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Photometric redshifts of galaxies from SDSS and 2MASS

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Chinese Journal of Astronomy and Astrophysics 2009年第4期9卷 390-400页

作者： tao Wang Jia-sheng Huang Qiu-sheng Gu Department of Astronomy Nanjing University Nanjing 210093 China Harvard-Smithsonian Center for Astrophysics 60 Garden Street Cambridge MA 02138

In order to find the physical parameters which determine the accuracy of pho- tometric redshifts, we compare the spectroscopic and photometric redshifts （photo-z＇s） for a large sample of -80000 SDSS-2MASS galaxies. Photo-z＇s in this paper are estimated by using the artificial neural network photometric redshift method （ANNz）. For a subset of -40000 randomly selected galaxies, we find that the photometric redshift recovers the spectroscopic redshift distribution very well with rms of 0.016. Our main results are as follows：（1） Using magnitudes directly as input parameters produces more accurate photo-z＇s than using colors; （2） The inclusion of 2MASS （J, H, Ks） bands does not improve photo-z＇s significantly, which indicates that near infrared data might not be important for the low-redshift sample; （3） Adding the concentration index （essentially the steepness of the galaxy brightness profile） as an extra input can improve the photo-z＇s estimation up to -10 percent; （4） Dividing the sample into early- and late-type galaxies by using the concentration index, normal and abnormal galaxies by using the emission line flux ratios, and red and blue galaxies by using color index （g - r）, we can improve the accuracy of photo-z＇s significantly; （5） Our analysis shows that the outliers （where there is a big difference between the spectroscopic and photometric redshifts） are mainly correlated with galaxy types, e.g., most outliers are late-type （blue） galaxies.

关键词： galaxies distances and redshifts-methods statistical-techniques pho-tometric

Comparison of pyrolysis characteristics of two Chinese oil shales based onthe migration and conversion of organic carbon

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Carbon Resources Conversion 2018年第3期1卷 209-217页

作者： Zhi-bing Chang mo Chu Chao Zhang Shu-xia Bai sheng-tao Wang Bao-man Liu School of Chemical and Environmental Engineering China University of Mining and Technology(Beijing)Beijing 100083China

In this study,the Huadian oil shale(HD-R)and Balikun oil shale(BLK-R)were pyrolyzed in a fixed-bed pyrolyzer at 360–530℃.Based on the migration and conversion of organic carbon,their pyrolysis characteristics were investigated and *** aliphaticity of Huadian kerogen(HD-K)and Balikun kerogen(BLK-K)are 80.53%and 52.83%,*** HD-K contains more C=O,which will render the depolymerization and decomposition of kerogen to occur at low temperatures to produce volatile ***,the cumulative conversion of the Huadian shale oil is greater than the Balikun shale oil at 390–435℃.The aliphatic carbons of the BLK-K are mainly present as short methylene chains attached to aromatic *** will leave the kerogen matrix with the breakage of relatively weaker CeC bonds at β-sites from aromatic rings at medium *** contrast,aliphatic carbons of the HD-K are dominated by long aliphatic *** temperature is necessary to break other stronger CeC to form shale oil and gaseous species,which appears to make the oil accumulation conversion of BLK-R exceed that of HD-R at 450–510℃.

关键词： Oil shale Pyrolysis Kerogen Organic carbon Thermal bitumen Shale oil

Intensity Estimation of Extreme Meteorological and Hydrological Factors Induced by Tropical Cyclones Affecting Hong Kong

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Journal of Ocean University of China 2023年第2期22卷 313-323页

作者： tao Shanshan HUA Yunfei DONG sheng College of Engineering Ocean University of ChinaQingdao 266100China

Hong Kong is often affected by tropical *** Hong Kong observatory issues warning signals based on the impact of tropical cyclones on the *** joint frequency analysis of tropical cyclones in Hong Kong can provide a scientific basis for disaster reduction and prevention and post-disaster reconstruction of tropical ***,the maximum hourly mean wind speed(W),warning signal duration(D),maximum sea level(L),and total rainfall(R)of each tropical cyclone that affected Hong Kong from 1985 to 2019 are selected and fitted using the Gumbel,Weibull,Pearson type 3,and lognormal ***,bivariate copula functions,such as the Clayton,Frank,Gumbel-Hougaard,and Gaussian copulas,are applied to construct the joint probability models of W,D,L,and R,*** joint return periods of W and D and those of L and R are defined as the meteorological and hydrological intensities of tropical cyclones,*** results show that the joint return periods are good indicators of the comprehensive effect of the meteorological and hydrological intensities of tropical *** necessary correlation between meteorological and hydrological intensities of tropical cyclones *** meteorological and hydrological intensities of tropical cyclones show an upward trend in recent years.

关键词： tropical cyclone warning signal meteorological intensity hydrological intensity copula

Landsat Image-Based Spatiotemporal Variation Analysis of Erosion and Deposition off the Qingshuigou of the Yellow River Delta from 1984 to 2021

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Journal of Ocean University of China 2024年第5期23卷 1173-1184页

作者： DONG sheng LI Songda tao Shanshan College of Engineering Ocean University of ChinaQingdao 266404China

Owing to climate change and human activity,the Qingshuigou of the Yellow River Delta(YRD)has undergone dynamic changes in erosion and ***,studying these changes is important to ensure ecological protection and sustainable *** this study,the trend of erosion-deposition evolution in the Qingshuigou was investigated based on 38 coastline phases extracted from Landsat series images of the YRD at one-year intervals from 1984 to *** periodicity of the scouring and deposition evolution was also analyzed using wavelet *** showed that the total area of the Qingshuigou was affected by deposition and erosion and that the fluctuation first increased and then *** total area reached a maximum in *** depositional area first increased and then decreased,whereas the overall erosion area *** and erosion areas showed periodic changes to some extent;however,the periodic signal intensity ***,factors including channel morphological evolution and variations in water and sediment discharge affect the spatiotemporal dynamics of erosion and deposition *** application of nonconsistency tests finally revealed that deposition area and flushing magnitude exhibited non-stationarities,which are potentially attributed to impacts from climatic change drivers.

关键词： Yellow River Delta coastline erosion and deposition remote sensing wavelet analysis

Hazard risk assessment of tropical cyclones based on joint probability theory

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Acta Oceanologica Sinica 2023年第6期42卷 89-99页

作者： Shanshan tao Yunfei Hua sheng Dong College of Engineering Ocean University of ChinaQingdao 266100China

The main hazard-causing factors of tropical cyclones are strong wind,heavy rainfall,and storm *** of the hazard-causing degree of a tropical cyclone requires a joint intensity analysis of these hazard-causing *** to the maximum hourly mean wind speed,total rainfall,and maximum tide level at various observation stations in Hong Kong during these tropical cyclones,three hazard-causing indices for tropical cyclones are introduced:the strong-wind index(VI),total-rainfall index(RI),and tide-level index(LI).Through a joint probability analysis of VI,RI,and LI for a tropical cyclone affecting Hong Kong,the joint return period is calculated to evaluate its joint hazard-causing intensity.A limit state function of Hong Kong’s resistance to tropical cyclones is developed and used to evaluate the regional risk of tropical cyclones affecting Hong *** results indicate that the joint return period of VI,RI,and LI can reflect the joint hazard-causing intensity of strong wind,heavy rain,and storm surge caused by tropical cyclones;if the overall design return periods of the regional structures decrease,the regional ability to defend against tropical cyclone disasters is degraded.

关键词： tropical cyclone Hong Kong trivariate copulas hazard-causing factors regional risk

Flexible Bio-tensegrity Manipulator with Multi-degree of Freedom and Variable Structure

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Chinese Journal of Mechanical Engineering 2020年第1期33卷 83-93页

作者： Dunwen Wei tao Gao Xiaojuan mo Ruru Xi Cong Zhou School of Mechanical and Electrical Engineering University of Electronic Science and Technology of ChinaChengdu 611731China School of Mechanical Engineering Northwestern Polytechnical UniversityXi’an 710072China School of Mechanical Engineering Hangzhou Dianzi UniversityHangzhou 310018China

Conventional manipulators with rigid structures and sti ness actuators have poor flexibility,limited obstacle avoidance capability,and constrained *** developed flexible or soft manipulators in recent years have the characteristics of infinite degrees of freedom,high flexibility,environmental adaptability,and extended manipulation ***,these existing manipulators still cannot achieve the shrinking motion and independent control of specified segments like the animals,which hinders their *** this paper,a flexible bio-tensegrity manipulator,inspired by the longitudinal and transversal muscles of octopus tentacles,was proposed to mimic the shrinking behavior and achieve the variable motion patterns of each *** proposed manipulator uses the elastic spring as the backbone,which is driven by four cables and has one variable structure mechanism in each segment to achieve the independent control of each *** variable structure mechanism innovatively contains seven lock-release states to independently control the bending and shrinking motion of each *** the kinematic modeling and analysis,one prototype of such bionic flexible manipulator was built and the open-loop control method was *** proof-of-concept experiments,including the shrinking motion,bending motion,and variable structure motion,were carried out by controlling the length of four cables and changing the lock-release states of the variable structure mechanism,which validate the feasibility and validity of our proposed ***,the experimental results show the flexible manipulator can accomplish the bending and shrinking motion with the relative error less than 6.8%through the simple independent control of each segment using the variable structure *** proposed manipulator has the features of controllable degree-of-freedom in each segment,which extend their environmental adaptability,and manipulation capability.

关键词： Bio-tensegrity Cable-driven actuation Multi-degree-of-freedom(Multi-DoF) Flexible manipulator Variable structure mechanism

A LEVEL SET METHOD FOR SIMULATION OF RISING BUBBLE

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Journal of Hydrodynamics 2004年第4期16卷 379-385页

作者： HUANGJun-tao ZHANGHui-sheng DepartmentofMechanicsandEngineeringSciences FudanUniversityShanghai200433China

A level set method, the TVD scheme of second-order upwind procedure coupledwith flux-limiter, and SIMPLE algorithm were incorporated to simulate the flow and interfacialmotion of immiscible two-fluids with large density ratio and viscosity ratios, large topologydistortion and surface tension. As a numerical example axi-symmetric rising bubbles wereinvestigated. It is found that the method is numerically stable and has good convergence propertyand the results are in good agreement with other works.

关键词： level set method high-resolution scheme SIMPLE algorithm rising bubble

Hard magnetization direction and its relation with magnetic permeability of highly grain-oriented electrical steel

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International Journal of Minerals,Metallurgy and Materials 2014年第11期21卷 1077-1082页

作者： Hao Wang Chang-sheng Li tao Zhu State Key Laboratory of Rolling and Automation Northeastern University

The magnetic properties of highly grain-oriented electrical steel vary along different directions. In order to investigate these properties, standard Epstein samples were cut at different angles to the rolling direction. The hard magnetization direction was found at an angle of 60° to the rolling direction. To compare the measured and fitting curves, when the magnetic field intensity is higher than 7000 A/m, it is appropriate to simulate the relation of magnetic permeability and magnetization angle using the conventional elliptical model. When the magnetic field intensity is less than 3000 A/m, parabolic fitting models should be used; but when the magnetic field intensity is between 3000 and 7000 A/m, hybrid models with high accuracy, as proposed in this paper, should be applied. Piecewise relation models of magnetic permeability and magnetization angle are significant for improving the accuracy of electromagnetic engineering calculations of electrical steel, and these new models could be applied in further industrial applications.

关键词： electrical steel magnetization direction magnetic permeability mathematical models

Power-law statistics of synchronous transition in inhibitory neuronal networks

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Chinese Physics B 2022年第8期31卷 310-316页

作者： Lei tao sheng-Jun Wang School of Physics and Information Technology Shaanxi Normal UniversityXi’an 710119China

We investigate the relationship between the synchronous transition and the power law behavior in spiking networks which are composed of inhibitory neurons and balanced by dc current. In the region of the synchronous transition, the avalanche size and duration distribution obey a power law distribution. We demonstrate the robustness of the power law for event sizes at different parameters and multiple time scales. Importantly, the exponent of the event size and duration distribution can satisfy the critical scaling relation. By changing the network structure parameters in the parameter region of transition, quasicriticality is observed, that is, critical exponents depart away from the criticality while still hold approximately to a dynamical scaling relation. The results suggest that power law statistics can emerge in networks composed of inhibitory neurons when the networks are balanced by external driving signal.

关键词： power-law inhibitory synchronization neuronal networks