving spatial quality and preserving spectral signature of the MS image.

关键词： PCA variational PCA fusion remote sensing image pan-sharpening gradient descend flow

Fast UAV path planning in urban environments based on three-step experience buffer sampling DDPG

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Digital Communications and Networks 2024年第4期10卷 813-826页

作者： Shasha Tian yuanxiang li Xiao Zhang Lu Zheng linhui Cheng Wei She Wei Xie College of Computer Science South-Central Minzu UniversityWuhan430074China Hubei Provincial Engineering Research Center for Intelligent Management of Manufacturing Enterprises Wuhan430074China School of Computer Science Wuhan UniversityWuhan430072China School of Mathematics&Statistics South-Central Minzu UniversityWuhan430074China

The path planning of Unmanned Aerial Vehicle(UAV)is a critical issue in emergency communication and rescue operations,especially in adversarial urban *** to the continuity of the flying space,complex building obstacles,and the aircraft's high dynamics,traditional algorithms cannot find the optimal collision-free flying path between the UAV station and the ***,in this paper,we study the fast UAV path planning problem in a 3D urban environment from a source point to a target point and propose a Three-Step Experience Buffer Deep Deterministic Policy Gradient(TSEB-DDPG)*** first build the 3D model of a complex urban environment with buildings and project the 3D building surface into many 2D geometric *** transformation,we propose the Hierarchical Learning Particle Swarm Optimization(HL-PSO)to obtain the empirical ***,to ensure the accuracy of the obtained paths,the empirical path,the collision information and fast transition information are stored in the three experience buffers of the TSEB-DDPG algorithm as dynamic guidance *** sampling ratio of each buffer is dynamically adapted to the training ***,we designed a reward mechanism to improve the convergence speed of the DDPG algorithm for UAV path *** proposed TSEB-DDPG algorithm has also been compared to three widely used competitors experimentally,and the results show that the TSEB-DDPG algorithm can archive the fastest convergence speed and the highest *** also conduct experiments in real scenarios and compare the real path planning obtained by the HL-PSO algorithm,DDPG algorithm,and TSEB-DDPG *** results show that the TSEBDDPG algorithm can archive almost the best in terms of accuracy,the average time of actual path planning,and the success rate.

关键词： Unmanned aerial vehicle Path planning Deep deterministic policy gradient Three-step experience buffer Particle swarm optimization

Evaluation of the Impact of Observations on Blended Sea Surface Winds in a Two-Dimensional Variational Scheme Using Degrees of Freedom

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Journal of Meteorological Research 2017年第6期31卷 1123-1132页

作者： Ting WANG Jie XIANG Jianfang FEI Yi WANG Chunxia liU yuanxiang li Institute of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101 Key Laboratory of Mesoscale Severe Weather of Ministry of Education Nanjing UniversityNanjing 210093 Guangdong Institute of Tropical and Marine Meteorology of China Meteorological Administration Guangzhou 510080 School of Aeronautics andAstronautics Shanghai Jiao Tong UniversityShanghai 200240

This paper presents an evaluation of the observational impacts on blended sea surface winds from a two- dimensional variational data assimilation （2D-Var） scheme. We begin by briefly introducing the analysis sensitivity with respect to observations in variational data assimilation systems and its relationship with the degrees of freedom for signal （DFS）, and then the DFS concept is applied to the 2D-Var sea surface wind blending scheme. Two meth- ods, a priori and a posteriori, are used to estimate the DFS of the zonal （u） and meridional （v） components of winds in the 2D-Var blending scheme. The a posteriori method can obtain almost the same results as the a priori method. Because only by-products of the blending scheme are used for the a posteriori method, the computation time is re- duced significantly. The magnitude of the DFS is critically related to the observational and background error statistics. Changing the observational and background error variances can affect the DFS value. Because the observation error variances are assumed to be uniform, the observational influence at each observational location is related to the background error variance, and the observations located at the place where there are larger background error variances have larger influences. The average observational influence of u and v with respect to the analysis is about 40%, implying that the background influence with respect to the analysis is about 60%.

关键词： sea surface wind blending sensitivity observational influence degrees of freedom for signal

Combining Multi-scale Directed Depth Motion Maps and Log-Gabor Filters for Human Action Recognition

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Journal of Harbin Institute of Technology(New Series) 2019年第4期26卷 89-96页

作者： Xiaoye Zhao Xunsheng Ji yuanxiang li li Peng Engineering Research Center of Internet of Things Technology Applications of the Ministry of Education School of Internet of Things Engineering Jiangnan University

Recognition of the human actions by computer vision has become an active research area in recent years. Due to the speed and the high similarity of the actions, the current algorithms cannot get high recognition rate. A new recognition method of the human action is proposed with the multi-scale directed depth motion maps(MsdDMMs) and Log-Gabor filters. According to the difference between the speed and time order of an action, MsdDMMs is proposed under the energy framework. Meanwhile, Log-Gabor is utilized to describe the texture details of MsdDMMs for the motion characteristics. It can easily satisfy both the texture characterization and the visual features of human eye. Furthermore, the collaborative representation is employed as action recognition by the classification. Experimental results show that the proposed algorithm, which is applied in the MSRAction3 D dataset and MSRGesture3 D dataset, can achieve the accuracy of 95.79% and 96.43% respectively. It also has higher accuracy than the existing algorithms, such as super normal vector(SNV), hierarchical recurrent neural network(Hierarchical RNN).

关键词： human action recognition depth motion maps Log-Gabor filters collaborative representation based classifier

Tropical cyclone spiral band extraction and center locating by binary ant colony optimization

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Science China Earth Sciences 2012年第2期55卷 332-346页

作者： BAI QiuChan WEI Kun JING Zhongliang li yuanxiang TUO HongYa liU ChengGang Faculty of Electronic and Electric Engineering Huaiyin Institute of TechnologyHuai'an 223003China School of Aeronautics and Astronautics Shanghai Jiaotong UniversityShanghai 200240China

Tropical cyclone (TC) center locating is crucial because it lays the foundation for TC forecasting. Locating TC centers, usually by manual means, continues to present many difficulties. Not least is the problem of inconsistency between TC center locations forecast by different agencies. In this paper, an objective TC center locating scheme is developed, using infrared satellite images. We introduce a pattern-matching concept, which we illustrate using a spiral curve model. A spiral band model, based on a spiral band region, is designed to extract the spiral cloud-rain bands (SCRBs) of TCs. We propose corresponding criteria on which to score the fitting value of a candidate template defined by our models. In the proposed scheme, TC location is an optimization problem, solved by an ant colony optimization algorithm. In numerical experiments, a minimal mean distance error of 17.9 km is obtained when the scheme is tested against best-track data. The scheme is suitable for TCs with distinct SCRBs or symmetrical central dense overcast, and for TCs both with and without clear eyes.

关键词： weather forecast tropical cyclones center locating spiral band model ant colony optimization

Parameter Estimation of S-Shaped Growth Model:A Modified Particle Swarm Algorithm

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Wuhan University Journal of Natural Sciences 2012年第2期17卷 137-143页

作者： XU Xing WEI Bo WU Yu liU Bingxiang li yuanxiang College of Information and Engineering Jingdezhen CeramicInstitute Jingdezhen 333403 Jiangxi China School of Computer Wuhan University Wuhan 430072Hubei China

Parameter estimation plays a critical role for the application and development of S-shaped growth model in the agricultural sciences and *** this paper,a modified particle swarm optimization algorithm based on the diffusion phenomenon（DPPSO） was employed to estimate the parameters for this *** the sense of least squares,the parameter estimation problem of S-shaped growth model,taking the Gompertz and Logistic models for example,is transformed into a multi-dimensional function optimization *** results show that the DPPSO algorithm can effectively estimate the parameters of the S-shaped growth model.

关键词： particle swarm optimization diffusion phenomenon parameter estimation S-shaped growth model

4-(4,6-二甲氧基嘧啶-2-基)-2-氧代-1,2-二氢喹啉-3-羧酸乙酯的烃化反应

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有机化学 2013年第11期33卷 2334-2340页

作者：李元祥怀化学院化学与化学工程系怀化418008

以卤化物作烃化试剂、NaH作缚酸剂，在N,N-二甲基甲酰胺（DMF）溶剂中室温条件下，4-（4，6-二甲氧基嘧啶-2-基）—2-氧代-1，2-二氢喹啉-3-羧酸乙酯经烃化反应同时得到了20个未见文献报道的N-取代及O-取代新化合物，烃化产物的结构通过... 详细信息

以卤化物作烃化试剂、NaH作缚酸剂，在N,N-二甲基甲酰胺（DMF）溶剂中室温条件下，4-（4，6-二甲氧基嘧啶-2-基）—2-氧代-1，2-二氢喹啉-3-羧酸乙酯经烃化反应同时得到了20个未见文献报道的N-取代及O-取代新化合物，烃化产物的结构通过^1H NMR，MS，元素分析，单品衍射及IR进行了表征．烃化反应的条件温和，转化率高达89％-98％．其中，主产物N-取代产物的收率为47％-77％，副产物O-取代产物的收率为21％～49％．

关键词：喹啉酮烃化反应结构表征