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Multiple Solutions of a Nonlinear Biharmonic Equation on Graphs

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Communications in Mathematics and Statistics 2023年第4期11卷 767-774页

作者： songbo Hou Department of Applied Mathematics College of ScienceChina Agricultural UniversityBeijing 100083People’s Republic of China

In this paper,we consider a biharmonic equation with respect to the Dirichlet problem on a domain of a locally finite *** the variation method,we prove that the equation has two distinct solutions under certain condit... 详细信息

关键词： Locallyﬁnite graph Biharmonic equation Distinct solutions Mathematics Subject Classiﬁcation 35A15 35G30

Harnack estimate for a semilinear parabolic equation

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Science China Mathematics 2017年第5期60卷 833-840页

作者： HOU songbo ZOU Liang Department of Applied Mathematics College of Science China Agricultural University Beijing 100083 China

We study the Cauchy problem of a semilinear parabolic equation. We construct an appropriate Harnack quantity and get a differential Harnack inequality. Using this inequality, we prove the finite-time blow-up of the positive solutions and recover a classical Harnack inequality. We also obtain a result of Liouville type for the elliptic equation.

关键词： parabolic equation Harnack estimate finite-time blow-up

Multi-temporal InSAR for Urban Deformation Monitoring:Progress and Challenges

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雷达学报（中英文） 2020年第2期9卷 277-294页

作者： WU songbo LE Yongyao ZHANG Lei DING Xiaoli Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic UniversityHung HomKLNHong Kong 999077China Xi’an Engineering Investigation and Design Research Institute of China National Nonferrous Metals Industry Co.Ltd. Xi’an 710000China

Multi-temporal Interferometric Synthetic Aperture Radar(MT-InSAR) is one of the most powerful Earth observation techniques, especially useful for measuring highly detailed ground deformation over large ground areas. Much research has been carried out to apply MT-InSAR to monitor ground and infrastructure deformation in urban areas related to land reclamation, underground construction and groundwater *** paper reviews the progress in the research and identifies challenges in applying the technology, including the inconsistency in coherent point identification when different approaches are used, the reliability issue in parameter estimation, difficulty in accurate geolocation of measured points, the one-dimensional line-of-sight nature of InSAR measurements, the inability of making complete measurements over an area due to geometric distortions, especially the shadowing effects, the challenges in processing large SAR datasets, the decrease of the number of coherent points with the increase of the length of SAR time series, and the difficulty in quality control of MT-InSAR results.

关键词： Urban deformation Monitoring Multi-temporal InSAR

A review of fracture mechanic behaviors of rocks containing various defects

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Underground Space 2023年第5期12卷 102-115页

作者： Fei Zhao Zhenming Shi songbo Yu Hongchao Zheng Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China Key Laboratory of Geotechnical and Underground Engineering Ministry of EducationTongii UniversityShanghai 200092China

The existence of defects in a rock mass is a vital factor complicating the mechanical response of the rock mass under *** characteristics of defects control the rock mass’s mechanical *** report reviews the experimental studies on the influence of simulating the internal defects of rock mass’s mechanical *** effects of preexisting defects(shape,size,number,angle,and other factors)on the mechanical properties and failure modes of the rock are investigated from the perspectives of rock failure and fracture *** fracture propagation mechanisms of different defective rock masses are analyzed by studying the stress state of different defective rock masses under uniaxial *** the defective rock samples with varying inclination angles are destroyed,the relationship among the compressive strength,the fracture propagation,and the failure characteristics is *** primary findings are as *** increase in the size and number of defects rapidly damages the mechanical properties of the rock and intensifies defect penetration and *** rock mechanics characteristics of fissured rocks with different inclination angles show two primary variations:one is a continuous increase,and the other is a decrease followed by an *** result is strongly related to the failure pattern of rocks with preexisting *** investigation is crucial for further studying the failure modes of complex defective rock masses and the geotechnical engineering related to defective rocks.

关键词： Rock mechanics Preexisting defects Failure patterns Fracture characteristics

Changes in the patterns of inorganic nitrogen and TN/TP ratio and the associated mechanism of biological regulation in the shallow lakes of the middle and lower reaches of the Yangtze River

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Science China Earth Sciences 2006年第Z1期49卷 126-134页

作者： WU Shikai XIE Ping WANG songbo ZHOU Qiong Donghu Experimental Station of Lake Ecosystems State Key Laboratory of Freshwater Ecology and Biotechnology of ChinaInstitute of Hydrobiology Chinese Academy of Sciences Wuhan 430072 China Donghu Experimental Station of Lake Ecosystems State Key Laboratory of Freshwater Ecology and Biotechnology of ChinaInstitute of Hydrobiology Chinese Academy of Sciences Wuhan 430072 China Donghu Experimental Station of Lake Ecosystems State Key Laboratory of Freshwater Ecology and Biotechnology of ChinaInstitute of Hydrobiology Chinese Academy of Sciences Wuhan 430072 China Donghu Experimental Station of Lake Ecosystems State Key Laboratory of Freshwater Ecology and Biotechnology of ChinaInstitute of Hydrobiology Chinese Academy of Sciences Wuhan 430072 China

The changes of NH3-N, NO3-N, NO2-N and TN/TP were studied during growth and non-growth season in 33 subtropical shallow lakes in the middle and lower reaches of the Yangtze River. There were significant positive correlations among all nutrient concentrations, and the correlations were better in growth season than in non-growth season. When TP＞0.1 mgL-1, NH3-N increased sharply in non-growth season with increasing TP, and NO3-N increased in growth season but decreased in non-growth season with TP. These might be attributed to lower dissolved oxygen and low temperature in non-growth season of the hypereutrophic lakes, since nitrification is more sensitive to dissolved oxygen and temperature than antinitrification. When 0.1 mgL-1＞TP＞0.035 mgL-1, TN and all kinds of inorganic nitrogen were lower in growth season than in non-growth season, and phytoplankton might be the vital regulating factor. When TP＜0.035 mgL-1, inorganic nitrogen concentrations were relatively low and NH3-N, NO2-N had significant correlations with phytoplankton, indicating that NH3-N and NO2-N might be limiting factors to phytoplankton. In addition, TN/TP went down with decline in TP concentration, and TN and inorganic nitrogen concentrations were obviously lower in growth season than in non-growth season, suggesting that decreasing nitrogen (especially NH3-N and NO3-N) was an important reason for the decreasing TN/TP in growth season. The ranges of TN/TP were closely related to trophic level in both growth and non-growth seasons, and it is apparent that in the eutrophic and hypertrophic state the TN/TP ratio was obviously lower in growth season than in non-growth season. The changes of the TN/TP ratio were closely correlated with trophic levels, and both declines of TN in the water column and TP release from the sediment were important factors for the decline of the TN/TP ratio in growth season.

关键词： nitrate-nitrogen, ammonium-nitrogen, nitrite-nitrogen, shallow lakes, phytoplankton.

Oxidation of benzene to phenol with N_(2)O over a hierarchical Fe/ZSM-5 catalyst

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Green Energy & Environment 2023年第4期8卷 1161-1173页

作者： Cui Ouyang Jianwei Li Yaqi Qu Song Hong songbo He State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing100029China Green Chemical Reaction Engineering Engineering and Technology Institute GroningenUniversity of GroningenNijenborgh 4Groningen9747 AGthe Netherlands CoRe Pro Colijnlaan 21Groningen9722 PJthe Netherlands

Catalytic oxidation of benzene with N_(2)O to phenol over the hierarchical and microporous Fe/ZSM-5-based catalysts in a continuous fixedbed reactor was *** spent catalyst was in-situ regenerated by an oxidative treatment using N_(2)O and in total 10 reaction-regeneration cycles were performed.A 100% N_(2)O conversion,93.3% phenol selectivity,and high initial phenol formation rate of 16.49±0.06mmol_(phenol gcatalyst)^(-1)h^(-1)at time on stream(TOS) of 5 min,and a good phenol productivity of 147.06 mmol_(phenol gcatalyst)^(-1)during catalyst lifetime of 1800 min were obtained on a fresh hierarchical Fe/ZSM-5-Hi2.8 *** the reaction-regeneration cycle,N_(2)O conversion is fully recovered within TOS of 3 h,moreover,the phenol productivity was decreased ca.2.2±0.8% after each cycle,leading to a total phenol productivity of ca.0.44 ton_(pheol kg_(catalyst)^(-1)estimated for 300 *** characterizations imply that the coke is rapidly deposited on catalyst surface in the initial TOS of 3 h(0.28 mgc_(gcatalyst)^(-1)min^(-1)) and gradually becomes graphitic during the TOS of 30 h with a slow formation rate of 0.06 mgc g_(catalyst)^(-1)min^(-1).Among others(e.g.,the decrease of textural property and acidity),the nearly complete coverage of the active Fe-O-Al sites by coke accounts for the main catalyst *** these reversible deactivation characteristics related to coking,the irreversible catalyst deactivation is also observed with the reaction-regeneration *** latter is reflected by a further decreased amount of the active Fe-O-Al sites,which agglomerate on catalyst surface with the cycle,likely associated with the hard coke residue that is not completely removed by the regeneration.

关键词： Hierarchical Fe/ZSM-5 N_(2)O conversion Phenol product productivity Reaction-regeneration cycles Irreversible deactivation mechanism

Effects of Conduction Electron Band Structure on Transport of Quantum Dot Systems

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Chinese Physics Letters 2003年第5期20卷 717-720页

作者： YANGKai-Hua songbo TIANGuang-Shan WANGYu-Peng HANRu-Shan HANRu-Qi InstituteforMicroelectronics PekingUniversityBeijing100871 TechnicalInstituteofPhysicsandChemistry ChineseAcademyofSciencesBeijing100080 SchoolofPhysics PekingUniversityBeijing100871 InstituteofPhysicsandCenterforCondensedMatterPhysics ChineseAcademyofSciencesBeijing100080

We study the effects of the energy band structure of conduction-electron on the transport properties of an interacting quantum dot system. By applying the nonequilibrium Keldysh Green function technique, we show that the finite width of electron band in leads causes the negative differential conductance in some regions of the applied voltage. We also show that the van Hove singularities in the density of states of conduction-electron do not qualitatively change the differential conductance of the system, and hence can be safely ignored. Therefore, the wide band approximation used in the previous investigations is partially justified.

关键词：量子通信体系相互作用电子传输电子结构量子点

Aqueous-phase reforming of hydroxyacetone solution to bio-based H_(2)over supported Pt catalysts

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Green Energy & Environment 2024年第4期9卷 777-788页

作者： A.K.K.Vikla K.Koichumanova songbo He K.Seshan Joint International Research Laboratory of Circular Carbon Nanjing Tech UniversityNanjing211816China Faculty of Science and Technology University of Twente7500 AE EnschedeThe Netherlands CoRe Pro 9723 BL GroningenThe Netherlands

Aqueous-phase reforming(APR)is an attractive process to produce bio-based hydrogen from waste biomass streams,during which the catalyst stability is often challenged due to the harsh reaction *** this work,three Pt-based catalysts supported on C,AlO(OH),and ZrO_(2)were investigated for the APR of hydroxyacetone solution in afixed bed reactor at 225℃and 35 *** them,the Pt/C catalyst showed the highest turnover frequency for H_(2)production(TOF of 8.9 molH_(2)molPt^(-1)min^(-1))and the longest catalyst *** the AlO(OH)and ZrO_(2)supported Pt catalysts,the side reactions consuming H_(2),formation of coke,and Pt sintering result in a low H_(2)production and the fast catalyst *** proposed reaction pathways suggest that a promising APR catalyst should reform all oxygenates in the aqueous phase,minimize the hydrogenation of the oxygenates,maximize the WGS reaction,and inhibit the condensation and coking reactions for maximizing the hydrogen yield and a stable catalytic performance.

关键词： APR Hydroxyacetone TOF Bio-based H_(2) Support effect

Pulsar giant pulse: Coherent instability near light cylinder

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Science China(Physics,Mechanics & Astronomy) 2019年第7期62卷 113-122页

作者： WeiYang Wang JiGuang Lu songbo Zhang XueLei Chen Rui Luo RenXin Xu Key Laboratory for Computational Astrophysics National Astronomical Observatories Chinese Academy of Sciences University of Chinese Academy of Sciences School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking University National Astronomical Observatories Chinese Academy of Sciences Key Laboratory of Radio Astronomy Chinese Academy of Sciences Purple Mountain Observatory Chinese Academy of Sciences CSIRO Astronomy and Space Science Australia Telescope National Facility International Centre for Radio Astronomy Research University of Western Australia Center for High Energy Physics Peking University Kavli Institute for Astronomy and Astrophysics Peking University Department of Astronomy School of Physics Peking University

Giant pulses(GPs) are extremely bright individual pulses of radio pulsar. In microbursts of Crab pulsar, which is an active GP emitter, zebra-pattern-like spectral structures are observed, which are reminiscent of the "zebra bands" that are observed in type Ⅳ solar radio flares. However, band spacing linearly increases with the band center frequency of ～5-30 GHz. In this study, we propose that the Crab pulsar GP can originate from the coherent instability of plasma near a light cylinder. Further, the growth of coherent instability can be attributed to the resonance observed between the cyclotron-resonant-excited wave and the background plasma oscillation. The particles can be injected into the closed-field line regions owing to magnetic reconnection near a light cylinder. These particles introduce a large amount of free energy that further causes cyclotron-resonant instability, which grows and amplifies radiative waves at frequencies close to the electron cyclotron harmonics that exhibit zebra-pattern-like spectral band structures. Further, these structures can be modulated by the resonance between the cyclotron-resonant-excited wave and the background plasma oscillation. In this scenario, the band structures of the Crab pulsar can be well fitted by a coherent instability model, where the plasma density of a light cylinder should be ～10^(13-15) cm^(-3), with an estimated gradient of >5.5 × 10~5 cm^(-4). This process may be accompanied by high-energy emissions. Similar phenomena are expected to be detected in other types of GP sources that have magnetic fields of ? 106 G in a light cylinder.

关键词： neutron star pulsar radiation mechanisms instabilities in plasmas