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Estimating the mirror seeing for a large optical telescope with a numerical method

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Research in Astronomy and Astrophysics 2018年第5期18卷 131-136页

It is widely accepted that mirror seeing is caused by turbulent fluctuations in the index of air refraction in the vicinity of a telescope mirror. Computational Fluid Dynamics（CFD） is a useful tool to evaluate the effects of mirror seeing. In this paper, we present a numerical method to estimate the mirror seeing for a large optical telescope（～ 4 m） in cases of natural convection with the ANSYS ICEPAK software. We get the FWHM of the image for different inclination angles（i） of the mirror and different temperature differences（△T） between the mirror and ambient air. Our results show that the mirror seeing depends very weakly on i, which agrees with observational data from the Canada-FranceHawaii Telescope. The numerical model can be used to estimate mirror seeing in the case of natural convection although with some limitations. We can determine △T for thermal control of the primary mirror according to the simulation, empirical data and site seeing.

关键词： astronomical instrumentation - methods numerical- telescopes

Feedback of Active Galactic Nuclei in Seyfert 2 Galaxies

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Chinese Journal of Astronomy and Astrophysics 2008年第5期8卷 537-546页

作者： en-peng zhang Wei-Hao Bian Chen Hu Wei-Ming Mao A-Li Luo Yong-Heng Zhao National Astronomical Observatory Chinese Academy of Sciences Beijing 100012 China Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing 210097 China Institute of High energy Physics Chinese Academy of Sciences Beijing 100049 China

It is well accepted that feedback from active galactic nuclei （AGNs） plays an important role in the coevolution of the supermassive black hole （SMBH） and its host galaxy, but the concrete mechanism of feedback remains unclear. A considerable body of evidence suggests that AGN feedback suppresses star formation in the host galaxy. We assemble a sample of Seyfert 2 galaxies with recent observational data of compact nuclear starbursts and estimate the gas surface density as a function of column density to illuminate the relation between feedback and AGN properties. Although there are some uncertainties, our data still imply the deviation from the star formation law （Kennicutt-Schmidt law）. Further, they indicate that：（1） Feedback correlates with the Eddington ratio, rather than with the mass of SMBH, as a result of decreasing star formation efficiency. （2） The SMBH and the torus are probably undergoing coevolution. Conclusions presented here can be refined through future high resolution CO or HCN observations.

关键词： galaxies active - galaxies Seyfert- feedback

Electronic origin of structural degradation in Li-rich transition metal oxides:The case of Li_(2)MnO_(3)and Li_(2)RuO_(3)

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Journal of Semiconductors 2024年第4期45卷 82-86页

作者： peng zhang Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics andOp toelec-tronic EngineeringShenzhen UniversityShenzhen 518060China

Li_(2)MnO_(3)and Li_(2)RuO_(3)represent two prototype Li-rich transition metal(TM)oxides as high-capacity cathodes for Li-ion batteries,which have similar crystal structures but show quite different cycling ***,based on the first-princi-ples calculations,we systematically studied the electronic structures and defect properties of these two Li-rich cathodes,in order to get more understanding on the structural degradation mechanism in Li-rich TM *** calculations indicated that the structural and cycling stability of Li_(2)MnO_(3)and Li_(2)RuO_(3)depend closely on their electronic structures,especially the energy of their highest occupied electronic states(HOS),as it largely determines the defect properties of these *** Li_(2)MnO_(3)with low-energy HOS,we found that,due to the defect charge transfer mechanism,various defects can form spontaneously in its host structure as Li ions are extracted upon delithiation,which seriously deteriorates its structural and cycling *** for Li_(2)RuO_(3),on the other hand,we identified that the high-energy HOS prevents it from the defect formation upon delithi-ation and thus preserve its cycling *** studies thus illustrated an electronic origin of the structural degradation in Li-rich TM oxides and implied that it is possible to improve their cycling performances by carefully adjusting their TM compo-nents.

关键词： defects Li-ion batteries first-principles calculations

Accelerated water harvesting from vapor via a bio-inspired hydrogel pattern

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National Science Review 2024年第3期11卷 48-49页

作者： Lianbin zhang peng Wang State Key Laboratory of Material Processing and Die&Mould Technology Key Laboratory of Materials Chemistry for Energy Conversion and Storage of Ministry of Education School of Chemistry and Chemical Engineering Huazhong University of Science and Technology(HUST) School of environmental Science and engineering Sun Yat-sen University

Water and energy sustainability are integral parts of resource sustainability of the world. Due to water molecules' superior capability of serving as both hydrogenbond donor and acceptor, phase change of water, especially between liquid and vapor, underpins global water cycles,facilitates energy transformation and transfer, and thus helps shape the unique local weather and global climate patterns.

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Stabilization and Blow-up in an Infinite Memory Wave Equation with Logarithmic Nonlinearity and Acoustic Boundary Conditions

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Journal of Systems Science & Complexity 2024年第4期37卷 1368-1391页

作者： peng Qingqing zhang Zhifei School of Mathematics and Statistics Huazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory of engineering Modeling and Scientific Computing Huazhong University of Science and TechnologyWuhan 430074China

In this paper,the authors consider the stabilization and blow up of the wave equation with infinite memory,logarithmic nonlinearity and acoustic boundary *** authors discuss the existence of global solutions for the initial energy less than the depth of the potential well and investigate the energy decay estimates by introducing a Lyapunov ***,the authors establish the finite time blow up results of solutions and give the blow up time with upper bounded initial energy.

关键词： Acoustic boundary condition finite time blow-up general decay infinite memory logarithmic nonlinearity

Depth-Guided Vision Transformer With Normalizing Flows for Monocular 3D Object Detection

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 673-689页

作者： Cong Pan Junran peng Zhaoxiang zhang the Center for Research on Intelligent Perception and Computing(CRIPAC) National Laboratory of Pattern Recognition(NLPR)Institute of AutomationChinese Academy of Sciences(CASIA)Beijing 100190 the School of Future Technology University of Chinese Academy of Sciences(UCAS)Beijing 100049China the Huawei Inc. Beijing 100085China IEEE the Institute of Automation Chinese Academy of Sciences(CASIA)Beijing 100190 the University of Chinese Academy of Sciences(UCAS) Beijing 100049 the Centre for Artificial Intelligence and Robotics Hong Kong Institute of Science&Innovation Chinese Academy of Sciences(HKISI CAS)Hong Kong 999077China

Monocular 3D object detection is challenging due to the lack of accurate depth *** methods estimate the pixel-wise depth maps from off-the-shelf depth estimators and then use them as an additional input to augment the RGB ***-based methods attempt to convert estimated depth maps to pseudo-LiDAR and then use LiDAR-based object detectors or focus on the perspective of image and depth fusion ***,they demonstrate limited performance and efficiency as a result of depth inaccuracy and complex fusion mode with *** from these approaches,our proposed depth-guided vision transformer with a normalizing flows(NF-DVT)network uses normalizing flows to build priors in depth maps to achieve more accurate depth *** we develop a novel Swin-Transformer-based backbone with a fusion module to process RGB image patches and depth map patches with two separate branches and fuse them using cross-attention to exchange information with each ***,with the help of pixel-wise relative depth values in depth maps,we develop new relative position embeddings in the cross-attention mechanism to capture more accurate sequence ordering of input *** method is the first Swin-Transformer-based backbone architecture for monocular 3D object *** experimental results on the KITTI and the challenging Waymo Open datasets show the effectiveness of our proposed method and superior performance over previous counterparts.

关键词： Monocular 3D object detection normalizing flows Swin Transformer

The medium-temperature dependence of jet transport coefficient in high-energy nucleus-nucleus collisions

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Nuclear Science and Techniques 2024年第7期35卷 173-191页

作者： Man Xie Qing-Fei Han en-Ke Wang Ben-Wei zhang Han-Zhong zhang Key Laboratory of Atomic and Subatomic Structure and Quantum Control(MOE) Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of MatterInstitute of Quantum Matter South China Normal UniversityGuangzhou510006China Guangdong-Hong Kong Joint Laboratory of Quantum Matter Guangdong Provincial Key Laboratory of Nuclear ScienceSouthern Nuclear Science Computing CenterSouth China Normal UniversityGuangzhou 510006China Key Laboratory of Quark and Lepton Physics(MOE)and Institute of Particle Physics Central China Normal UniversityWuhan430079China

The medium-temperature T dependence of the jet transport coefficient̂q was studied via the nuclear modification factor RAA(p_(T))and elliptical flow parameter v_(2)(p_(T))for large transverse momentum p_(T) hadrons in high-energy nucleus-nucleus *** a next-to-leading-order perturbative QCD parton model for hard scatterings with modified fragmentation functions due to jet quenching controlled by q,we check the suppression and azimuthal anisotropy for large p_(T) hadrons,and extract q by global fits to RAA(pT)and v_(2)(pT)data in A+A collisions at RHIC and LHC,*** numerical results from the best fits show that q∕T^(3) goes down with local medium-temperature T in the parton jet *** with the case of a constant q∕T^(3),the going-down T dependence of q∕T^(3) makes a hard parton jet to lose more energy near T_(c) and therefore strengthens the azimuthal anisotropy for large pT *** a result,v_(2)(p_(T))for large pT hadrons was enhanced by approximately 10%to better fit the data at RHIC/*** the first-order phase transition from QGP to the hadron phase and the additional energy loss in the hadron phase,v_(2)(p_(T))is again enhanced by 5-10%at RHIC/LHC.

关键词： Jet quenching Jet transport parameter Hadron suppression Elliptic flow coefficient energy loss asymmetry

Experimental and numerical simulation study on the erosion behavior of the elbow of gathering pipeline in shale gas field

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Petroleum Science 2024年第2期21卷 1257-1274页

作者： en-Bin Liu Shen Huang Ding-Chao Tian Lai-Min Shi Shan-Bi peng He Zheng Petroleum engineering School Southwest Petroleum UniversityChengdu 610500SichuanChina Chongqing Natural Gas Sales Center Natural Gas BranchSinopecChongqing400023China Zhejiang Zheneng Natural Gas Operation Co. Ltd.Hangzhou 310000ZhejiangChina School of Civil engineering and Architecture Southwest Petroleum UniversityChengdu 610500SichuanChina Louisiana Tech Univ Trenchless Technol Ctr599 Dan Reneau DrRustonLA71270USA Southwest Oil and Gas Field Branch Natural Gas Research Institute Chengdu 610213SichuanChina

During the production period of shale gas, proppant particles and rock debris are produced together,which will seriously erode the elbows of gathering pipelines. In response to this problem, this paper takes the elbow of the gathering pipeline in the Changning Shale Gas Field as an example to test the erosion rate and material removal mechanism of the test piece at different angles of the elbow through experiments and compares the four erosion models with the experimental results. Through analysis, it is found that the best prediction model for quartz sand-carbon steel erosion is the Oka model. Based on the Oka model, FLUenT software was used to simulate and analyze the law of erosion of the elbow of the gas gathering pipeline under different gas flow velocities, gas gathering pressure, particle size, length of L1,and bending directions of the elbow. And a spiral pipeline structure is proposed to reduce the erosion rate of the elbow under the same working conditions. The results show that this structure can reduce erosion by 34%.

关键词： Shale gas Gas gathering pipeline Elbow Erosion CFD

Predictive value of preoperative routine examination for the prognosis of patients with pT2N0M0 or pT3N0M0 colorectal cancer

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World Journal of Gastrointestinal Oncology 2024年第6期16卷 2429-2438页

作者： peng-Fei Jing Jin Chen en-Da Yu Chao-Yu Miao Department of Colorectal Surgery Changhai HospitalSecond Military Medical University/Naval Medical UniversityShanghai 200433China Department of endocrinology and Metabolism Changhai HospitalSecond Military Medical University/Naval Medical UniversityShanghai 200433China Department of Pharmacology Second Military Medical University/Naval Medical UniversityShanghai 200433China

BACKGROUND In recent years,the incidence of colorectal cancer(CRC)has been *** the popularization of endoscopic technology,a number of early CRC has been ***,despite current treatment methods,some patients with early CRC still experience postoperative recurrence and *** To search for indicators associated with early CRC recurrence and metastasis to identify high-risk *** A total of 513 patients with pT2N0M0 or pT3N0M0 CRC were retrospectively enrolled in this *** of blood routine test,liver and kidney function tests and tumor markers were collected before *** were followed up through disease-specific database and telephone *** recurrence,metastasis or death were used as the end point of study to find the risk factors and predictive value related to early CRC recurrence and *** We comprehensively compared the predictive value of preoperative blood routine,blood biochemistry and tumor markers for disease-free survival(DFS)and overall survival(OS)of *** multivariate analysis demonstrated that low platelet count was significantly associated with poor DFS[hazard ratio(HR)=0.995,95% confidence interval(CI):0.991-0.999,P=0.015],while serum carcinoembryonic antigen(CEA)level(HR=1.008,95%CI:1.001-1.016,P=0.027)and serum total cholesterol level(HR=1.538,95%CI:1.026-2.305,P=0.037)were independent risk factors for *** cutoff value of serum CEA level for predicting OS was 2.74 ng/*** the OS of CRC patients with serum CEA higher than the cutoff value was worse than those with lower CEA level,the difference between the two groups was not statistically significant(P=0.075).CONCLUSION For patients with T2N0M0 or T3N0M0 CRC,preoperative platelet count was a protective factor for DFS,while serum CEA level was an independent risk factor for *** that these measures are easier to detect and more acceptable to patients,they may have broader applications.

关键词： Colorectal cancer Platelet count Serum carcinoembryonic antigen Total cholesterol level Overall survival Disease-free survival