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Star formation properties of galaxy cluster A1767

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Research in Astronomy and Astrophysics 2015年第11期15卷 1773-1783页

作者： Peng-Fei Yan Feng Li qi-Rong yuan Department of Physics Nanjing Normal University School of Mathematics and Physics Qingdao University of Science and Technology School of Mathematics and Physics Changzhou University

Abell 1767 is a dynamically relaxed, c D cluster of galaxies with a redshift of 0.0703. Among 250 spectroscopically confirmed member galaxies within a projected radius of 2.5r200, 243 galaxies（ Digital Sky Survey. Based on this ～97%） are spectroscopically covered by the Sloanhomogeneous spectral sample, the stellar evolutionary synthesis code STARLIGHT is applied to investigate the stellar populations and star formation histories of galaxies in this cluster. The star formation properties of galaxies, such as mean stellar ages, metallicities, stellar masses, and star formation rates, are presented as functions of local galaxy density. A strong environmental effect is found such that massive galaxies in the high-density core region of the cluster tend to have higher metallicities, older mean stellar ages, and lower specific star formation rates（SSFRs）, and their recent star formation activities have been remarkably suppressed. In addition, the correlations of the metallicity and SSFR with stellar mass are confirmed.

关键词： galaxy galaxies stellar luminosity galactic SDSS dynamically nearby stars older

Optimization of Key Predistribution Protocol Based on Supernetworks Theory in Heterogeneous WSN

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Tsinghua Science and Technology 2016年第3期21卷 333-343页

作者： qi yuan Chunguang Ma Xiaorui Zhong Gang Du Jiansheng Yao College of Computer Science and Technology Harbin Engineering UniversityHarbin 150001China College of Communication and Electronic Engineering Qiqihar UniversityQiqihar 161006China Key Lab of Network Security and Cryptography of Fujian Province China Academy of Electronics and Information Technology Beijing 100041China

This work develops an equilibrium model for finding the optimal distribution strategy to maximize performance of key predistribution protocols in terms of cost, resilience, connectivity, and lifetime. As an essential attribute of wireless sensor networks, heterogeneity and its impacts on random key predistribution protocols are first discussed. Using supernetworks theory, the optimal node deployment model is proposed and illustrated. In order to find the equilibrium performance of our model, all optimal performance functions are changed into variational inequalities so that this optimization problem can be solved. A small-scale example is presented to illustrate the applicability of our model.

关键词： optimization key predistribution protocol supernetworks variational inequality wireless sensornetworks

Learnable three-dimensional Gabor convolutional network with global affinity attention for hyperspectral image classification

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Chinese Physics B 2022年第12期31卷 118-135页

作者： Hai-Zhu Pan Mo-qi Liu Hai-Miao Ge qi yuan College of Computer and Control Engineering Qiqihar UniversityQiqihar 161000China College of Telecommunication and Electronic Engineering Qiqihar UniversityQiqihar 161000China

Benefiting from the development of hyperspectral imaging technology,hyperspectral image(HSI)classification has become a valuable direction in remote sensing image ***,researchers have found a connection between convolutional neural networks(CNNs)and Gabor ***,some Gabor-based CNN methods have been proposed for HSI ***,most Gabor-based CNN methods still manually generate Gabor filters whose parameters are empirically set and remain unchanged during the CNN learning ***,these methods require patch cubes as network *** patch cubes may contain interference pixels,which will negatively affect the classification *** address these problems,in this paper,we propose a learnable three-dimensional(3D)Gabor convolutional network with global affinity attention for HSI *** precisely,the learnable 3D Gabor convolution kernel is constructed by the 3D Gabor filter,which can be learned and updated during the training ***,spatial and spectral global affinity attention modules are introduced to capture more discriminative features between spatial locations and spectral bands in the patch cube,thus alleviating the interfering pixels *** results on three well-known HSI datasets(including two natural crop scenarios and one urban scenario)have demonstrated that the proposed network can achieve powerful classification performance and outperforms widely used machine-learning-based and deep-learning-based methods.

关键词： image processing remote sensing 3D Gabor filter neural networks global affinity attention

Structural and elastic properties of Ce2O3 under pressure from LDA+U method

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Frontiers of Physics 2013年第4期8卷 405-411页

作者： yuan-yuan qi Zhen-Wei Niu Cai Cheng Yan Cheng Institute of Atomic and Molecular Physics Sichuan University

We investigate the structural and elastic properties of hexagonal Ce2O3 under pressure using LDA+U scheme in the frame of density functional theory(DFT).The obtained lattice constants and bulk modulus agree well with the available experimental and other theoretical *** pressure dependences of normalized lattice parameters a/a0 and c/c0,ratio c/a,and normalized primitive volume V /V0 of Ce2O3 are ***,the pressure dependences of elastic properties and three anisotropies of elastic waves of Ce2O3 are investigated for the frst *** fnd that the negative value of C44 is indicative of the structural instability of the hexagonal structure Ce2O3 at zero temperature and 30 ***,the density of states(DOS) of Ce2O3 under pressure is investigated.

关键词： elastic properties high pressure density functional theory Ce2O3

Phenols/Al(C_(6)F_(5))_(3) Initiation Systems for Cationic Polymerizations of Isobutylene

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Chinese Journal of Polymer Science 2023年第5期41卷 713-719,I0008页

作者： Ling Cai qi-yuan Wang Xin-Li Liu Dong-Mei Cui State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Department of Polymer Science and Engineering University of Science and Technology of ChinaHefei 230026China

We report herein the cationic polymerization of isobutylene(IB)under mild conditions is realized with a new binary initiation system generated by simply mixing a Lewis super acid Al(C_(6)F_(5))_(3) and a substituted phenol(RPhOH).Polymers with medium and/or high molecular weights(M_(W)=4.9×10^(4)-27.7×10^(4) g·mol^(-1))can be obtained in toluene and temperatures from-20℃to 0℃.NMR spectrum analysis and DFT sim ulation reveals the in situ generated acidic coordinating complex Ak(C_(6)F_(5))_(3)·RPhOH is the initiating active species,which fu rther tran sformed into the ion-pair[Al(C_(6)F_(5))_(3)ORPh]^(-)[PIB]^(+)of the active intermediates upon growing IB monomers where the counter anion[Al(C_(6)F_(5))_(3)R^(O)Ph]-coordinates to the macrocation via the phenoxy *** catalyst performances are the concert effects of the steric bulkiness and electronics of the counter anion on the coordinating strength to the macrocation,which is significant to the stability of the active species.

关键词： Cationic polymerization Phenols Lewis super acid Polyisobutylene

Flexible, ultrathin, and multifunctional polypyrrole/cellulose nanofiber composite films with outstanding photothermal effect, excellent mechanical and electrochemical properties

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Frontiers of Chemical Science and Engineering 2023年第8期17卷 1028-1037页

作者： Ya-Ge Zhang Ling-Zhi Huang qi yuan Ming-Guo Ma Research Center of Biomass Clean Utilization MOE Engineering Research Center of Forestry Biomass Materials and BioenergyBeijing Key Laboratory of Lignocellulosic ChemistryCollege of Materials Science and TechnologyBeijing Forestry UniversityBeijing 100083China

Electrodes that combine energy storage with mechanical and photothermal performance are necessary for efficient development and use of flexible energy storage and conversion *** this study,the flexible,ultrathin,and multifunctional polypyrrole/cellulose nanofiber composite films were fabricated via a one-step“soak and polymerization”*** dense sandwich structure and strong interfacial interaction endowed polypyrrole/cellulose nanofiber composite films with excellent flexibility,outstanding mechanical strength,and desired ***,the polypyrrole/cellulose nanofiber composite film electrodes with quaternary amine functionalized cellulose nanofiber had the highest specific mass capacitance(392.90 F∙g^(–1))and specific areal capacitance(3.32 F∙cm^(–2))than the electrodes with unmodified and carboxyl functionalized cellulose ***,the polypyrrole/cellulose nanofiber composite films with sandwich structure had excellent photothermal conversion *** study demonstrated a feasible and versatile method for preparing of multifunctional composite films,having promising applications in various energy storage fields.

关键词： cellulose nanofiber electrochemical photothermal conversion polypyrrole

The Lowest Order Relativistic Corrections for K^-p Two-Body Problem

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Communications in Theoretical Physics 2005年第6X期44卷 1061-1064页

作者： WANG Wan-Zhang ZHANG qi-Ren GAOChun-yuan Department of Technical Physics Peking University Beijing 100871 China

A two-body equation of the kaon-proton system with the lowest order relativistic corrections is derived and solved. The scattering lengths and the energy of an unstable bound state are calculated.

关键词： K^-p system relativistic corrections

Recent Advances in the Catalytic Upgrading of Biomass Platform Chemicals Via Hydrotalcite-Derived Metal Catalysts

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Transactions of Tianjin University 2022年第2期28卷 89-111页

作者： Zhe-Hui Zhang Zhuohua Sun Tong-qi yuan Beijing Key Laboratory of Lignocellulosic Chemistry Beijing Forestry UniversityBeijing 100083China

With the world’s fossil fuels being finite in nature,an increasing interest focuses on the application of alternative renewable resources such as ***-derived platform chemicals with abundant functional groups have the potential to replace bulk chemicals for the production of value-added chemicals,fuels,and *** upgrading of these platform chemicals relies on the development of efficient catalytic ***,with its wide compositional variety,tuneable anion-exchange capacity,and controlled acidity/basicity sites demonstrates great potential in the catalytic upgrading of biomass and the derived platform *** past decade has witnessed the emergence of research achievements on the development of efficient and robust hydrotalcite-derived metal catalysts and their applications in the upgrading of biomass or the derived platform *** this review,we aim to summarize the recent advances on the catalytic upgrading of biomass-derived platform chemicals(e.g.,furfural,5-hydroxymethylfurfural,levulinic acid,and glycerol)via hydrotalcitederived metal *** also observed that the crucial role of using hydrotalcite-derived catalysts relies on their strong metal–support *** a result,a section focusing on the discussion of the metal–support interactions of hydrotalcitederived catalysts was provided.

关键词： Hydrotalcite Biomass Catalysis Metal-support interactions

Subsynchronous oscillation monitoring and alarm method based on phasor measurements

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Global Energy Interconnection 2020年第5期3卷 464-474页

作者： yuan qi Jiaxian Li Hao Liu Tianshu Bi State Key Lab of Alternate Electric Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206P.R.China

Owing to the large-scale grid connection of new energy sources, several installed power electronic devices introduce sub-/supersynchronous inter-harmonics into power signals, resulting in the frequent occurrence of subsynchronous oscillations(SSOs). The SSOs may cause significant harm to generator sets and power systems;thus, online monitoring and accurate alarms for power systems are crucial for their safe and stable operation. Phasor measurement units(PMUs) can realize the dynamic real-time monitoring of power systems. Based on PMU phasor measurements, this study proposes a method for SSO online monitoring and alarm implementation for the main station of a PMU. First, fast Fourier transform frequency spectrum analysis is performed on PMU current phasor amplitude data to obtain subsynchronous frequency components. Second, the support vector machine learning algorithm is trained to obtain the amplitude threshold and subsequently filter out safe components and retain harmful ones. Finally, the adaptive duration threshold is determined according to frequency susceptibility, amplitude attenuation, and energy accumulation to decide whether to transmit an alarm signal. Experiments based on field data verify the effectiveness of the proposed method.

关键词： Subsynchronous oscillation(SSO) Phasor measurement unit(PMU) Frequency spectrum analysis Amplitude threshold Duration threshold