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Influence of baryons on the spatial distribution of matter:higher order correlation functions

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Research in Astronomy and Astrophysics 2012年第12期12卷 1603-1612页

作者： Xiao-jun Zhu jun pan Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China National Astronomical Observatories Chinese Academy of Sciences B eijing 100012 China

Physical processes involving baryons could leave a non-negligible imprint on the distribution of cosmic matter.A series of simulated data sets at high resolution with identical initial conditions are employed for count-in-cell analysis,including one N-body pure dark matter run,one with only adiabatic gas and one with dissipative *** and higher order cumulants Sn of dark matter and gas are *** is found that physical processes with baryons mainly affect distributions of dark matter at scales less than 1 h-1 *** comparison with the pure dark matter run,adiabatic processes alone strengthen the variance of dark matter by～10%at a scale of 0.1 h-1 Mpc,while the Sn parameters of dark matter only mildly deviate by a few *** dissipative gas run does not differ much from the adiabatic run in terms of variance for dark matter,but renders significantly different Sn parameters describing the dark matter,bringing about a more than 10%enhancement to S3 at 0.1 h-1 Mpc and z=0 and being even larger at a higher *** patterns of gas in two hydrodynamical simulations are quite *** of gas at z=0 decreases by～30%in the adiabatic simulation but by～60%in the nonadiabatic simulation at 0.1 h-1 *** attenuation is weaker at larger scales but is still obvious at～10 h-1 *** parameters of gas are biased upward at scales 〈～4 h-1 Mpc,and dissipative processes show an～84%promotion at z=0 to S3 at 0.1 h-1 Mpc in contrast with the～7%change in the adiabatic *** segregation in clustering between gas and dark matter could have dramatic implications on modeling distributions of galaxies and relevant cosmological applications demanding fine details of matter distribution in a strongly nonlinear regime.

关键词： cosmology:dark matter-large-scale structure of universe-methods: statistical

Improved seeded region growing for detection of water bodies in aerial images

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Geo-Spatial Information Science 2016年第1期19卷 1-8页

作者： jun pan Mi Wang State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan University129 Luoyu RoadWuhan 430079China Collaborative Innovation Center for Geospatial Technology Wuhan University129 Luoyu RoadWuhan 430079China

In aerial images,near-specular and specular reflection often appear in water *** often lead to irregular brightness or color changes in water bodies and even produce hot spots,harmful to radiometric ***,water bodies must be eliminated when calculating radiometric differences during radiometric normalization of aerial *** this paper,a simple method to detect water bodies in aerial images based on texture features is presented,an improved seeded region growing(SRG)method.A texture feature is calculated using the relative standard deviation index(RSDI)and a coarse-to-fine procedure is *** proposed method includes a multiple partition strategy and a refinement in gradient image that improves the reliability and accuracy of water body *** fusing water bodies detected in multiple images,hot spots in these water bodies are also *** validate the feasibility and effectiveness of the proposed method.

关键词： aerial images water specular reflection hot spots radiometric normalization

Reliability and Availability Models of Belt Drive Systems Considering Failure Dependence

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Chinese Journal of Mechanical Engineering 2019年第2期32卷 133-144页

作者： Peng Gao Liyang Xie jun pan School of Mechanical Engineering Liaoning Shihua University School of Mechanical Engineering and Automation Zhejiang Sci-Tech University School of Mechanical Engineering and Automation Northeastern University

Conventional reliability models of belt drive systems in the failure mode of fatigue are mainly based on the static stress strength interference model and its extended models, which cannot consider dynamic factors in the operational duration and be used for further availability analysis. In this paper, time-dependent reliability models, failure rate models and availability models of belt drive systems are developed based on the system dynamic equations with the dynamic stress and the material property degradation taken into account. In the proposed models, dynamic failure dependence and imperfect maintenance are taken into consideration. Furthermore, the issue of time scale inconsistency between system failure rate and system availability is proposed and addressed in the proposed system availability models. Besides, Monte Carlo simulations are carried out to validate the established models. The results from the proposed models and those from the Monte Carlo simulations show a consistency. Furthermore, the case studies show that the failure dependence, imperfect maintenance and the time scale inconsistency have significant influences on system availability. The independence assumption about the belt drive systems results in underestimations of both reliability and availability. Moreover, the neglect of the time scale inconsistency causes the underestimate of the system availability. Meanwhile, these influences show obvious time-dependent characteristics.

关键词： Availability Reliability Belt drive Failure dependence Time scale inconsistency

Note on Redshift Distortion in Fourier Space

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Chinese Journal of Astronomy and Astrophysics 2007年第1期7卷 51-62页

作者： Yan-Chuan Cai jun pan Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

We explore features of redshift distortion in Fourier analysis of N-body simulations. The phases of the Fourier modes of dark matter density fluctuation are generally shifted by the peculiar motion along the line of sight, the induced phase shift is stochastic and has a probability distribution function （PDF） that is symmetric about the peak at zero shift and whose exact shape depends on the wave vector, except on very large scales where phases are invariant by linear perturbation theory. Analysis of the phase shifts motivates our phenomenological models for the bispectrum in redshift space. Comparison with simulations shows that our toy models are very successful in modeling bispectrum of equilateral and isosceles trian- gles at large scales. In the second part we compare the monopole of the power spectrum and bispectrum in the radial and plane-parallel distortion to test the plane-parallel approximation. We confirm the results of Scoccimarro that difference of power spectrum is at the level of 10%, and, in the reduced bispectrum, the difference is as small as a few percent. However, on the plane perpendicular to the line of sight of kz = 0, the difference in power spectrum be- tween the radial and plane-parallel approximation can be more than - 10%, and even worse on very small scales. Such difference is prominent for bispectrum, especially for configura- tions of tilted triangles. Non-Ganssian signals under the radial distortion on small scales are systematically biased downside than are in the plane-parallel approximation, with amplitudes depending on the opening angle of the sample point to the observer. This observation gives warning to the practice of using the power spectrum and bispectrum measured on the kz = 0 plane as estimates of the real space statistics.

关键词： cosmology theory-large-scale structure of universe-methods statistical

Effect of Wave Nonlinearity on the Instantaneous Seabed Liquefaction

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China Ocean Engineering 2024年第1期38卷 93-103页

作者： WANG Zhao-jun SUI Ti-ti ZHANG Chi pan jun-ning Key Laboratory of Port Waterway and Sedimentation Engineering of the Ministry of TransportNanjing Hydraulic Research InstituteNanjing 210024China Key Laboratory of Coastal Disaster and Protection(Hohai University) Ministry of EducationNanjing 210098China The National Key Laboratory of Water Disaster Prevention Nanjing 210098China

The nonlinear variation of wave is commonly seen in nearshore area,and the resulting seabed response and liquefaction are of high concern to coastal *** this study,an analytical formula considering the nonlinear wave skewness and asymmetry is adopted to provide wave pressure on the seabed *** liquefaction depth attenuation coefficient and width growth coefficient are defined to quantitatively characterize the nonlinear effect of wave on seabed *** on the 2D full dynamic model of wave-induced seabed response,a detailed parametric study is carried out in order to evaluate the influence of the nonlinear variation of wave loadings on seabed ***,new empirical prediction formulas are proposed to fast predict the maximum liquefaction under nonlinear *** indicate that(1)Due to the influence of wave nonlinearity,the vertical transmission of negative pore water pressure in the seabed is hindered,and therefore,the amplitude decreases significantly.(2)In general,with the increase of wave nonlinearity,the liquefaction depth of seabed decreases *** under asymmetric and skewed wave loading,the attenuation of maximum seabed liquefaction depth is the most significant among all the nonlinear wave ***,highly skewed wave can cause the liquefaction depth of seabed greater than that under linear wave.(3)The asymmetry of wave pressure leads to the increase of liquefaction width,whereas the influence of skewedness is not significant.(4)Compared with the nonlinear waveform,seabed liquefaction is more sensitive to the variation of nonlinear degree of wave loading.

关键词： nonlinear wave seabed response seabed liquefaction numerical simulation liquefaction prediction

Shape-dependent hydrogen generation performance of Pt Pd bimetallic co-catalyst coupled with C_(3)N_(4)photocatalyst

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Rare Metals 2021年第12期40卷 3554-3560页

作者： Wen-Wen Liu jun pan Ren-Fu Peng College of Physical Science and Engineering Yichun UniversityYichun 336000China State Key Laboratory for Powder Metallurgy Central South UniversityChangsha 410083China

The shape-dependent performance of metal cocatalysts in photocatalysis has been one of the research focal points in recent *** this study,Pt Pd/C_(3)N_(4)hybrid structures were constructed to reveal the effect of the shape of the Pt Pd bimetallic co-catalyst on the performance of photocatalytic hydrogen *** Pd nanocubes(NCs)and nanotetrahedrons(NTs)were sequentially deposited in situ on the surface of C_(3)N_(4)nanosheets,establishing a strong contact interface to ensure the smooth transfer of photoinduced ***-visible(UV-Vis)diffuse reflectance spectroscopy and photoelectrochemical experiments revealed that the Pt Pd NCs/C_(3)N_(4)photocatalyst had comparable light absorption ability and equivalent carrier separation and transfer efficiency in comparison with the Pt Pd NTs/C_(3)N_(4)photocatalyst,which excluded the influence of these factors on shape-dependent *** photocatalytic hydrogen generation results indicate that the hydrogen generation rate of the Pt Pd NCs/C_(3)N_(4)photocatalyst is 1.33 times higher than that of the Pt Pd NTs/C_(3)N_(4)photocatalyst,demonstrating that the cubic Pt Pd bimetallic co-catalyst is more conducive to hydrogen generation compared to the tetrahedral Pt Pd bimetallic co-catalyst.

关键词： PtPd bimetallic co-catalyst C_(3)N_(4) Shape Hydrogen generation Photocatalyst

Corner Transition Toolpath Generation Based on Velocity-Blending Algorithm for Glass Edge Grinding

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Chinese Journal of Mechanical Engineering 2019年第5期32卷 50-58页

作者： Kun Ren Yujia pan Danyan Jiang jun pan Wenhua Chen Xuxiao Hu College of Mechanical Engineering and Automation Zhejiang Sci-Tech University

Sharp corners usually are used on glass contours to meet the highly increasing demand for personalized products,but they result in a broken wheel center toolpath in edge *** ensure that the whole wheel center toolpath is of G1 continuity and that the grinding depth is controllable at the corners,a transition toolpath generation method based on a velocity-blending algorithm is *** the grinding depth into consideration,the sharp-corner grinding process is planned,and a velocity-blending algorithm is *** the constraints,such as traverse displacement and grinding depth,the sharp-corner transition toolpath is generated with a three-phase motion arrangement and with confirmations of the acceleration/deceleration positions.A piece of glass with three sharp corners is ground on a three-axis numerical-control glass grinding *** experimental results demonstrate that the proposed algorithm can protect the sharp corners from breakage efficiently and achieve satisfactory shape *** research proposed a toolpath generation method based on a velocity-blending algorithm for the manufacturing of personalized glass products,which generates the transition toolpath as needed around a sharp corner in real time.

关键词： Glass edge grinding Toolpath planning Velocity blending Grinding depth control

From Proton Conductive Nanowires to Nanofuel Cells： A Powerful Candidate for Generating Electricity for Self-Powered Nanosystems

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Nano Research 2011年第11期4卷 1099-1109页

作者： Caofeng pan jun Luo Jing Zhu Beijing National Center for Electron Microscopy Laboratory of Advanced Materials State Key Laboratory of New Ceramics and FineProcessing Department of Material Science and Engineering Tsinghua University Beijing 100084 China

The likely goal of nanotectulology is the integration of individual nanodevices into a nanosystem, which includes the nanodevice（s）, power harvesting unit, data processing logic system, and possibly wireless communication unit. A nanosystem requires a nanoscale power source to make the entire package extremely small and high performance. The nanofuel and nanobiofuel cells developed here represent a new self-powering approach in nanotechnology, and their power output is high enough to drive nanodevices for performing self-powered sensing. This study shows the feasibility of building self-powered nanosystems for biological sciences, environmental monitoring, defense technology and even personal electronics.

关键词： Nation nanowire nanofuel cell nanobiofuel cell self-powered nanosystem

Combined heuristics for determining order quantity under time-varying demands

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Journal of Systems Engineering and Electronics 2008年第1期19卷 99-111页

作者： Tang Jiafu pan Zhendong Gong jun Liu Shixin Dept. of Systems Engineering Key Lab of Integrated Automation of Process Industry of MOE Northeastern Univ. Shenyang 110004 P. R. China

The time-varying demands for a certain period are often assumed to be less than the basic economic order quantity （EOQ） so that total replenishment quantity rather than economic order quantity is normally considered by most of the heuristics. This acticle focuses on a combined heuristics method for determining order quantity under generalized time-varying demands. The independent policy （IP）, abnormal independent policy （AIP） and dependent policies are studied and compared. Using the concepts of normal/abnormal periods and the properties of dependent policies, a dependent policy-based heuristics （DPH） is proposed for solving the order quantity problems with a kind of time-varying demands pattern under which the first period is normal. By merging the Silver-Meal （S-M） heuristics and the dependent policy-based heuristics （DPH）, a combined heuristics （DPH/S-M） is developed for solving order quantity problems with generalized time-varying demands. The experimentation shows that （1） for the problem with one normal period, no matter which position the normal period stands, the DPH/S-M could not guarantee better than the S-M heuristics, however it is superior to the S-M heuristics in the case that the demands in the abnormal periods are in descending order, and （2） The DPH/S-M is superior to the S-M heuristics for problems with more than one normal period, and the more the number of normal periods, the greater the improvements.

关键词： heuristics EOQ time-varying demands inventory management