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Evaluating COVID-19’s impacts on Puerto Rican’s travel behaviors

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Geo-Spatial Information Science 2023年第4期26卷 616-626页

作者： Lauren C.Carter ran tao School of Geosciences University of South FloridaTampaFLUSA

The COVID-19 pandemic has completely disrupted and possibly permanently changed the way humans *** Puerto Rico,major travel restrictions to the island have persisted at different levels since March 2020,which heavily influenced residents’travel ***,it remains unclear about how big the impact is and how inequitable it might *** goal of this study is to evaluate COVID-19’s impacts on Puerto Rican’s travel behaviors by analyzing travel flows from Puerto Rico to the contiguous US with a modified gravity *** roles of socioeconomic factors regarding the Puerto Rican travelers and COVID-19 factors regarding the destination US states have been ***-19 was a strong deterring factor of travel at the beginning of the pandemic and also in the winter of 2020,but it did not keep Puerto Ricans from traveling during the summer 2020 when most travel restrictions were *** found that the elderly population of Puerto Rico,despite being more vulnerable to COVID-19,were much more likely to travel during the *** also found that,during the holiday season in 2020,some socioeconomically disadvantaged populations were more likely to be traveling,a direct contradiction to their travel flows the year *** findings shed light on about how disproportionately affected populations behavior changed from pre-pandemic to after the pandemic *** the continuance of the pandemic,this information is extremely valuable for future planning with respect to emergency management,travel regulation,and social benefit.

关键词： COVID-19 Puerto Rico travel behavior social vulnerability human mobility

Liveness evaluation of multi-living agent system

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Journal of Systems Engineering and Electronics 2013年第3期24卷 435-444页

作者： Shengheng Liu tao Shan ran tao Yue Wang School of Information and Electronics Beijing Institute of Technology

Multi-living agent system （MLAS） is a new concept in the field of complex system research, which is peculiarly suitable for the design and analysis of a complex information system in a serious confrontation and tight constraint environment. However, the universal method to quantitatively measure the living degree of an MLAS remains uncertain, which is critical to the self-organizing process. Therefore, a novel analytic hierarchy process （AHP） based method with dependent pairwise comparison matrix （PCM） for the evaluation of living degree of the MLAS is proposed, which eliminates the shortcoming of fixed PCM in traditional process. Furthermore, to avoid the annoying procedure of the consistency validation, the PCMs are appropriately reconstructed. Through an illustration of the netted radar system, the calculation detail is explicitly presented. Altogether, the advanced evaluation method successfully accomplishes the preset objective and promotes the development of the MLAS theory and AHP as well.

关键词： multi-living agent system (MLAS) living degree ana- lytic hierarchy process (AHP).

On m-ovoids of finite classical polar spaces with an irreducible transitive automorphism group

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Science China Mathematics 2024年第3期67卷 683-712页

作者： tao Feng Weicong Li ran tao School of Mathematical Sciences Zhejiang UniversityHangzhou 310027China Department of Mathematics and National Center for Applied Mathematics Shenzhen Southern University of Science and TechnologyShenzhen 518055China Key Laboratory of Cryptologic Technology and Information Security Ministry of EducationShandong UniversityQingdao 266237China School of Cyber Science and Technology Shandong UniversityQingdao 266237China

In this paper, we classify the m-ovoids of finite classical polar spaces that admit a transitive automorphism group acting irreducibly on the ambient vector space. In particular, we obtain several new infinite familie... 详细信息

关键词： transitive m-ovoids irreducible action finite classical polar spaces primitive divisor

Carbon-based materials for photodynamic therapy: A mini-review

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Frontiers of Chemical Science and Engineering 2019年第2期13卷 310-323页

作者： Di Lu ran tao Zheng Wang School of Pharmaceutical Science & Technology Tianjin Key Laboratory for Modem Drug Delivery & High EfficiencyCollaborative Innovation Center of Chemical Science and Engineering (Tianjin)Tianjin UniversityTianjin 300072China

Carbon-based materials have been extensively applied in photodynamic therapy owing to the unique optical characteristics,good biocompatibility and tunable systematic *** mini-review mainly focuses on the recent application of carbon-based materials including graphene,carbon nanotube,fullerene,corannulene,carbon dot and mesoporous carbon *** carbon-based materials can perform not only as photosensitizers,but also effective carriers for photosensitizers in photodynamic therapy,and its combined treatment.

关键词： photodynamic therapy carbon-based materials graphene carbon nanotube fullerene corannulene carbon dot mesoporous carbon nanoparticle

Waveform design for higher-level 3D constellation mappings and its construction based on regular tetrahedron cells

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Science China(Information Sciences) 2015年第8期58卷 13-24页

作者： SHI PengFei HUAN Hao tao ran School of Information and Electronics Beijing Institute of Technology Key Lab for Spacecraft TT&C and Communication under the Ministry of Education

In this paper, we propose a generalized method of high-level three dimensional(3D) signal constellation mapping based on the most basic 3D structure: regular tetrahedron cells. First, we redefined the waveform design, the normalized frequency and phase modulation for the geometric construction of tetrahedron ***, the new topology of tetrahedron cells based on the traditional lattice 3D constellation were ***, we focused on the two essential types, 8-ary and 16-ary based on tetrahedron cells on behalf of the odd and even carry bits, respectively. The available range and closed forms of the symbol error probability(SEP)were derived to increase the effectiveness and safety of wireless communication systems. Normalized minimum Euclidean distance and average number of neighbors were utilized to measure the performance against Gaussian noise. Simulation results showed that the proposed 8-ary and 16-ary 3D constellation mapping obtained 0.25 and 0.5 d B gain at the SEP of 10-6and 10-4, respectively, over traditional 3D lattice structure in additive white Gaussian noise(AWGN) channel.

关键词： waveform design 3D constellation mapping regular tetrahedron cells OFDM systems wireless communication

Study of detection performance of passive bistatic radars based on FM broadcast

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Journal of Systems Engineering and Electronics 2007年第1期18卷 22-26页

作者： Shan tao tao ran Wang Yue Zhou Siyong Dept. of Electronic Engineering Beijing Inst. of Technology Beijing 100081 P. R. China

The passive bistatic radar based on the FM broadcast has inherent superiority with respect to its survivability. In this article, the ambiguity function （AF） and the cross ambiguity function （CAF） of the FM radio signal are analyzed and illustrated. The Kolmogorov Smirnov （K-S） test verifies that the amplitude probability density function of the CAF side lobes is exponential; the distribution of the target is also deduced. Finally, the detection performance of the passive radar is studied, and the result shows that this new type bistatic radar has favorable detection capability.

关键词： Bistatic radar Ambiguity function Cross ambiguity function Probability density function (PDF)

Improved RIP-based performance guarantees for multipath matching pursuit

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Science China(Information Sciences) 2018年第10期61卷 173-186页

作者： Juan ZHAO Xia BAI ran tao School of Information and Electronics Beijing Institute of Technology Beijing Key Laboratory of Fractional Signals and Systems Beijing Institute of Technology

The multipath matching pursuit(MMP) is a generalization of the orthogonal matching pursuit(OMP), which generates multiple child paths for every candidate in each iteration and selects the candidate having the minimal residual as the final support set when iteration ends. In this paper we analyze its performance in both noiseless and noisy cases. The restricted isometry property(RIP)-based condition of MMP that ensures accurate recovery of sparse signals in the noiseless case is derived by using a simple technique. The performance guarantees of the MMP for support recovery in noisy cases are also *** is shown that under certain conditions on the RIP and minimum magnitude of nonzero components of the sparse signal, the MMP will exactly recover the true support of the sparse signal in cases of bounded noises and recover the true support with a high probability in the case of Gaussian noise. Our bounds on the RIP improve the existing results.

关键词： compressed sensing(CS) sparse signal reconstruction multipath matching pursuit(MMP) support recovery restricted isometry property(RIP)

Wind Environment Analysis of Ground-based Optical Observatory

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Research in Astronomy and Astrophysics 2022年第4期22卷 11-20页

作者： tao-ran Li Xiao-Jun Jiang Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

The telescopes and the infrastructures may alter the local wind environment around the observatory and further affect the observing *** the completion of site testing,it is necessary to analyze the wind environment of the entire site and plan the telescope layout to make use of the excellent conditions scientifically and *** a typical observatory as an example,the effect of topographical features on the wind environment and the mutual interference between telescope enclosures are analyzed by using the Computational Fluid Dynamics(CFD)*** CFD simulations are compared with the seeing data from the Differential Image Motion Monitor,and the results are in good agreement,which verifies the effectiveness of the CFD *** results of wind environment analysis can provide reasonable suggestions for site layout and construction,reducing the interference effects and improving the observing environment.

关键词： methods:numerical telescopes atmospheric effects turbulence

Variation of a signal in Schwarzschild spacetime

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Science China(Information Sciences) 2019年第8期62卷 172-191页

作者： Huan LIU Xiang-Gen XIA ran tao School of Information and Electronics Beijing Institute of Technology Department of Electrical and Computer Engineering University of Delaware

In this paper, the variation of a signal in Schwarzschild spacetime is studied and a general equation for frequency shift parameter(FSP) is presented. The FSP is found to depend on the gravitationally modified Doppler effects and the gravitational effects of observers. In addition, the time rates of a transmitter and receiver may differ. When the FSP is a function of the receiver time, the FSP contributed through the gravitational effect(GFSP) or the gravitationally modified Doppler effect(GMDFSP) may convert a bandlimited signal into a non-bandlimited signal. Using the general equation, the FSP as a function of receiver time is calculated in three scenarios:(a) a spaceship leaving a star at constant velocity communicating with a transmitter at a fixed position;(b) a spaceship moving around a star with different conic trajectories communicating with a transmitter at a fixed position; and(c) a signal transmitted from a fixed position in a star system to a receiver following an elliptic trajectory in another star system. The studied stars are a Sun-like star, a white dwarf, and a neutron star. The theory is illustrated with numerical examples.

关键词： deep space communications general relativity Schwarzschild spacetime bandlimited signal gravitationally modified Doppler effect